Gastroesophageal reflux

Gastroesophageal reflux is common in infants and generally resolves spontaneously within the first year of life as the lower esophageal sphincter mechanism matures. The reflux is only considered a "disease" (GERD) when it becomes symptomatic or causes pathological consequences. GERD is commonly associated with esophageal atresia and there is a high incidence in neurologically impaired children; in both groups conservative treatment is notoriously ineffective. The diagnosis of GER is made on upper gastrointestinal contrast studies, endoscopy and pH monitoring. Medical management comprises antacids, reduction of gastric acid production and prokinetic agents. The indications for antireflux surgery include an established esophageal stricture, associated anatomical defect and failure of medical therapy. Apnoeic episodes secondary to documented GER in the infant, constitute an absolute indication for early surgery.

Use of complementary and alternative medicine in children: too important to ignore

There is evidence that complementary and alternative medicine (CAM) is commonly being used for Australian children, however, at the same time, many doctors have little interest or understanding of the topic. Just as with mainstream treatments, CAM therapies have significant potential for adverse effects and drug interactions. Some of these are potentially serious. The use of CAM therapies in children is not an occasional fringe activity, and evidence suggests its usage will increase further. Whatever one's own views on the role of CAM in childrens health care, the topic is important and it should not be ignored.

Distribution of cagG gene in Helicobacter pylori isolates from Chinese patients with different gastroduodenal diseases and its clinical and pathological significance

AIM: To determine the distribution of cagG gene of Helicobacter pylori (H pylori) isolates cultured from patients with various digestive diseases and its relationship with gastroduodenal diseases.

METHODS: cagG was amplified by polymerase chain reaction in 145 H pylori isolates cultured from patients with chronic gastritis (n = 72), duodenal ulcer (n = 48), gastric ulcer (n = 17), or gastric and duodenal ulcer (n = 8), and the relationship between cagG status and the grade of gastric mucosal inflammation was determined.

RESULTS: cagG was present in 91.7% of the 145 H pylori isolates, with the rates were 90.3%, 93.8%, 88.2% and 100.0%, respectively, in those from patients with chronic gastritis, duodenal ulcer, gastric ulcer, and gastric and duodenal ulcer. There was no significant difference among the four groups (P > 0.05). The average grade of gastric mucosal inflammation in the antrum and corpus was 1.819 ± 0.325 and 1.768 ± 0.312, respectively in cagG positive patients, whereas the average inflammation grade was 1.649 ± 0.297, 1.598 ± 0.278 respectively in cagG negative cases (P > 0.05).

CONCLUSION: cagG gene of H pylori was quite conservative, and most H pylori strains in Chinese patients were cagG positive. cagG status was not related to clinical outcome or the degree of gastric mucosal inflammation. Therefore, cagG can not be used as a single marker for discrimination of H pylori strains with respect to a specific digestive disease.

New approaches to Helicobacter pylori infection in children

Helicobacter pylori infection is usually acquired during childhood, and evidence-based guidelines regarding diagnosis and treatment of infected children have been recently published. Diseases associated with H. pylori infection are gastritis, duodenal ulcers, mucosal-associated lymphoid-type (MALT) lymphoma, and gastric adenocarcinoma. The association of specific symptoms with H. pylori infection in children and adults (ie, recurrent abdominal pain and nonulcer dyspepsia) remains controversial. Additionally, the role of H. pylori in gastroesophageal reflux disease or in extra-gastrointestinal diseases (ie, coronary artery disease) lacks sufficient evidence to demonstrate causality. The diagnosis of H. pylori-associated diseases in children can reliably be made through gastroduodenal endoscopy with biopsies. Clinical trials are underway for the validation of noninvasive diagnostic tests for the H. pylori-infected child, and current guidelines recommend eradication therapy for infected children with duodenal and gastric ulcer, gastric lymphoma, and atrophic gastritis with intestinal metaplasia. The natural history of childhood H. pylori infection is poorly described. Moreover, rational approaches to the prevention and control of childhood H. pylori infection are critically needed, requiring characterization of the determinants for acquisition and persistence and the disease outcomes following eradication.

Cytoskeletal rearrangements in gastric epithelial cells in response to Helicobacter pylori infection

Helicobacter pylori causes host epithelial cell cytoskeletal rearrangements mediated by the translocation and tyrosine phosphorylation of an outer-membrane protein, CagA, and by the vacuolating cytotoxin, VacA. However, the mechanisms by which H. pylori mediates cytoskeletal rearrangements in infected host cells need to be more clearly defined. The aim of this study was to determine the effects of H. pylori isolates from children on the architecture of host gastric epithelial cells. Gastric epithelial (AGS) cells were infected with type I (cagE(+), cagA(+), VacA(+)) H. pylori, a type II H. pylori strain (cagE(-), cagA(-), VacA(-)) or a cagE isogenic mutant. Double-labelled immune fluorescence was used to detect adherent H. pylori and the distribution of F-actin, alpha-actinin and Arp3. Both type I and type II H. pylori strains induced stress fibres in gastric epithelial cells that were not observed in uninfected cells. Type I H. pylori also induced cell elongation (hummingbird phenotype) after 4 h of infection, whereas the type II H. pylori strain did not. Less elongation occurred when AGS cells were exposed to a cagE isogenic mutant, compared with the parental strain. Confocal microscopy showed Arp3 accumulation in AGS cells infected with wild-type H. pylori, but not in response to infection with the cagE mutant. These findings indicate that type I H. pylori induce a stress fibre-like phenotype in infected gastric epithelia by a mechanism that is different from the induction of host-cell elongation. In addition to CagA and VacA, cagE also impacts on the morphology of infected gastric epithelial cells.

Helicobacter pylori infection in pediatrics

A high prevalence and early colonization of Helicobacter pylori infection in childhood was described again this year in developing countries in contrast to developed ones. Upper gastrointestinal endoscopy including gastric biopsies remains the diagnostic gold standard method for this infection. Also noninvasive tests have been studied in children, including serology, 13C-urea breath test and stool antigen test, showing good results in the different age groups as compared to the gold standard. However, the infection often remains asymptomatic in children and the role of this bacterium in gastric manifestations is the subject of conflicting reports. Extra-digestive manifestations are also reported in the course of this infection. The treatment of H. pylori infection is influenced by resistance of the bacteria to the antibiotics used. We suggest that eradication of H. pylori should take place only after susceptibility testing. The association of a proton pump inhibitor and two antibiotics for 1 or 2 weeks gives the best eradication rates. The crucial question to elucidate is whether asymptomatic children should be treated to prevent cancer in the future.

Familial occurrence of inflammatory bowel disease in celiac disease

BACKGROUND

The authors have previously reported a possible increased risk of the familial occurrence of Crohn's disease in patients with celiac disease.

AIM

The aim of the current study was to evaluate in a case-control study the familial occurrence of inflammatory bowel disease (IBD) in first-degree relatives of patients with celiac disease.

METHODS

One hundred eleven consecutive patients with biopsy-proven celiac disease were interviewed to ascertain whether IBD was present in first-degree relatives. The number of relatives, their ages, and possible IBD status were collected in a questionnaire. When a diagnosis of familial IBD was reported, the diagnosis was checked in the hospital records. Two hundred twenty-two controls matched for age and sex (111 from the general population and 111 from orthopedic wards) were also interviewed regarding the possible occurrence of IBD in first-degree relatives. The chi2 test was used to evaluate the difference in proportion of familial occurrence of IBD among individuals with celiac disease and controls.

RESULTS

Among 600 first-degree relatives of patients with celiac disease, 10 cases of IBD were identified among first-degree relatives (7 cases of ulcerative colitis and 3 cases of Crohn's disease), whereas only 1 case of IBD was identified among the 1,196 first-degree relatives of control patients (p < 0.01). When ulcerative colitis and Crohn's disease were analyzed separately, only the prevalence of ulcerative colitis was statistically significant (p </= 0.02).

CONCLUSIONS

This case-control study shows that there is a significantly increased prevalence of familial ulcerative colitis in patients with celiac disease. There was no significant increase in the prevalence of Crohn's disease in patients with celiac disease. The possible role of this association is discussed.

Effect of oral tacrolimus (FK 506) on steroid-refractory moderate/severe ulcerative colitis

BACKGROUND

Steroid refractory ulcerative colitis is most commonly treated with intravenous ciclosporin to avoid colectomy. In search for an alternative drug that can be administered orally we investigated oral tacrolimus (FK 506) for this indication.

METHODS

Nine patients with active, moderate/severe steroid refractory UC were treated with oral tacrolimus with a daily dose of 0.15 mg/kg body weight. After patients had responded azathioprine was added for long-term immunosuppression.

RESULTS

All patients responded within 1-2 weeks. After 12 weeks of tacrolimus therapy six patients (67%) were in complete remission, two patients (22%) had mild to moderate disease activity, and one patient (11%) underwent colectomy. After a mean follow up of 21 months six of the nine patients (67%) had their colon in situ. Two patients developed severe side-effects, one thrombopenia with intestinal bleeding, and one bicytopenia. Mild side-effects were common.

CONCLUSION

Oral tacrolimus may be an effective alternative to intravenous ciclosporin for the therapy of steroid-refractory ulcerative colitis. Patients receiving tacrolimus need to be watched carefully for side-effects.

Helicobacter pylori infection interferes with epithelial Stat6-mediated interleukin-4 signal transduction independent of cagA, cagE, or VacA

Helicobacter pylori is a bacterial pathogen evolved to chronically colonize the gastric epithelium, evade immune clearance by the host, and cause gastritis, peptic ulcers, and even gastric malignancies in some infected humans. In view of the known ability of this bacterium to manipulate gastric epithelial cell signal transduction cascades, we determined the effects of H. pylori infection on epithelial IL-4-Stat6 signal transduction. HEp-2 and MKN45 epithelial cells were infected with H. pylori strains LC11 or 8823 (type 1; cagA(+)/cagE(+)/VacA(+)), LC20 (type 2; cagA(-), cagE(-), VacA(-)), and cagA, cagE, and vacA isogenic mutants of strain 8823, with some cells receiving subsequent treatment with the Th2 cytokine IL-4, a known Stat6 activator. Immunofluorescence showed a disruption of Stat6-induced nuclear translocation by IL-4 in LC11-infected HEp-2 cells. IL-4-inducible Stat6 DNA binding in HEp-2 and MKN45 cells was abrogated by infection, but MKN45 cell viability was unaffected. A decrease in IL-4-mediated Stat6 tyrosine phosphorylation in nuclear and whole cell lysates was also observed following infection with strains LC11 and LC20, while neither strain altered IL-4 receptor chain alpha or Janus kinase 1 protein expression. Furthermore, parental strain 8823 and its isogenic cagA, cagE, and vacA mutants also suppressed IL-4-induced Stat6 tyrosine phosphorylation to comparable degrees. Thus, H. pylori did not directly activate Stat6, but blocked the IL-4-induced activation of epithelial Stat6. This may represent an evolutionarily conserved strategy to disrupt a Th2 response and evade the host immune system, allowing for successful chronic infection.

Effect of long-term administration of rebamipide on Helicobacter pylori infection in mice

BACKGROUND

It has been suggested that chronic, persistent, uncontrolled inflammations in the stomach could provide the basic step for the beginning of carcinogenesis. One of the potential clinical applications of rebamipide is the inhibition of the immunoinflammatory response in gastric mucosa imposed by Helicobacter pylori.

AIM

To determine the implications of long-term rebamipide treatment in H. pylori infection, we studied the underlying moleculo-pathological changes in gastric lesions in mice infected with H. pylori (SS1 strain), following this treatment.

METHODS

C57BL/6 mice were sacrificed 24 and 50 weeks after H. pylori infection, respectively. Colonization rates of H. pylori, degree of gastric inflammation and other pathological changes including atrophic gastritis and metaplasia, serum levels of IL-1beta, TNF-alpha, IFN-gamma and IL-10, mRNA transcripts of various mouse cytokines and chemokines, and NF-kappaB binding activities, and finally the presence of gastric adenocarcinoma were compared between an H. pylori infected group (HP), and an H. pylori infected group administered with long-term rebamipide-containing pellet diets (HPR).

RESULTS

Serum levels of IL-1beta, IFN-gamma and TNF-alpha, the gastric mucosal expression of ICAM-1, HCAM and MMP, and transcriptional regulation of NF-kappaB-DNA binding were all significantly decreased in the HPR group compared with the HP group. An RNase protection assay showed, in the rebamipide administered group, significantly decreased mRNA levels of apoptosis-related genes such as caspase-8, FasL, Fas, TRAIL and various cytokines genes such as IFN-gamma, RANTES, TNF-alpha, TNFR p75, IL-1beta. In the experiment designed to provoke gastric cancer through MNU treatment with H. pylori infection, the incidence of gastric carcinoma was not different in either group. However, long-term administration of rebamipide showed the advantage of decreasing precancerous lesions like chronic atrophic gastritis and showed molecular evidence of attenuation of proliferation.

CONCLUSION

The long-term administration of rebamipide should be considered in the treatment of H. pylori since it demonstrated molecular and biological advantages like a lessening of gastric inflammation and a possible chemopreventive effect.

Effects of Helicobacter pylori on intracellular Ca2+ signaling in normal human gastric mucous epithelial cells

In stomach, Helicobacter pylori (Hp) adheres to gastric mucous epithelial cells (GMEC) and initiates several different signal transduction events. Alteration of intracellular Ca2+ concentration ([Ca2+]i) is an important signaling mechanism in numerous bacteria-host model systems. Changes in [Ca2+]i induced by Hp in normal human GMEC have not yet been described; therefore, we examined effects of Hp on [Ca2+]i in normal human GMEC and a nontransformed GMEC line (HFE-145). Cultured cells were grown on glass slides, porous filters, or 96-well plates and loaded with fura 2 or fluo 4. Hp wild-type strain 60190 and vacA-, cagA-, and picB-/cagE- isogenic mutants were incubated with cells. Changes in [Ca2+]i were recorded with a fluorimeter or fluorescence plate reader. Wild-type Hp produced dose-dependent biphasic transient [Ca2+]i peak and plateau changes in both cell lines. Hp vacA- isogenic mutant produced changes in [Ca2+]i similar to those produced by wild type. Compared with wild type, cagA- and picB-/cagE- isogenic mutants produced lower peak changes and did not generate a plateau change. Preloading cultures with intracellular Ca2+ chelator BAPTA blocked all Hp-induced [Ca2+]i changes. Thapsigargin pretreatment of cultures to release Ca2+ from internal stores reduced peak change. Extracellular Ca2+ removal reduced plateau response. Hp-induced peak response was sensitive to G proteins and PLC inhibitors. Hp-induced plateau change was sensitive to G protein inhibitors, src kinases, and PLA2. These findings are the first to show that H. pylori alters [Ca2+]i in normal GMEC through a Ca2+ release/influx mechanism that depends on expression of cagA and picB/cagE genes.

Apoptosis of gastric lymphocytes in Helicobacter pylori-infected rhesus macaques

In vitro studies suggest that H. pylori induces apoptosis in gastric epithelial cells and perhaps in gastric lymphocytes as well. However, the early effects of H. pylori infection on lymphocyte apoptosis have not been examined in experimental animal models, nor have studies been performed using markers specific for T cells and T-cell subsets. Gastric T-cell apoptosis and Fas ligand expression were examined by flow cytometry after experimental infection of rhesus macaques with H. pylori. Infection induced transient apoptosis of gastric CD4+ and CD8+ T-cells, which began as soon as three days after inoculation and declined to baseline within eight weeks. Fas ligand expression showed a similar transient induction, suggesting that it mediates gastric T-cell apoptosis. We propose that transient, Fas-mediated apoptosis in gastric lymphocytes is a compensatory response to the initial T-cell inflammatory response after acute H. pylori infection.

Analysis of the vacA, cagA, cagE, iceA, and babA2 genes in Helicobacter pylori from sixty-one pediatric patients from the Midwestern United States

This study was designed to characterize H. pylori from pediatric gastric biopsy specimens in terms of several genes (vacA, cagA, cagE, iceA1, iceA2, and babA2) proposed to be involved in the pathogenesis of this organism. Many of these genes have been studied in adult H. pylori isolates, however, these genes have not been well characterized in H. pylori from children. Using PCR we observed that 44% of the H. pylori in our biopsies shared two common genotypes (vacA s1b m1, cagA, cagE, iceA2 +/- babA2). While 26% of the H. pylori had unique genotypes. The cag pathogenicity island associated genes, cagA and cagE, were found together in 64% or our H. pylori, while 84% were iceA2 positive. The presence of the babA2 gene has been proposed to be associated with a higher risk of H. pylori related diseases, however, we found that only 36% of our H. pylori contained this gene.

Helicobacter pylori activates Toll-like receptor 4 expression in gastrointestinal epithelial cells

Helicobacter pylori activates the transcription factor NF-kappaB, leading to proinflammatory cytokine production by gastric epithelial cells. However, the receptors for the initial bacterial interaction with host cells which activate downstream signaling events have not been completely defined. Recently, it has been shown that microbial components activate Toll-like receptors (TLRs), thereby leading to AP-1- and NF-kappaB-dependent transcription and resulting in the production of proinflammatory cytokines. The aim of this study was to determine whether H. pylori activates TLR4. Reverse transcription-PCR showed that both type I and type II H. pylori clinical isolates induced TLR4 mRNA expression in AGS cells compared with that by uninfected controls. H. pylori upregulated TLR4 protein expression in two gastric epithelial cell lines (AGS and MKN45) and one intestinal epithelial cell line (T84). Monoclonal TLR4 antibody inhibited lipopolysaccharide-induced interleukin-8 secretion from THP-1 macrophages but not from gastric epithelial cells infected with H. pylori. H. pylori demonstrated increased adherence to CHO TLR4-transfected cells compared with that to both CHO TLR2-transfected and nontransfected CHO cells (P < 0.01). These results indicate that H. pylori activates TLR4 expression in epithelial cells and that TLR4 can serve as a receptor for H. pylori binding.

Review article: diagnosis and treatment of Helicobacter: a 2002 updated review

The year 2002 saw advances on many fronts in the study of Helicobacter and gastroduodenal disease. Several studies have confirmed endoscopy as a valuable management procedure with confirmation of the diagnostic utility of the rapid urease test and the description of a new formulation of the test, which is more rapid in giving a result. Serology has been re-confirmed as a useful investigation in selected populations. Some commercial kits for near patient testing have also been assessed and although generally regarded as less accurate than laboratory based tests some have shown acceptable accuracy. The recent exciting development in diagnostic serology is the availability of the faecal antigen test; further studies have confirmed its usefulness as recommended screening tests. There have been several studies demonstrating that a test and treat policy has a significant patient benefit, both economic and medical, although there is some doubt if eradication of Helicobacter leads to regression of atrophy and metaplasia. However, in low Helicobacter-prevalence areas the test and treat policy is being challenged as an effective management strategy. Further studies have shown that compliance with treatment regimens is an important determinant of successful eradication. Finally several new eradication regimens have been reported particularly for use in patients who have had previous unsuccessful eradication attempts.

Investigation of the biological relevance of Helicobacter pylori cagE locus diversity, presence of CagA tyrosine phosphorylation motifs and vacuolating cytotoxin genotype on IL-8 induction in gastric epithelial cells

Isolates of Helicobacter pylori from dyspeptic patients in England and South Africa were tested for ability to induce interleukin-8 (IL-8) in gastric cells. All isolates were cagA-positive, which was used as a marker for the presence of the cag pathogenicity island. The aims were to determine if activities were related to diversity within cagE (HP0544), a locus encoding a key component in the Type IV secretion system, and if disease severity might be linked to a combination of strain features. We found that isolates were heterogeneous in ability to induce IL-8 activity with the 23 positive isolates (59%) showing activities ranging from 260 to 3200 pg ml(-1). The cagE locus was detected in most isolates and RFLP analysis of a 1.52-kb internal fragment showed interstrain diversity with 12 combined (MboI/NlaIII) types. Most cagE genotypes were not associated with IL-8 induction, however two genotypes were found only in IL-8-inducing strains and one genotype was associated with lack of IL-8 induction. IL-8 activity was not associated with either the number or composition of cagA tyrosine phosphorylation motifs and vacA m-type. Although we found a weak association between cagE type and the ability to induce IL-8, our results imply that gastric cell factors or bacterial factors other than vacA, cagA and cagE are involved in the induction of IL-8 and the development of severe gastric disease.

Rescue therapy with tacrolimus is effective in patients with severe and refractory inflammatory bowel disease

BACKGROUND

Oral tacrolimus, approved for the prophylaxis of organ rejection in liver or kidney transplants, has been reported to be effective in anecdotal cases of refractory inflammatory bowel disease.

AIM

To evaluate the usefulness of low-dose oral tacrolimus in refractory inflammatory bowel disease.

METHODS

Thirty-one adult Caucasian patients with steroid-dependent (n = 15) or steroid-refractory (n = 16) inflammatory bowel disease (Crohn's disease, n = 6; ulcerative colitis, n = 23; pouchitis, n = 2) were enrolled. Tacrolimus (0.1 mg/kg body weight per day) was administered orally in 30 patients and initially intravenously in one patient (0.01 mg/kg body weight per day), aiming for serum trough levels of 4-6 ng/mL. The median treatment duration was 12 months (range, 1-137 months).

RESULTS

Twenty-eight patients (90.3%) experienced a clinical and laboratory response and 20 (64.5%) went into remission. One ulcerative colitis patient and two Crohn's disease patients did not improve. Three ulcerative colitis patients (9.7%) were colectomized at 1, 12 and 24 months after tacrolimus initiation. In 19 of 23 patients (82.6%) taking steroids, steroids were reduced or discontinued. Side-effects included a temporary rise of creatinine (n = 3, 9.7%), tremor or paraesthesias (n = 3, 9.7%), hyperkalaemia (n = 1, 3.2%), hypertension (n = 1, 3.2%) and an opportunistic infection (n = 1, 3.2%).

CONCLUSION

Oral tacrolimus is safe and effective in refractory inflammatory bowel disease.

Helicobacter pylori infection and the risk for open-angle glaucoma

PURPOSE

To determine the frequency of exposure to Helicobacter pylori infection in glaucoma patients.

DESIGN

Prospective case-control study.

PARTICIPANTS

Ninety-seven consecutive patients attending a glaucoma clinic. These included 38 patients with primary open-angle glaucoma (POAG), 19 with normal pressure glaucoma (NPG), 16 with pseudoexfoliation glaucoma (PXE), and 24 with ocular hypertension (OHT). Ninety-four age-matched participants without glaucoma served as a control population.

METHODS

Serum was analyzed for the presence of H. pylori-specific immunoglobulin G antibodies by enzyme-linked immunosorbent assay.

MAIN OUTCOME MEASURES

Serologic analysis for H. pylori.

RESULTS

Seropositivity for H. pylori was higher in patients with glaucoma (26.0%) than in controls (20.2%), but this did not achieve statistical significance (P = 0.46). A total of 26.3% of POAG patients, 26.3% of NPG patients, 25.0% of PXE patients, and 25.0% of OHT patients were seropositive.

CONCLUSIONS

This study suggests that exposure to H. pylori infection is not associated with open-angle glaucoma.

Ulcerative colitis in children: medical management

Ulcerative colitis is a chronic relapsing inflammatory disorder of the colonic mucosa of unknown etiology. The inflammatory process involves the mucosa and submucosa in a continuous segment of bowel with rectal involvement in almost all cases. Since its etiology is unknown, therapy is directed at modulating the inflammatory response in order to control symptoms and to prevent relapses. 5-aminosalicylates and corticosteroids have been the most widely used therapeutic agents for treatment of ulcerative colitis. Recently, experience has been gained with the use of other immunomodulators, such as mercaptopurine, azathioprine, methotrexate, cyclosporine, and tacrolimus, in pediatric patients. Colectomy is indicated in patients with severe colitis who do not respond to intensive medical therapy. The care of children with ulcerative colitis not only involves control of symptoms from gastrointestinal and extraintestinal manifestations, but also optimizing growth and development. The complications of chronic inflammation and long-term medical therapy must be weighed against the risks and benefits of surgery for children and adolescents with this condition.

Alternative immunomodulators

There is now a large number of potential immunomodulatory agents that may be of value in inflammatory bowel disease. The newer immunosuppressants, such as tacrolimus and mycophenolate, probably offer little more than providing comparable alternatives to more established agents, and fish oil and other eicosanoid modulators are probably not especially potent if effective. The biological agents, however, bring a more novel and potentially powerful approach. Natalizumab, and targeted mucosal delivery of interleukin-10 already show considerable promise.

Attenuation of Helicobacter pylori CagA x SHP-2 signaling by interaction between CagA and C-terminal Src kinase

Helicobacter pylori (H. pylori) is a causative agent of gastric diseases ranging from gastritis to cancer. The CagA protein is the product of the cagA gene carried among virulent H. pylori strains and is associated with severe disease outcomes, most notably gastric carcinoma. CagA is injected from the attached H. pylori into gastric epithelial cells and undergoes tyrosine phosphorylation. The phosphorylated CagA binds and activates SHP-2 phosphatase and thereby induces a growth factor-like morphological change termed the "hummingbird phenotype." In this work, we demonstrate that CagA is also capable of interacting with C-terminal Src kinase (Csk). As is the case with SHP-2, Csk selectively binds tyrosine-phosphorylated CagA via its SH2 domain. Upon complex formation, CagA stimulates Csk, which in turn inactivates the Src family of protein-tyrosine kinases. Because Src family kinases are responsible for CagA phosphorylation, an essential prerequisite of CagA.SHP-2 complex formation and subsequent induction of the hummingbird phenotype, our results indicate that CagA-Csk interaction down-regulates CagA.SHP-2 signaling by both competitively inhibiting CagA.SHP-2 complex formation and reducing levels of CagA phosphorylation. We further demonstrate that CagA.SHP-2 signaling eventually induces apoptosis in AGS cells. Our results thus indicate that CagA-Csk interaction prevents excess cell damage caused by deregulated activation of SHP-2. Attenuation of CagA activity by Csk may enable cagA-positive H. pylori to persistently infect the human stomach for decades while avoiding excess CagA toxicity to the host.

Delta 9-tetrahydrocannabinol disrupts mitochondrial function and cell energetics

We have observed rapid and extensive depletion of cellular energy stores by Delta(9)-tetrahydrocannabinol (THC) in the pulmonary transformed cell line A549. ATP levels declined dose dependently with an IC(50) of 7.5 microg/ml of THC after 24-h exposure. Cell death was observed only at concentrations >10 microg/ml. Studies using JC-1, a fluorescent probe for mitochondrial membrane potential, revealed diminished mitochondrial function at THC concentrations as low as 0.5 microg/ml. At concentrations of 2.5 or 10 microg/ml of THC, a decrease in mitochondrial membrane potential was observed as early as 1 h after THC exposure. Mitochondrial function remained diminished for at least 30 h after THC exposure. Flow cytometry studies on cells exposed to particulate smoke extracts indicate that JC-1 red fluorescence was fivefold lower in cells exposed to marijuana smoke extract relative to cells exposed to tobacco smoke extract. Comparison with a variety of mitochondrial inhibitors demonstrates that THC produced effects similar to that of carbonyl cyanide p-trifluoromethoxyphenylhydrazone, suggesting uncoupling of electron transport. Loss of red JC-1 fluorescence by THC was suppressed by cyclosporin A, suggesting mediation by the mitochondrial permeability transition pore. This disruption of mitochondrial function was sustained for at least 24 h after removal of THC by extensive washing. These results suggest that exposure of the bronchopulmonary epithelium to THC may have important health and physiological consequences.

A novel apoptosis-inducing protein from Helicobacter pylori

Helicobacter pylori infection induces apoptosis in gastric epithelial cells. Here, we report a novel apoptosis-inducing protein that functions as a leading factor in H. pylori-mediated apoptosis induction. We purified the protein from H. pylori by separating fractions that showed apoptosis-inducing activity. This protein induced apoptosis of AGS cells in a dose-dependent manner. The purified protein consisted of two protein fragments with molecular masses of about 40 and 22 kDa, which combined to constitute a single complex in their natural form. N-terminal sequencing indicated that both these protein fragments were encoded by the HP1118 gene. The purified protein exhibited gamma-glutamyl transpeptidase activity, the inhibition of which by 6-diazo-5-oxo-l-norleucine resulted in a complete loss of apoptosis-inducing activity. To the best of our knowledge, the apoptosis-inducing function is a newly identified physiological role for bacterial gamma-glutamyl transpeptidase. The apoptosis-inducing activity of the isogenic mutant gamma-glutamyl transpeptidase-deficient strain was significantly lower compared with that of the parent strain, demonstrating that gamma-glutamyl transpeptidase plays a significant role in H. pylori-mediated apoptosis. Our findings provide new insights into H. pylori pathogenicity and reveal a novel aspect of the bacterial gamma-glutamyl transpeptidase function.

Helicobacter pylori induces apoptosis in Barrett's-derived esophageal adenocarcinoma cells

Helicobacter pylori may protect against the development of dysplasia in Barrett's epithelium of patients with gastroesophageal reflux disease. The aim of this study was to determine whether H. pylori preferentially induces apoptosis in Barrett's-derived cancer cells compared to normal cells. A Barrett's-derived adenocarcinoma cell line (OE33) was grown. H. pylori wild-type, isogenic vacA-, cagA(-), and picB-/cagE- mutant strains were grown on agar plates. Intact or sonicated bacteria were used to treat normal and OE33 cells for 24 hours, and Hoechst dye binding was performed to measure apoptosis. FAS protein expression was determined by Western immunoblotting. OE33 cells treated with intact H. pylori wild-type strains produced significant (P < 0.05) dose-dependent increases in apoptosis compared to normal esophageal cells. H. pylori wild-type and vacA- isogenic strains were more effective than cagA- and picB-/cage- isogenic strains in inducing apoptosis in OE33 cells. In OE33 cells, H. pylori sonicates produced lower levels of apoptosis than intact bacteria. Wild-type H. pylori strains increased Fas protein expression in OE33 cells at 18 hours. H. pylori induced apoptosis at a higher rate in the Barrett's-derived human esophageal adenocarcinoma cells than in normal esophageal cells. The H. pylori-induced apoptosis was primarily dependent on intact bacteria and the presence of the cagA and picB/cagE gene products. H. pylori-induced apoptosis may involve the Fas-caspase cascade.

Helicobacter pylori strains expressing the vacuolating cytotoxin interrupt phagosome maturation in macrophages by recruiting and retaining TACO (coronin 1) protein

Recent evidence suggests that persistence of Helicobacter pylori can be explained, at least in part, by the failure of macrophages to kill bacteria. The fate of type 1 H. pylori strain LC11, which expresses the cag pathogenicity island (PAI) and the vacuolating cytotoxin, and type 2 strain LC20, which lacks both these virulence factors, was determined following infection of the murine macrophage cell line RAW 264.7 or the human macrophage-like cell line THP-1. Helicobacter pylori strain LC11 displayed enhanced survival in macrophages in comparison with strain LC20 (4.0 +/- 0.2 versus 2.1 +/- 0.6 log CFU ml-1, P < 0.01) at 24 h. Phagosomes containing strain LC11 showed reduced co-localization with LysoTracker Red, higher levels of expression of the early endosome marker EEA1 expression and lower expression of the late endosome/lysosome marker LAMP1 relative to internalized strain LC20, both at 2 h and 24 h. These findings indicate that, in contrast to strain LC20, strain LC11 resides in a compartment with early endosome properties and does not fuse with lysosomes. In addition, phagosomes containing LC11 recruited and retained a higher percentage of TACO (coronin 1) protein in comparison with phagosomes containing strain LC20. Furthermore, IFN-gamma stimulation facilitated maturation of phagosomes containing strain LC11 in association with the release of TACO and a reduction in bacterial survival. We have demonstrated through the use of isogenic cagA-, cagE-/picB- and vacA- mutant strains, that VacA plays a significant role in the interruption of the phagosome maturation. Taken together, these results indicate that, following phagocytosis, H. pylori strains expressing the vacuolating cytotoxin arrest phagosome maturation in association with the retention of TACO.

Helicobacter pylori infection: pathogenesis

This review covers progress in identifying Helicobacter pylori-derived factors that are involved in survival and virulence of the organism and in elucidating host response pathways that can limit the infection but are also susceptible to dysregulation. Recent work has identified genes of the cytotoxin-associated gene (cag) pathogenicity island (PAI) involved in regulating signaling, interleukin-8 secretion, and phenotypic events in epithelial cells. New roles in pathogenesis have been recognized for vacuolating toxin A (VacA) and urease, H. pylori membrane and secreted factors, and host epithelial surface molecules. Molecular pathways involved in H. pylori-induced apoptosis in epithelial cells, T cells, and macrophages are being dissected. Activation of toll-like receptors and bacterial factors involved in nitric oxide (NO) and reactive oxygen species induction were also described. The ability of H. pylori to limit NO production by several mechanisms may be an important part of its ability to evade the host immune response.

A critical assessment of items on the Pediatric Crohn's Disease Activity Index

OBJECTIVES

Questions have been raised about the discriminative value of the three laboratory items (hematocrit, erythrocyte sedimentation rate, and albumin) and three physical items (height, perirectal disease, and extraintestinal manifestations) included in the Pediatric Crohn's Disease Activity Index (PCDAI). The aim of this study was to analyze the value of these six "criticized" items to the discriminative properties of the PCDAI.

METHODS

Data from 71 children with Crohn's disease visiting an outpatient clinic were analyzed. Physician global assessment of disease activity was used as the gold standard. A "basic index" was calculated by subtracting the score of the six criticized items from the score of the PCDAI calculated in the standard fashion. Multivariate logistic regression procedures identified which items significantly contributed to the "basic index". Receiver operating characteristic curves were produced comparing the standard PCDAI score to the "basic index" and a new "clinical index" which included only the criticized items truly contributing to the discriminatory ability of the "basic index".

RESULTS

Logistic regression models identified only perirectal disease as contributing to the discriminative abilities of the basic index. The clinical index therefore consists of the three history items (abdominal pain, number of liquid stools, and general well-being), three physical examination items (weight loss, abdominal examination, and perirectal disease) and no laboratory tests. The clinical index had an area under the curve not significantly inferior to that of the original PCDAI (0.93 [95% confidence interval, 0.89-0.99] vs. 0.96 [95% confidence interval, 0.92-0.99]).

CONCLUSIONS

A clinical index consisting of three history items and three physical examination items has an accuracy equal to the standard PCDAI in distinguishing children with disease in remission from those with a relapse.

Treatment of inflammatory bowel disease in childhood: best available evidence

The physician treating children with inflammatory bowel disease is confronted with a number of specific problems, one of them being the lack of randomized, controlled drug trials in children. In this review, the role of nutritional therapy is discussed with a focus on primary treatment, especially for children with Crohn's disease. Then, the available medical therapies are highlighted, reviewing the evidence of effectiveness and side effects in children, as compared with what is known in adults. Nutritional therapy has proven to be effective in inducing and maintaining remission in Crohn's disease while promoting linear growth. Conventional treatment consists of aminosalicylates and corticosteroids, whereas the early introduction of immunosuppressives (such as azathioprine or 6-mercaptopurine) is advocated as maintenance treatment. If these drugs are not tolerated or are ineffective, methotrexate may serve as an alternative in Crohn's disease. Cyclosporine is an effective rescue therapy in severe ulcerative colitis, but only will postpone surgery. A novel strategy to treat Crohn's disease is offered by infliximab, a monoclonal antibody to the proinflammatory cytokine tumor necrosis factor (TNF)-alpha. Based on the best-available evidence, suggested usage is provided for separate drugs with respect to dosage and monitoring of side effects in children.

Evolving medical therapies for ulcerative colitis

Therapies for patients with ulcerative colitis have, until recently, been limited in scope and efficacy. New formulations of mesalamine and corticosteroids have challenged the older therapies with respect to both efficacy and safety. The application of 6-mercaptopurine and azathioprine for steroid-refractory disease and maintenance of remission has resulted in studies of other candidate immunomodulatory agents. Biologic therapies targeting tumor necrosis factor, adhesion molecules, or other cytokines are under intense scrutiny as potential disease-altering agents that may even replace currently available products. Other approaches, including such wide-ranging products as heparin, nicotine, and probiotics, suggest that control of ulcerative colitis may require an individualized approach for each patient.

Helicobacter pylori genotypes in Israeli children: the significance of geography

BACKGROUND

There is substantial genetic variation among different isolates of Helicobacter pylori, which may affect the clinical outcome. The aims of this study were to find the common H. pylori genotypes in Israeli children and to look for a possible genotype-phenotype correlation.

METHODS

Ninety-eight H. pylori cultures were isolated from antral biopsy specimens of symptomatic Israeli children and were analyzed for vacA and iceA genotype and cagA and cagE status by polymerase chain reaction.

RESULTS

cagA and cagE genes were present in only 25.5% and 24.5%, respectively. The common vacA genotype was s2m2, which was found in 65%. Eleven specimens (11%) contained multiple vacA genotypes. iceA1 was found in 37% and iceA2 in 52% of cases. Both iceA alleles were found in 11%. Increased prevalence of iceA1 and cagE were observed in children with duodenal disease, although it did not reach significance.

CONCLUSIONS

The low prevalence of cagA and the high prevalence of vacA genotype s2m2 in Israeli pediatric patients are different from the genotype prevalence reported globally. However, similar findings have been reported in Egypt, indicating a possible geographic influence. There is a possible correlation between duodenal ulcer and cag E and ice A1 genotype, but the power of the study was too low to prove it.

Helicobacter pylori organisms induce expression of activation and apoptotic surface markers on human lymphocytes and AGS cells: a cytofluorimetric evaluation

Human peripheral blood mononuclear cells (PBMCs) were treated with Helicobacter pylori (Hp) organisms alone or with Hp-stimulated AGS cells (a gastric adenocarcinoma cell line). Hp organisms were able per se to increase the percentage of CD8 +/- CD95 +/- cells, while number of CD25+ cells and HLA-DR molecule expression increased following pretreatment with Hp-stimulated AGS cells. A comparison was made with a test system in which PBMCs were stimulated with Escherichia coli (Ec) organisms and colo-cells (a colon carcinoma cell line). In this case, CD95+ cells and CD25+ cells increased when the combination Ec organisms/colo-cells was present in the culture. On the other hand, Hp bacteria in combination with colo-cells were not able to induce activation and/or apoptotic surface markers on PBMCs, while Ec-stimulated AGS cells increased the expression of CD95 on PBMC. Finally, the direct interaction of AGS cells with Hp was able to induce higher expression of CD95 on gastric epithelial cells than Hp-stimulated PBMCs. Taken together, these data support the interplay between bacteria and epithelial cells in the course of Hp-mediated gastropathy.

Analysis of apoptotic and antiapoptotic signalling pathways induced by Helicobacter pylori

BACKGROUND AND AIMS

Although it is reported that Helicobacter pylori induces apoptosis on gastric epithelial cells, the mechanism remains unknown. Antiapoptotic effects generated by H pylori have not yet been evaluated.

METHODS

(1) H pylori strains (type 1 wild, TN2-deltacagE, TN2-deltavacA) were cocultured with MKN45, TMK1, and HeLa cells, and cell viability and apoptosis were assessed by trypan blue exclusion and DNA laddering, respectively. (2) Activation of caspases-3, 7, and 8, cytochrome c release from the mitochondria, and Fas, Fas associated death domain protein (FADD), Bax, Bak, and Bcl-X expression were evaluated by immunoblot analysis. (3) To investigate whether nuclear factor kappa B (NFkappaB) activation induced by cag pathogenicity island (PAI) positive H pylori affects antiapoptosis, MKN45 cells stably expressing super-repressor IkappaBalpha were cocultured with H pylori, and cell viability and caspase activation were evaluated. NFkappaB regulated gene expression was also evaluated by ribonuclease protection assay.

RESULTS

(1) Wild-type and deltavacA mutant H pylori induced apoptosis more potently than the deltacagE mutant. Inhibition of cell contact between H pylori and cancer cells and heat killing H pylori diminished cell death. (2) Caspases-3, 7, and 8 were activated time dependently by H pylori as well as by the agonist anti-Fas. Cytochrome c release from mitochondria was observed and was not inhibited by caspase-8 inhibitor. Although protein expression of Fas, FADD, Bax, Bak, and Bcl-X in the whole cell lysates was not changed by H pylori, Bax was decreased from mitochondria free cytosol suggesting that Bax was translocated into mitochondria. (3) Cell death and the activities of caspases-3 and 8 were promoted in MKN45 cells stably expressing super-repressor IkappaBalpha that inhibits NFkappaB activation. Antiapoptotic proteins c-IAP1 and c-IAP2 were upregulated by the wild-type strains.

CONCLUSION

cag PAI positive H pylori is capable of inducing apoptotic effects mainly through the mitochondrial pathway. Antiapoptotic effects mediated by NFkappaB activation were also observed.

Response of refractory colitis to intravenous or oral tacrolimus (FK506)

Intravenous cyclosporine has proven to be an alternative to emergency colectomy in steroid-refractory ulcerative colitis, whereas the experience with FK506 is limited. In this report we compare intravenous to oral FK506 treatment in 38 patients with refractory ulcerative (n = 33) or indeterminate (n = 5) colitis. FK506 was started intravenously in the first group (n = 18) at a dose of 0.01 to 0.02 mg/kg up to 14 days, followed by 0.1 to 0.2 mg/kg orally, or was started orally at this dose in a second group (n = 20). Additional azathioprine/6-mercaptopurine was given and steroids were tapered in responding patients, followed by a dose reduction of FK506. Clinical disease activity and laboratory parameters were assessed to evaluate efficacy and safety. Primary objectives were the induction of remission (Truelove index of mild) and colectomy-free survival. Treatment lasted for a mean of 7.6 months, and the mean observation period was 16.2 months. Eighteen of 38 patients improved within 14 days, and a complete remission was achieved in 13 patients after 1 month. A colectomy within 1 month was performed in 3 of 38 patients. The overall colectomy rate was 34%. One-half of the patients with a minimum follow-up of 2 years required a colectomy. Intravenous and per oral administration were equally safe and effective. The most frequent adverse events included tremor, hyperglycemia, hypertension, and infection, but none were severe. Renal impairment was rare and subsided upon drug withdrawal. In conclusion. FK506 is effective in the treatment of refractory colitis with per oral dosing being equivalent to intravenous administration.

Clinical presentation in relation to diversity within the Helicobacter pylori cag pathogenicity island

OBJECTIVE

This study investigated the genetic diversity of the cag pathogenicity island (PAI) in Helicobacter pylori (H. pylori) in relation to clinical outcome and interleukin (IL)-8 production.

METHODS

Seven genes in the cag PAI (cagA, cagE, cagG, cagM, cagT, open reading frame 13 and 10) were examined by polymerase chain reaction and Southern blot hybridization using H. pylori from 120 patients with different presentations (duodenal ulcer, gastric cancer, gastritis alone). IL-8 production from AGS cells (gastric cancer cell line) cocultured with H. pylori was measured by ELISA.

RESULTS

An intact cag PAI was present in 104 (87%) isolates, and five (4%) had deletions within the cag PAI; 11 (9%) lacked the entire cag PAI. Clinical isolates containing the complete cag PAI induced a greater secretion of IL-8 as compared with those without the cag PAI (3048 +/- 263 vs 480 +/- 28 pg/ml, p < 0.001). Deletion of only cagG reduced IL-8 secretion by two thirds. Deletions of more than one locus reduced IL-8 secretion to background. A similar proportion of H. pylori from patients with gastritis, duodenal ulcer, or gastric cancer had intact cag PAI (88%, 88%, and 85%, respectively). Although the presence of cagG was a better predictor of the presence of an intact cag PAI than cagA or cagE, the presence or absence of any of these genes had no association with clinical presentation.

CONCLUSION

Although the cag PAI plays an important role in IL-8 production, clinical presentation cannot be predicted by the presence of an intact cag PAI or any of these seven cag PAI genes.

Impact of Helicobacter pylori and nonsteroidal anti-inflammatory drugs on gastric ulcerogenesis in experimental animals and in humans

Helicobacter pylori (H. pylori) and nonsteroidal anti-inflammatory drugs (NSAID) are the most common pathogens in the gastroduodenal mucosa in animals and humans, but their relationship in ulcerogenesis has been little studied. According to some authors, H. pylori infection in humans does not act synergistically with NSAID on ulcer healing, therefore, there is no need to eradicate the germ. This notion is supported by the finding that the eradication of H. pylori does not affect NSAID-induced gastropathy treated with omeprazole and that H. pylori infection induces a strong cyclooxygenase-2 expression resulting in excessive biosynthesis of gastroprotective prostaglandins, which should in turn counteract NSAID-induced gastropathy and heal the existing ulcer. Other investigators claim that H. pylori infection acts synergistically with NSAID on ulcer development, therefore, H. pylori should be eradicated, particularly at the start of long-term NSAID therapy. Maastricht 2-2000 consensus also recommends eradication prior to NSAID treatment, but this eradication does not appear to accelerate ulcer healing or to prevent the recurrent ulcers in NSAID users. Our studies in almost 6,000 dyspeptic patients undergoing upper endoscopy and [(13)C]-urea breath test (UBT) revealed that about 70% of these patients are H. pylori (+) and about 30.6% of these develop gastroduodenal ulcers. Of these ulcers, over 70% were H. pylori (+) positive, 12% NSAID (+), 8% were both H. pylori (+) and NSAID (+), while 22% ulcers were H. pylori (-) and NSAID (-) or "idiopathic" ulcers. Basically, our results support Hawkey's concept and this also agrees with our findings in the rat model showing that: (1) there is no synergistic interaction between H. pylori infection and NSAID on gastric ulcer development, (2) H. pylori and NSAID are independent risk factors for peptic ulceration, and (3) NSAID therapy in H. pylori positive patients attenuates the ulcer development possibly due to direct inhibitory action of these drugs on H. pylori.

Therapy of Crohn's disease in childhood

Crohn's disease in childhood is a chronic relapsing and remitting condition that can significantly impact on normal growth and development. This influences the choice of both initial and ongoing management. The goal of therapy is to induce and maintain remission with minimal side effects. Enteral nutrition as the sole therapy for active disease is effective in some children, thus avoiding the use of corticosteroids. In disease that is resistant to conventional treatment, immunosuppression or anti-tumour necrosis factor therapy is indicated. We review the use of these treatments and discuss the new therapies being developed, including antibodies, cytokines and probiotics.

Role of Helicobacter pylori in gastric carcinogenesis

Peptic ulcers and gastric malignancies are the two major complication of the course of Helicobacter pylori-associated chronic gastritis. Both gastric adenocarcinomas and MALT lymphomas occur in association with H. pylori infection, and studies support an etiological association. This article discusses the natural history of H. pylori-related gastric carcinogenesis and criteria to identify people susceptible to H. pylori infection-associated gastric cancer. It then reviews the molecular and genetic mechanisms underlying the malignant transformation of the gastric mucosa associated with H. pylori.

Roles of tumor necrosis factor-alpha-receptor type 1 and Fas in the Helicobacter pylori-induced apoptosis of gastric epithelial cells

OBJECTIVES

Helicobacter pylori (HP) infection has been reported to accelerate the apoptosis of gastric epithelial cells. This bacteria has also been known to enhance the expression levels of molecules such as Fas antigen and a receptor for tumor necrosis factor-alpha-receptor type 1 (TNF-R1). However, whether Fas and/or TNF-R1 is actually involved in HP-mediated apoptosis has yet to be evaluated. The purpose of this study was therefore to examine the roles of Fas and TNF-R1 in HP-mediated apoptosis.

METHODS

Biopsy samples were collected from 10 HP-negative healthy volunteers and from 39 HP-positive ulcer patients. Gastric epithelial cells were obtained from the samples. The cells were then stained with anti-Fas, anti-TNF-R1 and Annexin V, which detected apoptotic cells. The findings were analyzed by three-color flow cytometry.

RESULTS

The percentages of apoptotic cells were significantly higher in HP-positive patients than in the controls. In HP-negative controls, almost all of the apoptotic cells lacked both Fas and TNF-R1. On the other hand, in HP-positive patients, HP upregulated the expression levels of Fas and TNF-R1 and, consequently, enhanced the apoptosis mediated by receptors such as Fas and TNF-R1. However, even in HP-positive patients, apoptosis was also observed in the cells that lacked both Fas and TNF-R1.

CONCLUSIONS

Fas and TNF-R1 expressed on gastric epithelial cells from HP-infected patients were responsible for the accelerated apoptosis of the cells.

Role of gamma interferon in Helicobacter pylori induction of inflammatory mediators during murine infection

Gamma interferon (IFN-gamma) has been proposed to play an important role in Helicobacter-related gastritis. Using the IFN-gamma gene knockout (IFN-gamma(-/-)) mouse model and a murine gastric epithelial cell line, GSM06, we demonstrated that Helicobacter pylori maximally induced macrophage inflammatory protein-2 (MIP-2) and inducible nitric oxide synthase (iNOS) mRNA only in wild-type mice. MIP-2 and iNOS mRNA were also induced by H. pylori in GSM06 cells. Induction of cyclooxygenase 2 mRNA through IFN-gamma was demonstrated in GSM06 cells. These data indicate that IFN-gamma mediates the induction of MIP-2 and iNOS mRNA expression by H. pylori in mice.

Inflammatory Bowel Disease in Children

Crohn's disease and ulcerative colitis remain medically incurable conditions with potentially significant morbidity. The treatment of children with these conditions therefore should seek to reduce or eliminate symptoms, optimize nutritional status, promote normal growth and development, prevent complications, and minimize the potential psychologic effects of chronic illness. Treatment strategies must seek to both induce and maintain clinical remission. For all but the most mildly affected children with Crohn's disease, a combination of nutritional and pharmacologic approaches is optimal. For those with ulcerative colitis, anti-inflammatory medication is necessary. Moderate to severe Crohn's disease acutely responds best to potent immunomodulatory therapy, eg, corticosteroids and infliximab. Either agent must be coupled with 6-mercaptopurine or azathioprine to maintain long-term remission and to minimize toxicity. Particular attention must be paid to limit the growth suppression and other toxic effects of corticosteroids. Elemental or semielemental enteral nutrition also can induce remission effectively, but relapse is common after primary nutritional therapy is discontinued, mandating concomitant pharmacologic therapy with either 6-mercaptopurine or azathioprine. The availability of 6-mercaptopurine/azathioprine metabolite testing allows optimization of immunomodulatory therapy, detection of noncompliance, and avoidance of potentially dangerous toxicity. Mild ulcerative colitis acutely responds to treatment with a 5-aminosalicylate medication. Long-term remission frequently can be maintained with the same medication. Moderate to severe disease activity requires potent immunomodulatory therapy if colectomy is to be avoided. Surgery is a potential cure for patients with ulcerative colitis, although the development of pouchitis after ileal pouch anal anastomosis is common and frequently requires long-term medical management. Surgery provides only palliative relief of complications in those with Crohn's disease. Emerging therapies, especially evolving biologic and probiotic agents, offer hope for better treatments in the years ahead.

Analysis of apoptotic and antiapoptotic signalling pathways induced by Helicobacter pylori

BACKGROUND AND AIMS

Although it is reported that Helicobacter pylori induces apoptosis on gastric epithelial cells, the mechanism remains unknown. Antiapoptotic effects generated by H pylori have not yet been evaluated.

METHODS

(1) H pylori strains (type 1 wild, TN2-DeltacagE, TN2-DeltavacA) were cocultured with MKN45, TMK1, and HeLa cells, and cell viability and apoptosis were assessed by trypan blue exclusion and DNA laddering, respectively. (2) Activation of caspases-3, 7, and 8, cytochrome c release from the mitochondria, and Fas, Fas associated death domain protein (FADD), Bax, Bak, and Bcl-X expression were evaluated by immunoblot analysis. (3) To investigate whether nuclear factor kappa B (NFkappaB) activation induced by cag pathogenicity island (PAI) positive H pylori affects antiapoptosis, MKN45 cells stably expressing super-repressor Ikappabetaalpha were cocultured with H pylori, and cell viability and caspase activation were evaluated. NFkappaB regulated gene expression was also evaluated by ribonuclease protection assay.

RESULTS

(1) Wild-type and DeltavacA mutant H pylori induced apoptosis more potently than the DeltacagE mutant. Inhibition of cell contact between H pylori and cancer cells and heat killing H pylori diminished cell death. (2) Caspases-3, 7, and 8 were activated time dependently by H pylori as well as by the agonist anti-Fas. Cytochrome c release from mitochondria was observed and was not inhibited by caspase-8 inhibitor. Although protein expression of Fas, FADD, Bax, Bak, and Bcl-X in the whole cell lysates was not changed by H pylori, Bax was decreased from mitochondria free cytosol suggesting that Bax was translocated into mitochondria. (3) Cell death and the activities of caspases-3 and 8 were promoted in MKN45 cells stably expressing super-repressor Ikappabetaalpha that inhibits NFkappaB activation. Antiapoptotic proteins c-IAP1 and c-IAP2 were upregulated by the wild-type strains.

CONCLUSION

cag PAI positive H pylori is capable of inducing apoptotic effects mainly through the mitochondrial pathway. Antiapoptotic effects mediated by NFkappaB activation were also observed.

Enhanced expression of transcription factor E2F in Helicobacter pylori-infected gastric mucosa

OBJECTIVE

Helicobacter pylori is implicated in gastric carcinogenesis through increased gastric epithelial cell turnover. In fact, high proportions of proliferating and apoptotic epithelial cells are found in H. pylori-infected gastric mucosa. E2F, a transcription factor, induces coordinated transactivation of a set of genes involved in cell cycle progression. The aim of this study was to investigate the expression of E2F in H. pylori-infected gastric mucosa and examine the correlation between such expression and gastric epithelial cell proliferation and apoptosis.

METHODS

Twenty-five patients with H. pylori-associated gastritis (HAG) and 13 control subjects negative for H. pylori were examined. E2F expression was studied in situ by Southwestern histochemistry, a method used to localize transcription factors. Labeled double-stranded oligo-DNA with specific consensus sequence for E2F binding sites was reacted with frozen sections from antral biopsy specimens obtained at endoscopy. Gastric epithelial cell proliferation was assessed by immunostaining of proliferating cell nuclear antigen (PCNA), while apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The percentages of epithelial cells with nuclear staining for PCNA and E2F were expressed as a positivity index (PI). The percentage of TUNEL-positive epithelial cells was defined as apoptotic index.

RESULTS

E2F was expressed in the nuclei of gastric epithelial cells within gastric pits. E2F PI in H. pylori-infected gastric mucosa was significantly higher than that in noninfected. Expression of E2F correlated well with PCNA-positive epithelial cells. We also demonstrated colocalization of PCNA with E2F expression in the same epithelial cells. Apoptotic index was also high in H. pylori-infected mucosa, and correlated with E2F PI.

CONCLUSION

Our results demonstrated a significant increase in the expression of E2F in H. pylori-infected mucosa, which correlated with both the percentages of PCNA- and TUNEL-positive cells. Our results suggest that enhanced E2F expression in gastric mucosa may be involved in H. pylori-related gastric carcinogenesis through accelerated cell turnover.

Enhanced disease severity in Helicobacter pylori-infected mice deficient in Fas signaling

Recent evidence suggests that immune-mediated gastric epithelial cell apoptosis through Fas-Fas ligand interactions participates in Helicobacter pylori disease pathogenesis. To define the role of Fas signaling in vivo, H. pylori strain SS1 infection in C57BL/6 mice was compared to that in mice deficient in the Fas ligand (gld). gld mice had a degree of gastritis similar to that of C57BL/6 mice after 6 weeks (gastritis score, 5.2 +/- 0.6 [mean +/- standard error] versus 3.5 +/- 0.8) and 12 weeks (4.0 +/- 0.7 versus 3.4 +/- 0.5) of infection. Bacterial colonization was comparable in each group of mice at 12 weeks of infection (2.1 +/- 0.3 versus 1.6 +/- 0.3 for gld and C57BL/6, respectively; the difference is not significant). Sixty-seven percent of H. pylori-infected gld mice displayed atrophic changes in the gastric mucosa, compared with 37% of infected C57BL/6 mice, at 12 weeks. In addition, atrophic changes were more severe in H. pylori-infected gld mice (P < 0.05). Splenocytes isolated from H. pylori-infected C57BL/6 mice had a twofold increase in production of the Th1 cytokine gamma interferon (IFN-gamma) in response to H. pylori antigens at both 6 and 12 weeks compared to controls (143 +/- 65 versus 69 +/-26 pg/ml and 336 +/- 73 versus 172 +/- 60, respectively). In contrast, there was a lack of detectable IFN-gamma in gld mice infected with the bacterium. H. pylori-infected C57BL/6 mice had increased epithelial cell apoptosis compared with sham-infected C57BL/6 mice (35.0 +/- 8.9 versus 12.3 +/- 6.9; P < 0.05). Epithelial cell apoptosis did not differ between H. pylori-infected and control gld mice (5.2 +/- 1.6 versus 6.5 +/- 2.9 [not significant]). These data demonstrate that mice with mutations in the Fas ligand develop more severe premalignant mucosal changes in response to infection with H. pylori in association with both an impaired gastric epithelial cell apoptotic response and IFN-gamma production. The Fas death pathway modulates disease pathophysiology following murine infection with H. pylori. Deregulation of the Fas pathway could be involved in the transition from gastritis to gastric cancers during H. pylori infection.

Helicobacter pylori strain-specific modulation of gastric mucosal cellular turnover: implications for carcinogenesis

Helicobacter pylori colonization induces inflammation in essentially all hosts, a persistent process that increases the risk of developing distal gastric adenocarcinoma. However, only a small percentage of persons carrying H. pylori develop neoplasia; enhanced risk may be related to differences in expression of specific bacterial products, differences in the host response to the bacteria, or the interaction between host and microbe. H. pylori strains that have the cag pathogenicity island are associated with further increased risk for developing distal gastric cancer; however, host responses to H. pylori, such as altered epithelial cell proliferation and apoptosis, also may be important in lowering the threshold for carcinogenesis. H. pylori cag+ strains selectively enhance proliferation and attenuate apoptosis in human mucosa compared to cag- strains. However, cag+ strains also induce more severe gastritis, suggesting that host inflammatory mediators such as cytokines, prostaglandins, and hormones may modulate H. pylori-induced alterations in cellular turnover. In the Mongolian gerbil model of gastric carcinogenesis, apoptosis increases early and transiently following H. pylori infection, but scores progressively decline despite worsening gastric inflammation. Epithelial cell proliferation peaks later and is significantly related to increased gastrin levels, suggesting that epithelial cell growth in H. pylori-colonized mucosa may be mediated by gastrin-dependent mechanisms. An emerging model invoked by these data is one in which H. pylori cag+ strains, in conjunction with host mediators, enhance gastric epithelial cell proliferation but not apoptosis in vivo. The combination of increased proliferation without a concordant increase in apoptosis may therefore contribute to the heightened retention of mutagenized cells, which over decades may increase the subsequent risk for gastric cancer.