The role of Helicobacter pylori infection in the development of allergic asthma

Helicobacter pylori infection: a dynamic process from diagnosis to treatment

Helicobacter pylori, a gram-negative microaerophilic pathogen, causes several upper gastrointestinal diseases, such as chronic gastritis, peptic ulcer disease, and gastric cancer. For the diseases listed above, H. pylori has different pathogenic mechanisms, including colonization and virulence factor expression. It is essential to make accurate diagnoses and provide patients with effective treatment to achieve positive clinical outcomes. Detection of H. pylori can be accomplished invasively and noninvasively, with both having advantages and limitations. To enhance therapeutic outcomes, novel therapeutic regimens, as well as adjunctive therapies with probiotics and traditional Chinese medicine, have been attempted along with traditional empiric treatments, such as triple and bismuth quadruple therapies. An H. pylori infection, however, is difficult to eradicate during treatment owing to bacterial resistance, and there is no commonly available preventive vaccine. The purpose of this review is to provide an overview of our understanding of H. pylori infections and to highlight current treatment and diagnostic options.

Treatment with Helicobacter pylori-derived VacA attenuates allergic airway disease

Background

Asthma is an incurable heterogeneous disease with variations in clinical and underlying immunological phenotype. New approaches could help to support existing therapy concepts. Neonatal infection of mice with Helicobacter pylori or administration of H. pylori-derived extracts or molecules after birth have been shown to prevent the development of allergic airway disease later in life. This study evaluated the potential therapeutic efficacy of H. pylori vacuolating cytotoxin A (VacA) in allergic airway inflammation and investigated the underlying immunological mechanisms for its actions.

Methods

Murine models of allergic airway diseases, and murine and human in vitro models were used.

Results

In both an acute model and a therapeutic house dust mite model of allergic airway disease, treatment with H. pylori-derived VacA reduced several asthma hallmarks, including airway hyperresponsiveness, inflammation and goblet cell metaplasia. Flow cytometry and ELISA analyses revealed induction of tolerogenic dendritic cells (DC) and FoxP3 positive regulatory T cells (Tregs), and a shift in the composition of allergen-specific immunoglobulins. Depletion of Tregs during treatment with VacA reversed treatment-mediated suppression of allergic airway disease. Human monocyte derived DCs (moDC) that were exposed to VacA induced Tregs in co-cultured naïve autologous T cells, replicating key observations made in vivo.

Conclusion

H. pylori-derived VacA suppressed allergic airway inflammation via induction of Tregs in both allergic airway disease models. These data suggest that the immunomodulatory activity of VacA could potentially be exploited for the prevention and treatment of allergic airway disease.

Precision medicine reaching out to the patients in allergology - a German-Japanese workshop report

An expert workshop in collaboration of the German Society of Allergy and Clinical Immunology (DGAKI) and the Japanese Society of Allergy (JSA) provided a platform for key opinion leaders of both countries aimed to join expertise and to highlight current developments and achievements in allergy research. Key domains of the meeting included the following seven main sections and related subchapters: 1) basic immunology, 2) bronchial asthma, 3) prevention of allergic diseases, 4) food allergy and anaphylaxis, 5) atopic dermatitis, 6) venom allergy, and 7) upper airway diseases. This report provides a summary of panel discussions of all seven domains and highlights unmet needs and project possibilities of enhanced collaborations of scientific projects.

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.

NTSHMDA: Prediction of Human Microbe-Disease Association Based on Random Walk by Integrating Network Topological Similarity

Accumulating clinic evidences have demonstrated that the microbes residing in human bodies play a significantly important role in the formation, development, and progression of various complex human diseases. Identifying latent related microbes for disease could provide insight into human disease mechanisms and promote disease prevention, diagnosis, and treatment. In this paper, we first construct a heterogeneous network by connecting the disease similarity network and the microbe similarity network through known microbe-disease association network, and then develop a novel computational model to predict human microbe-disease associations based on random walk by integrating network topological similarity (NTSHMDA). Specifically, each microbe-disease association pair is regarded as a distinct relationship level and, thus, assigned different weights based on network topological similarity. The experimental results show that NTSHMDA outperforms some state-of-the-art methods with average AUCs of 0.9070, 0.8896 ± 0.0038 in the frameworks of Leave-one-out cross validation and 5-fold cross validation, respectively. In case studies, 9, 18, 38 and 9, 18, 45 out of top-10, 20, 50 candidate microbes are verified by recently published literatures for asthma and inflammatory bowel disease, respectively. In conclusion, NTSHMDA has potential ability to identify novel disease-microbe associations and can also provide valuable information for drug discovery and biological researches.

Modulating local airway immune responses to treat allergic asthma: lessons from experimental models and human studies

With asthma affecting over 300 million individuals world-wide and estimated to affect 400 million by 2025, developing effective, long-lasting therapeutics is essential. Allergic asthma, where Th2-type immunity plays a central role, represents 90% of child and 50% of adult asthma cases. Research based largely on animal models of allergic disease have led to the generation of a novel class of drugs, so-called biologicals, that target essential components of Th2-type inflammation. Although highly efficient in subclasses of patients, these biologicals and other existing medication only target the symptomatic stage of asthma and when therapy is ceased, a flare-up of the disease is often observed. Therefore, it is suggested to target earlier stages in the inflammatory cascade underlying allergic airway inflammation and to focus on changing and redirecting the initiation of type 2 inflammatory responses against allergens and certain viral agents. This focus on upstream aspects of innate immunity that drive development of Th2-type immunity is expected to have longer-lasting and disease-modifying effects, and may potentially lead to a cure for asthma. This review highlights the current understanding of the contribution of local innate immune elements in the development and maintenance of inflammatory airway responses and discusses available leads for successful targeting of those pathways for future therapeutics.

Extract of Helicobacter pylori Ameliorates Parameters of Airway Inflammation and Goblet Cell Hyperplasia following Repeated Allergen Exposure

BACKGROUND

An inverse relation between Helicobacter pylori infection and asthma has been shown in epidemiological studies. Infection with H. pylori, or application of an extract of it before or after sensitization, inhibits allergic airway disease in mice.

OBJECTIVES

The aim of this study was to investigate the effect of an extract of H. pylori on allergic airway disease induced by repeated allergen exposure in mice that were sensitized and challenged prior to extract application.

METHOD

C57BL/6 mice were intranasally (i.n.) sensitized and challenged with house dust mite (HDM). After a minimum of 4 weeks, mice received the H. pylori extract intraperitoneally and were rechallenged i.n. with HDM. Allergen-specific antibodies were measured by ELISA. Cells present in the bronchoalveolar lavage fluid and dendritic cell (DC) subsets in the lung tissue were analyzed by flow cytometry. Tissue inflammation and goblet cell hyperplasia were assessed by histology. Cells of the mediastinal lymph node (mLN) were isolated and in vitro restimulated with HDM or H. pylori extract.

RESULTS

Treatment with H. pylori extract before rechallenge reduced allergen-specific IgE, the DC numbers in the tissue, and goblet cell hyperplasia. Cells isolated from mLN of mice treated with the extract produced significantly more IL-10 and IL-17 after in vitro restimulation with HDM. mLN cells of H. pylori-treated mice that were re-exposed to the H. pylori extract produced significantly more interferon gamma.

CONCLUSIONS

An extract of H. pylori is effective in reducing mucus production and various features of inflammation in HDM rechallenged mice.

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.

Prediction of microbe-disease association from the integration of neighbor and graph with collaborative recommendation model

BACKGROUND

Accumulating clinical researches have shown that specific microbes with abnormal levels are closely associated with the development of various human diseases. Knowledge of microbe-disease associations can provide valuable insights for complex disease mechanism understanding as well as the prevention, diagnosis and treatment of various diseases. However, little effort has been made to predict microbial candidates for human complex diseases on a large scale.

METHODS

In this work, we developed a new computational model for predicting microbe-disease associations by combining two single recommendation methods. Based on the assumption that functionally similar microbes tend to get involved in the mechanism of similar disease, we adopted neighbor-based collaborative filtering and a graph-based scoring method to compute association possibility of microbe-disease pairs. The promising prediction performance could be attributed to the use of hybrid approach based on two single recommendation methods as well as the introduction of Gaussian kernel-based similarity and symptom-based disease similarity.

RESULTS

To evaluate the performance of the proposed model, we implemented leave-one-out and fivefold cross validations on the HMDAD database, which is recently built as the first database collecting experimentally-confirmed microbe-disease associations. As a result, NGRHMDA achieved reliable results with AUCs of 0.9023 ± 0.0031 and 0.9111 in the validation frameworks of fivefold CV and LOOCV. In addition, 78.2% microbe samples and 66.7% disease samples are found to be consistent with the basic assumption of our work that microbes tend to get involved in the similar disease clusters, and vice versa.

CONCLUSIONS

Compared with other methods, the prediction results yielded by NGRHMDA demonstrate its effective prediction performance for microbe-disease associations. It is anticipated that NGRHMDA can be used as a useful tool to search the most potential microbial candidates for various diseases, and therefore boosts the medical knowledge and drug development. The codes and dataset of our work can be downloaded from https://github.com/yahuang1991/NGRHMDA .

The Gastrointestinal Tract Microbiota and Allergic Diseases

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

Take the Wnt out of the inflammatory sails: modulatory effects of Wnt in airway diseases

Bronchial asthma and chronic obstructive pulmonary disease (COPD) are chronic diseases that are associated with inflammation and structural changes in the airways and lungs. Recent findings have implicated Wnt pathways in critically regulating inflammatory responses, especially in asthma. Furthermore, canonical and noncanonical Wnt pathways are involved in structural changes such as airway remodeling, goblet cell metaplasia, and airway smooth muscle (ASM) proliferation. In COPD, Wnt pathways are not only associated with structural changes in the airways but also involved in the development of emphysema. The present review summarizes the role and function of the canonical and noncanonical Wnt pathway with regard to airway inflammation and structural changes in asthma and COPD. Further identification of the role and function of different Wnt molecules and pathways could help to develop novel therapeutic options for these diseases.

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.

The evolution of the hygiene hypothesis: the role of early-life exposures to viruses and microbes and their relationship to asthma and allergic diseases

PURPOSE OF REVIEW

Understanding the mechanisms involved in the development of asthma and allergic diseases is expanding, due in part to sequencing advances that have led to the identification of new viral strains such as human rhinovirus strain C (HRV-C) and the human microbiome project.

RECENT FINDINGS

Recent studies have identified new ways in which viral and microbial exposures in early life interact with host genetic background/variants to modify the risk for developing asthma and allergic diseases. Recent research suggests that HRV-C is the main pathogenic agent associated with infant wheeze, hospitalizations and likely the subsequent development of asthma. Pulmonary He MRI suggests that HRV infection in early childhood and subsequent immune responses initiate airway remodeling. Numerous studies of the microbiome indicate that intestinal and airway microbiome diversity and composition contribute to the cause of asthma and allergic diseases.

SUMMARY

Susceptibility to asthma and allergic diseases is complex and involves genetic variants and environmental exposures (bacteria, viruses, smoking, and pet ownership), alteration of our microbiome and potentially large-scale manipulation of the environment over the past century.

Correlation between Helicobacter pylori infection, IgE hypersensitivity, and allergic disease in Korean adults

BACKGROUND

The correlation between allergic disease and Helicobacter pylori infection is still controversial in endemic areas. The aim of this study was to determine whether H. pylori infection is related to allergic disease and/or immunoglobulin E (IgE) hypersensitivity in Korean adults.

MATERIALS AND METHODS

Consecutive Korean adults who visited our center for a routine checkup were enrolled. All subjects completed a questionnaire that was designed to ascertain their medical history pertaining to physician-diagnosed allergic disease, allergy treatments, and H. pylori eradication therapy. Blood was sampled for serum anti-H. pylori IgG antibody. IgE hypersensitivity was measured using a commercially available ImmunoCAP(®) Phadiatop (Phadia AB, Uppsala, Sweden).

RESULTS

Of the 3376 Korean adults who were enrolled, 62 did not answer to the questionnaires adequately and were thus excluded. The proportion of noninfected subjects (p < .001) and the prevalence of IgE-related allergic disease (p < .001) were both highest among those aged <40 years, while the prevalence of non-IgE-related allergic disease was highest among those aged ≥70 years (p < .001). Logistic regression analysis revealed that being younger than 40 years was significantly related to the absence of H. pylori infection (OR = 2.507, 95% CI = 1.621-3.878, p < .001).

CONCLUSIONS

The statuses of H. pylori infection, IgE hypersensitivity, and allergic diseases differ with age group, there being a higher prevalence of IgE-related allergic disease and a lower H. pylori infection rate among young adults. The hygiene hypothesis might explain these findings in young Koreans, due to the rapid development and improvements in sanitation in Korea.

Microorganism-induced suppression of allergic airway disease: novel therapies on the horizon?

Allergic airway disease is a major global health burden, and novel treatment options are urgently needed. Numerous epidemiological and experimental studies suggest that certain helminths and bacteria protect against respiratory allergies. These microorganisms are strong regulators of the immune system, and various potential regulatory mechanisms by which they protect against allergic airway inflammation have been proposed. Whereas early studies addressed the beneficial effect of natural infections, the focus now shifts toward identifying the dominant protective molecules and exploring their efficacy in models of allergic airway disease. In this article, we will review the evidence for microbe-mediated protection from allergic airway disease, the potential modes of action involved and discuss advances as well as limitations in the translation of this knowledge into novel treatment strategies against allergic airway disease.

An association between Helicobacter pylori and upper respiratory tract disease: Fact or fiction?

Helicobacter pylori (H. pylori) is a major cause of chronic gastritis and gastric ulcers and considerable evidence supports the notion that infection with this bacterium is also associated with gastric malignancy in addition to various other conditions including pulmonary, vascular and autoimmune disorders. Gastric juice infected with H. pylori might play an important role in upper respiratory tract infection. Although direct and/or indirect mechanisms might be involved in the association between H. pylori and upper respiratory tract diseases, the etiological role of H. pylori in upper respiratory tract disorders has not yet been fully elucidated. Although various studies over the past two decades have suggested a relationship between H. pylori and upper respiratory tract diseases, the findings are inconsistent. The present overview describes the outcomes of recent investigations into the impact of H. pylori on upper respiratory tract and adjacent lesions.

Is asthma an infectious disease? New evidence

The pathogenetic mechanisms leading to asthma are likely to be diverse, influenced by multiple genetic polymorphisms as well as elements of the environment. Recent data on the microbiome of the airway have revealed intriguing differences between the number and diversity of microbial populations in healthy persons and asthmatics. There is convincing evidence that early viral infections, particularly with human rhinovirus and respiratory syncytial virus, are often associated with the development of chronic asthma and with exacerbations. Recent studies suggest that two unrelated types of atypical bacteria, Mycoplasma pneumoniae (Mpn) and Chlamydia pneumoniae, are present in the airways of a substantial proportion of the population, bringing up the possibility that the persistent presence of the organism may contribute to the asthmatic phenotype in a subset of patients. This review will examine the current data regarding a possible role for infection in chronic asthma with a particular focus on atypical bacterial infections.

H. pylori virulence factors: influence on immune system and pathology

Helicobacter pylori is the most widespread chronic bacterial agent in humans and is well recognized for its association with ulcer disease and gastric cancer, with both representing major global health and socioeconomic issues. Given the high level of adaptation and the coevolution of this bacterium with its human host, a thorough and multidirectional view of the specific microbiological characteristics of this infection as well as the host physiology is needed in order to develop novel means of prevention of therapy. This review aims to pinpoint some of these potentially important angles, which have to be considered mutually when studying H. pylori's pathogenicity. The host's biological changes due to the virulence factors are a valuable pillar of H. pylori research as are the mechanisms by which bacteria provoke these changes. In this context, necessary adhesion molecules and significant virulence factors of H. pylori are discussed. Moreover, metabolism of the bacteria, one of the most important aspects for a better understanding of bacterial physiology and consequently possible therapeutic and prophylactic strategies, is addressed. On the other hand, we discuss the recent experimental proofs of the "hygiene hypothesis" in correlation with Helicobacter's infection, which adds another aspect of complexity to this infection.

Helicobacter pylori and nonmalignant diseases

Declining Helicobacter pylori prevalence rates have resulted in a decrease of peptic ulcer bleeding incidence. Moreover, eradication reduces peptic ulcer recurrence rate. Newer studies confirm that H. pylori eradication lowers the risk of recurrent peptic ulcer bleeding. Guidelines therefore advocate a test-and-treat strategy for patients with a history of ulcer bleeding and NSAIDs and/or aspirin use. There is mounting evidence that H. pylori status has no effect on symptoms and treatment efficacy in patients with gastroesophageal reflux disease (GERD). Some studies observed an improvement of GERD complaints after H. pylori eradication, which underlines that H. pylori treatment is not contra-indicated in GERD patients. The exact role of H. pylori in functional dyspepsia (FD) remains controversial. However, there is growing consensus that H. pylori-positive FD should be assessed as a separate entity. In these patients, eradication can be beneficial and appropriate. Finally, several studies suggest that H. pylori infection may also be associated with beneficial effects for the host. Epidemiologic studies showed an inverse relation between H. pylori infection and asthma and allergy, although data are conflicting and need to be expanded.

The pathophysiology of the hygiene hypothesis

There has been a considerable increase in the diagnosis of allergic diseases over the last decades. Prevalence of allergies in high-income countries and urban areas appears higher than in rural environments. While environmental factors like pollution or nutrition can be important, it is more likely that in the end they have a small association with allergies. Childhood infections and exposure to certain microbial antigens on the other hand seem to present a strong negative correlation with allergies, and therefore the increase of the allergic burden in the Western world has been frequently related to a decline of childhood infections giving birth to the "Hygiene Hypothesis". We address the issue with emphasis on the associated pathophysiology tightrope walking between the skepticism of the critics, which cast doubt on it, and the pilgrims' belief of having discovered allergy's Holy Grail.