LOCALIZATION OF DISTINCT F-2-ISOPROSTANES IN HUMAN ATHEROSCLEROTIC LESIONS

F-2-Isoprostanes are prostaglandin (PG) isomers formed in situ in cell membranes by peroxidation of arachidonic acid. 8-epi PGF(2 alpha) and IPF2 alpha-I are F-2-isoprostanes produced in humans which circulate in plasma and are excreted in urine. Measurement of F-2-isoprostanes m ay offer a sensitive, specific, and noninvasive method for measuring o xidant stress in clinical settings where reactive oxygen species are p utatively involved. We determined whether isoprostanes were present in human atherosclerotic lesions, where lipid peroxidation is thought to occur in vivo. 8-epi PGF(2 alpha) ranged from 1.310-3.450 pmol/mu mol phospholipid in atherectomy specimens compared with 0.045-0.115 pmol/ mu mol phospholipid (P < 0.001) in vascular tissue devoid of atheroscl erosis. Corresponding values of IPF2 alpha-I were 5.6-13.8 vs. 0.16-0. 44 pmol/mu mol phospholipid (P < 0.001). Levels of the two isoprostane s in vascular tissue were highly correlated (r = 0.80, P < 0.0001). Im munohistochemical studies confirmed that foam cells adjacent to the li pid necrotic core of the plaque were markedly positive for 8-epi PGF(2 alpha). These cells were also reactive with anti-CD68, and epitope sp ecific for human monocyte/macrophages. 8-epi PGF(2 alpha) immunoreacti vity was also detected in cells positive for anti-alpha-smooth muscle actin antibody, which specifically recognizes vascular smooth muscle c ells. Our results indicate that 8-epi PGF(2 alpha) and IPF2 alpha-I, t wo distinct F-2-isoprostanes and markers of oxidative stress in vivo, are present in human atherosclerotic plaque. Quantitation of these che mically stable products of lipid peroxidation in target tissues, as we ll as in biological fluids, map aid in the rational development of ant ioxidant drugs in humans.