Study On Anti-HSP90 Autoantibody As A Potential New Biomarker In Patients With Spondyloarthritis

Objective:Spondyloarthritis(SpA)is a common inflammatory rheumatic disease.Chronic inflammatory back pain and structural bone damage are the leading symptoms of the disease.So far,the early diagnosis and the diseases activity monitoring are often difficult because the lack of specific biomrker in diagnosis.Recently,several autoantibodies have been found in SpA patients,such as anti-CD74 autoantibody.The purpose of our study was to identify new biomarkers as diagnostic markers of SpA,and they may be able to assess the disease activity of patients with SpA.Methods:Western blotting was used to analyze the reaction of THP-1 cell lysis protein and serum of patients with SpA.Specific target bands were selected for mass spectrometry analysis.According to the results of mass spectrometry and searching results of literatures,we found that Heat Shock Protein(HSP90)may be a new autoantigen in SpA patients.Anti-HSP90 autoantibody in sera from 45 SpA patients,87 other rheumatic diseases patients(21 Gout,24 SLE,42 PSO)and 44 normal controls was investigated by ELISA.Large number of sample were further confirmed by the same methods,compared with anti-CD74 autoantibodies at the same time.The association between titer of anti-HSP90 and disease activity in SpA patients was analyzed.Serum HSP90 concentrations were assessed by Human HSP90 ELISA Kit.Results:In the protein components of THP-1 cells,there is a specific autoantigen of SpA patients with a molecular weight of 80-100kDa(about 90kDa).Mass spectrometry and literature review showed that HSP90 may become a new autoantigen in SpA patients.The presence of anti-HSP90 autoantibody in SpA patients was 24.4%,significantly higher than other rheumatic diseases patients(Gout 0,SLE 16.7%,PSO 0),and normal controls(6.8%).After enlarged sample,the presence of anti-HSP90 autoantibody in SpA patients was 21.0%,still significantly higher than normal controls(3.6%).Meanwhile,the presence of anti-CD74 autoantibody also higher than normal controls(14.5%,6.2%),but the difference was not significant.Titer of anti-HSP90 was positively associated with Ankylosing Spondylitis Disease Activity Score-C Reactive Protein(ASDAS-CRP),Bath Ankylosing Spondylitis Disease Activity Index(BASDAI),levels of back pain,morning stiffness,swelling/pain peripheral joint and patient global assessment.Titer of anti-CD74 was not associated with these indexes.The presence of HSP90 autoantigen in SpA patients was 46.3%,and there was no positive patient in the healthy controls.Conclusions:Anti-HSP90 autoantibody may be used as an important additional tool for diagnosis and assessment the disease activity of SpA.