IFNL1 and rheumatoid arthritis: TLR4 plays an important role in synovial inflammation and contributes to the pathogenesis of RA.42 Expression of TLR4 in RAW264.7 cells was increased when exposed to IL‐29.11 IL‐6, IL‐8 and MMP‐3 protein levels were significantly enhanced in RA fibroblast cell line MH7A by IL‐29 stimulation, whereas IL‐29 exposure down‐regulated IL‐10 expression.