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INTRODUCTION: Aquaporin (AQP) channels are involved in regulating fluid homeostasis in the colon. Several AQP channels were detected in human colon epithelial cells. In a previous study, rats fed 1% (wt/wt) sodium cholate had increased AQP3, 7, and 8 levels, suggesting AQP involvement in bile acid diarrhea (BAD). Our aim was to compare AQP expressions in rectosigmoid mucosal (RSM) biopsies from patients with irritable bowel syndrome–diarrhea (IBS-D) (divided into those with normal or high fecal BA excretion) and in patients with IBS-constipation (IBS-C) compared with healthy controls. METHODS: In RSM biopsies from 44 patients with IBS-D (with normal (<) or high (>2,337 μmol/48 hours (BAD)) fecal BA excretion), 10 patients with IBS-C, and 17 healthy controls, we measured expressions of AQP1, 3, 7, and 8, with RT-PCR (housekeeper gene GAPDH ). We analyzed RNA for expression by RT 2 -PCR assays, with expression calculated using 2 −ΔΔCT -based fold-change. Comparisons of IBS groups were corrected for false detection rate (Bonferroni correction for 12 comparisons; P < 0.0042). AQP protein measurements on biopsies from 3 healthy controls, 3 patients with IBS-D, and 3 patients with BAD were performed by western blots (GAPDH housekeeping protein). RESULTS: In RSM from patients with IBS-D (but not IBS-C), mRNA expression of AQP3 was decreased, and AQP7 and 8 were increased relative to controls. Fold differences were not different in IBS-D with or without BAD. Western blots confirmed increased expression of AQP7 and 8 and decreased AQP3 proteins in biopsies from patients with IBS-D compared with controls. CONCLUSIONS: Increased AQP7 and 8 and decreased AQP3 expressions in RSM suggest that further studies on AQPs' potential role in the pathophysiology of diarrhea in IBS-D are warranted.

Linked ContentThis article is linked to Rotondo et al and Masuy papers. To view these articles, visit https://doi.org/10.1111/apt.15195 and https://doi.org/10.1111/apt.15242.

Objective Over half of patients with IBS have either diarrhoea (IBS-D) or a mixed stool pattern (IBS-M). The relative efficacy of licenced pharmacological therapies is unclear in the absence of head-to-head trials. We conducted a network meta-analysis to resolve this uncertainty. Design We searched MEDLINE, Embase, Embase Classic, the Cochrane central register of controlled trials, and Clinicaltrials.gov through January 2019 to identify randomised controlled trials (RCTs) assessing the efficacy of licenced pharmacological therapies (alosetron, eluxadoline, ramosetron and rifaximin) in adults with IBS-D or IBS-M. Trials included in the analysis reported a dichotomous assessment of overall response to therapy, and data were pooled using a random effects model. Efficacy and safety of all pharmacological therapies were reported as a pooled relative risk with 95% CIs to summarise the effect of each comparison tested. Treatments were ranked according to their p score. Results We identified 18 eligible RCTs (seven alosetron, five ramosetron, two rifaximin and four eluxadoline), containing 9844 patients. All were superior to placebo for the treatment of IBS-D or IBS-M at 12 weeks, according to the Food and Drug Administration (FDA)-recommended endpoint for trials in IBS. Alosetron 1 mg twice daily was ranked first for efficacy, based on the FDA-recommended composite endpoint of improvement in both abdominal pain and stool consistency, effect on global symptoms of IBS and effect on stool consistency. Ramosetron 2.5µg once daily was ranked first for effect on abdominal pain. Total numbers of adverse events were significantly greater with alosetron 1 mg twice daily and ramosetron 2.5µg once daily, compared with placebo. Rifaximin 550 mg three times daily ranked first for safety. Constipation was significantly more common with all drugs, except rifaximin 550 mg three times daily. Conclusion In a network meta-analysis of RCTs of pharmacological therapies for IBS-D and IBS-M, we found all drugs to be superior to placebo, but alosetron and ramosetron appeared to be the most effective.

AbstractObjectiveTo compare estimates of gastric accommodation (GA) with single photon emission computed tomography (SPECT) to measurements based on intragastric meal distribution immediately post‐meal ingestion (IMD0).MethodsWe evaluated 108 diabetics with upper gastrointestinal (UGI) symptoms who had undergone gastric emptying of solids (GE) by scintigraphy and GA measurements by SPECT. Immediately after ingestion of a 99mTc‐labeled egg meal (time 0), we estimated IMD0 as radioactive counts or area of the proximal half of the stomach on two‐dimensional images. Gastric volume (GV) during fasting and after 300 mL Ensure® was measured by SPECT to quantify accommodation volume (AV) or postprandial to fasting volume ratio (GVR). From the measured proximal gastric area, we estimated the volume of proximal stomach (4/3 × π × r3). We performed regression analyses to assess relationships between IMD0 and GA (AV) and GVR.ResultsThere was a significant correlation between area and radioactivity counts in the proximal stomach (r = 0.67, P < 0.001); however, there was considerable interpersonal variation [bias 0.20 (95% CI −0.07, 0.47)]. There were no significant correlations between total GV or AV or VR by SPECT and measurements using IMD0: proximal gastric counts, area, and estimated volume as continuous variables of dichotomized patient groups, based on published cutoff values. There were no significant differences in total gastric area or the IMD0 parameters (% area or % radioactive counts) between those with and without UGI symptoms except for fullness and satiety.ConclusionsIntragastric meal distribution immediately post‐meal ingestion is not significantly correlated with GA measurement by SPECT.

AbstractBackgroundIn two phase 3 trials, elobixibat, a locally acting ileal bile acid transporter inhibitor, resolved constipation and was well tolerated in Japanese patients with chronic constipation. We analyzed the efficacy, safety, and impact on quality of life (QOL) of elobixibat in patients with symptomatically more severe constipation in the two phase 3 trials.MethodsThis post hoc analysis of elobixibat treatment outcomes included data from a 2‐week, randomized, placebo‐controlled, phase 3 trial (10 mg/d), and a 52‐week, open‐label trial (5‐15 mg/d) in subgroups with severe constipation defined as ≤2 spontaneous bowel movements (SBMs) and ≤3 Bristol Stool Form Scale score during the second week of the 2‐week run‐in period. We also analyzed the rates of abdominal pain, diarrhea, and QOL in subgroups according to sex, presence of constipation‐predominant irritable bowel syndrome (IBS‐C) and side effects.Key ResultsIn patients with severe constipation, there was significant improvement in the 10 mg elobixibat group compared to the placebo group in change in SBMs from baseline at week 1 (primary endpoint) of the 2‐week trial. The differences between groups were reduced in patients with more severe constipation. Increasing the dose to 15 mg was effective for more severe constipation in improving the number of SBMs per week in the 52‐week trial. Overall, elobixibat was well tolerated and improved QOL scores, irrespective of gender, presence of IBS‐C or side effects.Conclusions & InferencesElobixibat is effective for symptomatically severe constipation, is well tolerated and improves QOL, irrespective of potentially confounding patient characteristics.

SummaryBackgroundBiomarkers in irritable bowel syndrome (IBS) may guide targeted therapy in this multifactorial disease. It has been suggested that 75% accuracy and cost <$500 categorise biomarkers as cost‐effective.AimTo identify differences in faecal bile acids, faecal fat and fasting serum C4 (7a‐hydroxy‐4‐cholesten‐3‐one) and fibroblast growth factor 19 (FGF19) among patients with IBS‐D, IBS‐C and healthy controls and to determine accurate, cost‐effective biomarkers for clinically relevant diarrhoea and constipation.MethodsWe assessed daily stool frequency and consistency (Bristol Stool Form Scale) from validated bowel diaries, 48 hours total and individual faecal bile acids, 48 hours faecal fat and weight, fasting serum C4 and FGF19, and colonic transit by scintigraphy from healthy volunteers (HV) and patients with IBS‐D and IBS‐C (Rome III criteria). We utilised multivariate logistic regression to determine biomarkers of clinically significant diarrhoea or constipation based on stool frequency, consistency and weight.ResultsAmong the 126 HV (44M/82F, 37.5 ± 10.9 years [SD]), 64 IBS‐D (5M/59F, 41.9 ± 12.2 years), and 30 IBS‐C (0M/30F, 44.6 ± 10 years) patients, there were significant differences between all groups in stool weight, frequency, and consistency; in addition, there were differences in colonic transit at 48 hours, faecal fat, and total and individual faecal bile acids between IBS‐D and IBS‐C. Reduced total and primary faecal bile acids and increased faecal lithocholic acid were significant predictors of decreased faecal weight, frequency and consistency with AUC > 0.82 (sensitivity >76%, specificity >72%). Total and primary faecal bile acids and faecal fat were significant predictors of increased stool weight, frequency and consistency with AUC > 0.71 (sensitivity >55%, specificity >74%).The faecal parameters had a 11.5 positive likelihood ratio in predicting elevated faecal weight.ConclusionsFaecal bile acids and faecal fat are cost‐effective and accurate biomarkers associated with significant bowel dysfunction among IBS‐D and IBS‐C patients.

AbstractBackgroundThe purpose of this study was to evaluate the measurement properties of the American Neurogastroenterology and Motility Society Gastroparesis Cardinal Symptom Index‐Daily Diary, a patient‐reported outcome instrument developed to meet US FDA recommendations for a symptom‐based clinical trial endpoint in gastroparesis. The ANMS GCSI‐DD assesses nausea, early satiety, postprandial fullness, and upper abdominal pain on a severity score from none (0) to very severe (4) and number of vomiting episodes during the past 24 hours. The composite score includes the first four symptoms, the core symptom score includes all five symptoms.MethodsSeventy‐one patients diagnosed with idiopathic or diabetic gastroparesis were recruited for a four‐week observational study. Patients completed the ANMS GCSI‐DD at home between Baseline and Week 4. Statistical analyses included confirmatory factor analysis, item response theory analysis, internal consistency, test‐retest reliability, and construct and known‐groups validity.Key ResultsUnidimensionality for the composite and core symptom scores was supported, and items exhibited good fit. Internal consistency (Cronbach's alpha =0.85 and 0.83) and test‐retest reliability were 0.89 and 0.88, for composite and core symptom scores, respectively. Convergent validity was supported by strong correlations with patient‐reported and clinician measures. Baseline and Week 4 scores differed for three measures used to define disease severity status (P < 0.0001), supporting known‐groups validity.Conclusions & InferencesThe ANMS GCSI‐DD has excellent reliability and validity, supporting its use to assess symptom‐based endpoints in gastroparesis clinical studies. Further analyses will be conducted using clinical trial data to ascertain treatment responsiveness and define a responder.

AbstractObjectiveWe identified a pedigree over five generations with 49 members, some of whom had chronic megacolon presenting in adolescence or adulthood. We aimed to assess the genetic cause of chronic megacolon through clinical and DNA studies.DesignAfter ethical approval and informed consent, family members provided answers to standard bowel disease questionnaires, radiological or surgical records, and DNA (buccal mucosal scraping). Exome DNA sequencing of colon tissue or blood DNA from seven family members with colon or duodenal dilatation, or no megacolon (n = 1) was carried out. Sanger sequencing was performed in 22 additional family members to further evaluate candidate variants. The study focused on genes of potential relevance to enteric nerve (ENS) maturation and Hirschsprung's disease or megacolon, based on the literature (GFRA1, NKX2‐1, KIF26A, TPM3, ACTG2, SCN10A, and C17orf107 [CHRNE]) and other genetic variants that co‐segregated with megacolon in the six affected family members.ResultsInformation was available in all except five members alive at time of study; among 30 members who provided DNA, six had definite megacolon, one megaduodenum, seven significant constipation without bowel dilatation, and 16 normal bowel function by questionnaire. Among genes studied, SEMA3F (g.3:50225360A>G; c1873A>G) was found in 6/6 family members with megacolon. The SEMA3F gene variant was assessed as potentially pathogenic, based on M‐CAP in silico prediction. SEMA3F function is associated with genes (KIT and PDGFRB) that impact intestinal pacemaker function.ConclusionFamilial chronic megacolon appears to be associated with SEMA3F, which is associated with genes impacting enteric nerve or pacemaker function.

AbstractBackgroundBalloon expulsion test (BET) and high‐resolution anorectal manometry (HRM) are used in diagnosis of rectal evacuation disorders (REDs); their performance characteristics are suboptimal.MethodsWe audited records of 449 consecutive patients with chronic constipation (CC). We documented anal sphincter tone and contraction, puborectalis tenderness, and perineal descent on digital rectal exam (DRE); maximum resting and squeeze pressures, and rectoanal pressure gradient on HRM; weight or time to balloon expulsion; colonic transit, and area of rectal area on radiograph (RASF). We based the diagnosis of RED on ≥2 abnormalities on both DRE and HRM, excluding results of BET, as the performance of BET is being investigated. Results of RED vs non‐RED and results obtained using tbBET vs wbBET groups were compared. We used multivariate logistic regressions to identify predictors of RED using different diagnostic modalities.Key ResultsAmong 449 individuals, 276 were included (74 RED and 202 non‐RED). Predominant exclusions were for no HRM (n = 79) or use of low resolution anorectal manometry (n = 77). Logistic regression models for abnormal tbBET showed time >60 seconds, RASF and age‐predicted RED. For tbBET, the current cutoff of 60 seconds had sensitivity of 39.0% and specificity 93.0% to diagnose RED; on the other hand, applying the cutoff at 22 seconds, the sensitivity was 77.8% and specificity 69.8%.Conclusions & InferencesThe clinical diagnosis of RED in patients with CC is achieved with combination of DRE, HRM and an optimized, time‐based BET. Prospective studies are necessary to confirm the proposed 22 second cutoff for tbBET.