In vitro effects of exogenous carbon monoxide on oxidative stress and lipid metabolism in macrophages.

Carbon monoxide (CO) is a major constituent of traffic-related air pollution and is also produced endogenously under conditions of oxygen-mediated stress. It has been shown to affect both oxidative stress and inflammation. However, its role in lipid metabolism has been neglected. Using short exposure times, the effect of CO on J774A.1 macrophage atherogenic functions was investigated up to 16 h after exposure. Exposure of macrophages was found to be pro-atherogenic as it significantly increased triglyceride mass, up to 60%, and decreased high-density lipoprotein-mediated cholesterol efflux, up to 27%. In contrast, paraoxonase 2 lactonase activity was increased, up to 65%, and cellular oxidative stress was attenuated by 29%, compared with the control cells. The above results on lipid metabolism may lead to arterial macrophage foam cell formation, the hallmark of early atherogenesis.