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Background: Helicobacter pylori infection induces a biased T helper type 1 (Th1) response that produces IFN-gamma and Fas ligand (FasL). Th1 cytokines are associated with apoptosis in the gastric epithelial cells., Aim: We aimed to define the role of the recently cloned IL-18, a IFN-gamma inducing factor, in gastric mucosal injury induced by H. pylori infection., Methods: Twenty-seven gastric ulcer (GU) patients and 20 functional dyspepsia (FD) patients were enrolled in this study. Mucosal biopsy samples were obtained from the gastric antrum and GU site during endoscopy. Samples were used for histological examination, H. pylori culture and in-situ stimulation for 48 h in the presence of 10 microg/ml phytohemagglutinin-P. IL-18, IFN-gamma, and soluble FasL (sFasL) levels in culture supernatants were assayed by the enzyme-linked immunosorbent assay method. IL-18, IL-1beta-converting enzyme (ICE) and caspase-3 were evaluated by western blotting in gastric cancer cell lines (MKN45) cocultured with H. pylori., Results: All 27 GU patients and ten out of 20 FD patients were found to be H. pylori-positive, whereas ten FD patients were H. pylori-negative. Antral mucosal tissues from H. pylori-positive FD patients contained (P<0.01) higher levels of IL-18, IFN-gamma, and sFasL than those from uninfected FD patients. IL-18, IFN-gamma, and sFasL levels at the ulcer site were significantly (P<0.01) higher than those at distant sites in the antrum. A significant relationship was seen between IL-18 and IFN-gamma levels at the ulcer site (r=0.7, P<0.01). H. pylori eradication led to a significant decrease in the levels of IL-18, IFN-gamma, and sFasL at the ulcer site. Western blotting showed that IL-18, ICE, and caspase-3 were activated in gastric cancer cell lines cocultured with H. pylori., Conclusion: This study suggests that H. pylori infection enhanced mucosal injury by stimulating a Th1 response, which was mediated by IL-18 upregulation as well as activation of ICE and caspase-3.

Aim: To determine the role of interleukin (IL)-17 in gastric ulcerogenesis., Methods: Thirty-six gastric ulcer (GU) patients and 29 non-ulcer (NU) patients were enrolled in this study. Mucosal biopsy samples were obtained from the gastric antrum and GU site during endoscopy. Samples were used in in situ stimulation for 48 h in the presence of 10 microg/mL phytohemagglutinin-P (PHA), histological examination, and Helicobacter pylori (H pylori) culture. IL-17 and IL-8 protein levels in culture supernatants were assayed by ELISA. IL-17 mRNA expression was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). H pylori cagA and vacA status was assessed by reverse hybridization using a line probe assay (LiPA). IL-8 levels in culture supernatants were assayed after AGS cells were co-cultured with H pylori strain 26,695 or recombinant human (rh) IL-17., Results: All 36 GU patients and 15 of 29 NU patients were found to be H pylori-positive, while 14 NU patients were H pylori-negative. All 51 H pylori strains from both GU and NU patients were cagA- and vacAs1/m1-positive. Antral mucosal tissues from H pylori-positive patients contained significantly (H pylori-positive NU patients: median 467 pg/mg/protein, range 53-2,499; H pylori-negative NU patients: median 104 pg/mg/protein, range 16-312, P< 0.0005) higher levels of IL-17 than those from uninfected patients. IL-17 levels at the ulcer site were significantly (ulcer site: median 1,356 pg/mg/protein, range 121-1,3730; antrum: median 761 pg/mg/protein, range 24-7,620, P< 0.005) higher than those at distant sites in the antrum. Biopsies from H pylori-positive GU and NU patients showed IL-17 mRNA expression in all samples whereas those from the antrum of the H pylori-negative controls showed no detectable expression. A significant correlation was seen between IL-17 and IL-8 levels at each biopsy site (ulcer: r = 0.62, P< 0.0001; antrum: r = 0.61, P< 0.0001) in GU patients. RhIL-17 and H pylori strain 26,695 each stimulated IL-8 production from AGS cells., Conclusion: IL-17 may play an important role in the inflammatory response to H pylori colonization, and may ultimately influence the outcome of H pylori-associated diseases that arise within the context of gastritis.

Background: The long-term benefit of Helicobacter pylori eradication treatment that includes metronidazole on peptic ulcer disease in Japan is unclear. We investigated the rate of H. pylori re-infection and ulcer relapse after H. pylori eradication., Materials and Methods: A total of 266 patients with endoscopically confirmed peptic ulcer disease and H. pylori infection were treated with triple therapy of omeprazole 40 mg (20 mg b.i.d.), clarithromycin 800 mg (400 mg b.i.d.), and tinidazole 1000 mg (500 mg b.i.d.) for 7 days. Endoscopy with gastric biopsy was performed before and 1 month, 6 months, 1.5 years, and 3.5 years after therapy. H. pylori status was determined by H. pylori culture, rapid urease test, and histopathology. 13C-urea breath test was done at 6 months after eradication therapy. Treatment was deemed successful when all tests were negative at 6 months after therapy by endoscopic biopsy., Results: Successful H. pylori eradication was achieved in 262/266 (98.5%) patients with peptic ulcer. Total relapse of peptic ulcer occurred in 8/262 (3%) patients after eradication, with 3/262 (1.1%) occurring within 1.5 years after treatment and 5/262 (1.9%) within 3.5 years. All relapsed patients were found to be H. pylori-positive at the time of relapse. Of the 262 patients who experienced eradication, 20 (7.6%) were subsequently re-infected, six (2.3%) within 1.5 years and 14 (5.3%) within 3.5 years., Conclusion: Triple therapy with omeprazole, clarithromycin, and tinidazole (OCT) is useful for H. pylori eradication in Japan, but there is an appreciable re-infection rate in this population.

Background: The association between Helicobacter pylori infection and idiopathic thrombocytopenic purpura (ITP) has been reported widely. We investigated the prevalence of H. pylori infection, its virulence profile and the effectiveness of its eradication in patients with ITP., Materials and Methods: Twenty patients with ITP, 20 with peptic ulcer (10 gastric ulcer (GU), 10 duodenal ulcer (DU)) and 20 with NUD were studied. The virulence profile of the strains was assessed by genotyping for cagA, vacA, iceA, and hpyIIIR/hrgA and by assaying for IL-8 and DNA fragmentation after incubation with AGS cells. Infected patients and two uninfected ITP patients received triple therapy and platelets were counted before and 1 month, 6 months, 1 year, and 2 years after eradication therapy., Results: H. pylori infection was found in 17 ITP (85%), 20 ulcer (100%) and 13 NUD (65%) patients. Biopsies and strains were collected from five ITP, 20 ulcer and 13 NUD patients. The ITP patients had a pangastritis or corpus-predominant gastritis pattern. All H. pylori isolates, from ITP, ulcer and NUD patients, were cagA(+) and vacA s1/m1, and did not differ in levels of IL-8 induction or DNA fragmentation. Fifteen ITP (88%) and 17 ulcer (85%) patients had successful eradication of H. pylori. Ten of these 15 (67%) H. pylori-eradicated ITP patients had platelet recovery. There was no significant change in platelet count in the two ITP patients in whom eradication failed or in the two originally H. pylori-uninfected ITP patients, or in the treated ulcer patients. Age at onset of ITP was the main determinant of platelet recovery: 100% of patients diagnosed after the age of 60 recovered compared with only 22% of those diagnosed before 50., Conclusions: H. pylori-infected ITP patients have a corpus-predominant pattern of gastritis but the virulence profile of their strains does not differ from that of ulcer or NUD patients. Eradication of H. pylori infection is a good therapeutic option for some patients with chronic ITP, especially for those who develop ITP in older age.

Glycine is the simplest amino acid and is used as a metabolic product in some bacteria. However, an excess of glycine inhibits the growth of many bacteria, and it is used as a nonspecific antiseptic agent due to its low level of toxicity in animals. The effect of glycine on Helicobacter pylori is not precisely known. The present study was conducted to investigate (i) the effect of glycine on clarithromycin (CLR)-resistant and -susceptible strains of H. pylori, (ii) the effect of glycine in combination with amoxicillin (AMX), and (iii) the postantibiotic effect (PAE). The MIC at which 90% of strains are inhibited for glycine was almost 2.5 mg/ml for 31 strains of H. pylori, including CLR-resistant strains. We constructed isogenic CLR-resistant mutant strains by natural transformation and investigated the difference between clinical wild-type strains and isogenic mutants. There were no differences in the MICs between CLR-resistant and -susceptible strains or between clinical wild-type and mutant strains. The combination of AMX and glycine showed synergistic activity, with the minimum bactericidal concentration of AMX with glycine decreasing to 1/10 that of AMX alone. Glycine showed no PAE against H. pylori. These results suggest that glycine may be a useful antimicrobial agent against H. pylori not only alone but also in combination with antibacterial drugs for the treatment of H. pylori-associated diseases. Glycine may represent a component of a new type of eradication therapy for CLR-resistant H. pylori.

Background: Failure of Helicobacter pylori eradication occurs frequently despite use of multiple microbial agents., Aim: We aimed to study differences between H. pylori strains isolated before and after eradication failure., Methods: We treated 87 patients with peptic ulcer using triple therapy consisting of omeprazole plus combinations of clarithromycin, amoxicillin, or metronidazole. We studied the status of cagA, vacA, and iceA by PCR, and examined the differences in H. pylori isolates by pulsed-field gel electrophoresis and arbitrary primer polymerase chain reaction. The minimum inhibitory concentration of clarithromycin, amoxicillin, or metronidazole was determined by an agar dilution method., Results: Eradication therapy failed in 12 patients (14%); H. pylori isolates were obtained from all of these both before and after therapy. After eradication therapy, 10 patients were colonized with the same strain as before therapy, while the other two patients were colonized with different strains from those before therapy. In the former group, one isolate changed from metronidazole-sensitive to -resistant, one changed from clarithromycin- and metronidazole-sensitive to -resistant, and four were resistant to clarithromycin or metronidazole both before and after therapy. The other four isolates remained sensitive to clarithromycin and metronidazole after therapy. In the two patients who yielded apparently different isolates after therapy, they changed from clarithromycin- and metronidazole-sensitive to -resistant., Conclusion: Eradication of H. pylori by first-line therapy is an important goal in the treatment of H. pylori-positive peptic ulcer, and that appropriate antimicrobial sensitivity testing should be conducted in patients with eradication failure.

Background: Little information is currently available on the contribution of locally generated inflammatory and chemotactic cytokines to endothelial cell activation and subsequent neutrophil transendothelial migration in patients with Helicobacter pylori (H. pylori)-associated gastritis., Methods: The contents of interleukin (IL)-1beta and IL-8 in the organ culture supernatants of antral mucosal tissues were measured with an enzyme-linked immunosorbent assay. The effects of the endogenous IL-1beta and IL-8 in mucosal tissues on neutrophil adherence and transendothelial migration were investigated using an experimental model of human umbilical vein endothelial cells (HUVEC)., Results: The contents of IL-1beta and IL-8 in organ cultures of antral mucosal tissues were significantly higher in patients with H. pylori infection than in those without infection. The organ culture supernatants from H. pylori-positive patients induced the expression of intercellular adhesion molecule-1 mRNA in HUVEC with increased binding of neutrophils, and these stimulatory effects were inhibited when HUVEC were pretreated with a nuclear factor-kappaB inhibitor, MG-132. Moreover, neutrophil adherence to HUVEC induced by the supernatants decreased after preincubation with neutralizing anti-IL-1beta antibody. As compared with the supernatants from H. pylori-negative patients, the samples from H. pylori-positive patients exhibited a significantly higher chemotactic activity for neutrophils, which was inhibited almost completely by preincubation of the supernatants with anti-IL-8 antibody., Conclusions: Locally generated IL-1beta and IL-8 could coordinate with each other during the process of neutrophil infiltration into the gastric mucosa in patients with H. pylori infection.

Background: Little information is available on the precise mechanisms leading to the development of acute gastric mucosal lesions (AGMLs). We investigated whether the pathologic mechanism of AGMLs resulting in damage to epithelial cells is associated with cytotoxic molecules expressed by activated intraepithelial lymphocytes (IELs)., Methods: The expression of the lymphocyte markers, CD3, CD4, CD8, CD20, T-cell-restricted intracellular antigen (TIA)-1, and granzyme B (GrB)-7 in IELs and that of single-stranded DNA (ssDNA) in apoptotic epithelial cells were evaluated by immunohistochemistry, using endoscopic biopsy specimens from 20 patients with AGMLs and 20 controls., Results: The number of CD3- and CD8-positive IELs increased in AGML specimens when compared with controls, and this increase was accompanied by a concomitant increase in TIA-1-positive cells. The epithelial cell layers of AGML specimens contained more GrB-7-positive phenotypically activated cytotoxic T cells than those in controls. Apoptotic ssDNA-positive epithelial cells were detected more frequently in AGML specimens than in controls, a feature which was paralleled by an increase in GrB-7-positive IELs in the former group of specimens., Conclusions: The present study showed that activated cytotoxic IELs and apoptotic epithelial cells are increased in number in gastric mucosa affected with AGMLs. These results provide evidence that this condition could be categorized as apoptotic gastritis with activation of the innate immune response.

Background: Our previous study showed that histological scores of gastric mucosal inflammation and Helicobacter pylori density decreased even in patients who failed to eradicate Helicobacter pylori after antimicrobial therapy including clarithromycin. This may reflect indirect suppressive effects of lower concentrations of clarithromycin on Helicobacter pylori, as suggested in other Gram-negative rod infections., Aims: To investigate whether clarithromycin suppresses virulence factors of Helicobacter pylori at sub-minimal inhibitory concentration., Methods: Six clarithromycin-susceptible Helicobacter pylori isolates and 7 clarithromycin-resistant isolates were obtained from patients with peptic ulcer disease. These isolates were analysed for urease activity, motility, and ability to bind to gastric epithelial cells after they were incubated with or without clarithromycin at sub-minimal inhibitory concentrations., Results: Incubation of Helicobacter pylori isolates with clarithromycin at sub-minimal inhibitory concentrations reduced urease activity motility, and binding to gastric epithelial cells in a dose-dependent manner. These findings were observed both in clarithromycin-susceptible and resistant strains., Conclusions: Suppressive effects of clerithromycin on virulence factors of Helicobacter pylori at sub-minimal inhibitory concentrations may be associated with observed attenuation of gastric inflammation and Helicobacter pylori density in patients who failed in bacterial eradication after triple therapy including clarithromycin.

Background: Excessive upregulation of gastric epithelial cell apoptosis is speculated to be associated with ulcerogenesis in Helicobacter pylori-positive peptic ulcer disease. H. pylori may have an ulcerogenic effect through induction of gastric epithelial cell apoptosis mediated by infiltrating T cells and their soluble products., Methods: The contents of soluble Fas ligand (sFasL) and interferon-gamma (IFN-gamma) in organ cultures and the degree of apoptosis and the expression of apoptosis-related proteins in the gastric epithelium were examined using the mucosal tissues obtained from the antrum and the ulcer site in patients with H. pylori-positive gastric ulcer (GU). The molecular mechanisms of gastric epithelial cell apoptosis induced by sFasL and IFN-gamma were analyzed using epithelial cell lines, MKN 45 and KATO III., Results: The mucosal tissues of the ulcer site had substantially higher contents of sFasL and IFN-gamma in organ cultures regardless of its healing stage in association with increased numbers of apoptotic cells and enhanced expression of proapoptotic proteins Bak and Bax in the surface foveolar epithelium as compared with the antral tissues in patients with H. pylori-positive GU. The addition of sFasL caused increases in cytotoxic cell death and caspase-3 activation in MKN 45 and KATO III cells in which IFN-gamma treated cells had more prominent effects than untreated cells. The expression of Bak in MKN 45 cells increased when they were treated with IFN-gamma., Conclusions: Upregulation of mucosal sFasL and IFN-gamma may be involved in ulcerogenesis in patients with H. pylori-positive GU through induction of gastric epithelial cell apoptosis.

Background: Clarithromycin (CAM) may have certain indirect effects on Helicobacter pylori (H. pylori) other than its inhibitory activity on bacterial growth, as indicated in other infections with Gram-negative micro-organisms. In the present study, we examined the effects of lower concentrations of CAM on the release of heat shock protein B (HspB), one of the major antigenic proteins from H. pylori cells, as well as the changes in humoral immune response and histological degree of antral gastritis in patients who received eradication therapy with CAM., Methods: The H. pylori strain 26695 and three CAM-resistant clinical isolates were cultured in broth with and without CAM (2-500 ng/mL). Expression of H. pylori proteins was examined by two-dimensional (2D)-electrophoresis followed by N-terminal amino acid sequencing. Changes in host immune response and histological degree of antral gastritis were monitored in patients with peptic ulcer disease who received H. pylori eradication therapy., Results: 2D electrophoresis showed 26 spots in extracellularly released proteins with different profiles from those in cytoplasmic proteins. The release of HspB increased after incubation with CAM (30-500 ng/mL) in all three H. pylori clinical isolates tested. Patients with failed H. pylori eradication after triple therapy with CAM, but not those with failed eradication after dual therapy without CAM, showed an increase in serum IgG1 and IgG2 antibodies against HspB along with a decrease in the degree of neutrophil and H. pylori colonization density in tissue sections., Conclusions: CAM may induce a humoral immune response against H. pylori and a decrease in gastric mucosal inflammation through up-regulation of the release of HspB from the bacteria in infected patients.

Background: Although increased levels of interleukin (IL)-8 are known to be associated with infiltration of neutrophils in the gastric mucosa with Helicobacter pylori infection, no study has investigated the relationship between local IL-8 levels and neutrophil infiltration in the duodenal mucosa of patients with duodenal ulcer (DU)., Methods: Duodenal mucosal biopsy specimens with and without gastric metaplasia (GM) were obtained from patients with DU and controls with an endoscopic methylene blue (MB) staining method. Levels of IL-8 secreted in the organ cultures of biopsy specimens were measured with an enzyme-linked immunosorbent assay. The number of myeloperoxidase-positive neutrophils infiltrating the lamina propria was determined in immunohistochemically stained tissue sections., Results: Histologic assessment showed that there was a strong correlation between the absence of endoscopic MB staining and the extent of GM. The levels of IL-8 in both duodenal and antral mucosal tissues were significantly higher in patients with H. pylori infection than in those without infection. In patients with DU the duodenal mucosal tissues with GM (MB-unstained mucosa) showed significantly higher levels of IL-8 than those without GM (MB-stained mucosa) or the antral mucosa. The number of neutrophils showed similar variations among DU and control patients with a positive correlation with IL-8 activity. The levels of IL-8 and the number of neutrophils decreased after H. pylori eradication in both duodenal and antral mucosal tissues, and these changes were more remarkable in the duodenal mucosal tissues with GM., Conclusions: Increased IL-8 activity in the duodenal mucosa with GM may be important for ulcerogenesis in H. pylori-positive DU patients.

Background: Enhanced gastric mucosal chemokine activity has been demonstrated in patients with Helicobacter pylori infection. However, little is known about the mechanisms involved in this phenomenon., Aim: To examine whether in vivo chemokine activity is similar to in vitro response of gastric epithelial cells infected by H. pylori., Patients and Methods: Antral biopsy specimens were obtained from patients with H. pylori infection for organ culture, isolation of H. pylori and histological examination., Results: In organ cultures of mucosal tissues, the levels of interleukin-8 and growth-related gene product a were elevated in patients with peptic ulcer disease compared with those with erosive gastritis or endoscopically normal mucosa. However, there were no significant differences in in vitro cultures of MKN45 or KATO III cells that were infected with H. pylori isolated from these same patients. These in vivo and in vitro alpha-chemokine levels showed no significant association with the presence of cagA gene and CagA protein, ureB genotype, or binding capacity to MKN45 or KATO III cells in individual H. pylori isolates. In contrast, in vivo mucosal alpha-chemokine activity correlated with H. pylori colonization density., Conclusion: Mucosal chemokine profiles and inflammatory responses in H. pylori infection may be associated more closely with host factors, including those determining bacterial adhesiveness, than with differences in H. pylori strains.

Background and Aim: Although mucosal alpha- and beta-chemokines are considered to be involved in the pathogenesis of Helicobacter pylori-associated gastritis, little is known how these chemokines are related to the ulcerogenesis in peptic ulcer patients. We examined the levels of interleukin (IL)-8 and macrophage inflammatory protein-1alpha (MIP-1alpha) in organ cultures and the numbers of inflammatory cells infiltrating the lamina propria by using the mucosal tissues obtained from gastric ulcer (GU) patients with and without H. pylori infection., Methods: Levels of IL-8 and MIP-1alpha secreted in organ cultures were measured by an enzyme-linked immunosorbent assay. Numbers of myeloperoxidase-positive neutrophils, CD68-positive macrophages, and mononuclear cells were determined in tissue sections., Results: The mucosal tissues of both the gastric antrum and the ulcer site obtained from patients with H. pylori-positive GU showed significantly higher levels of IL-8 and MIP-1alpha and increased numbers of inflammatory cells compared with the corresponding mucosal tissues from those with H. pylori-negative GU or the antral mucosal tissues from H. pylori-negative controls. When the values were compared between the mucosal tissues from the gastric antrum and those from the ulcer site, the latter group of tissues showed significantly higher levels of IL-8 and MIP-1alpha and increased numbers of neutrophils and macrophages than the former group regardless of its healing process in patients with H. pylori-positive GU., Conclusion: Mucosal alpha- and beta-chemokines may be important to the ulcerogenesis in H. pylori-associated GU disease., (Copyright 2000 S. Karger AG, Basel.)

We examined the relationship between the levels of macrophage inflammatory protein 1alpha (MIP-1alpha) and interleukin-8 (IL-8) in organ cultures of antral mucosal tissues, background gastroduodenal diseases, and grades of histologic gastritis. Significantly higher levels of MIP-1alpha and IL-8 were detected in patients with H. pylori infection than in those without infection. In H. pylori-positive patients, mucosal specimens from patients with peptic ulcer disease showed higher levels of MIP-1alpha and IL-8 than the specimens obtained from patients with erosive gastritis or those from endoscopically normal mucosa, and this was particularly pronounced in patients with duodenal ulcer. There were positive correlations between MIP-1alpha and IL-8 levels and histologic grades of activity, inflammation, and H. pylori density as defined by the Sydney system. However, the degree of association with the inflammatory cell count was different between these two chemokines. MIP-1alpha levels had a stronger association with mononuclear cells than with neutrophils, whereas IL-8 levels showed an association with neutrophils and mononuclear cells to an almost equal degree. These results suggest that MIP-1alpha and IL-8 may play important roles as inflammatory mediators in the pathogenesis of histologically proven H. pylori-associated gastritis.

We examined secretion, mRNA expression, and histologic localization of interleukin-8 (IL-*) and growth-related gene product-alpha (GRO alpha) in the Helicobacter pylori-infected gastric antral mucosa. Antral biopsies were obtained from an area of endoscopically intact mucosa. Significantly higher levels of IL-8 and GRO alpha were secreted in organ cultures from patients with H. pylori infection, and their elevation was prominent in patients with duodenal ulcer. There was a significant association between these alpha-chemokine levels and histologic grades of activity, inflammation, and H. pylori density. In fresh antral biopsies, IL-8 and GRO alpha mRNA expression was detected more frequently in H. pylori-infected patients compared with those without infection. Immunofluorescence microscopy showed localization of IL-8 and GRO alpha proteins in gastric epithelial cells and infiltrating CD68+ macrophages. In the chemotaxis assay, a significant positive correlation was found between neutrophil migration induced by the organ culture supernatants and their contents of IL-8 and GRO alpha. After H. pylori eradication, a significant decrease was observed in IL-8 and GRO alpha levels detected in organ cultures. In conclusion, mucosal alpha-chemokine activity correlates well with histologic severity of H. pylori-associated antral gastritis and can be used to predict the effects of H. pylori eradication therapy.

Background: Excessive upregulation of gastric epithelial cell apoptosis is speculated to be associated with ulcerogenesis in Helicobacter pylori-positive peptic ulcer disease. H. pylori may have an ulcerogenic effect through induction of gastric epithelial cell apoptosis mediated by infiltrating T cells and their soluble products. Methods: The contents of soluble Fas ligand (sFasL) and interferon-γ (IFN-γ) in organ cultures and the degree of apoptosis and the expression of apoptosis-related proteins in the gastric epithelium were examined using the mucosal tissues obtained from the antrum and the ulcer site in patients with H. pylori-positive gastric ulcer (GU). The molecular mechanisms of gastric epithelial cell apoptosis induced by sFasL and IFN-γ were analyzed using epithelial cell lines, MKN 45 and KATO III. Results: The mucosal tissues of the ulcer site had substantially higher contents of sFasL and IFN-γ in organ cultures regardless of its healing stage in association with increased numbers of apoptotic cells and enhanced expression of proapoptotic proteins Bak and Bax in the surface foveolar epithelium as compared with the antral tissues in patients with H. pylori-positive GU. The addition of sFasL caused increases in cytotoxic cell death and caspase-3 activation in MKN 45 and KATO III cells in which IFN-γ-treated cells had more prominent effects than untreated cells. The expression of Bak in MKN 45 cells increased when they were treated with IFN-γ. Conclusions: Upregulation of mucosal sFasL and IFN-γ may be involved in ulcerogenesis in patients with H. pylori-positive GU through induction of gastric epithelial cell apoptosis. [ABSTRACT FROM AUTHOR]