IFNL1 and arthritic joint disease: Administration of IL‐29 further promoted the TLR4‐mediated IL‐6 and IL‐8 expression in RA arthritis synovial fibroblasts.11 Similarly, IL‐29 up‐regulated TLR2, TLR3 and TLR4 expression in RA FLS.43, 44 Chronic inflammation is an important factor of ongoing cartilage damage and joint degeneration in OA pathogenesis.