AHR and rheumatoid arthritis: For instance, in Th1 and Th17 cells, B cells, dendritic cells, M1 monocytes, natural killers, and osteoclasts, AhR activation has an exacerbating impact on rheumatoid arthritis [309,310,311,312,313,314]; however, in Th2 cells, regulatory T cells, regulatory dendritic cells, M2 monocytes, and osteoblasts, AhR activation protects against rheumatoid arthritis [311,314,315,316].