Expression of calpain and calpastatin in arthritis and antigen epitopes of human calpastatin recognized by rheumatoid arthritis sera / 中华风湿病学杂志

ABSTRACT

Objective To compare the expression level of calpain and calpastatin mRNA in rheumatoid arthritis (RA) and osteoarthritis (OA) synovial tissues (ST) and analyze the antigen epitopes of human calpastatin recognized by RA sera.Methods Total RNA of three RA and two OA patients was isolated from ST and expression levels of calpain and calpastatin mRNA were detected by reverse transcription polymerase chain reaction (RT PCR).According to hydrophilicity of human calpastatin (Accession,U 31346), overlapping oligopeptides were synthesized by auto spot Robot in N terminal (L domain) and C terminal (Ⅳ domain) of calpastatin.The epitopes of synthesized peptides were analyzed by RA sera using dot ELISA.Results mRNA expression of calpain showed higher than that of calpastatin in both OA and RA.Meanwhile,the mRNA expression level of calpain increased in RA more than that in OA.Three antigen epitopes of human calpastatin (with the sequence DKDLDDALD,DTIPPEYRH and QDPIDALSG) were identified by RA sera,while control sera failed to react with synthetic peptides.Conclusion The calpain calpastatin system may participate in pathogenic mechanism of RA,and the calpastatin may be a target for autoantibody of RA,which implies that it is not only possible to treat RA patients with synthetic peptide of human calpastatin,as a chemotherapeutant,but also a materials for immunodiagnosis of RA.