title: Heme oxygenase-1-derived bilirubin protects endothelial cells against high glucose-induced damage.
abstract: Hyperglycemia and diabetes are associated with endothelial cell dysfunction arising from enhanced oxidative injury, leading to the progression of diabetic vascular pathologies. The redox-sensitive transcription factor nuclear factor-E2-related factor 2 (Nrf2) is a master regulator of antioxidant genes, such as heme oxygenase-1 (HO-1), involved in cellular defenses against oxidative stress. We have investigated the pathways involved in high glucose-induced activation of HO-1 in endothelial cells and examined the molecular mechanisms underlying cytoprotection. Elevated d-glucose increased intracellular generation of reactive oxygen species (ROS), leading to nuclear translocation of Nrf2 and HO-1 expression in bovine aortic endothelial cells, with no changes in cell viability. Superoxide scavenging and inhibition of endothelial nitric oxide synthase (eNOS) abrogated upregulation of HO-1 expression by elevated glucose. Inhibition of HO-1 increased the sensitivity of endothelial cells to high glucose-mediated damage, while addition of bilirubin restored cell viability. Our findings establish that exposure of endothelial cells to high glucose leads to activation of endogenous antioxidant defense genes via the Nrf2/ARE pathway. Upregulation of HO-1 provides cytoprotection against high glucose-induced oxidative stress through the antioxidant properties of bilirubin. Modulation of the Nrf2 pathway in the early stages of diabetes may thus protect against sustained damage by hyperglycemia during progression of the disease.
authors.affiliation: Cardiovascular Division, British Heart Foundation Centre of Research Excellence, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK.
authors.forename: Meihua
authors.initials: M
authors.lastname: He
authors.affiliation: Department of Experimental Medicine, General Pathology Section, University of Genoa, 2L.B. Alberti Street, Genoa, Italy.
authors.forename: Mariapaola
authors.initials: M
authors.lastname: Nitti
authors.affiliation: Department of Experimental Medicine, General Pathology Section, University of Genoa, 2L.B. Alberti Street, Genoa, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Piras
authors.affiliation: Giannina Gaslini Institute, 16147 Genoa, Italy.
authors.forename: Anna Lisa
authors.initials: AL
authors.lastname: Furfaro
authors.affiliation: Department of Experimental Medicine, General Pathology Section, University of Genoa, 2L.B. Alberti Street, Genoa, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Traverso
authors.affiliation: Department of Experimental Medicine, General Pathology Section, University of Genoa, 2L.B. Alberti Street, Genoa, Italy.
authors.forename: Maria Adelaide
authors.initials: MA
authors.lastname: Pronzato
authors.affiliation: Cardiovascular Division, British Heart Foundation Centre of Research Excellence, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, UK. Electronic address: giovanni.mann@kcl.ac.uk.
authors.forename: Giovanni E
authors.initials: GE
authors.lastname: Mann
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001011:Aorta / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D001663:Bilirubin / Q000494:pharmacology*; D015153:Blotting, Western; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019610:Cytoprotection; D024202:Electrophoretic Mobility Shift Assay; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000633:toxicity*; D051547:Heme Oxygenase-1 / Q000378:metabolism*; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D017382:Reactive Oxygen Species; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013549:Sweetening Agents / Q000633:toxicity
chemical_list: D000975:Antioxidants; D051267:NF-E2-Related Factor 2; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013549:Sweetening Agents; D051547:Heme Oxygenase-1; D005947:Glucose; D001663:Bilirubin
keywords: Bilirubin; Endothelial cells; Heme oxygenase-1; Hyperglycemia; Nrf2; Oxidative stress; eNOS