Helicobacter pylori in childhood: new insights into the immunopathogenesis of gastric disease and implications for managing infection in children

Traditional and Modern Diagnostic Approaches in Diagnosing Pediatric Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is the most common bacterial infection worldwide, is usually acquired during childhood and is related to gastric carcinogenesis during adulthood. Therefore, its early proper diagnosis and subsequent successful eradication represent the cornerstones of gastric cancer prevention. The aim of this narrative review was to assess traditional and modern diagnostic methods in terms of H. pylori diagnosis. Several invasive and non-invasive methods were described, each with its pros and cons. The invasive diagnostic methods comprise endoscopy with biopsy, rapid urease tests, histopathological exams, cultures and biopsy-based molecular tests. Among these, probably the most available, accurate and cost-effective test remains histology, albeit molecular tests definitely remain the most accurate despite their high costs. The non-invasive tests consist of urea breath tests, serology, stool antigens and non-invasive molecular tests. Urea breath tests and stool antigens are the most useful in clinical practice both for the diagnosis of H. pylori infection and for monitoring the eradication of this infection after therapy. The challenges related to accurate diagnosis lead to a choice that must be based on H. pylori virulence, environmental factors and host peculiarities.

Helicobacter pylori in Native Americans in Northern Arizona

Background: In Arizona Helicobacter pylori prevalence of infection among Navajo adults is about 62% and gastric cancer incidence rate is 3–4 times higher than that of the non-Hispanic White population. Aim: The aim of this study was to estimate the prevalence of specific H. pylori virulence factors (cagA and vacA) among Navajo patients undergoing and their association with gastric disease. Methods: Virulence genes, cagA and vacA, in H. pylori were investigated in gastric biopsies from 96 Navajo patients over age 18 who were undergoing esophagogastroduodenoscopy. Biopsies from the antrum and fundus were used for molecular characterization to determine cagA type and number of EPIYA motifs and presence of alleles in the signal (s) and medium (m) regions of the vacA gene. Results: H. pylori infection was found in 22.9% of the biopsy samples. The cagA gene amplified in 57.6% of samples and showed a predominant “Western cagA” type, with the EPIYA-ABC motif (45.4%), most prevalent. The vacA allele s1bm1 was the most prevalent (54.5%). Conclusions: H. pylori genotypes were predominantly cagA Western-type and ABC EPIYA motifs. The vacA s1bm1 genotype was the most prevalent and seemed to be associated with gastritis. American Indian/Alaska Native populations are at higher risk for gastric cancer. It is important to identify genotypes of H. pylori and virulence factors involved in the high prevalence of H. pylori and associated disease among the Navajo population.

Declining prevalence of Helicobacter pylori infection in Jordanian children, report from developing country

INTRODUCTION

Helicobacter pylori (H. pylori) is a Gram-negative bacteria that is harbored in the stomach and linked to chronic gastritis, peptic ulcer disease, and gastric malignancy. Most Helicobacter infections are acquired during early infancy. This study aimed to establish the prevalence of H. pylori infection in Jordanian children using the 13C-urea breath test.

MATERIALS AND METHODS

We prospectively enrolled children between the ages of 4 and 17 years from April 2019 to July 2019. Enrolled children were patients with nongastrointestinal complaints at the pediatric clinics of two hospitals and at community centers caring for healthy children in Irbid, Jordan. Questionnaires obtaining data on sociodemographics, clinical symptomatology, and hygienic risk factors were completed. Recruited children underwent a urea breath test (UBT).

RESULTS

Of 340 children who were recruited, 328 (96.5%) were included in the final analysis. The mean age (±standard deviation) was 9.56 (±3.98) years (range, 4.0-17 years), and 168 (51.2%) were males. Only 48 children (14.6%) tested positive. There were no gender differences. Living in an urban area and a family history of previous H. pylori infection were risk factors for the acquisition of infection (P = 0.007 and 0.001, respectively). Although gastrointestinal symptoms were more common in H. pylori-infected children, only hiccups and constipation were statistically significant (P = 0.035 and 0.038, respectively).

CONCLUSION

H. pylori infects at least 15% of Jordanian children, suggesting a significant drop in infection rates in this group. Larger-scale studies combined with clinical evaluations will be important for further understanding the reasons for the observed decrease in H. pylori infections in Jordanian children.

Gastric Damage and Cancer-Associated Biomarkers in Helicobacter pylori-Infected Children

Helicobacter pylori (H. pylori) is well-known to be involved in gastric carcinogenesis, associated with deregulation of cell proliferation and epigenetic changes in cancer-related genes. H. pylori infection is largely acquired during childhood, persisting long-term in about half of infected individuals, a subset of whom will go on to develop peptic ulcer disease and eventually gastric cancer, however, the sequence of events leading to disease is not completely understood. Knowledge on carcinogenesis and gastric damage-related biomarkers is abundant in adult populations, but scarce in children. We performed an extensive literature review focusing on gastric cancer related biomarkers identified in adult populations, which have been detected in children infected with H. pylori. Biomarkers were related to expression levels (RNA or protein) and/or methylation levels (DNA) in gastric tissue or blood of infected children as compared to non-infected controls. In this review, we identified 37 biomarkers of which 24 are over expressed, three are under expressed, and ten genes are significantly hypermethylated in H. pylori-infected children compared to healthy controls in at least 1 study. Only four of these biomarkers (pepsinogen I, pepsinogen II, gastrin, and SLC5A8) have been studied in asymptomatically infected children. Importantly, 13 of these biomarkers (β-catenin, C-MYC, GATA-4, DAPK1, CXCL13, DC-SIGN, TIMP3, EGFR, GRIN2B, PIM2, SLC5A8, CDH1, and VCAM-1.) are consistently deregulated in infected children and in adults with gastric cancer. Future studies should be designed to determine the clinical significance of these changes in infection-associated biomarkers in children and their persistence over time. The effect of eradication therapy over these biomarkers in children if proven significant, could lead to modifications in treatment guidelines for younger populations, and eventually promote the development of preventive strategies, such as vaccination, in the near future.

Helicobacter pylori infection in children: an overview of diagnostic methods

Children differ from adults regarding Helicobacter pylori (H. pylori) infection in many terms. H. pylori infection represents a key factor in the pathogenesis of duodenal ulcer and chronic gastritis in children. H. pylori infection causes some extraintestinal diseases as well as gastrointestinal diseases. Although, among these illnesses in children, symptoms like recurrent abdominal pain are not specific. Moreover, the role of the pathogen in the growth faltering, iron deficiency anemia, and asthma still remains controversial. A reliable method to detect H. pylori infection is a crucial issue, sand is still a matter of active debate. The tests applied for H. pylori diagnosis are grouped as either invasive or non-invasive methods. Invasive methods consist of endoscopic evaluation, the rapid urease test (RUT), histology, and bacterial culture. Non-invasive tests include the urea breath test (UBT), stool antigen test (SAT), serology, and molecular diagnostic approaches. Use of endoscopy is a pre-requisite for all invasive methods and poses difficulties in children as it is a difficult procedure and requires patient's cooperation. For this reason, the non-invasive tests have been commonly used in children, although their accuracy is not very reliable in some cases. Invasive tests may be opted to confirm the diagnosis as and when needed. This review presents the diagnostic tests used to detect H. pylori infection in children.

Helicobacter pylori: a perspective in low- and middle-income countries

BACKGROUND

In adults, Helicobacter pylori is aetiologically associated with peptic ulcer disease and gastric cancer. However, the relationship between this bacteria and gastro-intestinal symptoms in children is less clear.

AIMS

To review the recent literature on H. pylori in children and to outline the approach to diagnosis and management.

METHODS

The English language literature was searched for articles on H. pylori in children. Special attention was paid to prevalence, diagnosis and management pertinent to low- and middle-income countries (LMIC).

RESULTS

Although the prevalence of H. pylori is 60-80% in LMIC, only 5% of infected children develop peptic ulcer disease. The virulence of the organism determines the outcome. There is a suggestion that H. pylori causes iron deficiency anaemia, growth retardation and idiopathic thrombocytopenic purpura, but the evidence is not sufficiently strong to justify screening. There is no evidence to suggest a link between H. pylori infection and recurrent abdominal pain. Endoscopy (with invasive tests) is the preferred method of investigation as the primary goal is to determine the underlying cause of the symptoms. Children with H. pylori-related diseases should be treated with a standard triple-drug regimen consisting of a protein pump inhibitor and two antibiotics for 10-14 days. All treated patients should be monitored for eradication with non-invasive tests such as the urea (13-C) breath test or stool antigen tests.

CONCLUSIONS

Although H. pylori infection is common in LMIC, most children are asymptomatic. There is no association between H. pylori and recurrent abdominal pain. Invasive tests are preferred for diagnosis and a triple-drug regimen is the treatment of choice.

Expression levels of A disintegrin and metalloproteases (ADAMs), and Th17-related cytokines and their association with Helicobacter pylori infection in patients with gastroduodenal diseases

Expression levels of A disintegrin and metalloproteases (ADAMs) (10 and 17) and Th17-related cytokines [interleukin (IL) 17A, IL-17F, IL-33, IL-23, IL-23R] were investigated by quantitative real time polymerase chain reaction in gastric biopsies of patients with different gastroduodenal pathologies in the presence and absence of Helicobacter pylori infection. Patients with gastric cancer (GC) (n = 70, intestinal-type 38 and diffuse type 32), peptic ulcer disease [n = 50, duodenal ulcer (DU) 16 and gastric ulcer (GU) 34] and functional dyspepsia (n = 120) were included in the study. Further, the expression levels of ADAMs and Th17 cytokines were correlated with H. pylori cytotoxin-associated genes pathogenicity island (cagPAI) status. Expression levels of ADAMs (10 and 17) and Th17-related cytokines (IL-17A, IL-23, IL-23R) were significantly higher in H. pylori-positive than in H. pylori-negative gastric biopsies. Significant increase in ADAM17 and Th17 cytokines (IL-17A and IL-23) expressions was observed in patients with GU and intestinal-type GC in the presence of H. pylori infection and in strains harbouring intact cagPAI. Expression levels of IL-17A, IL-23 and ADAM17 were strongly correlated with GU and intestinal-type GC and weakly with DU and diffuse-type GC in the presence of H. pylori infection. Higher expression levels of ADAM17 and Th17 cytokines (IL-17A and IL-23), and their strong correlation with GU and intestinal-type GC patients in the presence of H. pylori and its intact cagPAI status, suggest a possible role of strain specificity in the pathogenesis of these diseases.

Detection of Helicobacter pylori in dental plaque using a DNA biosensor for noninvasive diagnosis

H. pylori in dental plaque was detected with a DNA biosensor with results correlating well with the ¹³C urea breath test.

Regulation of Rac1 and Reactive Oxygen Species Production in Response to Infection of Gastrointestinal Epithelia

Generation of reactive oxygen species (ROS) during infection is an immediate host defense leading to microbial killing. APE1 is a multifunctional protein induced by ROS and after induction, protects against ROS-mediated DNA damage. Rac1 and NAPDH oxidase (Nox1) are important contributors of ROS generation following infection and associated with gastrointestinal epithelial injury. The purpose of this study was to determine if APE1 regulates the function of Rac1 and Nox1 during oxidative stress. Gastric or colonic epithelial cells (wild-type or with suppressed APE1) were infected with Helicobacter pylori or Salmonella enterica and assessed for Rac1 and NADPH oxidase-dependent superoxide production. Rac1 and APE1 interactions were measured by co-immunoprecipitation, confocal microscopy and proximity ligation assay (PLA) in cell lines or in biopsy specimens. Significantly greater levels of ROS were produced by APE1-deficient human gastric and colonic cell lines and primary gastric epithelial cells compared to control cells after infection with either gastric or enteric pathogens. H. pylori activated Rac1 and Nox1 in all cell types, but activation was higher in APE1 suppressed cells. APE1 overexpression decreased H. pylori-induced ROS generation, Rac1 activation, and Nox1 expression. We determined that the effects of APE1 were mediated through its N-terminal lysine residues interacting with Rac1, leading to inhibition of Nox1 expression and ROS generation. APE1 is a negative regulator of oxidative stress in the gastrointestinal epithelium during bacterial infection by modulating Rac1 and Nox1. Our results implicate APE1 in novel molecular interactions that regulate early stress responses elicited by microbial infections.

Helicobacter pylori infection of the gastric mucosa is largely lifelong leading to continued stimulation of immune cells. This results in the generation of reactive oxygen species (ROS) which are produced to kill bacteria, but at the same time ROS regulate cellular events in the host. However, prolonged generation of ROS has been implicated in damage of DNA, which ultimately could lead to the development of cancer. We studied a molecule known as APE-1 in gastric and intestinal cells, which is activated upon encounter of ROS. Our results show that APE1 limits the production of ROS in cells that form the lining of the gastrointestinal tract. APE1 regulates ROS production by inhibiting activation of the molecule Rac1. Inhibition of ROS production by APE1 occurred after infection of gastric cells with Helicobacter pylori and after Salmonella infection of intestinal cells. These data demonstrate that APE1 inhibits production of ROS in cells that line the inside of the digestive tract.

The role of C1q in recognition of apoptotic epithelial cells and inflammatory cytokine production by phagocytes during Helicobacter pylori infection

Background

Gastric epithelial cells (GECs) undergo apoptosis during H. pylori infection and phagocytes within the mucosa engulf these cells. The recognition and clearance of apoptotic cells is a multifactorial process, enhanced by the presence of various bridging molecules and opsonins which are abundant in serum. However, it is not clear how recognition or clearance may differ in the context of H. pylori infection induced apoptosis. In addition, efferocytosis of sterile apoptotic cells is known to confer anti-inflammatory properties in the engulfing phagocyte, however it is unknown if this is maintained when phagocytes encounter H. pylori-infected cells. Thus, the ability of macrophages to bind and engulf gastric epithelial cells rendered apoptotic by H. pylori infection and the association of these interactions to the modulation of phagocyte inflammatory responses was investigated in the absence and presence of serum with a particular focus on the role of serum protein C1q.

Methods

Control (uninfected) or H. pylori-infected AGS cells were co-cultured with THP-1 macrophages in the presence or absence of serum or serum free conditions + C1q protein (40–80 μg/mL). Binding of AGS cells to THP-1 macrophages was assessed by microscopy and cytokine (IL-6 and TNF-α) release from LPS stimulated THP-1 macrophages was quantified by ELISA.

Results

We show that macrophages bound preferentially to cells undergoing apoptosis subsequent to infection with H. pylori. Binding of apoptotic AGS to THP-1 macrophages was significantly inhibited when studied in the absence of serum and reconstitution of serum-free medium with purified human C1q restored binding of macrophages to apoptotic cells. Co-culture of sterile apoptotic and H. pylori-infected AGS cells both attenuated LPS-stimulated cytokine production by THP-1 macrophages. Further, direct treatment of THP-1 macrophages with C1q attenuated LPS stimulated TNF-α production.

Conclusions

These studies suggest that C1q opsonizes GECs rendered apoptotic by H. pylori. No differences existed in the ability of infected or sterile apoptotic cells to attenuate macrophage cytokine production, however, there may be a direct role for C1q in modulating macrophage inflammatory cytokine production to infectious stimuli.

Electronic supplementary material

The online version of this article (doi:10.1186/s12950-015-0098-8) contains supplementary material, which is available to authorized users.

Serum Zinc, Copper, Magnesium and Selenium Levels in Children with Helicobacter Pylori Infection

OBJECTIVE

Helicobacter pylori infection can cause disease from mild to severe that may be accompanied by micronutrient deficiencies. We aimed to investigate serum zinc, copper, magnesium and selenium levels in Helicobacter pylori positive children.

MATERIALS AND METHODS

Thirty-four children, with chronic abdominal pain and diag-nosed to be Helicobacter pylori-positive and 20 healthy children with the same demo-graphic characteristics were included in the study. Serum zinc, copper and magnesium levels were measured in the flame unit of atomic absorption spectrophotometer, selenium levels were measured in the graphite unit of the same atomic absorption spectrophotometer.

RESULTS

Serum zinc levels were significantly higher and serum magnesium levels were significantly lower (p<0.05) in Helicobacter pylori positive children than those of the control group. Although copper levels were lower in patient group than in control group, this difference was not statistically significant (p>0.05). There was no significant difference between serum selenium levels of two groups.

CONCLUSION

We concluded that in Helicobacter pylori-positive children, many trace elements and mineral metabolism may change.

Is Helicobacter pylori infection a risk factor for childhood periodic syndromes?

Background and objectives

Helicobacter pylori (H. pylori) infection has been assumed to have roles in various extra-digestive diseases. The current study was designed to evaluate the incidence of H. pylori infection in patients with cyclic vomiting syndrome and its possible role in the etiology of this disease.

Design and setting

In this case-control study, 120 cases with diagnoses of cyclic vomiting or abdominal migraine who were registered at the Gastroenterology Clinic at Shiraz University of Medical Sciences from 2010 to 2013 were enrolled.

Materials and methods

Primarily information regarding the patients' diseases were collected with a data gathering sheet, and fresh morning stool samples were collected from the patients and examined for H. pylori stool antigen with the H. pylori Ag EIA test kit. The results were compared with those of healthy children from the control group.

Results

A total of 120 patients with cyclic vomiting (47.5%) and abdominal migraine (52.5%) with a mean age of 7.1 ± 3.4 (range 2-16 years) and a male-to-female ratio of 1.6 were included. The HPs Ag tests were positive in only 7 (5.8%) patients in our case group, and the HPs Ag tests were positive in 13 (13%) of the children in the control group; this difference was statistically insignificant.

Conclusion

Our study did not support H. pylori infection as an etiological factor in CV or AM.

NF-κB activation and severity of gastritis in Helicobacter pylori-infected children and adults

BACKGROUND

In contrast to adults, Helicobacter pylori gastritis in children is reported as milder and ulcer disease as uncommon, but unequivocal data are lacking.

OBJECTIVES

To compare the frequency of gastro-duodenal ulcers in children and adults as well as the proportion of Helicobacter pylori infection in these patients and to study the effect of chronological age on NF-κB activation and on severity of gastritis.

DESIGN

Patients referred in one pediatric and one adult facility for upper GI endoscopy were included. Gastric biopsies were obtained in consecutive Helicobacter pylori-infected patients and age-matched negative controls for immunohistochemistry and electrophoresis mobility shift assay. Three age groups were defined: younger than 8 years, 8-17 years, and adults.

RESULTS

Peptic ulcer disease was less frequent in children and less frequently associated with Helicobacter pylori infection. When comparing infected subjects to controls, densities of neutrophils and CD20 cells in the lamina propria increased in all age groups, CD3 cells increasing only in patients older than 8 years and CD8 cells only in adults. NF-κB-p65-positive cells were also increased only in infected adults as well as NF-κB-binding activity. A positive correlation was found between age and densities of neutrophils and CD3, but not of CD8 or CD20 cells.

CONCLUSION

Peptic ulcer disease was less frequent in children and less frequently caused by Helicobacter pylori infection. The different clinical outcome of the infection in children can be the consequence of the lower mucosal immune response.

Geographic diversity of Helicobacter pylori in cadavers: forensic estimation of geographical origin

A method for determining the geographical origin of unidentified cadavers by determining the genotype of Helicobacter pylori, which is latent in one-half of the world's population, was developed. In the first stage, DNA was extracted from samplings at 5 points in the gastric mucosa of 177 individuals randomly selected from cadavers undergoing medico-legal autopsy. 16S-rDNA of H. pylori DNA was detected by polymerase chain reaction (PCR) in 101 cadavers (57.0%); by sex, 74 of 123 (60.1%) males and 28 of 54 (46.4%) females were positive. There were no significant differences in H. pylori detection rate among the 5 sampling points of the gastric mucosa, cause of death, or age. In the second stage, amplified fragments of H. pylori vacA regions s and m from 17 individuals with the following ethnic backgrounds were sequenced: Japanese, 10; Chinese, 2; South Korean, 1; Taiwanese, 1; Thai, 1; Afghan, 1; and Filipino, 1. A phylogenetic tree constructed with these and 28 previously reported H. pylori strain sequences revealed 3 major gene clusters consisting of East Asian type I (Japanese, South Korean and Chinese), Western type II, and Southeast Asia type III. The Taiwanese and Filipino samples deviated from the clusters type III to which they typically belong. The ultimate aim of the present study was to develop a more accurate method of determining of geographic origin of unidentified cadavers through the combination of the present method with other, virus-based methods H. pylori DNA was detected from over half of the cadavers tested and vacA genotypes showed specificity to geographical origin. Therefore, these results suggest that the H. pylori genome provides valuable additional information for tracing the geographical origin of unidentified cadavers.

Spontaneous autoimmune gastritis and hypochlorhydria are manifest in the ileitis-prone SAMP1/YitFcs mice

SAMP1/YitFcs mice serve as a model of Crohn's disease, and we have used them to assess gastritis. Gastritis was compared in SAMP1/YitFcs, AKR, and C57BL/6 mice by histology, immunohistochemistry, and flow cytometry. Gastric acid secretion was measured in ligated stomachs, while anti-parietal cell antibodies were assayed by immunofluorescence and enzyme-linked immunosorbent spot assay. SAMP1/YitFcs mice display a corpus-dominant, chronic gastritis with multifocal aggregates of mononuclear cells consisting of T and B lymphocytes. Relatively few aggregates were observed elsewhere in the stomach. The infiltrates in the oxyntic mucosa were associated with the loss of parietal cell mass. AKR mice, the founder strain of the SAMP1/YitFcs, also have gastritis, although they do not develop ileitis. Genetic studies using SAMP1/YitFcs-C57BL/6 congenic mice showed that the genetic regions regulating ileitis had comparable effects on gastritis. The majority of the cells in the aggregates expressed the T cell marker CD3 or the B cell marker B220. Adoptive transfer of SAMP1/YitFcs CD4(+) T helper cells, with or without B cells, into immunodeficient recipients induced a pangastritis and duodenitis. SAMP1/YitFcs and AKR mice manifest hypochlorhydria and anti-parietal cell antibodies. These data suggest that common genetic factors controlling gastroenteric disease in SAMP1/YitFcs mice regulate distinct pathogenic mechanisms causing inflammation in separate sites within the digestive tract.

Pathogenesis of gastritis in ileitis-prone SAMP1/Yit mice

Inflammatory bowel disease is a chronic inflammatory disease of the gut which manifests as ulcerative colitis or Crohn's disease. One of the most studied animal models of spontaneous Crohn's disease is the senescence-accelerated mouse (SAMP1/Yit strain) model. In SAMP1/Yit mice, although many immunological responses are perturbed, some evidence suggests that the primary defect lies in the epithelial cell barrier. In the process of studying epithelial permeability, we observed that the stomach in SAMP1/Yit mice also had increased permeability. Upon further examination, these mice were shown to have marked, chronic gastritis with focal to diffuse aggregates of mononuclear cells of mixed lineages. These aggregates were located predominantly in the oxyntic mucosa, with occasional lesions in the forestomach but with relatively fewer cellular infiltrates in the antral mucosa. Real-time RT PCR showed an increase in several helper T cell (Th cell)-derived pro-inflammatory cytokines in the gastric mucosa of SAMP1/Yit mice. However, many of the cells in the aggregates of SAMP1/Yit mice were B cells. SAMP1/Yit B cells exacerbate ileitis when co-transferred into immunodeficient recipients. The gastritis also reflects a contribution by B cells. As SAMP1/Yit mice were derived from AKR mice, we examined AKR mice and determined that they too have an increased occurrence of gastritis, although they do not develop ileitis. B cells contributed to the gastric inflammation in these mice also. Thus, SAMP1/Yit mice display gastritis as well as ileitis, and B cells appear to play a role in the pathogenesis of inflammation at both sites. This review will discuss some of the mechanisms that may account for these different manifestations of gastrointestinal disease.

Exposure to antibiotics in a United States-Mexico border birth cohort

OBJECTIVE

The goal was to compare the frequency of children's antibiotic intake, emphasizing antibiotics with anti-Helicobacter pylori effects, in El Paso, Texas, and Juarez, Mexico.

METHODS

Hispanic children were enrolled prenatally at mother-child clinics in El Paso, and Juarez, in 1998-2000, to identify determinants of H pylori infection. During follow-up examinations targeted every 6 months from 6 to 84 months of age, caretakers reported medication use during the preceding interval. Courses of any systemic and H pylori-effective antibiotics were compared for US and Mexican children.

RESULTS

Antibiotic data were available for 602 children, from 2938 follow-up visits. Overall antibiotic intake was higher in Juarez, where 84% of children received > or = 1 course during the follow-up period (52% of visits), compared with El Paso, where 76% of children received > or = 1 course (40% of visits). In contrast, the intake of H pylori-effective antibiotics was higher in El Paso, where 65% of children received > or = 1 course during the follow-up period (27% of visits), compared with Juarez, where 44% of children received > or = 1 course (16% of visits). Of H pylori-effective courses, 94% contained amoxicillin and 2% each clarithromycin, metronidazole, and furazolidone; uses were primarily for throat and ear infections, diarrhea, and cold/flu.

CONCLUSIONS

Pediatric antibiotic use was higher in Mexico than on the US side of the border. Apparent misuse of H pylori-effective antibiotics was more frequent in Juarez but also occurred in El Paso. Such misuse of antibiotics may lead to drug resistance and may impair the control of H pylori infection in this region.

Dietary and socio-economic factors in relation to Helicobacter pylori re-infection

AIM: To examine if dietary and socio-economic factors contribute to Helicobacter pylori (H pylori) re-infection.

METHODS: The population of patients consisted of subjects in whom H pylori infection had been successfully treated in the past. Patients were divided into two groups: I-examined group (111 persons with H pylori re-infection) and II-control group (175 persons who had not been re-infected). The respondents were interviewed retrospectively on their dietary habits and socio-economic factors.

RESULTS: A statistically significant lower frequency of fermented dairy products (P < 0.0001), vegetables (P = 0.02), and fruit (P = 0.008) consumption was noted among patients with H pylori re-infection as compared to those who had not been re-infected.

CONCLUSION: High dietary intake of probiotic bacteria, mainly Lactobacillus, and antioxidants, mainly vitamin C (contained in fruit and vegetables), might decrease the risk of H pylori re-infection.

Expression of COX-1, COX-2, and PPAR-gamma in the gastric mucosa of children with Helicobacter pylori infection

BACKGROUND

Gastric inflammation in patients with Helicobacter pylori infection is considered to be regulated by many kinds of inflammatory and cytoprotective factors. The present study examined the effects of cyclo-oxygenase (COX)-1, -2, and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) on gastric mucosal injury in children with H. pylori infection.

METHODS

The subjects were 24 children who underwent endoscopy for the evaluation of anemia or gastrointestinal symptoms, and they were divided into two groups: a H. pylori-positive group and -negative group. The numbers of neutrophils in the gastric mucosa of children with and without H. pylori infection and expression of COX-1, -2, and PPAR-gamma were examined, using reverse transcription-polymerase chain reaction.

RESULTS

The numbers of neutrophils were significantly higher in the H. pylori-positive group than in the H. pylori-negative group. The ratio of COX-1 mRNA to COX-2 mRNA in the H. pylori-positive group was significantly lower than that in the H. pylori-negative group. The ratio of PPAR-gamma m-RNA to beta-actin mRNA was significantly higher in the H. pylori-positive group than the H. pylori-negative group.

CONCLUSIONS

Enhanced production of COX-2 and PPAR-gamma in the gastric mucosa has cytoprotective and anti-inflammatory effects, although the relationship to the carcinogenic activity of COX-2 and PPAR-gamma should be clarified.

Improvement of the eradication rate of Helicobacter pylori gastritis in children is by adjunction of omeprazole to a dual antibiotherapy

AIM

The possible improvement of efficacy and tolerability of a 7-day dual antibiotherapy amoxicillin-clarithromycin (AC) on the eradication of Helicobacter pylori (H. pylori) gastritis in children by the adjunction of omeprazole (OAC) was studied.

METHODS

Forty-six children presenting with H. pylori gastritis, assessed at inclusion by endoscopy, H. pylori urease test, histology and/or culture were randomised to a twice-daily regimen of AC or OAC. A (13)C-urease breath test was performed 4-6 weeks after the end of the treatment period to evaluate H. pylori eradication.

RESULTS

A larger proportion of patients was H. pylori negative (69%) in the OAC regimen treatment 4-6 weeks after eradication treatment compared with those who received dual AC therapy (15%). A total of seven patients (three in the OAC and four in the AC group) reported adverse events (AEs). Only vomiting was reported in more than one patient (one in each treatment regimen) and only one AE was severe (urticaria: in the OAC group, but considered not related to treatment).

CONCLUSION

A larger eradication rate of H. pylori was obtained in the triple OAC group than in the dual AC group. Both therapy regimens can be safely administered to children for 7 days.

Comparison of the 13C-urea blood test to histology and rapid urease testing in the diagnosis of Helicobacter pylori infection in children

OBJECTIVE

Helicobacter pylori infection is commonly investigated in children with abdominal pain. The definitive means of diagnosing infection, histology, requires endoscopy and sedation, making it invasive and expensive. Our objective was to compare histology against a less invasive and safer method, the 13C-urea blood test.

PATIENTS AND METHODS

Forty children with abdominal pain undergoing upper endoscopy were randomized into either of 2 dosages of 13C-urea. Several biopsies were taken for histology and rapid urease testing. After endoscopy, each child ingested a randomly assigned dosage of either 75 mg or 125 mg 13C-urea, and blood was withdrawn 30 min later.

RESULTS

Irrespective of the dosage of 13C-urea, the 13C-urea blood test performed with high accuracy (89%) when compared against either histology or rapid urease testing. The sensitivity and specificity of the blood test was 83% and 91%, respectively. When the smaller dosage of 13C-urea was used, the accuracy of the blood test was 100% compared with histology. There were no adverse events related to using either dosage of 13C-urea.

CONCLUSIONS

The 13C-urea blood test may be comparable with histology in diagnosing H. pylori infection in children, and the smaller dosage of 13C-urea does not adversely affect blood test performance. The 13C-urea blood test is well tolerated in children.

Effect of a probiotic food as an adjuvant to triple therapy for eradication of Helicobacter pylori infection in children

OBJECTIVE

Current recommendations for treatment of Helicobacter pylori infection include a proton pump inhibitor in combination with two antibiotics. We evaluated the potential activity of a probiotic food as an adjuvant to antibiotic triple therapy for eradication of H. pylori infection in children from Buenos Aires, Argentina.

METHODS

Sixty-five children who tested positive for H. pylori, as diagnosed by (13)C-urea breath test and endoscopy, were included in this study. Patients were randomized to receive 1-wk triple therapy plus probiotic food (treated group) or milk placebo (control) that was administered for 3 mo. Probiotic food consisted of 250 mL of a commercial yogurt containing Bifidobacterium animalis and Lactobacillus casei (10(7) colony-forming units/mL). Post-treatment urea breath test controls were performed 1 and 3 mo after the end of triple therapy.

RESULTS

We found no significant differences in H. pylori eradication rates (ERs) at 1 and 3 mo between the treated group (ER = 45.5% and 42.4%) and the control group (ER = 37.5% and 40.6%). Relative risks between groups were 0.87 (95% confidence interval 0.58-1.32, P = 0.345) in the first month and 0.97 (95% confidence interval 0.64-1.46, P = 0.542) in the third month.

CONCLUSIONS

We could not demonstrate an adjuvant effect of the studied probiotic food to triple therapy in the eradication of H. pylori infection in children in Buenos Aires, Argentina. However, we found lower ERs than those reported for the same therapeutic scheme in developed countries, indicating that bacterial resistance and alternative therapeutic strategies should be studied.

Helicobacter pylori genotypes in children from a population at high gastric cancer risk: no association with gastroduodenal histopathology

OBJECTIVES

Both bacterial and host determinants underlying differences in histopathology and clinical outcome in H. pylori pediatric infection, as compared to adults, are still poorly documented. Pediatric studies may provide important insights on H. pylori infection immunopathogenesis, particularly in high gastric cancer risk populations. The present study concerns H. pylori genotypic diversity of isolates in children from a population with high gastric cancer risk, and its association with demographic and clinical variables, including gastroduodenal endoscopic and histopathological features.

METHODS

A total of 119 subjects (mean age 10.3 yr, 1.5-18.0 yr) with H. pylori infection were studied. H. pylori vacA, cagA, and iceA genotypes were determined (PCR) in antral-obtained primary cultures; histopathological evaluation was performed in corpus, antrum, and duodenum biopsy specimens.

RESULTS

cagA-, vacA s2m2, and iceA2 were the most prevalent genotypes. No association was observed between H. pylori genotypes and subject demographic and clinical variables, with the exception of a significant association between vacA s2 genotype and lower corpus inflammation score (p< 0.03).

CONCLUSIONS

In this pediatric cohort, H. pylori genotype profiles were distinct from those reported in adult subjects in the same area, with a lower prevalence of the putative more virulent genotypes. Moreover, they were not associated with clinical expression of gastroduodenal disease, suggesting the potential role of host and/or environmental factors for the development of clinical disease at a later age.

Helicobacter pylori as cause of gastrointestinal disease in children with hemato-oncologic diseases

After documentation of a case of life threatening Helicobacter pylori (H. pylori) gastric ulcer in an adolescent girl on treatment for acute lymphoblastic leukaemia, we started to systematically look for gastro-intestinal symptoms due to H. pylori infection in our cancer patients at G. Gaslini Children's Hospital. During a period of 46 months, we observed 13 further cases of severe dyspepsia syndrome or gastro intestinal bleeding associated with presence of H. pylori faecal antigen. All patients recovered with appropriate therapy. H. pylori may represent a cause of severe gastrointestinal complications in children with cancer or following bone marrow transplant.

Mucosal lymphocyte subsets and HLA-DR antigen expression in paediatric Helicobacter pylori-associated gastritis

Paediatric studies may provide important insights into the immunopathology of Helicobacter pylori-associated gastritis, as mucosal changes reflect different stages of the immunoinflammatory response. We characterized, by quantitative immunohistochemistry, gastric mucosal lymphocyte phenotype and HLA-DR antigen expression and evaluated correlation with histopathology, in H. pylori-infected (Hp+ve) and uninfected children (Hp-ve). In the infected group, lamina propria CD3+ and IgA plasmocyte cell numbers were significantly higher and a trend for predominance of CD8+ over CD4+ was observed both in epithelium and lamina propria. A correlation of inflammation score with lamina propria CD3+ and CD4+ cell numbers and of CD45RO+ T lymphocytes with density of colonization was observed. The proportion of epithelial cells expressing HLA-DR antigen was significantly higher in the Hp+ve group and furthermore, glandular HLA-DR expression correlated with lamina propria CD3+ cell numbers, emphasizing the potential role of epithelial cells as antigen-presenting cells at this stage of infection.

CagA positivity and its association with gastroduodenal disease in Turkish children undergoing endoscopic investigation

BACKGROUND

Cytotoxin-associated gene A (CagA) product is a bacterial virulence factor contributing to the pathogenicity of Helicobacter pylori (HP) infection in humans. Host factors, which vary in different countries, interact with bacterial factors to determine the disease state. Our objective was to investigate the frequency of CagA-positive HP strains and evaluate the contribution of CagA positivity to symptoms and development of mucosal lesions in HP-infected Turkish children.

METHODS

We conducted a prospective clinical trial in 240 consecutive Turkish children undergoing endoscopy (110 girls, 130 boys; mean age, 8.7 +/- 4.3 years). HP infection was diagnosed on the basis of a positive rapid urease test and histology of the mucosal specimens. HP IgG and CagA IgG antibodies were measured by enzyme-linked immunosorbent assay in HP-positive children.

RESULTS

The HP positivity rate was 50.4% in our study group (51 girls, 70 boys; mean age, 9.9 +/- 3.9 years). CagA was positive in 74.4%. HP infection was less common in children with vomiting (25.9%, P < 0.05). CagA positivity was not associated with any clinical symptom. HP positivity was higher in children with duodenal ulcer (80% vs. 49.1%, P = 0.05); while CagA positivity was similar. Antral nodularity was strongly associated with HP positivity and CagA positivity (30.6% vs. 3.4% and 36.7% vs. 12.9%, respectively, P < 0.05). A negative association between CagA positivity and esophagitis was observed (20% vs. 76.7%, P < 0.05).

CONCLUSIONS

CagA positivity is common in HP-infected Turkish children. Esophageal lesions are less common in children infected with CagA-positive strains. Although HP is associated with duodenal ulcer disease, CagA positivity does not seem to contribute to development of ulcers in children in our series.

Evaluation of rapid test Assure Helicobacter pylori for diagnosis of H. pylori in pediatric population

Non-invasive tests are needed to assess Helicobacter pylori infection, especially to screen a pediatric population. Assure H. pylori Rapid Test (Genelabs Diagnostics, Singapore) is an immunochromatographic assay device intended for the rapid detection of antibodies to H. pylori in human serum, plasma or whole blood. The aim of this study was to evaluate the performance of the rapid test, Assure H. pylori, in the diagnosis of H. pylori infection in children, using a Portuguese pediatric population. The study group included 130 children with age ranging from 1 to 14 years old (average age 9.2+/-3.1 years). According to the gold standard, 70 of the 130 patients studied were H. pylori positive and 60 were H. pylori negative. Using Assure H. pylori Rapid Test (Genelabs Diagnostics, Singapore), 53 sera had a positive result after 15 min (resulting in 17 false negatives) and 57 sera a negative result (resulting in 3 false positives). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the test were 75.7%, 95.0%, 94.6% and 77.0% respectively. When a longer read time of 45 min is considered, the rapid test revealed a good performance (sensitivity 98.6% and specificity 95%) in the evaluation of the H. pylori infection in a pediatric population. In conclusion, the test showed a good performance, suggesting its applicability as a screening method for the H. pylori infection.

Cytokine expression in pediatric Helicobacter pylori infection

Helicobacter pylori infection is one of the most common gastrointestinal infections worldwide and almost invariably causes chronic gastritis in the infected host. A predominant Th1 profile has been demonstrated in H. pylori-infected mucosa from adults, but no previous study has evaluated in situ cytokine expression in children. We therefore examined expression of proinflammatory, anti-inflammatory, and regulatory cytokines by immunohistochemistry in cryopreserved antral biopsy specimens from 10 H. pylori-infected and 10 uninfected children and correlated expression of cytokines with histology scores. Concomitant expression of interleukin-8 (IL-8), gamma interferon (IFN-gamma), IL-4, transforming growth factor beta, and tumor necrosis factor alpha was seen in 8/10 H. pylori-infected cases and in 5/10 noninfected cases; all H. pylori-infected subjects showed staining for at least two of the cytokines. The proportion of epithelial cytokine-specific staining did not differ significantly between the groups, either in surface or glandular epithelium. Furthermore, no significant differences were noticed between intraepithelial or lamina propria lymphocyte staining in the groups. There was, however, a tendency of higher numbers of IFN-gamma- and IL-8-positive cells in the H. pylori-infected group. IFN-gamma and IL-8 lamina propria lymphocyte expression correlated significantly with antrum chronic inflammation, but there was no correlation between histology scores and epithelial cytokine expression. When the same techniques were used, the cytokine response appeared to be smaller in H. pylori-infected children than in adults, and there was no clear Th1 dominance. These results therefore suggest a different mucosal immunopathology in children. It remains to be determined whether the gastric immune response is downregulated in children with H. pylori infection and whether this is relevant to the outcome of infection.

Seroconversion of Helicobacter pylori in Korean male employees

OBJECTIVE

Helicobacter pylori infections are acquired primarily during childhood, but also occur in adults. As no published estimates are available on the seroconversion rate of H. pylori in the Korean population, the purpose of this study was to evaluate the incidence and prevalence of H. pylori infection in male Korean employees.

MATERIAL AND METHODS

Levels of anti-H. pylori IgG were measured by ELISA, and gastroscopic findings were checked in 588 employees of the Subway Corporation (aged 40-60 years, male) in 1997, 1998, 1999, 2000, and 2003. Questionnaire responses concerning socio-economic state, education level, and type of job were analyzed versus serologic test results.

RESULTS

Out of the 588 subjects, 455 (77.4%) were positive for anti-H. pylori IgG. Multivariate analysis showed that abnormal gastroscopic findings, especially duodenal ulcers, were more frequent in the H. pylori-positive group (17.6) than in the initially H. pylori-negative group (9.0%) (OR: 1.71, 95% CI: 1.07-2.81). Among the multiple questionnaires, only the proportion of white-collar workers was significant; that is, it was lower in the H. pylori-positive group (44/6) than in the initial H. pylori-negative group (57.9%) (OR: 0.62, 95% CI: 0.41-0.92). Seventeen of 133 subjects (12.8%) who were initially seronegative underwent seroconversion during a 6-year follow-up period, a seroconversion rate of 2.13%/annum.

CONCLUSIONS

The seroprevalence of H. pylori infection in this study group was 77.4% and duodenal ulcer was more frequent in H. pylori-positive subjects, thus confirming the relationship between H. pylori infection and duodenal ulcer. Seroconversion of H. pylori infection in the Korean male employees was determined to be 2.13% per year, suggesting that new infections occur continuously even during late adulthood.

Cytokines in the gastric mucosa of children with Helicobacter pylori infection

AIM

Few studies have looked at the cytokine profile in gastric mucosa in children with Helicobacter pylori infection. This study investigated cytokines and their effects on histological abnormalities in the gastric mucosa of children with H. pylori infection.

METHODS

The levels of interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and IL-8 proteins were measured in biopsy specimens from the gastric antrum and corpus of children with H. pylori infection, and related to inflammatory cell infiltrations.

RESULTS

The antral and corporal mucosal levels of IFN-gamma and IL-8 proteins were significantly higher in children with H. pylori infection than in uninfected children, but there was no such difference in the levels of IL-4 protein. The antral mucosal level of IL-8 protein was significantly higher than the corporal mucosal level of IL-8 protein in the infected children. Inflammatory cell infiltration was significantly higher in the infected children than in the uninfected children, but there were no significant correlations between mucosal cytokine levels and inflammatory cell infiltrations.

CONCLUSION

The results suggest that the predominant Th1 cytokine response and enhanced IL-8 production in the mucosa may be involved in the gastric inflammation seen in children infected with H. pylori, as well as in adult patients.

Urinary 8-hydroxydeoxyguanosine excretion in children before and after therapy for eradication of Helicobacter pylori infection

AIM

A number of reports have implicated oxygen free radicals in the pathogenesis of Helicobacter pylori (H. pylori)-associated disease. 8-hydroxydeoxyguanosine (8-OHdG) has recently been accepted as a sensitive marker for reflecting the oxidative DNA damage. However, there have been no previous studies comparing the changes in urinary 8-OHdG excretions before and after therapy for eradication of H. pylori infection, or to examine 8-OHdG excretions in children with H. pylori infection. The aim of this study was therefore to examine the DNA damage in gastric mucosal cells in children with H. pylori infection.

METHODS

Urinary 8-OHdG excretions were measured before and after therapy for eradication of H. pylori infection in 15 children diagnosed with the H. pylori infection and 13 parents who were also suffering from the same infection.

RESULTS

In both the children and their parents, no significant differences were found in urinary 8-OHdG excretions either before or after the eradication therapy. Furthermore, there was no significant difference in urinary 8-OHdG excretions between 8 children with peptic ulcers and 7 children without ulcers, either before or after the therapy.

CONCLUSION

These results suggest that measurement of urinary 8-OHdG levels is not useful for evaluation of the DNA damage in H. pylori-infected gastric mucosa in children.

Genotypes of Helicobacter pylori in children with upper abdominal pain

BACKGROUND

Studies related to genotypes of Helicobacter pylori infection and upper abdominal pain (UAP) in children are scarce all over the world. We prospectively analyzed the association between H. pylori infection and UAP in our study group of children and evaluated the vacA genotypes associated with this disorder.

METHODS

We investigated 34 children with UAP (group I) and another 110 children as controls without UAP (group II) for H. pylori infection, using antral biopsies by culture, rapid urease tests, histopathology and ureA polymerase chain reaction (PCR). Genotyping was performed using specific cagA and vacA primers on 52 H. pylori strains (group I = 21; 18 boys, mean age 10.33 +/- 2.47 years; group II = 31; boys 21, mean age 9.63 +/- 2.51 years).

RESULTS

A significant association between H. pylori infection and UAP was observed when compared to controls (21/34; 61.8%vs 31/110; 28.2%; P = 0.0004). cagA positive H. pylori strains were detected in 20 (95.2%) children with UAP and in 28 (90.3%) controls. Mixed infection was detected in 25% of children with no significant difference between the groups. On univariate regression analysis, s1a, m1 alleles and s1a/m1 genotype of vacA had significant associations with UAP (P = 0.018, 0.015 and 0.007, respectively), while s2 and m2 alleles and the s2/m2 genotype were significantly more frequent in controls (P = 0.034, 0.001 and 0.034, respectively).

CONCLUSIONS

H. pylori infection is strongly associated with UAP in children and a significantly higher proportion have s1a, m1 alleles and s1a/m1 genotype. The negative associations of vacA s2, m2 alleles and s2/m2 genotype with UAP indicate that they are unlikely to have an important role in this disorder.

Knowledge, attitudes, and practice styles of North American pediatric gastroenterologists: Helicobacter pylori infection

OBJECTIVE

Most Helicobacter pylori infections are acquired during childhood. The North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) recently published practice guidelines for managing pediatric H. pylori infection. Before this publication, the authors conducted a survey to assess pediatric gastroenterologists' knowledge and practices regarding H. pylori.

METHODS

One hundred nine of 514 NASPGHAN members completed an Internet-based questionnaire on H. pylori infection.

RESULTS

Eighty-two percent of respondents performed outpatient testing for H. pylori. Of these, only 31% restricted testing to children aged >5 years. Most recommended testing for H. pylori in guideline-recommended conditions; some would not treat infected patients. Ninety-seven percent would test for H. pylori in a child with new duodenal ulcer (DU), 79% in a child with a history of DU, and 91% in a child with new gastric ulcer. However, only 86%, 60%, and 91%, respectively, would treat H. pylori infection in those conditions. A proton pump inhibitor (PPI)-based triple regimen was the first-choice therapy for 78% of respondents. Correct estimates of rates of resistance to amoxicillin, clarithromycin, metronidazole, and tetracycline were 10%, 17%, 43%, and 12%, respectively. Eighty-six percent believed there was insufficient research on H. pylori in children.

CONCLUSIONS

North American pediatric gastroenterologists seem well informed about H. pylori infection in children despite the lack of published guidelines at the time of survey. Knowledge about antibiotic resistance rates was deficient. Most offered some outpatient testing for H. pylori and would test children with ulcer disease. However, some would not treat patients based on a positive result.

Helicobacter pylori infection in children

A number of scientific breakthroughs since H pylori first became recognized as a human pathogen have increased our understanding of the pathogenesis of gastroduodenal disease. In particular, advances in molecular bacteriology and the complete sequencing of the H pylori genome in 1999, and soon thereafter the human genome, provide tools allowing better delineation of the pathogenesis of disease. These molecular tools for both bacteria and host should now be applied to multicenter pediatric studies that evaluate disease outcome. More recent developments indicate that a better understanding of the microbial-host interaction is critical to furthering knowledge with respect to H pylori-induced diseases. Studies are needed to evaluate either DNA-based or more traditional protein-based vaccines, to evaluate more specific antimicrobials that confer minimal resistance, and to evaluate probiotics for the management of H pylori infection. Multicenter multinational studies of H pylori infection in the pediatric population, which include specific, randomized controlled eradication trials, are essential to extend current knowledge and develop better predictors of disease outcome.

The disease spectrum of Helicobacter pylori: the immunopathogenesis of gastroduodenal ulcer and gastric cancer

Helicobacter pylori is a gram-negative bacterium that resides under microaerobic conditions in a neutral microenvironment between the mucus and the superficial epithelium of the stomach. From this site, it stimulates cytokine production by epithelial cells that recruit and activate immune and inflammatory cells in the underlying lamina propria, causing chronic, active gastritis. Although epidemiological evidence shows that infection generally occurs in children, the inflammatory changes progress throughout life. H. pylori has also been recognized as a pathogen that causes gastroduodenal ulcers and gastric cancer. These more severe manifestations of the infection usually occur later in life and in a minority of infected subjects. To intervene and protect those who might be at greatest risk of the more severe disease outcomes, it is of great interest to determine whether bacterial, host, or environmental factors can be used to predict these events. To date, several epidemiological studies have attempted to define the factors affecting the transmission of H. pylori and the expression of gastroduodenal disease caused by this infection. Many other laboratories have focused on identifying bacterial factors that explain the variable expression of clinical disease associated with this infection. An alternative hypothesis is that microorganisms that cause lifelong infections can ill afford to express virulence factors that directly cause disease, because the risk of losing the host is too great. Rather, we propose that gastroduodenal disease associated with H. pylori infection is predominantly a result of inappropriately regulated gastric immune responses to the infection. In this model, the interactions between the immune/inflammatory response, gastric physiology, and host repair mechanisms would dictate the disease outcome in response to infection.

Expression of proinflammatory and Th1 but not Th2 cytokines is enhanced in gastric mucosa of Helicobacter pylori infected children

BACKGROUND

Helicobacter pylori-induced gastric inflammation is thought to be largely regulated by cytokines.

PATIENTS AND METHODS

The expression of interferon-gamma, interleukin-12, interleukin-4, interleukin-10, interleukin-8, and interleukin-17 mRNA was examined on gastric mucosal samples from 24 children by semiquantitative reverse transcription polymerase chain reaction and southern blotting. Biopsy-based tests, serology, and urea 13C breath test were used to assess Helicobacter pylori status. Gastric biopsies were also evaluated for bacterial density, chronic inflammation, and acute inflammatory activity.

RESULTS

Interferon-gamma, interleukin-12, interleukin-8 and interleukin-17 expression was higher in Helicobacter pylori-infected (n=13) than uninfected (n=11) children. Conversely, interleukin-4 and interleukin-10 expression did not differ between Helicobacter pylori-infected and uninfected children. In Helicobacter pylori-infected children, interferon-gamma, interleukin-12, interleukin-8 and interleukin-17 expression correlated with bacterial density, and Interferon-gamma and interleukin-12 expression with chronic inflammation score.

CONCLUSIONS

The findings of this study indicate that, in children, Helicobacter pylori-induced inflammatory response would favour production of proinflammatory cytokines and development of cell-mediated immunity, namely Th1 response.

A comprehensive review of the natural history of Helicobacter pylori infection in children

Across populations of children, Helicobacter pylori prevalence ranges from under 10% to over 80%. Low prevalence occurs in the U.S., Canada, and northern and western Europe; high prevalence occurs in India, Africa, Latin America, and eastern Europe. Risk factors include socioeconomic status, household crowding, ethnicity, migration from high prevalence regions, and infection status of family members. H. pylori infection is not associated with specific symptoms in children; however, it is consistently associated with antral gastritis, although its clinical significance is unclear. Duodenal ulcers associated with H. pylori are seldom seen in children under 10 years of age. H. pylori-infected children demonstrate a chronic, macrophagic, and monocytic inflammatory cell infiltrate and a lack of neutrophils, as compared with the response observed in adults. The effect of H. pylori infection on acid secretion in children remains poorly defined. The events that occur during H. pylori colonization in children should be studied more thoroughly and should include urease activity, motility, chemotaxis, adherence, and downregulation of the host response. The importance of virulence determinants described as relevant for disease during H. pylori infection has not been extensively studied in children. Highly sensitive and specific methods for the detection of H. pylori in children are needed, especially in younger pediatric populations in which colonization is in its early phases. Criteria for the use of eradication treatment in H. pylori-infected children need to be established. Multicenter pediatric studies should focus on the identification of risk factors, which can be used as prognostic indicators for the development of gastroduodenal disease later in life.