The present invention relates to methods for examining a person having the biomarkers indicating Helicobacter pylori infection and/or atrophic gastritis with related risks. More precisely, the present invention relates to methods for improving the analysis steps relating to the screening and detection of the previously mentioned diseases and function of stomach mucosa.
GastroPanel®, the unique Helicobacter pylori test can detect the following conditions:
More precisely, BIOHIT GastroPanel® is a quantitative ELISA test panel that measures the blood plasma concentration of four biological markers of gastric mucosal structure and function: pepsinogen I (PGI), pepsinogen II (PGII), gastrin-17 (G-17) and Helicobacter pylori IgG antibodies. The main indications of use for GastroPanel® are to aid in the diagnosis of and for screening of asymptomatic and symptomatic subjects with 1) H. pylori infection 2) atrophic gastritis (AG) 3) disturbed gastric function.
GastroPanel® is the first-line diagnostic test for Helicobacter pylori (Hp) infection (5-80% of the world population), for examination of all the patients with dyspepsia (20-40% of the western population), as well as for the screening of atrophic gastritis (AG) with related risks, such as stomach- and oesophageal cancer (1-3). Atrophic gastritis also enhances the risk of malabsorption of vitamin B12, iron, magnesium, zinc, calcium and some medicines. The 13C Urea Breath Test (UBT), stool antigen test and antibody tests for Hp infection do not detect atrophic gastritis which is caused by Hp infection or an autoimmune disease nor the level of acid output. In addition, the 13C Urea Breath Test and stool antigen test may give false negative results if the patient has a) atrophic gastritis b) MALT lymphoma c) bleeding peptic ulcer disease or d) if the patient is currently receiving antibiotics or PPIs.
GastroPanel® consists of key stomach-specific biomarkers representing the key regulators of normal stomach physiology. These four biomarkers include pepsinogen I (PGI), pepsinogen II (PGII), amidated gastrin-17 (G-17), and Hp-antibodies, designed to give information on both the structure and function of the stomach mucosa (1-6). Most importantly, this panel gives accurate estimates of the capacity of the corpus and antrum mucosa to secrete gastric acid and G-17, respectively, as well as of important gastric pathologies, like inflammation, grade and topography of atrophic gastritis (7-9), which may represent increased risk of gastric cancer and its clinical sequels (1).
Normal plasma levels of all four biomarkers indicate that the stomach mucosa has normal structure and function, whereas the abnormal levels are signs of a non-healthy stomach, reflecting the disturbances in the feedback mechanisms between the acid output of the corpus, PGs and G-17. For G-17 assessment, there are two options; G-17 basal (G-17b) values, and G-17 stimulated (G-17s) values, the latter being particularly important in distinguishing between functional disturbance of the antrum (G-17s normal) and AG in the antrum (G-17s does not increase in AG)(10,11).
Being the first non-invasive diagnostic test for stomach mucosal health, GastroPanel® is unique also in that the results are interpreted by a software application (GastroSoft) (http://www.gastropanel.com), specifically designed for this purpose. GastroPanel® results are classified into one of five possible diagnostic categories: 1) normal mucosa, 2) superficial (Hp) gastritis, 3) AG in the antrum, 4) AG in the corpus, and 5) AG in both antrum and corpus (pangastritis)(11,12). Thus, GastroPanel® is optimized for use together with the Updated Sydney System (USS) for classification of gastritis, which is based on these same 5 diagnostic categories (13).
GastroPanel® has been validated in several large trials based on biopsy-confirmed gastroscopies (14,15), all included in a recent meta-analysis on the subject (14). These studies have been exploited to establish the validated reference (cut-off) values for each individual biomarkers of the panel, using the five histological categories as endpoints. These studies confirm the high accuracy of GastroPanel in detecting the most important study endpoint, moderate-to-severe AG (14-16). Thus, normal values of PGI, PGII and their ratio (PGI/PGII) preclude AG of the corpus with NPV over 95%. In turn, the values of PGI and PGII as well as their ratio below the established cut-off levels predict moderate-to-severe AG with area under ROC curve (AUC) values above 0.950 in adequately powered and USS validated series (1,2,3,16,17).
In brief, the levels of PGI decrease in AG of the corpus (and in pan-gastritis), but remain within the normal range in all other conditions. Elevated PGII levels reflect mucosal inflammation, the highest values being detected in Hp-associated non-AG. The G-17b values are highest in AG of the corpus, because of the missing negative feedback by the acid output from an atrophic corpus, resulting in uninhibited secretion of G-17b by the normal antral mucosa. The same applies to the situation where acid output is inhibited by prolonged use of PPI medication. By definition, when antral mucosa is atrophic and the G cells are depleted, G-17 secretion remains very low even after protein stimulation (G-17s)(17).
Hp IgG antibodies give significant added diagnostic value to the three biomarkers. IgG serology for Hp measures potentially two different conditions: 1) an ongoing Hp-infection, or 2) a previous exposure to Hp. Although GastroPanel® is not capable of making the distinction between these two, the evidence on Hp involvement gives significant added diagnostic value. As the only abnormal marker, Hp implicates an Hp-associated superficial gastritis (with no AG), while associated with abnormalities in the other three markers, elevated Hp-antibody titers confirm the diagnosis of Hp-associated AG (antrum or corpus)(1,3,18,19).
For more details in interpretation of the GastroPanel® results, please refer to http://www.gastropanel.com.
Also, WO 2009/053537 describes the principle methods and concepts relating to the GastroPanel innovation.
Furthermore, Syrjänen (2016) provides systematic review and meta-analysis of all relevant studies on GastroPanel® in diagnosis of atrophic gastritis and corroborates the statement of international experts, advocating GastroPanel® in diagnosis and screening of AG. Due to its high specificity for both AG of the antrum and AG of the corpus, GastroPanel® is truly a test for stomach health.
In the GastroPanel® test concentrations of four biomarkers are determined from a blood sample. These biomarkers: pepsinogen I (PGI), pepsinogen II (PGII) and gastrin-17 (G17), which are secreted by the cells in gastric mucosa, are measured. Additionally, Helicobacter pylori antibodies are measured. An overall interpretation of all four biomarker results provides more reliable and comprehensive understanding of the structure and function of the gastric mucosa than what could be achieved by using the individual biomarkers separately. The concentrations of these biomarkers should however be determined as soon as possible, or to take care that the samples are properly stored and handled before analyses. It is recommended that the blood sample should be centrifuged within 30 minutes from collection of the sample. A special stabilizer substance should be added to the separated plasma tube to prevent degradation of any of the analytes. The stabilizer enables the storage of the sample at room temperature (20-25° C.) for three days, or in the refrigerator (2-8° C.) for up to seven days. In case of longer delay before analysis, the sample tolerates storage at −20° C. for up to 2 weeks. For any longer storage time, the sample should be kept at −70° C. However, if it is not possible to centrifuge the sample it is not possible to use the stabilizer as the red blood cells become haemolysed. Therefore, the effect of temperature and time during storage and transportation of the whole blood sample is of high interest.
The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.
According to a first aspect of the present invention, there is provided a method for screening of asymptomatic and symptomatic subjects with Helicobacter pylori infection, atrophic gastritis with related risks and/or disturbed gastric function, based on obtaining a whole blood sample, recording of sample collection time, or sample storage temperature, or combination of both, measuring biomarker concentration of interest, and determining an initial biomarker concentration and status of stomach mucosa based on such information.
According to a second aspect of the present invention, there is provided a device or a program which determines the initial biomarker concentration based on measurement of the plasma or serum biomarker concentration, time between whole blood sample collection and plasma or serum sample analysis, and storage temperature of the whole blood sample.
According to a third aspect of the present invention, the initial concentration of a biomarker, such as gastrin-17, determined by such means is used in a non-invasive test for screening of asymptomatic and symptomatic subjects with Helicobacter pylori infection, atrophic gastritis with related risks and/or disturbed gastric function.
The present invention is based on the finding that the concentration of for example gastrin-17 biomarker drops monotonically versus time and temperature. If the concentration is higher than the limit of quantification and the information of the storage temperature and time of sample collection is known, the initial gastrin-17 concentration can be reliably estimated and used for interpreting the results of stomach mucosa health.
These and other aspects, together with the advantages thereof over known solutions are achieved by the present invention, as hereinafter described and claimed.
More precisely, the method of the present invention is characterized by what is stated in claims 1, 2 and 3.
A device or a program according to the present invention is characterized by what is stated in claim 7, and the use according to the present invention by what is stated in claim 9.
Considerable advantages are obtained by means of the invention. For example, blood samples do not require immediate centrifugation for separation of plasma or serum for further analysis. Instead, samples can be collected, stored and sent for further analysis as whole blood samples without processing them first. In the analysis step where the biomarkers are then measured, the time of sample collection and storage temperature are used to interpret and correct the obtained results, which may have been affected by for example protein degradation. This makes the actual clinical work less time-depending and time-consuming, and also saves costs. For example, it is not required to do the analysis of each sample on-site where the blood sample is taken, but just to collect samples to be processed and analyzed later on. Also internal logistics in the research unit are thus improved. In addition, blood samples do not require stabilizers for storage purposes, but instead can be stored at for example room temperature as whole blood samples before further analytical use.
Next, the present technology will be described more closely with reference to certain embodiments.
The present technology relates to the effect of temperature and time during storage and transportation of whole blood samples, when examining a person having or assuming to have the GP biomarkers indicating a Helicobacter pylori infection and/or atrophic gastritis with related risks.
It has been shown that pepsinogen I, pepsinogen II and Helicobacter pylori stands well without substantial degradation for few days storage at normal room temperature, unlike gastrin-17, as illustrated in
More precisely,
Storage/transportation temperature has significant effect on the gastrin-17 degradation rate as shown in
One embodiment of the present invention is a method for screening of asymptomatic and symptomatic subjects with Helicobacter pylori infection, atrophic gastritis with related risks and/or disturbed gastric function, said method including the steps of:
Another embodiment of the present invention is a method for screening of asymptomatic and symptomatic subjects with Helicobacter pylori infection, atrophic gastritis with related risks and/or disturbed gastric function, said method including the steps of:
Yet another embodiment of the present invention is a method for screening of asymptomatic and symptomatic subjects with Helicobacter pylori infection, atrophic gastritis with related risks and/or disturbed gastric function, said method including the steps of:
A method, wherein in addition to gastrin-17 concentration also concentrations of pepsinogen I, pepsinogen II and Helicobacter pylori IgG antibodies are determined from the plasma or serum sample, belongs to the scope of the present invention.
One suitable, but not limited to, analytical function for estimating the initial concentration of the samples is as follows. If assumed that the concentration decrease is proportional to the number of molecules
where
N(t)=N0e−kt, where
N(t, T)=N0e−ktf(T), where
The half time
and k(T) can be estimated from the measured data.
As the concentration drops monotonically vs time and temperature, and if the concentration is higher than the Limit of Quantification (LoQ), and information of the storage temperature and time of sample collection is known, it is possible to estimate the initial concentration and use that information when interpreting the results.
According to one embodiment of the present invention, high (vs the reference range) gastrin-17 concentration indicates acid-free stomach. If a sample that has been stored for some time before measurement still gives high concentration value, also the initial concentration must have been high. Such a situation is illustrated by the sample BN1999 in the
Further, if it is sure that the temperature chain has not exceeded certain temperature, it can predict concentration vs. reference range, and enable the use of that when interpreting the results. For example, when sample BN1998 in
Furthermore, if it is assumed that the sample has been stored for 24 hours before measurement, and the value is about 2 pmol/l, it indicates that the acid content of the stomach is normal, less than the upper limit of the reference range.
However, if the measured concentration is below the LoQ, it is not possible to predict the initial concentration. In that case the gastrin-17 results cannot be used for the interpretation. The GastroPanel® interpretation must then be made based on the other biomarker values.
According to one embodiment the whole blood sample is collected and stored without stabilizers.
According to one embodiment the time period between whole blood sample collection and further analysis from the plasma or serum sample is between 0 to 120 hours, more preferably between 0 to 72 hours and most suitably between 0 to 48 hours.
According to one embodiment the whole blood sample is collected and stored at temperatures between 0 to 30° C., for example at 4° C., 21° C. or 30° C., before the separation of plasma and/or serum and analysis of the biomarker concentrations.
A device or a program which determines an initial biomarker concentration based on measurement of plasma or serum biomarker concentration, time between whole blood sample collection and plasma and/or serum sample analysis, and storage temperature of the whole blood sample belongs to the scope of the present invention.
Preferably, the plasma or serum biomarker concentration is above the limit of quantification, the time between whole blood sample collection and plasma and/or sample analysis is between 0 to 48 hours, and the storage temperature of the whole blood sample is between 0 to 30° C.
Thus, such device or program may be for example GastroSoft program, which is designed for interpreting GastroPanel results, which has been modified to take into consideration the above mentioned essential parameters of the present invention.
One further embodiment of the present invention is to use the methods as disclosed in a non-invasive test for screening of asymptomatic and symptomatic subjects with Helicobacter pylori infection, atrophic gastritis with related risks and/or disturbed gastric function.
It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.
Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.
As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.
While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.
The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, that is, a singular form, throughout this document does not exclude a plurality.
At least some embodiments of the present invention find industrial application for example in screening and examination of patients with dyspepsia, as well as for the screening and detection of atrophic gastritis (AG) with related risks, such as stomach- and oesophageal cancer.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/FI2016/050800 | 11/14/2016 | WO | 00 |