Akira Imatani

The Prevalence of Helicobacter Pylori Infection and the Status of Gastric Acid Secretion in Patients with Barrett's Esophagus in Japan

OBJECTIVES:The acidity of the refluxate into the esophagus is a key factor for the pathogenesis of gastroesophageal reflux disease. Helicobacter pylori (H. pylori) infection can influence gastric acid secretion. We have reported that H. pylori infection prevents reflux esophagitis by decreasing gastric acid secretion in Japanese patients, but the role of this organism in Barretts esophagus is unclear. The aim of this study was to investigate the prevalence of H. pylori infection and gastric acid secretion in Japanese patients with reflux esophagitis with or without Barretts esophagus.METHODS:We enrolled 112 reflux esophagitis patients who were examined for the status of H. pylori and acid secretion in this study. They were divided into three groups, according to the presence or absence of Barretts esophagus as follows: reflux esophagitis group without Barretts esophagus (reflux esophagitis alone) (80 patients); short-segment Barretts esophagus group (16 patients); and long-segment Barretts esophagus group (LSBE) (16 patients). Age- and sex-matched control subjects were also assigned to the 80 patients with reflux esophagitis alone. The prevalence of H. pylori infection was determined by histology, rapid urease tests, and serum IgG antibodies. Gastric acid secretion was evaluated by the endoscopic gastrin test (EGT).RESULTS:The overall prevalence of H. pylori infection in the reflux esophagitis patient group (24.1%) was significantly lower than the control group (71.2%) (odds ratio 0.13, 95% confidence interval 0.07–0.24; p < 0.0001). The prevalence of H. pylori infection in the patients with Barretts esophagus tended to be lower than that in the patients with reflux esophagitis alone (reflux esophagitis alone; 30.0%, SSBE; 18.7%, LSBE; 0%), especially in the patients with LSBE compared with the reflux esophagitis alone group (p < 0.01). The EGT value of the respective reflux esophagitis patient group was significantly higher than the control group. The EGT value in the patients with Barretts esophagus tended to be higher than that in the patients with reflux esophagitis alone, but the difference was not statistically significant. When examined in H. pylori-negative subjects, no difference was found in the EGT value between the control subjects and the patients with reflux esophagitis alone, but it was significantly higher in patients with Barretts esophagus than the control subjects (p < 0.05). On the other hand, when examined in the H. pylori-positive subjects, the EGT value was significantly higher in the patients with reflux esophagitis alone than in the control subjects (p < 0.01).CONCLUSIONS:H. pylori infection may play a protective role in the development of Barretts esophagus, especially in the development of LSBE in Japan. Gastric acid hypersecretion may be concerned with the development of Barretts esophagus in addition to the absence of H. pylori infection.

Long-term effect of Helicobacter pylori eradication on the reversibility of acid secretion in profound hypochlorhydria

Background : Although profound hypochlorhydria is considered to be an important risk factor for development of gastric cancer, long‐term effect of Helicobacter pylori eradication on its reversibility remains uncertain.

Helicobacter pylori induces gastric mucosal intestinal metaplasia through the inhibition of interleukin-4-mediated HMG box protein Sox2 expression

Helicobacter pylori is a major cause of the transdifferentiation into intestinal metaplasia that may develop gastric cancer. However, the molecular pathogenesis of this transdifferentiation is poorly understood. A SRY-related HMG box protein Sox2 is an essential transcription factor of organ development in brain, lung, and stomach. Our aim of this study was to investigate the mechanism responsible for regulation of Sox2 in host Th1-dominant response to H. pylori. Sox2 protein was immunohistochemically expressed in both human oxyntic and pyloric glands with H. pylori infection, but not in intestinal metaplasia. Western immunoblotting of gastric epithelial cell lines showed that IL-4, a Th2-related cytokine, dose dependently enhanced Sox2 expression among H. pylori infection-mediated cytokines. Small changes of Sox2 expression were observed after each treatment with IFN-gamma, IL-1beta, or TNF-alpha. IL-4-mediated Sox2 induction was suppressed by the inhibition of STAT6 activation with STAT6 RNA interference, and electrophoretic mobility shift assay indicated that activation of the Sox2 promoter by IL-4 occurred through the action of STAT6. Furthermore, H. pylori and IFN-gamma inhibited the phosphorylation of STAT6, resulting in the suppression of IL-4-mediated Sox2 expression. Immunohistochemical analyses showed significantly the suppressed STAT6 activity in H. pylori-infected human gastric mucosa. Additionally, downregulation of Sox2 by knockdown experiments led to intestinal phenotype with expressions of Cdx2 and MUC2. These results suggest that H. pylori and IFN-gamma interfere with the differentiation into oxyntic and pyloric glands by the downregulation of Sox2 on IL-4/STAT6 signaling, which may contribute to the transdifferentiation into intestinal metaplasia.

Preservation of gastric acid secretion may be important for the development of gastroesophageal junction adenocarcinoma in Japanese people, irrespective of the H. pylori infection status

BACKGROUND:We have previously reported that Helicobacter pylori infection prevents reflux esophagitis (RE) and Barretts esophagus (BE) by decreasing gastric acid secretion. Gastroesophageal (GE) junction adenocarcinoma, including Barretts adenocarcinoma, has been thought to be a complication of gastroesophageal reflux disease (GERD). However, the relationship between H. pylori infection, gastric acid secretion, and GE junction adenocarcinoma has not yet been investigated in Japan. The aim of this study was to evaluate this relationship in the Japanese population.METHODS:A total of 168 Japanese patients (RE alone: 80, short-segment BE (SSBE): 16, long-segment BE (LSBE): 20, GE junction adenocarcinoma: 12, distal early gastric cancer (EGC): 40; male/female = 106/62; mean age 61.5 yr) and 80 Japanese control subjects who had no localized lesions in the upper gastrointestinal tract (male/female = 43/37, mean age 58.1 yr) were enrolled for this study. The prevalence of H. pylori infection was determined by biopsy, the rapid urease test, and measurement of the serum H. pylori IgG antibody. Gastric acid secretion was assessed by the endoscopic gastrin test (EGT). RE was diagnosed according to the Los Angeles classification.RESULTS:The prevalence of H. pylori infection in the patients with RE alone (30%) was significantly lower than that in control subjects (71.2%). There was also a tendency for the prevalence of H. pylori infection to be lower in patients with BE (SSBE, 18.7%; LSBE, 0%) when compared to that in patients with RE alone. On the other hand, while the prevalence of H. pylori infection in patients with GE junction adenocarcinoma (58.3%) was significantly lower than that in patients with EGC (87.5%), it tended to be higher than that in patients with RE alone or BE. The mean EGT value in patients with RE alone (3.74 mEq/10 min) was significantly higher than that in control subjects (1.83). The mean EGT value in patients with BE (SSBE, 4.74; LSBE, 4.76) tended to be even higher than that in patients with RE alone. The mean EGT value in patients with GE junction adenocarcinoma (3.94) was significantly higher than that in control subjects and patients with EGC (0.67), but it was comparable to that independent of the H. pylori infection status in patients with RE alone or BE.CONCLUSION:Preservation of gastric acid secretion may be important for the development of GE junction adenocarcinoma in Japanese people, irrespective of the H. pylori infection status.

Exogenous luminal nitric oxide exacerbates esophagus tissue damage in a reflux esophagitis model of rats

Objective. Cytotoxic concentrations of nitric oxide are generated luminally at the gastroesophageal junction through the entero-salivary recirculation of dietary nitrate in humans. The site of luminal nitric oxide generation shifts to the lower esophagus when gastric acid is refluxed into the esophagus. The aim of this study was to investigate the influence of persistent administration of exogenous nitric oxide on esophageal damage. Material and methods. 0.1% sodium nitrite and/or 1% ascorbic acid was administered in an established rat acid-refluxed esophagitis model. Co-administration of both reactants in this model is thought to induce high concentrations of nitric oxide luminally in the esophagus by an acid-catalyzed chemical reaction when refluxed gastric acid is present. The tissue damage was evaluated by a macroscopic lesion index and myeloperoxidase activity. Nitrotyrosin was assessed immunohistochemically as a footprint of peroxynitrite formation. Results. Co-administration of sodium nitrite and ascorbic acid induced a 4- to 5-fold increase in the esophageal damage compared with baseline reflux esophagitis, while the damage was unchanged when either of the reagents alone was given. Nitrotyrosine was strongly stained in the tissue from the co-administration. Treatment of superoxide scavengers efficiently prevented the exacerbation of esophageal damage by exogenous nitric oxide exposure, suggesting an essential role of superoxide in esophageal damage. Conclusions. Exogenous luminal nitric oxide greatly exacerbated the tissue damage of reflux esophagitis. Diffusion of the luminal nitric oxide into the adjacent superoxide-enriched inflamed tissue of the esophagus could lead to the production of the highly toxic agent peroxynitrite, thus causing exacerbation of the esophageal damage.

Optical coherence tomography for the staging of tumor infiltration in superficial esophageal squamous cell carcinoma.

BACKGROUND Optical coherence tomography (OCT) is a noninvasive technology that can produce high-resolution cross-sectional images in real-time without acoustic coupling, enabling precise assessment of tumor invasion in superficial esophageal squamous cell carcinomas (SESCCs). OBJECTIVE To elucidate the usefulness of in vivo OCT for the staging of SESCCs. DESIGN A single-center, prospective study in 2 phases: phase I to establish the OCT criteria classified into 3 categories (epithelium or lamina propria mucosa [EP/LPM], muscularis mucosa [MM], submucosa [SM]) and phase II to evaluate these criteria. SETTING An academic medical center. PATIENTS Sixty-two patients with a histological diagnosis of SESCC by routine endoscopy. In the phase I study, 35 images from 16 patients were used. In the phase II study, 109 images from 46 subsequent consecutive patients enrolled from January 2007 to May 2009 were used. INTERVENTIONS We performed OCT for preoperative staging followed by endoscopic submucosal dissection or a surgical procedure and compared precisely the visualized OCT sites with the corresponding tissue sections. MAIN OUTCOME MEASUREMENTS The accuracy of OCT for the staging. RESULTS The overall accuracy rate was 92.7% (EP/LPM, 94.9%; MM, 85.0%; SM, 90.9%). The OCT signal penetration depth was sufficient to depict the boundary of the deepest region of cancer, the thickness of which was less than 1.5 mm. LIMITATIONS The small number of patients. CONCLUSIONS To our knowledge, this is the first study demonstrating that OCT might be useful for the preoperative staging of SESCCs with a high degree of accuracy.

Extensive Gastric Atrophy: An Increased Risk Factor for Superficial Esophageal Squamous Cell Carcinoma in Japan

OBJECTIVES:A recent study in Sweden has reported that gastric atrophy is associated with an increased risk for esophageal squamous cell carcinoma. However, this finding needs to be confirmed in other ethnic groups due to the wide geographic variation of this cancer.OBJECTIVES:To investigate whether gastric atrophy is associated with a risk for esophageal squamous cell carcinoma using a case-control study in Japanese subjects, a population known to have a high prevalence of H. pylori infection and accompanying gastric atrophy.METHODS:Seventy-three patients who had undergone endoscopic mucosal resection for superficial esophageal squamous cell carcinoma, and 73 sex- and age-matched controls, were enrolled prospectively. Gastric fundic atrophy was evaluated by histology of biopsy specimens and serum pepsinogen I level (cutoff level 25 ng/mL). Conditional logistic regression model with adjustment for potential confounding factors was used to assess the associations.RESULTS:Gastric atrophy, defined histologically or serologically, was independently associated with an increased risk for esophageal squamous cell carcinoma and the risk seemed to increase with the progression of the atrophy. Multivariate odds ratio (95% confidence interval) for histological fundic atropy, fundic intestinal metaplasia, and serological atrophy are 4.2 (1.5–11.7), 10.7 (2.3–50.4), and 8.2 (2.2–30.4), respectively.CONCLUSIONS:Gastric atrophy, a newly recognized risk factor for esophageal squamous cell carcinoma in Sweden, is likely to be a risk factor in other areas. Further studies are warranted to explore the causal relationship.

A prospective comparative study of optical coherence tomography and EUS for tumor staging of superficial esophageal squamous cell carcinoma

BACKGROUND The precise assessment of superficial esophageal squamous cell carcinomas (SESCCs) limited to the epithelium (EP) or lamina propria mucosa (LPM), the standard indication for endoscopic resection, is important to ensure good outcomes of endoscopic resection. With regard to tomographic imaging techniques, although the accuracy of EUS is practically insufficient, we previously demonstrated that high-resolution optical coherence tomography (OCT) might enable precise assessment for staging in a noninvasive and real-time manner. OBJECTIVE To clarify the accuracy of the preoperative staging of SESCCs by using OCT compared with that by using 20-MHz probe-type EUS. DESIGN A prospective study. SETTING An academic medical center. PATIENTS A total of 123 consecutive patients with 131 SESCCs were enrolled from May 2007 to September 2011. INTERVENTIONS A specialist examined the patients, by using both OCT and EUS, recorded a representative still image for each lesion, and reported the staging immediately after each examination. Another blinded investigator reviewed the recorded images and reported the staging independently. The histological staging was confirmed by the resected specimens. Finally, we calculated the accuracy of staging by using OCT and EUS. MAIN OUTCOME MEASUREMENTS The accuracy of OCT or EUS for EP/LPM. RESULT The accuracy for EP/LPM by using OCT was significantly higher than that by using EUS (OCT, 94.6%; HF-EUS, 80.6%; P < .05). Interobserver agreement of OCT and EUS was good and moderate, respectively. LIMITATIONS The small number of patients; a single-center, single-operator, nonrandomized, crossover study. CONCLUSIONS We prospectively demonstrated that the preoperative staging of SESCC by using OCT was more useful than that by using EUS.

IN SITU ANALYSIS OF TISSUE DYNAMICS AND p53 EXPRESSION IN HUMAN GASTRIC MUCOSA

In situ tissue dynamics were studied in 12 cases of human gastric mucosa, including normal gastric body mucosa and gastric glands with intestinal metaplasia, obtained from gastrectomy specimens of adenocarcinoma. Cell proliferation was determined by Ki67 immunoreactivity. DNA fragmentation was studied in situ by TdT‐mediated dUTP‐biotin nick end labelling (TUNEL). In addition, p53 expression was examined by both immunohistochemistry and mRNA in situ hybridization. In the oxyntic gastric glands, Ki67 immunoreactivity was observed exclusively in the proliferative zone and TUNEL‐positive cells were present predominantly in the surface foveolar epithelium. In the gastric glands with complete intestinal metaplasia, Ki67‐positive cells were present in the lower portion of the glands and TUNEL‐positive cells in the superficial epithelium. In the gastric glands with incomplete intestinal metaplasia, TUNEL‐positive cells were detected in the lower gastric glands adjacent to cells immunoreactive for Ki67; the proportion of these gastric glands with TUNEL‐positive cells (40 out of 108 glands) was significantly higher than for oxyntic glands (94 out of 620 glands) or for glands with complete metaplasia (31 out of 254 glands). Relatively strong p53 immunoreactivity and mRNA hybridization were also observed in the proliferative and apoptotic areas of gastric glands with incomplete intestinal metaplasia. These results indicate that incomplete intestinal metaplasia is associated with increased cell turnover and p53 overexpression, possibly in response to various noxious or DNA‐damaging stimuli.

Analysis of cell damage in Helicobacter pylori‐associated gastritis

Helicobacter pylori infection is currently considered to be a major cause of acute and chronic gastritis, and of gastric and duodenal ulcers. Superoxide dismutase (SOD) is well known for scavenging superoxide radicals such as reactive oxygen species (ROS), subsequently protecting cells from oxidative injury, and for maintaining tissue homeostasis. In this study, we therefore evaluated the level of SOD activity and protein expression, as well as various factors associated with oxidative injury, in H. pylori‐positive (n = 46) and ‐negative (n = 28) gastric mucosa obtained from endoscopy, in order to elucidate the possible biological significance of SOD in these mucosa. Overall SOD activity was significantly higher in H. pylori‐positive mucosa (15.5 ± 7.0 U/mg protein) than in negative mucosa (9.2 ± 10.6 U/mg protein), and decreased markedly following H. pylori eradication (8.2 ± 4.2 U/mg protein). Enzyme‐linked immunosorbent assay (ELISA) analysis of SOD revealed that the manganese SOD (Mn‐SOD) level in H. pylori‐positive mucosa (1166.7 ± 435.2 ng/mg protein) was significantly higher than in control tissues (446.3 ± 435.3 ng/mg protein) and in mucosa obtained following eradication therapy (431.9 ± 189.9 ng/mg protein). The level of Mn‐SOD protein showed a significant correlation with degree of inflammation in the gastric mucosa. Moreover, Mn‐SOD immunolocalization patterns were well correlated with the activity and protein levels evaluated by ELISA. Factors presumably associated with oxidative injury in human gastric mucosa, including terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin nick‐end labeling, Ki‐67, 8‐hydroxydeoxyguanosine and single‐stranded DNA, were all significantly higher in H. pylori‐positive gastric mucosa than in control tissue and in tissue following eradication. These results all suggest that Mn‐SOD, but not cytoplasmic copper–zinc SOD, plays an important role as an anti‐oxidant against ROS generated in H. pylori‐infected gastric mucosa and, subsequently, in the maintenance of cell turnover in gastric mucosa.