The benefit of elobixibat in chronic constipation is associated with faecal deoxycholic acid but not effects of altered microbiota

Review on chronic metabolic diseases surrounding bile acids and gut microbiota: What we have explored so far

Bile acid, the final product of cholesterol breakdown, functions as a complex regulator and signaling factor in human metabolism. Chronic metabolic diseases pose significant medical challenges. Growing research underscores bile acids' capacity to enhance metabolism via diverse pathways, regulating disorders and offering treatment potential. Numerous bile-acid-triggered pathways have become treatment targets. This review outlines bile acid synthesis, its role as a signal in chronic metabolic diseases, and highlights its interaction with gut microbiota in different metabolic conditions. Exploring host-bacteria-bile acid links emerges as a valuable future research direction with clinical implications.

Elobixibat improves rectal sensation in patients with chronic constipation aged ≥60 years: a randomised placebo-controlled study

OBJECTIVE

High rectal sensory thresholds (RSTs) are associated with chronic constipation (CC), especially in older patients. Bile acids (BAs) affect the RSTs of healthy individuals. Here, we aimed to investigate the effects of the BA transporter inhibitor elobixibat in patients with CC aged ≥60 years.

DESIGN

We prospectively compared the RSTs of 17 patients with CC aged ≥60 years with those of 9 healthy individuals of the same age range. We next performed a prospective, randomised, parallel-group, double-blind, placebo-controlled clinical trial of 17 patients with CC who administered elobixibat or placebo daily for 1 week. Using barostat methodology, their first constant sensation volume (FCSV), defaecatory desire volume (DDV), and maximum tolerable volume (MTV) thresholds; their rectal compliance; and their faecal BA concentrations were measured before and after treatment.

RESULTS

There were no significant differences in the RSTs of healthy individuals and patients with CC, but all of these tended to be higher in the latter group. Elobixibat increased the desire to defaecate, significantly reduced the threshold for FCSV (p=0.0018), and tended to reduce the threshold for DDV (p=0.0899) versus placebo. However, there were no differences in the MTV or rectal compliance of the two groups. The total faecal BA concentration increased, and particularly that of secondary BAs in the elobixibat group. Elobixibat was most efficacious in participants with a longer duration of CC and a history of treatment for CC.

CONCLUSION

Elobixibat reduces the RSTs of patients with CC aged ≥60 years, which may be important for its therapeutic effects.

TRIAL REGISTRATION NUMBER

jRCTs061200030.

Evaluation of gut dysbiosis using serum and fecal bile acid profiles

Dysbiosis in the intestinal microflora can affect the gut production of microbial metabolites, and toxic substances can disrupt the barrier function of the intestinal wall, leading to the development of various diseases. Decreased levels of Clostridium subcluster XIVa (XIVa) are associated with the intestinal dysbiosis found in inflammatory bowel disease (IBD) and Clostridium difficile infection (CDI). Since XIVa is a bacterial group responsible for the conversion of primary bile acids (BAs) to secondary BAs, the proportion of intestinal XIVa can be predicted by determining the ratio of deoxycholic acid (DCA)/[DCA + cholic acid (CA)] in feces orserum. For example, serum DCA/(DCA+CA) was significantly lower in IBD patients than in healthy controls, even in the remission period. These results suggest that a low proportion of intestinal XIVa in IBD patients might be a precondition for IBD onset but not a consequence of intestinal inflammation. Another report showed that a reduced serum DCA/(DCA + CA) ratio could predict susceptibility to CDI. Thus, the BA profile, particularly the ratio of secondary to primary BAs, can serve as a surrogate marker of the intestinal dysbiosis caused by decreased XIVa.

Nanocrystalline Cellulose Cures Constipation via Gut Microbiota Metabolism

Constipation can seriously affect the quality of life and increase the risk of colorectal cancer. The present strategies for constipation therapy have adverse effects, such as causing irreversible intestinal damage and affecting the absorption of nutrients. Nanocrystalline cellulose (NCC), which is from natural plants, has good biocompatibility and high safety. Herein, we used NCC to treat constipation assessed by the black stool, intestinal tissue sections, and serum biomarkers. We studied the effect of NCC on gut microbiota and discussed the correlation of gut microbiota and metabolites. We evaluated the long-term biosafety of NCC. NCC could effectively treat constipation through gut microbiota metabolism, which required a small dosage and did not affect the organs and intestines. NCC could be used as an alternative to medications and dietary fiber for constipation therapy.

Development of stability indicating reversed phase HPLC method for determination of elobixibat in pure form and Laboratory prepared tablets: Application to dissolution study

A simple stability indicating reversed phase HPLC method has been developed for determination of elobixibat in presence of its potential impurities and degradation products. The chromatographic separation was carried on a Thermo scientific Base Deactivated Silica BDS Hypersil-C18 (150 × 4.6 mm; 5 μm) column using a mobile phase of acetonitrile and phosphate buffer (25 mM, pH 2.5) in a ratio of (70:30, volume/volume percentage). The experimental conditions were accurately investigated, and the method was validated according to International Conference on Harmonization ICH guidelines Q2 (R1). The drug was subjected to various stress conditions including acidic, basic, oxidative, and photolytic conditions. The method successfully separates the drug from the three reported impurities and different degradants. The method was also successfully applied for the determination of elobixibat in laboratory prepared tablets (5.0 mg). Analysis shows no interference from excipients and degradation products. The method was also applied for performing in vitro dissolution testing of elobixibat laboratory prepared tablets. Since elobixibat is recently introduced into the market, there are no previous stability studies and no reported analytical methods for its determination. Thus, this study presents a validated and selective method that can be effectively employed in routine quality control studies. This article is protected by copyright. All rights reserved.

Rationale and design of a multicenter, single-group, open-label trial aiming at investigating the effectiveness of elobixibat for loss of defecation desire in patients with chronic constipation

Background

Approximately 60% of patients with chronic constipation (CC) have a significantly higher rate of loss of defecation desire (LODD). Bile acids are expected to have a restorative effect on defecation desire (DD) because they lower the rectal sensory threshold, which is an objective index of DD. Elobixibat (EXB) specifically inhibits the ileal bile acid transporter/apical sodium-dependent bile acid transporter, which is a transporter involved in the reabsorption of bile acids in the terminal ileum. This study aims to investigate the LODD improvement rate in patients with CC after 4 weeks of EXB treatment.

Methods

A total of 40 adult patients with CC who meet the eligibility criteria will be enrolled. Patients will receive oral EXB (10 mg/day) for 4 weeks. A patient diary will be provided daily at 4 weeks after treatment. The primary endpoint will be the percentage LODD improvement at week 4 of the treatment period from week 2 of the observation period using questionnaires.

Ethics and dissemination

Ethical approval was obtained from the Yokohama City University Certified Institutional Review Board prior to participant enrolment (approval number: CRB21-008). The results of this study will be submitted for publication in international peer-reviewed journals, and key findings will be presented at international scientific conferences. Participants desiring the results of this study will be directly contacted for data dissemination.

Trial registration

This trial was registered at ClinicalTrials.gov (NCT05165199).

Protocol version

1.0, September 21, 2021.

Impact of elobixibat on serum and fecal bile acid levels and constipation symptoms in patients with chronic constipation

BACKGROUND AND AIM

Elobixibat is a locally acting inhibitor of the ileal bile acid transporter. We compared bile acid metabolism between healthy subjects and patients with chronic constipation and assessed changes in the bile acid profile after elobixibat administration in the latter group.

METHODS

Healthy subjects (n = 10) and patients with chronic constipation (n = 19) were assessed as inpatients for 7 days, during which they received meals containing ~60 g/day of fat. Patients with chronic constipation remained as inpatients for a further 7 days for once-daily elobixibat administration. Assessments included concentrations of fecal and serum bile acids, serum 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor 19, and bowel movements and constipation symptoms.

RESULTS

Fecal total and primary bile acids were significantly lower in patients with chronic constipation versus healthy subjects. Serum C4 and fibroblast growth factor 19 levels were comparable between groups. Elobixibat treatment increased fecal total and primary bile acids and decreased levels of fecal lithocholic acid and serum total as well as secondary bile acids in patients with chronic constipation. Bowel movements and other constipation-related symptoms were also improved by elobixibat to levels almost comparable with those of healthy subjects.

CONCLUSIONS

Despite comparable C4 levels, patients with chronic constipation demonstrated decreased levels of fecal bile acids versus healthy subjects. Elobixibat treatment increased fecal bile acid excretion and reduced serum bile acid concentrations. The improvement of constipation after elobixibat treatment was associated with increased total bile acids, particularly primary bile acids.

Emerging therapies in the management of Irritable Bowel Syndrome (IBS)

INTRODUCTION

Irritable bowel syndrome (IBS) is a common, symptom-based disorder of chronic abdominal pain and altered bowel habits. The pathogenesis of IBS is multifactorial, leading to the potential for the development of multiple, diverse treatment strategies. This mechanistic heterogeneity also leads to the realization that available therapies are only effective in a subset of IBS suffers. Current US Food and Drug Administration (FDA) approved therapies for IBS with diarrhea (IBS-D) and IBS with constipation (IBS-C) are reviewed. Limited symptom responses and side effect experiences lead to considerable patient dissatisfaction with currently available IBS treatments. Only a small percentage of IBS patients are on prescription therapies underscoring the potential market and need for additional therapeutic options.

AREAS COVERED

: Expanding on currently available therapies, the serotonergic and endogenous opioid receptor systems continue to be a focus of future IBS treatment development. Additional novel emerging therapies include the endogenous cannabinoid system, bile acid secretion and sequestration, and exploit our enhanced understanding of visceral sensory signaling and intestinal secretomotor function.

EXPERT OPINION

While challenges remain for the future development of IBS therapies, the diverse etiologies underlying the disorder present an opportunity for novel therapies. Hence, great potential is anticipated for future IBS treatment options.

Imidazole Propionate is Increased in Diabetes and Associated with Stool Consistency

BACKGROUND

Imidazole Propionate (ImP) is a new marker of Type 2 diabetes mellitus (T2DM), which can induce impaired glucose metabolism and weaken the efficacy of metformin. An extensive exploration into literature suggests that ImP may be associated with stool consistency.

PURPOSE

Through an in-depth study of the relationship between stool consistency, bile acids, fecal microbiota and ImP, we intend to explore the mechanism driving the ImP content difference in T2DM.

PATIENTS UNDER STUDY AND METHODS

This is a single-center, prospective, cross-sectional study. Plasma ImP and stool consistency were analyzed among 96 diabetic subjects and 45 healthy subjects. All subjects were divided into the stool consistency normal (N) group and the stool consistency abnormal group, of which the abnormal group was sub-divided into the hard stool (H) group and the soft stool (S) group. After identifying the correlation between ImP and stool consistency, we analyzed the influence of bile acids and fecal microbiota on ImP in diabetic subjects.

RESULTS

For T2DM patients, the ImP level of the abnormal stool consistency group was significantly higher than that of the normal stool consistency group (P < 0.001). Results were verified in 45 healthy subjects (P = 0.002). ImP was significantly associated with taurocholic acid (TCA) (P = 0.003) in feces, taurodeoxycholate (TDCA) (P = 0.003), glycochenodeoxycholate (GCDCA) (P = 0.021), and glycocholic acid (GCA) (P = 0.031) in plasma. The Shannon index of Group N was significantly higher than that of Group H (P = 0.041) and Group S (P = 0.003).

CONCLUSION

ImP was higher in diabetic patients with abnormal stool consistency than in those with normal stool consistency, which was related to the proportion of bile acids and fecal microbial structure. These findings may improve our understanding of ImP and contribute to the treatment of T2DM by improving stool consistency.

A prospective interventional trial on the effect of periodontal treatment on Fusobacterium nucleatum abundance in patients with colorectal tumours

Fusobacterium nucleatum is associated with the progression of colorectal cancer. Thus, the possibility of preventing colorectal cancer or its progression by targeting F. nucleatum has been explored. As F. nucleatum is associated with periodontitis, we analysed whether treating periodontitis could influence F. nucleatum abundance in the colon. Patients with colorectal tumours who underwent colonoscopy were recruited. Patients diagnosed with periodontitis by a dentist were treated for approximately 3 months. Endoscopic resection of colorectal tumours was performed after periodontitis treatment, and resected tumours were pathologically classified as high-(HGD) or low-grade dysplasia (LGD). Saliva and stool samples were collected before and after the treatment. Of the 58 patients with colorectal tumours, 31 were included in the study, 16 showed improvement in periodontitis, and 11 showed no improvement. Stool F. nucleatum levels before treatment were significantly lower in the LGD group than in the HGD group. A significant decrease in faecal F. nucleatum levels was observed in patients who underwent successful treatment but not in those whose treatment failed. Salivary F. nucleatum levels were not altered in patients despite periodontal treatment. Thus, successful periodontitis treatment reduces stool F. nucleatum levels and may aid research on periodontitis and suppression of colorectal cancer development.

Chronic Idiopathic Constipation in Adults: A Review on Current Guidelines and Emerging Treatment Options

Chronic idiopathic constipation (CIC) is a common functional bowel disorder characterized by difficult, infrequent, and/or incomplete defecation. It has a great impact on the quality of life and on health care system and represents a heavy economic burden. The diagnosis is based on symptoms, classified by the Rome IV criteria. The aim of this review was to evaluate the current therapeutic guidelines for adult CIC and highlight new emerging treatments. In detail, European, French, Spanish and Korean guidelines have been identified and compared. Osmotic laxatives, and in particular polyethylene glycol, represent the first-line therapeutic approach. Stimulant laxatives are recommended as a second-line therapy. Pelvic floor rehabilitation is recommended in patients with ano-rectal dyssynergia. In patients who fail to improve with pharmacological therapies sacral nerve stimulation is considered as last chance before surgery. Surgical approach has however limited indications in selected cases. Inertia coli refractory to any approach and obstructed defecation are two subtypes which can benefit from surgery. Among emerging agents, prucalopride, a prokinetic agent, is recommended as a second-line treatment in refractory CIC patients. In addition, the secretagogues linaclotide and plecanatide and the bile acid transported inhibitor elobixibat can be effective in patients not responsive to a second-line therapeutic regimen, although they are not worldwide commercially available.

Western Diet Changes Gut Microbiota and Ameliorates Liver Injury in a Mouse Model with Human-Like Bile Acid Composition

Western‐style high‐fat/high‐sucrose diet (HFHSD) changes gut microbiota and bile acid (BA) profiles. Because gut microbiota and BAs could influence each other, the mechanism of changes in both by HFHSD is complicated and remains unclear. We first aimed to clarify the roles of BAs in the HFHSD‐induced change of gut microbiota. Then, we studied the effects of the changed gut microbiota on BA composition and liver function. Male wild‐type (WT) and human‐like Cyp2a12/Cyp2c70 double knockout (DKO) mice derived from C57BL/6J were fed with normal chow or HFHSD for 4 weeks. Gut microbiomes were analyzed by fecal 16S ribosomal RNA gene sequencing, and BA composition was determined by liquid chromatography–tandem mass spectrometry. The DKO mice exhibited significantly reduced fecal BA concentration, lacked muricholic acids, and increased proportions of chenodeoxycholic and lithocholic acids. Despite the marked difference in the fecal BA composition, the profiles of gut microbiota in the two mouse models were quite similar. An HFHSD resulted in a significant increase in the BA pool and fecal BA excretion in WT mice but not in DKO mice. However, microbial composition in the two mouse models was drastically but similarly changed by the HFHSD. In addition, the HFHSD‐induced change of gut microbiota inhibited BA deconjugation and 7α‐dehydroxylation in both types of mice, which improved chronic liver injury observed in DKO mice. Conclusion: The HFHSD itself causes the change of gut microbiota due to HFHSD, and the altered composition or concentration of BAs by HFHSD is not the primary factor. On the contrary, the gut microbiota formed by HFHSD affects BA composition and ameliorates liver injury in the mouse model with human‐like hydrophobic BA composition.

Elobixibat, an ileal bile acid transporter inhibitor, ameliorates non-alcoholic steatohepatitis in mice

BACKGROUND

Recent studies have suggested that several types of toxic bile acids (BAs) are involved in the pathogenesis of non-alcoholic steatohepatitis (NASH). In the present study, we aimed to determine whether elobixibat, an ileal bile acid transporter (IBAT) inhibitor, would ameliorate NASH in mice.

METHODS

C57BL/6N mice were fed a methionine and choline-deficient (MCD) to induce NASH or standard diet as control for 8 weeks (n = 5 per group). The MCD diet-fed mice were administered elobixibat 5 days a week for 4 weeks by gavage (n = 5). The effects of the treatments on liver histopathology, proinflammatory cytokine concentrations, intestinal epithelial tight junctions, and the intestinal microbial composition were then assessed.

RESULTS

In MCD-fed mice, hepatic fibrosis and inflammatory cell infiltration developed, and the serum aspartate transaminase activity and BA concentration were higher than the control. In addition, the proinflammatory cytokine concentrations were high in the liver and mesenteric lymph nodes (MLN), and the expression of intestinal epithelium tight junction proteins, claudin1, was increased. In the intestinal microbial composition, the abundance of the Lachnospiraceae and Ruminococcaeae were decreased, whereas that of the Enterobacteriaceae was increased. Treatment with elobixibat reduced the serum BA and increased the fecal BA concentration, and ameliorated the liver inflammation and fibrosis. It also reduced the expression of proinflammatory cytokines in the liver and MLNs, and transforming growth factor-β expression in the liver. Finally, elobixibat normalized intestinal tight junction protein level and the composition of the intestinal microbiota.

CONCLUSION

Elobixibat ameliorates NASH-related histopathology, reduces cytokine expression, and normalizes the intestinal microbial composition in MCD-fed mice, which suggests that it may represent a promising candidate for the therapy of NASH.

Gut Microbiota Dysbiosis Is Associated with Elevated Bile Acids in Parkinson's Disease

The gut microbiome can impact brain health and is altered in Parkinson’s disease (PD). The vermiform appendix is a lymphoid tissue in the cecum implicated in the storage and regulation of the gut microbiota. We sought to determine whether the appendix microbiome is altered in PD and to analyze the biological consequences of the microbial alterations. We investigated the changes in the functional microbiota in the appendix of PD patients relative to controls (n = 12 PD, 16 C) by metatranscriptomic analysis. We found microbial dysbiosis affecting lipid metabolism, including an upregulation of bacteria responsible for secondary bile acid synthesis. We then quantitatively measure changes in bile acid abundance in PD relative to the controls in the appendix (n = 15 PD, 12 C) and ileum (n = 20 PD, 20 C). Bile acid analysis in the PD appendix reveals an increase in hydrophobic and secondary bile acids, deoxycholic acid (DCA) and lithocholic acid (LCA). Further proteomic and transcriptomic analysis in the appendix and ileum corroborated these findings, highlighting changes in the PD gut that are consistent with a disruption in bile acid control, including alterations in mediators of cholesterol homeostasis and lipid metabolism. Microbially derived toxic bile acids are heightened in PD, which suggests biliary abnormalities may play a role in PD pathogenesis.