Systematic review: the prevalence of idiopathic bile acid malabsorption as diagnosed by SeHCAT scanning in patients with diarrhoea-predominant irritable bowel syndrome

Randomised clinical trial: significant biochemical and colonic transit effects of the farnesoid X receptor agonist tropifexor in patients with primary bile acid diarrhoea

BACKGROUND

In primary bile acid diarrhoea, feedback by farnesoid X receptor (FXR) and fibroblast growth hormone 19 (FGF19) on hepatic bile acid production is impaired.

AIMS

To evaluate the safety, mechanisms and efficacy of negative feedback by FXR activation with tropifexor, a non-bile acid FXR agonist, in patients with primary bile acid diarrhoea.

METHODS

In this double-blind, multicentre, randomised, cross-over study, patients received tropifexor 60 µg or placebo once daily for 14 days in each of two treatment periods. Primary objectives included tropifexor safety and tolerability, and on stool frequency and form. Other assessments included pharmacokinetic and pharmacodynamic measures, biochemical markers and gastrointestinal transit.

RESULTS

Twenty patients (tropifexor 60 µg/placebo [N = 10]; placebo/tropifexor 60 µg [N = 10]) were enrolled. Adverse event rates were lower with tropifexor vs placebo (52.9% vs 73.7%). No patient had pruritus during tropifexor intake. There were no significant differences in stool frequency, stool form or loperamide use between treatments. Tropifexor increased FGF19 and decreased 7α-hydroxy-4-cholesten-3-one (C4) levels for up to 8 h. Plasma tropifexor concentrations peaked at 5 hours post-dose on days 1 and 12. At day 12, tropifexor caused reduction in peak total bile acid concentration (33%, P = 0.032) and exposure (36%, P = 0.005). Moreover, tropifexor showed a significant increase in ascending colon half-emptying time (P = 0.036).

CONCLUSIONS

Tropifexor 60 µg once daily had acceptable safety and tolerability. Changes in FGF19 and C4 showed effective target engagement; however, higher doses may be required to observe stool frequency changes. Slowing of ascending colon emptying suggests therapeutic potential of tropifexor in patients with primary bile acid diarrhoea. ClinicalTrials.gov number: NCT02713243.

High prevalence of primary bile acid diarrhoea in patients with functional diarrhoea and irritable bowel syndrome-diarrhoea, based on Rome III and Rome IV criteria

BACKGROUND

A high prevalence of primary bile acid diarrhoea (BAD) has been reported for Rome III defined irritable bowel syndrome (IBS)-diarrhoea and functional diarrhoea. We determined whether this still applies under the contemporaneous Rome IV criteria, given that the latter characterises IBS-diarrhoea as having more frequent abdominal pain compared with previous iterations, whilst no longer recognising abdominal discomfort.

METHODS

Patients referred for a 75SeHCAT test completed a baseline questionnaire comprising, i) demographic data, ii) risk factors for BAD (inflammatory bowel disease, bowel resection, cholecystectomy, microscopic colitis, celiac disease, abdominal-pelvic radiotherapy), iii) the Rome III and IV bowel disorder questionnaire, and iv) mood and somatisation scores. A diagnosis of BAD constituted a 75SeHCAT of ≤15%, with moderate to severe disease being defined as ≤10% and ≤5%, respectively.

FINDINGS

Of 300 patients with complete dataset, 184 had no risk factors for BAD and fulfilled criteria for either IBS-diarrhoea or functional diarrhoea. The prevalence of primary BAD was 38% (n = 70/184), with almost half having moderate (n = 16) to severe (n = 17) disease. Using the Rome III criteria, the prevalence of primary BAD was 36% in IBS-diarrhoea (n = 63/173) and 64% (n = 7/11) in functional diarrhoea; p = 0.11. Using the Rome IV criteria, the prevalence of primary BAD was 38% (n = 53/139) in IBS-diarrhoea and 38% (n = 17/45) in functional diarrhoea; p = 0.97. Patients with primary BAD experienced more frequent loose stools (p = 0.01) and had a higher body mass index (p<0.0001) compared to those without BAD, but otherwise no significant differences were seen in age, gender, mood, somatisation, or abdominal pain. The presence of primary BAD in patients classified as overweight or obese was approximately 40% and 60%, respectively.

INTERPRETATION

Over a third of patients with Rome IV IBS-diarrhoea or functional diarrhoea have primary BAD, similar to Rome III. We therefore recommend that, in secondary care settings, generic testing for primary BAD should be considered in patients presenting with chronic diarrhoea of presumed functional origin regardless of concomitant abdominal pain. Centres that lack tests for primary BAD, and who empirically treat instead, may consider targeting patients who are overweight or obese.

Chronic diarrhea, bile acids, and Clostridia

Excessive fecal bile acid (BA) loss causes symptoms in a large proportion of people diagnosed with irritable bowel syndrome with diarrhea, a common functional bowel disorder. This BA diarrhea (BAD) results from increased hepatic synthesis of BAs, with impaired negative feedback regulation by the ileal hormone fibroblast growth factor 19 (FGF19). In this issue of the JCI, Zhao et al. investigated BA metabolism, including fecal BAs, serum BAs, and FGF19, in patients and controls. They identified associations between fecal bacterial BA metabolism and specific microbiota, especially Clostridium scindens. These findings have been tested in a mouse model using microbiota transplants and antibiotic treatment. This group of organisms has potential as a biomarker for BAD and to be a target for therapy.

Fecal Bile Acid Testing in Assessing Patients With Chronic Unexplained Diarrhea: Implications for Healthcare Utilization

INTRODUCTION

Bile acid (BA) diarrhea is the cause in ∼26% of chronic unexplained (nonbloody) diarrhea (CUD) based on SeHCAT testing. To assess fecal BA excretion and healthcare utilization in patients with CUD.

METHODS

In a retrospective review of 1,071 consecutive patients with CUD who completed 48-hour fecal BA testing, we analyzed the symptoms, diagnostic tests performed, and final diagnoses.

RESULTS

After 135 patients were excluded because of mucosal diseases, increased BA excretion was identified in 476 (51%) of the 936 patients with CUD: 29% with selective increase in primary BA and 22% with increased total BA excretion (35% with normal primary BA excretion). There were no differences in demographics, clinical symptoms, or history of cholecystectomy in patients with elevated total or selective primary fecal BA excretion compared with patients with normal excretion. Before the 48-hour fecal BA excretion test was performed, patients completed on average 1.2 transaxial imaging, 2.6 endoscopic procedures, and 1.6 miscellaneous tests/person. Less than 10% of these tests identified the etiology of CUD. Total fecal BAs >3,033 µmol/48 hour or primary BAs >25% had a 93% negative predictive value to exclude mucosal disease. Among patients with increased fecal BA excretion, >70% reported diarrhea improved with BA sequestrant compared with 26% with normal fecal BA excretion. Patients with selective elevation in primary fecal BAs were 3.1 times (95% confidence interval, 1.5-6.63) more likely to respond to BA sequestrant therapy compared with those with elevated total fecal BAs.

DISCUSSION

Increased fecal BA excretion is frequent (51%) in patients with CUD. Early 48-hour fecal BA evaluation has the potential to decrease healthcare utilization in CUD.

Capacitive sensing of triglyceride film reactions: a proof-of-concept demonstration for sensing in simulated duodenal contents with gastrointestinal targeting capsule system

Ingestible capsule systems continue to evolve to overcome drawbacks associated with traditional gastrointestinal (GI) diagnostic and therapeutic processes, such as limitations on which sections of the GI tract can be accessed or the inability to measure local biomarker concentrations. We report an integrated capsule sensing system, utilizing a hybrid packaging scheme coupled with triglyceride film-coated capacitive sensors, for measuring biochemical species present in the duodenum, such as pancreatic lipase and bile acids. The system uses microfabricated capacitive sensors interfaced with a Bluetooth low-energy (BLE)-microcontroller, allowing wireless connectivity to a mobile app. The triglyceride films insulate the sensor surface and react either with 0.01-1 mM lipase via hydrolysis or 0.07-7% w/v bile acids via emulsification in simulated fluids, leading to measurable changes in capacitance. Cross reactivity of the triglyceride films is evaluated in both phosphate buffered saline (PBS) as well as pancreatic trypsin solutions. The film morphology is observed after exposure to each stimulus to better understand how these changes alter the sensor capacitance. The capsule utilizes a 3D-printed package coated with polymers that remain intact in acid solution (mimicking gastric conditions), then dissolve at a duodenum-mimicking neutral pH for triggered opening of the sensing chamber from which we can subsequently detect the presence of pancreatic lipase. This device strategy represents a significant step towards using embedded packaging and triglyceride-based materials to target specific regions of the GI tract and sensing biochemical contents for evaluating gastrointestinal health.

The association between irritable bowel syndrome and osteoporosis: a systematic review and meta-analysis

BACKGROUND

Recent studies have suggested that irritable bowel syndrome (IBS) could be a risk factor for osteoporosis although the evidence is still limited. The current study aimed to comprehensively examine the risk of osteoporosis among patients with IBS using systematic review and meta-analysis technique.

METHODOLOGY

Literature search was independently conducted by two investigators using MEDLINE, EMBASE, and Google Scholar database up to October 2019. Eligible study must evaluate whether patients with IBS have a higher risk of osteoporosis and/or osteoporotic fracture. It could be either cross-sectional study, case-control study, or cohort study. Point estimates and standard errors from each eligible study were combined together using the generic inverse variance method of DerSimonian and Laird.

RESULTS

Of the 320 articles identified from the three databases, four cohort and one cross-sectional study with 526,633 participants met the eligibility criteria and were included into the meta-analysis. All five studies investigated the risk of osteoporosis among patients with IBS, and the pooled analysis found that patients with IBS had a significantly higher risk of osteoporosis than individuals without IBS with the pooled risk ratio of 1.95 (95% CI, 1.04-3.64; I² 100%). Sensitivity analysis including only cohort studies found a lower RR (pooled RR 1.55; 95% CI, 1.39-1.72) with a lower I² (59%). Three studies investigated the risk of osteoporotic fracture, and the pooled analysis found that patients with IBS also had a higher risk of osteoporotic fracture than individuals without IBS with the pooled risk ratio of 1.58 although statistical significance was not reached (95% CI, 0.95-2.62; I² 99%). Sensitivity analysis including only cohort studies found a lower RR (pooled RR 1.27; 95% CI, 1.20-1.39) with a dramatically lower I² (0%). Limitations included high heterogeneity and reliance on diagnostic codes.

CONCLUSION

A significantly increased risk of osteoporosis among IBS patients was observed in this study. Early intervention to prevent the development of osteoporosis, such as weight-bearing exercise, adequate intake of vitamin D and calcium, and early screening for osteoporosis, may be beneficial to these patients although further studies are still required to confirm the efficacy and cost-effectiveness of this approach.

Marshall and Warren Lecture 2019: A paradigm shift in pathophysiological basis of irritable bowel syndrome and its implication on treatment

Irritable bowel syndrome (IBS), a common functional gastrointestinal disorder (FGID), has often been considered rather inappropriately as psychogenic in the past. Though psychological issues are important comorbidities in a proportion of IBS patients, the evidences are far from enough to label this condition as psychogenic only. In the recent past, evidences are emerging that underscores the concept supporting pure psychogenic theory of IBS and suggest this disorder to be rather microorganic. Accordingly, a move of Rome IV Committee attempting to delete the term "functional" and designating these to be disorders of "gut-brain interaction" rather than that of "brain-gut interaction," it emphasizes the importance of the gut over the brain in the pathogenesis. The introduction of the concept of multidimensional clinical profile in Rome IV requires attention to diagnostic category of FGID, overlap, severity, psychological issues, and physiological dysfunction or biomarkers; this attempts to recognize clinical variability and multidimensionality of pathophysiology and management of these disorders. The recognition of the biological factors in the pathogenesis of IBS is a significant paradigm shift in the recent time. This is somewhat similar to the progress in the pathogenesis of peptic ulcer disease from psychological factor to acid to Helicobacter pylori infection. It is expected that in the near future, therapeutic modalities targeting the different pathogenic mechanisms of different subtypes of IBS may bring revolution in management of the disorder.

Bile Acid Diarrhea and NAFLD: Shared Pathways for Distinct Phenotypes

Irritable bowel syndrome with diarrhea (IBS-D) and NAFLD are both common conditions that may be influenced by shared pathways of altered bile acid (BA) signaling and homeostatic regulation. Pathophysiological links between IBS-D and altered BA metabolism include altered signaling through the ileal enterokine and fibroblast growth factor 19 (FGF19) as well as increased circulating levels of 7α-hydroxy-4-cholesten-3-one, a metabolic intermediate that denotes increased hepatic BA production from cholesterol. Defective production or release of FGF19 is associated with increased BA production and BA diarrhea in some IBS-D patients. FGF19 functions as a negative regulator of hepatic cholesterol 7α-hydroxylase; therefore, reduced serum FGF19 effectively de-represses hepatic BA production in a subset of IBS-D patients, causing BA diarrhea. In addition, FGF19 modulates hepatic metabolic homeostatic response signaling by means of the fibroblast growth factor receptor 4/klotho beta receptor to activate cascades involved in hepatic lipogenesis, fatty acid oxidation, and insulin sensitivity. Emerging evidence of low circulating FGF19 levels in subsets of patients with pediatric and adult NAFLD demonstrates altered enterohepatic BA homeostasis in NAFLD. Conclusion: Here we outline how understanding of shared pathways of aberrant BA homeostatic signaling may guide targeted therapies in some patients with IBS-D and subsets of patients with NAFLD.

The Effects of the Rome IV Criteria on Pediatric Gastrointestinal Practice

PURPOSE OF REVIEW

To evaluate the impact of the implementation of the Rome IV criteria on pediatric gastrointestinal practice.

RECENT FINDINGS

In 2016, the Rome IV criteria were published, providing an update of symptom-based criteria to diagnose children with functional gastrointestinal disorders (FGIDs). For neonates and toddlers, Wessel's criteria for diagnosing infant colic were abandoned, and a differentiation was made between toilet-trained and non-toilet-trained children in the diagnosis of functional constipation. For children and adolescents, two new disorders (functional nausea and functional vomiting) are described, and in the diagnosis of functional dyspepsia, pain does not have to be the chief complaint anymore. This change has made functional dyspepsia the most common functional abdominal pain disorder, exceeding the prevalence of irritable bowel syndrome (IBS). Lastly, the diagnosis of abdominal migraine was narrowed, causing an appropriate drop in its prevalence.

Rational investigations in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder which accounts for a substantial proportion of a gastroenterologist's time in the outpatient clinic. However, there is variability in approaches to diagnosis and investigation between physicians, dependent on expertise. Many patients express disappointment over the lack of a patient-centred approach. Consequently, there have been calls for the care of patients with IBS to be standardised, a process which aims to promote high-quality and high-value care. Making an early diagnosis, based on a clinical assessment of symptoms, while limiting use of investigations, are key tenets of this process. Exhaustive investigation to exclude all organic pathology is unnecessary, and may be counterproductive. Routine blood tests in suspected IBS have low yield, but are an acceptable part of routine practice. All patients should have coeliac serology tested, regardless of their predominant stool form. Patients with diarrhoea should have a faecal calprotectin measured, and should proceed to colonoscopy to exclude inflammatory bowel disease (IBD) if this is positive. Beyond this, the need for investigations should be made on a case-by-case basis, contingent on the reporting of known risk factors for organic pathology. Colonoscopy should be considered in any patient with alarm features for colorectal cancer, and in those whose clinical features are suggestive of microscopic colitis. A 23-seleno-25-homotaurocholic acid (SeHCAT) scan should be considered in patients with IBS-D, a third of whom may actually have bile acid diarrhoea. There is no role for routine hydrogen breath tests for lactose malabsorption or small intestinal bacterial overgrowth.

Canadian Association of Gastroenterology Clinical Practice Guideline on the Management of Bile Acid Diarrhea

BACKGROUND & AIMS

Chronic diarrhea affects about 5% of the population overall. Altered bile acid metabolism is a common but frequently undiagnosed cause.

METHODS

We performed a systematic search of publication databases for studies of assessment and management of bile acid diarrhea (BAD). The certainty (quality) of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation approach. Patient population, intervention, comparator, and outcome questions were developed through an iterative process and were voted on by a group of specialists.

RESULTS

The certainty of evidence was generally rated as very low. Therefore, 16 of 17 recommendations are conditional. In patients with chronic diarrhea, consideration of risk factors (terminal ileal resection, cholecystectomy, or abdominal radiotherapy), but not additional symptoms, was recommended for identification of patients with possible BAD. The group suggested testing using ⁷⁵selenium homocholic acid taurine (where available) or 7α-hydroxy-4-cholesten-3-one, including patients with irritable bowel syndrome with diarrhea, functional diarrhea, and Crohn's disease without inflammation. Testing was suggested over empiric bile acid sequestrant therapy (BAST). Once remediable causes are managed, the group suggested cholestyramine as initial therapy, with alternate BAST when tolerability is an issue. The group suggested against BAST for patients with extensive ileal Crohn's disease or resection and suggested alternative antidiarrheal agents if BAST is not tolerated. Maintenance BAST should be given at the lowest effective dose, with a trial of intermittent, on-demand administration, concurrent medication review, and reinvestigation for patients whose symptoms persist despite BAST.

CONCLUSIONS

Based on a systematic review, BAD should be considered for patients with chronic diarrhea. For patients with positive results from tests for BAD, a trial of BAST, initially with cholestyramine, is suggested.

Intestinal Absorption of Bile Acids in Health and Disease

The intestinal reclamation of bile acids is crucial for the maintenance of their enterohepatic circulation. The majority of bile acids are actively absorbed via specific transport proteins that are highly expressed in the distal ileum. The uptake of bile acids by intestinal epithelial cells modulates the activation of cytosolic and membrane receptors such as the farnesoid X receptor (FXR) and G protein-coupled bile acid receptor 1 (GPBAR1), which has a profound effect on hepatic synthesis of bile acids as well as glucose and lipid metabolism. Extensive research has focused on delineating the processes of bile acid absorption and determining the contribution of dysregulated ileal signaling in the development of intestinal and hepatic disorders. For example, a decrease in the levels of the bile acid-induced ileal hormone FGF15/19 is implicated in bile acid-induced diarrhea (BAD). Conversely, the increase in bile acid absorption with subsequent overload of bile acids could be involved in the pathophysiology of liver and metabolic disorders such as fatty liver diseases and type 2 diabetes mellitus. This review article will attempt to provide a comprehensive overview of the mechanisms involved in the intestinal handling of bile acids, the pathological implications of disrupted intestinal bile acid homeostasis, and the potential therapeutic targets for the treatment of bile acid-related disorders. Published 2020. Compr Physiol 10:21-56, 2020.

Review of the management of diarrhea syndrome after a bariatric surgery

Obesity is a prevalent health problem in our population. Bariatric surgery is the indicated treatment for severe cases. It is very effective (together with an adequate lifestyle modification) but it is also associated with frequent adverse events. One of the most frequent and disturbing adverse event is diarrhea. Diarrhea after bariatric surgery may be secondary to multiple causes and the physiopathogenic mechanisms may depend on the type of surgery performed. The most frequent diarrhea mechanisms are dumping syndrome, vagotomy, short bowel syndrome, carbohydrate malabsorption, protein malabsorption, alterations of the microbiota, Clostridium difficile infection, bacterial overgrowth, bile salt malabsorption, pancreatic insufficiency, endocrinological disorders, addictive disorders, and other digestive disorders not necessarily related to surgery.

Canadian Association of Gastroenterology Clinical Practice Guideline on the Management of Bile Acid Diarrhea

Background and Aims

Chronic diarrhea affects about 5% of the population overall. Altered bile acid metabolism is a common but frequently undiagnosed cause.

Methods

We performed a systematic search of publication databases for studies of assessment and management of bile acid diarrhea (BAD). The certainty (quality) of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation approach. Patient population, intervention, comparator and outcome questions were developed through an iterative process and were voted on by a group of specialists.

Results

The certainty of evidence was generally rated as very low. Therefore, 16 of 17 recommendations are conditional. In patients with chronic diarrhea, consideration of risk factors (terminal ileal resection, cholecystectomy or abdominal radiotherapy), but not additional symptoms, was recommended for identification of patients with possible BAD. The group suggested testing using ⁷⁵selenium homocholic acid taurine (where available) or 7α-hydroxy-4-cholesten-3-one, including patients with irritable bowel syndrome with diarrhea, functional diarrhea and Crohn's disease without inflammation. Testing was suggested over empiric bile acid sequestrant therapy (BAST). Once remediable causes are managed, the group suggested cholestyramine as initial therapy, with alternate BAST when tolerability is an issue. The group suggested against BAST for patients with extensive ileal Crohn's disease or resection and suggested alternative antidiarrheal agents if BAST is not tolerated. Maintenance BAST should be given at the lowest effective dose, with a trial of intermittent, on-demand administration, concurrent medication review and reinvestigation for patients whose symptoms persist despite BAST.

Conclusions

Based on a systematic review, BAD should be considered for patients with chronic diarrhea. For patients with positive results from tests for BAD, a trial of BAST, initially with cholestyramine, is suggested.

Methods for diagnosing bile acid malabsorption: a systematic review

BACKGROUND

Bile acid malabsorption (BAM) and bile acid-related diarrhea represent an under-recognized cause of chronic diarrhea mainly because of limited guidance on appropriate diagnostic and laboratory tests. We aimed to perform a systematic review of the literature in order to identify and compare the diagnostic accuracy of different diagnostic methods for patients with BAM, despite a proven gold standard test is still lacking.

METHODS

A PubMed literature review and a manual search were carried out. Relevant full papers, evaluating the diagnostic accuracy of different methods for BAM, were assessed. Available data were analyzed to estimate the sensitivity and specificity of each published test.

RESULTS

Overall, more than one test was considered in published papers on BAM. The search strategy retrieved 574 articles; of these, only 16 were full papers (with a total of 2.332 patients) included in the final review. Specifically, n = 8 studies used ⁷⁵Selenium-homotaurocholic-acid-test (⁷⁵SeHCAT) with a < 10% retention threshold; n = 8 studies evaluated fasting serum 7-α-hydroxy-4-cholesten-3-one (C4); n = 3 studies involved total fecal bile acid (BA) excretion over 48 h; n = 4 studies assessed fibroblast growth factor 19 (FGF19). ⁷⁵SeHCAT showed an average sensitivity and specificity of 87.32 and 93.2%, respectively, followed by serum C4 (85.2 and 71.1%) and total fecal BA (66.6 and 79.3%). Fasting serum FGF19 had the lowest sensitivity and specificity (63.8 and 72.3%). All the extracted data were associated with substantial heterogeneity.

CONCLUSIONS

Our systematic review indicates that ⁷⁵SeHCAT has the highest diagnostic accuracy for BAM, followed by serum C4 assay. The diagnostic yield of fecal BA and FGF19 assays is still under investigation. Our review reinforces the need for novel biomarkers aimed to an objective detection of BAM and therefore improving the management of this condition.

What's in the pipeline for lower functional gastrointestinal disorders in the next 5 years?

The overall objectives of this review are to summarize actionable biomarkers for organic etiology of lower functional gastrointestinal disorders (FGIDs) that lead to individualized treatment for their FGIDs and to assess the pipeline for novel approaches to the management of constipation, diarrhea, and chronic abdominal pain in lower FGIDs. The new approaches to therapy include ion exchangers/transporters for functional constipation (sodium-glucose cotransporter 1, Na+/H+ exchanger 3, and solute carrier family 26 member 3 inhibitors), bile acid modulators for constipation such as ileal bile acid transporter inhibitors and fibroblast growth factor 19 analog for functional constipation, and bile acid sequestrants or farnesoid X receptor agonists for functional diarrhea. Treatment for chronic abdominal pain remains an unmet need in patients with lower FGIDs, and promising novel approaches include delayed-release linaclotide, nonclassical opioid visceral analgesics, and selective cannabinoid receptor agonists. The role of probiotics, fecal microbial transplantation, and possible future microbiome therapies is discussed.

Inhibition of CFTR-mediated intestinal chloride secretion as potential therapy for bile acid diarrhea

Bile acid diarrhea (BAD) is common with ileal resection, Crohn's disease, and diarrhea-predominant irritable bowel syndrome. Here, we demonstrate the efficacy of cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor (R)-benzopyrimido-pyrrolo-oxazine-dione-27 (BPO-27) in reducing bile acid-induced fluid and electrolyte secretion in colon. Short-circuit current measurements in human T84 colonic epithelial cells and planar colonic enteroid cultures showed a robust secretory response following mucosal but not serosal addition of chenodeoxycholic acid (CDCA) or its taurine conjugate, which was fully blocked by CFTR inhibitors, including (R)-BPO-27. (R)-BPO-27 also fully blocked CDCA-induced secretory current in murine colon. CFTR activation by CDCA primarily involved Ca2+ signaling. In closed colonic loops in vivo, luminal CDCA produced a robust secretory response, which was reduced by ∼70% by (R)-BPO-27 or in CFTR-deficient mice. In a rat model of BAD produced by intracolonic infusion of CDCA, (R)-BPO-27 reduced the elevation in stool water content by >55%. These results implicate CFTR activation in the colon as a major prosecretory mechanism of CDCA, a bile acid implicated in BAD, and support the potential therapeutic efficacy of CFTR inhibition in bile acid-associated diarrheas.-Duan, T., Cil, O., Tse, C. M., Sarker, R., Lin, R., Donowitz, M., Verkman, A. S. Inhibition of CFTR-mediated intestinal chloride secretion as potential therapy for bile acid diarrhea.

Diagnosis and management of bile acid diarrhoea: a survey of UK expert opinion and practice

OBJECTIVE

Bile acid diarrhoea (BAD), which includes bile acid malabsorption, causes a variety of digestive symptoms. Diagnostic rates and management vary considerably. We conducted a survey of current practice to review expert opinion and provide guidance on diagnosis and management.

DESIGN/METHOD

An online survey was conducted of clinical members of the UK Bile Acid Related Diarrhoea Network, who had all published research on BAD (n=21). Most were National Health Service consultants who had diagnosed over 50 patients with the condition.

RESULTS

The preferred terminology was to use BAD, with primary and secondary to classify causes. A wide range of presenting symptoms and associated conditions were recognised. SeHCAT (tauroselcholic acid) was the preferred diagnostic test, and 50% of respondents thought general practitioners should have access to this. Patients who met the Rome IV diagnostic criteria for functional diarrhoea, irritable bowel syndrome (IBS) with predominant diarrhoea or postcholecystectomy diarrhoea were usually investigated by SeHCAT, which was used sometimes in other types of IBS. Treatment with a bile acid sequestrant was offered to patients with low SeHCAT values, with expected response rates >70% in the most severe. Colestyramine was the usual sequestrant, starting between 2 g and 8 g daily; colesevelam was an alternative. In patients who had an incomplete response, increasing the dose, changing to an alternative sequestrant, use of loperamide and a low fat diet were suggested. Recommendations for follow-up and to improve the overall patient experience were made.

CONCLUSION

This expert survey indicates current best practice in the diagnosis and management of BAD.

Prevalence of, and predictors of, bile acid diarrhea in outpatients with chronic diarrhea: A follow-up study

BACKGROUND

23-seleno-25-homo-tauro-cholic acid (SeHCAT) scanning to rule out bile acid diarrhea (BAD) in patients with chronic diarrhea has a high yield. Our previous study showed that patients with terminal ileal (TI) Crohn's disease, TI resection, or cholecystectomy were highly likely to have an abnormal scan. As a result, we encouraged clinicians to use a therapeutic trial of a bile acid sequestrant in these patients, instead of scanning. This may have reduced diagnostic yield of the test, so we examined this issue, as well as factors predicting an abnormal scan, in a large cohort of patients referred subsequently.

METHODS

We retrospectively identified 1,071 consecutive patients with chronic diarrhea undergoing SeHCAT scanning at Leeds Teaching Hospitals Trust from 2012 to 2016. We reviewed electronic patient records to obtain information on presenting gastrointestinal symptoms and any proposed risk factors for BAD. BAD was categorized according to subtype and severity.

KEY RESULTS

As expected, indications for scanning changed between 2012 and 2016, with a significant reduction in referrals with TI Crohn's disease or resection year-on-year (P < 0.001). Despite this, 457 (42.7%) patients had BAD and there was no downward trend in yield of SeHCAT during the 5 year period (P = 0.39). Overall, 51.6% had type II BAD, 36.1% type III, and 12.3% type I. BAD was mild in 31.7%, moderate in 34.4%, and severe in 33.9%. In total, 653 (61.0%) patients had no known risk factors, other than chronic diarrhea, but 233 (35.7%) of these individuals had BAD, and in 143 (61.4%), this was moderate or severe.

CONCLUSIONS AND INFERENCES

Despite reduced referrals for SeHCAT scanning in those with clear risk factors for BAD, the yield remained > 40%. One-third of those without known risk factors had BAD.

Physiology of Electrolyte Transport in the Gut: Implications for Disease

We now have an increased understanding of the genetics, cell biology, and physiology of electrolyte transport processes in the mammalian intestine, due to the availability of sophisticated methodologies ranging from genome wide association studies to CRISPR-CAS technology, stem cell-derived organoids, 3D microscopy, electron cryomicroscopy, single cell RNA sequencing, transgenic methodologies, and tools to manipulate cellular processes at a molecular level. This knowledge has simultaneously underscored the complexity of biological systems and the interdependence of multiple regulatory systems. In addition to the plethora of mammalian neurohumoral factors and their cross talk, advances in pyrosequencing and metagenomic analyses have highlighted the relevance of the microbiome to intestinal regulation. This article provides an overview of our current understanding of electrolyte transport processes in the small and large intestine, their regulation in health and how dysregulation at multiple levels can result in disease. Intestinal electrolyte transport is a balance of ion secretory and ion absorptive processes, all exquisitely dependent on the basolateral Na⁺ /K⁺ ATPase; when this balance goes awry, it can result in diarrhea or in constipation. The key transporters involved in secretion are the apical membrane Cl^- channels and the basolateral Na⁺ -K⁺ -2Cl^- cotransporter, NKCC1 and K⁺ channels. Absorption chiefly involves apical membrane Na⁺ /H⁺ exchangers and Cl^- /HCO₃ ^- exchangers in the small intestine and proximal colon and Na⁺ channels in the distal colon. Key examples of our current understanding of infectious, inflammatory, and genetic diarrheal diseases and of constipation are provided. © 2019 American Physiological Society. Compr Physiol 9:947-1023, 2019.

Increased fecal primary bile acids in multiple myeloma with engraftment syndrome diarrhea after stem cell transplant

Autologous stem cell transplant (ASCT) for multiple myeloma (MM) is associated with diarrhea during the peri-transplant period. We aimed to appraise mechanisms of peri-ASCT diarrhea in a prospective, longitudinal study of patients with MM. We compared by repeated measures (RM)-ANOVA daily bowel movements (BMs) and consistency [7-point Bristol Stool Form Scale (BSFS)], fecal calprotectin (intestinal inflammation), ¹³C-mannitol excretion in urine 0-2 h (small intestinal permeability), fasting serum C4 (bile acid synthesis) and total and primary bile acid in stool samples during baseline, peri-transplant period (Days 5-7 after stem cell infusion), and after hematological recovery post-ASCT. The 12 (5F, 7M) patients' median age was 61 y (IQR 54.8-63.3). All participants reported increased BMs (increase of 2 and 1 per day with and without engraftment syndrome, respectively). There were no significant increases in serum C4, total fecal bile acids, or intestinal permeability. Relative to patients without engraftment syndrome, four participants with engraftment syndrome had looser stool consistency (mean 2.6 points higher BSFS compared to without engraftment syndrome), increased primary fecal bile acids relative to baseline (>33 µmol/L vs. 6 µmol/L without engraftment syndrome), and increased fecal calprotectin compared to baseline (313 μg/mL vs. 35.6 μg/mL without engraftment syndrome; p = 0.06). Engraftment syndrome post-ASCT is associated with increased fecal primary bile acids.

Association of Serum Vitamin D Concentration With Clinical Symptoms and Quality of Life in Patients With Irritable Bowel Syndrome

OBJECTIVE

A high prevalence of vitamin D deficiency (VDD) in gastrointestinal (GI) disorders and the role of vitamin D in the function of the gut have been shown previously. Therefore, we aimed to evaluated the VDD and the possible association of the GI symptoms severity and quality of life (QoL) score with the serum levels of vitamin D in irritable bowel syndrome (IBS).

METHODS

A total of 90 patients with IBS based on Rome III criteria enrolled in the study from the tertiary referral university hospital. In addition, 90 sex- and age-matched healthy controls (HCs) were recruited. To measure the serum levels of 25(OH)D3, blood samples were taken from all the participants. Severity of clinical symptoms, IBS quality of life (IBS-QoL), and IBS symptom severity score (IBSSS) were assessed.

RESULTS

In 66.7% of IBS patients, serum 25(OH)D3 concentrations were <20 ng/mL. The mean serum 25(OH)D3 of IBS patients was statistically (p < 0.05) lower vs. HCs. When different subtypes were analyzed, the serum 25(OH)D3 concentrations in diarrhea-predominant IBS were statistically (p < 0.05) lower as compared to HCs. Furthermore, the lower serum concentrations of 25(OH)D3 were associated (p < 0.05) with higher severity of abdominal pain and distention, flatulence, overall GI symptoms, and IBSSS. However, a direct significant association was seen between IBS-QoL and serum 25(OH)D3.

CONCLUSION

Results of this study showed a high prevalence of VDD in patients with IBS. In addition, VDD was associated with a higher severity of clinical symptoms and lower QoL in IBS.

Clinical evaluation and treatment of chronic bowel symptoms following cancer in the colon and pelvic organs

Background: Chronic gastrointestinal symptoms are common among patients surviving surgery and/or radio-/chemotherapy for cancer in the pelvic organs. However, little is known about the pathophysiology behind symptoms or the effect of treatment. The aim of the present study was to present the results of clinical evaluation and treatment of patients with chronic bowel symptoms after treatment for cancer in the colon or pelvic organs. Material and methods: All patients referred to our department of gastroenterology between May 2016 and June 2018 with chronic bowel symptoms after treatment for cancer in the colon or pelvic organs were prospectively evaluated. Results: In total, 60 patients had been referred. The patients were treated for cancer in the right colon (n = 31), sigmoid colon (n = 1), rectum (n = 14), anal canal (n = 4), cervix uteri (n = 5), corpus uteri (n = 2), ovary (n = 2), and prostate (n = 1). The median time from cancer treatment to referral was 5.5 (range 1-36) years. Symptoms mainly included frequent bowel movements (65%), loose stools (87%), urgency for defecation (57%), and fecal incontinence (50%). A specific cause of bowel dysfunction was found in 48 (80%) of the patients and 21 (35%) had more than one cause of bowel symptoms. Bile acid malabsorption was present in 35 patients and small intestinal bacterial overgrowth was detected in 32. Treatment included bile acid sequestrants (n = 36), antibiotics (n = 33), loperamide (n = 21), and dietary intervention (n = 20). Major improvement in bowel symptoms was reported by 23 (38%) patients, while another 27 (45%) reported some improvement. Conclusion: Most patients with chronic bowel symptoms following cancer in the colon or pelvic organs will benefit from expert clinical evaluation and targeted treatment.

Longitudinal assessment of microbial dysbiosis, fecal unconjugated bile acid concentrations, and disease activity in dogs with steroid-responsive chronic inflammatory enteropathy

Background

Mounting evidence from human studies suggests that bile acid dysmetabolism might play a role in various human chronic gastrointestinal diseases. It is unknown whether fecal bile acid dysmetabolism occurs in dogs with chronic inflammatory enteropathy (CE).

Objective

To assess microbial dysbiosis, fecal unconjugated bile acids (fUBA), and disease activity in dogs with steroid‐responsive CE.

Animals

Twenty‐four healthy control dogs and 23 dogs with steroid‐responsive CE.

Methods

In this retrospective study, fUBA were measured and analyzed. Fecal microbiota were assessed using a dysbiosis index. The canine inflammatory bowel disease activity index was used to evaluate remission of clinical signs. This was a multi‐institutional study where dogs with steroid‐responsive CE were evaluated over time.

Results

The dysbiosis index was increased in dogs with CE (median, 2.5; range, −6.2 to 6.5) at baseline compared with healthy dogs (median, −4.5; range, −6.5 to −2.6; P = .002) but did not change in dogs with CE over time. Secondary fUBA were decreased in dogs with CE (median, 29%; range, 1%‐99%) compared with healthy dogs (median, 88%; 4%‐96%; P = .049). The percent of secondary fUBA in dogs with CE increased from baseline values (median, 28%; range, 1%‐99%) after 2‐3 months of treatment (median, 94%; range, 1%‐99%; P = 0.0183).

Conclusions and Clinical Importance

These findings suggest that corticosteroids regulate fecal bile acids in dogs with CE. Additionally, resolution of clinical activity index in dogs with therapeutically managed CE and bile acid dysmetabolism are likely correlated. However, subclinical disease (i.e., microbial dysbiosis) can persist in dogs with steroid‐responsive CE.

Investigation of the adsorption capacity of the enterosorbent Enterosgel for a range of bacterial toxins, bile acids and pharmaceutical drugs

Oral intestinal adsorbents (enterosorbents) are orally administered materials which pass through the gut where they bind (adsorb) various substances. The enterosorbent Enterosgel (Polymethylsiloxane polyhdrate) is recommended as a symptomatic treatment for acute diarrhoea and chronic diarrhoea associated with irritable bowel syndrome (IBS). Since 1980’s there have been many Enterosgel clinical trials, however, the detailed mechanism of Enterosgel action towards specific toxins and interaction with concomitantly administered medications has not been fully investigated. Our in vitro study assessed the adsorption capacity of Enterosgel for bacterial enterotoxins and endotoxin, bile acids and interaction with the pharmaceutical drugs; Cetirizine and Amitriptyline hydrochloride. Our data demonstrate the good adsorption capacity of Enterosgel for bacterial toxins associated with gastrointestinal infection, with a lower than the comparator charcoal Charcodote capacity for bile acids whose levels can be raised in IBS patients. Adsorption capacity for the two drugs varied but was significantly lower than Charcodote. These findings suggest that the mechanism of Enterosgel action in the treatment of gastrointestinal infection or IBS is adsorption of target molecules followed by removal from the body. This therapy offers a drug free approach to prevention and treatment of infectious and chronic non-infectious diseases, where intestinal flora and endotoxemia play a role.

Canadian Association of Gastroenterology Clinical Practice Guideline for the Management of Irritable Bowel Syndrome (IBS)

BACKGROUND & AIMS

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal (GI) disorders, affecting about 10% of the general population globally. The aim of this consensus was to develop guidelines for the management of IBS.

METHODS

A systematic literature search identified studies on the management of IBS. The quality of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation (GRADE) approach. Statements were developed through an iterative online platform and then finalized and voted on by a multidisciplinary group of clinicians and a patient.

RESULTS

Consensus was reached on 28 of 31 statements. Irritable bowel syndrome is diagnosed based on symptoms; serological testing is suggested to exclude celiac disease, but routine testing for C-reactive protein (CRP), fecal calprotectin or food allergies is not recommended. A trial of a low fermentable oligosaccharides, disaccharides, monosaccharides, polyols (FODMAP) diet is suggested, while a gluten-free diet is not. Psyllium, but not wheat bran, supplementation may help reduce symptoms. Alternative therapies such as peppermint oil and probiotics are suggested, while herbal therapies and acupuncture are not. Cognitive behavioural therapy and hypnotherapy are suggested psychological therapies. Among the suggested or recommended pharmacological therapies are antispasmodics, certain antidepressants, eluxadoline, lubiprostone, and linaclotide. Loperamide, cholestyramine and osmotic laxatives are not recommended for overall IBS symptoms. The nature of the IBS symptoms (diarrhea-predominant or constipation-predominant) should be considered in the choice of pharmacological treatments.

CONCLUSIONS

Patients with IBS may benefit from a multipronged, individualized approach to treatment, including dietary modifications, psychological and pharmacological therapies.

Analysis of Fecal Primary Bile Acids Detects Increased Stool Weight and Colonic Transit in Patients With Chronic Functional Diarrhea

BACKGROUND & AIMS

Patients with bile acid diarrhea (BAD) are identified based on increased levels of BAs in fecal samples collected over a 48-hr period while on a 100-gram fat diet (48-hr BA), retention of 75Se-labeled homocholic acid taurine, or serum levels of C4 or FGF19. BAD increases fecal weight and colonic transit. We investigated whether results of tests for BAD associate with increased fecal weight and more rapid colonic transit over a 24- or 48-hr period in patients with irritable bowel syndrome with diarrhea (IBS-D). We also estimated the prevalence of increased 48-hr fecal BAs in patients with chronic diarrhea.

METHODS

We performed a retrospective study of 64 patients with IBS-D, 30 patients with IBS-constipation, 30 healthy volunteers (controls). We collected data on fecal weights (measured over a 48-hr period), colonic transit over a 24-hr period (measured by scintigraphy), and percentages of different BAs in stool samples. Colonic transit was measured as the geometric center (weighted average) of colonic counts on a scale of 1 (100% in ascending colon) to 5 (100% in stool). We performed area under the curve (AUC) analyses to assess the association between result of serum and stool tests and high fecal weight (>400g/48 hrs) or rapid colonic transit (>3.34, corresponding to isotope geometric center in sigmoid colon). We estimated the prevalence of increased 48-hr fecal BAs among 938 patients with chronic diarrhea.

RESULTS

Total fecal 48-hr BA alone, or in combination with percentage of primary fecal BAs, identified patients with increased fecal weight with an AUROC of 0.86. Percentage of primary fecal BA alone identified patients with increased fecal weight with an AUROC of 0.73. Total fecal 48-hr BA alone identified patients with increased colonic transit with an AUROC of 0.65 and percentage of primary fecal BA alone identified patients with increased colonic transit with an AUROC of 0.69; combined data on these features identified patients with increased colonic transit with an AUROC of 0.70. Serum level of C4 identified patients with increased colonic transit with an AUROC of 0.60. Primary BAs >10% identified patients with increased fecal weight (sensitivity 49% and specificity 91%) and rapid colonic transit (sensitivity 48% and specificity 87%). Among the patients with chronic diarrhea, 45.6% had fecal primary BAs >10% and 27% had increased total fecal BAs (>2337 μmol/48 hrs).

CONCLUSIONS

In a retrospective analysis of patients with IBS-D, we found percentage of primary BAs in fecal samples to provide an alternative to total fecal BAs in identification of patients with BAD or chronic diarrhea.

Aquaporin Expression in Colonic Mucosal Biopsies From Irritable Bowel Syndrome With Diarrhea

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-PCR assays, with expression calculated using 2-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.

Personalized medicine in functional gastrointestinal disorders: Understanding pathogenesis to increase diagnostic and treatment efficacy

There is overwhelming evidence that functional gastrointestinal disorders (FGIDs) are associated with specific mechanisms that constitute important targets for personalized treatment. There are specific mechanisms in patients presenting with functional upper gastrointestinal symptoms (UGI Sx). Among patients with UGI Sx, approximately equal proportions (25%) of patients have delayed gastric emptying (GE), reduced gastric accommodation (GA), both impaired GE and GA, or neither, presumably due to increased gastric or duodenal sensitivity. Treatments targeted to the underlying pathophysiology utilize prokinetics, gastric relaxants, or central neuromodulators. Similarly, specific mechanisms in patients presenting with functional lower gastrointestinal symptoms, especially with diarrhea or constipation, are recognized, including at least 30% of patients with functional constipation pelvic floor dyssynergia and 5% has colonic inertia (with neural or interstitial cells of Cajal loss in myenteric plexus); 25% of patients with diarrhea-predominant irritable bowel syndrome (IBSD) has evidence of bile acid diarrhea; and, depending on ethnicity, a varying proportion of patients has disaccharidase deficiency, and less often sucrose-isomaltase deficiency. Among patients with predominant pain or bloating, the role of fermentable oligosaccharides, disaccharides, monosaccharides and polyols should be considered. Personalization is applied through pharmacogenomics related to drug pharmacokinetics, specifically the role of CYP2D6, 2C19 and 3A4 in the use of drugs for treatment of patients with FGIDs. Single mutations or multiple genetic variants are relatively rare, with limited impact to date on the understanding or treatment of FGIDs. The role of mucosal gene expression in FGIDs, particularly in IBS-D, is the subject of ongoing research. In summary, the time for personalization of FGIDs, based on deep phenotyping, is here; pharmacogenomics is relevant in the use of central neuromodulators. There is still unclear impact of the role of genetics in the management of FGIDs.

Nutritional and vitamin status in patients with neuroendocrine neoplasms

Symptoms of gastroenteropancreatic located neuroendocrine neoplasms (GEP-NENs) are often related to food intake and manifest as abdominal pain or diarrhoea which can influence patients nutritional status. Malnutrition is common in cancer patients and influences quality of life, treatment options and survival but is also present in up to 40% of patients with GEP-NENs. As part of malnutrition there are often deficiencies in fat-soluble vitamins, mainly vitamin D. Little knowledge exists on trace elements. Several factors influence the development of malnutrition such as size and localisation of the primary tumour as well as metastases, side effects from treatment but also hormone production of the tumour itself. One of the main influencing factors leading to malnutrition is diarrhoea which leads to dehydration and electrolyte disturbances. Treatment of diarrhoea should be guided by its cause. Screening for malnutrition should be part of routine care in every GEP-NEN patient. Multidisciplinary treatment including dietician support is necessary for all malnourished patients with GEP-NENs.

Bile and fat excretion are biomarkers of clinically significant diarrhoea and constipation in irritable bowel syndrome

BACKGROUND

Biomarkers 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.

AIM

To 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.

METHODS

We 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.

RESULTS

Among 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.

CONCLUSIONS

Faecal bile acids and faecal fat are cost-effective and accurate biomarkers associated with significant bowel dysfunction among IBS-D and IBS-C patients.

75Se-Homocholic acid taurine scintigraphy (75SeHCAT®), a standard benchmark test in bile acid malabsorption?

Chronic diarrhoea due to bile acid malabsorption (BAM) is an underdiagnosed pathology. Different diagnostic tools are available. However, there is currently no consensus on which of these would be the benchmark test or gold standard. This review evaluates the possibility of using ⁷⁵Se-taurocholic acid (⁷⁵SeHCAT^®) scintigraphy as a benchmark diagnostic test and its perspective for the future. A literature review was conducted in Pubmed and OVID obtaining a total of 57 papers, 26 of which were finally used after being selected under the concepts of gold standard, diagnostic accuracy and other biomarkers. We evaluated the advantages and disadvantages of the different diagnostic tools: ¹⁴C-glycocholate, measurement of bile acids in faeces, C4 in serum, FGF19 in serum, cholestyramine, and ⁷⁵Se-tauroselcolic acid scintigraphy. We consider that the ⁷⁵SeHCAT^® scan is the most recommended diagnostic test in Europe for diagnosing BAM as it presents the highest values of sensitivity and specificity. It has a significant cost-benefit ratio, making it the test with the highest degree of recommendation. However, it is still not possible to use it in a recognised way as a gold standard due to the lack of studies that provide conclusive data that allow consensus. In the meantime, the combined use of cholestyramine testing in all patients we want to evaluate, regardless of the scintigraphy result, could be encouraged as a benchmark standard.

Systematic review with meta-analysis: the prevalence of bile acid malabsorption and response to colestyramine in patients with chronic watery diarrhoea and previous cholecystectomy

BACKGROUND

A limited number of small-sized studies suggest that bile acid diarrhoea is frequent in patients with chronic watery diarrhoea and previous cholecystectomy.

AIM

To perform a systematic review and meta-analysis to assess the prevalence of bile acid diarrhoea in patients with chronic watery diarrhoea and previous cholecystectomy, and their response to colestyramine, including a new consecutive series of patients.

METHODS

MEDLINE and EMBASE were searched up to January 2018. Selected studies included patients with previous cholecystectomy and chronic watery diarrhoea assessed by the 23-seleno-25-homotaurocholic acid (SeHCAT) test. We calculated the pooled rate of bile acid diarrhoea using the inverse double arcsine square root method. Additionally, the medical records of 291 consecutive patients with chronic watery diarrhoea in whom a SeHCAT test was performed were retrospectively reviewed and 74 with previous cholecystectomy were included in the meta-analysis.

RESULTS

The search strategy identified eight relevant studies, which, together with the data of the present series, comprise 361 individuals. The pooled bile acid diarrhoea rate was 70% (95% CI 56%-82%), and was similar when using cut-offs of 10% or 15%. There was substantial heterogeneity (I²  = 84%). Five studies comprising 166 patients evaluated the effect of colestyramine in patients with bile acid diarrhoea. The pooled colestyramine response rate was 79% (95% CI 63%-91%) with substantial heterogeneity (I²  = 73%).

CONCLUSIONS

Two-thirds of patients with chronic watery diarrhoea and previous cholecystectomy have bile acid diarrhoea. Response to colestyramine in these patients is good.

Non-alcoholic fatty liver disease is associated with dysregulated bile acid synthesis and diarrhea: A prospective observational study

Background

Non-alcoholic fatty liver disease (NAFLD) may be associated with changes in bile acid (BA) metabolism. Hepatic BA production, measured by serum levels of the precursor 7α-hydroxy-4-cholesten-3-one (C4), is regulated by the farnesoid-X-receptor (FXR)-dependent ileal hormone fibroblast growth factor 19 (FGF19). Low FGF19 and high C4 are features of chronic BA diarrhea. Obeticholic acid, an FXR agonist, stimulates FGF19 and has shown therapeutic potential in both BA diarrhea and in NAFLD. We hypothesized there are associations of FGF19, C4 and BA diarrhea with NAFLD.

Methods and findings

127 patients with known NAFLD were recruited prospectively. Clinical features, including metformin use, markers of NAFLD severity and BA synthesis were analyzed. The overall incidence of chronic diarrhea was 25%, with features of BA diarrhea in 12%. FGF19 negatively correlated with C4 (r_s = -0.43, p = 0.001) and with alanine aminotransferase (r_s = -0.22, p = 0.03), but not with either NAFLD fibrosis or Fibroscan scores. High C4 was associated with a higher NAFLD fibrosis score (p < 0.05), and with diarrhea (p = 0.001). The median NAFLD fibrosis score was higher in those with diarrhea (p = 0.002). Metformin use, in 44% overall, was particularly associated with diarrhea (in 36% vs 17%, p = 0.02), and a lower median FGF19 (74 vs 105 pg/mL, p < 0.05).

Conclusions

Increased hepatic BA production and diarrhea, but not low FGF19, were associated with increased NAFLD fibrosis score, indicating dysregulation of the FXR-FGF19 axis and suggesting hepatic FGF19 resistance. Metformin use was an important factor in a subgroup, lowering FGF19, and resulting in bile acid diarrhea.

Irritable Bowel Syndrome: What Treatments Really Work

Irritable bowel syndrome (IBS) is present in patients with symptoms of chronic abdominal pain and altered bowel habits but no identifiable organic etiology. Rome IV classification groups patients based on predominant stool pattern. Low-FODMAP diets have been helpful in providing symptom relief, as have cognitive behavioral and mind-body techniques that help patients manage symptoms. Targeted symptomatic relief for the patient's predominant symptoms provides relief in addition to effective older medications that are inexpensive and reliable. Newer treatments for IBS-D, such as eluxadoline, and IBS-C, with linaclotide, lubiprostone, plecanatide, also can provide durable relief.

What is the cost of delayed diagnosis of bile acid malabsorption and bile acid diarrhoea?

INTRODUCTION

⁷⁵Selenium taurocholic acid (SeHCAT) scanning diagnoses bile acid malabsorption/bile acid diarrhoea (BAM/BAD) and defines optimal treatment. Approximately 2% of the population have BAM/BAD.

AIM

To evaluate the cost of delayed diagnosis of BAM/BAD.

METHODS

Patients' notes who underwent SeHCAT scanning in three hospitals over a 1-year period were reviewed retrospectively. Scan results and treatment response were recorded. Package-of-care costs were calculated using costing tools from the National Institute for Health and Care Excellence and from United Lincolnshire Hospitals Trust business unit.

RESULTS

Between June 2016 and May 2017, 19 men and 37 women (median age 58 (range 19-83)) of 3860 new patients seen in gastroenterology clinics were referred for SeHCAT scanning. Sixty-four per cent of scans were abnormal: 13 demonstrated severe (<5% 7-day SeHCAT retention), 13 moderate (5%-10%), 5 mild (10%-15%) and 5 borderline (15%-20%) BAD/BAM. Likely causes included primary BAD (n=16), cholecystectomy (n=13), inflammatory bowel disease (n=4) and other (n=3). If SeHCAT scanning was ordered at first consultation (n=11), patients reported 24 months (median) of symptoms (range 6-360) and the median diagnostic package-of-care cost was £811.40 (95% CI £625.59 to £1508.20). If SeHCAT scanning was booked later (n=25), patients reported symptoms for 30 months (median, range 0.5-360) and the cost was £1568.31 (95% CI £1200.55 to £1713.18). Following diagnosis, treatment led to symptom improvement (n=24), no change/deterioration (n=3) and not reported (n=9).

CONCLUSIONS

SeHCAT is underused. Late diagnosis leads to unnecessary demands for other services and treatment delay. Early diagnosis achieves health benefits while reducing costs.

Rome Foundation Working Team Report on Post-Infection Irritable Bowel Syndrome

BACKGROUND & AIMS

The existence of postinfection irritable bowel syndrome (PI-IBS) has been substantiated by epidemiology studies conducted in diverse geographic and clinical settings. However, the available evidence has not been well summarized, and there is little guidance for diagnosis and treatment of PI-IBS. The ROME Foundation has produced a working team report to summarize the available evidence on the pathophysiology of PI-IBS and provide guidance for diagnosis and treatment, based on findings reported in the literature and clinical experience.

METHODS

The working team conducted an evidence-based review of publication databases for articles describing the clinical features (diagnosis), pathophysiology (intestinal sensorimotor function, microbiota, immune dysregulation, barrier dysfunction, enteroendocrine pathways, and genetics), and animal models of PI-IBS. We used a Delphi-based consensus system to create guidelines for management of PI-IBS and a developed treatment algorithm based on published findings and experiences of team members.

RESULTS

PI-IBS develops in about 10% of patients with infectious enteritis. Risk factors include female sex, younger age, psychological distress during or before acute gastroenteritis, and severity of the acute episode. The pathogenesis of PI-PBS appears to involve changes in the intestinal microbiome as well as epithelial, serotonergic, and immune system factors. However, these mechanisms are incompletely understood. There are no evidence-based, effective pharmacologic strategies for treatment of PI-IBS. We provide a consensus-based treatment algorithm, based on clinical presentation and potential disease mechanisms.

CONCLUSIONS

Based on a systematic review of the literature and team experience, we summarize the clinical features, pathophysiology (from animal models and human studies), and progression of PI-IBS. Based on these findings, we present an algorithm for diagnosis and treatment of PI-IBS based on team consensus. We also propose areas for future investigation.

Pros and Cons of the SeHCAT Test in Bile Acid Diarrhea: A More Appropriate Use of an Old Nuclear Medicine Technique

Bile acid malabsorption (BAM) causing chronic diarrhea may be due to organic as well as functional disorders, and some of them were included under the general label of diarrheic-type irritable bowel syndrome (IBS-D). The 75-selenium homocholic acid taurine (SeHCAT) test is a nuclear medicine investigation considered to be the gold standard for the diagnosis of bile acid malabsorption (BAM). Many studies demonstrate that it could be effective in the clinical workout of chronic diarrhea due to different conditions. The SeHCAT test provides a quantitative assessment to estimate the severity of BAM and the possible response to therapy with bile acid sequestrants (BASs). However, there is no general agreement regarding its cutoff value and the test is not widely available. The aim of this review is to discuss the advantages and disadvantages of the SeHCAT test in clinical practice.

Guts and Gall: Bile Acids in Regulation of Intestinal Epithelial Function in Health and Disease

Epithelial cells line the entire surface of the gastrointestinal tract and its accessory organs where they primarily function in transporting digestive enzymes, nutrients, electrolytes, and fluid to and from the luminal contents. At the same time, epithelial cells are responsible for forming a physical and biochemical barrier that prevents the entry into the body of harmful agents, such as bacteria and their toxins. Dysregulation of epithelial transport and barrier function is associated with the pathogenesis of a number of conditions throughout the intestine, such as inflammatory bowel disease, chronic diarrhea, pancreatitis, reflux esophagitis, and cancer. Driven by discovery of specific receptors on intestinal epithelial cells, new insights into mechanisms that control their synthesis and enterohepatic circulation, and a growing appreciation of their roles as bioactive bacterial metabolites, bile acids are currently receiving a great deal of interest as critical regulators of epithelial function in health and disease. This review aims to summarize recent advances in this field and to highlight how bile acids are now emerging as exciting new targets for disease intervention.

Elobixibat for the treatment of constipation

INTRODUCTION

Chronic idiopathic constipation (CC) is highly prevalent worldwide. A subset of patients with CC have reduced fecal (and by inference, intra-colonic) bile acids (BA). Elobixibat, a locally-acting ileal bile acid transporter (IBAT) inhibitor, leads to increased BA delivery to the colon and represents a new class of treatment for CC. BAs accelerate colonic transit and increase colonic secretion. Therefore, IBAT inhibitors have potential to treat patients with CC. Areas covered: Rationale for IBAT inhibitor in therapeutics, and preclinical and clinical pharmacology of elobixibat: In vitro, elobixibat is a highly potent, selective IBAT inhibitor. In humans, elobixibat accelerated colonic transit. In phase 2A, 2B and 3 studies in CC, elobixibat was efficacious, well tolerated and safe. An open-label, phase 3 trial (52 weeks) confirmed the safety of elobixibat. Elobixibat reduces LDL cholesterol, increases serum GLP-1, and has potential in metabolic syndrome. Expert commentary: Uniquely among current treatments of CC, elobixibat stimulates both motor and secretory functions in the colon. These dual effects suggest that, when approved, elobixibat may be a first-line choice for constipation associated with colonic BA deficiency and a second-line treatment for all patients with CC and constipation-predominant irritable bowel syndrome. Further studies are required to confirm efficacy for relief of CC. Once approved, elobixibat will likely become a second-line choice for treatment of CC.

Review article: an analysis of safety profiles of treatments for diarrhoea-predominant irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is multifactorial in nature, and a wide range of therapies is available to manage symptoms of this common disorder.

AIM

To provide an overview of the safety of interventions that may be used to manage patients with diarrhoea-predominant IBS (IBS-D).

METHODS

Medline and Embase database searches (through 02 May 2018) to identify clinical studies that evaluated treatment safety and/or efficacy in adults with IBS-D.

RESULTS

IBS-D treatments include dietary modification, probiotics, serotonin receptor antagonists, opioid receptor agonists and antagonists, nonsystemic antibiotics, bile acid sequestrants, antidepressants, and complementary and alternative therapies. These treatments vary in administration frequency (eg, daily; short-course therapy) and target various pathophysiologic factors. Safety profiles vary considerably by treatment among IBS-D therapies. The number needed to harm (defined as the number of patients treated to encounter an adverse event) was lowest (worse) for antidepressants (8.5) and highest (best) for probiotics (35), and the number needed to harm (defined as the number of patients who discontinued due to an adverse event) was lowest for tricyclic antidepressants (9) and highest for rifaximin (8971). Notable safety concerns with IBS-D treatments include pancreatitis with eluxadoline, ischaemic colitis and serious complications of constipation with alosetron, and cardiac adverse events with loperamide and tricyclic antidepressants. Treatment decisions need to account for medication risks and adverse events for each patient.

CONCLUSIONS

Multiple treatment options are now available for patients with IBS-D. However, the safety profiles of these agents vary widely by number needed to harm value. Providers should consider both safety and efficacy of a specific intervention when determining how best to manage patients' IBS-D symptoms.

Ileal Bile Acid Transporter Inhibition for the Treatment of Chronic Constipation, Cholestatic Pruritus, and NASH

Bile acids are synthesized from cholesterol in the liver, excreted with bile into the duodenum, almost completely taken up again in the distal ileum and finally returned to the liver with portal blood in a process termed enterohepatic circulation. Bile acid synthesis, excretion, and reuptake are tightly regulated. The apical sodium-dependent bile acid transporter [ASBT; also known as ileal bile acid transporter (IBAT) and SLC10A2] is pivotal for the almost complete reabsorption of conjugated bile acids in the ileum. Dysfunctional IBAT may be the cause of bile acid diarrhea. Pharmacological IBAT inhibition results in an increased bile acid load in the colon and subsequently a lower bile acid pool, which is associated with improved liver histology in animal models of cholestatic liver disease and non-alcoholic steatohepatitis (NASH). In humans, IBAT inhibitors have been tested in clinical trials with widely different indications: in patients with idiopathic chronic constipation, an increased number of bowel movements was observed. In adult and pediatric cholestatic liver diseases with pruritus, various IBAT inhibitors showed potential to improve itching. Adverse events of IBAT inhibitors, based on their mode of action, are abdominal pain and diarrhea which might patients to withdraw from study medications. So far, no data are available of a study of IBAT inhibitors in patients with NASH. In this review we summarize the preclinical and most recent clinical studies with various IBAT inhibitors and discuss the difficulties that should be addressed in future studies.

Guidelines for the investigation of chronic diarrhoea in adults: British Society of Gastroenterology, 3rd edition

Chronic diarrhoea is a common problem, hence clear guidance on investigations is required. This is an updated guideline from 2003 for the investigations of chronic diarrhoea commissioned by the Clinical Services and Standards Committee of the British Society of Gastroenterology (BSG). This document has undergone significant revision in content through input by 13 members of the Guideline Development Group (GDG) representing various institutions. The GRADE system was used to appraise the quality of evidence and grading of recommendations.

Impact of gastrointestinal disease states on oral drug absorption – implications for formulation design – a PEARRL review

Objectives

Drug product performance in patients with gastrointestinal (GI) diseases can be altered compared to healthy subjects due to pathophysiological changes. In this review, relevant differences in patients with inflammatory bowel diseases, coeliac disease, irritable bowel syndrome and short bowel syndrome are discussed and possible in vitro and in silico tools to predict drug product performance in this patient population are assessed.

Key findings

Drug product performance was altered in patients with GI diseases compared to healthy subjects, as assessed in a limited number of studies for some drugs. Underlying causes can be observed pathophysiological alterations such as the differences in GI transit time, the composition of the GI fluids and GI permeability. Additionally, alterations in the abundance of metabolising enzymes and transporter systems were observed. The effect of the GI diseases on each parameter is not always evident as it may depend on the location and the state of the disease. The impact of the pathophysiological change on drug bioavailability depends on the physicochemical characteristics of the drug, the pharmaceutical formulation and drug metabolism. In vitro and in silico methods to predict drug product performance in patients with GI diseases are currently limited but could be a useful tool to improve drug therapy.

Summary

Development of suitable in vitro dissolution and in silico models for patients with GI diseases can improve their drug therapy. The likeliness of the models to provide accurate predictions depends on the knowledge of pathophysiological alterations, and thus, further assessment of physiological differences is essential.

Long-term effect of medical treatment of diarrhoea in 377 patients with SeHCAT scan diagnosed bile acid malabsorption from 2003 to 2016; a retrospective study

BACKGROUND

Excessive amounts of bile acids entering the colon due to bile acid malabsorption cause chronic bile acid diarrhoea. Diagnosis is possible by measuring the retention fraction of orally ingested ⁷⁵ Selenium homotaurocholic acid (SeHCAT). The knowledge of long-term effects of medical treatment is sparse.

AIM

To describe diarrhoea, adherence to treatment, treatment effects and quality of life in a large, well-defined cohort of patients with bile acid diarrhoea.

METHODS

A retrospective survey was performed among 594 patients with bile acid malabsorption verified by SeHCAT scans at our unit between 2003 and 2016. Questionnaires about medical history, diarrhoea, use of medication, and quality of life scores were mailed to all patients.

RESULTS

Among 594 patients 377 (69%) responded. Among respondents, 121 (32%) had bile acid diarrhoea due to ileal disease or resection (type 1), 198 (52%) idiopathic bile acid diarrhoea (type 2) and 58 (16%) bile acid diarrhoea due to other non-ileal disease, mainly cholecystectomy (type 3). At follow-up, half of the patients, 184 (50%), reported improvement of diarrhoea. However, 273 patients (74%) still reported diarrhoea and 234 (62%) regularly used anti-diarrhoeal medication. In spite of treatment, 235 (64%) considered reduced quality of life by diarrhoea and 184 (50%) reported that diarrhoea was unaltered or worse than before established diagnosis.

CONCLUSION

Many patients with bile acid diarrhoea continue to have bothersome diarrhoea in spite of correct diagnosis and treatment.