Regulation and dysregulation of angiogenesis in rheumatic diseases

Angiogenesis is important in the pathogenesis of systemic inflammatory rheumatic diseases, a family of related disorders that includes rheumatoid arthritis and systemic sclerosis. Rheumatoid arthritis is the rheumatic disease in which the role of angiogenesis has been studied most extensively. However, whereas rheumatoid arthritis is characterized by excessive angiogenesis, the situation is not as clear cut in other rheumatic diseases. For example, systemic sclerosis is characterized by reduced capillary density with insufficient angiogenic responses. Results with angiogenesis inhibitors are controversial, and there is in parallel a wide range of upregulated angiogenic factors such as vascular endothelial growth factor. Dysregulation of angiogenesis in systemic sclerosis is accompanied by other pathogenic processes, including fibrosis, autoimmunity and vasculopathy. Animal models with at least partial features of the vasculopathy observed in systemic sclerosis include wound healing models, graft versus host disease models and, in particular, the University of California at Davis line 200 chicken model of systemic sclerosis.