title: NADPH oxidase mediates synergistic effects of IL-17 and TNF-α on CXCL1 expression by epithelial cells after lung ischemia-reperfusion.
abstract: Ischemia-reperfusion (I/R) injury leads to increased mortality and morbidity in lung transplant patients. Lung I/R injury involves inflammation contributed by innate immune responses. IL-17 and TNF-α, from iNKT cells and alveolar macrophages, respectively, contribute importantly to lung I/R injury. This study tests the hypothesis that IL-17 and TNF-α synergistically mediate CXCL1 (a potent neutrophil chemokine) production by alveolar type II epithelial (ATII) cells via an NADPH oxidase-dependent mechanism during lung I/R. Using a hilar clamp model, wild-type and p47(phox-/-) (NADPH oxidase-deficient) mice underwent left lung I/R, with or without recombinant IL-17 and/or TNF-α treatment. Wild-type mice undergoing I/R treated with combined IL-17 and TNF-α had significantly enhanced lung dysfunction, edema, CXCL1 production, and neutrophil infiltration compared with treatment with IL-17 or TNF-α alone. However, p47(phox-/-) mice had significantly less pulmonary dysfunction, CXCL1 production, and lung injury after I/R that was not enhanced by combined IL-17-TNF-α treatment. Moreover, in an acute in vitro hypoxia-reoxygenation model, murine ATII cells showed a multifold synergistic increase in CXCL1 expression after combined IL-17-TNF-α treatment compared with treatment with either cytokine alone, which was significantly attenuated by an NADPH oxidase inhibitor. Conditioned media transfer from hypoxia-reoxygenation-exposed iNKT cells and macrophages, major sources of IL-17 and TNF-α, respectively, to ATII cells significantly enhanced CXCL1 production, which was blocked by NADPH oxidase inhibitor. These results demonstrate that IL-17 and TNF-α synergistically mediate CXCL1 production by ATII cells after I/R, via an NADPH oxidase-dependent mechanism, to induce neutrophil infiltration and lung I/R injury.
authors.affiliation: Dept. of Surgery, Univ. of Virginia, P.O. Box 801359, Charlottesville, VA 22908. laubach@virginia.edu.
authors.forename: Ashish K
authors.initials: AK
authors.lastname: Sharma
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Mulloy
authors.forename: Lamvy T
authors.initials: LT
authors.lastname: Le
authors.forename: Victor E
authors.initials: VE
authors.lastname: Laubach
mesh_terms: D000403:Airway Resistance; D056809:Alveolar Epithelial Cells / Q000378:metabolism*; D000818:Animals; D001794:Blood Pressure; D002478:Cells, Cultured; D054360:Chemokine CXCL1 / Q000378:metabolism*; D020381:Interleukin-17 / Q000378:metabolism*; D008168:Lung / Q000098:blood supply / Q000276:immunology / Q000503:physiopathology; D016676:Macrophages, Alveolar / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019255:NADPH Oxidases / Q000502:physiology*; D055611:Natural Killer T-Cells / Q000276:immunology / Q000378:metabolism; D020556:Neutrophil Infiltration; D009195:Peroxidase / Q000378:metabolism; D011651:Pulmonary Artery / Q000503:physiopathology; D011654:Pulmonary Edema / Q000201:enzymology / Q000276:immunology; D015427:Reperfusion Injury / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D054360:Chemokine CXCL1; C475895:Cxcl1 protein, mouse; D020381:Interleukin-17; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D009195:Peroxidase; D019255:NADPH Oxidases
keywords: alveolar epithelial cells; ischemia-reperfusion injury; lung transplant; primary graft dysfunction