IL-1β and TNF-α are not involved in Cyr61-induced IL-8 expression in FLS. (A) The protein levels of IL-1β and TNF-α in SF from RA and OA patients were detected by ELISA. (B) IL-8 mRNA expression in IL-1β-knockdown FLS was detected by real-time PCR. Left panel, the sequence for siIL-1β (small interfering RNA against IL-1β) was evaluated. The IL-1β mRNA expression in FLS transfected with siIL-1β (black bar) or siNC (control, open bar) was measured by real-time PCR. Right panel, FLS were transfected with siIL-1β or siNC for 4 hours, cultured for 20 hours and incubated for an additional 2 hours in the presence or absence of Cyr61 (5 μg/ml). IL-8 mRNA expression in FLS was detected by real-time PCR. (C) IL-8 mRNA expression in TNF-α-knockdown FLS was detected by real-time PCR. Data represent the mean ± SEM of at least three independent experiments. * P <0.05, ** P <0.01. FLS, fibroblast-like synoviocytes; OA, osteoarthritis; RA, rheumatoid arthritis; SEM, standard error of the mean; siNC, control siRNA.