TNF and rheumatoid arthritis: PE down-regulated genes of several KEGG pathways related to immune/inflammatory processes, including cytokine–cytokine receptor interaction, Th1 and Th2 cell differentiation, phosphoinositide 3-kinase (PI3K)-Akt, Th17 cell differentiation, osteoclast differentiation, JAK-STAT, chemokines, mitogen-activated protein kinase (MAPK), nuclear factor (NF-)kappa B, TNF, TGF β, Toll-like receptor, and RA signaling pathways (Figure 2c).