title: Nox1 causes ileocolitis in mice deficient in glutathione peroxidase-1 and -2.
abstract: We previously reported that mice deficient in two Se-dependent glutathione peroxidases, GPx1 and GPx2, have spontaneous ileocolitis. Disease severity depends on mouse genetic background. Whereas C57BL/6J (B6) GPx1/2-double-knockout (DKO) mice have moderate ileitis and mild colitis, 129S1Svlm/J (129) DKO mice have severe ileocolitis. Because GPx's are antioxidant enzymes, we hypothesized that elevated reactive oxygen species trigger inflammation in these DKO mice. To test whether NADPH oxidase 1 (Nox1) contributes to colitis, we generated B6 triple-KO (TKO) mice to study their phenotype. Because the Nox1 gene is X-linked, we analyzed the effects of Nox1 on male B6 TKO mice and female B6 DKO mice with the Nox1(+/-) (het-TKO) genotype. We found that the male TKO and female het-TKO mice are virtually disease-free when monitored from 8 through 50 days of age. Male TKO and female het-TKO mice have nearly no signs of disease (e.g., lethargy and perianal alopecia) that are often exhibited in the DKO mice; further, the slower growth rate of DKO mice is almost completely eliminated in male TKO and female het-TKO mice. Male TKO and female het-TKO mice no longer have the shortened small intestine present in the DKO mice. Finally, the pathological characteristics of the DKO ileum, including the high level of crypt apoptosis (analyzed by apoptotic figures, TUNEL, and cleaved caspase-3 immunohistochemical staining), high numbers of Ki-67-positive crypt epithelium cells, and elevated levels of monocytes expressing myeloperoxidase, are all significantly decreased in male TKO mice. The attenuated ileal and colonic pathology is also evident in female het-DKO mice. Furthermore, the male DKO ileum has eightfold higher TNF cytokine levels than TKO ileum. Nox1 mRNA is highly elevated in both B6 and 129 DKO ileum compared to wild-type mouse ileum. Taking these results together, we propose that ileocolitis in the DKO mice is caused by Nox1, which is induced by TNF. The milder disease in female het-TKO intestine is probably due to random or imprinted X-chromosome inactivation, which produces mosaic Nox1 expression.
authors.affiliation: Department of Radiation Biology and Beckman Research Institute, City of Hope, Duarte, CA 91010, USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Esworthy
authors.affiliation: Irell & Manella Graduate School of Biological Sciences, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA.
authors.forename: Byung-Wook
authors.initials: BW
authors.lastname: Kim
authors.affiliation: Department of Radiation Biology and Beckman Research Institute, City of Hope, Duarte, CA 91010, USA.
authors.forename: Joni
authors.initials: J
authors.lastname: Chow
authors.affiliation: Department of Radiation Biology and Beckman Research Institute, City of Hope, Duarte, CA 91010, USA.
authors.forename: Binghui
authors.initials: B
authors.lastname: Shen
authors.affiliation: National Cancer Institute, Bethesda, MD 20816, USA.
authors.forename: James H
authors.initials: JH
authors.lastname: Doroshow
authors.affiliation: Department of Radiation Biology and Beckman Research Institute, City of Hope, Duarte, CA 91010, USA. Electronic address: fchu@coh.org.
authors.forename: Fong-Fong
authors.initials: FF
authors.lastname: Chu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D003424:Crohn Disease / Q000201:enzymology* / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D005979:Glutathione Peroxidase / Q000172:deficiency / Q000235:genetics*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009247:NADH, NADPH Oxidoreductases / Q000096:biosynthesis / Q000235:genetics*; D000074624:NADPH Oxidase 1; D012333:RNA, Messenger / Q000096:biosynthesis; D048069:Tumor Necrosis Factors / Q000378:metabolism; D049951:X Chromosome Inactivation / Q000235:genetics; D000094765:Glutathione Peroxidase GPX1
chemical_list: D012333:RNA, Messenger; D048069:Tumor Necrosis Factors; C492172:Gpx2 protein, mouse; D005979:Glutathione Peroxidase; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; C000614711:NOX1 protein, mouse; D000094765:Glutathione Peroxidase GPX1; C000722068:Gpx1 protein, mouse
keywords: Apoptosis; C57BL/6J; Free radicals; Glutathione peroxidase; Inflammatory bowel disease; Mouse colon; Mouse ileum; NADPH oxidase; TNF