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Combined NADPH oxidase 1 and interleukin 10 deficiency induces chronic endoplasmic reticulum stress and causes ulcerative colitis-like disease in mice.

ABSTRACT: Ulcerative colitis (UC) is a chronic inflammatory bowel disease affecting the rectum which progressively extents. Its etiology remains unknown and the number of treatments available is limited. Studies of UC patients have identified an unbalanced endoplasmic reticulum (ER) stress in the non-inflamed colonic mucosa. Animal models with impaired ER stress are sensitive to intestinal inflammation, suggesting that an unbalanced ER stress could cause inflammation. However, there are no ER stress-regulating strategies proposed in the management of UC partly because of the lack of relevant preclinical model mimicking the disease. Here we generated the IL10/Nox1dKO mouse model which combines immune dysfunction (IL-10 deficiency) and abnormal epithelium (NADPH oxidase 1 (Nox1) deficiency) and spontaneously develops a UC-like phenotype with similar complications (colorectal cancer) than UC. Our data identified an unanticipated combined role of IL10 and Nox1 in the fine-tuning of ER stress responses in goblet cells. As in humans, the ER stress was unbalanced in mice with decreased eIF2? phosphorylation preceding inflammation. In IL10/Nox1dKO mice, salubrinal preserved eIF2? phosphorylation through inhibition of the regulatory subunit of the protein phosphatase 1 PP1R15A/GADD34 and prevented colitis. Thus, this new experimental model highlighted the central role of epithelial ER stress abnormalities in the development of colitis and defined the defective eIF2? pathway as a key pathophysiological target for UC. Therefore, specific regulators able to restore the defective eIF2? pathway could lead to the molecular remission needed to treat UC.

SUBMITTER: Treton X

PROVIDER: S-EPMC4090121 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Combined NADPH oxidase 1 and interleukin 10 deficiency induces chronic endoplasmic reticulum stress and causes ulcerative colitis-like disease in mice.

Tréton Xavier X Pedruzzi Eric E Guichard Cécile C Ladeiro Yannick Y Sedghi Shirin S Vallée Mélissa M Fernandez Neike N Bruyère Emilie E Woerther Paul-Louis PL Ducroc Robert R Montcuquet Nicolas N Freund Jean-Noel JN Van Seuningen Isabelle I Barreau Frédérick F Marah Assiya A Hugot Jean-Pierre JP Cazals-Hatem Dominique D Bouhnik Yoram Y Daniel Fanny F Ogier-Denis Eric E

PloS one 20140709 7

Ulcerative colitis (UC) is a chronic inflammatory bowel disease affecting the rectum which progressively extents. Its etiology remains unknown and the number of treatments available is limited. Studies of UC patients have identified an unbalanced endoplasmic reticulum (ER) stress in the non-inflamed colonic mucosa. Animal models with impaired ER stress are sensitive to intestinal inflammation, suggesting that an unbalanced ER stress could cause inflammation. However, there are no ER stress-regul ...[more]

PMID: 25014110

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Project description:BackgroundMUC2 mucin produced by intestinal goblet cells is the major component of the intestinal mucus barrier. The inflammatory bowel disease ulcerative colitis is characterized by depleted goblet cells and a reduced mucus layer, but the aetiology remains obscure. In this study we used random mutagenesis to produce two murine models of inflammatory bowel disease, characterised the basis and nature of the inflammation in these mice, and compared the pathology with human ulcerative colitis.Methods and findingsBy murine N-ethyl-N-nitrosourea mutagenesis we identified two distinct noncomplementing missense mutations in Muc2 causing an ulcerative colitis-like phenotype. 100% of mice of both strains developed mild spontaneous distal intestinal inflammation by 6 wk (histological colitis scores versus wild-type mice, p < 0.01) and chronic diarrhoea. Monitoring over 300 mice of each strain demonstrated that 25% and 40% of each strain, respectively, developed severe clinical signs of colitis by age 1 y. Mutant mice showed aberrant Muc2 biosynthesis, less stored mucin in goblet cells, a diminished mucus barrier, and increased susceptibility to colitis induced by a luminal toxin. Enhanced local production of IL-1beta, TNF-alpha, and IFN-gamma was seen in the distal colon, and intestinal permeability increased 2-fold. The number of leukocytes within mesenteric lymph nodes increased 5-fold and leukocytes cultured in vitro produced more Th1 and Th2 cytokines (IFN-gamma, TNF-alpha, and IL-13). This pathology was accompanied by accumulation of the Muc2 precursor and ultrastructural and biochemical evidence of endoplasmic reticulum (ER) stress in goblet cells, activation of the unfolded protein response, and altered intestinal expression of genes involved in ER stress, inflammation, apoptosis, and wound repair. Expression of mutated Muc2 oligomerisation domains in vitro demonstrated that aberrant Muc2 oligomerisation underlies the ER stress. In human ulcerative colitis we demonstrate similar accumulation of nonglycosylated MUC2 precursor in goblet cells together with ultrastructural and biochemical evidence of ER stress even in noninflamed intestinal tissue. Although our study demonstrates that mucin misfolding and ER stress initiate colitis in mice, it does not ascertain the genetic or environmental drivers of ER stress in human colitis.ConclusionsCharacterisation of the mouse models we created and comparison with human disease suggest that ER stress-related mucin depletion could be a fundamental component of the pathogenesis of human colitis and that clinical studies combining genetics, ER stress-related pathology and relevant environmental epidemiology are warranted.

Project description:Vascular Nox (NADPH oxidase)-derived reactive oxygen species and endoplasmic reticulum (ER) stress have been implicated in hypertension. However, relationships between these processes are unclear. We hypothesized that Nox isoforms localize in a subcellular compartment-specific manner, contributing to oxidative and ER stress, which influence the oxidative proteome and vascular function in hypertension. Nox compartmentalization (cell fractionation), O2- (lucigenin), H2O2 (amplex red), reversible protein oxidation (sulfenylation), irreversible protein oxidation (protein tyrosine phosphatase, peroxiredoxin oxidation), and ER stress (PERK [protein kinase RNA-like endoplasmic reticulum kinase], IRE1? [inositol-requiring enzyme 1], and phosphorylation/oxidation) were studied in spontaneously hypertensive rat (SHR) vascular smooth muscle cells (VSMCs). VSMC proliferation was measured by fluorescence-activated cell sorting, and vascular reactivity assessed in stroke-prone SHR arteries by myography. Noxs were downregulated by short interfering RNA and pharmacologically. In SHR, Noxs were localized in specific subcellular regions: Nox1 in plasma membrane and Nox4 in ER. In SHR, oxidative stress was associated with increased protein sulfenylation and hyperoxidation of protein tyrosine phosphatases and peroxiredoxins. Inhibition of Nox1 (NoxA1ds), Nox1/4 (GKT137831), and ER stress (4-phenylbutyric acid/tauroursodeoxycholic acid) normalized SHR vascular reactive oxygen species generation. GKT137831 reduced IRE1? sulfenylation and XBP1 (X-box binding protein 1) splicing in SHR. Increased VSMC proliferation in SHR was normalized by GKT137831, 4-phenylbutyric acid, and STF083010 (IRE1-XBP1 disruptor). Hypercontractility in the stroke-prone SHR was attenuated by 4-phenylbutyric acid. We demonstrate that protein hyperoxidation in hypertension is associated with oxidative and ER stress through upregulation of plasmalemmal-Nox1 and ER-Nox4. The IRE1-XBP1 pathway of the ER stress response is regulated by Nox4/reactive oxygen species and plays a role in the hyperproliferative VSMC phenotype in SHR. Our study highlights the importance of Nox subcellular compartmentalization and interplay between cytoplasmic reactive oxygen species and ER stress response, which contribute to the VSMC oxidative proteome and vascular dysfunction in hypertension.

Project description:Human corneal-endothelial cells (hCEnCs) are located on the inner layer of the cornea. Injury to CEnCs leads to permanent corneal edema, requiring corneal transplantation. NADPH oxidase 4 (NOX4) has been reported to be implicated in the pathogenesis of CEnCs diseases. Thus, we investigated the role of NOX4 in CEnCs in this study. In an animal study, siRNA for NOX4 (siNOX4) or plasmid for NOX4 (pNOX4) was introduced into the corneal endothelium of rats by electroporation, using a square-wave electroporator (ECM830, Havard apparatus) to decrease or increase the expression of NOX4, respectively, and the rat corneas were cryoinjured through contact with a metal rod of 3 mm diameter frozen in liquid nitrogen for 10 min. The immunofluorescence staining of NOX4 and 8-OHdG showed that the levels of NOX4 and 8-OHdG were decreased in the siNOX4 group compared to the siControl, and increased in the pNOX4 group compared to the pControl at one week after treatment. Without cryoinjury, corneal opacity was more severe, and the density of CEnCs was lower, in pNOX4-treated rats compared to pControl. After cryoinjury, the corneas were more transparent, and the CEnC density was higher, in siNOX4-treated rats. The hCEnCs were cultured and transfected with siNOX4 and pNOX4. The silencing of NOX4 in hCEnCs resulted in a normal cell shape, higher viability, and higher proliferation rate than those transfected with the siControl, while NOX4 overexpression had the opposite effect. NOX4 overexpression increased the number of senescent cells and intracellular oxidative stress levels. NOX4 overexpression increased ATF4 and ATF6 levels, and nuclear translocation of XBP-1, which is the endoplasmic reticulum (ER) stress marker, while the silencing of NOX4 had the opposite effect. Additionally, the mitochondrial membrane potential was hyperpolarized by the silencing of NOX4, and depolarized by NOX4 overexpression. The LC3II levels, a marker of autophagy, were decreased by the silencing of NOX4, and increased by NOX4 overexpression. In conclusion, NOX4 plays a pivotal role in the wound-healing and senescence of hCEnCs, by modulating oxidative stress, ER stress, and autophagy. The regulation of NOX4 may be a potential therapeutic strategy for regulating the homeostasis of CEnCs, and treating corneal-endothelial diseases.

Dataset Information

Combined NADPH oxidase 1 and interleukin 10 deficiency induces chronic endoplasmic reticulum stress and causes ulcerative colitis-like disease in mice.

Publications

Combined NADPH oxidase 1 and interleukin 10 deficiency induces chronic endoplasmic reticulum stress and causes ulcerative colitis-like disease in mice.

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