Patent Application
20180217162
The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Dec. 4, 2017, is named P12557-03_SL.txt and is 764,203 bytes in size.
The present invention relates to the field of myocardial injury. More specifically, the present invention provides methods and compositions useful in the diagnosis, prognosis and/or assessment of myocardial injury.
Cardiac injury is defined as the disruption of normal myocyte membrane integrity results in releasing of the myocyte cellular components into extracellular space including blood caused by insults to the heart. The cellular components include cytosolic and structure proteins such as troponin, creatine kinase, myoglobin and others. Cardiac injury is caused by ischemic or non-ischemia insults to the heart. The non-ischemic insults to the heart can be caused by trauma, toxin and viral infection. The ischemic (lack of oxygen) insults to the heart can be caused by reduced the blood flow to the heart and cause myocardium injury (reversible and non-reversible). Physiologically, the decreased blood flow is caused by various abnormities and damages to the arterial, such as building up of atherosclerotic plaques in the arteries, narrowing or blockage of arteries in the heart, damage and/or rapture of heart arteries from atherosclerosis and thrombosis. When the body cannot pump enough oxygen-rich blood to the rest of the body, chest pain (angina) or a heart attack occurs (myocardium infarction). Acute Coronary Syndrome (ACS) refers to a group of heterogeneous coronary diseases that result from ischemic insults to the heart with different pathophysiology, clinical presentation, and risk for adverse events. ACS is manifestation of cardiac injury from ischemic, stable angina, unstable angina to myocardial infarction.
ASC, also known as myocardial (cardiac) injury or myocardial damage, represents about 20% of all deaths globally. The direct, treatment-related and management costs, as well as indirect, social and economic costs for ACS are estimated to be more than 150 billion. The proper diagnosis of ACS requires reliable and accurate biomarker tests. Currently, blood tests for the cardiac specific isoform of troponins (TnI or TnT, respectively) are generally used for the diagnosis of acute myocardial infarction. Creatine kinase (CK)-MB and myoglobin are considered to be less specific for cardiac injury.
It is important that ACS symptoms are recognized early and accurately, so patients can receive immediate and adequate medical attention. This will contribute to significantly reduced morbidity and mortality from ACS. At an earlier time point of MI in which the heart is in ischemia but is not yet in necrosis, it is this diagnosis of cardiac ischemia in the absence of necrosis that cannot currently be made with accuracy. It would be useful to be able to identify subjects in this diagnostic window (having non-necrotic ischemia). Such a diagnostic tool would be of great value for triage in the emergency department. It would allow for earlier intervention, including earlier perfusion, to allow increased salvage of the injured myocardium; and it would prevent unnecessary admittance to the hospital of patients with non-cardiac chest pain. Furthermore, such an assay could delay therapy in subjects who do not exhibit diagnostic electrocardiographic (ECG) changes, and could help to improve the accuracy of current provocative tests for ischemia, such as exercise stress testing. The sooner intervention can be carried out the less cardiac damage will occur. Less damage is correlated to increase long term survival.
Therefore, there is an urgent need in the art for a rapid, sensitive and specific, diagnostic assay for ischemic myocardium injury in ACS patients. Such assays also allow an early, accurate and differential diagnosis of MI in emergency room (ER), differentiate the types of ACS and identify individuals at risk for delayed adverse events.
The present invention is based, at least in part, on the identification and usage of diagnosis and/or prognosis cardiac injury markers for ACS including ischemia and/or necrosis. Currently, various tests have been used to detect myocardial events (particularly late occurring events, such as necrotic myocardial ischemia). The clinically available tests include determining the levels of cardiac specific isoform(s) of troponin I (TnI), and/or troponin T (TnT), or creatine kinase (CK-MB) or myoglobin. Only Tn I and TnT are the current gold standard, CK MB and myoglobin are not cardiac specific. The recent introduction of high sensitive Troponin assays allows for the detection of cardiac components in early stage of MI such as cardiac ischemia during first few hours of ER presentation.
However, there are several issues in the application of the gold standard Troponin assays and recent high-sensitive troponin assays in accessing cardiac injury: 1). clinical specificity for cardiac injury—the ultra-sensitive troponin assays also pick up miniscule amounts of troponin protein in older people, after strenuous or vigorous exercise like running marathons, and in people with subclinical hearing conditions; and 2). a small percentage of patients presenting at ER with negative troponin test will have life threatening cardiac events later.
Therefore, all current clinical tests are not completely satisfactory for accurate and differential diagnosis and prognosis of cardiac injury. There is a huge need to have additional markers/tests to provide specificity and differentiating underline pathophysiology in cardiac injury diagnosis and prognosis. The markers described here can be used in conjunction with other clinical available assays such high-sensitive troponin assays, myoglobin, CK-MB total and isoform types of assays.
The novelty of this invention is to monitor cardiac injury in three aspects:
A.) The present inventors identified markers for accurate and differential diagnosis and prognosis of cardiac injury. A panel of markers can be applied in multiple clinical settings.
B). Both antibody based immunosandwich assay and mass spectrometry based multiple reaction monitoring (MRM) assays listed markers can be used for monitoring cardiac injury markers in ACS patients for diagnosis, prognosis, disease management and risk stratification. The methods described provide quantitative measurement of identified markers.
Wherein a significant amount (e.g., at least a statistically significant amount) of overexpression of the protein(s) compared to the baseline value (or values normally observed in healthy individuals) is indicative of myocardial injury (e.g., indicates that the subject has, or is likely to have, myocardial ischemia). The amount of expression may be determined for any combination of class I and class II cardiac injury markers.
C) The present inventors identified post translational modification (PTM) together with quantitative information of the markers for accurate and differential diagnosis and prognosis of cardiac injury.
A panel of markers with specific PTM can be applied in multiple clinical settings.
1). Identified post translational modification (PTM) together with quantitative information of the new marker will allow for early, accurate and differential diagnosis of cardiac injury from cardiac ischemia to large MI. This will greatly facilitate the diagnosis of individuals presenting to the ER with chest pain.
2). Identified post translational modification (PTM) together with quantitative information of the markers will allow for accurate and differential evaluation of cardiacmyocytes injury in various acute and chronic cardiac diseases. Cardiovascular disease includes a number of conditions affecting the structures or function of the heart, such as coronary artery disease (narrowing of the arteries), heart attack, abnormal heart rhythms or arrhythmias, heart failure, heart valve disease, congenital heart disease, heart muscle disease (cardiomyopathy), pericardial disease, aorta disease and Marfan syndrome and vascular disease (blood vessel disease).
3). Identified post translational modification (PTM) together with quantitative information of the new marker will facilitate differentiating the types of ACS and identify individuals at risk for delayed adverse events. The markers have prognostic value for disease management and risk stratification in ACS patients.
4). Identified post translational modification (PTM) in together with quantitative information of the new marker act as “rule-in” and/or “rule-out” markers to differentiate ischemic cardiac injury from non-ischemic cardiac injury.
Another aspect of the invention relates to methods for identifying subjects that have myocardial injury that is induced by coronary blood vessel blockage which limits the supply of blood, comprising determining in the sample from the subject the amount, compared to a baseline value, of at least one of the proteins (intact or degradation or processed products) of class I or class II injury markers. The amount of expression may be determined for any combination of class I or II these proteins or in any order. In a method of the invention, a determination that increasing numbers of protein markers of the invention are overexpressed in a subject can further indicate that the subject has (or is likely to have) myocardial injury.
In further embodiments, a method may further comprise measuring in the sample the amount of one or more other markers that have been reported to be diagnostic of cardiac necrosis, including cardiac specific isoforms of troponin I (TnI) and/or troponin T (TnT), (although CK-MB, myoglobin have been used in the past, cTnI and cTnT are the current gold standards) wherein a significant increase (e.g., at least a statistically significant increase) of the one or more markers further is further indicative that the subject has myocardial injury.
Cardiac injury is a heterogeneous condition caused by a variety of underlying mechanisms. Even if a single marker of the invention is capable of detecting a subject having cardiac injury resulting from a particular mechanism, it is possible for some markers that the marker is also up-regulated in a disease other than myocardial injury. In such a case, it would be desirable to screen for up-regulation of at least one additional marker that is associated with cardiac injury caused by a different underlying mechanism.
Another aspect of the invention is a method for treating a subject suspected of having myocardial injury, comprising determining by a method as above if the subject has (or is likely to have) myocardial injury and, (1) if the subject is determined to have (or to be likely to have) myocardial injury, treating the subject aggressively [such as angioplasty (mechanical widening in opening blood vessels), or treated with an anti-thrombolysis agent (PCI, or TPA) or undergo coronary bypass surgery to replace the injured/blocked coronary artery], or (2) if the subject is determined not to have (or not to be likely to have) myocardial injury, treating the subject would be released from hospital (especially if not detectable cTnI or cTnT was present). This would allow the absence of the ischemic markers to be used as a rule out and allowing person to be release from care.
In another aspect, the present invention provides kits. In certain embodiments, a kit for detecting the presence of cardiac injury in a subject, comprises reagents for detecting the amounts of at least one marker described herein.
The present invention further provides methods for determining if a subject has myocardial ischemia, comprising (a) providing a sample obtained from a subject suspected of having myocardial ischemia; (b) determining in the sample the amount of at least one of the proteins in Tables 1-11; (c) comparing the amount(s) of the protein(s) to a baseline value (or healthy individual level) that is indicative of the amount of the protein in a subject that does not have myocardial ischemia, wherein an increased amount (e.g., a statistically significantly increased amount) of the protein(s) compared to the baseline value is indicative of myocardial ischemia. The method can also comprise generating a report summarizing the biomarker levels and the baseline values. In other embodiments, the method can further comprise indicating, recommending or otherwise listing a particular treatment modality.
In other embodiments, the method can further comprise (d) comparing the amount (s) of the proteins to a baseline over time, the kinetic rise and fall of proteins optionally in combination with known neurosis markers is indicative of impending myocardial injury (or other cardio and vascular events such as stroke). The method can further comprise (e) comparing the amount(s) of the PTMs of the protein(s) to a baseline value (or healthy individual level) that is indicative of the amount of the PTMs of the protein in a subject that does not have myocardial ischemia, wherein an increased amount (e.g., a statistically significantly increased amount) of the PTMs of protein(s) compared to the baseline value is indicative of myocardial ischemia. In certain embodiments, the method can further comprise (f) comparing the amount (s) of the PTMs of the proteins to a baseline over time, the kinetic rise and fall of the PTMs of the proteins optionally in combination with known neurosis markers is indicative of impending myocardial injury (or other cardio and vascular events such as stroke). It can also be used to determine risk in patients with stable and unstable angina.
Thus, the methods described herein include measuring the amounts (full length, isoforms, PTM forms or peptides thereof) over time. The methods further comprise comparing such amounts to a baseline value, wherein an increased or decreased amount compared to the baseline value is indicative of myocardial injury. The method can also comprise treating a subject with one or more of an anti-thrombolysis agent, coronary bypass surgery or angioplasty, wherein the subject was tested using a method described herein.
A sample which is “provided” can be obtained by the person (or machine) conducting the assay, or it can have been obtained by another, and transferred to the person (or machine) carrying out the assay.
This patent application is extension of the previous patent application (PCT/US2009/045168). The present invention 1). provides more markers; 2). provides broader utility of markers to general cardiac injury markers. 3). classifies the markers into cardiac injury markers (class I) and cardiac injury related markers (class II); 4). provides mass spectrometry based quantification assay MRM method for 18 cardiac injury markers; 5). provides data on various ACS cohorts including valve replacement cohort, ACS (TNI positive), CAD and normal individuals, Emergency Department MI, stable angina (SA), unstable angina (UA with Tni position and negative individuals). The future related work includes: 1). Develop MRM assay for the rest of cardiac injury markers; 2). Development antibody capture-mass spectrometry based quantification of cardiac injury markers with low concentrations; 3). Test them in various cohort.
Further embodiments of the present invention include:
1. An Emergency Department (ED) test of body fluids (blood, urine, etc.) to be administered to individuals presenting to the ER with chest pain;
2. A home chest pain test kit including these proteins and necrosis markers for blood and urine or any other body fluid. This would mean any patient released from an ED or cardiac ward who is at risk for another cardiac event over, for example, the next 48 hours would take test over that time at home and, if positive, return to ED;
3. The cardiac injury markers of clinical tests as well as home test kits to be performed for differential and specific diagnosis of cardiac abnormity; and
4). The cardiac injury markers of clinical tests and home test kits to monitor the health state of cardiac condition for risk stratification.
It is understood that the present invention is not limited to the particular methods and components, etc., described herein, as these may vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to a “protein” is a reference to one or more proteins, and includes equivalents thereof known to those skilled in the art and so forth.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Specific methods, devices, and materials are described, although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention.
All publications cited herein are hereby incorporated by reference including all journal articles, books, manuals, published patent applications, and issued patents. In addition, the meaning of certain terms and phrases employed in the specification, examples, and appended claims are provided. The definitions are not meant to be limiting in nature and serve to provide a clearer understanding of certain aspects of the present invention.
As used herein, the term “antibody” is used in reference to any immunoglobulin molecule that reacts with a specific antigen. It is intended that the term encompass any immunoglobulin (e.g., IgG, IgM, IgA, IgE, IgD, etc.) obtained from any source (e.g., humans, rodents, non-human primates, caprines, bovines, equines, ovines, etc.). Specific types/examples of antibodies include polyclonal, monoclonal, humanized, chimeric, human, or otherwise-human-suitable antibodies. “Antibodies” also includes any fragment or derivative of any of the herein described antibodies.
As used herein, the term “antigen” is generally used in reference to any substance that is capable of reacting with an antibody. More specifically, as used herein, the term “antigen” refers to a synthetic peptide, polypeptide, protein or fragment of a polypeptide or protein, or other molecule which elicits an antibody response in a subject, or is recognized and bound by an antibody.
As used herein, the term “biomarker” refers to a molecule that is associated either quantitatively or qualitatively with a biological change. Examples of biomarkers include polypeptides, proteins or fragments of a polypeptide or protein; and polynucleotides, such as a gene product, RNA or RNA fragment; and other body metabolites. In certain embodiments, a “biomarker” means a compound that is differentially present (i.e., increased or decreased) in a biological sample from a subject or a group of subjects having a first phenotype (e.g., having a disease or condition) as compared to a biological sample from a subject or group of subjects having a second phenotype (e.g., not having the disease or condition or having a less severe version of the disease or condition). A biomarker may be differentially present at any level, but is generally present at a level that is increased by at least 5%, by at least 10%, by at least 15%, by at least 20%, by at least 25%, by at least 30%, by at least 35%, by at least 40%, by at least 45%, by at least 50%, by at least 55%, by at least 60%, by at least 65%, by at least 70%, by at least 75%, by at least 80%, by at least 85%, by at least 90%, by at least 95%, by at least 100%, by at least 110%, by at least 120%, by at least 130%, by at least 140%, by at least 150%, or more; or is generally present at a level that is decreased by at least 5%, by at least 10%, by at least 15%, by at least 20%, by at least 25%, by at least 30%, by at least 35%, by at least 40%, by at least 45%, by at least 50%, by at least 55%, by at least 60%, by at least 65%, by at least 70%, by at least 75%, by at least 80%, by at least 85%, by at least 90%, by at least 95%, or by 100% (i.e., absent). A biomarker is preferably differentially present at a level that is statistically significant (e.g., a p-value less than 0.05 and/or a q-value of less than 0.10 as determined using, for example, either Welch's T-test or Wilcoxon's rank-sum Test).
In addition, the term “biomarker” also includes the isoforms and/or post-translationally modified forms of any of the foregoing. The present invention contemplates the detection, measurement, quantification, determination and the like of both unmodified and modified (e.g., glycosylation, citrullination, phosphorylation, oxidation or other post-translational modification) proteins/polypeptides/peptides. In certain embodiments, it is understood that reference to the detection, measurement, determination, and the like, of a biomarker refers detection of the protein/polypeptide/peptide (modified and/or unmodified).
The proteins and combinations of proteins discussed herein are sometimes referred to herein as “proteins (or protein markers) of the invention.” The properties and amino acid sequences of the proteins of the invention are well-known and can be determined routinely, as well as downloaded from various known databases. See, e.g., International Protein Index (IPI) and Uniprot databases. A summary of some properties of some of the proteins discussed herein, including their IPI ID number and amino acid sequences, is provided. This information is accurate as of the date of filing of this application. However, some of this information, including the sequences, is routinely updated (e.g., to correct mistakes in the previous entries), so updated (corrected) information about the proteins is included in this application. Information provided in the IPI database is incorporated by reference in the present application.
Although much of the data presented in the Examples herein are directed to particular forms of proteins of interest (or peptides thereof), it will be evident to a skilled worker that a variety of forms of these proteins may be indicative of the presence of myocardial ischemia in a subject. For example, the protein may be an intact, full-length protein. If a protein undergoes processing naturally (e.g., is converted from a pre-pro-hormone to a pro-hormone to a fully processed hormone; the N-terminal methionine is cleaved off; the signal sequence is removed, often accompanied by a post-translational modification, such as acetylation; etc.), any of these forms of the protein are included in the invention. Furthermore, in some instances, a protein of the invention may be broken down or degraded (e.g., proteins that are found in the urine). In such a case, an investigator can determine the level of one or more of the fragments or degradation products. A “diagnostic protein fragment,” as used herein, is a fragment that is unique to the protein being identified, as detected by the assay. For example, a diagnostic fragment is recognized specifically by an antibody used to detect the full-length protein. Certain isoforms or post translational modifications (PTM) may also be encompassed by the invention.
The term “one or more of” refers to combinations of various biomarker proteins. The term encompasses 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 . . . N, where “N” is the total number of biomarker proteins in the particular embodiment. The term also encompasses at least 1, at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 15, 16, 17, at least 18, at least 19, at least 20, at least 21, at least 22, at least 23, at least 24, at least 25, at least 26, at least 27, at least 28, at least 29, at least 30, at least 31, at least 32, at least 33, at least 34, at least 35, at least 36, at least 37, at least 38, at least 39, at least 40 . . . N. It is understood that the recitation of biomarkers herein includes the phrase “one or more of” the biomarkers and, in particular, includes the “at least 1, at least 2, at least 3” and so forth language in each recited embodiment of a biomarker panel.
As used herein, the terms “comparing” or “comparison” refers to making an assessment of how the proportion, level or cellular localization of one or more biomarkers in a sample from a patient relates to the proportion, level or cellular localization of the corresponding one or more biomarkers in a standard or control sample. For example, “comparing” may refer to assessing whether the proportion, level, or cellular localization of one or more biomarkers in a sample from a patient is the same as, more or less than, or different from the proportion, level, or cellular localization of the corresponding one or more biomarkers in standard or control sample. More specifically, the term may refer to assessing whether the proportion, level, or cellular localization of one or more biomarkers in a sample from a patient is the same as, more or less than, different from or otherwise corresponds (or not) to the proportion, level, or cellular localization of predefined biomarker levels/ratios that correspond to, for example, a patient having myocardial injury, not having myocardial injury, is responding to treatment for myocardial injury, is not responding to treatment for myocardial injury, is/is not likely to respond to a particular myocardial injury treatment, or having/not having another disease or condition. In a specific embodiment, the term “comparing” refers to assessing whether the level of one or more biomarkers of the present invention in a sample from a patient is the same as, more or less than, different from other otherwise correspond (or not) to levels/ratios of the same biomarkers in a control sample (e.g., predefined levels/ratios that correlate to uninfected individuals, standard myocardial injury levels/ratios, etc.).
In another embodiment, the terms “comparing” or “comparison” refers to making an assessment of how the proportion, level or cellular localization of one or more biomarkers in a sample from a patient relates to the proportion, level or cellular localization of another biomarker in the same sample. For example, a ratio of one biomarker to another from the same patient sample can be compared. In another embodiment, a level of one biomarker in a sample (e.g., a post-translationally modified biomarker protein) can be compared to the level of the same biomarker (e.g., unmodified biomarker protein) in the sample. Ratios of modified:unmodified biomarker proteins can be compared to other protein ratios in the same sample or to predefined reference or control ratios.
In embodiments in which the relationship of the biomarkers are described in terms of a ratio, the ratio can include 1-fold, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-, 13-, 14-, 15-, 16-, 17-, 18-, 19-, 20-, 21-, 22-, 23-, 24-, 25-, 26-, 27-, 28-, 29-, 30-, 31-, 32-, 33-, 34-, 35-, 36-, 37-, 38-, 39-, 40-, 41-, 42-, 43-, 44-, 45-, 46-, 47-, 48-, 49-, 50-, 51-, 52-, 53-, 54-, 55-, 56-, 57-, 58-, 59-, 60-, 61-, 62-, 63-, 64-, 65-, 66-, 67-, 68-, 69-, 70-, 71-, 72-, 73-, 74-, 75-, 76-, 77-, 78-, 79-, 80-, 81-, 82-, 83-, 84-, 85-, 86-, 87-, 88-, 89-, 90-, 91-, 92-, 93-, 94-, 95-, 96-, 97-, 98-, 99-, 100-fold or more difference (higher or lower). Alternatively, the difference can include 0.9-fold, 0.8-fold, 0.7-fold, 0.7-fold, 0.6-fold, 0.5-fold, 0.4-fold, 0.3-fold, 0.2-fold, and 0.1-fold (higher or lower) depending on context. The foregoing can also be expressed in terms of a range (e.g., 1-5 fold/times higher or lower) or a threshold (e.g., at least 2-fold/times higher or lower).
As used herein, the terms “indicates” or “correlates” (or “indicating” or “correlating,” or “indication” or “correlation,” depending on the context) in reference to a parameter, e.g., a modulated proportion, level, or cellular localization in a sample from a patient, may mean that the patient has a myocardial injury or is otherwise suffering from neurodegeneration. In specific embodiments, the parameter may comprise the level of one or more biomarkers of the present invention. A particular set or pattern of the amounts of one or more biomarkers may indicate that a patient has a myocardial injury (i.e., correlates to a patient having myocardial injury). In other embodiments, a correlation could be the ratio of a post-translationally modified protein to the unmodified protein indicates (or a change in the ratio over time or as compared to a reference/control ratio) could mean that the patient has a myocardial injury).
In other embodiments, a particular set or pattern of the amounts of one or more biomarkers may be correlated to a patient being unaffected (i.e., indicates a patient does not have myocardial injury). In certain embodiments, “indicating,” or “correlating,” as used according to the present invention, may be by any linear or non-linear method of quantifying the relationship between levels/ratios of biomarkers to a standard, control or comparative value for the assessment of the diagnosis, prediction of myocardial injury or myocardial injury progression, assessment of efficacy of clinical treatment, identification of a patient that may respond to a particular treatment regime or pharmaceutical agent, monitoring of the progress of treatment, and in the context of a screening assay, for the identification of an anti-myocardial injury therapeutic.
A “subject,” as used herein, includes any animal that has, or is suspected of having, a myocardial injury, for example, myocardial ischemia. Suitable subjects (patients) include laboratory animals (such as mouse, rat, rabbit, guinea pig or pig), farm animals, sporting animals (e.g., dogs or horses) and domestic animals or pets (such as a horse, dog or cat). Non-human primates and human patients are included. For example, human subjects who present with chest pain or other symptoms of cardiac distress, including, e.g., shortness of breath, nausea, vomiting, sweating, weakness, fatigue, or palpitations, can be evaluated by a method of the invention. About ¼ of myocardial infarction (MI) are silent and without chest pain. Furthermore, patients who have been evaluated in an emergency room or in an ambulance or physician's office and then dismissed as not being ill according to current tests for infarction have an increased risk of having a heart attack in the next 24-48 hours; such patients can be monitored by a method of the invention to determine if and when they begin express markers of the invention, which indicates that, e.g., they are beginning to exhibit ischemia. Subjects can also be monitored by a method of the invention to improve the accuracy of current provocative tests for ischemia, such as exercise stress testing. An individual can be monitored by a method of the invention during exercise stress tests or Dobutamine stress tests to determine if the individual is at risk for ischemia; such monitoring can supplement or replace the test that is currently carried out. Athletes (e.g., humans, racing dogs or race horses) can be monitored during training to ascertain if they are exerting themselves too vigorously and are in danger of undergoing an MI.
The terms “measuring” and “determining” are used interchangeably throughout, and refer to methods which include obtaining or providing a patient sample and/or detecting the level of a biomarker(s) in a sample. In one embodiment, the terms refer to obtaining or providing a patient sample and detecting the level of one or more biomarkers in the sample. In another embodiment, the terms “measuring” and “determining” mean detecting the level of one or more biomarkers in a patient sample. The term “measuring” is also used interchangeably throughout with the term “detecting.” In certain embodiments, the term is also used interchangeably with the term “quantitating.”
The terms “sample,” “patient sample,” “biological sample,” and the like, encompass a variety of sample types obtained from a patient, individual, or subject and can be used in a diagnostic, prognostic and/or monitoring assay. The patient sample may be obtained from a healthy subject, a diseased patient or a patient having associated symptoms of myocardial injury. In particular embodiments, a “sample” (e.g., a test sample) from a subject refers to a sample that might be expected to contain elevated levels of the protein markers of the invention in a subject having myocardial ischemia. In certain embodiments, a sample that is “provided” can be obtained by the person (or machine) conducting the assay, or it can have been obtained by another, and transferred to the person (or machine) carrying out the assay.
Moreover, a sample obtained from a patient can be divided and only a portion may be used for diagnosis. Further, the sample, or a portion thereof, can be stored under conditions to maintain sample for later analysis. The definition specifically encompasses blood and other liquid samples of biological origin (including, but not limited to, peripheral blood, serum, plasma, cord blood, amniotic fluid, cerebrospinal fluid, urine, saliva, stool and synovial fluid), solid tissue samples such as a biopsy specimen or tissue cultures or cells derived therefrom and the progeny thereof. In certain embodiment, a sample comprises cerebrospinal fluid. In a specific embodiment, a sample comprises a blood sample. In another embodiment, a sample comprises a plasma sample. In yet another embodiment, a serum sample is used.
In another embodiment, the sample is urine, sweat, or another body fluid into which proteins are sometimes removed from the blood stream. In the case of urine, for example, the protein is likely to be broken down, so diagnostic fragments of the proteins of the invention can be screened for by appropriate methods. In another embodiment, the sample is cardiac tissue, which is harvested, e.g., after a heart transplant or the insertion of a pacemaker or defibrillator. Methods for obtaining samples and preparing them for analysis (e.g., for detection of the amount of protein) are conventional and well-known in the art.
The definition of “sample” also includes samples that have been manipulated in any way after their procurement, such as by centrifugation, filtration, precipitation, dialysis, chromatography, treatment with reagents, washed, or enriched for certain cell populations. The terms further encompass a clinical sample, and also include cells in culture, cell supernatants, tissue samples, organs, and the like. Samples may also comprise fresh-frozen and/or formalin-fixed, paraffin-embedded tissue blocks, such as blocks prepared from clinical or pathological biopsies, prepared for pathological analysis or study by immunohistochemistry.
Various methodologies of the instant invention include a step that involves comparing a value, level, feature, characteristic, property, etc. to a “suitable control,” referred to interchangeably herein as an “appropriate control,” a “control sample,” a “reference” or simply a “control.” A “suitable control,” “appropriate control,” “control sample,” “reference” or a “control” is any control or standard familiar to one of ordinary skill in the art useful for comparison purposes. A “reference level” of a biomarker means a level of the biomarker that is indicative of a particular disease state, phenotype, or lack thereof, as well as combinations of disease states, phenotypes, or lack thereof. A “positive” reference level of a biomarker means a level that is indicative of a particular disease state or phenotype. A “negative” reference level of a biomarker means a level that is indicative of a lack of a particular disease state or phenotype. For example, a “myocardial injury-positive reference level” of a biomarker means a level of a biomarker that is indicative of a positive diagnosis of myocardial injury in a subject, and a “myocardial injury—negative reference level” of a biomarker means a level of a biomarker that is indicative of a negative diagnosis of myocardial injury in a subject. A “reference level” of a biomarker may be an absolute or relative amount or concentration of the biomarker, a presence or absence of the biomarker, a range of amount or concentration of the biomarker, a minimum and/or maximum amount or concentration of the biomarker, a mean amount or concentration of the biomarker, and/or a median amount or concentration of the biomarker; and, in addition, “reference levels” of combinations of biomarkers may also be ratios of absolute or relative amounts or concentrations of two or more biomarkers with respect to each other. Appropriate positive and negative reference levels of biomarkers for a particular disease state, phenotype, or lack thereof may be determined by measuring levels of desired biomarkers in one or more appropriate subjects, and such reference levels may be tailored to specific populations of subjects (e.g., a reference level may be age-matched so that comparisons may be made between biomarker levels in samples from subjects of a certain age and reference levels for a particular disease state, phenotype, or lack thereof in a certain age group). Such reference levels may also be tailored to specific techniques that are used to measure levels of biomarkers in biological samples (e.g., LC-MS, GC-MS, ELISA, PCR, etc.), where the levels of biomarkers may differ based on the specific technique that is used.
In one embodiment, a “suitable control” or “appropriate control” is a value, level, feature, characteristic, property, etc., determined in a cell, organ, or patient, e.g., a control or normal cell, organ, or patient, exhibiting, for example, normal traits. For example, the biomarkers of the present invention may be assayed for levels/ratios in a sample from an unaffected individual (UI) or a normal control individual (NC) (both terms are used interchangeably herein). For example, a “suitable control” or “appropriate control” can be a value, level, feature, characteristic, property, ratio, etc. determined prior to performing a therapy (e.g., myocardial injury treatment) on a patient or a value, level, feature, characteristic, property, ratio, etc. determined prior to injury (e.g., a baseline test). In yet another embodiment, a transcription rate, mRNA level, translation rate, protein level/ratio, biological activity, cellular characteristic or property, genotype, phenotype, etc., can be determined prior to, during, or after administering a therapy into a cell, organ, or patient. In a further embodiment, a “suitable control” or “appropriate control” is a predefined value, level, feature, characteristic, property, ratio, etc. A “suitable control” can be a profile or pattern of levels/ratios of one or more biomarkers of the present invention that correlates to myocardial injury, to which a patient sample can be compared. The patient sample can also be compared to a negative control, i.e., a profile that correlates to not having myocardial injury.
As used herein, the term “predetermined threshold value of expression” of a biomarker refers to the level of expression of the same biomarker (expressed, for example, in ng/ml) in a corresponding control/normal sample or group of control/normal samples obtained from normal, or healthy, subjects, i.e., subject who do not have myocardial injury. Further, the term “altered level of expression” of a biomarker in a sample refers to a level that is either below or above the predetermined threshold value of expression for the same biomarker and thus encompasses either high (increased) or low (decreased) expression levels.
When the values of more than one protein are being analyzed, a statistical method such as multi-variant analysis or principal component analysis (PCA) can be used which takes into account the levels of the various proteins (e.g., using a linear regression score). For verification, an immunoassay or multiple reaction monitoring (MRM, a MS-based targeted method that quantifies peptides that are unique to the protein of interest) can be used on individuals (control, ischemia and MI).
In some embodiments, it is desirable to express the results of an assay in terms of an increase (e.g., a statistically significant increase) in a value (or combination of values) compared to a baseline value. A “significant” increase in a value, as used herein, can refer to a difference which is reproducible or statistically significant, as determined using statistical methods that are appropriate and well-known in the art, generally with a probability value of less than five percent chance of the change being due to random variation. In general, a statistically significant value is at least two standard deviations from the value in a “normal” healthy control subject. Suitable statistical tests will be evident to a skilled worker. For example, a significant increase in the amount of a protein compared to a baseline value can be about 50%, 2-fold, or higher. A significantly elevated amount of a protein of the invention compared to a suitable baseline value, then, is indicative that a test subject has, for example, myocardial ischemia (indicates that the subject is likely to have, for example, myocardial ischemia). A subject is “likely” to have myocardial injury, e.g., myocardial ischemia, if the subject has levels of the marker protein(s) and/or PTMs significantly above those of a healthy control or his own baseline (taken at an earlier time point). The extent of the increased levels correlates to the % chance. For example, the subject can have greater than about a 50% chance, e.g., greater than about 70%, 80% 90%, 95% or higher chance, of having the ischemia. In general, the presence of an elevated amount of a marker of the invention is a strong indication that the subject has ischemia. Although several embodiments are mentioned in the context of myocardial ischemia, it is understood that the methods and compositions of the present invention apply to other forms of myocardial injury.
As used herein, a “baseline value” generally refers to the level (amount) of a protein in a comparable sample (e.g., from the same type of tissue as the tested tissue, such as blood or serum), from a “normal” healthy subject that does not exhibit myocardial ischemia. If desired, a pool or population of the same tissues from normal subjects can be used, and the baseline value can be an average or mean of the measurements. Suitable baseline values can be determined by those of skill in the art without undue experimentation. Suitable baseline values may be available in a database compiled from the values and/or may be determined based on published data or on retrospective studies of patients' tissues, and other information as would be apparent to a person of ordinary skill implementing a method of the invention. Suitable baseline values may be selected using statistical tools that provide an appropriate confidence interval so that measured levels that fall outside the standard value can be accepted as being aberrant from a diagnostic perspective, and predictive of ischemia.
It is generally not practical in a clinical or research setting to use patient samples as sources for baseline controls. Therefore, one can use any of variety of reference values in which the same or a similar level of expression is found as in a subject that does not have myocardial ischemia.
It will be appreciated by those of skill in the art that a baseline or normal level need not be established for each assay as the assay is performed but rather, baseline or normal levels can be established by referring to a form of stored information regarding a previously determined baseline levels for a given protein or panel of proteins, such as a baseline level established by any of the above-described methods. Such a form of stored information can include, for example, a reference chart, listing or electronic file of population or individual data regarding “normal levels” (negative control) or positive controls; a medical chart for the patient recording data from previous evaluations; a receiver-operator characteristic (ROC) curve; or any other source of data regarding baseline levels that is useful for the patient to be diagnosed. In one embodiment of the invention, the amount of the proteins in a combination of proteins, compared to a baseline value, is expressed as a linear regression score, as described, e.g., in Irwin, in Neter, Kutner, Nachtsteim, Wasserman (1996) Applied Linear Statistical Models, 4.sup.th edition, page 295.
In an embodiment in which the progress of a treatment is being monitored, a baseline value can be based on earlier measurements taken from the same subject, before the treatment was administered.
The terms “specifically binds to,” “specific for,” and related grammatical variants refer to that binding which occurs between such paired species as enzyme/substrate, receptor/agonist, antibody/antigen, and lectin/carbohydrate which may be mediated by covalent or non-covalent interactions or a combination of covalent and non-covalent interactions. When the interaction of the two species produces a non-covalently bound complex, the binding which occurs is typically electrostatic, hydrogen-bonding, or the result of lipophilic interactions. Accordingly, “specific binding” occurs between a paired species where there is interaction between the two which produces a bound complex having the characteristics of an antibody/antigen or enzyme/substrate interaction. In particular, the specific binding is characterized by the binding of one member of a pair to a particular species and to no other species within the family of compounds to which the corresponding member of the binding member belongs. Thus, for example, an antibody typically binds to a single epitope and to no other epitope within the family of proteins. In some embodiments, specific binding between an antigen and an antibody will have a binding affinity of at least 10−6 M. In other embodiments, the antigen and antibody will bind with affinities of at least 10−7 M, 10−8 M to 10−9 M, 10−10 M, 10−11 M, or 10−12 M. As used herein, the terms “specific binding” or “specifically binding” when used in reference to the interaction of an antibody and a protein or peptide means that the interaction is dependent upon the presence of a particular structure (i.e., the epitope) on the protein.
As used herein, the terms “binding agent specific for” or “binding agent that specifically binds” refers to an agent that binds to a biomarker and does not significantly bind to unrelated compounds. Examples of binding agents that can be effectively employed in the disclosed methods include, but are not limited to, proteins and antibodies, such as monoclonal or polyclonal antibodies, or antigen-binding fragments thereof. In certain embodiments, a binding agent binds a biomarker (e.g., a polypeptide biomarker) with an affinity constant of, for example, greater than or equal to about 1×10−6 M.
A variety of tests have been used to detect myocardial events (particularly late occurring events, such as necrotic myocardial ischemia). These include, e.g., determining the levels of cardiac specific isoform(s) of troponin I (TnI) and/or troponin T (TnT), CK-MB (Creatine Kinase-MB), or myoglobin, although only the former two are the current gold standard. CK MB and myoglobin are not cardiac-specific. However, none of these markers is completely satisfactory for the detection of myocardial ischemia. For example, they fail to detect early stages of heart disease, such as non-necrotic myocardial ischemia. The new markers described herein can be used in conjunction with these types of assays.
The amount of a protein can be measured using any suitable method. Some methods involve the use of antibodies, binding ligands, or mass spectrometry tagged peptides specific for a protein of interest. Antibodies suitable for use in assays of the invention are commercially available, or can be prepared routinely. Methods for preparing and using antibodies in assays for proteins of interest are conventional, and are described, e.g., in Green et al., Production of Polyclonal Antisera, in immunochemical Protocols (Manson, ed.), (Humana Press 1992); Coligan et al., in Current Protocols in Immunology, Sec. 2.4.1 (1992); Kohler & Milstein (1975), Nature 256, 495; Coligan et al., sections 2.5.1-2.6.7; and Harlow et al., Antibodies: A Laboratory Manual, page 726 (Cold Spring Harbor Laboratory Pub. 1988).
A. Detection by Immunoassay
In particular embodiments, the biomarkers of the present invention can be detected and/or measured by immunoassay. Immunoassay requires biospecific capture reagents/binding agent, such as antibodies, to capture the biomarkers. Many antibodies are available commercially. Antibodies also can be produced by methods well known in the art, e.g., by immunizing animals with the biomarkers. Biomarkers can be isolated from samples based on their binding characteristics. Alternatively, if the amino acid sequence of a polypeptide biomarker is known, the polypeptide can be synthesized and used to generate antibodies by methods well-known in the art.
The present invention contemplates traditional immunoassays including, for example, sandwich immunoassays including ELISA or fluorescence-based immunoassays, immunoblots, Western Blots (WB), as well as other enzyme immunoassays. Nephelometry is an assay performed in liquid phase, in which antibodies are in solution. Binding of the antigen to the antibody results in changes in absorbance, which is measured. In a SELDI-based immunoassay, a biospecific capture reagent for the biomarker is attached to the surface of an MS probe, such as a pre-activated protein chip array. The biomarker is then specifically captured on the biochip through this reagent, and the captured biomarker is detected by mass spectrometry.
In certain embodiments, the expression levels of the biomarkers employed herein are quantified by immunoassay, such as enzyme-linked immunoassay (ELISA) technology. In specific embodiments, the levels of expression of the biomarkers are determined by contacting the biological sample with antibodies, or antigen binding fragments thereof, that selectively bind to the biomarkers; and detecting binding of the antibodies, or antigen binding fragments thereof, to the biomarkers. In certain embodiments, the binding agents employed in the disclosed methods and compositions are labeled with a detectable moiety.
For example, the level of a biomarker in a sample can be assayed by contacting the biological sample with an antibody, or antigen binding fragment thereof, that selectively binds to the target biomarker (referred to as a capture molecule or antibody or a binding agent), and detecting the binding of the antibody, or antigen-binding fragment thereof, to the biomarker. The detection can be performed using a second antibody to bind to the capture antibody complexed with its target biomarker. A target biomarker can be an entire protein, or a variant or modified form thereof. Kits for the detection of biomarkers as described herein can include pre-coated strip plates, biotinylated secondary antibody, standards, controls, buffers, streptavidin-horse radish peroxidase (HRP), tetramethyl benzidine (TMB), stop reagents, and detailed instructions for carrying out the tests including performing standards.
In one embodiment of the invention, antibodies specific for a (one or more) protein of the invention are immobilized on a surface (e.g., are reactive elements on an array, such as a microarray, or are on another surface, such as used for surface plasmon resonance (SPR)-based technology, such as Biacore), and proteins in the sample are detected by virtue of their ability to bind specifically to the antibodies. Alternatively, proteins in the sample can be immobilized on a surface, and detected by virtue of their ability to bind specifically to the antibodies. Methods of preparing the surfaces and performing the analyses, including conditions effective for specific binding, are conventional and well-known in the art.
In one embodiment, a tissue sample (e.g., a cardiac tissue sample) is stained with a suitable antibody in a conventional immunohistochemical assay for those proteins which are present in the myocardium. Note that it can be difficult to obtain human tissue unless an individual is undergoing surgery or a routine biopsy (e.g., following heart transplantation), and such subjects are likely to be ischemic to some degree.
The present disclosure also provides methods for identifying which patients have myocardial injury, diagnosing myocardial injury in a subject, etc. wherein the levels of expression of the biomarkers in a biological sample are determined simultaneously. For example, in one embodiment, methods are provided that comprise: (a) contacting a biological sample obtained from the subject with a plurality of binding agents that selectively bind to a plurality of biomarkers disclosed herein for a period of time sufficient to form binding agent-biomarker complexes; (b) detecting binding of the binding agents to the plurality of biomarkers, thereby determining the levels of expression of the biomarkers in the biological sample; and (c) comparing the levels of expression of the plurality of biomarkers in the biological sample with predetermined threshold values, wherein levels of expression of at least one of the plurality of polypeptide biomarkers above the predetermined threshold values indicates, for example, a myocardial injury in the subject. Examples of binding agents that can be effectively employed in such methods include, but are not limited to, antibodies or antigen-binding fragments thereof, aptamers, lectins and the like.
In a further aspect, the present disclosure provides compositions that can be employed in the disclosed methods. In certain embodiments, such compositions a solid substrate and a plurality of binding agents immobilized on the substrate, wherein each of the binding agents is immobilized at a different, indexable, location on the substrate and the binding agents selectively bind to a plurality of biomarkers disclosed herein. In a specific embodiment, the locations are pre-determined. In one embodiment, the binding agents selectively bind to a plurality of biomarkers comprising one or more of GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, S100A9, PRD2, LTF, Exostosin-like 2, cDNAFLI53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Proalctin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelcidin antibmicrobial peptide, Desmoglein-1, Protein-glutamine gamma-glytamyltransferase E, Bleomycin hydrolase, Protein FAM136A, Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig gamma-2 chain C region, Myoglobin, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Insulin-like growth factor-binding protein 1, cDNA FLI75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA, SAA, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12p70, IL-1b, EMC, and LUM. In other embodiments, such compositions additionally comprise binding agents that selectively bind to other myocardial injury biomarkers. Binding agents that can be employed in such compositions include, but are not limited to, antibodies, or antigen-binding fragments thereof, aptamers, lectins and the like.
Binding agents can include agents that specifically bind post-translationally modified peptides of the foregoing. The PTMS include, for example, citrullination, phosphorylation and oxidation. Post translational modification of carbonic anhydrase 1 (CA1) can include citrullination (ESISVSSEQLAQFR[157] (SEQ ID NO:1), SLLSNVEGDNAVPMQHNNR[157]PTQPLK (SEQ ID NO:2)). PTM of CAT includes citrullination (NAIHTFVQSGSHLAAR[157] (SEQ ID NO:3)) and oxidation (M) (HM[147]N[115]GYGSHTFK (SEQ ID NO:4)). PTM of properdin (CFP) can include oxi (M) (YPPTVSM[147]VEGQGEK (SEQ ID NO:5)). PTM of desmoplakin (DSP) can include citrullination (IGLVR[157]PGTALELLEAQAATGFIVDPVSNLR (SEQ ID NO:6)). PTM of extracellular matrix protein 1 (ECM1) can include citrullination (DILTIDIGR[157] (SEQ ID NO:7), LVWEEAMSR[157] (SEQ ID NO:8), NLPATDPLQR[157] (SEQ ID NO:9), QGETLNFLEIGYSR[157] (SEQ ID NO:10), QHVVYGPWNLPQSSYSHLTR[157] (SEQ ID NO:11)) and citrullination and phosphorylation (Q[129]HVVYGPWN[115]LPQ[129]S[167]S[167]Y[243]S[167]HLT[181]R[157] (SEQ ID NO:12)). PTM of lactoferrin (LTF) can include citrullination (IDSGLYLGSGYFTAIQNLR[157] (SEQ ID NO:13)), VPSHAVVAR[157] (SEQ ID NO:14)) and phosphorylation (S[167]DT[181]S[167]LT[181]W[202]N[115]S[167]VK (SEQ ID NO:15)). PTM of Lumican (LUM) can include citrullination (FN[115]ALQ[129]YLR[157] (SEQ ID NO:16), FNALQYLR[157] (SEQ ID NO:17), SLEYLDLSFNQIAR[157] (SEQ ID NO:18)). PTM of Myosin-7 (MYH7) can include oxidation (M) (IEDMAM[147]LTFLHEPAVLYNLK(SEQ ID NO:19)). Peroxiredoxin-2 (PRD2) PTMs include citrullination (EGGLGPLNIPLLADVTR[157] (SEQ ID NO:20), R[157]LSEDYGVLK(SEQ ID NO:21), TDEGIAYR[157] (SEQ ID NO:22)). S100A7: Oxidation(M) (SIIGM[147]IDM[147]FHK (SEQ ID NO:23), SIIGMIDM[147]FHK) (SEQ ID NO:24); Phosphorylatio (Q[112]S[167]HGAAPCS[167]GGS[167]Q[129] (SEQ ID NO:25)). PTM of S100A9 can include oxidation(M) (QLSFEEFIM[147]LMAR (SEQ ID NO:26)). PTM of SAA1 can include citrullination (FFGHGAEDSLADQAANEWGR[157] (SEQ ID NO:27), GPGGVWAAEAISDAR[157] (SEQ ID NO:28)). PTM of semenogelin-1 (SEMG1) can include citrullination (HLAQHLNNDR[157] (SEQ ID NO:29), HLGGSQQLLHNKQEGR[157] (SEQ ID NO:30)) and citrullination and phosphoryaltion (GES[167]GQ[129]S[167]T[181]N[115]R[157] (SEQ ID NO:31)).
In a related aspect, methods for diagnosing the presence of myocardial injury in a subject are provided, such methods comprising: (a) contacting a biological sample obtained from the subject with a composition disclosed herein for a period of time sufficient to form binding agent-polypeptide biomarker complexes; (b) detecting binding of the plurality of binding agents to the plurality of polypeptide biomarkers, thereby determining the levels of expression of the plurality of polypeptide biomarkers in the biological sample; and (c) comparing the levels of expression of the plurality of polypeptide biomarkers in the biological sample with predetermined threshold values, wherein levels of expression of at least two of the plurality of polypeptide biomarkers above the predetermined threshold values indicates the presence of myocardial injury in the subject. In another embodiment, the method comprises d). comparing the PTMs of the plurality of polypeptide biomarkers in the biological sample with predetermined threshold values, wherein PTMs of expression of at least two of the plurality of polypeptide biomarkers above the predetermined threshold indicates the presence of myocardial injury in the subject.
In yet another aspect, the present disclosure provides compositions comprising a solid substrate and a plurality of polypeptide biomarkers disclosed herein immobilized on the substrate, wherein each of the polypeptide biomarkers is immobilized at a different, indexable, location on the substrate. In certain embodiments, the plurality of polypeptide biomarkers includes one or more of GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, S100A9, PRD2, LTF, Exostosin-like 2, cDNAFLI53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Proalctin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelcidin antibmicrobial peptide, Desmoglein-1, Protein-glutamine gamma-glytamyltransferase E, Bleomycin hydrolase, Protein FAM136A, Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig gamma-2 chain C region, Myoglobin, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Insulin-like growth factor-binding protein 1, cDNA FLI75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA, SAA, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12p70, IL-1b, EMC, and LUM. In other embodiments, the plurality of polypeptide biomarkers further includes at least one polypeptide biomarker selected from the group consisting of GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, S100A9, PRD2, LTF, Exostosin-like 2, cDNAFLI53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Proalctin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelcidin antibmicrobial peptide, Desmoglein-1, Protein-glutamine gamma-glytamyltransferase E, Bleomycin hydrolase, Protein FAM136A, Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig gamma-2 chain C region, Myoglobin, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Insulin-like growth factor-binding protein 1, cDNA FLI75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA, SAA, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12p70, IL-1b, EMC, and LUM.
Although antibodies are useful because of their extensive characterization, any other suitable agent (e.g., a peptide, an aptamer, or a small organic molecule) that specifically binds a biomarker of the present invention is optionally used in place of the antibody in the above described immunoassays. For example, an aptamer that specifically binds a biomarker and/or one or more of its breakdown products might be used. Aptamers are nucleic acid-based molecules that bind specific ligands. Methods for making aptamers with a particular binding specificity are known as detailed in U.S. Pat. No. 5,475,096; U.S. Pat. No. 5,670,637; U.S. Pat. No. 5,696,249; U.S. Pat. No. 5,270,163; U.S. Pat. No. 5,707,796; U.S. Pat. No. 5,595,877; U.S. Pat. No. 5,660,985; U.S. Pat. No. 5,567,588; U.S. Pat. No. 5,683,867; U.S. Pat. No. 5,637,459; and U.S. Pat. No. 6,011,020.
In specific embodiments, the assay performed on the biological sample can comprise contacting the biological sample with one or more capture agents (e.g., antibodies, peptides, aptamer, etc., combinations thereof) to form a biomarker:capture agent complex. The complexes can then be detected and/or quantified. A subject can then be identified as having myocardial injury based on a comparison of the detected/quantified/measured levels of biomarkers to one or more reference controls as described herein.
In one method, a first, or capture, binding agent, such as an antibody that specifically binds the biomarker of interest, is immobilized on a suitable solid phase substrate or carrier. The test biological sample is then contacted with the capture antibody and incubated for a desired period of time. After washing to remove unbound material, a second, detection, antibody that binds to a different, non-overlapping, epitope on the biomarker is then used to detect binding of the polypeptide biomarker to the capture antibody. The detection antibody is preferably conjugated, either directly or indirectly, to a detectable moiety. Examples of detectable moieties that can be employed in such methods include, but are not limited to, cheminescent and luminescent agents; fluorophores such as fluorescein, rhodamine and eosin; radioisotopes; colorimetric agents; and enzyme-substrate labels, such as biotin.
In another embodiment, the assay is a competitive binding assay, wherein labeled biomarker is used in place of the labeled detection antibody, and the labeled biomarker and any unlabeled biomarker present in the test sample compete for binding to the capture antibody. The amount of biomarker bound to the capture antibody can be determined based on the proportion of labeled biomarker detected.
Solid phase substrates, or carriers, that can be effectively employed in such assays are well known to those of skill in the art and include, for example, 96 well microtiter plates, glass, paper, and microporous membranes constructed, for example, of nitrocellulose, nylon, polyvinylidene difluoride, polyester, cellulose acetate, mixed cellulose esters and polycarbonate. Suitable microporous membranes include, for example, those described in US Patent Application Publication no. US 2010/0093557 A1. Methods for the automation of immunoassays are well known in the art and include, for example, those described in U.S. Pat. Nos. 5,885,530, 4,981,785, 6,159,750 and 5,358,691.
The presence of several different polypeptide biomarkers in a test sample can be detected simultaneously using a multiplex assay, such as a multiplex ELISA. Multiplex assays offer the advantages of high throughput, a small volume of sample being required, and the ability to detect different proteins across a board dynamic range of concentrations.
In certain embodiments, such methods employ an array, wherein multiple binding agents (for example capture antibodies) specific for multiple biomarkers are immobilized on a substrate, such as a membrane, with each capture agent being positioned at a specific, pre-determined, location on the substrate. Methods for performing assays employing such arrays include those described, for example, in US Patent Application Publication nos. US2010/0093557A1 and US2010/0190656A1, the disclosures of which are hereby specifically incorporated by reference.
Multiplex arrays in several different formats based on the utilization of, for example, flow cytometry, chemiluminescence or electron-chemiluminesence technology, are well known in the art. Flow cytometric multiplex arrays, also known as bead-based multiplex arrays, include the Cytometric Bead Array (CBA) system from BD Biosciences (Bedford, Mass.) and multi-analyte profiling (xMAP®) technology from Luminex Corp. (Austin, Tex.), both of which employ bead sets which are distinguishable by flow cytometry. Each bead set is coated with a specific capture antibody. Fluorescence or streptavidin-labeled detection antibodies bind to specific capture antibody-biomarker complexes formed on the bead set. Multiple biomarkers can be recognized and measured by differences in the bead sets, with chromogenic or fluorogenic emissions being detected using flow cytometric analysis.
In an alternative format, a multiplex ELISA from Quansys Biosciences (Logan, Utah) coats multiple specific capture antibodies at multiple spots (one antibody at one spot) in the same well on a 96-well microtiter plate. Chemiluminescence technology is then used to detect multiple biomarkers at the corresponding spots on the plate.
B Detection by Mass Spectrometry
Mass spectrometry (MS) can also be used to determine the amount of a protein, using conventional methods. Some typical such methods are described in the Examples herein. Relative ratio between multiple samples can be determined using label free methods (as done in the present Examples), based on spectral count (and the number of unique peptides and the number of observation of each peptide). In particular embodiments, a LTQ-Orbitrap LC/MS/MS instrument can be used. Alternatively, quantitative data can be obtained using multiple reaction monitoring (MRM), most often carried out using a triple quadruple mass spectrometer. In this case, peptides that are unique to a given protein are selected in the MS instrument and quantified. Absolute quantification can be obtained if a known labeled synthetic peptide is used. For detailed methods see, e.g., Qin Fu and JE Van Eyk, in Clinical Proteomics: from diagnostics to therapy (Van Eyk JE and Dunn M, eds), Wiley and Son Press; Current Protocols in Molecular Biology, Preparation of Proteins and Peptides for Mass Spectrometry Analysis in a Bottom-Up Proteomics Workflow, Gundry et al., chapter 10, 2009, in press); and Fu Q, Grote E, Zhu J, Jelinek C, Kottgen A, Coresh J, Van Eyk JE. An Empirical Approach to Signature Peptide Choice for Selected Reaction Monitoring: Quantification of Uromodulin in Urine. Clin Chem. 2016 January; 62(1):198-207. doi: 10.1373/clinchem.2015.242495.
Thus, in one aspect, the biomarkers of the present invention may be detected by mass spectrometry, a method that employs a mass spectrometer to detect gas phase ions. Examples of mass spectrometers are time-of-flight, magnetic sector, quadrupole filter, ion trap, ion cyclotron resonance, Orbitrap, Triple TOFF, hybrids or combinations of the foregoing, and the like.
In particular embodiments, the biomarkers of the present invention are detected using selected reaction monitoring (SRM) mass spectrometry techniques. Selected reaction monitoring (SRM) is a non-scanning mass spectrometry technique, performed on triple quadrupole-like instruments and in which collision-induced dissociation is used as a means to increase selectivity. In SRM experiments two mass analyzers are used as static mass filters, to monitor a particular fragment ion of a selected precursor ion. The specific pair of mass-over-charge (m/z) values associated to the precursor and fragment ions selected is referred to as a “transition” and can be written as parent m/z→fragment m/z (e.g. 673.5→534.3). Unlike common MS based proteomics, no mass spectra are recorded in a SRM analysis. Instead, the detector acts as counting device for the ions matching the selected transition thereby returning an intensity distribution over time. Multiple SRM transitions can be measured within the same experiment on the chromatographic time scale by rapidly toggling between the different precursor/fragment pairs (sometimes called multiple reaction monitoring, MRM). Typically, the triple quadrupole instrument cycles through a series of transitions and records the signal of each transition as a function of the elution time. The method allows for additional selectivity by monitoring the chromatographic coelution of multiple transitions for a given analyte. The terms SRM/MRM are occasionally used also to describe experiments conducted in mass spectrometers other than triple quadrupoles (e.g. in trapping instruments) where upon fragmentation of a specific precursor ion a narrow mass range is scanned in MS2 mode, centered on a fragment ion specific to the precursor of interest or in general in experiments where fragmentation in the collision cell is used as a means to increase selectivity. In this application the terms SRM and MRM or also SRM/MRM can be used interchangeably, since they both refer to the same mass spectrometer operating principle. As a matter of clarity, the term MRM is used throughout the text, but the term includes both SRM and MRM, as well as any analogous technique, such as e.g. highly-selective reaction monitoring, hSRM, LC-SRM or any other SRM/MRM-like or SRM/MRM-mimicking approaches performed on any type of mass spectrometer and/or, in which the peptides are fragmented using any other fragmentation method such as e.g. CAD (collision-activated dissociation (also known as CID or collision-induced dissociation), HCD (higher energy CID), ECD (electron capture dissociation), PD (photodissociation) or ETD (electron transfer dissociation).
In another specific embodiment, the mass spectrometric method comprises matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF MS or MALDI-TOF). In another embodiment, method comprises MALDI-TOF tandem mass spectrometry (MALDI-TOF MS/MS). In yet another embodiment, mass spectrometry can be combined with another appropriate method(s) as may be contemplated by one of ordinary skill in the art. For example, MALDI-TOF can be utilized with trypsin digestion and tandem mass spectrometry as described herein.
In an alternative embodiment, the mass spectrometric technique comprises surface enhanced laser desorption and ionization or “SELDI,” as described, for example, in U.S. Pat. No. 6,225,047 and U.S. Pat. No. 5,719,060. Briefly, SELDI refers to a method of desorption/ionization gas phase ion spectrometry (e.g. mass spectrometry) in which an analyte (here, one or more of the biomarkers) is captured on the surface of a SELDI mass spectrometry probe. There are several versions of SELDI that may be utilized including, but not limited to, Affinity Capture Mass Spectrometry (also called Surface-Enhanced Affinity Capture (SEAC)), and Surface-Enhanced Neat Desorption (SEND) which involves the use of probes comprising energy absorbing molecules that are chemically bound to the probe surface (SEND probe). Another SELDI method is called Surface-Enhanced Photolabile Attachment and Release (SEPAR), which involves the use of probes having moieties attached to the surface that can covalently bind an analyte, and then release the analyte through breaking a photolabile bond in the moiety after exposure to light, e.g., to laser light (see, U.S. Pat. No. 5,719,060). SEPAR and other forms of SELDI are readily adapted to detecting a biomarker or biomarker panel, pursuant to the present invention.
In another mass spectrometry method, the biomarkers can be first captured on a chromatographic resin having chromatographic properties that bind the biomarkers. For example, one could capture the biomarkers on a cation exchange resin, such as CM Ceramic HyperD F resin, wash the resin, elute the biomarkers and detect by MALDI. Alternatively, this method could be preceded by fractionating the sample on an anion exchange resin before application to the cation exchange resin. In another alternative, one could fractionate on an anion exchange resin and detect by MALDI directly. In yet another method, one could capture the biomarkers on an immuno-chromatographic resin that comprises antibodies that bind the biomarkers, wash the resin to remove unbound material, elute the biomarkers from the resin and detect the eluted biomarkers by MALDI or by SELDI.
C. Detection by Polymerase Chain Reaction
In certain embodiments, the biomarkers of the present invention can be detected/measure/quantitated by polymerase chain reaction (PCR). In certain embodiments, the present invention contemplates quantitation of one or more biomarkers described herein including GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, S100A9, PRD2, LTF, Exostosin-like 2, cDNAFLI53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Proalctin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelcidin antibmicrobial peptide, Desmoglein-1, Protein-glutamine gamma-glytamyltransferase E, Bleomycin hydrolase, Protein FAM136A, Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig gamma-2 chain C region, Myoglobin, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Insulin-like growth factor-binding protein 1, cDNA FLI75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA, SAA, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12p70, IL-1b, EMC, and LUM. The one or more biomarkers can be quantitated and the expression can be compared to reference levels. Overexpression or underexpression, depending on the biomarker, relative to the reference is indicative of injury. PCR can include quantitative type PCR, such as quantitative, real-time PCR (both singleplex and multiplex). In a specific embodiment, the quantitation steps are carried using quantitative, real-time PCR. One of ordinary skill in the art can design primers that specifically bind and amplify one or more biomarkers described herein using the publicly available sequences thereof.
In more particular embodiments, an assay performed on a biological sample obtained from a subject may comprise extracting nucleic acids from the biological sample. The assay can further comprise contacting nucleic acids with one or more primers that specifically bind one or more biomarker described herein to form a primer:biomarker complex. The assay can further comprise the step of amplifying the primer:biomarker complexes. The amplified complexes can then be detected/quantified to determine a level of expression of the one or more biomarkers. A subject can then be identified as having a myocardial injury based on a comparison of the measure/quantified/determined levels of one or more biomarkers described herein to one or more reference controls as described herein. The subject can then be treated appropriately, based on the grade/extent of injury. The assay can be performed on mRNA extracted from the biological sample.
D. Detection by Electrochemicaluminescent Assay
In several embodiments, the biomarker biomarkers of the present invention may be detected by means of an electrochemicaluminescent assay developed by Meso Scale Discovery (Gaithersrburg, MD). Electrochemiluminescence detection uses labels that emit light when electrochemically stimulated. Background signals are minimal because the stimulation mechanism (electricity) is decoupled from the signal (light). Labels are stable, non-radioactive and offer a choice of convenient coupling chemistries. They emit light at ˜620 nm, eliminating problems with color quenching. See U.S. Pat. No. 7,497,997; U.S. Pat. No. 7,491,540; U.S. Pat. No. 7,288,410; U.S. Pat. No. 7,036,946; U.S. Pat. No. 7,052,861; U.S. Pat. No. 6,977,722; U.S. Pat. No. 6,919,173; U.S. Pat. No. 6,673,533; U.S. Pat. No. 6,413,783; U.S. Pat. No. 6,362,011; U.S. Pat. No. 6,319,670; U.S. Pat. No. 6,207,369; U.S. Pat. No. 6,140,045; U.S. Pat. No. 6,090,545; and U.S. Pat. No. 5,866,434. See also U.S. Patent Applications Publication No. 2009/0170121; No. 2009/006339; No. 2009/0065357; No. 2006/0172340; No. 2006/0019319; No. 2005/0142033; No. 2005/0052646; No. 2004/0022677; No. 2003/0124572; No. 2003/0113713; No. 2003/0003460; No. 2002/0137234; No. 2002/0086335; and No. 2001/0021534.
E. Other Methods for Detecting Biomarkers
The biomarkers of the present invention can be detected by other suitable methods. Detection paradigms that can be employed to this end include optical methods, electrochemical methods (voltametry and amperometry techniques), atomic force microscopy, and radio frequency methods, e.g., multipolar resonance spectroscopy. Illustrative of optical methods, in addition to microscopy, both confocal and non-confocal, are detection of fluorescence, luminescence, chemiluminescence, absorbance, reflectance, transmittance, and birefringence or refractive index (e.g., surface plasmon resonance, ellipsometry, a resonant mirror method, a grating coupler waveguide method or interferometry).
Furthermore, a sample may also be analyzed by means of a biochip. Biochips generally comprise solid substrates and have a generally planar surface, to which a capture reagent (also called an adsorbent or affinity reagent) is attached. Frequently, the surface of a biochip comprises a plurality of addressable locations, each of which has the capture reagent bound there. Protein biochips are biochips adapted for the capture of polypeptides. Many protein biochips are described in the art. These include, for example, protein biochips produced by Ciphergen Biosystems, Inc. (Fremont, Calif.), Invitrogen Corp. (Carlsbad, Calif.), Affymetrix, Inc. (Fremong, CA), Zyomyx (Hayward, Calif.), R&D Systems, Inc. (Minneapolis, Minn.), Biacore (Uppsala, Sweden) and Procognia (Berkshire, UK). Examples of such protein biochips are described in the following patents or published patent applications: U.S. Pat. No. 6,537,749; U.S. Pat. No. 6,329,209; U.S. Pat. No. 6,225,047; U.S. Pat. No. 5,242,828; PCT International Publication No. WO 00/56934; and PCT International Publication No. WO 03/048768.
A detection (diagnostic) method of the invention can be adapted for many uses. For example, it can be used to follow the progression of cardiac ischemia. In one embodiment of the invention, the detection is carried out both before (or at approximately the same time as), and after, the administration of a treatment, and the method is used to monitor the effectiveness of the treatment. A subject can be monitored in this way to determine the effectiveness for that subject of a particular drug regimen, or a drug or other treatment modality can be evaluated in a pre-clinical or clinical trial. If a treatment method is successful, the levels of the protein markers of the invention are expected to decrease.
A method of the invention can be used to suggest a suitable method of treatment for a subject. For example, if a subject is determined by a method of the invention to be likely to have myocardial ischemia, a decision can be made to treat the subject with an aggressive form of treatment; and, in one embodiment, the treatment is then administered. Suitable aggressive treatment modalities include, for example, angioplasty (mechanical widening to open blood vessels); treating with an anti-thrombolysis agent or, if possible, with percutaneous coronary intervention (PCI, or TPA); or undergoing coronary bypass surgery to replace the injured/blocked coronary artery. By contrast, if a subject is determined not to be likely to have myocardial ischemia, a decision can be made to adopt a less aggressive treatment regimen; and, in one embodiment, the subject is then treated with this less aggressive forms of treatment. Suitable less aggressive forms of treatment include, for example, treatment with asprin and/or agents that bring about thrombolysis (e.g., TPA); periodic monitoring to ensure no future MI events; or recommending changes in life style. A subject that does not have myocardial ischemia is thus spared the unpleasant side-effects associated with the unnecessary, more aggressive forms of treatment. By “treated” is meant that an effective amount of a drug or other anti-heart disease procedure is administered to the subject. An “effective” amount of an agent refers to an amount that elicits a detectable response (e.g., of a therapeutic response) in the subject.
The present invention relates to the use of biomarkers to diagnose myocardial injury. More specifically, the biomarkers of the present invention can be used in diagnostic tests to determine, qualify, and/or assess myocardial injury or status, for example, to diagnose myocardial injury, in an individual, subject or patient. In particular embodiments, myocardial injury status can include determining a patient's myocardial injury status or myocardial injury status, for example, to diagnose myocardial injury, in an individual, subject or patient. More specifically, the biomarkers to be detected in diagnosing myocardial injury include, but are not limited to, GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, S100A9, PRD2, LTF, Exostosin-like 2, cDNAFLI53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Proalctin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelcidin antibmicrobial peptide, Desmoglein-1, Protein-glutamine gamma-glytamyltransferase E, Bleomycin hydrolase, Protein FAM136A, Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig gamma-2 chain C region, Myoglobin, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Insulin-like growth factor-binding protein 1, cDNA FLI75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA, SAA, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12p70, IL-1b, EMC, and LUM. Other biomarkers known in the relevant art may be used in combination with the biomarkers described herein. The present invention further contemplates the detection, measurement, quantification, determination and the like of both unmodified and modified (e.g., glycosylation or other post-translational modification) proteins/polypeptides/peptides as well as autoantibodies to any of the foregoing, determining a patient's myocardial injury status. It is understood that the methods and compositions described herein can not only be used to diagnose myocardial injury.
A. Biomarker Panels
The biomarkers of the present invention can be used in diagnostic tests to assess, determine, and/or qualify (used interchangeably herein) myocardial injury status in a patient. The phrase “myocardial injury status” includes any distinguishable manifestation of the condition, including not having myocardial injury. For example, myocardial injury status includes, without limitation, the presence or absence of myocardial injury in a patient, the risk of developing myocardial injury, the stage or severity of myocardial injury, the progress of myocardial injury (e.g., progress of myocardial injury over time), the effectiveness or response to treatment of myocardial injury (e.g., clinical follow up and surveillance of myocardial injury after treatment). Based on this status, further procedures may be indicated, including additional diagnostic tests or therapeutic procedures or regimens.
In particular embodiments, the biomarkers comprise one or more of GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, S100A9, PRD2, LTF, Exostosin-like 2, cDNAFLI53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Proalctin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelcidin antibmicrobial peptide, Desmoglein-1, Protein-glutamine gamma-glytamyltransferase E, Bleomycin hydrolase, Protein FAM136A, Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig gamma-2 chain C region, Myoglobin, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Insulin-like growth factor-binding protein 1, cDNA FLI75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA, SAA1, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12p70, IL-1b, ECM1, and LUM.
In certain embodiments, the biomarkers comprise one or more of APOA2, BLMH, CAL CAMP, CASP14, CAT, CD38, CDSL, CFP, CHGA, CNDP1, CSRP1, CSTA, CTSL, DBH, DSG1, DSP, ECM1, EXTL2, Fam136A, GAPDH, H2AFZ, HIST1H1B, HIST1H1E, HIST1H4A, HLA-A, ICAM1, IGFB1, IGHG2, IL2, LCN2, LTF, LUM, MATN2, MB, MMP9, MPO, MYH6, MYH7, NPPB, PFN1, PRDX2, S100A12, S100A4, S100A6, S100A7, S100A9, SAA1, SEMG1, TAGLN2, TGM3, TNNI3, VASP, and VCAM1.
The biomarkers can comprise one or more of carbonic anhydrase 1 (CA1), cysteine and glycine-rich protein 1 (CAT1), properdin (CFP), desmoplakin (DSP), extracellular matrix protein 1 (EMC1), lactoferrin (LTF), lumican (LUM), myosin-7 (MYH7), peroxiredoxin-2 (PRDX2), S100A7, S100A9, SAA1, and semenogelin-1 (SEMG1).
In particular embodiments, the biomarkers comprise one or more of Exostosin-like 2 (EXTL2), cDNA FLJ53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5) (CD38), Protein S100-A12 (S100A12), Cysteine and glycine-rich protein 1 (CSRP1), Isoform 2 of Transmembrane protease serine 4 (TMPRSS4), Transgelin-2 (TAGLN2), Profilin-1 (PFN1), Matrix metalloproteinase-9 (MMP9), Protein S100-A4 (S100A4), Histone H1.5 (HIST1H1B), Properdin (CFP), Vasodilator-simulated phosphoprotein (VASP), Myosin-7 (MYH7), Myosin-6 (MYH6), MHC class I antigen (Fragment) (HLA-A), CD5 antigen-like (CDSL), Cystatin-A (CSTA), Cathepsin L1 (CTSL1), Dopamine beta-hydroxylase (DBH), Histone H2A.Z(H2AFZ), Prolactin-inducible protein (PIP), Isoform VCAM-6D of Vascular cell adhesion protein1 (VCAM1), Caspase-14 (CASP14), Regulator of G-protein signaling 19 (RSG19), Cathelicidin antimicrobial peptide (CAMP includes EG:12796), Desmoglein-1 (DSG1)1, Protein-glutamine gamma-glutamyltransferase E (TGM3), Bleomycin hydrolase (BLMH), Protein FAM136A (FAM136A), Isoform H14 of Myeloperoxidase (MPO), Isoform 2 of Neutrophil gelatinase-associated lipocalin (LCN2), Beta-Ala-His dipeptidase (CNDP1), Catalase (CAT), Desmoplakin (DSP), Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Ig gamma-2 chain C region (IGHG2), Myoglobin (MB), Protein S100-A9 (S100A9), Semenogelin-1 (SEMG1), Chromogranin-A (CHGA), Histone H4 (HIST1H4A includes others), Histone H1.4 (HIST1H1E), Protein S100-A7 (S100A7), Apolipoprotein A-II (APOA2), Carbonic anhydrase 1 (CA1), Lactoferrin (LTF), Insulin-like growth factor-binding protein 1 (IGFBP1 includes EG: 16006), cDNA FLJ75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA (MATN2), Peroxiredoxin-2 (PRDX2) and Extracellular matrix protein 1 (ECM1).
The biomarkers can comprise one or more Class I markers shown in Tables 8-10. Such markers include one or more of EXTL2, CD38, S100A12, CSRP1, TMPRSS4, TAGLN2, PFN1, MMP9, S100A4, HIST1H1B, CFP, VASP, MH7, MH6, HLA-A, CDSL, CSTA, CTSL1, DBH, H2AFZ, PIP, VCAM1, CASP14, RGS19, CAMP, DSG1, TGM3, BLMH, FAM136A. The biomarkers can comprise one or more Class II markers shown in Table 10. Such markers include one or more of S100A6, MPO, LCN2, CNDP1, CAT, DSP, GAPDH, IGHG2, MB, S100A9, SEMG1, CHGA, HIST1H4A, HIST1HE, S100A7, APOA2, CA1, LTF, IGFBP1, MATN2 and PRDX2. In alternative embodiments, the biomarkers can comprise one or more Class I markers and one or more Class II markers.
In particular embodiments, the biomarkers can comprise one or more listed in Tables 11-12, specifically, one or more of LTF, S100A9, PRD (also known as PRD-2 or PRDX2), S100A9, and S100A8. Alternatively, the biomarkers can comprise one or more of CA1, CAT, CFP, DSP, ECM1, LTF, LUM, MYH7, PRDX2, S100A7, S100A9, SAA1 and SEMG1 (see Table 5).
In certain embodiments, the biomarkers comprise one or more of ANG, ECM1, LPLUNC1, LTF, LUM, S100A9, PRDX2 and SEMG1. In other embodiments, the biomarkers comprise one or more of APOA2, CA1, CD38, CAT, MMP9, LCN2 (also known as NGAL2), S100A7, and S100A8. The biomarkers can also comprise one or more of CNDP1, CSRP1, EXTL2, S100A1, S100A12, S100A4, S100A6, SH3, THIO, TMPR4 (also known as TMPRSS4). In other embodiments, the biomarkers comprise one or more of the biomarkers described in Example 2-4.
It is understood that the term biomarkers means the protein itself in general, as well as peptides of the biomarker protein. In other words, a biomarker refers to a level of the full length protein. It also refers to the levels of one or more peptides of the protein itself. In certain embodiments, the term biomarkers refers to measuring a level of the full length protein, isoforms thereof, as well as peptides of the foregoing. Such proteins, isoforms and peptides of the foregoing include post-translational modified forms. The PTMs can include citrullination (Cit), oxidation (Oxi), phosphorylation (Phospho), glycosylation, etc. Thus, within the scope of the embodiments listed above and herein, are peptides of the foregoing including PTMs. For example, in certain embodiments, CA1 biomarkers include citrullinated forms as well including, but not limited to, citrullinated peptides such as SEQ ID NOS:1-2. CAT biomarkers also include citrullinated and oxidized forms such as SEQ ID NOS:3-4. See Tables 5 and 6 for additional embodiments. It is understood the embodiments of the present invention include peptides of the proteins described herein including PTMs shown in Tables 5 and 6.
References to biomarkers (full length, isoforms, peptides (including peptides comprising one or more PTMs) can be described in conjunction with the full length (or isoform length) of the biomarker protein. Accession Numbers described herein refer to the accession number useful for searching in databases such as Uniprot. For example, the following biomarkers and associated accession numbers for sequence include Exostosin-like 2 (EXTL2): Q9UBQ6 (SEQ ID NO:1107), B4DNZ2 (SEQ ID NO:1108), C9IYF5 (SEQ ID NO:1109), C9JEG3 (SEQ ID NO:1110), D3DT60 (SEQ ID NO:1111), Q05DH5 (SEQ ID NO:1112), Q49A43 (SEQ ID NO:1113), Q8IYF4 (SEQ ID NO:1114), Q8N8F1 (SEQ ID NO:1115); cDNA FLJ53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5) (CD38): B4E006 (SEQ ID NO:1116); Protein S100-A12 (S100A12): P80511 (SEQ ID NO:1117); Cysteine and glycine-rich protein 1 (CSRP1), P21291 (SEQ ID NO:1118), A8K268 (SEQ ID NO:1119), B4DY28 (SEQ ID NO:1120), B4E2T4 (SEQ ID NO:1121), Q59EQ5 (SEQ ID NO:1122), Q5U0J2 (SEQ ID NO:1123), Q6ZMS3 (SEQ ID NO:1124), Q9BTA4 (SEQ ID NO:1125); Isoform 2 of Transmembrane protease serine 4 (TMPRSS4): Q9NRS4-2 (SEQ ID NO:1126), Q9NRS4-3 (SEQ ID NO:1127), Q9NRS4 (SEQ ID NO:1128), A8K2U6 (SEQ ID NO:1129), B7Z8X1 (SEQ ID NO:1130), B7Z900 (SEQ ID NO:1131); Transgelin-2 (TAGLN2): P37802 (SEQ ID NO:1132); Profilin-1 (PFN1): P07737 (SEQ ID NO:1133), Q53Y44 (SEQ ID NO:1134); Matrix metalloproteinase-9 (MMP9): P14780 (SEQ ID NO:1135), B7Z747 (SEQ ID NO:1136); Protein S100-A4 (S100A4): P26447 (SEQ ID NO:1137), D3DV46 (SEQ ID NO:1138); Histone H1.5 (HIST1H1B): P16401 (SEQ ID NO:1139); Properdin (CFP): P27918 (SEQ ID NO:1140); Vasodilator-simulated phosphoprotein (VASP): P50552 (SEQ ID NO:1141); Myosin-7 (MYH7): P12883 (SEQ ID NO:1142); Myosin-6 (MYH6): P13533 (SEQ ID NO:1143), D9YZU2 (SEQ ID NO:1144); MHC class I antigen (Fragment) (HLA-A): D7NNN8 (SEQ ID NO:1145), D7NNP3 (SEQ ID NO:1146), Q05G04 (SEQ ID NO:1147); CD5 antigen-like (CDSL): 043866 (SEQ ID NO:1148); Cystatin-A (CSTA): P01040 (SEQ ID NO:1149), C9J0E4 (SEQ ID NO:1150), Q6IB90 (SEQ ID NO:1151); Cathepsin L1 (CTSL1): P07711 (SEQ ID NO:1152), A5PLM9 (SEQ ID NO:1153), B3KQK4 (SEQ ID NO:1154), Q5T8F0 (SEQ ID NO:1155); Dopamine beta-hydroxylase (DBH): P09172 (SEQ ID NO:1156); Histone H2A.Z(H2AFZ): POCOSS (SEQ ID NO:1157), Q71UI9 (SEQ ID NO:1158), A6NN01 (SEQ ID NO:1159), C9J0D1 (SEQ ID NO:1160); Prolactin-inducible protein (PIP): P12273 (SEQ ID NO:1161); Isoform VCAM-6D of Vascular cell adhesion protein1 (VCAM1): P19320-2 (SEQ ID NO:1162), P19320 (SEQ ID NO:1163), B4DKS4 (SEQ ID NO:1164), Q53FL7 (SEQ ID NO:1165); Caspase-14 (CASP14): P31944 (SEQ ID NO:1166), B2CIS9 (SEQ ID NO:1167); Regulator of G-protein signaling 19 (RSG19): P49795 (SEQ ID NO:1168), B4DP94 (SEQ ID NO:1169), Q61955 (SEQ ID NO:1170); Cathelicidin antimicrobial peptide (CAMP includes EG:12796): P49913 (SEQ ID NO:1171); Desmoglein-1 (DSG1)1: Q02413 (SEQ ID NO:1172); Protein-glutamine gamma-glutamyltransferase E (TGM3): Q08188 (SEQ ID NO:1173), B4DQ50 (SEQ ID NO:1174), D3DVX1 (SEQ ID NO:1175); Bleomycin hydrolase (BLMH): Q13867 (SEQ ID NO:1176); Protein FAM136A (FAM136A): Q96C01 (SEQ ID NO:1177), BOAZT6 (SEQ ID NO:1178), C9JF51 (SEQ ID NO:1179); Protein S100-A6 (S100A6): P06703 (SEQ ID NO:1180), D3DV39 (SEQ ID NO:1181); Isoform H14 of Myeloperoxidase (MPO): P05164-2 (SEQ ID NO:1182), P05164-3 (SEQ ID NO:1183), P05164 (SEQ ID NO:1184); Isoform 2 of Neutrophil gelatinase-associated lipocalin (LCN2): P80188-2 (SEQ ID NO:1185), P80188 (SEQ ID NO:1186), B2ZDQ1 (SEQ ID NO:1187); Beta-Ala-His dipeptidase (CNDP1): Q96KN2 (SEQ ID NO:1188), A8K1K1 (SEQ ID NO:1189), B4E180 (SEQ ID NO:1190); Catalase (CAT):P04040 (SEQ ID NO:1191), D3DR07 (SEQ ID NO:1192); Desmoplakin (DSP): P15924 (SEQ ID NO:1193); Glyceraldehyde-3-phosphate dehydrogenase (GAPDH): P04406 (SEQ ID NO:1194), Q2TSD0 (SEQ ID NO:1195); Ig gamma-2 chain C region (IGHG2): P01859 (SEQ ID NO:1196); Myoglobin (MB): P02144 (SEQ ID NO:1197), B2RA67 (SEQ ID NO:1198), Protein S100-A9 (S100A9), P06702 (SEQ ID NO:1199), D3DV36 (SEQ ID NO:1200); Semenogelin-1 (SEMG1): P04279 (SEQ ID NO:1201), Chromogranin-A (CHGA): P10645 (SEQ ID NO:1202); Histone H4 (HIST1H4A includes others): P62805 (SEQ ID NO:1203), B2R4R0 (SEQ ID NO:1204), QOVASS (SEQ ID NO:1205); Histone H1.4 (HIST1H1E): P10412 (SEQ ID NO:1206), P16402 (SEQ ID NO:1207), P16403 (SEQ ID NO:1208), A3R0T7 (SEQ ID NO:1209), A3R0T8 (SEQ ID NO:1210), A8K4I2 SEQ ID NO:1211), B2R984 (SEQ ID NO:1212), Q4VB24 (SEQ ID NO:1213); Protein S100-A7 (S100A7): P31151 (SEQ ID NO:1214); Apolipoprotein A-II (APOA2): P02652 (SEQ ID NO:1215); Carbonic anhydrase 1 (CA1): P00915 (SEQ ID NO:1216); Lactoferrin (LTF): Q2TUW9 (SEQ ID NO:1217); Insulin-like growth factor-binding protein 1 (IGFBP1 includes EG: 16006), P08833 (SEQ ID NO:1218), C1K3N3 (SEQ ID NO:1219), C9JXF9 (SEQ ID NO:1220), D3DVL9 (SEQ ID NO:1221), Q6PEY6 (SEQ ID NO:1222); cDNA FLJ75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA (MATN2): A8K106 (SEQ ID NO:1223); Peroxiredoxin-2 (PRDX2): P32119 (SEQ ID NO:1224), B4DF70 (SEQ ID NO:1225); Extracellular matrix protein 1 (ECM1): Q16610 (SEQ ID NO:1226); Intracellular adhesion molecule 1 (ICAM1): P05362 (SEQ ID NO:1227); Interleukin-2 (IL2): P60568 (SEQ ID NO:1228); Lumican (LUM): P51884 (SEQ ID NO:1229); Natriuretic Peptide B (NPPB): P16860 (SEQ ID NO:1230); Serum amyloid A-1 protein (SAA1): P0DJI8 (SEQ ID NO:1231). A skilled artisan can associate a PTM peptide (e.g., in Tables 5 and 6) with a full length (or isoform length) of the biomarker protein described in SEQ ID NOS:1107-1235).
The power of a diagnostic test to correctly predict status is commonly measured as the sensitivity of the assay, the specificity of the assay or the area under a receiver operated characteristic (“ROC”) curve. Sensitivity is the percentage of true positives that are predicted by a test to be positive, while specificity is the percentage of true negatives that are predicted by a test to be negative. An ROC curve provides the sensitivity of a test as a function of 1-specificity. The greater the area under the ROC curve, the more powerful the predictive value of the test. Other useful measures of the utility of a test are positive predictive value and negative predictive value. Positive predictive value is the percentage of people who test positive that are actually positive. Negative predictive value is the percentage of people who test negative that are actually negative.
In particular embodiments, the biomarker panels of the present invention may show a statistical difference in different myocardial injury statuses of at least p<0.05, p<10−2, p<10−3, p<10−4 or p<10−5. Diagnostic tests that use these biomarkers may show an ROC of at least 0.6, at least about 0.7, at least about 0.8, or at least about 0.9.
The biomarkers can be differentially present in UI (NC or non-myocardial injury) and myocardial injury, and, therefore, are useful in aiding in the determination of myocardial injury status. In certain embodiments, the biomarkers are measured in a patient sample using the methods described herein and compared, for example, to predefined biomarker levels/ratios and correlated to myocardial injury status. In particular embodiments, the measurement(s) may then be compared with a relevant diagnostic amount(s), cut-off(s), or multivariate model scores that distinguish a positive myocardial injury status from a negative myocardial injury status. The diagnostic amount(s) represents a measured amount of a biomarker(s) above which or below which a patient is classified as having a particular myocardial injury status. For example, if the biomarker(s) is/are up-regulated compared to normal during myocardial injury, then a measured amount(s) above the diagnostic cutoff(s) provides a diagnosis of myocardial injury. Alternatively, if the biomarker(s) is/are down-regulated during myocardial injury, then a measured amount(s) at or below the diagnostic cutoff(s) provides a diagnosis of non-myocardial injury. As is well understood in the art, by adjusting the particular diagnostic cut-off(s) used in an assay, one can increase sensitivity or specificity of the diagnostic assay depending on the preference of the diagnostician. In particular embodiments, the particular diagnostic cut-off can be determined, for example, by measuring the amount of biomarkers in a statistically significant number of samples from patients with the different myocardial injury statuses, and drawing the cut-off to suit the desired levels of specificity and sensitivity.
In other embodiments, ratios of post-translationally modified biomarkers to the corresponding unmodified biomarkers are useful in aiding in the determination of myocardial injury status. In certain embodiments, the biomarker ratios are indicative of diagnosis. In other embodiments, a biomarker ratio can be compared to another biomarker ratio in the same sample or to a set of biomarker ratios from a control or reference sample.
Indeed, as the skilled artisan will appreciate there are many ways to use the measurements of two or more biomarkers in order to improve the diagnostic question under investigation. In a quite simple, but nonetheless often effective approach, a positive result is assumed if a sample is positive for at least one of the markers investigated.
Furthermore, in certain embodiments, the values measured for markers of a biomarker panel are mathematically combined and the combined value is correlated to the underlying diagnostic question. Biomarker values may be combined by any appropriate state of the art mathematical method. Well-known mathematical methods for correlating a marker combination to a disease status employ methods like discriminant analysis (DA) (e.g., linear-, quadratic-, regularized-DA), Discriminant Functional Analysis (DFA), Kernel Methods (e.g., SVM), Multidimensional Scaling (MDS), Nonparametric Methods (e.g., k-Nearest-Neighbor Classifiers), PLS (Partial Least Squares), Tree-Based Methods (e.g., Logic Regression, CART, Random Forest Methods, Boosting/Bagging Methods), Generalized Linear Models (e.g., Logistic Regression), Principal Components based Methods (e.g., SIMCA), Generalized Additive Models, Fuzzy Logic based Methods, Neural Networks and Genetic Algorithms based Methods. The skilled artisan will have no problem in selecting an appropriate method to evaluate a biomarker combination of the present invention. In one embodiment, the method used in a correlating a biomarker combination of the present invention, e.g. to diagnose myocardial injury, is selected from DA (e.g., Linear-, Quadratic-, Regularized Discriminant Analysis), DFA, Kernel Methods (e.g., SVM), MDS, Nonparametric Methods (e.g., k-Nearest-Neighbor Classifiers), PLS (Partial Least Squares), Tree-Based Methods (e.g., Logic Regression, CART, Random Forest Methods, Boosting Methods), or Generalized Linear Models (e.g., Logistic Regression), and Principal Components Analysis. Details relating to these statistical methods are found in the following references: Ruczinski et al., 12 J.
C. Determining Risk of Developing Myocardial Injury
In a specific embodiment, the present invention provides methods for determining the risk of developing myocardial injury in a patient. Biomarker percentages, ratios, amounts or patterns are characteristic of various risk states, e.g., high, medium or low. The risk of developing myocardial injury is determined by measuring the relevant biomarkers and then either submitting them to a classification algorithm or comparing them with a reference amount, i.e., a predefined level or pattern of biomarkers that is associated with the particular risk level.
D. Determining Myocardial Injury Severity
In another embodiment, the present invention provides methods for determining the severity of myocardial injury in a patient. Each grade or stage of myocardial injury likely has a characteristic level of a biomarker or relative levels/ratios of a set of biomarkers (a pattern or ratio). The severity of myocardial injury is determined by measuring the relevant biomarkers and then either submitting them to a classification algorithm or comparing them with a reference amount, i.e., a predefined level or pattern of biomarkers that is associated with the particular stage.
E. Determining Myocardial Injury Prognosis
In one embodiment, the present invention provides methods for determining the course of myocardial injury in a patient. Myocardial injury course refers to changes in myocardial injury status over time, including myocardial injury progression (worsening) and myocardial injury regression (improvement). Over time, the amount or relative amount (e.g., the pattern or ratio) of the biomarkers changes. For example, biomarker “X” may be increased with myocardial injury, while biomarker “Y” may be decreased with myocardial injury. Therefore, the trend of these biomarkers, either increased or decreased over time toward myocardial injury or non-myocardial injury indicates the course of the condition. Accordingly, this method involves measuring the level of one or more biomarkers in a patient at least two different time points, e.g., a first time and a second time, and comparing the change, if any. The course of myocardial injury is determined based on these comparisons.
F. Patient Management
In certain embodiments of the methods of qualifying myocardial injury status, the methods further comprise managing patient treatment based on the status. Such management includes the actions of the physician or clinician subsequent to determining myocardial injury status. For example, if a physician makes a diagnosis of myocardial injury, then a certain regime of monitoring would follow. An assessment of the course of myocardial injury using the methods of the present invention may then require a certain myocardial injury therapy regimen. Alternatively, a diagnosis of non-myocardial injury might be followed with further testing to determine a specific disease that the patient might be suffering from. Also, further tests may be called for if the diagnostic test gives an inconclusive result on myocardial injury status.
G. Determining Therapeutic Efficacy of Pharmaceutical Drug
In another embodiment, the present invention provides methods for determining the therapeutic efficacy of a pharmaceutical drug. These methods are useful in performing clinical trials of the drug, as well as monitoring the progress of a patient on the drug. Therapy or clinical trials involve administering the drug in a particular regimen. The regimen may involve a single dose of the drug or multiple doses of the drug over time. The doctor or clinical researcher monitors the effect of the drug on the patient or subject over the course of administration. If the drug has a pharmacological impact on the condition, the amounts or relative amounts (e.g., the pattern, profile or ratio) of one or more of the biomarkers of the present invention may change toward a non-myocardial injury profile. Therefore, one can follow the course of one or more biomarkers in the patient during the course of treatment. Accordingly, this method involves measuring one or more biomarkers in a patient receiving drug therapy, and correlating the biomarker levels/ratios with the myocardial injury status of the patient (e.g., by comparison to predefined levels/ratios of the biomarkers that correspond to different myocardial injury statuses). One embodiment of this method involves determining the levels/ratios of one or more biomarkers for at least two different time points during a course of drug therapy, e.g., a first time and a second time, and comparing the change in levels/ratios of the biomarkers, if any. For example, the levels/ratios of one or more biomarkers can be measured before and after drug administration or at two different time points during drug administration. The effect of therapy is determined based on these comparisons. If a treatment is effective, then the level/ratio of one or more biomarkers will trend toward normal, while if treatment is ineffective, the level/ratio of one or more biomarkers will trend toward myocardial injury indications.
In another embodiment of the invention, the methods of the present invention are used as a screen in order to identify a drug (or to improve a cardioplegic solution) that protects the heart from ischemia and necrosis. The detection of one or more of the proteins of the invention in blood (or media if cell culture is used) is indicative of ischemia, and the quantity of the protein(s) is indicative of the severity of the ischemia.
H. Generation of Classification Algorithms for Qualifying Myocardial Injury Status
In some embodiments, data that are generated using samples such as “known samples” can then be used to “train” a classification model. A “known sample” is a sample that has been pre-classified. The data that are used to form the classification model can be referred to as a “training data set.” The training data set that is used to form the classification model may comprise raw data or pre-processed data. Once trained, the classification model can recognize patterns in data generated using unknown samples. The classification model can then be used to classify the unknown samples into classes. This can be useful, for example, in predicting whether or not a particular biological sample is associated with a certain biological condition (e.g., diseased versus non-diseased).
Classification models can be formed using any suitable statistical classification or learning method that attempts to segregate bodies of data into classes based on objective parameters present in the data. Classification methods may be either supervised or unsupervised. Examples of supervised and unsupervised classification processes are described in Jain, “Statistical Pattern Recognition: A Review”, IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 22, No. 1, January 2000, the teachings of which are incorporated by reference.
In supervised classification, training data containing examples of known categories are presented to a learning mechanism, which learns one or more sets of relationships that define each of the known classes. New data may then be applied to the learning mechanism, which then classifies the new data using the learned relationships. Examples of supervised classification processes include linear regression processes (e.g., multiple linear regression (MLR), partial least squares (PLS) regression and principal components regression (PCR)), binary decision trees (e.g., recursive partitioning processes such as CART), artificial neural networks such as back propagation networks, discriminant analyses (e.g., Bayesian classifier or Fischer analysis), logistic classifiers, and support vector classifiers (support vector machines).
Another supervised classification method is a recursive partitioning process. Recursive partitioning processes use recursive partitioning trees to classify data derived from unknown samples. Further details about recursive partitioning processes are provided in U.S. Patent Application No. 2002 0138208 A1 to Paulse et al., “Method for analyzing mass spectra.”
In other embodiments, the classification models that are created can be formed using unsupervised learning methods. Unsupervised classification attempts to learn classifications based on similarities in the training data set, without pre-classifying the spectra from which the training data set was derived. Unsupervised learning methods include cluster analyses. A cluster analysis attempts to divide the data into “clusters” or groups that ideally should have members that are very similar to each other, and very dissimilar to members of other clusters. Similarity is then measured using some distance metric, which measures the distance between data items, and clusters together data items that are closer to each other. Clustering techniques include the MacQueen's K-means algorithm and the Kohonen's Self-Organizing Map algorithm.
Learning algorithms asserted for use in classifying biological information are described, for example, in PCT International Publication No. WO 01/31580 (Barnhill et al., “Methods and devices for identifying patterns in biological systems and methods of use thereof”), U.S. Patent Application Publication No. 2002/0193950 (Gavin et al. “Method or analyzing mass spectra”), U.S. Patent Application Publication No. 2003/0004402 (Hitt et al., “Process for discriminating between biological states based on hidden patterns from biological data”), and U.S. Patent Application Publication No. 2003/0055615 (Zhang and Zhang, “Systems and methods for processing biological expression data”).
The classification models can be formed on and used on any suitable digital computer. Suitable digital computers include micro, mini, or large computers using any standard or specialized operating system, such as a Unix, Windows® or Linux™ based operating system. In embodiments utilizing a mass spectrometer, the digital computer that is used may be physically separate from the mass spectrometer that is used to create the spectra of interest, or it may be coupled to the mass spectrometer.
The training data set and the classification models according to embodiments of the invention can be embodied by computer code that is executed or used by a digital computer. The computer code can be stored on any suitable computer readable media including optical or magnetic disks, sticks, tapes, etc., and can be written in any suitable computer programming language including R, C, C++, visual basic, etc.
The learning algorithms described above are useful both for developing classification algorithms for the biomarkers already discovered, and for finding new biomarker biomarkers. The classification algorithms, in turn, form the base for diagnostic tests by providing diagnostic values (e.g., cut-off points) for biomarkers used singly or in combination.
In another aspect, the present invention provides kits for qualifying myocardial injury status, which kits are used to detect the biomarkers described herein. In a specific embodiment, the kit is provided as an ELISA kit comprising antibodies to one or more of the biomarkers of the present invention including, but not limited to, GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, S100A9, PRD2, LTF, Exostosin-like 2, cDNAFLI53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Proalctin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelcidin antibmicrobial peptide, Desmoglein-1, Protein-glutamine gamma-glytamyltransferase E, Bleomycin hydrolase, Protein FAM136A, Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig gamma-2 chain C region, Myoglobin, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Insulin-like growth factor-binding protein 1, cDNA FLI75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA, SAA, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12p70, IL-1b, EMC, and LUM.
A kit can also comprise antibodies that specifically bind a biomarker comprising a PTM, as opposed to a biomarker protein not having the PTM. In certain embodiments, different antibodies can be used to the same biomarker protein, each antibody recognizing a specific PTM of the biomarker. The PTMS include, for example, citrullination, phosphorylation and oxidation. Post translational modification of carbonic anhydrase 1 (CA1) can include citrullination (ESISVSSEQLAQFR[157] (SEQ ID NO:1), SLLSNVEGDNAVPMQHNNR[157]PTQPLK (SEQ ID NO:2)). PTM of CAT includes citrullination (NAIHTFVQSGSHLAAR[157] (SEQ ID NO:3)) and oxidation (M) (HM[147]N[115]GYGSHTFK (SEQ ID NO:4)). PTM of properdin (CFP) can include oxi (M) (YPPTVSM[147]VEGQGEK (SEQ ID NO:5)). PTM of desmoplakin (DSP) can include citrullination (IGLVR[157]PGTALELLEAQAATGFIVDPVSNLR (SEQ ID NO:6)). PTM of extracellular matrix protein 1 (ECM1) can include citrullination (DILTIDIGR[157] (SEQ ID NO:7), LVWEEAMSR[157] (SEQ ID NO:8), NLPATDPLQR[157] (SEQ ID NO:9), QGETLNFLEIGYSR[157] (SEQ ID NO:10), QHVVYGPWNLPQSSYSHLTR[157] (SEQ ID NO:11)) and citrullination and phosphorylation (Q[129]HVVYGPWN[115]LPQ[129]S[167]S[167]Y[243]S[167]HLT[181]R[157] (SEQ ID NO:12)). PTM of lactoferrin (LTF) can include citrullination (IDSGLYLGSGYFTAIQNLR[157] (SEQ ID NO:13)), VPSHAVVAR[157] (SEQ ID NO:14)) and phosphorylation (S[167]DT[181]S[167]LT[181]W[202]N[115]S[167]VK (SEQ ID NO:15)). PTM of Lumican (LUM) can include citrullination (FN[115]ALQ[129]YLR[157] (SEQ ID NO:16), FNALQYLR[157] (SEQ ID NO:17), SLEYLDLSFNQIAR[157] (SEQ ID NO:18)). PTM of Myosin-7 (MYH7) can include oxidation (M) (IEDMAM[147]LTFLHEPAVLYNLK(SEQ ID NO:19)). Peroxiredoxin-2 (PRD2) PTMs include citrullination (EGGLGPLNIPLLADVTR[157] (SEQ ID NO:20), R[157]LSEDYGVLK(SEQ ID NO:21), TDEGIAYR[157] (SEQ ID NO:22)). S100A7: Oxidation(M) (SIIGM[147]IDM[147]FHK (SEQ ID NO:23), SIIGMIDM[147]FHK) (SEQ ID NO:24); Phosphorylatio (Q[112]S[167]HGAAPCS[167]GGS[167]Q[129] (SEQ ID NO:25)). PTM of S100A9 can include oxidation(M) (QLSFEEFIM[147]LMAR (SEQ ID NO:26)). PTM of SAA1 can include citrullination (FFGHGAEDSLADQAANEWGR[157] (SEQ ID NO:27), GPGGVWAAEAISDAR[157] (SEQ ID NO:28)). PTM of semenogelin-1 (SEMG1) can include citrullination (HLAQHLNNDR[157] (SEQ ID NO:29), HLGGSQQLLHNKQEGR[157] (SEQ ID NO:30)) and citrullination and phosphoryaltion (GES[167]GQ[129]S[167]T[181]N[115]R[157] (SEQ ID NO:31)). Antibodies specific to each of the PTMs shown in Table 6 and Examples 2-4 can be used.
One aspect of the invention is a kit for detecting whether a subject is likely to have myocardial ischemia, comprising one or more agents for detecting the amount of a protein of the invention. In addition, other markers for ischemia (e.g., as discussed elsewhere herein) can also be present in a kit. If mass spectrometry is to be used to measure protein levels, the following reagents can be included in the kit: known amounts of a labeled (e.g., stable isotope) peptide (synthetic or recombinant) standard for each peptide to be assessed, separately or combined into a single mixture containing all peptides; optionally, a different peptide standard for assessing reproducibility of the assay; and/or, optionally, dilutant and trypsin for preparation of the sample. If an antibody-based method is to be used to measure protein levels, the agents in the kit can encompass antibodies specific for the proteins. The kit may also include additional agents suitable for detecting, measuring and/or quantitating the amount of protein, including conventional analytes for creation of standard curves. Among other uses, kits of the invention can be used in experimental applications. A skilled worker will recognize components of kits suitable for carrying out a method of the invention.
Optionally, a kit of the invention may comprise instructions for performing the method. Optional elements of a kit of the invention include suitable buffers, containers, or packaging materials. The reagents of the kit may be in containers in which the reagents are stable, e.g., in lyophilized form or stabilized liquids. The reagents may also be in single use form, e.g., for the performance of an assay for a single subject. In one embodiment of the invention, the kit is a “home chest pain test kit,” that can be used to test blood, urine, or other body fluids for the presence (and/or level) of protein markers of the invention. Thus, a patient who has been released from an Emergency Department (ED) or a cardiac ward, but who is at risk over the next about 48 hours, can take the test over time at home and, if the test produces positive results, return to the ED.
The ELISA kit may comprise a solid support, such as a chip, microtiter plate (e.g., a 96-well plate), bead, or resin having biomarker capture reagents attached thereon. The kit may further comprise a means for detecting the biomarkers, such as antibodies, and a secondary antibody-signal complex such as horseradish peroxidase (HRP)-conjugated goat anti-rabbit IgG antibody and tetramethyl benzidine (TMB) as a substrate for HRP.
The kit for qualifying myocardial injury status may be provided as an immuno-chromatography strip comprising a membrane on which the antibodies are immobilized, and a means for detecting, e.g., gold particle bound antibodies, where the membrane, includes NC membrane and PVDF membrane. The kit may comprise a plastic plate on which a sample application pad, gold particle bound antibodies temporally immobilized on a glass fiber filter, a nitrocellulose membrane on which antibody bands and a secondary antibody band are immobilized and an absorbent pad are positioned in a serial manner, so as to keep continuous capillary flow of blood serum.
In certain embodiments, a patient can be diagnosed by adding blood or blood serum from the patient to the kit and detecting the relevant biomarkers conjugated with antibodies, specifically, by a method which comprises the steps of: (i) collecting a biological sample (e.g., blood or blood serum) from the patient; (ii) separating blood serum from the patient's blood; (iii) adding the blood serum from patient to a diagnostic kit; and, (iv) detecting the biomarkers conjugated with antibodies. In this method, the antibodies are brought into contact with the patient's blood. If the biomarkers are present in the sample, the antibodies will bind to the sample, or a portion thereof. In other kit and diagnostic embodiments, blood or blood serum need not be collected from the patient (i.e., it is already collected). Moreover, in other embodiments, the sample may comprise a tissue sample or a clinical sample.
The kit can also comprise a washing solution or instructions for making a washing solution, in which the combination of the capture reagents and the washing solution allows capture of the biomarkers on the solid support for subsequent detection by, e.g., antibodies or mass spectrometry. In a further embodiment, a kit can comprise instructions for suitable operational parameters in the form of a label or separate insert. For example, the instructions may inform a consumer about how to collect the sample, how to wash the probe or the particular biomarkers to be detected, etc. In yet another embodiment, the kit can comprise one or more containers with biomarker samples, to be used as standard(s) for calibration.
In another specific embodiment, the kit is provided as a PCR kit comprising primers that specifically bind to one or more of the nucleic acid biomarkers described herein. Primers the specifically bind and amplify the target biomarkers described herein include, but are not limited to, one or more of GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, S100A9, PRD2, LTF, Exostosin-like 2, cDNAFLI53119, highly similar to ADP-ribosyl cyclase 1 (EC 3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Prolactin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelcidin antibmicrobial peptide, Desmoglein-1, Protein-glutamine gamma-glytamyltransferase E, Bleomycin hydrolase, Protein FAM136A, Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig gamma-2 chain C region, Myoglobin, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Insulin-like growth factor-binding protein 1, cDNA FLI75188, highly similar to Homo sapiens matrillin 2, transcript variant 2, mRNA, SAA, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12p70, IL-1b, EMC, and LUM. The kit can further comprise substrates and other reagents necessary for conducting PCR (e.g., quantitative real-time PCR). The kit can be configured to conduct singleplex or multiplex PCR. The kit can further comprise instructions for carrying out the PCR reaction(s). In specific embodiments, the biological sample obtained from a subject may be manipulated to extract nucleic acid. In a further embodiment, the nucleic acids are contacted with primers that specifically bind the target biomarkers to form a primer:biomarker complex. The complexes can then be amplified and detected/quantified/measured to determine the levels of one or more biomarkers. The subject can then be identified as having myocardial injury based on a comparison of the measured levels of one or more biomarkers to one or more reference controls.
Without further elaboration, it is believed that one skilled in the art, using the preceding description, can utilize the present invention to the fullest extent. The following examples are illustrative only, and not limiting of the remainder of the disclosure in any way whatsoever.
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices, and/or methods described and claimed herein are made and evaluated, and are intended to be purely illustrative and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for herein. Unless indicated otherwise, parts are parts by weight, temperature is in degrees Celsius or is at ambient temperature, and pressure is at or near atmospheric. There are numerous variations and combinations of reaction conditions, e.g., component concentrations, desired solvents, solvent mixtures, temperatures, pressures and other reaction ranges and conditions that can be used to optimize the product purity and yield obtained from the described process. Only reasonable and routine experimentation will be required to optimize such process conditions.
Table I summarizes the results of 67cardiac injury proteins measured with multiple approaches (protoemic spectra counting via orbitrap, MRM via QTRAP and antibody based multiple technology platforms, ELISA, multiplex, singleplexed and clinical antibody based assay).
Homo
sapiens
Multiple post translational modifications are found in 13 markers. The PTM include citrullination, oxidation and/or phosphorylation of carbonic anhydrase 1 (CA1), cysteine and glycine-rich protein 1 (CAT1), properdin (CFP), desmoplakin (DSP), extracellular matrix protein 1 (EMC1), lactoferrin (LTF), lumican (LUM), myosin-7 (MYH7), peroxiredoxin-2 (PRDX2), S100A7, S100A9, SAA1, and semenogelin-1 (SEMG1). Table 5 listed the nature of the modification, site and peptides sequence of these 13 markers.
Table 6 below summarizes the specific post translational modification, site and peptide sequence of carbonic anhydrase 1 (CA1), cysteine and glycine-rich protein 1(CAT1), properdin (CFP), desmoplakin (DSP), extracellular matrix protein 1 (EMC1), lactoferrin (LTF), lumican (LUM), myosin-7 (MYH7), peroxiredoxin-2 (PRDX2), S100A7, S100A9, SAA1, and semenogelin-1 (SEMG1).
A. Exemplary Markers
Exostosin-Like 2.
IPI ID: IPI00002732; UniProtKB/Swiss-Prot ID: Q9UBQ6. Sequence length: 330 aa, molecular weight: 37466 Da. Subcellular location: Endoplasmic reticulum membrane; Single-pass type II membrane protein, Processed exostosin-like 2: Secreted. Note: A soluble form is found in the serum.
Function: Glycosyltransferase required for the biosynthesis of heparan-sulfate and responsible for the alternating addition of beta-1-4-linked glucuronic acid (GlcA) and alpha-1-4-linked N-acetylglucosamine (GlcNAc) units to nascent heparan sulfate chains.
Alternative names: Alpha-1,4-N-acetylhexosaminyltransferase EXTL2; Alpha-GalNAcT EXTL2; EXT-related protein 2; Glucuronyl-galactosyl-proteoglycan 4-alpha-N-acetylglucosaminyltransferase
Cleaved into the following chain: Processed exostosin-like 2
ADP-Ribosyl Cyclase 1.
UniProtKB/Swiss-Prot: CD38 HUMAN, P28907 (See protein sequence). Recommended Name: ADP-ribosyl cyclase 1. Size: 300 amino acids; 34328 Da. Subcellular location: Membrane; Single-pass type II membrane protein.
Developmental stage: Preferentially expressed at both early and late stages of the B and T-cell maturation. It is also detected on erythroid and myeloid progenitors in bone marrow, where the level of surface expression was shown to decrease during differentiation of blast-forming unit E to colony-forming unit E Function Summary: Synthesizes cyclic ADP-ribose, a second messenger for glucose-induced insulin secretion. Also has cADPr hydrolase activity. Also moonlights as a receptor in cells of the immune system.
Catalytic activity: NAD(+)+H(2)O=ADP-ribose+nicotinamide. Enzyme regulation: ATP inhibits the hydrolyzing activity.
Protein S100-A12.
Protein names: Protein S100-A12. IPI ID: IPI00218131. UniProtKB/Swiss-Prot ID: P80511. Sequence length: 92 aa, molecular weight: 10575 Da.
Function: Calcitermin possesses antifungal activity against C. albicans and is also active against E. coli and P. aeruginosa but not L. monocytogenes and S. aureus. Binds calcium, zinc and copper. Presence of zinc increases the affinity for calcium. Plays an important role in the inflammatory response. Interaction with AGER on endothelium, mononuclear phagocytes, and lymphocytes triggers cellular activation, with generation of key proinflammatory mediators By similarity.
Alternative name(s): CGRP; Calcium-binding protein in amniotic fluid 1 (Short name=CAAF1); Calgranulin-C(Short name=CAGC); Extracellular newly identified RAGE-binding protein (Short name=EN-RAGE); Neutrophil S100 protein; S100 calcium-binding protein A12.
Cysteine and Glycine-Rich Protein 1.
Protein names: Cysteine and glycine-rich protein 1. IPI ID: IPI0442073. UniProtKB/Swiss-Prot ID: P21291 Sequence length: 193 aa, molecular weight: 20567 Da. Subcellular location: Nucleus. Function: Could play a role in neuronal development.
Alternative name(s): Cysteine-rich protein 1 (Short name=CRP; CRP1).
Transmembrane Protease Serine 4.
Protein names: Transmembrane protease serine 4 (EC=3.4.21.−). IPI ID: IPI00221211(isoform 1) (Q9NRS4); IPI00411324(isoform 2) (Q9NRS4-2); IPI0554650(isoform 3) (Q9NRS4-3). Sequence length: 437aa, 432aa, 435aa. molecular weight: 48246 Da, 47686 Da, 48005 Da. Subcellular location: Membrane; Single-pass type II membrane protein. Function: Probable protease. Seems to be capable of activating ENaC.
Alternative name(s): Channel-activating protease 2 (Short name=CAPH2); Membrane-type serine protease 2 (Short name=MT-SP2).
B. Data
The validation study was done with a human valve replacement cohort with 19 subjects and a label-free spectra counting mass spectrometry based method.
1). Method:
The present inventors have identified a number of protein markers for cardiac (myocardial) injury (including non-necrotic cardiac (myocardial) ischemia injury) using a valve replacement model. In this study, ischemia was induced by coronary blockage: subjects undergoing valve replacement surgery exhibited ischemia because of blood loss during the procedure. This procedure mimics naturally occurring events in which ischemia is induced by coronary blood vessel blockage. Coronary sinus serum samples were obtained from individuals (n=19) that underwent aortic valve replacements immediately prior to (T0) and 5 minutes following (T1) removal of the individual from coronary pump bypass. The operative technique was similar in all patients, with an average aortic cross clamp time of 55.6 minutes. For each individual, cross clamp times (time of ischemia), circulating cTnI for T0, T1 and delta TnI (data now shown). The lower limit of detection for the cTnI assay was 0.005 ng/mL.
Each plasma sample was analyzed essentially according to Sheng et al. [11]. Briefly, 20 mg plasma was partitioned using affinity (IgY) chromatography comprising antibodies raised against the top abundant plasma proteins (IgY12-LC10 (Beckman Coulter, # A24355), resulting in approximately 750 mg of depleted sample present in the flow through. 200 mg were separated based on hydrophobicity using 1-dimensional reversed phase high performance liquid chromatography (C18300_A 250_4:6 mm RP column (Phenomenex)). Proteins were separated using 15 minute isocratic gradient at 20% B followed by a linear A/B gradient of 2.0% B/minute (total of 38 analysis) where solvent A was composed of 0.08% aqueous triuoroacetic acid and solvent B consisted of 0.08% triuoroacetic acid in acetonitrile. Fractions were collected, dried down, then resolubilized in neutralizing buffer compatible for tryptic digestion and stored at −80° C. until use. At that time of MS analysis, tryptic digestion was carried out as described in [13].
Each digested fraction was analyzed using the LTQ Orbitrap LC MS/MS instrument (ThermoFinnigan, San Jose, Calif.) using an Agilent 1200 nano-liquid chromatographic system (Agilent, Santa Clara, Calif.) as previously described [11] in duplicate (total of 1216 MS runs). Briefly, peptides were dissolved in 6 μL of buffer A (4% acetonitrile in water with 0.1% formic acid). Samples (3 mL) were loaded onto a 75 mm 10 cm BioBasic C18 column (New Objective, Woburn, Mass.) and eluted using a linear A/B gradient comprising of 5% to 60% B (0.1% formic acid in 90% acetonitrile/water) over 60 minutes. The mass spectrometer was operated in data-dependent mode on randomized patient samples; every FT-MS scan (survey 350-2000 Da) was followed by MS/MS scans of the 5 most abundant ions.
Raw MS data was converted to m/zXML format and searched using the X!Tandem algorithm (version 2009.10.01.1) [14] with the k-score plug-in against the concatenated target/decoy human Uniprot database [15] as of Oct. 22, 2010. The search was performed with the following parameters: Trypsin-based digestion with a maximum of two missed cleavages; parent-ion mass tolerance of 0.1 Da; fragment-ion mass tolerance of 1.0 Da; a modification of cysteine carbamidomethylation and variable states for methionine oxidation, serine phosphorylation, threonine phosphorylation, tyrosine phosphorylation, tryptophan oxidation, methionine dioxidation, tryptophan dioxidation, asparagine deamidation and glutamine deamidation. Software msConvert v2.0.1905 from ProteoWizard was used for peaklist generation; the searched database contained 221992 entries (including decoys, 110996 excluding them).
2). Cardiac Injury and Cardiac Injury Related Markers:
The results from the search were subsequently processed through PeptideProphet for pep tide validation using the Trans Proteomic Pipeline, version v4.4, rev 1. iProphet was used to further improve the identification probabilities, and ProteinProphet was then used to infer protein identifications from the resulting combined peptide list and perform grouping of ambiguous hits. The resulting list includes proteins identified by one or more unique peptides even if found only once and in a single sample. Only those proteins identified by doubly and triply charged ions were considered for the analysis during the initial analysis. Furthermore, the CD-HIT [19] clustering tool was used to cluster highly similar proteins with sequence homology above 90% over the entire protein.
The results of the studies are summarized in Table 7 and Table 8. The results were calculated based on spectra counting ratio of T6/T0. Spectra counting ratio ≥2 is considered to be significant for that particular individual. There are 29 proteins that are found to have induced expression in the blood by supply ischemia (valve replacement procedure) and they are classified as class I cardiac injury markers. These 29 proteins are ischemia induced proteins, their expression in the blood increased only after supply ischemia. The study shows that 29 proteins are referred to herein as “Class I” markers as they released into blood only after injury (Table III). They are: Exostosin-like 2, cDNA FLI53119 (highly similar to ADP-ribosyl cyclase 1 (EC3.2.2.5), Protein S100-A12, Cysteine and glycine-rich protein 1, Isoform 2 of Transmembrane protease serine 4, Transgelin-2, Profilin-1, Matrix metalloproteinase-9, Protein S100-A4, Histone H1.5, Properdin, Vasodilator-stimulated phosphoprotein, Myosin-7, Myosin-6, MHC class I antigen (Fragment), CD5 antigen-like, Cystatin-A, Cathepsin L1, Dopamine beta-hydroxylase, Histone H2A.Z, Prolactin-inducible protein, Isoform VCAM-6D of Vascular cell adhesion protein 1, Caspase-14, Regulator of G-protein signaling 19, Cathelicidin antimicrobial peptide, Desmoglein-1, Protein-glutamine gammaglutamyltransferase E, Bleomycin hydrolase, Protein FAM136A.
Another 28 proteins were referred as “Class II” markers, as they are elevated in >60% of valve replacement cohort (Table IV). The second 21 proteins are classified as cardiac injury class II markers (Table IV). They are Protein S100-A6, Isoform H14 of Myeloperoxidase, Isoform 2 of Neutrophil gelatinase-associated lipocalin, Beta-Ala-His dipeptidase, Catalase, Desmoplakin, Glyceraldehyde-3-phosphate dehydrogenase, Ig, gamma-2 chain C region, Myoglobin, Protein S100-A9, Semenogelin-1, Chromogranin-A, Histone H4, Histone H1.4, Protein S100-A7, Apolipoprotein A-II, Carbonic anhydrase 1, Lactoferrin, Insulin-like, growth factor-binding protein 1, cDNA FLJ75188, highly similar to Homo sapiens matrilin 2, transcript variant 2, mRNA, Peroxiredoxin-2. These proteins present in the blood prior to supply ischemia (valve replacement procedure). Their expression was elevated post cardiac injury induced by supply ischemia. They are cardiac injury related proteins.
indicates data missing or illegible when filed
Cardiac Injury Markers Validation with a MRM assays. SRM (Single Reaction Monitoring) analysis utilizes a triple quadrupole type of instrument to select and analyze a specific analyte (such as a peptide or a small molecule). In SRM analysis, the specificity depends on multiple mass analyzers (mass filters): the first quadrupole is to select the desired parent ion; the third quadrupole is to monitor the (one or more) fragment ion(s). The fragment ion(s) is generated through collisional induced dissociation in the second quadrupole. Therefore, SRM is a highly specific detection/monitoring method with low background interference. When multiple parent ions are monitored in a single MS run, this type of analysis is known as MRM (Multiple Reaction Monitoring). Using MRM analysis, multiple proteins and multiple regions (signature peptides) of a protein can be monitored in a single MS run. MRM is rapidly evolving as an alternative to multiplex immunoassays and is reproducible. MRM eliminates the need for developing immunoassays for an analyte while providing absolute quantification for the specific protein(s) within complex protein mixtures such as serum or plasma. Prior to MRM analysis, proteins present in biofluids (such as plasma or urine) are initially cleaved usually with an enzyme (typically trypsin) although chemical methods can also be used to generate a complex peptide mixture. The peptide mixture is often extracted with a solid phase (such as C18 chromatography) to remove any interference (such as salt) prior to applying to a LC system coupled to a mass spectrometer. In general, there are two approaches in quantification of target proteins and their representative peptides in biological fluids using MRM: (i) absolute quantification with stable isotope labeled peptides as internal standards, and (ii) relative quantification with signal intensities of specific transitions(also known as label free quantification). In the first approach, the peptides are synthesized and labeled with a heavy isotope that will shift the mass of the peptide higher than the endogenous peptide, and a known quantity of this labeled peptide is spiked into the samples. After signal intensities of specific MRM transitions of both labeled peptides and matched endogenous peptides obtained, the quantification is achieved by comparing the relative intensity of samples with that of spiked isotopically labeled standard peptide. For label-free quantification, the quantification is based on relative intensities of specific MRM transitions. In all assays, each peptide and each analyte must perform in a reproducible and accurate manner.
Using isotope labeled heavy peptide as internal standards, we have developed MRM assay for 18 cardiac injury proteins and cardiac injury related proteins (list in the Table 9).
E4; Q6IB90
0188-2; P80188; B2ZDQ1
fD0
indicates data missing or illegible when filed
4.) Verification of Cardiac Injury Markers in Different Cohorts with MRM Analysis.
Valve Replacement Cohort.
S100A9, PRD-2, Lactoferrin, EMC and Lumican levels were measured with plasma samples from the valve replacement cohort. The selected time points of T1, T7 and T9 from all 19 patients' venous plasma were baseline (T1), 30 minutes (T7) and 120 (T9) minutes post Cardiopulmonary Bypass (CPB). The results demonstrate that expression of S100A9, Lactoferrin and Peroxiredoxin were elevated 2-20 fold in CPB patients under going valve replacement procedure (post cardiac injury).
Additional markers GM-CSF, IL-10, IL-2, IL-6, IL-8, TNFa, TnI, sICAM, sVCAM, CRP, NTproBNP, IFNg, IL-12 p70, IL-1b, SAA also measured with antibody based simplex or multiplexed analysis. See
Emergency Department (ED) Cohort).
Patients were admitted to the emergency room complaining of chest pain. Blood samples were collected at T0—at admission, T1—one hour after admission, T2—2 hours after admission, T4—4 hours after admission and T8—8 hours after admission. The time points are tracking biomarker rise and sall. Tables 11 and 12 show results from MRM mass spectrometry based and antibody based analysis of fold of change in MI (myocardial infarction), UA (unstable angina, TnI positive and TnI negative) and NCCP (non-cardiac chest pain). The classification and MI diagnosis were carried by cardiologists.
Extracellular matrix protein (ECM1), Long palate, lung and nasal epithelium carcinoma-1 (LPLUNC1), lactotransferrin (LTF), Lumican (LUM), S100A9, Peroxiredoxin (PRD, PRDX2 or PRD2) and workflow control: Beta-gal protein with three peptides. It is understood that various embodiments of the present invention include performing the MRM described in this Example 2 including analyzing one or more of the peptides described herein, recited transitions, as well as using the parameters described herein. One of ordinary skill in the art can perform the method of Example 2 without undue experimentation.
(APOA2), Carbonic anhydrase 1 (CAL also known as CAH), CD38 ADP-ribosyl cyclase/cyclic ADPribose hydrolase (CD38), Catalase (CATA or CAT), Matrix metalloproteinase-9 (MMP9), Isoform 2 of Neutrophil gelatinase associated lipocalin (NGAL2, also known as LCN2), S100-A7, S100-A8) and workflow control: Beta gal with three peptides). It is understood that various embodiments of the present invention include performing the MRM described in this Example 3 including analyzing one or more of the peptides described herein, recited transitions, as well as using the parameters described herein. One of ordinary skill in the art can perform the method of Example 3 without undue experimentation.
dipeptidase (CNDP1), Cysteine and glycine-rich protein 1 (CSRP1), Exostosin-like 2 (EXTL2), S100A1, S100A12, S100A4, S100A6, SH3 domain-binding glutamic acid rich-like protein (SH3 or SH3L1), Thioredoxin (THIO), Isoform 2 of Transmembrane protease serine 4 (TMPR4, TMPS4 or TMPRSS4) and workflow control Beta gal with three peptides. It is understood that various embodiments of the present invention include performing the MRM described in this Example 4 including analyzing one or more of the peptides described herein, recited transitions, as well as using the parameters described herein. One of ordinary skill in the art can perform the method of Example 4 without undue experimentation.
cDNA FLJ53119, Highly Similar to ADP-Ribosyl Cyclase 1 (EC 3.2.2.5) (CD38)
cDNA FLJ75188, Highly Similar to Homo sapiens Matrillin 2, Transcript Variant 2, mRNA (MATN2)
This application claims the benefit of U.S. Provisional Application No. 62/118,796, filed Feb. 20, 2015, which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2016/018931 | 2/22/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62118796 | Feb 2015 | US |
