title: Nitric oxide promotes airway epithelial wound repair through enhanced activation of MMP-9.
abstract: The airway epithelium provides a protective barrier against inhaled environmental toxins and microorganisms, and epithelial injury initiates a number of processes to restore its barrier integrity, including activation of matrix metalloproteinases such as MMP-9 (92-kD gelatinase B). Airway epithelial cells continuously produce nitric oxide (NO), which has been linked to cell migration and MMP-9 regulation in several cell types, but the importance of epithelial NO in mediating airway epithelial repair or MMP-9 activation is unknown. Using primary or immortalized human bronchial epithelial cells, we demonstrate that low concentrations of NO promote epithelial cell migration and wound repair in an in vitro wound assay, which was associated with increased localized expression and activation of MMP-9. In addition, in HBE1 cells that were stably transfected with inducible NOS (NOS2), to mimic constitutive epithelial NOS2 expression in vivo, NOS inhibition decreased epithelial wound repair and MMP-9 expression. The stimulatory effects of NO on epithelial wound repair and MMP-9 expression were dependent on cGMP-mediated pathways and were inhibited by 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase. Inhibition of cGMP-dependent protein kinase (PKG) attenuated NO-mediated epithelial wound closure, but did not affect MMP-9 expression. However, pharmacologic MMP inhibition and siRNA knockdown of MMP-9 expression demonstrated the contribution of MMP-9 to NO-mediated wound closure. Overall, our results demonstrate that NOS2-derived NO contributes to airway epithelial repair by both PKG-dependent and -independent mechanisms, and involves NO-dependent expression and activation of MMP-9.
authors.affiliation: Department of Pathology, College of Medicine, University of Vermont, Burlington, VT 05405, USA.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Bove
authors.forename: Umadevi V
authors.initials: UV
authors.lastname: Wesley
authors.forename: Anne-Katrin
authors.initials: AK
authors.lastname: Greul
authors.forename: Milena
authors.initials: M
authors.lastname: Hristova
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Dostmann
authors.forename: Albert
authors.initials: A
authors.lastname: van der Vliet
mesh_terms: D002465:Cell Movement / Q000187:drug effects; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D018093:Gelatinases / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis / Q000494:pharmacology*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009603:Nitroso Compounds / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012137:Respiratory System / Q000166:cytology* / Q000201:enzymology*; D014945:Wound Healing / Q000187:drug effects*; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D009603:Nitroso Compounds; D012333:RNA, Messenger; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D019323:omega-N-Methylarginine; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II; D018093:Gelatinases; D020780:Matrix Metalloproteinase 9; D006152:Cyclic GMP