Youichi Miyaoka

Essential Role of MD-2 in TLR4-Dependent Signaling during Helicobacter pylori-Associated Gastritis

TLR4, a member of pattern recognition receptors, is the main receptor of LPS. MD-2 physically associates with TLR4 on the cell surface and confers LPS responsiveness. Helicobacter pylori LPS is one of the major virulence factors for induction of gastritis. We demonstrated in this study the role of MD-2 in TLR4-dependent signaling in H. pylori-associated gastritis. Gastric biopsy samples collected from patients with and without H. pylori infection and four gastric cancer cell lines were used for this study. TLR-4 and MD-2 expression in biopsy specimens and the cell lines was examined by using RT-PCR. Localization of TLR-4 in histological sections was evaluated by immunohistochemistry. For in vitro functional assays, we established stable transfectants of AGS cells expressing TLR4 and MD-2. Cellular distribution of TLR4 was examined by flow cytometry. NF-κB activation and activation of IL-8 and MD-2 promoters were assessed by reporter gene assay. H. pylori infection up-regulated the TLR4 and MD-2 expression in gastric mucosa. TLR4 staining was observed predominantly in epithelial cells, located in both the cytoplasm and at the apical surface. MD-2 transfection in AGS cells markedly increased cell surface expression of TLR4 and augmented the activation of NF-κB and IL-8 promoter upon stimulation with H. pylori LPS. Live H. pylori also stimulated transcriptional activation of MD-2. This study revealed that MD-2 expression is elevated in gastric epithelial cells during H. pylori infection, suggesting that the TLR4/MD-2 system is a potent receptor complex involved in the response to H. pylori LPS in the stomach.

Transgenic overexpression of Reg protein caused gastric cell proliferation and differentiation along parietal cell and chief cell lineages

Reg (regenerating gene product) was originally identified as a growth factor involved in pancreatic regeneration. During the healing course of gastric erosion, Reg expression is highly increased in the enterochromaffin-like (ECL) cells surrounding the ulcer crater, suggesting its role as a regulator of gastric mucosal regeneration. However, there has been no direct in vivo evidence of a growth-promoting role of Reg for the gastric mucosal cells. In the current study, Reg-transgenic mice were created and gastric mucosa were analysed for histological changes. Transgenic mice showed a marked increase in the thickness of the fundic mucosa. Anti-proliferating cell nuclear antigen (PCNA) staining of the fundic mucosa demonstrated the enlargement of the proliferating neck zone and the lower PCNA-negative zone. Histological analysis employing antibodies against cell-type markers revealed expansion of the chief cell and parietal cell populations and no change in the number of surface mucus-producing cells, ECL cells, or G cells. In conclusion, Reg has a growth-promoting effect on gastric progenitor cells and an activity to direct the differentiation of the cells into chief cell and parietal cell lineages. This was in contrast to other factors, all of which had been shown to drive differentiation towards mucus producing cells in vivo. In the injured gastric mucosa, Reg may play a unique and important part in the reconstruction of the properly organized mucosal architecture.

Crystal Violet Chromoendoscopy with Mucosal Pit Pattern Diagnosis is Useful for Surveillance of Short-Segment Barrett's Esophagus

BACKGROUND:Because of a rapid increase in the incidence of Barretts cancer, the appropriate surveillance method for Barretts esophagus is of interest. Methylene blue chromoendoscopy has been reported to be an effective and inexpensive method to improve biopsy surveillance of Barretts epithelium. However, the usefulness of this method in short-segment Barretts esophagus cases is still controversial.AIMS:This study was undertaken to evaluate the abilities of crystal violet and methylene blue chromoendoscopy to detect potentially dysplastic Barretts epithelium in cases with short-segment columnar-appearing epithelium of the esophago-gastric junction.PATIENTS AND METHODS:Four hundred patients with endoscopically suspected short-segment Barretts esophagus were enrolled and randomly assigned to receive chromoendoscopy with 0.05% crystal violet, 0.1% crystal violet, 0.5% methylene blue, or 1.0% methylene blue. During crystal violet and methylene blue chromoendoscopy, biopsy specimens were obtained from stained and unstained columnar-appearing epithelium of the esophago-gastric junction, and the detection rates of Barretts epithelium were evaluated. The value of pit pattern diagnosis was also evaluated as a possible way to detect dysplastic Barretts epithelium.RESULTS:Chromoendoscopy with 0.05% crystal violet detected histologically confirmed Barretts epithelium with the highest sensitivity (89.2%) and specificity (85.7%). Crystal violet clearly stained both dysplastic and nondysplastic Barretts epithelia and made the surface pit pattern easy to observe without using magnifying endoscopy.CONCLUSIONS:The combination of crystal violet chromoendoscopy and pit pattern diagnosis is considered to be useful for the surveillance of short-segment Barretts esophagus.

Reg protein is overexpressed in gastric cancer cells, where it activates a signal transduction pathway that converges on ERK1/2 to stimulate growth.

Reg is a growth factor with mitogenic effects on pancreatic β cells and gastric stem cells. To date, there has been no information available on Reg‐mediated intracellular signal transduction pathways. The role of Reg in the gastric carcinogenesis is also unknown. In the current study, the Reg signaling pathway in gastric cancer cell was examined. Reg treatment of MKN45 gastric cancer cells resulted in tyrosyl‐phoshorylation of several cellular proteins and subsequent activation of classical MAPK, ERK1/2. Reg also stimulated thymidine incorporation in MKN45 and AGS gastric cancer cells in a dose‐dependent manner. Finally, Reg was shown to be highly expressed in a large number of gastric cancers in vivo. Taken together, these data suggest that gastric cancer cells have gained the ability to overexpress Reg protein, which confer upon themselves added proliferative capacities, resulting in a considerable growth advantage.

A study of arteriosclerosis in healthy subjects with HBV and HCV infection.

BackgroundIt is unclear whether infection with hepatitis B virus (HBV) or hepatitis C virus (HCV) affects arteriosclerosis. We performed a cross-sectional study to clarify the effect of HBV and HCV infection on arteriosclerosis.MethodsThe study subjects were 1806 healthy individuals who visited Shimane Environment and Health Public Corporation for routine medical check-ups. Serum levels of total cholesterol, high-density lipoprotein (HDL)-cholesterol, triglycerides, and blood glucose were investigated in all subjects. The degree of arteriosclerosis was assessed using systolic blood pressure, the bilateral ankle brachial index (ABI), the heart-carotid pulse wave velocity (HCPWV), and the heart-ankle PWV (HAPWV). These cardiovascular parameters were compared between control subjects and subjects with HBV and HCV infection, using analysis of covariance to adjust for confounding factors (sex, age, body mass index, and smoking and drinking).ResultsOf the 1806 subjects, 39 and 31 were diagnosed as positive for HBV and HCV infection, respectively. The remaining 1736 were considered to be the controls. Adjusted serum lipid levels in the subjects with HBV and those with HCV infection tended to be lower than those in the control subjects. Adjusted arteriosclerotic parameters in the subjects with HBV and HCV infection were similar to those in the control subjects, even after adjusting for serum lipid levels.ConclusionsInfection with HBV or HCV does not influence the severity of arteriosclerosis in healthy subjects.

Barrett's oesophagus with predominant intestinal metaplasia correlates with superficial cyclo-oxygenase-2 expression, increased proliferation and reduced apoptosis: changes that are partially reversed by non-steroidal anti-inflammatory drugs usage.

Background : Cyclo‐oxygenase‐2 expression has been reported to play an important role in the metaplasia‐dysplasia‐carcinoma sequence in Barretts oesophagus. However, the existence of cyclo‐oxygenase‐2 expressing cells in Barretts epithelium is still uncertain.

Pulse-wave velocity and cardiovascular risk factors in subjects with Helicobacter pylori infection

Background: Helicobacter pylori infection has been reported to correlate with the onset of cardiovascular diseases. However, the relationship between H. pylori infection and the development of arteriosclerosis has not been fully investigated. We performed a cross‐sectional study to clarify the possible role of H. pylori infection in the development of arteriosclerosis.

Is a computerized bowel sound auscultation system useful for the detection of increased bowel motility

pylori positive status indicated a weak correlation (r 0.267, p 0.05) between the bacterial burden of gastric mucosa and the GUA ratio. However, we failed to find any significant correlation between the GUA ratio and colonization density of H. pylori in children with peptic ulcers (r 0.454, p 0.05) and in the H. pylori positive children without ulcers (r 0.174, p 0.05). Significant correlation was observed between GUA ratio and gastric inflammation score (r 0.406, p 0.01) in the total H. pylori positive group. However, the GUA ratio did not correlate with gastritis severity in the patients with peptic ulceration (r 0.358, p 0.05) and in the H. pylori negative patients (r 0.02, p 0.05). Nevertheless, there was a significant positive correlation between GUA ratio and the gastritis score in the ulcer-free group of children with H. pylori positive status (r 0.416, p 0.05). It is well known that H. pylori produce large amounts of the enzyme urease. Unusually high urease activity of H. pylori may allow consideration of urease as a specific marker of the infection (1, 2). The standard biopsy-dependent urease tests are very specific but moderately sensitive because of patchy dissemination of H. pylori on the gastric mucosa (4). Noninvasive C urea breath tests have great sensitivity and safety, but they are very expensive techniques. In the present study we propose a sensitive, cheap, and biopsy-independent minimally invasive method for rapid H. pylori detection. The present procedure is more suitable for pediatric practice because it is a safer technique than the standard local biopsy-dependent methods. The presented data on the diagnostic importance of the GUA ratio are comparable with the results obtained by the noninvasive C urea breath test (5). Therefore, the GUA measurement method is an excellent surrogate marker that reflects the total urease activity in the stomach but does not predict density of the bacterial load on the gastric mucosa. Finally, the current findings are mainly in agreement with our previous data on the lack of a relationship between the H. pylori urease activity and duodenal ulceration in childhood (2, 6).

Study of arteriosclerosis in patients with hiatal hernia and reflux esophagitis

Background and Aim:  It has been reported that the prevalence of hiatal hernia (HH) and reflux esophagitis (RE) increases with age, as does the degree of arteriosclerosis. However, it has not been investigated whether or not arteriosclerosis is correlated with the presence of HH and RE. Therefore, we prospectively investigated the degree of arteriosclerosis in patients with HH and RE compared with subjects without HH and RE.

The role of enhanced multi-detector-row computed tomography before urgent endoscopy in acute upper gastrointestinal bleeding

Multi‐detector‐row computed tomography (MDCT) has been reported to be a potentially useful modality for detection of the bleeding origin in patients with acute upper massive gastrointestinal (GI) bleeding. The purpose of this study is to investigate the efficacy of MDCT as a routine method for detecting the origin of acute upper GI bleeding prior to urgent endoscopy.