Distribution of Helicobacter pylori virulence markers in patients with gastroduodenal diseases in a region at high risk of gastric cancer

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.

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.

Zwitterionic polymer on silicone implants inhibits the bacteria-driven pathogenic mechanism and progress of breast implant-associated anaplastic large cell lymphoma

Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) occurs in the capsule surrounding breast implants. Malignant transformation of T cells by bacteria-driven chronic inflammation may be underlying BIA-ALCL mechanism. Here, we covalently grafted 2-methacryloyloxyethyl phosphorylcholine (MPC)-based polymers on a silicone surface and examined its effects against BIA-ALCL pathogenesis. MPC grafting strongly inhibited the adhesion of bacteria and bacteria-causing inflammation. Additionally, cancer T cell proliferation and capsule-derived fibroblast-cancer cell communication were effectively inhibited by MPC grafting. We further demonstrated the effect of MPC against the immune responses causing BIA-ALCL around human silicone implants in micro-pigs. Finally, we generated a xenograft anaplastic T cell lymphoma mouse model around the silicone implants and demonstrated that MPC grafting could effectively inhibit the lymphoma progression. This study is the first to show that bacteria-driven induction and progression of BIA-ALCL can be effectively inhibited by surface modification of implants. STATEMENT OF SIGNIFICANCE: Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is a major concern in the field of plastic and reconstructive surgery. In this study, we demonstrate strong inhibitory effect of zwitterionic polymer grafting on BIA-ALCL pathogenesis and progression, induced by bacterial infection and inflammation, both in vitro and in vivo. This study provides a molecular basis for the development of novel breast implants that can prevent various potential complications such as excessive capsular contracture, breast implant illness, and BIA-ALCL incidence, as well as for expanding the biomedical applications of zwitterionic polymers.

Advances in surface modifications of the silicone breast implant and impact on its biocompatibility and biointegration

Silicone breast implants are commonly used for cosmetic and oncologic surgical indications owing to their inertness and being nontoxic. However, complications including capsular contracture and anaplastic large cell lymphoma have been associated with certain breast implant surfaces over time. Novel implant surfaces and modifications of existing ones can directly impact cell-surface interactions and enhance biocompatibility and integration. The extent of foreign body response induced by breast implants influence implant success and integration into the body. This review highlights recent advances in breast implant surface technologies including modifications of implant surface topography and chemistry and effects on protein adsorption, and cell adhesion. A comprehensive online literature search was performed for relevant articles using the following keywords silicone breast implants, foreign body response, cell adhesion, protein adsorption, and cell-surface interaction. Properties of silicone breast implants impacting cell-material interactions including surface roughness, wettability, and stiffness, are discussed. Recent studies highlighting both silicone implant surface activation strategies and modifications to enhance biocompatibility in order to prevent capsular contracture formation and development of anaplastic large cell lymphoma are presented. Overall, breast implant surface modifications are being extensively investigated in order to improve implant biocompatibility to cater for increased demand for both cosmetic and oncologic surgeries.

Helicobacter pylori virulence dupA gene: risk factor or protective factor?

Helicobacter pylori is the etiological agent of chronic gastritis, peptic ulcer, and gastric cancer. The duodenal ulcer-promoting gene dupA, which is located in the plasticity region of the H. pylori genome, is homologous to the virB gene which encodes a type IV secretion protein in Agrobacterium tumefaciens. Studies have shown associations between H. pylori dupA-positive strains and gastroduodenal diseases. However, whether dupA acts as a risk factor or protective factor in these diseases remains unclear. Therefore, in this study, we aimed to verify the presence of the dupA gene in infectious H. pylori strains in the Brazilian mid-west and to investigate its association with the clinical outcomes of patients with dyspepsia. Additionally, the phylogenetic origin of the strains was determined. Gastric biopsies from 117 patients with dyspepsia were analyzed using histological and molecular techniques. The hpx gene (16S rRNA) was used to screen for H. pylori infection, and positive samples were then subjected to dupA gene detection and sequencing. The estimated prevalence of H. pylori infection was 64.1%, with the dupA gene being detected in a high proportion of infectious strains (70.7%). Furthermore, a risk analysis revealed that for women, a dupA-positive H. pylori infection increased the chance of developing gastritis by twofold. The partial dupA sequences from isolated infectious strains in this work are similar to those of strains isolated in westerns countries. This study provides useful insights for understanding the role of the H. pylori dupA gene in disease development.

Facing Cell Autophagy in Gastric Cancer - What Do We Know so Far?

Autophagy is a process by which misfolded proteins and damaged organelles in the lysosomes of tumor cells were degraded reusing decomposed substances and avoiding accumulation of large amounts of harmful substances. Here, the role of autophagy in the development of malignant transformation of gastric tumors, and the underlying mechanisms involved in autophagy formation, and the application of targeted autophagy in the treatment of gastric cancer were summarized.

Novel virulence factor dupA of Helicobacter pylori as an important risk determinant for disease manifestation: An overview

Helicobacter pylori (H. pylori) is a microaerophilic, Gram-negative, human gastric pathogen found usually in the mucous lining of stomach. It infects more than 50% of the world’s population and leads to gastroduodenal diseases. The outcome of disease depends on mainly three factors: Host genetics, environment and bacterial factors. Among these, bacterial virulence factors such as cagA, vacA are well known for their role in disease outcomes. However, based on the global epidemiological results, none of the bacterial virulence (gene) factors was found to be associated with particular diseases like duodenal ulcer (DU) in all populations. Hence, substantial importance has been provided for research in strain-specific genes outside the cag pathogenicity island, especially genes located within the plasticity regions. dupA found within the plasticity regions was first demonstrated in 2005 and was proposed for duodenal ulcer development and reduced risk of gastric cancer in certain geographical regions. Due to the discrepancies in report from different parts of the world in DU development related to H. pylori virulence factor, dupA became an interesting area of research in elucidating the role of this gene in the disease progression. In this review, we shed light on the detailed information available on the polymorphisms in dupA and their clinical relevance. We have critically appraised several pertinent studies on dupA and discussed their merits and shortcomings. This review also highlights dupA gene as an important biomarker for DU in certain populations.

The A, B and C's of Silicone Breast Implants: Anaplastic Large Cell Lymphoma, Biofilm and Capsular Contracture

Breast implantation either for cosmetic or reconstructive e purposes is one of the most common procedures performed in plastic surgery. Biofilm infection is hypothesised to be involved in the development of both capsular contracture and anaplastic large cell lymphoma (ALCL). Capsular contracture is one of the principal reasons for breast revision surgery and is characterised by the tightening and hardening of the capsule surrounding the implant, and ALCL is an indolent lymphoma found only in women with textured implants. We describe the types of breast implants available with regard to their surface characteristics of surface area and roughness and how this might contribute to capsular contracture and/or biofilm formation. The pathogenesis of capsular contracture is thought to be due to biofilm formation on the implant, which results in on-going inflammation. We describe the current research into breast implant associated ALCL and how implant properties may affect its pathogenesis, with ALCL only occurring in women with textured implants.

The type IV secretion system in Helicobacter pylori

Helicobacter pylori (H. pylori) has an essential role in the pathogenesis of gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue lymphoma and gastric cancer. The severity of the host inflammatory responses against the bacteria have been straightly associated with a special bacterial virulence factor, the cag pathogenicity island, which is a type IV secretion system (T4SS) to deliver CagA into the host cells. Besides cag-T4SS, the chromosomes of H. pylori can encode another three T4SSs, including comB, tfs3 and tfs4. In this review, we systematically reviewed the four T4SSs of H. pylori and explored their roles in the pathogenesis of gastroduodenal diseases. The information summarized in this review might provide valuable insights into the pathogenic mechanism for H. pylori.

Risk of gastric cancer in association with Helicobacter pylori different virulence factors: A systematic review and meta-analysis

INTRODUCTION

It has been proposed that specific analysis of Helicobacter pylori virulence factors can be suitable for predicting of post H. pylori infection disorders like gastric cancer (GC). The present study was designed to evaluate the association between different virulence factors of H. pylori and GC.

METHODS

Studies investigated the association between virulence factors of H. pylori and GC were collected from the several databases. All analysis was performed by Comprehensive Meta-Analysis V2.2 software (Biostat, Englewood, NJ, USA).

RESULTS

Based on a comprehensive literature search, 25 eligible studies were included for meta-analyses. Infection with cagA- and vacA s1m1-positive H. pylori strains were significantly associated with increased risk of GC (OR of [2.82 (95% CI 1.96-4.06), P < 0.001]) and ([1.75 (95% CI 1.04-2.96), P 0.034)], respectively.

CONCLUSIONS

Infection by H. pylori strains with positive vacA s1m1 and the cagA genes can significantly increase the risk of GC. The association between the vacA s1m1 and the cagA and GC, suggests that screening of these genes may be helpful for identifying populations at higher risk for GC.

Biological characteristics and virulence of Helicobacter pylori

This review summarizes the most recent data on the biological characteristics of Helicobacter pylori (morphological, cultural, biochemical). H. pylori pathogenicity factors promoting colonization, adhesion, biofilm formation, aggression, and cytotoxicity, their contribution to the pathogenesis of diseases as well as the possible relationships with various clinical outcomes are described in detail. The genetic heterogeneity of H. pylori strains which can determine different clinical manifestations and have significance for conducting epidemiological studies is also considered.

Helicobacter pylori genotypes determine risk of non-cardia gastric cancer and intestinal- or diffuse-type GC in Ardabil: A very high-risk area in Northwestern Iran

Frequency of the Helicobacter pylori vacA gene polymorphism and its association with gastric cancer (GC) was assessed in Ardabil, a very high-risk area in Northwestern Iran. We determined the presence of the H. pylori 16S rDNA gene and the vacA s-, m-, i-, and d-region genotypes in DNA from fresh gastric biopsies. Patients with GC were classified based on both the anatomic site and the histopathologic type of tumor Of 135 patients, including 57 with non-atrophic gastritis (NAG) and 78 with GC, 103 were infected by H. pylori. The vacA i1 and d1 genotypes were significantly linked to an increased risk of GC, where both cardia (CGC) and non-cardia GC (NCGC) patients were entered into the analysis. The adjusted OR was 9.59 for i1 and 4.39 for d1. Furthermore, i1 was significantly linked to an increased risk of the intestinal-type adenocarcinoma (OR = 14.04) and d1 to the risk of the diffuse-type adenocarcinoma (OR = 7.71). The presence of the m1-type of vacA in combination with i1 or d1 further increased the risk of GC. When the analysis was restricted to NCGC, the adjusted OR for i1 and d1, was 37.52 and 7.17, respectively. No significant association was found between genotypes and the risk of GC in the cardia site of the stomach. It is proposed that the new types of H. pylori vacA, i1 and d1, might be important determinants of NCGC risk in Ardabil. The m1, not independently, but in combination might further define the risk of GC. i1and d1 might also predict the risk of the intestinal- and diffuse-type adenocarcinomas, respectively.

Helicobacter pylori with East Asian-type cagPAI genes is more virulent than strains with Western-type in some cagPAI genes

The severity of Helicobacter pylori-related disease is correlated with the presence and integrity of a cag pathogenicity island (cagPAI). cagPAI genotype may have a modifying effect on the pathogenic potential of the infecting strain. After analyzing the sequences of cagPAI genes, some strains with the East Asian-type cagPAI genes were selected for further analysis to examine the association between the diversity of the cagPAI genes and the virulence of H. pylori. The results showed that gastric mucosal inflammatory cell infiltration was significantly higher in patients with East Asian-type cagPAI genes H. pylori strain compared with mosaicism cagPAI genes H. pylori strain (p < 0.05). H. pylori strains with the East Asian-type cagPAI genes were closely associated with IL-8 secretion in vitro and in vivo compared with H. pylori strains with the mosaicism cagPAI genes (p < 0.01). H. pylori strains with East Asian-type cagPAI genes are able to strongly translocate CagA to host cells. These results suggest that H. pylori strains with East Asian-type cagPAI genes are more virulent than the strains of cagPAI gene/genes that are Western type.

What exists beyond cagA and vacA? Helicobacter pylori genes in gastric diseases

Helicobacter pylori (H. pylori) infection is present in more than half the world's population and has been associated with several gastric disorders, such as gastritis, peptic ulceration, and gastric adenocarcinoma. The clinical outcome of this infection depends on host and bacterial factors where H. pylori virulence genes seem to play a relevant role. Studies of cagA and vacA genes established that they were determining factors in gastric pathogenesis. However, there are gastric cancer cases that are cagA-negative. Several other virulence genes have been searched for, but these genes remain less well known that cagA and vacA. Thus, this review aimed to establish which genes have been suggested as potentially relevant virulence factors for H. pylori-associated gastrointestinal diseases. We focused on the cag-pathogenicity island, genes with adherence and motility functions, and iceA based on the relevance shown in several studies in the literature.

Helicobacter pylori virulence factors in development of gastric carcinoma

Helicobacter pylori plays a vital role in the pathogenesis of gastric carcinoma. However, only a relatively small proportion of individuals infected with H. pylori develop gastric carcinoma. Differences in the incidence of gastric carcinoma among infected individuals can be explained, at least partly, by the different genotypes of H. pylori virulence factors. Thus far, many virulence factors of H. pylori, such as Cag PAI, VacA, OMPs and DupA, have been reported to be involved in the development of gastric cancer. The risk of developing gastric cancer during H. pylori infection is affected by specific host-microbe interactions that are independent of H. pylori virulence factors. In this review, we discuss virulence factors of H. pylori and their role in the development of gastric carcinoma that will provide further understanding of the biological interactions of H. pylori with the host.

Helicobacter pylori with the Intact dupA Cluster is more Virulent than the Strains with the Incomplete dupA Cluster

The duodenal ulcer promoting gene (dupA), located in the plasticity region of Helicobacter pylori (H. pylori), is predicted to form a type IV secretory system (T4SS) with vir genes around dupA. In the study, we investigated the association between the dupA cluster status and the virulence of H. pylori in a littoral region of Northeast China. Two hundred and sixty-two H. pylori strains isolated from the chronic gastritis were examined to evaluate the dupA cluster status, cag PAI genes and vacA genotype using PCR and Western blot. Histopathologic evaluations of biopsy specimens were performed to analysis the association between the dupA cluster and the inflammatory response. IL-8 productions in gastric mucosa and from GES-1 cells co-cultured with H. pylori were measured, respectively, to analysis the association between the dupA cluster status and IL-8 production. We found that gastric mucosal inflammatory cell infiltration was significantly higher in patients with dupA-positive H. pylori, including H. pylori with complete dupA cluster (2.71 ± 0.79) and incomplete dupA cluster (2.09 ± 0.61) than in patients with dupA-negative strain (1.73 ± 0.60, p < 0.01), whereas no significant difference in the gastric mucosal atrophy was found according to the status of dupA cluster. Gastric mucosal IL-8 levels were higher in the complete dupA cluster group than in other groups (p < 0.01), and IL-8 production from GES-1 cells was also significantly higher in strains with a complete dupA cluster (1527.9 ± 180.0 pg/ml) than in those with an incomplete dupA cluster (1229.4 ± 75.3 pg/ml, p < 0.01) or those with dupA negative (1201.9 ± 92.3 pg/ml, p < 0.01). In conclusion, the complete dupA cluster in H. pylori is associated with inflammatory cell infiltration and IL-8 secretion, and H. pylori strain with a complete dupA cluster seems to be more virulent than other strains with the incomplete dupA cluster or dupA negative.

Intact long-type DupA protein in Helicobacter pylori is an ATPase involved in multifunctional biological activities

The function of intact long-type DupA protein in Helicobacter pylori was analyzed using immunoblotting and molecular biology techniques in the study. After cloning, expression and purification, ATPase activity of DupA protein was detected. Antibody was produced for localization and interaction proteins analysis. The dupA-deleted mutant was generated for adhesion and CagA protein translocation assay, susceptibility to different pH, IL-8 secretion assay, cytotoxicity to MKN-45 cells and proteins-involved apoptosis analysis. DupA protein exhibited an ATPase activity (129.5±17.8 U/mgprot) and located in bacterial membrane, while it did not involve the adhesion and CagA protein delivery of H. pylori. DupA protein involved the urease secretion as the interaction proteins. The wild type strain had a stronger growth in low pH than the dupA-deleted mutant (p < 0.001). IL-8 productions from GES-1 cells infected with the wild type strain were significantly higher than from those with the mutant (p < 0.001). The amounts of vital MKN-45 cells were decreased and the numbers of apoptotic cells were increased with the wild type strain, compared to those with the mutant after 12 h (p < 0.05). The increase of cleaved Caspase-3 and Bax was significantly higher and the decrease of Bcl-2 was more obvious in MKN-45 cells exposed to the wild type strain than that exposed to the mutant after 6 h. We demonstrate that intact long-type DupA protein located in membrane as ATPase is a true virulence factor associated with duodenal ulcer development involving the IL-8 induction and urease secretion, while it inhibits gastric cancer cell growth in vitro by activating the mitochondria-mediated apoptotic pathway.

At the crossroad between obesity and gastric cancer

Obesity has reached epidemic proportions worldwide with disproportionate prevalence in different communities and ethnic groups. Recently, the American Medical Association recognized obesity as a disease, which is a significant milestone that opens the possibilities of treating obesity under standardized health plans. Obesity is an inflammatory disease characterized by elevated levels of biomarkers associated with abnormal lipid profiles, glucose levels, and blood pressure that lead to the onset of metabolic syndrome. Interestingly, inflammatory biomarkers, in particular, have been implicated in the risk of developing several types of cancer. Likewise, obesity has been linked to esophageal, breast, gallbladder, kidney, pancreatic, and colorectal cancers. Thus, there exists a link between obesity status and tumor appearance, which may be associated to the differential levels and the circulating profiles of several inflammatory molecules. For example, mediators of the inflammatory responses in both obesity and gastric cancer risk are the same: pro-inflammatory molecules produced by the activated cells infiltrating the inflamed tissues. These molecules trigger pathways of activation shared by obesity and cancer. Therefore, understanding how these different pathways are modulated would help reduce the impact that both diseases, and their concomitant existence, have on society.

Helicobacter pylori-mediated autophagy and gastric carcinogenesis

Helicobacter pylori (H. pylori) infection is closely related to the development of chronic gastritis, peptic ulcer, gastrointestinal metaplasia, and gastric carcinogenesis. H. pylori infection is multifactorial, including host genetic susceptibility, gene regulation, environmental factors and heterogeneity of H. pylori virulence factors. H. pylori adsorbs on the stomach wall through a variety of adhesion molecules, evades the host immune response through multiple virulence factors and defends against the killing effects of antibiotics killing through the capability of membrane resistance. Currently, the cooperative mechanisms between H. pylori and the human host have not yet been fully elucidated. Recent studies have shown that autophagy is an intracellular degradation process through the formation of double-membrane autophagosomes and plays an important role in H. pylori infection. Understanding of the process and molecular mechanisms of autophagy in host cells caused by H. pylori virulence factors will help better understand gastric carcinogenesis related to H. pylori-induced autophagy.

CagA status & genetic characterization of metronidazole resistant strains of H. pylori from: A region at high risk of gastric cancer

Objective: The aim of study was to determine relationship between cagA and genetic characterization of metronidazole (MTZ) resistant H. pylori strains from a region at high risk of gastric cancer.

Methods: 172 H. pylori strains were isolated from the patients with dyspeptic symptoms, and antimicrobial susceptibility testing for MTZ was assessed by E-test. rdxA and frxA genes were amplified using PCR among the MTZ resistant isolates. The status of the plasmid and classes 1～3 integrons were investigated in all isolates.

Results: MTZ was detected in 88 isolates (51.16%). Variations in the rdxA gene leading to alterations of amino acids in RdxA proteins were identified in all MTZ resistant strains. FrxA contained missense alterations in 55 MTZ resistant isolates, while the premature truncation of FrxA was caused by frameshift mutations in 9 MTZ resistant strains. Plasmid was found in one MTZ sensitive strain (0.58%), and none of Class 1～3 integrases gene was detected in the studied isolates. The conservative cagA fragment was obtained from all clinical isolates of H. pylori. The sequence of cagA 3' variable region in 164 strains were obtained, including East Asian-type (122, 74.39%) and Western-type (42, 25.61%). Prevalence of Western-type cagA 3' variable region was significantly higher in MTZ resistant (33.73%, 28/83) than those of MTZ-sensitive strains (17.28%, 14/81) (p=0.02).

Conclusion: A high prevalence of MTZ resistance was found in the region, and bacterial chromosome mutations in the rdxA and frxA gene still contribute to the high-level MTZ resistance. H. pylori strains characterized with West-type cagA 3’ variable region tend to acquire MTZ resistance in the region.

Associations of a TLR4 single-nucleotide polymorphism with H. pylori associated gastric diseases in Iranian patients

OBJECTIVE

Helicobacter pylori (H. pylori) is associated with gastric ulcer and gastric adenocarcinoma. Polymorphisms in the host genes coding for toll-like receptors (TLRs) may influence the innate and adaptive immune response to the infection, affecting the susceptibility to H. pylori or the disease outcomes. But the details and association to different polymorphisms and different clinical expressions in patients infected with H. pylori (different clinical expression of H. pylori infection) remain unclear.

METHODS

A case-control study consisting of 195 patients with H. pylori infection and 241 H. pylori uninfection was conducted. Genomic DNA was extracted and genotypes of TLR4Asp299Gly polymorphism were assessed through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Presence of cagA was evaluated using PCR.

RESULTS

TLR4 (Asp299Gly) G and DG alleles frequency in H. pylori infected population was significantly higher in the chronic gastritis group than in the chronic active gastritis group (P=0.021; OR, 2.409; 95% CI, 1.124-5.162). Grade mononuclear (MN) infiltration in H. pylori infected patients with DG genotype of TLR-4 Asp299Gly increased significantly. CagA positivity was more frequently associated with chronic active gastritis (P=0.017, OR=2.26, 95% CI=1.144-4.462) and grade polymorphonucler (PMN) infiltration.

CONCLUSION

TLR-4 Asp299Gly G allele substitution may be modified pattern of immune response in the gastric mucosa of H. pylori infected patients and may be H. pylori infected patients with gastritis have increased risk for the development of chronic gastritis. CagA positivity may be a risk factor for development of gastritis.

Virulence Factors of Helicobacter pylori: A Review

Helicobacter pylori is a spiral-shaped Gram-negative bacterium that colonizes the human stomach and can establish a long-term infection of the gastric mucosa, a condition that affects the relative risk of developing various clinical disorders of the upper gastrointestinal tract, such as chronic gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma. H. pylori presents a high-level of genetic diversity, which can be an important factor in its adaptation to the host stomach and also for the clinical outcome of infection. There are important H. pylori virulence factors that, along with host characteristics and the external environment, have been associated with the different occurrences of diseases. This review is aimed to analyzing and summarizing the main of them and possible associations with the clinical outcome.

Virulence factors of Helicobacter pylori vacA increase markedly gastric mucosal TGF-β1 mRNA expression in gastritis patients

OBJECTIVE

Helicobacter pylori (H. pylori) infection is the main cause of gastric inflammation. Regulatory T cells (Treg cells) suppress the activation and proliferation of antigen-specific T cells and mediate immunologic tolerance. TGF-β1 was shown to be secreted in a subset of Treg cells known as 'Th3 cells'. These cells have not been sufficiently studied in context to H. pylori-induced inflammation in human gastric mucosa. In this study we therefore, aimed to investigate the expression of TGF-β1 in the context of H. pylori colonization in chronic gastritis, to examine the relationship between it and histopathologic findings and to compare it with virulence factors.

PATIENTS AND METHODS

Total RNA was extracted from gastric biopsies of 48 H. pylori-infected patients and 38 H. pylori-negative patients with gastritis. Mucosal TGF-β1 mRNA expression in H. pylori-infected and uninfected gastric biopsies was determined by real-time PCR. Presence of vacA, cagA, iceA, babA2 and oipA virulence factors was evaluated using PCR.

RESULTS

TGF-β1 mRNA expression was significantly increased in biopsies of H. pylori-infected patients compared to H. pylori-uninfected patients. There was association between virulence factors and TGF-β1 mRNA expression. TGF-β1 mRNA expression in mucosa was significantly higher in patients with vacA s1 and s1m1.

CONCLUSIONS

TGF-β1 may play an important role in the inflammatory response and promote the chronic and persistent inflammatory changes in the gastric. This may ultimately influence the outcome of H. pylori-associated diseases that arise within the context of gastritis and vacA may suffice to induce expression of TGF-β1 mRNA.

Association among H. pylori virulence markers dupA, cagA and vacA in Brazilian patients

Background

Only a few Helicobacter pylori-infected individuals develop severe gastric diseases and virulence factors of H. pylori appear to be involved in such clinical outcomes. Duodenal ulcer promoting gene A (dupA) is a novel virulence factor of Helicobacter pylori that is associated with duodenal ulcer development and reduced risk for gastric carcinoma in some populations. The aims of the present study were to determine the presence of dupA gene and evaluate the association among dupA and other virulence factors including cagA and vacA in Brazilian patients. Gastric biopsies were obtained from 205 dyspeptic patients (100 children and 105 adults). DNA was extracted and analyzed for the presence of H. pylori and its virulence factors using the polymerase chain reaction method.

Results

Patients with gastritis tested positive for H. pylori more frequently. The dupA gene was detected in 41.5% of them (85/205); cagA gene was found in 98 isolates (47.8%) and vacA genotype s1/m1 in 50.2%, s1/m2 in 8.3%, s2/m2 in 36.6%, s2/m1 in 0.5% and s1/s2/m1/m2 in 4.4%. We also verified a significant association between cagA and dupA genes [p = 0.0003, relative risk (RR) 1.73 and confidence interval [CI] = 1.3–2.3]. The genotypes s1/m1 were also associated with dupA gene (p = 0.0001, RR: 1.72 and CI: 1.3–2.2). The same associations were found when analyzing pediatric and adult groups of patients individually.

Conclusion

Ours results suggest that dupA is highly frequent in Brazilian patients and is associated with cagA gene and vacA s1/m1 genotype, and it may be considered an important virulence factor in the development of gastric diseases in adults or children.