Animal Models and Helicobacter pylori Infection

Outer membrane vesicles from genetically engineered Salmonella enterica serovar Typhimurium presenting Helicobacter pylori antigens UreB and CagA induce protection against Helicobacter pylori infection in mice

Helicobacter pylori causes globally prevalent infections that are highly related to chronic gastritis and even development of gastric carcinomas. With the increase of antibiotic resistance, scientists have begun to search for better vaccine design strategies to eradicate H. pylori colonization. However, while current strategies prefer to formulate vaccines with a single H. pylori antigen, their potential has not yet been fully realized. Outer membrane vesicles (OMVs) are a potential platform since they could deliver multiple antigens. In this study, we engineered three crucial H. pylori antigen proteins (UreB, CagA, and VacA) onto the surface of OMVs derived from Salmonella enterica serovar Typhimurium (S. Typhimurium) mutant strains using the hemoglobin protease (Hbp) autotransporter system. In various knockout strategies, we found that OMVs isolated from the ΔrfbP ΔfliC ΔfljB ΔompA mutants could cause distinct increases in immunoglobulin G (IgG) and A (IgA) levels and effectively trigger T helper 1- and 17-biased cellular immune responses, which perform a vital role in protecting against H. pylori. Next, OMVs derived from ΔrfbP ΔfliC ΔfljB ΔompA mutants were used as a vector to deliver different combinations of H. pylori antigens. The antibody and cytokine levels and challenge experiments in mice model indicated that co-delivering UreB and CagA could protect against H. pylori and antigen-specific T cell responses. In summary, OMVs derived from the S. Typhimurium ΔrfbP ΔfliC ΔfljB ΔompA mutant strain as the vector while importing H. pylori UreB and CagA as antigenic proteins using the Hbp autotransporter system would greatly benefit controlling H. pylori infection.

The Helicobacter pylori infection alters the intercellular junctions on the pancreas of gerbils (Meriones unguiculatus)

Helicobacter pylori is a common resident in the stomach of at least half of the world's population and recent evidence suggest its emergence in other organs such as the pancreas. In this organ, the presence of H. pylori DNA has been reported in cats, although the functional implications remain unknown. In this work, we determined distinct features related to the H. pylori manifestation in pancreas in a rodent model, in order to analyse its functional and structural effect. Gerbils inoculated with H. pylori exhibited the presence of this bacterium, as revealed by the expression of some virulence factors, as CagA and OMPs in stomach and pancreas, and confirmed by urease activity, bacterial culture, PCR and immunofluorescence assays. Non-apparent morphological changes were observed in pancreatic tissue of infected animals; however, delocalization of intercellular junction proteins (claudin-1, claudin-4, occludin, ZO-1, E-cadherin, β-catenin, desmoglein-2 and desmoplakin I/II) and rearrangement of the actin-cytoskeleton were exhibited. This structural damage was consistent with alterations in the distribution of insulin and glucagon, and a systemic inflammation, event demonstrated by elevated IL-8 levels. Overall, these findings indicate that H. pylori can reach the pancreas, possibly affecting its function and contributing to the development of pancreatic diseases.

Current progresses and challenges for microbiome research in human health: a perspective

It is becoming increasingly clear that the human microbiota, also known as "the hidden organ", possesses a pivotal role in numerous processes involved in maintaining the physiological functions of the host, such as nutrient extraction, biosynthesis of bioactive molecules, interplay with the immune, endocrine, and nervous systems, as well as resistance to the colonization of potential invading pathogens. In the last decade, the development of metagenomic approaches based on the sequencing of the bacterial 16s rRNA gene via Next Generation Sequencing, followed by whole genome sequencing via third generation sequencing technologies, has been one of the great advances in molecular biology, allowing a better profiling of the human microbiota composition and, hence, a deeper understanding of the importance of microbiota in the etiopathogenesis of different pathologies. In this scenario, it is of the utmost importance to comprehensively characterize the human microbiota in relation to disease pathogenesis, in order to develop novel potential treatment or preventive strategies by manipulating the microbiota. Therefore, this perspective will focus on the progress, challenges, and promises of the current and future technological approaches for microbiome profiling and analysis.

Recent Advances in Vitamin D3 Intervention to Eradicate Helicobacter pylori Infection

Helicobacter pylori (HP) infections affect approximately one-third of children worldwide. In China, the incidence of HP infection in children ranges from approximately 30% to 60%. In addition to damaging the gastrointestinal tract mucosa, HP infection in children can negatively affect their growth and development, hematology, respiratory and hepatobiliary system, skin, nutritional metabolism, and autoimmune system. However, the rate of HP eradication also fell considerably from the previous rate due to the presence of drug-resistant HP strains and the limited types of antibiotics that can be used in young patients. Vitamin D3 (VitD3) is a steroid hormone that can reduce inflammation in the stomach mucosa induced by HP and can alleviate and eradicate HP through a variety of pathways and mechanisms, including immune regulation and the stimulation of antimicrobial peptide (AMP) secretion and Ca2+ influx, to reestablish lysosomal acidification; thus, these results provide new strategies and ideas for the eradication of drug-resistant HP strains.

Future Nanotechnology-Based Strategies for Improved Management of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is a recalcitrant pathogen, which can cause gastric disorders. During the past decades, polypharmacy-based regimens, such as triple and quadruple therapies have been widely used against H. pylori. However, polyantibiotic therapies can disturb the host gastric/gut microbiota and lead to antibiotic resistance. Thus, simpler but more effective approaches should be developed. Here, some recent advances in nanostructured drug delivery systems to treat H. pylori infection are summarized. Also, for the first time, a drug release paradigm is proposed to prevent H. pylori antibiotic resistance along with an IVIVC model in order to connect the drug release profile with a reduction in bacterial colony counts. Then, local delivery systems including mucoadhesive, mucopenetrating, and cytoadhesive nanobiomaterials are discussed in the battle against H. pylori infection. Afterward, engineered delivery platforms including polymer-coated nanoemulsions and polymer-coated nanoliposomes are poposed. These bioinspired platforms can contain an antimicrobial agent enclosed within smart multifunctional nanoformulations. These bioplatforms can prevent the development of antibiotic resistance, as well as specifically killing H. pylori with no or only slight negative effects on the host gastrointestinal microbiota. Finally, the essential checkpoints that should be passed to confirm the potential effectiveness of anti-H. pylori nanosystems are discussed.

Genomic and vaccine preclinical studies reveal a novel mouse-adapted Helicobacter pylori model for the hpEastAsia genotype in Southeast Asia

Introduction. Helicobacter pylori infection is a major global health concern, linked to the development of various gastrointestinal diseases, including gastric cancer. To study the pathogenesis of H. pylori and develop effective intervention strategies, appropriate animal pathogen models that closely mimic human infection are essential.Gap statement. This study focuses on the understudied hpEastAsia genotype in Southeast Asia, a region marked by a high H. pylori infection rate. No mouse-adapted model strains has been reported previously. Moreover, it recognizes the urgent requirement for vaccines in developing countries, where overuse of antimicrobials is fuelling the emergence of resistance.Aim. This study aims to establish a novel mouse-adapted H. pylori model specific to the hpEastAsia genotype prevalent in Southeast Asia, focusing on comparative genomic and histopathological analysis of pathogens coupled with vaccine preclinical studies.Methodology. We collected and sequenced the whole genome of clinical strains of H. pylori from infected patients in Vietnam and performed comparative genomic analyses of H. pylori strains in Southeast Asia. In parallel, we conducted preclinical studies to assess the pathogenicity of the mouse-adapted H. pylori strain and the protective effect of a new spore-vectored vaccine candidate on male Mlac:ICR mice and the host immune response in a female C57BL/6 mouse model.Results. Genome sequencing and comparison revealed unique and common genetic signatures, antimicrobial resistance genes and virulence factors in strains HP22 and HP34; and supported clarithromycin-resistant HP34 as a representation of the hpEastAsia genotype in Vietnam and Southeast Asia. HP34-infected mice exhibited gastric inflammation, epithelial erosion and dysplastic changes that closely resembled the pathology observed in human H. pylori infection. Furthermore, comprehensive immunological characterization demonstrated a robust host immune response, including both mucosal and systemic immune responses. Oral vaccination with candidate vaccine formulations elicited a significant reduction in bacterial colonization in the model.Conclusion. Our findings demonstrate the successful development of a novel mouse-adapted H. pylori model for the hpEastAsia genotype in Vietnam and Southeast Asia. Our research highlights the distinctive genotype and pathogenicity of clinical H. pylori strains in the region, laying the foundation for targeted interventions to address this global health burden.

Cross-species single-cell transcriptomic analysis of animal gastric antrum reveals intense porcine mucosal immunity

As an important part of the stomach, gastric antrum secretes gastrin which can regulate acid secretion and gastric emptying. Although most cell types in the gastric antrum are identified, the comparison of cell composition and gene expression in the gastric antrum among different species are not explored. In this study, we collected antrum epithelial tissues from human, pig, rat and mouse for scRNA-seq and compared cell types and gene expression among species. In pig antral epithelium, we identified a novel cell cluster, which is marked by high expression of AQP5, F3, CLCA1 and RRAD. We also discovered that the porcine antral epithelium has stronger immune function than the other species. Further analysis revealed that this may be due to the insufficient function of porcine immune cells. Together, our results replenish the information of multiple species of gastric antral epithelium at the single cell level and provide resources for understanding the homeostasis maintenance and regeneration of gastric antrum epithelium.

Fish Oil Ameliorates Vibrio parahaemolyticus Infection in Mice by Restoring Colonic Microbiota, Metabolic Profiles, and Immune Homeostasis

The effect of fish oil (FO) on colonic function, immunity, and microbiota was investigated in Vibrio parahaemolyticus (Vp)-infected C57BL/6J mice. Mice intragastrically presupplemented with FO (4.0 mg) significantly reduced Vp infection as evidenced by stabilizing body weight and reducing disease activity index score and immune organ ratios. FO minimized colonic pathological damage, strengthened the mucosal barrier, and sustained epithelial permeability by increasing epithelial crypt depth, goblet cell numbers, and tight junctions and inhibiting colonic collagen accumulation and fibrosis protein expression. Mechanistically, FO enhanced immunity by decreasing colonic CD³⁺ T cells, increasing CD⁴⁺ T cells, downregulating the TLR4 pathway, reducing interleukin-17 (IL-17) and tumor necrosis factor-α, and increasing immune cytokine IL-4 and interferon-γ levels. Additionally, FO maintained colonic microbiota eubiosis by improving microbial diversity and boosting Clostridium, Akkermansia, and Roseburia growth and their derived propionic acid and butyric acid levels. Collectively, FO alleviated Vp infection by enriching beneficial colonic microbiota and metabolites and restoring immune homeostasis.

The correlation of Th22 and regulatory T cells with Helicobacter pylori infection in patients with chronic gastritis

OBJECTIVE

Helicobacter pylori is planted in the human stomach and is the most common cause of chronic gastritis, which produced specific local and systemic humoral immunity, while the associations of these immune responses and H. pylori in the development of chronic gastritis remain unclear.

METHODS

This study analyzed histology, the number of Th22 and regulatory T (Treg) cells, and the levels of inflammation- and gastritis-related indicators between 22 H. pylori-infected and 24 non-H. pylori-infected chronic gastritis patients by hematoxylin-eosin staining, enzyme-linked immunosorbent assay, quantitative reverse transcription PCR, and flow cytometry analysis.

RESULTS

This study found that the pathological damage degree of gastric mucosa in H. pylori infection patients was more serious. In the H. pylori-infected patient serum, the gastrin, G-17, interleukins (IL)-22, transforming growth factor (TGF)-β, tumor necrosis factor (TNF)-α, IL-4, and IL-17A levels were notably raised, while the interferon (IFN)-γ level was inhibited, and in gastric mucosa, and except IFN-γ, the IL-22, forkhead box P3 (Foxp3), TNF-α, IL-4, and IL-17A mRNA levels were raised too. The receiver operating characteristic curve analysis indicates serum IL-22, TGF-β, TNF-α, IL-4, and IL-17A are suitable for differential diagnosis of H. pylori infection. In addition, in the peripheral blood, the percentages of the IL-22⁺ CD4⁺ and Foxp3⁺ CD4⁺ T cells were raised with H. pylori infection. The positive correlation between IL-22 and Foxp3 mRNA levels and the degree of H. pylori colonization and gastric mucositis by Pearson's correlation analysis.

CONCLUSIONS

Treg and Th22 cells were positively associated with the degree of H. pylori infection and the severity of gastritis. In summary, this study provides an experimental basis for the study of the eradication of H. pylori and the biological mechanism of chronic gastritis.

Pathogenomics of Helicobacter pylori

The human stomach bacterium Helicobacter pylori, the causative agent of gastritis, ulcers and adenocarcinoma, possesses very high genetic diversity. H. pylori has been associated with anatomically modern humans since their origins over 100,000 years ago and has co-evolved with its human host ever since. Predominantly intrafamilial and local transmission, along with genetic isolation, genetic drift, and selection have facilitated the development of distinct bacterial populations that are characteristic for large geographical areas. H. pylori utilizes a large arsenal of virulence and colonization factors to mediate the interaction with its host. Those include various adhesins, the vacuolating cytotoxin VacA, urease, serine protease HtrA, the cytotoxin-associated genes pathogenicity island (cagPAI)-encoded type-IV secretion system and its effector protein CagA, all of which contribute to disease development. While many pathogenicity-related factors are present in all strains, some belong to the auxiliary genome and are associated with specific phylogeographic populations. H. pylori is naturally competent for DNA uptake and recombination, and its genome evolution is driven by extraordinarily high recombination and mutation rates that are by far exceeding those in other bacteria. Comparative genome analyses revealed that adaptation of H. pylori to individual hosts is associated with strong selection for particular protein variants that facilitate immune evasion, especially in surface-exposed and in secreted virulence factors. Recent studies identified single-nucleotide polymorphisms (SNPs) in H. pylori that are associated with the development of severe gastric disease, including gastric cancer. Here, we review the current knowledge about the pathogenomics of H. pylori.

Impact of the Helicobacter pylori Oncoprotein CagA in Gastric Carcinogenesis

Helicobacter pylori CagA is the first and only bacterial oncoprotein etiologically associated with human cancer. Upon delivery into gastric epithelial cells via bacterial type IV secretion, CagA acts as a pathogenic/pro-oncogenic scaffold that interacts with and functionally perturbs multiple host proteins such as pro-oncogenic SHP2 phosphatase and polarity-regulating kinase PAR1b/MARK2. Although H. pylori infection is established during early childhood, gastric cancer generally develops in elderly individuals, indicating that oncogenic CagA activity is effectively counteracted at a younger age. Moreover, the eradication of cagA-positive H. pylori cannot cure established gastric cancer, indicating that H. pylori CagA-triggered gastric carcinogenesis proceeds via a hit-and-run mechanism. In addition to its direct oncogenic action, CagA induces BRCAness, a cellular status characterized by replication fork destabilization and loss of error-free homologous recombination-mediated DNA double-strand breaks (DSBs) by inhibiting cytoplasmic-to-nuclear localization of the BRCA1 tumor suppressor. This causes genomic instability that leads to the accumulation of excess mutations in the host cell genome, which may underlie hit-and-run gastric carcinogenesis. The close connection between CagA and BRCAness was corroborated by a recent large-scale case-control study that revealed that the risk of gastric cancer in individuals carrying pathogenic variants of genes that induce BRCAness (such as BRCA1 and BRCA2) dramatically increases upon infection with cagA-positive H. pylori. Accordingly, CagA-mediated BRCAness plays a crucial role in the development of gastric cancer in conjunction with the direct oncogenic action of CagA.

25-hydroxyvitamin D levels in children of different ages and with varying degrees of Helicobacter pylori infection and immunological features

Background

Helicobacter pylori (HP) is a major cause of upper digestive tract diseases. However, the relationship between HP infection and 25-hydroxyvitamin D [25(OH)D] levels in children has not been fully elucidated. This study investigated the levels of 25(OH)D in children of different ages and with varying degrees of HP infection and immunological features as well as the correlations between 25(OH)D levels in children infected with HP and their ages and degrees of infection.

Materials and methods

Ninety-four children who underwent upper digestive endoscopy were divided into an HP-positive group without peptic ulcers (Group A), an HP-positive group with peptic ulcers (Group B) and an HP-negative control group (Group C). The serum levels of 25(OH)D and immunoglobulin and the percentages of lymphocyte subsets were determined. HP colonization, the degree of inflammation, and the degree of activity were further evaluated by HE staining and immunohistochemical staining in gastric mucosal biopsy.

Results

The 25(OH)D level of the HP-positive groups (50.93 ± 16.51 nmol/L) was significantly lower than that of the HP-negative group (62.89 ± 19.18 nmol/L). The 25(OH)D level of Group B (47.79 ± 14.79 nmol/L) was lower than that of Group A (51.53 ± 17.05 nmol/L) and was significantly lower than that of Group C (62.89 ± 19.18 nmol/L). The 25(OH)D level decreased with increasing age, and there was a significant difference between Group C subjects who were ≤5 years old and those who were aged 6-9 years and ≥10 years. The 25(OH)D level was negatively correlated with HP colonization (r = -0.411, P < 0.01) and the degree of inflammation (r = -0.456, P < 0.01). The percentages of lymphocyte subsets and immunoglobulin levels among Groups A, B and C were not significantly different.

Conclusions

The 25(OH)D level was negatively correlated with HP colonization and the degree of inflammation. As the age of the children increased, the level of 25(OH)D decreased, and the susceptibility to HP infection increased.