Helicobacter pylori infection has been proposed to be associated with various diseases of the hepatobiliary tract, including cancer of the bile duct epithelial cells (cholangiocarcinoma, CCA). The ability of H. pylori bacteria to cause pathogenic effects in these cells has, however, yet to be investigated. Given that the cag pathogenicity island (cagPAI) is required for H. pylori pathogenesis in gastric epithelial cells, we investigated wild-type and cag mutant strains for their ability to adhere, be internalized and induce pro-inflammatory responses in two bile duct epithelial cell lines derived from cases of CCA. The findings from these experiments were compared to results obtained with the well-characterized AGS gastric cancer cell line. We showed that the cagPAI encodes factors involved in H. pylori internalization in CCA cells, but not for adhesion to these cells. Consistent with previous studies in hepatocytes, actin polymerization and α5β1 integrin may be involved in H. pylori internalization in CCA cells. As for AGS cells, we observed significantly reduced levels of NF-κB activation and IL-8 production in CCA cells stimulated with either cagA, cagL or cagPAI bacteria, when compared with wild-type bacteria. Importantly, these IL-8 responses could be inhibited via either pre-treatment of cells with antibodies to α5β1 integrins, or via siRNA-mediated knockdown of the innate immune signaling molecules, nucleotide oligomerization domain 1 (NOD1) and myeloid differentiation response gene 88 (MyD88). Taken together, the data demonstrate that the cagPAI is critical for H. pylori pathogenesis in bile duct cells, thus providing a potential causal link for H. pylori in biliary tract disease.
AIM: To investigate the diversity of Helicobacter pylori (H. pylori) genotypes and correlations with disease outcomes in an Iranian population with different gastroduodenal disorders.
METHODS: Isolates of H. pylori from patients with different gastroduodenal disorders were analyzed after culture and identification by phenotypic and genotypic methods. Genomic DNA was extracted with the QIAamp DNA mini kit (Qiagen, Germany). After DNA extraction, genotyping was done for cagA, vacA (s and m regions), iceA (iceA1, iceA2) and babA with specific primers for each allele using polymerase chain reaction (PCR). All patients’ pathologic and clinical data and their relation with known genotypes were analyzed by using SPSS version 19.0 software. χ2 test and Fisher’s exact test were used to assess relationships between categorical variables. The level of statistical significance was set at P < 0.05.
RESULTS: A total of 71 isolates from 177 patients with different gastroduodenal disorders were obtained. Based on analysis of the cagA gene (positive or negative), vacA s-region (s1 or s2), vacA m-region (m1 or m2), iceA allelic type (iceA1 and iceA2) and babA gene (positive or negative), twenty different genotypic combinations were recognized. The prevalence of cagA, vacA s1, vacA s2, vacA m1, vacA m2, iceA1, iceA2, iceA1+iceA2 and babA were 62%, 78.9%, 19.7%, 21.1%, 78.9%, 15.5%, 22.5%, 40.8% and 95.8%, respectively. Interestingly, evaluation of PCR results for cagA in 6 patients showed simultaneous existence of cagA variants according to their size diversities that proposed mixed infection in these patients. The most prevalent genotype in cagA-positive isolates was cagA+/vacAs1m2/iceA1+A2/babA+ and in cagA-negative isolates was cagA-/vacAs1m2/iceA-/babA+. There were no relationships between the studied genes and histopathological findings (H. pylori density, neutrophil activity, lymphoid aggregation in lamina propria and glandular atrophy). The strains which carry cagA, vacAs1/m1, iceA2 and babA genes showed significant associations with severe active chronic gastritis (P = 0.011, 0.025, 0.020 and 0.031, respectively). The vacAs1 genotype had significant correlation with the presence of the cagA gene (P = 0.013). Also, babA genotype showed associations with cagA (P = 0.024). In the combined genotypes, only cagA+/vacAs1m1/iceA2/babA+ genotype showed correlation with severe active chronic gastritis (P = 0.025).
CONCLUSION: This genotyping panel can be a useful tool for detection of virulent H. pylori isolates and can provide valuable guidance for prediction of the clinical outcomes.
Helicobacter pylori; cagA; vacA; iceA; babA
We have shown that Helicobacter pylori induces tolerogenic programming of dendritic cells and inhibits the host immune response. Toll-like receptors (TLRs) represent a class of transmembrane pattern recognition receptors essential for microbial recognition and control of the innate immune response. In this study, we examined the role of TLRs in mediating H. pylori tolerogenic programming of dendritic cells and their impact on anti–H. pylori immunity using C57BL/6 wild-type and TLR2-knockout (TLR2KO) mice. We analyzed the response of TLR2KO bone marrow-derived dendritic cells (BMDCs) to H. pylori SS1 stimulation and the outcome of chronic H. pylori infection in TLR2KO mice. We showed that H. pylori–stimulated BMDCs upregulated the expression of TLR2, but not TLR4, TLR5, or TLR9. H. pylori-stimulated BMDCs from TLRKO mice induced lower Treg and Th17 responses, but a higher IFN-γ response compared to H. pylori-stimulated BMDCs from wild-type mice. In vivo analyses following an H. pylori infection of 2 months duration showed a lower degree of gastric H. pylori colonization in TLR2KO mice and more severe gastric immunopathology compared to WT mice. The gastric mucosa of the infected TLR2KO mice showed a lower mRNA expression of Foxp3, IL-10, and IL-17A, but higher expression of IFN-γ compared to the gastric mRNA expression in infected wild-type mice. Moreover, the H. pylori–specific Th1 response was higher and the Treg and Th17 responses were lower in the spleens of infected TLR2KO mice compared to infected WT mice. Our data indicate that H. pylori mediates immune tolerance through TLR2-derived signals and inhibits Th1 immunity, thus evading host defense. TLR2 may be an important target in the modulation of the host response to H. pylori.
AIM: To survey the antibiotic resistance pattern of Helicobacter pylori (H. pylori) strains isolated from Bhutanese population.
METHODS: We isolated 111 H. pylori strains from the gastric mucosa of H. pylori-infected patients in Bhutan in 2010. The Epsilometer test was used to determine the minimum inhibitory concentrations (MICs) of amoxicillin (AMX), clarithromycin (CLR), metronidazole (MNZ), levofloxacin (LVX), ciprofloxacin (CIP), and tetracycline (TET).
RESULTS: Nineteen of the isolated H. pylori strains were susceptible to all antibiotics tested. The isolated strains showed the highest rate of antibiotic resistance to MNZ (92/111, 82.9%). Among the 92 MNZ-resistant strains, 74 strains (80.4%) showed high-level resistance (MIC ≥ 256 μg/mL). Three strains were resistance to LVX (2.7%). These strains were also resistance to CIP. None of the strains showed resistance to CLR, AMX and TET.
CONCLUSION: CLR-based triple therapy is a more effective treatment approach over MNZ-based triple therapy for H. pylori infection in Bhutan.
Helicobacter pylori; Drug resistance; Bhutan
H. pylori can survive under a nutrition-deficient environment. During infection and transmission, H. pylori is confronted with nutrient limitation and the bacterium requires rapid alteration in gene expression for survival under stress conditions. However, the mechanism underlining this regulation remains unknown. A previous study showed that σ54 is an important regulation factor for H. pylori survival in the nutrition-deficient environment. Our results show that the expression of σ54 (rpoN) is significantly induced in the stationary phase (nutrition deficiency) and the rpoN mutant showed a significantly lower viability than wild-type H. pylori in the late stationary phase. Thus, σ54 is involved in H. pylori survival during nutrient limitation. We used comparative proteomics to analyze the protein differentiation between wild-type and rpoN mutant during the stationary phase. With depleted nutrients, σ54 can slow the process of proliferation by negatively regulating genes involved in energy metabolism and biosynthesis and enhance stress-resistant ability by positively regulating genes involved in protein fate and redox reaction. Especially, NapA positively regulated by σ54 plays an important function in H. pylori survival both in the stationary phase and in water, and the latter situation would be beneficial for bacterial in vitro transmission. Our investigations give new light on the adaptive regulation of H. pylori under stress conditions.
Although two studies have indicated a possible link between Alzheimer’s disease (AD) and Helicobacter pylori (H. pylori) infection, these were reported from Europe, where the prevalence of H. pylori infection is not very high. In this study, the prevalence of H. pylori infection was examined in AD patients in Japan, where there is a high prevalence of H. pylori. Consecutive patients referred to the Memory and Dementia Outpatient Clinic from August 2002 to March 2009 were studied. H. pylori infection status was determined by measuring urinary levels of anti-H. pylori antibody (RAPIRUN®). Multiple stepwise logistic regression analyses were used to examine the associations of AD with the main predictor variables. Of the 917 patients who visited the clinic, 385 were diagnosed as having AD. Ninety-seven patients did not have dementia and were considered controls. On univariate analysis, average age and the proportion of males were significantly higher in AD patients than in controls. There was no difference in the prevalence of H. pylori infection between patients with AD and controls (62.0% vs. 59.7%, p = 0.67, crude odds ratio (OR), 1.10). Multiple logistic regression analysis showed that older age and male sex, but not H. pylori status, were significantly associated with AD (p < 0.001, p = 0.01, p = 0.83, respectively). The prevalence of H. pylori infection did not differ between AD patients and controls among Japanese subjects. The high prevalence of H. pylori in controls may contribute to the discrepancy with previous reports.
Alzheimer’s disease; Helicobacter pylori; Urine test
The renin-angiotensin system (RAS) plays an important role not only in homeostasis but also in carcinogenesis. Recent epidemiological studies suggest that hypertensive patients with upregulated systemic RAS functions are at a significantly increased risk for the subsequent development of cancers with poor outcomes, and moreover that RAS inhibitors reduce tumor development, progression, and metastasis. Notably, Helicobacter pylori infection, one of the major predictors of gastric carcinogenesis, generally leads to RAS component overexpression, as exemplified by that of angiotensin I, angiotensin II, angiotensin I converting enzyme and angiotensin II receptor. Gastric mucosal RAS expression gradually increases with time after H. pylori infection with respect to the severity of inflammatory cell infiltration. Gastric carcinogenic potential is therefore considered to relate to RAS component expression levels and activities. This hypothesis is supported by findings that RAS genotypic variation can lead to high component expression levels (e.g. angiotensin I converting enzyme, chymase and angiotensinogen), and thereby increase the risk of development of gastric cancer. Thus, the RAS may be potently associated with the pathogenesis of H. pylori-related gastric carcinogenesis, and RAS inhibitors may provide tools for specifically preventing this disease.
chemoprevention; gastric cancer; Helicobacter pylori; renin-angiotensin system
Previous studies reported an epidemiological association between CagA-positive H. pylori strains and pre-eclampsia. As antibodies anti-CagA cross-react with endothelial cells and trophoblast cells show an endothelial phenotypic profile, we hypothesized that anti-CagA antibodies may recognize antigens of cytotrophoblast cells, thus impairing their function.
Materials and Methods
Placenta samples were obtained from healthy women. Cytotrophoblast cells were cultured in a medium containing increasing concentration of polyclonal anti-CagA antibodies. Binding of anti-CagA antibodies to cytotrophoblast cells was evaluated by cell ELISA and immunofluorescence assay. Invasive potential of those cells was assessed by an invasion culture system and by measuring of MMP-2. Protein sequencing was performed on antigens precipitated by anti-CagA antibodies. Measurement of phosphorylated ERK expression and NF-kB DNA-binding activity in trophoblast cells incubated with anti-CagA or irrelevant antibodies was also performed.
Anti-CagA antibodies recognized β-actin of cytotrophoblast cells, showing a dose-dependent binding. Incubation of cytotrophoblast cells with increasing doses of anti-CagA antibodies significantly reduced their invasiveness and determined a significant decrease in phosphorylated ERK expression and a reduced NF-kB translocation activity.
This study shows that anti-CagA antibodies recognize β-actin of cytotrophoblast cells, reducing their invasiveness ability, possibly giving a biological explanation for the epidemiological association.
CagA+; Helicobacter pylori; pregnancy
Background and Aim
The prevalence of allergic disorders, including asthma, atopic dermatitis, and allergic rhinitis has been increasing, and the prevalence of Helicobacter pylori (H. pylori) infection has been decreasing. Chronic bacterial infection during childhood is reported to protect the development of allergic diseases. The aim of the present study was to identify whether H. pylori infection influences the prevalence of allergic rhinitis, which has become a serious social problem, especially in the developed countries.
We initially investigated the association between the prevalence of H. pylori and pollinosis symptoms in 97 healthy volunteers.We had investigated the association between the serum H. pylori–immunoglobulin (Ig) G antibodies and specific IgE antibodies for pollen, mites, and house dust in 211 consecutive patients.
There were 52.2% (36/69) of H. pylori-negative volunteers with allergic symptoms, which was significantly higher than H. pylori-positive volunteers (14.3%, 4/28, P <0.05). The risk of pollinosis symptoms by H. pylori infection was 0.148 (95% confidence interval): 0.046–0.475, P <0.05). The prevalence of H. pylori infection increased according to age, whereas that of specific IgE-positive patients gradually decreased. Among the IgE-positive patients, the prevalence of H. pylori-negative patients was significantly higher than H. pylori-positive patients who were younger in age (P <0.05).
H. pylori infection decreased the pollinosis effects, especially among the younger volunteers. However, the prevalence of pollinosis in patients who were 50 years or older were almost same between H. pylori-positive and H. pylori-negative patients; therefore, the recent increase of pollinosis might relate to not only H. pylori infection, but also change in social environment.
allergic rhinitis; Helicobacter pylori; pollinosis
Certain populations with high incidences of Helicobacter pylori infection, such as those in East Asian countries, have high incidences of gastric cancer, while other highly infected populations, such as those in Africa and South Asia, do not. The various rates of gastric cancer associated with different geographic areas can be explained, at least in part, by the differences in the genotypes of H. pylori cagA and vacA. Populations expressing a high incidence of gastric cancer are mostly identical with regions where East Asian type CagA is predominant. In contrast, incidence of gastric cancer is low in Africa, South Asia, and Europe, where strains typically possess Western type CagA. Within East Asia, strains from northern parts, where the incidence of gastric cancer is high, predominantly possess the vacA m1 genotype, whereas the m2 genotype is predominant in southern parts where the gastric cancer incidence is low.
Helicobacter pylori; genotypes; gastric cancer; cagA; vacA
This review summarizes studies on the epidemiology and public health implications of Helicobacter pylori published in peer-reviewed journals from April 2010 through March 2011. Prevalence rates vary widely between different geographical regions and ethnic groups. An interesting study from the USA identified the degree of African ancestry as an independent predictor of H. pylori infection. Two studies have demonstrated early childhood as the period of transmission of infection and identified an infected sibling as an important risk factor. An oral–oral route of spread has been substantiated with several studies showing the presence of H. pylori in the oral cavity. Studies have shown the presence of H. pylori in drinking water and the role of poor living conditions and sanitation in H. pylori infection, supporting an oral–fecal route of spread. Screening for H. pylori as a gastric cancer prescreening strategy has been described in Japan, and the importance of H. pylori eradication as a gastric cancer–prevention strategy has now been further emphasized in Japanese guidelines. Two studies have shown a decrease in the burden of dyspepsia and peptic ulcer disease with H. pylori eradication.
H. pylori risk factors; transmission; prevalence; incidence
Mosaicism in vacA alleles with two distinct families of vacA signal sequences (s1 and s2) and two distinct families of middle region alleles (m1 and m2) has been reported. Research suggests that the vacA s1 genotype is closely associated with duodenal ulcer disease and with high cytotoxin production. The aims of this study were to evaluate the role of vacA genotyping with respect to gastric inflammation and injury, and clinical presentation in Iranian populations. Genomic DNA of biopsy specimens from patients with gastritis, peptic ulcer disease (PUD), or gastric cancer (GC) were characterized based on ureC (glmM), cagA, and vacA genotyping by using polymerase chain reaction. Of 167 patients including 33 with PUDs, 129 with non-ulcer dyspepsia (NUD), and 5 with GC, 96 (57.5%) cases were infected by Helicobacter pylori. Among these patients, H. pylori were isolated from 19 (57.7%) PUD patients, 74 (68.7%) NUD patients, and 3 (60%) GC patients. The cagA was detected in 76% of H. pylori-positive cases. The vacA s1-m2 genotype was the most prevalent in 7/19 PUD (37%) and 30/74 NUD (40.5%) patients with H. pylori infection. The prevalence of vacA s2-m1 (8%) was high in Iranian isolates. A significant association was not found between H. pylori genotypes and clinical outcomes. The vacA genotypes and cagA status were not useful markers for gastroduodenal diseases in Tehran, Iran.
Helicobacter pylori (H. pylori) infection can be significantly reduced by immunization in mice. Th17 cells play an essential role in the protective immune response. Th1 immunity has also been demonstrated to play a role in the protective immune response and can compensate in the absence of IL-17. To further address the potential of Th1 immunity, we investigated the efficacy of immunization in mice deficient in IL-23p19, a cytokine that promotes Th17 cell development. We also examined the course of Helicobacter infection in unimmunized mice treated with Th1 promoting cytokine IL-12. C57BL/6, IL-12 p35 KO, and IL-23 p19 KO mice were immunized and challenged with H. pylori. Protective immunity was evaluated by CFU determination and QPCR on gastric biopsies. Gastric and splenic IL-17 and IFNγ levels were determined by PCR or by ELISA. Balb/c mice were infected with H. felis and treated with IL-12 therapy and the resulting gastric bacterial load and inflammatory response were assessed by histologic evaluation. Vaccine induced reductions in bacterial load that were comparable to wild type mice were observed in both IL-12 p35 and IL-23 p19 KO mice. In the absence of IL-23 p19, IL-17 levels remained low but IFNγ levels increased significantly in both immunized challenged and unimmunized/challenged mice. Additionally, treatment of H. felis-infected Balb/c mice with IL-12 resulted in increased gastric inflammation and the eradication of bacteria in most mice. These data suggest that Th1 immunity can compensate for the lack of IL-23 mediated Th17 responses, and that protective Th1 immunity can be induced in the absence of immunization through cytokine therapy of the infected host.
Helicobacter pylori contains a pathogenicity island, cagPAI, with genes homologous to components of the type IV secretion system (T4SS) of Agrobacterium tumefaciens. The T4SS components assemble a structure that transfers CagA protein and peptidoglycan into host epithelial cells, causing the increased release of interleukin 8 (IL8) from the cells. The Toll-like receptors on neutrophils recognize H. pylori, initiating signaling pathways that enhance the activation of NF-κB. However, the roles of cagPAI and T4SS in the inflammatory response of neutrophils are unknown. We evaluated the participation of cagPAI and T4SS in the response of human neutrophils to H. pylori infection. Neutrophils were isolated from the blood of healthy donors and infected with H. pylori cagPAI+, cagPAI–, and cagPAI mutant strains virB4– and virD4–. Whereas cagPAI+ strain 26695 induced the greatest IL8 production, a proinflammatory response, cagPAI– strain 8822 induced the greatest IL10 production, an anti-inflammatory response. In contrast, the virB4– and virD4– mutant strains produced significantly more of the two proinflammatory cytokines IL1β and tumor necrosis factor αthan the cagPAI+ strain 26695. We observed that H. pylori downregulated the expression of TLRs 2 and 5 but upregulated TLR9 expression in a cagPAI and T4SS-independent manner. These results show for the first time that the response of human neutrophils to H. pylori may vary from a pro-inflammatory to an anti-inflammatory response, depending on cagPAI and the integrity of T4SS.
Interaction of Helicobacter pylori with gastric mucosa leads to marked cellular and humoral host immunological responses. The signaling pathways initiated by bacteria-host interaction that result in perturbations in cell structure and function remain unclear. Forkhead transcription factors of class O (FoxO) are implicated in the regulation of apoptosis, cell survival, and pathogenesis. H. pylori infection of gastric epithelial cells induces phosphoinositide-3 kinase (PI3K)-dependent Akt activation and cell survival signaling. We investigated the role of H. pylori-activated PI3K/Akt in the regulation of FoxO1/3a in gastric cells.
Immunoblot, immunoprecipitation, and fluorescence microscopy were used to assess the effect of infection of gastric epithelial cells with wild-type H. pylori and their isogenic cag pathogenicity island (PAI) or oipA mutants on the FoxO1/3a signaling pathways. Interleukin-8 release was determined by enzyme-linked immunosorbent assays.
H. pylori infection resulted in activation of the PI3K p85 subunit and inactivation of FoxO1 and FoxO3a by their phosphorylation and translocation of from the nucleus to the cytoplasm. Inhibition of PI3K or Akt kinase activity reduced FoxO1/3a phosphorylation. Akt, FoxO1, or FoxO3a siRNA reduced H. pylori-induced interleukin-8 production. Infection with oipA mutants reduced PI3K/Akt activation and inhibited FoxO1/3a phosphorylation, whereas infection with cag PAI mutants reduced PI3K/Akt activity but did not inhibit FoxO1/3a activation.
FoxO1 and FoxO3a are novel nuclear substrates of H. pylori-induced PI3K/Akt cell survival signaling pathways that partially control interleukin-8 production. OipA-regulated interleukin-8 release through PI3K/Akt is dependent on FoxO1/3a inactivation whereas cag PAI-mediated interleukin-8 production employs FoxO1/3-independent signaling.
AIM: To revealed the prevalence of Helicobacter pylori (H. pylori) infection in the Bhutanese population.
METHODS: We recruited a total of 372 volunteers (214 females and 158 males; mean age of 39.6 ± 14.9 years) from three Bhutanese cities (Thimphu, Punaka, and Wangdue). The status of H. pylori infection was determined based on five different tests: the rapid urease test (CLO test), culture, histology, immunohistochemistry (IHC), and serum anti H. pylori-antibody.
RESULTS: The serological test showed a significantly higher positive rate compared with the CLO test, culture, histology and IHC (P < 0.001, P < 0.001, P = 0.01, and P = 0.01, respectively). When the subjects were considered to be H. pylori positive in the case of at least one test showing a positive result, the overall prevalence of H. pylori infection in Bhutan was 73.4%. The prevalence of H. pylori infection significantly decreased with age (P < 0.01). The prevalence of H. pylori infection was lower in Thimphu than in Punakha and Wangdue (P = 0.001 and 0.06, respectively). The prevalence of H. pylori infection was significantly higher in patients with peptic ulcers than in those with gastritis (91.4% vs 71.3%, P = 0.003).
CONCLUSION: The high incidence of gastric cancer in Bhutan may be attributed to the high prevalence of H. pylori infection.
Helicobacter pylori; Bhutan; Prevalence
H. pylori infection is acquired during childhood and causes a chronic inflammatory response in the gastric mucosa, which is considered the main risk factor to acquire gastric cancer (GC) later in life. More recently, infection by Epstein-Barr virus (EBV) have also been associated with GC. The role of EBV in early inflammatory responses and its relationship with H. pylori infection remains poorly studied. Here, we assessed whether EBV infection in children correlated with the stage of gastritis and whether co-infection with H. pylori affected the severity of inflammation.
333 pediatric patients with chronic abdominal pain were studied. From them, gastric biopsies were taken and inflammation graded according to the Sydney system; peripheral blood was drawn and antibodies against EBV (IgG and IgM anti-VCA) and H. pylori (IgG anti-whole bacteria and anti-CagA) were measured in sera. We found that children infected only by EBV presented mild mononuclear (MN) and none polymorphonuclear (PMN) cell infiltration, while those infected by H. pylori presented moderate MN and mild PMN. In contrast, patients co-infected with both pathogens were significantly associated with severe gastritis. Importantly, co-infection of H. pylori CagA+/EBV+ had a stronger association with severe MN (PR 3.0) and PMN (PR 7.2) cells than cases with single H. pylori CagA+ infection.
Co-infection with EBV and H. pylori in pediatric patients is associated with severe gastritis. Even single infections with H. pylori CagA+ strains are associated with mild to moderate infiltration arguing for a cooperative effect of H. pylori and EBV in the gastric mucosa and revealing a critical role for EBV previously un-appreciated. This study points out the need to study both pathogens to understand the mechanism behind severe damage of the gastric mucosa, which could identified children with increased risk to present more serious lesions later in life.
Chronic Helicobacter pylori infection provokes an inflammation of the gastric mucosa, at high risk for ulcer and cancer development. The most virulent strains harbor the cag pathogenicity island (cagPAI) encoding a type 4 secretion system, which allows delivery of bacterial effectors into gastric epithelial cells, inducing pro-inflammatory responses and phenotypic alterations reminiscent of an epithelial-to-mesenchymal transition (EMT). This study characterizes EMT features in H. pylori-infected gastric epithelial cells, and investigates their relationship with NF-κB activation. Cultured human gastric epithelial cell lines were challenged with a cagPAI+ H. pylori strain or cag isogenic mutants. Morphological changes, epithelial and mesenchymal gene expression and EMT-related microRNAs were studied. H. pylori up-regulates mesenchymal markers, including ZEB1. This transcription factor is prominently involved in the mesenchymal transition of infected cells and its up-regulation depends on cagPAI and NF-κB activation. ZEB1 expression and NF-κB activation were confirmed by immunohistochemistry in gastric mucosa from cagPAI+ H. pylori-infected patients. Gastric epithelial cell lines express high miR-200 levels, which are linked to ZEB1 in a reciprocal negative feedback loop and maintain their epithelial phenotype in non-infected conditions. However, miR-200b/c were increased upon infection, despite ZEB1 up-regulation and mesenchymal morphology. In the miR-200b-200a-429 cluster promoter, we identified a functional NF-κB binding site, recruiting NF-κB upon infection and trans-activating the microRNA cluster transcription. In conclusion, in gastric epithelial cells, cagPAI+ H. pylori activates NF-κB, which transactivates ZEB1, subsequently promoting mesenchymal transition. The unexpected N-FκB-dependent increase of miR-200 levels likely thwarts the irreversible loss of epithelial identity in that critical situation.
To determine whether the presence of dupA Helicobacter pylori (H. pylori) influences the cure rate of primary eradication therapy.
Several virulence factors of H. pylori have been reported to affect the efficacy of the eradication rate. However, no study has investigated whether the presence of dupA affects eradication failure.
The presence of dupA was evaluated in 142 H. pylori strains isolated from 142 patients with gastrointestinal diseases. Of these patients, 104 received primary eradication therapy for 1 week. The risk factors for eradication failure were determined using univariate and multivariate analyses.
Among 142 strains, 44 (31.0%) were dupA-positive. There was no association between dupA status and gastroduodenal diseases (P > 0.05). The clarithromycin (CLR) resistance rate was generally lower in the dupA-positive than in the dupA-negative group (20.4 vs. 35.7%, P = 0.06). However, dupA prevalence was higher in the eradication failure group than in the success group (36.3 vs. 21.9%). Among the CLR-resistant H. pylori infected group, the successful eradication rate was significantly lower in patients infected with dupA-positive H. pylori than -negative H. pylori (P = 0.04). In multivariate analysis adjusted for age, gender, and type of disease, not only CLR resistance but also dupA presence was independent risk factors for eradication failure (adjusted odds ratio = 3.71, 95% confidence interval = 1.07–12.83).
Although CLR resistant was more reliable predictor, the presence of dupA may also be an independent risk factor for eradication failure.
Helicobacter pylori; dupA; eradication rate
Helicobacter pylori infection leads to an inflammatory response in 100% of infected individuals. The inflammatory cells which are recruited to the gastric mucosa during infection produce several pro- and anti-inflammatory cytokines including several cytokines in the interleukin-17 family. The anti-inflammatory cytokine, interleukin 25 (IL-25, also known as IL-17E), signals through a receptor, which is a heterotrimeric receptor comprised of two IL-17 receptor A subunits and an IL-17 receptor B subunit. Previous studies in our laboratory demonstrated that IL-17RA is required to control infection with Helicobacter pylori in the mouse model. Moreover, the absence of IL-17 receptor A leads to a significant B cell infiltrate and a remarkable increase in lymphoid follicle formation in response to infection compared to infection in wild-type mice. We hypothesized that IL-25, which requires both IL-17 receptor A and IL-17 receptor B for signaling, may play a role in control of inflammation in the mouse model of Helicobacter pylori infection. IL-17 receptor B deficient mice, IL-17 receptor A deficient mice and wild-type mice were infected with Helicobacter pylori (strains SS1 and PMSS1). At several time points H. pylori- infected mice were sacrificed to investigate their ability to control infection and inflammation. Moreover, the effects of IL-17 receptor B deficiency on T helper cytokine expression and H. pylori- specific serum antibody responses were measured. IL-17 receptor B−/− mice (unlike IL-17 receptor A−/− mice) exhibited similar or modest changes in gastric colonization, inflammation, and Th1 and Th17 helper cytokine responses to wild-type mice infected with Helicobacter pylori. However, H. pylori-infected IL-17 receptor B−/− mice have reduced expression of IL-4 and lower serum IgG1 and IgG2a levels compared to infected IL-17 receptor A−/− and wild-type mice. These data indicate that signaling through the IL-17 receptor B subunit is not necessary for control of Helicobacter pylori in our model.
Helicobacter pylori infection is linked to various gastroduodenal diseases; however, only approximately 20% of infected individuals develop severe diseases. Despite the high prevalence of H. pylori infection in Africa and South Asia, the incidence of gastric cancer in these areas is much lower than in other countries. Furthermore, the incidence of gastric cancer tends to decrease from north to south in East Asia. Such geographic differences in the pathology can be explained, at least in part, by the presence of different types of H. pylori virulence factors, especially cagA, vacA, and the right end of the cag pathogenicity island. The genotype of the virulence genes is also useful as a tool to track human migration utilizing the high genetic diversity and frequent recombination between different H. pylori strains. Multilocus sequence typing (MLST) analysis using 7 housekeeping genes can also help predict the history of human migrations. Population structure analysis based on MLST has revealed 7 modern population types of H. pylori, which derived from 6 ancestral populations. Interestingly, the incidence of gastric cancer is closely related to the distribution of H. pylori populations. The different incidence of gastric cancer can be partly attributed to the different genotypes of H. pylori circulating in different geographic areas. Although approaches by MLST and virulence factors are effective, these methods focus on a small number of genes and may miss information conveyed by the rest of the genome. Genome-wide analyses using DNA microarray or whole-genome sequencing technology give a broad view on the genome of H. pylori. In particular, next-generation sequencers, which can read DNA sequences in less time and at lower costs than Sanger sequencing, enabled us to efficiently investigate not only the evolution of H. pylori, but also novel virulence factors and genomic changes related to drug resistance.
Helicobacter pylori; cagA; vacA; multilocus sequence typing; whole genome sequencing technology; next-generation sequencer
Previous studies have demonstrated that valosin-containing protein (VCP) is associated with H. pylori-induced gastric carcinogenesis. By identifying the interactome of VCP overexpressed in AGS cells using a subtractive proteomics approach, we aimed to characterize the cellular responses mediated by VCP and its functional roles in H. pylori-associated gastric cancer. VCP immunoprecipitations followed by proteomic analysis identified 288 putative interacting proteins, 18 VCP-binding proteins belonged to the PI3K/Akt signaling pathway. H. pylori infection increased the interaction between Akt and VCP, Akt-dependent phosphorylation of VCP, levels of ubiquitinated proteins, and aggresome formation in AGS cells. Furthermore, phosphorylated VCP co-localized with the aggresome, bound ubiquitinated proteins, and increased the degradation of cellular regulators to protect H. pylori-infected AGS cells from apoptosis. Our study demonstrates that VCP phosphorylation following H. pylori infection promotes both gastric epithelial cell survival, mediated by the PI3K/Akt pathway, and the degradation of cellular regulators. These findings provide novel insights into the mechanisms of H. pylori infection induced gastric carcinogenesis.