Fig. 2.

Small interfering Toll-like receptor 2 (siTLR-2) knockdown of endogenous TLR-2 expression suppresses 29-kDa amino-terminal fibronectin fragment (29-kDa FN-f)-induced matrix metalloproteinase (MMP) production in normal and osteoarthritis (OA) chondrocytes. Chondrocytes were transfected with siTLR-2 or control small interfering RNA (siRNA). Cells were stimulated 48 h after transfection using different concentrations of 29-kDa FN-f for 6 or 24 h. a Real-time reverse transcription polymerase chain reaction (RT-PCR) analysis demonstrated specific inhibition of TLR-2 expression by siRNA against TLR-2. b In normal and OA chondrocytes, MMP-1, MMP-3, and MMP-13 mRNA expression was analyzed using SYBR Green RT-PCR. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was used as an internal control. The mRNA expression level in untreated control siRNA transfected chondrocytes was set as 1. Data represent the mean ± SD for triplicate experiments from three different donors. *P < 0.05, **P < 0.01, and ***P < 0.001 vs. control. c Secretion of MMP-1 and MMP-3 in supernatants of 29-kDa FN-f-stimulated chondrocytes was assessed using Western blot analysis. Data are representative of four independent experiments from different donors with similar results. d MMP-13 production in culture supernatants was determined by enzyme-linked immunosorbent assay. Each value represents the mean ± SD of triplicate experiments from three different donors. *P < 0.05 and **P < 0.01 vs. control siRNA-transfected chondrocytes