動脈硬化と酸化ストレス(<特集>動脈硬化とアフェレシス)

Abstract

In the presence of reactive oxygen species (ROS) such as hydrogen peroxide (H_2O_2) and the superoxide anion (O_2^-), low-density lipoprotein (LDL) cholesterol can become oxidized to form a highly atherogenic lipoprotein species. In an in vivo study, ROS production was demonstrated in human atherosclerotic plaques and human coronary resistant arteries. Moreover, the role of ROS in the proatherogenic actions of angiotensin II (Ang II) has been well documented in a number of experimental studies. In VSMC in vitro, subnanomolar concentrations of Ang II induces NAD (P) H oxidase activity, in which the ROS produced serve as intracellular secondary messengers, mediating the mitogenic response. Thus, induction of vascular ROS tone is probably a major mechanism by which Ang II enhances atherosclerosis. Antioxidant therapy is supposed to be effective in the early stage of atherosclerosis by preventing LDL oxidation and oxidative lesion of the endothelium. Bioactive components of food which are of special interest, including vitamin E, vitamin C, and β-carotene, are characterized by antioxidant properties. There have been several prospective, placebo-control, randomized clinical trials to evaluate the efficacy of these compounds. However, results are not consistent and thus further studies are necessary.