Helicobacter pylori Deregulates T and B Cell Signaling to Trigger Immune Evasion

Clinical analysis of the effect of helicobacter pylori infection on immune function in children with peptic ulcer

Objective

To study whether children with peptic ulcer would have abnormalities in cellular and humoral immune functions, and whether Helicobacter pylori (Hp) infection would affect the immune function of children with peptic ulcer.

Methods

This is a retrospective study. The subjects of study were 72 children with diagnosed and cured peptic ulcer (ulcer group), and 50 healthy children with physical examination (control group) at Baoding Hospital, Beijing Children's Hospital Affiliated to Capital Medical University from June 2020 to December 2022. Further detection was conducted on T lymphocyte subsets (CD3+, CD4+, CD8+, and CD4+/CD8+ ratio) and immunoglobulin levels.

Results

Of the 72 children with peptic ulcer, 53(73.6%) were positive for Hp (Hp-positive group) and 19 (26.4%) were negative (Hp-negative group). The levels of CD3+, CD4+, and CD4+/CD8+ ratio in the control group were significantly higher than those in the ulcer group, with statistically significant difference (P<0.05); while the level of IgG in the control group was lower than that in the ulcer group, with statistically significant difference (P<0.05). Meanwhile, there were statistically significant differences in that the levels of CD3+, CD4+ and CD8+ were increased in Hp-positive group than those in Hp-negative group before treatment (P<0.05); while CD4+/CD8+ ratio was lower in the former group than that in the latter group, with statistically significant difference (P<0.05).

Conclusion

Hp infection can induce the elevation of T lymphocyte subsets. The development of peptic ulcer has an intimate association with the disorder of cellular and humoral immune functions.

CD4+ T cell count and HIV-1 viral load dynamics positively impacted by H. pylori infection in HIV-positive patients regardless of ART status in a high-burden setting

BACKGROUND

There is a widespread co-infection of HIV and Helicobacter pylori (H. pylori) globally, particularly in developing countries, and it has been suggested that this co-infection may affect the course of HIV disease. However, the interplay between H. pylori infection and HIV disease progression is not fully elucidated. In this study, we investigated the effect of H. pylori co-infection on CD4+ T cell count and HIV viral load dynamics in HIV-positive individuals in a high co-endemic setting.

METHODS

A comparative cross-sectional study was conducted among 288 HIV-positive and 175 HIV-negative individuals, both with and without H. pylori infection. Among HIV-positive participants, 195 were on antiretroviral therapy (ART) and 93 were ART-naïve. CD4+ T cell count and HIV-1 viral load were measured and compared between H. pylori-infected and -uninfected individuals, taking into account different HIV and ART status.

RESULT

Our study demonstrated that individuals infected with H. pylori had a significantly higher CD4+ T cell count compared to uninfected controls among both HIV-negative and HIV-positive participants, regardless of ART therapy. Conversely, HIV/H. pylori co-infected participants had lower HIV-1 viral load than those without H. pylori infection. Linear regression analysis further confirmed a positive association between H. pylori infection, along with other clinical factors such as BMI, ART, and duration of therapy, with CD4+ T cell count while indicating an inverse relationship with HIV-1 viral load in HIV-positive patients. Additionally, factors such as khat chewing, age and WHO clinical stage of HIV were associated with reduced CD4+ T cell count and increased HIV-1 viral load.

CONCLUSION

Our study demonstrates that H. pylori co-infection was associated with higher CD4+ T cell count and lower HIV-1 viral load in HIV-positive patients, regardless of ART status. These findings show a positive effect of H. pylori co-infection on the dynamics of HIV-related immunological and virological parameters. Further studies are needed to elucidate the underlying mechanisms of the observed effects.

Role of Helicobacter pylori virulence factors and alteration of the Tumor Immune Microenvironment: challenges and opportunities for Cancer Immunotherapy

Various forms of malignancies have been linked to Helicobacter pylori. Despite advancements in chemotherapeutic and surgical approaches, the management of cancer, particularly at advanced stages, increasingly relies on the integration of immunotherapy. As a novel, safe therapeutic modality, immunotherapy harnesses the immune system of the patient to treat cancer, thereby broadening treatment options. However, there is evidence that H. pylori infection may influence the effectiveness of immunotherapy in various types of cancer. This association is related to H. pylori virulence factors and the tumor microenvironment. This review discusses the influence of H. pylori infection on immunotherapy in non-gastrointestinal and gastrointestinal tumors, the mechanisms underlying this relationship, and directions for the development of improved immunotherapy strategies.

Immune evasion by proteolytic shedding of natural killer group 2, member D ligands in Helicobacter pylori infection

Background

Helicobacter pylori (H. pylori) uses various strategies that attenuate mucosal immunity to ensure its persistence in the stomach. We recently found evidence that H. pylori might modulate the natural killer group 2, member 2 (NKG2D) system. The NKG2D receptor and its ligands are a major activation system of natural killer and cytotoxic T cells, which are important for mucosal immunity and tumor immunosurveillance. The NKG2D system allows recognition and elimination of infected and transformed cells, however viruses and cancers often subvert its activation. Here we aimed to identify a potential evasion of the NKG2D system in H. pylori infection.

Methods

We analyzed expression of NKG2D system genes in gastric tissues of H. pylori gastritis and gastric cancer patients, and performed cell-culture based infection experiments using H. pylori isogenic mutants and epithelial and NK cell lines.

Results

In biopsies of H. pylori gastritis patients, NKG2D receptor expression was reduced while NKG2D ligands accumulated in the lamina propria, suggesting NKG2D evasion. In vitro, H. pylori induced the transcription and proteolytic shedding of NKG2D ligands in stomach epithelial cells, and these effects were associated with specific H. pylori virulence factors. The H. pylori-driven release of soluble NKG2D ligands reduced the immunogenic visibility of infected cells and attenuated the cytotoxic activity of effector immune cells, specifically the anti-tumor activity of NK cells.

Conclusion

H. pylori manipulates the NKG2D system. This so far unrecognized strategy of immune evasion by H. pylori could potentially facilitate chronic bacterial persistence and might also promote stomach cancer development by allowing transformed cells to escape immune recognition and grow unimpeded to overt malignancy.

Helicobacter pylori infection increases the risk of carotid plaque formation: Clinical samples combined with bioinformatics analysis

Objective

Infection with Helicobacter pylori (H. pylori) may increase atherosclerosis, which can lead to carotid plaque formation. Our study examined the relationship between H. pylori infection and carotid plaque formation, and its underlying mechanisms.

Methods

A total of 36,470 people who underwent physical examination in Taizhou Hospital Health Examination Center from June 2017 to June 2022 were included in this study. All people participated in the urease test, neck ultrasound, blood pressure detection, anthropometric measurement and biochemical laboratory examination. In addition, the GSE27411 and GSE28829 datasets in the Gene Expression Omnibus (GEO) database were used to analyze the mechanism of H. pylori infection and atherosclerosis progression.

Results

H. pylori infection, sex, age, blood lipids, blood pressure, fasting blood glucose, glycated hemoglobin and body mass index were risk factors for carotid plaque formation. An independent risk factor was still evident in the multivariate logistic regression analysis, indicating H. pylori infection. Furthermore, after weighted gene coexpression network analysis (WGCNA), we discovered 555 genes linked to both H. pylori infection and the advancement of atherosclerosis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed a strong correlation between these genes and immunity, infection, and immune disorders. SsGSEA analysis showed that H. pylori infection and atherosclerosis included changes in the immune microenvironment. Finally, three genes MS4A6A, ADAMDEC1 and AQP9 were identified to be involved in the formation of atherosclerosis after H. pylori infection. Conclusion: Our research affirms that H. pylori is a unique contributor to the formation of carotid plaque, examines the immune microenvironment associated with H. pylori infection and advanced carotid atherosclerosis, and offers fresh perspectives on how H. pylori infection leads to atherosclerosis.

Impact of Helicobacter pylori infection on the efficacy of immune checkpoint inhibitors for cancer treatment: a meta-analysis

Aim: The present systematic review and meta-analysis was designed to assess the impact of Helicobacter pylori infection on the efficacy of immune checkpoint inhibitors (ICIs). Materials & methods: PubMed, Scopus, Web of Science and EMBASE databases were systematically searched up to 1 February 2023. Results: Three studies comprising 263 patients treated with ICIs were included. The results of pooled analysis showed that H. pylori infection was associated with reduced overall survival and progression-free survival. Furthermore, the rate of progressive disease after administration of ICIs was higher in H. pylori-positive patients relative to H. pylori-negative patients. Conclusion: H. pylori infection status is a novel potential response biomarker for predicting the efficacy of ICIs in different cancers.

Helicobacter pylori Immune Response in Children Versus Adults

H. pylori is perhaps the most prevalent human pathogen worldwide and infects almost half of the world's population. Despite the decreasing prevalence of infection overall, it is significant in developing countries. Most infections are acquired in childhood and persist for a lifetime unless treated. Children are often asymptomatic and often develop a tolerogenic immune response that includes T regulatory cells and their products, immunosuppressive cytokines, such as interleukin (IL)-10, and transforming growth factor-β (TGF-β). This contrasts to the gastric immune response seen in H. pylori-infected adults, where the response is mainly inflammatory, with predominant Th1 and Th17 cells, as well as, inflammatory cytokines, such as TNF-α, IFN-γ, IL-1, IL-6, IL-8, and IL-17. Therefore, compared to adults, infected children generally have limited gastric inflammation and peptic ulcer disease. H. pylori surreptitiously subverts immune defenses to persist in the human gastric mucosa for decades. The chronic infection might result in clinically significant diseases in adults, such as peptic ulcer disease, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. This review compares the infection in children and adults and highlights the H. pylori virulence mechanisms responsible for the pathogenesis and immune evasion.

DNA Damage Repair and Current Therapeutic Approaches in Gastric Cancer: A Comprehensive Review

DNA in cells is frequently damaged by endogenous and exogenous agents. However, comprehensive mechanisms to combat and repair DNA damage have evolved to ensure genomic stability and integrity. Improper DNA damage repair may result in various diseases, including some types of tumors and autoimmune diseases. Therefore, DNA damage repair mechanisms have been proposed as novel antitumor drug targets. To date, numerous drugs targeting DNA damage mechanisms have been developed. For example, PARP inhibitors that elicit synthetic lethality are widely used in individualized cancer therapies. In this review, we describe the latent DNA damage repair mechanisms in gastric cancer, the types of DNA damage that can contribute to the development of gastric cancer, and new therapeutic approaches for gastric cancer that target DNA damage repair pathways.

Innate Immunity Crosstalk with Helicobacter pylori: Pattern Recognition Receptors and Cellular Responses

Helicobacter pylori is one of the most successful gastric pathogens that has co-existed with human for centuries. H. pylori is recognized by the host immune system through human pattern recognition receptors (PRRs), such as toll-like receptors (TLRs), C-type lectin like receptors (CLRs), NOD-like receptors (NLRs), and RIG-I-like receptors (RLRs), which activate downstream signaling pathways. Following bacterial recognition, the first responders of the innate immune system, including neutrophils, macrophages, and dendritic cells, eradicate the bacteria through phagocytic and inflammatory reaction. This review provides current understanding of the interaction between the innate arm of host immunity and H. pylori, by summarizing H. pylori recognition by PRRs, and the subsequent signaling pathway activation in host innate immune cells.

The immune microenvironment in gastric adenocarcinoma

Like most solid tumours, the microenvironment of epithelial-derived gastric adenocarcinoma (GAC) consists of a variety of stromal cell types, including fibroblasts, and neuronal, endothelial and immune cells. In this article, we review the role of the immune microenvironment in the progression of chronic inflammation to GAC, primarily the immune microenvironment driven by the gram-negative bacterial species Helicobacter pylori. The infection-driven nature of most GACs has renewed awareness of the immune microenvironment and its effect on tumour development and progression. About 75-90% of GACs are associated with prior H. pylori infection and 5-10% with Epstein-Barr virus infection. Although 50% of the world's population is infected with H. pylori, only 1-3% will progress to GAC, with progression the result of a combination of the H. pylori strain, host susceptibility and composition of the chronic inflammatory response. Other environmental risk factors include exposure to a high-salt diet and nitrates. Genetically, chromosome instability occurs in ~50% of GACs and 21% of GACs are microsatellite instability-high tumours. Here, we review the timeline and pathogenesis of the events triggered by H. pylori that can create an immunosuppressive microenvironment by modulating the host's innate and adaptive immune responses, and subsequently favour GAC development.

Emerging Role of Helicobacter pylori in the Immune Evasion Mechanism of Gastric Cancer: An Insight Into Tumor Microenvironment-Pathogen Interaction

Helicobacter pylori (H. pylori) infection is the strongest causative factor of gastric cancer. Growing evidence suggests that the complex crosstalk of H. pylori and the tumor microenvironment (TME) exerts a profound influence on gastric cancer progression. Hence, there is emerging interest to in-depth comprehension of the mechanisms of interplay between H. pylori and the TME. This review discusses the regulatory mechanisms underlying the crosstalk between H. pylori infection and immune and stromal cells, including tumor-associated macrophages (TAMs), neutrophils, dendritic cells, myeloid-derived suppressor cells (MDSCs), natural killer (NK) cells, B and T cells, cancer associated fibroblasts (CAFs), and mesenchymal stem cells (MSCs), within the TME. Such knowledge will deepen the understanding about the roles of H. pylori in the immune evasion mechanism in gastric cancer and contribute to the development of more effective treatment regimens against H. pylori-induced gastric cancer.

The Promising Mechanisms of Low Molecular Weight Compounds of Panax Ginseng C.A. Meyer in Alleviating COVID-19: A Network Pharmacology Analysis

Panax Ginseng C.A. Meyer (PGCAM) is a well-known phytomedicine, but most of its compounds, such as ginsenoside derivatives, have poor absorption and bioavailability profile due to high molecular weight (≥500 Daltons), which is the major hurdle for their clinical application. Hence, this research explored the efficiency of low molecular weight compounds (LMWCs) (<500 Daltons) screened from PGCAM and their anti-COVID-19 mechanisms through network pharmacology. Molecular compounds from PGCAM were identified using public databases and filtered out by the drug-likeness evaluation. Genes interacted with these filtered compounds, and COVID-19-related genes were extracted from public databases. In addition, overlapping genes between compounds and interactive genes were identified using the Venn diagram. In parallel, the networking between compounds and overlapping genes was analyzed by RStudio. The pathway enrichment analysis of overlapping genes was determined by STRING. Finally, the key bioactive compounds were documented through virtual screening. The bubble chart suggested that the mechanisms of PGCAM against COVID-19 were related to 28 signaling pathways. The key molecular anti-COVID-19 mechanisms might be the anti-inflammation, anti-permeability, and pro-apoptosis by inactivating the PI3K-Akt signaling pathway. The six key genes and the five compounds related to the PI3K-Akt signaling pathway were RELA-paeonol, NFKB1-frutinone A, IL6-nepetin, MCL1-ramalic acid, VEGFA-trifolirhizin, and IL2-trifolirhizin. The docking between these key genes and compounds demonstrated promising binding affinity with a good binding score. Overall, our proposed LMWCs from PGCAM provide a fundamental basis with noteworthy pharmacological evidence to support the therapeutic efficacy of PGCAM in relieving the main symptoms of COVID-19.

Association between Helicobacter pylori infection and food-specific immunoglobulin G in Southwest China

BACKGROUND

Helicobacter pylori (H. pylori) has been found to be associated with extragastrointestinal diseases, possibly including adverse food reactions (such as food allergy or intolerance). However, there are few studies on H. pylori and food allergy or intolerance, and the results are inconsistent. Food-specific immunoglobulin (Ig) G has been revealed to be associated with food allergy or intolerance and can be used as a marker to explore the correlation between H. pylori infection and food allergy or intolerance.

AIM

To explore the relationship between H. pylori infection and food-specific IgG

METHODS

We retrospectively analyzed the physical examination data of 21822 subjects from February 2014 to December 2018 in this study. H. pylori infection was detected using the ¹³C urea breath test. Food-specific IgG of eggs, milk and wheat in serum was assessed. Subjects were grouped according to H. pylori positivity, and the positive rates of three kinds of food-specific IgG were compared between the two groups. Multivariable logistic regression analysis was performed to elucidate the association between H. pylori infection and food-specific IgG.

RESULTS

The total infection rate of H. pylori was 39.3%, and the total food-specific IgG-positive rates of eggs, milk and wheat were 25.2%, 9.0% and 4.9%, respectively. The infection rate of H. pylori was higher in males than in females, while the positive rates of food-specific IgG were lower in males than in females. The positive rates of food-specific IgG decreased with age in both males and females. In the H. pylori-positive groups, the positive rates of food-specific IgG of eggs, milk and wheat were all lower than those in the H. pylori-negative groups. Multivariate logistic regression analysis revealed that H. pylori infection was negatively correlated with the food-specific IgG-positive rates of eggs, milk and wheat (odds ratio value of eggs 0.844-0.873, milk 0.741-0.751 and wheat 0.755-0.788, in different models).

CONCLUSION

H. pylori infection was found to be negatively associated with the food-specific IgG of eggs, milk and wheat in Southwest China.

Interference of LPS H. pylori with IL-33-Driven Regeneration of Caviae porcellus Primary Gastric Epithelial Cells and Fibroblasts

Background: Lipopolysaccharide (LPS) of Helicobacter pylori (Hp) bacteria causes disintegration of gastric tissue cells in vitro. It has been suggested that interleukin (IL)-33 is involved in healing gastric injury. Aim: To elucidate whether Hp LPS affects regeneration of gastric barrier initiated by IL-33. Methods: Primary gastric epithelial cells or fibroblasts from Caviae porcellus were transfected with siRNA IL-33. Such cells, not exposed or treated with LPS Hp, were sub-cultured in the medium with or without exogenous IL-33. Then cell migration was assessed in conjunction with oxidative stress and apoptosis, activation of extracellular signal-regulated kinase (Erk), production of collagen I and soluble ST2 (IL-33 decoy). Results: Control cells not treated with LPS Hp migrated in the presence of IL-33. The pro-regenerative activity of IL-33 was related to stimulation of cells to collagen I production. Wound healing by cells exposed to LPS Hp was inhibited even in the presence of IL-33. This could be due to increased oxidative stress and apoptosis in conjunction with Erk activation, sST2 elevation and modulation of collagen I production. Conclusions: The recovery of gastric barrier cells during Hp infection potentially can be affected due to downregulation of pro-regenerative activity of IL-33 by LPS Hp.

Network pharmacology approach to decipher signaling pathways associated with target proteins of NSAIDs against COVID-19

Non-steroidal anti-inflammatory drugs (NSAIDs) showed promising clinical efficacy toward COVID-19 (Coronavirus disease 2019) patients as potent painkillers and anti-inflammatory agents. However, the prospective anti-COVID-19 mechanisms of NSAIDs are not evidently exposed. Therefore, we intended to decipher the most influential NSAIDs candidate(s) and its novel mechanism(s) against COVID-19 by network pharmacology. FDA (U.S. Food & Drug Administration) approved NSAIDs (19 active drugs and one prodrug) were used for this study. Target proteins related to selected NSAIDs and COVID-19 related target proteins were identified by the Similarity Ensemble Approach, Swiss Target Prediction, and PubChem databases, respectively. Venn diagram identified overlapping target proteins between NSAIDs and COVID-19 related target proteins. The interactive networking between NSAIDs and overlapping target proteins was analyzed by STRING. RStudio plotted the bubble chart of the KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment analysis of overlapping target proteins. Finally, the binding affinity of NSAIDs against target proteins was determined through molecular docking test (MDT). Geneset enrichment analysis exhibited 26 signaling pathways against COVID-19. Inhibition of proinflammatory stimuli of tissues and/or cells by inactivating the RAS signaling pathway was identified as the key anti-COVID-19 mechanism of NSAIDs. Besides, MAPK8, MAPK10, and BAD target proteins were explored as the associated target proteins of the RAS. Among twenty NSAIDs, 6MNA, Rofecoxib, and Indomethacin revealed promising binding affinity with the highest docking score against three identified target proteins, respectively. Overall, our proposed three NSAIDs (6MNA, Rofecoxib, and Indomethacin) might block the RAS by inactivating its associated target proteins, thus may alleviate excessive inflammation induced by SARS-CoV-2.

Stomach microbiota, Helicobacter pylori, and group 2 innate lymphoid cells

The stomach has been thought to host few commensal bacteria because of the existence of barriers, such as gastric acid. However, recent culture-independent, sequencing-based microbial analysis has shown that the stomach also harbors a wide diversity of microbiota. Although the stomach immune system, especially innate lymphoid cells (ILCs), has not been well elucidated, recent studies have shown that group 2 ILCs (ILC2s) are the dominant subtype in the stomach of both humans and mice. Stomach ILC2s are unique in that their existence is dependent on stomach microbiota, in sharp contrast to the lack of an impact of commensal microbiota on ILC2s in other tissues. The microbiota dependency of stomach ILC2s is partly explained by their responsiveness to interleukin (IL)-7. Stomach ILC2s express significantly higher IL-7 receptor protein levels on their surface and proliferate more in response to IL-7 stimulation in vitro than small intestinal ILC2s. Consistently, the stomach expresses much higher IL-7 protein levels than the small intestine. IL-5 secreted from stomach ILC2s promotes immunoglobulin (Ig) A production by plasma B cells. In a murine model, stomach ILC2s are important in containing Helicobacter pylori infection, especially in the early phase of infection, by promoting IgA production.

Helicobacter pylori elicits B7H3 expression on gastric epithelial cells: Implications in local T cell regulation and subset development during infection

Helicobacter pylori (H. pylori) is a gram negative bacterium that infects more than 50% of humanity and is associated with gastritis, peptic ulcer and gastric cancer. Although CD4⁺ T cells are recruited to the gastric mucosa, the host is unable to clear the bacteria. Previously, we demonstrated that H. pylori infection upregulates the expression of the T cell co-inhibitory molecule B7-H1 while simultaneously downregulating the expression of T cell co-stimulatory molecule B7-H2 on gastric epithelial cells (GEC), which together affect the Treg and Th17 cell balance and foster bacterial persistence. Because B7-H3, another member of the B7 family of co-inhibitory receptors, has been found to have important immunoregulatory roles and in cancer, in this study we examined the expression of B7-H3 molecules on GEC and how the expression is regulated by H. pylori during infection. Our study showed that both human and murine GEC constitutively express B7-H3 molecules, but their expression levels increased during H. pylori infection. We further demonstrated that H. pylori uses its type 4 secretion system (T4SS) components CagA and cell wall peptidoglycan (PG) fragment to upregulate B7-H3. Th17 cells and Treg cells which are increased during H. pylori infection also had an effect on B7-H3 induction. The underlying cell signaling pathway involves modulation of p38MAPK pathway. Since B7-H3 were shown to up-regulate Th2 responses, the phenotype of T cell subpopulations in mice infected with H. pylori PMSS1 or SS1 strains were characterized. A mixed Th1/Th2 response in H. pylori infected mice was observed. Consistent with previous findings, increased Treg cells and decreased Th17 cells in MLN of PMSS1 infected mice compared to SS1 infected mice was observed. Human biopsy samples collected from gastritis biopsies and gastric tumors showed a strong association between increased B7-H3 and Th2 responses in H. pylori strains associated with gastritis. T cell: GEC co-cultures and anti-B7-H3 blocking Ab confirmed that the induction of Th2 is mediated by B7-H3 and associated exclusively with an H. pylori gastritis strain not cancer or ulcer strains. In conclusion, these studies revealed a novel regulatory mechanism employed by H. pylori to influence the type of T cell response that develops within the infected gastric mucosa.

Helicobacter pylori elicits B7H3 expression on gastric epithelial cells: Implications in local T cell regulation and subset development during infection

Helicobacter pylori (H. pylori) is a gram negative bacterium that infects more than 50% of humanity and is associated with gastritis, peptic ulcer and gastric cancer. Although CD4+ T cells are recruited to the gastric mucosa, the host is unable to clear the bacteria. Previously, we demonstrated that H. pylori infection upregulates the expression of the T cell co-inhibitory molecule B7-H1 while simultaneously downregulating the expression of T cell co-stimulatory molecule B7-H2 on gastric epithelial cells (GEC), which together affect the Treg and Th17 cell balance and foster bacterial persistence. Because B7-H3, another member of the B7 family of co-inhibitory receptors, has been found to have important immunoregulatory roles and in cancer, in this study we examined the expression of B7-H3 molecules on GEC and how the expression is regulated by H. pylori during infection. Our study showed that both human and murine GEC constitutively express B7-H3 molecules, but their expression levels increased during H. pylori infection. We further demonstrated that H. pylori uses its type 4 secretion system (T4SS) components CagA and cell wall peptidoglycan (PG) fragment to upregulate B7-H3. Th17 cells and Treg cells which are increased during H. pylori infection also had an effect on B7-H3 induction. The underlying cell signaling pathway involves modulation of p38MAPK pathway. Since B7-H3 were shown to up-regulate Th2 responses, the phenotype of T cell subpopulations in mice infected with H. pylori PMSS1 or SS1 strains were characterized. A mixed Th1/Th2 response in H. pylori infected mice was observed. Consistent with previous findings, increased Treg cells and decreased Th17 cells in MLN of PMSS1 infected mice compared to SS1 infected mice was observed. Human biopsy samples collected from gastritis biopsies and gastric tumors showed a strong association between increased B7-H3 and Th2 responses in H. pylori strains associated with gastritis. T cell: GEC co-cultures and anti-B7-H3 blocking Ab confirmed that the induction of Th2 is mediated by B7-H3 and associated exclusively with an H. pylori gastritis strain not cancer or ulcer strains. In conclusion, these studies revealed a novel regulatory mechanism employed by H. pylori to influence the type of T cell response that develops within the infected gastric mucosa.