The clock gene Bmal1 controls inflammatory mediators in rheumatoid arthritis fibroblast-like synoviocytes

Object: To clarify the involvement of clock genes in the production of inflammatory mediators from RA-FLS, we examined the role of Bmal1, one of the master clock genes. Methods: RA-FLSs were stimulated with IL-10 (0, 20 ng/mL), IL-6 (0, 20 ng/mL), IL-17 (0, 20 ng/mL), TNF-alpha (0, 20 ng/mL) or IFN-gamma (0, 20 ng/mL) to examine the expression of Bmal1, MMP-3, CCL2, IL-6, IL-7 and IL-15 by qPCR and immunofluorescence staining. After silencing Bmal1, RA-FLSs were stimulated with IL-10 (0, 20 ng/ mL), TNF-alpha (0, 20 ng/mL) or IFN-gamma (0, 20 ng/mL) to examine the expressions of inflammatory mediators; MMP-3, CCL2, IL-6 and IL-15 by qPCR, ELISA and immunofluorescence staining. Results: Bmal1 expressions were increased by IL-10, TNF-alpha and IFN-gamma stimulations. Under stimulations with TNF alpha, IL-10, and IFN-gamma, mRNA and protein expressions of MMP-3, CCL2 and IL-6 were suppressed by siBmal1. Conclusion: Results indicate that Bmal1 contributes the production of MMP-3, CCL2, and IL-6 from RA-FLS, implying Bmal1 is involved in the pathogenesis of RA by regulating the inflammation.