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.

Peptidoglycan crosslinking relaxation promotes Helicobacter pylori's helical shape and stomach colonization.

The mechanisms by which bacterial cells generate helical cell shape and its functional role are poorly understood. Helical shape of the human pathogen Helicobacter pylori may facilitate penetration of the thick gastric mucus where it replicates. We identified four genes required for helical shape: three LytM peptidoglycan endopeptidase homologs (csd1-3) and a ccmA homolog. Surrounding the cytoplasmic membrane of most bacteria, the peptidoglycan (murein) sacculus is a meshwork of glycan strands joined by peptide crosslinks. Intact cells and isolated sacculi from mutants lacking any single csd gene or ccmA formed curved rods and showed increased peptidoglycan crosslinking. Quantitative morphological analyses of multiple-gene deletion mutants revealed each protein uniquely contributes to a shape-generating pathway. This pathway is required for robust colonization of the stomach in spite of normal directional motility. Our findings suggest that the coordinated action of multiple proteins relaxes peptidoglycan crosslinking, enabling helical cell curvature and twist.

Genomic insights into the antimicrobial resistance and virulence of Helicobacter pylori isolates from gastritis patients in Pereira, Colombia.

BACKGROUND: Helicobacter pylori infects the stomach and/or small intestines in more than half of the human population. Infection with H. pylori is the most common cause of chronic gastritis, which can lead to more severe gastroduodenal pathologies such as peptic ulcer, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. H. pylori infection is particularly concerning in Colombia in South America, where > 80% of the population is estimated to be infected with H. pylori and the rate of stomach cancer is one of the highest in the continent. RESULTS: We compared the antimicrobial susceptibility profiles and short-read genome sequences of five H. pylori isolates obtained from patients diagnosed with gastritis of varying severity (chronic gastritis, antral erosive gastritis, superficial gastritis) in Pereira, Colombia sampled in 2015. Antimicrobial susceptibility tests revealed the isolates to be resistant to at least one of the five antimicrobials tested: four isolates were resistant to metronidazole, two to clarithromycin, two to levofloxacin, and one to rifampin. All isolates were susceptible to tetracycline and amoxicillin. Comparative genome analyses revealed the presence of genes associated with efflux pump, restriction modification systems, phages and insertion sequences, and virulence genes including the cytotoxin genes cagA and vacA. The five genomes represent three novel sequence types. In the context of the Colombian and global populations, the five H. pylori isolates from Pereira were phylogenetically distant to each other but were closely related to other lineages circulating in the country. CONCLUSIONS: H. pylori from gastritis of different severity varied in their antimicrobial susceptibility profiles and genome content. This knowledge will be useful in implementing appropriate eradication treatment regimens for specific types of gastritis. Understanding the genetic and phenotypic heterogeneity in H. pylori across the geographical landscape is critical in informing health policies for effective disease prevention and management that is most effective at local and country-wide scales. This is especially important in Colombia and other South American countries that are poorly represented in global genomic surveillance studies of bacterial pathogens.

Antibiotic resistance and virulence genes in Helicobacter pylori strains isolated from children in Shanghai, China (2019-2022).

BACKGROUND: The increasing prevalence of antibiotic-resistant Helicobacter pylori strains poses a significant threat to children's health. This study investigated antibiotic resistance rates in Helicobacter pylori strains isolated from children in Shanghai and analyzed the presence of virulence genes in these strains. METHODS: We obtained 201 Helicobacter pylori strains from pediatric patients with upper gastrointestinal symptoms who underwent gastrointestinal endoscopy between 2019 and 2022. Subsequently, we performed antibiotic susceptibility tests and virulence gene PCR assays on these strains. RESULTS: Helicobacter pylori resistance rates of 45.8%, 15.4%, 1.0%, and 2.5% were detected for metronidazole, clarithromycin, amoxicillin, and levofloxacin, respectively. Among all isolates, 64.7% exhibited resistance to at least one antibiotic. Resistance to metronidazole and clarithromycin increased from 2019 to 2022. The predominant vacA gene subtype was vacA s1a/m2. The prevalence of vacA m2 and dupA exhibited an upward trend, while oipA presented a decreasing trend from 2019 to 2022. The prevalence of dupA was significantly higher in gastritis than peptic ulcer disease, and in non-treatment compared to treatment groups. CONCLUSIONS: Helicobacter pylori antibiotic resistance remains high in children and has risen in recent years. Therefore, the increasing use of metronidazole and clarithromycin requires increased monitoring in children. No association was observed between antibiotic resistance and virulence gene phenotypes.

Insights into the molecular mechanisms of H. pylori-associated B-cell lymphoma.

Cancer research has extensively explored various factors contributing to cancer development, including chemicals, drugs, smoking, and obesity. However, the role of bacterial infections in cancer induction remains underexplored. In particular, the mechanisms underlying H. pylori-induced B-cell lymphoma, a potential consequence of bacterial infection, have received little attention. In recent years, there has been speculation about contagious agents causing persistent inflammation and encouraging B-lymphocyte transition along with lymphomagenesis. MALT lymphoma associated with chronic H. pylori infection, apart from two other central associated lymphomas - Burkitt's Lymphoma and DLBCL, is well studied. Owing to the increasing colonization of H. pylori in the host gut and its possible action in the development of B-cell lymphoma, this review aims to summarize the existing reports on different B-cell lymphomas' probable association with H. pylori infections; also emphasizing the function of the organism in lymphomagenesis; including its interaction with the host, pathogen and host-specific factors, and tumor microenvironment.

Helicobacter pylori infection promotes liver injury through an exosome-mediated mechanism.

Helicobacter pylori infection has been thought to be associated with liver diseases, although the exact mechanisms remain elusive. This study identified H. pylori-induced liver inflammation and tissue damage in infected mice and examined the exosome-mediated mechanism underlying H. pylori infection's impact on liver injury. Exosomes were isolated from H. pylori-infected gastric epithelial GES-1 cells (Hp-GES-EVs), and the crucial virulence factor CagA was identified within these exosomes. Fluorescent labeling demonstrated that Hp-GES-EVs can be absorbed by liver cells. Treatment with Hp-GES-EVs enhanced the proliferation, migration, and invasion of Hep G2 and Hep 3B cells. Additionally, exposure to Hp-GES-EVs activated NF-κB and PI3K/AKT signaling pathways, which provides a reasonable explanation for the liver inflammation and neoplastic traits. Using a mouse model established via tail vein injection of Hp-GES-EVs, exosome-driven liver injury was evidenced by slight hepatocellular erosion around the central hepatic vein and elevated serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and IL-6. Administering the exosome inhibitor GW4869 via intraperitoneal injection in mice resulted in a reduction of liver damage caused by H. pylori infection. These findings illuminate the exosome-mediated pathogenesis of H. pylori-induced liver injury and offer valuable insights into the extra-gastrointestinal manifestations of H. pylori infection.

The Interplay Between Helicobacter pylori and Suppressors of Cytokine Signaling (SOCS) Molecules in the Development of Gastric Cancer and Induction of Immune Response.

Helicobacter pylori (H. pylori) colonizes the stomach and leads to the secretion of a vast range of cytokines by infiltrated leukocytes directing immune/inflammatory response against the bacterium. To regulate immune/inflammatory responses, suppressors of cytokine signaling (SOCS) proteins bind to multiple signaling components located downstream of cytokine receptors, such as Janus kinase (JAK), signal transducers and activators of transcription (STAT). Dysfunctional SOCS proteins in immune cells may facilitate the immune evasion of H. pylori, allowing the bacteria to induce chronic inflammation. Dysregulation of SOCS expression and function can contribute to the sustained H. pylori-mediated gastric inflammation which can lead to gastric cancer (GC) development. Among SOCS molecules, dysregulated expression of SOCS1, SOCS2, SOCS3, and SOCS6 were indicated in H. pylori-infected individuals as well as in GC tissues and cells. H. pylori-induced SOCS1, SOCS2, SOCS3, and SOCS6 dysregulation can contribute to the GC development. The expression of SOCS molecules can be influenced by various factors, such as epigenetic DNA methylation, noncoding RNAs, and gene polymorphisms. Modulation of the expression of SOCS molecules in gastric epithelial cells and immune cells can be considered to control gastric carcinogenesis as well as regulate antitumor immune responses, respectively. This review aimed to explain the interplay between H. pylori and SOCS molecules in GC development and immune response induction as well as to provide insights regarding potential therapeutic strategies modulating SOCS molecules.

Effect of Lactobacillus gasseri BIO6369 and Lacticaseibacillus rhamnosus BIO5326 on Gastric Carcinogenesis Induced by Helicobacter pylori Infection.

BACKGROUND: Helicobacter pylori infection-associated gastric adenocarcinoma is influenced by various factors, including the digestive microbiota. Lactic acid bacteria role in digestive carcinogenesis has been discussed, and some Lactobacillaceae family species have been shown to act against H. pylori-induced inflammation and colonization. However, their effects on H. pylori-related carcinogenesis have not yet been studied. Lactobacillaceae family effects on the epithelial-to-mesenchymal transition (EMT), emergence of cells with cancer stem cell (CSC) properties and the pro-inflammatory response of gastric epithelial cells to H. pylori infection were investigated. MATERIALS AND METHODS: A co-culture model of AGS gastric epithelial cells infected with a carcinogenic strain of H. pylori associated with 18 different probiotic strains candidates were used. Different EMT indicators and CSC properties were studied, including quantification of the mesenchymal phenotype, tumorsphere formation, EMT marker expression, and tight junction evaluation with immunofluorescence microscopy. The effect of the strains on the pro-inflammatory response to H. pylori was also evaluated by quantifying interleukin-8 (IL-8) production using ELISA. RESULTS: Among the strains tested, Lactobacillus gasseri BIO6369 and Lacticaseibacillus rhamnosus BIO5326 induced a 30.6% and 38.4% reduction in the mesenchymal phenotype, respectively, caused a significant decrease in Snail and Zeb1 EMT marker expression and prevented the loss of tight junctions induced by H. pylori infection. A separate co-culture with a Boyden chamber maintained the effects induced by the two strains. H. pylori-induced IL-8 production was also significantly reduced in the presence of L. gasseri BIO6369 and L. rhamnosus BIO5326. CONCLUSION: Lactobacillus gasseri BIO6369 and L. rhamnosus BIO5326 strains decreased epithelial-to-mesenchymal transition and inflammation induced by H. pylori infection, suggesting that these species may have a protective effect against H. pylori-induced gastric carcinogenesis.

Helicobacter pylori with trx1 high expression promotes gastric diseases via upregulating the IL23A/NF-κB/IL8 pathway.

BACKGROUND: Helicobacter pylori infection is one of the main causes of gastric cancer. thioredoxin-1 (Trx1) and arginase (RocF) expressed by H. pylori were found to be closely related to its pathogenicity. However, whether Trx1 and RocF can be used in clinical screening of highly pathogenic H. pylori and the pathogenesis of trx1 high expressing H. pylori remain still unknown. MATERIALS AND METHODS: We investigated the expression level of H. pylori trx1 and H. pylori rocF in human gastric antrum tissues using reverse transcription and quantitative real-time PCR (RT-qPCR) and clarified the clinical application value of trx1 and rocF for screening highly pathogenic H. pylori. The pathogenic mechanism of Trx1 were further explored by RNA-seq of GES-1 cells co-cultured with trx1 high or low expressing H. pylori. Differentially expressed genes and signaling pathways were validated by RT-qPCR, Enzyme-linked immunosorbent assay (ELISA), western blot, immunohistochemistry and immunofluorescence. We also assessed the adherence of trx1 high and low expressing H. pylori to GES-1 cells. RESULTS: We found that H. pylori trx1 and H. pylori rocF were more significantly expressed in the gastric cancer and peptic ulcer group than that in the gastritis group and the parallel diagnosis of H. pylori trx1 and H. pylori rocF had high sensitivity. The trx1 high expressing H. pylori had stronger adhesion ability to GES-1 cells and upregulated the interleukin (IL) 23A/nuclear factor κappaB (NF-κB)/IL17A, IL6, IL8 pathway. CONCLUSIONS: H. pylori trx1 and H. pylori rocF can be used in clinical screening of highly pathogenic H. pylori and predicting the outcome of H. pylori infection. The trx1 high expressing H. pylori has stronger adhesion capacity and promotes the development of gastric diseases by upregulating the activation of NF-κB signaling pathway.

Genomic analysis of Helicobacter pylori in Australia: Antimicrobial resistance, phylogenetic patterns, and virulence factors.

BACKGROUND AND AIM: Rates of antimicrobial-resistant Helicobacter pylori infection are rising globally, but little is known about contemporary resistance patterns, virulence factors, and phylogenetic patterns of isolates within Australia. We aimed to characterize antimicrobial resistance and genetic mutations associated with adverse clinical outcomes. METHODS: Whole genome sequencing, culturing, and antibiotic sensitivity data for refractory H. pylori isolates at Australian centers were collected between 2013 and 2022. Phylogenetic origins, antibiotic resistance mutations, and virulence factors were examined with phenotypic resistance profiles. RESULTS: One hundred thirty-five isolates underwent culture, with 109 of these undergoing whole genome sequencing. Forty-three isolates were isolated from patients in South Australia and 66 from Western Australia. Isolates originated primarily from hpEurope (59.6%), hpEastAsia (25.7%), and hpNEAfrica (6.4%). Antimicrobial resistance to clarithromycin was seen in 85% of isolates, metronidazole in 52%, levofloxacin in 18%, rifampicin in 14%, and amoxicillin in 9%. Most isolates (59%) were multi-drug resistant. Resistance concordance between genetically determined resistance and phenotypic resistance was 92% for clarithromycin and 94% for levofloxacin. Analysis of virulence factors demonstrated cag pathogenicity island (cagPAI) in 67% of isolates and cagA in 61%, correlating with isolate genetic origin. The most virulent s1m1 vacuolating cytotoxin A genotype was present in 26% of isolates. CONCLUSION: Refractory H. pylori isolates in Australia emanate from multiple global origins. Strong concordance between genetic and phenotypic antibiotic resistance profiles raises the possibility of utilizing genetic profiling in clinical practice. The dynamic landscape of H. pylori in Australia warrants the establishment of a national database to monitor H. pylori resistance and evolving virulence.

Extent of Virulence and Antibiotic Resistance Genes in Helicobacter pylori and Campylobacteria.

Helicobacter pylori, a member of the clade campylobacteria, is the leading cause of chronic gastritis and gastric cancer. Virulence and antibiotic resistance of H. pylori are of great concern to public health. However, the relationship between virulence and antibiotic resistance genes in H. pylori in relation to other campylobacteria remains unclear. Using the virulence and comprehensive antibiotic resistance databases, we explored all available 354 complete genomes of H. pylori and compared it with 90 species of campylobacteria for virulence and antibiotic resistance genes/proteins. On average, H. pylori had 129 virulence genes, highest among Helicobacter spp. and 71 antibiotic resistance genes, one of the lowest among campylobacteria. Just 2.6% of virulence genes were shared by all campylobacterial members, whereas 9.4% were unique to H. pylori. The cytotoxin-associated genes (cags) seemed to be exclusive to H. pylori. Majority of the isolates from Asia and South America were cag2-negative and many antibiotic resistance genes showed isolate-specific patterns of occurrence. Just 15 (8.8%) antibiotic resistance genes, but 103 (66%) virulence genes including 25 cags were proteomically identified in H. pylori. Arcobacterial members showed large variation in the number of antibiotic resistance genes and there was a positive relation with the genome size. Large repository of antibiotic resistance genes in campylobacteria and a unique set of virulence genes might have important implications in shaping the course of virulence and antibiotic resistance in H. pylori.

Meta-analysis of the Correlation between Helicobacter Pylori Infection and the risk of Colorectal Neoplasia.

Objective: To study the association of H. pylori infection with colorectal adenomas. Methods: Web searches of PubMed, Embase, and Scopus databases for randomized controlled trials, class-experimental studies, and cohort studies on the association between H. pylori and colorectal adenomas were performed from May 2000 to May 2023. Literature was screened based on inclusion and exclusion criteria, data were extracted and evaluated for quality, and statistical analyses were performed using RevMan 5.2 software. Results: A total of 15 studies were included, and meta-analysis showed a statistically significant difference between colorectal neoplastic polyp cases in the H. pylori-positive and H. pylori-negative groups [OR=1.80, 95%CI: (1.31, 2.47), P < .01, I2 = 95%]. Analysis based on subgroups of different H. pylori detection methods showed that the correlation between H. pylori infection and colorectal polyp incidence is not affected by their detection methods, with serological detection subgroup: [OR=0.13, 95%CI: (0.05, 0.21), P < .01, I2 = 88%], and non-serological detection subgroup: [OR=0.13, 95%CI: (0.04, 0.22), P < .01, I2 = 95%]. Subgroup analysis of pathological types showed that H. pylori infection is not significantly associated with the development of non-neoplastic polyps [OR=1.47, 95%CI: 0.98-2.22, P = .06], whereas it is correlated with the development of neoplastic polyps [95%CI: 1.69-3.22, P < .01]. In the subgroup analysis of geographic differences in the population, H. pylori infection was correlated with the development of colorectal polyps in different geographic populations (P < .01). Conclusion: H. pylori infection is a risk factor for colorectal polyp neoplasia, its infection is associated with colorectal neoplasia, and the correlation is not affected by the different methods of H. pylori detection and the different geographic regions of the population.

The Impact of Tobacco Smoking and Alcohol Consumption on the Development of Gastric Cancers.

Chronic infection of Helicobacter pylori is considered the principal cause of gastric cancers, but evidence has accumulated regarding the impact of tobacco smoking and alcohol consumption on the development of gastric cancers. Several possible mechanisms, including the activation of nicotinic acetylcholine receptors, have been proposed for smoking-induced gastric carcinogenesis. On the other hand, local acetaldehyde exposure and ethanol-induced mucosal inflammation have been proposed as the mechanisms involved in the development of gastric cancers in heavy alcohol drinkers. In addition, genetic polymorphisms are also considered to play a pivotal role in smoking-related and alcohol-related gastric carcinogenesis. In this review, we will discuss the molecular mechanisms involved in the development of gastric cancers in relation to tobacco smoking and alcohol consumption.

Gastric Carcinogenesis and Potential Role of the Transient Receptor Potential Vanilloid 1 (TRPV1) Receptor: An Observational Histopathological Study.

The potential role of the transient receptor potential Vanilloid 1 (TRPV1) non-selective cation channel in gastric carcinogenesis remains unclear. The main objective of this study was to evaluate TRPV1 expression in gastric cancer (GC) and precursor lesions compared with controls. Patient inclusion was based on a retrospective review of pathology records. Patients were subdivided into five groups: Helicobacter pylori (H. pylori)-associated gastritis with gastric intestinal metaplasia (GIM) (n = 12), chronic atrophic gastritis (CAG) with GIM (n = 13), H. pylori-associated gastritis without GIM (n = 19), GC (n = 6) and controls (n = 5). TRPV1 expression was determined with immunohistochemistry and was significantly higher in patients with H. pylori-associated gastritis compared with controls (p = 0.002). TRPV1 expression was even higher in the presence of GIM compared with patients without GIM and controls (p < 0.001). There was a complete loss of TRPV1 expression in patients with GC. TRPV1 expression seems to contribute to gastric-mucosal inflammation and precursors of GC, which significantly increases in cancer precursor lesions but is completely lost in GC. These findings suggest TRPV1 expression to be a potential marker for precancerous conditions and a target for individualized treatment. Longitudinal studies are necessary to further address the role of TRPV1 in gastric carcinogenesis.

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, ß-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.

HELICOBACTER PYLORI AND GALLBLADDER PATHOLOGIES: IS THERE A CAUSE-AND-EFFECT RELATIONSHIP?

The relationship between Helicobacter pylori infection and gallbladder diseases, particularly cholecystitis and gallbladder polyps, remains unclear. This study aimed to investigate the presence of H. pylori in gallbladder tissues and its potential role in gallbladder pathologies, as well as to examine the expression of chemokines CXCL2 and CXCL5 in these conditions. MATERIAL AND METHODS: A total of 137 laparoscopically excised gallbladders were analysed through histological examination, PCR for H. pylori-specific DNA, and quantitative real-time PCR for CXCL2 and CXCL5 gene expression. The study cohort included patients with acute calculous cholecystitis, chronic calculous cholecystitis, and gallbladder polyps. RESULTS: H. pylori was detected in 30.7% of cases by histological methods and 42.3% by PCR. Elevated expression of CXCL2 and CXCL5 was observed in 62% and 57.7% of cases, respectively, with a higher prevalence in acute cholecystitis compared to chronic conditions. However, no statistically significant association was found between H. pylori presence and the forms of cholecystitis, as well as between H. pylori presence and chemokine expression in gallbladder. CONCLUSIONS: The study did not establish a direct link between the presence of H. pylori infection and forms of gallbladder pathologies. The findings suggest that other factors other than H. pylori may contribute to the upregulation of CXCL2 and CXCL5 in gallbladder diseases. Further research is needed to elucidate the complex interactions between H. pylori, chemokines, and gallbladder pathologies.

Small RNAs that target G-rich sequences are generated by diverse biogenesis pathways in Epsilonproteobacteria.

Bacterial small RNAs (sRNAs) are widespread post-transcriptional regulators that control bacterial stress responses and virulence. Nevertheless, little is known about how they arise and evolve. Homologs can be difficult to identify beyond the strain level using sequence-based approaches, and similar functionalities can arise by convergent evolution. Here, we found that the virulence-associated CJnc190 sRNA of the foodborne pathogen Campylobacter jejuni resembles the RepG sRNA from the gastric pathogen Helicobacter pylori. However, while both sRNAs bind G-rich sites in their target mRNAs using a C/U-rich loop, they largely differ in their biogenesis. RepG is transcribed from a stand-alone gene and does not require processing, whereas CJnc190 is transcribed from two promoters as precursors that are processed by RNase III and also has a cis-encoded antagonist, CJnc180. By comparing CJnc190 homologs in diverse Campylobacter species, we show that RNase III-dependent processing of CJnc190 appears to be a conserved feature even outside of C. jejuni. We also demonstrate the CJnc180 antisense partner is expressed in C. coli, yet here might be derived from the 3'UTR (untranslated region) of an upstream flagella-related gene. Our analysis of G-tract targeting sRNAs in Epsilonproteobacteria demonstrates that similar sRNAs can have markedly different biogenesis pathways.

Induction of MMP-3 and MMP-9 expression during Helicobacter pylori infection via MAPK signaling pathways.

BACKGROUND AND AIMS: Helicobacter pylori (H. pylori)-induced gastric pathology involves remodeling of extracellular matrix mediated by aberrant activity of matrix metalloproteinases (MMPs). We have previously shown that in vitro H. pylori infection leads to MMP-3 and MMP-9 overexpression, associated with phosphorylation of bacterial oncoprotein CagA. We extended these findings in an in vivo model of H. pylori infection and further assessed the involvement of MAPK pathways in MMP expression. MATERIALS AND METHODS: C57BL/6 mice were infected with H. pylori strains HPARE, HPARE ΔCagA, and SS1, for 6 and 9 months. Transcriptional expression of Mmp-3 and Mmp-9 was evaluated via qPCR while respective protein levels in the gastric mucosa were determined immunohistochemically. Epithelial cell lines AGS and GES-1 were infected with H. pylori strain P12 in the presence of chemical inhibitors of JNK, ERK1/2, and p38 pathways, for 24 h. mRNA and protein expression of MMP-3 and MMP-9 were determined via qPCR and Western blot, respectively. RESULTS: We observed transcriptional activation of Mmp-3 and Mmp-9 as well as aberrant MMP-3 and MMP-9 protein expression in murine gastric tissue following H. pylori infection. CagA expression was associated with MMP upregulation, particularly during the early time points of infection. We found that inhibition of ERK1/2 resulted in reduced mRNA and protein expression of MMP-3 and MMP-9 during H. pylori infection, in both cell lines. Expressed protein levels of both MMPs were also found reduced in the presence of JNK pathway inhibitors in both cell lines. However, p38 inhibition resulted in a more complex effect, probably attributed to the accumulation of phospho-p38 and increased phospho-ERK1/2 activity due to crosstalk between MAPK pathways. CONCLUSIONS: H. pylori colonization leads to the upregulation of MMP-3 and MMP-9 in vivo, which primarily involves ERK1/2 and JNK pathways. Therefore, their inhibition may potentially offer a protective effect against gastric carcinogenesis and metastasis.

Stromal R-spondin orchestrates gastric epithelial stem cells and gland homeostasis.

The constant regeneration of stomach epithelium is driven by long-lived stem cells, but the mechanism that regulates their turnover is not well understood. We have recently found that the gastric pathogen Helicobacter pylori can activate gastric stem cells and increase epithelial turnover, while Wnt signalling is known to be important for stem cell identity and epithelial regeneration in several tissues. Here we find that antral Wnt signalling, marked by the classic Wnt target gene Axin2, is limited to the base and lower isthmus of gastric glands, where the stem cells reside. Axin2 is expressed by Lgr5+ cells, as well as adjacent, highly proliferative Lgr5- cells that are able to repopulate entire glands, including the base, upon depletion of the Lgr5+ population. Expression of both Axin2 and Lgr5 requires stroma-derived R-spondin 3 produced by gastric myofibroblasts proximal to the stem cell compartment. Exogenous R-spondin administration expands and accelerates proliferation of Axin2+/Lgr5- but not Lgr5+ cells. Consistent with these observations, H. pylori infection increases stromal R-spondin 3 expression and expands the Axin2+ cell pool to cause hyperproliferation and gland hyperplasia. The ability of stromal niche cells to control and adapt epithelial stem cell dynamics constitutes a sophisticated mechanism that orchestrates epithelial regeneration and maintenance of tissue integrity.