CD4 and autoimmune disease: Th17 cells, characterized by expression of cytokines IL-17, IL-21, IL-22, and IL-23, and steroid receptor–type nuclear receptor RORγt as the master TF, contribute to protection against extracellular pathogens as well as chronic inflammation and autoimmune diseases (27, 28).Treg cells, on the other hand, are a specialized CD4+ T cell subset that suppress excessive immune responses, preventing autoimmune reactions and maintaining immune tolerance to self-antigens (29).