CRT promoted c-FLIP expression via NF-κB pathway in rheumatoid arthritis fibroblast-like synoviocytes / 天津医药

ABSTRACT

Objective To investigate the molecular mechanisms of upregulated expression of cellular Fas-associated death domain-like interleukin-1 beta converting enzyme inhibitory protein(c-FLIP)by calreticulin(CRT)in patients with rheumatoid arthritis (RA). Methods The semi-quantitative analysis and localization of c-FLIP in RA and osteoarthritis (OA)synovium were detected by immunohistochemistry.The fibroblast-like synoviocytes(FLS)were isolated by enzymatic digestion of synovial tissue specimens obtained from RA and OA patients,and cultured as an in vitro experiment model.The expressions of c-FLIP in RA and OA synovial fibroblasts were detected by immunofluorescence and Western blot assay. Whether CRT influenced c-FLIP expression and its molecular mechanism were explored by Western blot assay. Results The high expression of c-FLIP was found in RA synovium, mainly in the lining and sublining areas of FLS and vascular endothelial cells detected by immunohistochemistry.Meanwhile,weak staining of c-FLIP was observed in OA synovium.The expression of c-FLIP was significantly higher in RA synovium than that of OA synovium(t=11.717,P<0.001).Results of immunofluorescence and Western blot assay showed that c-FLIP was mainly located in cytoplasm, and which was higher expressed in FLS of RA than that of OA. The increased c-FLIP expression and phosphorylation of NF-κB were detected after being co-incubated with exogenous CRT (0, 10, 50, 100 μg/L), in dose-dependent manner. The effect of CRT upregulating c-FLIP expression was blocked by NF-κB inhibitor BAY 11-7082.Conclusion CRT can increase c-FLIP expression at least partly through NF-κB pathway in RA,which may provide therapeutic target for the treatment of RA.