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.

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.

Helicobacter pylori CagA protein induces gastric cancer stem cell-like properties through the Akt/FOXO3a axis.

The presence of Helicobacter pylori (H. pylori) infection poses a substantial risk for the development of gastric adenocarcinoma. The primary mechanism through which H. pylori exerts its bacterial virulence is the cytotoxin CagA. This cytotoxin has the potential to induce inter-epithelial mesenchymal transition, proliferation, metastasis, and the acquisition of stem cell-like properties in gastric cancer (GC) cells infected with CagA-positive H. pylori. Cancer stem cells (CSCs) represent a distinct population of cells capable of self-renewal and generating heterogeneous tumor cells. Despite evidence showing that CagA can induce CSCs-like characteristics in GC cells, the precise mechanism through which CagA triggers the development of GC stem cells (GCSCs) remains uncertain. This study reveals that CagA-positive GC cells infected with H. pylori exhibit CSCs-like properties, such as heightened expression of CD44, a specific surface marker for CSCs, and increased ability to form tumor spheroids. Furthermore, we have observed that H. pylori activates the PI3K/Akt signaling pathway in a CagA-dependent manner, and our findings suggest that this activation is associated with the CSCs-like characteristics induced by H. pylori. The cytotoxin CagA, which is released during H. pylori infection, triggers the activation of the PI3K/Akt signaling pathway in a CagA-dependent manner. Additionally, CagA inhibits the transcription of FOXO3a and relocates it from the nucleus to the cytoplasm by activating the PI3K/Akt pathway. Furthermore, the regulatory function of the Akt/FOXO3a axis in the transformation of GC cells into a stemness state was successfully demonstrated.

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.

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.

Associations between biofilm formation and virulence factors among clinical Helicobacter pylori isolates.

INTRODUCTION: Helicobacter pylori (H. pylori) causes several gastrointestinal diseases. Its virulence factors contributing to disease development include biofilm formation, cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) proteins that induce host tissue damage. In addition, urease activity enables H. pylori growth in the gastric acidic environment. This work aimed to characterize bacterial factors associated with biofilm production among 89 clinical H. pylori isolates, collected from patient gastric biopsies. METHODS: Biofilm production was detected using the crystal violet method. PCR was performed to determine vacA genotype (s1m1, s1m2, s2m1 and s2m2) and cagA gene presence. Urease activity was measured via the phenol red method. Susceptibility to six antibiotics was assessed by the Etest method. RESULTS: Most H. pylori isolates produced biofilm. No association was found between biofilm-formation capacity and cagA presence or vacA genotype. Urease activity levels varied across isolates; no association was found between biofilm-formation and urease activity. Clarithromycin resistance was measured in 49 % of the isolates. Isolates susceptible to tetracycline were more commonly strong biofilm producers. In contrast, a significantly higher rate of strong biofilm producers was observed among resistant isolates to amoxicillin, levofloxacin and rifampicin, compared to susceptible isolates. Non-biofilm producers were more common among isolates sensitive to rifampicin and metronidazole, compared to resistant isolates. CONCLUSIONS: Further studies are needed to understand the factors that regulate biofilm production in order to search for treatments for H. pylori biofilm destruction.

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.

Antagonizing roles of SHP1 in the pathogenesis of Helicobacter pylori infection.

BACKGROUND: SHP1 has been documented as a tumor suppressor and it was thought to play an antagonistic role in the pathogenesis of Helicobacter pylori infection. In this study, the exact mechanism of this antagonistic action was studied. MATERIALS AND METHODS: AGS, MGC803, and GES-1 cells were infected with H. pylori, intracellular distribution changes of SHP1 were first detected by immunofluorescence. SHP1 overexpression and knockdown were then constructed in these cells to investigate its antagonistic roles in H. pylori infection. Migration and invasion of infected cells were detected by transwell assay, secretion of IL-8 was examined via ELISA, the cells with hummingbird-like alteration were determined by microexamination, and activation of JAK2/STAT3, PI3K/Akt, and ERK pathways were detected by immunoblotting. Mice infection model was established and gastric pathological changes were evaluated. Finally, the SHP1 activator sorafenib was used to analyze the attenuating effect of SHP1 activation on H. pylori pathogenesis in vitro and in vivo. RESULTS: The sub-localization of SHP1 changed after H. pylori infection, specifically that the majority of the cytoplasmic SHP1 was transferred to the cell membrane. SHP1 inhibited H. pylori-induced activation of JAK2/STAT3 pathway, PI3K/Akt pathway, nuclear translocation of NF-κB, and then reduced EMT, migration, invasion, and IL-8 secretion. In addition, SHP1 inhibited the formation of CagA-SHP2 complex by dephosphorylating phosphorylated CagA, reduced ERK phosphorylation and the formation of CagA-dependent hummingbird-like cells. In the mice infection model, gastric pathological changes were observed and increased IL-8 secretion, indicators of cell proliferation and EMT progression were also detected. By activating SHP1 with sorafenib, a significant curative effect against H. pylori infection was obtained in vitro and in vivo. CONCLUSIONS: SHP1 plays an antagonistic role in H. pylori pathogenesis by inhibiting JAK2/STAT3 and PI3K/Akt pathways, NF-κB nuclear translocation, and CagA phosphorylation, thereby reducing cell EMT, migration, invasion, IL-8 secretion, and hummingbird-like changes.

Helicobacter pylori CagA Promotes the Formation of Gallstones by Increasing the Permeability of Gallbladder Epithelial Cells.

BACKGROUND: The formation of gallstones is often accompanied by chronic inflammation, and the mechanisms underlying inflammation and stone formation are not fully understood. Our aim is to utilize single-cell transcriptomics, bulk transcriptomics, and microbiome data to explore key pathogenic bacteria that may contribute to chronic inflammation and gallstone formation, as well as their associated mechanisms. METHODS: scRNA-seq data from a gallstone mouse model were extracted from the Gene Expression Omnibus (GEO) database and analyzed using the FindCluster() package for cell clustering analysis. Bulk transcriptomics data from patients with gallstone were also extracted from the GEO database, and intergroup functional differences were assessed using GO and KEGG enrichment analysis. Additionally, 16S rRNA sequencing was performed on gallbladder mucosal samples from asymptomatic patients with gallstone (n = 6) and liver transplant donor gallbladder mucosal samples (n = 6) to identify key bacteria associated with stone formation and chronic inflammation. Animal models were constructed to investigate the mechanisms by which these key pathogenic bacterial genera promote gallstone formation. RESULTS: Analysis of scRNA-seq data from the gallstone mouse model (GSE179524) revealed seven distinct cell clusters, with a significant increase in neutrophil numbers in the gallstone group. Analysis of bulk transcriptomics data from patients with gallstone (GSE202479) identified chronic inflammation in the gallbladder, potentially associated with dysbiosis of the gallbladder microbiota. 16S rRNA sequencing identified Helicobacter pylori as a key bacterium associated with gallbladder chronic inflammation and stone formation. CONCLUSIONS: Dysbiosis of the gallbladder mucosal microbiota is implicated in gallstone disease and leads to chronic inflammation. This study identified H. pylori as a potential key mucosal resident bacterium contributing to gallstone formation and discovered its key pathogenic factor CagA, which causes damage to the gallbladder mucosal barrier. These findings provide important clues for the prevention and treatment of gallstones.

New strategies for Helicobacter pylori isolation and sequencing analysis for virulence genes contributing to its pathogenicity.

BACKGROUND: Helicobacter pylori is a fastidious pathogen that is required a complicated medium for growth. Invading epithelial cells of the stomach. H. pylori virulence factors are classified by function, acidic resistivity, adhesion, chemotaxis and motility, molecular mimicry, immunological invasion and modulation, and toxins formation such as cytotoxin-associated genes A (cagA) and vacuolating cytotoxin A (vacA). This study aims to determine a simple and innovative technique to isolate H. pylori from gastric biopsies and assess pathogenicity by virulence factor gene detection. METHODS: A total of 200 patients who were suspected of having H. pylori infection had two antral gastric biopsies undertaken. A rapid urease test (RUT) was used for one, and Brain Heart Infusion broth (BHI) was used to cultivate the other. The molecular study included diagnostics utilizing the 16sRNA housekeeping gene along with the identification of the virulence factors genes (cagA, cagT, and vacA) and sequencing, RESULT: Of the 200 antral gastric biopsies collected, 135 were positive rapid urease tests, and 17 H. pylori isolates were successfully obtained from 135 biopsies. The 16SrRNA as a housekeeping gene is confirmed, and about 53%, 70.5%, and 82.3% of the 17 isolates show carrying cagA, cagT, and vacA genes, respectively. All peptic ulcer isolates have the cagA gene, while Gastroesophageal Reflux Disease (GERD) and non-peptic ulcer disease (NPUD) isolates show the lack of the cagA gene. All bacteria, which were isolated from peptic ulcer, nodular gastritis, and gastritis patients, have a vacA gene. CONCLUSION: The effective method for isolating H. pylori is centrifuging the transport broth after 24 h of incubation. The cagA toxin causes peptic ulcer while vacA toxin induces several histopathological changes in the stomach. Three virulence genes were present in all peptic ulcer-causing bacteria, while only one or none were present in the GERD and NPUD biopsy isolates.

Helicobacter pylori induce circ_0046854 to regulate microRNA-511-3p/CSF1 axis and enhance the resistance of gastric cancer to cisplatin.

Helicobacter pylori (HP) is considered a major risk factor for gastric cancer (GC) and during this process, cytotoxin­associated gene A (CagA) plays in essence. The study mainly focused on the molecular mechanism of circular RNA 0046854 (circ_0046854) in HP-induced GC. Clinically, 56 cases of GC and normal tissues were collected, and the GC tissues were divided into HP-negative GC tissues (HP-) and 33 HP-positive GC tissues (HP+). Tissue expression of circ_0046854, microRNA (miR)-511-3p and colony-stimulating factor 1 (CSF1) was tested. BGC-823/Cisplatin (DDP) resistant strain was induced and cell growth and DDP resistance were detected after HP infection. In vivo experiments were performed using a mouse xenograft model. The relationship between circ_0046854, miR-511-3p and CSF1 was confirmed. GC tissues especially HP+ cancer tissues expressed high circ_0046854 and CSF1 and low miR-511-3p. HP-induced circ_0046854 expression in GC cells through CagA. Inhibition of circ_0046854 or miR-511-3p elevation inhibited the growth and DDP resistance in GC cells. Circ_0046854 acted as a sponge for miR-511-3p, which targeted CSF1. Restoring CSF1 could abolish the inhibitory effect of miR-511-3p overexpression on CagA+ HP-induced GC progression in vitro. Circ_0046854 silencing repressed tumor growth and aggrandized the inhibiting effects of DDP on tumorigenesis in vivo. Circ_0046854/miR-511-3p/CSF1 axis may be involved in the development of HP-induced GC, thus providing new ideas for studying the mechanism of HP-related gastric diseases.

Causal association between helicobacter pylori and atherosclerosis: a two-sample Mendelian randomization.

BACKGROUND: Helicobacter pylori (H. pylori), according to a number of recent observational studies, is connected to atherosclerosis (AS). However, the link between H. pylori and AS is debatable. METHODS: In order to calculate the causal relationship between H. pylori and AS, we employed a two-sample Mendelian randomization (MR) analysis. The data for H. pylori were obtained from the IEU GWAS database ( https://gwas.mrcieu.ac.uk/datasets/ ) and the data for AS were obtained from the Finngen GWAS database ( https://r5.finngen.fi/ ). We selected single nucleotide polymorphisms with a threshold of 5 × 10-6 from earlier genome-wide association studies. MR was performed mainly using the inverse variance weighted (IVW) method. To ensure the reliability of the findings, We performed a leave-one-out sensitivity analysis to test for sensitivity. F-value was used to test weak instrument. RESULTS: A positive causal relationship between H. pylori OMP antibody levels and peripheral atherosclerosis was shown by our two-sample MR analysis (odds ratio (OR) = 1.33, 95% confidence interval (CI) = 1.14-1.54, P = 0.26E-03) using IVW. Additionally, there was a causative link between coronary atherosclerosis and H. pylori VacA antibody levels (IVW OR = 1.06, 95% CI = 1.01-1.10, P = 0.016). All the F-values were above 10. CONCLUSIONS: This MR study discovered a causal link between H. pylori and AS. Different antibodies have different effects, so future researches are needed to figure out the exact mechanisms behind this link.

Inhibition of the type IV secretion system from antibiotic-resistant Helicobacter pylori clinical isolates supports the potential of Cagα as an anti-virulence target.

Helicobacter pylori resistance to antibiotics is a growing problem and it increasingly leads to treatment failure. While the bacterium is present worldwide, the severity of clinical outcomes is highly dependent on the geographical origin and genetic characteristics of the strains. One of the major virulence factors identified in H. pylori is the cag pathogenicity island (cagPAI), which encodes a type IV secretion system (T4SS) used to translocate effectors into human cells. Here, we investigated the genetic variability of the cagPAI among 13 antibiotic-resistant H. pylori strains that were isolated from patient biopsies in Québec. Seven of the clinical strains carried the cagPAI, but only four could be readily cultivated under laboratory conditions. We observed variability of the sequences of CagA and CagL proteins that are encoded by the cagPAI. All clinical isolates induce interleukin-8 secretion and morphological changes upon co-incubation with gastric cancer cells and two of them produce extracellular T4SS pili. Finally, we demonstrate that molecule 1G2, a small molecule inhibitor of the Cagα protein from the model strain H. pylori 26695, reduces interleukin-8 secretion in one of the clinical isolates. Co-incubation with 1G2 also inhibits the assembly of T4SS pili, suggesting a mechanism for its action on T4SS function.

Helicobacter pylori cagA/vacAs1-m1 strain is associated with high risk of fibrosis in metabolic-dysfunction-associated steatotic liver disease.

INTRODUCTION AND OBJECTIVES: Recent studies have suggested an association between H. pylori and metabolic dysfunction associated steatotic liver disease (MASLD). We aim to evaluate the association of H. pylori virulence genes with non-invasive markers of liver injury and fibrosis in MASLD subjects. PATIENTS AND METHODS: A total of 362 dyspeptic patients who underwent gastroscopy were selected. Biochemical, clinical parameters, ultrasound, FIB-4 score, liver stiffness measurement (LSM) by vibration-controlled transient elastography (VCTE), gastric biopsies, and H. pylori virulence genes (cagA, vacA) were evaluated. RESULTS: A cohort comprised of 61 % women and 39 % men with a median age of 52 (40-60) years. MASLD was observed in 42 %, and H. pylori-positive in 45 %. No differences were observed regarding H. pylori status at co-morbid metabolic conditions. In MASLD cohort, H. pylori-positive was associated with higher AST, ALT, FIB-4 and LSM. Indeed, carriers of cagA/vacA-s1/m1-positive allelic combination were associated with higher AST, ALT, FIB-4 and LSM but not cagA/vacA-s1/m1-negative. The OR for high-risk of significant/advanced- fibrosis by VCTE (≥8 kPa) with H. pylori-positive was 2.56 (95 % CI, 1.2-5.75) and for cagA/vacA-s1/-m1-positive allelic carriers was 4.01 (95 % CI, 1.38-11.56), but non-significant association in cagA/vacA-s1/-m1-negative. After adjusting for age, gender, diabetes, BMI and hypertension the OR for VCTE ≥8 kPa with H. pylori-positive was 2.43 (95 % CI, 1.88-12.44), and cagA/vacA-s1/m1-positive allelic carriers was 4.06 (95 % CI, 1.22-14.49). CONCLUSIONS: In our cohort of functional dyspepsia (FD) patients with MASLD, H. pylori was associated with non-invasive markers of liver injury and fibrosis. Carriers of cagA/vacA-s1/m1-positive allelic combination showed an independent risk of significant/advanced fibrosis by VCTE.

Optical Biosensor Based on Porous Silicon and Tamm Plasmon Polariton for Detection of CagA Antigen of Helicobacter pylori.

Helicobacter pylori (H. pylori) is a common pathogen with a high prevalence of infection in human populations. The diagnosis of H. pylori infection is critical for its treatment, eradication, and prognosis. Biosensors have been demonstrated to be powerful for the rapid onsite detection of pathogens, particularly for point-of-care test (POCT) scenarios. In this work, we propose a novel optical biosensor, based on nanomaterial porous silicon (PSi) and photonic surface state Tamm Plasmon Polariton (TPP), for the detection of cytotoxin-associated antigen A (CagA) of H. pylori bacterium. We fabricated the PSi TPP biosensor, analyzed its optical characteristics, and demonstrated through experiments, with the sensing of the CagA antigen, that the TPP biosensor has a sensitivity of 100 pm/(ng/mL), a limit of detection of 0.05 ng/mL, and specificity in terms of positive-to-negative ratio that is greater than six. From these performance factors, it can be concluded that the TPP biosensor can serve as an effective tool for the diagnosis of H. pylori infection, either in analytical labs or in POCT applications.

HtrA-Dependent E-Cadherin Shedding Impairs the Epithelial Barrier Function in Primary Gastric Epithelial Cells and Gastric Organoids.

Impaired E-cadherin (Cdh1) functions are closely associated with cellular dedifferentiation, infiltrative tumor growth and metastasis, particularly in gastric cancer. The class-I carcinogen Helicobacter pylori (H. pylori) colonizes gastric epithelial cells and induces Cdh1 shedding, which is primarily mediated by the secreted bacterial protease high temperature requirement A (HtrA). In this study, we used human primary epithelial cell lines derived from gastroids and mucosoids from different healthy donors to investigate HtrA-mediated Cdh1 cleavage and the subsequent impact on bacterial pathogenesis in a non-neoplastic context. We found a severe impairment of Cdh1 functions by HtrA-induced ectodomain cleavage in 2D primary cells and mucosoids. Since mucosoids exhibit an intact apico-basal polarity, we investigated bacterial transmigration across the monolayer, which was partially depolarized by HtrA, as indicated by microscopy, the analyses of the transepithelial electrical resistance (TEER) and colony forming unit (cfu) assays. Finally, we investigated CagA injection and observed efficient CagA translocation and tyrosine phosphorylation in 2D primary cells and, to a lesser extent, similar effects in mucosoids. In summary, HtrA is a crucially important factor promoting the multistep pathogenesis of H. pylori in non-transformed primary gastric epithelial cells and organoid-based epithelial models.

Historical and Molecular Perspectives on the Presence of Helicobacter pylori in Latin America: A Niche to Improve Gastric Cancer Risk Assessment.

Helicobacter pylori (H. pylori) is responsible for causing chronic gastritis, which can cause peptic ulcer and premalignant lesions such as atrophic gastritis, intestinal metaplasia, and dysplasia, with the risk of developing gastric cancer. Recent data describe that H. pylori colonizes the gastric mucosa of more than 50% of the world's population; however, this bacterium has been described as infecting the human population since its prehistory. This review focuses on the populations and subpopulations of H. pylori, differentiated by the polymorphisms present in their constitutive and virulence genes. These genes have spread and associated with different human populations, showing variability depending on their geographical distribution, and have evolved together with the human being. The predominant genotypes worldwide, Latin America and Chile, are described to understand the genetic diversity and pathogenicity of H. pylori in different populations and geographic regions. The high similarity in the sequence of virulence genes between H. pylori strains present in Peruvian and Spanish natives in Latin America suggests a European influence. The presence of cagA-positive strains and vacA s1 m1 allelic variants is observed with greater prevalence in Chilean patients with more severe gastrointestinal diseases and is associated with its geographical distribution. These findings highlight the importance of understanding the genetic diversity of H. pylori in different regions of the world for a more accurate assessment of the risk of associated diseases and their potential impact on health.

Reduction of UreB and CagA expression level by siRNA construct in Helicobacter pylori strain SS1.

BACKGROUND: Two important virulence factors, urease and cagA, play an important role in Helicobacter pylori (H. pylori) gastric cancer. Aim of this study was to investigate the expression level and function of ureB and cagA using small interfering RNAs (siRNA). METHODS: SS1 strain of H. pylori was considered as host for natural transformation. siRNA designed for ureB and cagA genes were inserted in pGPU6/GFP/Neo siRNA plasmid vector to evaluate using phenotypic and genotypic approaches. Then, qPCR was performed for determining inhibition rate of ureB and cagA gene expression. RESULTS: The expression levels of siRNA-ureB and siRNA-cagA in the recombinant strain SS1 were reduced by about 5000 and 1000 fold, respectively, compared to the native H. pylori strain SS1. Also, preliminary evaluation of siRNA-ureB in vitro showed inhibition of urea enzyme activity. These data suggest that siRNA may be a powerful new tool for gene silencing in vitro, and for the development of RNAi-based anti-H. pylori therapies. CONCLUSION: Our results show that targeting ureB and cagA genes with siRNA seems to be a new strategy to inhibit urease enzyme activity, reduce inflammation and colonization rate.

Low-grade intestinal metaplasia in Indonesia: Insights into the expression of proinflammatory cytokines during Helicobacter pylori infection and unique East-Asian CagA characteristics.

Helicobacter pylori infection is a major cause of intestinal metaplasia. In this study, we aimed to understand the reason underlying the low grade and incidence of intestinal metaplasia in Indonesia, based on the expression of genes encoding proinflammatory cytokines in gastric biopsy specimens. The possible reasons for the lesser virulence of the East-Asian-type CagA in Indonesia than that of the Western-type CagA, which is not common in other countries, were also investigated. The mRNA expression of cytokines was evaluated using real-time PCR. CagA characteristics were analyzed using in silico analysis. The expression of cytokines was typically not robust, among H. pylori-infected subjects in Indonesia, despite them predominantly demonstrating the East-Asian-type CagA. This might partially be explained by the characteristics of the East-Asian-type CagA in Indonesia, which showed a higher instability index and required higher energy to interact with proteins related to the cytokine induction pathway compared with the other types (p < 0.001 and p < 0.05, respectively). Taken together, besides the low prevalence of H. pylori, the low inflammatory response of the host and low CagA virulence, even among populations with high infection rates, may play an essential role in the low grade and low incidence of intestinal metaplasia in Indonesia. We believe that these findings would be relevant for better understanding of intestinal metaplasia, which is closely associated with the development of gastric cancer.

Helicobacter pylori virulence genotypes in Bogotá River and wastewater treatment plants in Colombia.

BACKGROUND: Helicobacter pylori is a bacterium that infects 70%-80% of the population in Colombia, causing chronic gastritis in all those infected and gastric cancer in 1%-2% of those infected. In Colombia, some studies have identified the presence of vacA and cagA genes in environmental samples such as treated, surface, and wastewater, but they have not been evaluated in the Bogotá River. For this, the aim of this study was to identify the virulence genotypes of H. pylori present in samples from the Bogotá River and domestic wastewater treatment plants (WWTPs). MATERIALS AND METHODS: A total of 75 water samples (51 from the Bogotá River and 24 from wastewater treatment plants) were collected. The presence of H. pylori DNA and its virulence genotypes was determined by polymerase chain reaction (PCR). RESULTS: The presence of H. pylori DNA was demonstrated in 44% (33/75) of the samples, obtaining 63.6% (21/33) from the Bogotá River and 36.4% (12/33) from the WWTPs. The most prevalent H. pylori genotype was cagA (-) and vacAm1/s1/i1 being the most virulent of the vacA gene. CONCLUSIONS: This is the first study in Colombia that determines the cagA and vacA genotypes in surface water and WWTPs, indicating the circulation of virulent genotypes in the population. The presence of this pathogen in the waters can be represent a risk to the health of the surrounding population since these waters are reused by the communities for different purposes.