Pylori-infected Wild-type Mice Research Articles

IL-17 Receptor Signaling through IL-17A or IL-17F Is Sufficient to Maintain Innate Response and Control of Helicobacter pylori Immunopathogenesis.

IL-17R signaling is required for control of extracellular pathogens and is also implicated in development of chronic inflammatory processes. The response to the human pathogen Helicobacter pylori results in Th1 and Th17 cell activation and a chronic inflammatory process that can lead to adverse outcomes, such as gastric cancer. Previously, we identified IL-17RA as a requirement for the recruitment of neutrophils and control of H. pylori colonization in the gastric mucosa. Unexpectedly, H. pylori-infected Il17ra -/- mice had significantly more chronic inflammation than H. pylori-infected wild-type mice. In this study, human epithelial cell lines and murine models were used to investigate differential roles for IL-17A, IL-17F, and IL-17A/F during H. pylori infection. Moreover, the hypothesis that IL-17RA signaling, specifically in lymphocytes, provides an autocrine feedback loop that downregulates Th17 cytokine production was investigated. The data indicate that epithelial cells exhibit a stronger response to IL-17A and IL-17A/F than IL-17F, and that IL-17A and IL-17A/F can synergize with TNF and IL-22 to induce antimicrobial genes of gastric epithelial cells. In vivo deficiencies of IL-17A or IL-17F alone did not significantly change the immunopathological response to H. pylori, but if both cytokines were absent, a hyperinflammatory lymphocytic response developed. Using a cre/flox targeting approach for IL-17RA combined with infection, our findings demonstrate that increased chronic inflammation in Il17ra -/- mice was not attributed to a T cell-intrinsic defect. These data imply that IL-17A and IL-17F may have overlapping roles in maintenance of the gastric mucosal response to infection.

MiR-30a acts as a tumor suppressor by double-targeting COX-2 and BCL9 in H. pylori gastric cancer models

Helicobacter pylori (H. pylori) is one of the most important factors that affect the development of gastric cancer, and its mechanism remains un-elucidated. Our present study found that, miR-30a is crucial for regulating the growth and migration of H. pylori infected gastric cancer in vitro by targeting COX-2 and BCL9. In details, double-stranded miR-30a precursor produced two single-stranded and matured miRNAs including miR-30a-3p and miR-30a-5p, which played significant biological functions in two different manners. First, miR-30a-3p inhibited COX-2 expression and regulated nuclear translocation of β-catenin, and second, miR-30a-5p targeted BCL9 to regulate TCF/LEF promoter activity followed by affecting β-catenin downstream target gene expression. In vivo, miR-30a knockout mice were successfully achieved using CRISPR/Cas9 gene editing technology. Compared with H. pylori-infected wild-type mice, H. pylori-infected miR-30a knockout mice showed increased incidence of chronic gastritis, chronic atrophic gastritis, atypical hyperplasia, and other precancerous lesions or adenocarcinoma manifestations in the antral or gastric mucosa of mice, as well as regulation of genes closely associated with tumor development. Taken together, miR-30a acts as a tumor suppressor by double-targeting COX-2 and BCL9, and significantly affects the development of H. pylori-induced gastric cancer, shedding new light on the mechanisms underlying H. pylori-associated gastric cancer.

Increased expression of deleted in malignant brain tumors (DMBT1) gene in precancerous gastric lesions: Findings from human and animal studies.

Helicobacter pylori infection triggers a cascade of inflammatory stages that may lead to the appearance of non-atrophic gastritis, multifocal atrophic, intestinal metaplasia, dysplasia, and cancer. Deleted in malignant brain tumors 1 (DMBT1) belongs to the group of secreted scavenger receptor cysteine-rich proteins and is considered to be involved in host defense by binding to pathogens. Initial studies showed its deletion and loss of expression in a variety of tumors but the role of this gene in tumor development is not completely understood. Here, we examined the role of DMBT1 in gastric precancerous lesions in Caucasian, African American and Hispanic individuals as well as in the development of gastric pathology in a mouse model of H. pylori infection. We found that in 3 different populations, mucosal DMBT1 expression was significantly increased (2.5 fold) in individuals with dysplasia compared to multifocal atrophic gastritis without intestinal metaplasia; the increase was also observed in individuals with advanced gastritis and positive H. pylori infection. In our animal model, H. pylori infection of Dmbt1−/− mice resulted in significantly higher levels of gastritis, more extensive mucous metaplasia and reduced Il33 expression levels in the gastric mucosa compared to H. pylori-infected wild type mice. Our data in the animal model suggest that in response to H. pylori infection DMBT1 may mediate mucosal protection reducing the risk of developing gastric precancerous lesions. However, the increased expression in human gastric precancerous lesions points to a more complex role of DMBT1 in gastric carcinogenesis.

IL-23 Contributes to Control of Chronic Helicobacter Pylori Infection and the Development of T Helper Responses in a Mouse Model1

The immune response to Helicobacter pylori involves a mixed T helper-1, T helper-2, and T helper-17 response. It has been suggested that T helper cells contribute to the gastric inflammatory response during infection, and that T helper 1 (Th1) and T helper 17 (Th17) subsets may be required for control of H. pylori colonization in the stomach. The relative contributions of these subsets to gastritis and control of infection are still under investigation. IL-23 plays a role in stabilizing and expanding Th17 cell cytokine expression. Expression of IL-23, which is induced in dendritic cells and macrophages following co-culture with H. pylori, has also been reported to increase during H. pylori infection in humans and animal models. To investigate the role of IL-23 in H. pylori, we infected IL-23p19 deficient mice (IL-23−/−) and wild-type littermates with H. pylori strain SS1. At various time points post-infection, we assessed colonization, gastric inflammation, and cytokine profiles in the gastric tissue. Specifically, H. pylori-infected IL-23−/− mice have higher levels of H. pylori in their stomachs, significantly less chronic gastritis, and reduced expression of IL-17 and IFNγ compared to H. pylori-infected wild-type mice. While many of these differences were significant, the H. pylori infected IL-23−/− had mild increases in our measurements of disease severity. Our results indicate that IL-23 plays a role in the activation of the immune response and induction of gastritis in response to H. pylori by contributing to the control of infection and severity of gastritis.

High-Mobility Group Box-1 Protein Delays the Healing of Gastric Ulcer in Mice

Background: Helicobacter pylori-induced immune responses are skewed toward the T helper (Th) 1 phenotype, which is indicated by the predominant production of interferon (IFN)γ and tumor necrosis factor (TNF)-α. Toll-like receptors (TLRs) play an essential role in the defense against microbes through the recognition of bacterial molecules. Among TLRs, TLR9 identifies unmethylated CpG DNA sites, which are abundant in bacterial and viral DNA. Although TLR9 signaling exerts pro-inflammatory actions through Th1 responses, the activation of an anti-inflammatory program has been reported in several models of experimental colitis. Aim: To investigate the expression and role of TLR9 in H. pylori-induced gastritis in mice. Methods: Wild-type and TLR9-/mice were inoculated with H. pylori (SS 1 strain). After 2, 4, and 6 months of inoculation of H. pylori, gastric tissues were subjected to activity measurement of myeloperoxidase, a marker of neutrophil infiltration; detection of cytokine mRNA levels by real-time reverse transcriptase-polymerase chain reaction (RTPCR); and immunohistochemical analysis. Results: TLR9 mRNA expression was increased by 6.0-fold, 10.1-fold, and 23.4-fold, respectively, after 2, 4, and 6 months of H. pylori infection. After 2 months, mRNA levels for IFN-γ and TNF-α (Th1-type cytokines) in TLR9-/mice were significantly elevated by 6.7-fold and 5.3-fold, respectively, with a 2.7-fold increase in myeloperoxidase activity, compared to those in H. pylori-infected wild-type mice. The expression of Th1-type cytokines and myeloperoxidase activity in TLR9-/mice were also increased 4 months after H. pylori infection, but these inflammatory parameters were similar 6 months after H. pylori infection in the wild-type and TLR9-/mice. IL-4 and IL-5 (Th2type cytokines) mRNA expression levels did not differ between wild-type and TLR9-/mice throughout the experiment. Immunohistochemical analysis showed that TLR9 proteins were mainly expressed on inflammatory cells. Conclusion: These findings suggest that TLR9 signaling may play important roles in the inhibition of H. pylori-induced gastritis in the early phase through the suppression of Th1 differentiation.

Reduced Hedgehog Signal Transduction Exacerbates the TH1 Response in Helicobacter felis-Infected Mice

Background: Helicobacter pylori-induced immune responses are skewed toward the T helper (Th) 1 phenotype, which is indicated by the predominant production of interferon (IFN)γ and tumor necrosis factor (TNF)-α. Toll-like receptors (TLRs) play an essential role in the defense against microbes through the recognition of bacterial molecules. Among TLRs, TLR9 identifies unmethylated CpG DNA sites, which are abundant in bacterial and viral DNA. Although TLR9 signaling exerts pro-inflammatory actions through Th1 responses, the activation of an anti-inflammatory program has been reported in several models of experimental colitis. Aim: To investigate the expression and role of TLR9 in H. pylori-induced gastritis in mice. Methods: Wild-type and TLR9-/mice were inoculated with H. pylori (SS 1 strain). After 2, 4, and 6 months of inoculation of H. pylori, gastric tissues were subjected to activity measurement of myeloperoxidase, a marker of neutrophil infiltration; detection of cytokine mRNA levels by real-time reverse transcriptase-polymerase chain reaction (RTPCR); and immunohistochemical analysis. Results: TLR9 mRNA expression was increased by 6.0-fold, 10.1-fold, and 23.4-fold, respectively, after 2, 4, and 6 months of H. pylori infection. After 2 months, mRNA levels for IFN-γ and TNF-α (Th1-type cytokines) in TLR9-/mice were significantly elevated by 6.7-fold and 5.3-fold, respectively, with a 2.7-fold increase in myeloperoxidase activity, compared to those in H. pylori-infected wild-type mice. The expression of Th1-type cytokines and myeloperoxidase activity in TLR9-/mice were also increased 4 months after H. pylori infection, but these inflammatory parameters were similar 6 months after H. pylori infection in the wild-type and TLR9-/mice. IL-4 and IL-5 (Th2type cytokines) mRNA expression levels did not differ between wild-type and TLR9-/mice throughout the experiment. Immunohistochemical analysis showed that TLR9 proteins were mainly expressed on inflammatory cells. Conclusion: These findings suggest that TLR9 signaling may play important roles in the inhibition of H. pylori-induced gastritis in the early phase through the suppression of Th1 differentiation.

IL-21 contributes to the control of infection and to the severity of gastritis during Helicobacter infection (56.3)

Abstract The immune response to Helicobacter pylori involves a mixed T helper-1, T helper-2, and T helper-17 response. It has been suggested that T helper cells contribute to the gastric inflammatory response during infection, and that Th1 and Th17 subsets may be required for control of H. pylori colonization in the stomach. The relative contributions of these subsets to gastritis and control of infection are still under investigation. Expression of IL-21, which may be produced by a number of T cell subsets, has been reported to increase during H. pylori infection. IL-21 plays a role in both B cell stimulation and T cell differentiation. To investigate the role of IL-21 in H. pylori, we infected IL-21 deficient mice and wild-type littermates with H. pylori strain SS1. At 3 months post-infection, we assessed colonization, gastric inflammation, cellular infiltrate in the stomach, and cytokine profiles in the gastric tissue. Specifically, H. pylori-infected IL-21-/- mice have higher levels of H. pylori in their stomachs (4.5±0.4x107 CFU v. 4.3±2.3x106 CFU, **p=0.004), significantly less gastritis (gastritis scores 3.8±0.2 v. 1.2±0.3, ***p=0.0002), and reduced expression IL-17 and IFNγ (*p<0.05) compared to H. pylori-infected wild-type mice. Our results indicate that IL-21 contributes to the control of infection and severity of gastritis, suggesting IL-21 is required for activation of the immune response and induction of gastritis in response to H. pylori.

Lack of gastritis and of an adaptive immune response in interferon regulatory factor-1-deficient mice infected with Helicobacter pylori.

To study the role of T cell responses in Helicobacter pylori gastritis, C57BL/6 wild-type and interferon regulatory factor-1-deficient (IRF-1(-/-)) mice were infected with the mouse-adapted H. pylori Sydney strain. Mice lacking the transcription factor IRF-1 are defective in Th1 development and are therefore biased to mount a Th2-type response. After 4 months of infection, C57BL/6 mice developed severe gastritis and atrophy and mounted a Th1-type response towards H. pylori. The Th1 response was abrogated in IRF-1(-/-) mice. This defective Th1 response was associated with the total lack of gastritis and atrophy in IRF-1(-/-) mice despite severe colonization with H. pylori. In addition, IRF-1(-/-) mice did also not develop a Th2 reaction, since they failed to generate H. pylori-specific antibodies and to produce IL-4 in response to H. pylori antigens in vitro. Thus, the transcription factor IRF-1 is necessary for the development of gastritis and atrophy in H. pylori-infected wild-type mice, suggesting a role of Th1 cells in the pathogenesis of H. pylori-associated diseases.