Pathogenetic roles of Synoviolin in synovial hyperplasia of rheumatoid arthritis

Background

Synovial hyperplasia is a pathological hallmark of rheumatoid arthritis (RA). However, the mechanisms that regulate synovial cell outgrowth are not fully understood. We recently isolated a novel membrane-type molecule named 'Synoviolin'. This molecule was cloned from the cDNA library of RA synovial cells by immunoscreening using antirheumatoid synovial cell antibody. It is thus expected that the molecule plays important roles in synovial hyperplasia of RA. We examine the pathogenetic role of Synoviolin in RA in vivo and in vitro.

Methods

We examined the protein expression of Synoviolin in RA synovia by immunohistochemistry. We also examined the protein expression of the molecule in cultured synovial cells by Western blotting. To examine the effects of this molecule on synovial cell proliferation, the expression of Synoviolin in cultured synovial cells was knocked down using the RNAi technique.

Results

Synoviolin is highly expressed in synovia of RA compared with synovia of osteoarthritis. Correspondingly, the protein expressions of Synoviolin in cultured RA synovial cells are higher than that in osteoarthritis synovial cells. The proliferation of synovial cells is significantly inhibited by downregulation of Synoviolin mediated by RNAi.

Conclusion

Our results implicate the important roles of Synoviolin in synovial hyperplasia of RA. These findings will provide a novel pathogenetic mechanism in RA, and suggest that further research on Synoviolin will provide new therapeutic strategies for RA.