Pathophysiology and Clinical Management of Bile Acid Diarrhea

Efficacy of Bile Acid Sequestrants in the Treatment of Bile Acid Diarrhea: A Meta-Analysis of Randomized Controlled Trials

Bile acid sequestrants (BASs) have often been used for bile acid diarrhea (BAD) but carry a high risk of adverse events. New generations of BASs show promising results; however, their efficacy remains unclear. This systematic review and meta-analysis was conducted using PubMed, Cochrane, and Embase to assess randomized controlled trials (RCTs) published up to November 2023 to retrieve studies that measured the parameters before and after the administration of BASs. The outcomes assessed were cessation or improvement in diarrhea, fecal consistency, abdominal cramping, frequency of diarrhea, and adverse events. Risk ratios (RRs) and mean differences with 95% confidence intervals (CIs) were pooled using a random-effects model. Statistical analyses were conducted using RStudio version 4.1.2. The protocol was prospectively registered with PROSPERO (CRD42023445444). Seven RCTs with a total of 311 patients were included, of which 168 (54%) were randomized to BASs. Among BAS-treated patients, 101 (60.1%) received colesevelam, 40 (23.8%) received chenodeoxycholate, 18 (10.7%) received cholestyramine, and 9 (5.3%) received colestid. BASs were associated with a significant improvement in the cessation of diarrhea (RR 3.27; 95% CI 2.08 to 5.15; P ≤  .05) and liquid stool to normal fecal consistency (RR 2.69; 95% CI 1.56 to 4.65; P ≤  .05), as well as an increase in abdominal cramps (RR 5.27; 95% CI 1.21 to 22.93; P ≤  .05). There were no differences in urgency, adverse events, or nausea between groups. These findings indicate that BASs are effective in the treatment of BAD, as indicated by the improvement or cessation of diarrhea episodes.

High throughput bioanalysis of serum 7a-hydroxy-4-cholesten-3-one (C4) using LC-MS/MS: Devising an end-to-end single vial solution for a sample limited application

Crohn's disease (CD) is characterized by chronic ileal/ileocolonic inflammation, and in some cases, can result in bile acid malabsorption (BAM) and subsequent bile acid diarrhea (BAD). Although BAD is common in CD, diagnosis is difficult. In patients with CD who had ileal resection (IR), elevated serum 7a-hydroxy-4-cholesten-3-one (C4), a cholesterol-derived stable intermediate in bile acid synthesis, is associated with diarrhea attributable to BAM and therefore, may have diagnostic utility. The previously existing validated methodology to measure C4 in human serum required 100 μL with an analytical range of 0.5-100 ng/mL, making it incompatible with the clinical trial sample set we had available for analysis due to limited serum volume and an extended assay range requirement (up-to 1 μg/mL). We present here a simplified, end-to-end single vial approach performed in a 96-well format for clinical sample C4 analysis for application in sample limited settings.

Towards routine high-throughput analysis of fecal bile acids: validation of an enzymatic cycling method for the quantification of total bile acids in human stool samples on fully automated clinical chemistry analyzers

OBJECTIVES

Bile acid diarrhea is a common but underdiagnosed condition. Because the gold standard test (75SeHCAT) is time-consuming and not widely available, fecal bile acid excretion is typically assessed by chromatography and mass spectrometry. Although enzymatic cycling assays are well established for the rapid and cost-effective analysis of total bile acids (TBA) in serum or plasma, their full potential has yet not been extended to stool samples in clinical routine.

METHODS

The performance of the 'Total bile acids 21 FS' reagent (DiaSys) was evaluated in fecal matrix according to CLSI guidelines and EU-IVD Regulations (2017/745), and compared to an established microplate-based kit (IDK®) by measuring patient stool samples (n=122). Method agreement was assessed by Passing-Bablok and Bland-Altman analysis. The quantification of eight individual BAs was assessed using HPLC-MS/MS as reference method.

RESULTS

The DiaSys assay showed linearity between 3.5 and 130 μmol/L, good repeatability, total precision, and reproducibility with CVs of 1.7 %, 3.5 %, and 3.0 %. Limit of blank (LoB), detection (LoD), and quantitation (LoQ) were ≤0.17, ≤0.3, and 3.5 μmol/L, respectively. No significant interference from endogenous substances was observed. The methods showed good correlation up to 140 μmol/L (r=0.988), despite differences in the quantification of individual BAs, with mean deviations of 7 % (DiaSys) and 31 % (IDK®), respectively.

CONCLUSIONS

The advantages of enzymatic TBA analysis on fully automated clinical chemistry platforms can be exploited for the routine analysis of stool samples. However, cycling assays may benefit from reference standards that take into account the composition of the fecal BA pool.

Microbiota modulation in disorders of gut-brain interaction

Disorders of gut-brain interaction (DGBI) are common chronic conditions characterized by persistent and recurring gastrointestinal symptoms triggered by several pathophysiological factors, including an altered gut microbiota. The most common DGBI are irritable bowel syndrome (IBS), functional constipation (FC) and functional dyspepsia (FD). Recently, a deep understanding of the role of the gut microbiota in these diseases was possible due to multi-omics methods capable to provide a comprehensive assessment. Most of the therapies recommended for these patients, can modulate the gut microbiota such as diet, prebiotics, probiotics and non-absorbable antibiotics, which were shown to be safe and effective. Since patients complain symptoms after food ingestion, diet represents the first line therapeutic approach. Avoiding dietary fat and fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, and increasing the number of soluble fibers represent the therapeutic choices for FD, IBS and FC respectively. Probiotics, as a category, have been employed with good results in all the abovementioned DGBI. Rifaximin has been shown to be useful in the context of bowel related disorders, although a recent trial showed positive results for FD. Fecal microbiota transplantation has been tested for IBS and FC with promising results. In this review, we will briefly summarize the current understanding on dysbiosis and discuss microbiota modulation strategies to treat patients with DGBI.

Advances in the pathophysiology, diagnosis and management of chronic diarrhoea from bile acid malabsorption: a systematic review

Bile acid malabsorption (BAM) is an important disorder of digestive pathophysiology as it generates chronic diarrhoea. This condition originates from intricate pathways involving bile acid synthesis and metabolism in the liver and gut, the composition of gut microbiota, enterohepatic circulation and key receptors as farnesoid X receptor (FXR), fibroblast growth factor receptor 4 (FGFR4), and the G-protein bile acid receptor-1 (GPBAR-1). Although symptoms can resemble those related to disorders of gut brain interaction, accurate diagnosis of BAM may greatly benefit the patient. The empiric diagnosis of BAM is primarily based on the clinical response to bile acid sequestrants. Specific tests including the 48-hour fecal bile acid test, serum levels of 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor 19 (FGF19), and the 75Selenium HomotauroCholic Acid Test (SeHCAT) are not widely available. Nevertheless, lack of diagnostic standardization of BAM may account for poor recognition and delayed management. Beyond bile acid sequestrants, therapeutic approaches include the use of FXR agonists, FGF19 analogues, glucagon-like peptide-1 (GLP-1) receptor agonists, and microbiota modulation. These novel agents can best make their foray into the therapeutic armamentarium if BAM does not remain a diagnosis of exclusion. Ignoring BAM as a specific condition may continue to contribute to increased healthcare costs and reduced quality of life. Here, we aim to provide a comprehensive review of the pathophysiology, diagnosis, and management of BAM.

Gut microbiota and intestinal immunity-A crosstalk in irritable bowel syndrome

Irritable bowel syndrome (IBS), one of the most prevalent functional gastrointestinal disorders, is characterized by recurrent abdominal pain and abnormal defecation habits, resulting in a severe healthcare burden worldwide. The pathophysiological mechanisms of IBS are multi-factorially involved, including food antigens, visceral hypersensitivity reactions, and the brain-gut axis. Numerous studies have found that gut microbiota and intestinal mucosal immunity play an important role in the development of IBS in crosstalk with multiple mechanisms. Therefore, based on existing evidence, this paper elaborates that the damage and activation of intestinal mucosal immunity and the disturbance of gut microbiota are closely related to the progression of IBS. Combined with the application prospect, it also provides references for further in-depth exploration and clinical practice.

Epithelial Na + Channels Function as Extracellular Sensors

The epithelial Na + channel (ENaC) resides on the apical surfaces of specific epithelia in vertebrates and plays a critical role in extracellular fluid homeostasis. Evidence that ENaC senses the external environment emerged well before the molecular identity of the channel was reported three decades ago. This article discusses progress toward elucidating the mechanisms through which specific external factors regulate ENaC function, highlighting insights gained from structural studies of ENaC and related family members. It also reviews our understanding of the role of ENaC regulation by the extracellular environment in physiology and disease. After familiarizing the reader with the channel's physiological roles and structure, we describe the central role protein allostery plays in ENaC's sensitivity to the external environment. We then discuss each of the extracellular factors that directly regulate the channel: proteases, cations and anions, shear stress, and other regulators specific to particular extracellular compartments. For each regulator, we discuss the initial observations that led to discovery, studies investigating molecular mechanism, and the physiological and pathophysiological implications of regulation. © 2024 American Physiological Society. Compr Physiol 14:5407-5447, 2024.

Diseases of bile duct in children

Several diseases originate from bile duct pathology. Despite studies on these diseases, certain etiologies of some of them still cannot be concluded. The most common disease of the bile duct in newborns is biliary atresia, whose prognosis varies according to the age of surgical correction. Other diseases such as Alagille syndrome, inspissated bile duct syndrome, and choledochal cysts are also time-sensitive because they can cause severe liver damage due to obstruction. The majority of these diseases present with cholestatic jaundice in the newborn or infant period, which is quite difficult to differentiate regarding clinical acumen and initial investigations. Intraoperative cholangiography is potentially necessary to make an accurate diagnosis, and further treatment will be performed synchronously or planned as findings suggest. This article provides a concise review of bile duct diseases, with interesting cases.

Journal of Clinical Gastroenterology Lectureship Dubai 2022 : Management of Irritable Bowel Syndrome With Diarrhea

Irritable bowel syndrome (IBS) with diarrhea (IBS-D) affects ~1% of the general population and is characterized by abdominal pain associated with diarrhea. IBS-D symptoms significantly impact the quality of life of patients. Major uncertainties remain regarding the optimal management of these patients. Several therapies have been investigated over the years for the treatment of IBS-D. In the initial management, commonly prescribed approaches with an effect on global IBS symptoms include a low Fermentable Oligo-, Di-, Mono-Saccharides and Polyols diet and probiotics, while antispasmodics are used for targeting abdominal pain and loperamide for diarrhea only. Additional therapeutic options for the relief of global IBS symptoms include rifaximin, 5-HT 3 antagonists, gut-directed psychological therapies, and eluxadoline, while tricyclic antidepressants can target abdominal pain and bile acid sequestrants diarrhea. Promising evidence exists for the use of mesalazine and fecal microbiota transplantation in IBS-D, although further evidence is needed for definitive conclusions regarding their efficacy.

Bile Acid Diarrhea: From Molecular Mechanisms to Clinical Diagnosis and Treatment in the Era of Precision Medicine

Bile acid diarrhea (BAD) is a multifaceted intestinal disorder involving intricate molecular mechanisms, including farnesoid X receptor (FXR), fibroblast growth factor receptor 4 (FGFR4), and Takeda G protein-coupled receptor 5 (TGR5). Current diagnostic methods encompass bile acid sequestrants (BAS), 48-h fecal bile acid tests, serum 7α-hydroxy-4-cholesten-3-one (C4), fibroblast growth factor 19 (FGF19) testing, and 75Selenium HomotauroCholic acid test (75SeHCAT). Treatment primarily involves BAS and FXR agonists. However, due to the limited sensitivity and specificity of current diagnostic methods, as well as suboptimal treatment efficacy and the presence of side effects, there is an urgent need to establish new diagnostic and treatment methods. While prior literature has summarized various diagnostic and treatment methods and the pathogenesis of BAD, no previous work has linked the two. This review offers a molecular perspective on the clinical diagnosis and treatment of BAD, with a focus on FXR, FGFR4, and TGR5, emphasizing the potential for identifying additional molecular mechanisms as treatment targets and bridging the gap between diagnostic and treatment methods and molecular mechanisms for a novel approach to the clinical management of BAD.

A case for screening real-world data for collateral drug benefits: Glucagon-like peptide 1 receptor agonists and bile acid diarrhea

PURPOSE

Collateral drug benefits are hitherto unknown beneficial effects that might lead to repurposing of already marketed drugs. A randomized controlled trial has found liraglutide to be non-inferior to colesevelam in reducing bile acid diarrhea. We hypothesized that this collateral drug benefit of liraglutide could have been detected using observational data.

METHODS

We performed a sequence symmetry analysis (SSA). In the SSA, we indexed individuals on the date of the first prescription of GLP1-RA and restricted the analysis to all individuals who had a first prescription of bile acid sequestrants between 365 days prior to until 365 days after the index date. Sequence ratios (SR), that is, the ratio between counts of persons initiating GLP1-RA first versus last, were calculated, and 95% confidence intervals were obtained. We adjusted for prescribing trends using null-effect SR adjustment.

RESULTS

We included 158 individuals, with a median age of 58 years. The trend-adjusted SR was 0.96 (95% confidence interval 0.70-1.31). When stratifying on the type of GLP1-RA (liraglutide or semaglutide), we found results compatible with the previous trial (SRliraglutide 0.75, 0.51-1.10 and SRsemagltuide 1.23, 0.80-1.89). Since BAS also can be used as a cholesterol lowering drug, we repeated the main analysis while excluded statin users, resulting in a stronger association (SR 0.56, 0.33-0.96).

CONCLUSION

Using the SSA methodology, we obtained estimates of a collateral drug benefit that were compatible with trial results. These results support the use of epidemiological analyses of observational data as instrument for detecting collateral drug benefits.

The gut microbiome in disorders of gut-brain interaction

Functional gastrointestinal disorders (FGIDs), chronic disorders characterized by either abdominal pain, altered intestinal motility, or their combination, have a worldwide prevalence of more than 40% and impose a high socioeconomic burden with a significant decline in quality of life. Recently, FGIDs have been reclassified as disorders of gut-brain interaction (DGBI), reflecting the key role of the gut-brain bidirectional communication in these disorders and their impact on psychological comorbidities. Although, during the past decades, the field of DGBIs has advanced significantly, the molecular mechanisms underlying DGBIs pathogenesis and pathophysiology, and the role of the gut microbiome in these processes are not fully understood. This review aims to discuss the latest body of literature on the complex microbiota-gut-brain interactions and their implications in the pathogenesis of DGBIs. A better understanding of the existing communication pathways between the gut microbiome and the brain holds promise in developing effective therapeutic interventions for DGBIs.

Recent developments in diagnosing bile acid diarrhea

INTRODUCTION

Bile acid diarrhea (BAD) commonly causes chronic diarrhea. Symptoms may be mistaken for disorders of gut brain interaction. Due to the lack of widely available diagnostic tests and poor recognition of BAD, there is a delay in diagnosis leading to increased healthcare system burden and decreased patient quality of life.

AREAS COVERED

A thorough review of the literature was conducted using PubMed for articles on the biological functions of bile acids, pathophysiology and management of BAD, but focusing on diagnostic testing including 75SeHCAT retention, 7αC4, FGF-19, fecal bile acids, and single stool tests. This narrative review discusses available modalities focusing on noninvasive stool and serum testing that are more widely available and show good sensitivity and specificity for diagnosis of BAD. 75SeHCAT retention is not available in many countries. Alternative diagnostic tests include total and primary fecal bile acid (BA) excretion in 48-hour collection or a single stool sample, serum7αC4 >46 or 52.5 ng/mL, and combination of single stool and serum 7αC4 ±watery stools (Bristol Stool Form Scale 6-7).

EXPERT OPINION

Given the ease of serum and single stool sample acquisition and diagnostic advances, clinical practice should embrace positive diagnosis, rather than BAS therapeutic trial. BAD needs to be considered in diverse gastrointestinal diseases.