A microbial transporter of the dietary antioxidant ergothioneine.

Low-molecular-weight (LMW) thiols are small-molecule antioxidants required for the maintenance of intracellular redox homeostasis. However, many host-associated microbes, including the gastric pathogen Helicobacter pylori, unexpectedly lack LMW-thiol biosynthetic pathways. Using reactivity-guided metabolomics, we identified the unusual LMW thiol ergothioneine (EGT) in H. pylori. Dietary EGT accumulates to millimolar levels in human tissues and has been broadly implicated in mitigating disease risk. Although certain microorganisms synthesize EGT, we discovered that H. pylori acquires this LMW thiol from the host environment using a highly selective ATP-binding cassette transporter-EgtUV. EgtUV confers a competitive colonization advantage in vivo and is widely conserved in gastrointestinal microbes. Furthermore, we found that human fecal bacteria metabolize EGT, which may contribute to production of the disease-associated metabolite trimethylamine N-oxide. Collectively, our findings illustrate a previously unappreciated mechanism of microbial redox regulation in the gut and suggest that inter-kingdom competition for dietary EGT may broadly impact human health.

Bacteria-Induced Group 2 Innate Lymphoid Cells in the Stomach Provide Immune Protection through Induction of IgA.

The intestinal microbiota shapes and directs immune development locally and systemically, but little is known about whether commensal microbes in the stomach can impact their immunological microenvironment. Here, we report that group 2 innate lymphoid cells (ILC2s) were the predominant ILC subset in the stomach and show that their homeostasis and effector functions were regulated by local commensal communities. Microbes elicited interleukin-7 (IL-7) and IL-33 production in the stomach, which in turn triggered the propagation and activation of ILC2. Stomach ILC2s were also rapidly induced following infection with Helicobacter pylori. ILC2-derived IL-5 resulted in the production of IgA, which coated stomach bacteria in both specific pathogen-free (SPF) and H. pylori-infected mice. Our study thus identifies ILC2-dependent IgA response that is regulated by the commensal microbiota, which is implicated in stomach protection by eliminating IgA-coated bacteria including pathogenic H. pylori.

A Repeat-Associated Small RNA Controls the Major Virulence Factors of Helicobacter pylori.

Many bacterial pathogens regulate their virulence genes via phase variation, whereby length-variable simple sequence repeats control the transcription or coding potential of those genes. Here, we have exploited this relationship between DNA structure and physiological function to discover a globally acting small RNA (sRNA) regulator of virulence in the gastric pathogen Helicobacter pylori. Our study reports the first sRNA whose expression is affected by a variable thymine (T) stretch in its promoter. We show the sRNA post-transcriptionally represses multiple major pathogenicity factors of H. pylori, including CagA and VacA, by base pairing to their mRNAs. We further demonstrate transcription of the sRNA is regulated by the nickel-responsive transcriptional regulator NikR (thus named NikS for nickel-regulated sRNA), thereby linking virulence factor regulation to nickel concentrations. Using in-vitro infection experiments, we demonstrate NikS affects host cell internalization and epithelial barrier disruption. Together, our results show NikS is a phase-variable, post-transcriptional global regulator of virulence properties in H. pylori.

Gastric stem cells promote inflammation and gland remodeling in response to Helicobacter pylori via Rspo3-Lgr4 axis.

Helicobacter pylori is a pathogen that colonizes the stomach and causes chronic gastritis. Helicobacter pylori can colonize deep inside gastric glands, triggering increased R-spondin 3 (Rspo3) signaling. This causes an expansion of the "gland base module," which consists of self-renewing stem cells and antimicrobial secretory cells and results in gland hyperplasia. The contribution of Rspo3 receptors Lgr4 and Lgr5 is not well explored. Here, we identified that Lgr4 regulates Lgr5 expression and is required for H. pylori-induced hyperplasia and inflammation, while Lgr5 alone is not. Using conditional knockout mice, we reveal that R-spondin signaling via Lgr4 drives proliferation of stem cells and also induces NF-κB activity in the proliferative stem cells. Upon exposure to H. pylori, the Lgr4-driven NF-κB activation is responsible for the expansion of the gland base module and simultaneously enables chemokine expression in stem cells, resulting in gland hyperplasia and neutrophil recruitment. This demonstrates a connection between R-spondin-Lgr and NF-κB signaling that links epithelial stem cell behavior and inflammatory responses to gland-invading H. pylori.

Under the Radar: Strategies Used by Helicobacter pylori to Evade Host Responses.

The body depends on its physical barriers and innate and adaptive immune responses to defend against the constant assault of potentially harmful microbes. In turn, successful pathogens have evolved unique mechanisms to adapt to the host environment and manipulate host defenses. Helicobacter pylori (Hp), a human gastric pathogen that is acquired in childhood and persists throughout life, is an example of a bacterium that is very successful at remodeling the host-pathogen interface to promote a long-term persistent infection. Using a combination of secreted virulence factors, immune subversion, and manipulation of cellular mechanisms, Hp can colonize and persist in the hostile environment of the human stomach. Here, we review the most recent and relevant information regarding how this successful pathogen overcomes gastric epithelial host defense responses to facilitate its own survival and establish a chronic infection.

The shapeshifting Helicobacter pylori: From a corkscrew to a ball.

There is growing evidence that bacterial morphology is closely related to their lifestyle. The helical Helicobacter pylori relies on its unique shape for survival and efficient colonization of the human stomach. Yet, they have been observed to transform into another distinctive morphology, the spherical coccoid. Despite being hypothesized to be involved in the persistence and transmission of this species, years of effort in deciphering the roles of the coccoid form remain fruitless since contrasting observations regarding its lifestyle were reported. Here, we discuss the two forms of H. pylori with a focus on the coccoid form, the molecular mechanism behind its morphological transformation, and experimental approaches to further develop our understanding of this phenomenon. We also propose a putative mechanism of the coccoid formation in H. pylori through induction of a type-I toxin-antitoxin (TA) system recently shown to influence the morphology of this species.

Global Prevalence of Helicobacter pylori Infection and Incidence of Gastric Cancer Between 1980 and 2022.

BACKGROUND & AIMS: We aimed to assess the secular trend of the global prevalence of Helicobacter pylori (H pylori) infection in adults and children/adolescents and to show its relation to that of gastric cancer incidence. METHODS: We performed a systematic review and meta-analysis to calculate overall prevalence, adjusted by multivariate meta-regression analysis. The incidence rates of gastric cancer were derived from the Global Burden of Disease Study and Cancer Incidence in Five Continents. RESULTS: Of the 16,976 articles screened, 1748 articles from 111 countries were eligible for analysis. The crude global prevalence of H pylori has reduced from 52.6% (95% confidence interval [CI], 49.6%-55.6%) before 1990 to 43.9% (95% CI, 42.3%-45.5%) in adults during 2015 through 2022, but was as still as high as 35.1% (95% CI, 30.5%-40.1%) in children and adolescents during 2015 through 2022. Secular trend and multivariate regression analyses showed that the global prevalence of H pylori has declined by 15.9% (95% CI, -20.5% to -11.3%) over the last 3 decades in adults, but not in children and adolescents. Significant reduction of H pylori prevalence was observed in adults in the Western Pacific, Southeast Asian, and African regions. However, H pylori prevalence was not significantly reduced in children and adolescents in any World Health Organization regions. The incidence of gastric cancer has decreased globally and in various countries where the prevalence of H pylori infection has declined. CONCLUSIONS: The global prevalence of H pylori infection has declined during the last 3 decades in adults, but not in children and adolescents. The results raised the hypothesis that the public health drive to reduce the prevalence of H pylori as a strategy to reduce the incidence of gastric cancer in the population should be confirmed in large-scale clinical trials.

Risk of Esophageal Adenocarcinoma After Helicobacter pylori Eradication Treatment in a Population-Based Multinational Cohort Study.

BACKGROUND & AIMS: Helicobacter pylori infection is associated with a decreased risk of esophageal adenocarcinoma, and the decreasing prevalence of such infection might contribute to the increasing incidence of this tumor. We examined the hypothesis that eradication treatment of H pylori increases the risk of esophageal adenocarcinoma. METHODS: This population-based multinational cohort, entitled "Nordic Helicobacter Pylori Eradication Project (NordHePEP)," included all adults (≥18 years) receiving H pylori eradication treatment from 1995-2018 in any of the 5 Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) with follow-up throughout 2019. Data came from national registers. We calculated standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) by dividing the cancer incidence in the exposed cohort by that of the entire Nordic background populations of the corresponding age, sex, calendar period, and country. Analyses were stratified by factors associated with esophageal adenocarcinoma (ie, education, comorbidity, gastroesophageal reflux, and certain medications). RESULTS: Among 661,987 participants who contributed 5,495,552 person-years after eradication treatment (median follow-up, 7.8 years; range, 1-24 years), 550 cases of esophageal adenocarcinoma developed. The overall SIR of esophageal adenocarcinoma was not increased (SIR = 0.89; 95% CI, 0.82-0.97). The SIR did not increase over time after eradication treatment, but rather decreased and was 0.73 (95% CI, 0.61-0.86) at 11-24 years after treatment. There were no major differences in the stratified analyses. The overall SIR of esophageal squamous cell carcinoma, calculated for comparison, showed no association (SIR = 0.99; 95% CI, 0.89-1.11). CONCLUSIONS: This absence on an increased risk of esophageal adenocarcinoma after eradication treatment of H pylori suggests eradication is safe from a cancer perspective.

AGA Clinical Practice Update on Integrating Potassium-Competitive Acid Blockers Into Clinical Practice: Expert Review.

DESCRIPTION: The purpose of this American Gastroenterological Association (AGA) Institute Clinical Practice Update (CPU) is to summarize the available evidence and offer expert Best Practice Advice on the integration of potassium-competitive acid blockers (P-CABs) in the clinical management of foregut disorders, specifically including gastroesophageal reflux disease, Helicobacter pylori infection, and peptic ulcer disease. METHODS: This expert review was commissioned and approved by the AGA Institute Governing Board and CPU Committee to provide timely guidance on a topic of high clinical importance to the AGA membership. This CPU expert review underwent internal peer review by the CPU Committee and external peer review through the standard procedures of Gastroenterology. These Best Practice Advice statements were developed based on review of the published literature and expert consensus opinion. Because formal systematic reviews were not performed, these Best Practice Advice statements do not carry formal ratings of the quality of evidence or strength of the presented considerations. Best Practice Advice Statements BEST PRACTICE ADVICE 1: Based on nonclinical factors (including cost, greater obstacles to obtaining medication, and fewer long-term safety data), clinicians should generally not use P-CABs as initial therapy for acid-related conditions in which clinical superiority has not been shown. BEST PRACTICE ADVICE 2: Based on current costs in the United States, even modest clinical superiority of P-CABs over double-dose proton pump inhibitors (PPIs) may not make P-CABs cost-effective as first-line therapy. BEST PRACTICE ADVICE 3: Clinicians should generally not use P-CABs as first-line therapy for patients with uninvestigated heartburn symptoms or nonerosive reflux disease. Clinicians may use P-CABs in selected patients with documented acid-related reflux who fail therapy with twice-daily PPIs. BEST PRACTICE ADVICE 4: Although there is currently insufficient evidence for clinicians to use P-CABs as first-line on-demand therapy for patients with heartburn symptoms who have previously responded to antisecretory therapy, their rapid onset of acid inhibition raises the possibility of their utility in this population. BEST PRACTICE ADVICE 5: Clinicians should generally not use P-CABs as first-line therapy in patients with milder erosive esophagitis (EE) (Los Angeles classification of erosive esophagitis grade A/B EE). Clinicians may use P-CABs in selected patients with documented acid-related reflux who fail therapy with twice-daily PPIs. BEST PRACTICE ADVICE 6: Clinicians may use P-CABs as a therapeutic option for the healing and maintenance of healing in patients with more severe EE (Los Angeles classification of erosive esophagitis grade C/D EE). However, given the markedly higher costs of the P-CAB presently available in the United States and the lack of randomized comparisons with double-dose PPIs, it is not clear that the benefits in endoscopic outcomes over standard-dose PPIs justify the routine use of P-CABs as first-line therapy. BEST PRACTICE ADVICE 7: Clinicians should use P-CABs in place of PPIs in eradication regimens for most patients with H pylori infection. BEST PRACTICE ADVICE 8: Clinicians should generally not use P-CABs as first-line therapy in the treatment or prophylaxis of peptic ulcer disease. BEST PRACTICE ADVICE 9: Although there is currently insufficient evidence for clinicians to use P-CABs as first-line therapy in patients with bleeding gastroduodenal ulcers and high-risk stigmata, their rapid and potent acid inhibition raises the possibility of their utility in this population.

Unveiling Cancer-Related Metaplastic Cells in Both Helicobacter pylori Infection and Autoimmune Gastritis.

BACKGROUND & AIMS: Gastric metaplasia may arise as a consequence of chronic inflammation and is associated with an increased risk of gastric cancer development. Although Helicobacter pylori (Hp) infection and autoimmune gastritis (AIG) both induce gastric metaplasia, possible distinctions in resulting metaplastic cells and their respective cancer risks requires further investigation. METHODS: Using both mouse models and human participants, we scrutinized the metaplasia originating from Hp infection and AIG. Gastric pathology and metaplasia were examined through histopathologic assessment. Molecular features of metaplastic cells were defined using single-cell transcriptomics in murine models of Hp infection and AIG, as well as in human biopsy specimens from patients with Hp infection and AIG. Expression of a newly defined cancer-related metaplastic biomarker was confirmed through immunofluorescence. RESULTS: Metaplasia in Hp infection and AIG displayed comparable histopathologic and transcriptional features. Diverse metaplastic subtypes were identified across both disease settings, with subtle differences in the prevalence of certain subtypes between inflammatory contexts. Notably, Hp infection did not drive a unique metaplastic cell phenotype. One metaplastic subtype, which resembled incomplete intestinal metaplasia and shared transcriptional features with gastric cancer, was identified in both diseases. This cancer-like metaplastic subtype was characterized by expression of the cancer-associated biomarker alanyl aminopeptidase N/CD13. CONCLUSION: Both Hp infection and AIG trigger a diverse array of metaplastic cell types. Identification of a cancer-related metaplastic cell uniquely expressing alanyl aminopeptidase N/CD13, present in both Hp- and AIG-induced gastritis, indicates the carcinogenic capacity of both diseases. This discovery can guide early detection and risk stratification for patients with chronic gastritis.