Xanthine Oxidoreductase Function Contributes to Normal Wound Healing
Chronic, nonhealing wounds result in patient morbidity and disability. Reactive oxygen species (ROS) and nitric oxide (NO) are both required for normal wound repair, and derangements of these result in impaired healing. Xanthine oxidoreductase (XOR) has the unique capacity to produce both ROS and NO. We hypothesize that XOR contributes to normal wound healing. Cutaneous wounds were created in C57Bl6 mice. XOR was inhibited with dietary tungsten or allopurinol. Topical hydrogen peroxide (H2O2, 0.15%) or allopurinol (30 µg) was applied to wounds every other day. Wounds were monitored until closure or collected at d 5 to assess XOR expression and activity, cell proliferation and histology. The effects of XOR, nitrite, H2O2 and allopurinol on keratinocyte cell (KC) and endothelial cell (EC) behavior were assessed. We identified XOR expression and activity in the skin and wound edges as well as granulation tissue. Cultured human KCs also expressed XOR. Tungsten significantly inhibited XOR activity and impaired healing with reduced ROS production with reduced angiogenesis and KC proliferation. The expression and activity of other tungsten-sensitive enzymes were minimal in the wound tissues. Oral allopurinol did not reduce XOR activity or alter wound healing but topical allopurinol significantly reduced XOR activity and delayed healing. Topical H2O2 restored wound healing in tungsten-fed mice. In vitro, nitrite and H2O2 both stimulated KC and EC proliferation and EC migration. These studies demonstrate for the first time that XOR is abundant in wounds and participates in normal wound healing through effects on ROS production.
We gratefully acknowledge the excellent technical assistance provided by NJ Hundley, SI Zharikov and N Cantu-Medellin. This material is based on work supported in part by the Department of Veterans Affairs, Veterans Health Administration and Office of Biomedical Laboratory Research and Development (ET), through funding from the National Institutes of Health (NIH) (NIH T32 HL098036 to MC Madigan, RM McEnaney and AJ Shukla and NIH R01 HL058115 to MM Tarpey). M Gladwin received research support from NIH grants R01HL098032, R01HL096973 and PO1HL103455 as well as from the Institute for Transfusion Medicine and the Hemophilia Center of Western Pennsylvania.
The contents of this manuscript do not represent the views of the Department of Veterans Affairs or the United States Government.
- 29.Committee for the Update of the Guide for the Care and Use of Laboratory Animals, Institute for Laboratory Animal Research, Division on Earth and Life Studies, National Research Council of the National Academies. (2011) Guide for the Care and Use of Laboratory Animals. 8th edition. Washington (DC): National Academies Press.Google Scholar
- 31.Kibbe MR, et al. (2000) Inducible nitric oxide synthase (iNOS) expression upregulates p21 and inhibits vascular smooth muscle cell proliferation through p42/44 mitogen-activated protein kinase activation and independent of p53 and cyclic guanosine monophosphate. J. Vasc. Surg. 31:1214–28.CrossRefGoogle Scholar
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