Etiopathogenesis of Relapsing Polychondritis
The etiology of Relapsing Polychondritis is unknown but is thought to be an autoimmune process. Patients with RPC and animal models of the disease have demonstrated cellular and humoral immunity against a variety of cartilage components including collagen (types II, IX, XI), matrilin-1 (found exclusively in cartilage found in the respiratory tract and ears), and proteoglycans. In patients with RPC, the degree of immune response correlates with clinical disease activity.
An inciting agent (infectious, toxic, immunologic) has not yet been identified. However, once stimulated, activated lymphocytes and macrophages are thought to secrete mediators that induce the release of lysosomal enzymes, especially proteases. The resulting inflammatory destruction of cartilage eventually generates an attempt at repair by local fibroblasts and chondrocytes, leading to the formation of granulation tissue and fibrosis.
