Isotope tracing reveals bacterial catabolism of host-derived glutathione during Helicobacter pylori infection

Helicobacter pylori γ-glutamyltransferase is linked to proteomic adaptions important for colonization

Helicobacter pylori γ-glutamyltransferase (gGT) is a virulence factor that promotes bacterial colonization and immune tolerance. Although some studies addressed potential functional mechanisms, the supportive role of gGT for in vivo colonization remains unclear. Additionally, it is unknown how different gGT expression levels may lead to compensatory mechanisms ensuring infection and persistence. Hence, it is crucial to unravel the in vivo function of gGT. We assessed acid survival under conditions mimicking the human gastric fluid and elevated the pH in the murine stomach prior to H. pylori infection to link gGT-mediated acid resistance to colonization. By comparing proteomes of gGT-proficient and -deficient isolates before and after infecting mice, we investigated proteomic adaptations of gGT-deficient bacteria during infection. Our data indicate that gGT is crucial to sustain urease activity in acidic environments, thereby supporting survival and successful colonization. Absence of gGT triggers expression of proteins involved in the nitrogen and iron metabolism and boosts the expression of adhesins and flagellar proteins during infection, resulting in increased motility and adhesion capacity. In summary, gGT-dependent mechanisms confer a growth advantage to the bacterium in the gastric environment, which renders gGT a valuable target for the development of new treatments against H. pylori infection.

Helicobacter pylori and arsenic co-exposure Intensify gastric barrier damage and serum metabolic disorder

Environmental arsenic exposure and Helicobacter pylori (H. pylori) infection are widespread public health concerns, yet their combined effects on gastric pathophysiology remain poorly understood. This study investigated the impact of H. pylori infection and arsenic co-exposure on gastric barrier integrity, oxidative stress, and serum metabolic profiles using a murine model. Mice were divided into control, single-exposure (arsenic), and multiple exposure group (H. pylori infection and arsenic exposure). Gastric barrier function was assessed via immunofluorescence staining of ZO-1 and occludin proteins. Untargeted metabolomics, including PCA, PLS-DA, and KEGG pathway enrichment analyses, were employed to characterize serum metabolic alterations. Gene expression levels of IL-18, Nrf2, Keap1, Cat, Sod1, and Hmox1 in gastric tissues were quantified by qRT-PCR, with Spearman correlation analysis to evaluate metabolite-gene expression relationships. Fluorescence intensity of ZO-1 and occludin was significantly reduced in H. pylori-infected mice, with further deterioration under arsenic co-exposure. Metabolomic profiling revealed distinct serum metabolic perturbations across groups, with the multiple exposure group exhibiting more pronounced fluctuations in metabolite levels (e.g., lipids, amino acids, and peptides) and greater pathway diversity compared to single exposure groups. qRT-PCR analysis demonstrated synergistic upregulation of oxidative stress (Nrf2, Hmox1) and inflammatory (IL-18) markers in the multiple exposure group. Spearman correlation analysis identified significant associations between specific metabolites (e.g., acylcarnitines, bile acids) and antioxidant gene expression, suggesting bidirectional interactions between systemic metabolism and gastric oxidative responses. This study establishes a murine model of H. pylori infection and arsenic co-exposure, revealing synergistic disruption of gastric barrier function, oxidative homeostasis, and metabolic regulation. These findings provide critical insights into the pathophysiological interplay between microbial infection and environmental toxicants, highlighting potential therapeutic targets for mitigating combined exposure risks.

Microbial metabolism of host-derived antioxidants

Humans are exposed to a wide variety of small molecules with antioxidant properties that are poorly metabolized by mammalian cells. However, gastrointestinal microbes encode enzymes that convert these redox-active molecules into nutrient sources and electron acceptors to support bacterial growth in the gut. Here, we describe recent studies highlighting how microbial metabolism of host-derived antioxidants modulates interspecies interactions and provide an overview of the interdisciplinary approaches being used to map these metabolic pathways in vivo. Uncovering microbe-driven biotransformations of redox-active small molecules could create new opportunities to improve human health by modulating redox reactions at the host-microbe interface.

Oxidative Stress in Aortic Valves Associated with Infective Endocarditis: A Report on Three Cases

Background/Objectives: Infective endocarditis (IE) most commonly results from infections by Gram-positive bacteria, and, in this condition, the redox homeostasis is lost due to the overproduction of H2O2, leading to the overstimulation of the immune system and the upregulation of the production of proinflammatory cytokines. The aim of this study was to evaluate the levels of oxidative biomarkers and the enzymatic and non-enzymatic antioxidant systems in subjects with IE. Methods: The study included three cases with IE that had undergone aortic valve replacement (AVR) surgery that was complicated by IE, comparing them with subjects with AVR without IE. We determined the malondialdehyde (MDA), total antioxidant capacity (TAC), carbonyl group concentration, glutathione (GSH), thiols and the nitrate/nitrite ratio (NO3-/NO2-) in homogenized tissue from the cardiac valves. We also measured the activity of glutathione-S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR) and thioredoxin reductase (TrxR). The superoxide dismutase (SOD) isoforms and peroxidase activity were determined using native gels. Results: There were increases in the activity of antioxidant enzymes such as GST, SOD isoforms and peroxidases (p ≤ 0.01) and decreases in oxidative stress markers such as GSH (p = 0.05); meanwhile, MDA and carbonylation were increased (p ≤ 0.05). Conclusions: The results suggest that bacterial infections favor oxidative stress in the aortic valves, which increases the SOD isoforms and peroxidase activity. This contributes to the loss of the intricate redox homeostasis system in patients with IE, causing a positive feedback loop in the oxidative background that results in damage to the heart, likely leading to a fatal outcome.

Infection of Helicobacter pylori contributes to the progression of gastric cancer through ferroptosis

Helicobacter pylori (H. pylori) is a gram-negative pathogen that colonizes gastric epithelial cells, and its chronic infection is the primary risk factor for the development of gastric cancer (GC). Ferroptosis is an iron-dependent form of cell death characterized by intracellular lipid peroxide accumulation and reactive oxygen species (ROS) imbalance. There is evidence suggesting that pathogens can manipulate ferroptosis to facilitate their replication, transmission, and pathogenesis. However, the interaction between ferroptosis and H. pylori infection requires further elucidation. We reviewed the mechanism of ferroptosis and found that H. pylori virulence factors such as cytotoxin-associated gene A (CagA), vacuolating cytotoxin A (VacA), neutrophil-activating protein A (NapA), superoxide dismutase B (SodB), γ-glutamyl transpeptidase (gGT), lipopolysaccharide (LPS), and outer inflammatory protein A (OipA) affected glutathione (GSH), ROS, and lipid oxidation to regulate ferroptosis. It also affected the progression of GC by regulating ferroptosis-related indicators through abnormal gene expression after H. pylori infected gastric mucosa cells. Finally, we discuss the potential application value of ferroptosis inducers, inhibitors and other drugs in treating H. pylori-infected GC patients while acknowledging that their interactions are still not fully understood.

Infiltration to infection: key virulence players of Helicobacter pylori pathogenicity

PURPOSE

This study aims to comprehensively review the multifaceted factors underlying the successful colonization and infection process of Helicobacter pylori (H. pylori), a prominent Gram-negative pathogen in humans. The focus is on elucidating the functions, mechanisms, genetic regulation, and potential cross-interactions of these elements.

METHODS

Employing a literature review approach, this study examines the intricate interactions between H. pylori and its host. It delves into virulence factors like VacA, CagA, DupA, Urease, along with phase variable genes, such as babA, babC, hopZ, etc., giving insights about the bacterial perspective of the infection The association of these factors with the infection has also been added in the form of statistical data via Funnel and Forest plots, citing the potential of the virulence and also adding an aspect of geographical biasness to the virulence factors. The biochemical characteristics and clinical relevance of these factors and their effects on host cells are individually examined, both comprehensively and statistically.

RESULTS

H. pylori is a Gram-negative, spiral bacterium that successfully colonises the stomach of more than half of the world's population, causing peptic ulcers, gastric cancer, MALT lymphoma, and other gastro-duodenal disorders. The clinical outcomes of H. pylori infection are influenced by a complex interplay between virulence factors and phase variable genes produced by the infecting strain and the host genetic background. A meta-analysis of the prevalence of all the major virulence factors has also been appended.

CONCLUSION

This study illuminates the diverse elements contributing to H. pylori's colonization and infection. The interplay between virulence factors, phase variable genes, and host genetics determines the outcome of the infection. Despite biochemical insights into many factors, their comprehensive regulation remains an understudied area. By offering a panoramic view of these factors and their functions, this study enhances understanding of the bacterium's perspective, i.e. H. pylori's journey from infiltration to successful establishment within the host's stomach.

Cross-talk between Helicobacter pylori and gastric cancer: a scientometric analysis

Background

Helicobacter pylori (HP) is considered a leading risk factor for gastric cancer (GC). The aim of this article is to conduct bibliometric and visual analysis to assess scientific output, identify highly cited papers, summarize current knowledge, and explore recent hotspots and trends in HP/GC research.

Methods

A bibliographic search was conducted on October 24, 2023, to retrieve relevant studies on HP/GC research between 2003 and 2022. The search terms were attached to HP and GC. The main data were from the Web of Science Core Collection (WoSCC). Data visualization was performed using Biblioshiny, VOSviewer, and Microsoft Excel.

Results

In HP/GC research, 1970 papers were retrieved. The total number of papers (Np) in HP/GC was growing from 2003 to 2022. China and Japan were in the leading position and made the most contributions to HP/GC. Vanderbilt University and the US Department of Veterans Affairs had the highest Np. The most productive authors were Peek Jr Richard M. and Piazuelo M Blanca. Helicobacter received the most Np, while Gastroenterology had the most total citations (TC). High-cited publications and keyword clustering were used to identify the current status and trends in HP/GC research, while historical citation analysis provided insight into the evolution of HP/GC research. The hot topics included the effect of HP on gastric tumorigenesis and progression, the pathogenesis of HP-induced GC (HP factors), and the mechanisms by which HP affects GC (host factors). Research in the coming years could focus on topics such as autophagy, gut microbiota, immunotherapy, exosomes, epithelial-mesenchymal transition (EMT), and gamma-glutamyl transpeptidase (GGT).

Conclusion

This study evaluated the global scientific output in HP/GC research and its quantitative characteristics, identified the essential works, and collected information on the current status, main focuses and emerging trends in HP/GC research to provide academics with guidance for future paths.

Interactions between Helicobacter pylori infection and host metabolic homeostasis: A comprehensive review

The microbiota actively and extensively participates in the regulation of human metabolism, playing a crucial role in the development of metabolic diseases. Helicobacter pylori (H. pylori), when colonizing gastric epithelial cells, not only induces local tissue inflammation or malignant transformation but also leads to systemic and partial changes in host metabolism. These shifts can be mediated through direct contact, toxic components, or indirect immune responses. Consequently, they influence various molecular metabolic events that impact nutritional status and iron absorption in the host. Unraveling the intricate and diverse molecular interaction links between H. pylori and human metabolism modulation is essential for understanding pathogenesis mechanisms and developing targeted treatments for related diseases. However, significant challenges persist in comprehensively understanding the complex association networks among H. pylori itself, the infected host's status, the host microbiome, and the immune response. Previous metabolomics research has indicated that H. pylori infection and eradication may selectively shape the metabolite and microbial profiles of gastric lesions. Yet, it remains largely unknown how these diverse metabolic pathways, including isovaleric acid, cholesterol, fatty acids, and phospholipids, specifically modulate gastric carcinogenesis or affect the host's serum metabolism, consequently leading to the development of metabolic-associated diseases. The direct contribution of H. pylori to metabolisms still lacks conclusive evidence. In this review, we summarize recent advances in clinical evidence highlighting associations between chronic H. pylori infection and metabolic diseases, as well as its potential molecular regulatory patterns.