Apoptosis of human gastric epithelial cells via caspase-3 activation in response to Helicobacter pylori infection: possible involvement of neutrophils through tumor necrosis factor alpha and soluble Fas ligands

Circulating and Tumor-Associated Neutrophils in the Era of Immune Checkpoint Inhibitors: Dynamics, Phenotypes, Metabolism, and Functions

Neutrophils are the most abundant myeloid cells in the blood and are a considerable immunological component of the tumor microenvironment. However, their functional importance has often been ignored, as they have always been considered a mono-dimensional population of terminally differentiated, short-living cells. During the last decade, the use of cutting-edge, single-cell technologies has revolutionized the classical view of these cells, unmasking their phenotypic and functional heterogeneity. In this review, we summarize the emerging concepts in the field of neutrophils in cancer, by reviewing the recent literature on the heterogeneity of both circulating neutrophils and tumor-associated neutrophils, as well as their possible significance in tumor prognosis and resistance to immune checkpoint inhibitors.

Effect of sodium butyrate on gastric ulcer aggravation and hepatic injury inflicted by bile duct ligation in rats

BACKGROUND AND AIM

Cholestasis is positively associated with an increased risk of peptic ulceration. The present study investigated the aggravating effect of cholestasis on piroxicam-induced gastric ulceration. The study also evaluated the effect of sodium butyrate (SoB) on piroxicam-induced gastric ulceration in cholestatic animals and its effect on hepatic tissues and both effects were compared to ursodeoxycholic acid (UDCA) as a standard anticholestatic drug.

METHODS

Bile duct ligation was adopted for induction of cholestasis in rats. The cholestatic animals received saline, SoB (P.O, 400 mg/kg, twice daily) or UDCA (P.O, 30 mg/kg/day) for 4 days starting from the first day of surgery. On the 4th day, blood samples were collected for determination of serum hepatic markers, then gastric ulcers were induced by piroxicam administration (P.O, 50 mg/kg) and 4 h later, the stomach was isolated and gastric mucosa was collected for biochemical determinations. The ulcer indices for the investigated drugs were compared to omeprazole as a standard acid suppressive drug.

RESULTS

Piroxicam-induced ulceration was exacerbated in cholestatic rats. Gastric mucosa showed a significant elevation of MDA and TNF-α together with a significant decrease in GSH &VEGF levels. SoB treatment significantly attenuated ulcer development. The afforded protection was higher than that provided by UDCA and was not significantly different from that afforded by omeprazole. SoB significantly decreased gastric mucosal MDA and TNF-α level, whereas UDCA failed to alter these parameters. Both drugs significantly elevated GSH, VEGF and IL10 levels. Similar to UDCA, SoB showed a significant reduction in AST, ALT, GGT, ALP and bilirubin level. Histopathological examination confirmed the attenuating effect of SoB on gastric and hepatic injury.

CONCLUSIONS

Sodium butyrate effectively protected gastric and hepatic tissues against cholestasis-induced damage. Gastroprotection was mediated through antioxidant, anti-inflammatory and angiogenic activities.

Improved antitumor efficacy of neutrophils stimulated by bacillus Calmette‑Guérin

Bacillus Calmette‑Guérin (BCG) has become a significant treatment for bladder cancer, and neutrophils are reported to be associated with the antitumor effect of BCG. The aim of the present study was to clarify the antitumor function of neutrophils stimulated by BCG. Initially, the killing effect and cytotoxic activity of neutrophils treated with BCG was detected. Subsequently, the effectiveness of BCG‑treated neutrophils extracted from tumor‑bearing mice was analyzed. The results revealed that the cytotoxic effect of neutrophils was stronger in the BCG‑treated group compared with that in the normal saline (NS)‑treated and control groups (P<0.05). A significantly higher concentration of cytokines tumor necrosis factor (TNF)‑α, interleukin (IL)‑1β, IL‑6 and TNF‑related apoptosis‑inducing ligand occurred in the BCG‑treated neutrophil group compared with the NS and control groups (P<0.01), which was also associated with the BCG dose (P<0.01). The gross tumor volume percentage in BCG‑treated neutrophils from tumor‑bearing mice (BCGT group) was significantly lower in comparison with that in the NS‑treated neutrophils from tumor‑bearing mice (NST group; P<0.05). In addition, the survival rate of tumor‑bearing mice was higher in the BCGT group compared with the NST group (P<0.05), while more BCG‑treated neutrophils from tumor‑bearing mice were infiltrated in the MethA tumor (P<0.01). In conclusion, BCG‑treated neutrophils were observed to enhance the antitumor efficacy and extend the life span of mice.

Association of tumor necrosis factor alpha gene polymorphisms with Helicobacter pylori infection in dyspeptic patients in Sri Lanka

Single nucleotide polymorphisms present on the promoter sequence of the TNF-α gene may affect production of TNF-α, a pro-inflammatory cytokine, during immune responses. The presence of TNF-α polymorphisms is also reportedly associated with more severe manifestations of Helicobacter pylori infection. However, the frequency of TNF-α polymorphisms and the associated disease severity vary between different patient groups. In this study, gastric biopsies and blood specimens were collected from 138 patients with dyspepsia undergoing routine upper gastrointestinal endoscopy. Our institution's Ethics Review Committee approved the study and written informed consent was obtained from all participants. The presence of H. pylori was confirmed histologically in all patients. The frequency of TNF-α polymorphisms in the study cohort was investigated using PCR-restriction fragment length polymorphism and expression of serum TNF-α quantitated using a commercial ELISA assay. The proportions of selected TNF-α polymorphisms (TNF-α -238, -308 and -863) were similar in H. pylori-positive and -negative patients. Homozygous mutations of TNF-α polymorphisms were rarely detected in the study group. There was a significant difference in TNF-α concentrations between patients with mild chronic gastritis and TNF-α -308 GG genotype and patients with moderate to severe chronic gastritis (P = 0.008). It was not possible to identify an association between these genotypes and disease severity because of the low frequency of heterozygous and homozygous mutated genes in Sri Lankan patients with dyspepsia.

Progress in the use of Immunotherapy to Treat Uterine Cervical Cancer

Cervical intraepithelial neoplasia has a high incidence in many of the world's populations, and it has been hypothesized to be a precursor of uterine cervical cancer. Cervical intraepithelial neoplasia also shares similar pathological traits with human papillomavirus infections. Various surgical treatments have been proposed over the years for the treatment of cervical intraepithelial neoplasia, including conization, hysterectomy and, more recently, a loop electrosurgical excisional procedure. However, a higher recurrence rate of the disease has been observed after these procedures. Therefore, immunotherapy has been proposed as a potential treatment to be used in conjunction with surgery, or independently, as treatment for cervical intraepithelial neoplasia. Currently, immunotherapy includes the application of recombinant viral proteins, vaccines, or antibody- and dendritic cell-based therapies. In this review, we summarize the development and testing of these immunotherapy approaches, particularly in regard to their application for the treatment of cervical intraepithelial neoplasia.

Effect of recombinant human lactoferrin treatment on mRNA expression of vacuolating cytotoxin A and content of tumor necrosis factor-α in gastric tissue of mice with Helicobacter pylori-associated gastritis

AIM: To explore whether recombinant human lactoferrin (rhLF) plus triple therapy can increase the rate of Helicobacter pylori(H. pylori) eradication, reduce gastric mucosal inflammation, and inhibit vacuolating cytotoxin (VacA) mRNA expression.

METHODS: One hundred and ninety-two H. pylori ATCC43504 infected Babl/c mice with gastritis were randomly divided into four groups: A (rhLF+standard triple therapy), B (rhLF alone), C (standard triple therapy alone), and D (saline). H. pyloricolonization of the gastric mucosa was assessed by silver staining. Gastric mucosal inflammation was assessed by HE staining. Tumor necrosis factor (TNF)-α content was determined by ELISA. VacA mRNA expression was detected by RT-PCR.

RESULTS: Compared with group D, the rate of H. pylori colonization and gastric mucosal inflammation score decreased significantly in groups A, B, and C (P < 0.05). Compared with groups B and C, the rate of H. pylori colonization and gastric mucosal inflammation score decreased significantly in group A (P < 0.05). rhLF plus standard triple therapy significantly decreased gastric TNF-α content (28.64 pg/mL ± 12.07 pg/mL vs 300.16 pg/mL ± 59.1 pg/mL, 54.96 pg/mL ± 15.02 pg/mL, 503.25 pg/mL ± 1.35 pg/mL, P < 0.01) and VacA mRNA expression (P < 0.01) compared with groups B, C and D.

CONCLUSION: rhLF combined with triple therapy can improve H. pylori eradication rate, reduce gastric mucosal inflammation possibly by inhibiting proinflammatory factor release, and effectively inhibit VacA mRNA expression.

Role of Tumor Necrosis Factor-Alpha and Interferon-Gamma inHelicobacter pyloriInfection

Immune responses to Helicobacter pylori infection play important roles in gastroduodenal diseases. The contributions of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) to the induction of gastric inflammation and to the protection from H. pylori infection were investigated using TNF-alpha geneknockout (TNF-alpha(-/-)) mice and IFN-gamma gene-knockout (IFN-gamma(-/-)) mice. We first examined the colonizing ability of H. pylori strain CPY2052 in the stomach of C57BL/6 wild-type and knockout mice. The number of H. pylori colonized in the stomach of IFN-gamma(-/-) and TNF-alpha(-/-) mice was higher than that of wild-type mice. These findings suggest that TNF-alpha and IFN-gamma may play a protective role in H. pylori infection. Furthermore, we examined the contribution of TNF-alpha and IFN-gamma to gastric inflammation. The CPY2052-infected TNF-alpha(-/-) mice showed a moderate infiltration of mononuclear cells in the lamina propria and erosions in the gastric epithelium as did wild-type mice, whereas the CPY2052-infected IFN-gamma(-/-) mice showed no inflammatory findings even 6 months after infection. These results demonstrate that IFN-gamma may play an important role in gastric inflammation induced by H. pylori infection, whereas TNF-alpha may not participate in the development of inflammatory response.

Molecular and histological evaluation of tumor necrosis factor-alpha expression in Helicobacter pylori-mediated gastric carcinogenesis

PURPOSE

Helicobacter pylori (H. pylori) is considered to be a major factor contributing to gastric mucosal damage by stimulating mucosal macrophage production of inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), but the inflammatory responses within the gastric mucosa in vivo are not well known. Therefore, this study was designed to investigate the expression of TNF-α induced by H. pylori infection which is involved in the tumor initiation and promotion of gastric carcinogenesis.

METHODS

This study was carried out in 200 patients, consisting of normal gastric mucosa (n = 20), mucosa with chronic gastritis (n = 63), intestinal metaplasia (n = 20), dysplasia (n = 11), and gastric adenocarcinoma (n = 86), in which the H. pylori status has been analyzed. The expression of TNF-α was studied at mRNA as well as protein level using RT-PCR and western blotting, respectively. The localization of TNF-α was also studied semiquantitatively by immunohistochemistry.

RESULTS

The RT-PCR and western blotting results of TNF-α mRNA and protein expressions were significantly increased in chronic gastritis, intestinal metaplasia, dysplasia and gastric adenocarcinoma patients, respectively. Immunohistochemical study also showed the increased expression of TNF-α in the similar way.

CONCLUSION

Over expression of TNF-α showed a significant severity-dose-response as risk markers from preneoplastic lesions to gastric cancer.

Differential induction of apoptosis in human colonic carcinoma cells (Caco-2) by Atopobium, and commensal, probiotic and enteropathogenic bacteria: mediation by the mitochondrial pathway

The induction of apoptosis in mammalian cells by bacteria is well reported. This process may assist infection by pathogens whereas for non-pathogens apoptosis induction within carcinoma cells protects against colon cancer. Here, apoptosis induction by a major new gut bacterium, Atopobium minutum, was compared with induction by commensal (Escherichia coli K-12 strains), probiotic (Lactobacillus rhamnosus, Bifidobacterium latis) and pathogenic (E. coli: EPEC and VTEC) gut bacteria within the colon cancer cell line, Caco-2. The results show a major apoptotic effect for the pathogens, mild effects for the probiotic strains and A. minutum, but no effect for commensal E. coli. The mild apoptotic effects observed are consistent with the beneficial roles of probotics in protection against colon cancer and suggest, for the first time, that A. minutum possesses similar advantageous, anti-cancerous activity. Although bacterial infection increased Caco-2 membrane FAS levels, caspase-8 was not activated indicating that apoptosis is FAS independent. Instead, in all cases, apoptosis was induced through the mitochondrial pathway as indicated by BAX translocation, cytochrome c release, and caspase-9 and -3 cleavage. This suggests that an intracellular stimulus initiates the observed apoptosis responses.

Serum markers of apoptosis decrease with age and cancer stage

The physical manifestations of aging reflect a loss of homeostasis that effects molecular, cellular and organ system functional capacity. As a sentinel homeostatic pathway, changes in apoptosis can have pathophysiological consequences in both aging and disease. To assess baseline global apoptosis balance, sera from 204 clinically normal subjects had levels of sFas (inhibitor of apoptosis), sFasL (stimulator of apoptosis), and total cytochrome c (released from cells during apoptosis) measured. Serum levels of sFas were significantly higher while sFasL and cytochrome c levels were lower in men compared to women. With increasing age there was a decrease in apoptotic markers (cytochrome c) and pro-apoptotic factors (sFasL) and an increase in anti-apoptotic factors (sFas) in circulation. The observed gender differences are consistent with the known differences between genders in mortality and morbidity. In a separate cohort, subjects with either breast (n = 66) or prostate cancer (n = 38) exhibited significantly elevated sFas with reduced sFasL and total cytochrome c regardless of age. These markers correlated with disease severity consistent with tumor subversion of apoptosis. The shift toward less global apoptosis with increasing age in normal subjects is consistent with increased incidence of diseases whose pathophysiology involves apoptosis dysregulation.

The use of neem for controlling gastric hyperacidity and ulcer

H(2)-receptor blockers and proton pump inhibitors are now used extensively to control gastric and duodenal ulcer, inflammation and pain, but these drugs have limitations and are not always affordable. The development of novel nontoxic antiulcer drugs, including from medicinal plants, is therefore desirable, and Azadirachta indica A. Juss, commonly known as Neem, is known to have potent gastroprotective and antiulcer effects. This review deals with the pharmacological and biochemical studies carried out regarding the antiulcer activities of Neem extracts and their mechanism of action, including the inhibition of acid secretion. A comparison with ranitidine and omeprazole in some animal models has been included and clinical studies, where available, have also been incorporated, along with a safety evaluation. Neem bark extract has the potential for the development of novel medicines for the therapeutic control of gastric hyperacidity and ulcer.

Long-term use of nonsteroidal anti-inflammatory drugs normalizes the kinetics of gastric epithelial cells in patients with Helicobacter pylori infection via attenuation of gastric mucosal inflammation

BACKGROUND

Helicobacter pylori (H. pylori) is associated with chronic gastritis and gastric carcinogenesis. The effects of nonsteroidal anti-inflammatory drugs (NSAIDs), which exert chemopreventive effects on several cancers, on H. pylori-induced gastritis remain unknown. We investigated the effects of NSAIDs on gastric inflammation and the kinetics of gastric epithelial cells in H. pylori-induced gastritis.

METHODS

Patients with rheumatoid arthritis or osteoarthritis who took NSAIDs for more than 1 month and complained of dyspeptic symptoms were recruited for this study. Patients not on any NSAIDs were included as non-NSAID user controls. All patients underwent diagnostic testing for H. pylori infection, esophagogastroduodenoscopy, and gastric biopsies. Neutrophil infiltration into gastric mucosa, expression of inducible nitric oxide synthase (iNOS), and apoptosis and proliferation of gastric epithelial cells were evaluated by immunohistochemistry. In an in vitro study, the effects of NSAIDs on production of interleukin (IL)-8 induced by H. pylori in a gastric epithelial cell line (AGS) were determined.

RESULTS

Numbers of neutrophils infiltrating the gastric mucosa, iNOS-expressing inflammatory cells and apoptotic cells, and proliferating cells in gastric epithelium were higher in H. pylori-positive groups than H. pylori-negative groups. Among H. pyloripositive groups, these parameters were lower in NSAID users than in non-NSAID users. NSAIDs inhibited the production of IL-8 induced by H. pylori in AGS cells.

CONCLUSIONS

These findings suggest that long-term use of NSAIDs normalizes the kinetics of gastric epithelial cells in patients with H. pylori infection by attenuating gastric mucosal inflammation, which may result in prevention of the gastric carcinogenesis associated with H. pylori infection.

Immune response to Helicobacter pylori and its association with the dynamics of chronic gastritis in the antrum and corpus

The aim of the study was to establish possible factors which play a role in progression of gastritis to atrophic gastritis in long-term follow-up among the Estonian population, to assess the association between the host immune response and different Helicobacter pylori antigens and autoantigens in relation to the histological parameters of gastritis in the antrum and corpus. ELISA and immunoblot were used for detection of IgG to H. pylori acid glycine-extracted cell surface proteins, CagA protein, and H. pylori HSP60. Anticanalicular autoantibodies (ACAB) in the serum were evaluated according to Faller et al. (1996). Apoptosis was evaluated using the TUNEL method. Study subjects were 1958 persons from an unselected Estonian population, and 70 persons from a sample from Saaremaa Island, who had been investigated over a period of 18 years. Seropositivity for CagA was a sign of gastritis activity [OR=14.8 (4.5-50.3)] and atrophy [OR=7.0 (2.1-23.1)] and might predict development of atrophy, particularly in the corpus [OR=7.1 (1.8-27.7)]. The prevalence of ACAB increased significantly with duration of H. pylori gastritis from 22% in 1985 to 46% in 1997 (p=0.004). Immune response to H. pylori HSP60 indicates chronic inflammation in the antrum (p=0.003). Apoptosis of gastric epithelial cells is largely dependent on grade of activity of gastritis, and, particularly in the antrum, on grade of H. pylori colonization (p=0.01; p=0.02), but is not associated with development of atrophy. Seropositivity for different H. pylori antigens (CagA, HSP 60) serves as a marker of different histological manifestations in the antrum and corpus mucosa.

Inhibition of apoptosis in Bacteroides fragilis enterotoxin-stimulated intestinal epithelial cells through the induction of c-IAP-2

Enterotoxigenic Bacteroides fragilis produces an approximately 20-kDa heat-labile enterotoxin (BFT) that plays an essential role in generating mucosal inflammation. Although it is well known that proinflammatory signals are expressed in BFT-stimulated intestinal epithelial cells, cell death processes have not been elucidated. BFT induced apoptosis in HT-29 cells, but the apoptosis was first apparent 36 h after stimulation. During the early period of BFT stimulation, expression of cellular inhibitor of apoptosis protein-2 (c-IAP2) increased, and inhibition of c-IAP2 augmented the apoptotic cell death. Inhibition of BFT-induced COX-2 expression decreased prostaglandin E(2) (PGE(2)) production, which led not only to a decrease of c-IAP2 activity but also to an enhancement of DNA fragmentation in the early period of BFT stimulation. Furthermore, apoptosis inhibition through PGE(2) and c-IAP2 was mainly regulated by a p38 mitogen-activated protein kinase (MAPK). These results suggest that the inhibition of apoptosis may be mediated by a sequential pathway, including MAPK, COX-2, PGE(2) and c-IAP2, in the early period of stimulation. The delay in the onset of epithelial cell apoptosis after enterotoxigenic B. fragilis infection may be important to the host since it can provides sufficient time for epithelial cells to generate signals for the activation of mucosal inflammation and it may increase the chances of bacterial colonization.

Circulating neutrophils may play a role in the host response in cervical cancer

Neutrophil migration is a key event in the inflammatory response of any origin, and neutrophils may present antitumor activity. We investigated the number and function of circulating neutrophils obtained from patients with cervical neoplasia at different stages. Patients with preinvasive (cervical intraepithelial neoplasia, CIN3,n= 6) or microinvasive ([MICRO] stage IA1,n= 4) neoplasia were evaluated together as CIN/MICRO group (n= 10), while patients at stages II–IV were evaluated as invasive group (INV,n= 12). Healthy women served as controls (n= 15). For patients, analysis of leukogram on diagnosis showed a significant elevated neutrophil count in INV group compared with that in CIN/MICRO group. A neutrophil/lymphocyte ratio ≥5 was observed in 67% patients from INV group compared with only 10% from CIN/MICRO group. Neutrophil migration, assayed in a microchemotaxis chamber in response to the chemoattractants (10−7M)N-formyl-L-methionyl-l-leucyl-l-phenylalanine, leukotriene B4, or interleukin-8, was reduced in INV group than in controls or CIN/MICRO group. Surgical treatment in randomly selected patients from CIN/MICRO group (four CIN, one MICRO) increased neutrophil migration to all chemoattractants compared with time on diagnosis. The serum levels of nitric oxide (NO) metabolites, assayed by the Griess reaction, were higher in patients (n= 19) than in controls (n= 15), without differences related to tumor stage, but were reduced in patients after surgery compared with pretreatment (n= 10). Taken together, the results suggest that neutrophils play a role in the host response in cervical cancer. Soluble circulating mediators released by tumor cells, such as NO, could interfere early in the capacity of neutrophils to migrate, thus impairing host immune response.

Effects of lactobacillus on phosphorylated p38 mitogen-activated protein kinase and apoptosis in SGC-7901 cells treated with lipopolysaccharide of Helicobacter pylori

AIM: To investigate effects of lactobacillus bulgaricus (LBG) on the levels of phosphorylated p38 mitogen-activated protein kinase (P-p38MAPK) and apoptosis index (AI) in gastric cancer cell line SGC-7901 treated with lipopolysaccharide of H. pylori Sydney strain 1 (H. pylori SS1-LPS).

METHODS: Human gastric cancer cell line SGC-7901 was treated with H. pylori SS1-LPS at the concentration of 2.5×10³, 2.5×10⁴, 2.5 ×10⁵ EU/L, respectively, after pretreatment for 1 h with 10 mmol/L SB203580 (blocker of p38MAPK) or 1×10¹³ CFU/L LBG. The level of P-p38MAPK was analyzed by immunocytochemistry after 2 h of H. pylori SS1-LPS treatment. The cell activity was detected by MTT assay after 4、5 and 6 h of treatment, and the apoptosis was measured by flow cytometry at the 6^th hour.

RESULTS: H. pylori SS1-LPS inhibited cell activity (0.164 ± 0.028 vs 0.622 ± 0.068, P < 0.05) and up-regulated the level of P-p38MAPK (79.771 ± 1.424 vs 4.075 ± 0.135, P < 0.01) and AI value (10.000% ± 0.510% vs 4.175% ± 0.206%, P < 0.05) in a dose-dependent manner. The level of P-p38MAPK and AI value in SGC-7901 cells were not significantly different between LBG pretreatment group and the controls, and the cell activity and AI value were not markedly different between SB203580 pretreatment group and the controls.

CONCLUSION: H. pylori SS1-LPS may induce the apoptosis of SGC-7901 cells by activating the phosphorylation of p38MAPK, while LBG can prevent H. pylori SS1-LPS-induced apoptosis of SGC-7901 cells by inhibiting the phosphorylation of p38MAPK.

Hydrogenosomal activity of Trichomonas vaginalis cultivated under different iron conditions

To evaluate whether iron concentration in TYM medium influence on hydrogenosomal enzyme gene expression and hydrogenosomal membrane potential of Trichomonas vaginalis, trophozoites were cultivated in irondepleted, normal and iron-supplemented TYM media. The mRNA of hydrogenosomal enzymes, such as pyruvate ferredoxin oxidoreductase (PFOR), hydrogenase, ferredoxin and malic enzyme, was increased with iron concentrations in T. vaginalis culture media, measured by RT-PCR. Hydrogenosomal membrane potentials measured with DiOC6 also showed similar tendency, e.g. T. vaginalis cultivated in iron-depleted and iron-supplemented media for 3 days showed a significantly reduced and enhanced hydrogenosomal membrane potential compared with that of normal TYM media, respectively. Therefore, it is suggested that iron may regulate hydrogenosomal activity through hydrogenosomal enzyme expression and hydrogenosomal membrane potential.

Molecular markers in Helicobacter pylori-associated gastric carcinogenesis

Helicobacter pylori infection is a known risk factor of gastric carcino-genesis. This article presents early molecular alterations associated with H. pylori chronic gastritis and advances in the molecular characterization of preneoplastic intestinal metaplasia (IM) and premalignant gastric mucosal lesions. H. pylori infection induces changes in gene expression, genomic instability and accumulation of gene mutations in the stomach epithelium. Mutations, including LOH and microsatellite instability, and gene hypermethylation are seen not only in gastric cancer, but are already detectable in IM and gastric dysplasia/adenoma. Recent reports using microarray expression analysis identified several gastric epithelial genes that are regulated by H. pylori. Among the many genes showing altered epithelial expression in response to H. pylori, some might be useful as markers to assess gastric cancer risk. Profiles of mutagenesis and gene expression in IM and dysplasia/adenoma have been characterized and represent potential markers of preneoplastic and premalignant lesions during gastric carcinogenesis.

Smoking and the pathogenesis of gastroduodenal ulcer--recent mechanistic update

Peptic ulcer is a common disorder of gastrointestinal system and its pathogenesis is multifactorial, where smoking and nicotine have significant adverse effects. Smoking and chronic nicotine treatment stimulate basal acid output which is more pronounced in the smokers having duodenal ulcer. This increased gastric acid secretion is mediated through the stimulation of H2-receptor by histamine released after mast cell degranulation and due to the increase of the functional parietal cell volume or secretory capacity in smokers. Smoking and nicotine stimulate pepsinogen secretion also by increasing chief cell number or with an enhancement of their secretory capacity. Long-term nicotine treatment in rats also significantly decreases total mucus neck cell population and neck-cell mucus volume. Smoking also increases bile salt reflux rate and gastric bile salt concentration thereby increasing duodenogastric reflux that raises the risk of gastric ulcer in smokers. Smoking and nicotine not only induce ulceration, but they also potentiate ulceration caused by H. pylori, alcohol, nonsteroidal anti-inflammatory drugs or cold restrain stress. Polymorphonuclear neutrophils (PMN) play an important role in ulcerogenesis through oxidative damage of the mucosa by increasing the generation of reactive oxygen intermediates (ROI), which is potentiated by nicotine and smoking. Nicotine by a cAMP-protein kinase A signaling system elevates the endogenous vasopressin level, which plays an aggressive role in the development of gastroduodenal lesions. Smoking increases production of platelet activating factor (PAF) and endothelin, which are potent gastric ulcerogens. Cigarette smoking and nicotine reduce the level of circulating epidermal growth factor (EGF) and decrease the secretion of EGF from the salivary gland, which are necessary for gastric mucosal cell renewal. Nicotine also decreases prostaglandin generation in the gastric mucosa of smokers, thereby making the mucosa susceptible to ulceration. ROI generation and ROI-mediated gastric mucosal cell apoptosis are also considered to be important mechanism for aggravation of ulcer by cigarette smoke or nicotine. Both smoking and nicotine reduce angiogenesis in the gastric mucosa through inhibition of nitric oxide synthesis thereby arresting cell renewal process. Smoking or smoke extract impairs both spontaneous and drug-induced healing of ulcer. Smoke extract also inhibits gastric mucosal cell proliferation by reducing ornithine decarboxylase activity, which synthesises growth-promoting polyamines. It is concluded that gastric mucosal integrity is maintained by an interplay of some aggressive and defensive factors controlling apoptotic cell death and cell proliferation and smoking potentiates ulcer by disturbing this balance.

Neutrophil-Derived TNF-Related Apoptosis-Inducing Ligand (TRAIL)

To detect the novel genes expressed uniquely in neutrophils and elucidate their function, the gene expression pattern was compared by using cDNA microarray containing 240 cytokine genes between the neutrophils and peripheral blood mononuclear cells (PBMCs) obtained from healthy human donors. Twenty-six genes, including tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), were expressed in neutrophils at a level >10 times higher than that seen in phytohemagglutinin-stimulated PBMCs. The amounts of mRNA and protein of TRAIL were quantified by real-time reverse transcription-PCR and ELISA, respectively. TRAIL was expressed in resting neutrophils at the mRNA and protein levels, and its expression was enhanced after stimulation with IFN-gamma. Neutrophils expressed TRAIL on the cell surface and released it into the culture media. The cytotoxicity of neutrophil-derived TRAIL against Jurkat cells was determined by flow cytometry using FITC-conjugated annexin V. When Jurkat cells were cultured with neutrophils in the presence of IFN-gamma, the number of Jurkat cells undergoing apoptosis increased, and such increase depended on the effector:target ratio. This cytotoxicity was suppressed partially by adding anti-TRAIL antibody to the media. Neutrophils may exert their own antitumor effect by TRAIL. A microarray analysis was found to be a useful tool for detecting novel genes that are suggested to play unknown roles in the neutrophil function.

Anti-inflammatory effect of two isoforms of COX in H. pylori-induced gastritis in mice: possible involvement of PGE2

Neutrophil infiltration mediated by TNF-alpha is associated with various types of gastric injury, whereas PGs play a crucial role in gastric defense. We examined roles of two isoforms of cyclooxygenase (COX) and PGE2 in Helicobacter pylori-induced gastritis in mice. Mice infected with H. pylori were given selective COX-1 inhibitor SC-560 (10 mg/kg), selective COX-2 inhibitor NS-398 (10 mg/kg), or nonselective COX inhibitor indomethacin (2 mg/kg) with or without 16,16-dimethyl PGE2 for 1 wk. H. pylori infection increased levels of mRNA for COX-1 and -2 in gastric tissue by 1.2-fold and 3.3-fold, respectively, accompanied by a significant increase in PGE2 production by gastric tissue. H. pylori infection significantly elevated MPO activity, a marker of neutrophil infiltration, and epithelial cell apoptosis in the stomach. SC-560 augmented MPO activity and epithelial cell apoptosis with associated reduction in PGE2 production, whereas NS-398 had the same effects without affecting PGE2 production. Inhibition of both COX-1 and -2 by indomethacin or concurrent treatment with SC-560 and NS-398 resulted in a stronger increase in MPO activity and apoptosis than inhibition of either COX-1 or -2 alone. H. pylori infection elevated TNF-alpha mRNA expression in the stomach, which was further increased by indomethacin. Effects of COX inhibitors on neutrophil infiltration, apoptosis, and TNF-alpha expression in H. pylori-infected mice were abolished by exogenous 16,16-dimethyl PGE2. In conclusion, PGE2 derived from either COX-1 or -2 is involved in regulation of gastric mucosal inflammation and contributes to maintenance of mucosal integrity during H. pylori infection via inhibition of TNF-alpha expression.

Helicobacter pylori infection activates NF-kappaB signaling pathway to induce iNOS and protect human gastric epithelial cells from apoptosis

Helicobacter pylori infection induces apoptosis and inducible nitric oxide synthase (iNOS) expression in gastric epithelial cells. In this study, we investigated the effects of NF-kappaB activation and iNOS expression on apoptosis in H. pylori-infected gastric epithelial cells. The suppression of NF-kappaB significantly increased caspase-3 activity and apoptosis in H. pylori-infected MKN-45 and Hs746T gastric epithelial cell lines as well as primary gastric epithelial cells. An NF-kappaB signaling pathway via NF-kappaB-inducing kinase and IkappaB kinase-beta activation was found to be involved in the inhibition of apoptosis in H. pylori-infected gastric epithelial cells. In gastric epithelial cells transfected with retrovirus containing IkappaBalpha superrepressor, iNOS mRNA and protein levels were reduced, indicating that H. pylori infection induced the expression of iNOS by activating NF-kappaB. Moreover, a NO donor, S-nitroso-N-acetylpenicillamine (100 microM), decreased caspase-3 activity and apoptosis in NF-kappaB-suppressed cells infected with H. pylori. These results suggest that NF-kappaB activation may play a role in protecting gastric epithelial cells from H. pylori-induced apoptosis by upregulating endogenous iNOS.

Inhibition of Helicobacter pylori-induced nuclear factor-kappa B activation and interleukin-8 gene expression by ecabet sodium in gastric epithelial cells

BACKGROUND

Helicobacter pylori stimulates nuclear factor-kappa B (NF-kappa B) activation and chemokine interleukin-8 (IL-8) expression in gastric epithelial cells. Ecabet sodium (ecabet), a locally acting antiulcer drug, is known to have anti-H. pylori activity. However, there is little understanding of how ecabet induces anti-inflammatory activity in gastric epithelial cells infected with H. pylori. The aim of this study was to investigate the effects of ecabet on IL-8 gene expression and NF-kappa B activation in human gastric epithelial cells infected with H. pylori.

MATERIALS AND METHODS

After Hs746T, MKN-45, or SNU-5 gastric epithelial cell lines had been infected with cagA+cytotoxin+H. pylori in the presence of ecabet, IL-8 mRNA expression was assessed by quantitative reverse transcription-polymerase chain reaction, and IL-8 secretion was measured by enzyme-linked immunosorbent assay. NF-kappa B and inhibitory kappa B-alpha (I kappa B alpha) signals were assayed by electrophoretic mobility shift assay and Western blot, respectively. The activation of NF-kappa B and IL-8 reporter genes was determined by luciferase assay.

RESULTS

Ecabet showed no antimicrobial activiy against Gram-positive or -negative bacteria. However, ecabet inhibited transcription of the IL-8 gene and secretion of IL-8 by gastric epithelial cells infected with H. pylori at a concentration of 5 micro g/ml. Moreover, ecabet inhibited the activation of NF- kappa B and the degradation of I kappa B alpha in gastric epithelial cells in response to H. pylori infection. In addition, the NF-kappa B signal inhibited by ecabet was comprised predominantly of heterodimers of p65/p50.

CONCLUSIONS

Ecabet inhibited H. pylori-induced IL-8 gene transcription and secretion by suppressing the NF-kappa B signal. This inhibition might be one pathway by which ecabet exerts its anti-inflammatory effect on H. pylori-induced gastric inflammation.

Tumor necrosis factor alpha and apoptosis in Helicobacter pylori related progressive gastric damage: a possible mechanism of immune system involvement in epithelial turnover regulation

Helicobacter pylori (HP) related inflammation is mediated by tumour necrosis factor alpha (TNFalpha), which "in vitro" increases epithelial apoptosis in response to infection. In the early stages of HP gastritis, a raised epithelial apoptosis occurs; this phenomenon becomes less evident with progression towards intestinal metaplasia. Aim of our study was to analyze "in vivo" mucosal TNFalpha in relation to epithelial apoptosis in the progression of HP related histological damage. Antral biopsies from 20 HP positive patients were retrospectively studied: 10 with and 10 without intestinal metaplasia (IM and CG group respectively); samples of 10 dyspeptics with normal HP negative stomach (N) were used as control. The following parameters were evaluated by immunohistochemistry: 85 kDa caspase-cleaved fragment (p85) of human poly (ADP-ribose) polymerase (PARP) labelling index (LI) as marker of apoptosis and TNFalpha LI in stromal cells as marker of inflammatory response. Both epithelial apoptosis and mucosal TNFalpha expression were higher in chronic active gastritis compared to intestinal metaplasia and controls (PARP and TNFalpha LI: CG > IM > N; ANOVA & Student-Neumann-Keuls; p < 0.05 and p < 0.01, respectively). Pearson's coefficient showed a significant correlation between PARP and TNFalpha LI in IM and CG groups. Our data show that mucosal TNFalpha, similarly to what suggested "in vitro", may be related "in vivo" to epithelial apoptosis thus suggesting a possible mechanism for immune system involvement in the control of gastric epithelial turnover.

Downregulation of caspases and Fas ligand expression, and increased lifespan of neutrophils after transmigration across intestinal epithelium

During inflammatory bowel diseases, commitment of extravased polymorphonuclear leucocytes (PMN) to apoptosis is required for the resolution of inflammation. To investigate the effect of transepithelial migration on PMN apoptotic rates, PMN transepithelial migration was reproduced in vitro using T84 intestinal monolayers. Transepithelial migration was found to delay neutrophil apoptosis, and this survival effect correlated with a downregulation of the surface expression of Fas ligand (FasL) and with a decrease in both procaspases-3, and -8 mRNA and procaspases-3, -6, -7 and -8 protein levels. Moreover, neutrophil survival and FasL shedding mediated by transepithelial migration were abrogated by a broad-spectrum metalloproteinase inhibitor, BB-94. Although Erk1/2 and p38 MAPK were activated in transmigrated PMN, inhibition of these MAP kinases did not impair transmigration-induced PMN survival. Taken together, our results show that trans-epithelial migration induces the downregulation of proapoptotic proteins expression in transmigrated PMN, which results in their increased lifespan.

Identification of novel matrix metalloproteinase-7 (matrilysin) cleavage sites in murine and human Fas ligand

Soluble Fas ligand (sFasL) is released from the cell surface by matrix metalloproteinases (MMPs), one of which is MMP-7. We have reported that MMP-7-generated sFasL is pro-apoptotic in both in vitro and in vivo systems. However, there are contradictory reports that the soluble form of FasL is inactive or anti-apoptotic, resulting in significant controversy in the literature. One potential explanation for these discrepancies is that forms of sFasL with different amino-terminal sequences have been demonstrated to have varying activities. Here we report that MMP-7 cleaves murine and human FasL at sites that are distinct from previously reported cleavage sites resulting in production of novel forms of sFasL. Cleavage of FasL by MMP-7 occurs at the leucine residues in the sequence "ELAELR" within the region between the transmembrane and trimerization domains. When this site is unavailable, a more c-terminal site, "SL," is cleaved. MMP-7 differentially processes murine and human FasL since it cleaves human FasL not only at the "ELAELR" site but also at a previously identified site. Additionally, MMP-3, but not MMP-2, was found to have the same cleavage specificity for murine FasL as MMP-7. We conclude that the controversy regarding the biological activity of sFasL may be explained, in part, by the generation of distinct forms of sFasL as a result of cleavage at specific sequences.

Nuclear factor-kappa B activation pathway in intestinal epithelial cells is a major regulator of chemokine gene expression and neutrophil migration induced by Bacteroides fragilis enterotoxin

Although intestinal epithelial cells are known to up-regulate the expression of several chemokine genes in response to the stimulation with B. fragilis enterotoxin (BFT), there has been little understanding on the cellular mechanisms of BFT-induced mucosal inflammation. To test whether nuclear transcriptional factor-kappa B (NF-kappaB) is involved in the process, we stimulated intestinal epithelial cells with BFT, and evaluated the signalling NF-kappaB pathways. BFT increased signals of NF-kappaB in HT-29 and T84 epithelial cell lines as well as primary human colon epithelial cells. NF-kappaB molecules activated by BFT stimulation were composed of p65 and p50 heterodimers. In contrast, BFT decreased the signals of IkappaBalpha and IkappaB epsilon, as assessed by immunoblot. Super-repressors of IkappaBalpha, IkappaB kinase (IKK)beta, and NF-kappaB inducing kinase (NIK) inhibited an up-regulated transcription of downstream target gene (CXCL8) of NF-kappaB. Moreover, blocking the activation of NF-kappaB by MG-132 or antisense p50 oligonucleotide transfection resulted in down-regulated expression of chemokines such as CXCL1, CXCL8, and CCL2 in BFT-stimulated HT-29 cells. In addition, NF-kappaB inhibition suppressed the BFT-induced neutrophil transepithelial migration in T84 cells. These results indicate that NF-kappaB can be a central regulator of chemokine gene expression in BFT-stimulated intestinal epithelial cells and may be an important regulator of neutrophil migration.

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.

Role of tumor necrosis factor alpha in Helicobacter pylori gastritis in tumor necrosis factor receptor 1-deficient mice

Increased gastric production of interleukin 8 and tumor necrosis factor alpha (TNF-alpha) has been implicated in the pathogenesis of Helicobacter pylori-associated gastroduodenal disease. In the present study we used a mouse model to demonstrate whether loss of the tumor necrosis factor receptor 1 (TNF-R1) function leads to differences in gastric inflammation or the systemic immune response in H. pylori infection. Six different clinical isolates of H. pylori (three cytotoxin-positive and three cytotoxin-negative strains) were adapted to C57BL/6 mice. TNF-R1-deficient (TNF-R1(-/-)) mice (n = 19) and isogenetic controls (n = 24) were infected and sacrificed after 4 weeks of infection. Inflammation of the stomach and the humoral immune response to H. pylori were evaluated by histological, immunohistochemical, and serological methods. There was no detectable difference in the grade or activity of gastritis in TNF-R1(-/-) mice when they were compared with wild-type mice, but the number of lymphoid aggregates was slightly reduced in the gastric mucosa of TNF-R1(-/-) mice. Interestingly, total immunoglobulin G (IgG), as well as IgG1, IgG2b, and IgG3, H. pylori-specific antibody titers were significantly higher in wild-type mice. As revealed by immunoblot analysis, the difference in reactivity against H. pylori antigens was not based on a failure to recognize single H. pylori antigens in TNF-R1(-/-) mice. We therefore suggest that TNF-R1-mediated TNF-alpha signals might support a systemic humoral immune response against H. pylori and that the gastric inflammatory response to H. pylori infection seems to be independent of TNF-R1-mediated signals.

Up-regulation of inducible nitric oxide synthase and nitric oxide in Helicobacter pylori-infected human gastric epithelial cells: possible role of interferon-gamma in polarized nitric oxide secretion

BACKGROUND

Nitric oxide (NO) generated by nitric oxide synthase (NOS) is known to be an important modulator of the mucosal inflammatory response. In this study, we questioned whether Helicobacter pylori infection could up-regulate the epithelial cell inducible NOS (iNOS) gene expression and whether NO production could show polarity that can be regulated by immune mediators.

MATERIALS AND METHODS

Human gastric epithelial cell lines were infected with H. pylori, and the iNOS mRNA expression was assessed by quantitative RT-PCR. NO production was assayed by determining nitrite/nitrate levels in culture supernatants. To determine the polarity of NO secretion by the H. pylori-infected epithelial cells, Caco-2 cells were cultured as polarized monolayers in transwell chambers, and NO production was measured.

RESULTS

iNOS mRNA levels were significantly up-regulated in the cells infected with H. pylori, and expression of iNOS protein was confirmed by Western blot analysis. Increased NO production in the gastric epithelial cells was seen as early as 18 hours postinfection, and reached maximal levels by 24 hours postinfection. The specific MAP kinase inhibitors decreased H. pylori-induced iNOS and NO up-regulation. After H. pylori infection of polarized epithelial cells, NO was released predominantly into the apical compartment, and IL-8 was released predominantly into basolateral compartment. The addition of IFN-gamma to H. pylori-infected polarized epithelial cells showed a synergistically higher apical and basolateral NO release.

CONCLUSION

These results suggest that apical NO production mediated by MAP kinase in H. pylori-infected gastric epithelial cells may influence the bacteria and basolateral production of NO and IL-8 may play a role in the tissue inflammation.

Ubiquitin-proteasome inhibitor enhances tumour necrosis factor-alpha-induced apoptosis in rat gastric epithelial cells

BACKGROUND

Tumour necrosis factor (TNF-alpha) is a candidate factor for involvement in inflammation-mediated gastric mucosal injury. However, the effect of this cytokine on gastric epithelial cells has been poorly investigated. In the present study, we examined whether gastric epithelial cells are resistant to TNF-alpha-induced apoptosis, and whether this resistance is related to ubiquitin-proteasome-associated nuclear factor-kappaB (NF-kappaB) activation.

METHODS

The rat gastric mucosal cell line RGM-1 was grown in DMEM/F12 medium supplemented with 10% FCS. Confluent monolayers of cells were pretreated or not for 60 min with PSI, a peptide aldehyde known to specifically inhibit the chymotrypsin-like activity of 26S proteasome. Cells were subsequently stimulated with recombinant rat TNF-alpha and their viability was determined by WST-1 assay. Apoptosis was confirmed by fluorescence microscopy after staining with Hoechst 33342 and propidium iodide, and DNA fragmentation was determined by flow cytometry using an APO-BRDU kit. IkappaB-alpha and the p65 binding subunit of NF-kappaB were detected by Western blots.

RESULTS

Twenty-four-hour incubation with TNF-alpha alone or PSI alone did not affect the cell viability of RGM-1 cells. Pretreatment with PSI significantly enhanced the level of apoptosis induced by TNF-alpha. In RGM-1 cells treated with TNF-alpha, cytoplasmic IkappaB-alpha decreased and p65 in nuclear extracts increased markedly 30 min after cytokine stimulation. Pretreatment with PSI at 12.5 micromol/L blocked these TNF-alpha-induced changes.

CONCLUSION

PSI enhances TNF-alpha-induced apoptosis through inhibition of NF-kappaB activation in RGM-1 cells.

Helicobacter heilmannii gastritis: a histological and immunohistochemical trait

AIM

Biopsies of the gastric antrum were reviewed over a period of 10 years to determine the prevalence of Helicobacter heilmannii in symptomatic subjects from this geographical area and to relate its presence to distinctive histopathological and immunohistochemical features.

METHODS

Biopsies from 7926 symptomatic patients were reviewed. Ten serial sections were stained with haematoxylin and eosin for conventional histology. Another 10 sections were stained with the Gram method for spiral bacteria. When H heilmannii was suspected, 10 additional serial sections were stained with methylene blue to obtain homogeneous colouring. An equal number of sections from patients affected by isolated H heilmannii or H pylori gastritis were analysed by immunohistochemistry to evaluate lymphoid aggregate/mucosal lymphocyte clonality (CD20 and CD3) and tumour necrosis factor alpha (TNF-alpha) in stromal cells.

RESULTS

The prevalence of H heilmannii was 0.1% (eight of 7926), whereas H pylori was present in 60.7% of patients (4813 of 7926). In two of the eight H heilmannii positive patients both helicobacters were found. In all subjects infected by H heilmannii only, distinctive histology (lymphocyte exudation into gastric foveolae) was seen. Lymphoid aggregates, chronic mucosal inflammation with patchy activity, and the absence of epithelial mucus depletion were regular features of H heilmannii gastritis. Immunohistochemistry did not reveal different lymphocyte clonal patterns between H pylori and H heilmannii gastritis: CD20 positive cells were predominant in the centre of aggregates and mucosal infiltrates, whereas CD3 positive cells were prevalent at the periphery of follicles. Only H pylori gastritis showed a significant increase in TNF-alpha positive stromal cells.

CONCLUSION

These data suggest that an unusual lymphocyte reaction, with the tendency to invade the foveolar lumen, is a distinctive histopathological aspect of H heilmannii chronic gastritis, although further studies in a larger series are necessary to confirm this fact. Nevertheless, lymphocyte clones do not differ qualitatively from those found in H pylori infection. Moreover, compared with H heilmannii, H pylori provokes a more intense release of TNF-alpha, suggesting that different inflammatory responses exist to these two organisms.

Caspase-3 activity and expression of Bcl-2 family in human neutrophils by Helicobacter pylori water-soluble proteins

BACKGROUND

Persistent infiltration of neutrophils is an almost invariable feature of Helicobacter pylori-infected gastric mucosa. A prolongation of neutrophil life-span could contribute to the pathogenesis of H. pylori infection. Recently, we have demonstrated that H. pylori water extracts (HPWE) inhibited neutrophil apoptosis. To elucidate the regulation of intracellular apoptotic signals by HPWE, we examined the activity of caspase-8, -3 and expression of Bcl-2 family in neutrophils.

MATERIALS AND METHODS

Human neutrophils were obtained from the peripheral blood of healthy volunteers by density gradient separation. HPWE was prepared from a supernatant of the H. pylori suspension in distilled water. After neutrophils were incubated with HPWE, expression of Bcl-2 family [antiapoptotic (Bcl-2, Bcl-XL and Mcl-1) and proapoptotic (Bax, Bak and Bcl-XS)] was determined by RT-PCR and Western blotting, respectively. Western blot for Bcl-2 family also performed in neutrophilic differentiated HL-60 cells by all-trans-retinoic acid. The activity of caspase-8, -3 was measured by the detection of p-nitroanilide after cleavage from labeled substrate.

RESULTS

HPWE suppressed the activation of caspase-8 and -3, and upregulated the expression of Bcl-XL mRNA and proteins in neutrophils. The expression of Bax and Bak was upregulated and Bcl-2, Bcl-XL and Mcl-1 downregulated in HL-60 cells during neutrophilic differentiation.

CONCLUSION

Bcl-XL may have an important role in the neutrophilic development and inhibition of neutrophil apoptosis by H. pylori.