Dietary threonine prevented stress-related mucosal diseases in rats.

Stress-related mucosal disease (SRMD), or stress ulceration, is a group of conditions ranging from stress-related superficial gastric mucosal damage to deep gastric ulcers that are primarily correlated with mucosal ischemia, and pharmacologic interventions that optimize tissue perfusion or preserve defensive mucus aim to decrease the occurrence of conditions, such as gastric acidity, or enhance gastric defenses. However, the identification of multifactorial pathogenesis may be effective in preventing SMRD, and the use of stress prophylaxis is generally preferred. Since threonine is a component in the polymerization and synthesis of gastric mucin and possibly enhanced defense actions and lignin may provide structural support for defense and antioxidative function, we hypothesized that dietary intake of threonine and/or lignin can enhance defense against SRMD. The water immersion-restraint stress (WIRS) was used in rats and additional groups were pretreated with threonine alone or the combination of threonine and lignin. Based on gross and microscopic evaluations, threonine alone or the combination of threonine and lignin, a natural antioxidant, significantly reduced the development of SRMD (P < 0.05). According to molecular explorations, the levels of inflammatory mediators, such as interleukin (IL)-8, IL-6, IL-1ß, inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ), all of which are mediators that play a significant role in controlling WIRS, significantly decreased in the groups pretreated with either threonine alone or the combination of threonine and lignin (P < 0.01). WIRS significantly increased apoptosis in the stomach. However, the apoptotic index significantly decreased with threonine pretreatment. According to periodic acid Schiff staining results, the expression of gastric mucin was significantly preserved in groups pretreated with threonine but remarkedly decreased in the WIRS group. The gastric heme oxygenase-1 levels significantly increased in the group treated with threonine. In conclusion, the dietary intake of threonine or the combination of threonine and lignin is effective in preventing SRMD.

Oligonol prevented the relapse of dextran sulfate sodium-ulcerative colitis through enhancing NRF2-mediated antioxidative defense mechanism.

Repeated bouts of ulcerative colitis featured troublesome course of inflammatory bowel disease leading to fatal colitis-associated cancer, which is strongly associated with oxidative stress and sustained inflammation. Since oligonol, low molecular weighted polyphenol extracted from fruit lychee, showed antioxidative and anti-inflammatory actions, we hypothesized that oligonolcan prevent relapse of colitis. We compared oligonol with current gold standard therapeutics, sulfasalazine in preventive efficacy of relapse. First, dextran sulfate sodium (DSS)-induced colitis were made following pretreatment with oligonol, 10, 50, and 100 mg/kg for 7 days to measure therapeutic effect of oligonol and relapse model via repeated DSS administration was made following with either 50 mg/kg oligonol or 30 mg/kg sulfasalazine to explore relapse preventing action of oligonol in C57BL/6 mice. Detailed changes in colon were measured to explain molecular mechanisms. Pretreatment of 10, 50, 100 mg/kg oligonol (p.o.), significantly reduced DSS-induced colitis; total pathologic scores, colon length, and clinical symptom scores (P < 0.05). Oligonol pretreatment significantly decreased the levels of interleukin (IL)-1, IL-6, and tumor necrosis factor-α (TNF-α) as well as nuclear factor-κB (NF-κB), c-Fos, and c-Jun in affected colon tissues, but the expression of heme oxygenase-1 (HO-1) and NADH: quinone oxidoreductase-1(NQO-1) as well as total antioxidant concentration (P < 0.005) was significantly increased with oligonol. A relapse model established with repeated DSS administration led to high mortality. However, oligonol significantly ameliorated exacerbations of colitis, while sulfasalazine did not (P < 0.01). Significantly decreased expressions of cyclooxygenase-2 (COX-2), TNF-α, and macrophages inhibition were relapse preventing actions of oligonal, but significant action of oligonol relevant to relapse prevention was either significantly increased expressions of NQO-1 or significantly preserved mucin (P < 0.05). Concerted anti-inflammatory, antioxidative, and host defense enhancing actions of oligonol can be applied during maintenance therapy of IBD to prevent relapse of IBD.

Host nuclear factor erythroid 2-related factor-2 defense system determines the outcome of dextran sulfate sodium-induced colitis in mice.

Administration of dextran sulfate sodium (DSS) in drinking water led to significant bout of colitis simulating ulcerative colitis of human. However, colitis usually developed 5 - 7 days after DSS administration. Therefore, we hypothesized host defense system might protect colitis up to 5 days of DSS administration. 2.5% DSS-induced colitis were administered to C57BL/6 mice and sequential measurements of pathology, cyclooxygenase-2 (COX-2), nuclear factor-κB (NF-κB), heme oxygenase-1 (HO-1), NADPH quinone oxidoreductase-1 (NQO1), γ-glutamylcysteine synthetase (γ-GCS), nuclear factor erythroid 2-related factor-2 (Nrf2), and keap1 were done at 2, 6, 12, 24, 48, 96, 120, and 168 hour of DSS administration, respectively. DSS-induced colitis was repeated in either COX-2-/- or Nrf2-/- mice. On serial pathological analysis, significant colitis was noted after 120 h of DSS administration, during which both activations of COX-2/NF-κB and HO-1/Nrf2 were noted. Nrf2 activations after keap1 inactivation led to significant increases in HO-1 after 168 hours of DSS administration, when NF-κB nuclear translocation was noted. Significantly attenuated colitis was noted in DSS-challenged COX-2-/- mice, in which the levels of HO-1 were significantly decreased compared to DSS-challenged WT littermates (p < 0.01), while the levels of NQO1 were significantly increased. On DSS administration to Nrf2-/- mice, colitis was significantly aggravated (p < 0.01), in which the expressions of COX-2 as well as expressions of HO-1 and γ-GCS were significantly increased (p < 0.01). Reciprocal activations of inflammatory and antioxidative defense signaling after DSS administration might be prerequisite to make intestinal homeostasis and host defense Nrf2 system can determine colitis.

Role of proton pump inhibitors in preventing hypergastrinemia-associated carcinogenesis and in antagonizing the trophic effect of gastrin.

Gastrin is the main hormone stimulating gastric acid secretion, but it exerts proliferative and anti-apoptotic actions on various cancer cell types, in addition to its well-known trophic effect on enterochromaffin-like cells. As treatment with proton pump inhibitors (PPIs) increases the biosynthesis and secretion of gastrin, it has been postulated that treatment with PPIs could increase the risk of cancer, especially in Barrett's esophagus, gastric carcinoids, and colorectal cancer (CRC). Some tumors produce gastrin of their own, which can act in an autocrine manner to promote tumor growth. In addition, gastrin is known to foster the tumor microenvironment. However, in spite of these potentially increased cancer risks due to PPI-induced hypergastrinemia, prospective, large-scale cohort studies did not show an increase in CRC prevalence. The question as to why the long-term use of PPIs was not associated with an increased cancer risk of CRC might be answered by the fact that the PPIs antagonized the trophic effects of hypergastrinemia. Furthermore, the blockade of proton pumps or potassium channels in cancer cells could limit the abnormal glycolytic energy metabolism of cancer cells. Apart from their suppressive effect on gastric acids, PPIs exert an anti-tumor effect through the selective induction of apoptosis as well as an anti-inflammatory effect, and they protect cells from developing chemo- or radiotherapeutic resistance. Moreover, the anti-carcinogenic actions of PPIs were augmented with PPI-induced hypergastrinemia. Together with their potential targeted killing of cancer stem cells, these effects demonstrate their potential anti-cancer actions.

Gastrin promotes intestinal polyposis through cholecystokinin-B receptor-mediated proliferative signaling and fostering tumor microenvironment.

Increased serum gastrin concentrations in patients with colorectal cancer suggested the tumorigenic trophic effect of gastrin. Detailed and global molecular mechanisms explaining trophic effect of gastrin had not been revealed. In the current study, intestinal polyposis of APC(Min/⁺) mice was compared between phosphate buffered saline (PBS) injected and gastrin (10 µg/kg, thrice per week) injected group. Total number of intestinal polyposis was counted and immunohistochemical staining with F4/80 and CD3 was done. MTT assay, cell cycle analysis, and Western blot for cyclin D1, CDK4, and ß-catenin were performed in Raw 264.7 and HCT116 cells before and after gastrin administration. Experiments were repeated with YM022 or transfection with si-cholecystokinin-B receptor (CCK-B-R). Intraperitoneal gastrin significantly increased intestinal polyposis in APC(Min/⁺) mice (P<0.005), in which significant increases in macrophage were noted on F4/80 immunohistochemical staining (Plt;0.05) as well as Ki-67 staining (Plt;0.05) after gastrin. On comparative cytokine array, gastrin increased interleukin-1ß (IL-1ß), interleukin 3Rß (IL-3Rß), stromal cell-derived factor-1α (SDF-1α), thymus and activation-regulated chemokine (TARC), and thymus-derived chemotactic agent 3 (TCA-3) in macrophage cells, which was further confirmed with real time polymerase chain reaction (RT-PCR) analysis (P<0.05). In addition to increased inflammatory cytokines, gastrin increased macrophage proliferation accompanied with increased cyclin D1 and CDK4. Targeted for HCT116 cells, gastrin significantly increased proliferation as well as increases in synthetic phase of cell cycle. YM022 as gastrin antagonist significantly abolished the trophic actions of gastrin (P<0.05). HCT116 cells transfected with siCCK-B-R, gastrin did not increase either cell cycle or ß-catenin in spite of gastrin administration. Conclusively, gastrin promoted intestinal polyposis through either direct gastrin receptor-mediated proliferative signaling or fostering tumor microenvironment such as macrophage activation.

Nonsteroidal anti-inflammatory drugs (NSAID) sparing effects of glucosamine hydrochloride through N-glycosylation inhibition; strategy to rescue stomach from NSAID damage.

Gastrointestinal or cardiovascular complications limit nonsteroidal anti-inflammatory drugs (NSAID) prescription. Glucosamine hydrochloride (GS-HCl) alternatively chosen, but debates still exist in its clinical efficiency. COX-2 instability through inhibiting COX-2 N-glycosylation of GS-HCl raised the possibility of NSAID sparing effect. Study was done to determine whether combination treatment of glucosamine and NSAID contributes to gastric safety through NSAID sparing effect. IEC-6 cells were stimulated with TNF-α and compared the expressions of inflammatory mediators after indomethacin alone or combination of indomethacin and GS-HCl by Western blotting and RT-PCR. C57BL/6 mice injected with type II collagen to induce arthritis were treated with indomethacin alone or combination of reduced dose of indomethacin and GS-HCl after 3 weeks. TNF-α increased the expression of COX-2, iNOS and inflammatory cytokines, but GS-HCl significantly attenuated TNF-α-induced COX-2 expression. Decreased COX-2 after GS-HCl was caused by N-glycosylation inhibition as much as tunicamycin. Combination of reduced dose of indomethacin and GS-HCl significantly reduced the expressions of ICAM-1, VCAM-1, IL-8, IL-1ß, MMP-2, MMP-7, MMP-9, and MMP-11 mRNA as well as NF-κB activation better than high dose indomethacin alone. These NSAID sparing effect of GS-HCl was further proven in collagen-induced arthritis model. Combination of GS-HCl and 2.5 mg/kg indomethacin showed significant protection from gastric damages as well as efficacious anti-arthritic effect. Taken together, COX-2 N-glycosylation inhibition by GS-HCl led to indomethacin sparing effects, based on which combination of GS-HCl and reduced dose of NSAID can provide the strategy to secure stomach from NSAID-induced gastric damage as well as excellent anti-arthritic effects.

Role of heat shock proteins in gastric inflammation and ulcer healing.

With the discovery of gastric acid and pepsin in the stomach, the questions about "why does the stomach not digest itself?", "how does the stomach preserve its normal integrity under the continuous exposure to lytic materials that are secreted?", and "how does the stomach resist against overwhelming Helicobacter pylori (H. pylori) infection or persistent nonsteroidal anti-inflammatory drugs (NSAID) administration?" had been raised. The discovery of "gastric mucosal barrier" or "the presence of defense system" might be the answers to these questions. The first level of gastric mucosal barrier consists of the factors secreted into the lumen including bicarbonates, mucus, immunoglobulins, other antibacterial substances including lactoferrin, and surface active phospholipids. The second level of defense system is the gastric epithelia, which are remarkably resistant to acids or irritants and forms relatively tight barrier to passive diffusion. In addition, the epithelium is capable of undergoing extremely rapid repair and restitution if its continuity is disrupted. The third level of gastric mucosal barrier is the mucosal microcirculation in concert with sensory afferent nerves within the mucosa and submucosa. Back diffusion of acid or toxin into the mucosa results in neural system-mediated elevations of calcitonin gene related peptide, which contribute to enhancing mucosal blood flows that are very critical for limiting damage and facilitating repair. The fourth level of defense is the mucosal immune system, consisting of mast cells and macrophage, which orchestrate an appropriate inflammatory response to challenge. All the above factors are known to contribute to orchestrated artwork of "gastric mucosal protection". In recent years, heat shock proteins (HSPs) have been implicated to be an additional factor utilized for the gastric defense mechanisms at the intracellular level. Certain HSPs are expressed under non-stressful conditions and play an important role in the maintenance of normal cell integrity, but HSPs are generally considered to improve cellular recovery both by either refolding partially damaged functional proteins or increasing delivery of precursor proteins to important organelles such as mitochondria and endoplasmic reticulum, through which HSPs might complete efficient mucosal defense mechanisms and achieve ulcer healing, mostly probably protecting key enzymes related to cytoprotection. In this review, role of each heat shock protein, HSP90, HSP70, HSP27, in gastric inflammation and gastric ulcer healing will be described with general roles of HSPs.

Novel action of gastric proton pump inhibitor on suppression of Helicobacter pylori induced angiogenesis.

BACKGROUND: Although activation of mitogen activated protein kinases (MAPKs) by Helicobacter pylori infection is associated with induction of host angiogenesis, which may contribute to H pylori associated gastric carcinogenesis, the strategy for its prevention has not been identified. As we previously reported a strong inhibitory action of gastric proton pump inhibitors (PPIs) on MAPK extracellular signal regulated kinase (ERK)1/2 phosphorylation, we investigated whether PPIs could suppress the H pylori induced angiogenesis via inhibition of MAPK ERK1/2. METHODS: To address the relationship between H pylori infection and angiogenesis, comparative analysis of density of CD34(+) blood vessel was performed in tissues obtained from 20 H pylori positive gastritis and 18 H pylori negative gastritis patients. Expression of hypoxia inducible factor 1 (HIF-1alpha) and vascular endothelial growth factor (VEGF) was tested by reverse transcription-polymerase chain reaction and secretion of interleukin 8, and VEGF was measured by ELISA. To evaluate the direct effect of H pylori infection on the tubular formation of human umbilical vein endothelial cells (HUVEC), an in vitro angiogenesis assay was employed. Activation of MAPK and nuclear factor kappaB (NFkappaB) was detected by immunoblotting. RESULTS: H pylori positive gastritis patients showed a higher density of CD34(+) blood vessels (mean 40.9 (SEM 4.4)) than H pylori negative gastritis patients (7.2+/-0.8), which was well correlated with expression of HIF-1alpha. Conditioned media from H pylori infected gastric epithelial cells directly induced tubular formation of HUVEC and the increase of in vitro angiogenesis was suppressed by PPI treatment. Infection of H pylori significantly upregulated expression of HIF-1alpha and VEGF in gastric epithelial cells and expression of proangiogenic factors was mediated by MAPK activation and partially responsible for NFkappaB activation. PPIs effectively inhibited the phosphorylation of MAPK ERK1/2 that is a principal signal for H pylori induced angiogenesis. CONCLUSIONS: The fact that PPIs could downregulate H pylori induced angiogenesis indicates that antiangiogenic treatment using a PPI could be a promising protective therapeutic approach for H pylori associated carcinogenesis.

Decreased Helicobacter pylori associated gastric carcinogenesis in mice lacking inducible nitric oxide synthase.

BACKGROUND AND AIMS: Overproduction of nitric oxide via inducible nitric oxide synthase (iNOS) is suggested to be a significant pathogenic factor in Helicobacter pylori induced gastritis. The purpose of this study was to examine the role of iNOS in H pylori associated gastric carcinogenesis. METHODS: Two types of mice were used in this study: iNOS deficient mice (iNOS-/-) and wild-type littermates. Gastric cancer was generated in mice using a combination treatment comprising N-methyl-N-nitrosourea administration and H pylori infection. Fifty weeks after treatment, tumours in gastric tissues from both types of mice were examined using histopathology, immunohistochemistry, and immunoblotting for iNOS and 3-nitrotyrosine. RESULTS: The overall incidence of gastric cancer at week 50 was significantly lower in iNOS-/- compared with iNOS wild-type mice (p<0.05). When analysed according to tumour pathology, the incidence of gastric adenocarcinoma was significantly lower in iNOS-/- compared with iNOS wild-type mice (p<0.05). Immunostaining for iNOS was clearly observed in adenocarcinoma cells of iNOS wild-type mice, and was characterised by a strong cytoplasmic expression pattern. 3-Nitrotyrosine was expressed mostly in the area of the lamina propria of gastritis and adenoma lesions in iNOS wild-type mice. Immunoblotting analyses showed that iNOS and 3-nitrotyrosine were also expressed in both adenoma and adenocarcinoma tissues from iNOS wild-type mice. iNOS and 3-nitrotyrosine expression was greater in tumour tissues than in non-tumour tissues. CONCLUSIONS: These findings suggest that iNOS contributes to H pylori associated gastric carcinogenesis in mice.

Long-term evaluation of mice model infected with Helicobacter pylori: focus on gastric pathology including gastric cancer.

BACKGROUND: Long-term evaluation of gastric pathology after H. pylori infection is very important in order to reveal its clinical implications, since debate still exists on the gastric carcinogenesis provoked by H. pylori infection in animal models. AIM: Either to evaluate the long-term outcome of H. pylori infection or to determine how H. pylori could provoke gastric cancer in the mice model. METHODS: Four-week-old specific pathogen free C57BL/6 mice (n = 115) were infected with SS1, the mouse-adapted H. pylori strain. After 4, 8, 16, 24, 36, 50 and 80 weeks of bacterial infection, the H. pylori-infected mice were sacrificed. RESULTS: After 80 weeks of infection, almost all the H. pylori-infected mice developed hyperplastic gastritis, but did not show any evidence of gastric adenoma, dysplasia or carcinoma. PCNA positive cells were most abundant after 50 weeks and tended to decrease thereafter up to 80 weeks, whereas apoptosis began to be noted 8 weeks after H. pylori infection, showing 7-8 apoptotic cells/high power field, and tending to increase as time passed. Normally observed neutral mucin decreased during the experiment, showing the most marked decrease 50 weeks after H. pylori infection. In contrast, acidic mucin was noted from 50 weeks after infection. CONCLUSION: The SS1-infected mouse seems to be a suitable animal model for H. pylori-related research, and H. pylori itself does not induce gastric cancer in normal wild-type mouse model following long-term exposure, which could be explained by the balance that exists between cell proliferation and apoptosis.

Effect of long-term administration of rebamipide on Helicobacter pylori infection in mice.

BACKGROUND: It has been suggested that chronic, persistent, uncontrolled inflammations in the stomach could provide the basic step for the beginning of carcinogenesis. One of the potential clinical applications of rebamipide is the inhibition of the immunoinflammatory response in gastric mucosa imposed by Helicobacter pylori. AIM: To determine the implications of long-term rebamipide treatment in H. pylori infection, we studied the underlying moleculo-pathological changes in gastric lesions in mice infected with H. pylori (SS1 strain), following this treatment. METHODS: C57BL/6 mice were sacrificed 24 and 50 weeks after H. pylori infection, respectively. Colonization rates of H. pylori, degree of gastric inflammation and other pathological changes including atrophic gastritis and metaplasia, serum levels of IL-1beta, TNF-alpha, IFN-gamma and IL-10, mRNA transcripts of various mouse cytokines and chemokines, and NF-kappaB binding activities, and finally the presence of gastric adenocarcinoma were compared between an H. pylori infected group (HP), and an H. pylori infected group administered with long-term rebamipide-containing pellet diets (HPR). RESULTS: Serum levels of IL-1beta, IFN-gamma and TNF-alpha, the gastric mucosal expression of ICAM-1, HCAM and MMP, and transcriptional regulation of NF-kappaB-DNA binding were all significantly decreased in the HPR group compared with the HP group. An RNase protection assay showed, in the rebamipide administered group, significantly decreased mRNA levels of apoptosis-related genes such as caspase-8, FasL, Fas, TRAIL and various cytokines genes such as IFN-gamma, RANTES, TNF-alpha, TNFR p75, IL-1beta. In the experiment designed to provoke gastric cancer through MNU treatment with H. pylori infection, the incidence of gastric carcinoma was not different in either group. However, long-term administration of rebamipide showed the advantage of decreasing precancerous lesions like chronic atrophic gastritis and showed molecular evidence of attenuation of proliferation. CONCLUSION: The long-term administration of rebamipide should be considered in the treatment of H. pylori since it demonstrated molecular and biological advantages like a lessening of gastric inflammation and a possible chemopreventive effect.

Effect of virological response on post-treatment durability of lamivudine-induced HBeAg seroconversion.

Lamivudine-induced HBeAg seroconversion may not be durable in Korean patients with hepatitis B virus (HBV) infection. It is unknown whether virological response during lamivudine treatment affects the post-treatment outcome. We retrospectively analysed 124 consecutive HBeAg-positive chronic hepatitis B (CHB) patients treated with lamivudine. Lamivudine was given at a dose of 100 mg per day. HBV DNA levels in sera obtained before and during therapy were measured by the Digene Hybrid Capture II assay and Digene Ultrasensitive Hybrid Capture II assay, respectively. HBeAg seroconversion was achieved in 42 of the 124 patients (33.8%) treated with lamivudine. Mean duration of treatment in HBeAg seroconverters was 12.86 +/- 4.44 months. During the follow-up period, the cumulative relapse rates at 3 months and 6 months post-treatment in 42 patients with HBeAg seroconversion were 40.5% and 57.4%, respectively. Among 31 seroconverted patients whose sera were available at the second month of treatment, HBV DNA remained at > 4.7 x 103 genomes/mL in 15 patients and decreased to < 4.7 x 103 genomes/mL in the remaining 16 patients. HBV DNA levels at the second month of treatment was not related with relapse after discontinuation of treatment (66.7% vs. 43.8%, P= 0.2). At the time of HBeAg seroconversion, HBV DNA remained at > 4.7 x 103 genomes/mL in five patients and decreased to < 4.7 x 103 genomes/mL in the remaining 37 patients. Relapse rates were increased in patients who remained at > 4.7 x 103 genomes/mL compared with patients with HBV DNA levels < 4.7 x 103 genomes/mL (100% vs. 51.4%, P < 0.001). Thus, monitoring of serum HBV DNA at the time of HBeAg seroconversion may be helpful for predicting relapse in patients with lamivudine-induced HBeAg seroconversion.

Conditional loss of TGF-beta signalling leads to increased susceptibility to gastrointestinal carcinogenesis in mice.

BACKGROUND: Downregulation of TGF-beta receptors is implicated in colon cancer development. Inactivation of either of the two transmembrane serine/threonine kinases, TGF-beta1 types I/II receptors, is now implicated in carcinogenesis, especially gastrointestinal carcinogenesis. METHODS: We generated transgenic mice, called pS2-dnRII or ITF-dnRII, of which the dominant negative mutant of the TGF-beta type II receptor was expressed under the control of tissue-specific promoters, the pS2 promoter for stomach and ITF for intestine. They were either infected with H.pylori (ATCC 43504 strain, CagA+ and VacA+) or administered with azoxymethane to determine the significance of loss of TGF-beta signalling in gastrointestinal carcinogenesis. RESULTS: Gastric adenocarcinoma developed in pS2-dnRII mice, whereas only chronic active gastritis was noted in wild-type littermates after 36 weeks of H.pylori infection. Mice lacking in TGF-beta signalling specifically in the stomach showed a significantly higher proliferation cell nuclear antigen-labelling index when infected with H.pylori than wild-type littermates (P < 0.01). Development of colonic aberrant crypt foci was provoked in mice by intraperitoneal injections of azoxymethane, and ITF-dnRII mice showed significantly higher incidences of ACF and colon cancers than wild-type littermates. CONCLUSIONS: Maintaining normal TGF-beta signalling in the gastrointestinal tract seems to be important either for preventing abnormal mucosal proliferation, or for suppressing or retarding carcinogenesis.

Effect of rebamipide in treatment of Helicobacter pylori-associated duodenal ulcer: attenuation of chemokine expression and nitrosative damage.

Production of cytokines along with increased activity of nitric oxide synthase has been implicated as one of the contributing mechanisms of Helicobacter pylori-mediated gastroduodenal diseases. We aimed to evaluate the effect of rebamipide in treating Helicobacter pylori-associated duodenal ulcers in terms of cytokine production and nitrosative damage of the gastric mucosa. In patients with duodenal ulcers, rebamipide or placebo were given randomly after eradication. Mucosal cytokine production was measured by enzyme linked immunoassay, and nitrotyrosine immunoexpression was measured by immunohistochemistry. The inflammatory activity and degree of neutrophil infiltration were graded accordingly. The mucosal production of RANTES, interleukin-8, and TNF-alpha showed a significant decrease after eradication in patients with rebamipide after-treatment. The nitrotyrosine immunoreactivity of gastric epithelium was significantly decreased in the rebamipide group. Rebamipide treatment after eradication resulted in a significant reduction in chemokine production along with nitrotyrosine immunoexpression in Helicobacter pylori-associated duodenal ulcers.

Heterozygous mice for the transforming growth factor-beta type II receptor gene have increased susceptibility to hepatocellular carcinogenesis.

The transforming growth factor-beta (TGF-beta) receptor complex and its downstream signaling intermediates constitute a tumor suppressor pathway. In many cancers, expression of TGF-beta type II receptor (TbetaR-II) is markedly decreased. In the present study, we show that the hepatocytes isolated from 15-day-old, but not 9-month-old, mice heterozygous for the deletion of the TbetaR-II gene are slightly less sensitive to the growth-inhibitory effect of TGF-beta when compared with wild-type littermates of same age. In addition, the proliferation index of hepatocytes as indicated by bromodeoxyuridine incorporation is mildly increased in the heterozygous mice. These subtle changes in cellular phenotype did not result in either gross or microscopic abnormality of the liver. The treatment of these mice with the chemical carcinogen, diethylnitrosamine, results in a significantly enhanced tumorigenesis in the liver when compared with the wild-type littermates. Our results demonstrate the gene-dosage effect of TbetaR-II and indicate that the reduced expression of TbetaR-II in mice increases susceptibility to tumorigenesis in the liver.

Self-expanding coil stent with a long delivery system for palliation of unresectable malignant gastric outlet obstruction: a prospective study.

BACKGROUND AND STUDY AIMS: Peroral intubation of a self-expanding metal stent is usually difficult in patients with unresectable malignant gastric outlet obstruction, because the delivery systems currently available are not long enough and cannot easily pass the angulated gastroduodenal structure. We carried out a prospective study to assess the efficacy of a coil stent with a newly developed long delivery system, for palliation of unresectable malignant gastric outlet obstruction. PATIENTS AND METHODS: In 29 patients with unresectable malignant gastric outlet obstruction, caused by gastric cancer (26 patients), pancreatic head cancer (two patients), or duodenal cancer (one patient), peroral intubation of a self-expanding nickel-titanium coil stent was attempted, using a lengthened delivery system of 150 cm, under endoscopic and fluoroscopic guidance. RESULTS: Management was successful in 26 of 29 patients (89.7 %) without immediate major complications. In one patient in whom peroral intubation failed, percutaneous intubation of the coil stent via percutaneous endoscopic gastrostomy was done. After insertion of the coil stent, food ingestion with symptomatic improvement with regard to vomiting was achieved in 26 of 27 patients (96.3 %), including the patient with percutaneous stent insertion. During the follow-up period, dysphagia and Karnofsky scores improved significantly. Stent migration occurred in two patients, and tumor ingrowth in another two; re-intervention was done successfully performed in two instances. The mean survival time was 124 days (range 34 - 310 days) in the 22 patients who had no need for re-intervention during follow-up; among these was a patient who experienced stent occlusion by food material, which was easily corrected with endoscopic flushing. CONCLUSIONS: Peroral intubation of a self-expanding coil stent using a long delivery system is a safe and effective palliative technique for unresectable malignant gastric outlet obstruction, and significantly improves the quality of life of patients.

Oxidative stress is more important than acid in the pathogenesis of reflux oesophagitis in rats.

BACKGROUND: Although antisecretory medications such as histamine type II receptor antagonists or proton pump inhibitors have been used to treat reflux oesophagitis, a considerable number of patients do not achieve complete mucosal healing or suffer from either sustained symptoms or ensuing complications, suggesting other damaging factors or impaired mucosal resistance are also involved in the pathogenesis of reflux oesophagitis. AIMS: The present study was designed to evaluate oxidative stress as the major pathogenic factor of reflux oesophagitis and to determine the usefulness of antioxidants in the treatment of reflux oesophagitis. MATERIALS AND METHODS: Reflux oesophagitis was induced by insertion of a 3 mm calibre ring into the duodenum, 1 cm distal to the ligament of Treitz, in Sprague-Dawley rats. RESULTS: DA-9601, a novel antioxidant substance, significantly attenuated the gross and histopathological scores of reflux oesophagitis compared with those treated with ranitidine alone or reflux oesophagitis controls in a dose dependent manner. Only scattered erosions were observed in the antioxidant pretreated group but acid suppression by ranitidine was not effective in decreasing the severity of reflux oesophagitis. Significantly increased amounts of malondialdehyde (MDA), increased nuclear factor kappaB (NFkappaB) activation, and depletion of reduced glutathione (GSH) were observed in experimentally induced reflux oesophagitis. DA-9601 pretreatment attenuated the decrement in mucosal GSH levels and decreased MDA formation significantly. DA-9601 treatment caused significant reductions in activation of NFkappaB transcription factor, especially the p50 subunit, in accordance with the significantly higher levels of inhibitory protein of NFkappaB expression. CONCLUSION: Reflux oesophagitis caused considerable levels of oxidative stress in the oesophageal mucosa and antioxidant treatment should be considered as supplementary therapy in the prevention or treatment of reflux oesophagitis with acid suppression.

Involvement of oxidative stress in experimentally induced reflux esophagitis and Barrett's esophagus: clue for the chemoprevention of esophageal carcinoma by antioxidants.

Oxidative damage has long been related to mucosal damages of gastrointestinal tracts and their ensuing carcinogenesis. In spite of treatment with anti-secretory medications for reflux esophagitis, considerable portions of patient did not achieve the complete mucosal healings or suffered from sustaining symptoms or development of dread complication like Barrett's esophagus, suggesting other damaging factors or impaired mucosal resistance are also involved in their pathogenesis. The present study was designed either to evaluate the oxidative stress as the major pathogenic factor of reflux esophagitis or to find out the usefulness of antioxidant in the treatment of reflux esophagitis and the prevention of development of Barrett's esophagus. Acute or chronic reflux esophagitis was induced through either narrowing the third portion of duodenal lumen or performing myotomy of lower esophageal sphincter in rats, respectively. DA-9601, a new phytopharmaceutical possessing antioxidative properties, significantly attenuated the gross and histopathologic scores of acute reflux esophagitis in a dose-dependent manner compared to those treated with ranitidine alone. Only scattered erosions were observed in antioxidant pre-treated group, but acid suppression by ranitidine was not so effective in decreasing the severity of reflux esophagitis. Significantly increased amounts of malondialdehyde (MDA), increased NF-kappa B activations, and depletions of reduced glutathione (GSH) were observed in experimentally induced reflux esophagitis, but DA-9601 pre-treatment attenuated the decrement of mucosal GSH levels and decreased MDA formations significantly. DA-9601 treatment showed significant reductions in the activation of NF-kappa B transcription factor. DA-9601 significantly decreased the proliferating cell nuclear antigen-labeling index (PCNA-LI) of esophagus (P<0.05) in chronic reflux esophagitis model and prevented the development of Barrett's esophagus. In conclusion, reflux esophagitis provoked considerable levels of oxidative stress in the esophageal mucosa. Antioxidant treatment seems to be the first line therapeutics in the prevention or treatment of reflux esophagitis. Moreover, antioxidant possibly played the chemopreventive role through preventing the development of Barrett's esophagus.

Loss of transforming growth factor beta signalling in the intestine contributes to tissue injury in inflammatory bowel disease.

BACKGROUND: Inflammatory bowel disease (IBD) is a chronic inflammation of the gastrointestinal tract caused by an abnormal and uncontrolled immune response to one or more normally occurring gut constituents. AIM: Given the effects of transforming growth factor beta1 (TGF-beta1) on both the immune system and extracellular matrix, we postulated that alterations in TGF-beta signalling in intestinal epithelial cells may play an important role in the development of IBD. METHODS: TGF-beta signalling was inactivated in mouse intestine by expressing a dominant negative mutant form of the TGF-beta type II receptor under the control of the mouse intestinal trefoil peptide (ITF)/TFF3 promoter. Transgenic mice (ITF-dnRII) developed spontaneous colitis presenting with diarrhoea, haematochezia, and anal prolapse when not maintained under specific pathogen free (SPF) conditions. Under SPF conditions we induced colitis by mixing dextran sodium sulphate (DSS) in drinking water to examine the significance of loss of TGF-beta signalling in the pathogenesis of IBD. RESULTS: Transgenic mice showed increased susceptibility to DSS induced IBD, and elicited increased expression of major histocompatibility complex class II, generation of autoantibodies against intestinal goblet cells, and increased activity of matrix metalloproteinase in intestinal epithelial cells compared with wild-type littermates challenged with DSS. CONCLUSIONS: Deficiency of TGF-beta signalling specifically in the intestine contributes to the development of IBD. Maintenance of TGF-beta signalling may be important in regulating immune homeostasis in the intestine

Efficacy of use of colonoscopy in dextran sulfate sodium induced ulcerative colitis in rats: the evaluation of the effects of antioxidant by colonoscopy.

The goals in developing animal models of inflammatory bowel disease (IBD) are to determine the underlying mechanisms and the action of currently available drugs and to evaluate the value of new therapeutic approaches. Because of the difficulty in determining the severity of colitis in living animals, it has been necessary to kill the experimental animals at varying stages in the studies. If colonoscopic evaluation or endoscopic biopsy is feasible in these experimental animals, continuous observations could be possible, thus avoiding the need to kill them. The aims of the current study were to assess the efficacy of endoscopic examination as a monitoring tool for the severity of colitis in rats and to the efficacy of DA-9601, an extract from Artemisia asiatica which has both antioxidative and cytoprotective actions, on dextran sulfate sodium induced ulcerative colitis in rats endoscopically. Sprague-Dawley rats received 4% DSS in drinking water for 5 consecutive days. Either DA-9601 or sulfasalazine was administered twice a day for 8 days, starting 3 days before DSS administration. After the colonoscopic evaluations on days 2, 4, and 5 after DSS administration the rats were also killed for gross and histopathological evaluations. Simultaneous measurements of malondialdehyde (MDA) and myeloperoxidase (MPO) activities were performed. There was a statistically significant correlation between the scores evaluated by the gross examination and colonoscopic scores, between the colonoscopic scores and the levels of MDA or mucosal MPO activities, and between colonoscopic scores and histopathological activity index. DA-9601 showed excellent improvement in gross lesion scores, decreased MDA amounts and MPO activities compared to sulfasalazine. In conclusion, the introduction of appropriate colonoscopic examination in animal models of IBD could avoid the sacrifice of experimental animals for interim evaluation and provide the valuable information on the course and efficacy of treatment. The potential usefulness of antioxidants in treating IBD is very promising based on the colonoscopic intervention of IBD.