Pathogenesis of Helicobacter pylori infection

Helicobacter pylori: A Contemporary Perspective on Pathogenesis, Diagnosis and Treatment Strategies

Helicobacter pylori (H. pylori) is a Gram-negative bacterium that colonizes the gastric mucosa and is associated with various gastrointestinal disorders. H. pylori is a pervasive pathogen, infecting nearly 50% of the world's population, and presents a substantial concern due to its link with gastric cancer, ranking as the third most common cause of global cancer-related mortality. This review article provides an updated and comprehensive overview of the current understanding of H. pylori infection, focusing on its pathogenesis, diagnosis, and treatment strategies. The intricate mechanisms underlying its pathogenesis, including the virulence factors and host interactions, are discussed in detail. The diagnostic methods, ranging from the traditional techniques to the advanced molecular approaches, are explored, highlighting their strengths and limitations. The evolving landscape of treatment strategies, including antibiotic regimens and emerging therapeutic approaches, is thoroughly examined. Through a critical synthesis of the recent research findings, this article offers valuable insights into the contemporary knowledge of Helicobacter pylori infection, guiding both clinicians and researchers toward effective management and future directions in combating this global health challenge.

Helicobacter pylori and Epstein-Barr Virus Co-Infection in Gastric Disease: What Is the Correlation with p53 Mutation, Genes Methylation and Microsatellite Instability in a Cohort of Sicilian Population?

Genetic predisposition, environmental factors, and infectious agents interact in the development of gastric diseases. Helicobacter pylori (Hp) and Epstein-Barr virus (EBV) infection has recently been shown to be correlated with these diseases. A cross-sectional study was performed on 100 hospitalized Italian patients with and without gastric diseases. The patients were stratified into four groups. Significant methylation status differences among CDH1, DAPK, COX2, hMLH1 and CDKN2A were observed for coinfected (Hp-EBV group) patients; particularly, a significant presence of COX2 (p = 0.0179) was observed. For microsatellite instability, minor stability was described in the Hp-HBV group (69.23%, p = 0.0456). Finally, for p53 mutation in the EBV group, exon 6 was, significantly, most frequent in comparison to others (p = 0.0124), and in the Hp-EBV group exon 8 was, significantly, most frequent in comparison to others (p < 0.0001). A significant positive relationship was found between patients with infection (Hp, EBV or both) and p53 mutation (rho = 0.383, p = 0.0001), methylation status (rho = 0.432, p < 0.0001) and microsatellite instability (rho = 0.285, p = 0.004). Finally, we observed among infection and methylation status, microsatellite instability, and p53 mutation a significant positive relationship only between infection and methylation status (OR = 3.78, p = 0.0075) and infection and p53 mutation (OR = 6.21, p = 0.0082). According to our analysis, gastric disease in the Sicilian population has different pathways depending on the presence of various factors, including infectious agents such as Hp and EBV and genetic factors of the subject.

Influence of Iron on the Gut Microbiota in Colorectal Cancer

Perturbations of the colonic microbiota can contribute to the initiation and progression of colorectal cancer, leading to an increase in pathogenic bacteria at the expense of protective bacteria. This can contribute to disease through increasing carcinogenic metabolite/toxin production, inducing inflammation, and activating oncogenic signaling. To limit disease progression, external factors that may influence the colonic microbiota need to be considered in patients with colorectal cancer. One major factor that can influence the colonic microbiota is iron. Iron is an essential micronutrient that is required by both prokaryotes and eukaryotes for cellular function. Most pathogenic bacteria have heightened iron acquisition mechanisms and therefore tend to outcompete protective bacteria for free iron. Colorectal cancer patients often present with anemia due to iron deficiency, and thus they require iron therapy. Depending upon the route of administration, iron therapy has the potential to contribute to a procarciongenic microbiota. Orally administered iron is the common treatment for anemia in these patients but can lead to an increased gut iron concentration. This suggests the need to reassess the route of iron therapy in these patients. Currently, this has only been assessed in murine studies, with human trials being necessary to unravel the potential microbial outcomes of iron therapy.

Oral medications for central serous chorioretinopathy: a literature review

Central serous chorioretinopathy (CSCR) is characterised by acute or chronic neurosensory detachments of the retina, usually in the posterior pole, with or without associated detachments of retinal pigment epithelium. Although the condition often resolves spontaneously, chronic and recurrent cases can lead to significant visual loss in the working population and it is thus increasingly recognised as an important public health issue. The uncertainty regarding the underlying cause of CSCR has led to a wide range of therapies being tried for this condition including photodynamic therapy, laser photocoagulation, anti-VEGF injections and a multitude of oral agents. This article aims to review the current evidence for oral agents that have been used for treatment of CSCR. A systematic literature search was conducted for articles published between 1980 to July 2018. A total of 73 articles were included. These studied the following oral medications: eplerenone, spironolactone, beta blockers, H. pylori agents, omeprazole, rifampicin, methotrexate, aspirin, acetazolamide, mifepristone, melatonin, finasteride, ketoconazole, antioxidants and curcumin phospholipid. Although none of the studies showed robust evidence of efficacy, the mineralocorticoid receptor antagonists, particularly eplerenone, appear to demonstrate the highest quality evidence for use in this condition. The review aims to give the reader an overview of the current available evidence for oral medications used in the treatment of CSCR in order to provide an evidence-based discussion with the patient and guide through possible options for treatment.

Application of PCR and Microscopy to Detect Helicobacter pylori in Gastric Biopsy Specimen among Acid Peptic Disorders at Tertiary Care Centre in Eastern Nepal

BACKGROUND

Helicobacter pylori infection is most prevalent in developing countries. It is an etiological agent of peptic ulcer, gastric adenocarcinoma, and mucosal-associated lymphoid tissue (MALT) lymphoma. Despite the development of different assays to confirm H. pylori infection, the diagnosis of infection is challenged by precision of the applied assay. Hence, the aim of this study was to understand the diagnostic accuracy of PCR and microscopy to detect the H. pylori in the gastric antrum biopsy specimen from gastric disorder patients.

METHODS

A total of 52 patients with gastric disorders underwent upper gastrointestinal endoscopy with biopsy. The H. pylori infection in gastric biopsies was identified after examination by microscopy and 23S rRNA specific PCR. The agreement between two test results were analysed by McNemar's test and Kappa coefficient.

RESULT

H. pylori infection was confirmed in 9 (17.30%) patients by both assays, 6.25% in antral gastritis, 22.22% in gastric ulcer, 100% in gastric ulcer with duodenitis, 50% in gastric ulcer with duodenal ulcer, and 33.33% in severe erosive duodenitis with antral gastritis. Out of nine H. pylori infection confirmed patients, 3 patients were confirmed by microscopy and 8 patients by PCR. In case of two patients, both microscopy and PCR assay confirmed the H. pylori infection. The agreement between two test results was 86.54% and disagreed by 13.46% (p value > 0.05).

CONCLUSION

We found that PCR assay to detect H. pylori is more sensitive than microscopy. However, we advocate for the combination of both assays to increase the strength of diagnostic accuracy due to the absence of the gold standard assay for H. pylori infection.

The prevalence of Helicobacter pylori infection and other risk factors among Mongolian dyspeptic patients who have a high incidence and mortality rate of gastric cancer

BACKGROUND

Mongolia has not only the second highest incidence rate but also the highest mortality rate for gastric cancer globally. In addition to gastric cancer, ulcerative disease complications are also life threatening; thus, investigating Helicobacter pylori infection and other risk factors is essential.

RESULTS

H.pylori infection was high in tested dyspeptic patients from all parts of Mongolia, with an overall infection rate of 80.0%. Logistic regression analysis showed that H. pylori infection was associated with gastritis (odds ratio; 9.0 ([95% confidence interval 5.0-16.2]); p < 0.0001). H. pylori infection (3.3 [2.0-5.4]; p < 0.0001) and > 40 years old (1.5 [1.0-2.0]; p < 0.02) were both associated with atrophy. However, > 40 years old (3.8 [2.4-6.0]; p < 0.0001) and high salt intakes (1.6 [1.0-2.3]; p < 0.02), but not H. pylori infection, were associated with intestinal metaplasia. Excessive amount of salt usage was dramatically higher in northern and western parts of Mongolia, where precancerous diseases, such as erosive esophagitis (for cardia cancer), severe atrophy, and intestinal metaplasia (for non-cardia cancer), were highly prevalent.

CONCLUSIONS

H. pylori infection was the major gastric health problem among the Mongolian population. In addition, environmental factors such as high salt intake worsened the clinical outcome. Therefore, a nationwide screening and eradication of H. pylori infection as well as salt-reducing measures should be implemented.

Interleukin-32: An endogenous danger signal or master regulator of intracellular pathogen infections-Focus on leishmaniases

Interleukin 32 (IL-32) is an intracellular cytokine produced by immune and non immune cells after different stimuli. It contributes to inflammation and control of intracellular pathogens mainly by inducing proinflammatory cytokines and microbicidal molecules. Evidence is rising showing that IL-32 can be considered an endogenous danger signal after tissue injury, amplifying the inflammatory process and acquired immune responses. It seems to be a master regulator of intracellular infectious diseases. In this review, first the general properties of IL-32 are described followed by its role in the immunopathogenesis of inflammatory and infectious diseases. Roles of IL-32 in the control of infectious diseases caused by intracellular pathogens are reported, and later a focus on IL-32 in leishmaniases, diseases caused by an intracellular protozoan, is presented.

The Middle Fragment of Helicobacter pylori CagA Induces Actin Rearrangement and Triggers Its Own Uptake into Gastric Epithelial Cells

Cytotoxin-associated gene product A (CagA) is a major virulence factor secreted by Helicobacter pylori. CagA activity in the gastric epithelium is associated with higher risk of gastric cancer development. Bacterial type IV secretion system (T4SS)-mediated translocation of CagA into the cytosol of human epithelial cells occurs via a poorly understood mechanism that requires CagA interaction with the host membrane lipid phosphatidylserine (PS) and host cell receptor integrin α₅β₁. Here we have characterized the isolated recombinant middle fragment of CagA (CagA-M) that contains the positively-charged PS-binding region (aa 613–636) and a putative β₁ integrin binding site, but lacks the EPIYA region, secretion signal peptide and the CagA multimerization motif. We show that CagA-M, when immobilized on latex beads, is capable of binding to, and triggering its own uptake into, gastric epithelial cells in the absence of infection with cagA-positive H. pylori. Using site-directed mutagenesis, fluorescent and electron microscopy, and highly-specific inhibitors, we demonstrate that the cell-binding and endocytosis-like internalization of CagA-M are dependent on (1) binding to PS; (2) β₁ integrin activity; and (3) actin dynamics. Interaction of CagA-M with the host cells is accompanied by the development of long filopodia-like protrusions (macrospikes). This novel morphology is different from the hummingbird phenotype induced by the translocation of full-length CagA. The determinants within CagA-M and within the host that are important for endocytosis-like internalization into host cells are very similar to those observed for T4SS-mediated internalization of full-length CagA, suggesting that the latter may involve an endocytic pathway.

Role of caspase-3/E-cadherin in helicobacter pylori-induced apoptosis of gastric epithelial cells

This study was designed to investigate the role of caspase-3/E-cadherin in Helicobacter pylori (H. pylori) -induced gastric epithelial apoptosis in cells, animal models and clinical gastritis patients. In cultured gastric mucosal epithelial cells, gastric glandular epithelial cells and C57BL/6 mice, H. pylori infection significantly induced apoptosis of gastric epithelial cells, down-regulated full-length E-cadherin and Bcl-2 expression, and up-regulated cleaved-caspase-3, E-cadherin/carboxy-terminal fragment 3 and Bax expression. Z-DEVD-FMK, an inhibitor of caspase-3, attenuated the effect of H. pylori. E-cadherin overexpression significantly inhibited the apoptosis of GES-1 and SGC-7901 cells induced by the H. pylori. The results from clinical studies also showed down-regulation of E-cadherin, up-regulation of cleaved-caspase-3 expression and increased apoptosis in gastric tissues from gastritis patients with H. pylori infection. These results suggest that the caspase-3/E-cadherin pathway is involved in the apoptosis of gastric epithelial cells induced by H. pylori.

Prediagnostic Helicobacter pylori Antibodies and Colorectal Cancer Risk in an Elderly, Caucasian Population

BACKGROUND

Study results on overall seroprevalence of Helicobacter pylori and colorectal cancer risk have been inconsistent. However, one study found positive associations with antibodies to specific H. pylori proteins. To follow up on those findings, we assessed associations of 15 H. pylori specific proteins with colorectal cancer incidence in the prospective Cancer Prevention Study-II Nutrition Cohort.

MATERIALS AND METHODS

Participants in this nested case-control study included 392 cases and 774 controls who were predominantly elderly (median age at blood draw: 71 years) and Caucasian (98%). Seroreactivity against 15 H. pylori proteins was assessed by fluorescent bead-based multiplex serology and associations with colorectal cancer were estimated using conditional logistic regression.

RESULTS

Helicobacter pylori serostatus was not associated with colorectal cancer incidence (odds ratio (OR), 1.17, 95% confidence interval (95% CI), 0.91-1.50). Among individual antigens, GroEl serostatus was associated with colorectal cancer risk (OR, 1.32, 95% CI: 1.03-1.70), whereas CagM was associated with colon cancer risk only (OR, 1.35, 95% CI: 1.01-1.80). No dose-response relationships were observed for any of the antigens, including GroEl and CagM.

CONCLUSIONS

The results of our study do not support an association between H. pylori infection and colorectal cancer risk in this elderly, mostly Caucasian population.

Serum IL-10, MMP-7, MMP-9 Levels in Helicobacter pylori Infection and Correlation with Degree of Gastritis

AIM

Helicobacter pylori causes gastric mucosal inflammation and immune reaction. However, the increase of IL-10, MMP-7, and MMP-7 levels in the serum is still controversial. The objective of this study was to investigate the serum levels of IL-10, MMP-7 & MMP-9 in gastritis patients with H. pylori infection.

MATERIALS AND METHODS

A cross-sectional study was done on seventy gastritis patients that consecutive admitted to endoscopy units. The diagnosis of gastritis was made based on histopathology and diagnosis of H. pylori infection was based on rapid urease test. Serum samples were obtained to determine to circulate IL-10, MMP-7, and MMP-9 level. Univariate and bivariate analysis were done by SPSS version 22.

RESULTS

Forthy percentages of the patients were infected with H. pylori. The IL-10 level was significantly higher in H. pylori-infected patients compared to non-infected patients. However, there were no differences between serum levels of MMP-7 and MMP-9 in infected and non-infected H. pylori patients.

CONCLUSIONS

The immune response to H. pylori promotes systemic inflammation, which was reflected by the increased levels of serum IL-10. However, there were no significant differences in MMP-7 and MMP-9 serum levels between positive and negative infected H. pylori patients.

IL-32: A Novel Pluripotent Inflammatory Interleukin, towards Gastric Inflammation, Gastric Cancer, and Chronic Rhino Sinusitis

A vast variety of nonstructural proteins have been studied for their key roles and involvement in a number of biological phenomenona. Interleukin-32 is a novel cytokine whose presence has been confirmed in most of the mammals except rodents. The IL-32 gene was identified on human chromosome 16 p13.3. The gene has eight exons and nine splice variants, namely, IL-32α, IL-32β, IL-32γ, IL-32δ, IL-32ε, IL-32ζ, IL-32η, IL-32θ, and IL-32s. It was found to induce the expression of various inflammatory cytokines including TNF-α, IL-6, and IL-1β as well as macrophage inflammatory protein-2 (MIP-2) and has been reported previously to be involved in the pathogenesis and progression of a number of inflammatory disorders, namely, inflammatory bowel disease (IBD), gastric inflammation and cancer, rheumatoid arthritis, and chronic obstructive pulmonary disease (COPD). In the current review, we have highlighted the involvement of IL-32 in gastric cancer, gastric inflammation, and chronic rhinosinusitis. We have also tried to explore various mechanisms suspected to induce the expression of this extraordinary cytokine as well as various mechanisms of action employed by IL-32 during the mediation and progression of the above said problems.

Challenges to the Treatment and New Perspectives for the Eradication of Helicobacter pylori

Helicobacter pylori (H. pylori) is one of the leading causes of gastric diseases such as chronic gastritis, peptic ulcer, and gastric adenocarcinoma. The current treatment of H. pylori infection with antibiotics and proton pump inhibitors has several limitations, including poor adherence and intrinsic patient-related factors, drug resistance, and the absence of adequate treatments. This review summarizes the current therapeutic approaches to eradicating H. pylori, the difficulties associated with its treatment, and several new perspectives aimed at improving existing treatment strategies.

Higher glucose level can enhance the H. pylori adhesion and virulence related with type IV secretion system in AGS cells

BACKGROUND

Hyperglycemia increases the risk of gastric cancer in H. pylori-infected patients. High glucose could increase endothelial permeability and cancer-associated signaling. These suggest high glucose may affect H. pylori or its infected status.We used two strains to investigate whether H. pylori growth, viability, adhesion and CagA-phosphorylation level in the infected-AGS cells were influenced by glucose concentration (100, 150, and 200 mg/dL).

RESULTS

The growth curves of both strains in 200 mg/dL of glucose were maintained at the highest optimal density after 48 h and the best viability of both strains were retained in the same glucose condition at 72 h. Furthermore, adhesion enhancement of H. pylori was significantly higher in 200 mg/dL of glucose as compared to that in 100 and 150 mg/dL (p < 0.05). CagA protein also increased in higher glucose condition. The cell-associated CagA and phosphorylated-CagA was significantly increased in 150 and 200 mg/dL of glucose concentrations as compared to that of 100 mg/dL (p < 0.05), which were found to be dose-dependent.

CONCLUSION

Higher glucose could maintain H. pylori growth and viability after 48 h. H. pylori adhesion and CagA increased to further facilitate the enhancement of cell-associated CagA and phosphorylated CagA in higher glucose conditions.

Helicobacter pylori infection activates Src homology-2 domain-containing phosphatase 2 to suppress IFN-γ signaling

Helicobacter pylori infection not only induces gastric inflammation but also increases the risk of gastric tumorigenesis. IFN-γ has antimicrobial effects; however, H. pylori infection elevates IFN-γ-mediated gastric inflammation and may suppress IFN-γ signaling as a strategy to avoid immune destruction through an as-yet-unknown mechanism. This study was aimed at investigating the mechanism of H. pylori-induced IFN-γ resistance. Postinfection of viable H. pylori decreased IFN-γ-activated signal transducers and activators of transcription 1 and IFN regulatory factor 1 not only in human gastric epithelial MKN45 and AZ-521 but also in human monocytic U937 cells. H. pylori caused an increase in the C-terminal tyrosine phosphorylation of Src homology-2 domain-containing phosphatase (SHP) 2. Pharmacologically and genetically inhibiting SHP2 reversed H. pylori-induced IFN-γ resistance. In contrast to a clinically isolated H. pylori strain HP238, the cytotoxin-associated gene A (CagA) isogenic mutant strain HP238(CagAm) failed to induce IFN-γ resistance, indicating that CagA regulates this effect. Notably, HP238 and HP238(CagAm) differently caused SHP2 phosphorylation; however, imaging and biochemical analyses demonstrated CagA-mediated membrane-associated binding with phosphorylated SHP2. CagA-independent generation of reactive oxygen species (ROS) contributed to H. pylori-induced SHP2 phosphorylation; however, ROS/SHP2 mediated IFN-γ resistance in a CagA-regulated manner. This finding not only provides an alternative mechanism for how CagA and ROS coregulate SHP2 activation but may also explain their roles in H. pylori-induced IFN-γ resistance.

Association of Helicobacter pylori babA2 with peptic ulcer disease and gastric cancer

AIM: To investigate the association between babA2 gene and peptic ulcer disease (PUD) and gastric cancer (GC) in Helicobacter pylori-infected populations.

METHODS: We evaluated the relationship between babA2 and clinical outcomes (PUD and GC) using a meta-analysis. A literature search was performed using the PubMed and Web of Science databases for relevant case-control studies that met the defined inclusion criteria. The ORs and 95%CIs were calculated to estimate the association between babA2 genotype and clinical outcomes. A fixed-effect or random-effect model was performed depending on the absence or presence of significant heterogeneity.

RESULTS: A total of 25 articles with 38 studies met the inclusion criteria and were finally included in this meta-analysis. The results showed that the babA2 genotype was significantly associated with an increased risk of PUD (OR = 2.069, 95%CI: 1.530-2.794, P < 0.001) and especially in the subgroup of duodenal ulcer (OR = 1.588, 95%CI: 1.141-2.209, P = 0.006). Moreover, a significant association between babA2 gene and PUD and duodenal ulcer (OR = 2.739, 95%CI: 1.860-4.032, P < 0.001; OR = 2.239, 95%CI: 1.468-3.415, P < 0.001, respectively) was observed in western countries but not in Asian countries.

CONCLUSION: We demonstrated that the presence of babA2 may be associated with increased risks for PUD, especially duodenal ulcer, in western countries.

Comparative genomic study of gastric epithelial cells co-cultured with Helicobacter pylori

AIM: To identify genes potentially involved in Helicobacter pylori (H. pylori)-induced gastric carcinogenesis.

METHODS: GES-1 cells were co-cultured with H. pylori strains isolated from patients with gastric carcinoma (GC, n = 10) or chronic gastritis (CG, n = 10) for in vitro proliferation and apoptosis assays to identify the most and least virulent strains. These two strains were cagA-genotyped and used for further in vivo carcinogenic virulence assays by infecting Mongolian gerbils for 52 wk, respectively; a broth free of H. pylori was lavaged as control. Genomic profiles of GES-1 cells co-cultured with the most and least virulent strains were determined by microarray analysis. The most differentially expressed genes were further verified using quantitative real-time polymerase chain reaction in GES-1 cells infected with the most and least virulent strains, and by immunohistochemistry in H. pylori positive CG, precancerous diseases, and GC biopsy specimens in an independent experiment.

RESULTS: GC-derived H. pylori strains induced a potent proliferative effect in GES-1 cells in co-culture, whereas CG-derived strains did not. The most (from a GC patient) and least (from a CG patient) virulent strains were cagA-positive and negative, respectively. At week 52, CG, atrophy, metaplasia, dysplasia, and GC were observed in 90.0%, 80.0%, 80.0%, 90%, and 60.0%, respectively, of the animals lavaged with the most virulent strain. However, only mild CG was observed in 90% of the animals lavaged with the least virulent strain. On microarray analysis, 800 differentially expressed genes (49 up- and 751 down-regulated), involving those associated with cell cycle regulation, cell apoptosis, cytoskeleton, immune response, and substance and energy metabolisms, were identified in cells co-cultured with the most virulent strain as compared with those co-cultured with the least virulent strain. The six most differentially expressed genes (with a betweenness centrality of 0.1-0.2) were identified among the significant differential gene profile network, including JUN, KRAS, BRCA1, SMAD2, TRAF1, and HDAC6. Quantitative real-time polymerase chain reaction analyses verified that HDAC6 and TRFA1 mRNA expressions were significantly more up-regulated in GES-1 cells co-cultured with the most virulent strain than in those co-cultured with the least virulent strain. Immunohistochemistry of gastric mucosal specimens from H. pylori-positive patients with CG, intestinal metaplasia (IM), dysplasia, and GC showed that moderately positive and strongly positive HDAC6 expression was detected in 21.7% of CG patients, 30.0% of IM patients, 54.5% of dysplasia patients, and 77.8% of GC patients (P < 0.001). The up-regulation of TRAF1 expressions was detected in 34.8%, 53.3%, 72.7%, and 88.9% specimens of CG, IM, dysplasia, and GC, respectively (P < 0.001).

CONCLUSION: The overexpression of HDAC6 and TRAF1 in GES-1 cells co-cultured with the GC-derived strain and in H. pylori-positive dysplasia and GC suggests that HDAC6 and TRAF1 may be involved in H. pylori-induced gastric carcinogenesis.

Helicobacter pylori as a potential target for the treatment of central serous chorioretinopathy

OBJECTIVES

The objective of this study was to evaluate the relationship between the treatment of Helicobacter pylori gastric infection and changes in best-corrected visual acuity and macular detachment in patients with chronic central serous chorioretinopathy.

METHODS

Seventeen patients diagnosed with central serous chorioretinopathy were examined for gastric infection with Helicobacter pylori using the urease test and gastric biopsy. Helicobacter pylory-positive patients were treated with the appropriate medication. The response to therapy was monitored by evaluating the best-corrected visual acuity and optical coherence tomography. The data were analyzed using Student's t-test before and after treatment.

RESULTS

Fourteen patients (15 eyes) aged 30-56 years (mean 43.4 ± 8.3 years) were positive for Helicobacter pylori. Most of the positive patients had gastric symptoms (78.5%); one had bilateral central serous chorioretinopathy. The mean baseline best-corrected visual acuity was 20/98 (logMAR = 0.53 ± 0.28). Three months after starting treatment with antibiotics, the serous detachment had resolved in 14 of 15 eyes, but two cases required laser treatment. The follow-up period ranged from 6 to 27 months. The mean final best-corrected visual acuity differed significantly from baseline.

CONCLUSION

Our findings suggest that Helicobacter pylori infection may be present in many chronic central serous chorioretinopathy patients and that treatment for the infection may have a favorable effect on the outcome of chronic central serous chorioretinopathy. Due to the possibility of the spontaneous regression of chronic central serous chorioretinopathy and the high prevalence of the infection in the general population, prospective and masked clinical trials are necessary to confirm that treatment for Helicobacter pylori infection may benefit patients with chronic central serous chorioretinopathy.

Helicobacter pylori promotes apoptosis, activates cyclooxygenase (COX)-2 and inhibits heat shock protein HSP70 in gastric cancer epithelial cells

OBJECTIVE

Apoptosis plays an important role in the regulation of gastric epithelial cell number and gastrointestinal disorders induced by Helicobacter pylori (Hp). Heat shock proteins (HSPs) are involved in cell integrity, cell growth and in gastric mucosa colonized by Hp. COX-2 was implicated in Hp-induced carcinogenesis but the effects of this germ and CagA cytotoxin on HSP70, COX-2, Bax and Bcl-2 in gastric cancer epithelial cells have been little studied.

MATERIAL AND METHODS

We determined the expression for HSP70, Bax and Bcl-2 in human gastric epithelial MKN7 cells incubated with live strain Hp (cagA + vacA+) with or without co-incubation with exogenous CagA and NS-398, the selective COX-2 inhibitor. After 3-48 h of incubation, the expression of HSP70, COX-2, Bax and Bcl-2 mRNA and proteins were determined by RT-PCR and immunoprecipitation.

RESULTS

Hp inhibited expression for HSP70 and this was significantly potentiated by exogenous CagA. Co-incubation of epithelial cells with Hp, without or with CagA increased Bax expression and simultaneously decreased expression for Bcl-2. The increase in COX-2 mRNA and Bax expression were significantly inhibited by NS-398. We conclude that Hp promotes apoptosis in adenocarcinoma gastric epithelial cells in vitro and this is associated with activation of COX-2 and inhibition of HSP70.

Role of interleukin-32 in Helicobacter pylori-induced gastric inflammation

Helicobacter pylori infection is associated with gastritis and gastric cancer. An H. pylori virulence factor, the cag pathogenicity island (PAI), is related to host cell cytokine induction and gastric inflammation. Since elucidation of the mechanisms of inflammation is important for therapy, the associations between cytokines and inflammatory diseases have been investigated vigorously. Levels of interleukin-32 (IL-32), a recently described inflammatory cytokine, are increased in various inflammatory diseases, such as rheumatoid arthritis and Crohn's disease, and in malignancies, including gastric cancer. In this report, we examined IL-32 expression in human gastric disease. We also investigated the function of IL-32 in activation of the inflammatory cytokines in gastritis. IL-32 expression paralleled human gastric tissue pathology, with low IL-32 expression in H. pylori-uninfected gastric mucosa and higher expression levels in gastritis and gastric cancer tissues. H. pylori infection increased IL-32 expression in human gastric epithelial cell lines. H. pylori-induced IL-32 expression was dependent on the bacterial cagPAI genes and on activation of nuclear factor κB (NF-κB). IL-32 expression induced by H. pylori was not detected in the supernatant of AGS cells but was found in the cytosol. Expression of the H. pylori-induced cytokines CXCL1, CXCL2, and IL-8 was decreased in IL-32-knockdown AGS cell lines compared to a control AGS cell line. We also found that NF-κB activation was decreased in H. pylori-infected IL-32-knockdown cells. These results suggest that IL-32 has important functions in the regulation of cytokine expression in H. pylori-infected gastric mucosa.

H. pylori clinical isolates have diverse babAB genotype distributions over different topographic sites of stomach with correlation to clinical disease outcomes

Background

Intragenomic recombination between babA and babB mediates antigenic variations and may help H. pylori colonization. This study determined whether variable genotypes of babA and babB correlate to different clinical disease outcomes, and can distribute over the different gastric niches.

Results

This study enrolled 92 clinical strains (45 from peptic ulcer, 27 from gastritis, and 20 from gastric cancer) to detect whether the babA and babB are at locus A or B by PCR reactions using the primers designed from the upstream and variable region of the babA and babB genes. Four genotypes of babA and babB (A B, AB B, A AB, AB AB) were found. The distribution of the 4 genotypes in 92 clinical strains was significantly different among patients with different gastric diseases (p < 0.05). The isolates from gastric cancer patients had a higher rate of AB AB genotype than those from non-cancer patients (40.0% vs. 9.7%, p < 0.05). The AB AB genotype was associated with a higher intensity of intestinal metaplasia (p < 0.05), but did not correlate with a higher inflammation and colonization density in gastric histology (p > 0.05). Besides, the study enrolled 19 patients to verify whether variable genotypes of babAB existed in the different gastric niches. Among the patients infected with more than one babAB genotypes over antrum and corpus, there were higher rate of genotypes as A B or AB AB in isolates from antrum than in those from corpus (75.0 % vs. 16.7%, p < 0.05).

Conclusions

The H. pylori isolate with the AB AB genotype correlates with an increased gastric cancer risk, and colonize in an antrum predominant manner.

Helicobacter pylori infection and systemic sclerosis-is there a link?

Over the last 20 years, increasing evidence has accumulated to implicate infectious agents in the etiology of systemic sclerosis (SSc) and Raynaud's phenomenon. Infection rates in patients with SSc compared with those in control populations do not provide clear support for any specific pathogen. However, increased antibody titers, a preponderance of specific strains in patients with SSc, and evidence of molecular mimicry inducing autoimmune responses suggest mechanisms by which infectious agents may contribute to the development and progression of SSc. Helicobacter pylori (H. pylori) has been associated with diseases such as autoimmune gastritis, Sjögren's syndrome, atherosclerosis, immune thrombocytopenia purpura, inflammatory bowel diseases and autoimmune pancreatitis, in each of which it seems to play a pathogenetic, but it has also been suggested that it may help to protect against the development of autoimmune gastritis, multiple sclerosis, systemic lupus erythemathosus and inflammatory bowel diseases. A systematic literature search was carried out in MEDLINE, EMBASE, Cochrane Library and ACR/EULAR meeting abstracts. We hypotheses that H. pylori infection might play a critical role in the pathogenesis of SSc. Here we review studies examining the potential involvement of H. pylori infection in SSc.

Infectious causes of colorectal cancer

Colorectal cancer is a major cause of cancer-related morbidity and mortality in the United States and many other regions of the world. Our understanding of the pathogenesis of colorectal cancer, from the precursor adenomatous polyp to adenocarcinoma, has evolved rapidly. Colorectal carcinogenesis is a sequential process characterized by the accumulation of multiple genetic and molecular alterations in colonic epithelial cells. However, the development of colorectal cancer involves more then just a genetic predisposition. External or environmental factors presumably play a significant role, and inflammatory bowel diseases, obesity, alcohol consumption, and a diet high in fat and low in fiber have all been implicated as risk factors for the development of either colonic adenomas or carcinomas. We are becoming increasingly aware of microbes as causes of malignancies. This article reviews the various microbes that have been associated with the development of colorectal carcinomas.

Effector prediction in host-pathogen interaction based on a Markov model of a ubiquitous EPIYA motif

Background

Effector secretion is a common strategy of pathogen in mediating host-pathogen interaction. Eight EPIYA-motif containing effectors have recently been discovered in six pathogens. Once these effectors enter host cells through type III/IV secretion systems (T3SS/T4SS), tyrosine in the EPIYA motif is phosphorylated, which triggers effectors binding other proteins to manipulate host-cell functions. The objectives of this study are to evaluate the distribution pattern of EPIYA motif in broad biological species, to predict potential effectors with EPIYA motif, and to suggest roles and biological functions of potential effectors in host-pathogen interactions.

Results

A hidden Markov model (HMM) of five amino acids was built for the EPIYA-motif based on the eight known effectors. Using this HMM to search the non-redundant protein database containing 9,216,047 sequences, we obtained 107,231 sequences with at least one EPIYA motif occurrence and 3115 sequences with multiple repeats of the EPIYA motif. Although the EPIYA motif exists among broad species, it is significantly over-represented in some particular groups of species. For those proteins containing at least four copies of EPIYA motif, most of them are from intracellular bacteria, extracellular bacteria with T3SS or T4SS or intracellular protozoan parasites. By combining the EPIYA motif and the adjacent SH2 binding motifs (KK, R4, Tarp and Tir), we built HMMs of nine amino acids and predicted many potential effectors in bacteria and protista by the HMMs. Some potential effectors for pathogens (such as Lawsonia intracellularis, Plasmodium falciparum and Leishmania major) are suggested.

Conclusions

Our study indicates that the EPIYA motif may be a ubiquitous functional site for effectors that play an important pathogenicity role in mediating host-pathogen interactions. We suggest that some intracellular protozoan parasites could secrete EPIYA-motif containing effectors through secretion systems similar to the T3SS/T4SS in bacteria. Our predicted effectors provide useful hypotheses for further studies.

Matrix metalloproteinase-3 promoter polymorphisms but not dupA-H. pylori correlate to duodenal ulcers in H. pylori-infected females

Background

This study investigated if the H. pylori dupA genotype and certain host single nucleotide polymorphisms (SNPs) of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs), including MMP-3, MMP-7, MMP-9, TIMP-1 and TIMP-2, might correlate with ulcer risk of H. pylori-infected Taiwanese patients.

Results

Of the 549 H. pylori-infected patients enrolled, 470 patients (265 with gastritis, 118 with duodenal ulcer, and 87 with gastric ulcer) received SNPs analysis of MMP-3_{-1612 6A > 5A}, MMP-7_{-181 A > G}, MMP-9_{exon 6 A > G}, TIMP-1_{372 T > C} and TIMP-2_{-418 G > C} by PCR-RFLP. The 181 collected H. pylori isolates were detected for the dupA genotype by PCR. The rates of dupA-positive H. pylori infection were similar among patients with duodenal ulcer (22.8%), gastric ulcer (20.0%), and gastritis (25.5%) (p > 0.05). Males had higher rates of duodenal ulcer and gastric ulcer than females (p < 0.01). Of H. pylori-infected patients, the MMP-3 6A6A genotype were more common in patients with duodenal ulcers than in those with gastritis (87.7% vs. 74.9%, p < 0.05) in females. This genotype had a 2.4-fold (95% CI: 1.02-5.66) increased risk of duodenal ulcer, compared to those with the 5A carrier. Combining the MMP-3/TIMP-1 genotype as 6A6A/CC, the risk of duodenal ulcer increased up to 3.6 fold (p < 0.05) in H. pylori-infected females.

Conclusions

The MMP-3 promoter polymorphism, but not the dupA-status, may correlate with susceptibility to duodenal ulcer after H. pylori infection in Taiwanese females.

Both the p33 and p55 subunits of the Helicobacter pylori VacA toxin are targeted to mammalian mitochondria

Helicobacter pylori infection causes peptic ulcers and gastric cancer. A major toxin secreted by H. pylori is the bipartite vacuolating cytotoxin A, VacA. The toxin is believed to enter host cells as two subunits: the p55 subunit (55 kDa) and the p33 subunit (33 kDa). At the biochemical level, it has been shown that VacA forms through the assembly of large multimeric pores composed of both the p33 subunit and the p55 subunit in biological membranes. One of the major target organelles of VacA is the mitochondria. Since only the p33 subunit has been reported to be translocated into mitochondria and the p55 subunit is not imported, it has been contentious as to whether VacA assembles into pores in a mitochondrial membrane. Here we show the p55 protein is imported into the mitochondria along with the p33 protein subunit. The p33 subunit integrally associates with the mitochondrial inner membrane, and both the p33 subunit and the p55 subunit are exposed to the mitochondrial intermembrane space. Their colocalization suggests that they could reassemble and form a pore in the inner mitochondrial membrane.

Activation of the abundant nuclear factor poly(ADP-ribose) polymerase-1 by Helicobacter pylori

Modification of eukaryotic proteins is a powerful strategy used by pathogenic bacteria to modulate host cells during infection. Previously, we demonstrated that Helicobacter pylori modify an unidentified protein within mammalian cell lysates in a manner consistent with the action of a bacterial ADP-ribosylating toxin. Here, we identified the modified eukaryotic factor as the abundant nuclear factor poly(ADP-ribose) polymerase-1 (PARP-1), which is important in the pathologies of several disease states typically associated with chronic H. pylori infection. However, rather than being ADP-ribosylated by an H. pylori toxin, the intrinsic poly(ADP-ribosyl) polymerase activity of PARP-1 is activated by a heat- and protease-sensitive H. pylori factor, resulting in automodification of PARP-1 with polymers of poly(ADP-ribose) (PAR). Moreover, during infection of gastric epithelial cells, H. pylori induce intracellular PAR-production by a PARP-1-dependent mechanism. Activation of PARP-1 by a pathogenic bacterium represents a previously unrecognized strategy for modulating host cell signaling during infection.

Helicobacter pylori infection in developing countries: the burden for how long?

Approximately 50% (over 3 billion) of the world populations are known to be infected with Helicobacter pylori , mainly in the developing countries . Among those, hundreds of millions of people develop peptic ulceration during their lifetime and still tens of millions might progress to gastric cancer. Possible modes of H. pylori transmission generally described are through direct contact between family members and also through contaminated water and food. Because the high prevalence of infection occurs mainly in developing countries and because the test-and-treat strategy puts a huge economic burden on many of these countries, it is time to take an immediate action toward this bacterial infection and adopt a strategy to prevent it. To address this issue, an updated prevalence of infection, modes of transmission, economics of infection and preventative measures to block the infection process have been discussed.

Comparative proteomic analysis of Helicobacter pylori animal model adapted SS1 and its original strain

AIM: To analyze the protein profiles of mouse-adapted H pylori SS1 and its initial strain 10700 and to find out the proteins associated with enhanced adhesive ability of SS1.

METHODS: Three sets of cellular proteins of SS1 and 10 700 were prepared independently. The samples were separated by two-dimensional gel electrophoresis (2DE) technique, and the gels were scanned and recorded as digitalized images with high-resolution scanner. The images were analyzed by Image Master 2D software. Spots on gels were paired between 10 700 and SS1. Differently expressed proteins in all three sets were cut for in-gel digestion and identified by MALDI-TOF-TOF/MS. Peptide mass fingerprints were searched in the NCBI and Swiss-Prot database.

RESULTS: Eleven down-regulated spots presented with ten proteins. Four were related to anti-oxidation, namely, catalase, thioredoxin reductase, superoxide dismutase and thioredoxin. Five were enzymes associated with metabolism, including proline peptidase, fructose-bisphosphate aldolase, inorganic pyrophosphatase, 3-oxoacid CoA-transferase subunit B and Elongation factor P. Another one was a putative protein HPAG0942.

CONCLUSION: In the course of mouse-adapted, H pylori strain SS1 may increase its adhesive ability by decreasing metabolism and anti-oxidative level measurably.

Infectious agents and colorectal cancer: a review of Helicobacter pylori, Streptococcus bovis, JC virus, and human papillomavirus

Based on the high volume of bacteria and viruses that the intestine is exposed to and the importance of infectious agents in some gastrointestinal and anogenital cancers, it is not surprising the many studies have evaluated the association between colorectal cancer and infectious agents. This review highlights investigations of four agents in relation to colorectal cancer. Helicobacter pylori, Streptococcus bovis, JC virus, and human papillomavirus have all been evaluated as possible etiologic agents for colorectal cancer. For each of these agents, a review of possible mechanisms for carcinogenesis and epidemiologic evidence is discussed, and future directions for research are proposed.

Intestinal metaplasia: a premalignant lesion involved in gastric carcinogenesis

Despite a plateau in incidence, gastric cancer remains a significant problem globally. The majority of gastric cancer is associated with histologically recognizable premalignant stages as first described by Pelayo Correa in the mid-1970s. The mortality from gastric cancer remains high especially in Western countries where, arguably, the index of suspicion of gastric cancer in patients presenting with upper abdominal symptoms is lower than in high prevalence countries. What is the evidence that intestinal metaplasia (IM) is a premalignant condition? What should the clinician know about IM and the relative risks of progression to gastric cancer? Finally, what are the current and future strategies that may help stratify patients into high risk and low risk for the development of gastric cancer? This review focuses on gastric IM and outlines some of the literature that discusses it as a premalignant condition. It also reviews the issue of surveillance of patients with IM in order to attempt to reduce the significant mortality of gastric cancer by detection of earlier stages of disease which are eminently treatable.

Monochloramine impairs caspase-3 through thiol oxidation and Zn2+ release

BACKGROUND

Caspase-3, a pro-apoptotic enzyme, represents a class of proteins in which the active site contains reduced thiol (S-H) groups and is modulated by heavy metal cations, such as Zn(2+). We explored the effects of the thiol oxidant monochloramine (NH(2)Cl) on caspase-3 activity within cells of isolated rabbit gastric glands. In addition, we tested the hypothesis that NH(2)Cl-induced alterations of caspase-3 activity are modulated by oxidant-induced accumulation of Zn(2+) within the cytoplasm.

MATERIALS AND METHODS

Isolated gastric glands were prepared from rabbit mucosa by collagenase digestion. Caspase-3 activity was measured colorimetrically in suspensions of healthy rabbit gastric glands, following exposure to various concentrations of NH(2)Cl with or without the zinc chelator TPEN [tetrakis-(2-pyridylmethyl)ethylene diamine] for 1 h, and re-equilibration in Ringer's solution for 5 h. Conversion of procaspase-3 to active caspase-3 was monitored by Western blot.

RESULTS

Monochloramine inhibited caspase-3 activity in a dose-dependent fashion. At concentrations of NH(2)Cl up to 100 microM, these effects were prevented if TPEN was given concurrently and were partly reversed if TPEN was given 1 h later. Caspase-3 activity was preserved by concurrent treatment with a thiol-reducing agent, dithiothreitol.

CONCLUSIONS

At pathologically relevant concentrations, NH(2)Cl impairs caspase-3 activity through oxidation of its thiol groups. Independently from its thiol oxidant effects on the enzyme, NH(2)Cl-induced accumulation of Zn(2+) in the cytoplasm is sufficient to restrain endogenous caspase-3 activity. Our studies suggest that some bacterially generated oxidants, such as NH(2)Cl, impair host pathways of apoptosis through release of Zn(2+) from endogenous pools.