Gastric Microenvironment-A Partnership between Innate Immunity and Gastric Microbiota Tricks Helicobacter pylori

Investigating associations between HLA DQA1 ~ DQB1 haplotypes, H. pylori infection, metaplasia, and anti-CagA IgA seropositivity in a Turkish gastritis cohort

Helicobacter pylori was reported as an important cause of gastritis, and gastric ulcers and CagA oncoprotein-producing H. pylori subgroups were blamed to increase the severity of gastritis. Disparities were reported in that the presence of serum anti-CagA IgA was not parallel with CagA-positive H. pylori cohabitation. We hypothesized that the HLA-DQA1 ~ DQB1 haplotypes in human populations include protective haplotypes that more effectively present immunogenic CagA peptides and susceptible haplotypes with an impaired capacity to present CagA peptides. We recruited patients (n = 201) admitted for gastroendoscopy procedures and performed high-resolution HLA-DQA1 and DQB1 typing. Serum anti-CagA IgA levels were analyzed by ELISA (23.0% positive), and H. pylori was classified as positive or negative in gastric mucosal tissue slides (72.6% positive). The HLA DQA1*05:05 allele (29.1%) and HLA DQB1*03:01 allele (32.8%) were found at the highest frequency among gastritis patients of Turkish descent. In HLA DQA1*05:05 ~ DQB1*03:01 double homozygous (7.3%) and heterozygous (40.7%) haplotype carriers, the presence of anti-CagA IgA decreased dramatically, the presence of H. pylori increased, and the presence of metaplasia followed a decreasing trend. The DQ protein encoded by HLA DQA1*05:05-DQ*03:01 showed a low binding affinity to the CagA peptide when binding capacity was analyzed by the NetMHCIIPan 4.0 prediction method. In conclusion, HLA DQA1 ~ DQB1 polymorphisms are crucial as host defense mechanisms against CagA H. pylori since antigen binding capacity plays a crucial role in anti-CagA IgA production.

The Most Recent Insights into the Roots of Gastric Cancer

Helicobacter pylori (H. pylori) is the most common bacterial infection worldwide, usually being acquired during childhood, and its persistence into adulthood represents one of the main contributors of gastric carcinogenesis. Based on these statements, it would be of great importance to know if the most early premalignant transformation occurs in children or later since, this would enable the development of effective anti-tumorigenesis strategies. The interplay between H. pylori virulence factors, the host's responses modified by this infection, and the gastric microecology are complex and eventually lead to the development of gastric cancer in susceptible individuals. Several biomarkers were identified as major contributors of this long-lasting process, such as pepsinogens, gastrin 17, lipid-, glucose- and iron-metabolism parameters, immunity players, aberrant bacterial DNA methylation, H. pylori virulence factors, and hallmarks of gastric dysbiosis. Several of these biomarkers were also identified in children with H. pylori infection, independently of the presence of premalignant lesions, which were also proven to be present in a subgroup of H. pylori-infected children, especially those carrying extremely virulent strains. Therefore, the most incipient premalignant gastric changes might indeed occur early during childhood, opening a promising research gate for further studies to delineate the border between infection and cancer.

The Influence of Helicobacter pylori on Human Gastric and Gut Microbiota

Helicobacter pylori is a Gram-negative bacterium that is able to colonize the human stomach, whose high prevalence has a major impact on human health, due to its association with several gastric and extra-gastric disorders, including gastric cancer. The gastric microenvironment is deeply affected by H. pylori colonization, with consequent effects on the gastrointestinal microbiota, exerted via the regulation of various factors, including gastric acidity, host immune responses, antimicrobial peptides, and virulence factors. The eradication therapy required to treat H. pylori infection can also have detrimental consequences for the gut microbiota, leading to a decreased alpha diversity. Notably, therapy regimens integrated with probiotics have been shown to reduce the negative effects of antibiotic therapy on the gut microbiota. These eradication therapies combined with probiotics have also higher rates of eradication, when compared to standard treatments, and are associated with reduced side effects, improving the patient's compliance. In light of the deep impact of gut microbiota alterations on human health, the present article aims to provide an overview of the complex interaction between H. pylori and the gastrointestinal microbiota, focusing also on the consequences of eradication therapies and the effects of probiotic supplementation.

Relationship between Helicobacter pylori infection and gastrointestinal microecology

The prevalence of Helicobacter pylori (H. pylori) infection has exceeded 50% worldwide, and it is considered a high-risk factor for chronic gastritis, peptic ulcer, gastric adenocarcinoma, gastroesophageal reflux disease and functional dyspepsia. H. pylori drug resistance is a common problem worldwide. In recent years, the relationship between H. pylori infection and gastrointestinal microecology has received much attention. H. pylori infection changes the structure and composition of gastrointestinal microflora by regulating the gastrointestinal microecological environment, local pH value, cytokines and antimicrobial peptides, and immune response and then plays a crucial role in the occurrence and development of digestive system tumors, liver metabolism and extragastrointestinal diseases. The quadruple strategy of H. pylori eradication can also aggravate gastrointestinal microflora disorder. However, probiotics can reduce intestinal flora changes and imbalances through different mechanisms, thus enhancing the efficacy of H. pylori eradication therapy and reducing adverse reactions caused by eradication therapy. Therefore, this paper reviews the relationship between H. pylori infection and gastrointestinal microecology and its clinical application, providing a basis for clinical treatment.

Traditional and Modern Diagnostic Approaches in Diagnosing Pediatric Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is the most common bacterial infection worldwide, is usually acquired during childhood and is related to gastric carcinogenesis during adulthood. Therefore, its early proper diagnosis and subsequent successful eradication represent the cornerstones of gastric cancer prevention. The aim of this narrative review was to assess traditional and modern diagnostic methods in terms of H. pylori diagnosis. Several invasive and non-invasive methods were described, each with its pros and cons. The invasive diagnostic methods comprise endoscopy with biopsy, rapid urease tests, histopathological exams, cultures and biopsy-based molecular tests. Among these, probably the most available, accurate and cost-effective test remains histology, albeit molecular tests definitely remain the most accurate despite their high costs. The non-invasive tests consist of urea breath tests, serology, stool antigens and non-invasive molecular tests. Urea breath tests and stool antigens are the most useful in clinical practice both for the diagnosis of H. pylori infection and for monitoring the eradication of this infection after therapy. The challenges related to accurate diagnosis lead to a choice that must be based on H. pylori virulence, environmental factors and host peculiarities.

The Challenges of Eradicating Pediatric Helicobacter pylori Infection in the Era of Probiotics

Helicobacter pylori (H. pylori), the most common infection of childhood, results in life-threatening complications during adulthood if left untreated. Most of these complications are related to H. pylori-induced chronic inflammation. The dysbiosis caused by H. pylori is not limited to the gastric microenvironment, but it affects the entire gastrointestinal tract. Eradication of H. pylori has recently become a real challenge for clinicians due to both the persistent increase in antibiotic resistance worldwide and the wide spectrum of side effects associated with the eradication regimens resulting; therefore, there is an urgent need for more effective and less noxious treatment options. Thus, probiotics might be a promising choice in both adults and children with H. pylori infection since their role in improving the eradication rate of this infection has been proved in multiple studies. The positive effects of probiotics might be explained by their abilities to produce antimicrobial compounds and antioxidants, alter local gastric pH, and subsequently decrease H. pylori colonization and adherence to gastric epithelial cells. Nevertheless, if used alone probiotics do not considerably increase the eradication rate.

The Effects of Helicobacter pylori Infection on Gastric Microbiota in Children With Duodenal Ulcer

Background

Helicobacter pylori (H. pylori) infection is the main cause of chronic gastritis and duodenal ulcer in children. Little is known about the effect of H. pylori on gastric microbiota in children with duodenal ulcer. This study is aimed at the characteristics of gastric microbiota in children with duodenal ulcer on H. pylori infection.

Methods

We studied 23 children diagnosed with duodenal ulcer by gastric endoscopy because of the gastrointestinal symptoms, 15 children were diagnosed with H. pylori infection, while 8 children were without H. pylori infection. Endoscopic mucosal biopsy samples were obtained for DNA extraction. Microbiomes were analyzed by 16S rRNA profiling and microbial functions were predicted using the software Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt).

Results

Bacterial richness and diversity of gastric microbiota in duodenal ulcer with H. pylori-positive were lower than those negative. The gastric microbiota in H. pylori-positive group significantly reduced proportions of six phyla and fifteen genera; only Helicobacter taxa were more abundant in H. pylori-positive group. Co-expression network analysis showed a more complex network of interactions in the H. pylori-positive group than that in the H. pylori-negative group. For the predicted functions, lower abundance in the pathways of carbohydrate metabolism, signal transduction, amino acid metabolism, and lipid metabolism were found in H. pylori-positive group than the H. pylori-negative group. H. pylori colonization reduces a microbial community with genotoxic potential in the gastric mucosa of children with duodenal ulcer.

Conclusions

The presence of H. pylori significantly influences gastric microbiota and results in a lower abundance of multiple taxonomic levels in children with duodenal ulcer. Children with duodenal ulcer exhibit a dysbiotic microbial community with genotoxic potential, which is distinct from that of children with H. pylori infection.

Clinical Trial Registration

[http://www.chictr.org.cn], identifier [ChiCTR1800015190].

Influence of Helicobacter pylori infection on PD-1/PD-L1 blockade therapy needs more attention

BACKGROUND AND OBJECTIVE

The tumor microenvironment and tumor immunity are crucially involved in tumor therapy. Immune checkpoint inhibitors targeting PD-1/PD-L1 signal transduction have been widely used in tumor therapy and have shown ideal clinical efficacy. However, some kinds of cancers still do not respond to PD-1/PD-L1 blockade therapy effectively, including gastric cancer. The related factors should be explored.

METHODS AND RESULTS

This review summarizes the recent progression of understanding the influence of Helicobacter pylori infection on PD-1/PD-L1 blockade therapy. Current pieces of evidence have indicated that H. pylori infection might affect the curative effect of tumor therapy associating with the induced immunomodulation.

CONCLUSION

It is necessary to understand the overall integration of PD-1/PD-L1 blockade therapy, the tumor microenvironment, and H. pylori infection. Much attention on the influence of H. pylori infection on the efficacy of tumor immunotherapy should be paid.

Innate Immune Responses in Pediatric Patients with Gastritis—A Trademark of Infection or Chronic Inflammation?

The aim of this study was to define the relationship between several environmental, laboratory, and genetic factors, i.e., TLR2 and NLRP3 polymorphisms, and Helicobacter pylori (H. pylori) infection in children, by comparing three different groups of pediatric subjects: H. pylori-induced gastritis, non-H. pylori gastritis, and healthy controls. Our final study sample included 269 children, which were divided into three groups according to the histopathological exam: group 1 with 51 children with H. pylori-induced gastritis, group 2 with 103 children with H. pylori-negative gastritis, and group 3 (control group) with 115 children without any histopathological changes. All children underwent a thorough anamnesis, clinical exam, laboratory tests, and upper digestive endoscopy with gastric biopsy for rapid urease test, histopathological exam, and genetic analysis of TLR2 rs3804099, TLR2 rs3804100, and NLRP3 rs10754558 gene polymorphisms. We noticed a significant association between living conditions and the type of gastritis (p < 0.0001). Both rapid urease and serological tests were significantly associated with the presence of H. pylori (p < 0.0001). The CT variant genotype of TLR2 rs380499 was significantly associated with neutrophil count (p = 0.0325). We noticed a significant association between the CC variant genotype of NLRP3 rs10754558 and leucocytes, neutrophils, eosinophils, as well as ALT (p = 0.0185, p = 0.0379, p = 0.0483, p = 0.0356). Based on these findings, we state that poor living conditions and rural areas represent risk factors for H. pylori infection. The rapid urease test is a reliable diagnostic tool for this infection. CT and TT carriers of TLR2 rs3804099, as well as CC carriers of NLRP3 rs10754558, might display a more severe degree of systemic inflammation.