EP2488865A1 - Anticorps associé à la pancréatite auto-immune et ses utilisations - Google Patents
Anticorps associé à la pancréatite auto-immune et ses utilisationsInfo
- Publication number
- EP2488865A1 EP2488865A1 EP10770878A EP10770878A EP2488865A1 EP 2488865 A1 EP2488865 A1 EP 2488865A1 EP 10770878 A EP10770878 A EP 10770878A EP 10770878 A EP10770878 A EP 10770878A EP 2488865 A1 EP2488865 A1 EP 2488865A1
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- EP
- European Patent Office
- Prior art keywords
- seq
- peptide
- antibodies
- patients
- aip
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
- G01N33/564—Immunoassay; Biospecific binding assay; Materials therefor for pre-existing immune complex or autoimmune disease, i.e. systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, rheumatoid factors or complement components C1-C9
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2800/00—Detection or diagnosis of diseases
- G01N2800/06—Gastro-intestinal diseases
- G01N2800/067—Pancreatitis or colitis
Definitions
- the present invention relates a method for detecting antibodies specific for a peptide newly identified as a marker of autoimmune pancreatitis.
- the method allows to discriminate between a subject affected by autoimmune pancreatitis from a subject affected by pancreatic adenocarcinoma or other autoimmune diseases such as systemic sclerosis or rheumatoid arthritis.
- AIP Autoimmune pancreatitis
- AIP may mimic pancreatic carcinoma and the differential diagnosis may be difficult.
- Serological markers of the disease include non organ specific autoantibodies (ANA) 7 and organ specific autoantibodies, such as anti-carbonic anhydrase, 7"9 lactoferrin 7 and anti-pancreatic secretory trypsin inhibitor. 10 These organ specific autoantibodies have been found in AIP, but none of them has provided a satisfactory specificity and sensitivity. IgG4 has been proposed as a possible diagnostic marker, 11 but later studies have not confirmed this previous report. 12 ' 13 Therefore, the identification of a serological marker for AIP is a major goal in clinical research.
- the cause of the disease is still unknown.
- the autoimmune origin for AIP has been suggested but never proven and little is known about its pathogenesis.
- the present invention identifies a serological marker able to discriminate AIP from pancreatic adenocarcinoma.
- the authors have used a molecular biology approach that has already been successfully applied to other autoimmune diseases. 14"17
- peptide AIP i_ 7 (SKDER F, SEQ ID NO. 2) was recognized by 18/20 AIP patients' sera, and by 4/40 sera of patients with pancreatic cancer (PC) but not by sera of normal donors.
- the peptide showed homology with an amino acid sequence of plasminogen-binding protein (PBP) of Helicobacter pylori (NCBI (national center accession number 025249) and with human UBR2 (NCBI accession number Q8IWV8), a protein ubiquitination enzyme highly expressed in acinar cells of the pancreas.
- PBP plasminogen-binding protein
- NCBI National center accession number 025249
- human UBR2 NCBI accession number Q8IWV8
- the authors have, thus, identified an antibody that was detectable in most patients with AIP but was also detected in some patients with pancreatic cancer.
- the peptide comprises the sequence selected from the group of: SKDERRF (SEQ ID NO. 2), AKEERRY (SEQ ID NO. 4) or AKEQRRQ (SEQ ID NO. 5).
- the peptide consists of the sequence selected from the group of: SKDERRF (SEQ ID NO. 2), AKEERRY (SEQ ID NO. 4) or AKEQRRQ (SEQ ID NO. 5). Yet preferably, the peptide consists of AKEERRYLRDER, SEQ ID NO. 7.
- the reagent that specifically recognizes and binds the antibodies is a peptide comprising the sequence X 1 KX 2 X 3 RRX 4 (SEQ ID No. 8) wherein Xi is S or A, X 2 is D or E, X 3 is E or Q and X 4 is F, Y or Q.
- the reagent that specifically recognizes and binds the antibodies is a peptide comprising the sequence selected from the group of: SKDERRF (SEQ ID NO. 2), AKEERRY (SEQ ID NO. 4) or AKEQRRQ (SEQ ID NO. 5). Still preferably the reagent that specifically recognizes and binds the antibodies is a peptide consisting of a sequence selected from the group of: SKDERRF (SEQ ID NO. 2), AKEER Y (SEQ ID NO. 4) or AKEQR Q (SEQ ID NO. 5).
- the reagent that specifically recognizes and binds the antibodies is a peptide consisting of AKEER YLRDER, SEQ ID NO. 7.
- the biological sample is obtained from a subject suspected of autoimmune pancreatitis or from a subject under immunotherapy.
- the detection of the complex allows to discriminate between a subject affected by autoimmune pancreatitis and a subject affected by pancreatic carcinoma.
- kits for the diagnosis and/or prognosis of autoimmune pancreatitis and/or for detecting antibodies specific for a peptide as disclosed above in a biological sample comprising at least:
- reagent that specifically recognizes and binds the antibodies, said reagent being a peptide comprising the sequence X 1 KX 2 3 RR 4 (SEQ ID No. 8) wherein Xi is S or A, X 2 is D or E, X 3 is E or Q and X 4 is F, Y or Q; and
- the reagent that specifically recognizes and binds the antibodies is a peptide comprising the sequence selected from the group of: SKDERRF (SEQ ID NO. 2), AKEERRY (SEQ ID NO. 4) or AKEQRRQ (SEQ ID NO. 5).
- the reagent that specifically recognizes and binds the antibodies is a peptide consisting of a sequence selected from the group of: SKDERRF (SEQ ID NO. 2), AKEERRY (SEQ ID NO. 4) or AKEQRRQ (SEQ ID NO. 5).
- the reagent that specifically recognizes and binds the antibodies is a peptide consisting of AKEERRYLRDER, SEQ ID NO. 7.
- FIG. 1 Sera of AIP patients recognized the PBP peptide, a.
- Training set the different diseases studied are represented on the x axis: autoimmune pancreatitis (AIP); alcoholic chronic pancreatitis (ACP); pancreatic adenocarcinoma (PC); intraductal papillary-mucinous neoplasm (IPMN); systemic sclerosis (SSc) and rheumatoid arthritis (PvA).
- SSc systemic sclerosis
- PvA rheumatoid arthritis
- Validation set autoimmune pancreatitis (AIP) and pancreatic cancer (PC) on the x axis; europium counts: y axis.
- the horizontal line represents the cut-off value.
- FIG. 1 Receiver Operating Characteristic (ROC) curve for IgG antibodies against PBP peptide comparing patients suffering from AIP and pancreatic cancer.
- X axis False positive rate (specificity)
- Y axis False negative rate (sensitivity) with an AUC in the ROC analysis of 0.988 (95% CI, 0.963 to 1.000; PO.001).
- FIG. 3 AIP serum IgG antibodies bind the Helicobacter pylori derived protein in Western blot.
- a Helicobacter pylori bacterial lysate was probed with: normal pooled human serum IgG (lane 1), rabbit antiserum raised against the peptide of the Helicobacter pylori plasminogen-binding protein (lane 2), antibodies affinity purified against the peptide of the the Helicobacter pylori plasminogen-binding protein from sera of patients with AIP (lane 3), sera from five different patients with AIP (lanes 4-8), antibodies affinity purified against an irrelevant control peptide from sera of patients with AIP (lane 9), sera of two healthy donors (lane 10 - 11).
- a peroxidase-labelled anti-human IgG antibody and an anti- rabbit IgG antibody (lane 2) were used for detection.
- FIG. 4 Inhibition experiments confirm cross-reactivity between anti-Helicobacter plasminogen-binding protein and anti-UBR2 peptide antibodies.
- Panel A serum from an AIP patient, at a dilution that achieved 50% of the maximal binding to the Helicobacter plasminogen-binding protein coated plate (1 :400), was preincubated with increasing concentrations of either purified H. pylori protein (HP PROT) or PBP peptide (HP PEP) or UBR peptide (UBR2 PEP) or an irrelevant peptide (IRR PEP) for 1 hour at 37 C. The mixture was then transferred to the H.pylori derived protein coated ELISA plate. The remainder of the assay was then carried out as a direct ELISA test.
- HP PROT purified H. pylori protein
- HP PEP PBP peptide
- UBR peptide UBR peptide
- IRR PEP irrelevant peptide
- the binding to the protein is inhibited by the Helicobacter protein, the PBP peptide and by the UBR2 peptide, but not by the irrelevant control peptide. Similar results were obtained in 5 other samples tested.
- the UBR2 peptide was used instead of the protein, since UBR2 expression in the cell is too low to purify an adequate amount of protein to perform this type of experiment.
- the recombinant human UBR2 protein commercially available is only a part of the protein and does not comprise the homologous sequence of interest.
- Panel B serum from an AIP patient, at a dilution that achieved 50% of the maximal binding to a UBR2 peptide (UBR2 PEP) coated plate (1 :800), was preincubated with increasing concentrations of either UBR2 peptide or purified H. pylori plasminogen-binding protein (HP PROT) or PBP peptide (HP PEP) or an irrelevant peptide (IR PEP) for 1 hour at 37 C. The mixture was then transferred to a UBR2 peptide coated ELISA plate. The remainder of the assay was then carried out as a direct ELISA test.
- UBR2 PEP UBR2 peptide
- Serum samples were obtained from patients and healthy controls. All serum samples were stored at -20 C. Blood samples were obtained from all the subjects after written informed consent and the local ethical committee approved the study.
- HP+ serology (%) Positive serology for Helycobacter Pylori
- AIP focal autoimmune pancreatitis
- Sera were collected within one month of symptom onset from 40 patients who had histologically confirmed pancreatic adenocarcinoma (PC). Furthermore, sera from 21 patients with alcoholic chronic pancreatitis (ACP) and from 18 patients with intraductal papillary-mucinous neoplasm (IPMN) were analysed. Finally sera from patients with two unrelated autoimmune diseases, systemic sclerosis (SSc) and rheumatoid arthritis (RA) were studied.
- PC pancreatic adenocarcinoma
- ACP alcoholic chronic pancreatitis
- IPMN intraductal papillary-mucinous neoplasm
- SSc systemic sclerosis
- RA rheumatoid arthritis
- AIP patients the diagnosis was made on the basis of pancreatic specimens in 1 patient.
- diagnosis was made in the presence of: 1) fine needle aspiration cytology (4 patients) or histology (6 patients), 2) association with other autoimmune diseases (6 patients); 3) typical radiological findings (CT or MR) (14 patients); 4) clinical, laboratory and instrumental response to steroid therapy (14 patients).
- Serum IgG4 and ⁇ -Helicobacter pylori antibodies detection Serum IgG4 levels were determined using a commercially available immuno- nephelometric kit (Dade Behring, Marburg, Germany). The upper normal limit of serum IgG4 levels was considered 135 mg/dl, as reported by Hamano et al. 11
- IgG antibodies to H. pylori were detected using a commercially available kit (Enzygnost H. Pylori, Siemens, Deerfield, IL, USA).
- the FliTrx random dodecamer peptide library which displays peptides on the surface of Escherichia coli, was purchased from Invitrogen (Carlsbad, California, United States) and screened with pooled Immunoglobulins (Igs) purified from the sera of the 20 patients with AIP, according to manufacturer's instructions (FliTrx Panning Kit, Invitrogen). After five rounds of biopanning experiments, the enriched library was grown and single colonies induced with tryptophan to express the fusion peptides. Bacteria were lysed in sample buffer and tested in western blot with the pooled Ig fraction from autoimmune pancreatitis to check for positive clones.
- Igs Immunoglobulins
- DNA was extracted from positive clones and sequenced. A set of 15 peptides, out of the 30 peptides obtained from the last biopanning round, was synthetized and used in a dissociation-enhanced lanthanide fluorescent immunoassay (DELFIA) assay to test individual patients' sera.
- DELFIA dissociation-enhanced lanthanide fluorescent immunoassay
- All the synthetic peptides including the AIP peptide (SKDERRFEQPRV, SEQ ID No. 1), the AIPi_7 peptide (SKDERRF, SEQ ID No. 2), the AIP 6 _i 2 peptide (RFEQPRV, SEQ ID No. 3), the PBP peptide (AKEERRY, SEQ ID No. 4), the UBR2 peptide (AKEQRRQ, SEQ ID No. 5) and the irrelevant control peptide (VTLPKDSDVELP, SEQ ID No. 6), were manually synthesized using the standard method of solid-phase peptide synthesis, which follows the 9-fluorenylmethoxycarbonyl (FMOC) strategy with minor modifications. 18
- the DELFIA is a time-resolved fluorescence method that can be used to study antibody binding to solid-phase proteins or peptides.
- the peptides were used at a concentration of 20 ⁇ g/ml in phosphate buffered saline (PBS) to coat DELFIA plates (Perkin Elmer, Boston MA). Plates were then blocked for 1 h with a blocking reagent (Perkin Elmer). Serum samples were diluted 1 :50 in bovine serum albumin (BSA) 1% (Sigma, Saint Louis MO) and incubated on the plates overnight at 4-8 °C. Plates were then washed ten times with washing buffer (Perkin Elmer).
- BSA bovine serum albumin
- Bound antibodies were detected with a europium-labelled anti-human IgG antiserum (1 :500 in diluting buffer) (Perkin Elmer). Plates were read on a Victor 3 instrument (Perkin Elmer) and the data analyzed with a software supplied with the DELFIA instrument. Absorbance values higher than the mean + 3 SD of each serum dilution of the control group were considered positive.
- H. pylori extract (Virion, Ruschlikon, Switzerland) was used to detect the H. pylori PBP in immunoblot.
- the extract was enriched for the PBP by affinity chromatography using a Sepharose column coupled to a rabbit anti-PBP peptide antibody (see above). Blots were probed with primary antibodies followed by either peroxidase-linked anti-human Igs antibodies or anti-rabbit IgG antibodies (purchased from Sigma).
- HELA cell lysates were prepared using a commercially available kit (Nuclear Extract kit, Active Motif, Carlsbad, CA, USA).
- ROC Receiver Operating Characteristic
- the authors have screened a peptide library with pooled Igs derived from a panel of 20 patients with AIP, in order to identify only those peptides possibly relevant to the pathogenesis of the disease.
- the authors identified a peptide (named AIP peptide or AIP peptidei_i 2 : SKDERRFEQPRV, SEQ ID NO. 1) recognized by serum IgGs of 17 out of 20 (85%) AIP patients but not by healthy donors, using a DELFIA assay. However 22 out of 40 (55%) patients' sera with pancreatic cancer and 10 out of 20 (50%) with ACP reacted with this peptide.
- the AIP 6 _i 2 peptide was recognized by 4/20 (20%>) patients with AIP and 20/40 patients (50%) with PC.
- the AIPi_ 7 peptide was recognized by 18/20 AIP patients (90%) and by 4/40 (10%) patients with PC. These data demonstrate that the AIPi_ 7 peptide sequence contains an epitope recognized by nearly all the sera of patients with AIP.
- H. pylori infection has been associated with the pathogenesis of AIP, 19"21 the authors decided to compare the AIPi_ 7 peptide sequence with known bacterial protein sequences in a protein data bank (Swiss-Prot database) using the BLASTP via the NCBI BLAST network service. The authors found that the peptide AIPi_ 7 shared a high degree of homology (4 identities and 3 conservative substitutions) with the PBP encoded by H. pylori (Table 2B).
- PBP peptide The authors then synthesized the bacterial peptide called PBP peptide (AKEERRY, SEQ ID NO. 4) and used it to test the panel of patients 'sera.
- Serum antibodies against the identified peptide were not detected also in the two systemic autoimmune diseases considered, RA and SSc ( Figure 1A).
- the sensitivity and specificity of the quantitative analysis of the present invention's assay were 95% and 96.6%>, respectively (p ⁇ 0.0001).
- the area under the curve (AUC) in the ROC analysis was 0,988 (CI 95%: 0.970-1.000).
- AUC area under the curve
- the sensitivity and specificity were 95% and 90% respectively, with AUC in the ROC analysis of 0.973 (CI: 95%: 0.937- 1.000)(p ⁇ 0.0001) ( Figure 2).
- IgG4 resulted positive in 19/35 AIP patients (54%), with a cut-off of 135 mg/dL (i.e. if the concentration of IgG4 is > 135 mg/dL, then the sample is positive) 11 .
- the 2 patients negative for the anti-PBP antibodies were IgG4 positive, whereas all the remaining 16 IgG4 negative patients were positive for anti-peptide antibodies. Eleven of the 110 patients with PC (10%) tested positive for IgG4.
- the ELISA results obtained with the PBP peptide were confirmed by western blot analysis using an H. pylori derived protein extract (Fig. 3); 32 out of the 35 AIP sera showed reactivity against a protein band corresponding to the PBP. Representative examples are shown in Figure 3.
- Antibodies directed against the H. pylori PBP were not detected in healthy donors and in patients with IPMN and ACP and were present in 4 out of 110 patients with pancreatic cancer.
- AIP is characterized by chronic pancreatic tissue damage
- the authors next compared the PBP peptide with human pancreatic proteins in a protein data bank (Swiss-Prot database of known human sequences) using the BLASTP via the NCBI BLAST network service, and found that the peptide is homologous (5 identities and 1 conservative substitution) to E3 ubiquitin-protein ligase (UBR2), AKEQRRQ (SEQ ID NO. 5) a component of the N-end rule pathway, highly expressed in acinar cells of the pancreas (Table 2C).
- UBR2 E3 ubiquitin-protein ligase
- AKEQRRQ SEQ ID NO. 5
- the present assay was able to discriminate between AIP and pancreatic cancer in the majority of the cases. Of note, 4,5% of patients with pancreatic cancer tested positive on the invention's assay. The mean age of patients with AIP is lower than that of patients with PC, however the authors do not believe that such difference influences the test. Indeed the test resulted negative in other groups of patients with a mean age similar to that of the AIP group.
- the anti-PBP peptide antibody the authors describe here was not positive in normal healthy donors or in patients with autoimmune diseases unrelated with AIP, such as SSc and RA.
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Abstract
La présente invention concerne un procédé de détection d'anticorps spécifiques pour un peptide récemment identifié comme marqueur de la pancréatite auto-immune.
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| US25102909P | 2009-10-13 | 2009-10-13 | |
| PCT/IB2010/054615 WO2011045745A1 (fr) | 2009-10-13 | 2010-10-12 | Anticorps associé à la pancréatite auto-immune et ses utilisations |
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| CN103808924B (zh) * | 2014-02-24 | 2016-03-09 | 北京工业大学 | 一种Th17免疫相关因子与IgG4抗体组合物及其应用 |
| WO2017223116A2 (fr) * | 2016-06-20 | 2017-12-28 | Healthtell Inc. | Procédés pour le diagnostic différentiel de maladies auto-immunes |
| CN109790203A (zh) | 2016-06-20 | 2019-05-21 | 健康之语公司 | 自身免疫疾病的诊断和治疗方法 |
| CN110168370A (zh) * | 2016-11-11 | 2019-08-23 | 健康之语公司 | 用于鉴定候选生物标志物的方法 |
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| WO2005023851A1 (fr) * | 2003-09-05 | 2005-03-17 | Karolinska Innovations Ab | Polypeptides de liaison au plasminogene/a la plasmine et acides nucleiques associes |
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