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Ornithine Decarboxylase in Gastric Epithelial Cells Promotes the Immunopathogenesis of Helicobacter pylori Infection

ABSTRACT: Colonization by H. pylori is associated with a wide range of gastric diseases, ranging from superficial gastritis to more severe pathologies, including intestinal metaplasia and adenocarcinoma. The interplay of the host response and the pathogen affect the outcome of disease. One major component of the mucosal response to H. pylori is the activation of a strong, but inefficient immune response that fails to control the infection and frequently causes tissue damage. We have shown that polyamines can regulate H. pylori-induced inflammation. Chemical inhibition of ornithine decarboxylase (ODC), which generates putrescine from L-ornithine, reduces gastritis in mice and adenocarcinoma incidence in gerbils infected with H. pylori. However, we have also demonstrated that Odc deletion in myeloid cells enhances M1 macrophage activation and gastritis. Here we used a genetic approach to assess the specific role of gastric epithelial ODC during H. pylori infection. Deletion of Odc in gastric epithelial cells reduces gastritis, attenuates epithelial proliferaton, alters the metabolome, and dowregulates the expression of immune mediators induced by H. pylori. Inhibition of ODC activity in gastric epithelial cells reduces H. pylori-induced NF-B activation and CXCL8 mRNA expression. Chronic inflammation is a major risk factor for the progression to more severe pathologies associated with H. pylori infection and we now show that epithelial ODC plays an important role in mediating this inflammatory response.

INSTRUMENT(S): Liquid Chromatography MS - positive - hilic

SUBMITTER: M. Wade Calcutt

PROVIDER: MTBLS3235 | MetaboLights | 2022-06-15

REPOSITORIES: MetaboLights

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Project description:Chronic infection with the bacterial pathogen Helicobacter pylori is a risk factor for the development of gastric cancer, yet remains asymptomatic in a majority of individuals. We report here that the C57Bl6 mouse model of experimental infection with the closely related H. felis recapitulates this wide range in host susceptibility. A majority of infected mice develop premalignant lesions such as gastric atrophy, compensatory epithelial hyperplasia and intestinal metaplasia, whereas a minority is completely protected from preneoplasia. Protection is associated with the failure to mount an IFN-gamma response to the infection and an associated high Helicobacter burden. We demonstrate that IFN-gamma is essential for clearance of Helicobacter, but also mediates the formation of preneoplastic lesions. We further provide evidence that IFN-gamma triggers a specific transcriptional program in murine gastric epithelial cells in vitro and in vivo, and induces their preferential transformation to the hyperplastic phenotype. In summary, our data suggest a dual role for IFN-gamma in Helicobacter pathogenesis that could provide an explanation for the differential susceptibility to H. pylori-induced gastric pathology in the human population. Keywords: response to in vitro stimulus / comparison of histopathological states We chose mice for gene expression profiling that following Helicobacter infection had (a) symptoms of gastritis, but no epithelial changes, (b) atrophic gastritis accompanied by corpus gland hyperplasia or (c) atrophic gastritis accompanied by intestinal metaplasia. An uninfected control group was also included in the analysis, as were two groups of mice that lacked mature T- and B-cells due to a deletion mutation in the rag1 gene (Rag-1-/-) and that were either experimentally infected or served as Rag-1-/- uninfected controls. To see the effects of IFNg on murine gastric epithelial cells we analysed an immortalized murine primary gastric epithelial cell line treated with three different concentrations of IFNg in comparison to an untreated control.

Project description:We previously established long-term 3D organoid culture systems for several murine tissues (intestine, stomach, pancreas and liver) as well as human intestine and pancreas. Here, we describe culture conditions to generate long-term 3D culture from human gastric stem cells. The technology can be applied to study the epithelial response to infection with Helicobacter pylori. Human gastric cultures can expand indefinitely in 3D Matrigel. Cultures can be generated from normal tissue, from single sorted stem cells, or from tumor tissue. Organoids maintain many characteristics of the respective tissue in terms of histology, marker expression and euploidy. Organoids from normal tissue express markers of four lineages of the stomach and self-organize in gland and pit-domains. They can be directed to specifically express either lineages of the gastric gland, or the gastric pit by addition of Nicotinamide and withdrawal of Wnt. While gastric pit lineages react marginally to bacterial infection, gastric gland lineages mount a strong inflammatory response. The gastric culture system provides a unique tool to study gastric pathologies. We generated 2 sets of experiments. The first set contains organoids in 4 conditions: (1) organoids in expansion condition ENRWFGNiTi ("gland-type organoids") from 3 donors, (2) organoids as in 1 but differentiated for 4 days in differentiation condition ENR_FGNiTi ("pit'type organoids"), (3) organoids as in 1 but infected with Helicobacter pylori strain P12 MOI 50 for 2 h, (4) organoids as in 2 but infected as in 3. All 4 conditions were tested on the same organoid line in parallel. This experiment was conducted independently with cultures from 3 different donors. The second set of experiments compares freshly isolated glands with organoids. Samples from 2 patients were analyzed. Each patient received a total gastrectomy. From each patient, glands from corpus region or pyloric antrum were isolated. From each isolation, one aliquod was stored for microarray analysis and one aliquod used to generate organoids. Organoids and glands were subsequently lysed and analyzed in parallel.

Project description:The model is first model of tissue level cellular immune responses to H. pylori in the publication, "Modeling the role of lanthionine synthetase C-like 2 (LANCL2) in the modulation of immune responses to Helicobacter pylori infection" in PlosOne by Leber, Bassaganya-Riera, Tubau-Juni, Zoccoli-Rodriguez, Viladomiu, Abedi, Lu, and Hontecillas. Abstract: Immune responses to Helicobacter pylori are orchestrated through complex balances of host-bacterial interactions, including inflammatory and regulatory immune responses across scales that can lead to the development of the gastric disease or the promotion of beneficial systemic effects. While inflammation in response to the bacterium has been reasonably characterized, the regulatory pathways that contribute to preventing inflammatory events during H. pylori infection are incompletely understood. To aid in this effort, we have generated a computational model incorporating recent developments in the understanding of H. pylori-host interactions. Sensitivity analysis of this model reveals that a regulatory macrophage population is critical in maintaining high H. pylori colonization without the generation of an inflammatory response. To address how this myeloid cell subset arises, we developed a second model describing an intracellular signaling network for the differentiation of macrophages. Modeling studies predicted that LANCL2 is a central regulator of inflammatory and effector pathways and its activation promotes regulatory responses characterized by IL-10 production while suppressing effector responses. The predicted impairment of regulatory macrophage differentiation by the loss of LANCL2 was simulated based on multiscale linkages between the tissue-level gastric mucosa and the intracellular models. The simulated deletion of LANCL2 resulted in a greater clearance of H. pylori, but also greater IFNγ responses and damage to the epithelium. The model predictions were validated within a mouse model of H. pylori colonization in wild-type (WT), LANCL2 whole body KO and myeloid-specific LANCL2-/- (LANCL2Myeloid) mice, which displayed similar decreases in H. pylori burden, CX3CR1+ IL-10-producing macrophages, and type 1 regulatory (Tr1) T cells. This study shows the importance of LANCL2 in the induction of regulatory responses in macrophages and T cells during H. pylori infection.

Project description:The model is the second model of the publication "Modeling the role of lanthionine synthetase C-like 2 (LANCL2) in the modulation of immune responses to Helicobacter pylori infection" published in PlosOne by Leber, Bassaganya-Riera, Tubau-Juni, Zoccoli-Rodriguez, Viladomiu, Abedi, Lu, and Hontecillas. Abstract: Immune responses to Helicobacter pylori are orchestrated through complex balances of host-bacterial interactions, including inflammatory and regulatory immune responses across scales that can lead to the development of the gastric disease or the promotion of beneficial systemic effects. While inflammation in response to the bacterium has been reasonably characterized, the regulatory pathways that contribute to preventing inflammatory events during H. pylori infection are incompletely understood. To aid in this effort, we have generated a computational model incorporating recent developments in the understanding of H. pylori-host interactions. Sensitivity analysis of this model reveals that a regulatory macrophage population is critical in maintaining high H. pylori colonization without the generation of an inflammatory response. To address how this myeloid cell subset arises, we developed a second model describing an intracellular signaling network for the differentiation of macrophages. Modeling studies predicted that LANCL2 is a central regulator of inflammatory and effector pathways and its activation promotes regulatory responses characterized by IL-10 production while suppressing effector responses. The predicted impairment of regulatory macrophage differentiation by the loss of LANCL2 was simulated based on multiscale linkages between the tissue-level gastric mucosa and the intracellular models. The simulated deletion of LANCL2 resulted in a greater clearance of H. pylori, but also greater IFNγ responses and damage to the epithelium. The model predictions were validated within a mouse model of H. pylori colonization in wild-type (WT), LANCL2 whole body KO and myeloid-specific LANCL2-/- (LANCL2Myeloid) mice, which displayed similar decreases in H. pylori burden, CX3CR1+ IL-10-producing macrophages, and type 1 regulatory (Tr1) T cells. This study shows the importance of LANCL2 in the induction of regulatory responses in macrophages and T cells during H. pylori infection.

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Ornithine Decarboxylase in Gastric Epithelial Cells Promotes the Immunopathogenesis of Helicobacter pylori Infection

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