Association of 72-kDa heat shock protein expression with adaptation to aspirin in rat gastric mucosa

Cashew apple byproduct: Gastroprotective effects of standardized extract

ETHNOPHARMACOLOGICAL RELEVANCE

The incidence of gastric mucosa lesions in the adult population has increased mainly due to the continued use of nonsteroidal anti-inflammatory drugs (NSAIDs). The cashew (Anacardium occidentale L.) is a tropical tree, cultivated in several countries, whose barks, leaves and pseudofruit (cashew apple) are popularly used in traditional medicine for the treatment of many diseases, including gastric ulcer.

AIM

Our study evaluated the potential gastroprotective effect of the carotenoid and anacardic acids-enriched aqueous extract (CAE), prepared from cashew apple pomace, in the dose-repeated acetylsalicylic acid (ASA)-induced gastric lesions model in rats.

MATERIAL AND METHODS

After randomly distribution into five group (G1 - G5, n = 8 animals/group), male Wistar rats were daily treated with ASA solution (200 mg/kg, 5 ml/kg, G2 - G5) or potable water (Satellite group, G1) during 14 days. From 8th to 14th experimental day, rats in G3 - G5 groups were orally treated with CAE (50, 100 and 500 mg/kg, 5 ml/kg, respectively). Body weight was measured on 0, 7th and 14th day. On the 14th experimental day, all surviving animals were euthanized for macroscopic evaluation of the inner organs and stomach removal. After weighting, each stomach was properly prepared for biochemical analysis [myeloperoxidase activity (MPO), reduced glutathione analysis (GSH), IL-1β, CXCL2/MIP-2, TNF-α and IL-10 levels].

RESULTS

At the most efficient dose (100 mg/kg, p.o.), CAE-treated animals showed a slight improvement in the macroscopic aspect of gastric mucosa associated with significant (p < 0.05) reduced levels of IL-1β, CXCL2/MIP-2, and MPO activity besides increased levels of GSH (partially), and IL-10 in stomach tissues.

CONCLUSIONS

The present study demonstrated that the carotenoid and anacardic acids-enriched extract obtained from cashew apple pomace is a promising raw material for the development of herbal medicine and/or functional food supplements for the adjuvant treatment of NSAIDs-induced gastric ulcers.

Apoptosis in response to heat stress is positively associated with heat-shock protein 90 expression in chicken myocardial cells in vitro

To determine heat-shock protein (Hsp)90 expression is connected with cellular apoptotic response to heat stress and its mechanism, chicken (Gallus gallus) primary myocardial cells were treated with the Hsp90 promoter, aspirin, and its inhibitor, geldanamycin (GA), before heat stress. Cellular viability, heat-stressed apoptosis and reactive oxygen species level under different treatments were measured, and the expression of key proteins of the signaling pathway related to Hsp90 and their colocalization with Hsp90 were detected. The results showed that aspirin treatment increased the expression of protein kinase B (Akt), the signal transducer and activator of transcription (STAT)-3 and p-IKKα/β and the colocalization of Akt and STAT-3 with Hsp90 during heat stress, which was accompanied by improved viability and low apoptosis. GA significantly inhibited Akt expression and p-IKKα/β level, but not STAT-3 quantity, while the colocalization of Akt and STAT-3 with Hsp90 was weakened, followed by lower cell viability and higher apoptosis. Aspirin after GA treatment partially improved the stress response and apoptosis rate of tested cells caused by the recovery of Akt expression and colocalization, rather than the level of STAT-3 (including its co-localization with Hsp90) and p-IKKα/β. Therefore, Hsp90 expression has a positive effect on cellular capacity to resist heat-stressed injury and apoptosis. Moreover, inhibition of Hsp90 before stress partially attenuated its positive effects.

The association of Hsp90 expression induced by aspirin with anti-stress damage in chicken myocardial cells

The protective effect of aspirin during exposure to heat stress in broiler chickens was investigated. We assayed pathological damage, expression and distribution of Hsp90 protein and hsp90 mRNA expression in chicken heart tissues after oral administration of aspirin following exposure to high temperature for varying times. Heat stress induced increases in plasma aspartate aminotransferase, creatine kinase and lactate dehydrogenase activities while causing severe heart damage, which was characterized by granular and vacuolar degeneration, nuclear shrinkage and even myocardium fragmentation in cardiac muscle fibers. After aspirin administration, myocardial cells showed fewer pathological lesions than broilers treated with heat alone. A high positive Hsp90 signal was always detected in the nuclei of myocardial cells from broilers treated with aspirin, while in myocardial cells treated with heat alone, Hsp90 in the nuclei decreased, as did that in the cytoplasm. Aspirin induced rapid and significant synthesis of Hsp90 before and at the initial phase of heat stress, and significant expression of hsp90 mRNA was stimulated throughout the experiment when compared with cells exposed to heat stress alone. Thus, specific pre-induction of Hsp90 in cardiovascular tissue was useful for resisting heat stress damage because it produced stable damage-related enzymes and fewer pathologic changes.

Cloning HSP70 and HSP90 genes of kaluga (Huso dauricus) and the effects of temperature and salinity stress on their gene expression

The genes encoding HSP70 and HSP90 proteins were isolated from kaluga by homologous cloning and rapid amplification of complementary DNA (cDNA) ends (RACE). HSP70 (GenBank accession no. KP050541) and HSP90 (GenBank accession no. KP050542) cDNAs were composed of 2275 and 2718 bp and encoded polypeptides of 650 and 725 amino acids, respectively. Basic Local Alignment Search Tool (BLAST) analysis showed that HSP70 and HSP90 of kaluga shared high identities with those of Acipenser ruthenus, Acipenser schrenckii, and Acipenser baerii (98-99 %). Fluorescent real-time RT-PCR under unstressed conditions revealed that HSP70 and HSP90 were expressed in 11 different tissues of kaluga. Messenger RNA (mRNA) expressions of both HSP70 and HSP90 were highest in the intestine and lowest in the muscle. In addition, the patterns of mRNA expression of HSP70 and HSP90 were similar, although the level of expression was more in HSP90 than in HSP70 (P < 0.05).We also analyzed patterns of HSP70 and HSP90 expression in the muscle, gill, and liver of kaluga under different combinations of temperature and salinity stress, including temperatures of 4,10, 25, and 28 °C at 0 ppt salinity, and salinities of 10, 20, 30, and 40 ppt at 16 °C, where 16 °C at 0 ppt (parts per thousand) served as the control. We found that levels of mRNA expression of both HSP70 and HSP90 were highest at 4 °C in the muscle, gill, and liver and changed little with salinity stress. These results increase understanding of the mechanisms of stress response of cold freshwater fish.

Dry state preservation of nucleated cells: progress and challenges

Effective stabilization of nucleated cells for dry storage would be a transformative development in the field of cell-based biosensors and biotechnologic devices, as well as regenerative medicine and other areas in which stem cells have clinical utility. Ultimately, the tremendous promise of cell-based products will only be fully realized when stable long-term storage becomes available without the use of liquid nitrogen and bulky, energetically expensive freezers. Significant progress has been made over the last 10 years toward this goal, but obstacles still remain. Loading cells with the protective disaccharide trehalose has been achieved by several different techniques and has been shown to increase cell survival at low water contents. Likewise, the protective effect of heat shock proteins and other compounds have also been explored alone and in combination with trehalose. In some cases, the benefit of these molecules is seen not initially upon rehydration, but over time during cellular recovery. Other considerations, such as inhibiting apoptosis and utilizing isotonic buffer conditions have also provided stepwise increases in cell viability and function following drying and rehydration. In all these cases, however, a low level of residual water is required to achieve viability after rehydration. The most significant remaining challenge is to protect nucleated cells such that this residual water can be safely removed, thus allowing vitrification of intra- and extracellular trehalose and stable dry state storage at room temperature.

Heat Shock Proteins: Intestinal Gatekeepers that Are Influenced by Dietary Components and the Gut Microbiota

Trillions of microorganisms that inhabit the intestinal tract form a diverse and intricate ecosystem with a deeply embedded symbiotic relationship with their hosts. As more detailed information on gut microbiota complexity and functional diversity accumulates, we are learning more about how diet-microbiota interactions can influence the immune system within and outside the gut and host health in general. Heat shock proteins are a set of highly conserved proteins that are present in all types of cells, from microbes to mammals. These proteins carry out crucial intracellular housekeeping functions and unexpected extracellular immuno-regulatory features in order to maintain the mucosal barrier integrity and gut homeostasis. It is becoming evident that the enteric microbiota is one of the major determinants of heat shock protein production in intestinal epithelial cells. This review will focus on the interactions between diet, gut microbiota and their role for regulating heat shock protein production and, furthermore, how these interactions influence the immune system and the integrity of the mucosal barrier.

Cloning and expression analysis of a HSP70 gene from Korean rockfish (Sebastes schlegeli)

The gene encoding HSP70 was isolated from Korean rockfish Sebastes schlegeli by homologous cloning and rapid amplification of cDNA ends (RACE). The full-length of HSP70 cDNA was composed of 2259 bp and encoded a polypeptide of 639 amino acids. BLAST analysis showed that HSP70 of S. schlegeli shared high identities with those of the Lates calcarifer, Oreochromis niloticus, Seriola quinqueradiata HSP70s (88-89%). Our current study also revealed that HSP70 of Korean rockfish was expressed in many tissues by RT-PCR under unstressed condition. Quantitative real-time PCR showed that the expression patterns of Korean rockfish HSP70 were developmental stage-dependency. The expression of HSP70 was measured by quantitative real-time PCR after different oxygen treatments. The results showed that expression of HSP70 increased significantly after exposure to hypoxia for 30 min in gill and ovary, and then decreased for 60 min, and the level in spleen and liver gradually increased and reached the highest at 60 min. In addition, in gill, spleen and liver, the HSP70 mRNA level reached the maximum in hypoxia group after one hour different oxygen concentration stress. Increased amounts of serum thyroxine (T4), and triiodothyronine (T3) were also found during 30 min hypoxia treatment and 60 min normoxia group in our study. All of the results provide information to further study the mechanism of physiology and immune function under stress conditions of ovoviviparous teleosts.

Mechanisms of Gastroprotective Effects of Ethanolic Leaf Extract of Jasminum sambac against HCl/Ethanol-Induced Gastric Mucosal Injury in Rats

Jasminum sambac is used in folk medicine as the treatment of many diseases. The aim of the present investigation is to evaluate the gastroprotective effects of ethanolic extracts of J. sambac leaves against acidified ethanol-induced gastric ulcers in rats. Seven groups of rats were orally pre-treated with carboxymethylcellulose (CMC) as normal group, CMC as ulcer group, 20 mg/kg of omeprazole as positive group, 62.5, 125, 250, and 500 mg/kg of extract as the experimental groups, respectively. An hour later, CMC was given orally to normal group and acidified ethanol solution was given orally to the ulcer control, positive control, and the experimental groups. The rats were sacrificed after an hour later. Acidity of gastric content, the gastric wall mucus, ulcer areas, and histology and immunohistochemistry of the gastric wall were assessed. Gastric homogenates were determined for prostaglandin E₂ (PGE₂), superoxide dismutase (SOD), andmalondialdehyde (MDA) content. Ulcer group exhibited significantly severe mucosal injury as compared with omeprazole or extract which shows significant protection towards gastric mucosal injury the plant promotes ulcer protection as it shows significant reduction of ulcer area grossly, and histology showed marked reduction of edema and leucocytes infiltration of submucosal layer compared with ulcer group. Immunohistochemistry showed overexpression of Hsp70 protein and downexpression of Bax protein in rats pretreated with extract. Significant increased in the pH, mucus of gastric content and high levels of PGE₂, SOD and reduced amount of MDA was observed.

Effects of transportation on expression of Hsp90, Hsp70, Hsp27 and αB-crystallin in the pig stomach

Twenty pigs were randomly divided into four groups based on the amount of time spent in transport (zero, one, two or four hours). Pathological examination of all transported pigs showed that exfoliation of chief cells from the gastric surface occurred in pigs during transportation. These results imply that integrity of the gastric mucosa was compromised by damage occurring during the four-hour transportation, despite the fact that gastric ulcers were not present. Levels of Hsp90 expression in stomach tissues were significantly decreased (P<0.01) after two-hour transportation, but Hsp70 levels increased significantly (P<0.05) after one, two and four hours of transportation. Hsp27 levels remained relatively stable independent of the length of transport. Levels of αB-crystallin expression in the stomach were significantly increased (P<0.05) after four hours of transportation. Variations in Hsp90, Hsp70, Hsp27 and αB-crystallin levels suggest that distinct protective functions are modulated by different Hsps in stomach tissues during transportation. Alterations in Hsp70 and αB-crystallin expression appear to be associated with protective functions, as no apparent gastric ulcers were present in pigs that underwent four hours of transportation. Levels of heat shock transcription factor-1, which regulate the expression of Hsps, remained relatively stable independent of the transportation period.

Traditional Herbal Medicine, Rikkunshito, Induces HSP60 and Enhances Cytoprotection of Small Intestinal Mucosal Cells as a Nontoxic Chaperone Inducer

Increasing incidence of small intestinal ulcers associated with nonsteroidal anti-inflammatory drugs (NSAIDs) has become a topic with recent advances of endoscopic technology. However, the pathogenesis and therapy are not fully understood. The aim of this study is to examine the effect of Rikkunshito (TJ-43), a traditional herbal medicine, on expression of HSP60 and cytoprotective ability in small intestinal cell line (IEC-6). Effect of TJ-43 on HSP60 expression in IEC-6 cells was evaluated by immunoblot analysis. The effect of TJ-43 on cytoprotective abilities of IEC-6 cells against hydrogen peroxide or indomethacin was studied by MTT assay, LDH-release assay, caspase-8 activity, and TUNEL. HSP60 was significantly induced by TJ-43. Cell necrosis and apoptosis were significantly suppressed in IEC-6 cells pretreated by TJ-43 with overexpression of HSP60. Our results suggested that HSP60 induced by TJ-43 might play an important role in protecting small intestinal epithelial cells from apoptosis and necrosis in vitro.

Evidence for enhanced cytoprotective function of HSP90-overexpressing small intestinal epithelial cells

BACKGROUND

In the clinical field, increasing incidence of small intestinal ulcers associated with nonsteroidal anti-inflammatory drugs (NSAIDs) has become a topic with the advances of capsule endoscopy and balloon enteroscopy technology for the detection of small intestinal lesions. However, the pathogenesis of NSAID-induced mucosal damage, defensive mechanism of intestinal epithelial cells, and therapy for small intestinal mucosal lesion have not been fully understood. Heat shock proteins (HSPs) are involved in cytoprotection mediated by their function as a molecular chaperone. Since the function of HSP90 in the intestinal epithelial cells has not been well investigated, we examined the cytoprotective ability of HSP90-overexpressing small intestinal epithelial cells against hydrogen peroxide-induced or indomethacin-induced cell damage.

METHODS

cDNA of human HSP90 gene was transfected to rat small intestinal epithelial cells (IEC-6 cells), and HSP90-overexpressing cells (IEC-6-90 cells) were selected and cloned. Anti-necrotic abilities and anti-apoptotic abilities of IEC-6-90 cells were compared with IEC-6-mock cells (transfected with vector alone). To examine the specific contribution of HSP90 on cytoprotection of IEC-6-90 cells, cytoprotective ability of IEC-6-90 cells was analyzed with or without pretreatment with functional inhibitor of HSP90, geldanamycine analog, followed by hydrogen peroxide-challenge or indomethacin-challenge.

RESULTS

Hydrogen peroxide-induced or indomethacin-induced cell necrosis and apoptosis were significantly suppressed in IEC-6-90 cells. The cytoprotective ability of IEC-6-90 cells was suppressed by HSP90 inhibitor.

CONCLUSIONS

Our results suggest that HSP90 might play an important role in protecting small intestinal epithelial cells from hydrogen peroxide-induced or indomethacin-induced cell injury in vitro, and raised the possibility of protection of small intestinal epithelial cells by manipulation of HSP90 expression.

Acid pump antagonist-provoked HSP27 dephosphorylation and accentuation rescues stomach from indomethacin-induced damages

OBJECTIVE

Heat shock proteins (HSPs) are crucial for the maintenance of cellular integrity during normal cell growth as well as pathophysiological conditions. While acting as molecular chaperones with their folding activities, HSPs play a cytoprotective role to rescue epithelial cells from several gastric damages including non-steroidal anti-inflammatory drugs (NSAIDs) and Helicobacter pylori. Since the exact relationship between HSP27 phosphorylation and biological function remains unknown in NSAID-induced gastropathy, we hypothesized that revaprazan, a novel acid pump antagonist, can secure significant cytoprotection from NSAID damages through HSP27 accentuation.

METHODS

We evaluated protective actions of revaprazan against either in vivo animal model of indomethacin induced gastropathy or in vitro cell model focused on HSP27 expression and activation.

RESULTS

Indomethacin induced significant cytotoxicities accompanied with phosphorylated HSP27 and attenuated levels of HSP27 in the in vitro cell experiment and revaprazan administration protected stomach from indomethacin-induced gastric damages in accordance with HSP27 dephosphorylation in the in vivo animal experiment. HSP27 siRNA abolished these cytoprotective privileges of revaprazan. Indomethacin, 40 mg/kg, po, administration provoked significant levels of gastric damages accompanied with decrement in HSP27, while rats administrated with revaprazan prior to indomethacin imposed the accentuation of HSP27, of which levels were significantly correlated with the prevention of the indomethacin-induced gastric damages.

CONCLUSION

HSP27 phosphorylation with resultant decrease in HSP27 level was one of the mechanisms of indomethacin-induced cytotoxicity, of which post-translational modifications were prevented with revaprazan administration in the presence of indomethacin. Therefore, acid pump antagonist could be a choice for the prevention of NSAID-induced gastropathy backed up with distinctive cytoprotective action beyond acid suppressor.

Reinvestigation of the effect of carbenoxolone on the induction of heat shock proteins

Carbenoxolone (CBX) is a semisynthetic derivative of the licorice root substance glycyrrhizinic acid and has been previously reported to induce only heat shock protein 70 [Hsp70, HSPA1A (the systematic name of heat shock protein is given in the parenthesis after each HSP, according to the recent nomenclature guidelines, Kampinga et al., Cell Stress Chaperones, 14:105-111, 2008) but not other heat shock proteins (HSPs) (Nagayama et al., Life Sci. 69:2867-2873, 2001). In this study, we reinvestigated the effect of CBX on the induction of HSPs in HeLa and human neuroblastoma (A-172) cells. CBX clearly induced not only Hsp70 but also Hsp90 (HSPC1), Hsp40 (DNAJB1), and Hsp27 (HSPB1) at concentrations of 10 to 800 microM for 16 h incubation. At higher concentrations (more than 400 microM), however, CBX appeared to be toxic. Treatment of cells with CBX resulted in enhanced phosphorylation and acquisition of DNA-binding ability of heat shock transcription factor 1 (HSF1). Furthermore, characteristic HSF1 granules were formed in the nucleus, suggesting that the induction of HSPs by CBX is mediated by the activation of HSF1. Furthermore, thermotolerance was induced by CBX treatment, as determined by clonogenic survival. Although the precise target of CBX is not known at present, these results indicate that CBX is one of the molecular chaperone inducers and suggest that some pharmacological activities of CBX might be ascribable in part to its molecular chaperone-inducing property.

Protective effects of DIDS against ethanol-induced gastric mucosal injury in rats

The compound 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) is an efficient anion exchanger inhibitor that can block the activities of anion exchanger 2 (AE2), which plays an indispensable role in gastric acid secretion. DIDS also has potent anti-oxidative and antiapoptosis activities. This study aimed to investigate the effect of DIDS on ethanol-induced mucosal damage in rats and to evaluate the underlying mechanisms that mediate the action of the compound. The rats received 1 ml of absolute ethanol or saline orally. DIDS [50 mg/kg intravenous (i.v.)] was given 5 min before ethanol administration. Gastric lesions were evaluated macroscopically, microscopically, and electron microscopically at 60 min after ethanol challenge. Gastric myeloperoxidase (MPO) activity, malonyldialdehyde (MDA) level, prostaglandin E2 (PGE2) synthesis, and cyclooxygenase-2 (COX-2) expression were assessed. For the evaluation of the effect of DIDS on gastric acid secretion, histamine-stimulatory gastric acid secretion was examined with or without pretreatment of DIDS (50 mg/kg; i.v.). Ethanol-induced gastric lesions were characterized by increasing gastric MDA level, MPO activity, and COX-2 expression, and decreasing PGE2 synthesis. It was found that DIDS significantly reduced the extent of gastric mucosal damage and reversed tissue MDA level and MPO activity. DIDS further enhanced the expression of COX-2 and reversed the decrease of PGE2. Our results suggested that DIDS is beneficial in rat model of gastric injury through mechanisms that involve inhibiting inflammatory cell infiltration and lipid peroxidation and up-regulating the COX-2/PGE2 pathway.

Target molecules of molecular chaperone (HSP70 family) in injured gastric mucosa in vivo

AIMS

Several recent studies, including ours, have indicated the importance of heat shock proteins (HSPs) in cytoprotection against cytotoxic agents and environmental stresses mediated by the chaperone function of HSPs (molecular chaperones). However, the target molecule that is recognized by HSPs in damaged cells currently remains unknown. As HSPs rapidly recognize and bind to degenerated protein in cells, target molecules of HSPs might be key molecules for the initiation and pathogenesis of cellular damage. In the present study, gastric mucosal proteins that specifically bind to the HSP70 family (HSC70) were analyzed using HSC70-affinity chromatography.

MAIN METHODS

The gastric mucosa was removed from Sprague-Dawley rats after exposure to water immersion-stress for 0, 1, 3 or 5 h. Soluble fractions of each gastric mucosa were applied to the HSC70-affinity column separately. After washing off non-specific binding proteins, specific binding proteins were eluted by ATP-containing buffer. Binding proteins were analyzed by SDS-polyacrylamide gel electrophoresis. In addition, the amino acid sequence of purified proteins was also analyzed.

KEY FINDINGS

Specific HSC70-binding proteins with a molecular weight of 200-kDa and 45-kDa were eluted from an affinity column when gastric mucosal homogenate of 1-h stress exposure was applied. The amino acid sequencing showed that these binding proteins were cytoskeletal myosin (heavy chain) and actin, respectively.

SIGNIFICANCE

During the pathogenesis of stress-induced gastric mucosal damage, structurally degenerated cytoskeletal myosin (heavy chain) and actin may be key or initiation molecules which structural changes were firstly recognized by molecular chaperone.

Reduction of ethanol-induced injury in portal hypertensive gastric mucosa of rats by induction of heat shock protein 72 by geranylgeranylacetone

Portal hypertensive (PHT) gastropathy has an increased susceptibility to damage due to noxious factors. Heat shock protein (HSP) 72 has a protective effect against gastric mucosal injury and geranylgeranylacetone (GGA) is an inducer of HSP 72. However, it remains unclear how HSP 72 influences the PHT gastric mucosa. The aim of the present study was to investigate HSP 72 induction by GGA and the protective effect to gastric mucosa in PHT rats. PHT rats were produced by staged portal vein occlusion, and GGA 200 mg/kg was orally administered. Expression of HSP 72 protein in the gastric mucosa was evaluated by enzyme-linked immunosorbent assay, and gastric mucosal damage against 70% ethanol (10 mL/kg) following GGA or vehicle treatment was also estimated. Expression of mucosal HSP 72 after vehicle administration was significantly higher in the PHT rats compared with the sham-operated rats. After GGA treatment, portal pressure did not change but HSP 72 was significantly increased in the gastric mucosa of both groups. Ethanol-induced gastric mucosal damage was significantly decreased due to GGA treatment in the PHT rats, but not in the sham-operated rats. These findings suggest that HSP 72 expression is enhanced in PHT gastric mucosa and plays an important role in gastric mucosal protection. The induction of HSP 72 by GGA may therefore effectively prevent mucosal injury in the PHT stomach.

Association of high expression in rat gastric mucosal heat shock protein 70 induced by moxibustion pretreatment with protection against stress injury

AIM: To study the effect of moxibustion on Zusanli or Liangmeng point on gastric mucosa injury in stress-induced ulcer rats and its correlation with the expression of heat shock protein 70 (HSP70).

METHODS: Sixty healthy SD rats (30 males, 30 females) were divided into control group, injury model group, Zushanli point group, Liangmeng point group. Stress gastric ulcer model was induced by binding cold stress method. Gastric mucosa ulcer injury (UI) index was calculated by Guth method. Gastric mucosa blood flow (GMBF) was recorded with a biological signal analyzer. Protein content and gene expression in gastric mucosal HSP70 were detected by immunohistochemistry (IHC) and reverse transcription polymerase chain reaction (RT-PCR). Thiobarbital method was used to determine malondialdehyde (MDA) content. Gastric mucosal endothelin (ET) and prostaglandin E₂ (PGE₂) were analyzed by radioimmunoassay.

RESULTS: High gastric mucosal UI index, high HSP70 expression, low GMBF and PGF₂, elevated MDA and ET were observed in gastric mucosa of rats subjected to cold stress. Moxibustion on Zusanli or Liangmeng point decreased rat gastric mucosal UI index, MDA and ET. Conversely, the expression of HSP70, GMBF, and PGE₂ was elevated in gastric mucosa after pretreatment with moxibustion on Zusanli or Liangmeng point. The observed parameters were significantly different between Zusanli and Liangmeng points.

CONCLUSION: Pretreatment with moxibustion on Zusanli or Liangmeng point protects gastric mucosa against stress injury. This protection is associated with the higher expression of HSP70 mRNA and protein, leading to release of PGE₂ and inhibition of MDA and ET, impairment of gastric mucosal index.

Protective effect of a novel rice extract against ethanol-induced gastric mucosal injury in rat

The aim of this study was to investigate the protective action of rice extract on ethanol-induced mucosal damage in vivo and wound healing of epithelial cells in vitro. Also, the effect of rice extract on gastric mucosal prostaglandin E(2) level, HSP72 expression, gastric acid secretion, and contribution of vanilloid receptor-mediated action was studied. In addition, using cultured gastric mucosal cells (RGM-1), the effect of rice extract on cytoprotection and wound healing of epithelial cells was evaluated. Rice extract significantly reduced gastric mucosal damage produced by ethanol in vivo, and heat treatment (80 degrees C, 3 min) of this agent did not alter its protective effect. Rice extract also protected RGM-1 from ethanol-induced damage in a dose-dependent manner. Rice extract accelerated wound healing of gastric epithelial cells. Our results demonstrate that rice extract could be an alternative ulcer treatment that provides cytoprotection and enhancement of wound healing not dependent on acid secretion, prostaglandin E(2) level, HSP72 expression, or vanilloid receptors.

Zinc l-carnosine protects colonic mucosal injury through induction of heat shock protein 72 and suppression of NF-κB activation

In this study, we investigated the effects of zinc L-carnosine, an anti-ulcer drug, on acetic acid-induced colonic mucosal injury and the correlation of these effects with expression of 72-kDa heat shock proteins (HSP72) and nuclear factor kappa B (NF-kappaB) activation in rat colonic mucosa in vivo. After intrarectal administration of zinc L-carnosine, the rats received intrarectal infusion of 5% acetic acid (1 ml). The colonic mucosal damage was evaluated by macroscopic assessments 24 h after the intrarectal infusion of acetic acid. Expression of HSP72 in rat colonic mucosa was evaluated by Western blot analysis before and after zinc L-carnosine administration. NF-kappaB activation was evaluated by electrophoretic mobility shift assays (EMSA). Zinc L-carnosine inhibited visible damage in rat colonic mucosa by acetic acid. Expression of HSP72 was significantly increased at 6 h after zinc L-carnosine administration. Furthermore, NF-kappaB activation in colonic mucosa was suppressed 6 h after zinc L-carnosine treatment. These results suggested that zinc L-carnosine protects the colonic mucosa against acetic acid by induction of HSP72 and suppression of NF-kappaB activation and zinc L-carnosine may be a novel therapeutic agent for the therapy of inflammatory bowel disease.

Zinc L-carnosine protects against mucosal injury in portal hypertensive gastropathy through induction of heat shock protein 72

BACKGROUND AND AIMS

Increased susceptibility to gastric mucosal injury is observed in portal hypertensive gastropathy (PHG). In this study, the effects of zinc L-carnosine, an anti-ulcer drug, were evaluated on expression of heat shock protein (hsp) 72 and cytoprotection in gastric mucosa in a rat model of PHG.

METHODS

Portal hypertensive gastropathy with liver cirrhosis was induced by bile duct ligation for 4 weeks in male Sprague-Dawley rats. Expression of gastric mucosal hsp72 was evaluated by Western blotting at 6 h after intragastric administration of L-carnosine, zinc sulfate, or zinc L-carnosine. Blood was also collected for determination of serum zinc level. Mucosal protective abilities against hydrochloric acid (HCl) (0.6N) followed by pretreatment with L-carnosine, zinc sulfate or zinc L-carnosine were also studied.

RESULTS

L-carnosine, zinc sulfate, and zinc L-carnosine induced hsp72 in gastric mucosa of rats with bile duct ligation. Zinc sulfate and zinc L-carnosine suppressed HCl-induced mucosal injury. However, L-carnosine could not suppress HCl-induced mucosal injury. Serum zinc levels were significantly elevated after zinc L-carnosine administration. Furthermore, pretreatment with zinc L-carnosine (30-300 mg/kg) increased the expression of hsp72 in gastric mucosa and prevented HCl-induced mucosal injury in rats with bile duct ligation in a dose-dependent manner.

CONCLUSIONS

Zinc derivatives, especially zinc L-carnosine, protected portal hypertensive gastric mucosa with increased hsp72 expression in cirrhotic rats. It is postulated that zinc L-carnosine may be beneficial to the mucosal protection in PHG as a 'chaperone inducer'.

Expression of HSP72 in the gastric mucosa is regulated by gastric acid in rats-correlation of HSP72 expression with mucosal protection

BACKGROUND AND AIM

The real mechanism of adaptive cytoprotection in the gastric mucosa is not well established. In the present study, we investigated the effect of acid suppressing agents on a 72-kDa heat shock protein (HSP72) expression, which is known as endogenous cytoprotective factor, in the gastric mucosa. Also, the association of gastric mucosal protective function against HCl-challenge was compared between HSP72-induced and -reduced group.

MATERIALS AND METHODS

Expression of HSP72 was measured by Western blotting in the gastric mucosa before and after administration of famotidine or omeprazole. The gastric mucosal protective function against 0.6 N HCl was compared between control group and HSP72-reduced group. Also, the effect of increased expression of gastric HSP72 by additional administration of zinc sulfate or zinc L-carnosine, which is known as HSP72-inducer, on mucosal protective function was studied.

RESULTS

HSP72 expression in the gastric mucosa was reduced by acid suppressing agents. The lowest expression level of HSP72 was observed 12 h (famotidine, H2-receptor antagonist) or 48 h (omeprazole, proton pump inhibitor) after administration. The gastric mucosal protective ability against 0.6 N HCl was also reduced when HSP72 expression was decreased by famotidine or omeprazole. This phenomenon was reversed by HSP72 induction by additional administration of zinc derivatives.

CONCLUSION

Our results might indicate that the expression of HSP72 in the gastric mucosa is physiologically regulated by gastric acid, and that HSP72 induction could be important in view of mucosal protection especially when HSP72 expression is reduced by administration of acid suppressing agents such as proton pump inhibitor or H2 receptor antagonist.

Role of heat shock proteins (molecular chaperones) in intestinal mucosal protection

Most studies into the pathogenesis of inflammatory bowel diseases (IBD) have primarily focused on the cytotoxic agents and processes involved in producing mucosal injury, including the immune system. However, less consideration has been given to the inherent mechanisms of cytoprotection and cellular repair in the intestinal mucosa. This review will focus on intestinal mucosal protection against cytotoxic agents and cellular stress mainly from the viewpoint of expression and function of heat shock proteins, in their role of "molecular chaperones," as internal cytoprotectants. Elucidation of such stress-responses in the intestinal mucosa may provide a better understanding of the mechanisms of cytoprotection and cellular repair, and present new strategies for IBD therapy.

Is Mongolian gerbil really adequate host animal for study of Helicobacter pylori infection-induced gastritis and cancer?

BACKGROUND

Many researches have been published to understand the pathogenesis and mechanism of Helicobacter pylori (Hp)-associated diseases, including gastritis followed by gastric cancer, using Mongolian gerbil (MG) model because Hp could be hardly inoculated in other animal species. The aim of this study was to evaluate the induction ability of heat shock protein (HSP70) and protective ability in the gastric mucosa of MG comparing with those of Sprague-Dawley (SD) rats, since HSP70 is a key molecule known to be involved in important biological activities such as apoptosis, carcinogenesis, and cytoprotection from cytotoxic damage.

MATERIALS AND METHODS

Basal expression level and induction ability of gastric mucosal HSP70 were evaluated by immunoblotting and densitometric analysis in MG and SD rats before and after HSP-induction by zinc l-carnosine, gastric HSP70 inducer, administration. Mucosal protective ability against water-immersion stress-induced mucosal lesion was also compared.

RESULTS

Basal expression level of HSP70 was not significantly different between MG and SD rats. However, HSP70-induction by zinc derivatives was not observed in MG. Mucosal lesion induced by water-immersion stress was significantly severe in MG compared with SD rats.

CONCLUSIONS

MG might be special (not ordinary) animal, in which HSP70-induction was absent and has extremely poor mucosal protective ability in view of HSP-dependent cytoprotection in the gastric mucosa. Our results may suggest that MG is not an adequate animal to evaluate the effect of Hp-infection-associated gastric inflammation followed by development of gastric cancer.

Over-expression of 70-kDa heat shock protein confers protection against monochloramine-induced gastric mucosal cell injury

The major heat shock protein, HSP70, is known to be involved in cytoprotection against environmental stresses mediated by their function as a "molecular chaperone". Monochloramine (NH(2)Cl) is a potent cytotoxic oxidant generated by neutrophil-derived hypochlorous acid and Helicobacter pylori urease-induced ammonia. In this study, to evaluate the cytoprotective effect of HSP70 against NH(2)Cl-induced gastric mucosal cell injury, rat gastric mucosal cells (RGM-1) were stably transfected with pBK-CMV containing the human HSP70 gene (7018-RGM-1) or pBK-CMV alone (pBK-CMV-12) as control cells. These cells were treated with various concentrations of NH(2)Cl. Cell Viability was determined by MTT assay and the direct plasma membrane damage was analyzed by lactate dehydrogenase (LDH) release assay. Apoptosis was determined by DNA fragmentation analysis. NH(2)Cl caused injury to pBK-CMV-12 cells in a concentration-dependent manner. NH(2)Cl-induced gastric cell injury was significantly diminished in HSP70 over-expressing cell line (7018-RGM-1) both necrosis and apoptosis compared to the control cell line (pBK-CMV-12) transfected with CMV vector alone. These result suggest that overexpression of HSP70 plays an important role in protecting gastric cells against NH(2)Cl-induced injury.

Luminal bacterial flora determines physiological expression of intestinal epithelial cytoprotective heat shock proteins 25 and 72

Heat shock proteins (HSP) 25 and 72 are expressed normally by surface colonocytes but not by small intestinal enterocytes. We hypothesized that luminal commensal microflora maintain the observed colonocyte HSP expression. The ability of the small intestine to respond to bacteria and their products and modulate HSPs has not been determined. The effects of luminal bacterial flora in surgically created midjejunal self-filling (SFL) vs. self-emptying (SEL) small-bowel blind loops on epithelial HSP expression were studied. HSP25 and HSP72 expression were assessed by immunoblot and immunohistochemistry. SFL were chronically colonized, whereas SEL contained levels of bacteria normal for the proximal small intestine. SFL creation significantly increased HSP25 and HSP72 expression relative to corresponding sections from SEL. Metronidazole treatment, which primarily affects anaerobic bacteria as well as a diet lacking fermentable fiber, significantly decreased SFL HSP expression. Small bowel incubation with butyrate ex vivo induced a sustained and significant upregulation of HSP25 and altered HSP72 expression, confirming the role of short-chain fatty acids. To determine whether HSPs induction altered responses to an injury, effects of the oxidant, monochloramine, on epithelial resistance and short-circuit current (I(sc)) responses to carbachol and glucose were compared. Increased SFL HSP expression was associated with protection against oxidant-induced decreases in transmural resistance and I(sc) responses to glucose, but not secretory responses to carbachol. In conclusion, luminal microflora and their metabolic byproducts direct expression of HSPs in gut epithelial cells, an effect that contributes to preservation of epithelial cell viability under conditions of stress.

Over-expression of inducible heat shock protein 70 in the gastric mucosa of partially sleep-deprived rats

BACKGROUND

Previous findings have demonstrated increased expression of inducible heat shock protein 70 (iHSP70) in the gastric mucosa of rats exposed to partial sleep deprived (PSD). The purpose of this study was to investigate the functional role of iHSP70 and its relationship with acid secretion in the stomachs of PSD animals.

METHODS

A slowly rotating drum was used to induce PSD in male Sprague-Dawley rats with or without omeprazole treatment. Gastric mucosal samples were harvested for iHSP70 mRNA and protein analysis with RT-PCR and Western blotting, respectively. Enzyme immunoassay was used to determine plasma gastrin level and gastric acidity was measured by titration. The modulating effect of PSD on 0.6 M hydrochloric acid (HCl)-induced gastric damage was also evaluated.

RESULTS

PSD increased plasma gastrin, gastric acidity and expression of iHSP70, while significantly reducing HCl-induced gastric damage. Omeprazole administration decreased gastric acidity and reversed iHSP70 over-expression in PSD rats.

CONCLUSIONS

PSD increases gastric acidity which enhances expression of mucosal iHSP70. Over-expression of iHSP70 may be a protective homeostatic response of the stomach to stress induced by PSD and acid secretion.

Physiopathologie des lésions gastro-duodénales induites par les anti-inflammatoires non stéroïdiens

The pathogenesis of the gastroduodenal lesions induced by non-steroidal anti-inflammatory drugs and aspirin is primarily caused by a reduction in mucosal blood flow, which is the consequence of inhibition of cyclooxygenase-producing vasodilator prostaglandins. The subsequent phase is adherence of leukocytes to the endothelium, which may depend on cyclooxygenase-2. Endothelial lesions accentuate the fall of mucosal blood flow and promote the inflammatory process in the gastric mucosa. The inflammatory process is amplified by expression of TNFalpha in polymorphonuclears induced by non-steroidal anti-inflammatory drugs. A few days after starting treatment, epithelial proliferation and increased mucosal blood flow, partly dependent on cyclooxygenase-2 and nitric oxide expression, compensates for the damaging process. Selective inhibitors of inducible cyclooxygenase-2 have reduced gastrointestinal toxicity, which could partially be explained by the protection effect of cyclooxygenase-2 on the gastrointestinal mucosa during inflammation or epithelial repair. Selective inhibitors may worsen inflammatory bowel disease. Non-steroidal inflammatory drugs and aspirin, but perhaps not selective inhibitors, increase the mucosal lesions associated with Helicobacter pylori-induced gastritis. Co-administration of selective inhibitors and aspirin leads to gastrointestinal toxicity equivalent to that of non-specific anti-inflammatory drugs.

Role and regulation of intestinal epithelial heat shock proteins in health and disease

Mucosal injury and inflammation are cardinal manifestations of inflammatory bowel diseases (IBD), arising when the effects of cytotoxic factors and conditions overwhelm the cell's capacity for defense (i.e. cytoprotection) or repair. To date, most research in this area has focused primarily on agents and processes involved in producing tissue injury, with less consideration given to inherent mechanisms of cytoprotection and cellular repair. Therapeutic approaches to IBD reflect this bias, being largely directed towards down-regulating the inflammatory process by inhibiting the production of immune and inflammatory mediators. This review will focus on the cell's inherent ability to defend itself against cellular stress and injury through the production of evolutionarily conserved stress proteins called heat shock proteins (HSP). The physiological role of these proteins in maintaining intestinal epithelial cell structure and function will be reviewed, with emphasis on studies that examine the role of HSP in IBD. A clearer understanding of the innate cytoprotective mechanisms inherent in intestinal epithelial cells will foster the development of new insights into basic epithelial cell biology, which ultimately can be used to establish target-specific therapies directed at reducing or alleviating mucosal injury, thereby promoting tissue healing and repair.

Expression of glucose-regulation protein 94 in gastric mucosa infected with Helicobacter pylori

AIM

To study the expression of glucose regulation protein 94 in gastric mucosa infected with Helicobacter pylori.

METHODS

Semi-quantitative RT-PCR method was used to demonstrate mRNA expression of Grp94 in H.pylori (Hp) infected and non-infected gastric mucosa. Western blot was used to detect the expression level of Grp94 protein in the tissues.

RESULTS

Hp negative group had 28 cases, and the expression amount of Grp94 mRNA was 0.424±0.055. Hp infected group had 32 cases and the expression amount of Grp94 mRNA was 0.882±0.082. The expression amounts of Grp94 protein were 0.427±0.036, 0.671±0.072 respectively in Hp-negative and positive groups. The expression amounts of Grp94 mRNA and Grp94 protein in infected group showed a significant increase (P<0.01) respectively.

CONCLUSION

H.pylori infection may increase the expression of Grp94 at mRNA level in gastric mucosa. Meanwhile, it also increases synthesis of the protein.

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Enteric flora and lymphocyte-derived cytokines determine expression of heat shock proteins in mouse colonic epithelial cells

BACKGROUND & AIMS

Inducible heat shock proteins (hsps), particularly hsp25 and hsp72, are expressed by surface colonocytes and may have a role in protecting intestinal epithelial cells against injury. This study is aimed at determining if enteric bacteria and/or immune signals regulate their physiologic expression.

METHODS

Intestinal hsp25, hsp72, and constitutive hsc73 expression were studied in immunodeficient RAG-1(-/-) mice and in normal mice. Mucosal permeability was measured by mannitol flux and transepithelial resistance. Hsp expression in intestinal YAMC cells was assessed after incubation with recombinant cytokines, activated lamina propria lymphocytes (LPLs), or Bacteroides fragilis.

RESULTS

Chronic metronidazole treatment decreases colonic mucosal hsp25 and hsp72 expression, an effect associated with increased susceptibility of mucosal barrier function to C. difficile toxin A. Hsp expression also was increased in YAMC cells incubated with B. fragilis, an effect mediated by lipopolysaccharide and other bacteria-derived factors. Colonic hsp72, but not hsp25 or hsc73, expression is decreased in RAG-1(-/-) mice. Recombinant IL-2 and other cytokines enhance YAMC hsp25 and/or hsp72 expression. Activated LPLs induce YAMC hsp expression, an effect blocked by IL-2 neutralizing antibody.

CONCLUSIONS

Enteric flora and mucosal lymphocytes play a role in maintaining physiologic expression of colonocyte hsp25 and hsp72.

Effects of schisandrin B pretreatment on tumor necrosis factor-alpha induced apoptosis and Hsp70 expression in mouse liver

Tumor necrosis factor-alpha (TNFalpha) could cause apoptosis in hepatic tissue of D-galactosamine sensitized mice, as evidenced by the increase in the extent of DNA fragmentation. The hepatic apoptosis induced by TNFalpha was associated with hepatocellular damage as assessed by plasma alanine aminotransferase activity. Schisandrin B (Sch B) pretreatment at daily doses ranging from 0.5 to 2 mmol/kg for 3 days caused a dose-dependent protection against TNFalpha-induced apoptosis in mice. The hepatoprotection was accompanied by a parallel reduction in the extent of hepatocellular damage. The same Sch B pretreatment regimens increased hepatic Hsp70 level in a dose-dependent manner. The relevance of Sch B-induced increase in Hsp70 expression to the prevention of TNFalpha-triggered hepatic apoptosis remains to be elucidated.

Recent advances in gastrointestinal pathophysiology: role of heat shock proteins in mucosal defense and ulcer healing

The defense mechanism of the gastrointestinal mucosa against aggressive factors, such as hydrochloric acid, bile acid and non-steroidal anti-inflammatory drugs, mainly consists of functional, humoral and neuronal factors. Mucus-alkaline secretion, mucosal microcirculation, and motility act as functional factors, while prostaglandins and nitric oxide act as humoral factors, and capsaicin sensitive sensory neurons act as neuronal factors. All the above factors are known to contribute to mucosal protection. In recent years, heat shock proteins (HSPs), to include HSP70, have been implicated to be an additional factor utilized for the defense mechanisms of the gastrointestinal mucosa at the intracellular level. The expression of HSP70 and HSP47 markedly changes during the development and healing of chronic gastric ulcers in rats. It was revealed that HSC70 (a constitutive form of HSP70) is coprecipitated with cyclooxygenase-1 and the neuronal form of nitric oxide synthase after treatment with a mild irritant (20% ethanol). A positive relationship between enhanced interaction of HSC70 with either cyclooxygenase-1 or nitric oxide synthase and mucosal protection against a strong irritant (100% ethanol) was observed. It was concluded that HSPs might contribute to mucosal defense mechanisms and ulcer healing, most probably through protecting key enzymes related to cytoprotection.

Effect of xiaokuiling prescription on the expression of HSP72, HSP B in gastric mucosa of patients with Helicobacter pylori-associated duodenal ulcer

In order to investigate the mechanism of Xiaokuiling prescription (XKL) in the treatment of Helicobacter pylori (HP)-associated duodenal ulcer (DU) and the pathophysiologic role of heat shock proteins (HSPs) in the healing of ulcer, the expression of HSP72 and HSP B in gastric mucosa was detected by using SABC immunohistochemistry method and processed by micro-image analysis system. The method of Western blotting was used to measure the contents of HSP72 and HSP B in the tissue emulsion of gastric mucosa. The results were as follows: (1) HSP72 expression of the gastric mucosa in the treated group was obviously increased as compared with that in the control group (P < 0.05); (2) HSP B expression of the gastric mucosa in the treated group was significantly decreased as compared with that in the control group (P < 0.01). It was suggested that the increased expression of HSP72 and the elimination of HP might be related to the mechanism of action of XKL. HSPs might play an pathological and physiological role in the process of healing of gastric ulcer.

Gastroduodenal mucosal defense

The gastroduodenal mucosa is a model system of defense with several structural levels and biologic strategies that are closely interrelated with each other to cope with the harmful ingredients of ingested food and the potentially deleterious effects of gastric acid and pepsin. Experimental and clinical research carried out during the review period added to the understanding of each component of the multiple mechanisms of gastroduodenal mucosal protection. In the first place, mucosal integrity is defended by the mucus gel barrier, the epithelial cell barrier, and the immune barrier. The properties of these barriers are maintained by adequate regulation of mucus production, bicarbonate secretion, mucosal microcirculation, and motor activity. These regulatory systems are alarmed by nociceptive neurons and the mucosal immune system which includes chemokine-secreting epithelial cells. The ultimate defense system is rapid repair of the injured mucosa under the control of several growth factors. Progressing insight into the network of mucosal defense not only will improve existing therapies of inflammation and ulceration but also will provide new leads for the management of functional diseases in the gastroduodenal region.

Eicosanoids and the stomach

Eicosanoids are arachidonic acid derivatives that include prostaglandins, thromboxanes, and leukotrienes. During the last three decades, it has become evident that these bioactive lipids play a pivotal role in gastric physiology. The goal of the present review is to describe their involvement in the normal regulation of gastric secretion and gastric motility, as well as in gastric mucosal defense. Their role in gastric mucosal mitogenesis, apoptosis, inflammation, and immune modulatory responses is also discussed.