Rheumatoid arthritis (RA) is a typical, chronic autoimmune disease that primarily affects the joints, ultimately leading to synovitis that often develops into cartilage and bone erosion, apart from which, extra-articular features are presented, including subcutaneous nodules, vasculitis, and pulmonary fibrosis, particularly in severer cases. https://www.creative-biolabs.com/drug-discovery/therapeutics/collagen-induced-arthritis-cia-rodent-model.htm