Regulation of programmed cell death or apoptosis in atherosclerosis.

Intimal thickening caused by accumulation of cells, lipids, and connective tissue characterizes atherosclerosis, an arterial disease that leads to cardiac and cerebral infarction. Apoptosis, or genetically programmed cell death, is important for the development and morphogenesis of organs and tissues. As in other tissues, cells of cardiovascular tissues can undergo apoptosis. Increased apoptosis has been found in both human and animal atherosclerotic lesions, mediating tissue turnover and lesion development. In addition to vascular cells, many activated immune cells, mainly macrophages and T cells, are present in atherosclerotic lesions, where these cells produce biologically active substances such as the proinflammatory cytokines tumor necrosis factor, interleukin-1 (IL-1), and interferon-gamma. Simultaneous exposure to these cytokines may trigger apoptosis of vascular smooth muscle cells. The products of death-regulating genes including Fas/Fas ligand, members of IL-1 beta cysteinyl protease (caspase) family, the tumor suppressive gene p53, and the protooncogene c-myc have been found in vascular cells and may participate in the regulation of vascular apoptosis during the development of atherosclerosis. Abnormal occurrence of apoptosis may take place in atherosclerotic lesions, including attenuation or acceleration of the apoptotic death process. The former may cause an increase in the cellularity of the lesions, and the latter can reduce cellular components important for maintaining the integrity and stability of the plaques. Clarification of the molecular mechanism that regulates apoptosis may help design a new strategy for treatment of patients with atherosclerosis and its major complications, heart attack and stroke.