Angiotensin II type 1 receptor-mediated peroxide production in human macrophages

Our previous experiments demonstrated upregulation of the renin-angiotensin system in macrophages, including angiotensin II type 1 (AT1) and type 2 (A T2) receptors, during transformation from monocytes. We investigated the ro le of angiotensin II in oxidative stress of monocytes/macrophages, which pl ays a role in the advance of atherosclerosis. THP1, a human monocytic leuke mia cell line, was differentiated re macrophages by adding of phorbol 12-my ristate 13-acetate for 24 hours. The intracellular production of peroxide w as measured by a cytofluorometric assay with 2',7'-dichlorofluorescein-diac etate with a flow cytometer scan. Peroxide was detected in monocytes and up regulated during the transformation to macrophages by 3.18+/-0.52 times in relative fluorescein of peak value (P<0.01). Angiotensin II (1 mu mol/L) in duced oxidative stress in macrophages, with the peak at 15 minutes by 451+/ -223%, and returned to the control level within 1 hour. EC50 was 5.4x10(-9) mol/L. AT1 antagonist (CV11974, 1 mu mol/L) significantly decreased angiot ensin II-induced oxidative stress in macrophages, but AT2 antagonist (PD123 319, 1 mu mol/L) did not. Of interest, AT1 antagonist also decreased basal levels of peroxide production in macrophages in a dose-dependent manner. Th ese results suggest that upregulation of the expression of AT1 receptor in macrophages contributes in part to upregulation of peroxide production. AT1 receptor antagonists may be useful to suppress oxidative stress of macroph ages in atherosclerotic lesions.