Helicobacter pylori-induced peptic ulcer disease is associated with inadequate regulatory T cell responses

The Human Stomach in Health and Disease: Infection Strategies by Helicobacter pylori

Helicobacter pylori is a bacterial pathogen which commonly colonizes the human gastric mucosa from early childhood and persists throughout life. In the vast majority of cases, the infection is asymptomatic. H. pylori is the leading cause of peptic ulcer disease and gastric cancer, however, and these outcomes occur in 10-15% of those infected. Gastric adenocarcinoma is the third most common cause of cancer-associated death, and peptic ulcer disease is a significant cause of morbidity. Disease risk is related to the interplay of numerous bacterial host and environmental factors, many of which influence chronic inflammation and damage to the gastric mucosa. This chapter summarizes what is known about health and disease in H. pylori infection, and highlights the need for additional research in this area.

Celiac disease and Helicobacter pylori infection in children: Is there any Association?

BACKGROUND AND AIM

Helicobacter pylori (HP) infection can influence the inflammatory and immune responses in the gut and may therefore play a role in the development of gluten-related enteropathy in genetically susceptible individuals. Our objective was to assess the relationship between celiac disease and HP infection in children.

METHODS

Children (1-18 years) diagnosed as celiac disease (CD) (n = 324) with submission of gastric and duodenal biopsies and duodenal histology having Marsh grade III features were eligible for the study. Non-celiac patients referred for endoscopy were selected as controls. We studied proportion of HP prevalence in children with confirmed CD as compared with HP prevalence in reference group comprising non-celiac children referred for endoscopy. We also evaluated predictors of HP infection in children with celiac disease.

RESULTS

Of the 324 participants with CD, gastric HP was seen in 37 (11.4%) patients. The prevalence of HP in patients without CD (50%, P < 0.001) was significantly higher. Among patients with CD, HP infection was most frequent in patients with Marsh IIIa. In the stepwise regression analysis for risk factors of HP infection in CD patients: presence of gastritis, hemoglobin, and absence of scalloping were found to be independent predictors in a multivariate setup.

CONCLUSION

Celiac disease and gastric HP infection have inverse relationship that raises the question whether development of HP infection confers protection against CD.

The Association between Arrhythmia and Helicobacter pylori Infection: A Meta-Analysis of Case-Control Studies

Arrhythmia is a common disease around the world and Helicobacter pylori (H. pylori) is a bacterium infecting 28% to 84% of subjects, depending on the population tested. However, the implication of H. pylori in cardiac arrhythmia is poorly understood. We performed this meta-analysis with an aim to identify the association between arrhythmia and H. pylori. We searched PubMed, Embase, Web of Science, and the Cochrane library databases to select studies on the association between arrhythmia and H. pylori. In the arrhythmia group, 392 (58.1%) were H. pylori-positive and in the control group 640 (47.8%) were H. pylori-positive. Compared to the controls, the infection rate of H. pylori was higher in patients with arrhythmia than in controls (odds ratio (OR) = 1.797, 95% confidence interval (CI): 1.081–2.988, p < 0.05). Subgroup analysis indicated that H. pylori infection was a risk factor for atrial fibrillation in Asia and Africa. Therefore, a correlation between H. pylori infection and arrhythmia may exist and H. pylori eradication may decrease the occurrence of arrhythmia, especially in Asia and Africa.

How host regulation of Helicobacter pylori-induced gastritis protects against peptic ulcer disease and gastric cancer

The bacterial pathogen Helicobacter pylori is the etiological agent of a range of gastrointestinal pathologies including peptic ulcer disease and the major killer, gastric adenocarcinoma. Infection with this bacterium induces a chronic inflammatory response in the gastric mucosa (gastritis). It is this gastritis that, over decades, eventually drives the development of H. pylori-associated disease in some individuals. The majority of studies investigating H. pylori pathogenesis have focused on factors that promote disease development in infected individuals. However, an estimated 85% of those infected with H. pylori remain completely asymptomatic, despite the presence of pathogenic bacteria that drive a chronic gastritis that lasts many decades. This indicates the presence of highly effective regulatory processes in the host that, in most cases, keeps a check on inflammation and protect against disease. In this minireview we discuss such known host factors and how they prevent the development of H. pylori-associated pathologies.

Does the antibody production ability affect the serum anti-Helicobacter pylori IgG titer?

AIM: To investigate the relationship between serum titers of anti-Helicobacter pylori (H. pylori) immunoglobulin G (IgG) and hepatitis B virus surface antibody (HBsAb).

METHODS: Korean adults were included whose samples had positive Giemsa staining on endoscopic biopsy and were studied in the hepatitis B virus surface antigen (HBsAg)/HBsAb serologic assay, pepsinogen (PG) assay, and H. pylori serologic test on the same day. Subjects were excluded if they were positive for HBsAg, had a recent history of medication, or had other medical condition(s). We analyzed the effects of the following factors on serum titers of HBsAb and the anti-H. pylori IgG: Age, density of H. pylori infiltration in biopsy samples, serum concentrations of PG I and PG II, PG I/II ratio, and white blood cell count.

RESULTS: Of 111 included subjects, 74 (66.7%) exhibited a positive HBsAb finding. The serum anti-H. pylori IgG titer did not correlate with the serum HBsAb titer (P = 0.185); however, it correlated with the degree of H. pylori infiltration on gastric biopsy (P < 0.001) and serum PG II concentration (P = 0.042). According to the density of H. pylori infiltration on gastric biopsy, subjects could be subdivided into those with a marked (median: 3.95, range 0.82-4.00) (P = 0.458), moderate (median: 3.37, range 1.86-4.00), and mild H. pylori infiltrations (median: 2.39, range 0.36-4.00) (P < 0.001). Subjects with a marked H. pylori infiltration on gastric biopsy had the highest serological titer, whereas in subjects with moderate and mild H. pylori infiltrations titers were correspondingly lower (P < 0.001). After the successful eradication, significant decreases of the degree of H. pylori infiltration (P < 0.001), serum anti-H. pylori IgG titer (P < 0.001), and serum concentrations of PG I (P = 0.028) and PG II (P = 0.028) were observed.

CONCLUSION: The anti-H. pylori IgG assay can be used to estimate the burden of bacteria in immunocompetent hosts with H. pylori infection, regardless of the HBsAb titer after HBV vaccination.

Helicobacter pylori infection and asthma: Is there a direct or an inverse association? A meta-analysis

AIM: To analyze the consistency of a potential involvement of the bacterium infection in the asthma disease.

METHODS: A systematic literature search of the terms “Helicobacter pylori” (H. pylori) associated to “asthma” using PubMed, Scopus and the Cochrane Library Central was performed. Reference lists from published articles were also employed. Titles of these publications and their abstracts were scanned in order to eliminate duplicates and irrelevant articles. The criteria of inclusion of the studies were: Original studies; the H. pylori diagnostic method has been declared; all ranges of age have been included in our study; a definitive diagnosis of asthma has been reported.

RESULTS: We selected 14 articles in which the association between the two conditions was addressed. In 7 studies the prevalence of H. pylori infection in the asthma population and in the control population was made explicit. There was heterogeneity between the studies (Cohran’s Q = 0.02). The H. pylori infection in the asthma population resulted 33.6% (518 of 1542), while in the control population resulted 37.6% (2746 of 7310) (relative risk of H. pylori infection in the asthma population = 0.87, 95%CI: 0.72-1.05, P = 0.015, random effects model). Instead, considering the more virulent strains, the majority of studies showed an inverse relationship between the prevalence of H. pylori infection and asthma.

CONCLUSION: In our meta-analysis the prevalence of H. pylori infection in the asthma population resulted not statistically significant lower than in control population (P = 0.15). Instead, considering the more virulent strains, the majority of studies showed an inverse relationship between the prevalence of H. pylori infection and asthma.

The Immunomodulator VacA Promotes Immune Tolerance and Persistent Helicobacter pylori Infection through Its Activities on T-Cells and Antigen-Presenting Cells

VacA is a pore-forming toxin that has long been known to induce vacuolization in gastric epithelial cells and to be linked to gastric disorders caused by H. pylori infection. Its role as a major colonization and persistence determinant of H. pylori is less well-understood. The purpose of this review is to discuss the various target cell types of VacA and its mechanism of action; specifically, we focus on the evidence showing that VacA targets myeloid cells and T-cells to directly and indirectly prevent H. pylori-specific T-cell responses and immune control of the infection. In particular, the ability of VacA-proficient H. pylori to skew T-cell responses towards regulatory T-cells and the effects of Tregs on H. pylori chronicity are highlighted. The by-stander effects of VacA-driven immunomodulation on extragastric diseases are discussed as well.

Helicobacter pylori: Does Gastritis Prevent Colitis?

Background

Since its discovery in the early 1980s, Helicobacter pylori has been linked to a variety of gastric and extragastric diseases. Chronic infection with H. pylori causes histologically evident gastritis in all colonized individuals and is the predominant risk factor for gastric and duodenal ulcers as well as gastric adenocarcinoma. However, increasingly robust experimental and epidemiological evidence suggests that H. pylori may at the same time be beneficial to its carriers, as it efficiently prevents allergic disorders and chronic inflammatory conditions. The purpose of this review is to summarize and document the latest evidence for a possible inverse association of H. pylori infection status and the risk of inflammatory bowel disease (IBD), as provided in both experimental and human observational studies. The pathogenesis of IBDs, the available mouse models for these diseases and the dual role of H. pylori in health and disease are presented in dedicated chapters.

Summary and Key Messages

Almost all available epidemiological data suggest that H. pylori infection is inversely associated with both Crohn's disease (CD) and ulcerative colitis in European, Asian as well as American populations; large meta-analyses reviewing 30 original articles or more document that this inverse association is especially strong in CD patients and in children and young adults. Experimental data available from various mouse models of IBD confirm that live H. pylori infection as well as treatment with immunomodulatory molecules of H. pylori reduce clinical and histopathological IBD symptoms. Various proposed mechanisms involving the tolerization of dendritic cells, the production of protective cytokines and the preferential induction and differentiation of regulatory T-cells are presented. The implications of the beneficial aspects of the Helicobacter-host interaction for H. pylori eradication decisions, as well as potential new therapeutic options in the treatment of IBD are discussed in this review.

Impact of Helicobacter pylori on multiple sclerosis-related clinically isolated syndrome

OBJECTIVES

There are no data regarding the relationship between Helicobacter pylori infection (Hp-I) and clinically isolated syndrome (CIS) suggestive of multiple sclerosis. The purpose of this pilot study was to investigate the association between active Hp-I, confirmed by histology, and CIS and to evaluate the impact of Hp eradication on the CIS clinical course.

MATERIAL AND METHODS

We conducted a study on 48 patients with CIS and 20 matched controls. At baseline, apart from histology, serum anti-Hp-specific IgG titer, inflammatory mediators, and HLA-A, HLA-B, HLA-DR genetic polymorphisms were estimated. Hp-positive patients received standard triple eradication regimen, and all patients were followed up for 2 years.

RESULTS

The prevalence of Hp-I was significantly higher in patients with CIS (43/48, 89.6%) than in control (10/20, 50%) (P < 0.001, OR: 8.6, 95% CI: 2.4-30.8). When compared with controls, patients with CIS also showed significantly higher serum anti-Hp IgG titer and HLA-A26, HLA-A30, and HLA-B57 frequencies. Hp-positive patients also showed higher serum concentrations of inflammatory cytokines and homocysteine. At 2-year clinical endpoint, in the subgroup of CIS patients with successful Hp eradication, the number of patients who presented with a second episode was significantly lower accompanied by significant improvement in mean Expanded Disability Status Scale score.

CONCLUSIONS

Hp-I seems more frequent in a Greek CIS cohort and its eradication might delay CIS progression, suggesting a possible link between Hp-I and CIS.

The Gastrointestinal Tract Microbiota and Allergic Diseases

The gastrointestinal (GI) tract microbiota is required for optimal digestion of foods, for the development of resistance against pathogens (termed colonization resistance), for the development of mucosa-associated lymphoid tissue, and for local as well as systemic immune homeostasis. Certain constituents of the GI tract microbiota are widely recognized as critical regulators and modulators of their host's immune response. These include bacterial members of the microbiota as well as parasitic nematodes. Immune regulation by immunomodulatory members of the GI microbiota primarily serves to subvert host antimicrobial immune defenses and promote persistent colonization, but as a side effect may prevent or suppress immunological disorders resulting from inappropriate responses to harmless antigens, such as allergy, colitis or autoimmunity. Many of the best understood GI-resident immunomodulatory species have co-evolved with their mammalian hosts for tens of thousands of years and masterfully manipulate host immune responses. In this review, we discuss the epidemiological evidence for the role of the GI tract microbiota as a whole, and of specific members, in protection against allergic and other immunological disorders. We then focus on the mechanistic basis of microbial immunomodulation, which is presented using several well-understood paradigmatic examples, that is, helminths, Helicobacter pylori, Bifidobacteria and Lactobacilli. In a final chapter, we highlight past and ongoing attempts at harnessing the immunomodulatory properties of GI microbiota species and their secreted products for intervention studies and describe the promises and limitations of these experimental approaches. The effects of pro- and prebiotics, bacterial lysates, as well as of fecal microbiota transplantation are presented and compared.

Helicobacter pylori-Mediated Protection from Allergy Is Associated with IL-10-Secreting Peripheral Blood Regulatory T Cells

Helicobacter pylori infections are usually established in early childhood and continuously stimulate immunity, including T-helper 1 (Th1), Th17, and regulatory T-cell (Treg) responses, throughout life. Although known to be the major cause of peptic ulcer disease and gastric cancer, disease occurs in a minority of those who are infected. Recently, there has been much interest in beneficial effects arising from infection with this pathogen. Published data robustly show that the infection is protective against asthma in mouse models. Epidemiological studies show that H. pylori is inversely associated with human allergy and asthma, but there is a paucity of mechanistic data to explain this. Since Th1 and Treg responses are reported to protect against allergic responses, we investigated if there were links between the human systemic Th1 and Treg response to H. pylori and allergen-specific IgE levels. The human cytokine and T-cell responses were examined using peripheral blood mononuclear cells (PBMCs) from 49 infected and 58 uninfected adult patients. Concentrations of total and allergen-specific plasma IgE were determined by ELISA and ImmunoCAP assays. These responses were analyzed according to major virulence factor genotypes of the patients' colonizing H. pylori strains. An in vitro assay was employed, using PBMCs from infected and uninfected donors, to determine the role of Treg cytokines in the suppression of IgE. Significantly higher frequencies of IL-10-secreting CD4(+)CD25(hi) Tregs, but not H. pylori-specific Th1 cells, were present in the peripheral blood of infected patients. Total and allergen-specific IgE concentrations were lower when there was a strong Treg response, and blocking IL-10 in vitro dramatically restored IgE responses. IgE concentrations were also significantly lower when patients were infected with CagA(+) strains or those expressing the more active i1 form of VacA. The systemic IL-10(+) Treg response is therefore likely to play a role in H. pylori-mediated protection against allergy in humans.

Gastric Helicobacter pylori Infection Affects Local and Distant Microbial Populations and Host Responses

Helicobacter pylori is a late-in-life human pathogen with potential early-life benefits. Although H. pylori is disappearing from the human population, little is known about the influence of H. pylori on the host's microbiota and immunity. Studying the interactions of H. pylori with murine hosts over 6 months, we found stable colonization accompanied by gastric histologic and antibody responses. Analysis of gastric and pulmonary tissues revealed increased expression of multiple immune response genes, conserved across mice and over time in the stomach and more transiently in the lungs. Moreover, H. pylori infection led to significantly different population structures in both the gastric and intestinal microbiota. These studies indicate that H. pylori influences the microbiota and host immune responses not only locally in the stomach, but distantly as well, affecting important target organs.

Systems-wide analyses of mucosal immune responses to Helicobacter pylori at the interface between pathogenicity and symbiosis

Helicobacter pylori is the dominant member of the gastric microbiota in over half of the human population of which 5-15% develop gastritis or gastric malignancies. Immune responses to H. pylori are characterized by mixed T helper cell, cytotoxic T cell and NK cell responses. The presence of Tregs is essential for the control of gastritis and together with regulatory CX3CR1+ mononuclear phagocytes and immune-evasion strategies they enable life-long persistence of H. pylori. This H. pylori-induced regulatory environment might contribute to its cross-protective effect in inflammatory bowel disease and obesity. Here we review host-microbe interactions, the development of pro- and anti-inflammatory immune responses and how the latter contribute to H. pylori's role as beneficial member of the gut microbiota. Furthermore, we present the integration of existing and new data into a computational/mathematical model and its use for the investigation of immunological mechanisms underlying initiation, progression and outcomes of H. pylori infection.

Association of Hay Fever with the Failure of Helicobacter pylori Primary Eradication

Objective Recently, the number of patients receiving Helicobacter pylori eradication treatment has dramatically increased in Japan, although the eradication rate has gradually decreased. Patient characteristics could affect the eradication rate. Our aim in this study was to investigate the association between failed first-line eradication therapy and hay fever. Methods We researched 356 patients who visited a pharmacy adjacent to the Internal Medicine clinic with a prescription for first-line H. pylori eradication treatment and investigated whether the patients had hay fever using a questionnaire. We separated these patients into 2 groups based on the success or failure of eradication according to the clinical data and performed a logistic regression analysis to investigate the influence of hay fever on first-line eradication failure. Results The eradication rate of patients with and without hay fever was 65.6% and 77.7%, respectively. The adjusted odds ratios according to which patients with hay fever would fail eradication therapy gradually lowered with increasing patient age [≤50 years, odds ratio (OR) 6.81, p=0.089; 51-60 years, OR 2.75, p=0.145; 61-70 years, OR 1.60, p=0.391; >70 years, OR 1.02, p=0.979]. A significant relationship was found for all patients (OR 1.88, p=0.047) and the age group ≤70 years (OR 2.31, p=0.024). Conclusion Patients with hay fever have difficulty with first-line eradication, especially younger patients. The existence of clarithromycin-resistant bacteria is suspected, and other factors may also be involved. When a hay fever sufferer receives first-line treatment, eradication might be difficult and other treatment may be required.

Differential inflammatory response to Helicobacter pylori infection: etiology and clinical outcomes

The bacterial pathogen Helicobacter pylori commonly colonizes the human gastric mucosa during early childhood and persists throughout life. The organism has evolved multiple mechanisms for evading clearance by the immune system and, despite inducing inflammation in the stomach, the majority of infections are asymptomatic. H. pylori is the leading cause of peptic ulcer disease and gastric cancer. However, disease outcomes are related to the pattern and severity of chronic inflammation in the gastric mucosa, which in turn is influenced by both bacterial and host factors. Despite over 2 decades of intensive research, there remains an incomplete understanding of the circumstances leading to disease development, due to the fascinating complexity of the host-pathogen interactions. There is accumulating data concerning the virulence factors associated with increased risk of disease, and the majority of these have pro-inflammatory activities. Despite this, only a small proportion of those infected with virulent strains develop disease. Several H. pylori virulence factors have multiple effects on different cell types, including the induction of pro- and anti-inflammatory, immune stimulatory, and immune modulatory responses. The expression of multiple virulence factors is also often linked, making it difficult to assess the meaning of their effects in isolation. Overall, H. pylori is thought to usually modulate inflammation and limit acute damage to the mucosa, enabling the bacteria to persist. If this delicate balance is disturbed, disease may then develop.

Helicobacter urease-induced activation of the TLR2/NLRP3/IL-18 axis protects against asthma

Inflammasome activation and caspase-1-dependent (CASP1-dependent) processing and secretion of IL-1β and IL-18 are critical events at the interface of the bacterial pathogen Helicobacter pylori with its host. Whereas IL-1β promotes Th1 and Th17 responses and gastric immunopathology, IL-18 is required for Treg differentiation, H. pylori persistence, and protection against allergic asthma, which is a hallmark of H. pylori-infected mice and humans. Here, we show that inflammasome activation in DCs requires the cytoplasmic sensor NLRP3 as well as induction of TLR2 signaling by H. pylori. Screening of an H. pylori transposon mutant library revealed that pro-IL-1β expression is induced by LPS from H. pylori, while the urease B subunit (UreB) is required for NLRP3 inflammasome licensing. UreB activates the TLR2-dependent expression of NLRP3, which represents a rate-limiting step in NLRP3 inflammasome assembly. ureB-deficient H. pylori mutants were defective for CASP1 activation in murine bone marrow-derived DCs, splenic DCs, and human blood-derived DCs. Despite colonizing the murine stomach, ureB mutants failed to induce IL-1β and IL-18 secretion and to promote Treg responses. Unlike WT H. pylori, ureB mutants were incapable of conferring protection against allergen-induced asthma in murine models. Together, these results indicate that the TLR2/NLRP3/CASP1/IL-18 axis is critical to H. pylori-specific immune regulation.

Evaluation of CD4(+)CD25(+)FoxP3(+) T cell populations, IL-10 production, and their correlation with clinical and biochemical parameters in sickle cell anemia patients with leg ulcers

Leg ulcers (LUs) are a debilitating complication of sickle cell anemia (SCA), with inflammation known to play a crucial role in their pathogenesis. Many studies have described the roles of T helper type 1 (Th1) and Th2 pathways in SCA; however, defects in anti-inflammatory responses are poorly understood. We evaluated interleukin (IL)-10 levels in serum and peripheral blood mononuclear cells (PBMCs) in SCA patients with leg ulcers (SCALU) and without leg ulcers (SCAWH) in addition to CD4(+) CD25(+)FoxP3(+) T cell populations and their its IL-10 expression. In stimulated and unstimulated PBMC cultures, SCALU patients produced higher levels of IL-10 than those in the SCAWH group. Higher levels of IL-10 in SCALU patients correlated with a history of osteonecrosis in stimulated and unstimulated cultures when compared with those in SCAWH. Immunophenotyping revealed that SCALU patients had a higher proportion of CD4(+)CD25(+)FoxP3(+), Tr1 and CD4(+)CD25(+)FoxP3(+)IL-10(+) T cells than other groups. Our findings revealed that IL-10 levels were increased in unstimulated cells from the SCALU group, and that this group also presented with a predominant CD4(+) CD25(+)FoxP3(+) cell population despite many of those cells being IL-10 negative.

Epinecidin-1 antimicrobial activity: In vitro membrane lysis and In vivo efficacy against Helicobacter pylori infection in a mouse model

Helicobacter pylori (H. pylori) infection is highly prevalent, and has a strong association with various gastric diseases, including gastritis, digestive ulcers, and cancer. H. pylori strains with resistance to existing antibiotics have emerged in the past two decades. Currently, treatment of H. pylori infection (involving the use of proton pump inhibitors, followed by triple therapy with broad-spectrum antibiotics) is suboptimal, with high failure rates. As such, there is a clear need for new approaches against H. pylori. Here, we report that Epinecidin-1 (Epi-1) shows effective bactericidal activity against H. Pylori in vitro, and modulates H. Pylori-induced host immune responses in a mouse model. Epi-1 exhibited a low minimum inhibitory concentration (MIC) against antibiotic-sensitive and clinical antibiotic-resistant strains. Moreover, Epi-1 treatment caused 1-N-phenylnaphthylamine (NPN)-fluorescent probe uptake, suggesting it induced membrane lysis; transmission electron micrographs revealed that membranes were destabilized by the generation of saddle-splay membrane curvature. Oral administration of Epi-1 (quaque die dose) in a mouse infection model had strong efficacy (p < 0.00152) against H. pylori, as compared with conventional proton pump inhibitor (PPI)-triple therapeutic antibiotics. Epi-1 inhibited infection through in vivo depletion of CD4+-FOXP3+ T Regulatory and Th17 subset populations, and aided in clearance of persistent H. pylori colonization. Flow cytometry and gene expression analysis of mouse splenic and gastric tissue indicated that Epi-1 inhibits IL-10, and thereby affects FOXP3 expression levels and reduces pro-inflammatory cytokine responses. Crucially, high doses of Epi-1 did not exert toxic effects in oral, dermal, and eye irritation models. Collectively, our results suggest that Epi-1 may be a promising, effective, and safe monotherapeutic agent for the treatment of multi-drug resistant H. pylori infection.

Human gastric epithelial cells contribute to gastric immune regulation by providing retinoic acid to dendritic cells

Despite the high prevalence of chronic gastritis caused by Helicobacter pylori, the gastric mucosa has received little investigative attention as a unique immune environment. Here, we analyzed whether retinoic acid (RA), an important homeostatic factor in the small intestinal mucosa, also contributes to gastric immune regulation. We report that human gastric tissue contains high levels of the RA precursor molecule retinol (ROL), and that gastric epithelial cells express both RA biosynthesis genes and RA response genes, indicative of active RA biosynthesis. Moreover, primary gastric epithelial cells cultured in the presence of ROL synthesized RA in vitro and induced RA biosynthesis in co-cultured monocytes through an RA-dependent mechanism, suggesting that gastric epithelial cells may also confer the ability to generate RA on gastric dendritic cells (DCs). Indeed, DCs purified from gastric mucosa had similar levels of aldehyde dehydrogenase activity and RA biosynthesis gene expression as small intestinal DCs, although gastric DCs lacked CD103. In H. pylori-infected gastric mucosa, gastric RA biosynthesis gene expression was severely disrupted, which may lead to reduced RA signaling and thus contribute to disease progression. Collectively, our results support a critical role for RA in human gastric immune regulation.

Helicobacter pylori-Mediated Protection against Extra-Gastric Immune and Inflammatory Disorders: The Evidence and Controversies

A large number of studies link H. pylori infection with a reduced risk of developing extra-gastric conditions such as allergy, asthma, inflammatory bowel disease, coeliac disease and multiple sclerosis. The strength of the evidence for these protective associations is quite variable, and published studies often do not agree. This review article discusses some of the reasons for these discrepancies, and the difficulties faced when designing studies. Examples of some protective disease associations are described in detail, where the evidence is most abundant and thought to be more reliable. The most convincing of these are supported by published mechanistic data, for example with animal models, or incidence of disease exacerbation in humans following H. pylori eradication. Although controversial, this field is very important as the prevalence of H. pylori is decreasing throughout the world whilst many chronic diseases are becoming more common. These trends are likely to continue in the future, therefore it is important that we fully understand if and how H. pylori confers protection.

Prevalence of serum celiac antibodies in a multiracial Asian population--a first study in the young Asian adult population of Malaysia

Background

Celiac disease (CD) is an immune-mediated disorder induced by the ingestion of gluten in genetically susceptible persons. The prevalence of CD in Malaysia is unknown. We aim to determine the seroprevalence of CD antibodies and also investigate the correlation between H. pylori infection and CD in the young and healthy multiracial Malaysian population.

Methods

Healthy young adult volunteers between the ages of 18–30 years were consecutively recruited from June 2012 to May 2014 at the University of Malaya Medical Centre (UMMC), Kuala Lumpur. Serum samples from all the participants were tested for anti-gliadin antibody immunoglobulin A/immunoglobulin G (IgA/IgG) and anti-tissue transglutaminase antibody (tTG) IgA/IgG. Samples positive for both anti-gliadin and anti-tTG were further validated for anti-human endomysial IgA antibodies (EmA). Serological diagnosis of CD was made when anti-gliadin, anti-tTG and anti-EmA were positive.

Results

562 qualified participants with mean age 24 ± 2.4 years old were recruited into our study. CD was found in 7 participants where most of them were asymptomatic and unaware of their CD status. The median of anti-gliadin and anti-tTG IgA/IgG value was 38.2 U/ml (interquartile range, 28.3–60.4 U/ml) and 49.2 U/ml (interquartile range, 41.1–65.9 U/ml), respectively. Seroprevalence of CD antibodies was 1.9% (6 out of 324) in female while only 0.4% (1 out of 238) in male. Seroprevalence among Malay was 0.8% (2 of 236), Chinese was 1.7% (3 of 177) and Indian was 1.3% (2 of 149). Overall, seroprevalence of CD antibodies in healthy asymptomatic adults in the Malaysian population was 1.25% (95% CI, 0.78%-1.72%). No significant relationship was discovered between CD and H. pylori infection.

Conclusions

The seroprevalence of CD antibodies in healthy young adults in the Malaysian population was 1.25% (1 in 100). CD is underdiagnosed and it could be a much greater problem in Malaysia than previously thought.

Helicobacter pylori infection reduces disease severity in an experimental model of multiple sclerosis

Recent research has demonstrated that infection with the bacterial pathogen Helicobacter pylori is less common amongst patients with multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS). We aimed to compare the prevalence of H. pylori amongst MS patients and healthy controls, and also investigated the impact of this infection on an animal model for MS, experimental autoimmune encephalomyelitis (EAE). The H. pylori status of 71 MS patients and 42 healthy controls was determined by serology. Groups of C57BL/6 mice were infected with H. pylori, or given diluent alone as a placebo, prior to inducing EAE. Clinical scores were assessed for all mice, and spleens and spinal cord tissue were harvested. CD4⁺ T cell subsets were quantified by flow cytometry, and T cell proliferation assays were performed. In MS patients the seroprevalence of H. pylori was half that of healthy controls (p = 0.018). Over three independent experiments, prior H. pylori infection had a moderate effect in reducing the severity of EAE (p = 0.012). In line with this, the antigen-specific T cell proliferative responses of infected animals were significantly reduced (p = 0.001), and there was a fourfold reduction in the number of CD4⁺ cells in the CNS. CD4⁺ populations in both the CNS and the spleens of infected mice also contained greatly reduced proportions of IFNγ⁺, IL-17⁺, T-bet⁺, and RORγt⁺ cells, but the proportions of Foxp3⁺ cells were equivalent. There were no differences in the frequency of splenic CD4⁺cells expressing markers of apoptosis between infected and uninfected animals. H. pylori was less prevalent amongst MS patients. In mice, the infection exerted some protection against EAE, inhibiting both Th1 and Th17 responses. This could not be explained by the presence of increased numbers of Foxp3⁺ regulatory T cells, or T cell apoptosis. This is the first direct experimental evidence showing that H. pylori may provide protection against inflammatory demyelination in the CNS.

Helicobacter pylori infection in patients with selective immunoglobulin E deficiency

AIM: To investigate the prevalence and clinical characteristics of Helicobacter pylori (H. pylori)-infected dyspeptic patients with selective immunoglobulin E deficiency (IgEd).

METHODS: All individuals who underwent serum total immunoglobulin E (IgE) measurement at the Leumit Healthcare Services (Israel) in 2012 were identified in an electronic database search (n = 18487). From these, selected case group subjects were ≥ 12 years of age and had serum total IgE < 2 kIU/L (n = 158). The control group was selected from a random sampling of the remaining subjects ≥ 12 years of age to obtain a case-control ratio of 1:20 (n = 3160). Dyspeptic diseases, diagnosed no more than 5 years before serum total IgE testing, were identified and retrieved from the electronic database using specific International Classification of Diseases diagnostic codes. Results of C¹³-urea breath tests were used to identify subjects infected with H. pylori. Categorical variables between case and control subjects were analyzed using Fisher’s exact tests, whereas continuous variables were analyzed using χ² tests.

RESULTS: Dyspepsia was present in 27.2% (43/158) of case subjects and 22.7% (718/3160) of controls. Of these, significantly more case subjects (32/43, 74.4%) than controls (223/718, 31.1%) were positive for H. pylori (P < 0.01). Esophagogastroduodenoscopy was performed in 19 case and 94 control subjects, revealing that gastritis was more prevalent in IgEd case subjects than in controls (57.9% vs 29.8%, P < 0.05). Furthermore, a significantly greater proportion of case subjects presented with peptic duodenal ulcers (63.2% vs 15.9%, P < 0.01). Histopathologic examination showed marked chronic inflammation, lymphoid follicle formation and prominent germinal centers, with polymorphonuclear cell infiltration of gastric glands, that was similar in case and control biopsy tissues. Finally, IgEd case subjects that underwent esophagogastroduodenoscopy were more likely to exhibit treatment-refractory H. pylori infections that require second-line triple antibiotic therapy (47.4% vs 11.7%, P < 0.01).

CONCLUSION: IgEd is associated with higher rates of H. pylori-associated gastritis and peptic duodenal ulcers.

Exposure to Helicobacter pylori infection in early childhood and the risk of allergic disease and atopic sensitization: a longitudinal birth cohort study

Background

An inverse relation between Helicobacter pylori infection and allergic disease has been reported by a range of independent epidemiological studies, but evidence from longitudinal studies is scarce.

Objective

We have investigated the effects of H. pylori infection on the incidence and prevalence of allergic diseases and sensitization in a low-income birth cohort.

Methods

In 2005/2006, a population-based birth cohort was established in Butajira, Ethiopia, and the 1006 singleton babies born were followed up at ages 1, 3, and 5. Symptoms of allergic disease were collected using the ISAAC questionnaire, allergen skin tests performed, and stool samples analysed for H. pylori antigen and geohelminths. Multiple logistic regression was used to determine the independent effects of H. pylori measured at age 3 on the incidence of each outcome between ages 3 and 5 years (in those without the outcome at age 3), controlling for potential confounders, and to additionally assess cross-sectional associations.

Results

A total of 863 children were followed up to age 5. H. pylori infection was found in 25% of the children at both ages 3 and 5, in 21% at age 5 but not 3, and in 17% at age 3 but not at age 5. H. pylori infection at age 3 was significantly associated with a decreased risk of incident eczema between ages 3 and 5 (adjusted OR, 95% CI, 0.31; 0.10–0.94, P = 0.02). Cross-sectionally at age 5, H. pylori infection was inversely associated with skin sensitization (adjusted OR, 95% CI, 0.26; 0.07–0.92, P = 0.02).

Conclusion and clinical relevance

These findings provide further evidence to suggest that early-life exposure to H. pylori may play a protective role in the development of allergy.

Susceptibility to pediatric Helicobacter pylori infection correlates with the host responses of regulatory and effector T cells

BACKGROUND

Tolerance to the early acquisition of Helicobacter pylori is suggested because of a biased ratio of regulatory to effector T cells in a mice model. This study investigated whether the CD4CD25 regulatory T (Treg) and CD4+CD25- effector T (Teff) cell responses after H. pylori exposure determine H. pylori susceptibility in children.

METHODS

Treg and Teff cells from peripheral blood mononuclear cells (PBMCs) of H. pylori-infected and non-infected children were incubated with H. pylori protein. The cytokine levels and fraction of FOXP3+ to T cells were measured. FOXP3 expression was assessed by Western blotting and immunohistochemistry of gastric biopsies from dyspeptic children.

RESULTS

The fraction of FOXP3+ to CD4+CD25 high cells in PBMCs, FOXP3-positive staining and translation level in gastric tissues were higher in H. pylori-infected children than in controls (P < 0.05). The translation levels of TGF-β1 in gastric tissues were higher in H. pylori-infected children than in controls (P < 0.05). After H. pylori challenge, H. pylori-infected children had a positive net-change in TGF-β1 from Treg cells, and a negative net-change of IFN-γ from Teff cells. Paradoxically, the non-infected controls had a negative net-change in TGF-β1 from Treg cells, and a positive net-change of IFN-γ from Teff cells.

CONCLUSIONS

The host response of Treg cells with increases in FOXP3 and TGF-β1 combined with a reduction in IFN-γ by Teff cells may contribute to H. pylori susceptibility in children.

The impact of proton pump inhibitors on the human gastrointestinal microbiome

Potent gastric acid suppression using proton pump inhibitors (PPIs) is common in clinical practice but may have important effects on human health that are mediated through changes in the gastrointestinal microbiome. In the esophagus, PPIs change the normal bacterial milieu to decrease distal esophageal exposure to inflammatory gram-negative bacteria. In the stomach, PPIs alter the abundance and location of gastric Helicobacter pylori and other bacteria. In the small bowel, PPIs cause polymicrobial small bowel bacterial overgrowth and have been associated with the diagnosis of celiac disease. In the colon, PPIs associate with incident but not recurrent Clostridium difficile infection.

Peptic ulcer disease in Helicobacter pylori-infected children: clinical findings and mucosal immune response

OBJECTIVES

Peptic ulcer disease (PUD) is highly prevalent among adults but less common in children. Helicobacter pylori infection, the main cause of PUD, is, however, acquired extremely early in life. The aim of the study was to analyze clinical characteristics of children with PUD in a country with a high prevalence of the disease and to evaluate which host factors could determine this clinical outcome.

METHODS

Children referred for upper gastrointestinal (GI) endoscopy with suspicion of peptic diseases were included prospectively during an 8-year period. Antral biopsies were performed to determine H pylori presence and mucosal cytokines profile.

RESULTS

A total of 307 children between 3 and 18 years old were enrolled. Of the total, 237 children (46% boys) with complete data were included. H pylori infection was confirmed in 133 (56.1%) participants. Duodenal ulcer (DU) was diagnosed in 32 patients (13.5%); among them 29 were infected with H pylori (90.6%). Infected children had a nodular appearance of the gastric mucosa more often than noninfected children. Noninfected children had fewer lymphoid follicles and less inflammatory infiltrate than infected children. Only mucosal polymorphonuclear cell infiltration was more intense in DU-infected children as compared with non-DU-infected children. DU-infected children had higher levels of mucosal interferon-γ than noninfected and non-DU-infected patients. Non-DU-infected children had also higher levels of mucosal interleukin-10 than noninfected patients (P < 0.05).

CONCLUSIONS

PUD in children, especially DU, is strongly associated with H pylori infection in developing countries. There is no distinctive clinical presentation of children with PUD. T-helper cytokine balance may influence clinical outcomes in children.

Crosstalks between cytokines and Sonic Hedgehog in Helicobacter pylori infection: a mathematical model

Helicobacter pylori infection of gastric tissue results in an immune response dominated by Th1 cytokines and has also been linked with dysregulation of Sonic Hedgehog (SHH) signaling pathway in gastric tissue. However, since interactions between the cytokines and SHH during H. pylori infection are not well understood, any mechanistic understanding achieved through interpretation of the statistical analysis of experimental results in the context of currently known circuit must be carefully scrutinized. Here, we use mathematical modeling aided by restraints of experimental data to evaluate the consistency between experimental results and temporal behavior of H. pylori activated cytokine circuit model. Statistical analysis of qPCR data from uninfected and H. pylori infected wild-type and parietal cell-specific SHH knockout (PC-SHH^KO) mice for day 7 and 180 indicate significant changes that suggest role of SHH in cytokine regulation. The experimentally observed changes are further investigated using a mathematical model that examines dynamic crosstalks among pro-inflammatory (IL1β, IL-12, IFNγ, MIP-2) cytokines, anti-inflammatory (IL-10) cytokines and SHH during H. pylori infection. Response analysis of the resulting model demonstrates that circuitry, as currently known, is inadequate for explaining of the experimental observations; suggesting the need for additional specific regulatory interactions. A key advantage of a computational model is the ability to propose putative circuit models for in-silico experimentation. We use this approach to propose a parsimonious model that incorporates crosstalks between NFĸB, SHH, IL-1β and IL-10, resulting in a feedback loop capable of exhibiting cyclic behavior. Separately, we show that analysis of an independent time-series GEO microarray data for IL-1β, IFNγ and IL-10 in mock and H. pylori infected mice further supports the proposed hypothesis that these cytokines may follow a cyclic trend. Predictions from the in-silico model provide useful insights for generating new hypothesis and design of subsequent experimental studies.

Role of Tregs in Helicobacter pylori infection

AIM: To investigate the role of Foxp3⁺ regulatory T cells (Tregs) in Helicobacter pylori (H. pylori) infection.

METHODS: By using biopsies from 89 H. pylori-positive patients, 60 of whom underwent treatment for eradication of H. pylori, and 79 H. pylori-negative adults, immunohistochemistry was performed to semi-quantify the number of Tregs in the gastric mucosa.

RESULTS: The proportion of Tregs was 2.4% in H. pylori-negative individuals, and 8.9% in H. pylori-positive patients (P < 0.01). After eradication of H. pylori, the proportion of Tregs significantly declined (3.0%, P < 0.01).

CONCLUSION: Tregs actively participate in the immune response to H. pylori infection. H. pylori chronically colonizes the stomach and increases the frequency of Tregs in the gastric mucosa, thereby suppressing the immune response and contributing to the persistence of H. pylori infection. Tregs decrease in the gastric mucosa after eradication of H. pylori, and mucosal immune balance is then restored.

CCL20/CCR6-mediated migration of regulatory T cells to the Helicobacter pylori-infected human gastric mucosa

BACKGROUND

Helicobacter pylori-induced peptic ulceration is less likely to occur in patients with a strong gastric anti-inflammatory regulatory T cell (Treg) response. Migration of Tregs into the gastric mucosa is therefore important.

OBJECTIVE

To identify the homing receptors involved in directing Tregs to the gastric mucosa, and investigate how H pylori stimulates the relevant chemokine responses.

DESIGN

Gastric biopsy samples and peripheral blood were donated by 84 H pylori-infected and 46 uninfected patients. Luminex assays quantified gastric biopsy chemokine concentrations. Flow cytometry was used to characterise homing receptors on CD4(+)CD25(hi) Tregs. H pylori wild-type and isogenic mutants were used to investigate the signalling mechanisms behind CCL20 and IL-8 induction in gastric epithelial cell lines. Transwell assays were used to quantify Treg migration towards chemokines in vitro.

RESULTS

CCL20, CXCL1-3 and IL-8 concentrations were significantly increased in gastric biopsy samples from H pylori-infected patients. CCR6 (CCL20 receptor), CXCR1 and CXCR2 (IL-8 and CXCL1-3 receptors) were expressed by a higher proportion of peripheral blood Tregs in infected patients. Most gastric Tregs expressed these receptors. H pylori induced CCL20 production by gastric epithelial cells via cag pathogenicity island (cagPAI)-dependent NF-κB signalling. Foxp3(+), but not Foxp3(-), CD4 cells from infected mice migrated towards recombinant CCL20 in vitro.

CONCLUSIONS

As well as increasing Treg numbers, H pylori infection induces a change in their characteristics. Expression of CCR6, CXCR1 and CXCR2 probably enables their migration towards CCL20 and IL-8 in the infected gastric mucosa. Such qualitative changes may also explain how H pylori protects against some extragastric inflammatory disorders.

An Update on Helicobacter pylori as the Cause of Gastric Cancer

BACKGROUND

Gastric cancer is the second most common cause of cancer deaths worldwide. The vast majority of gastric cancers are inflammation-related cancers caused by infection with Helicobacter pylori. H. pylori-induced oxidative stress damages DNA, resulting in genetic instability. In addition, H. pylori itself can cause DNA damage and epigenetic changes that trigger genetic instability and neoplastic transformation.

SUMMARY

H. pylori strain-specific components act in combination with host factors and environmental and dietary factors to greatly enhance the inflammatory response and thus the cancer risk. Variations in several key factors, such as the cag pathogenicity island and the VacA protein, can trigger a greater inflammatory response in host cells. Genetic polymorphisms in the host such as in the IL-1β gene, and chromosomes 9p21.3 and 10q23 also play a contributing role. Finally, diet is a major external factor that modulates the risk of gastric cancer.

KEY MESSAGE

The majority of gastric cancers are inflammation-related cancers caused by infection with H. pylori. Eradication of H. pylori is important for the prevention and treatment of gastric cancer.

PRACTICAL IMPLICATIONS

H. pylori eradication results in healing of gastritis and prevention of further H. pylori-induced genetic damage. Eradication of H. pylori prior to development of atrophic gastritis can prevent the development of gastric cancer. Japan has undertaken a nationwide program to identify and eliminate H. pylori, along with surveillance for those who underwent H. pylori eradication too late to eliminate cancer risk. Population-wide eradication of H. pylori will result in gastric cancer becoming a vanishingly rare disease.

At the Bench: Helicobacter pylori, dysregulated host responses, DNA damage, and gastric cancer

Helicobacter pylori infection is the strongest known risk factor for the development of gastric cancer. Given that ∼50% of the global population is infected with this pathogen, there is great impetus to elucidate underlying causes that mediate progression from infection to cancer. Recent evidence suggests that H. pylori-induced chronic inflammation and oxidative stress create an environment conducive to DNA damage and tissue injury. DNA damage leads to genetic instability and eventually, neoplastic transformation. Pathogen-encoded virulence factors induce a robust but futile immune response and alter host pathways that lower the threshold for carcinogenesis, including DNA damage repair, polyamine synthesis and catabolism, antioxidant responses, and cytokine production. Collectively, such dysregulation creates a protumorigenic microenvironment within the stomach. This review seeks to address each of these aspects of H. pylori infection and to call attention to areas of particular interest within this field of research. This review also seeks to prioritize areas of translational research related to H. pylori-induced gastric cancer based on insights garnered from basic research in this field. See related review by Dalal and Moss, At the Bedside: H. pylori, dysregulated host responses, DNA damage, and gastric cancer.

Helicobacter pylori and gastric cancer

Infection with Helicobacter pylori is established as the major risk factor for gastric cancer development. Damage of the mucosal barrier due to H. pylori-induced inflammation enhances the carcinogenic effect of other risk factors such as salt intake or tobacco smoking. The genetic disposition of both the bacterial strain and the host can increase the potential towards gastric cancer formation. Genetic variance of the bacterial proteins CagA and VacA is associated with a higher gastric cancer risk, as are polymorphisms and epigenetic changes in host gene coding for interleukins (IL1β, IL8), transcription factors (CDX2, RUNX3) and DNA repair enzymes. Application of high-throughput assays for genome-wide assessment of either genetic structural variance or gene expression patterns may lead to a better understanding of the pathobiological background of these processes, including the underlying signaling pathways. Understanding of the stepwise alterations that take place in the transition from chronic atrophic gastritis, via metaplastic changes, to invasive neoplasia is vital to define the 'point of no return' before which eradication of H. pylori has the potential to prevent gastric cancer. Currently, eradication as preventive strategy is only recommended for high-incidence regions in Asia; large population studies with an adequate follow-up are required to demonstrate the effectiveness of such an approach in Western populations.

Immune response and the tumor microenvironment: how they communicate to regulate gastric cancer

Gastric cancer is the second most common cause of cancer-related death in the world. A growing body of evidence indicates that inflammation is closely associated with the initiation, progression, and metastasis of many tumors, including those of gastric cancer. In addition, approximately 60% of the world's population is colonized by Helicobacter pylori, which accounts for more than 50% of gastric cancers. While the role of inflammation in intestinal and colonic cancers is relatively well defined, its role in stomach neoplasia is still unclear because of the limited access of pathogens to the acidic environment and the technical difficulties isolating and characterizing immune cells in the stomach, especially in animal models. In this review, we will provide recent updates addressing how inflammation is involved in gastric malignancies, and what immune characteristics regulate the pathogenesis of stomach cancer. Also, we will discuss potential therapeutics that target the immune system for the efficient treatment of gastric cancer.

Helicobacter pylori and skin autoimmune diseases

Autoimmune skin diseases are characterized by dysregulation of the immune system resulting in a loss of tolerance to skin self-antigen(s). The prolonged interaction between the bacterium and host immune mechanisms makes Helicobacter pylori (H. pylori) a plausible infectious agent for triggering autoimmunity. Epidemiological and experimental data now point to a strong relation of H. pylori infection on the development of many extragastric diseases, including several allergic and autoimmune diseases. H. pylori antigens activate cross-reactive T cells and induce autoantibodies production. Microbial heat shock proteins (HSP) play an important role of in the pathogenesis of autoimmune diseases because of the high level of sequence homology with human HSP. Eradication of H. pylori infection has been shown to be effective in some patients with chronic autoimmune urticaria, psoriasis, alopecia areata and Schoenlein-Henoch purpura. There is conflicting and controversial data regarding the association of H. pylori infection with Behçet’s disease, scleroderma and autoimmune bullous diseases. No data are available evaluating the association of H. pylori infection with other skin autoimmune diseases, such as vitiligo, cutaneous lupus erythematosus and dermatomyositis. The epidemiological and experimental evidence for a possible role of H. pylori infection in skin autoimmune diseases are the subject of this review.

Helicobacter pylori infection and extragastric disorders in children: a critical update

Helicobacter pylori (H. pylori) is a highly prevalent, serious and chronic infection that has been associated causally with a diverse spectrum of extragastric disorders including iron deficiency anemia, chronic idiopathic thrombocytopenic purpura, growth retardation, and diabetes mellitus. The inverse relation of H. pylori prevalence and the increase in allergies, as reported from epidemiological studies, has stimulated research for elucidating potential underlying pathophysiological mechanisms. Although H. pylori is most frequently acquired during childhood in both developed and developing countries, clinicians are less familiar with the pediatric literature in the field. A better understanding of the H. pylori disease spectrum in childhood should lead to clearer recommendations about testing for and treating H. pylori infection in children who are more likely to develop clinical sequelae. A further clinical challenge is whether the progressive decrease of H. pylori in the last decades, abetted by modern clinical practices, may have other health consequences.

Differences in the antigens of Helicobacter pylori strains influence on the innate immune response in the in vitro experiments

The immune response to Helicobacter pylori importantly determines the pathogenesis of infection as well as the success of antibiotic eradication of the bacteria. Strains of H. pylori were gathered from 14 patients who failed to eradicate H. pylori infection with antibiotics—therapy resistant strains (TRS)—or from patients who were able to eradicate H. pylori infection—therapy susceptible strains (TSS). The THP-1 cells were stimulated with H. pylori antigens. Cathepsin X expression on THP-1 cells and concentration of cytokines in the supernatant of THP-1 cells were measured with a flow cytometer. TSS H. pylori antigens increased the proportion of cathepsin X positive cells compared to TRS H. pylori antigens. TSS H. pylori antigens induced higher secretion of IL-12 and IL-6 compared to TRS H. pylori antigens (P < 0.001; 0.02). Polymyxin B, a lipid A inhibitor, lowered the secretion of IL-12 and IL-6 in TRS and TSS. We demonstrated a H. pylori strain-dependent cathepsin X and cytokine expression that can be associated with H. pylori resistance to eradication due to lack of effective immune response. Differences in lipid A of H. pylori might have an influence on the insufficient immune response, especially on phagocytosis.

Helicobacter pylori membrane vesicles stimulate innate pro- and anti-inflammatory responses and induce apoptosis in Jurkat T cells

Persistent Helicobacter pylori infection induces chronic inflammation in the human gastric mucosa, which is associated with development of peptic ulceration, gastric atrophy, and gastric adenocarcinoma. It has been postulated that secretion of immunomodulatory molecules by H. pylori facilitates bacterial persistence, and membrane vesicles (MV), which have the potential to cross the gastric epithelial barrier, may mediate delivery of these molecules to host immune cells. However, bacterial MV effects on human immune cells remain largely uncharacterized to date. In the present study, we investigated the immunomodulatory effects of H. pylori MV with and without the vacuolating cytotoxin, VacA, which inhibits human T cell activity. We show a high degree of variability in the toxin content of vesicles between two H. pylori strains (SS1 and 60190). Vesicles from the more toxigenic 60190 strain contain more VacA (s1i1 type) than vesicles from the SS1 strain (s2i2 VacA), but engineering the SS1 strain to produce s1i1 VacA did not increase the toxin content of its vesicles. Vesicles from all strains tested, including a 60190 isogenic mutant null for VacA, strongly induced interleukin-10 (IL-10) and IL-6 production by human peripheral blood mononuclear cells independently of the infection status of the donor. Finally, we show that H. pylori MV induce T cell apoptosis and that this is enhanced by, but not completely dependent on, the carriage of VacA. Together, these findings suggest a role for H. pylori MV in the stimulation of innate pro- and anti-inflammatory responses and in the suppression of T cell immunity.

Decreased risk of celiac disease in patients with Helicobacter pylori colonization

The prevalence of celiac disease (CD) has increased in recent decades without a clear explanation. The "hygiene hypothesis" theorizes that decreased exposure to bacterial antigens may trigger autoimmunity. We aimed to determine whether Helicobacter pylori infection and CD were associated among patients undergoing upper gastrointestinal endoscopy. We performed a cross-sectional study of patients who underwent esophagogastroduodenoscopy with submission of gastric and duodenal biopsies to Miraca Life Sciences, Inc. (Irving, Texas), a US commercial pathology laboratory, during a 4.5-year period (January 2008-June 2012). We compared the prevalence of H. pylori in CD patients with that in persons without CD. We performed multiple logistic regression analysis, adjusting odds ratios for patient age, gender, and racial, ethnic, and socioeconomic factors. Among 136,179 patients, a total of 2,689 (2.0%) had CD. H. pylori prevalence was significantly lower in patients with CD (4.4%) than in those without CD (8.8%; P < 0.0001). After adjustment for the above covariates, this inverse relationship remained strong (adjusted odds ratio (OR) = 0.48, 95% confidence interval (CI): 0.40, 0.58). The relationships were similar in men (unadjusted OR = 0.51, 95% CI: 0.38, 0.69) and women (unadjusted OR = 0.46, 95% CI: 0.36, 0.58) and in all age groups. We conclude that H. pylori presence and CD are inversely associated, a relationship that persists after adjustment for socioeconomic factors. Future studies should address whether H. pylori modulates immune responses to ingested gluten.

Signal transduction of Helicobacter pylori during interaction with host cell protein receptors of epithelial and immune cells

Helicobacter pylori infections can induce pathologies ranging from chronic gastritis, peptic ulceration to gastric cancer. Bacterial isolates harbor numerous well-known adhesins, vacuolating cytotoxin VacA, protease HtrA, urease, peptidoglycan, and type IV secretion systems (T4SS). It appears that H. pylori targets more than 40 known host protein receptors on epithelial or immune cells. A series of T4SS components such as CagL, CagI, CagY, and CagA can bind to the integrin α 5β 1 receptor. Other targeted membrane-based receptors include the integrins αvβ 3, αvβ 5, and β 2 (CD18), RPTP-α/β, GP130, E-cadherin, fibronectin, laminin, CD46, CD74, ICAM1/LFA1, T-cell receptor, Toll-like receptors, and receptor tyrosine kinases EGFR, ErbB2, ErbB3, and c-Met. In addition, H. pylori is able to activate the intracellular receptors NOD1, NOD2, and NLRP3 with important roles in innate immunity. Here we review the interplay of various bacterial factors with host protein receptors. The contribution of these interactions to signal transduction and pathogenesis is discussed.

Downregulated Th17 responses are associated with reduced gastritis in Helicobacter pylori-infected children

Helicobacter pylori induces less gastric inflammation in children than adults. Here we investigated whether this reduced inflammation involves dysregulated T helper type 17 (Th17) responses. H. pylori-infected children and adults in Santiago, Chile had similar levels of H. pylori colonization, proportions of bacteria containing cagA and s1/s2 vacA markers of virulence, and strain genotypes (predominantly hpEurope), but the children had significantly reduced levels of gastric inflammation and neutrophil infiltration. The reduced neutrophil accumulation in the infected children was accompanied by significantly fewer gastric Th17 cells and significantly lower levels of interleukin (IL)-17-specific mRNA and protein compared with the infected adults. The gastric mucosa of H. pylori-infected children also contained higher numbers of IL-10+ cells and increased levels of both IL-10 and Foxp3 mRNA compared with that of the infected adults. Thus, reduced gastric inflammation, including diminished neutrophil accumulation, in H. pylori-infected children compared with infected adults is likely due to downregulated gastric Th17/IL-17 responses as a consequence of enhanced mucosal regulatory T-cell activity in the children.