29-kDa FN-f-activated TLR-2 and NOD2 signaling pathway modulates the cGAS/STING signaling pathway. (A) The cGAS/STING pathway was modulated by TLR-2 and NOD2 activated by 29-kDa FN-f. Chondrocytes were transfected with si-TLR-2 or si-NOD2 and incubated with 29-kDa FN-f for 24 h. The levels of phosphorylated TBK1 and IRF3 were measured using western blot analysis. The protein levels were measured by western blot analysis. Western blot data are representative of three independent experiments using different donors. β-actin served as a loading control. (B) GM-CSF (CSF-2), G-CSF (CSF-3), and IFN-α expressions were regulated by 29-kDa FN-f-modulated TLR-2 and NOD2. Chondrocytes were transfected with si-TLR-2 or si-NOD2 and incubated with 29-kDa FN-f for 6 h. Expression of GM-CSF, G-CSF, and IFN-α was measured by using qRT-PCR analysis. GAPDH was used as an endogenous control. Data are expressed as the mean ± standard deviation (SD) of duplicate data derived from three different donors. *P < 0.05 and **P < 0.01 vs. si-control-transfected cells. ns, not significant.