7,3′‐dimethoxy hesperetin induces apoptosis of fibroblast‐like synoviocytes in rats with adjuvant arthritis through caspase 3 activation

Approaches inducing fibroblast‐like synoviocytes (FLS) apoptosis in rheumatoid arthritis (RA) patients have been considered as a promising strategy for treating RA. Here, adjuvant arthritis (AA) in rat was induced by complete Freund's adjuvant and FLS were separated and cultured using a tissue explant cultivation method. The apoptotic effect of 7,3′‐dimethoxy hesperetin (DMHP, a highly antirheumatic active derivative of hesperidin) on AA FLS was evaluated with MTT assay, Hoechst staining and flow cytometry analysis. Bcl‐2, Bax, caspase 3 gene expressions and caspase 3 activity were assayed to identify whether caspase 3 was involved in the apoptosis induced by DMHP. It was found that DMHP significantly decreased AA FLS proliferation in vitro by MTT assay. The AA FLS treated with DMHP displayed typical apoptotic characteristics including irregularity in shape, nuclear shrinkage and chromatin condensation. Flow cytometry analysis indicated that DMHP could obviously increase the AA FLS apoptosis rate. Compared with the AA‐FLS control group, DMHP markedly decreased the mRNA expression of Bcl‐2, whereas those of Bax and caspase 3 were increased. Moreover, DMHP significantly increased caspase 3 activity in a dose‐dependent manner. In aggregate, the results demonstrate that DMHP effectively induces AA FLS apoptosis through caspase 3 activation and can be considered as a possible antirheumatic agent. Copyright © 2010 John Wiley & Sons, Ltd.