Function and regulation of the complement system in cardiovascular diseases.

The complement system plays a central role in innate immunity and also regulates adaptive immunity. The complement system has been demonstrated to contribute to various diseases, including cardiovascular diseases. Complement is extensively activated in atherosclerotic lesions, in arterial aneurysms, and in the myocardium of ischemic and failing hearts. Accumulating evidence shows that limitation of excessive complement activation under these conditions may hold therapeutic value. On the other hand, defects in the classical complement pathway predispose to vasculitis and atherosclerosis, possibly due to ineffective clearance of apoptotic/necrotic cells and abnormal processing of immune complexes. Here, we describe complement activation and regulation in cardiovascular diseases and discuss the evidence derived mainly from experimental animals suggesting that modulation of complement activation may alter the course of these disorders.