Capsaicin as an inhibitor of the growth of the gastric pathogen Helicobacter pylori

Anti-inflammatory effect of capsaicin in Helicobacter pylori-infected gastric epithelial cells

BACKGROUND AND AIM

Capsaicin, the main pungent ingredient of hot red and chilli pepper, has been considered as not only a cytoprotective but also a detrimental agent to the gastric mucosa. However, the effect and mechanism of capsaicin that modulate the induction of pro-inflammatory cytokine in Helicobacter pylori-infected epithelial cells have not been investigated previously. Herein, we demonstrated that capsaicin inhibited the release of pro-inflammatory cytokine, interleukin-8 (IL-8) by H. pylori-infected gastric epithelial cells through nuclear factor-kappaB (NF-kappaB) signal pathway.

MATERIALS AND METHODS

AGS or MKN45 cells as gastric epithelial cells and Vac A+, CagA+ wild-type H. pylori strain ATCC 49503 were used. Gastric epithelial cells were pre-treated with various concentrations of capsaicin and infected with H. pylori for different periods of time to determine IL-8 concentrations in culture supernatant by an ELISA assay. We measured IL-8 mRNA transcripts in H. pylori-infected gastric epithelial cells co-treated with capsaicin by reverse transcriptase-polymerase chain reaction analysis. We performed electrophoretic mobility shift assay to examine the NF-kappaB DNA binding activity with capsaicin and immunofluorescence microscopy to examine nuclear staining of p65. We also performed immunoblotting for IkappaB, IKK activity with capsaicin.

RESULTS

Capsaicin inhibits H. pylori-induced IL-8 production by gastric epithelial cells in dose- and time-dependent manner. Capsaicin as low as 100 micromol/L significantly inhibited IL-8 production in H. pylori-infected MKN45 cells (43.2% of control) at 24 hours incubation, whereas inhibited IL-8 production in H. pylori-infected AGS cells (70% of control). We confirmed that capsaicin inhibited IL-8 mRNA expression after infection of gastric epithelial cells with H. pylori for 6 hours. The addition of capsaicin (100 micromol/L) suppressed H. pylori-induced NF-kappaB activation in gastric epithelial cells at 1 hour post-infection. We also found that the degradation of IkappaB and IKK activation were inhibited by capsaicin.

CONCLUSIONS

Nontoxic dose of capsaicin inhibited H. pylori-induced IL-8 production by gastric epithelial cells through the modulation of IkappaB-, NF-kappaB-, and IL-8 pathways. We conclude that capsaicin can be proposed as a potential anti-inflammatory drug by inhibition of the production of IL-8 in H. pylori-infected gastric epithelium.

Capsaicin and gastric ulcers

In recent years, infection of the stomach with the organism Helicobacter Pylori has been found to be the main cause of gastric ulcers, one of the common ailments afflicting humans. Excessive acid secretion in the stomach, reduction in gastric mucosal blood flow, constant intake of non-steroid anti-inflammatory drugs (NSAIDS), ethanol, smoking, stress etc. are also considered responsible for ulcer formation. The prevalent notion among sections of population in this country and perhaps in others is that "red pepper" popularly known as "Chilli," a common spice consumed in excessive amounts leads to "gastric ulcers" in view of its irritant and likely acid secreting nature. Persons with ulcers are advised either to limit or avoid its use. However, investigations carried out in recent years have revealed that chilli or its active principle "capsaicin" is not the cause for ulcer formation but a "benefactor." Capsaicin does not stimulate but inhibits acid secretion, stimulates alkali, mucus secretions and particularly gastric mucosal blood flow which help in prevention and healing of ulcers. Capsaicin acts by stimulating afferent neurons in the stomach and signals for protection against injury causing agents. Epidemiologic surveys in Singapore have shown that gastric ulcers are three times more common in the "Chinese" than among Malaysians and Indians who are in the habit of consuming more chillis. Ulcers are common among people who are in the habit of taking NSAIDS and are infected with the organism "Helicobacter Pylori," responsible for excessive acid secretion and erosion of the mucosal layer. Eradication of the bacteria by antibiotic treatment and avoiding the NSAIDS eliminates ulcers and restores normal acid secretion.

New constituents of sweet Capsicum annuum L. fruits and evaluation of their biological activity

Four new acyclic diterpene glycosides named capsianosides (1-4), together with 12 known compounds, were isolated from the fresh sweet pepper fruits of Capsicum annuum L., a plant used as a vegetable food, spice, and external medicine. The chemical structures of new natural compounds, as well as their absolute configurations, were established by means of spectroscopic data including infrared, high-resolution mass spectrometry, and one- and two-dimensional nuclear magnetic resonance and by chemical derivatization. The known capsidiol (11) showed bacteriostatic properties in vitro against Helicobacter pylori with a minimum inhibitory concentration (MIC) of 200 microg/mL when compared with the commercial drug metronidazole (MIC, 250 microg/mL). Some purified components were also tested for their antioxidant activities.

Antibacterial activity of Tabebuia impetiginosa Martius ex DC (Taheebo) against Helicobacter pylori

The growth-inhibiting activity of Tabebuia impetiginosa Martius ex DC dried inner bark-derived constituents against Helicobacter pylori ATCC 43504 was examined using paper disc diffusion and minimum inhibitory concentration (MIC) bioassays. The activity of the isolated compounds was compared to that of the commercially available anti-Helicobacter pylori agents, amoxicillin, metronidazole, and tetracycline. The biologically active components of Tabebuia impetiginosa dried inner bark (taheebo) were characterized by spectroscopic analysis as 2-(hydroxymethyl)anthraquinone, anthraquinone-2-carboxylic acid, and 2-hydroxy-3-(3-methyl-2-butenyl)-1,4-naphthoquinone (lapachol). With the paper disc diffusion assay 2-(hydroxymethyl)anthraquinone exhibited strong activity against Helicobacter pylori ATCC 43504 at 0.01 mg/disc. Anthraquinone-2-carboxylic acid, lapachol and metronidazole were less effective, exhibiting moderate anti-Helicobacter pylori activity at 0.1 mg/disc. Amoxicillin and tetracycline were the most potent compounds tested, displaying very strong activity at 0.005 mg/disc. 2-(Hydroxymethyl)anthraquinone exhibited moderate activity at this dose. Tetracycline still had strong activity at 0.001 mg/disc while amoxicillin had little activity at this dose. In the MIC bioassay, 2-(hydroxymethyl)anthraquinone (2 microg/mL), anthraquinone-2-carboxylic acid (8 microg/mL), and lapachol (4 microg/mL) were more active than metronidazole (32 microg/mL) but less effective than amoxicillin (0.063 microg/mL) and tetracycline (0.5 microg/mL). The anti-Helicobacter pylori activity of seven 1,4-naphthoquinone derivatives (structurally related to lapachol), 1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone (naphthazarin), 2-methyl-1,4-naphthoquinone (menadione), 2-hydroxy-1,4-naphthoquinone (lawsone), 5-hydroxy-2-methyl-1,4-naphthoquinone (plumbagin), 5-hydroxy-1,4-naphthoquinone (juglone), and 2,3-dichloro-1,4-naphthoquinone (dichlone) was also evaluated using the paper disc assay. Menadione and plumbagin were the most potent compounds tested with the later still exhibiting very strong activity at 0.001 mg/disc. Menadione, juglone and tetracycline had strong activity at this low dose while the latter two compounds and amoxicillin had very strong activity at 0.005 mg/disc. Lawsone was unusual in that it had very strong activity at 0.1 and 0.05 mg/disc but weak activity at doses of 0.01 mg/disc and lower. Naphthazalin, lapachol and dichlone had similar activities while metronidazole had the lowest activity of all compounds tested. These results may be an indication of at least one of the pharmacological actions of taheebo. The Tabebuia impetiginosa dried inner bark-derived materials, particularly 2-(hydroxymethyl)anthraquinone, merit further study as potential Helicobacter pylori eradicating agents or lead compounds.

Bactericidal and anti-adhesive properties of culinary and medicinal plants against Helicobacter pylori

AIM

To investigate the bactericidal and anti-adhesive properties of 25 plants against Helicobacter pylori (H. pylori).

METHODS

Twenty-five plants were boiled in water to produce aqueous extracts that simulate the effect of cooking. The bactericidal activity of the extracts was assessed by a standard kill-curve with seven strains of H. pylori. The anti-adhesive property was assessed by the inhibition of binding of four strains of FITC-labeled H. pylori to stomach sections.

RESULTS

Of all the plants tested, eight plants, including Bengal quince, nightshade, garlic, dill, black pepper, coriander, fenugreek and black tea, were found to have no bactericidal effect on any of the isolates. Columbo weed, long pepper, parsley, tarragon, nutmeg, yellow-berried nightshade, threadstem carpetweed, sage and cinnamon had bactericidal activities against H. pylori, but total inhibition of growth was not achieved in this study. Among the plants that killed H. pylori, turmeric was the most efficient, followed by cumin, ginger, chilli, borage, black caraway, oregano and liquorice. Moreover, extracts of turmeric, borage and parsley were able to inhibit the adhesion of H. pylori strains to the stomach sections.

CONCLUSION

Several plants that were tested in our study had bactericidal and/or anti-adhesive effects on H. pylori. Ingestion of the plants with anti-adhesive properties could therefore provide a potent alternative therapy for H. pylori infection, which overcomes the problem of resistance associated with current antibiotic treatment.

Inhibition of Helicobacter pylori and associated urease by oregano and cranberry phytochemical synergies

Ulcer-associated dyspepsia is caused by infection with Helicobacter pylori. H. pylori is linked to a majority of peptic ulcers. Antibiotic treatment does not always inhibit or kill H. pylori with potential for antibiotic resistance. The objective of this study was to determine the potential for using phenolic phytochemical extracts to inhibit H. pylori in a laboratory medium. Our approach involved the development of a specific phenolic profile with optimization of different ratios of extract mixtures from oregano and cranberry. Subsequently, antimicrobial activity and antimicrobial-linked urease inhibition ability were evaluated. The results indicated that the antimicrobial activity was greater in extract mixtures than in individual extracts of each species. The results also indicate that the synergistic contribution of oregano and cranberry phenolics may be more important for inhibition than any species-specific phenolic concentration. Further, based on plate assay, the likely mode of action may be through urease inhibition and disruption of energy production by inhibition of proline dehydrogenase at the plasma membrane.

Non-antibiotic therapies for Helicobacter pylori infection

Despite years of experience with Helicobacter pylori treatment, the ideal regimen for treating the infection has not been found. The most effective eradication treatment is the combination of a proton pump inhibitor with antibiotics, but 10-20% of the patients fail to obtain eradication of the infection. Antibiotic resistance is a major factor affecting the outcome of treatment. Non-antibiotic therapies, including phytomedicines, probiotics, and antioxidants, have been increasingly investigated as potential alternatives for the treatment of H. pylori. In this article, we review the non-antibiotic therapies for H. pylori infection.

Screening of anti-Helicobacter pylori herbs deriving from Taiwanese folk medicinal plants

In this study, extracts from 50 Taiwanese folk medicinal plants were examined and screened for anti-Helicobacter pylori activity. Ninety-five percent ethanol was used for herbal extraction. Paederia scandens (Lour.) Merr. (PSM), Plumbago zeylanica L. (PZL), Anisomeles indica (L.) O. Kuntze (AIOK), Bombax malabaricum DC. (BMDC) and Alpinia speciosa (J. C. Wendl.) K. Schum. (ASKS) and Bombax malabaricum DC. (BMDC) all demonstrated strong anti-H. pylori activities. The minimum inhibitory concentration values of the anti-H. pylori activity given by the five ethanol herb extracts ranged from 0.64 to 10.24 mg ml(-1). Twenty-six herbs, including Artemisia argvi Levl. et Vant (AALEV), Phyla nodiflora (Linn.) Greene (PNG) and others, showed moderate anti-H. pylori activity. The additional 19 herbs, including Areca catechu Linn. (ACL), Euphorbia hirta Linn. (EHL) and Gnaphalium adnatum Wall. ex DC. (GAWEDC), possessed lower anti-H. pylori effects. About half of the Taiwanese folk medicinal plants tested, demonstrated to possess higher anti-H. pylori activity.

Efficacy of sulforaphane in eradicating Helicobacter pylori in human gastric xenografts implanted in nude mice

Sulforaphane, an isothiocyanate abundant in the form of its glucosinolate precursor in broccoli sprouts, has shown in vitro activity against Helicobacter pylori. We evaluated the effect of sulforaphane in vivo against this bacterium by using human gastric xenografts in nude mice. H. pylori was completely eradicated in 8 of the 11 sulforaphane-treated grafts. This result suggests that sulforaphane might be beneficial in the treatment of H. pylori-infected individuals.

In vitro anti-Helicobacter pylori activity of Greek herbal medicines

In this paper, we have studied the anti-Helicobacter pylori effect of 70 Greek plant extracts and a number of commercially available herbs used traditionally in folk medicine against gastric ailments, peptic ulcer included. The extracts of Anthemis melanolepis, Cerastium candidissimum, Chamomilla recutita, Conyza albida, Dittrichia viscosa, Origanum vulgare and Stachys alopecuros have been proved active against one standard strain and 15 clinical isolates of H. pylori.

Metabolism of capsaicin by cytochrome P450 produces novel dehydrogenated metabolites and decreases cytotoxicity to lung and liver cells

Capsaicin is a common dietary constituent and a popular homeopathic treatment for chronic pain. Exposure to capsaicin has been shown to cause various dose-dependent acute physiological responses including the sensation of burning and pain, respiratory depression, and death. In this study, the P450-dependent metabolism of capsaicin by recombinant P450 enzymes and hepatic and lung microsomes from various species, including humans, was determined. A combination of LC/MS, LC/MS/MS, and LC/NMR was used to identify several metabolites of capsaicin that were generated by aromatic (M5 and M7) and alkyl hydroxylation (M2 and M3), O-demethylation (M6), N- (M9) and alkyl dehydrogenation (M1 and M4), and an additional ring oxygenation of M9 (M8). Dehydrogenation of capsaicin was a novel metabolic pathway and produced unique macrocyclic, diene, and imide metabolites. Metabolism of capsaicin by microsomes was inhibited by the nonselective P450 inhibitor 1-aminobenzotriazole (1-ABT). Metabolism was catalyzed by CYP1A1, 1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4. Addition of GSH (2 mM) to microsomal incubations stimulated the metabolism of capsaicin and trapped several reactive electrophilic intermediates as their GSH adducts. These results suggested that reactive intermediates, which inactivated certain P450 enzymes, were produced during catalytic turnover. Comparison of the rate and types of metabolites produced from capsaicin and its analogue, nonivamide, demonstrated similar pathways in the P450-dependent metabolism of these two capsaicinoids. However, production of the dehydrogenated (M4), macrocyclic (M1), and omega-1-hydroxylated (M3) metabolites was not observed for nonivamide. These differences may be reflective of the mechanism of formation of these metabolites of capsaicin. The role of metabolism in the cytotoxicity of capsaicin and nonivamide was also assessed in cultured lung and liver cells. Lung cells were markedly more sensitive to cytotoxicity by capsaicin and nonivamide. Cytotoxicity was enhanced 5 and 40% for both compounds by 1-ABT in BEAS-2B and HepG2, respectively. These data suggested that metabolism of capsaicinoids by P450 in cells represented a detoxification mechanism (in contrast to bioactivation).

Anti-Helicobacter pylori flavonoids from licorice extract

Licorice is the most used crude drug in Kampo medicines (traditional Chinese medicines modified in Japan). The extract of the medicinal plant is also used as the basis of anti-ulcer medicines for treatment of peptic ulcer. Among the chemical constituents of the plant, glabridin and glabrene (components of Glycyrrhiza glabra), licochalcone A (G. inflata), licoricidin and licoisoflavone B (G. uralensis) exhibited inhibitory activity against the growth of Helicobacter pylori in vitro. These flavonoids also showed anti-H. pylori activity against a clarithromycin (CLAR) and amoxicillin (AMOX)-resistant strain. We also investigated the methanol extract of G. uralensis. From the extract, three new isoflavonoids (3-arylcoumarin, pterocarpan, and isoflavan) with a pyran ring, gancaonols A[bond]C, were isolated together with 15 known flavonoids. Among these compounds, vestitol, licoricone, 1-methoxyphaseollidin and gancaonol C exhibited anti-H. pylori activity against the CLAR and AMOX-resistant strain as well as four CLAR (AMOX)-sensitive strains. Glycyrin, formononetin, isolicoflavonol, glyasperin D, 6,8-diprenylorobol, gancaonin I, dihydrolicoisoflavone A, and gancaonol B possessed weaker anti-H. pylori activity. These compounds may be useful chemopreventive agents for peptic ulcer or gastric cancer in H. pylori-infected individuals.

Vanilloid receptor ligands: hopes and realities for the future

Neurons possessing C-fibers transmit nociceptive information into the central nervous system and participate in various reflex responses. These neurons carry receptors that bind capsaicin, recently identified as the vanilloid VR1 receptor. Excitation of these cells by capsaicin is followed by a lasting refractory state, termed desensitisation, in which the neurons fail to respond to a variety of noxious stimuli. Desensitisation to capsaicin has a clear therapeutic potential in relieving neuropathic pain and ameliorating urinary bladder overactivity, just to cite 2 important examples. Vanilloids may also be beneficial in the treatment of benign prostate hyperplasia (BPH). Since the majority of elderly patients have neuropathic pain co-existent with urinary incontinence and/or BPH, a drug that ameliorates pain and improves urinary symptoms at the same time promises to be of great clinical value in geriatric medicine. In fact, capsaicin has already been shown to have a role in the treatment of conditions that can arise in the elderly, including herpes zoster-related neuropathic pain, diabetic neuropathy, postmastectomy pain, uraemic itching associated with renal failure, and urinary incontinence. The potent VR1 agonist resiniferatoxin, now in phase II clinical trials, appears to be superior to capsaicin in terms of its tolerability profile. Recent discoveries enhance the therapeutic potential of vanilloids. The recognition that VR1 also functions as a principal receptor for protons and eicosanoids implies that VR1 antagonists may be of value in the treatment of inflammatory hyperalgesia and pain. Animal experimentation has already lent support to this assumption. The discovery of VR1-expressing cells in the brain as well as in non-neural tissues such as the kidney and urothelium places VR1 in a much broader perspective than peripheral pain perception, and is hoped to identify further, yet unsuspected, indications for vanilloid therapy. The realisation that VR1 and cannabinoid CB1 receptors have overlapping ligand recognition properties may also have far-reaching implications for vanilloid therapy. In fact, arvanil, a combined agonist of VR1 and CB1 receptors, has already proved to be a powerful analgesic drug in the mouse. From academic molecular biology laboratories to industrial drug discovery centres to the clinics, there is a steady flow of new data, forcing us to constantly revise the ways we are thinking about vanilloid receptor ligands and their hopes and realities for the future. This review covers the most promising current trends in vanilloid research with special emphasis on geriatric medicine.

Bactericidal activity of Pistacia lentiscus mastic gum against Helicobacter pylori

In this study we evaluated the antibacterial activity of mastic gum, a resin obtained from the Pistacia lentiscus tree, against clinical isolates of Helicobacter pylori. The minimal bactericidal concentrations (MBCs) were obtained by a microdilution assay. Mastic gum killed 50% of the strains tested at a concentration of 125 microg/ml and 90% at a concentration of 500 microg/ml. The influence of sub-MBCs of mastic gum on the morphologies of H. pylori was evaluated by transmission electron microscopy. The lentiscus resin induced blebbing, morphological abnormalities and cellular fragmentation in H. pylori cells.

In vitro anti-Helicobacter pylori activity of panaxytriol isolated from ginseng

This study investigated the effect that some polyacetylenes and protopanaxatriol, which were isolated from heated ginseng (family Araliaceae), have on inhibiting Helicobacter pylori (HP) growth. Among the compounds tested, panaxytriol was quite effective in inhibiting HP growth with an MIC of 50 microg/ml. Ginsenoside Rh1 and protopanaxatriol weakly inhibited H+/K+-ATPase from a rat stomach.

Biphasic membrane effects of capsaicin, an active component in Capsicum species

Capsaicin, an active component in Capsicum species, not only stimulates sensory afferent neurons but also inhibits bacterial growth and platelet aggregation. To address the pharmacological mechanism of non-neuronal actions, the effects of capsaicin and its structural analog (N-vanillylnonanamide) on membrane fluidity were studied by measuring fluorescence polarization of liposomes prepared with different phospholipids and cholesterol. Capsaicin and the analog changed membrane fluidity over the concentration range of 50-500 microM differentially with varying concentrations and membrane lipid composition. They showed biphasic effects on 100 mol% 1-palmitoyl-2-oleoylphosphatidylcholine liposomes and 40 mol% cholesterol-containing 1-palmitoyl-2-oleoylphosphatidylcholine liposomes to fluidize and rigidify both liposomal membranes at low and high concentrations, respectively. Changes in membrane fluidity occurred at concentrations corresponding to their reported antibacterial and antiplatelet concentrations. Antibacterial (geraniol and lidocaine) and antiplatelet reference compounds (4-ethylphenol and benzyl alcohol) concentration-dependently fluidized membranes, while not showing biphasic effects. Comparing the potency to fluidize membranes, capsaicin was almost comparable to geraniol and 4-ethylphenol, and more active than lidocaine and benzyl alcohol. The membrane effects of capsaicinoids are responsible for their non-neuronal antibacterial and antiplatelet actions, although they are not the simple membrane fluidizers.

Antimicrobial screening of some Indian spices

In India, spices have been traditionally used since ancient times, for the preservation of food products as they have been reported to have antiseptic and disinfectant properties. In this respect, a preliminary screening for antimicrobial activities of 35 different Indian spices has been carried out. Of the spices surveyed, the results indicate that clove, cinnamon, bishop's weed, chilli, horse raddish, cumin, tamarind, black cumin, pomegranate seeds, nutmeg, garlic, onion, tejpat, celery, cambodge, have potent antimicrobial activities against the test organisms Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 10536) and Saccharomyces cerevisiae (ATCC 9763). The results also establish the traditional use of spices as food preservatives, disinfectants and antiseptics.

Plant products as antimicrobial agents

The use of and search for drugs and dietary supplements derived from plants have accelerated in recent years. Ethnopharmacologists, botanists, microbiologists, and natural-products chemists are combing the Earth for phytochemicals and "leads" which could be developed for treatment of infectious diseases. While 25 to 50% of current pharmaceuticals are derived from plants, none are used as antimicrobials. Traditional healers have long used plants to prevent or cure infectious conditions; Western medicine is trying to duplicate their successes. Plants are rich in a wide variety of secondary metabolites, such as tannins, terpenoids, alkaloids, and flavonoids, which have been found in vitro to have antimicrobial properties. This review attempts to summarize the current status of botanical screening efforts, as well as in vivo studies of their effectiveness and toxicity. The structure and antimicrobial properties of phytochemicals are also addressed. Since many of these compounds are currently available as unregulated botanical preparations and their use by the public is increasing rapidly, clinicians need to consider the consequences of patients self-medicating with these preparations.

Helicobacter pylori induces gastric epithelial cell apoptosis in association with increased Fas receptor expression

The mechanisms involved in mediating the enhanced gastric epithelial cell apoptosis observed during infection with Helicobacter pylori in vivo are unknown. To determine whether H. pylori directly induces apoptosis of gastric epithelial cells in vitro and to define the role of the Fas-Fas ligand signal transduction cascade, human gastric epithelial cells were infected with H. pylori for up to 72 h under microaerophilic conditions. As assessed by both transmission electron microscopy and fluorescence microscopy, incubation with a cagA-positive, cagE-positive, VacA-positive clinical H. pylori isolate stimulated an increase in apoptosis compared to the apoptosis of untreated AGS cells (16.0% +/- 2.8% versus 5.9% +/- 1. 4%, P < 0.05) after 72 h. In contrast, apoptosis was not detected following infection with cagA-negative, cagE-negative, VacA-negative clinical isolates or a Campylobacter jejuni strain. In addition to stimulating apoptosis, infection with H. pylori enhanced Fas receptor expression in AGS cells to a degree comparable to that of treatment with a positive control, gamma interferon (12.5 ng/ml) (148% +/- 24% and 167% +/- 24% of control, respectively). The enhanced Fas receptor expression was associated with increased sensitivity to Fas-mediated cell death. Ligation of the Fas receptor with an agonistic monoclonal antibody resulted in an increase in apoptosis compared to the apoptosis of cells infected with the bacterium alone (38.5% +/- 7.1% versus 16.0% +/- 2.8%, P < 0.05). Incubation with neutralizing anti-Fas antibody did not prevent apoptosis of H. pylori-infected cells. Taken together, these findings demonstrate that the gastric pathogen H. pylori stimulates apoptosis of gastric epithelial cells in vitro in association with the enhanced expression of the Fas receptor. These data indicate a role for Fas-mediated signaling in the programmed cell death that occurs in response to H. pylori infection.