Acosta, Andrés

Prior studies in with irritable bowel syndrome with diarrhea (IBS-D) patients showed immune activation, secretion, and barrier dysfunction in jejunal or colorectal mucosa. We measured mRNA expression by RT-PCR of 91 genes reflecting tight junction proteins, chemokines, innate immunity, ion channels, transmitters, housekeeping genes, and controls for DNA contamination and PCR efficiency in small intestinal mucosa from 15 IBS-D and 7 controls (biopsies negative for celiac disease). Fold change was calculated using 2(−ΔΔCT) formula. Nominal P values ( P < 0.05) were interpreted with false detection rate (FDR) correction ( q value). Cluster analysis with Lens for Enrichment and Network Studies (LENS) explored connectivity of mechanisms. Upregulated genes (uncorrected P < 0.05) were related to ion transport (INADL, MAGI1, and SONS1), barrier (TJP1, 2, and 3 and CLDN) or immune functions (TLR3, IL15, and MAPKAPK5), or histamine metabolism (HNMT); downregulated genes were related to immune function (IL-1β, TGF-β1, and CCL20) or antigen detection (TLR1 and 8). The following genes were significantly upregulated ( q < 0.05) in IBS-D: INADL, MAGI1, PPP2R5C, MAPKAPK5, TLR3, and IL-15. Among the 14 nominally upregulated genes, there was clustering of barrier and PDZ domains (TJP1, TJP2, TJP3, CLDN4, INADL, and MAGI1) and clustering of downregulated genes (CCL20, TLR1, IL1B, and TLR8). Protein expression of PPP2R5C in nuclear lysates was greater in patients with IBS-D and controls. There was increase in INADL protein (median 9.4 ng/ml) in patients with IBS-D relative to controls (median 5.8 ng/ml, P > 0.05). In conclusion, altered transcriptome (and to lesser extent protein) expression of ion transport, barrier, immune, and mast cell mechanisms in small bowel may reflect different alterations in function and deserves further study in IBS-D.

AbstractBackgroundSynthetic human ghrelin accelerates gastric emptying, reduces gastric accommodation, and results in numerical increases in postprandial symptom scores. The ghrelin receptor agonist, relamorelin, accelerates gastric emptying in patients with diabetic gastroparesis.AimTo measure pharmacological effects of relamorelin on gastric accommodation, distal antral motility, and satiation in healthy volunteers.MethodsIn a placebo‐controlled, double‐blind, randomized study of 16 healthy volunteers, we compared effects of 30 μg subcutaneous (s.c.) relamorelin to placebo on: (i) gastric volumes measured by single photon emission computed tomography, (ii) 1‐h postprandial distal antral motility index (MI) by 15‐lumen perfusion gastroduodenal manometry, and (iii) satiation tested by Ensure nutrient drink test. Primary endpoints were: fasting and postprandial gastric volumes, distal antral phasic pressure activity (number of contractions, mean amplitude, and MI), and maximum tolerated volume. Results were normally distributed and the two treatment groups were compared using t‐test.Key ResultsRelamorelin, 30 μg s.c., significantly increased the number of contractions in the distal antrum during 0–60 min postmeal when compared to placebo (p = 0.022); this was also observed in the first two 15‐min periods (p = 0.005 and 0.015 for number of contractions 0–15 and 16–30). There was borderline increase in MI0‐15 (p = 0.055) and numerically increased MI0‐60 (p = 0.139) and MI16‐30 (p = 0.116). The amplitude of contractions was not significantly increased. Relamorelin did not significantly alter fasting or postprandial gastric volumes, gastric accommodation, or satiation volumes and symptoms.Conclusions & InferencesRelamorelin increases frequency of distal antral motility contractions without significant effects on amplitude of contractions. The lack of inhibition of accommodation and absence of increase in satiation symptoms support relamorelin for the treatment of symptomatic gastroparesis (ClinicalTrials.gov NCT02466711).

AbstractBackgroundNeostigmine, an acetyl cholinesterase inhibitor, stimulates colonic motor activity and may induce vagally mediated cardiovascular effects. Our aim was to evaluate effects of i.v. neostigmine on colonic compliance and its safety in patients with chronic constipation.MethodsWe retrospectively reviewed medical records of a selected group of 144 outpatients with chronic constipation who were refractory to treatment. These patients had undergone intracolonic motility and compliance measurements with an infinitely compliant balloon linked to a barostat. Data abstracted included barostat balloon mean volumes with increases in pressure (4 mmHg steps from 0 to 44 mmHg) before and after i.v. neostigmine. Vital signs and oxygen saturation before and after neostigmine were recorded.Key ResultsOf the 144 patients, 133 were female, mean age was 41.0 ± 15.4 years (SD), and duration of constipation was 12.9 ± 13.8 years. Among patients who had undergone colonic transit measurement by scintigraphy, the overall colonic transit at 24 h (geometric center, GC24 [n = 115]) was 1.5 ± 0.7 (normal >1.3), and at 48 h (GC48 [n = 75]) it was 2.3 ± 0.9 (normal >1.9). Neostigmine decreased colonic compliance at lower distension pressures (e.g., 12 and 20 mmHg [both p < 0.001]), but not at 40 mmHg. There were expected minor changes in vital signs in response to neostigmine in 144 patients; however, one patient developed unresponsiveness, significant bradycardia, hypotension, and muscular rigidity that responded to 400 mcg i.v. atropine.Conclusions & InferencesNeostigmine significantly decreases colonic compliance in patients with refractory chronic constipation. Symptomatic bradycardia in response to neostigmine should be promptly reversed with atropine.

Abstract Background Gastrointestinal ( GI ) manifestations are found in Ehlers Danlos syndrome ( EDS ) hypermobility subtype ( HM ). We aimed to assess associations between EDS HM and other EDS subtypes with GI manifestations. Methods We reviewed medical records of EDS patients evaluated at Mayo Clinic's Medical Genetics Clinic 1994–2013. We extracted information regarding EDS subtypes, GI manifestations, and treatments. Key Results We identified 687 patients; 378 (56%) had associated GI manifestations (female 86.8%, diagnosis mean age 29.6 years). Of the patients identified, 58.9% (43/73) had EDS classic, 57.5% (271/471) EDS HM , 47.3% (27/57) EDS vascular subtypes. In addition, 86 patients had EDS that could not be classified in any of those three subtypes. Commonest GI symptoms were: abdominal pain (56.1%), nausea (42.3%), constipation (38.6%), heartburn (37.6%), and irritable bowel syndrome‐like symptoms (27.5%). Many GI symptoms were commoner in EDS HM than the other subtypes together. Among 37.8% of the 378 patients who underwent esophagogastroduodenoscopy, the commonest abnormalities were gastritis, hiatal hernia and reflux esophagitis. Abnormal gastric emptying was observed in 22.3% (17/76): 11.8% delayed and 10.5% accelerated. Colonic transit was abnormal in 28.3% (13/46): 19.6% delayed and 8.7% accelerated. Rectal evacuation disorder was confirmed in 18/30 patients who underwent anorectal manometry. Angiography showed aneurysms in abdominal vessels in EDS vascular type. Proton pump inhibitors (38%) and drugs for constipation (23%) were the most commonly used medications. A minority underwent colectomy (2.9%) or small bowel surgery (4%). Conclusions & Inferences EDS HM and other subtypes should be considered in patients with chronic functional GI symptoms and abdominal vascular lesions.

There is no universally available laboratory test to diagnose bile acid diarrhoea (BAD). Objective To conduct a systematic review and meta-analysis to identify a biomarker for idiopathic BAD in patients with functional bowel disorder (FBD) with diarrhoea. Design We searched multiple databases through 15 May 2015. Data were only available to estimate the diagnostic yield of each test (the prevalence of a positive test). Estimates were pooled across studies using the random effects model. Results We included 36 studies, enrolling 5028 patients (24 using 75 selenium homotaurocholic acid test ( 75 SeHCAT) retention of <10%, 6 using fasting serum C4, 3 using fasting serum fibroblast growth factor 19 (FGF19) and 2 based on total faecal bile acid (BA) excretion over 48 h). The diagnostic yields (and 95% CI) of abnormal tests were: 0.308 (0.247 to 0.377) for 75 SeHCAT retention (<10%), 0.171 (0.134 to 0.217) for serum C4, 0.248 (0.147 to 0.385) for serum FGF19 and 0.255 (0.071 to 0.606) for total faecal BA excretion over 48 h. The majority of the analyses were associated with substantial heterogeneity. Performance characteristics relative to a gold standard test could not be estimated. Conclusions Overall, the test with the highest diagnostic yield conducted in the largest number of studies was 75 SeHCAT retention, which is not widely available in many countries outside Europe and Canada. Using different diagnostic tests, 25% (average) of patients with lower FBD with diarrhoea has evidence of idiopathic BAD. These tests serve to identify idiopathic BAD among patients with FBD with diarrhoea. Further studies are required to appraise the performance characteristics of tests for idiopathic BAD.

Obective Glucagon‐like peptide‐1 (GLP‐1) receptor agonists are indicated for treatment of type 2 diabetes since they mimic the actions of native GLP‐1 on pancreatic islet cells, stimulating insulin release, while inhibiting glucagon release, in a glucose‐dependent manner. The observation of weight loss has led to exploration of their potential as antiobesity agents, with liraglutide 3.0 mg day −1 approved for weight management in the US on December 23, 2014, and in the EU on March 23, 2015. This review examines the potential nonglycemic effects of GLP‐1 receptor agonists. Methods A literature search was conducted to identify preclinical and clinical evidence on nonglycemic effects of GLP‐1 receptor agonists. Results GLP‐1 receptors are distributed widely in a number of tissues in humans, and their effects are not limited to the well‐recognized effects on glycemia. Nonglycemic effects include weight loss, which is perhaps the most widely recognized nonglycemic effect. In addition, effects on the cardiovascular, neurologic, and renal systems and on taste perception may occur independently of weight loss. Conclusions GLP‐1 receptor agonists may provide other nonglycemic clinical effects besides weight loss. Understanding these effects is important for prescribers in using GLP‐1 receptor agonists for diabetic patients, but also if approved for chronic weight management.

The mucosal gene expression in rectosigmoid mucosa (RSM) in irritable bowel syndrome with diarrhea (IBS-D) is unknown. Our objectives were, first, to study mRNA expression [by RT2 PCR of 19 genes pertaining to tight junctions, immune activation, intestinal ion transport and bile acid (BA) homeostasis] in RSM in IBS-D patients ( n = 47) and healthy controls ( n = 17) and study expression of a selected protein (PDZD3) in 10 IBS-D patients and 4 healthy controls; second, to assess RSM mRNA expression according to genotype and fecal BA excretion (high ≥2,337 μmol/48 h); and third, to determine whether genotype or mucosal mRNA expression is associated with colonic transit or BA parameters. Fold changes were corrected for false detection rate for 19 genes studied ( P < 0.00263). In RSM in IBS-D patients compared with controls, mRNA expression of GUC2AB, PDZD3, and PR2Y4 was increased, whereas CLDN1 and FN1 were decreased. One immune-related gene was upregulated (C4BP4) and one downregulated (CCL20). There was increased expression of a selected ion transport protein (PDZD3) on immunohistochemistry and Western blot in IBS-D compared with controls ( P = 0.02). There were no significant differences in mucosal mRNA in 20 IBS-D patients with high compared with 27 IBS-D patients with normal BA excretion. GPBAR1 ( P < 0.05) was associated with colonic transit. We concluded that mucosal ion transport mRNA (for several genes and PDZD3 protein) is upregulated and barrier protein mRNA downregulated in IBS-D compared with healthy controls, independent of genotype. There are no differences in gene expression in IBS-D with high compared with normal fecal BA excretion.

ObjectiveTo examine the association of gene variants of uncoupling proteins (UCP)‐2 and −3 with obesity and gastrointestinal (GI) traits.MethodsIn 255 overweight or obese adults, the associations of gene variants in UCP‐2 (−3474, rs659366) and UCP‐3 (rs1626521, rs2075577, rs15763) with body weight (BW) and GI traits were studied. Gene variants were genotyped by TaqMan® assay. The associations of genotypes with BW and GI traits (gastric emptying, gastric volume, satiety by buffet meal, satiation by nutrient drink test and GI hormones) were assessed using ANOVA corrected for false detection rate (FDR).ResultsA novel UCP‐3 gene variant, rs1626521, was identified; it was associated with BW (P = 0.039), waist circumference (P = 0.035), and significantly higher postprandial gastric volume (P = 0.003) and calories ingested at buffet meal (P = 0.006, both significant with FDR). In a subgroup of 11 participants, rs1626521 was also associated with reduced mitochondrial bioenergetics efficiency in skeletal muscle (P = 0.051). In an in vitro study in HEK293 cells, rs1626521 reduced UCP‐3 protein expression (P = 0.049). Associations detected between other genotypes and GI traits were nonsignificant with FDR.ConclusionsA newly identified functional variant (rs1626521) in UCP‐3 affects postprandial gastric functions and satiety and may contribute to weight gain and alter human mitochondrial function.

Summary Background About one‐third of patients with IBS ‐diarrhoea (irritable bowel syndrome‐D) have evidence of increased bile acid synthesis or excretion. Aims To assess effects of the bile acid sequestrant, colesevelam, on faecal excretion of BA s, hepatic BA synthesis and diarrhoea in IBS ‐D; to appraise whether individual or random stool samples accurately reflect 48‐h total faecal bile acid excretion and proportions of the main bile acids excreted and to study the faecal fat excretion in response to colesevelam. Methods A single‐centre, unblinded, single‐dose trial of effects of colesevelam, 1875 mg [3 tablets (625 mg tablets)] orally, twice daily, for 10 days on total 48‐h faecal bile acid excretion and fasting serum C4 (7α‐hydroxy‐4‐cholesten‐3‐one; surrogate of hepatic bile acid synthesis). Stool diaries documented bowel functions for 8 days prior and 8 days during colesevelam treatment. Stool 48‐h samples and fasting serum were collected for faecal fat, faecal bile acid and serum C4. Results Colesevelam was associated with significantly increased faecal total bile acid excretion and deoxycholic acid excretion, increased serum C4 and more solid stool consistency. There was a significant inverse correlation between number of bowel movements per week and the total bile acid sequestered into stool during the last 48 h of treatment. Random stool samples did not accurately reflect 48‐h total or individual faecal bile acid excretion. Sequestration of bile acids by colesevelam did not increase faecal fat. Conclusions Colesevelam increases delivery of bile acids to stool while improving stool consistency, and increases hepatic bile acid synthesis, avoiding steatorrhoea in patients with IBS ‐D. Overall effects are consistent with luminal bile acid sequestration by colesevelam.