Is Helicobacter pylori infection associated with asthma risk? A meta-analysis based on 770 cases and 785 controls

Helicobacter pylori infection is associated with decreased odds for eosinophilic esophagitis in Mexican patients

BACKGROUND

The incidence of eosinophilic esophagitis (EoE) is increasing in some regions of the world. Retrospective studies have found an inverse association with Helicobacter pylori infection (H. pylori). A recent prospective study has questioned this relationship. We aimed to evaluate this relationship in Mexican patients.

PATIENTS AND METHODS

We evaluated adult patients without prior eradication of H. pylori. Cases were defined by the presence of esophageal symptoms and >15 eosinophils/high power field (HPF) in the esophageal biopsy. Controls were defined by the presence of <15 eosinophils/HPF in esophageal biopsy. H. pylori infection was defined by histology. Patients were matched by age and gender assigning four controls per case.

RESULTS

We included 190 patients: 38 cases and 152 controls. Cases had higher frequency of atopy, dysphagia, food impaction, peripheral eosinophilia, and endoscopic EoE abnormalities. The overall prevalence of H. pylori was 63.6%. Cases had significantly lower prevalence of H. pylori than controls (36.8% vs. 70.4%, OR 0.21 95% CI 0.08-0.69, p = 0.001). Atopic patients had lower prevalence of H. pylori than non-atopic: 13.1% vs. 50.5% (OR 0.20, 95% CI 0.06-0.69, p < 0.001), particularly allergic rhinitis and food allergy.

CONCLUSIONS

We observed an inverse relationship between H. pylori and EoE as well as atopy. Studies in experimental models of EoE that clarify the role of H. pylori in this interaction are required, as well as robust studies that include other factors (socioeconomic, cultural, microbiota, etc.) in order to clarify this relationship.

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.

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.

Comparative Microbiomics Analysis of Antimicrobial Antibody Response between Patients with Lung Cancer and Control Subjects with Benign Pulmonary Nodules

BACKGROUND

CT screening can detect lung cancer early but suffers a high false-positive rate. There is a need for molecular biomarkers that can distinguish malignant and benign indeterminate pulmonary nodules (IPN) detected by CT scan.

METHODS

We profiled antibodies against 901 individual microbial antigens from 27 bacteria and 29 viruses in sera from 127 lung adenocarcinoma (ADC), 123 smoker controls (SMC), 170 benign nodule controls (BNC) individuals using protein microarrays to identify ADC and BNC specific antimicrobial antibodies.

RESULTS

Analyzing fourth quartile ORs, we found more antibodies with higher prevalence in the three BNC subgroups than in ADC or SMC. We demonstrated that significantly more anti-Helicobacter pylori antibodies showed higher prevalence in ADC relative to SMC. We performed subgroup analysis and found that more antibodies with higher prevalence in light smokers (≤20 pack-years) compared with heavy smokers (>20 pack-years), in BNC with nodule size >1 cm than in those with ≤1 cm nodules, and in stage I ADC than in stage II and III ADC. We performed multivariate analysis and constructed antibody panels that can distinguish ADC versus SMC and ADC versus BNC with area under the ROC curve (AUC) of 0.88 and 0.80, respectively.

CONCLUSIONS

Antimicrobial antibodies have the potential to reduce the false positive rate of CT screening and provide interesting insight in lung cancer development.

IMPACT

Microbial infection plays an important role in lung cancer development and the formation of benign pulmonary nodules.

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 in early childhood and asthma in adolescence

Objective

An inverse effect of Helicobacter pylori (H. pylori) on the occurrence of asthma is debated and early acquisition of H. pylori may be important. We analyzed sera from 197 children from Environment and Childhood Asthma (ECA) study in Oslo for Helicobacter pylori (H. pylori) at 2 and 10 years, and symptoms and signs of asthma at 16 years of age.

Results

While 16.4% of children who were H. pylori negative at 2 and 10 years had current asthma at 16 years, none of the 12 children who were H. pylori positive at 2 years of age had asthma at the age of 16 years, regardless of H. pylori status at 10 years. This trend for less current asthma in children who were H. pylori positive at 2 years compared to persistent or transient negative status at 10 years was not statistically significant, probably due to low number of H. pylori positive children at 2 years of age. Acquisition of H. pylori in school age did not appear to influence the risk of current asthma. Much larger prospective studies are probably required to document whether or not early H. pylori infection may be involved in the risk of asthma development in later childhood.

Helicobacter pylori infection in children: an overview of diagnostic methods

Children differ from adults regarding Helicobacter pylori (H. pylori) infection in many terms. H. pylori infection represents a key factor in the pathogenesis of duodenal ulcer and chronic gastritis in children. H. pylori infection causes some extraintestinal diseases as well as gastrointestinal diseases. Although, among these illnesses in children, symptoms like recurrent abdominal pain are not specific. Moreover, the role of the pathogen in the growth faltering, iron deficiency anemia, and asthma still remains controversial. A reliable method to detect H. pylori infection is a crucial issue, sand is still a matter of active debate. The tests applied for H. pylori diagnosis are grouped as either invasive or non-invasive methods. Invasive methods consist of endoscopic evaluation, the rapid urease test (RUT), histology, and bacterial culture. Non-invasive tests include the urea breath test (UBT), stool antigen test (SAT), serology, and molecular diagnostic approaches. Use of endoscopy is a pre-requisite for all invasive methods and poses difficulties in children as it is a difficult procedure and requires patient's cooperation. For this reason, the non-invasive tests have been commonly used in children, although their accuracy is not very reliable in some cases. Invasive tests may be opted to confirm the diagnosis as and when needed. This review presents the diagnostic tests used to detect H. pylori infection in children.

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, 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 Mechanisms Underlying Helicobacter Pylori-Mediated Protection against Allergic Asthma

Helicobacter pylori, a gram negative pathogen, infects the stomach and gastrointestinal tract and causes pathological damage to these organs. H. pylori infection is more prevalent among people living in developing countries. Allergic asthma is a chronic inflammatory disease of the airways. Hyperinflation, hyperresponsiveness, and abnormal immunological and inflammatory processes in respiratory airways typically occur during an asthma attack. The results of recent studies have suggested an association between H. pylori and asthma risk. However, the role of H. pylori infection in the pathophysiology of asthma is still a matter of debate. The results of some studies indicate an association between H. pylori infection and protection against allergic asthma. Exposure to infectious agents might educate the immune system and provide protection against allergic diseases. H. pylori inflammation also changes gastric hormonal levels and could influence the autonomic nervous system. T-regs could be influenced by the immunological response to H. pylori and then inhibit the Th-2-mediated allergic response. Therefore, H. pylori might play a protective role against asthma. H. pylori can also reduce gastro-esophageal reflux, which is an asthma stimulator. High loads of H. pylori are not always present during infection. It is not definitely clear whether H. pylori is a pathogen or simply an opportunist. It has been suggested that early exposure to H. pylori prevents development of pediatric asthma. Therefore, it is possible that therapeutic products made from H. pylori can be used for the treatment or prevention of asthma.

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.

The Clinical Evidence Linking Helicobacter pylori to Gastric Cancer

Gastric cancer has long been recognized to be accompanied and preceded by chronic gastritis, lasting decades. Arguably, the most important development in our understanding of gastric cancer pathogenesis over the past 50 years has been the realization that, for most cases of gastric cancer, Helicobacter pylori is the cause of the underlying gastritis. Gastritis can promote gastric carcinogenesis, typically via the Correa cascade of atrophic gastritis, intestinal metaplasia, and dysplasia. Nested case-control studies have shown that H pylori infection increases the risk of gastric cancer significantly, both of the intestinal and diffuse subtypes, and that H pylori is responsible for approximately 90% of the world's burden of noncardia gastric cancer. Based largely on randomized studies in high gastric cancer prevalence regions in East Asia, it appears that primary and tertiary intervention to eradicate H pylori can halve the risk of gastric cancer. Some public health authorities now are starting screening and treatment programs to reduce the burden of gastric cancer in these high-risk areas. However, there is currently much less enthusiasm for initiating similar attempts in the United States. This is partially because gastric cancer is a relatively less frequent cause of cancer in the United States, and in addition there are concerns about theoretical downsides of H pylori eradication, principally because of the consistent inverse relationship noted between H pylori and esophageal adenocarcinoma. Nevertheless, establishing a link between chronic H pylori infection and gastric cancer has led to novel insights into cancer biology, the gastrointestinal microbiome, and on individual and population-based gastric cancer prevention strategies.

Detection of Helicobacter pylori in the Bronchoalveolar Lavage of Patients with Lung Cancer Using Real-Time PCR

Background

Lung cancer is one of the most common causes of death worldwide. Although smoking and environmental pollutants are the most important risk factors of lung cancer, the role of infectious causes should also be considered in the pathogenesis and progress of lung cancer.

Objectives

This study examined the relationship between Helicobacter pylori and lung cancer through serology, real-time PCR, and urease tests.

Methods

This descriptive cross-sectional study was conducted on 52 adult patients with lung cancer who were selected after having their history taken and being physically examined by a pulmonologist. Then, the patients underwent a bronchoscopy, a BAL, and biopsy sampling. A urease test was run for each biopsy sample, real-time PCR was used for each BAL sample, and H. pylori serology was used for each patient’s serum.

Results

The patients’ average age was 60.65 ± 9.15 years; 11.5% were female and 88.5% were male. The prevalence of H. pylori in lung cancer patients was 11.5% according to the BAL PCR test, 92.3% according to the serology test, and 3.8% according to the urease test.

Conclusions

The results demonstrated an association between of lung cancer and H. Pylori infection via the hypothesis of direct damage and chronic inflammation through inhalation and aspiration and the systematic immune response induced by H. pylori colonization. Helicobacter pylori, together with a host’s genetic predisposition and other environmental risk factors, could be attributed to the induction of lung cancer.

Management of Helicobacter pylori infections

BACKGROUND

Infection with Helicobacter pylori is associated with severe digestive diseases including chronic gastritis, peptic ulcer disease, and gastric cancer. Successful eradication of this common gastric pathogen in individual patients is known to prevent the occurrence of peptic ulcer disease and gastric cancer.

DISCUSSION

With half of the world's population being infected with H, pylori and only few antibiotics result in an effective eradication, a successful antibiotic driven worldwide eradication program seems unlikely. In addition, H. pylori eradication is not always beneficial as it has been described that eradication can be associated with an increased frequency of other disorders such as pediatric asthma, inflammatory bowel diseases and Barrett's Esophagus. We have to accept that eradication of this infection is a two-edged sword that is both useful and harmful and we should therefore focus our H. pylori eradication policy toward selectively identify and destroy only the virulent strains.

CONCLUSION

In order to still be able to effectively treat H. pylori infections in the future we need an alternative diagnostic/treatment algorithm. This would involve a shift towards more precise and enhanced disease predicting diagnosis that tries to identify patients with chance of developing severe diseases such as gastric cancer, rather than the current regime that is geared towards find and destroy all H. pylori.

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.

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.

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.

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.

[Helicobacter pylori infection and extragastroduodenal diseases]

At present, the clinical significance of Helicobacter pylori infection has been validly determined within the development of a diversity of gastroduodenal diseases, including chronic gastritis, gastroduodenal ulcer, MALT lymphoma, and gastric adenocarcinoma. The Expert Council's Maastricht IV consensus (2010) determining international standards for the diagnosis and treatment of H. pylori infection is that there is evidence that the latter may be associated with the development of a number of extragastroduodenal diseases (EGDDs) presented by iron-deficiency anemia of unspecified etiology, idiopathic thrombocytopenic purpura, and vitamin B12 deficiency. In these diseases, it is recommended that infection with H. pylori be diagnosed and, if the test is positive, this microorganism be eradicated. A large number of investigations have been recently conducted to examine the association of H. pylori infection with other EGDDs. This paper reviews theoretical and epidemiological data on the association of H. pylori with diseases of the cardiovascular (atherosclerosis, myocardial infarction) and central nervous (Alzheimer's disease, Parkinson's disease) systems, pancreas (autoimmune pancreatitis, pancreatic cancer), oncological (colonic adenomas, colorectal cancer, hepatocellular carcinoma), dermatological (chronic spontaneous urticaria), and other EGDDs. The review highlights the potential protective role of H. pylori in diseases with the atopic element of genesis and a complicated course of gastroesophageal reflux disease (Barrett's esophagus, esophageal adenocarcinoma).

Prevention of Helicobacter pylori infection in childhood

Helicobacter pylori (H. pylori) infection is one of the most common infections worldwide. Although infection rates are falling in the developed and developing countries, H. pylori is still widespread in the world. This article has reviewed the important publications on H. pylori in childhood with a focus on its evolving transmission route and the source of infection and preventive strategies in childhood, PubMed was searched up to identify eligible studies. Relevant publications were searched using the following.

Association Between Chronic Respiratory Diseases and Helicobacter pylori: A Meta-Analysis

BACKGROUND

The prevalence of chronic respiratory diseases (CRDs), including chronic bronchitis and chronic obstructive pulmonary disease (COPD), has increased significantly over the past decades. Several studies suggest that Helicobacter pylori infection may be related to the development of CRDs, but the results were not consistent. We carried out a meta-analysis to evaluate the potential association of H.pylori infection with CRDs.

METHODS

We conducted a systematic literature search in PubMed, Embase, Ovid, Google Scholar and CNKI from inception to October 31, 2013. The following search terms were used: "chronic respiratory disease," "chronic bronchitis," "chronic obstructive pulmonary disease" or "COPD" in combination with "Helicobacter pylori" or "Campylobacter pylori." According to established inclusion criteria, we selected all eligible published papers and then extracted essential data. To evaluate the association of H.pylori with chronic bronchitis and COPD, an overall analysis and subgroup analyses were conducted.

RESULTS

A total of 9 case-control studies comprising 782 cases and 815 controls were included in the study. Pooled ORs were 2.30 (95%CI: 1.85-2.85) in the overall analysis, 2.90 (95%CI: 2.04-4.13) in the chronic bronchitis subgroup, and 2.11 (95%CI: 1.35-3.29) in the COPD subgroup.

CONCLUSIONS

The results of the overall analysis and subgroup analyzed suggest a significant association between H.pylori and CRDs. Further studies are needed to clarify the pathogenetic mechanisms involved.

Helicobacter pylori infection: New pathogenetic and clinical aspects

Helicobacter pylori (H. pylori) infects more than half of the world’s human population, but only 1% to 3% of infected people consequently develop gastric adenocarcinomas. The clinical outcome of the infection is determined by host genetic predisposition, bacterial virulence factors, and environmental factors. The association between H. pylori infection and chronic active gastritis, peptic ulcer disease, gastric cell carcinoma, and B cell mucosa-associated lymphoid tissue lymphoma has been well established. With the exception of unexplained iron deficiency anemia and idiopathic thrombocytopenic purpura, H. pylori infection has no proven role in extraintestinal diseases. On the other hand, there is data showing that H. pylori infection could be beneficial for some human diseases. The unpredictability of the long-term consequences of H. pylori infection and the economic challenge in eradicating it is why identification of high-risk individuals is crucial.

Helicobacter pylori infection--a boon or a bane: lessons from studies in a low-prevalence population

Helicobacter pylori (H. pylori) infection is etiologically associated with gastric cancer and peptic ulcer diseases which are both important public health burdens which could be largely eliminated by H. pylori eradication. However, some investigators urge caution based on the hypothesis that eradication of H. pylori may result in an increase in the incidence of gastroesophageal reflux disease, esophageal adenocarcinoma, and childhood asthma. The ethnic Malays of northeastern Peninsular Malaysia have long had a low prevalence of H. pylori infection and, as expected, the incidence of gastric cancer and its precursor lesions is exceptionally low. The availability of a population with a low H. pylori prevalence and generally poor sanitation allows separation of H. pylori from the hygiene hypothesis and direct testing of whether absence of H. pylori is associated with untoward consequence. Contrary to predictions, in Malays, erosive esophagitis, Barrett's esophagus, distal esophageal cancers, and childhood asthma are all of low incidence. This suggests that H. pylori is not protective rather the presence of H. pylori infection is likely a surrogate for poor hygiene and not an important source of antigens involved in the hygiene hypothesis. Helicobacter pylori in Malays is related to transmission from H. pylori-infected non-Malay immigrants. The factors responsible for low H. pylori acquisition, transmission, and burden of H. pylori infection in Malays remain unclear and likely involves a combination of environmental, host (gene polymorphisms), and strain virulence factors. Based on evidence from this population, absence of H. pylori infection is more likely to be boon than a bane.

Extragastric diseases and Helicobacter pylori

In the last year, several diseases from outside of the gastrointestinal tract have been associated with Helicobacter pylori infection. Indeed, this bacterium produces a low-grade inflammatory state, induces molecular mimicry mechanisms, and interferes with the absorbance of nutrients and drugs possibly influencing the occurrence or the evolution of many diseases. In addition to its role in some hematologic conditions, such as immune thrombocytopenic purpura, idiopathic sideropenic anemia, and vitamin B12 deficiency, which were included in the current guidelines, several other conditions such as cardiovascular diseases, diabetes mellitus, hepatobiliary diseases, and neurologic disorders have also shown promising results.

Helicobacter pylori Infection and Risk of Lung Cancer: A Meta-Analysis

Background. Recent evidence showed that Helicobacter pylori seropositivity is a risk factor for gastric and several other cancers. However, evidence on H. pylori infection and risk of lung cancer has been controversial, with a limited number of underpowered studies. We therefore examined the association between H. pylori infection and risk of lung cancer. Methods. A comprehensive literature search was performed using PubMed, EMBASE (until October 2012) for studies investigating an association between Helicobacter pylori (H. pylori) infection and risk of lung cancer. Pooled odds ratio (OR) was calculated using random-effects model. Subgroup and sensitivity analysis were also done. Results. A total of seven studies (6 case-control and 1 cohort study) were included for the analysis. There was a significant heterogeneity among the studies, but no publication bias was observed. We found that H. pylori infection was associated with significantly increased risk of lung cancer (pooled OR, 2.29 (95% CI, 1.34–3.91) P = 0.01). Conclusions. Our meta-analysis suggests a significant increased risk of lung cancer in patients with H. pylori infection. Further research is needed to confirm these findings and to identify the underlying biological mechanisms.