The present invention refers to p53 sequence and post translational modifications (PTMs) and to their use as biomarkers in the diagnosis of a neurodegenerative disease and cognitive decline to Alzheimer's disease and Alzheimer's disease and/or in the prognosis of Alzheimer's disease at different stages and/or of neurodegenerative disease in a biological sample. The invention also provides for a diagnostic method based on a highly accurate mass spectrometry analysis for the diagnosis of neurodegenerative disease, including Mild Cognitive Impairment (MCI), Alzheimer's disease (AD), fronto-temporal dementia (FTD), Lewi's Body (LB), and vascular dementia (VD) in a subject, by evaluating the changes (PTMs) to said p53 linear protein sequence specifically in a biofluid sample. The invention also provides for a diagnostic method based on a highly accurate mass spectrometry analysis for the prognosis of Alzheimer's disease (AD) at asymptomatic and prodromal stages (MCI) by evaluating the changes of said PTMs to the linear sequence of p53 protein specifically in a biofluid sample.
The confirmation of the presence of a large amount of altered conformational p53 isoform as an early risk factor for Alzheimer's disease (shortly ‘AD’) have been demonstrated in different published studies [1-3]. Initially, more than 400 subjects among AD, Mild Cognitive Impairment, Parkinson Disease, other Dementia and healthy subjects were enrolled in different independent studies and tested for Unfolded p53 by using different techniques (immunoprecipitation experiments, FACS analysis, ELISA) with a commercial conformational specific anti-p53 antibody [4-7]. In 2006 for the first time Uberti et al. [8], demonstrated that fibroblasts from sporadic Alzheimer's disease (AD) patients specifically expressed an anomalous and detectable conformational state of p53 that differentiate these cells from fibroblasts of age-matched non-AD subjects. In this conformational altered state, p53 lost its ability to transactivate its target genes, and consequently its biological functions [9-10]. The higher amount of unfolded p53 was also confirmed in blood of AD compared to healthy-non demented subjects or patients affected by other dementia and PD, as well as in MCI converted to AD.
Altogether these data suggested a direct association between Unfolded p53 and AD pathology.
In EP3201234B1, it has been reported the development of a new conformational specific anti-Up53 antibody named 2D3A8, that binds to an epitope (aa 282-297), accessible only when p53 loses its wild type conformation towards an unfolded phenotype. Comparing to the commercial antibody used at the beginning of Unfolded p53 discovering in AD (PAb240, aa214-217), the 2D3A8 antibody showed higher sensitivity and specificity in identifying AD patients compared to healthy elderly in Oviedo cohort.
In particular, said immunodiagnostic method is able to identify immunocomplex in a biological sample that are indicative of AD and to determine the predisposition of a subject affected by Mild Cognitive Impairment (MCI) to develop AD.
PCT/IB2019/051785 discloses a method based on the identification and quantification of the levels of specific p53 peptides, indicated as “P1” and “P2”, that have been detected by mass spectrometry analysis in human plasma of patients affected by Alzheimer's disease or patients that have symptoms that can predispose to the development of AD.
There is now the need of identifying new specific biological markers that can be used in the diagnosis and/or prognosis of Alzheimer's disease and of developing an accurate and sensible diagnostic method that can be used for the diagnosis and/or prognosis of AD, in particular at the pre-clinical and prodromal stages of the disease and for the differential analysis of AD from other forms of dementia, such as Frontotemporal Dementia, Levy Body dementia and vascular dementia.
The object of the present invention has been achieved by identifying eleven main post-translation modifications (PTMs) in the amino acidic sequence of the p53 protein within the region of amino acids 1-371, herein called PTM-1, PTM-2, PTM-3, PTM-4, PTM-5, PTM-6, PTM-7, PTM-8, PTM-9, PTM-10, PTM-11 and/or some truncated forms of the p53 protein in a biofluid sample.
An aspect of the present invention therefore relates to a diagnostic method based on the identification of said PTMs for use in the diagnosis of different forms of dementia and cognitive decline and/or in the prognosis of Alzheimer's disease at different stages.
The characteristics and the advantages of the present invention will become apparent from the following detailed description and the working examples provided for illustrative purposes, as well as the annexed Figures, wherein:
The sequences reported in the figures correspond to the linear sequence of SEQ ID N: 1.
With the term “U-p53” it is meant to denote the region of amino acids 1-371 of the p53 protein, which involves the post translational modifications (PTMs), and in some cases also a truncation, on linear protein sequence as described below.
With term “p53” it is meant the wild-type protein p53 as following the Database “UniProtKB, Protein ID: P04637, amino acids: 1-393”.
With the term “neurodegenerative disease” it is meant to denote a range of conditions that mainly affect the neurons in the human brain, also comprising forms of dementia, such as Mild Cognitive Impairment (MCI), fronto-temporal dementia (FTD), Lewi's Body (LB), and vascular dementia (VD), as well as the different stages of the said neurodegenerative diseases and cognitive decline to dementia, and Alzheimer's disease (AD) (including pre-clinical and prodromal stages).
The invention therefore relates to a combination of p53 post translational modifications detected by a highly accurate mass spectrometry method that can be used as biomarkers in an in vitro o ex vivo method for the diagnosis of a neurodegenerative disease. Said method is based on the identification of specific p53 modifications compared to its linear sequence, shorty referred to as ‘PTMs’, that have been detected by mass spectrometry analysis in a biofluid sample derived from patients affected by Alzheimer's disease or patients that have symptoms that can predispose to the development of AD or to different forms of dementia.
In particular, first, p53 protein is captured by immunoprecipitation in a biofluid sample from patients at pre-clinical, prodromal clinical stages of Alzheimer's, Mild Cognitive Impairment (MCI) stable patients, and cognitive unimpaired subjects (CU), Frontotemporal Dementia (FD), Vascular Dementia (VD) and Lewy Body Dementia (LB). Then, the post translational modifications of the captured protein are identified by protein sequencing with a highly sensitive selective mass spectrometry method. After sequencing, the post translational modifications are also identified by a database searching to check ones already described in literature.
The data obtained for each sample are then compared with PTMs detected in the biofluid samples from subjects with same clinical evidence showing a correlation between “PTMs and diagnosis”, therefore demonstrating a strong evidence that the U-p53 PTMs can be considered as highly reliable biomarkers in the prognosis and diagnosis of a neurodegenerative disease.
Said method is advantageously fast, requires a small volume of biofluid sample and reliably identifies U-p53 PTMs in each sample analysed.
Furthermore, the method and the biomarkers identified can be used also in the diagnosis and prognosis of Alzheimer's disease in asymptomatic individuals and people suffering from MCI, thus allowing the access to the diagnostics market.
Furthermore, the method and the biomarkers identified can be used also for differentiating Alzheimer's disease, from other forms of dementia, such as LB, VD, FTD in demented patients. In fact, as it will be seen below, the U-p53 protein sequence in biofluid samples of patients affected by Alzheimer's disease shows a variability in terms of length within the region of amino acids 1-271, said variability including a truncation within the same region. It should be appreciated that said variability and truncation are peculiar of Alzheimer's disease, as the same are not detected in biofluid samples of patients affected by other forms of dementia, much less in cognitive unimpaired subjects. At the same time, a residual amount of U-p53 in the biofluid samples keeps its sequence length, whereon peculiar PTMs of Alzheimer's disease are detected. It follows that patients affected by Alzheimer's disease are unequivocally identified and distinguished from other dementia patients, insofar as the former show both a truncation in the U-p53 protein sequence and peculiar PTMs in the residual amount of untruncated U-p53 protein.
In addition, since said biomarkers can be used in the prognosis of cognitive decline to Alzheimer's Dementia in asymptomatic and MCI subjects and in the diagnosis of neurodegenerative disease as the dementia, said method advantageously allows the use of a U-p53 PTMs to select the subjects in clinical trials to enable success of the trial and to differentiate patients affected by AD from other forms of dementia as LB, VD, FTD.
The present invention thus relates to an in vitro or ex vivo method for the diagnosis or prognosis of a neurodegenerative disease, the method comprising the steps of:
According to the present invention, preferably in the in vitro or ex vivo method:
In a preferred embodiment, the in vitro or ex vivo method of the present invention is for differentiating Alzheimer's disease, from other forms of dementia, such as LB, VD, FTD in demented patients. In fact, as said above, the assessment of following criteria are indicative of AD:
Said truncation, mainly due to biological reactions, does not affect the detectability of PTMs in said residual amount of untruncated sequence.
As said above, it should be appreciated that said variability and truncation are peculiar of Alzheimer's disease, as the same are not detected in biofluid samples of patients affected by other forms of dementia. At the same time, a residual amount of U-p53 in the biofluid samples keeps its sequence length, whereon peculiar PTMs of Alzheimer's disease are detected. It follows that patients affected by Alzheimer's disease are unequivocally identified and distinguished from other dementia patients, insofar as the former show both a truncation in the U-p53 protein sequence and peculiar PTMs in the residual amount of untruncated U-p53 protein.
Preferably, in the in vitro or ex vivo method of the present invention, the presence of all PTM-2, PTM-7, PTM-8, and PTM-11 is indicative of a cognitive unimpaired subject (CU).
Preferably, in the in vitro or ex vivo method of the present invention the presence of PTM-1, and PTM-10 is indicative of MCI.
Preferably, in the in vitro or ex vivo method of the present invention the presence of at least two PTMs selected from PTM-4, PTM-5, and PTM-9 is indicative of an asymptomatic subject having the prognosis of cognitive decline of Alzheimer's dementia (AD), more preferably the presence of all PTM-4, PTM-5, and PTM-9. In this regard, it should be appreciated that the method of the invention allows the cognitive unimpaired subject (CU) to be identified and distinguished from the asymptomatic subject having the prognosis of cognitive decline of Alzheimer's dementia, although both subjects are formally asymptomatic and accordingly not distinguishable from each other through conventional cognitive tests.
Preferably, in the in vitro or ex vivo method of the present invention the presence of at least two PTMs selected from PTM-1, PTM-3, PTM-5, PTM-6, and PTM-10 is indicative of MCI with a prognosis of cognitive decline of AD, more preferably the presence of all PTM-1, PTM-3, PTM-5, PTM-6, and PTM-10.
Preferably, in the in vitro or ex vivo method of the present invention the presence of PTM-5, and PTM-9 is indicative of FTD.
Preferably, in vitro or ex vivo method of the present invention the presence of PTM-5, and PTM-6 is indicative of LB.
Preferably, in the in vitro or ex vivo method of the present invention the presence of PTM-4, and PTM-5 is indicative of VD.
Preferably, said biofluid is blood, plasma, serum, saliva, urine, neuronal cells, blood cells or other types of cells.
According to a preferred embodiment, in the step a) of the in vitro or ex vivo method of the present invention, the p53 protein is captured in a biofluid sample by performing the following sub-steps of:
In a preferred embodiment, the p53 protein in step a) is the U-p53 in a misfolded conformation.
Preferably, the antibody of sub-step (ii) is a conformationally specific antibody that binds to a p53 peptide, more preferably is a monoclonal/polyclonal antibody. In preferred embodiments, said monoclonal antibody is the antibody 2D3A8.
The amino acid sequences of the 2D3A8 antibody include the heavy chain (SEQ ID NO: 7) and light chain (SEQ ID NO: 8), heavy chain variable region (SEQ ID NO: 9) and light chain variable region (SEQ ID NO: 10), heavy chain CDRs 1, 2 and 3 (SEQ ID NOs: 11, 12 and 13, respectively) and light chain CDRs 1, 2 and 3 (SEQ ID NOs: 14, 15 and 16, respectively).
Preferably, the biological sample of step a) is subjected to protein plasma depletion by HPLC or chromatographic columns or chemical treatment, before performing step (ii). In a preferred embodiment, in the step c) of the method of the present invention, the detected PTMs are correlated with the diagnosis/prognosis of Alzheimer's disease in a patient at different stages of the diseases or cognitive decline due to dementia.
Preferably, in the step c) the detected PTMs are correlated with the prognosis of cognitive decline of Alzheimer's disease in asymptomatic individuals and subjects suffering from MCI.
In a further aspect, the present invention also relates to a diagnostic kit to be used for the implementation of the in vitro or ex vivo method above described, the kit comprising the reagent set to perform the immunoprecipitation including an antibody, the digestion of the protein (preferably trypsin with/without Lys C), elution buffer to precipitate the protein captured by the antibody, and an injection buffer.
In further aspects, the present invention also relates to a method for detecting neurodegenerative disease or development of neurodegenerative disease in a subject by identifying the type of post-translational modifications (PTMs) in the region of amino acids 1-371 of the p53 protein (U-p53) present in a sample from said subject, the method comprising the steps of:
According to the present invention, preferably in said method said PTM-1 has a group CO—CH3 branched to the amino acid M1 of the p53 protein; said PTM-2 has a group CO—CH3 branched to the amino acid K164 of the p53 protein; said PTM-3 has a group CO—CH3 branched to the amino acid K370 of the p53 protein; said PTM-4 has a ubiquitination site [GG] branched at the amino acid K101 of the p53 protein; said PTM-5 has a ubiquitination site [GG] branched 10 at the amino acid K120 of the p53 protein; said PTM-6 has a ubiquitination site [GG] branched at the amino acid K132 of the p53 protein; said PTM-7 has a ubiquitination site [GG] branched at the amino acid K139 of the p53 protein; said PTM-8 has a ubiquitination site [GG] branched at the amino acid K291 of the p53 protein; said PTM-9 has a ubiquitination site [GG] branched at the amino acid K357 of the p53 protein; said PTM-10 has phosphorylation at the amino acid S6 of the p53 protein; and said PTM-11 has phosphorylation at the amino acid S33 of the p53 protein.
Preferably in said method, said at least two PTMs detected in step (c) are selected from the group consisting of PTM-1, PTM-3, PTM-4, PTM-5, and PTM-6, said detection being indicative of Alzheimer's disease (AD) or prognosis of AD.
Preferably in said method, said at least two PTMs detected in step (c) are selected from the group consisting of PTM-1, and PTM-10, said detection being indicative of MCI. Preferably in said method, said sample is from a subject who exhibits no symptoms of AD, wherein said at least two PTMs detected in step (c) are selected from the group consisting of PTM-4, PTM-5, and PTM-9, said detection being indicative of a prognosis of cognitive decline to AD.
Preferably in said method, said at least two PTMs detected in step (c) are selected from the group consisting of PTM-1, PTM-3, PTM-5, PTM-6, and PTM-10, said detection being indicative of MCI with a prognosis of cognitive decline to AD.
Preferably in said method, said at least two PTMs detected in step (c) are selected from the group consisting of PTM-5, and PTM-9, said detection being indicative of FTD.
Preferably in said method, said at least two PTMs detected in step (c) are selected from the group consisting of PTM-5, and PTM-6, said detection being indicative of LB.
Preferably in said method, said at least two PTMs detected in step (c) are selected from the group consisting of PTM-4, and PTM-5, said detection being indicative of VD.
Preferably in said method, said sample is selected from the group consisting of blood, plasma, serum, saliva, urine, neuronal cells.
Preferably in said method, said protease is trypsin.
Preferably in said method, said detection of step (c) is performed by one or more of HPLC-mass spectrometry, Peptide Mass Fingerprint and Database search.
Preferably in said method, said antibody is a monoclonal antibody, more preferably it is 2D3A8.
Preferably in said method, said sample is subjected to protein plasma depletion by HPLC or chromatographic columns or chemical treatment, prior to performing steps (a) to (c). In further aspects, the present invention also relates to a kit for detecting neurodegenerative disease or development of neurodegenerative disease in a subject, the kit comprising a reagent set to perform immunoprecipitation, said reagent set comprising an anti-human p53 antibody capable of binding to an amino acid sequence defined by amino acids 282-297 of U-p53, preferably wherein said anti-human p53 antibody being a monoclonal antibody, more preferably said monoclonal antibody being 2D3A8.
It should be also understood that all the combinations of preferred aspects of the peptides of the invention, as well as of the preparation processes, kit and methods using of the same, as above reported, are to be deemed as hereby disclosed.
All combinations of the preferred aspects of the PTMs of the invention, preparation processes, kit and methods disclosed above are to be understood as herein described. Below are working examples of the present invention provided for illustrative purposes.
The analysis relates to the identification of the U-p53 protein sequence and of its post translational modifications when extracted from plasma of cognitive unimpaired subjects (CU), of patients affected by AD, of other forms of dementia (FTD, LB and VD) and from individuals with Mild Cognitive Decline (MCI), from MCI patients with a prognosis of cognitive decline of AD (MCI to AD) and from patients with a prognosis of cognitive decline of an asymptomatic AD (CU to AD).
Protein sequence and PTM data is obtained using the SANIST-prot tool operating in bottom up conditions.
The plasma samples of 7 patients affected by AD, 5 cognitive unimpaired (CU), 2 patients affected by MCI, 6 frontal dementia (FD), 1 patient with vascular dementia (VD) and 1 patient with Lewy Body dementia (LB) and 6 patients with MCI to AD and 6 patients CU to AD have been treated with the experimental protocol based on protein L to isolate protein p53 disclosed above. Said protein has been exposed to double enzymatic digestion (Lys-C+trypsin) in order to maximize the peptide recovery.
1. U-p53 Protein Immunocaptured from Subjects AD
The p53 protein extracted from AD individuals results truncated in the region of amino acid 1-248 with respect to the wt p53 protein (SEQ ID NO: 1) Database: UniProtKB, Protein ID: P04637, amino acids: 1-393). Different mistakes of enzymatic digestion have been reported that lead to the presence of variable regions, inter-subjects, between the residuals 249-371 of the truncated protein.
In Table 2 are reported the p53 linear sequences identified in AD patients and the respective molecular weight (MW).
2. U-p53 Immunocaptured from Cognitive Unimpaired (CU) and Cognitive Unimpaired to AD Patients.
The linear sequence of p53 extracted from 5 Cognitive unimpaired patients and 6 Cognitive unimpaired later declined to AD correspond to the entire sequence with 1-371 amino acids (SEQ ID N. 6), with a molecular weight of 41134 Da. No residuals corresponding to the region 372-391 have been identified. Table 3 reports the linear sequences obtained from the Cognitive unimpaired and Cognitive unimpaired to AD patients.
3. U-p53 Protein Immunocaptured from Subjects Affected by Fronto-Temporal Dementia, Lewy Body's Dementia, Vascular Dementia, Mild Cognitive Decline (MCI) and MCI to AD
The results obtained from 16 subjects (6 with frontotemporal dementia, 1 with vascular dementia, 1 with Lewy Body's dementia, 2 MCI subjects and 6 MCI who developed AD) report the presence of the whole protein of 1-371 residuals. Table 4 reports the linear protein sequences of the tested subjects.
4. Description of the PTMs Observed from the Immunocaptured Protein
The extracted and sequenced p53 protein from the different clinical groups in addition to a different linear sequence, corresponding accordingly to different molecular weight, also showed post-transductional modifications (PTMs), mainly characterized by ubiquitination, acetylation and phosphorylation on specific amino acid residues. The samples belonging to the same clinical group also showed a highly homogeneity in the PTMs, which in combination with the same protein sequence represent an element characterizing the clinical group to which they belong.
In
Under-expressed peptide sequences belonging to the amino acid region 1-248 were detected in AD patients. Given their low abundance, they could derive from whole sequence of p53 proteins that are believed to be weakly interacting with the antibody. The protein sequence has several ubiquitination sites indicated with the notation “*” in
The Ubiquitination Sites Detected in Cognitive Unimpaired Samples are Reported in
The ubiquitination sites detected in FTD samples are reported in
The ubiquitination sites detected in LB samples are reported in
The ubiquitination sites detected in VD samples are reported in
The ubiquitination sites detected in MCI samples are reported in
The protein ubiquitination sites detected in the samples of cognitively healthy subjects who developed AD over a period of 18-72 months are shown in
The ubiquitination sites detected in MCI subjects who developed AD are reported in
From the data obtained we can observe that there were cumulatively 11 PTMs spanning the full sequence of the protein. Peptides spanning the protein up 371 residues were detected in all samples, however the peptides belonging to the region 1-248 residues AD patients seemed to be cut from the protein not as consequence of enzymatic digestion due to the analytical protocol but due to biological process of full p-53 protein. Amino acids in the region from 372 to the end of the p-53 protein was missing in all samples belonging to different clinical groups.
The PTMs observed in the different patients are disclosed in Table 5 (Y=detected; N=not detected)
In Journal of Alzheimer's Disease. pp. 93-99.
Number | Date | Country | Kind |
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102020000018544 | Jul 2020 | IT | national |
Sequence listing ASCII file 00519PTITWO-seq1-000001.txt, created Jul. 11, 2023 and of size of 19,913 bytes is incorporated herein by reference. This application is a U.S. national stage of PCT/IB2021/056792 filed on 27 Jul. 2021, which claims priority to and the benefit of Italian Application No. 102020000018544 filed on 30 Jul. 2020, the contents of which are incorporated herein by reference in their entireties.
Filing Document | Filing Date | Country | Kind |
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PCT/IB2021/056792 | 7/27/2021 | WO |