TNF and rheumatoid arthritis: Additionally, large numbers of synovial lining macrophages in RA represent a source of nitric oxide (NO) that promote the highly expression of TNF-α production and further induce the incidence of synovitis [10], and the transcription of proinflammatory cytokine genes in lipopolysaccharide (LPS)-stimulated macrophages is usually regulated by the activation of NF-κB signaling pathway [11].