Yutaka Isozaki

Increased expression of microRNA in the inflamed colonic mucosa of patients with active ulcerative colitis

Background and Aims:  MicroRNA (miRNA) are endogenous, approximately 22‐nucleotide non‐coding RNA that suppress gene expression at post‐transcriptional levels by binding to the 3′‐untranslated region of specific mRNA targets through base‐pairing. It has been recently reported that miRNA have critical functions in key biological processes such as cell proliferation and cell death in various cancer cells. However, the relationship between intestinal inflammation and miRNA expression remains unclear. In the present study, we used microarray technology to identify miRNA induced in the colonic mucosa of patients with active ulcerative colitis (UC).

Anti-tryptase treatment using nafamostat mesilate has a therapeutic effect on experimental colitis

Objective. Mast cell tryptase has been proposed to be involved in the pathogenesis of human inflammatory bowel disease (IBD). Recently, it was reported that a low dose of nafamostat mesilate (NM), a serine protease inhibitor that is widely used to treat disseminated intravascular coagulation (DIC) and acute pancreatitis, can selectively inhibit human tryptase activity. The aim of this study was to investigate the anti-inflammatory effects of NM on experimental colitis in rats. Material andmethods. Colitis was induced in male Wistar rats using an enema of trinitrobenzene sulfonic acid (TNBS) dissolved in 50% ethanol. NM or 5-aminosalicylic acid (5-ASA), foundation therapy for mild-to-moderate IBD, was administered via the anus once a day on each of the 6 days after administration of TNBS. Colonic inflammation was assessed 1 week after TNBS administration. Results. Intracolonic administration of TNBS resulted in the infiltration of numerous tryptase-positive cells in the colonic mucosa. The colonic mucosal injury induced by TNBS was significantly decreased by treatment with NM or 5-ASA. The increases in thiobarbituric acid-reactive substances (TBA-RS), myeloperoxidase (MPO) activity, tumor necrosis factor (TNF)-α and cytokine-induced neutrophil chemoattractants-1 (CINC-1) in the colonic mucosa were inhibited in the NM group and the 5-ASA group, without significant differences between them. Conclusions. These results indicate that a low dose of NM can inhibit the colonic mucosal inflammation induced by TNBS in rats, which suggests that anti-tryptase therapy using low doses of NM has excellent potential to become a new therapeutic strategy for IBD.

Heme oxygenase-1 (Hsp32) is involved in the protection of small intestine by whole body mild hyperthermia from ischemia/reperfusion injury in rat.

Aim: The aim of the present study was to explore whether heme oxygenase-1 (HO-1) is involved in the hyperthermia-provided protection of the small intestine from ischemia/reperfusion injury in rats. Methods: Intestinal damage was induced in male Sprague-Dawley rats by clamping both the superior mesenteric artery and the celiac trunk for 30 min, followed by reperfusion. Whole-body hyperthermia was induced in anesthetized rats by placement in a temperature-controlled water bath. Whole-body hyperthermia to a core temperature of 42–43°C for 15 min was followed by passive cooling. We started the hyperthermic treatment 6 h before the vascular clamping. The severity of the mucosal injury was evaluated by several biochemical markers and histological findings. Hyperthermia-induced heat-shock proteins were detected by Western blotting. We also investigated the effect of zinc protoporphyrin IX (an HO-1 inhibitor) on the protective effect of hyperthermia. Results: The rats, which were killed after ischemia/reperfusion, had severe intestinal inflammation. Hyperthermia significantly induced the production of Hsp70 and HO-1 in intestinal mucosa and significantly reduced ischemia/reperfusion-induced mucosal injury. The combination of zinc protoporphyrin IX with hyperthermia extinguished the protective effects of hyperthermia on ischemia/reperfusion injury. Conclusion: Hyperthermia protects against ischemia/reperfusion injury in rat small intestine through the expression of heat-shock proteins, especially HO-1.

Synergistic effect of HLA class II loci and cytokine gene polymorphisms on the risk of gastric cancer in Japanese patients with Helicobacter pylori infection

It has been reported that polymorphisms of human leukocyte antigen (HLA) genes and several cytokine genes are associated with an increased risk of developing gastric cancer (GC). However, the results of studies from different geographic regions, ethnic groups and study groups are inconsistent. The aim of this study was to evaluate the influence of H. pylori infection and host genetic factors on GC susceptibility in Japanese patients with GC. We analyzed genotypes for HLA class I and II, tumor necrosis factor α, interleukin (IL)‐1β, IL‐1 receptor, IL‐4, IL‐4Rα and IL‐10 in 330 H. pylori‐infected noncardia patients with GC and 190 H. pylori‐infected nonulcer dyspeptic controls. Haplotype analyses indicated that the frequencies of the HLA DRB1*0405 and DQB1*0401 alleles were increased in the patients with intestinal‐type GC when compared with controls (both DRB1*0405 and DQB1*0401: p = 0.015, OR = 1.57, 95% CI = 1.09–2.26), but the changes were not statistically significant after correction for multiple comparisons. None of the cytokine gene polymorphisms were associated with GC susceptibility, whether patients with GC were analyzed as a group according to the histological subtype. Of interest was the comparison of controls and patients with intestinal‐type GC. The frequency of an IL‐10‐592AA homozygote showing concomitant carriage of the HLA DRB1*0405‐DQB1*0401 haplotype was significantly higher in patients with intestinal‐type GC (χ2 = 6.369, p = 0.0116, pc = 0.0464, OR = 2.43, 95% CI = 1.21–4.48). Our results suggest that the HLA class II and IL‐10‐592A/C polymorphisms synergistically affect the susceptibility to GC development of H. pylori‐infected individuals in the Japanese population.

Prevention by rebamipide of acute reflux esophagitis in rats.

Proinflammatory factors, including neutrophil-derived oxygen free radicals and inflammatory cytokines, have recently been implicated in the pathogenesis of reflux esophagitis. Rebamipide has been widely used as an anti-ulcer agent. The aim of the present study was to assess the protective effect of rebamipide against acute reflux esophagitis in rats. Esophagitis was induced in rats by ligation at the limiting ridge and the lower portion of the duodenum. Vehicle or rebamipide were given as a single dose intraduodenally. Lesion index (LI), thiobarbituric acid-reactive substances (TBA-RS), myeloperoxidase (MPO) activity, mRNA and protein of tumor necrosis factor (TNF)-α and cytokine-induced neutrophil chemoattractant (CINC)-1 in the esophageal mucosa were markedly increased; pretreatment with rebamipide, however, significantly reduced both macroscopic and microscopic injuries and increases in inflammatory mediators. The results of this study indicate that rebamipide protects against the occurrence of esophagitis and has highly promising potential as a new therapeutic agent for reflux esophagitis.

A Comparative Study on Endoscopic Ulcer Healing of Omeprazole Versus Rabeprazole with Respect to CYP2C19 Genotypic Differences

Omeprazole is mainly metabolized in the liver by CYP2C19, a genetically determined enzyme, while rabeprazole is mainly nonenzymatically degraded with a minor involvement by CYP2C19. We investigated the gastric ulcer healing effect of omeprazole versus rabeprazole evaluated endoscopically with reference to the different CYP2C19 genotypes. Eighty patients with active gastric ulcer were treated with a daily dose of 20 mg of omeprazole or 10 mg of rabeprazole. The endoscopic evaluation was performed at the baseline and 2- and 8-week posttreatment periods. The endoscopic improvement of gastric ulcer size and ulcer healing rates using a thin rubber disc with a diameter of 6 mm, were evaluated in relation to the CYP2C19 genotypic status. The mean 2-week posttreatment ulcer size value by rabeprazole did not significantly differ among the different CYP2C19 genotypes, whereas the mean value in the homozygous extensive metabolizer patients treated with omeprazole was significantly (P = 0.0057) greater than in those with rabeprazole. However, after the 8-week treatment, omeprazole and rabeprazole showed the similarly high healing rates of 87.8% (31/37) and 88.9% (32/36), respectively. Although both omeprazole and rabeprazole showed a high healing rate of gastric ulcer after the 8-week treatment period, the healing effect of rabeprazole appears to be relatively independent of the CYP2C19 status, resulting in an earlier repair of gastric mucosal damage evaluated endoscopically compared to that of omeprazole.

A PPAR-γ ligand, 15-deoxy-Δ12,14-prostaglandin J2, inhibited gastric mucosal injury induced by ischemia-reperfusion in rats

Abstract Introduction: Recent studies have demonstrated the anti-inflammatory action of 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), a derivative of the PGD2 metabolic pathway. Acute inflammation, including neutrophil activation, plays a critical role in the pathogenesis of ischemia–reperfusion (I/R). The aim of the present study was to determine the effect of 15d-PGJ2 on I/R-induced gastric mucosal injury in rats. Methods: Gastric mucosal damage was induced in male Wistar rats by clamping the celiac artery for 30 min followed by reperfusion. 15d-PGJ2 (0.01–1.0 mg/kg) was given to the rats intraperitoneally 1 h before the vascular clamping. The area of gastric mucosal erosions (erosion index) was measured. Thiobarbituric acid reactive substances (TBARS) and tissue-associated myeloperoxidase (MPO) activity were measured in the gastric mucosa as indices of lipid peroxidation and neutrophil infiltration. The expression of tumor necrosis factor-α (TNF-α) in gastric mucosa was measured by ELISA. In addition, to elucidate whether the protective effects of 15d-PGJ2 are related to the activation of the PPAR-γ receptor, we also investigated the effects of a PPAR-γ antagonist, GW9662. Results: After 60 min of reperfusion, the area of gastric erosion index had significantly increased from the mean basal levels. The increase in the erosion index was significantly inhibited by pretreatment with 15d-PGJ2 in a dose-dependent manner. On the other hand, GW9662 reversed the protective effect of 15d-PGJ2. The concentration of TBARS and MPO activity in the gastric mucosa were both significantly increased after I/R, and pretreatment with 15d-PGJ2 significantly reduced these increases. The TNF-α content was significantly higher in the I/R group than in the sham-operated group. However, the increase in TNF-α was significantly inhibited by pretreatment with 15d-PGJ2. Conclusions: 15d-PGJ2 significantly inhibited the severity of acute gastric mucosal injury induced by I/R in rats through PPAR-γ-dependent mechanisms. This effect may be due, in part, to a reduction in the infiltration of neutrophils into the gastric mucosa, possibly via the inhibition of inflammatory cytokine.

Multifaceted Assessment of Chronic Gastritis: A Study of Correlations between Serological, Endoscopic, and Histological Diagnostics

Aim. Chronic gastritis was assessed serologically, endoscopically and histologically to identify correlations between these methods. Methods. Subjects comprised 319 patients who had provided informed consent. Serological assessment of chronic gastritis was based on the pepsinogen test method. Endoscopic gastritis and histological gastritis were assessed and scored according to the Kimura-Takemoto classification system and the updated Sydney classification system respectively, and correlations between these three methods were studied. Results. Pepsinogen I/II ratio showed a significant correlation to the extent of mononuclear cell infiltration of the gastric corpus. When histological gastritis was divided, on the basis of the distribution of mononuclear cell infiltration, into gastritis limited to the antrum and corpus gastritis, these types were distinguished with high accuracy using a pepsinogen I/II ratio of 3 as the cutoff. A good correlation was also seen between pepsinogen I/II ratio and development of atrophy in endoscopic gastritis, where groups with and without advanced atrophy were also distinguished with high accuracy using a cutoff value of 3. Conclusion. Significant correlations exist between serum pepsinogen levels, endoscopic gastritis, and histological gastritis. Pepsinogen I/II ratio allows prediction of the existence of endoscopic gastritis and histological gastritis, or the extent of their development, with high accuracy.

Proinflammatory role of protease-activated receptor-2 in intestinal ischemia/reperfusion injury in rats

Protease-activated receptors (PARs) are widely recognized for their modulatory properties during inflammation. The aim of the present study was to examine the role of PAR-2 on ischemia/reperfusion-induced small intestinal injury in rats. Intestinal damage was induced in male Wistar rats by clamping both the superior mesenteric artery and the celiac trunk for 30 min, followed by reperfusion for 60 min. Expression of PAR-2 in the intestinal mucosa was estimated by Western blot analysis and real-time PCR. Anti-rat PAR-2 cleavage site (PCS) antibody was intraperitoneally administered to the rats 1 h before the vascular clamping. The intestinal mucosal injury and inflammation were evaluated by biochemical markers and histological findings. Thiobarbituric acid (TBA) reactive substances and tissue-associated myeloperoxidase (MPO) activity were measured in the intestinal mucosa as indices of lipid peroxidation and neutrophil infiltration, respectively. Expression of cytokine-induced neutrophil chemoattractant-1 (CINC-1) in intestinal mucosa was measured by enzyme-linked immunosorbent assay. Expression of PAR-2 mRNA and protein in the intestinal mucosa was increased after reperfusion following ischemia. Reperfusion after ischemia resulted in an increase in luminal protein concentrations, hemoglobin concentrations, TBA reactive substances, MPO activity and CINC-1 protein. Pre-treatment with anti-rat PCS antibody significantly inhibited the increases in these parameters. These results suggest that PAR-2 plays an important role in the pathogenesis of ischemia/reperfusion-induced intestinal injury.

Rotenone, a mitochondrial electron transport inhibitor, ameliorates ischemia-reperfusion-induced intestinal mucosal damage in rats.

Abstract In ischemia–reperfusion (I/R)-induced tissue injury, oxygen radicals can be generated by several mechanisms. One of the important sources of oxygen radicals is thought to be mitochondrial respiration. The aim of this study was to investigate the antioxidative defense effect of the mitochondrial electron transport inhibitor, rotenone using the I/R-induced rat intestinal mucosal injury model in vivo. Intestinal ischemia was induced for 30 min by applying a small clamp to the superior mesenteric artery in rats. Rotenone at a dose of 100 mg/kg was given to rats orally 2 h before the ischemia. Intraluminal hemoglobin and protein levels, the mucosal content of thiobarbituric acid-reactive substances (TBARS), the mucosal myeloperoxidase activity, and the content of inflammatory cytokines (CINC-1, TNF-α) were all significantly increased from mean basal levels after 60 min of reperfusion. These increases after I/R were inhibited by treatment with rotenone at a dose of 100 mg/kg. Co-administration with succinate (100 mg/kg), a substrate of the mitochondrial electron transport system, cancelled significant reduction of intraluminal hemoglobin and mucosal TBARS treated with rotenone alone. The results of the present study indicate that rotenone inhibited lipid peroxidation and reduced development of the intestinal mucosal inflammation induced by I/R in rats. This investigation suggests that rotenone has potential as a new therapeutic agent for reperfusion injury.