Takafumi Ando

Helicobacter pylori strain-specific differences in genetic content, identified by microarray, influence host inflammatory responses

Helicobacter pylori enhances the risk for ulcer disease and gastric cancer, yet only a minority of H. pylori-colonized individuals develop disease. We examined the ability of two H. pylori isolates to induce differential host responses in vivo or in vitro, and then used an H. pylori whole genome microarray to identify bacterial determinants related to pathogenesis. Gastric ulcer strain B128 induced more severe gastritis, proliferation, and apoptosis in gerbil mucosa than did duodenal ulcer strain G1.1, and gastric ulceration and atrophy occurred only in B128+ gerbils. In vitro, gerbil-passaged B128 derivatives significantly increased IL-8 secretion and apoptosis compared with G1.1 strains. DNA hybridization to the microarray identified several strain-specific differences in gene composition including a large deletion of the cag pathogenicity island in strain G1.1. Partial and complete disruption of the cag island in strain B128 attenuated induction of IL-8 in vitro and significantly decreased gastric inflammation in vivo. These results indicate that the ability of H. pylori to regulate epithelial cell responses related to inflammation depends on the presence of an intact cag pathogenicity island. Use of an H pylori whole genome microarray is an effective method to identify differences in gene content between H. pylori strains that induce distinct pathological outcomes in a rodent model of H. pylori infection.

Outcome after enteroscopy for patients with obscure GI bleeding : diagnostic comparison between double-balloon endoscopy and videocapsule endoscopy

BACKGROUND Double-balloon endoscopy (DBE) and videocapsule endoscopy (VCE) have been useful in managing obscure GI bleeding (OGIB). OBJECTIVE This study compared diagnostic yields of OGIB between DBE and VCE, and evaluated the outcome after DBE. DESIGN A single-center retrospective study. SETTING A tertiary-referral hospital. PATIENTS Between June 2003 and February 2007, 162 consecutive patients with OGIB were enrolled and treated. The diagnostic yield between VCE and DBE was compared in 74 patients. MAIN OUTCOME MEASUREMENTS Comparison of diagnostic yields between DBE and VCE, and the prognosis after DBE. RESULTS Of 162 patients, 95 (59%) were diagnosed with small-bowel diseases. They were treated by medical, enteroscopic, and surgical therapies (n = 35, 30, and 30, respectively). A comparison of the overall diagnostic yield between DBE (64%) and VCE (54%) was not significantly different. The 4 VCE-positive DBE-negative cases were because of inaccessibility of DBE. The 11 VCE-negative DBE-positive cases were because of a failure to detect lesions in the proximal small bowel and the Roux-en-Y loop, and because of diverticula. At a median follow-up of 555 days after DBE, 11 patients with small-bowel diseases developed rebleeding; all were treated by enteroscopic or medical therapies. Vascular diseases, comorbidities, especially portal hypertensive disease and chronic renal failure that required hemodialysis, and severe anemia (Hb </=7.0 g/dL) were associated with rebleeding. LIMITATIONS A retrospective comparative study, and participation bias. CONCLUSIONS A complementary combination between DBE and VCE was useful for the management of OGIB. In particular, patients with vascular disease, comorbidities, and severe anemia should be intensively treated.

Elevation of interleukin-6 in inflammatory bowel disease is macrophage- and epithelial cell-dependent

Local interleukin-6 (IL-6) activity was studied using colonic mucosal tissues in inflammatory bowel disease (IBD) and inflammatory control patients. Active IBD specimens exhibited significantly higher IL-6 activity than control specimens in both cultures of isolated lamina propria mononuclear cells (LPMC) and mucosal tissues with an increased number of IL-6-producing cells. However, the activity in inactive IBD or inflammatory controls did not differ from controls. Northern blot analysis demonstrated IL-6 messenger RNA in LPMC and colonic epithelial cells isolated from active IBD specimens but not in control cells. Furthermore, immunofluorescent microscopic study of active IBD specimens showed more conspicuous staining of IL-6 in infiltrating LPMC (mostly CD68+ cells) and colonic epithelial cells. These results suggest that elevation of local IL-6 activity may be a characteristic feature of active IBD and both macrophages and colonic epithelial cells are the major cell types responsible for this phenomenon.

Small-bowel obstruction: diagnostic comparison between double-balloon endoscopy and fluoroscopic enteroclysis, and the outcome of enteroscopic treatment.

BACKGROUND Small-bowel obstruction (SBO) sometimes remains undiagnosed and untreatable without surgery. OBJECTIVE To evaluate the diagnostic yields of SBO between double-balloon endoscopy (DBE) and fluoroscopic enteroclysis (FE), and the outcome of enteroscopic treatment. DESIGN Single-center, retrospective, and prospective study. SETTING Tertiary-referral hospital. PATIENTS Between June 2003 and July 2007, 66 consecutive patients with SBO were enrolled, investigated, and treated. MAIN OUTCOME MEASUREMENTS A comparison of diagnostic yields between DBE and FE, and the prognosis after enteroscopic balloon dilation. RESULTS The diagnostic yield of DBE for SBO (95%) was higher than that of FE (71%) in 59 patients who underwent both examinations (P= .004). The first treatment included 27 surgical, 25 enteroscopic, and 14 conservative therapies. Of 47 enteroscopic balloon dilation procedures in 22 patients, 45 (96%) were successful. Of 16 patients with Crohns disease, 11 (69%) remained asymptomatic over the postdilation follow-up period but 5 relapsed: 2 recovered by repeated dilations, but 3 required surgery. Of 6 patients who had diseases other than Crohns disease, 4 (67%) remained asymptomatic but 2 relapsed: one with remission of metastasis recovered by repeated dilations, and one with ischemic enteritis required surgery. Anastomotic stricture was an independent marker of the symptom-free outcome (hazard ratio 0.037-0.084, P= .037). Two acute pancreatitis, one perforation, and one exacerbation of SBO complications occurred. LIMITATIONS Small sample size and participation bias. CONCLUSIONS DBE was useful for the diagnosis of SBO. Balloon dilation is considered an alternative to surgery in patients with fibrotic strictures both related and unrelated to Crohns disease.

Restriction–modification system differences in Helicobacter pylori are a barrier to interstrain plasmid transfer

Helicobacter pylori cells are naturally competent for the uptake of both plasmid and chromosomal DNA. However, we demonstrate that there are strong barriers to transformation of H. pylori strains by plasmids derived from unrelated strains. We sought to determine the molecular mechanisms underlying these barriers. Transformation efficiency was assessed using pHP1, an Escherichia coli–H. pylori shuttle vector conferring kanamycin resistance. Transformation of 33 H. pylori strains was attempted with pHP1 purified from either E. coli or H. pylori, and was successfully introduced into only 11 strains. Digestion of H. pylori chromosomes with different restriction endonucleases (REs) showed that DNA methylation patterns vary substantially among strains. The strain most easily transformed, JP26, was found to have extremely low endogenous RE activity and to lack a restriction–modification (R–M) system, homologous to MboI, which is highly conserved among H. pylori strains. When we introduced this system to JP26, pHP1 from MboI.M+ JP26, but not from wild‐type JP26, transformed MboI R−M+ JP26 and heterologous MboI R−M+ wild‐type H. pylori strains. Parallel studies with pHP1 from dam+ and dam−E. coli strains confirmed these findings. These data indicate that the endogenous REs of H. pylori strains represent a critical barrier to interstrain plasmid transfer among H. pylori.

Efficacy of rebamipide for diclofenac-induced small-intestinal mucosal injuries in healthy subjects : a prospective, randomized, double-blinded, placebo-controlled, cross-over study

BackgroundAlthough obscure gastrointestinal bleeding cannot be detected by colonoscopy or upper endoscopy, wireless video capsule endoscopy (VCE) is capable of imaging it. Few data are available on medical therapy for patients with nonsteroidal anti-inflammatory drug (NSAID)-induced small-intestinal mucosal injuries. The aim of this study was to compare prevention by rebamipide and placebo of NSAID-induced smallintestinal injury in healthy subjects.MethodsTen healthy subjects who provided written informed consent were enrolled. Rebamipide or placebo plus diclofenac was administered with omeprazole for 7 days, and for an additional 7-day period with treatments reversed in the same subjects, with a 4-week washout period between treatments. VCE of the small intestine was performed four times, before and after each of the two study periods.ResultsThe number of subjects with small-intestinal mucosal injuries was higher in the placebo group (8/10) than in the rebamipide group (2/10) (P = 0.023). Two cases of ulcer and one of bleeding were observed in the placebo group, while no ulcer or bleeding was observed in the rebamipide group.ConclusionsRebamipide had significantly higher efficacy than placebo in preventing NSAID-induced small-intestinal mucosal injury.

Interleukin 15 activity in the rectal mucosa of inflammatory bowel disease

BACKGROUND & AIMS Interleukin (IL)-15 has been found to share many immunoregulatory activities in lymphocytes with IL-2. The aim of this study was to investigate IL-15 activity in organ cultures, localization of IL-15 messenger RNA (mRNA), and proliferation of lamina propria mononuclear cells (LPMCs) in response to recombinant IL-15 using the mucosal tissues obtained from patients with inflammatory bowel disease (IBD). METHODS The contents of IL-15, tumor necrosis factor alpha, and IL-2 in the culture supernatant of the rectal mucosal tissues were determined by an enzyme-linked immunosorbent assay. Expression of IL-15 mRNA was analyzed by in situ hybridization, and proliferative response of LPMCs to recombinant IL-15 was determined by [3H]thymidine incorporation into DNA. RESULTS Significantly greater IL-15 activity was detected in active IBD, and this elevation was also observed in inactive ulcerative colitis. In contrast, greater tumor necrosis factor alpha activity was observed only in active IBD, and IL-2 was not detected in organ cultures. In situ hybridization showed IL-15 mRNA in macrophages and epithelial cells in active IBD specimens, and recombinant IL-15 induced a dose-dependent proliferative response in LPMCs. CONCLUSIONS Mucosal IL-15 may be involved in the pathogenesis of IBD as one of the important mediators in activation of mucosal immune cells.

Ginger ingredients reduce viability of gastric cancer cells via distinct mechanisms

Ginger has been used throughout the world as spice, food and traditional herb. We found that 6-gingerol, a phenolic alkanone isolated from ginger, enhanced the TRAIL-induced viability reduction of gastric cancer cells while 6-gingerol alone affected viability only slightly. 6-Gingerol facilitated TRAIL-induced apoptosis by increasing TRAIL-induced caspase-3/7 activation. 6-Gingerol was shown to down-regulate the expression of cIAP1, which suppresses caspase-3/7 activity, by inhibiting TRAIL-induced NF-kappaB activation. As 6-shogaol has a chemical structure similar to 6-gingerol, we also assessed the effect of 6-shogaol on the viability of gastric cancer cells. Unlike 6-gingerol, 6-shogaol alone reduced the viability of gastric cancer cells. 6-Shogaol was shown to damage microtubules and induce mitotic arrest. These findings indicate for the first time that in gastric cancer cells, 6-gingerol enhances TRAIL-induced viability reduction by inhibiting TRAIL-induced NF-kappaB activation while 6-shogaol alone reduces viability by damaging microtubules.

Interleukin‐6 and soluble interleukin‐6 receptor in the colonic mucosa of inflammatory bowel disease

Background : Interleukin‐6 (IL‐6) has multiple immunological effects on a wide variety of cells and tissues. The expression of IL‐6 and IL‐6 receptor (IL‐6R) may be important to the pathogenesis of inflammatory bowel disease (IBD).

Plasticity of repetitive DNA sequences within a bacterial (type IV) secretion system component

DNA rearrangement permits bacteria to regulate gene content and expression. In Helicobacter pylori, cagY, which contains an extraordinary number of direct DNA repeats, encodes a surface-exposed subunit of a (type IV) bacterial secretory system. Examining potential DNA rearrangements involving the cagY repeats indicated that recombination events invariably yield in-frame open reading frames, producing alternatively expressed genes. In individual hosts, H. pylori cell populations include strains that produce CagY proteins that differ in size, due to the predicted in-frame deletions or duplications, and elicit minimal or no host antibody recognition. Using repetitive DNA, H. pylori rearrangements in a host-exposed subunit of a conserved bacterial secretion system may permit a novel form of antigenic evasion.