Tatsuhiko Hamamoto

Comparison of gastric emptying and plasma ghrelin levels in patients with functional dyspepsia and non-erosive reflux disease.

Background and Aims: The symptoms of postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS), the two subtypes of functional dyspepsia (FD) under the new Rome III classification, tend to overlap with those of non-erosive reflux disease (NERD). Plasma ghrelin levels have been associated with gastric motility; however, clinical studies have yet to examine this relationship among patients with PDS, EPS or NERD. Thus, this study aims to evaluate the correlation between gastric emptying and ghrelin levels as possible candidate factors for gastric motility in these diseases. Methods: One hundred and fifty-one patients presenting with typical symptoms of FD (EPS, n = 36; PDS, n = 76) or NERD (n = 39), and 20 healthy volunteers were enrolled. Gastric motility was evaluated with the Tmax value as a marker of gastric emptying using the 13C-acetate breath test. We used Rome III criteria to evaluate upper abdominal symptoms, and SRQ-D scores to determine depression status. We measured both acylated and des-acylated ghrelin levels by ELISA methods. Results: The Tmax value in PDS patients was significantly higher than in healthy volunteers. Acylated ghrelin levels were significantly lower in NERD and PDS patients than in healthy volunteers. Interestingly, there was significant correlation between the acylated ghrelin levels and Tmax value in PDS patients but not in EPS or NERD patients. Conclusion: Our results suggest that acylated ghrelin might play an important role in the pathophysiology of PDS patients through its effect on gastric emptying.

Monocyte chemoattractant protein 1 and CD40 ligation have a synergistic effect on vascular endothelial growth factor production through cyclooxygenase 2 upregulation in gastric cancer

BackgroundRecent studies have reported that expression of monocyte chemoattractant protein 1 (MCP-1) and its receptor (CCR2) and CD40 ligation on mesenchymal cells play important roles in tumor development. Cyclooxygenase 2 (COX-2) has also been shown to contribute to tumor angiogenesis. We examined the interaction between MCP-1 and CD40 ligation in mesenchymal cells in gastric cancer to determine the effect of these factors on vascular endothelial growth factor (VEGF) production via upregulation of COX-2 expression.MethodsCOX-2, prostaglandin E2 (PGE2), and VEGF production were evaluated in CD40 ligand (CD40L)-stimulated macrophages. CD40L and MCP-1 mRNA levels in gastric cancer tissues were evaluated by real-time polymerase chain reaction (PCR). Localizations of MCP-1, CD40L, CD34, CD40, and CCR2 in 34 gastric cancer tissue specimens were evaluated by single-or double-label immunohistochemistry.ResultsCOX-2 expression levels were significantly higher in CD40L-stimulated macrophages and correlated with increased PGE2 and VEGF production. Addition of MCP-1 to CD40L-stimulated macrophages had a synergistic effect on COX-2 expression and subsequent PGE2 and VEGF production. CD40L and MCP-1 mRNA levels were significantly higher in poorly differentiated gastric cancers than in H. pylori-infected gastritis patients. High microvessel density was significantly associated with MCP-1 and CCR2 scores and lymph node metastasis.ConclusionsMCP-1 and CD40L had a synergistic effect on COX-2 expression and subsequent VEGF production in gastric cancer.

Expression of apurinic/apyrimidinic endonuclease-1 (APE-1) in H. pylori-associated gastritis, gastric adenoma, and gastric cancer.

Background and Aim:  Apurinic/apyrimidinic endonuclease‐1 (APE‐1) is a key enzyme in DNA base excision repair (BER), linked to cancer chemosensitivity. However, little is known about the localization of APE‐1 in Helicobacter pylori‐infected gastric mucosa or its role in the development of gastric cancer. To investigate the role of APE‐1 in the development of gastric cancer, we examined APE‐1 expression and localization in cultured cells and gastric biopsies from patients with H. pylori‐infected gastritis or gastric adenoma, and from surgically resected gastric cancer.

Chemopreventive effect of celecoxib in gastric cancer.

Abstract.COX (cyclooxygenase) is one of the key enzymes involved in the synthesis of a variety of prostaglandins (PGs), some of which have been strongly linked to inflammation. One of its two well-known isoforms, COX-2, is an inducible enzyme whose induction and expression is dynamically regulated by growth factors, mitogens, and tumor promoters.Several animal and clinical studies have reported the chemopreventive effect of celecoxib, a selective COX-2 inhibitor; and in particular, a few studies have shown that celecoxib prevents the development of gastric cancer. Administration of celecoxib also showed increases in cardiovascular risk and disruption of renal physiology. Therefore, studies hoping to clarify how selective COX-2 inhibitors modulate gastric cancer must keep in mind that coxibs have also been linked to serious cardiovascular events and disruption of renal physiology.

Celecoxib Inhibits Cdx2 Expression and Prevents Gastric Cancer in Helicobacter pylori-Infected Mongolian Gerbils

Background/Aim: The aim of this study was to see whether administration of celecoxib, a selective COX-2 inhibitor, prior to the appearance of intestinal metaplasia could prevent the development of gastric cancer in Helicobacter pylori-infected Mongolian gerbils. Methods:Fifty-two Mongolian gerbilswere divided into 3 groups and given 5 biweekly doses of N-methyl-N-nitrosourea (MNU; 30 ppm). At week 12, group 2 (n = 20) and group 3 (n = 22) gerbils were then given an injection of H. pylori, while group 1 controls (n = 10) received Brucella broth alone. In addition, 7 weeks after H. pylori inoculation, at week 19, group 3 gerbils also received a 36-week administration course of celecoxib (1,500 ppm) in their diet. The incidence of gastric adenocarcinoma was determined at week 54 by histological analysis. COX-2 and Cdx2 protein expression and COX activity were evaluated for each group. The extent of intestinal metaplasia, Cdx2 and MUC2 expression, and the apoptotic index were evaluated semi-quantitatively by immunohistochemistry. Results: The incidence of gastric adenocarcinoma was: group 1, 0% (0/10); group 2, 65% (13/20), and group 3, 23% (5/22; p < 0.05). Continuous celecoxib administration significantly reduced COX activity and COX-2 protein expression, Cdx2 and MUC2 protein immunoreactivity, and the extent of Alcian blue periodic acid-Schiff-positive intestinal metaplasia in H. pylori-infected gerbils. Celecoxib also induced apoptosis in these gerbils. Significant inhibition of Cdx2 expression in group 3 gerbils was also shown by Western blot analysis. Conclusions: Prior to the first appearance of intestinal metaplasia, timely administration of celecoxib prevents gastric cancer occurrence by disrupting the progression of intestinal metaplasia into gastric carcinoma through its inhibition of Cdx2 expression in MNU-pretreated H. pylori-infected Mongolian gerbils.

Rebamipide reduces indomethacin-induced gastric injury in mice via down-regulation of ICAM-1 expression

Non-steroidal anti-inflammatory drugs (NSAIDs) induced gastric mucosal injury occurs through subsequent events following free radical production derived from activated neutrophils. In this study, we hypothesized that rebamipide, a novel anti-ulcer agent, exerts a protective effect on NSAID-induced gastric injury through its antioxidant properties. The protective effect of rebamipide in a mouse model of indomethacin-induced gastric injury and mechanisms for this effect were investigated. Pre-treatment with rebamipide significantly inhibited indomethacin-induced gastric mucosal injury in mice. Gastric thiobarbituric acid reactive substances (TBARS) levels and myeloperoxidase (MPO) activity substantially increased 3 hr after indomethacin administration. These increases were significantly inhibited by pre-treatment with rebamipide. Furthermore, rebamipide pre-treatment notably decreased intercellular adhesion molecule-1 (ICAM-1) expression that was up-regulated in gastric tissue treated with indomethacin. Therefore, rebamipide may reduce indomethacin-induced gastric mucosal injuries through its antioxidant effect, which inhibits the neutrophil activation step following up-regulation of ICAM-1 expression on endothelial cells.

Celecoxib Inhibits CD133-Positive Cell Migration via Reduction of CCR2 in Helicobacter pylori-Infected Mongolian Gerbils

Background/Aims: To see whether celecoxib prevents gastric cancer occurrence by disrupting the progression of chronic gastritis into gastric carcinoma through its inhibition of the migration of CD133-positive cells, one of the surface markers of bone marrow-derived cells, in Helicobacter pylori-infected gerbils. Methods: 70 gerbils were divided into six groups. Group 1 gerbils served as control (n = 6). 10 gerbils were given N-methyl-N-nitrosourea (MNU), 30 ppm (group 2). 6 short-term Helicobacter pylori-infected gerbils (group 3) were sacrificed after 8 weeks of H. pylori infection and 6 long-term H. pylori-infected gerbils were sacrificed after 42 weeks of H. pylori infection (group 4). 20 gerbils were given MNU pretreatment and long-term H. pylori infection (group 5). In addition, after H. pylori inoculation, 22 gerbils also received a celecoxib in their diet (group 6). CD133 and CCR2 expression in gastric tissues was evaluated by Western blot analysis and immunostaining. Results: CD133-positive cells were mainly localized in the bottom of the gastric epithelial cells. CD133-positive cells also migrated into gastric cancer tissues in this model. CD133-positive cells in MNU-pretreated H. pylori-infected gerbils were significantly increased compared to those in H. pylori short-term infected gerbils. Celecoxib treatment significantly reduced CD133-positive cell migration and CCR2 expression levels. CD133- and CCR2-positive cells were colocalized in H. pylori-infected gastritis and gastric cancer tissues. Celecoxib treatment significantly reduced the number of CD133- and CCR2-positive cells. Conclusions: Celecoxib inhibits CD133-positive cell migration via the reduction of CCR2 in this model. Further studies are needed to clarify the precise mechanisms driving H. pylori infection-induced CD133-positive cell migration and its link to the progression of chronic gastritis into gastric cancer.

Extracellular HSP70 blocks CD40L-induced apoptosis and tubular formation in endothelial cells

Background:  Recent studies have shown that CD40, a key player in angiogenesis and tubular formation, is an extracellular receptor of the heat shock protein 70 (HSP70)–peptide complex in endothelial cells. The aim of the present study was to determine the effect of extracellular HSP70 treatment on CD40L‐suppressed apoptosis and CD40L‐induced tubular formation in human umbilical vein endothelial cells (HUVEC).

Celecoxib Inhibits Apurinic/Apyrimidinic Endonuclease-1 Expression and Prevents Gastric Cancer in Helicobacter pylori-Infected Mongolian Gerbils

Background and Aims: The aim of this study was to see whether administration of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, could prevent the development of gastric cancer via inhibition of apurinic/apyrimidinic endonuclease-1 (APE-1) expression induced by Helicobacter pylori infection. Methods: 70 Mongolian gerbils were divided into 6 groups. Group 1 gerbils served as controls (n = 6). Ten gerbils were given N-methyl-N-nitrosourea (MNU), 30 ppm, 5 times biweekly (group 2). Short-term H. pylori infection was induced in 6 gerbils which were sacrificed 8 weeks after H. pylori infection (group 3). Long-term H. pylori infection was induced in 6 other gerbils which were sacrificed 44 weeks after H. pylori infection (group 4). Twenty gerbils were given MNU pretreatment 5 times biweekly and long-term H. pylori infection (group 5). In addition, after H. pylori inoculation, group 6 gerbils also received celecoxib with their diet for 26 weeks. APE-1 expression alone or with COX-2 in gastric tissues was evaluated by Western blot and immunohistological analysis. Myeloperoxidase (MPO) activity and thiobarbituric-acid-reactive substance (TBARS) levels were also evaluated. Results: APE-1 was localized in gastric epithelial cells and mesenchymal cells including macrophages in H. pylori-infected gerbils. The numbers of APE-1-positive cells in group 4 and 5 were significantly increased compared to those of group 3. Celecoxib treatment significantly reduced MPO activity, TBARS levels and the incidence of gastric cancer. APE-1 and IκBα phosphorylation levels were significantly increased in MNU-pretreated H. pylori-infected gerbils compared to those in MNU-only gerbils. Celecoxib significantly reduced APE-1 and IκBα phosphorylation levels in MNU-pretreated H. pylori-infected gerbils. COX-2 and APE-1 were coexpressed in the macrophages of H. pylori-infected gerbils. Conclusion: Celecoxib prevented gastric cancer in MNU-pretreated H. pylori-infected gerbils with a reduction in APE-1 expression thereby suggesting the implication of APE-1 in gastric carcinogenesis in this model.