Anti-citrullinated α-enolase peptide as a highly sensitive autoantigen in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common autoimmune rheumatic disease in Taiwan. Anti-cyclic citrullinated peptide (anti-CCP) assay is widely used for RA diagnosis; however, not all anti-CCPs are detectable in RA-joint lesions. Citrullinated α-enolase peptide (CEP), which has a unique immunodominant epitope, can be detected in synovial fluid. Here, we aimed to evaluate the potential of anti-CEP as a serologic marker for the early diagnosis of RA and a prognostic predictor of joint destruction. We also determined the association of single-nucleotide polymorphisms (SNPs) in genes with the serological status and clinical characteristics of RA. Clinical records of 30 patients with RA were collected, and their serum and DNA samples were evaluated using enzyme-linked immunosorbent assay (ELISA) and SNP cross-reaction analysis. A considerable amount of anti-CEP was detected in patients with RA, a trend similar to that of anti-CCP. Moreover, anti-CEP was considerably associated with the protein-arginine deiminase type-2 SNP rs1005753.