NAD(P)H oxidase mediates angiotensin II-induced vascular macrophage infiltration and medial hypertrophy.

OBJECTIVE Our preliminary data suggested that angiotensin II (Ang II)-induced reactive oxygen species are involved in intercellular adhesion molecule-1 (ICAM-1) expression and leukocyte infiltration in the rat thoracic aorta. Other reports demonstrating reactive oxygen species-induced cell growth suggested a potential role of NAD(P)H oxidase in vascular hypertrophy. In the present study, we postulate that NAD(P)H oxidase is functionally involved in Ang II-induced ICAM-1 expression, macrophage infiltration, and vascular growth, and that oxidase inhibition attenuates these processes independently of a reduction in blood pressure. METHODS AND RESULTS Rats were infused subcutaneously with vehicle or Ang II (750 microg/kg per day) for 1 week in the presence or absence of gp91 docking sequence (gp91ds)-tat peptide (1 mg/kg per day), a cell-permeant inhibitor of NAD(P)H oxidase. Immunohistochemical staining for ICAM-1 and ED1, a marker of monocytes and macrophages, showed that both were markedly increased with Ang II compared with vehicle and were reduced in rats receiving Ang II plus gp91ds-tat. This effect was accompanied by an Ang II-induced increase in medial hypertrophy that was attenuated by coinfusion of gp91ds-tat; however, gp91ds-tat had no effect on blood pressure. CONCLUSIONS Ang II-enhanced NAD(P)H oxidase plays a role in the induction of ICAM-1 expression, leukocyte infiltration, and vascular hypertrophy, acting independently of changes in blood pressure.