Interleukin-10 counteracts impaired endothelium-dependent relaxation induced by ANG II in murine aortic rings

ANG II stimulates the production of reactive oxygen species and activates proinflammatory cytokines leading to endothelial dysfunction. We hypothesized that the antiinflammatory cytokine IL-10 counteracts the impairment in endothelium-dependent ACh relaxation caused by ANG II. Aortic rings of C57BL/6 mice were incubated in DMEM in the presence of vehicle (deionized H ₂O), ANG II (100 nmol/l), recombinant mouse IL-10 (300 ng/ml), or both ANG II and IL-10 for 22 h at 37̊C. After incubation, rings were mounted in a wire myograph to assess endothelium-dependent vasorelaxation to cumulative concentrations of ACh. Overnight exposure of aortic rings to ANG II resulted in blunted ACh-induced vasorelaxation compared with that shown in untreated rings (maximal response = 44 ± 3% vs. 64 ± 3%, respectively; P < 0.05). IL-10 treatment significantly restored this impairment in relaxation (63 ± 2%). In addition, the NADPH oxidase inhibitor apocynin restored the impairment in relaxation (maximal response = 76 ± 3%). Western blotting showed increased gp91^phox expression (a subunit of NADPH oxidase) in response to ANG II. Vessels treated with a combination of ANG II and IL-10 showed decreased expression of gp91 ^phox. Immunohistochemical analysis showed increased gp91 ^phox expression in ANG II-treated vessels compared with those treated with combined ANG II and IL-10. We found that the anti-inflammatory cytokine IL-10 prevents impairment in endothelium-dependent vasorelaxation in response to long-term incubation with ANG II via decreasing NADPH oxidase expression.