Dataset Information

Dextran Sulfate Sodium Colitis Facilitates Colonization with Shiga Toxin-Producing Escherichia coli: a Novel Murine Model for the Study of Shiga Toxicosis.

ABSTRACT: Shiga toxin-producing Escherichia coli (STEC) bacteria are globally important gastrointestinal pathogens causing hemorrhagic gastroenteritis with variable progression to potentially fatal Shiga toxicosis. Little is known about the potential effects of E. coli-derived Shiga-like toxins (STXs) on host gastrointestinal immune responses during infection, in part due to the lack of a reproducible immunocompetent-animal model of STEC infection without depleting the commensal microbiota. Here, we describe a novel and reproducible murine model utilizing dextran sulfate sodium (DSS) colitis to induce susceptibility to colonization with clinical-isolate STEC strains. After exposure to DSS and subsequent oral STEC challenge, all the mice were colonized, and 66% of STEC-infected mice required early euthanasia. Morbidity during STEC infection, but not infection with an isogenic STEC mutant with toxin deleted, was associated with increased renal transcripts of the injury markers KIM1 and NGAL, histological evidence of renal tubular injury, and increased renal interleukin 6 gene (IL-6) and CXCL1 inflammatory transcripts. Interestingly, the intestinal burden of STEC during infection was increased compared to its isogenic Shiga toxin deletion strain. Increased bacterial burdens during Shiga toxin production coincided with decreased induction of colonic IL-23 axis transcripts known to be critical for clearance of similar gastrointestinal pathogens in mice, suggesting a previously undescribed role for STEC Shiga toxins in suppressing host immune responses during STEC infection and survival. The DSS+STEC model establishes infection with clinical-isolate strains of STEC in immunocompetent mice without depleting the gastrointestinal microbiota, enabling characterization of the effects of STXs on the IL-23 axis and other gastrointestinal pathogen-host interactions.

SUBMITTER: Hall G

PROVIDER: S-EPMC6204700 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Dextran Sulfate Sodium Colitis Facilitates Colonization with Shiga Toxin-Producing Escherichia coli: a Novel Murine Model for the Study of Shiga Toxicosis.

Hall Gregory G Kurosawa Shinichiro S Stearns-Kurosawa D J DJ

Infection and immunity 20181025 11

Shiga toxin-producing <i>Escherichia coli</i> (STEC) bacteria are globally important gastrointestinal pathogens causing hemorrhagic gastroenteritis with variable progression to potentially fatal Shiga toxicosis. Little is known about the potential effects of <i>E. coli-</i>derived Shiga-like toxins (STXs) on host gastrointestinal immune responses during infection, in part due to the lack of a reproducible immunocompetent-animal model of STEC infection without depleting the commensal microbiota. ...[more]

PMID: 30150257

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Project description:BackgroundHuman defensin-5 (HD-5) is a key antimicrobial peptide which plays an important role in host immune defense, while the short half-life greatly limits its clinical application. The purpose of this study was to investigate the effects of an engineering probiotic producing HD-5 on intestinal barrier and explore its underlying mechanism METHODS: We constructed the pN8148-SHD-5 vector, and transfected this plasmid into Lactococcus lactis (L. lactis) to create the recombinant NZ9000SHD-5 strain, which continuously produces mature HD-5. NZ9000SHD-5 was administrated appropriately in a dextran sodium sulfate (DSS)-induced colitis model. Alterations in the wounded intestine were analyzed by hematoxylin-eosin staining. The changes of intestinal permeability were detected by FITC-dextran permeability test, the tight junction (TJ) proteins ZO-1 and occludin and cytokines were analyzed by western blotting or enzyme linked immunosorbent assay. In Caco-2 cell monolayers, the permeability were analyzed by transepithelial electrical resistance, and the TJ proteins were detected by western blotting and immunofluorescence. In addition, NF-κB signaling pathway was investigated to further analyze the molecular mechanism of NZ9000SHD-5 treatment on inducing intestinal protection in vitro.ResultsWe found oral administration with NZ9000SHD-5 significantly reduced colonic glandular structure destruction and inflammatory cell infiltration, downregulated expression of several inflammation-related molecules and preserved epithelial barrier integrity. The same protective effects were observed in in vitro experiments, and pretreatment of macrophages with NZ9000SHD-5 culture supernatants prior to LPS application significantly reduced the expression of phosphorylated nuclear transcription factor-kappa B (NF-κB) p65 and its inhibitor IκBα.ConclusionsThese results indicate the NZ9000SHD-5 can alleviate DSS-induced mucosal damage by suppressing NF-κB signaling pathway, and NZ9000SHD-5 may be a novel therapeutic means for ulcerative colitis.

Project description:BackgroundG protein-coupled receptor 35 (GPR35) is an orphan receptor and is vastly expressed in immune cells and gastrointestinal cells, suggesting the potential physiological importance of GPR35 in these cells. Here, we tested the hypothesis that the lack of GPR35 expression in the colon mucosa exacerbates the severity of dextran sulfate sodium (DSS)-induced experimental colitis in mice.MethodsColitis was induced in GPR35 wild-type (GPR35+/+) and GPR35 knockout (GPR35-/-) mice through the administration of DSS in drinking water for 5 days followed by regular facility water for 1 day. Induction of colitis was evaluated by measuring relative body weight loss, clinical illness scores, and morphological changes in the colon. Abolition of Gpr35 gene expression in the colon mucosa of GPR35-/- mice was confirmed by quantitative real-time PCR (qPCR). Gene expressions of inflammatory and tissue remodeling cytokines were detected by qPCR. Human colorectal epithelial Caco cells were transfected with siRNA against GPR35 before treated with 1% DSS in vitro. Protein expressions were measured using Western blot.ResultsGPR35-/- mice receiving DSS showed a significantly worsened colitis disease with profound loss of body weight and a considerable amount of severe clinical illness compared to GPR35+/+ mice that received DSS. The histology of colon sections from GPR35-/- mice showed extensive pathological changes including submucosal edema, diffuse ulcerations, and evidence of complete loss of crypts compared to wild-type mice. The mean histopathological score was significantly higher in GPR35-/- mice as compared to GPR35+/+ mice. The qPCR data revealed significant expression of pro-inflammatory and tissue remodeling cytokines in GPR35-/- colon mucosa, including IL-1β, CXCL1, CXCL2, CCL2, HMGB1, TGFβ1, TGFβ3, MMP1/9/12. The protein expressions of Zonula occludens-1, E-cadherin, Claudin1 were decreased upon knocking down GPR35 with or without 1% DSS treatment.ConclusionsOur experimental data suggest that lack of GPR35 resulted in worsened disease outcome in DSS-induced experimental colitis, indicating that GPR35 could play a crucial role in protecting from colonic inflammation and serve as a therapeutic target.

Dataset Information

Dextran Sulfate Sodium Colitis Facilitates Colonization with Shiga Toxin-Producing Escherichia coli: a Novel Murine Model for the Study of Shiga Toxicosis.

Publications

Dextran Sulfate Sodium Colitis Facilitates Colonization with Shiga Toxin-Producing Escherichia coli: a Novel Murine Model for the Study of Shiga Toxicosis.

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