TNF and rheumatoid arthritis: IL-38 is strongly expressed in the synovial lining [76], and elevated IL-38 expression is associated with TNF-α, IL-1β, IL-6 [76], IL-1Ra, CCL3, CCL4, M-CSF [29], erythrocyte sedimentation rate (ESR), and CRP, and probably serve as a potential biomarker for RA [78].