| AimSystemic lupus erythematosus(SLE)is one of the common autoimune diseases in China that brings long-term physical and mental torture to patients.Early-diagnosis and individualized treatment are the key to control the disease.However,the routine used specific auto-antibodies for clinical diagnosis of SLE cannot meet the needs of early clinical diagnosis and treatment of SLE.Finding new diagnostic bio-markers for SLE is of great significance to improve the diagnosis and treatment of SLE.Epitope polypeptide,which usually consists of 8-15 amino acids,and is a diagnostic marker with great potential.Therefore,our study is to find SLE-related epitope peptides as b io-markers by using phage display random peptide technology.Methods1.In this study,we adopted the case-control design.The phage display random peptide(1012)library was used to bind IgG antibodies which extracted from three groups including SLE group,healthy control group and other common autoimmune disease control group.50 epitope polypeptides were selected preliminarily based on the biological information and comparison results finally.2.According the screening results,50 polypeptides were selected to construct a peptide array.Then,644 serum samples(296 samples from SLE group,168 samples from disease control group and 180 samples from healthy control group)were collected for further screening and verification.The polypeptides with AUC>0.650 were selected as the candidate markers for the next verification phase.3.The polypeptide selected from the results of peptide array was verified by ELISA testing.In this stage,another 500 serum samples(200 in SLE group,150 in disease control group and 150 in healthy control group)were recruited.The diagnostic capability of polypeptide were compared between SLE and healthy cohort,other autoimmune disease cohort,respectively.Meanwhile,the correlation between polypeptide and clinical manifestations of SLE was preliminary analyzed.Furthermore,we also analyzed whether these polypeptide can improved the the diagnostic efficacy after combined with anti-dsDNA antibody and anti-Sm antibody.Results1.Statistical analysis of peptide array results showed that five epitope polypeptides(SLE_P19,SLE_P20,SLE_P27,SLE_P28,SLE_P29)have statistical significant(P<0.0001)among three groups.Compared with healthy cohort,SLE_P20 is better than other polypeptides with AUC of 0.864.While SLE_P27 also has greatest value of AUC(0.844)compared with disease control group.The AUC of five polypeptides is 0.956 after combined diagnosis with the accuracy of 92.80%.2.Further verification showed that the AUC of the five epitope polypeptides were all greater than 0.7,among which the AUC,SEN,SPE,PLR,NLR and Ac of SLE_P27 were 0.938,76.00%.92.70%,10.411,0.259,84.40%,respectively.And the AUC after combined diagnosis was 0.943,which was consistent with the detection results from the SLE peptide array.Compared with other autoimmune diseases,SLE_P27 is superior to other four polypeptide in distinguishing SLE from RA,while the value of AUC is 0.842,SLE_P29 is superior to other four polypeptides in distinguishing SLE from other common autoimmune disease(CTD,ALD,SS,PM/DM,Scl).Compared with disease control cohort,our results showed these five polypeptides,can improve the diagnostic efficiency for SLE after combined with anti-dsDNA,anti-Sm.3.The protein blast results found that SLE_P19 might come from the third m ember A2(BTN3A2)of lactophil subfamily,while SLE_P20 from two proteins:polypeptide n-acetylgalactosamine transferase 15(GALNT15)and transferrin receptor(TFRC).ConclusionWe found that five polypeptides(SLE_P19,SLE_P20,SLE_P27,SLE_P28,SLE_P29)may be potential bio-markers for SLE.Among them.SLE_P27 can not only distinguish SLE from healthy people,but also distinguish SLE from some common autoimmune diseases,and its overall performance is superior to the other four polypeptides.Besides SLE_P19/P20 may be derived from three proteins:BTN3A2,GALNT15 and TFRC. |
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