Pylori-induced Gastric Mucosal Injury Research Articles

Anti-Inflammatory Effect of Korean Propolis on Helicobacter pylori-Infected Gastric Mucosal Injury Mice Model.

Propolis, a natural resinous substance obtained from a variety of buds and plants, has been reported to possess various biological functions. Several recent studies have demonstrated the inhibitory effects of propolis on the growth of Helicobacter pylori (H. pylori) in vitro; however, current research efforts on Korean propolis (KP) remain insufficient especially in vivo. Our study aims to investigate the anti-inflammatory effect and molecular mechanism of KP on mouse gastric mucosa during H. pylori infection. We examined an in vivo H. pylori-induced gastric mucosal injury mice model. We found that KP inhibited the growth of H. pylori and attenuated the expression of H. pylori virulence factors such as cytotoxin-associated gene A, encoding urease A subunit, surface antigen gene and neutrophil-activating protein A. Moreover, KP reduced both gross lesions and pathological scores in H. pylori-challenged mice. In addition, KP markedly restrained the production of pro-inflammatory cytokines and nitric oxide levels compared with an untreated H. pylori-infected group. In particular, we found that KP repressed the phosphorylation of IκBα and NF-κB p65 subunit, and subsequently suppressed their downstream target genes. Taken together, these findings demonstrate the beneficial effects of KP on inflammation through the inhibition of NF-κB signaling as well as inhibition of H. pylori growth in a mouse model infected with H. pylori. This suggests the potential application of KP as a natural supplement for patient's suffering from gastric mucosal injury caused by H. pylori infection.

Atractylone Alleviates Ethanol-Induced Gastric Ulcer in Rat with Altered Gut Microbiota and Metabolites.

BackgroundGastric ulcer (GU) is the most common multifactor gastrointestinal disorder affecting millions of people worldwide. There is evidence that gut microbiota is closely related to the development of GU. Atractylone (ATR) has been reported to possess potential biological activities, but research on ATR alleviating GU injury is unprecedented.MethodsHelicobacter pylori (H. pylori)-induced GU model in zebrafish and ethanol-induced acute GU model in rat were established to evaluate the anti-inflammatory and ulcer inhibitory effects of ATR. Then, 16S rRNA sequencing and metabolomics analysis were performed to investigate the effect of ATR on the microbiota and metabolites in rat feces and their correlation.ResultsTherapeutically, ATR inhibited H. pylori-induced gastric mucosal injury in zebrafish. In the ulceration model of rat, ATR mitigated the gastric lesions damage caused by ethanol, decreased the ulcer area, and reduced the production of inflammatory factors. Additionally, ATR alleviated the gastric oxidative stress injury by increasing the activity of superoxide dismutase (SOD) and decreasing the level of malondialdehyde (MDA). Furthermore, ATR played a positive role in relieving ulcer through reshaping gut microbiota composition including Parabacteroides and Bacteroides and regulating the levels of metabolites including amino acids, short-chain fatty acids (SCFAs), and bile acids.ConclusionOur work sheded light on the mechanism of ATR treating GU from the perspective of the gut microbiota and explored the correlation between gut microbiota, metabolites, and host phenotype.

Role of the Outer Inflammatory Protein A/Cystine–Glutamate Transporter Pathway in Gastric Mucosal Injury Induced by Helicobacter pylori

INTRODUCTION:Helicobacter pylori infection is a major cause of gastrointestinal diseases. However, the pathogenesis of gastric mucosal injury by H. pylori remains unclear. Exogenous glutamate supplementation protects against gastric mucosal injury caused by H. pylori. Previously, we showed that aspirin-induced gastric injury is associated with reduction in glutamate release by inhibition of cystine–glutamate transporter (xCT) activity. We hypothesized that the xCT pathway is involved in H. pylori-induced gastric mucosal injury. In this study, we tested the activity of xCT and evaluated the regulatory effect of outer inflammatory protein (Oip) A on xCT in H. pylori-induced gastric mucosal injury.METHODS:In the H. pylori-infected mice and cell lines, the activity of xCT and the regulatory effect of microRNA on xCT were tested, and the effect of OipA from H. pylori on xCT activity was observed.RESULTS:The results of in vivo and in vitro experiments showed that H. pylori infection induced gastric mucosal injury. This was accompanied by a reduction in xCT activity, which was attenuated by exogenous glutamate treatment. Furthermore, the expression of miR-30b was upregulated, and miR-30b inhibitors significantly restored xCT activity and gastric mucosal injury caused by H. pylori infection. The OipA, a virulence protein from H. pylori, significantly upregulated the expression levels of miR-30b and inhibited xCT activity.DISCUSSION:OipA plays a significant role in H. pylori-induced gastric mucosal injury, and the effects are mediated by micro30b/xCT pathway.

Gastric Carcinogenesis and Underlying Molecular Mechanisms: Helicobacter pylori and Novel Targeted Therapy.

The oxygen-derived free radicals that are released from activated neutrophils are one of the cytotoxic factors of Helicobacter pylori-induced gastric mucosal injury. Increased cytidine deaminase activity in H. pylori-infected gastric tissues promotes the accumulation of various mutations and might promote gastric carcinogenesis. Cytotoxin-associated gene A (CagA) is delivered into gastric epithelial cells via bacterial type IV secretion system, and it causes inflammation and activation of oncogenic pathways. H. pylori infection induces epigenetic transformations, such as aberrant promoter methylation in tumor-suppressor genes. Aberrant expression of microRNAs is also reportedly linked to gastric tumorogenesis. Moreover, recent advances in molecular targeting therapies provided a new interesting weapon to treat advanced gastric cancer through anti-human epidermal growth factor receptor 2 (HER-2) therapies. This updated review article highlights possible mechanisms of gastric carcinogenesis including H. pylori-associated factors.

Role of DC-SIGN in Helicobacter pylori infection of gastrointestinal cells

H. pylori causes gastritis and increases the risk of gastric ulcer and gastric cancer. However, it was recently shown that H. pylori provides protection against inflammatory bowel diseases. To assess the molecular mechanism of such functions, we studied the role of DC-SIGN in H. pylori-infected gastrointestinal epithelial cells. DC-SIGN was found to be over-expressed in the gastric epithelial cells infected with H. pylori and mediated Th1 differentiation, which may be involved in H. pylori-induced gastric mucosal injury. In addition, DC-SIGN was also up-regulated in the intestinal epithelial cells derived from colitis mouse model, but the expression levels were blocked upon H. pylori infection, indicating that H. pylori infection may reduce both local and systemic inflammatory responses. In conclusion, we propose that gastrointestinal epithelial cells infected with H. pylori may lead to acquiring of immune properties via a trans-differentiation process, and regulate tissue-associated immune compartments under the control of DC-SIGN.

Effect of teprenone on gastric mucosal injury induced by Helicobacter pylori in rats.

The aim of this study was to investigate the protective effect of gastric mucus against Helicobacter pylori-induced gastric mucosal injury, measuring intramucosal mucus and the surface hydrophobicity. Male Sprague-Dawley rats' stomachs were exposed to H. pylori suspension (1 x 10(5) ml) plus 1 ml of urea solution (400 mg/dl) with gastric ischemia (withdrawal of 3 ml of blood) for 60 min, 60 min after pretreatment with teprenone (CAS 6809-52-5) (50 mg/rat, intragastric). The control rats were treated in the same manner without pretreatment with teprenone. A high concentration of intragastric ammonia was generated 60 min after administration of H. pylori plus urea in both the control and the teprenone-pretreated rats. A reduction in transmucosal potential difference, formation of hemorrhagic gastric lesions, and impairment in both intramucosal mucus and surface hydrophobicity were observed in the corpus of the control rats. However, the pretreatment with teprenone prevented such a reduction in potential difference and the development of gastric lesions against ammonia through the preservation of gastric mucus. The preservation of gastric mucus might protect gastric mucosa against attacks by H. pylori, suggesting that the mechanism of H. pylori-associated gastric injury is associated with the decrease in gastric mucus.

Artemisia asiatica extracts protect against ethanol‐induced injury in gastric mucosa of rats

Based on our previous studies that Artemisia asiatica extracts exert either antioxidative or cytoprotective actions against non-steroidal anti-inflammatory drugs or Helicobacter pylori-induced gastric mucosal injury, or imposes qualified ulcer healing in an acetic acid-induced gastric ulcer model, we investigated the protective effects of Artemisia asiatica extracts against ethanol-induced gastric mucosal injury. Sprague-Dawley rats received 4 g/kg body weight (BW) of absolute ethanol intragastrically, which produced visible hemorrhagic gastric lesions 60 min later. In this animal setting, the pretreatment of Artemisia extracts (30 or 100 mg/kg BW), 1 h before ethanol administration, significantly attenuated the source of gastric injury, which was assessed with gross and microscopic analysis (P < 0.01). Protection from alcohol-induced damage with Artemisia pretreatment was associated with significantly decreased lipid peroxidation, protecting gastric mucosa from glutathione depletion, as well as the inhibition of the cytochrome 2E1 ethanol-metabolizing enzyme. It attenuated the expressions of ethanol-induced pro-inflammatory cytokines, including interleukin (IL)-1beta and interferon-gamma, a weak activation of IL-10, the inhibition of the alcohol-induced overexpression of intercellular adhesion molecule-1, and the considerable induction of heat shock protein-72 expression in gastric mucosal homogenates. The data suggest that the ethanol extracts of Artemisia asiatica exerted significant protection from alcohol-induced gastric mucosal injury through bio-regulation, which is essential for cytoprotection and anti-inflammation.

Peroxiredoxin I protects gastric mucosa from oxidative injury induced by H. pylori infection

Helicobacter pylori (H. pylori) infection enhances the production of reactive oxygen species and peroxynitrite, thereby resulting in oxidative tissue damage. In this study, we examined the role of peroxiredoxin I (Prx I), a stress-induced antioxidant enzyme, in protecting gastric mucosa from H. pylori-induced gastric mucosal injury. Wild type (Prx I(+/+)) and Prx I-deficient type (Prx I(-/-)) mice were maintained for 2 to 12 months with or without infection of H. pylori, Sydney strain-1. Gastric mucosal expression of Prx I was assessed by immunoblot analysis and immunohistochemistry. The degree of gastritis was evaluated by the updated Sydney system and by mucosal levels of inflammatory cytokines (MIP-2, IL-1beta, and TNF-alpha). Oxidative DNA injury and apoptosis were analyzed by mucosal level of 8-hydroxy-2'-deoxyguanosine, and the number of apoptotic cells stained with a single-stranded DNA antibody, respectively. H. pylori infection upregulated gastric mucosal Prx I expression in the Prx I(+/+) but not the Prx I(-/-) mice. H. pylori infection also induced more severe gastritis and a more prominent increase in MIP level, more marked oxidative DNA injury, and apoptosis in the Prx I(-/-) than the Prx I(+/+) mice. In the absence of H. pylori infection, no changes were demonstrated in gastric mucosa in either the Prx I(+/+) or the Prx I(-/-) mice. These data suggest that H. pylori infection upregulates gastric mucosal Prx I expression, and further, that Prx I plays an important role in gastric mucosal protection against oxidative injury induced by H. pylori infection.

Use of egg yolk-derived immunoglobulin as an alternative to antibiotic treatment for control of Helicobacter pylori infection.

The present study evaluated the potential use of immunoglobulin prepared from the egg yolk of hens immunized with Helicobacter pylori (immunoglobulin Y [IgY]-Hp) in the treatment of H. pylori infections. The purity of our purified IgY-Hp was 91.3%, with a yield of 9.4 mg of IgY per ml of egg yolk. The titer for IgY-Hp was 16 times higher than that for IgY in egg yolk from nonimmunized hens, and IgY-Hp significantly inhibited the growth and urease activity of H. pylori in vitro. Bacterial adhesion on AGS cells was definitely reduced by preincubation of both H. pylori (10(8) CFU/ml) and 10 mg of IgY-Hp/ml. In Mongolian gerbil models, IgY-Hp decreased H. pylori-induced gastric mucosal injury as determined by the degree of lymphocyte and neutrophil infiltration. Therefore, in this experimental model, H. pylori-associated gastritis could be successfully treated by orally administered IgY-Hp. The immunological activity of IgY-Hp stayed active at 60 degrees C for 10 min, suggesting that pasteurization can be applied to sterilize the product. Fortification of food products with this immunoglobulin would significantly decrease the H. pylori infection. In conclusion, the IgY-Hp obtained from hens immunized by H. pylori could provide a novel alternative approach to treatment of H. pylori infection.

NSAIDs counteractH. pyloriVacA toxin-induced cell vacuolation in MKN 28 gastric mucosal cells

The relationship between nonsteroidal anti-inflammatory drugs (NSAIDs) and Helicobacter pylori-induced gastric mucosal injury is still under debate. VacA toxin is an important H. pylori virulence factor that causes cytoplasmic vacuolation in cultured cells. Whether and how NSAIDs affect VacA-induced cytotoxicity is unclear. This study was designed to evaluate the effect of NSAIDs on H. pylori VacA toxin-induced cell vacuolation in human gastric mucosal cells in culture (MKN 28 cell line). Our data show that 1) NSAIDs (indomethacin, aspirin, and NS-398) inhibit VacA-induced cell vacuolation independently of inhibition of cell proliferation and prostaglandin synthesis; 2) NSAIDs impair vacuole development/maintenance without affecting cell binding and internalization of VacA; and 3) NSAIDs, as well as the chloride channel blocker 5-nitro-2-(3-phenylpropylamino) benzoic acid, also inhibit cell vacuolation induced by ammonia. We thus hypothesize that NSAIDs might protect MKN 28 cells against VacA-induced cytotoxicity by inhibiting VacA channel activity required for vacuole genesis.

Effect of Helicobacter pylori-mediated inflammation on nonsteroidal anti-inflammatory drugs-induced gastric mucosal injury.

Helicobacter pylori (H. pylori) infection and nonsteroidal anti-inflammatory drugs (NSAIDs) are two major causes of gastric ulceration, but relation between H. pylori infection and use of these drugs in gastric mucosal injury is controversial. Neutrophils have been implicated in the pathogenesis of gastric mucosal damage induced by H. pylori or NSAIDs. H. pylori itself and H. pylori extract induce neutrophil activation, such as superoxide production, expression of adhesion molecule (CD11b/CD18) and transendothelial migration, capillary plugging. Several clinical and experimental studies demonstrated that the degree of H. pylori-induced gastric mucosal injury was closely correlated with the extents of H. pylori infection and of neutrophil infiltration, suggesting implication in extravascular neutrophils for H. pylori-induced gastric mucosal injury. On the other hand, aspirin promotes neutrophil-endothelial adhesive interactions via increasing CD11b/CD18, but not neutrophil migration to extravascular space. In addition, our recent in vivo study suggests that neutrophils adhering to the blood vessels, but not neutrophils migrating to the interstitium, are implicated in aspirin-induced gastric mucosal injury. Recently, we found that administration of aspirin to gerbils three weeks after H. pylori inoculation produced severe gastric mucosal injury via marked infiltration of neutrophils. In this animal model, pretreatment with anti-neutrophil serum, elastase inhibitor or scavengers of reactive oxygen species remarkably inhibited gastric mucosal injury. These results suggest that H. pylori infection potentiates aspirin-induced gastric mucosal injury by mechanisms that include accumulation of activated neutrophils.

Gastric Mucosal Damage Caused by Monochloramine in the Rat and Protective Effect of Taurine: Endoscopic Observation Through Gastric Fistula

The mechanism of Helicobacter pylori-induced gastric mucosal injury is unknown, but H. pylori infection is conducive to accumulation in the stomach of monochloramine, a cytotoxic substance. The present study involved morphological investigation of the damaging effects of monochloramine on rat gastric mucosa, using endoscopic observations through a gastric fistula. The study also examined the protective effect of taurine against monochloramine-induced gastric mucosal lesions in rats. The effects of monochloramine in rats were studied by administering the substance via a gastrostomy, which was then used to conduct a series of endoscopic observations. Local blood flow was measured using a laser Doppler method. Histological examination was carried out after 24 hours. Various monochloramine concentrations were used, and some animals were pretreated with taurine, a monochloramine scavenger, via the gastrostomy. Endoscopically, monochloramine was found to produce hemorrhagic mucosal erosions, mainly in the gastric body, in a time-dependent and concentration-dependent manner. Blood flow was decreased in advance of mucosal erosion. Taurine prevented mucosal injury by 30 mM monochloramine, the highest concentration tested. Although only the first 24 hours of mucosal injury were observed in the present study, the most likely mechanisms by which monochloramine caused injury to the gastric mucosa appeared to be both oxidative damage and a reduction in blood flow, impairing the mucosal defense mechanism.

Effect of vitamin E on Helicobacter pylori-induced gastric mucosal injury

Effect of vitamin E on Helicobacter pylori-induced gastric mucosal injury

Role of Rebamipide on Induction of Heat-Shock Proteins and Protection Against Reactive Oxygen Metabolite-Mediated Cell Damage in Cultured Gastric Mucosal Cells

Reactive oxygen metabolites (ROM) have been reported to be important in the pathogenesis of ischemia/reperfusion-, ethanol-, nonsteroidal antiinflammatory drug-, or Helicobacter pylori-induced gastric mucosal injury. Rebamipide, a novel antiulcer agent, has been reported either to prevent various acute experimental gastric mucosal lesions or to accelerate the healing of chronic gastric ulcers. The underlying mechanism by which rebamipide exerts its cytoprotective effect in the damaged stomach is not fully determined. We investigated the role of rebamipide in protecting against ROM-mediated cell damage in gastric mucosal cells and in inducing cytoprotective proteins. Cells were exposed to ROM enzymatically generated by hypoxanthine-xanthine oxidase. Cytotoxicity was quantified by measuring specific 51Cr release from prelabeled cells. ROM caused dose-dependent increase in cytotoxicity and amount of thiobarbituric acid-reactive substances (TBA-RS). ROM-induced cytotoxicity and TBA-RS were dose-dependently decreased by the addition of rebamipide and/or catalase, but not by superoxide dismutase alone. The effects of rebamipide on electric spin resonance signal were investigated. We found that the DMPO spin adduct ESR signal of hydroxyl radicals (DMPO-OH) was significantly attenuated by rebamipide. Western blot analysis showed that induction of heat-shock protein (HSP70) was significantly increased following rebamipide administration in a dose-dependent manner. Based on these results, it is concluded that rebamipide exerted a protective effect on HX-XO-induced gastric mucosal cell cytotoxicity through one or more of the following mechanism(s): (1) inhibition of lipid peroxidation of the cell membrane; (2) hydroxyl radical scavenging activity; and (3) induction of cellular cytoprotective protein such as HSP70.Copyright © 1997 Elsevier Science Inc.

Helicobacter pylori-associated ammonia production enhances neutrophil-dependent gastric mucosal cell injury.

The role of neutrophil and its chlorinated oxidant were investigated in Helicobacter pylori-induced gastric mucosal injury in vitro. Luminol-dependent chemiluminescence (ChL) was used to detect neutrophil-derived oxidants. ChL activity was significantly elevated when neutrophils were incubated in H. pylori, indicating that H. pylori actually elicits oxidative burst of neutrophils. To assess whether H. pylori-activated neutrophils exert the cytotoxicity for gastric mucosal cells, rabbit gastric mucosal cell was monolayered in culture wells and labeled with a fluorescence dye, 2',7'-bis(2-carboxyethyl)-5(6)carboxy-fluorescein, which is retained in the intracellular space as long as the cell membrane is intact. Labeled cells were coincubated with neutrophils and H. pylori. We inferred from the cytotoxicity index (specific %cytotoxicity), which was calculated from fluorometrical measurements of supernatant and lysate, that the mucosal cells were significantly damaged by H. pylori-activated neutrophils. This injury was largely attenuated by eliminating urea from the incubation mixture or by acetohydroxamic acid, a potent urease inhibitor. Additionally, the scavengers of neutrophil-derived oxidants, including taurine, methionine, and catalase, also attenuated this injury. Cultured mucosal cells that were exposed to the solution containing monochloramine (an oxidant yielded by reaction of hypochlorous acid and ammonia) were highly damaged compared with cells exposed to hypochlorous acid or hydrogen peroxide at physiological concentrations. These data suggest that H. pylori-activated neutrophils promote gastric mucosal cell injury and that monochloramine plays a unique and important role in this process.

Mechanism of gastric mucosal damage induced by ammonia

The mechanism for Helicobacter pylori-induced gastric mucosal injury remains obscure. H. pylori has high urease activity to produce ammonia from urea in the stomach. In this study, the effects of ammonia on (a) gastric mucosal integrity, (b) gastric mucosal hemodynamics, (c) mucosal cellular viability, (d) mitochondrial respiration, and (e) energy metabolism of gastric mucosa were investigated. Ammonia (pH 10.3) at concentrations of >125 mmol/L caused acute macroscopic gastric mucosal lesions in a dose-dependent manner, whereas glycine-NaOH buffer (pH 10.3) or ammonium chloride (pH 4.5) did not. The decrease in energy charge preceded the occurrence of gastric mucosal lesions, but ammonia caused no change in mucosal hemodynamics. Oxygen consumption of isolated cells and mitochondria of gastric mucosa was inhibited by ammonia dose-dependently. The present results indicate that ammonia impairs mitochondrial and cellular respiration and energy metabolism and that ammonia decreases mucosal cell viability, leading subsequently to mucosal damage.