Foundations of CFA-Induced Rheumatoid Arthritis Models: From Immune Activation to Joint Destruction

Abstract

Complete Freund’s Adjuvant (CFA) induced rheumatoid arthritis in rats is one of the most extensively used experimental models for studying chronic inflammatory joint disease. The model is initiated by administration of CFA, leading to a strong immune reaction that activates both innate and adaptive immune responses. Early events include stimulation of macrophages and antigen-presenting cells, followed by T-lymphocyte activation and excessive release of pro-inflammatory cytokines such as tumour necrosis factor-α, interleukin-1β, and interleukin-6. Persistent cytokine signalling results in synovial inflammation, vascular proliferation, and infiltration of immune cells into joint tissues. As the disease progresses, enhanced oxidative stress, matrix metalloproteinase activity, and osteoclast differentiation contribute to cartilage breakdown and bone erosion. These pathological changes are accompanied by clinical manifestations including paw swelling, joint rigidity, and pain-associated behavioural alterations. CFA-induced arthritis closely resembles key pathological and immunological features of human rheumatoid arthritis, making it a valuable tool for mechanistic studies. Moreover, this model is widely applied for preclinical evaluation of anti-inflammatory agents, immunomodulators, and disease-modifying anti-rheumatic drugs. Overall, CFA-induced arthritis provides a robust and reproducible platform to investigate immune-driven joint destruction and to assess therapeutic strategies targeting rheumatoid arthritis.