Exposure of human keratinocytes to ischemia, hyperglycemia and their combination induces oxidative stress via the enzymes inducible nitric oxide synthase and xanthine oxidase

• Published in: Journal of dermatological science 2009-08, Vol.55 (2), p.82-90
• Main Authors: Portugal-Cohen, Meital, Kohen, Ron
• Format: Article
• Language: English
• Subjects: Biomarkers - metabolism; Cell Hypoxia; Cell Line; Cell Survival; Dermatology; Glucose - metabolism; Glutathione - metabolism; Glutathione Disulfide - metabolism; Humans; Hyperglycemia; Hyperglycemia - enzymology; Hyperglycemia - immunology; Hyperglycemia - pathology; Inducible nitric oxide synthase (iNOS); Inflammation Mediators - metabolism; Interleukin-6 - metabolism; Ischemia - enzymology; Ischemia - immunology; Ischemia - pathology; Ischemia-reperfusion injury (IRI); Keratinocytes - enzymology; Keratinocytes - immunology; Keratinocytes - pathology; Nitric Oxide - metabolism; Nitric Oxide Synthase Type II - metabolism; Nitrites - metabolism; Oxidative Stress; Reactive oxygen species (ROS); Reperfusion Injury - enzymology; Reperfusion Injury - immunology; Reperfusion Injury - pathology; Superoxides - metabolism; Total antioxidant scavenging capacity (TSC); Uric Acid - metabolism; Xanthine oxidase (XO); Xanthine Oxidase - metabolism
• ISSN: 0923-1811; 1873-569X
• DOI: 10.1016/j.jdermsci.2009.05.006

Abstract Background Diabetes mellitus is characterized by a chronic hyperglycemia and might cause skin pathologies resulting from an ischemic insult. A variety of mechanisms have been suggested for the damage provided by ischemia-reperfusion injury (IRI) or for hyperglycemic conditions. Yet, the association between IRI and hyperglycemia together in skin has been poorly investigated even thought they are both present in diabetic patients. Objective To examine the effect of a dual stress combining IRI and hyperglycemia on human keratinocytes—its ability to cause oxidative damage and inflammatory response via the enzymes xanthine oxidase (XO) and inducible nitric oxide synthase (iNOS). Methods HaCaT cells were used as a model to induce IRI and hyperglycemia. In order to assess the oxidative damage, total antioxidant scavenging capacity (TSC) and GSH/GSSG ratio were evaluated. iNOS expression was evaluated and its metabolite nitric oxide was estimated by measuring nitrite levels. XO activity was assessed by uric acid quantification and by superoxide radical formation. Inflammatory response was determined through interleukin-6 secretion. Results Our observations demonstrate different responses of the cells exposed to single stress (IRI) compared to dual stress combining also hyperglycemia. However, cells response exhibited similarity during reperfusion, by enhancing iNOS expression as well as superoxide levels. While ischemia led to changes in TSC and redox state, reperfusion restored them to basal levels. IRI also caused the enhancement of secreted IL-6 and uric acid levels. Conclusion iNOS and XO play a major role in IRI and hyperglycemia. Inhibition of one of these enzymes may be beneficial to skin cells under these conditions.