Angiogenesis: general mechanisms and implications for rheumatoid arthritis.

In rheumatoid arthritis, the vascular endothelium is among the key targets for circulating mediators of inflammation and controls the trafficking of cells and molecules from the bloodstream toward the synovial tissue. Local blood vessel proliferation allows the pannus to develop and grow, thereby promoting cartilage and bone destruction and joint remodeling. Angiogenesis, the production of new capillaries from preexisting blood vessels, is a key process in rheumatoid arthritis that involves multiple substances such as cytokines, chemokines, growth factors, cell adhesion molecules, proteinases, proteinase inhibitors, and matrix proteins. In animal models of arthritis, angiogenesis inhibitors have been found to improve clinical and radiological outcomes, opening up the possibility of therapeutic applications in humans. Before this possibility is realized, the steady accumulation of data on the mechanisms that regulate angiogenesis will have to continue until a clear picture of angiogenesis is formed.