The association between asthma and Helicobacter pylori: a meta-analysis

Risk of Ischemic Stroke in Relation to Helicobacter pylori Infection and Eradication Status: A Large-Scale Prospective Observational Cohort Study

Background/Aims

: A few studies have suggested the association between Helicobacter pylori (HP) infection and ischemic stroke. However, the impact of HP eradication on stroke risk has not been well evaluated. This study aimed to assess the influence of HP eradication on the incidence of ischemic stroke, considering the potential effect of sex.

Methods

: This prospective observational cohort study was conducted at Seoul National University Bundang Hospital, from May 2003 to February 2023, and involved gastroscopy-based HP testing. Propensity score (PS) matching was employed to ensure balanced groups by matching patients in the HP eradicated group (n=2,803) in a 3:1 ratio with patients in the HP non-eradicated group (n=960). Cox proportional hazard regression analysis was used to evaluate the risk of ischemic stroke.

Results

: Among 6,664 patients, multivariate analysis after PS matching indicated that HP eradication did not significantly alter the risk of ischemic stroke (hazard ratio, 0.531; 95% confidence interval, 0.221 to 1.270; p=0.157). Sex-specific subgroup analyses, both univariate and multivariate, did not yield statistically significant differences. However, Kaplan-Meier analysis revealed a potential trend: the females in the HP eradicated group exhibited a lower incidence of ischemic stroke than those in the HP non-eradicated group, although this did not reach statistical significance (p=0.057).

Conclusions

: This finding suggests that HP eradication might not impact the risk of ischemic stroke. However, there was a trend showing that females potentially had a lower risk of ischemic stroke following HP eradication, though further investigation is required to establish definitive evidence.

Microbes little helpers and suppliers for therapeutic asthma approaches

Bronchial asthma is a prevalent and increasingly chronic inflammatory lung disease affecting over 300 million people globally. Initially considered an allergic disorder driven by mast cells and eosinophils, asthma is now recognized as a complex syndrome with various clinical phenotypes and immunological endotypes. These encompass type 2 inflammatory endotypes characterized by interleukin (IL)-4, IL-5, and IL-13 dominance, alongside others featuring mixed or non-eosinophilic inflammation. Therapeutic success varies significantly based on asthma phenotypes, with inhaled corticosteroids and beta-2 agonists effective for milder forms, but limited in severe cases. Novel antibody-based therapies have shown promise, primarily for severe allergic and type 2-high asthma. To address this gap, novel treatment strategies are essential for better control of asthma pathology, prevention, and exacerbation reduction. One promising approach involves stimulating endogenous anti-inflammatory responses through regulatory T cells (Tregs). Tregs play a vital role in maintaining immune homeostasis, preventing autoimmunity, and mitigating excessive inflammation after pathogenic encounters. Tregs have demonstrated their ability to control both type 2-high and type 2-low inflammation in murine models and dampen human cell-dependent allergic airway inflammation. Furthermore, microbes, typically associated with disease development, have shown immune-dampening properties that could be harnessed for therapeutic benefits. Both commensal microbiota and pathogenic microbes have demonstrated potential in bacterial-host interactions for therapeutic purposes. This review explores microbe-associated approaches as potential treatments for inflammatory diseases, shedding light on current and future therapeutics.

Helicobacter pylori Infections in Children

In the context of epidemiology, host response, disease presentation, diagnosis, and treatment management, the manifestation of Helicobacter pylori (H. pylori) infection diverges between children and adults. H. pylori infection stands out as one of the most prevalent bacterial infections globally, and its prevalence in both children and adults is decreasing in many developing countries but some still struggle with a high prevalence of pediatric H. pylori infection and its consequences. The majority of infected children are asymptomatic and pediatric studies do not support the involvement of H. pylori in functional disorders such as recurrent abdominal pain. The pathophysiology of H. pylori infection relies on complex bacterial virulence mechanisms and their interaction with the host immune system and environmental factors. This interaction gives rise to diverse gastritis phenotypes, which subsequently influence the potential development of various gastroduodenal pathologies. In clinical settings, the diagnosis of this infection in childhood requires an upper gastrointestinal endoscopic exam with mucosal biopsy samples for histology and culture, or Polymerase Chain Reaction (PCR) at the very least. When warranted, eradication treatment should be given when good compliance is expected, and there should be systematic use of a treatment adapted to the antimicrobial susceptibility profile. To combat the burgeoning threat of multidrug resistance, vigilant surveillance of resistance patterns and strategic antibiotic management are paramount.

Impact of the gut-lung axis on tuberculosis susceptibility and progression

Tuberculosis (TB) has remained at the forefront of the global infectious disease burden for centuries. Concerted global efforts to eliminate TB have been hindered by the complexity of Mycobacterium tuberculosis (Mtb), the emergence of antibiotic resistant Mtb strains and the recent impact of the ongoing pandemic of coronavirus disease 2019 (COVID19). Examination of the immunomodulatory role of gastrointestinal microbiota presents a new direction for TB research. The gut microbiome is well-established as a critical modulator of early immune development and inflammatory responses in humans. Recent studies in animal models have further substantiated the existence of the 'gut-lung axis', where distal gastrointestinal commensals modulate lung immune function. This gut microbiome-lung immune crosstalk is postulated to have an important correlation with the pathophysiology of TB. Further evaluation of this gut immunomodulation in TB may provide a novel avenue for the exploration of therapeutic targets. This mini-review assesses the proposed mechanisms by which the gut-lung axis impacts TB susceptibility and progression. It also examines the impact of current anti-TB therapy on the gut microbiome and the effects of gut dysbiosis on treatment outcomes. Finally, it investigates new therapeutic targets, particularly the use of probiotics in treatment of antibiotic resistant TB and informs future developments in the field.

Epidemiology of Helicobacter pylori

In many countries alike, the time trends of gastric cancer, gastric and duodenal ulcer, ulcerative colitis, Crohn's disease, and colorectal cancer are characterized by similar birth-cohort patterns. Mortality from these diagnoses rose in cohorts born during the 19th century and then fell in subsequent cohorts born during the 20th century.

Helicobacter pylori in Human Stomach: The Inconsistencies in Clinical Outcomes and the Probable Causes

Pathogenic potentials of the gastric pathogen, Helicobacter pylori, have been proposed, evaluated, and confirmed by many laboratories for nearly 4 decades since its serendipitous discovery in 1983 by Barry James Marshall and John Robin Warren. Helicobacter pylori is the first bacterium to be categorized as a definite carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). Half of the world’s population carries H. pylori, which may be responsible for severe gastric diseases like peptic ulcer and gastric cancer. These two gastric diseases take more than a million lives every year. However, the role of H. pylori as sole pathogen in gastric diseases is heavily debated and remained controversial. It is still not convincingly understood, why most (80–90%) H. pylori infected individuals remain asymptomatic, while some (10–20%) develop such severe gastric diseases. Moreover, several reports indicated that colonization of H. pylori has positive and negative associations with several other gastrointestinal (GI) and non-GI diseases. In this review, we have discussed the state of the art knowledge on “H. pylori factors” and several “other factors,” which have been claimed to have links with severe gastric and duodenal diseases. We conclude that H. pylori infection alone does not satisfy the “necessary and sufficient” condition for developing aggressive clinical outcomes. Rather, the cumulative effect of a number of factors like the virulence proteins of H. pylori, local geography and climate, genetic background and immunity of the host, gastric and intestinal microbiota, and dietary habit and history of medicine usage together determine whether the H. pylori infected person will remain asymptomatic or will develop one of the severe gastric diseases.

Association between Helicobacter pylori and risk of childhood asthma: a meta-analysis of 18 observational studies

Objective: The association between Helicobacter pylori (H. pylori) and childhood asthma is unclear. Thus, the aim of this study was to explore the association between H. pylori and childhood asthma.Methods: A literature search, study selection, and data extraction were performed independently and in duplicate. Data were analyzed using STATA software.Results: Eighteen studies enrolling 17,196 children were analyzed. All studies were of moderate-to-high quality. Four studies subcategorized H. pylori infection according to CagA status. Overall, there was a significant negative association between H. pylori and risk for childhood asthma (OR = 0.68; 95% CI, 0.54-0.87; P = 0.002), with no/marginal publication bias identified by the Egger's test and the Begg's test (P = 0.162 and P = 0.198, respectively). The observed inverse association persisted for CagA(+) strains of H. pylori (OR = 0.58; 95% CI, 0.35-0.96; P = 0.034) but not for CagA(-) strains (OR = 0.52; 95% CI, 0.12-2.28; P = 0.387). There was no significant difference between studies with respect to study design, participant age, geographical region, and method of measuring H. pylori.Conclusion: The evidence suggests that H. pylori infection, particularly CagA(+) H. pylori infection, is inversely associated with the risk of childhood asthma. Supplemental data for this article can be accessed at publisher's website.

Prevalence and associated risk factors of Helicobacter pylori infection in the Wuwei cohort of north-western China

OBJECTIVES

To evaluate the prevalence of Helicobacter pylori infection and risk factors and to serotype the strains in Wuwei, located in north-western China, which has a high incidence of gastric cancer.

METHODS

Helicobacter pylori infection was analysed in 21 291 adults by ¹⁴ C-urea breath test, and H. pylori antibody were detected in 9183 serum samples by latex immunoturbidimetric method. The correlation of H. pylori infection with demographic-economic, lifestyle factors and medical history among the participants was determined by questionnaire. The antibodies against H. pylori urease, VacA and CagA in serum were determined by dot immunobinding assay.

RESULTS

The infection rate of H. pylori was 53.0%, and 90.1% of strains were type I strains. The H. pylori infection rate was higher among farmers (OR = 1.34, 95% CI: 1.19-1.50) and individuals who had a junior high school or higher education level (OR = 1.10, 95% CI: 1.06-1.15), and was lower in older individuals (OR = 0.86, 95% CI: 0.83-0.90), individuals with high income (OR = 0.93, 95% CI: 0.90-0.95), individuals with a habit of eating quickly (OR = 0.93, 95% CI: 0.87-0.99) and individuals who consumed more fruit and vegetables (OR = 0.90, 95% CI: 0.85-0.95). Individuals with history of cholecystitis/cholecystolithiasis, hypertension and asthma were negatively correlated with H. pylori infection (P < 0.05).

CONCLUSION

The prevalence of H. pylori infection is high in Wuwei. The major prevalent strain is type I strain. Age, education, occupation, household income, consumption of fruit and vegetables, and habit of eating quickly are independent risk factors for H. pylori infection, which is also associated with individuals with a history of extragastric diseases.

Dendritic cell-derived TGF-β mediates the induction of mucosal regulatory T-cell response to Helicobacter infection essential for maintenance of immune tolerance in mice

BACKGROUND

Helicobacter pylori infection leads to regulatory T-cell (Treg) induction in infected mice, which contributes to H. pylori immune escape. However, the mechanisms responsible for H. pylori induction of Treg and immune tolerance remain unclear. We hypothesized DC-produced TGF-β may be responsible for Treg induction and immune tolerance.

MATERIALS AND METHODS

To test this hypothesis, we generated TGF-β^∆DC mice (CD11c⁺ DC-specific TGF-β deletion) and assessed the impact of DC-specific TGF-β deletion on DC function during Helicobacter infection in vitro and in vivo. To examine the T cell-independent DC function, we crossed TGF-β^∆DC mice onto Rag1KO background to generate TGF-β^∆DC xRag1KO mice.

RESULTS

When stimulated with H. pylori, TGF-β^∆DC BMDC/splenocyte cocultures showed increased levels of proinflammatory cytokines and decreased levels of anti-inflammatory cytokines compared to control, indicating a proinflammatory DC phenotype. Following 6 months of H. felis infection, TGF-β^∆DC mice developed more severe gastritis and a trend toward more metaplasia compared to TGF-β^fl/fl with increased levels of inflammatory Th1 cytokine mRNA and lower gastric H. felis colonization compared to infected TGF-β^fl/fl mice. In a T cell-deficient background using TGF-β^∆DC xRag1KO mice, H. felis colonization was significantly lower when DC-derived TGF-β was absent, revealing a direct, innate function of DC in controlling H. felis infection independent of Treg induction.

CONCLUSIONS

Our findings indicate that DC-derived TGF-β mediates Helicobacter-induced Treg response and attenuates the inflammatory Th1 response. We also demonstrated a previously unrecognized innate role of DC controlling Helicobacter colonization via a Treg-independent mechanism. DC TGF-β signaling may represent an important target in the management of H. pylori.

The Protective Effects of Helicobacter pylori Infection on Allergic Asthma

As an ancient Gram-negative bacterium, Helicobacter pylori has settled in human stomach. Eradicating H. pylori increases the morbidities of asthma and other allergic diseases. Therefore, H. pylori might play a protective role against asthma. The "disappearing microbiota" hypothesis suggests that the absence of certain types of the ancestral microbiota could change the development of immunology, metabolism, and cognitive ability in our early life, contributing to the development of some diseases. And the Hygiene Hypothesis links early environmental and microbial exposure to the prevalence of atopic allergies and asthma. Exposure to the environment and microbes can influence the growing immune system and protect subsequent immune-mediated diseases. H. pylori can inhibit allergic asthma by regulating the ratio of helper T cells 1/2 (Th1/Th2), Th17/regulatory T cells (Tregs), etc. H. pylori can also target dendritic cells to promote immune tolerance and enhance the protective effect on allergic asthma, and this effect relies on highly suppressed Tregs. The remote regulation of lung immune function by H. pylori is consistent with the gut-lung axis theory. Perhaps, H. pylori also protects against asthma by altering levels of stomach hormones, affecting the autonomic nervous system and lowering the expression of heat shock protein 70. Therapeutic products from H. pylori may be used to prevent and treat asthma. This paper reviews the possible protective influence of H. pylori on allergic asthma and the possible application of H. pylori in treating asthma.

Helicobacter pylori infection: Beyond gastric manifestations

Helicobacter pylori (H. pylori) is a bacterium that infects more than a half of world’s population. Although it is mainly related to the development of gastroduodenal diseases, several studies have shown that such infection may also influence the development and severity of various extragastric diseases. According to the current evidence, whereas this bacterium is a risk factor for some of these manifestations, it might play a protective role in other pathological conditions. In that context, when considered the gastrointestinal tract, H. pylori positivity have been related to Inflammatory Bowel Disease, Gastroesophageal Reflux Disease, Non-Alcoholic Fatty Liver Disease, Hepatic Carcinoma, Cholelithiasis, and Cholecystitis. Moreover, lower serum levels of iron and vitamin B12 have been found in patients with H. pylori infection, leading to the emergence of anemias in a portion of them. With regards to neurological manifestations, a growing number of studies have associated that bacterium with multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, and Guillain-Barré syndrome. Interestingly, the risk of developing cardiovascular disorders, such as atherosclerosis, is also influenced by the infection. Besides that, the H. pylori-associated inflammation may also lead to increased insulin resistance, leading to a higher risk of diabetes mellitus among infected individuals. Finally, the occurrence of dermatological and ophthalmic disorders have also been related to that microorganism. In this sense, this minireview aims to gather the main studies associating H. pylori infection with extragastric conditions, and also to explore the main mechanisms that may explain the role of H. pylori in those diseases.

Helicobacter pylori seroprevalence in six different ethnic groups living in Amsterdam: The HELIUS study

BACKGROUND

Helicobacter pylori prevalence varies greatly worldwide. We explored the prevalence of H. pylori and CagA seropositivity among adults aged 18-44 years living in the Netherlands by ethnicity and migration status (first vs second generation).

MATERIALS AND METHODS

Participants from six different ethnic groups were selected from the population-based multi-ethnic HELIUS study in Amsterdam, the Netherlands. Serum samples were tested for H. pylori antigens using a validated Luminex-based multiplex serology assay. Prevalence ratios were estimated using Poisson regression analysis.

RESULTS

A total of 4683 participants aged 18-44 years were randomly selected based on sex, ethnicity, and age. H. pylori seroprevalence was highest in the Ghanaian group (84%), followed by Moroccan (81%), Turkish (66%), African Surinamese (51%), South-Asian Surinamese (48%), and Dutch (17%) participants. All ethnic minority groups had a significantly higher risk of being H. pylori seropositive compared to the Dutch group. This association was strongest among participants born outside the Netherlands (first generation), but was still significant and apparent among second-generation participants. Among first-generation participants, all groups, except the Moroccans, had a significantly higher proportion of individuals with a cagA + H. pylori strain compared to the Dutch participants.

CONCLUSION

Helicobacter pylori seroprevalence among first-generation migrants is high in the Netherlands and remains elevated among second-generation migrants (ie, those born in the Netherlands). High exposure to H. pylori, and especially to the more virulent cagA+ strain, highlights the need for tailored prevention of gastric diseases (notably peptic ulcers and cancers) among migrants.

Clinical and endoscopic characteristics of eosinophilic esophagitis in Japan: a case-control study

Background

Eosinophilic esophagitis (EoE) is an allergy-associated clinicopathologic condition gaining an increasing amount of recognition in various areas of the world. While the clinical definition and characteristics may differ depending on country and region, sufficient studies have not yet been performed in Japan.

Objective

To assess the prevalence of EoE among the Japanese population and the clinical features associated with the disease.

Methods

Endoscopic data from January 2012 to October 2018 was gathered from 9 Japanese clinical institutes. EoE, defined as esophageal mucosal eosinophilia of at least 15 eosinophils per high-power field, was determined based on esophageal biopsies. Clinical and endoscopic patterns in the cases with EoE were investigated and compared with 186 age- and sex-matched controls.

Results

From 130,013 upper endoscopic examinations, 66 cases of EoE were identified (0.051%; mean age, 45.2 years [range, 7-79 years]; 45 males). Twenty-five patients (37.9%) with EoE were diagnosed by endoscopy during a medical check-up. Patients with EoE had more symptoms (69.7% vs. 10.8%, p < 0.01) such as dysphagia and food impaction, and more allergies (65.2% vs. 23.7%, p < 0.01) compared with the controls. The prevalence of atrophic gastritis was lower in EoE patients than in the controls (20.0% vs. 33.3%, p < 0.05).

Conclusion

The prevalence of EoE in the Japanese population was 0.051% which was comparable with previous reports in Japan. History of allergies and the absence of atrophic gastritis were associated with EoE.

Helicobacter pylori Reactivates Human Immunodeficiency Virus-1 in Latently Infected Monocytes with Increased Expression of IL-1β and CXCL8

Background

Helicobacter pylori are gram-negative bacteria, which colonize the human stomach. More than 50% of the world's population is infected by H. pylori. Based on the high prevalence of H. pylori, it is very likely that HIV and H. pylori infection may coexist. However, the molecular events that occur during HIV-H. pylori co-infection remain unclear. Latent HIV reservoirs are the major obstacle in HIV cure despite effective therapy. Here, we explored the effect of H. pylori stimulation on latently HIV-infected monocytic cell line U1.

Methods

High throughput RNA-Seq using Illumina platform was performed to analyse the change in transcriptome between unstimulated and H. pylori-stimulated latently HIV-infected U1 cells. Transcriptome analysis identified potential genes and pathways involved in the reversal of HIV latency using bioinformatic tools that were validated by real-time PCR.

Results

H. pylori stimulation increased the expression of HIV-1 Gag, both at transcription (p<0.001) and protein level. H. pylori stimulation also increased the expression of proinflammatory cytokines IL-1β, CXCL8 and CXCL10 (p<0.0001). Heat-killed H. pylori retained their ability to induce HIV transcription. RNA-Seq analysis revealed 197 significantly upregulated and 101 significantly downregulated genes in H. pylori-stimulated U1 cells. IL-1β and CXCL8 were found to be significantly upregulated using transcriptome analysis, which was consistent with real-time PCR data.

Conclusion

H. pylori reactivate HIV-1 in latently infected monocytes with the upregulation of IL-1β and CXCL8, which are prominent cytokines involved in the majority of inflammatory pathways. Our results warrant future in vivo studies elucidating the effect of H. pylori in HIV latency and pathogenesis.

Inflammation, Immunity, and Vaccine Development for the Gastric Pathogen Helicobacter pylori

It has been over 30 years since a link was established between H. pylori infection of the gastric mucosa and the development of chronic gastric diseases. Research in rodent models supported by data from human tissue demonstrated that the host immune response to H. pylori is limited by host regulatory T cells. Immunization has been shown to induce a potent Th1- and Th17-mediated immune response capable of eradicating or at least significantly reducing the bacterial load of H. pylori in the stomach in small animal models. These results have not translated well to humans. Clinical trials employing many of the strategies used in rodents for oral immunization including the use of a mucosal adjuvant such as Escherichia coli LT or delivery by attenuated enteric bacteria have failed to limit H. pylori infection and have highlighted the potential toxicity of exotoxin-based mucosal adjuvants. A recent study, however, utilizing a recombinant fusion protein of H. pylori urease and the subunit B of E. coli LT, was performed on over 4000 children. Efficacy of over 70% was demonstrated against naturally acquired infection compared to control volunteers one year post-immunization. Efficacy was reduced, but still above 50% at three years. This study provided new insight into the strategies for developing an improved vaccine for widespread use in countries with high infection rates and where gastric cancer (GC) remains one of the most common causes of death due to cancer.

Helicobacter pylori in relation to asthma and allergy modified by abdominal obesity: The HUNT study in Norway

Objective

It is unknown whether the decreasing prevalence of H. pylori infections is associated with the increase in obesity and asthma and allergy. In this study, we assessed if obesity plays an intermediate role between H. pylori infections and allergy.

Design

A population-based, nested case-control study of 10,005 participants within the second Nord-Trøndelag Health Study (HUNT2), Norway, was performed in 1995-1997. The presence of H. pylori was tested by an enzyme immunoassay Pyloriset EIA-IgG, and weight, height, and waist circumference were measured. Body mass index (BMI) and waist circumference were used as measures of general and abdominal obesity, respectively. Self-reported asthma and allergic diseases were collected through questionnaires. The odds ratios of H. pylori relative to asthma and allergic diseases were estimated by logistic regression models stratified by waist circumference categories.

Results

H. pylori infection was present in 31%, ever asthma was reported in 10.4% and allergic rhinitis in 16.2%. The mean BMI was 26.4 ​kg/m² and the mean waist circumference was 86.6 ​cm. H. pylori infection was neither associated with asthma nor allergic diseases. However, when stratified by waist circumference, H. pylori infection was associated with 30-40% reduced odds of asthma and 25% reduced odds of allergic diseases in individuals with abdominal obesity (waist circumference ≥86 ​cm in women and ≥96 ​cm in men).

Conclusion

H. pylori infection is associated with reduced risk of asthma and allergy in individuals with abdominal obesity, suggesting a possible causal pathway from reduced H. pylori infections through obesity to increased risk of asthma and allergy.

Transmaternal Helicobacter pylori exposure reduces allergic airway inflammation in offspring through regulatory T cells

BACKGROUND

Transmaternal exposure to tobacco, microbes, nutrients, and other environmental factors shapes the fetal immune system through epigenetic processes. The gastric microbe Helicobacter pylori represents an ancestral constituent of the human microbiota that causes gastric disorders on the one hand and is inversely associated with allergies and chronic inflammatory conditions on the other.

OBJECTIVE

Here we investigate the consequences of transmaternal exposure to H pylori in utero and/or during lactation for susceptibility to viral and bacterial infection, predisposition to allergic airway inflammation, and development of immune cell populations in the lungs and lymphoid organs.

METHODS

We use experimental models of house dust mite- or ovalbumin-induced airway inflammation and influenza A virus or Citrobacter rodentium infection along with metagenomics analyses, multicolor flow cytometry, and bisulfite pyrosequencing, to study the effects of H pylori on allergy severity and immunologic and microbiome correlates thereof.

RESULTS

Perinatal exposure to H pylori extract or its immunomodulator vacuolating cytotoxin confers robust protective effects against allergic airway inflammation not only in first- but also second-generation offspring but does not increase susceptibility to viral or bacterial infection. Immune correlates of allergy protection include skewing of regulatory over effector T cells, expansion of regulatory T-cell subsets expressing CXCR3 or retinoic acid-related orphan receptor γt, and demethylation of the forkhead box P3 (FOXP3) locus. The composition and diversity of the gastrointestinal microbiota is measurably affected by perinatal H pylori exposure.

CONCLUSION

We conclude that exposure to H pylori has consequences not only for the carrier but also for subsequent generations that can be exploited for interventional purposes.

Helicobacter pylori VacA Targets Myeloid Cells in the Gastric Lamina Propria To Promote Peripherally Induced Regulatory T-Cell Differentiation and Persistent Infection

Helicobacter pylori has coexisted with humans for at least 60.000 years and has evolved persistence strategies that allow it to evade host immunity and colonize its host for life. The VacA protein is expressed by all H. pylori strains and is required for high-level persistent infection in experimental mouse models. Here, we show that VacA targets myeloid cells in the gastric mucosa to create a tolerogenic environment that facilitates regulatory T-cell differentiation, while suppressing effector T-cell priming and functionality. Tregs that are induced in the periphery during H. pylori infection can be found not only in the stomach but also in the lungs of infected mice, where they are likely to affect immune responses to allergens.

The gastric bacterium Helicobacter pylori causes a persistent infection that is directly responsible for gastric ulcers and gastric cancer in some patients and protective against allergic and other immunological disorders in others. The two outcomes of the Helicobacter-host interaction can be modeled in mice that are infected as immunocompetent adults and as neonates, respectively. Here, we have investigated the contribution of the Helicobacter immunomodulator VacA to H. pylori-specific local and systemic immune responses in both models. We found that neonatally infected mice are colonized at higher levels than mice infected as adults and fail to generate effector T-cell responses to the bacteria; rather, T-cell responses in neonatally infected mice are skewed toward Foxp3-positive (Foxp3⁺) regulatory T cells that are neuropilin negative and express RORγt. We found these peripherally induced regulatory T cells (pTregs) to be enriched, in a VacA-dependent manner, not only in the gastric mucosa but also in the lungs of infected mice. Pulmonary pTreg accumulation was observed in mice that have been infected neonatally with wild-type H. pylori but not in mice that have been infected as adults or mice infected with a VacA null mutant. Finally, we traced VacA to gastric lamina propria myeloid cells and show that it suppressed interleukin-23 (IL-23) expression by dendritic cells and induced IL-10 and TGF-β expression in macrophages. Taken together, the results are consistent with the idea that H. pylori creates a tolerogenic environment through its immunomodulator VacA, which skews T-cell responses toward Tregs, favors H. pylori persistence, and affects immunity at distant sites.

Helicobacter pylori and extragastric diseases: A review

Helicobacter pylori (H. pylori) infection is very common and affects approximately half of the world population. It causes gastric diseases, but some authors have reported an association of H. pylori infection with other systemic manifestations beginning in 1994. The list of potential effects of H. pylori outside the stomach includes a number of extragastric manifestations and we focused on neurological, dermatological, hematologic, ocular, cardiovascular, metabolic, allergic, and hepatobiliary diseases. This review discusses these important reported manifestations that are not related to the gastrointestinal tract.

Helicobacter pylori infection does not protect against eosinophilic esophagitis: results from a large multicenter case-control study

OBJECTIVES

Rising trends in eosinophilic esophagitis (EoE) have been repeatedly linked to declining Helicobacter pylori (H. pylori) infection, mostly in retrospective studies. We aimed to prospectively evaluate this inverse association.

METHODS

Prospective case-control study conducted in 23 centers. Children and adults naïve to eradication therapy for H. pylori were included. Cases were EoE patients, whereas controls were defined by esophageal symptoms and <5 eos/HPF on esophageal biopsies. H. pylori status was diagnosed by non-invasive (excluding serology) or invasive testing off proton pump inhibitor (PPI) therapy for 2 weeks. Atopy was defined by the presence of IgE-mediated conditions diagnosed by an allergist.

RESULTS

808 individuals, including 404 cases and 404 controls (170 children) were enrolled. Overall H. pylori prevalence was 38% (45% children vs. 37% adults, p 0.009) and was not different between cases and controls (37% vs. 40%, p 0.3; odds ratio (OR) 0.97; 95% confidence interval (CI) 0.73-1.30), neither in children (42% vs. 46%, p 0.1) nor in adults (36% vs. 38%, p 0.4). Atopy (OR 0.85; 95%CI 0.75-0.98) and allergic rhinitis (OR 0.81; 95%CI 0.68-0.98) showed a borderline inverse association with H. pylori infection in EoE patients. This trend was not confirmed for asthma or food allergy.

CONCLUSIONS

H. pylori infection was not inversely associated with EoE, neither in children nor in adults. A borderline inverse association was confirmed for atopy and allergic rhinitis, but not asthma of food allergy. Our findings question a true protective role of H. pylori infection against allergic disorders, including EoE.

Helicobacter pylori Infection and Risk Factors in Relation to Allergy in Children

PURPOSE

To analyze presence of Helicobacter pylori infection and environmental risk factors among children with and without allergy.

METHODS

Parents of children at primary health care centres/kindergartens and allergologist consultation were asked to answer a questionnaire and to bring a faecal sample. H. pylori infection was detected by monoclonal stool antigen test. Prevalence of H. pylori infection and risk factors were compared between individuals with and without allergy using χ² test, ANOVA test and parameters and logistic regression.

RESULTS

Among 220 children (mean age, 4.7 years; ±standard deviation 2.3 years) H. pylori positivity was non-significantly lower among patients with allergy (n=122) compared to individuals without allergy (n=98): 13.9% (17/122) vs. 22.4% (22/98); p=0.106. In logistic regression analysis presence of allergy was significantly associated with family history of allergy (odds ratio [OR], 8.038; 95% confidence interval [CI], 4.067-15.886; p<0.0001), delivery by Caesarean section (OR, 2.980; 95% CI, 1.300-6.831; p=0.009), exclusive breast feeding for five months (OR, 2.601; 95% CI, 1.316-5.142; p=0.006), antibacterial treatment during the previous year (OR, 2.381; 95% CI, 1.186-4.782; p=0.015).

CONCLUSION

Prevalence of H. pylori infection did not differ significantly between children with and without allergy. Significant association of allergy with delivery by Caesarean section and antibacterial therapy possibly suggests the role of gastrointestinal flora in the development of allergy, while association with family history of allergy indicates the importance of genetic factors in the arise of allergy.

Helicobacter pylori and its secreted immunomodulator VacA protect against anaphylaxis in experimental models of food allergy

BACKGROUND

Food allergy is an increasingly common health problem in Western populations. Epidemiological studies have suggested both positive and negative associations between food allergy and infection with the gastric bacterium Helicobacter pylori.

OBJECTIVE

The objective of this work was to investigate whether experimental infection with H. pylori, or prophylactic treatment with H. pylori-derived immunomodulatory molecules, affects the onset and severity of food allergy, either positively or negatively.

METHODS

We infected neonatal C57BL/6 or C3H mice with H. pylori or treated animals with H. pylori components (bacterial lysate or the immunomodulator VacA) and subsequently subjected them to four different protocols for food allergy induction, using either ovalbumin or peanut extract as allergens for sensitization and challenge. Readouts included anaphylaxis scoring, quantification of allergen-specific serum IgE and IgG1 and of the mast cell protease MCPT1, as well as splenic T-helper-2 cell-derived cytokine production. Mesenteric lymph node CD4⁺ FoxP3⁺ regulatory T cells were subjected to flow cytometric quantification and sorting followed by qRT-PCR, and to DNA methylation analyses of the Treg-specific demethylated region (TSDR) within the FOXP3 locus.

RESULTS

Mice that had been infected with H. pylori or treated with H. pylori-derived immunomodulators showed reduced anaphylaxis upon allergen sensitization and challenge, irrespective of the allergen used. Most of the immunologic assays confirmed a protective effect of H. pylori. CD4⁺ FoxP3⁺ T cells were more abundant in protected mice and exhibited a stable Treg phenotype characterized by FOXP3 TSDR demethylation.

CONCLUSIONS AND CLINICAL RELEVANCE

Helicobacter pylori confers protection against the anaphylaxis associated with ovalbumin and peanut allergy and affects the epigenome of T cells, thereby promoting stable Treg differentiation and functionality. Prophylactic treatment with H. pylori-derived immunomodulators appears to be a promising strategy for food allergy prevention.

Accumulated evidence on Helicobacter pylori infection and the risk of asthma: A meta-analysis

BACKGROUND

Helicobacter pylori (H pylori) infection has been suggested to be related to a decreased risk of asthma, but findings in the literature are inconsistent.

OBJECTIVE

To quantitatively summarize the existing evidence on the association between H pylori infection and asthma risk.

METHODS

The PubMed database was searched for observational studies of H pylori infection in relation to the risk of asthma published in English through May 2017. Measurements of association were pooled using a meta-analytic approach and expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs).

RESULTS

Twenty-four studies were identified in this meta-analysis, including 8 case-control studies composed of 1,247 cases and 2,410 controls, and 16 cross-sectional studies composed of 50,290 participants (4,185 cases and 46,105 noncases). The average H pylori infection rates were 40.01% and 48.74% in case-control and cross-sectional studies, respectively. Five studies subcategorized H pylori infection according to CagA status, in which 59.37% of H pylori-infected participants were identified as having CagA positivity. Helicobacter pylori infection was significantly inversely associated with the risk of asthma in case-control studies (OR 0.83, 95% CI 0.71-0.98) but was borderline significant in cross-sectional studies (OR 0.88, 95% CI 0.76-1.02). The observed inverse association persisted for CagA-positive H pylori infection (OR 0.77, 95% CI 0.63-0.93, P for interaction = .03) but not for CagA-negative strains (OR 1.08, 95% CI 0.66-1.78). No significant difference was observed across age or region subgroups.

CONCLUSION

The accumulated evidence supports that H pylori infection, especially CagA-positive H pylori infection, is inversely associated with the risk of asthma.

Helicobacter, Hygiene, Atopy, and Asthma

The hygiene hypothesis links environmental and microbial exposures in early life to the prevalence of atopy, allergy, and asthma. Helicobacter pylori infection is typically acquired in childhood and acquisition of the infection is associated with poor household hygiene. Some population surveys have shown an inverse association between H. pylori infection and atopy, allergy, and asthma leading to the suggestion that H. pylori infection may be protective against disease; others consider it simply a biomarker for poor household hygiene. We review the relevant surveys, cohort studies, meta-analyses, and studies testing the protective hypothesis. Overall, the results of surveys and cohort studies are inconsistent, whereas meta-analyses show a significant but weak inverse correlation. In contrast, studies directly testing the protection hypothesis in relation to asthma in populations with poor hygiene and low H. pylori prevalence failed to confirm a protective effect. H. pylori is a major cause of human disease including chronic gastritis, peptic ulcer, and gastric malignancies. H. pylori infections most likely serve as a biomarker for poor hygienic conditions in childhood. We conclude that while synergistic interactions between environmental factors in childhood are important determinants of the pathogenesis of atopy, allergy, and asthma; H. pylori is inversely related to good hygiene and thus it's presence serves as a biomarker rather than for a specific prevention role for H. pylori or H. pylori antigens.

The state of asthma epidemiology: an overview of systematic reviews and their quality

BACKGROUND

Recently, we have published an overview of systematic reviews in allergy epidemiology and identified asthma as the most commonly reviewed allergic disease. Building on this work, we aimed to investigate the quality of systematic reviews in asthma using the AMSTAR checklist and to provide a reference for future, more in-depth assessment of the extent of previous knowledge.

METHODS

We included all 307 systematic reviews indexed with asthma, including occupational asthma, and/or wheeze from our previous search in PubMed and EMBASE up to December 2014 for systematic reviews on epidemiological research on allergic diseases. Topics of the included systematic reviews were indexed and we applied the AMSTAR checklist for methodological quality to all. Statistical analyses include description of lower and upper bounds of AMSTAR scores and variation across publication time and topics.

RESULTS

Of 43 topics catalogued, family history, birth weight, and feeding of formula were only covered once in systematic reviews published from 2011 onwards. Overall, at least one meta-analysis was conducted for all topics except for "social determinants", "perinatal", "birth weight", and "climate". AMSTAR quality scores were significantly higher in more recently published systematic reviews, in those with meta-analysis, and in Cochrane reviews. There was evidence of variation of quality across topics even, after accounting for these characteristics. Genetic factors in asthma development were often covered by systematic reviews with some evidence of unsubstantiated updates or repetition.

CONCLUSIONS

We present a comprehensive overview with an indexed database of published systematic reviews in asthma epidemiology including quality scores. We highlight some topics including active smoking and pets, which should be considered for future systematic reviews. We propose that our search strategy and database could be a basis for topic-specific overviews of systematic reviews in asthma epidemiology.

Host pathogen interactions in Helicobacter pylori related gastric cancer

Helicobacter pylori (H. pylori), discovered in 1982, is a microaerophilic, spiral-shaped gram-negative bacterium that is able to colonize the human stomach. Nearly half of the world's population is infected by this pathogen. Its ability to induce gastritis, peptic ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma has been confirmed. The susceptibility of an individual to these clinical outcomes is multifactorial and depends on H. pylori virulence, environmental factors, the genetic susceptibility of the host and the reactivity of the host immune system. Despite the host immune response, H. pylori infection can be difficult to eradicate. H. pylori is categorized as a group I carcinogen since this bacterium is responsible for the highest rate of cancer-related deaths worldwide. Early detection of cancer can be lifesaving. The 5-year survival rate for gastric cancer patients diagnosed in the early stages is nearly 90%. Gastric cancer is asymptomatic in the early stages but always progresses over time and begins to cause symptoms when untreated. In 97% of stomach cancer cases, cancer cells metastasize to other organs. H. pylori infection is responsible for nearly 60% of the intestinal-type gastric cancer cases but also influences the development of diffuse gastric cancer. The host genetic susceptibility depends on polymorphisms of genes involved in H. pylori-related inflammation and the cytokine response of gastric epithelial and immune cells. H. pylori strains differ in their ability to induce a deleterious inflammatory response. H. pylori-driven cytokines accelerate the inflammatory response and promote malignancy. Chronic H. pylori infection induces genetic instability in gastric epithelial cells and affects the DNA damage repair systems. Therefore, H. pylori infection should always be considered a pro-cancerous factor.

Helicobacter pylori in children with asthmatic conditions at school age, and their mothers

BACKGROUND

Helicobacter pylori prevalence in Western countries has been declining simultaneously with increases in childhood asthma and allergic diseases; prior studies have linked these phenomena.

AIMS

To examine the association between H. pylori colonisation in children and risk of asthma and related conditions at school age. We secondly examined additional effects of maternal H. pylori status by pairing with children's status.

METHODS

This study was embedded in a multi-ethnic population-based cohort in Rotterdam, The Netherlands. We measured anti-H. pylori and anti-CagA antibodies in serum of children obtained at age 6 years, and of their mothers obtained during midpregnancy. Asthma or related conditions were reported for children at age 6 years. We used multivariate logistic regression analyses among 3797 subjects.

RESULTS

In children, the H. pylori positivity rate was 8.7%, and 29.2% of these were CagA-positive. A child's colonisation with a CagA-negative-H. pylori strain was associated with an increased risk of asthma (Odds ratio 2.11; 95% CI 1.23-3.60), but this differed for European (3.64; 1.97-6.73) and non-European (0.52; 0.14-1.89) children. When taking into account maternal H. pylori status, only H. pylori-positive children with an H. pylori-negative mother had increased risk of asthma (2.42; 1.11-5.27), accounting for 3.4% of the asthma risk.

CONCLUSIONS

Colonisation of a European child with a CagA-negative-H. pylori strain at age 6 was associated with an increased prevalence of asthma, but there was no association for non-European children. The underlying mechanisms for the observed risk differences require further research.

Potential protective effect of Helicobacter pylori on the development of gastrointestinal GvHD

Previous reports ascribe a modulating capacity of the immune response to Helicobacter pylori (HP). Our hypothesis was to demonstrate in a prospective study that HP infection could have a protective effect against development of gastrointestinal GvHD in patients receiving allogeneic hematopoietic cell transplantation (HCT). Presence of HP before transplant was determined using C(13) urea breath test. Seventy-nine patients receiving an allogeneic HCT were included and 93.7% of them received PBSC; in 51.9%, the donor was unrelated. Acute gastrointestinal GvHD was diagnosed in 51.9% (n=41). In the multivariable analysis, HP infection was associated with a lower frequency of gastrointestinal GvHD (odds ratio (OR)=0.19 (95% confidence interval (CI): 0.05-0.67); in contrast, an unrelated donor was associated with a higher frequency of gastrointestinal GvHD (odds ratio=5.4 (95% confidence interval: 1.6-18.2). One year overall survival (OS) was 74%. In the multivariate Cox proportional-hazards regression analysis, stages 0-II gastrointestinal GvHD (hazards ratio (HR)=0.19), reduced intensity conditioning (HR=0.04) and tacrolimus-sirolimus GvHD prophylaxis (HR=0.06) were all associated with a better OS. In summary, HP infection could have a role in decreasing gastrointestinal GvHD in patients receiving allogeneic HCT from peripheral blood including related and unrelated donors.

Helicobacter pylori and allergy: Update of research

Recently a lot of literature has been published about the possible preventive action of Helicobacter pylori (H. pylori) against allergy. The present review summarizes research data about the association between H. pylori and allergic diseases, as well as discusses possible hypotheses about the preventive action of H. pylori against atopy. There is evidence from observational studies to support a weak inverse association between prevalence of H. pylori infection and allergy. However, confounders like some unidentified socioeconomic factors, antibiotic use and others could bias the association. Although data from cohort studies point to a possible association of H. pylori with some of the allergic diseases, no definite proof for causal relationship has been clearly demonstrated yet. A biological mechanism proposed to explain the preventive action of H. pylori to allergy is reduced exposure to a major stimulus for the generation of Treg cells in individuals without H. pylori infection. In addition, H. pylori could be an indicator for changes in gut microbiome, reflecting the complex interaction between microbes and immune system.

Activation of Helicobacter Pylori Causes Either Autoimmune Thyroid Diseases or Carcinogenesis in the Digestive Tract

Helicobacter pylori has been implicated in stimulation of immune system, development of autoimmune endocrinopathies as autoimmune thyroiditis (AT) and on other hand induction of immunosupresion activates gastric and extra-gastric diseases such as gastric ulcer or cancer. It causes persistent lifelong infection despite local and systemic immune response. Our results indicate that Helicobacter pylori might cause inhibition of the specific cellular immune response in Helicobacter pylori-infected patients with or without autoimmune diseases such as AT. We cannot also declare the carcinogenic effect in oropharynx. However the association of any infection agents and cancerogenesis exists. The adherence of Helicobacter pylori expression and enlargement of benign lymphatic tissue and the high incidence of the DNA of Helicobacter pylori in laryngopharyngeal and oropharyngeal cancer is reality. LTT appears to be a good tool for detection of immune memory cellular response in patients with Helicobacter pylori infection and AT. All these complications of Helicobacter pylori infection can be abrogated by successful eradication of Helicobacter pylori.

Are probiotics useful in Helicobacter pylori eradication?

Helicobacter pylori (H. pylori) is considered an etiologic factor for the development of peptic ulcer disease, gastric adenocarcinoma, and MALT lymphoma. Therapeutic schemes to eradicate the bacteria are based on double antibiotic therapy and proton pump inhibitor. Despite many therapeutic improvements in H. pylori eradication treatment, it is still associated with high infection rate also in developed countries. Bacterial resistance and adverse events occurrence are among most frequent causes for anti- H. pylori treatment failure. Several studies have reported that certain probiotic strains can exhibit inhibitory activity against H. pylori bacteria. In addition, some probiotic strains can reduce the occurrence of side effects due to antibiotic therapy and consequently increase the H. pylori eradication rate. The results of the prospective double-blind placebo-controlled studies suggest that specific probiotics, such as S. boulardii and L. johnsonni La1 probably can diminish the bacterial load, but not completely eradicate the H. pylori bacteria. Furthermore, it seems that supplementation with S. boulardii is a useful concomitant therapy in the standard H. pylori eradication treatment protocol and most probably increases eradication rate. L. reuteri is equally effective, but more positive studies are needed. Finally, probiotic strains, such as S. boulardii, L. reuteri and L. GG, decrease gastrointestinal antibiotic associated adverse effects.

Disease associations in eosinophilic oesophagitis and oesophageal eosinophilia

Eosinophilic infiltration into oesophageal tissue, typical of eosinophilic oesophagitis (EoE), has been described in several other conditions, including infections, hypersensitivity, and other autoimmune disorders. Since its description, EoE has been associated with an increasing number of diseases also characterized by tissue infiltration, including eosinophilic gastroenteritis and Crohn's disease. While an association between EoE and coeliac disease was previously reported, it is not supported by recent research. In contrast, EoE seems to be common in patients with a history of congenital oesophageal atresia, leading to hypotheses linking both disorders. The prevalence of EoE has also been shown to be eight times higher in patients with connective tissue disorders (CTDs), which has led to the proposal of an EoE-CTD phenotype, although this requires further assessment. This paper reviews the evidence of EoE's associations with several disorders, defining the common bases from an epidemiological, clinical, molecular and genetic perspective whenever possible.

Allergies, Helicobacter pylori and the continental enigmas

Helicobacter pylori, a gastric pathogen, is known to be associated with gastric and duodenal ulcers, and is also a strong risk factor for the development of gastric cancer and lymphoma of the mucosal-associated lymphoid tissue. Ordinarily, this should make a strong case for its eradication at par with any other infectious disease. However, the unique biology of H. pylori and the complexity of its interactions with humans, its only known natural host, do not permit the recommendation of unambiguous preventive and therapeutic measures. Moreover, this organism has co-evolved with humans as a practically universal member of the natural gastric microbiota over at least 100,000 years. H. pylori persists for a lifetime in mostly asymptomatic hosts, and causes clinical disease only in a minority of infections. Therefore, its potential contribution to the maintenance of human immune homeostasis, as is the case with the better-studied members of the intestinal microbiota, is certainly worthy of serious investigation. In this paper, we summarize some interesting and often anecdotal data drawn from recent studies, and examine their significance in the context of the hygiene hypothesis. We also examine whether the lower incidence of gastric cancer over large parts of the world in spite of a high prevalence of infection (the Asian and African enigmas) may be re-interpreted in terms of the hygiene hypothesis. Finally, it is suggested that an evolutionary-ecological approach to the study of H. pylori infection may help in the formulation of strategies for the management of this infection. This may well be an infectious disease wherein medical interventions may have to be personalized to ensure optimal outcomes.

Evaluation of the Correlation Between Childhood Asthma and Helicobacter pylori in Kashan

Background:

Asthma is a chronic inflammatory air-way disease with increasing prevalence rate during the recent years. There are studies about the relationship between asthma and infectious diseases, including the association between asthma and Helicobacter pylori. According to the latest studies, there is an epidemiological correlation between asthma prevalence and prevalence of H. pylori.

Objectives:

The aim of this research was to study the correlation between H. pylori and asthma by biopsy in five to eighteen year-old children who had undergone endoscopy at Shahid Beheshti Hospital.

Patients and Methods:

Three hundred children (5 to 18 years old) undergoing endoscopy owing to gastro-intestinal problems at Shahid Beheshti Hospital were observed for childhood asthma using the Gina 2010 questionnaire which included 24 questions with “yes” and “no” answers to identify asthmatic patients with five positive answers. Next, the patients were referred to an allergy and asthma specialist for clinical examinations, spirometry and post bronchodilator test (Post BD).

Results:

Among 138 H. pylori positive patients, eight cases (5.8 %) were asthmatic while of the 162 H. pylori negative patients 28 (17.3%) were asthmatic. This difference was statistically significant (P Value = 0.002). The correlation between H. pylori and asthma was studied after controlling the confounding variables including, gender, age and family history. The results obtained for the above-mentioned variables were significant (P Values of 0.004, 0.005 and 0.002, and Odd-Ratio Mantel Haenszel (ORMH) of 3.38, 3.24 and 4.06, respectively).

Conclusions:

Our findings showed that there is an inverse correlation between H. pylori and asthma. Performing more studies with larger sample sizes is necessary to confirm these results.

An inverse association of Helicobacter pylori infection with oral squamous cell carcinoma

BACKGROUND

Few studies have focused on the relationship between Helicobacter pylori (H. pylori) infection and oral diseases. In this study, we explored the correlation between H. pylori infection and oral squamous cell carcinoma (OSCC).

METHODS

A total of 68 patients with OSCC and 104 age- and sex- matched healthy control subjects were retrospectively enrolled in this study. The H. pylori immunoglobin (Ig) G antibodies in serum were detected by enzyme-linked immunosorbent assay (ELISA) method to assess the status of H. pylori infection of our study sample. Polymerase chain reaction (PCR) was also employed using H. pylori genus-specific 16S rRNA primers in fasting blood, and OSCC specimens were analyzed by histochemical stain of each enrolled subject. The strength of correlation between H. pylori and the development of OSCC was estimated by Spearman's correlation coefficient.

RESULTS

According to the three methods for detecting prevalence of H. pylori infection in the patients with OSCC, it was statistically lower than that in the healthy controls (35.3% vs. 54.8%, P = 0.012). An inverse correlation was observed between H. pylori infection and OSCC development (Spearman's correlation coefficient = -0.191, P = 0.012). In stratification analysis, we also found a statistical association between H. pylori infection and OSCC in the subpopulation with age ≥ 60 years (P = 0.037).

CONCLUSION

Our findings suggested that H. pylori infection may be negatively related to OSCC. A reverse association of H. pylori infection with OSCC risk in the subpopulation with age ≥ 60 years was also found.

Helicobacter pylori-specific protection against inflammatory bowel disease requires the NLRP3 inflammasome and IL-18

BACKGROUND

The Gram-negative bacterium Helicobacter pylori is a constituent of the human gastric microbiota. Chronic infection with H. pylori causes gastritis and predisposes to gastric carcinoma but has also been inversely linked to various allergic and chronic inflammatory conditions. In particular, large meta-analyses have documented an inverse association between H. pylori infection and the risk of developing ulcerative colitis and Crohn's disease.

METHODS

We investigated possible protective effects of experimental H. pylori infection and of regular treatment with H. pylori extract in 2 mouse models of colitis and in mouse models of type I diabetes and multiple sclerosis. The mechanism of protection was examined in mouse strains lacking specific innate immune recognition pathways and cytokines.

RESULTS

We show here that experimental infection with H. pylori and administration of regular doses of H. pylori extract both alleviate the clinical and histopathological features of dextran sodium sulfate-induced chronic colitis and of T-cell transfer-induced colitis. High resolution endoscopy of the protected animals revealed the accumulation of large amounts of colonic mucus upon H. pylori exposure, which could be attributed to transcriptional activation of the mucin 2 gene. The protection against dextran sodium sulfate-induced colitis was dependent on the NLRP3 inflammasome and interleukin-18 signaling. Other autoimmune diseases, i.e., experimental autoimmune encephalomyelitis and type I diabetes, were not controlled by H. pylori.

CONCLUSIONS

In summary, we propose here that the immunomodulatory activity of an ancient constituent of the gut microbiota, H. pylori, may be exploited for the prevention and/or treatment of inflammatory bowel diseases.

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.

Clinical features of eosinophilic esophagitis: differences between Asian and Western populations

The prevalence and incidence of eosinophilic esophagitis (EoE) have been rapidly increasing in Western countries. It is thought to be more common among Caucasians than other racial or ethnic groups, but epidemiological studies have not been fully evaluated in Asian populations, and its clinical manifestation is rarely documented. In this review, recent reports regarding EoE in Asian countries have been collected, and differences in the clinical features, including symptoms and endoscopic findings, between Asian and Western populations have been evaluated. In Asia, EoE is still much less prevalent than in Western countries. Baseline values for average age, male/female ratio, and personal history of allergic disease were comparable to those in Western populations. Predominant symptoms were dysphagia, and food impaction was extremely rare among Asian patients. Although the frequency of abnormal endoscopic findings varies among studies, over 90% of patients with EoE have shown abnormal findings such as linear furrow, which is the most common findings, in recent prospective studies in Asia. There are few reports regarding the treatment of EoE and no prospective studies evaluating drugs or elimination diet in patient with EoE have been reported in Asia. Overall, EoE had similar clinical characteristics in Asian populations. Because the incidence of EoE could increase in the future with the increase in allergic disorders in Asian countries, large-scale, nationwide prospective studies should be performed to more fully understand the epidemiology and pathophysiology of EoE in Asian populations.

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.