Restoration of endothelin-1-induced impairment in endothelium-dependent relaxation by interleukin-10 in murine aortic ringsThis article is one of a selection of papers published in the special issue (part 2 of 2) on Forefronts in Endothelin.

Abstract

Endothelin-1 (ET-1) is implicated in the development of endothelial dysfunction through the generation of reactive oxygen species by NADPH oxidase activation. Interleukin-10 (IL-10) is an antiinflammatory cytokine that stimulates nitric oxide production, decreases superoxide production, and restores endothelial integrity after vascular injury. In this study, we tested whether IL-10 attenuates ET-1-induced endothelial dysfunction by improving acetylcholine (ACh)-induced relaxation of cultured murine aortic rings. Aortic rings (2 mm long) of C57BL/6 mice were incubated in 2 mL DMEM containing 120 U/mL penicillin and 120 µg/mL streptomycin in the presence of one of 4 treatments: vehicle (deionized water), ET-1 (100 nmol/L), recombinant mouse IL-10 (300 ng/ mL), or a combination of both ET-1 and IL-10. After incubation at 37 °C for either 1 or 6 h (shortterm exposure) or 22 h (overnight exposure), rings were mounted in a wire myograph and stretched to a passive force of 5 mN. Endothelium-dependent vasorelaxation was assessed by constructing cumulative concentration-response curves to ACh (0.001-10 µmol/L) during 10 µmol/L phenylephrine (PE)-induced contraction. Short-term exposure of ET-1 did not result in an impairment of ACh-induced relaxation. Overnight exposure of aortic rings to ET-1 resulted in a statistically significant endothelial dysfunction characterized by a reduced maximal relaxation response to ACh compared with that of untreated rings (E max 57% ± 3% versus 82% ± 4%). IL-10 treatment restored ACh-induced relaxation (E max 77% ± 3%). Western blotting showed decreased eNOS expression in response to ET-1, whereas vessels treated with a combination of ET-1 and IL-10 showed increased expression of eNOS. Immunohistochemical analysis showed decreased eNOS expression in ET-1-treated vessels compared with those treated with both ET-1 and IL-10. We conclude that, in murine aorta, the antiinflammatory cytokine IL-10 prevents impairment in endothelium-dependent 1 This article is one of a selection of papers published in the special issue (part 2 of 2) on Forefronts in Endothelin.

Chronic social isolation in the prairie vole induces endothelial dysfunction: implications for depression and cardiovascular disease

“…First, the relaxant effects of ACh are expressed as relative (percent) not absolute changes in the PE-induced precontractions. This is common practice in all vascular contraction/relaxation experiments involving precontractions [35, 46, 48–50, 71–74] and is designed to correct for anticipated individual tissue differences in the absolute magnitude of the precontractile tensions. Second, the statistically significant attenuating effect of chronic social isolation on ACh-induced relaxation in the endothelium-intact tissues in question (Figure 2, left) is most noticeable at the maximum level of that relaxation (which occurred at the same ACh concentration, 10 −6 molar, in tissues from both paired and isolated animals).…”

“…After rinsing the same rings repeatedly with ACh-free buffer, they were treated again with multiple levels of ACh, except this time after first precontracting their smooth muscle with the selective alpha-1 adrenergic receptor agonist phenylephrine (PE). This allows evaluation of ACh-induced endothelium-dependent relaxation of such smooth muscle, due to stimulation of muscarinic receptors only in the endothelial layer [35], as widely conducted in aortic tissues from other species and usually expressed as % of the PE-induced precontraction [42, 46, 48–50]. We chose a PE concentration of 0.25 micromolar which in preliminary work caused nearly 50 % of maximum PE-induced contraction in our prairie vole aortas.…”

“…Finally, all the above aortic rings were rinsed repeatedly once more (with ACh- and PE-free buffer) and then, after precontracting again with PE, treated with multiple graded concentrations of the nitric oxide-donor NP to allow estimation of endothelium-independent relaxation of the underlying smooth muscle (also expressed as % of the PE-induced precontraction). NP is commonly employed for this purpose as a control measure for ACh relaxation tests in large conduit arteries like the aorta [46, 48–50]. In such vessels, the principal relaxing substance released by the endothelium in response to ACh is nitric oxide [52, 53].…”

The role of inflammation in the pathology of preeclampsia

“…IL-10 decreases inflammatory cytokines that are linked to oxidative stress, while promoting vascular healing, a necessary process for spiral artery remodeling and placental perfusion. These functions of IL-10 were shown to lead to a restoration of endothelin-dependent relaxation and increased eNOS expression in endothelin-1 treated aortic rings (148). IL-10 has also been shown to improve characteristics of PE in pregnant, DOCA/saline rats where investigators noted a decrease in circulating endothelin-1 and IFN-γ, restoration of aortic relaxation responses, decreased proteinuria and an improvement in litter size following IL-10 treatment (149).…”

IL-10 supplementation increases Tregs and decreases hypertension in the RUPP rat model of preeclampsia

“…These functions of IL-10 were shown to lead to a restoration of ET-1-dependent relaxation and increased eNOS expression in aortic rings (34,41). In addition, IL-10 has been shown to improve characteristics of PE in pregnant, DOCA/saline (PDS) rats by decreasing circulating ET-1 and IFN-γ, restoring aortic relaxation responses, decreasing proteinuria, and improving litter size following IL-10 treatment (40).…”