Long-term rebleeding rate and predictive factors of rebleeding after capsule endoscopy in patients with obscure GI bleeding.

BACKGROUND AND AIMS: The incidence of rebleeding in obscure GI bleeding (OGIB) remains unclear. This study used capsule endoscopy (CE) to determine the long-term rebleeding rate and predictive factors for rebleeding in patients with OGIB. METHODS: This single-center, observational study enrolled consecutive patients with OGIB who underwent CE as the first small intestinal examination between March 2004 and December 2015 and were followed up through medical records or letters. RESULTS: Three hundred eighty-nine patients were included in the analysis. Survival curve analysis showed that the overall cumulative rebleeding rate in OGIB during the 5 years was 41.7%. Multivariate analysis using the Cox proportional hazards model revealed that overt OGIB (hazard ratio [HR], 2.017; 95% confidence interval [CI], 1.299-3.131; P = .002), anticoagulants (HR, 1.930; 95% CI, 1.093-3.410; P = .023), positive balloon-assisted enteroscopy findings after CE (HR, 2.927; 95% CI, 1.791-4.783; P < .001), and iron supplements without therapeutic intervention (HR, 2.202; 95% CI, 1.386-3.498; P = .001) were associated with rebleeding, whereas a higher minimum hemoglobin level (HR, .902; 95% CI, .834-.975; P = .009) and therapeutic intervention (HR, .288; 95% CI, .145-.570; P < .001) significantly reduced the risk of rebleeding. Among the Charlson Comorbidity Index components, liver cirrhosis was an independent predictor associated with rebleeding in patients with OGIB (HR, 4.362; 95% CI, 2.622-7.259; P < .001) and in patients with negative CE findings (HR, 8.961; 95% CI, 4.424-18.150; P < .001). CONCLUSIONS: Rebleeding is common during the long-term follow-up of patients with OGIB. Careful follow-up is required for patients with liver cirrhosis or previous massive bleeding.

Rebamipide ameliorates indomethacin-induced small intestinal damage and proton pump inhibitor-induced exacerbation of this damage by modulation of small intestinal microbiota.

Non-steroidal anti-inflammatory drugs (NSAIDs) induce small intestinal damage. It has been reported that rebamipide, a mucoprotective drug, exerts a protective effect against NSAID-induced small intestinal damage; however, the underlying mechanism remains unknown. In this study, we investigated the significance of the small intestinal microbiota in the protective effect of rebamipide against indomethacin-induced small intestinal damage in mice. A comprehensive analysis of the 16S rRNA gene sequencing revealed an alteration in the composition of the small intestinal microbiota at the species level, modulated by the administration of rebamipide and omeprazole. The transplantation of the small intestinal microbiota of the mice treated with rebamipide suppressed the indomethacin-induced small intestinal damage. Omeprazole, a proton pump inhibitor, exacerbated the indomethacin-induced small intestinal damage, which was accompanied by the alteration of the small intestinal microbiota. We found that the transplantation of the small intestinal microbiota of the rebamipide-treated mice ameliorated indomethacin-induced small intestinal damage and the omeprazole-induced exacerbation of the damage. These results suggest that rebamipide exerts a protective effect against NSAID-induced small intestinal damage via the modulation of the small intestinal microbiota, and that its ameliorating effect extends also to the exacerbation of NSAID-induced small intestinal damage by proton pump inhibitors.

High-fat diet-mediated dysbiosis exacerbates NSAID-induced small intestinal damage through the induction of interleukin-17A.

Non-steroidal anti-inflammatory drugs (NSAIDs) cause damage in the small intestine in a bacteria-dependent manner. As high-fat diet (HFD) is a potent inducer of gut dysbiosis, we investigated the effects of HFD on bacterial flora in the small intestine and NSAID-induced enteropathy. 16S rRNA gene analysis revealed that the population of Bifidobacterium spp. significantly decreased by fold change of individual operational taxonomic units in the small intestine of mice fed HFD for 8 weeks. HFD increased intestinal permeability, as indicated by fluorescein isothiocyanate-dextran absorption and serum lipopolysaccharide levels, accompanied by a decrease in the protein expressions of ZO-1 and occludin and elevated mRNA expression of interleukin (IL)-17A in the small intestine. HFD-fed mice exhibited increased susceptibility to indomethacin-induced damage in the small intestine; this phenotype was observed in normal diet-fed mice that received small intestinal microbiota from HFD-fed mice. Administration of neutralizing antibodies against IL-17A to HFD-fed mice reduced intestinal permeability and prevented exacerbation of indomethacin-induced damage. Thus, HFD-induced microbial dysbiosis in small intestine caused microinflammation through the induction of IL-17A and increase in intestinal permeability, resulting in the aggravation of NSAID-induced small intestinal damage.

Involvement of gliadin, a component of wheat gluten, in increased intestinal permeability leading to non-steroidal anti-inflammatory drug-induced small-intestinal damage.

Gliadin, a component of wheat gluten known to be an important factor in the etiology of celiac disease, is related to several other diseases through its enhancing effect on intestinal paracellular permeability. We investigated the significance of gliadin in non-steroidal anti-inflammatory drug (NSAID)-induced small-intestinal damage in mice. 7-week-old C57BL/6 male mice were divided into the following groups: standard diet group, in which mice were fed with wheat-containing standard rodent diet (CE-2); gluten-free diet group, in which mice were fed with gluten-free diet (AIN-76A); and gliadin-administered group, in which mice fed with gluten-free diet were administered with gliadin (~250 mg/kg BW). Each group was subdivided into negative, healthy control group and NSAID-treated group. To some mice fed with gluten-free diet and administered with gliadin, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor was administered for clarification of the significance of EGFR in NSAID-induced small intestinal damage and intestinal permeability. In mice fed with a gluten-free diet, indomethacin or diclofenac induced very mild mucosal damage in the small intestine compared with that in mice fed with a wheat-containing standard diet. Gliadin exacerbated the NSAID-induced small-intestinal damage in mice fed with a gluten-free diet. With the administration of indomethacin, MPO activity, a marker of neutrophil infiltration into the mucosa and mRNA expression level of tumor necrosis factor α and interleukin-1ß in the small intestine were higher in the gliadin-administered mice. Gliadin increased the intestinal paracellular permeability without indomethacin administration (4.3-fold) and further increased the permeability after indomethacin administration (2.1-fold). Gliadin induced phosphorylation of epidermal growth factor receptor (EGFR) in small-intestinal tissues, and erlotinib (an EGFR tyrosine kinase inhibitor) attenuated the indomethacin-induced intestinal damage and permeability exacerbated by gliadin, accompanied by inhibition of EGFR phosphorylation. These results suggest that gliadin plays an important role in the induction and exacerbation of NSAID-induced small-intestinal damage, and that increase in intestinal permeability via the EGFR signalling pathway is involved in its mechanism.

Does discontinuation of antithrombotics affect the diagnostic yield of small bowel capsule endoscopy in patients demonstrating obscure gastrointestinal bleeding?

A large proportion of patients demonstrating obscure gastrointestinal bleeding (OGIB) are antithrombotic users and need to undergo small bowel capsule endoscopy (SBCE). We examined the effect of discontinuation of antithrombotics on the diagnostic yield of SBCE. Additionally, we assessed predictive factors associated with positive SBCE findings. Our study included 130 patients using antithrombotics who underwent SBCE for overt OGIB. The primary endpoint was the difference in the rate of positive SBCE findings between patients who continued and those who discontinued antithrombotics. Secondary endpoints were to investigate the effect of discontinuation of antithrombotics using a propensity score analysis, and to assess predictive factors associated with a positive SBCE. Among the 73 patients who continued use of antithrombotics, 36 (49.3%) patients demonstrated positive findings, while among the 57 patients who discontinued antithrombotics, 35 (61.4%) patients showed positive findings. Rates of positive SBCE findings didn't differ between the two groups. After we performed propensity score matching, discontinuation didn't affect the rate of positive SBCE findings. The lowest hemoglobin level was the only independent predictive factor associated with positive SBCE findings. In conclusion, discontinuation of antithrombotic therapy didn't affect the diagnostic yield of SBCE in patients presenting with overt OGIB.

Microbiome and intestinal ischemia/reperfusion injury.

Intestinal ischemia/reperfusion injury is a severe disease associated with a high mortality. The mechanisms that cause ischemia/reperfusion injury are complex and many factors are involved in the injury formation process; however, the only available treatment is surgical intervention. Recent studies demonstrated that the intestinal microbiome plays a key role in intestinal ischemia/reperfusion injury and there are many factors associated with intestinal bacteria during the formation of the intestinal ischemia/reperfusion injury. Among the Toll-like receptors (TLR), TLR2, TLR4, and their adaptor protein, myeloid differentiation primary-response 88 (MyD88), have been reported to be involved in intestinal ischemia/reperfusion injury. Oxidative stress and nitric oxide are also associated with intestinal bacteria during the formation of the intestinal ischemia/reperfusion injury. This review focuses on our current understanding of the impact of the microbiome, including the roles of the TLRs, oxidative stress, and nitric oxide, on intestinal ischemia/reperfusion injury.

Usefulness of small bowel reexamination in obscure gastrointestinal bleeding patients with negative capsule endoscopy findings: Comparison of repeat capsule endoscopy and double-balloon enteroscopy.

BACKGROUND: Although capsule endoscopy (CE) is a noninvasive diagnostic tool for patients with obscure gastrointestinal bleeding (OGIB), bleeding lesions are often not detected. No strategies have been established to determine whether CE or double-balloon enteroscopy (DBE) should be performed after negative CE. METHODS: Among 652 patients who underwent CE for OGIB, a total of 359 patients had negative findings. Of these, 41 and 48 patients underwent repeat CE and DBE for small bowel reexamination, respectively. We compared the rate of positive findings between the two groups. The findings were considered positive if mucosal break, vascular lesion, tumor, or active bleeding was observed. RESULTS: The rate of positive findings in the repeat CE group was significantly higher than that in the DBE group (73.2% vs. 39.6%; p = 0.001). Logistic regression analysis showed that the repeat CE group was significantly associated with positive findings (odds ratio (OR), 4.2; 95% confidence interval (CI), 1.7-10.2; p = 0.002). Inverse probability of treatment-weighted analysis revealed that repeat CE was significantly associated with positive findings (OR, 4.4; 95% CI, 1.6-12.2; p = 0.004). CONCLUSIONS: Reexamination via CE appears to have more diagnostic value than DBE for OGIB patients with negative CE findings.

Clinical Utility of Capsule Endoscopy and Double-Balloon Enteroscopy in the Management of Obscure Gastrointestinal Bleeding.

BACKGROUND: Obscure gastrointestinal bleeding (OGIB) is a common but embarrassing problem for gastroenterologists. Most bleeding lesions associated with OGIB are present in the small intestine and sometimes cannot be identified due to the difficulty associated with physical accessibility. Capsule endoscopy (CE) and double-balloon enteroscopy (DBE) have enabled in the process of diagnosing and have evolved to become approaches to treating OGIB. SUMMARY: CE is a minimally invasive procedure and has a high diagnostic yield in patients with OGIB. DBE offers additional advantage of biopsy collection for pathological diagnosis and therapeutic intervention, but it should be noted that it sometimes causes severe adverse events such as acute pancreatitis, intestinal bleeding, and intestinal perforation. CE should be performed early in the workup course of OGIB. Positive CE findings enhance the diagnostic yield of subsequent DBE, and the effective therapeutic intervention improves the clinical outcomes of OGIB patients. On the contrary, there are no clear guidelines for further investigation of patients with negative CE findings at the present. Although patients in stable general condition may only require follow-up, repeated CE is useful to detect positive findings in patients with evidence of sustained bleeding and progressing anemia. We have revealed that repeated CE has higher positive finding rate than DBE in OGIB patients with negative CE findings in a preliminary study. Key Messages: CE and DBE have complementary roles in the management of OGIB, and the precise timing and proper sequence may be important for the approach to treating OGIB.

Isoliquiritigenin Ameliorates Indomethacin-Induced Small Intestinal Damage by Inhibiting NOD-Like Receptor Family, Pyrin Domain-Containing 3 Inflammasome Activation.

Activation of the NOD-Like Receptor Family, Pyrin Domain-Containing 3 (NLRP3) inflammasome, which consists of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and pro-caspase-1, triggers pro-caspase-1 cleavage promoting the processing of pro-interleukin (IL)-1ß into mature IL-1ß, which is critical for the development of non-steroidal anti-inflammatory drug (NSAID)-induced enteropathy. We investigated the effects of isoliquiritigenin, a flavonoid derived from the roots of Glycyrrhiza species, on NSAID-induced small intestinal damage and the inflammasome activation. To induce enteropathy, mice were administered indomethacin by gavage with or without isoliquiritigenin pretreatment. Some mice received an intraperitoneal injection of recombinant murine IL-1ß in addition to isoliquiritigenin and indomethacin. Indomethacin induced small intestinal damage and increased protein levels of cleaved caspase-1 and mature IL-1ß in the small intestine. Treatment with 7.5 and 75 mg/kg isoliquiritigenin inhibited indomethacin-induced small intestinal damage by 40 and 56%, respectively. Isoliquiritigenin also inhibited the indomethacin-induced increase in cleaved caspase-1 and mature IL-1ß protein levels, whereas it did not affect the mRNA expression of NLRP3, ASC, caspase-1, and IL-1ß. Protection against intestinal damage in isoliquiritigenin-treated mice was completely abolished with exogenous IL-1ß. NLRP3-/- and caspase-1-/- mice exhibited resistance to intestinal damage, and isoliquiritigenin treatment failed to inhibit the damage in NLRP3-/- and caspase-1-/- mice. Isoliquiritigenin prevents NSAID-induced small intestinal damage by inhibiting NLRP3 inflammasome activation.

Clinical factors associated with positive capsule endoscopy findings in patients with obscure gastrointestinal bleeding: a single-center study.

BACKGROUND: Capsule endoscopy (CE) is a useful tool for patients with obscure gastrointestinal bleeding (OGIB), but positive finding rate differs among trials, which may be attributable to the difference in patients' background. OBJECTIVES: To evaluate the predictive factors associated with positive findings on CE. METHODS: Consecutive patients with OGIB who underwent CE between March 2004 and May 2015 at a single university hospital were enrolled. Patients' clinical factors and CE data were reviewed retrospectively, and we evaluated the relationship between clinical factors and positive findings by univariate and multivariate logistic regression analyses. RESULTS: Five hundred and seventy-eight patients were included in the analysis. Positive CE findings were obtained in 284 patients (49.1%). In multivariate analysis, low hemoglobin level (odds ratio (OR), 1.142 per 1 g/dL decrease; p < .001), Charlson comorbidity index (CCI) score (OR, 1.170 per 1 point increase; p = .002), and non-steroidal anti-inflammatory drug (NSAID) use (OR, 1.640; p = .044) were associated with an increased prevalence of positive findings. As for components of CCI, malignant tumor (OR, 1.839; p = .017) was associated with the positive findings. CONCLUSIONS: OGIB patient with a low-hemoglobin level, complex and severe comorbidities, and NSAID use should receive CE.

Microbiota Plays a Key Role in Non-Steroidal Anti-Inflammatory Drug-Induced Small Intestinal Damage.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) damage the small intestine by causing multiple erosions and ulcers. However, to date, no established therapies and prophylactic agents are available to treat such damages. We reviewed the role of intestinal microbiota in NSAID-induced intestinal damage and identified potential therapeutic candidates. SUMMARY: The composition of the intestinal microbiota is an important factor in the pathophysiology of NSAID-induced small intestinal damage. Once mucosal barrier function is disrupted due to NSAID-induced prostaglandin deficiency and mitochondrial malfunction, lipopolysaccharide from luminal gram-negative bacteria and high mobility group box 1 from the injured epithelial cells activate toll-like receptor 4-signaling pathway and nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 inflammasome; this leads to the release of proinflammatory cytokines such as tumor necrosis factor-α and interleukin-1ß. Proton pump inhibitors (PPIs) are often used for the prevention of NSAID-induced injuries to the upper gastrointestinal tract. However, several studies indicate that PPIs may induce dysbiosis, which may exacerbate the NSAID-induced small intestinal damage. Our recent research suggests that probiotics and rebamipide could be used to prevent NSAID-induced small intestinal damage by regulating the intestinal microbiota. Key Messages: Intestinal microbiota plays a key role in NSAID-induced small intestinal damage, and modulating the composition of the intestinal microbiota could be a new therapeutic strategy for treating this damage.

NLRP3 inflammasome has a protective effect against oxazolone-induced colitis: a possible role in ulcerative colitis.

The inflammasomes induce maturation of pro-interleukin-1ß (IL-1ß) and pro-IL-18. We investigated roles of the NLRP3 inflammasome in the pathogenesis of ulcerative colitis (UC). After induction of oxazolone-induced colitis, a mouse UC model, colonic tissues were assayed for inflammatory mediators. Histological studies were performed on inflamed colonic tissue from mice and UC patients. Histological severity of murine colitis peaked on day 1, accompanied by an increase in the expression of Th2 cytokines including IL-4 and IL-13. Oxazolone treatment stimulated maturation of pro-caspase-1 and pro-IL-1ß, while it reduced IL-18 expression. Either exogenous IL-1ß or IL-18 ameliorated the colitis with or without reduction in Th2 cytokine expression, respectively. Induction of colitis decreased MUC2 expression, which was reversed by administration of IL-18, but not IL-1ß. Compared to wild-type mice, NLRP3-/- mice exhibited higher sensitivity to oxazolone treatment with enhancement of Th2 cytokine expression and reduction of mature IL-1ß and IL-18 production; this phenotype was rescued by exogenous IL-1ß or IL-18. Immunofluorescent studies revealed positive correlation of NLRP3 expression with disease severity in UC patients, and localization of the inflammasome-associated molecules in macrophages. The NLRP3 inflammasome-derived IL-1ß and IL-18 may play a protective role against UC through different mechanisms.

Double-balloon endoscopy WAS effective in diagnosing small intestinal duplication: a case report.

INTRODUCTION: Ileal duplications are encountered infrequently in adults, because symptoms including abdominal pain, intussusception, hemorrhage, and perforation usually present in early childhood. In this report, we present an adult case of ileal duplication that was revealed by double-balloon endoscopy (DBE). CASE DESCRIPTION: A 73-year-old Japanese man presented with anemia and melena. Anal DBE detected the narrow opening of an extra lumen in the ileum about 100 cm proximal to the ileocecal valve. Enteroclysis via DBE showed a 5-cm-long ileal diverticulum-like structure at the mesenteric side of the ileum. No ectopic gastric mucosa was detected by technetium-99m pertechnetate scintigraphy. The final diagnosis was ileal duplication. DISCUSSION AND EVALUATION: This is the first report of tubular ileal duplication diagnosed by using DBE. The small intestinal duplication opening was not detected by using VCE and plane CT in this case, but was found by using DBE. CONCLUSIONS: The present case demonstrates that DBE was useful in the diagnosis of an adult small intestinal duplication that was not visualized by other modalities.

Colchicine prevents NSAID-induced small intestinal injury by inhibiting activation of the NLRP3 inflammasome.

The inflammasome is a large, multiprotein complex that consists of a nucleotide-binding oligomerization domain-like receptor (NLR), an apoptosis-associated speck-like protein containing a caspase recruitment domain, and pro-caspase-1. Activation of the inflammasome results in cleavage of pro-caspase-1 into cleaved caspase-1, which promotes the processing of pro-interleukin (IL)-1ß into mature IL-1ß. We investigated the effects of colchicine on non-steroidal anti-inflammatory drug (NSAID)-induced small intestinal injury and activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome. Colchicine treatment inhibited indomethacin-induced small intestinal injury by 86% (1 mg/kg) and 94% (3 mg/kg) as indicated by the lesion index 24 h after indomethacin administration. Colchicine inhibited the protein expression of cleaved caspase-1 and mature IL-1ß, without affecting the mRNA expression of NLRP3 and IL-1ß. Although treatment with recombinant IL-1ß (0.1 µg/kg) did not change the severity of small intestinal damage, the preventive effects of colchicine were abolished by supplementation with the same dose of recombinant IL-1ß. Indomethacin-induced small intestinal damage was reduced by 77%, as determined by the lesion index in NLRP3(-/-) mice, and colchicine treatment failed to inhibit small intestinal damage in NLRP3(-/-) mice. These results demonstrate that colchicine prevents NSAID-induced small intestinal injury by inhibiting activation of the NLRP3 inflammasome.