Epidemiology of Sapovirus Infections in a Birth Cohort in Peru.

Background: Sapovirus is one of the primary viral causes of acute gastroenteritis (AGE), especially where rotavirus vaccination has been implemented. The characteristics and impact of natural infection at the community level, however, have not been well documented. Methods: Stool samples were analyzed from 100 children randomly selected from a community-based birth cohort study in Peru. All diarrheal and 1 nondiarrheal stools collected trimonthly from children up to age 2 years (n = 1669) were tested for sapovirus detection. Viral shedding duration was determined by testing additional weekly samples (n = 440) collected before and after a sapovirus-positive sample. Results: The incidence of sapovirus infection in the first and second years of life was 4.3 and 11.1 per 100 child-months, respectively. By age 2 years, 82% of children had at least 1 sapovirus infection, and 64% had at least 1 sapovirus-associated diarrhea episode. The median shedding period was 18.5 days. In 112 of 175 infections, 14 genotypes from 4 genogroups (GI, GII, GIV, and GV) were determined. Among genogroups, GI were more frequently found in symptomatic infections than in asymptomatic infections (odds ratio, 3.1; 95% confidence interval, 1.3-7.4). Fifty-nine children had serial sapovirus infections, but only 3 had repeated infection of the same genotype. Conclusions: Sapovirus was frequently detected in children with AGE at the community level during the first 2 years of life. Serial sapovirus infections by multiple genotypes in a child suggest genotype-specific immunity from each infection, which needs to be taken into account for vaccine development.

Etiological Role and Repeated Infections of Sapovirus among Children Aged Less than 2 Years in a Cohort Study in a Peri-urban Community of Peru.

Human sapovirus has been shown to be one of the most important etiologies in pediatric patients with acute diarrhea. However, very limited data are available about the causative roles and epidemiology of sapovirus in community settings. A nested matched case-control study within a birth cohort study of acute diarrhea in a peri-urban community in Peru from 2007 to 2010 was conducted to investigate the attributable fraction (AF) and genetic diversity of sapovirus. By quantitative reverse transcription-real-time PCR (qPCR) sapovirus was detected in 12.4% (37/299) of diarrheal and 5.7% (17/300) of nondiarrheal stools (P = 0.004). The sapovirus AF (7.1%) was higher in the second year (13.2%) than in the first year (1.4%) of life of children. Ten known genotypes and one novel cluster (n = 5) within four genogroups (GI, GII, GIV, and GV) were identified by phylogenetic analysis of a partial VP1 gene. Further sequence analysis of the full VP1 gene revealed a possible novel genotype, tentatively named GII.8. Notably, symptomatic reinfections with different genotypes within the same (n = 3) or different (n = 5) genogroups were observed in eight children. Sapovirus exhibited a high attributable burden for acute gastroenteritis, especially in the second year of life, of children in a Peruvian community. Further large-scale studies are needed to understand better the global burden, genetic diversity, and repeated infections of sapovirus.

Iron Deficiency and IL1ß Polymorphisms in Helicobacter pylori-infected Children.

BACKGROUND: Helicobacter pylori infection has been associated with an imbalance of iron homeostasis. IL-1ß has been related with iron absorption disturbances through a variety of mechanisms. The aim of this study was to evaluate the presence of polymorphic variants for IL-1ß cluster and gastric IL1ß mRNA expression in H. pylori-infected children and their relationship with hypochlorhydria and iron deficiency (ID). PATIENTS AND METHODS: Prospective study of 123 symptomatic children. At endoscopy, antral biopsies were taken for urease test, pathology and culture and blood for analysis of ferritin, transferrin, serum iron, and total iron-binding capacity. Polymorphisms in the IL-1ß cluster (positions -511, -31, +3954, ILRN) were determined by PCR-RFLP. Gastric mucosal expression of IL-1ß mRNA was determined by RT-PCR. RESULTS: After exclusions, of 105 patients, 33 (31.4%) were H. pylori positive. Nine (8.6%) children were classified as iron deficient (ID). Helicobacter pylori positivity was associated with ID (OR: 5.1; 95% CI: 1.2-21.9) (p = .04). No significant differences were found in allele frequency for IL1ß gene cluster polymorphisms between infected and uninfected children. Helicobacter pylori-infected children with ID had significantly increased gastric IL1ß mRNA in comparison with infected children without ID. In addition, a significant positive correlation was observed between mucosal IL-1ß mRNA and fasting gastric juice pH. Gastric pH values were significantly increased in H. pylori-infected patients with ID compared to uninfected children. CONCLUSIONS: The established association between H. pylori infection and ID in children may be mediated by increased gastric mucosal IL-1ß.

Modelling subject-specific childhood growth using linear mixed-effect models with cubic regression splines.

BACKGROUND: Childhood growth is a cornerstone of pediatric research. Statistical models need to consider individual trajectories to adequately describe growth outcomes. Specifically, well-defined longitudinal models are essential to characterize both population and subject-specific growth. Linear mixed-effect models with cubic regression splines can account for the nonlinearity of growth curves and provide reasonable estimators of population and subject-specific growth, velocity and acceleration. METHODS: We provide a stepwise approach that builds from simple to complex models, and account for the intrinsic complexity of the data. We start with standard cubic splines regression models and build up to a model that includes subject-specific random intercepts and slopes and residual autocorrelation. We then compared cubic regression splines vis-à-vis linear piecewise splines, and with varying number of knots and positions. Statistical code is provided to ensure reproducibility and improve dissemination of methods. Models are applied to longitudinal height measurements in a cohort of 215 Peruvian children followed from birth until their fourth year of life. RESULTS: Unexplained variability, as measured by the variance of the regression model, was reduced from 7.34 when using ordinary least squares to 0.81 (p < 0.001) when using a linear mixed-effect models with random slopes and a first order continuous autoregressive error term. There was substantial heterogeneity in both the intercept (p < 0.001) and slopes (p < 0.001) of the individual growth trajectories. We also identified important serial correlation within the structure of the data (ρ = 0.66; 95 % CI 0.64 to 0.68; p < 0.001), which we modeled with a first order continuous autoregressive error term as evidenced by the variogram of the residuals and by a lack of association among residuals. The final model provides a parametric linear regression equation for both estimation and prediction of population- and individual-level growth in height. We show that cubic regression splines are superior to linear regression splines for the case of a small number of knots in both estimation and prediction with the full linear mixed effect model (AIC 19,352 vs. 19,598, respectively). While the regression parameters are more complex to interpret in the former, we argue that inference for any problem depends more on the estimated curve or differences in curves rather than the coefficients. Moreover, use of cubic regression splines provides biological meaningful growth velocity and acceleration curves despite increased complexity in coefficient interpretation. CONCLUSIONS: Through this stepwise approach, we provide a set of tools to model longitudinal childhood data for non-statisticians using linear mixed-effect models.

Accumulation of somatic mutations in TP53 in gastric epithelium with Helicobacter pylori infection.

BACKGROUND & AIMS: Helicobacter pylori infection is a risk factor for gastric cancer. To explore the genetic basis of gastric cancer that develops in inflamed gastric mucosa, we investigated genetic aberrations that latently accumulate in nontumorous gastric epithelium with H pylori infection. METHODS: We performed whole-exome sequencing of gastric tumors, noncancerous tissues with gastritis, and peripheral lymphocytes from 5 patients. We performed additional deep-sequencing analyses of selected tumor-related genes using 34 gastritis mucosal samples from patients with or without gastric cancer. We also performed deep sequencing analyses of gastric mucosal tissues from mice that express transgenic human TP53 and constitutively express activation-induced cytidine deaminase (AICDA or AID) (human TP53 knock-in/AID-transgenic mice). RESULTS: Whole-exome sequencing revealed that somatic mutations accumulated in various genes in inflamed gastric tissues. Additional deep-sequencing analyses of tissues from regions of gastritis confirmed nonsynonymous low-abundance mutations in TP53 in 15 cases (44.1%) and ARID1A in 5 cases (14.7%). The mutations that accumulated in gastric mucosal tissues with H pylori-induced gastritis, as well as gastric tumors, were predominantly C:G>T:A transitions in GpCpX motifs-a marker of cytidine deamination induced by AID. Constitutive expression of AID in the gastric mucosa of mice led to mutations in the human TP53, at amino acid coding positions identical to those detected in human gastric cancers. CONCLUSIONS: Studies of gastric tumors and tissues from humans and mice indicate that somatic mutations accumulate in various genes in gastric mucosal tissues with H pylori infection. Increased cytidine deaminase activity in these tissues appears to promote the accumulation of these mutations and might promote gastric carcinogenesis in patients with H pylori infection.

Multiple norovirus infections in a birth cohort in a Peruvian Periurban community.

BACKGROUND: Human noroviruses are among the most common enteropathogens globally, and are a leading cause of infant diarrhea in developing countries. However, data measuring the impact of norovirus at the community level are sparse. METHODS: We followed a birth cohort of children to estimate norovirus infection and diarrhea incidence in a Peruvian community. Stool samples from diarrheal episodes and randomly selected nondiarrheal samples were tested by polymerase chain reaction for norovirus genogroup and genotype. Excretion duration and rotavirus coinfection were evaluated in a subset of episodes. RESULTS: Two hundred twenty and 189 children were followed to 1 and 2 years of age, respectively. By 1 year, 80% (95% confidence interval [CI], 75%-85%) experienced at least 1 norovirus infection and by 2 years, 71% (95% CI, 65%-77%) had at least 1 episode of norovirus-associated diarrhea. Genogroup II (GII) infections were 3 times more frequent than genogroup 1 (GI) infections. Eighteen genotypes were found; GII genotype 4 accounted for 41%. Median excretion duration was 34.5 days for GII vs 8.5 days for GI infection (P = .0006). Repeat infections by the same genogroup were common, but repeat infections by the same genotype were rare. Mean length-for-age z score at 12 months was lower among children with prior norovirus infection compared to uninfected children (coefficient: -0.33 [95% CI, -.65 to -.01]; P = .04); the effect persisted at 24 months. CONCLUSIONS: Norovirus infection occurs early in life and children experience serial infections with multiple genotypes, suggesting genotype-specific immunity. An effective vaccine would have a substantial impact on morbidity, but may need to target multiple genotypes.

First detected Helicobacter pylori infection in infancy modifies the association between diarrheal disease and childhood growth in Peru.

BACKGROUND: In endemic settings, Helicobacter pylori infection can occur shortly after birth and may be associated with a reduction in childhood growth. MATERIALS AND METHODS: This study investigated what factors promote earlier age of first H. pylori infection and evaluated the role of H. pylori infection in infancy (6-11 months) versus early childhood (12-23 months) on height. We included 183 children near birth from a peri-urban shanty town outside of Lima, Peru. Field-workers collected data on socioeconomic status (SES), daily diarrheal and breast-feeding history, antibiotic use, anthropometrics, and H. pylori status via carbon 13-labeled urea breath test up to 24 months after birth. We used a proportional hazards model to assess risk factors for earlier age at first detected infection and linear mixed-effects models to evaluate the association of first detected H. pylori infection during infancy on attained height. RESULTS: One hundred and forty (77%) were infected before 12 months of age. Lower SES was associated with earlier age at first detected H. pylori infection (low vs middle-to-high SES Hazard ratio (HR) 1.59, 95% CI 1.16, 2.19; p = .004), and greater exclusive breast-feeding was associated with reduced likelihood (HR 0.63, 95% CI 0.40, 0.98, p = .04). H. pylori infection in infancy was not independently associated with growth deficits (p = .58). However, children who had their first detected H. pylori infection in infancy (6-11 months) versus early childhood (12-23 months) and who had an average number of diarrhea episodes per year (3.4) were significantly shorter at 24 months (-0.37 cm, 95% CI, -0.60, -0.15 cm; p = .001). DISCUSSION: Lower SES was associated with a higher risk of first detected H. pylori infection during infancy, which in turn augmented the adverse association of diarrheal disease on linear growth.

Helicobacter pylori infection in infants and toddlers in South America: concordance between [13C]urea breath test and monoclonal H. pylori stool antigen test.

Accurate noninvasive tests for diagnosing Helicobacter pylori infection in very young children are strongly required. We investigated the agreement between the [(13)C]urea breath test ([(13)C]UBT) and a monoclonal ELISA (HpSA) for detection of H. pylori antigen in stool. From October 2007 to July 2011, we enrolled 414 infants (123 from Brazil and 291 from Peru) of ages 6 to 30 months. Breath and stool samples were obtained at intervals of at least 3 months from Brazilian (n = 415) and Peruvian (n = 908) infants. [(13)C]UBT and stool test results concurred with each other in 1,255 (94.86%) cases (kappa coefficient = 0.90; 95% confidence interval [CI] = 0.87 to 0.92). In the H. pylori-positive group, delta-over-baseline (DOB) and optical density (OD) values were positively correlated (r = 0.62; P < 0.001). The positivity of the tests was higher (P < 0.001; odds ratio [OR] = 6.01; 95% CI = 4.50 to 8.04) in Peru (546/878; 62.2%) than in Brazil (81/377; 21.5%) and increased with increasing age in Brazil (P = 0.02), whereas in Peru it decreased with increasing age (P < 0.001). The disagreement between the test results was associated with birth in Brazil and female gender but not with age and diarrhea. Our results suggest that both [(13)C]UBT and the stool monoclonal test are reliable for diagnosing H. pylori infection in very young children, which will facilitate robust epidemiological studies in infants and toddlers.

Dietary habits and gastric cancer risk in north-west Iran.

OBJECTIVES: North-west Iran is a high-risk area for gastric cancer (GC). Dietary practices may increase risk of GC. For the first time, the diet-GC association in this area was assessed using a validated food frequency questionnaire. METHODS: Cases and controls were recruited in a population-based study. In addition to collecting dietary data using a food frequency questionnaire, Helicobacter pylori antibody level was measured. Multiple logistic regression models were used to estimate odds ratios for associations between dietary factors and GC among 286 cases and 304 controls. RESULTS: A positive association was estimated for total fat intake (OR = 1.33/20 g, 95% CI: 1.12-1.57) and risk of GC. Inverse associations were observed for vitamin C, iron, and zinc intake and risk of GC and its subgroups (cardia, non-cardia). Fruits and vegetables consumption and refrigerator use showed inverse associations (OR = 0.72/100 g, 95% CI: 0.65-0.80 and OR = 0.75/10 years, 95% CI: 0.60-0.95, respectively). Positive association was observed among those who preferred fried food (OR = 2.21, 95% CI: 1.45-3.37) or consumed highly salted/roasted seeds (OR = 1.97, 95% CI: 1.13-3.43). CONCLUSION: GC in north-west Iran is associated with dietary practices: foods, nutrients and food preparation habits.

Enhanced gastric IL-18 mRNA expression in Helicobacter pylori-infected children is associated with macrophage infiltration, IL-8, and IL-1 beta mRNA expression.

OBJECTIVE: To investigate IL-18 mRNA expression in the gastric mucosa in Helicobacter pylori-infected children and its association with macrophage infiltration, IL-8, and IL-1 beta mRNA expression. METHODS: From 39 children, blood samples were taken for IL-1 beta gene polymorphism analysis and antral biopsies were obtained for histology (including macrophage immunostaining), culture and semiquantitative analysis of IL-18, IL-8, IL-1 beta, and CD14 mRNA expression by reverse transcription-PCR (RT-PCR). RT-PCR was used for H. pylori ureA and cagA mRNA detection in gastric tissue. RESULTS: H. pylori-infected patients had significantly higher IL-18, IL-8, and IL-1 beta transcript levels and macrophage numbers in the antral mucosa than H. pylori-negative children. IL-1 beta-511/31 gene polymorphism had no impact on gastric IL-1 beta mRNA levels. IL-18 mRNA expression correlated with mRNA expression of IL-8 and IL-1 beta, and transcript levels of all three cytokines were associated with macrophage infiltration and CD14 mRNA expression in the gastric tissue. Significant correlation was also observed between macrophage numbers and histological parameters of gastritis. CONCLUSION: These results suggest that interleukin(IL)-18 and macrophages may have an important function in gastric inflammatory response to H. pylori infection in children. IL-18, and possibly CD14 receptor signalling pathway, may be involved in macrophage activation and subsequent IL-8 and IL-1 beta release.

Special Issue "H. pylori Virulence Factors in the Induction of Gastric Cancer".

Twenty-five years ago, Helicobacter pylori was identified as the causative agent of gastric disorders,ranging from acute inflammation [...].

Epidemiology of Helicobacter pylori and CagA-Positive Infections and Global Variations in Gastric Cancer.

Gastric cancer is a major health burden and is the fifth most common malignancy and the third most common cause of death from cancer worldwide. Development of gastric cancer involves several aspects, including host genetics, environmental factors, and Helicobacter pylori infection. There is increasing evidence from epidemiological studies of the association of H. pylori infection and specific virulence factors with gastric cancer. Studies in animal models indicate H. pylori is a primary factor in the development of gastric cancer. One major virulence factor in H. pylori is the cytotoxin-associated gene A (cagA), which encodes the CagA protein in the cag pathogenicity island (cag PAI). Meta-analysis of studies investigating CagA seropositivity irrespective of H. pylori status identified that CagA seropositivity increases the risk of gastric cancer (OR = 2.87, 95% CI: 1.95⁻4.22) relative to the risk of H. pylori infection alone (OR = 2.31, 95% CI: 1.58⁻3.39). Eradicating H. pylori is a strategy for reducing gastric cancer incidence. A meta-analysis of six randomised controlled trials (RCTs) suggests that searching for and eradicating H. pylori infection reduces the subsequent incidence of gastric cancer with a pooled relative risk of 0.66 (95% CI: 0.46⁻0.95). The introduction in regions of high gastric cancer incidence of population-based H. pylori screening and treatment programmes, with a scientifically valid assessment of programme processes, feasibility, effectiveness and possible adverse consequences, would impact the incidence of H. pylori-induced gastric cancer. Given the recent molecular understanding of the oncogenic role of CagA, targeting H. pylori screening and treatment programmes in populations with a high prevalence of H. pylori CagA-positive strains, particularly the more oncogenic East Asian H. pylori CagA strains, may be worth further investigation to optimise the benefits of such strategies.

In-Cell Western analysis of Helicobacter pylori-induced phosphorylation of extracellular-signal related kinase via the transactivation of the epidermal growth factor receptor.

Helicobacter pylori activates extracellular-signal related (ERK) kinases in gastric epithelial cells, via transactivation of the EGF receptor (EGFR). H. pylori activation of EGFR may be relevant to epithelial hyperproliferation and gastric carcinogenesis. The aim of this study was to develop an 'In-Cell Western' (ICW) assay for quantitative examination of H. pylori-induced epithelial signalling, to enable the role of the EGFR in H. pylori-induced phosphorylation of ERK in epithelial cells to be ascertained. H. pylori strains were co-incubated with A431 and AGS cells. pERK and total ERK were quantified in situ using ICW analysis. H. pylori strains both with, and without a cag PAI, and Helicobacter felis, significantly increased pERK levels in A431 cells. The EGFR inhibitor EKB-569 dose-dependently reduced H. pylori-induced ERK phosphorylation in A431 and AGS cells. A significantly lower reduction was observed with cag+ strains in A431 but not AGS cells. The cag PAI was not necessary for EGFR signal transactivation. These data suggest that H. pylori induces pERK in epithelial cells partly via the EGFR pathway. Additional signalling mechanisms are likely to be involved in H. pylori-induced ERK phosphorylation. ICW analysis is a rapid quantitative method for evaluating the effects of inhibitors on H. pylori-induced cell signalling pathways of relevance to gastric carcinogenesis.

Proteolysis in Helicobacter pylori-Induced Gastric Cancer.

Persistent infections with the human pathogen and class-I carcinogen Helicobacter pylori (H. pylori) are closely associated with the development of acute and chronic gastritis, ulceration, gastric adenocarcinoma and lymphoma of the mucosa-associated lymphoid tissue (MALT) system. Disruption and depolarization of the epithelium is a hallmark of H. pylori-associated disorders and requires extensive modulation of epithelial cell surface structures. Hence, the complex network of controlled proteolysis which facilitates tissue homeostasis in healthy individuals is deregulated and crucially contributes to the induction and progression of gastric cancer through processing of extracellular matrix (ECM) proteins, cell surface receptors, membrane-bound cytokines, and lateral adhesion molecules. Here, we summarize the recent reports on mechanisms how H. pylori utilizes a variety of extracellular proteases, involving the proteases Hp0169 and high temperature requirement A (HtrA) of bacterial origin, and host matrix-metalloproteinases (MMPs), a disintegrin and metalloproteinases (ADAMs) and tissue inhibitors of metalloproteinases (TIMPs). H. pylori-regulated proteases represent predictive biomarkers and attractive targets for therapeutic interventions in gastric cancer.

Helicobacter pylori and Schistosoma japonicum co-infection in a Chinese population: helminth infection alters humoral responses to H. pylori and serum pepsinogen I/II ratio.

The effects of helminth infection on humoral IgG responses and clinical outcome of gastric Helicobacter pylori infection are unknown. IgG and IgG subclass responses to H. pylori and serum pepsinogen I/II ratio, a marker of gastric atrophy, were investigated in a Schistosoma japonicum prevalent Chinese population. H. pylori, CagA and IgG subclass responses were assayed by ELISA. Serum pepsinogen I and pepsinogen II were assayed by ELISA and the pepsinogen I/II ratio determined. In 150 subjects, infection with S. japonicum and H. pylori was 55.3% and 51.3%, respectively. H. pylori IgG titres and CagA seropositivity were significantly lower (P<0.05) in co-infected subjects, and differences in H. pylori IgG isotype responses were evident. In H. pylori positives, a significantly higher (P<0.05) pepsinogen I/II ratio was observed in co-infected subjects. The difference between S. japonicum positive and negative subjects was only evident in H. pylori CagA seronegative subjects. In conclusion, S. japonicum co-infection with H. pylori is associated with alterations in IgG responses to H. pylori and less gastric atrophy.

Helicobacter pylori regulates the expression of inhibitors of DNA binding (Id) proteins by gastric epithelial cells.

Id transcription factors control proliferation, differentiation and apoptosis by inhibiting the DNA binding of basic helix-loop-helix transcription factors. Increased expression of Id proteins promotes proliferation, inhibits differentiation, and is associated with intestinal tumorigenesis. We aimed to determine how Helicobacter pylori may alter the expression of Id proteins by gastric epithelial cells: it was hypothesised that H. pylori, a known carcinogen, would result in increased expression of one or more Id family members. In vitro and in vivo models of infection were employed, including treatment of AGS gastric epithelial cells with wild-type H. pylori strains, 60190 and SS1, and Mongolian gerbils infected with H. pylori SS1. A small cohort of human gastric mucosal biopsies was also examined. Treatment of AGS cells with H. pylori resulted in down-regulation of Id1 and Id3. Unexpectedly, expression of the main target of Id proteins, the basic helix-loop-helix transcription factor E2A, was also suppressed, with an associated decrease in E-box binding activity. In contrast, H. pylori induced the expression of the CDK inhibitor p21(WAF-1/cip1), and the homeobox transcription factor, Cdx2, an early marker of intestinal metaplasia of the stomach epithelium. Gastric epithelium from H. pylori-infected gerbils demonstrated similar changes, with decreased Id2, Id3 and E2A, and elevated p21(WAF-1/cip1) expression. In human gastric epithelium also, H. pylori infection was associated with reduced Id and E2A expression. In conclusion, H. pylori alters the expression of Id proteins, in vitro and in vivo; it is hypothesised that these changes contribute to H. pylori-associated pathologies.

Helicobacter pylori-induced epithelial cell signalling in gastric carcinogenesis.

Helicobacter pylori represents a highly successful human microbial pathogen that infects the stomach of more than half of the world's population. H. pylori induces gastric inflammation, and the diseases that can follow such infection include chronic gastritis, peptic ulcers and, more rarely, gastric cancer. The reasons why a minority of patients with H. pylori develops gastric cancer could be related to differences in host susceptibility, environmental factors and the genetic diversity of the organism. This review examines the features of H. pylori-induced epithelial cell signalling in gastric diseases. Clinical studies and animal models, and also evidence for H. pylori strain-related differences in gastric epithelial cell proliferation in vivo are discussed. In addition, the mechanisms by which H. pylori triggers hyperproliferative processes and takes direct command of epithelial cell signalling, including activation of tyrosine kinase receptors, cell-cell interactions and cell motility are reviewed.

Epithelial cell ADAM17 activation by Helicobacter pylori: role of ADAM17 C-terminus and Threonine-735 phosphorylation.

Helicobacter pylori transactivates the epidermal growth factor receptor (EGFR) on gastric epithelial cells via a signalling cascade involving a disintegrin and metalloprotease 17 (ADAM17) cleavage of membrane bound heparin binding-epidermal growth factor (HB-EGF). The effects of H. pylori on ADAM17 C-terminus in epithelial cells have been examined. Total cellular ADAM17 and surface expression of ADAM17 were significantly increased by H. pylori in AGS gastric epithelial cells. These changes were associated with ADAM17 C-terminal phosphorylation at T375 and S791. AGS cells lacking the ADAM17 C-terminal domain induced significantly attenuated cleavage of HB-EGF and were also unable to upregulate HB-EGF and EGFR transcripts to the same extent as cells expressing full length ADAM17. In mitotic unstimulated AGS and ADAM17 over-expressing AGS cells, ADAM17 was highly T735 phosphorylated indicating ADAM17 T735 phosphorylation is modified during the cell cycle. In conclusion, H. pylori induced ADAM17 C-terminal T735 and/or S791 phosphorylation in gastric epithelial cells are likely to be an important trigger inducing ADAM17 activation and shedding of HB-EGF leading to EGFR transactivation. ADAM17 over-expression in gastric cancer represents a potential target for therapeutic intervention.

Infection of Mongolian gerbils with Chinese Helicobacter pylori strains.

To date only a few Helicobacter pylori strains have been demonstrated to colonise Mongolian gerbils successfully. The aim of this study was to establish stable colonisation of Chinese strains of H. pylori in gerbils. Fresh clinical isolates from Chinese patients were inoculated into gerbils. At 4-6 weeks post inoculation, infection status was evaluated by culture, biopsy urease test and pathology. Sequencing of glmM and random amplified polymorphic DNA (RAPD) fingerprinting of DNA from cultured H. pylori were used to evaluate the genetic identity of pre-inoculated and post-inoculated strains. The ability of pre- and post-inoculated strains to stimulate interleukin-8 transcription in L5F11 gastric epithelial cells was analysed. Three of five clinical isolates colonised gerbils. The three pre- and post-inoculation strains had identical glmM sequences and RAPD profiles, and stimulated luciferase secretion from L5F11 epithelial cells. The strain that caused severe pathological changes was selected for repeat infection to prove reproducible and stable colonisation. The cagA+ strain 42GX gave stable colonisation in the gerbil and induced severe gastritis.