Chronic inflammatory and autoimmune diseases are generally characterized by a prolonged and persistent pro‐inflammatory state, such as metabolic syndrome, neurodegenerative disease, cardiovascular disease, rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE).[234] PRR stimulation causes dendritic cells (DCs) to secrete miscellaneous cytokines that regulate the differentiation of CD4+ T cells to different subclasses of T helper (Th) cells, including inducible regulatory T cells (Tregs), T follicular helper cells (Tfh), and Th1, Th2, Th9, and Th17 cells. The gene discussed is CD4; the disease is rheumatoid arthritis.