IL-6 deficiency protects against angiotensin II induced endothelial dysfunction and hypertrophy.

OBJECTIVE The goal of this study was to test the hypothesis that IL-6 mediates the increases in superoxide, vascular hypertrophy, and endothelial dysfunction in response to angiotensin II (Ang II). METHODS AND RESULTS Responses of carotid arteries from control and IL-6-deficient mice were examined after acute (22-hour) incubation with Ang II (10 nmol/L) or chronic infusion of Ang II (1.4 mg/kg/d for 14 days). The hypertrophic response and endothelial dysfunction produced by Ang II infusion was markedly less in carotid arteries from IL-6-deficient mice than that in control mice. IL-6 deficiency also protected against endothelial dysfunction in response to acute (local) Ang II treatment (eg, 100 mumol/L acetylcholine produced 100+/-4 and 98+/-4% relaxation in vehicle-treated and 51+/-4 and 99+/-4% relaxation in Ang II-treated, control, and IL-6-deficient vessels, respectively). Endothelial dysfunction could be reproduced in vessels from IL-6-deficient mice with combined Ang II plus IL-6 (0.1 nmol/L) treatment. Increases in vascular superoxide and IL-6, as well as reductions in endothelial nitric oxide synthase mRNA expression, produced by Ang II were absent in IL-6-deficient mice. CONCLUSIONS These data demonstrate that IL-6 is essential for Ang II-induced increases in superoxide, endothelial dysfunction, and vascular hypertrophy.