The CD4+ T cell-mediated IFN-gamma response to Helicobacter infection is essential for clearance and determines gastric cancer risk

Helicobacter pylori induces the expression of Lgr5 and stem cell properties in gastric target cells

Helicobacter pylori infection predisposes carriers to a high risk of developing gastric cancer. The cell-of-origin of antral gastric cancer is the Lgr5+ stem cell. Here, we show that infection of antrum-derived gastric organoid cells with H. pylori increases the expression of the stem cell marker Lgr5 as determined by immunofluorescence microscopy, qRT-PCR, and Western blotting, both when cells are grown and infected as monolayers and when cells are exposed to H. pylori in 3D structures. H. pylori exposure increases stemness properties as determined by spheroid formation assay. Lgr5 expression and the acquisition of stemness depend on a functional type IV secretion system (T4SS) and at least partly on the T4SS effector CagA. The pharmacological inhibition or genetic ablation of NF-κB reverses the increase in Lgr5 and spheroid formation. Constitutively active Wnt/β-catenin signaling because of Apc inactivation exacerbates H. pylori-induced Lgr5 expression and stemness, both of which persist even after eradication of the infection. The combined data indicate that H. pylori has stemness-inducing properties that depend on its ability to activate NF-κB signaling.

An intranasal influenza virus vector vaccine protects against Helicobacter pylori in mice

Helicobacter pylori is a human pathogen that infects almost half of the population. Antibiotic resistance in H. pylori threatens health and increases the demand for prophylactic and therapeutic vaccines. Traditional oral vaccine research faces considerable challenges because of the epithelial barrier, potential enterotoxicity of adjuvants, and the challenging conditions of the gastric environment. We developed an intranasal influenza A virus (IAV) vector vaccine based on two live attenuated influenza viruses with modified acidic polymerase protein (PA) genes encoding the A subunit of H. pylori neutrophil-activating protein (NapA), named IAV-NapA, including influenza virus A/WSN/33 (WSN)-NapA and A/Puerto Rico/8/34 (PR8)-NapA. These recombinant influenza viruses were highly attenuated and exhibited strong immunogenicity in mice. Vaccination with IAV-NapA induced antigen-specific humoral and mucosal immune responses while stimulating robust Th1 and Th17 cell immune responses in mice. Our findings suggest that prophylactic and therapeutic vaccination with influenza virus vector vaccines significantly reduces colonization of H. pylori and inflammation in the stomach of mice.IMPORTANCEHelicobacter pylori is the most common cause of chronic gastritis and leads to severe gastroduodenal pathology in some patients. Many studies have shown that Th1 and Th17 cellular and gastric mucosal immune responses are critical in reducing H. pylori load. IAV vector vaccines can stimulate these immune responses while overcoming potential adjuvant toxicity and antigen dosing issues. To date, no studies have demonstrated the role of live attenuated IAV vector vaccines in preventing and treating H. pylori infection. Our work indicates that vaccination with IAV-NapA induces antigen-specific humoral, cellular, and mucosal immunity, producing a protective and therapeutic effect against H. pylori infection in BALB/c mice. This undescribed H. pylori vaccination approach may provide valuable information for developing vaccines against H. pylori infection.

WITHDRAWN: PIRES2-EGFP/CTB-UreI vaccination activated a mixed Th1/Th2/Th17 immune system defense towards Helicobacter pylori infection in the BALB/c mice model

This article has been withdrawn at the request of the Editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/policies/article-withdrawal. The data presented in the manuscript was deemed severely flawed after appearing online as an Article in Press. The scientific community raised concerns about the methodology (including but not limited to major technical issues) used in the study and the subsequent conclusions drawn from the presented experiments. After careful investigation, the Vaccine editorial office concluded that the data in the publication was indeed severely flawed and that the concerns raised by the scientific community were valid. Therefore, the journal editors decided to withdraw the article and sincerely apologize for any inconvenience caused.

Inactivation of the tumor suppressor gene Apc synergizes with H. pylori to induce DNA damage in murine gastric stem and progenitor cells

Helicobacter pylori infection is a major risk factor for the development of gastric cancer. The bacteria reside in close proximity to gastric surface mucous as well as stem and progenitor cells. Here, we take advantage of wild-type and genetically engineered murine gastric organoids and organoid-derived monolayers to study the cellular targets of H. pylori-induced DNA damage and replication stress and to explore possible interactions with preexisting gastric cancer driver mutations. We find using alkaline comet assay, single-molecule DNA fiber assays, and immunofluorescence microscopy of DNA repair foci that H. pylori induces transcription-dependent DNA damage in actively replicating, Leucine-rich-repeat containing G-Protein-Coupled Receptor 5 (Lgr5)-positive antral stem and progenitor cells and their Troy-positive corpus counterparts, but not in other gastric epithelial lineages. Infection-dependent DNA damage is aggravated by Apc inactivation, but not by Trp53 or Smad4 loss, or Erbb2 overexpression. Our data suggest that H. pylori induces DNA damage in stem and progenitor cells, especially in settings of hyperproliferation due to constitutively active Wnt signaling.

An Evaluation of Urease A Subunit Nanocapsules as a Vaccine in a Mouse Model of Helicobacter pylori Infection

Using removable silica templates, protein nanocapsules comprising the A subunit of Helicobacter pylori urease (UreA) were synthesised. The templates were of two sizes, with solid core mesoporous shell (SC/MS) silica templates giving rise to nanocapsules of average diameter 510 nm and mesoporous (MS) silica templates giving rise to nanocapsules of average diameter 47 nm. Both were shown to be highly monodispersed and relatively homogenous in structure. Various combinations of the nanocapsules in formulation were assessed as vaccines in a mouse model of H. pylori infection. Immune responses were evaluated and protective efficacy assessed. It was demonstrated that vaccination of mice with the larger nanocapsules combined with an adjuvant was able to significantly reduce colonisation.

Designing and development of multi-epitope chimeric vaccine against Helicobacter pylori by exploring its entire immunogenic epitopes: an immunoinformatic approach

BACKGROUND

Helicobacter pylori is a prominent causative agent of gastric ulceration, gastric adenocarcinoma and gastric lymphoma and have been categorised as a group 1 carcinogen by WHO. The treatment of H. pylori with proton pump inhibitors and antibiotics is effective but also leads to increased antibiotic resistance, patient dissatisfaction, and chances of reinfection. Therefore, an effective vaccine remains the most suitable prophylactic option for mass administration against this infection.

RESULTS

We modelled a multi-chimera subunit vaccine candidate against H. pylori by screening its secretory/outer membrane proteins. We identified B-cell, MHC-II and IFN-γ-inducing epitopes within these proteins. The population coverage, antigenicity, physiochemical properties and secondary structure were evaluated using different in-silico tools, which showed it can be a good and effective vaccine candidate. The 3-D construct was predicted, refined, validated and docked with TLRs. Finally, we performed the molecular docking/simulation and immune simulation studies to validate the stability of interaction and in-silico cloned the epitope sequences into a pET28b(+) plasmid vector.

CONCLUSION

The multiepitope-constructed vaccine contains T- cells, B-cells along with IFN-γ inducing epitopes that have the property to generate good cell-mediated immunity and humoral response. This vaccine can protect most of the world's population. The docking study and immune simulation revealed a good binding with TLRs and cell-mediated and humoral immune responses, respectively. Overall, we attempted to design a multiepitope vaccine and expect this vaccine will show an encouraging result against H. pylori infection in in-vivo use.

Single-cell Profiling Uncovers a Muc4-Expressing Metaplastic Gastric Cell Type Sustained by Helicobacter pylori-driven Inflammation

Mechanisms for Helicobacter pylori (Hp)-driven stomach cancer are not fully understood. In a transgenic mouse model of gastric preneoplasia, concomitant Hp infection and induction of constitutively active KRAS (Hp+KRAS+) alters metaplasia phenotypes and elicits greater inflammation than either perturbation alone. Gastric single-cell RNA sequencing showed that Hp+KRAS+ mice had a large population of metaplastic pit cells that expressed the intestinal mucin Muc4 and the growth factor amphiregulin. Flow cytometry and IHC-based immune profiling revealed that metaplastic pit cells were associated with macrophage and T-cell inflammation. Accordingly, expansion of metaplastic pit cells was prevented by gastric immunosuppression and reversed by antibiotic eradication of Hp. Finally, MUC4 expression was significantly associated with proliferation in human gastric cancer samples. These studies identify an Hp-associated metaplastic pit cell lineage, also found in human gastric cancer tissues, whose expansion is driven by Hp-dependent inflammation.

Significance

Using a mouse model, we have delineated metaplastic pit cells as a precancerous cell type whose expansion requires Hp-driven inflammation. In humans, metaplastic pit cells show enhanced proliferation as well as enrichment in precancer and early cancer tissues, highlighting an early step in the gastric metaplasia to cancer cascade.

Tubulointerstitial nephritis antigen-like 1 is a novel matricellular protein that promotes gastric bacterial colonization and gastritis in the setting of Helicobacter pylori infection

The interaction between the gastric epithelium and immune cells plays key roles in H. pylori-associated pathology. Here, we demonstrate a procolonization and proinflammatory role of tubulointerstitial nephritis antigen-like 1 (TINAGL1), a newly discovered matricellular protein, in H. pylori infection. Increased TINAGL1 production by gastric epithelial cells (GECs) in the infected gastric mucosa was synergistically induced by H. pylori and IL-1β via the ERK-SP1 pathway in a cagA-dependent manner. Elevated human gastric TINAGL1 correlated with H. pylori colonization and the severity of gastritis, and mouse TINAGL1 derived from non-bone marrow-derived cells promoted bacterial colonization and inflammation. Importantly, H. pylori colonization and inflammation were attenuated in Tinagl1-/- and Tinagl1ΔGEC mice and were increased in mice injected with mouse TINAGL1. Mechanistically, TINAGL1 suppressed CCL21 expression and promoted CCL2 production in GECs by directly binding to integrin α5β1 to inhibit ERK and activate the NF-κB pathway, respectively, which not only led to decreased gastric influx of moDCs via CCL21-CCR7-dependent migration and, as a direct consequence, reduced the bacterial clearance capacity of the H. pylori-specific Th1 response, thereby promoting H. pylori colonization, but also resulted in increased gastric influx of Ly6Chigh monocytes via CCL2-CCR2-dependent migration. In turn, TINAGL1 induced the production of the proinflammatory protein S100A11 by Ly6Chigh monocytes, promoting H. pylori-associated gastritis. In summary, we identified a model in which TINAGL1 collectively ensures H. pylori persistence and promotes gastritis.

Artificial intelligence-guided discovery of gastric cancer continuum

BACKGROUND

Detailed understanding of pre-, early and late neoplastic states in gastric cancer helps develop better models of risk of progression to gastric cancers (GCs) and medical treatment to intercept such progression.

METHODS

We built a Boolean implication network of gastric cancer and deployed machine learning algorithms to develop predictive models of known pre-neoplastic states, e.g., atrophic gastritis, intestinal metaplasia (IM) and low- to high-grade intestinal neoplasia (L/HGIN), and GC. Our approach exploits the presence of asymmetric Boolean implication relationships that are likely to be invariant across almost all gastric cancer datasets. Invariant asymmetric Boolean implication relationships can decipher fundamental time-series underlying the biological data. Pursuing this method, we developed a healthy mucosa → GC continuum model based on this approach.

RESULTS

Our model performed better against publicly available models for distinguishing healthy versus GC samples. Although not trained on IM and L/HGIN datasets, the model could identify the risk of progression to GC via the metaplasia → dysplasia → neoplasia cascade in patient samples. The model could rank all publicly available mouse models for their ability to best recapitulate the gene expression patterns during human GC initiation and progression.

CONCLUSIONS

A Boolean implication network enabled the identification of hitherto undefined continuum states during GC initiation. The developed model could now serve as a starting point for rationalizing candidate therapeutic targets to intercept GC progression.

Immune Biology and Persistence of Helicobacter pylori in Gastric Diseases

Helicobacter pylori is a prevalent pathogen, which affects more than 40% of the global population. It colonizes the human stomach and persists in its host for several decades or even a lifetime, if left untreated. The persistent infection has been linked to various gastric diseases, including gastritis, peptic ulcers, and an increased risk for gastric cancer. H. pylori infection triggers a strong immune response directed against the bacterium associated with the infiltration of innate phagocytotic immune cells and the induction of a Th1/Th17 response. Even though certain immune cells seem to be capable of controlling the infection, the host is unable to eliminate the bacteria as H. pylori has developed remarkable immune evasion strategies. The bacterium avoids its killing through innate recognition mechanisms and manipulates gastric epithelial cells and immune cells to support its persistence. This chapter focuses on the innate and adaptive immune response induced by H. pylori infection, and immune evasion strategies employed by the bacterium to enable persistent infection.

Gastric Stem Cell Biology and Helicobacter pylori Infection

Helicobacter pylori colonizes the human gastric mucosa and persists lifelong. An interactive network between the bacteria and host cells shapes a unique microbial niche within gastric glands that alters epithelial behavior, leading to pathologies such as chronic gastritis and eventually gastric cancer. Gland colonization by the bacterium initiates aberrant trajectories by inducing long-term inflammatory and regenerative gland responses, which involve various specialized epithelial and stromal cells. Recent studies using cell lineage tracing, organoids and scRNA-seq techniques have significantly advanced our knowledge of the molecular "identity" of epithelial and stromal cell subtypes during normal homeostasis and upon infection, and revealed the principles that underly stem cell (niche) behavior under homeostatic conditions as well as upon H. pylori infection. The activation of long-lived stem cells deep in the gastric glands has emerged as a key prerequisite of H. pylori-associated gastric site-specific pathologies such as hyperplasia in the antrum, and atrophy or metaplasia in the corpus, that are considered premalignant lesions. In addition to altering the behaviour of bona fide stem cells, injury-driven de-differentiation and trans-differentation programs, such as "paligenosis", subsequently allow highly specialized secretory cells to re-acquire stem cell functions, driving gland regeneration. This plastic regenerative capacity of gastric glands is required to maintain homeostasis and repair mucosal injuries. However, these processes are co-opted in the context of stepwise malignant transformation in chronic H. pylori infection, causing the emergence, selection and expansion of cancer-promoting stem cells.

Perspectives from recent advances of Helicobacter pylori vaccines research

BACKGROUND

Helicobacter pylori (H. pylori) infection is the main factor leading to some gastric diseases. Currently, H. pylori infection is primarily treated with antibiotics. However, with the widespread application of antibiotics, H. pylori resistance to antibiotics has also gradually increased year by year. Vaccines may be an alternative solution to clear H. pylori.

AIMS

By reviewing the recent progress on H. pylori vaccines, we expected it to lead to more research efforts to accelerate breakthroughs in this field.

MATERIALS & METHODS

We searched the research on H. pylori vaccine in recent years through PubMed®, and then classified and summarized these studies.

RESULTS

The study of the pathogenic mechanism of H. pylori has led to the development of vaccines using some antigens, such as urease, catalase, and heat shock protein (Hsp). Based on these antigens, whole-cell, subunit, nucleic acid, vector, and H. pylori exosome vaccines have been tested.

DISCUSSION

At present, researchers have developed many types of vaccines, such as whole cell vaccines, subunit vaccines, vector vaccines, etc. However, although some of these vaccines induced protective immunity in mouse models, only a few were able to move into human trials. We propose that mRNA vaccine may play an important role in preventing or treating H. pylori infection. The current study shows that we have developed various types of vaccines based on the virulence factors of H. pylori. However, only a few vaccines have entered human clinical trials. In order to improve the efficacy of vaccines, it is necessary to enhance T-cell immunity.

CONCLUSION

We should fully understand the pathogenic mechanism of H. pylori and find its core antigen as a vaccine target.

IFNγ-dependent silencing of TFF1 during Helicobacter pylori infection

Chronic Helicobacter pylori infection is the leading cause of intestinal-type adenocarcinoma, as prolonged Helicobacter colonization triggers chronic active gastritis, which may evolve into adenocarcinoma of the intestinal type. In this environment, cytokines play a significant role in determining the evolution of the infection. In combination with other factors (genetic, environmental and nutritional), the pro-inflammatory response may trigger pro-oncogenic mechanisms that lead to the silencing of tumour-suppressor genes, such as trefoil factor 1 (TFF1). The latter is known to play a protective role by maintaining the gastric mucosa integrity and retaining H. pylori in the mucus layer, preventing the progression of infection and, consequently, the development of gastric cancer (GC). Since TFF1 expression is reduced during chronic Helicobacter infection with a loss of gastric mucosa protection, we investigated the molecular pathways involved in this reduction. Specifically, we evaluated the effect of some pro-inflammatory cytokines on TFF1 regulation in GC and primary gastric cells by RT-qPCR and luciferase reporter assay analyses and the repressor role of the transcription factor C/EBPβ, overexpressed in gastric-intestinal cancer. Our results show that, among several cytokines, IFNγ stimulates C/EBPβ expression, which acts as a negative regulator of TFF1 by binding its promoter at three different sites.

Inhibitory and Injury-Protection Effects of O-Glycan on Gastric Epithelial Cells Infected with Helicobacter pylori

Helicobacter pylori (H. pylori) is an important pathogen that can cause gastric cancer. Multiple adhesion molecules mediated H. pylori adherence to cells is the initial step in the infection of host cells. H. pylori cholesterol-α-glucosyltransferase (CGT) recognizes and extracts cholesterol from cell membranes to destroy lipid raft structure, further promotes H. pylori adhesion to gastric epithelial cells. O-Glycan, a substance secreted by the deep gastric mucosa, can competitively inhibit CGT activity and may serve as an important factor to prevent H. pylori colonization in the deep gastric mucosa. However, the inhibitory and injury-protection effects of O-Glycan against H. pylori infection has not been well investigated. In this study, we found that O-Glycan significantly inhibited the relative urease content in the coinfection system. In the presence of O-glycan, the injury of GES-1 cells in H. pylori persistent infection model was attenuated and the cell viability was increased. We use fluorescein isothiocyanate-conjugated cholera toxin subunit B (FITC-CTX-B) to detect lipid rafts on gastric epithelial cells and observed that O-glycan can protect H. pylori from damaging lipid raft structures on cell membranes. In addition, transcriptome data showed that O-glycan treatment significantly reduced the activation of inflammatory cancer transformation pathway caused by H. pylori infection. Our results suggest that O-Glycan is able to inhibit H. pylori persistent infection of gastric epithelial cells, reduce the damage caused by H. pylori, and could serve as a potential medicine to treat patients infected with H. pylori.

Beyond the gastric epithelium - the paradox of Helicobacter pylori-induced immune responses

Chronic infections are typically characterized by an ineffective immune response to the inducing pathogen. While failing to clear the infectious microbe, the provoked inflammatory processes may cause severe tissue damage culminating in functional impairment of the affected organ. The human pathogen Helicobacter pylori is a uniquely successful Gram-negative microorganism inhabiting the gastric mucosa in approximately 50% of the world's population. This bacterial species has evolved spectacular means of evading immune surveillance and influencing host immunity, leading to a fragile equilibrium between proinflammatory and anti-inflammatory signals, the breakdown of which can have serious consequences for the host, including gastric ulceration and cancer. This review highlights novel insights into this delicate interaction between host and pathogen from an immunological perspective.

Helicobacter pylori-induced RASAL2 Through Activation of Nuclear Factor-κB Promotes Gastric Tumorigenesis via β-catenin Signaling Axis

BACKGROUND & AIMS

Helicobacter pylori infection is the predominant risk factor for gastric cancer. RAS protein activator like 2 (RASAL2) is considered a double-edged sword in carcinogenesis. Herein, we investigated the role of RASAL2 in response to H pylori infection and gastric tumorigenesis.

METHODS

Bioinformatics analyses of local and public databases were applied to analyze RASAL2 expression, signaling pathways, and clinical significance. In vitro cell culture, spheroids, patient-derived organoids, and in vivo mouse models were used. Molecular assays included chromatin immunoprecipitation, co-immunoprecipitation, Western blotting, quantitative polymerase chain reaction, and immunocyto/histochemistry.

RESULTS

H pylori infection induced RASAL2 expression via a nuclear factor-κB (NF-κB)-dependent mechanism whereby NF-κB was directly bound to the RASAL2 promoter activating its transcription. By gene silencing and ectopic overexpression, we found that RASAL2 upregulated β-catenin transcriptional activity. RASAL2 inhibited protein phosphatase 2A activity through direct binding with subsequent activation of the AKT/β-catenin signaling axis. Functionally, RASAL2 silencing decreased nuclear β-catenin levels and impaired tumor spheroids and organoids formation. Furthermore, the depletion of RASAL2 impaired tumor growth in gastric tumor xenograft mouse models. Clinicopathological analysis indicated that abnormal overexpression of RASAL2 correlated with poor prognosis and chemoresistance in human gastric tumors.

CONCLUSIONS

These studies uncovered a novel signaling axis of NF-κB/RASAL2/β-catenin, providing a novel link between infection, inflammation and gastric tumorigenesis.

BMP feed-forward loop promotes terminal differentiation in gastric glands and is interrupted by H. pylori-driven inflammation

Helicobacter pylori causes gastric inflammation, gland hyperplasia and is linked to gastric cancer. Here, we studied the interplay between gastric epithelial stem cells and their stromal niche under homeostasis and upon H. pylori infection. We find that gastric epithelial stem cell differentiation is orchestrated by subsets of stromal cells that either produce BMP inhibitors in the gland base, or BMP ligands at the surface. Exposure to BMP ligands promotes a feed-forward loop by inducing Bmp2 expression in the epithelial cells themselves, enforcing rapid lineage commitment to terminally differentiated mucous pit cells. H. pylori leads to a loss of stromal and epithelial Bmp2 expression and increases expression of BMP inhibitors, promoting self-renewal of stem cells and accumulation of gland base cells, which we mechanistically link to IFN-γ signaling. Mice that lack IFN-γ signaling show no alterations of BMP gradient upon infection, while exposure to IFN-γ resembles H. pylori-driven mucosal responses.

Helicobacter pylori causes gastric inflammation, gland hyperplasia and is linked to gastric cancer. Here the authors identify a BMP feedback loop between the stomach epithelium and surrounding stroma that controls gland homeostasis and demonstrate its interruption upon infection with H. pylori.

Mycobacterial infection aggravates Helicobacter pylori-induced gastric preneoplastic pathology by redirection of de novo induced Treg cells

The two human pathogens Helicobacter pylori and Mycobacterium tuberculosis (Mtb) co-exist in many geographical areas of the world. Here, using a co-infection model of H. pylori and the Mtb relative M. bovis bacillus Calmette-Guérin (BCG), we show that both bacteria affect the colonization and immune control of the respective other pathogen. Co-occurring M. bovis boosts gastric Th1 responses and H. pylori control and aggravates gastric immunopathology. H. pylori in the stomach compromises immune control of M. bovis in the liver and spleen. Prior antibiotic H. pylori eradication or M. bovis-specific immunization reverses the effects of H. pylori. Mechanistically, the mutual effects can be attributed to the redirection of regulatory T cells (Treg cells) to sites of M. bovis infection. Reversal of Treg cell redirection by CXCR3 blockade restores M. bovis control. In conclusion, the simultaneous presence of both pathogens exacerbates the problems associated with each individual infection alone and should possibly be factored into treatment decisions.

Aberrant lipid metabolism reprogramming and immune microenvironment for gastric cancer: a literature review

Objective

We summarize the aberrant lipid metabolism disorders associated with enzyme activity and expression changes and related immune microenvironment for gastric cancer.

Background

Gastric cancer is a malignant tumor of the primary digestive system with high incidence, poor prognosis characterized by extensive metastasis and poor effect with radiotherapy and chemotherapy. One of the most important metabolic characteristics of cancer cells is lipid metabolism reprogramming to adapt to the tumor micro-environment.

Methods

The focus of research in recent years has also been on lipid metabolism disorders, particularly aberrant metabolism of fatty acids (FAs) in gastric cancer cells, as well as an upregulation of the expression and activity of key enzymes in lipid metabolism. These changes remind us of the occurrence and development of gastric cancer. These metabolic changes are not unique to cancer cells. Changes in metabolic procedures also determine the function and viability of immune cells. In the immune microenvironment of gastric cancer, the metabolic competition and interaction between cancer cells and immune cells are not very clear, while a deeper understanding of the topic is critical to targeting the differential metabolic requirements of them that comprise an immune response to cancer offers an opportunity to selectively regulate immune cell function.

Conclusions

Recent research suggests that targeting metabolism is an emerging and potentially promising treatment strategy for gastric cancer patients. We need to explore it further.

IL-9 contributes to the host immune response against Helicobacter pylori and helps limit infection in a Mouse Model

BACKGROUND

As an important mediator in lots of diseases, interleukin-9 (IL-9) can be a protector or pro-inflammatory cytokine depending on the complicated inflammatory milieu. Helicobacter pylori (H. pylori) induced a series of immunology cells and cytokines change, and however, the role of IL-9 in H. pylori infection remains unknown.

MATERIALS AND METHODS

Wild-type and IL-9 deficient mice were infected with H. pylori by means of intragastric administration. The colonization of H. pylori bacteria was measured by detecting specific 16s rDNA, and the intensity of inflammation was observed by H&E stain. The expression level of inflammation cytokines was determined by ELISA and quantitative real-time PCR.

RESULTS

IL-9 was increased due to the attack of H. pylori, besides deletion of Il9 aggravated the bacterial colonization and inflammation intensity. In addition, treatment of rmIL-9 reduced colonized H. pylori and inflammation level, indicated that IL-9 was a protector for the host against this bacterium. Followed by the H. pylori infection, interferon (IFN)-γ and interleukin (IL)-17A were up-regulated as expected, and nevertheless, the expression of IL-17A shared a positive relationship with IL-9 while IFN-γ negative associated with IL-9. Moreover, we also proved that Treg cells were not involved in the protective effect of IL-9, and meanwhile, CD4⁺ CD25^- T cells secreted more IFN-γ and less IL-17A in vitro due to the deletion of Il9.

CONCLUSIONS

IL-9 plays a protective role against H. pylori and the protection associated with cytokines change including IFN-γ and IL-17A.

IL13 Acts Directly on Gastric Epithelial Cells to Promote Metaplasia Development During Chronic Gastritis

BACKGROUND & AIMS

It is well established that chronic inflammation promotes gastric cancer-associated metaplasia, but little is known regarding the mechanisms by which immune cells and cytokines regulate metaplastic cellular changes. The goals of this study were to identify interleukin 13 (IL13)-producing immune cells, determine the gastric epithelial cell response(s) to IL13, and establish the role(s) of IL13 in metaplasia development.

METHODS

Experiments used an established mouse model of autoimmune gastritis (TxA23), TxA23×Il4ra-/- mice, which develop gastritis but do not express the IL4/IL13-receptor subunit IL4Rα, and TxA23×Il13-Yfp mice, which express yellow fluorescent protein in IL13-producing cells. Flow cytometry was used to measure IL13 secretion and identify IL13-producing immune cells. Mouse and human gastric organoids were cultured with IL13 to determine epithelial cell response(s) to IL13. Single-cell RNA sequencing was performed on gastric epithelial cells from healthy and inflamed mouse stomachs. Mice with gastritis were administered IL13-neutralizing antibodies and stomachs were analyzed by histopathology and immunofluorescence.

RESULTS

We identified 6 unique subsets of IL13-producing immune cells in the inflamed stomach. Organoid cultures showed that IL13 acts directly on gastric epithelium to induce a metaplastic phenotype. IL4Rα-deficient mice did not progress to metaplasia. Single-cell RNA sequencing determined that gastric epithelial cells from IL4Rα-deficient mice up-regulated inflammatory genes but failed to up-regulate metaplasia-associated transcripts. Neutralization of IL13 significantly reduced and reversed metaplasia development in mice with gastritis.

CONCLUSIONS

IL13 is made by a variety of immune cell subsets during chronic gastritis and promotes gastric cancer-associated metaplastic epithelial cell changes. Neutralization of IL13 reduces metaplasia severity during chronic gastritis.

The Role of Helicobacter pylori Proinflammatory Outer Membrane Protein and Propolis in Immunomodulation on U937 Macrophage Cell Model

Background

Regarding the important role of proinflammatory outer membrane protein (OipA) in the pathogenesis of Helicobacter pylori infection and immunomodulatory activity of propolis, we aimed to evaluate the immunogenicity effect of a purified recombinant OipA protein and propolis in the induction of two cytokines, interferon-gamma (IFN-γ) and interleukin-4 (IL-4), in a macrophage cell model.

Materials and Methods

The recombinant protein used in the present study corresponding to the oipA expressing a 34-35 kDa protein. OipA protein was purified by Ni-NTA affinity chromatography. The purified OipA protein (2.5- 40 μg /mL) and the propolis ethanolic extract (5-40 μg/mL) were incubated with phorbol 12-myristate 13-acetate-treated human myelomonocytic cell line U937 cells. IL-4 and IFN-γ levels were measured after 48 hours of incubation using enzyme-linked immunosorbent assay.

Results

The amounts of IL-4 and IFN-γ were significantly increased. The optimum concentration of OipA for the secretion of IL-4 was 5 μg/ml (P<0.0001). At higher concentrations, the amount of IL-4 diminished until suppression at 40 μg/mL. The optimum concentration of propolis, resulting in the most significant increased secretion of both IL-4 and IFN-γ was 40 μg/mL (P=0.0001 and P=0.0004).

Conclusion

We found that an OipA concentration of 10 μg/mL was more effective for IFN-γ production; however, it was not effective for the high production of IL-4. Therefore, it is postulated that the OipA could mainly induce a Th1 response through the production of IFN-γ. We also observed propolis's capability to induce IFN-γ production; however, the effective concentration for this was the same as for IL-4. Therefore, as an adjuvant, proper concentration of propolis is required for OipA to give the optimum response.

Cytokine TGF-β1, TNF-α, IFN-γ and IL-6 Gene Polymorphisms and Localization of Premalignant Gastric Lesions in Immunohistochemically H. pylori-negative Patients

Background: Cytokines and their gene variants are proven to play a role in pathogenic gastritis and carcinogenesis. The study assesses associations of the cytokine gene polymorphisms with extension of atrophic gastritis/intestinal metaplasia (AGIM) in patients without Helicobacter pylori infection on immunohistochemistry study. Methods: 224 adult consecutive patients undergoing an upper digestive endoscopy were included and grouped according to localization of AGIM: 37 patients with antrum-limited AGIM, 21 corpus-limited AGIM, 15 extended-AGIM (antrum and corpus) and 151 patients had no AGIM. Medical records of the patients were checked and a structured direct interview was applied in order to collect clinical data, including digestive symptoms. In all cases, IFN-γ +874T>A, TGF-β1 +869T>C, TNF-α-308G>A and -238G>A, and IL-6 -174C>G polymorphisms were genotyped. Results: The mean age was significantly higher in the AGIM group, while the comorbidies were similar among patients with different localization of lesions or in patients without AGIM. There were no significant differences in digestive symptoms, nor in the consumption of non-steroidal anti-inflammatory drugs or proton pump inhibitor with the different extensions of AGIM. There was a significant association between oral anticoagulant consumption and localization of AGIM (P = 0.042), frequency being higher among patients with corpus-limited AGIM than those with no AGIM (P = 0.007, adjusted P = 0.041). TGF-β1 +869T>C was less frequent among patients with corpus-limited AGIM (n=7, 33.3%) and extended AGIM (n=5, 33.3%) than in antrum-limited AGIM (n=25, 67.6%). There were no other significant differences regarding variant and wild genotype frequencies of IFN-γ +874T>A (86.5%, 81.0%, 86.7%, p=0.814), TNF-α-308G>A (35.1%, 28.6%, 53.3%, p=0.48) and IL-6 -174C>G (70.3%. 61.9%, 73.3% p=0.656) among patients with antrum-limited, corpus-limited or extended AGIM. TGF-β1 +869T>C was associated with a decreased risk for corpus-affected AGIM (adjusted odds ratio: 0.42, 95% confidence interval: 0.19-0.93, P = 0.032). The dominant inheritance models no revealed significant association for IFN-γ +874T>A, TNF-α-308G>A and IL-6 -174C>G gene polymorphism and the risk of localization of AGIM. Conclusion: TGF-β1 +869T>C gene polymorphism is associated with a decreased risk for corporeal localization of premalignant lesions, while IFN-γ +874T>A, TNF-α-308G>A and IL-6 -174C>G are not associated with the risk for AGIM in immunohistochemically H. pylori negative patients.

Programmed Death Ligand 1-Expressing Classical Dendritic Cells MitigateHelicobacter-Induced Gastritis

BACKGROUND & AIMS

Helicobacter pylori has been reported to modulate local immune responses to colonize persistently in gastric mucosa. Although the induced expression of programmed cell death ligand 1 (PD-L1) has been suggested as an immune modulatory mechanism for persistent infection of H pylori, the main immune cells expressing PD-L1 and their functions in Helicobacter-induced gastritis still remain to be elucidated.

METHODS

The blockades of PD-L1 with antibody or PD-L1-deficient bone marrow transplantation were performed in Helicobacter-infected mice. The main immune cells expressing PD-L1 in Helicobacter-infected stomach were determined by flow cytometry and immunofluorescence staining. Helicobacter felis or H pylori-infected dendritic cell (DC)-deficient mouse models including Flt3-/-, Zbtb46-diphtheria toxin receptor, and BDCA2-diphtheria toxin receptor mice were analyzed for pathologic changes and colonization levels. Finally, the location of PD-L1-expressing DCs and the correlation with H pylori infection were analyzed in human gastric tissues using multiplexed immunohistochemistry.

RESULTS

Genetic or antibody-mediated blockade of PD-L1 aggravated Helicobacter-induced gastritis with mucosal metaplasia. Gastric classical DCs expressed considerably higher levels of PD-L1 than other immune cells and co-localized with T cells in gastritis lesions from Helicobacter-infected mice and human beings. H felis- or H pylori-infected Flt3-/- or classical DC-depleted mice showed aggravated gastritis with severe T-cell and neutrophil accumulation with low bacterial loads compared with that in control mice. Finally, PD-L1-expressing DCs were co-localized with T cells and showed a positive correlation with H pylori infection in human subjects.

CONCLUSIONS

The PD-1/PD-L1 pathway may be responsible for the immune modulatory function of gastric DCs that protects the gastric mucosa from Helicobacter-induced inflammation, but allows persistent Helicobacter colonization.

Helicobacter-stimulated IL-10-producing B cells suppress differentiation of lipopolysaccharide/Helicobacter felis-activated stimulatory dendritic cells

Regulatory B cells (Bregs) produce antiinflammatory cytokines and inhibits proinflammatory response. Recently, immunosuppressive roles of Bregs in the effector functions of dendritic cells (DCs) were demonstrated. However, cross talk between Bregs and DCs in Helicobacter infection remains unknown. Here, we showed that direct stimulation of bone marrow-derived DCs (BM-DCs) with Helicobacter felis (H. felis) antigen upregulates their CD86 surface expression and causes the production of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), interleukin-12 (IL-12), and interleukin-10 (IL-10). Furthermore, prestimulation of DCs with supernatants derived from both Helicobacter-stimulated IL-10^– B (Hf_stim-IL-10^– B) or IL-10⁺ B (Hf_stim-IL-10⁺) cells suppresses the secretion of TNF-α and IL-6, but does not affect the expression of CD86 and secretion of IL-12 by lipopolysaccharide (LPS) or H. felis-activated BM-DCs. Remarkably, soluble factors secreted by Hf_stim-IL-10^– B cells, but not by Hf_stim-IL-10⁺ B cells, suppress the secretion of IL-10 by BM-DCs upon subsequent LPS stimulation. In contrast, prestimulation with BM-DCs with supernatants of Hf_stim-IL-10⁺ B cells before H. felis antigen stimulation induces significantly their IL-10 production. Collectively, our data indicated that prestimulation with soluble factors secreted by Hf_stim-IL-10⁺ B cells, DCs exhibit a tolerogenic phenotype in response to LPS or Helicobacter antigen by secreting high levels of IL-10, but decreased levels of IL-6 and TNF-α.

Cholesterol glucosylation-based survival strategy in Helicobacter pylori

Helicobacter pylori is a major chronic health problem, infecting more than half of the population worldwide. H. pylori infection is linked with various clinical complications ranging from gastritis to gastric cancer. The resolution of gastritis and peptic ulcer appears to be linked with the eradication of H. pylori. However, resistance to antibiotics and eradication failure rates are reaching alarmingly high levels. This calls for urgent action in finding alternate methods for H. pylori eradication. Here, we discuss the recently identified mechanism of H. pylori known as cholesterol glucosylation, mediated by the enzyme cholesterol-α-glucosyltransferase, encoded by the gene cgt. Cholesterol glucosylation serves several functions that include promoting immune evasion, enhancing antibiotic resistance, maintaining the native helical morphology, and supporting functions of prominent virulence factors such as CagA and VacA. Consequently, strategies aiming at inhibition of the cholesterol glucosylation process have the potential to attenuate the potency of H. pylori infection and abrogate H. pylori immune evasion capabilities. Knockout of H. pylori cgt results in unsuccessful colonization and elimination by the host immune responses. Moreover, blocking cholesterol glucosylation can reverse antibiotic susceptibility in H. pylori. In this work, we review the main roles of cholesterol glucosylation in H. pylori and evaluate whether this mechanism can be targeted for the development of alternate methods for eradication of H. pylori infection.

Helicobacter pylori-Induced Rev-erbα Fosters Gastric Bacteria Colonization by Impairing Host Innate and Adaptive Defense

BACKGROUND & AIMS

Rev-erbα represents a powerful transcriptional repressor involved in immunity. However, the regulation, function, and clinical relevance of Rev-erbα in Helicobacter pylori infection are presently unknown.

METHODS

Rev-erbα was examined in gastric samples from H pylori-infected patients and mice. Gastric epithelial cells (GECs) were isolated and infected with H pylori for Rev-erbα regulation assays. Gastric tissues from Rev-erbα^-/- and wild-type (littermate control) mice or these mice adoptively transferred with CD4⁺ T cells from IFN-γ^-/- and wild-type mice, bone marrow chimera mice and mice with in vivo pharmacological activation or inhibition of Rev-erbα were examined for bacteria colonization. GECs, CD45⁺CD11c^-Ly6G^-CD11b⁺CD68^- myeloid cells and CD4⁺ T cells were isolated, stimulated and/or cultured for Rev-erbα function assays.

RESULTS

Rev-erbα was increased in gastric mucosa of H pylori-infected patients and mice. H pylori induced GECs to express Rev-erbα via the phosphorylated cagA that activated ERK signaling pathway to mediate NF-κB directly binding to Rev-erbα promoter, which resulted in increased bacteria colonization within gastric mucosa. Mechanistically, Rev-erbα in GECs not only directly suppressed Reg3b and β-defensin-1 expression, which resulted in impaired bactericidal effects against H pylori of these antibacterial proteins in vitro and in vivo; but also directly inhibited chemokine CCL21 expression, which led to decreased gastric influx of CD45⁺CD11c^-Ly6G^-CD11b⁺CD68^- myeloid cells by CCL21-CCR7-dependent migration and, as a direct consequence, reduced bacterial clearing capacity of H pylori-specific Th1 cell response.

CONCLUSIONS

Overall, this study identifies a model involving Rev-erbα, which collectively ensures gastric bacterial persistence by suppressing host gene expression required for local innate and adaptive defense against H pylori.

Sustained Helicobacter pylori infection accelerates gastric dysplasia in a mouse model

More than 80% of gastric cancer is attributable to stomach infection with Helicobacter pylori (Hp). Gastric preneoplastic progression involves sequential tissue changes, including loss of parietal cells, metaplasia and dysplasia. In transgenic mice, active KRAS expression recapitulates these tissue changes in the absence of Hp infection. This model provides an experimental system to investigate additional roles of Hp in preneoplastic progression, beyond its known role in initiating inflammation. Tissue histology, gene expression, the immune cell repertoire, and metaplasia and dysplasia marker expression were assessed in KRAS+ mice +/-Hp infection. Hp+/KRAS+ mice had severe T-cell infiltration and altered macrophage polarization; a different trajectory of metaplasia; more dysplastic glands; and greater proliferation of metaplastic and dysplastic glands. Eradication of Hp with antibiotics, even after onset of metaplasia, prevented or reversed these tissue phenotypes. These results suggest that gastric preneoplastic progression differs between Hp+ and Hp- cases, and that sustained Hp infection can promote the later stages of gastric preneoplastic progression.

Dysregulated Immune Responses by ASK1 Deficiency Alter Epithelial Progenitor Cell Fate and Accelerate Metaplasia Development during H. pylori Infection

The mechanism of H. pylori-induced atrophy and metaplasia has not been fully understood. Here, we demonstrate the novel role of Apoptosis signal-regulating kinase 1 (ASK1) and downstream MAPKs as a regulator of host immune responses and epithelial maintenance against H. pylori infection. ASK1 gene deficiency resulted in enhanced inflammation with numerous inflammatory cells including Gr-1+CD11b+ myeloid-derived suppressor cells (MDSCs) recruited into the infected stomach. Increase of IL-1β release from apoptotic macrophages and enhancement of TH1-polarized immune responses caused STAT1 and NF-κB activation in epithelial cells in ASK1 knockout mice. Dysregulated immune and epithelial activation in ASK1 knockout mice led to dramatic expansion of gastric progenitor cells and massive metaplasia development. Bone marrow transplantation experiments revealed that ASK1 in inflammatory cells is critical for inducing immune disorder and metaplastic changes in epithelium, while ASK1 in epithelial cells regulates cell proliferation in stem/progenitor zone without changes in inflammation and differentiation. These results suggest that H. pylori-induced immune cells may regulate epithelial homeostasis and cell fate as an inflammatory niche via ASK1 signaling.

Inflammation-Associated Senescence Promotes Helicobacter pylori-Induced Atrophic Gastritis

BACKGROUND & AIMS

The association between cellular senescence and Helicobacter pylori-induced atrophic gastritis is not clear. Here, we explore the role of cellular senescence in H pylori-induced atrophic gastritis and the underlying mechanism.

METHODS

C57BL/6J mice were infected with H pylori for biological and mechanistic studies in vivo. Gastric precancerous lesions from patients and mouse models were collected and analyzed using senescence-associated beta-galactosidase, Sudan Black B, and immunohistochemical staining to analyze senescent cells, signaling pathways, and H pylori infection. Chromatin immunoprecipitation, luciferase reporter assays, and other techniques were used to explore the underlying mechanism in vitro.

RESULTS

Gastric mucosa atrophy was highly associated with cellular senescence. H pylori promoted gastric epithelial cell senescence in vitro and in vivo in a manner that depended on C-X-C motif chemokine receptor 2 (CXCR2) signaling. Interestingly, H pylori infection not only up-regulated the expression of CXCR2 ligands, C-X-C motif chemokine ligands 1 and 8, but also transcriptionally up-regulated the expression of CXCR2 via the nuclear factor-κB subunit 1 directly. In addition, CXCR2 formed a positive feedback loop with p53 to continually enhance senescence. Pharmaceutical inhibition of CXCR2 in an H pylori-infected mouse model attenuated mucosal senescence and atrophy, and delayed further precancerous lesion progression.

CONCLUSIONS

Our study showed a new mechanism of H pylori-induced atrophic gastritis through CXCR2-mediated cellular senescence. Inhibition of CXCR2 signaling is suggested as a potential preventive therapy for targeting H pylori-induced atrophic gastritis. GEO data set accession numbers: GSE47797 and GSE3556.

Notch 1 Is Involved in CD4+ T Cell Differentiation Into Th1 Subtype During Helicobacter pylori Infection

Helicobacter pylori infection induces CD4⁺ T differentiation cells into IFN-γ-producing Th1 cells. However, the details of mechanism underlying this process remain unclear. Notch signal pathway has been reported to regulate the differentiation of CD4⁺ T cells into Th1 subtype in many Th1-mediated inflammatory disorders but not yet in H. pylori infection. In the present study, the mRNA expression pattern of CD4⁺ T cells in H. pylori-infected patients differed from that of healthy control using Human Signal Transduction Pathway Finder RT2 Profiler PCR Array, and this alteration was associated with Notch signal pathway, as analyzed by Bioinformation. Quantitative real-time PCR showed that the mRNA expression of Notch1 and its target gene Hes-1 in CD4⁺ T cells of H. pylori-infected individuals increased compared with the healthy controls. In addition, the mRNA expression of Th1 master transcription factor T-bet and Th1 signature cytokine IFN-γ was both upregulated in H. pylori-infected individuals and positively correlated with Notch1 expression. The increased protein level of Notch1 and IFN-γ were also observed in H. pylori-infected individuals confirmed by flow cytometry and ELISA. In vitro, inhibition of Notch signaling decreased the mRNA expression of Notch1, Hes-1, T-bet, and IFN-γ, and reduced the protein levels of Notch1 and IFN-γ and the secretion of IFN-γ in CD4⁺ T cells stimulated by H. pylori. Collectively, this is the first evidence that Notch1 is upregulated and involved in the differentiation of Th1 cells during H. pylori infection, which will facilitate exploiting Notch1 as a therapeutic target for the control of H. pylori infection.

Amplification of transglutaminase 2 enhances tumor-promoting inflammation in gastric cancers

Tumor-promoting inflammation is a hallmark of cancer and is highly associated with tumor progression, angiogenesis, and metastasis. Tumor-associated macrophages (TAMs) are major drivers of tumor-promoting inflammation, but due to the complexity of the tumor microenvironment, the detailed regulatory mechanisms are still under investigation. Here, we investigated a novel role for transglutaminase 2 (TGM2) in the development of tumor-promoting inflammation and recruitment of TAMs to gastric cancer (GC) tissues. When estimated by array comparative genomic hybridization and droplet digital PCR, the copy numbers of the TGM2 gene were amplified in 13.6% (14/103) of GC patients and positively associated with TGM2 expression. Gene set enrichment analysis of expression microarray data for GC samples with high or low TGM2 expression showed that increased TGM2 expression was associated with tumor-promoting inflammation in GC. In addition, the expression of TGM2 was correlated with the expression of markers for macrophages, neutrophils, blood vessels, and lymphatic vessels. Overexpression of TGM2 in GC cells augmented the IL-1β-induced secretion of macrophage-recruiting chemokines and NF-κB activation. TGM2 protein levels were associated with the expression levels of the macrophage marker CD163 in human GC tissue samples. Moreover, GC patients with high expression of TGM2 had a worse prognosis than those with low expression of TGM2. These results suggest TGM2 as a novel regulator of the tumor microenvironment of GC and provide a promising target for constraining tumor-promoting inflammation.

An enzyme linked to harmful inflammation that promotes tumor growth could be a target for stomach cancer treatment. The expression of the enzyme transglutaminase 2 (TGM2) has been shown to increase in several types of cancer, but its precise role has been unclear. Sung-Yup Cho at Seoul National University College of Medicine, Korea and co-workers measured copy numbers and expression levels of TGM2 in gastric cancer cell lines and in tissue samples from patients undergoing gastrectomy. They found that higher levels of TGM2 were closely associated with increases in various genes that promote the recruitment and activity of tumor-associated macrophages, malfunctioning white blood cells that drive tumor-promoting inflammation. In addition, stomach cancer patients with higher expression of TGM2 had poorer prognoses, indicating the potential therapeutic value of targeting this enzyme.

Aim2-mediated/IFN-β-independent regulation of gastric metaplastic lesions via CD8+ T cells

Development of gastric cancer is often preceded by chronic inflammation, but the immune cellular mechanisms underlying this process are unclear. Here we demonstrated that an inflammasome molecule, absent in melanoma 2 (Aim2), was upregulated in patients with gastric cancer and in spasmolytic polypeptide-expressing metaplasia of chronically Helicobacter felis-infected stomachs in mice. However, we found that Aim2 was not necessary for inflammasome function during gastritis. In contrast, Aim2 deficiency led to an increase in gastric CD8+ T cell frequency, which exacerbated metaplasia. These gastric CD8+ T cells from Aim2-/- mice were found to have lost their homing receptor expression (sphingosine-1-phosphate receptor 1 [S1PR1] and CD62L), a feature of tissue-resident memory T cells. The process was not mediated by Aim2-dependent regulation of IFN-β or by dendritic cell-intrinsic Aim2. Rather, Aim2 deficiency contributed to an increased production of CXCL16 by B cells, which could suppress S1PR1 and CD62L in CD8+ T cells. This study describes a potentially novel function of Aim2 that regulates CD8+ T cell infiltration and retention within chronically inflamed solid organ tissue. This function operates independent of the inflammasome, IFN-β, or dendritic cells. We provide evidence that B cells can contribute to this mechanism via CXCL16.

Significance of TC9 and TH9 in Helicobacter pylori-induced gastritis

BACKGROUND

H pylori plays a critical role in the development of stomach cancer, especially in people affected by the bacteria at an early stage of life. Th9 cells and IL-9 play major roles in immune responses against various infections. IL-9 is influential in chronic or acute inflammation of the mucosa.

AIM

This study seeks to investigate the possible functions of Tc9, Th9 cells, and IL-9 level in patients with inflammation due to H pylori infection.

METHODS

Eighty-three patients with dyspepsia symptoms and twenty normal subjects with no sign and symptoms of dyspepsia were recruited. Frequencies of T-cell subsets were determined by flow cytometry. Levels of cytokines IL-9 family in the sera and supernatants of antigen-activated PBMCs patients were measured by ELISA and flow cytometry.

RESULTS

The participants included 56 females and 47 males with a mean age of 39.2 ± 15.3 years. We assigned the infected group into peptic ulcer and gastritis (chronic active and chronic). Frequencies of Tc9, Th17, Tc17, Th17/9, and Tc17/9 increased significantly in the peptic ulcer, chronic active, and chronic gastritis, compared with the uninfected and healthy control groups. A significant increase was seen in IL-9, IL-4, and IL-23 in the chronic active gastritis. Further observed was a significant increase in IL-21 and a decrease in IL-10 in the infected groups.

CONCLUSION

The results revealed that increased Tc9, Th17/9, and Tc17/9 cells appear to be influential in the progression and severity of H pylori infection. Also, increased IL-9 and IL-4 levels and Tc9, Tc17/9, and Th17/9 were seen in chronic active gastritis patients. These findings may provide useful information for a therapeutic targeting of chronic active H pylori infections.

A mass spectrometry guided approach for the identification of novel vaccine candidates in gram-negative pathogens

Vaccination is the most effective method to prevent infectious diseases. However, approaches to identify novel vaccine candidates are commonly laborious and protracted. While surface proteins are suitable vaccine candidates and can elicit antibacterial antibody responses, systematic approaches to define surfomes from gram-negatives have rarely been successful. Here we developed a combined discovery-driven mass spectrometry and computational strategy to identify bacterial vaccine candidates and validate their immunogenicity using a highly prevalent gram-negative pathogen, Helicobacter pylori, as a model organism. We efficiently isolated surface antigens by enzymatic cleavage, with a design of experiment based strategy to experimentally dissect cell surface-exposed from cytosolic proteins. From a total of 1,153 quantified bacterial proteins, we thereby identified 72 surface exposed antigens and further prioritized candidates by computational homology inference within and across species. We next tested candidate-specific immune responses. All candidates were recognized in sera from infected patients, and readily induced antibody responses after vaccination of mice. The candidate jhp_0775 induced specific B and T cell responses and significantly reduced colonization levels in mouse therapeutic vaccination studies. In infected humans, we further show that jhp_0775 is immunogenic and activates IFNγ secretion from peripheral CD4+ and CD8+ T cells. Our strategy provides a generic preclinical screening, selection and validation process for novel vaccine candidates against gram-negative bacteria, which could be employed to other gram-negative pathogens.

Nonhelical Helicobacter pylori Mutants Show Altered Gland Colonization and Elicit Less Gastric Pathology than Helical Bacteria during Chronic Infection

Half of all humans harbor Helicobacter pylori in their stomachs. Helical cell shape is thought to facilitate H. pylori's ability to bore into the protective mucus layer in a corkscrew-like motion, thereby enhancing colonization of the stomach. H. pylori cell shape mutants show impaired colonization of the mouse stomach, highlighting the importance of cell shape in infection. To gain a deeper understanding of how helical cell morphology promotes host colonization by H. pylori, we used three-dimensional confocal microscopy to visualize the clinical isolate PMSS1 and an isogenic straight-rod mutant (Δcsd6) within thick longitudinal mouse stomach sections. We also performed volumetric image analysis to quantify the number of bacteria residing within corpus and antral glands in addition to measuring total CFU. We found that straight rods show attenuation during acute colonization of the stomach (1 day or 1 week postinfection) as measured by total CFU. Our quantitative imaging revealed that wild-type bacteria extensively colonized antral glands at 1 week postinfection, while csd6 mutants showed variable colonization of the antrum at this time point. During chronic infection (1 or 3 months postinfection), total CFU were highly variable but similar for wild-type and straight rods. Both wild-type and straight rods persisted and expanded in corpus glands during chronic infection. However, the straight rods showed reduced inflammation and disease progression. Thus, helical cell shape contributes to tissue interactions that promote inflammation during chronic infection, in addition to facilitating niche acquisition during acute infection.

Aberrant DNA Polymerase Beta Enhances H. pylori Infection Induced Genomic Instability and Gastric Carcinogenesis in Mice

H. pylori is a significant risk factor of gastric cancer that induces chronic inflammation and oxidative DNA damage to promote gastric carcinoma. Base excision repair (BER) is required to maintain the genome integrity and prevent oxidative DNA damage. Mutation in DNA polymerase beta (Pol β) impacts BER efficiency and has been reported in approximately 30-40% of gastric carcinoma tumors. In this study, we examined whether reduced BER capacity associated with mutation in the POLB gene, along with increased DNA damage generated by H. pylori infection, accelerates gastric cancer development. By infecting a Pol β mutant mouse model that lacks dRP lyase with H. pylori, we show that reactive oxygen and nitrogen species (RONS) mediated DNA damage is accumulated in Pol β mutant mice (L22P). In addition, H. pylori infection in Leu22Pro (L22P) mice significantly increases inducible nitric oxide synthesis (iNOS) mediated chronic inflammation. Our data show that L22P mice exhibited accelerated H. pylori induced carcinogenesis and increased tumor incidence. This work shows that Pol β mediated DNA repair under chronic inflammation conditions is an important suppressor of H. pylori induced stomach carcinogenesis.

Bent Bacteria: A Comparison of Cell Shape Mechanisms in Proteobacteria

Helical cell shape appears throughout the bacterial phylogenetic tree. Recent exciting work characterizing cell shape mutants in a number of curved and helical Proteobacteria is beginning to suggest possible mechanisms and provide tools to assess functional significance. We focus here on Caulobacter crescentus, Vibrio cholerae, Helicobacter pylori, and Campylobacter jejuni, organisms from three classes of Proteobacteria that live in diverse environments, from freshwater and saltwater to distinct compartments within the gastrointestinal tract of humans and birds. Comparisons among these bacteria reveal common themes as well as unique solutions to the task of maintaining cell curvature. While motility appears to be influenced in all these bacteria when cell shape is perturbed, consequences on niche colonization are diverse, suggesting the need to consider additional selective pressures.

NLRP3 Controls the Development of Gastrointestinal CD11b+ Dendritic Cells in the Steady State and during Chronic Bacterial Infection

The gastric lamina propria is largely uncharted immunological territory. Here we describe the evolution and composition of the gastric, small intestinal, and colonic lamina propria mononuclear phagocyte system during the steady state and infection with the gastric pathogen Helicobacter pylori. We show that monocytes, CX₃CR1^hi macrophages, and CD11b⁺ dendritic cells are recruited to the infected stomach in a CCR2-dependent manner. All three populations, but not BATF3-dependent CD103⁺ DCs, sample red fluorescent protein (RFP)⁺Helicobacter pylori (H. pylori). Mice reconstituted with human hematopoietic stem cells recapitulate several features of the myeloid cell-H. pylori interaction. The differentiation in and/or recruitment to gastrointestinal, lung, and lymphoid tissues of CD11b⁺ DCs requires NLRP3, but not apoptosis-associated speck-like protein containing a carboxy-terminal CARD (ASC) or caspase-1, during steady-state and chronic infection. NLRP3^-/- mice fail to generate Treg responses to H. pylori and control the infection more effectively than wild-type mice. The results demonstrate a non-canonical inflammasome-independent function of NLRP3 in DC development and immune regulation.

The Sweeping Role of Cholesterol Depletion in the Persistence of Helicobacter pylori Infections

The ability of Helicobacter pylori to persist lifelong in the human gastric mucosa is a striking phenomenon. It is even more surprising since infection is typically associated with a vivid inflammatory response. Recent studies revealed the mechanism by which this pathogen inhibits the epithelial responses to IFN-γ and other central inflammatory cytokines in order to abolish an effective antimicrobial defense. The mechanism is based on the modification and depletion of cholesterol by the pathogen's cholesterol-α-glucosyltransferase. It abrogates the assembly of numerous cytokine receptors due to the reduction of lipid rafts. Particularly, the receptors for IFN-γ, IL-22, and IL-6 then fail to assemble properly and to activate JAK/STAT signaling. Consequently, cholesterol depletion prevents the release of antimicrobial peptides, including the highly effective β-defensin-3. Intriguingly, the inhibition is spatially restricted to heavily infected cells, while the surrounding epithelium continues to respond normally to cytokine stimulation, thus providing a platform of the intense inflammation typically observed in H. pylori infections. It appears that pathogen and host establish a homeostatic balance between tightly colonized and rather inflamed sites. This homeostasis is influenced by the levels of available cholesterol, which potentially exacerbate H. pylori-induced inflammation. The observed blockage of epithelial effector mechanisms by H. pylori constitutes a convincing explanation for the previous failures of T-cell-based vaccination against H. pylori, since infected epithelial cells remain inert upon stimulation by effector cytokines. Moreover, the mechanism provides a rationale for the carcinogenic action of this pathogen in that persistent infection and chronic inflammation represent a pro-carcinogenic environment. Thus, cholesterol-α-glucosyltransferase has been revealed as a central pathogenesis determinant of H. pylori.

Three types of metaplasia model through Kras activation, Pten deletion, or Cdh1 deletion in the gastric epithelium

Chronic inflammation and intestinal metaplasia are strongly associated with gastric carcinogenesis. Kras activation and Pten deletion are observed in intestinal-type gastric cancer, and Cdh1 mutation is associated with diffuse-type gastric cancer. Although various mouse models of gastric carcinogenesis have been reported, few mouse lines enable gene manipulation selectively in the stomach. Here we established a Tff1-Cre bacterial artificial chromosome transgenic mouse line in an attempt to induce gene modification specifically in the gastric pit lineage. In the stomach, Tff1-Cre-mediated recombination was most evident in the pit lineage in the corpus and in entire antral glands; recombination was also observed in a few gastric chief and parietal cells. Outside the stomach, recombination was patchy throughout the intestines, and particularly frequently in the duodenum (Brunner glands), cecum, and proximal colon. In the stomachs of Tff1-Cre;LSL-Kras^G12D mice, proliferating cell clusters expanded throughout the corpus glands, with foveolar cell expansion with ectopic Alcian blue-positive mucins, oxyntic atrophy, and pseudopyloric changes with spasmolytic polypeptide-expressing metaplasia; however, gastric cancer was not observed even at 12 months of age. Corpus-derived organoids from Tff1-Cre;LSL-Kras^G12D mice exhibited accelerated growth and abnormal differentiation with a loss of chief and parietal cell markers. Tff1-Cre;Pten^flox/flox mice displayed similar changes to those seen in Tff1-Cre;LSL-Kras^G12D mice, both with aberrant ERK activation within 3 months. In contrast, Tff1-Cre;Cdh1^flox/flox mice initially showed signet ring-like cells that were rapidly lost with disruption of the mucosal surface, and later developed gastric epithelial shedding with hyperproliferation and loss of normal gastric lineages. Eventually, the glandular epithelium in Tff1-Cre;Cdh1^flox/flox mice was completely replaced by squamous epithelium which expanded from the forestomach. Tff1-Cre mice offer an additional useful tool for studying gastric carcinogenesis both in vivo and in vitro. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Increased risk of non-AIDS-defining cancers in Asian HIV-infected patients: a long-term cohort study

BACKGROUND

Data on the long-term risks of non-AIDS defining cancers (NADCs) are limited, especially in Asians. The incidence of NADCs may correlate with the epidemiological trend of cancers or oncogenic infection in each country, and thus the target cancers would be different between Western and Asian countries. We aimed to elucidate the incidence of NADCs and its predictive factors in Asian HIV-infected patients.

METHODS

Subjects were HIV-infected patients (n = 1001) periodically followed-up for 9 years on average. NADCs were diagnosed by histopathology and/ or imaging findings. Standardized incidence ratios (SIR) were calculated as the ratio of the observed to expected number of NADCs for comparison with an age-and sex-matched general population. Cox's proportional hazards model was used to estimate hazard ratios (HR).

RESULTS

During the median follow-up of 9 years, the 10-year cumulative incidence of NADCs was 6.4%.At NADC diagnosis, half of patients presented at age 40-59 years and with advanced tumor stage. Compared with the age-and sex-matched general population, HIV-infected patients are at increased risk for liver cancer (SIR, 4.7), colon cancer (SIR, 2.1), and stomach cancer (SIR, 1.8). In multivariate analysis, a predictive model for NADCs was developed that included age group (40-49, 50-59, 60-69, and ≥ 70 years), smoker, HIV infection through blood transmission, and injection drug use (IDU), and HBV co-infection. The c-statistic for the NADCs predictive model was 0.8 (95%CI, 0.8-0.9, P < 0.001). The higher 10-year incidence rate of NADCs was associated with increasing prediction score.

CONCLUSIONS

Liver and colon cancer risk was elevated in Asian HIV-infected individuals, similar to in Western populations, whereas stomach cancer risk was characteristically elevated in Asian populations. Half of Asian NADC patients were aged 40-59 years and had advanced-stage disease at diagnosis. Periodic cancer screening may be warranted for high-risk subpopulations with smoking habit, HIV infection through blood transmission or IDU, and HBV co-infection, and screening should be started over 40 years of age.

Eosinophils suppress Th1 responses and restrict bacterially induced gastrointestinal inflammation

Arnold et al. report that eosinophils in the gastrointestinal tract are conditioned by IFN-γ to restrict Th1 responses and promote tissue homeostasis. Eosinophils control Th1 cells in acute and chronic infection and in the steady state and possess bactericidal properties.

Eosinophils are predominantly known for their contribution to allergy. Here, we have examined the function and regulation of gastrointestinal eosinophils in the steady-state and during infection with Helicobacter pylori or Citrobacter rodentium. We find that eosinophils are recruited to sites of infection, directly encounter live bacteria, and activate a signature transcriptional program; this applies also to human gastrointestinal eosinophils in humanized mice. The genetic or anti–IL-5–mediated depletion of eosinophils results in improved control of the infection, increased inflammation, and more pronounced Th1 responses. Eosinophils control Th1 responses via the IFN-γ–dependent up-regulation of PD-L1. Furthermore, we find that the conditional loss of IFN-γR in eosinophils phenocopies the effects of eosinophil depletion. Eosinophils further possess bactericidal properties that require their degranulation and the deployment of extracellular traps. Our results highlight two novel functions of this elusive cell type and link it to gastrointestinal homeostasis and anti-bacterial defense.

The role of T helper 1-cell response in Helicobacter pylori-infection

Helicobacter pylori (H. pylori) is a human pathogen affecting over 50% of the world population. This pathogen is usually associated with chronic inflammation of the gastric mucosa that can lead to peptic ulcer disease (PUD) and gastric cancer (GC), especially in susceptible individuals. These outcomes have been attributed to the interaction of several factors, including host genetic susceptibility, local innate and adaptive immune responses, virulence factors of H. pylori, and environmental factors. T helper (Th) cell subsets and their signature cytokines especially IFN-γ, contribute to anti-bacterial response, but at the mean time sustaining chronic inflammatory responses in the site of infection. It has been acknowledged that H. pylori-infection results in a Th1-dominant response and that inflammation of the gastric mucosa depends mainly on Th1 cell responses. But, the mechanism of the role of Th1 cell responses in H. pylori-infection has not yet been clearly explained. In this review, we will focus on the role of Th1 involved in H. pylori-infection, its interaction with Th17/Treg cells and its association with the clinical consequences of the infection.

Identification of Two Lpp20 CD4+ T Cell Epitopes in Helicobacter pylori-Infected Subjects

Antigen-specific CD4⁺ T cells play an essential role in effective immunity against Helicobacter pylori (H. pylori) infection. Lpp20, a conserved lipoprotein of H. pylori, has been investigated as one of major protective antigens for vaccination strategies. Our previous study identified two H-2^d-restricted CD4⁺ T cell epitopes within Lpp20 and an epitope vaccine based on these epitopes was constructed, which protected mice in prophylactic and therapeutic vaccination against H. pylori infection. Immunodominant CD4⁺ T cell response is an important feature of antiviral, antibacterial, and antitumor cellular immunity. However, while many immunodominant HLA-restricted CD4⁺ T cell epitopes of H. pylori protective antigens have been identified, immunodominant HLA-restricted Lpp20 CD4⁺ T cell epitope has not been elucidated. In this study, a systematic method was used to comprehensively evaluate the immunodominant Lpp20-specific CD4⁺ T cell response in H. pylori-infected patients. Using in vitro recombinant Lpp20 (rLpp20)-specific expanded T cell lines from H. pylori-infected subjects and 27 18mer overlapping synthetic peptides spanned the whole Lpp20 protein, we have shown that L_55-72 and L_79-96 harbored dominant epitopes for CD4⁺ T cell responses. Then the core sequence within these two 18mer dominant epitopes was screened by various extended or truncated 13mer peptides. The immunodominant epitope was mapped to L_57-69 and L_83-95. Various Epstein-Barr virus (EBV) transformed B lymphoblastoid cell lines (B-LCLs) with different HLA alleles were used as antigen presenting cell (APC) to present peptides to CD4⁺ T cells. The restriction molecules were determined by HLA class-antibody blocking. L_57-69 was restricted by DRB1-1501 and L_83-95 by DRB1-1602. The epitopes were recognized on autologous dendritic cells (DCs) loaded with rLpp20 but also those pulsed with whole cell lysates of H. pylori (HP-WCL), suggesting that these epitopes are naturally processed and presented by APC. CD4⁺ T cells were isolated from H. pylori-infected patients and stimulated with L_57-69 and L_83-95. These two epitopes were able to stimulate CD4⁺ T cell proliferation. This study may be of value for the future development of potential H. pylori vaccine.

Helicobacter pylori Depletes Cholesterol in Gastric Glands to Prevent Interferon Gamma Signaling and Escape the Inflammatory Response

BACKGROUND & AIMS

Despite inducing an inflammatory response, Helicobacter pylori can persist in the gastric mucosa for decades. H pylori expression of cholesterol-α-glucosyltransferase (encoded by cgt) is required for gastric colonization and T-cell activation. We investigated how cgt affects gastric epithelial cells and the host immune response.

METHODS

MKN45 gastric epithelial cells, AGS cells, and human primary gastric epithelial cells (obtained from patients undergoing gastrectomy or sleeve resection or gastric antral organoids) were incubated with interferon gamma (IFNG) or interferon beta (IFNB) and exposed to H pylori, including cagPAI and cgt mutant strains. Some cells were incubated with methyl-β-cyclodextrin (to deplete cholesterol from membranes) or myriocin and zaragozic acid to prevent biosynthesis of sphingolipids and cholesterol and analyzed by immunoblot, immunofluorescence, and reverse transcription quantitative polymerase chain reaction analyses. We compared gene expression patterns among primary human gastric cells, uninfected or infected with H pylori P12 wt or P12Δcgt, using microarray analysis. Mice with disruption of the IFNG receptor 1 (Ifngr1-/- mice) and C57BL6 (control) mice were infected with PMSS1 (wild-type) or PMSS1Δcgt H pylori; gastric tissues were collected and analyzed by reverse transcription quantitative polymerase chain reaction or confocal microscopy.

RESULTS

In primary gastric cells and cell lines, infection with H pylori, but not cgt mutants, blocked IFNG-induced signaling via JAK and STAT. Cells infected with H pylori were depleted of cholesterol, which reduced IFNG signaling by disrupting lipid rafts, leading to reduced phosphorylation (activation) of JAK and STAT1. H pylori infection of cells also blocked signaling by IFNB, interleukin 6 (IL6), and IL22 and reduced activation of genes regulated by these signaling pathways, including cytokines that regulate T-cell function (MIG and IP10) and anti-microbial peptides such as human β-defensin 3 (hBD3). We found that this mechanism allows H pylori to persist in proximity to infected cells while inducing inflammation only in the neighboring, non-infected epithelium. Stomach tissues from mice infected with PMSS1 had increased levels of IFNG, but did not express higher levels of interferon-response genes. Expression of the IFNG-response gene IRF1 was substantially higher in PMSS1Δcgt-infected mice than PMSS1-infected mice. Ifngr1-/- mice were colonized by PMSS1 to a greater extent than control mice.

CONCLUSIONS

H pylori expression of cgt reduces cholesterol levels in infected gastric epithelial cells and thereby blocks IFNG signaling, allowing the bacteria to escape the host inflammatory response. These findings provide insight into the mechanisms by which H pylori might promote gastric carcinogenesis (persisting despite constant inflammation) and ineffectiveness of T-cell-based vaccines against H pylori.

Immunodominant antigens that induce Th1 and Th17 responses protect mice against Helicobacter pylori infection

Helicobacter pylori has infected more than half of the world's population, causing gastritis, gastric ulcers, gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer. The oral recombinant Helicobacter pylori vaccine currently used has made great progress in addressing this problem, however, its efficacy and longevity still need to be improved. Th1 and Th17 cells play essential roles in local protection against Helicobacter pylori in the stomach mucosa. Additionally, protective immunodominant antigens are the preferred for a vaccine. In this work, Helicobacter pylori whole cell lysate was separated into 30 groups based on molecular weight by molecular sieve chromatography. The group best promoting CD4 T cells proliferation was selected and evaluated by immunization. The detail proteins were then analyzed by LC-MS/MS and expressed in Escherichia coli. Eleven proteins were selected and the dominant ones were demonstrated. As a result, three protective immunodominant antigens, inosine 5'-monophosphate dehydrogenase, type II citrate synthase, and urease subunit beta, were selected from Helicobacter pylori whole cell. Two of them (inosine 5'-monophosphate dehydrogenase and type II citrate synthase) were newly identified, and one (urease subunit beta) was confirmed as previously reported. The mixture of the three antigens showed satisfactory protective efficiency, with significant lower H. pylori colonization level (P < 0.001) and stronger Th1 (P < 0.001) and Th17 (P < 0.001) responses than PBS control group. Thus, inosine 5'-monophosphate dehydrogenase, type II citrate synthase, and urease subunit beta are three protective antigens inducing dominant Th1 and Th17 responses to defend against Helicobacter pylori infection.

Interleukin-17C in Human Helicobacter pylori Gastritis

The interleukin-17 (IL-17) family of cytokines (IL-17A to IL-17F) is involved in many inflammatory diseases. Although IL-17A is recognized as being involved in the pathophysiology of Helicobacter pylori-associated diseases, the role of other IL-17 cytokine family members remains unclear. Microarray analysis of IL-17 family cytokines was performed in H. pylori-infected and uninfected gastric biopsy specimens. IL-17C mRNA was upregulated approximately 4.5-fold in H. pylori-infected gastric biopsy specimens. This was confirmed by quantitative reverse transcriptase PCR in infected and uninfected gastric mucosa obtained from Bhutan and from the Dominican Republic. Immunohistochemical analysis showed that IL-17C expression in H. pylori-infected gastric biopsy specimens was predominantly localized to epithelial and chromogranin A-positive endocrine cells. IL-17C mRNA levels were also significantly greater among cagA-positive than cagA-negative H. pylori infections (P = 0.012). In vitro studies confirmed an increase in IL-17C mRNA and protein levels in cells infected with cagA-positive infections compared to cells infected with either cagA-negative or cag pathogenicity island (PAI) mutant. Chemical inhibition of IκB kinase (IKK), mitogen-activated protein extracellular signal-regulated kinase (MEK), and Jun N-terminal kinase (JNK) inhibited induction of IL-17C proteins in infected cells, whereas p38 inhibition had no effect on IL-17C protein secretion. In conclusion, H. pylori infection was associated with a significant increase in IL-17C expression in human gastric mucosa. The role of IL-17C in the pathogenesis of H. pylori-induced diseases remains to be determined.