Prevalence of Helicobacter pylori Infection in Children from Urban and Rural West Virginia

Our objective was to evaluate the prevalencerate of Helicobacter pylori (HP) in children from urbanand rural areas of West Virginia. In all, 1164 bloodsamples were collected from children who attended a local health fair, pediatric clinics, andemergency departments of four different hospitalslocated in urban and rural counties. Socioeconomicstatus was determined in 303 children. Serum HP antibody (IgG) was measured by enzyme immunoassay (EIA).A total of 468 (40%) samples were HP positive. HPacquisition correlated with increasing age, familycrowding, and community location (urban/rural) but not with gender, water source used (city/well), orsocioeconomic status. The prevalence rate of HP in thechildren of West Virginia is higher than any datapreviously reported from the United States. The results correlated with only few socioeconomiccriteria, suggesting that other factors may contributeto the increased prevalence of HP infection in thechildren of West Virginia.     

Detection of Helicobacter pylori Organisms by Hp-Fast in Children

Hp-fast is a new rapid urease test (RUT) thathas not been evaluated in children. The aim of the studywas to prospectively compare the Hp-fast test to theCLOtest in children. Children with gastrointestinal symptoms who undergo diagnostic upper endoscopywere prospectively enrolled to the study. Antral gastricbiopsies were evaluated for histology and for CLO-testand Hp-fast. Results were then compared to histology. Of the 94 children who participated,gastritis was found in 38 (40%), of whom 16 (42%) hadassociated H. pylori organisms. In two children, H.pylori organisms were identified without gastritis. The concordance between both RUT tests was 98%.A significant correlation was found between RUT resultsand histological factors or serology. The accuracy rateof both RUT increased significantly when different gold standards were utilized todetect Hp infection in children. The best correlationwas found when histology and serology were considered asthe gold standard for the diagnosis of H. pylori infection in children (sensitivity: 100%compared to 43-80% with other standards, respectively).In conclusion, the Hp-fast test result is comparable toCLOtest, but neither alone is sufficient to establish the diagnosis of Hp infection inchildren.     

Role of epidermal growth factor receptor transactivation in PPARγ-dependent suppression of Helicobacter pylori interference with gastric mucin synthesis

Peroxisome-proliferator-activated receptor γ (PPARγ) is recognized for its role in regulation of genes associated with inflammation, and its activation of phosphatidylinositol 3-kinase (PI3K) has emerged recently as an important regulator of mucosal responses to bacterial infection. In this study, we report that PPARγ activation leading to the impedance of Helicobacter pylori lipopolysaccharide (LPS) inhibitory effect on salivary mucin synthesis requires epidermal growth factor receptor (EGFR) participation. Using gastric mucosal cells in culture, we show that activation of PPARγ with a specific agonist, ciglitazone, prevents the LPS-induced reduction in mucin synthesis, and the effect is reflected in a marked decrease in apoptosis, caspase-3 activity and NO generation. The impedance by ciglitazone of the LPS-induced reduction in mucin synthesis was blunted (up to 65.8%) in a concentration-dependent fashion by a specific inhibitor of EGFR kinase, PD153035, as well as the PPARγ antagonist BADGE, and wortmannin, an inhibitor of PI3K. Moreover, the inhibitory effect of ciglitazone on the LPS-induced reduction in mucin synthesis and upregulation in apoptosis, caspase-3 activity and NO generation was countered by PP2, a selective inhibitor of tyrosine kinase Src responsible for ligand-independent EGFR transactivation. These findings indicate that PPARγ activation leading to the suppression of H. pylori LPS inhibition of gastric mucin synthesis involves Src kinase-dependent EGFR transactivation.     

Effect of Potent Urease Inhibitor, Fluorofamide, on Helicobacter sp. in Vivo and in Vitro

The therapeutic potential of urease inhibitionof Helicobacter pylori has been studied by examining theeffect of the potent urease inhibitor, fluorofamide(N-(diaminophosphinyl)-4-fluorobenzenamide), on urease activity and bacterial survival invivo and in vitro. In culture, acid protection in H.pylori was shown to be due to changes in the pH of themedium brought about by the release of ammonia. Both the acid protection and the ammoniarelease were completely blocked by fluorofamide at lowdoses (ED₅₀ = ~100 nM). However, fluorofamidewas unstable under acidic conditions (T_1/25.7 min at pH 2). Despite this, fluorofamide was the best availablecompound to test in vivo. In ferrets naturally infectedwith H. mustelae, a single dose (50 mg/kg, per os ) offluorofamide completely inhibited bacterial urease. In repeat dosing studies, fluorofamide(50 mg/kg per os, three times a day) was compared withthe Helicobacter triple therapy regime (amoxycillin,metronidazole, and bismuth subcitrate). Fluorofamide failed to eradicate the H. mustelae infection,compared to 80% eradication with triple therapy.However, histological samples showed a profoundreduction in bacterial numbers following fluorofamidetreatment. A combination of fluorofamide and amoxycillinwas dosed to ferrets (seven days of treatment with 50mg/kg fluorofamide plus 10 mg/kg amoxycillin per ostwice a day); however, this failed to eradicate the infection, despite there being a reduction inbacterial numbers in 3/5 ferrets after 21 days afterdosing stopped. It was concluded that urease inhibitors(either alone or in combination with antibiotics) are unlikely to have therapeutic potential forHelicobacter pylori infections. This is probablybecause, in vivo, some bacteria (perhaps dormant forms)are not entirely dependent upon urease for survival. However, given the acid instability offluorofamide, the possibility that more stable ureaseinhibitors might have therapeutic potential, cannot beexcluded.     

Interleukin-8 Stimulates Leukocyte Migration Across a Monolayer of Cultured Rabbit Gastric Epithelial Cells (Effect Associated with the Impairment of Gastric Epithelial Barrier Function)

Acute Helicobacter pylori infection producespredominantly neutrophilic infiltration of the gastricmucosa. However, the precise mechanisms and mediators ofneutrophil migration are not known. Interleukin-8(IL-8), a potent chemotactic factor for neutrophils, ispresent at high concentration in the gastric mucosa ofsubjects with chronic gastritis caused by H. pyloriinfection. The aims of this study were to determinewhether IL-8 stimulates polymorphonuclear leukocyte(PMN) migration across a cultured monolayer of rabbitgastric epithelial cells and whether PMN migrationaffects epithelial cell barrier function. Confluent gastric epithelialmonolayers grown on the inserts were overlaid with PMNsand various amounts of IL-8 were administered into thewell under the insert. Gastric epithelial barrierfunction was assessed by sodium back diffusion. IL-8stimulated PMN migration across the monolayer in a dose-and time-dependent manner. PMN transmigrationsignificantly increased sodium back diffusion. Inconclusion, IL-8 induces PMN migration across a monolayerof cultured gastric epithelial cells. This IL-8 actionis associated with impairment of gastric epithelialbarrier function. Since H. pylori infection causes a local mucosal increase of IL-8, our presentfindings may explain the mechanism of H. pylori -inducedPMN infiltration of the gastric glands and mucosalinjury.     

Mechanisms of peptic ulcer recurrence: role of inflammation

The mechanism of peptic ulcer recurrence is still unclear. Since ulcerogenic factors such as Helicobacter pylori, non-steroidal anti-inflammatory drugs and stress can increase expression of inflammatory cytokines in gastric mucosa, gastric mucosal inflammation may play key roles in ulcer recurrence. In acetic acid-induced gastric ulcers, persistent infiltration of neutrophils into scarred mucosa, which is caused by prostaglandin deficiency, affects future ulcer recurrence. In a rat model of ulcer recurrence which we developed, inflammatory cytokines such as interleukin (IL)-1 are key mediators of ulcer recurrence. In this model, IL-1 increases expression of adhesion molecules on both leukocytes and endothelial cells, and cytokines, leading to neutrophil infiltration into scarred mucosa. Gastric acid also plays important roles in recurrence of gastric ulcer in this model. Acid regulates inflammatory processes, including expression of adhesion molecules and inflammatory cytokines during ulcer recurrence. This review focuses on recent advances in understanding of the mechanisms underlying development of gastric ulcer recurrence.     

Anti-CagA Reactivity in Helicobacter pylori-Negative Subjects (A Comparison of Three Different Methods)

Emerging evidence suggests that infection byCagA-positive Helicobacter pylori strains is related tothe development of more serious gastroduodenal diseases,thus conferring to the determination of anti-CagA antibodies a relevant clinical significance inserological screenings. The detection of anti-CagApositivity in sera negative for anti-H. pyloriantibodies raises the question of whether thisapparently nonsense result is merely due to a falsepositive reaction. To address this issue, we comparedthree different methods for the detection of anti-CagAantibodies. In all, 272 selected sera from patients with precisely defined H. pylori status(positive or negative concordance of five tests, ie,histology by Giemsa in both antrum and corpus, rapidurease test, culture, [¹³C]urea breath test,IgG ELISA) were tested for anti-CagA reactivity by threedifferent techniques (western immunoblotting, ELISA, andrecombinant immunoblotting assay). In order to assessthe sensibility and specificity of each tests, we considered as true anti-CagApositive sera those with two out of three positiveresults. Sera from 70% of H. pylori-positive patientsand 10% from H. pylori-negative patients turned out to be true positives foranti-CagA antibodies. The three methods showed similarexcellent results, in terms of both sensitivity andspecificity, always over 93%. It is confirmed that aproportion of patients with a negative conventionalserology against H. pylori possess anti-CagA antibodiesin their sera. In this paper we demonstrate that it canhappen even in patients without any biological signs of actual H. pylori infection. The possibilitythat this can be due to a false positive laboratoryresult is very likely ruled out by the accuracy of thethree methods used. The clinical management of these patients needs further study on largerseries.     

Examination of Tissue Distribution of Helicobacter pylori Within Columnar-Lined Esophagus

H. pylori may colonize columnar-lined esophagus,although an etiologic role in esophageal adenocarcinomais unproven. H. pylori can adhere to intestinalmetaplasia in the stomach. This study was designed to examine if H. pylori adheres to specializedintestinal metaplasia in columnar-lined esophagus.Esophageal biopsies from patients with columnar-linedesophagus were reviewed. Patients with only gastric metaplasia were excluded. Sections withspecialized intestinal metaplasia in at least one thirdof at least one gland were recut, stained using theGiemsa stain, and reexamined by two independentpathologists using strict criteria for adherence by H.pylori . The 209 esophageal biopsies with adequatespecialized intestinal metaplasia from 58 patients wereexamined: H. pylori was only seen on gastric metaplasia in three patients — and never onspecialized intestinal metaplasia. Within the esophagus,H. pylori adheres only to gastric metaplasia, which isnot considered premalignant for esophagealadenocarcinoma.