CCL20 and rheumatoid arthritis: It also reduces IL-8, IL-17, IL-22, and MIP-3a (CCL20) expression in psoriatic skin causing a decrease in T cells and dendritic cells, and a reduction in keratinocyte hyperplasia.[59] It is FDA approved for the treatment of rheumatoid arthritis, ankylosing spondylitis, psoriatic arthropathy, and plaque psoriasis (moderate-to-severe).