Yohei Mizuta

Endoscopic submucosal dissection for early gastric cancer: a large-scale feasibility study

Objective: Endoscopic submucosal dissection (ESD) has the advantage over conventional endoscopic mucosa resection, permitting removal of early gastric cancer (EGC) en bloc, but long-term clinical outcomes remain unknown. A follow-up study on tumour recurrence and survival after ESD was conducted. Method: ESD was performed for patients with EGC that fulfilled the expanded criteria: mucosal cancer without ulcer findings irrespective of tumour size; mucosal cancer with ulcer findings ⩽3 cm in diameter; and minute submucosal invasive cancer ⩽3 cm in size. 551 patients with 589 EGC lesions were enrolled. The patients underwent ESD and then received periodic endoscopic follow-up and metastatic surveys for 6–89 months (median, 30 months). The main outcome measures were resectability (en bloc or piecemeal resection), and curability (curative or non-curative). Complications were assessed, and factors related to each were analysed statistically. The overall and disease-free survival rates were estimated. Results: En bloc resection was achieved in 94.9% (559/589), and larger lesions were at higher risk of piecemeal resection. 550 of 581 lesions (94.7%) were deemed to have undergone curative resection. En bloc resection was the only significant contributor to curative ESD. Patients with non-curative resection developed local recurrence more frequently. The 5-year overall and disease-specific survival rates were 97.1% and 100%, respectively. Conclusion: Precise assessment of curability with successful one-piece resection may reduce tumour recurrence after ESD. The prognosis of EGC patients treated by ESD is likely to be excellent, though further longer follow-up studies are warranted.

Fatty liver in non-alcoholic non-overweight Japanese adults: Incidence and clinical characteristics

Background and Aims: Fatty liver is not uncommon in many countries, including Japan, and is mainly caused by alcohol usage and obesity. The aim of this study was to determine the incidence and causative factors of fatty liver in Japanese adults.

Reversal of breast cancer resistance protein (BCRP/ABCG2)-mediated drug resistance by novobiocin, a coumermycin antibiotic

Breast cancer resistance protein (BCRP/ABCG2) of an ATP‐binding cassette half‐transporter confers resistance against mitoxantrone and camptothecin derivatives of topotecan and irinotecan. Novobiocin, a coumermycin antibiotic, is known to enhance anticancer drug sensitivity of cancer cells in vitro and in vivo, the mechanism of which remains undetermined. Here we focused on drug efflux pump and examined whether novobiocin reversed drug resistance in multidrug‐resistant cells highly expressing BCRP. To explore the reversal mechanisms, intracellular drug accumulation was measured by flow cytometry, and a topotecan transport study using plasma membrane vesicles was performed. We used PC‐6/SN2‐5H2 small cell lung cancer and MCF‐7/MX breast cancer cells selected with SN‐38 of the active irinotecan metabolite and mitoxantrone, respectively, and the BCRP cDNA transfectant MCF‐7/clone 8 cells. These cells expressed high levels of BCRP mRNA but not other known transporters. Compared to the parental PC‐6 cells, PC‐6/SN2‐5H2 cells were 141‐, 173‐ and 57.2‐fold resistant to topotecan, SN‐38 and mitoxantrone, respectively. Novobiocin at 60 μM decreased the degree of the above resistance by approximately 26‐fold in PC‐6/SN2‐5H2 cells, and similarly reversed resistance in MCF‐7/MX, MCF‐7/clone 8 and un‐selected NCI‐H460 cells highly expressing BCRP. Furthermore, novobiocin increased the intracellular topotecan accumulation in these cells and inhibited the topotecan transport into the membrane vesicles of PC‐6/SN2‐5H2 cells. No effects of novobiocin in these assay were observed in the parental PC‐6 and MCF‐7 cells. The kinetic parameters in the transport study indicated that novobiocin was a inhibitor for BCRP, resulting in competitive inhibition of BCRP‐mediated topotecan transport. These findings suggest that novobiocin effectively overcomes BCRP‐mediated drug resistance at acceptable concentrations.

Azithromycin Inhibits MUC5AC Production Induced by the Pseudomonas aeruginosa Autoinducer N-(3-Oxododecanoyl) Homoserine Lactone in NCI-H292 Cells

ABSTRACT The features of chronic airway diseases, including chronic bronchitis, cystic fibrosis, bronchiectasis, and diffuse panbronchiolitis, include chronic bacterial infection and airway obstruction by mucus. Pseudomonas aeruginosa is one of the most common pathogens in chronic lung infection, and quorum-sensing systems contribute to the pathogenesis of this disease. The quorum-sensing signal molecule [N-(3-oxododecanoyl) homoserine lactone (3O-C12-HSL)] not only regulates bacterial virulence but also is associated with the immune response. In this study, we investigated whether 3O-C12-HSL could stimulate the production of a major mucin core protein, MUC5AC. The effect of a macrolide on MUC5AC production was also studied. 3O-C12-HSL induced NCI-H292 cells to express MUC5AC at both the mRNA and the protein levels in time- and dose-dependent manners. A 15-membered macrolide, azithromycin, inhibited MUC5AC production that was activated by 3O-C12-HSL. 3O-C12-HSL induced extracellular signal-regulated kinase (ERK) 1/2 and I-κB phosphorylation in cells, and this induction was suppressed by azithromycin. 3O-C12-HSL-induced MUC5AC production was blocked by the ERK pathway inhibitor PD98059. Our findings suggest that the P. aeruginosa autoinducer 3O-C12-HSL contributes to excessive mucin production in chronic bacterial infection. Azithromycin seems to reduce this mucin production by interfering with intracellular signal transduction.

Elevated levels of chemokines in esophageal mucosa of patients with reflux esophagitis.

Abstract Objective Chemokines play a key role in the pathogenesis of various inflammatory conditions. However, there is little information on their profile in reflux esophagitis (RE). We sought to study esophageal mucosa levels of chemokines in RE. Methods A total of 32 outpatients with RE and 13 normal controls were studied. Endoscopic severity of RE was classified according to the Los Angeles grading system. Paired biopsy specimens were taken from the esophagus 3 cm above the gastroesophageal junction; one biopsy was snap frozen for measurement of mucosal levels of interleukin 8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), regulated on activation normal T-cell expressed and presumably secreted (RANTES), and IL-1β by enzyme linked immunosorbent assays, while the other was formalin-fixed for histopathological evaluation. Results IL-8, MCP-1, and RANTES levels were significantly higher in esophageal mucosa of RE patients than those of the controls. IL-8 levels correlated significantly with the endoscopic severity of RE. Basal zone hyperplasia and papillary elongation, histopathological hallmarks of RE, were both associated with higher levels of IL-8 and MCP-1. The presence of intraepithelial neutrophils and eosinophils, which also indicate RE, was associated with high levels of IL-8 and RANTES, respectively. There were no significant differences in IL-1β levels between the RE and control groups, but IL-1β levels correlated significantly with the IL-8 production. Again, the IL-8 levels were significantly decreased after lansoprazole treatment. Conclusion Our results indicate that chemokines produced locally in the esophageal mucosa may be involved in the development and progression of RE.

Impact of Helicobacter pylori infection on gastric and plasma ghrelin dynamics in humans.

OBJECTIVES:There are contradictory reports on the relationship between Helicobacter pylori and circulating ghrelin. We sought to clarify the influence of H. pylori infection on gastric and plasma ghrelin dynamics in humans.METHODS:Using endoscopic biopsies from the corpus of 56 H. pylori-infected patients and 25 uninfected subjects, ghrelin mRNA expression levels and gastric ghrelin peptide contents were measured by real-time polymerase chain reaction and radioimmunoassay, respectively. We also measured plasma ghrelin concentrations and analyzed the numbers of ghrelin immunoreactive cells in the fundic gland area. Fifty-one patients with H. pylori infection were treated with a 7-day triple therapy consisting of lansoprazole, clarithromycin, and amoxicillin.RESULTS:The gastric ghrelin mRNA expression level of H. pylori-positive patients (1.64 ± 1.27 in arbitrary units) was significantly lower than in H. pylori-negative subjects (4.87 ± 4.1, p < 0.0001). A similar trend was noted for ghrelin peptide contents (31.2 ± 27.5 vs 81.2 ± 64.1 ng/mg protein, respectively, p < 0.0001). There was no significant difference in the number of ghrelin immunoreactive cells/mm2 in terms of H. plyori status. Plasma ghrelin concentrations in H. pylori-infected patients (144.6 ± 7.8.8 fmol/ml) were significantly lower than in uninfected subjects (196.1 ± 97.2, p < 0.05) and increased following cure of the infection. Plasma ghrelin levels correlated positively with the expression levels of ghrelin mRNA (r = 0.583, p < 0.0001) and peptide products (r = 0.574, p < 0.0001). There was a significant stepwise decrease in gastric ghrelin mRNA expression (p < 0.05), peptide contents (p < 0.01) and density of ghrelin immunoreactive cells (p < 0.05) with progression of histological severity of glandular atrophy in the corpus. The histological severity of chronic inflammation also negatively influenced the ghrelin mRNA expression (p < 0.001) and peptide production (p < 0.005).CONCLUSIONS:H. pylori infection has a negative impact on gastric and plasma ghrelin dynamics. Chronic inflammatory and atrophic changes associated with the infection may affect gastric ghrelin biosynthesis and contribute to the low circulating levels.

Impaired nitrergic innervation in rat colitis induced by dextran sulfate sodium

BACKGROUND & AIMS The pathophysiological role of neuronal nitric oxide synthase (nNOS) in colitis remains unknown. METHODS We investigated colonic transit, nonadrenergic, noncholinergic (NANC) relaxation, nNOS activity, and nNOS synthesis in the myenteric plexus in dextran sulfate sodium (DSS)-induced colitis in rats. RESULTS Oral administration of 5% DSS for 7 days induced predominant distal colitis and delayed colonic transit. In the proximal colon, carbachol-, sodium nitroprusside-, and electrical field stimulation (EFS)-induced responses were not different between control and DSS-treated rats. In the distal colon, EFS-evoked cholinergic contraction, NANC relaxation, and orphanin FQ-induced contraction were significantly impaired in DSS-treated rats compared with those in control rats, but carbachol- and sodium nitroprusside-induced responses remained intact in DSS-treated rats. The number of nNOS-immunopositive cells, catalytic activity of NOS, and nNOS synthesis in the colonic wall were significantly reduced in the distal colon of DSS-treated rats. In contrast, the number of PGP 9.5-immunopositive cells and PGP 9.5 synthesis in the colonic wall remained intact in the distal colon of DSS-treated rats. CONCLUSIONS These results suggest that impaired NANC relaxation in the distal colon is associated with reduced activity and synthesis of nNOS in the myenteric plexus in DSS-induced colitis.

Enhanced Expression of Interleukin-8 and Activation of Nuclear Factor Kappa-B in Endoscopy-negative Gastroesophageal Reflux Disease

OBJECTIVE:Interleukin-8 (IL-8) mediates neutrophil trafficking via its receptors. Recent studies have shown that IL-8 is likely involved in the development and progression of erosive reflux esophagitis (RE), yet little is known about its implication in endoscopy-negative gastroesophageal reflux disease (GERD). The purpose of this study was to determine IL-8 messenger ribonucleic acid (mRNA) expression levels in endoscopy-negative GERD, along with assessment of nuclear factor kappaB (NF-κB) activation, which upregulates IL-8 expression.METHODS:We studied 31 patients with endoscopy-negative GERD, 15 patients with erosive RE, and 15 asymptomatic controls. Paired biopsy samples were taken from the esophagus 3 cm above the gastroesophageal junction; one biopsy was snap-frozen for measurement of IL-8 mRNA levels by real-time quantitative polymerase chain reaction, and another was formalin-fixed for histopathological evaluation. In nine endoscopy-negative GERD patients, the IL-8 mRNA expression levels were measured before and 8 wk after treatment with lansoprazole. We also sampled additional specimens for NF-κB-DNA binding assay and immunohistochemical analyses of NF-κB p65 and p50 subunits, IL-8 and specific IL-8 receptor, CXCR-1.RESULTS:The relative IL-8 mRNA expression levels were significantly higher in esophageal mucosa of patients with endoscopy-negative GERD than those of the controls. The presence of basal zone hyperplasia and intraepithelial neutrophils, histopathological hallmarks of GERD, were associated with higher levels of IL-8 mRNA. Lansoprazole treatment significantly reduced the IL-8 mRNA expression levels. The esophageal epithelium of patients with GERD showed intense immunoreactivity for IL-8, and expressed CXCR-1 antigen. We found NF-κB activation in esophageal mucosa in GERD patients and the NF-κB subunits were localized predominantly in the nuclei of IL-8-expressing cells.CONCLUSIONS:Our results demonstrate enhanced mucosal expression of IL-8 in incipient GERD even without mucosal breaks. NF-κB activation may be implicated in the pathogenesis in GERD.

Implication of NF-kappaB in Helicobacter pylori-associated gastritis

OBJECTIVE:Transcription factor NF-κB plays a pivotal role in inflammatory responses by up-regulating mRNA expression of bioactive molecules such as chemokines and adhesion molecules. The present study was designed to elucidate the implication of NF-κB in Helicobacter pylori–associated gastritis (HAG).METHODS:We examined 41 patients with HAG and 18 H. pylori–negative control subjects. Expression of activated NF-κB was studied in situ by immunohistochemistry using α-p65 mouse monoclonal antibody (α-p65 mAb), which recognizes activated NF-κB. To identify the cell types in which NF-κB was activated, we performed immunohistochemical analysis using antibodies against vascular endothelial cells, macrophages, and B and T lymphocytes. We also examined the colocalization of activated NF-κB with the expression of intercellular adhesion molecule-1 (ICAM-1) on endothelial cells. We measured the levels of NF-κB–dependent chemokines including interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1), regulated on activation normal T-cell expressed and secreted (RANTES) and macrophage inflammatory protein-1α (MIP-1α) in antral mucosa by ELISA (ELISA).RESULTS:Activated NF-κB was detected in the nuclei of epithelial cells in antral mucosa, especially of patients with HAG. NF-κB positivity index (NF-κB PI), representing the percentages of epithelial cells with positive nuclear staining for activated NF-κB, was significantly higher in patients with HAG than in H. pylori–negative controls. NF-κB PI correlated significantly with histological scores of gastritis. Moreover, activated NF-κB was identified in the nuclei of vascular endothelial cells, macrophages, and B lymphocytes within the lamina propria in HAG. Colocalization of activated NF-κB with ICAM-1 expression in the same endothelial cells was demonstrated. The IL-8 levels significantly correlated with the NF-κB PI.CONCLUSIONS:In addition to epithelial cells, macrophages, vascular endothelial cells, and B lymphocytes contained activated NF-κB. In these cells, activated NF-κB may be involved in the inflammation process in HAG through the up-regulation of chemokines or adhesion molecules.

Differing effects of clarithromycin and azithromycin on cytokine production by murine dendritic cells

The macrolide antibiotics are now well known to have anti‐inflammatory effects. Because dendritic cells (DCs) orchestrate immune responses, we examined the in vitro effects of clarithromycin (CAM), azithromycin (AZM) and midecamycin (MDM) on the expression of co‐stimulatory molecules and production of cytokines [interleukin (IL)‐10, IL‐6, interferon (IFN)‐γ, IL‐12p40, tumour necrosis factor (TNF)‐α] of murine bone marrow‐derived DCs by lipopolysaccharide (LPS) stimulation. A 15‐membered macrolide, AZM, and a 14‐membered macrolide, CAM, significantly enhanced the intensity of a co‐stimulatory molecule, CD80, on DCs but not CD86 and CD40. AZM significantly increased the production of IL‐10 and CAM significantly inhibited the production of IL‐6 by DCs. However, a 16‐membered macrolide, MDM, did not have any significant effect on these surface markers and cytokine productions. Moreover, AZM increased IL‐10 and CAM decreased IL‐2 productions significantly, when naive T cells derived from spleen were co‐cultured with DCs treated in advance with LPS and these macrolides. These findings suggest that 14‐membered and 15‐membered, but not 16‐membered macrolides play as anti‐inflammatory agents, at least in part, through modulating the functions of DCs. However, each macrolide affects them in different ways.