Gastric infection by Helicobacter pylori. Curr Gastroenterol Rep. 2009;11:455-461. [PMID: 19903421 DOI: 10.1007/s11894-009-0070-y]

Challenges for developing bacterial CA inhibitors as novel antibiotics

Acetazolamide, methazolamide, ethoxzolamide and dorzolamide, classical sulfonamide carbonic anhydrase (CA) inhibitors (CAIs) designed for targeting human enzymes, were also shown to effectively inhibit bacterial CAs and were proposed for repurposing as antibacterial agents against several infective agents. CAs belonging to the α-, β- and/or γ-classes from pathogens such as Helicobacter pylori, Neisseria gonorrhoeae, vacomycin resistant enterococci (VRE), Vibrio cholerae, Mycobacterium tuberculosis, Pseudomonas aeruginosa and other bacteria were considered as drug targets for which several classes of potent inhibitors have been developed. Treatment of some of these pathogens with various classes of such CAIs led to an impairment of the bacterial growth, reduced virulence and for drug resistant bacteria, a resensitization to clinically used antibiotics. Here I will discuss the strategies and challenges for obtaining CAIs with enhanced selectivity for inhibiting bacterial versus human enzymes, which may constitute an important weapon for addressing the drug resistance to β-lactams and other clinically used antibiotics.

Novel carbonic anhydrase inhibitors for the treatment of Helicobacter pylori infection

INTRODUCTION

Helicobacter pylori, the causative agent of peptic ulcer, gastritis, and gastric cancer encodes two carbonic anhydrases (CA, EC 4.2.1.1) belonging to the α- and β-class (HpCAα/β), which have been validated as antibacterial drug targets. Acetazolamide and ethoxzolamide were also clinically used for the management of peptic ulcer.

AREAS COVERED

Sulfonamides were the most investigated HpCAα/β compounds, with several low nanomolar inhibitors identified, some of which also crystallized as adducts with HpCAα, allowing for the rationalization of the structure-activity relationship. Few data are available for other classes of inhibitors, such as phenols, sulfamides, sulfamates, dithiocarbamates, arylboronic acids, some of which showed effective in vitro inhibition and for phenols, also inhibition of planktonic growth, biofilm formation, and outer membrane vesicles spawning.

EXPERT OPINION

Several recent drug design studies reported selenazoles incorporating seleno/telluro-ethers attached to benzenesulfonamides, hybrids incorporating the EGFR inhibitor erlotinib and benzenesulfonamides, showing KIs < 100 nM against HpCAα and MICs in the range of 8-16 µg/mL for the most active derivatives. Few drug design studies for non-sulfonamide inhibitors were performed to date, although inhibition of these enzymes may help the fight of multidrug resistance to classical antibiotics which emerged in the last decades also for this bacterium.

An overview of novel antimicrobial carbonic anhydrase inhibitors

INTRODUCTION

Four different genetic families of the enzyme carbonic anhydrase (CA, EC 4.2.1.1) are present in bacteria, α-, β-, γ- and ι-CAs. They play relevant functions related to CO2, HCO3-/H+ ions homeostasis, being involved in metabolic biosynthetic pathways, pH regulation, and represent virulence and survival factors for bacteria in various niches. Bacterial CAs started to be considered druggable targets in the last decade, as their inhibition impairs survival, growth, and virulence of these pathogens.

AREAS COVERED

Significant advances were registered in the last years for designing effective inhibitors of sulfonamide type for Helicobacter pylori α-CA, Neisseria gonorrhoeae α-CA, vacomycin-resistant enterococci (VRE) α- and γ-CAs, for which the in vivo validation has also been achieved. MIC-s in the range of 0.25-4.0 µg/mL for wild type and drug resistant N. gonorrhoeae strains, and of 0.007-2.0 µg/mL for VRE were observed for some 1,3,4-thiadiazole-2-sulfonamides, and acetazolamide was effective in gut decolonization from VRE.

EXPERT OPINION

Targeting bacterial CAs from other pathogens, among which Vibrio cholerae, Mycobacterium tuberculosis, Brucella suis, Salmonella enterica serovar Typhimurium, Legionella pneumophila, Porphyromonas gingivalis, Clostridium perfringens, Streptococcus mutans, Burkholderia pseudomallei, Francisella tularensis, Escherichia coli, Mammaliicoccus (Staphylococcus) sciuri, Pseudomonas aeruginosa, may lead to novel antibacterials devoid of drug resistance problems.

Implications of the paradigm shift in management of Helicobacter pylori infections

The recent availability of susceptibility testing for Helicobacter pylori infections in the United Sates has resulted in paradigm shifts in the diagnosis, therapy, and follow-up of H. pylori infections. Here, we reviewed the English literature concerning changes in H. pylori diagnosis and therapy with an emphasis on the last 3 years. We focus on the new methods that offer rapid and convenient susceptibility testing using either invasive (endoscopic) or noninvasive (stool) methods of obtaining test material. We also discuss the implications of this availability on therapy and follow-up after therapy. The approach to therapy was categorized into four groups: (1) therapies that can be used empirically, (2) therapies that should be restricted to those that are susceptibility-based, (3) potentially effective therapies that have yet to be optimized for local use, and (4), therapies that contain unneeded antibiotics that should not be prescribed. The most convenient and efficient method of susceptibility testing is by using reflexive stool testing in which if the sample is positive, it is automatically also used for determination of susceptibility. Reflexive testing can also be done via reflexive ordering (e.g., for all positive urea breath tests). The post therapy test-of-cure has emerged as a critical component of therapy as it not only provides feedback regarding treatment success but when combined with susceptibility testing also provide evidence regarding the cause of failure (e.g., poor adherence versus emergence of resistance during therapy. Susceptibility testing has made even the most current H. pylori guidelines for diagnosis and therapy generally obsolete. Clarithromycin, metronidazole, and levofloxacin triple therapies should only be administered as susceptibility-based therapy. Regimens containing unneeded antibiotics should not be given. We provide recommendations regarding the details and indications for all current therapies.

Helicobacter pylori infection enhances heparanase leading to cell proliferation via mitogen‑activated protein kinase signalling in human gastric cancer cells

Helicobacter pylori (H. pylori) infection is the most important factor in the development of gastric cancer. Heparanase (HPA) is involved in tissue remodelling and cell migration, which leads to inflammation and tumour metastasis. The current study aimed was to explore whether a H. pylori infection leads to an increase in the level of HPA in gastric cancer and to investigate the specific mechanism underlying this association. Reverse transcription‑polymerase chain reaction and western blotting were used to detect HPA mRNA and protein expression, respectively, in MKN‑45 cells infected by H. pylori, MKN‑45 cells treated with the mitogen‑activated protein kinase (MAPK) inhibitor SB203580 and MKN‑45 cells transfected with small interfering RNA against HPA. MAPK and nuclear factor (NF)‑κB expression were determined by western blotting in the different cells group. Cell Counting Kit‑8, Transwell method, and Scratch and Clone tests were conducted to detect proliferation, invasion, migration and clone formation ability of gastric cancer cells. It was demonstrated that HPA mRNA expression was highest at 6 h post‑infection, while the expression of the HPA protein was highest at 24 h post‑infection in H. pylori‑infected gastric cancer cells. Furthermore, it was demonstrated that H. pylori infection significantly enhanced the expression of MAPK and NF‑κB in MKN‑45 cells at the mRNA and protein levels. SB203580 significantly decreased the expression of NF‑κB in MKN‑45 cells infected with H. pylori. Exposure to SB203580 also significantly decreased the expression of HPA. In the present study, the inhibition of HPA significantly lowered H. pylori‑induced cell proliferation, suggesting that H. pylori infection induces the proliferation of gastric cancer cells through the upregulation of HPA. Taken together, the results of the present study demonstrated that HPA serves a critical role in the development of gastric cancer in H. pylori‑infected cells, which may be an important mechanism through which H. pylori infection leads to gastric cancer. In addition, H. pylori infection promotes the proliferation, invasion and metastasis of gastric cancer cells through the upregulation of HPA expression, and this is likely mediated via the MAPK and NF‑κB signalling pathways. These data suggest that HPA can be used as a therapeutic target in gastric cancer, particularly in cases induced by H. pylori infection.

Detection of Helicobacter pylori by Real-Time PCR for 16s rRNA in Stools of NonInfected Healthy Children, Using ELISA Antigen Stool Test as the Gold Standard

BACKGROUND

We previously detected Helicobacter pylori infection by stool antigen ELISA assay in 33-41% of asymptomatic Chilean children between 2-3 years of age, of which 11-20% had a transient infection and 21-22% a persistent infection. A total of 88% of ELISA-positive samples were also rtPCR positive, while 37/133 (33%) of ELISA-negative stool samples were rtPCR positive. The significance of a ELISA-negative/rtPCR-positive sample requires clarification. We aimed to determine whether rtPCR is able to detect persistent infections not detected by ELISA.

MATERIALS AND METHODS

We selected 36 children with an ELISA-negative/rtPCR-positive stool sample, of which 25 were never H. pylori infected according to ELISA, and 11 had a transient infection with an ELISA-positive sample before or after the discordant sample. At least two additional consecutive ELISA-negative samples per child were tested in duplicate by rtPCR for the 16s rRNA gene.

RESULTS

A total of 14 of 78 (17.9%) rtPCR reactions were positive, but only 4/78 (5.1%) were positive in both duplicates, representing a total of 3/36 (8.3%) children with an additional rtPCR-positive sample, only one of whom was persistently negative by ELISA. One child with a transient infection had two positive rtPCR reactions despite negative ELISA samples.

CONCLUSIONS

In H. pylori noninfected or transiently infected children, as determined by stool ELISA, additional ELISA-negative/rtPCR-positive stool samples were found in 8.3% of children, but a possible persistent infection was only identified in 2.7% of children. Thus, the characterization of infection dynamics in children is not being misrepresented by application of stool ELISA. Furthermore, rtPCR does not significantly improve dynamic characterization.

Gene polymorphisms of pathogenic Helicobacter pylori in patients with different types of gastrointestinal diseases

Helicobacter pylori (H. pylori) is a kind of chronic infectious pathogen which can cause chronic gastritis, peptic ulcer, gastric cancer and other diseases. The genetic structure of the pathogenic genes of H. pylori varies largely, which contributes to the differences in virulence among various strains, and in clinical symptoms. Virulence genes of H. pylori can be categorized into three main classes: those related to adhesion and colonization, those related to gastric mucosal injury, and others. This review focuses on the relationship between genetic polymorphisms of the three classes of virulence genes of H. pylori and diseases. Most of the genetic polymorphisms of the main virulence factors of H. pylori are summarized in this paper.

HIV-Helicobacter pylori Co-Infection: Antibiotic Resistance, Prevalence, and Risk Factors

Background

Patients infected with human immunodeficiency virus (HIV) are living longer due to the availability of more potent treatments. However, prescription of antibiotics to treat or prevent infections in these patients may increase the likelihood of co-infection with antibiotic-resistant species.

Aim

To compare antimicrobial susceptibility of Helicobacter pylori (H. pylori) in HIV-positive and HIV-negative patients and assess risk-factors for resistance.

Methods

We prospectively collected data from consecutive HIV-positive and HIV-negative patients undergoing upper gastrointestinal endoscopy. Patients with H. pylori-positive gastric biopsies who had never received H. pylori treatment were included.

Results

Of the 353 patients included, 93 were HIV-positive and 260 HIV-negative. Among the HIV-positive patients, 56 (60%) had been infected for <10 years, the median CD4+ count was 493 cells/μl and median viral load was 61 copies/mL; 66 (71%) were receiving antiretroviral therapy. HIV-positive patients were more often male (p = 0.009), had a lower body mass index (p<0.0001), and had less frequently received antibiotics during the 12-months prior to the endoscopy (p<0.0001) than HIV-negative patients. HIV-positive patients were more likely to have H. pylori resistant to levofloxacin (p = 0.0004), metronidazole (p = 0.01), or multiple antibiotics (p = 0.006). HIV-positive Black Africans were more likely to have resistant strains than were HIV-negative Black Africans (p = 0.04). Ethnicity and HIV status were independent risk factors for H. pylori resistance in all patients and acquired immune deficiency syndrome (AIDS) and sex were risk factors in HIV-positive patients.

Conclusions

There was a higher prevalence of primary H. pylori-resistant strains in HIV-positive than in HIV-negative patients. AIDS and sex were predictors of H. pylori resistance in HIV-positive patients.

High-dose extended-release lansoprazole (dexlansoprazole) and amoxicillin dual therapy for Helicobacter pylori infections

BACKGROUND

Helicobacter pylori infections have become increasingly difficult to treat.

AIM

To examine whether amoxicillin and high-dose dexlansoprazole would reliably achieve an H. pylori eradication rate of ≥90%.

METHODS

An open-label prospective pilot study of H. pylori eradication in treatment-naïve subjects with active H. pylori infection (positive by two tests).

THERAPY

amoxicillin 1 g and dexlansoprazole 120 mg each twice a day at approximately 12-hour intervals for 14 days. Success was accessed by urea breath test. An effective therapy was defined as a per-protocol treatment success of 90% or greater; treatment success of 80% or less was prespecified as an unacceptable result.

RESULTS

After 13 subjects were entered (12 men, one woman; average age of 54 years), the prespecified stopping rule of six treatment failures was achieved (i.e., the 95% confidence interval excluded achieving the required 90% success rate even if the proposed study of 50 completed patients were entered) and enrollment was stopped. Per-protocol and intention-to-treat treatment success were both 53.8%; (7/13); 95% CI = 25-80%. Compliance was 100%. Three patients (23%) reported side effects, all of which were mild and none interrupted therapy.

CONCLUSION

Theoretically, dual PPI plus amoxicillin should reliably eradicate H. pylori provided nearly neutral intragastric pH can be maintained. Clearly, dexlansoprazole, despite being administered at high dose and twice a day (i.e., total daily dose 240 mg), failed to achieve an intragastric milieu consistent with dual PPI plus amoxicillin therapy being an effective anti-H. pylori regimen.

Mechanisms of molecular transport through the urea channel of Helicobacter pylori

Helicobacter pylori survival in acidic environments relies on cytoplasmic hydrolysis of gastric urea into ammonia and carbon dioxide, which buffer the pathogen’s periplasm. Urea uptake is greatly enhanced and regulated by HpUreI, a proton-gated inner membrane channel protein essential for gastric survival of H. pylori. The crystal structure of HpUreI describes a static snapshot of the channel with two constriction sites near the center of the bilayer that are too narrow to allow passage of urea or even water. Here we describe the urea transport mechanism at atomic resolution, revealed by unrestrained microsecond equilibrium molecular dynamics simulations of the hexameric channel assembly. Two consecutive constrictions open to allow conduction of urea, which is guided through the channel by interplay between conserved residues that determine proton rejection and solute selectivity. Remarkably, HpUreI conducts water at rates equivalent to aquaporins, which might be essential for efficient transport of urea at small concentration gradients.

Helicobacter pylori survives in the acidic environment of the stomach by taking up urea and converting it to ammonia and carbon dioxide, which buffer the bacterial periplasm. Using molecular dynamics simulations, McNulty et al. provide insight into the mechanism of urea uptake through the H. pylori urea transporter.

Protein-Loosing Entropathy Induced by Unique Combination of CMV and HP in an Immunocompetent Patient

Protein-losing gastroenteropathies are characterized by an excessive loss of serum proteins into the gastrointestinal tract, resulting in hypoproteinemia (detected as hypoalbuminemia), edema, and, in some cases, pleural and pericardial effusions. Protein-losing gastroenteropathies can be caused by a diverse group of disorders and should be suspected in a patient with hypoproteinemia in whom other causes, such as malnutrition, proteinuria, and impaired liver protein synthesis, have been excluded. In this paper, we present a case of protein-losing enteropathy in a 22-year-old immunocompetent male with a coinfection of CMV and Hp.

Inhibition of H. pylori colonization and prevention of gastritis in murine model

Helicobacter pylori is a Gram-negative spiral bacterium that colonizes human gastric mucosa causing infection. In this study aiming at inhibition of H. pylori infection we made an attempt to evaluate immunogenicity of the total (UreC) and C-terminal (UreCc) fragments of H. pylori urease. Total UreC and its C-terminal fragment were expressed in E. coli. Recombinant proteins were analyzed by SDS-PAGE and western blot and then purified by Ni-NTA affinity chromatography. Female C57BL6/j mice were immunized with the purified proteins (UreC and UreCc). Antibody titers from isolated sera were measured by ELISA. Immunized mice were then challenged by oral gavage with live H. pylori Sydney strain SS1. Total of 109 CFU were inoculated into stomach of immunized and unimmunized healthy mice three times each at one day interval. Eight weeks after the last inoculation, the blood sample was collected and the serum antibody titer was estimated by ELISA. Stomach tissues from control and experimental animal groups were studied histopathologically. UreC and UreCc yielded recombinant proteins of 61 and 31 kDa respectively. ELIZA confirmed establishment of immunity and the antibodies produced thereby efficiently recognized H. pylori and inhibited its colonization in vivo. Pathological analysis did not reveal established infection in immunized mice challenged with H. pylori. The results support the idea that UreC and UreCc specific antibodies contribute to protection against H. pylori infections.

Increased Toll-like receptor 9 expression indicates adverse prognosis in oesophageal adenocarcinoma

AIMS

Toll-like receptor 9 (TLR-9) is a cellular DNA receptor that has been linked previously to invasion in various cancers. The aim of this study was to investigate TLR-9 expression and its possible association with prognosis in oesophageal adenocarcinoma.

METHODS AND RESULTS

Immunohistochemical TLR-9 expression was graded in clinical specimens (n = 76) of oesophageal adenocarcinoma. The TLR-9 immunostaining intensity was compared with tumour grade, stage and indicators of proliferation, apoptosis and tumour vascular supply. High TLR-9 expression correlated with advanced tumour stage, tumour unresectability, poor differentiation and high proliferation. Strong immunoreactivity of TLR-9 also indicated poor overall survival.

CONCLUSIONS

High TLR-9 expression is associated with poor differentiation, a high proliferation rate and disseminated disease. Accordingly, increased TLR-9 expression may contribute to the growth and metastatic properties of oesophageal adenocarcinoma.

Oral immunization with recombinant Mycobacterium smegmatis expressing the outer membrane protein 26-kilodalton antigen confers prophylactic protection against Helicobacter pylori infection

Helicobacter pylori infection is prevalent worldwide and results in chronic gastritis, which may lead to gastric mucosa-associated lymphoid tissue lymphoma and gastric cancer. We have previously reported that oral immunization with recombinant Mycobacterium smegmatis expressing the H. pylori outer membrane protein 26-kilodalton (Omp26) antigen affords therapeutic protection against H. pylori infection in mice. In the present study, we investigated the prophylactic effects of this vaccine candidate on H. pylori challenge in mice. We found that oral immunization with recombinant Mycobacterium Omp26 significantly reduced H. pylori colonization in the stomach compared to inoculation with wild-type M. smegmatis in control mice. Six of the recombinant Mycobacterium-immunized mice (60%) were completely protected from H. pylori infection. The severity of H. pylori-associated chronic gastritis assessed histologically was significantly milder in mice vaccinated with recombinant Mycobacterium than in control animals. Mice immunized with recombinant Mycobacterium showed enhanced antigen-specific lymphocyte proliferation and antibody responses. Moreover, immunization with recombinant Mycobacterium resulted in an increased expression of interleukin-2 and gamma interferon in the stomach and spleen, as determined by reverse transcription-PCR analysis. Our results collectively suggest that vaccination with recombinant Mycobacterium Omp26 confers prophylactic protection against H. pylori infection. The inhibition of H. pylori colonization is associated with the induction of antigen-specific humoral and cell-mediated immune responses.

[Helicobacter pylori -- 2010]

Helicobacter pylori, discovered 27 years ago, has remained the most prevalent infectious agent in the world. In the author's hypothesis, the increase of peptic ulcer prevalence in the 19-20th century could be attributable to the extended worldwide use of gastric tubes for secretory testing which led to the iatrogenic transmission of pathogenic strains. Helicobacter pylori outer membrane proteins (OMP), and duodenal ulcer promoting (dupA) proteins were identified as novel virulence factors, leading to the production of pro-inflammatory cytokines, which could be future targets of therapy. There is no ideal first-line eradication of the infection and according to expert's opinion, the efficiency of these regimens has fallen gradually in recent years to unacceptably low levels; however, in the author's opinion this is a multifactorial phenomenon which can not be generalized. As alternative drugs, the efficiency of levofloxacin, furazolidone and rifabutin has been proven by meta-analyses. Sequential and bismuth-free quadruple therapies, although highly efficient, are not yet used on a large scale. The recurrence of the infection is 2.27%/year in developed and of 13.0%/year in developing countries. Spontaneous eradication occurred in 8-20% of the children and 5-11% of adults. The prevalence of clarithromycin resistance is increasing worldwide. In Hungary, it has reached 10.9% in county cities, according to a national survey. In a district of Budapest called Ferencváros, the prevalence between 2005 and 2009 was 16-22%, with no increasing trend. The development of enzymatic inhibitors (urease, carbonic anhydrase and gamma-glutamyl transpeptidase), modified antibiotics and efflux pump inhibitors seem promising ways because these compounds do not lead to resistance; however, none have yet been used in humans.

Use of proton pump inhibitors and risk of hip/femur fracture: a population-based case-control study

Previous studies evaluated the association between proton pump inhibitor (PPI) use and subsequent fracture risk, but they showed ambiguous results. Therefore, the objective was to evaluate this association in a different study population. Our findings show that there is probably no causal relationship between PPI use and hip fracture risk.

INTRODUCTION

Previous studies evaluated the association between PPI use and subsequent fracture risk, but they showed ambiguous results. To further test these conflicting results, the objective of this study was to evaluate the association between the use of PPIs and the risk of hip/femur fracture in a different study population.

METHODS

A case-control study was conducted using data from the Dutch PHARMO record linkage system. The study population included 6,763 cases aged 18 years and older with a first hip/femur fracture during enrollment and 26,341 age-, gender- and region-matched controls.

RESULTS

Current users of PPIs had an increased risk of hip/femur fracture yielding an adjusted odds ratio (AOR) of 1.20 (95% CI 1.04-1.40). Fracture risk attenuated with increasing durations of use, resulting in AORs of 1.26 (95% CI 0.94-1.68) in the first 3 months, 1.31 (95% CI 0.97-1.75) between 3 and 12 months, 1.18 (95% CI 0.92-1.52) between 13 and 36 months and 1.09 (95% CI 0.81-1.47) for use longer than 36 months.

CONCLUSION

Our findings show that there is probably no causal relationship between PPI use and hip fracture risk. The observed association may be the result of unmeasured distortions: although current use of PPIs was associated with a 1.2-fold increased risk of hip/femur fracture, the positive association was attenuated with longer durations of continuous use. Our findings do not support that discontinuation of PPIs decreases risk of hip fracture in elderly patients.

Helicobacter pylori infection increases the transcriptional activity of COX-2 promoter via the p38MAPK signal transduction pathway in MKN45 cells

AIM: To investigate the effect of Helicobacter pylori (H.pylori) infection on the transcriptional activity of cyclooxygenase-2 (COX-2) promoter in gastric cancer MKN45 cells and to explore potential mechanisms involved.

METHODS: The recombinant vector pGL3-Basic-COX-2-promoter and a control vector (pRL-SV40) was transiently co-transfected into MKN45 cells. Twelve hours later, the transfected cells were infected with H.pylori (100 times the number of cells) for different durations. The COX-2 promoter activity was detected using the dual luciferase assay. The activation of p38MAPK pathway was evaluated by Western blot. The p38MAPK signal transduction pathway was then blocked with a specific inhibitor SB203580 to detect the effect of H.pylori infection on COX-2 promoter activity.

RESULTS: After transient transfection, the activity of COX-2 promoter in MKN45 cells was increased with time. At 40 h after transfection, the activity of dual-luciferase was 3.5 folds higher than that at 8 h (P < 0.05). H.pylori infection significantly increased the activity of dual-luciferase compared with control cells (all P < 0.05 or 0.01). The activity of dual-luciferase in cells infected with H.pylori at 40 h after transfection was 5 folds higher than that at 8 h (P < 0.01). The expression of p38MAPK was up-regulated at 20 min after infection and reached the peak at 60 min. Blockage of the p38MAPK signal transduction pathway with SB203580 significantly reduced the COX-2 promoter activity.

CONCLUSION: H.pylori infection increases the transcriptional activity of COX-2 promoter via the p38MAPK signal transduction pathway, which may be one of the important mechanisms by which H.pylori infection causes gastric cancer.

Establishment of a mouse model of chronic Helicobacter pylori infection-induced gastric adenocarcinoma and investigation of the effect of Helicobacter pylori infection on angiogenesis

AIM: To investigate the carcinogenicity of long-term Helicobacter pylori (H.pylori) infection in C57BL/6 mice and to investigate the role of angiogenesis in the pathogenesis of H.pylori infection-induced gastric cancer.

METHODS: Eighty male C57BL/6 mice of SPF grade were equally and randomly divided into normal group and model group. The normal group was fed normally, while the model group was inoculated by oral gavage with H.pylori SS1. Mice were sacrificed at weeks 10, 25, 45 and 72 after the last inoculation. H.pylori infection was analyzed by rapid urease test and Giemsa staining. The pathological changes in the gastric mucosa of mice were assessed by hematoxylin-eosin staining. Microvessel density (MVD) was detected by immunohistochemistry.

RESULTS: No H.pylori infection was detected in the gastric antrum, gastric body and duodenal mucosa in the normal group. The rates of H.pylori colonization were 88.9%, 100%, 100% and 100% at weeks 10, 25, 45 and 72 in the model group. At week 72, the incidence rates of chronic gastritis, atrophic gastritis, intestinal metaplasia, dysplasia and gastric cancer were 100%, 88.9%, 77.8%, 33.3% and 22.2% in the model group, respectively. The MVD in the gastric mucosa in the model group was 18.56 ± 2.62, significantly higher than that in the normal group (P < 0.01).

CONCLUSION: A mouse model of chronic H.pylori infection-induced gastric adenocarcinoma has been established successfully. H.pylori infection can increase the MVD in the gastric mucosa in C57BL/6 mice and therefore play an important role in the development of gastric cancer.