The renal apical sodium-dependent bile acid transporter expression rescue attenuates renal damage in diabetic nephropathy via farnesoid X receptor activation.

AIM: Bile acids (BA) function as signalling molecules regulating glucose-lipid homeostasis and energy expenditure. However, the expression of the apical sodium-dependent bile acid transporter (ASBT) in the kidney, responsible for renal BA reabsorption, is downregulated in patients with diabetic kidney disease (DKD). Using the db/db mouse model of DKD, this study aimed to investigate the effects of rescuing ASBT expression via adeno-associated virus-mediated delivery of ASBT (AAVASBT) on kidney protection. METHODS: Six-week-old male db/db mice received an intraparenchymal injection of AAVASBT at a dose of 1 × 1011 viral genomes (vg)/animal and were subsequently fed a chow diet for 2 weeks. Male db/m mice served as controls. For drug treatment, daily intraperitoneal (i.p.) injections of the farnesoid X receptor (FXR) antagonist guggulsterone (GS, 10 mg/kg) were administered one day after initiating the experiment. RESULTS: AAVASBT treatment rescued renal ASBT expression and reduced the urinary BA output in db/db mice. AAVASBT treatment activated kidney mitochondrial biogenesis and ameliorated renal impairment associated with diabetes by activating FXR. In addition, the injection of FXR antagonist GS in DKD mice would reverse these beneficial effects by AAVASBT treatment. CONCLUSION: Our work indicated that restoring renal ASBT expression slowed the course of DKD via activating FXR. FXR activation stimulates mitochondrial biogenesis while reducing renal oxidative stress and lipid build up, indicating FXR activation's crucial role in preventing DKD. These findings further suggest that the maintenance of renal BA reabsorption could be a viable treatment for DKD.

Smooth muscle contractile responses to bile acids in mouse ileum require TGR5 but not ASBT.

Background: Many disorders of gut-brain interaction (DGBIs) are more prevalent in women than men and feature alterations in gastrointestinal motility and bile acid homeostasis. Mechanisms by which bile acids regulate gastrointestinal motility are poorly characterized. We recently validated an adapted tissue bath technique using everted mouse ileum, which revealed differential contractile responses to ursodeoxycholic acid (UDCA) and deoxycholic acid (DCA). Here, we aimed to determine whether these responses are dependent on host sex, the plasma membrane bile acid receptor TGR5, or the apical sodium-dependent bile acid transporter ASBT. Methods: Ileal segments from male and female mice were everted and suspended in tissue baths. Contractile responses to physiologic concentrations of UDCA and DCA were quantified with or without TGR5 or ASBT inhibitors. Phosphorylation of extracellular signal-regulated kinase (ERK) and myosin light chain (MLC), markers of TGR5 activation and smooth muscle contraction, respectively, were assessed with western blot. Results: There were no sex differences in the dose-dependent contractile responses to bile acids. At 100 µmol/L, UDCA but not DCA increased MLC phosphorylation and increased contractility. TGR5 inhibition decreased ERK phosphorylation and led to decreases in contractility, phosphorylated MLC, and surprisingly, total MLC. ASBT inhibition did not affect contractile responses. Conclusion: Differential effects of UDCA and DCA on ileal smooth muscle contractility are not dependent on host sex or ASBT-mediated transport. Bile acids signal through mucosal TGR5, which regulates smooth muscle contractility by complex mechanisms. Understanding how bile acids differentially regulate gastrointestinal motility could facilitate new therapeutic options for specific DGBIs.

Regulating the absorption and excretion of perfluorooctane sulfonate and its alternatives through influencing enterohepatic circulation.

Enterohepatic circulation has been reported to play a significant role in the bioaccumulation of PFASs. In this study, the tissue distribution and excretion of PFOS and its alternatives, namely 6:2 and 8:2 fluorotelomer sulfonic acid (FTSA) was investigated using a mouse assay with a focus on role of enterohepatic circulation. Liver was the primarily accumulating organ for PFOS and 8:2 FTSA (33.4 % and 25.8 % of total doses absorbed after 14 days), whereas 65 % of 6:2 FTSA was excreted via urine within 24 h. Peak levels of 8:2 FTSA and PFOS were found in the gallbladder, implying the important role of enterohepatic circulation in PFASs reabsorption. The role of enterohepatic circulation was further evaluated through co-exposure of 8:2 FTSA and PFOS with medicines (namely metformin (MET) and ursodeoxycholic acid (UDCA)). MET reduced accumulation of 8:2 FTSA and PFOS in the liver by 68.6 % and 65.8 %, through down-regulation of bile acid transporter (Asbt) and enhancement of fecal excretion. Conversely, UDCA raised their concentrations by 21.9 % and 34.6 % compared to that exposed solely to PFASs. A strong positive correlation was identified between PFASs serum levels and Asbt expression. This study illuminated PFAS bioaccumulation mechanisms and suggested potential strategies to mitigate the exposure risks.

Emerging drugs for the treatment of progressive familial intrahepatic cholestasis: a focus on phase II and III trials.

INTRODUCTION: Progressive familial intrahepatic cholestasis (PFIC) is a group of disorders characterized by inappropriate bile formation, causing hepatic accumulation of bile acids and, subsequently, liver injury. Until recently, no approved treatments were available for these patients. AREAS COVERED: Recent clinical trials for PFIC treatment have focused on intestine-restricted ileal bile acid transporter (IBAT) inhibitors. These compounds aim to reduce the pool size of bile acids by interrupting their enterohepatic circulation. Other emerging treatments in the pipeline include systemic IBAT inhibitors, synthetic bile acid derivatives, compounds targeting bile acid synthesis via the FXR/FGF axis, and chaperones/potentiators that aim to enhance the residual activity of the mutated transporters. EXPERT OPINION: Substantial progress has been made in drug development for PFIC patients during the last couple of years. Although data concerning long-term efficacy are as yet only scarcely available, new therapies have demonstrated robust efficacy in a considerable fraction of patients at least on the shorter term. However, a substantial fraction of PFIC patients do not respond to these novel therapies and thus still requires surgical treatment, including liver transplantation before adulthood. Hence, there is still an unmet medical need for long-term effective medical, preferably non-surgical, treatment for all PFIC patients.

Normally, the liver produces bile which is a route of secretion of waste products from the body and also helps in the intestinal absorption of fats from the diet. The bile goes from the liver, through the bile duct to the intestines and components are taken up again at the end of the intestine and transported back to the liver. However, progressive familial intrahepatic cholestasis (PFIC in short) is a group of diseases where bile stays in the liver and damages it. PFIC often causes symptoms already in very young children, like itch and jaundice (getting a slight yellow color). Patients get more and worse symptoms over time and may eventually need a liver transplantation. This review discusses what drugs have been developed for PFIC recently and what drugs are in development now. Two new drugs for PFIC have been developed and approved in the last few years: odevixibat and maralixibat. These drugs help bile in the intestines leave the body via the stool and prevent bile from going back to the liver instead. Drugs in development aim to either 1) do the same, 2) make the bile less toxic, 3) reduce the production of bile, or 4) help bile go from the liver into the bile ducts. There has been a lot of progress in drug development for PFIC in the last few years. The new drugs have helped a considerable number of patients, but many patients still do not respond to these new drugs, keep having symptoms and may need surgery. Therefore, despite considerable progress, research needs to continue for an effective treatment for all PFIC patients.

Real-world experience of maralixibat in Alagille syndrome: Novel findings outside of clinical trials.

OBJECTIVE: Maralixibat, an ileal bile acid transporter inhibitor, is the first drug approved by the U.S. Food and Drug Administration for the treatment of cholestatic pruritus in patients aged ≥3 months with Alagille syndrome (ALGS). Approval was based on reductions in pruritus from the pivotal ICONIC trial, information from two additional trials (ITCH and IMAGO), and long-term extension studies. Although participants in these trials met strict inclusion and exclusion criteria, patients have received maralixibat under broader circumstances as part of an expanded access program or commercially. The expanded access and postapproval settings inform a real-world understanding of effectiveness and safety. The objective was to report on the use of maralixibat in the real-world setting in eight patients who otherwise would not have met entrance criteria for the clinical trials, providing unique insights into its effectiveness in the management of ALGS. METHODS: We reviewed records of patients with ALGS who received maralixibat but would have been excluded from trials due to surgical biliary diversion, reduction of antipruritic/cholestatic concomitant medications, administration of medication through a gastrostomy or nasogastric tube, or use in patients under consideration for transplantation. RESULTS: Maralixibat appeared to be effective with reductions in pruritus compared to baseline. Consistent with clinical trials, maralixibat was well tolerated without appreciable gastrointestinal complications. Liver enzyme elevations were observed but were interpreted as consistent with normal fluctuations observed in ALGS, with no increases in bilirubin. CONCLUSION: Maralixibat may be effective and well tolerated in patients with ALGS in broader clinical contexts than previously reported.

Intestinal in vitro transport assay combined with physiologically based kinetic modeling as a tool to predict bile acid levels in vivo.

Bile acid homeostasis is vital for numerous metabolic and immune functions in humans. The enterohepatic circulation of bile acids is extremely efficient, with ~95% of intestinal bile acids being reabsorbed. Disturbing intestinal bile acid uptake is expected to substantially affect intestinal and systemic bile acid levels. Here, we aimed to predict the effects of apical sodium-dependent bile acid transporter (ASBT)-inhibition on systemic plasma levels. For this, we combined in vitro Caco-2 cell transport assays with physiologically based (PBK) modeling. We used the selective ASBT-inhibitor odevixibat (ODE) as a model compound. Caco-2 cells grown on culture inserts were used to obtain transport kinetic parameters of glycocholic acid (GCA). The apparent Michaelis-Menten constant (Km,app), apparent maximal intestinal transport rate (Vmax,app), and ODE's inhibitory constant (Ki) were determined for GCA. These kinetic parameters were incorporated into a PBK model and used to predict the ASBT inhibition effects on plasma bile acid levels. GCA is transported over Caco-2 cells in an active and sodium-dependent manner, indicating the presence of functional ASBT. ODE inhibited GCA transport dose-dependently. The PBK model predicted that oral doses of ODE reduced conjugated bile acid levels in plasma. Our simulations match in vivo data and provide a first proof-of-principle for the incorporation of active intestinal bile acid uptake in a bile acid PBK model. This approach could in future be of use to predict the effects of other ASBT-inhibitors on plasma and intestinal bile acid levels.

Bile acids regulate digestion and immune functions. Too little bile acid reuptake in the gut is related to several diseases, including inflammatory bowel disease. This study investigates how reducing bile acid absorption affects bile acid levels in humans using the drug odevixibat (ODE) as an example. ODE reduces bile acid absorption by blocking the intestinal bile acid transporter protein in gut cells. The transport of a bile acid through a gut cell line commonly used to model the intestinal barrier was measured with and without ODE, and mathematical modeling was used to translate the laboratory results to whole-body effects. This combined approach accurately predicted the known effects of ODE on intestinal and bloodstream bile acid levels in humans. This novel approach could be used to predict the effects of other chemicals on intestinal bile acid absorption and intestinal and bloodstream bile acid levels instead of animal testing.

Role of apical sodium-dependent bile acid transporter in hepatobiliary diseases / 临床肝胆病杂志

Apical sodium-dependent bile acid transporter （ASBT） is a key transporter responsible for intestinal reabsorption of bile acid and plays an important role in maintaining bile acid and cholesterol homeostasis， and its expression is regulated by various factors including transcription factors， nuclear receptors， and intestinal microflora. The abnormal expression and function of ASBT can lead to disorders in the metabolism of bile acid and cholesterol， causing a variety of hepatobiliary diseases. At present， ASBT has attracted wide attention as a therapeutic target. This article elaborates on the biological characteristics and expression regulation mechanism of ASBT and reviews the role of ASBT in hepatobiliary diseases， in order to provide a new direction for the treatment of related diseases.

Exploiting Apical Sodium-Dependent Bile Acid Transporter (ASBT)-Mediated Endocytosis with Multi-Functional Deoxycholic Acid Grafted Alginate Amide Nanoparticles as an Oral Insulin Delivery System.

OBJECTIVE: Oral administration of insulin is a potential candidate for managing diabetes. However, it is obstructed by the gastrointestinal tract barriers resulting in negligible oral bioavailability. METHODS: This investigation presents a novel nanocarrier platform designed to address these challenges. In this regard, the process involved amination of sodium alginate by ethylene diamine, followed by its conjugation with deoxycholic acid. RESULTS: The resulting DCA@Alg@INS nanocarrier revealed a significantly high insulin loading content of 63.6 ± 1.03% and encapsulation efficiency of 87.6 ± 3.84%, with a particle size of 206 nm and zeta potentials of -3 mV. In vitro studies showed sustained and pH-dependent release profiles of insulin from nanoparticles. In vitro cellular studies, confocal laser scanning microscopy and flow cytometry analysis confirmed the successful attachment and internalization of DCA@Alg@INS nanoparticles in Caco-2 cells. Furthermore, the DCA@Alg@INS demonstrated a superior capacity for cellular uptake and permeability coefficient relative to the insulin solution, exhibiting sixfold and 4.94-fold enhancement, respectively. According to the uptake mechanism studies, the results indicated that DCA@Alg@INS was mostly transported through an energy-dependent active pathway since the uptake of DCA@Alg@INS by cells was significantly reduced in the presence of NaN3 by ~ 92% and at a low temperature of 4°C by ~ 94%. CONCLUSIONS: Given the significance of administering insulin through oral route, deoxycholic acid-modified alginate nanoparticles present a viable option to surmount various obstacles presented by the gastrointestinal.

Impact of elobixibat on liver tumors, microbiome, and bile acid levels in a mouse model of nonalcoholic steatohepatitis.

BACKGROUND: Elevated bile acid levels have been associated with liver tumors in fatty liver. Ileal bile acid transporter inhibitors may inhibit bile acid absorption in the distal ileum and increase bile acid levels in the colon, potentially decreasing the serum and hepatic bile acid levels. This study aimed to investigate the impact of these factors on liver tumor. METHODS: C57BL/6J mice received a one-time intraperitoneal injection of 25-mg/kg diethylnitrosamine. They were fed a choline-deficient high-fat diet for 20 weeks starting from 8 weeks of age, with or without elobixibat (EA Pharma, Tokyo, Japan). RESULTS: Both groups showed liver fat accumulation and fibrosis, with no significant differences between the two groups. However, mice with elobixibat showed fewer liver tumors. The total serum bile acid levels, including free, tauro-conjugated, glyco-conjugated, and tauro-α/ß-muricholic acids in the liver, were noticeably reduced following elobixibat treatment. The proportion of gram-positive bacteria in feces was significantly lower in the group treated with elobixibat (5.4%) than in the group without elobixibat (33.7%). CONCLUSION: Elobixibat suppressed tumor growth by inhibiting bile acid reabsorption, and decreasing total bile acid and primary bile acid levels in the serum and liver. Additionally, the presence of bile acids in the colon may have led to a significant reduction in the proportion of gram-positive bacteria, potentially resulting in decreased secondary bile acid synthesis.

Mechanism of substrate binding and transport in BASS transporters.

The Bile Acid Sodium Symporter (BASS) family transports a wide array of molecules across membranes, including bile acids in humans, and small metabolites in plants. These transporters, many of which are sodium-coupled, have been shown to use an elevator mechanism of transport, but exactly how substrate binding is coupled to sodium ion binding and transport is not clear. Here we solve the crystal structure at 2.3 Å of a transporter from Neisseria Meningitidis (ASBTNM) in complex with pantoate, a potential substrate of ASBTNM. The BASS family is characterised by two helices that cross-over in the centre of the protein in an arrangement that is intricately held together by two sodium ions. We observe that the pantoate binds, specifically, between the N-termini of two of the opposing helices in this cross-over region. During molecular dynamics simulations the pantoate remains in this position when sodium ions are present but is more mobile in their absence. Comparison of structures in the presence and absence of pantoate demonstrates that pantoate elicits a conformational change in one of the cross-over helices. This modifies the interface between the two domains that move relative to one another to elicit the elevator mechanism. These results have implications, not only for ASBTNM but for the BASS family as a whole and indeed other transporters that work through the elevator mechanism.

Enhancing oral bioavailability of insulin through bilosomes: Implication of charge and chain length on apical sodium-dependent bile acid transporter (ASBT) uptake.

This study investigates the impact of charge and chain length of bile salts in the bilosomes on the oral bioavailability of insulin (IN) by examining their uptake via the apical sodium-dependent bile acid transporter (ASBT). Deoxycholic acid bile salt was conjugated with different amino acids to create conjugates with varying charge and chain length, which were then embedded in liposomes. The resulting bilosomes had a particle size <400 nm, a PDI of 0.121 ± 0.03, and an entrapment efficiency of ∼70 %, while maintaining the chemical and conformational integrity of the loaded IN. Bilosomes also provided superior protection in biological fluids without compromising their biophysical attributes. Quantitative studies using the Caco-2 cell line demonstrated that anionic bilosomes were taken up more efficiently through ASBT than cationic bilosomes with 4- and 1.3-fold increase, respectively. Ex-vivo permeability studies corroborated these findings. In-vivo efficacy studies revealed a 1.6-fold increase in the AUC of IN with bilosomes compared to subcutaneous IN. The developed bilosomes were able to reduce blood glucose levels by ∼65 % at 6 h, with a cumulative hypoglycemic value of 35 % and a BAR of ∼30 %. These results suggest that ASBT can be a suitable target for improving the oral bioavailability of bilosomes containing IN.

Red ginseng extracts ameliorate high-fat diet-induced obesity and insulin resistance by activating the intestinal TGR5-mediated bile acids signaling pathway.

BACKGROUND: Obesity has emerged as a worldwide metabolic disease, given its rapid growth in global prevalence. Red ginseng extracts (RGS), one of the traditional processed products of ginseng, show the potential to improve the metabolic phenotype of obesity. However, the RGS mechanism for regulating obesity and late insulin resistance remains to be clarified. PURPOSE: This study aimed to emphasize the potential use of RGS in treatment of obesity and insulin resistance (IR) and explore the underlying mechanism affecting glucose and lipid metabolism improvements. METHODS: The role of RGS was evaluated in a high-fat diet (HFD) rodent model. Glucose tolerance test (GTT) and insulin tolerance test (ITT) were performed to characterize the glucose metabolism level. The expression of lipolysis proteins and uncoupling protein-1 (UCP-1) were investigated by western blot. Glucagon-like peptide-1 (GLP-1) and apical sodium-dependent bile acid transporter (ASBT) protein expression in the intestine were determined via immunofluorescence. UPLC-Q-TOF-MS were used to detect the alterations in bile acids (BAs) levels in serum, ileum, and inguinal white adipose tissue (iWAT). In addition, intestine-specific Tgr5 knockout mice were employed to verify the efficacy of RGS in improving obesity. RESULTS: RGS treatment alleviated dietary-induced dyslipidemia and IR in obese mice in a dose-dependent manner and improved glucose and insulin tolerance, and energy expenditure. RGS treatment significantly reduced lipid deposition and induced GLP-1 secretion in the intestine of wild-type mice but not in Tgr5ΔIN obese mice. Furthermore, RGS intervention increased BA levels in serum, ileum, and iWAT. The increase of circulating BAs in mice was related to the activation of ileal TGR5 and the promotion of ASBT translocation to the plasma membrane, thus affecting BA transport. Next, the increased level of circulating BAs entered the periphery, which might facilitate lipolysis and energy consumption by activating TGR5 in iWAT. CONCLUSION: Our results demonstrated that RGS significantly alleviated HFD-induced obesity and insulin resistance in mice. RGS intervention improved glucose metabolism, promoted lipolysis, and energy metabolism by activating TGR5 in the intestine. In addition, we found that activating intestinal TGR5 facilitated the localization of ASBT to the plasma membrane, which ultimately promoted the transport of BAs to regulate metabolic phenotype.

Influence of the Bile Acid Transporter Genes ABCB4, ABCB8, and ABCB11 and the Farnesoid X Receptor on the Response to Ursodeoxycholic Acid in Patients with Nonalcoholic Steatohepatitis.

The prevalence of NAFLD and NASH is increasing worldwide, and there is no approved medical treatment until now. Evidence has emerged that interfering with bile acid metabolism may lead to improvement in NASH. In this study, 28 patients with elevated cholestatic liver function tests (especially GGT) were screened for bile acid gene polymorphisms and treated with UDCA. All patients had a bile acid gene polymorphism in ABCB4 or ABCB11. Treatment with UDCA for 12 months significantly reduced GGT in all patients and ALT in homozygous patients. No difference in fibrosis was observed using FIb-4, NFS, and transient elastography (TE). PNPLA3 and TM6SF2 were the most common NASH-associated polymorphisms, and patients with TM6SF2 showed a significant reduction in GGT and ALT with the administration of UDCA. In conclusion, NASH patients with elevated GGT should be screened for bile acid gene polymorphisms, as UDCA therapy may improve liver function tests. However, no difference in clinical outcomes, such as progression to cirrhosis, has been observed using non-invasive tests (NITs).

Organic Anion Transporting Polypeptide (OATP) 1B3 is a Significant Transporter for Hepatic Uptake of Conjugated Bile Acids in Humans.

BACKGROUND & AIMS: OATP1B3/SLCO1B3 is a human liver-specific transporter for the clearance of endogenous compounds (eg, bile acid [BA]) and xenobiotics. The functional role of OATP1B3 in humans has not been characterized, as SLCO1B3 is poorly conserved among species without mouse orthologs. METHODS: Slc10a1-knockout (Slc10a1-/-), Slc10a1hSLCO1B3 (endogenous mouse Slc10a1 promoter-driven human-SLCO1B3 expression in Slc10a1-/- mice), and human SLCO1B3 liver-specific transgenic (hSLCO1B3-LTG) mice were generated and challenged with 0.1% ursodeoxycholic-acid (UDCA), 1% cholic-acid (CA) diet, or bile duct ligation (BDL) for functional studies. Primary hepatocytes and hepatoma-PLC/RPF/5 cells were used for mechanistic studies. RESULTS: Serum BA levels in Slc10a1-/- mice were substantially increased with or without 0.1% UDCA feeding compared with wild-type (WT) mice. This increase was attenuated in Slc10a1hSLCO1B3-mice, indicating that OATP1B3 functions as a significant hepatic BA uptake transporter. In vitro assay using primary hepatocytes from WT, Slc10a1-/-, and Slc10a1hSLCO1B3-mice indicated that OATP1B3 has a similar capacity in taking up taurocholate/TCA as Ntcp. Furthermore, TCA-induced bile flow was significantly impaired in Slc10a1-/- mice but partially recovered in Slc10a1hSLC01B3-mice, indicating that OATP1B3 can partially compensate the NTCP function in vivo. Liver-specific overexpression of OATP1B3 markedly increased the level of hepatic conjugated BA and cholestatic liver injury in 1% CA-fed and BDL mice. Mechanistic studies revealed that conjugated BAs stimulated Ccl2 and Cxcl2 in hepatocytes to increase hepatic neutrophil infiltration and proinflammatory cytokine production (eg, IL-6), which activated STAT3 to repress OATP1B3 expression by binding to its promoter. CONCLUSIONS: Human OATP1B3 is a significant BA uptake transporter and can partially compensate Ntcp for conjugated BA uptake in mice. Its downregulation in cholestasis is an adaptive protective response.

Oral lymphatic delivery of alpha-galactosylceramide and ovalbumin evokes anti-cancer immunization.

We developed an orally delivered nanoemulsion that induces cancer immunization. It consists of tumor antigen-loaded nano-vesicles carrying the potent invariant natural killer T-cell (iNKT) activator α-galactosylceramide (α-GalCer), to trigger cancer immunity by effectively activating both innate and adaptive immunity. It was validated that adding bile salts to the system boosted intestinal lymphatic transport as well as the oral bioavailability of ovalbumin (OVA) via the chylomicron pathway. To increase intestinal permeability further and amplify the antitumor responses, an ionic complex of cationic lipid 1,2-dioleyl-3-trimethylammonium propane (DTP) with sodium deoxycholate (DA) (DDP) and α-GalCer were anchored onto the outer oil layer to form OVA-NE#3. As expected, OVA-NE#3 exhibited tremendously improved intestinal cell permeability as well as enhanced delivery to mesenteric lymph nodes (MLNs). Subsequent activation of dendritic cells and iNKTs, in MLNs were also observed. Tumor growth in OVA-expressing mice with melanoma was more strongly suppressed (by 71%) after oral administration of OVA-NE#3 than in untreated controls, confirming the strong immune response induced by the system. The serum levels of OVA-specific IgG1 and IgG2a were 3.52- and 6.14-fold higher than in controls. Treating OVA-NE#3 increased the numbers of tumor-infiltrating lymphocytes, including cytotoxic T-cell and M1-like macrophage. Antigen- and α-GalCer-associated enrichment of dendritic cells and iNKTs in tumor tissues also increased after OVA-NE#3 treatment. These observations indicate that our system induces both cellular and humoral immunity by targeting the oral lymphatic system. It may offer a promising oral anti-cancer vaccination strategy that involves the induction of systemic anti-cancer immunization.

Japanese subgroup analysis of GLIMMER: A global Phase IIb study of linerixibat for the treatment of cholestatic pruritus in patients with primary biliary cholangitis.

AIM: To compare patient characteristics and outcomes between the overall and Japanese populations of GLIMMER. METHODS: GLIMMER was a multicenter, double-blind, randomized, placebo-controlled, Phase IIb study evaluating linerixibat for the treatment of pruritus in patients with primary biliary cholangitis. RESULTS: In total, 147 patients were randomized in the GLIMMER overall population with 38 patients comprising the Japanese population. Demographics and baseline clinical characteristics were similar across treatment groups and between both populations. A reduction in mean worst daily itch score from baseline to week 16 (primary endpoint) was seen in all groups, with the largest reduction observed with linerixibat 40 mg twice daily (BID; -2.92 [95% confidence interval: -5.07, -0.76] and -2.86 [95% confidence interval: -3.76, -1.95] for Japanese and overall populations, respectively). The highest proportion of responders was generally in the 40 mg BID group in both populations regardless of the responder definition applied. Improvements in health-related quality of life were generally consistent in both populations. In the Japanese and overall populations, on-treatment drug-related adverse events were reported in 25% and 19% of patients in the placebo group and 0%-86% and 31%-78% of patients in the linerixibat groups, respectively. Consistent with the mechanism of action, the most common events were gastrointestinal in nature. The effects of linerixibat on pharmacodynamic biomarkers favored BID dosing. CONCLUSIONS: Therapeutic responses and safety of linerixibat were consistent between the Japanese and overall populations of GLIMMER. Linerixibat may provide an effective treatment option for cholestatic pruritus in patients with primary biliary cholangitis. CLINICAL TRIAL REGISTRATION: NCT02966834.

Maralixibat Treatment Response in Alagille Syndrome is Associated with Improved Health-Related Quality of Life.

OBJECTIVE: The objective of this study was to assess the impact of treatment response to the ileal bile acid transporter inhibitor maralixibat on health-related quality of life (HRQoL) in children with Alagille syndrome. STUDY DESIGN: This analysis used data from the ICONIC trial, a phase 2 study with a 4-week double-blind, placebo-controlled, randomized drug withdrawal period in children with Alagille syndrome with moderate-to-severe pruritus. Clinically meaningful treatment response to maralixibat was defined a priori as a ≥1-point reduction in the Itch-Reported Outcome (Observer) score, from baseline to week 48. HRQoL was assessed using the Pediatric Quality of Life Inventory Generic Core, Family Impact, and Multidimensional Fatigue scale scores, which were collected via the caregiver. The minimal clinically important difference for HRQoL ranged from 4 to 5 points, depending on the scale. RESULTS: Twenty of the 27 patients (74%) included in this analysis achieved an Itch-Reported Outcome (Observer) treatment response at week 48. The mean (SD) change in Multidimensional Fatigue score was +25.8 (23.0) for responders vs -3.1 (19.8) for nonresponders (P = .03). Smaller and non-statistically significant mean changes were observed for the Pediatric Quality of Life Inventory Generic Core and Family Impact scores. Controlling for baseline Family Impact score, responders' Family Impact scores increased an average of 16.9 points over 48 weeks compared with non-responders (P = .05). Smaller and non-statistically significant point estimates were observed for the Pediatric Quality of Life Inventory Generic Core and Multidimensional Fatigue scores. CONCLUSION: The significant improvements in pruritus seen with maralixibat at week 48 of the ICONIC study are clinically meaningful and are associated with improved HRQoL. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02160782.

Odevixibat: an investigational inhibitor of the ileal bile acid transporter (IBAT) for the treatment of biliary atresia.

INTRODUCTION: Biliary atresia (BA) is a rare, non-curable cholestasis-causing disease in infancy, due to progressive ascending bile duct sclerosis. Even after restoration of bile flow following Kasai portoenterostomy, about half of these children need a liver transplant by their 2nd birthday, due to progressive fibrosis. Toxicity of bile acids may play a central role in disease progression, but drug therapies are not yet available. With ileal bile acid transporter (IBAT) inhibitors, there is a potential novel drug option that inhibits the absorption of bile acids in the small intestine. As a result of reduced bile acid accumulation in the cholestatic liver, it may be possible to delay hepatic remodeling. AREAS COVERED: This review summarizes the dataset on bile acids and the potential effects of odevixibat, an IBAT inhibitor, in children with BA. EXPERT OPINION: Systemic reduction of bile acids with the aim of preventing inflammation, and thus liver remodeling, is a novel, promising, therapeutic concept. In principle, however, the time until diagnosis and surgical treatment of BA should still be kept as short as possible in order to minimize liver remodeling before medical intervention can be initiated. IBAT inhibitors may add to the medical options in limiting disease progression in BA.

Suppression of bile acid synthesis as a tipping point in the disease course of primary sclerosing cholangitis.

Background & Aims: Farnesoid X receptor (FXR) agonists and fibroblast growth factor 19 (FGF19) analogues suppress bile acid synthesis and are being investigated for their potential therapeutic efficacy in cholestatic liver diseases. We investigated whether bile acid synthesis associated with outcomes in 2 independent populations of people with primary sclerosing cholangitis (PSC) not receiving such therapy. Methods: Concentrations of individual bile acids and 7α-hydroxy-4-cholesten-3-one (C4) were measured in blood samples from 330 patients with PSC attending tertiary care hospitals in the discovery and validation cohorts and from 100 healthy donors. We used a predefined multivariable Cox proportional hazards model to evaluate the prognostic value of C4 to predict liver transplantation-free survival and evaluated its performance in the validation cohort. Results: The bile acid synthesis marker C4 was negatively associated with total bile acids. Patients with fully suppressed bile acid synthesis had strongly elevated total bile acids and short liver transplantation-free survival. In multivariable models, a 50% reduction in C4 corresponded to increased hazards for liver transplantation or death in both the discovery (adjusted hazard ratio [HR] = 1.24, 95% CI 1.06-1.43) and validation (adjusted HR = 1.23, 95% CI 1.03-1.47) cohorts. Adding C4 to established risk scores added value to predict future events, and predicted survival probabilities were well calibrated externally. There was no discernible impact of ursodeoxycholic acid treatment on bile acid synthesis. Conclusions: Bile acid accumulation-associated suppression of bile acid synthesis was apparent in patients with advanced PSC and associated with reduced transplantation-free survival. In a subset of the patients, bile acid synthesis was likely suppressed beyond a tipping point at which any further pharmacological suppression may be futile. Implications for patient stratification and inclusion criteria for clinical trials in PSC warrant further investigation. Lay summary: We show, by measuring the level of the metabolite C4 in the blood from patients with primary sclerosing cholangitis (PSC), that low production of bile acids in the liver predicts a more rapid progression to severe disease. Many people with PSC appear to have fully suppressed bile acid production, and both established and new drugs that aim to reduce bile acid production may therefore be futile for them. We propose C4 as a test to find those likely to respond to these treatments.

N-(4-[18F]fluorobenzyl)cholylglycine, a potential tracer for positron emission tomography of enterohepatic circulation and drug-induced inhibition of ileal bile acid transport. A proof-of-concept PET/CT study in pigs.

INTRODUCTION: Enterohepatic circulation (EHC) of conjugated bile acids is an important physiological process crucial for bile acids to function as detergents and signal carriers. Perturbation of the EHC by disease or drugs may lead to serious and life-threatening liver and gastrointestinal disorders. In this proof-of-concept study in pigs, we investigate the potential of N-(4-[18F]fluorobenzyl)cholylglycine ([18F]FBCGly) as tracer for quantitative positron emission tomography (PET) of the EHC of conjugated bile acids. METHODS: The biodistribution of [18F]FBCGly was investigated by PET/CT in domestic pigs following intravenous and intraileal administration of the tracer. Hepatic kinetics were estimated from PET and blood data using a 2-tissue compartmental model and dual-input of [18F]FBCGly. The ileal uptake of [18F]FBCGly was investigated with co-injection of nifedipine and endogenous cholyltaurine. Dosimetry was estimated from the PET data using the Olinda 2.0 software. Blood, bile and urine samples were analyzed for possible fluorine-18 labelled metabolites of [18F]FBCGly. RESULTS: [18F]FBCGly was rapidly taken up by the liver and excreted into bile, and underwent EHC without being metabolized. Both nifedipine and endogenous cholyltaurine inhibited the ileal uptake of [18F]FBCGly. The flow-dependent hepatic uptake clearance was estimated to median 1.2 mL blood/min/mL liver tissue. The mean residence time of [18F]FBCGly in hepatocytes was 4.0 ± 1.1 min. Critical organs for [18F]FBCGly were the gallbladder wall (0.94 mGy/MBq) and the small intestine (0.50 mGy/MBq). The effective dose for [18F]FBCGly was 36 µSv/MBq. CONCLUSION: We have shown that [18F]FBCGly undergoes EHC in pigs without being metabolized and that its ileal uptake is inhibited by nifedipine and endogenous bile acids. Combined with our previous findings in rats, we believe that [18F]FBCGly has potential as PET tracer for assessment of EHC of conjugated bile acids under physiological conditions as well as conditions with perturbed hepatic and ileal bile acid transport.