title: Relaxin improves TNF-α-induced endothelial dysfunction: the role of glucocorticoid receptor and phosphatidylinositol 3-kinase signalling.
abstract: OBJECTIVE
  Human relaxin-2 influences renal and cardiovascular functions. We investigated its effects on experimental endothelial dysfunction.
  
  
  RESULTS
  Acetylcholine-mediated vasodilation of rat aortic rings, impaired by 48 h tumour necrosis factor-α (TNF-α) treatment, was dose-dependently improved by relaxin co-incubation, an effect sensitive to phosphatidylinositol 3-kinase (PI3K) inhibition and the glucocorticoid receptor (GR) antagonist RU-486. TNF increased endothelial nitric oxide synthase (eNOS) phosphorylation at Thr495 and decreased total eNOS expression and both basal and stimulated eNOS activity. Relaxin co-incubation did not affect eNOS expression but improved its activity via PI3K-dependent Thr495 dephosphorylation and Ser1177 phosphorylation, and additional Ser633 phosphorylation. Via GR, relaxin attenuated the TNF-related stimulation of endothelin-1 expression, superoxide and nitrotyrosine formation, and arginase II expression. Relaxin restored, via GR-CCAAT/enhancer-binding protein-β (c/EBP-β)-mediated promoter stimulation, the compromised expression of superoxide dismutase-1 (SOD1). In rat aortic endothelial cells, relaxin activated protein kinase B (Akt) and repressed TNF-induced nuclear factor-κB and activator protein-1. Finally, the relevance of the different findings to the model used was proved by pharmacological interventions.
  
  
  CONCLUSIONS
  Relaxin improved endothelial dysfunction by promoting eNOS activity, suppressing endothelin-1 and arginase-II expression, and up-regulating SOD1 via GR, GR-c/EBP-β, and PI3K-Akt pathways. This corroborates the notion that it functions as an endogenous and potentially therapeutic vasoprotector.
authors.affiliation: Immundiagnostik AG, Stubenwaldallee 8a, Bensheim, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dschietzig
authors.forename: Anna
authors.initials: A
authors.lastname: Brecht
authors.forename: Cornelia
authors.initials: C
authors.lastname: Bartsch
authors.forename: Gert
authors.initials: G
authors.lastname: Baumann
authors.forename: Karl
authors.initials: K
authors.lastname: Stangl
authors.forename: Konstantin
authors.initials: K
authors.lastname: Alexiou
mesh_terms: D000818:Animals; D001119:Arginase / Q000378:metabolism; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism; D016328:NF-kappa B / Q000502:physiology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011965:Receptors, Glucocorticoid / Q000502:physiology*; D012065:Relaxin / Q000494:pharmacology*; D015398:Signal Transduction / Q000502:physiology*; D013482:Superoxide Dismutase / Q000235:genetics; D000072105:Superoxide Dismutase-1; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; D016328:NF-kappa B; D011965:Receptors, Glucocorticoid; C000606290:SOD1 protein, human; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D012065:Relaxin; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; C000606292:Sod1 protein, rat; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D001119:Arginase; C542908:arginase I, rat