CD4 and rheumatoid arthritis: IL-23 is involved in the proliferation of CD4+ Th17 cells to produce IL-17 and along with IL-17, associated with several autoimmune and inflammatory disorders such as psoriasis, psoriatic/rheumatoid arthritis, multiple sclerosis, Crohn's disease, uveitis, and inflammatory bowel disease (Braegelmann et al., 2016; Chan et al., 2018; Fotiadou et al., 2018).