TNF and rheumatoid arthritis: The GO and KEGG functional annotation and pathway enrichment analyses suggested that the identified DEGs were mainly involved in ‘immune response’, ‘cytokine–cytokine receptor interaction’ (RA vs. NC group), ‘signal transduction’, ‘fat cell differentiation’ and ‘TNF signaling pathway’ (OA vs. NC group), and ‘signal transduction’, ‘immune response’, and ‘cytokine–cytokine receptor interaction’ (RA vs. OA group).