Regulation Of Bile Acid Synthesis Research Articles

Acute lung injury therapeutic mechanism exploration for Chinese classic prescription Qingzao Jiufei Decoction by UFLC-MS/MS quantification of bile acids, fatty acids and eicosanoids in rats

Acute lung injury (ALI) is a common and complex inflammatory disease, which has been reasonably associated with carboxyl-containing metabolites in our preliminary non-targeted metabolomic strategy. Qingzao Jiufei Decoction (QZJFD), a classic prescription, is widely used in the treatment of pulmonary inflammatory injuries. Successively, in this targeted project, to fill in the research gap and exposit the therapeutic mechanism of QZJFD on ALI, considering the structure similarity and bioactivity correlation, 21 bile acids, 11 fatty acids and 19 eicosanoids were profiled simultaneously in plasma, lung, bronchoalveolar lavage fluid, spleen and feces from rats utilizing a novel ultraperformance liquid chromatography-mass spectrometry approach. As a result, potential biomarkers and ALI characteristic metabolomic spectrums were obtained to distinguish different physical states using discriminative similarity threshold as 0.65 for clinical application. After treatment with QZJFD, obvious reversing ability for various biomarker levels was observed in different bio-samples, providing insights into the systemic intervention of QZJFD on ALI by regulating bile acid synthesis, fatty acid synthesis and eicosanoid metabolism. Conclusively, this investigation represented more information on the comprehensive therapeutic action of QZJFD on ALI involving with multi-targets and multi-pathways for clinical application and traditional Chinese medicine modernization.

Fibroblast growth factor 19 alleviates palmitic acid-induced mitochondrial dysfunction and oxidative stress via the AMPK/PGC-1α pathway in skeletal muscle

Obesity-induced fat ectopic deposition results in mitochondrial dysfunction and oxidative stress in skeletal muscle, which could impair the quality and function of the skeletal muscle. Human fibroblast growth factor 19 (FGF19) acts as a vital metabolic regulator of bile acid synthesis and metabolic homeostasis. Recent studies have shown that FGF19 regulates skeletal muscle mass through the enlargement of muscle fiber size and protects muscles from atrophy. However, the role of FGF19 in regulating mitochondrial function and the antioxidant response in skeletal muscle remains unknown. Therefore, we investigated the effect of FGF19 on palmitic acid (PA)-induced mitochondrial dysfunction and oxidative stress in C2C12 cells. In this study, we found that FGF19 can increase the mRNA and protein expression levels of mitochondrial biogenesis regulators (PGC-1α, Nrf-1, and TFAM) and antioxidant response regulators (Nrf-2 and HO-1), alleviating PA-induced mitochondrial dysfunction and oxidative stress. However, the regulatory effect of FGF19 was blocked by Compound C, an AMP-activated protein kinase (AMPK) inhibitor, and siRNA knockdown of PGC-1a. Taken together, these findings indicate that FGF19 might promote mitochondrial biogenesis and antioxidant response via the AMPK/PGC-1α pathway, attenuating the effect of PA on mitochondrial dysfunction and oxidative stress; therefore, FGF19 might be a potential therapeutic target for the effects of obesity on skeletal muscle.

Fucose Ameliorate Intestinal Inflammation Through Modulating the Crosstalk Between Bile Acids and Gut Microbiota in a Chronic Colitis Murine Model.

Recurrent intestinal inflammation is frequently associated with aberrant bile acid profiles and microbial community. Fucose exerts a protective effect on commensal bacteria in the case of intestinal pathogen infection. We speculated that fucose might also have certain impact on the microbial ecosystem under the chronic colitis setting. To validate our hypothesis, multi-omics examination was performed in combination with microbiomics and metabonomics in a chronic dextran sulfate sodium (DSS) murine model in the presence or absence of fucose. The 16S RNA sequencing was carried out to determine the ileum and colon microbiota. Primary and secondary bile acids, together with the respective taurine and glycine conjugates, were quantified through ultraperformance liquid chromatography coupled with mass spectrometry (UPLC-MS). Moreover, enzymes involved in regulating bile acid synthesis were also detected. Finally, an experiment was carried out on the antibiotic-treated mice to examine the role of gut microbiota. Administration of exogenous-free fucose markedly alleviated the inflammatory response in colitis mice. In addition, excessive intestinal bile acid accumulated in DSS mice was decreased in the presence of fucose, along with the restoration of the compromised regulation on hepatic bile acid synthesis. Moreover, the shifts in bile acid profiles were linked with the improved gut microbiome dysbiosis. However, the protective effects of fucose were abolished in mice treated with antibiotic cocktail, indicating that microbiota played a pivotal role. Findings in this study suggest that fucose ameliorates colitis through restoring the crosstalk between bile acid and gut microbiota.

Bile acid receptors FXR and TGR5 signaling in fatty liver diseases and therapy.

Bile acid synthesis is the most significant pathway for catabolism of cholesterol and for maintenance of whole body cholesterol homeostasis. Bile acids are physiological detergents that absorb, distribute, metabolize, and excrete nutrients, drugs, and xenobiotics. Bile acids also are signal molecules and metabolic integrators that activate nuclear farnesoid X receptor (FXR) and membrane Takeda G protein-coupled receptor 5 (TGR5; i.e., G protein-coupled bile acid receptor 1) to regulate glucose, lipid, and energy metabolism. The gut-to-liver axis plays a critical role in the transformation of primary bile acids to secondary bile acids, in the regulation of bile acid synthesis to maintain composition within the bile acid pool, and in the regulation of metabolic homeostasis to prevent hyperglycemia, dyslipidemia, obesity, and diabetes. High-fat and high-calorie diets, dysbiosis, alcohol, drugs, and disruption of sleep and circadian rhythms cause metabolic diseases, including alcoholic and nonalcoholic fatty liver diseases, obesity, diabetes, and cardiovascular disease. Bile acid-based drugs that target bile acid receptors are being developed for the treatment of metabolic diseases of the liver.

Disruption of hepatic small heterodimer partner induces dissociation of steatosis and inflammation in experimental nonalcoholic steatohepatitis

Disruption of hepatic small heterodimer partner induces dissociation of steatosis and inflammation in experimental nonalcoholic steatohepatitis

Abstract C072: Discovery of highly potent and selective covalent inhibitors of FGFR4

Abstract Hepatocellular carcinoma (HCC) accounts for 65% of all cases of liver cancers, ranking the 6th most common cancer and the 2nd cause of cancer mortality. HCC has more than 700,000 new cases/year and 600,000 deaths/year. Sorafenib is currently the standard of care for advanced disease, provides a response rate of ~2% and median survival <11 months. The fibroblast growth factor 19 (FGF19)-fibroblast growth factor receptor 4 (FGFR4)-Klotho β (KLB) signaling pathway regulates bile acid synthesis and is also a key driver in certain subtypes of HCC (around 30%). We generated BGS2219 and BGS2223 through FGFR4 structure-based design. BGS2219 and BGS223 are potent, selective and irreversible FGFR4 inhibitors. BGS2219 inhibits FGFR4 with an IC50 of 4nM and has greater than 2500 fold selectivity over FGFR1, 2 and 3. BG2219 took effects in both HCC and RMS tumor cell lines. In vivo administration of BG2219 was well tolerated in mice at all dosages with no body weight loss and and inhibited tumor growth in a dose -dependent fashion in HCC xenograft model. Complete tumor regression was observed at 40mg/kg. BGS2219 was tested in a combo therapy regimen with R1507 (anti-IGFR1 mab) in RMS (rhabdomyosarcoma) xenograft model in mice and showed that BG2219 plus R1507 significantly reduce the tumor volume in comparison with R1507 alone. BGS2223 is derived from BG2219, with improved oral bioavailability. BGS2223 has no hit in Cerep Screen safety panel and no activity detected in hERG assay at 10mM. In vivo oral administration of BG2223 in mice was well tolerated with no body weight loss and showed dose-dependent tumor growth inhibition in HCC CDX model at all dosages. Tumor regression was achieved at high dose treatment. BGS22 treatment in vivo in HCC tumor bearing mice caused alteration of CYP7A1 and FGF19 expression, which were utilized as biomarkers for FGFR4 inhibition. Citation Format: Hang Chen, Katherine Slemmons, Heather Ha, Robert Stanley, Qian Cai, Irene Yuan, Lee Helman, Ping Cao. Discovery of highly potent and selective covalent inhibitors of FGFR4 [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C072. doi:10.1158/1535-7163.TARG-19-C072

FGF21 acts as a negative regulator of bile acid synthesis

Fibroblast growth factor 21 (FGF21) is a potent regulator of glucose and lipid homeostasis in vivo; its most closely related subfamily member, FGF19, is known to be a critical negative regulator of bile acid synthesis. To delineate whether FGF21 also plays a functional role in bile acid metabolism, we evaluated the effects of short- and long-term exposure to native FGF21 and long-acting FGF21 analogs on hepatic signal transduction, gene expression and enterohepatic bile acid levels in primary hepatocytes and in rodent and monkey models. FGF21 acutely induced ERK phosphorylation and inhibited Cyp7A1 mRNA expression in primary hepatocytes and in different rodent models, although less potently than recombinant human FGF19. Long-term administration of FGF21 in mice fed a standard chow diet resulted in a 50-60% decrease in bile acid levels in the liver and small intestines and consequently a 60% reduction of bile acid pool size. In parallel, colonic and fecal bile acid was decreased, whereas fecal cholesterol and fatty acid excretions were elevated. The long-acting FGF21 analog showed superiority to recombinant human FGF21 and FGF19 in decreasing bile acid levels with long duration of effect action in mice. Long-term administration of the long-acting FGF21 analogs in obese cynomolgus monkeys suppressed plasma total bile acid and 7α-hydroxy-4-cholesten-3-one levels, a biomarker for bile acid synthesis. Collectively, these data reveal a previously unidentified role of FGF21 in bile acid metabolism as a negative regulator of bile acid synthesis.

New treatments/targets for primary biliary cholangitis.

SummaryPrimary biliary cholangitis (PBC) is an autoimmune, cholestatic, chronic liver disease that ultimately progresses towards cirrhosis and liver failure if untreated. While ursodeoxycholic acid has been established as standard of care for PBC in the last few decades, significant advances in second-line treatment options have recently been made and new therapeutic developments are currently under evaluation. The purpose of this article is to provide the clinician with an overview of the current treatment options and future opportunities for patients with PBC.

Hepatocyte peroxisome proliferator-activated receptor α regulates bile acid synthesis and transport

Peroxisome proliferator-activated receptor alpha (PPARα) controls lipid homeostasis through regulation of lipid transport and catabolism. PPARα activators are clinically used for hyperlipidemia treatment. The role of PPARα in bile acid (BA) homeostasis is beginning to emerge. Herein, Ppara-null and hepatocyte-specific Ppara-null (Ppara∆Hep) as well as the respective wild-type mice were treated with the potent PPARα agonist Wy-14,643 (Wy) and global metabolomics performed to clarify the role of hepatocyte PPARα in the regulation of BA homeostasis. Levels of all serum BAs were markedly elevated in Wy-treated wild-type mice but not in Ppara-null and Ppara∆Hep mice. Gene expression analysis showed that PPARα activation (1) down-regulated the expression of sodium-taurocholate acid transporting polypeptide and organic ion transporting polypeptide 1 and 4, responsible for the uptake of BAs into the liver; (2) decreased the expression of bile salt export pump transporting BA from hepatocytes into the bile canaliculus; (3) upregulated the expression of multidrug resistance-associated protein 3 and 4 transporting BA from hepatocytes into the portal vein. Moreover, there was a notable increase in the compositions of serum, hepatic and biliary cholic acid and taurocholic acid following Wy treatment, which correlated with the upregulated expression of the Cyp8b1 gene encoding sterol 12α-hydroxylase. The effects of Wy were identical between the Ppara∆Hep and Ppara-null mice. Hepatocyte PPARα controlled BA synthesis and transport not only via direct transcriptional regulation but also via crosstalk with hepatic farnesoid X receptor signaling. These findings underscore a key role for hepatocyte PPARα in the control of BA homeostasis.

Enhanced Microbial Bile Acid Deconjugation and Impaired Ileal Uptake in Pregnancy Repress Intestinal Regulation of Bile Acid Synthesis.

Pregnancy is associated with progressive hypercholanemia, hypercholesterolemia, and hypertriglyceridemia, which can result in metabolic disease in susceptible women. Gut signals modify hepatic homeostatic pathways, linking intestinal content to metabolic activity. We sought to identify whether enteric endocrine signals contribute to raised serum bile acids observed in human and murine pregnancies, by measuring fibroblast growth factor (FGF) 19/15 protein and mRNA levels, and 7α‐hydroxy‐4‐cholesten‐3‐one. Terminal ileal farnesoid X receptor (FXR)‐mediated gene expression and apical sodium bile acid transporter (ASBT) protein concentration were measured by qPCR and western blotting. Shotgun whole‐genome sequencing and ultra‐performance liquid chromatography tandem mass spectrometry were used to determine the cecal microbiome and metabonome. Targeted and untargeted pathway analyses were performed to predict the systemic effects of the altered metagenome and metabolite profiles. Dietary CA supplementation was used to determine whether the observed alterations could be overcome by intestinal bile acids functioning as FXR agonists. Human and murine pregnancy were associated with reduced intestinal FXR signaling, with lower FGF19/15 and resultant increased hepatic bile acid synthesis. Terminal ileal ASBT protein was reduced in murine pregnancy. Cecal bile acid conjugation was reduced in pregnancy because of elevated bile salt hydrolase‐producing Bacteroidetes. CA supplementation induced intestinal FXR signaling, which was not abrogated by pregnancy, with strikingly similar changes to the microbiota and metabonome as identified in pregnancy. Conclusion: The altered intestinal microbiota of pregnancy enhance bile acid deconjugation, reducing ileal bile acid uptake and lowering FXR induction in enterocytes. This exacerbates the effects mediated by reduced bile acid uptake transporters in pregnancy. Thus, in pregnant women and mice, there is reduced FGF19/15‐mediated hepatic repression of hepatic bile acid synthesis, resulting in hypercholanemia.

An overview of bile acid synthesis and its physiological and pathological functions

Bile acids are a class of cholesterol derivatives that play important roles in cholesterol and energy homeostasis and intestinal nutrition absorption. Bile acids are mainly synthesized in the liver. During fasting, bile acids are secreted from the liver and stored in the gallbladder. After a meal, the stored bile acids are released into small intestines. In the intestine, about 95% of bile acids will be re-absorbed and travel back into the liver through port veins, which is called bile acid enterohepatic circulation. This enterohepatic circulation of bile acids plays important roles in the emulsification and intestinal absorption of lipids and other nutrition. On the other hand, bile acids function as ligands for a number of receptors, such as farnesoid X receptor (FXR), proterane X receptor (PXR), vitamin D receptor (VDR) and cell membrane surface receptor-G protein coupled receptor (TGR5), which play important roles from metabolic homeostasis to innate immunity. A number of cytokines such as hepatocyte growth factor (HGF), interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α) regulate the homeostasis of bile acids. In the current review, we will summarize the recent progress in the regulation of bile acid synthesis and its physiological and pathological functions from energy homeostasis to innate immunity and cancer progression to provide a reference for the study of bile acid metabolism.

Weight loss and fitness intervention increase markers of hepatic bile acid (BA) synthesis, while reducing serum total BA concentrations in sedentary, obese insulin resistant women

Beyond adipose and muscle, excerise has profound effects in other metabolically‐important tissues including the liver. Bile acids (BAs) are synthesized from cholesterol via the rate‐limiting enzyme cholesterol 7 alpha‐hydroxylase (CYP7A1) and contribute to the solubilization and absorption of lipid soluble nutrients, and serve as important signaling molecules capable of systemic endocrine function. Circulating BA are known to be higher in obesity and insulin resistance, but effects following exercise and diet‐induced weight loss are unknown. To test if improved fitness and weight loss influence bile acid metabolism and homeostasis, we measured fasting serum concentrations of total BAs (conjugated and free forms of primary and secondary BAs) in sedentary, obese insulin‐resistant women (N=12) before and after a ~14 wk weight loss and exercise intervention [Campell et al. 2014, PLoS One, 9: e84260]. In addition, serum FGF19 (a regulator of BA synthesis) and 7‐alpha‐hydroxy‐cholesten‐3‐one (C4, a verified marker of CYP7A1 enzymatic acitivity) were measured by ELISA and LC‐MS, respectively. Using mixed‐model analyses and the change in relative VO2peak (mL/min/kg) as a covariate, we observed a significant decrease (~30%) in total serum BAs post‐intervention relative to pre‐intervention samples. Corresponding to the decrease in total BAs, fasting serum concentrations of C4 were 55% higher post‐intervention relative to the matched pre‐intervention samples (P=0.004). Interestingly, we observed no changes in serum FGF19. These data suggest that weight loss and/or improved fitness altered BA metabolism marked by increased hepatic BA synthesis and reduced serum BA. The underlying mechanisms remain to be determined, but work from our preclinical rodent models supports the idea that increased BA metabolic flux is linked to enhanced hepatic mitochondrial function.Support or Funding InformationThis work was supported by USDA Projects 6026‐51000‐010‐05S and 2032‐51530‐022‐00D, and NIH‐NIDDK R01DK078328 and NIDDK U24 DK097154.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Activation of the Bile Acid Pathway and No Observed Antimicrobial Peptide Sequences in the Skin of a Poison Frog.

The skin secretions of many frogs have genetically-encoded, endogenous antimicrobial peptides (AMPs). Other species, especially aposematic poison frogs, secrete exogenously derived alkaloids that serve as potent defense molecules. The origins of these defense systems are not clear, but a novel bile-acid derived metabolite, tauromantellic acid, was recently discovered and shown to be endogenous in poison frogs (Mantella, Dendrobates, and Epipedobates). These observations raise questions about the evolutionary history of AMP genetic elements, the mechanism and function of tauromatellic acid production, and links between these systems. To understand the diversity and expression of AMPs among frogs, we assembled skin transcriptomes of 13 species across the anuran phylogeny. Our analyses revealed a diversity of AMPs and AMP expression levels across the phylogenetic history of frogs, but no observations of AMPs in Mantella. We examined genes expressed in the bile-acid metabolic pathway and found that CYP7A1 (Cytochrome P450), BAAT (bile acid-CoA: amino acid N-acyltransferase), and AMACR (alpha-methylacyl-CoA racemase) were highly expressed in the skin of M. betsileo and either lowly expressed or absent in other frog species. In particular, CYP7A1 catalyzes the first reaction in the cholesterol catabolic pathway and is the rate-limiting step in regulation of bile acid synthesis, suggesting unique activation of the bile acid pathway in Mantella skin. The activation of the bile acid pathway in the skin of Mantella and the lack of observed AMPs fuel new questions about the evolution of defense compounds and the ectopic expression of the bile-acid pathway.

Regulation of Fgf15 expression in the intestine by glucocorticoid receptor.

Fibroblast growth factor 15 (FGF15) was previously identified to be highly expressed in the ileum and functions as an endocrine factor to regulate bile acid synthesis in the liver. FGF15 targets its receptor fibroblast growth factor receptor 4 in the liver and serves important roles in energy metabolism, including bile acid homeostasis, glucose metabolism and protein synthesis. The expression of FGF15 is known to be regulated by the transcription factor farnesoid X receptor (FXR). In the present study, reverse transcription-quantitative polymerase chain reaction was used for measuring Fgf15 expression from the animal and tissue culture experiments, and it was identified that dexamethasone, a drug widely used in anti-inflammation therapy, and a classical inducer of glucocorticoid receptor (GR)- and pregnane X receptor (PXR)-target genes, may downregulate Fgf15 expression in the ileum. GR was identified to be highly expressed in the ileum by western blot analysis. Furthermore, it was demonstrated that the downregulation of Fgf15 by dexamethasone is due to the repression of ileal FXR activity via GR; however, not PXR, in the ileum. The present results provide insight for a better understanding of the adverse effects associated with dexamethasone therapy.

Obesity in Adolescents and Youth: The Case for and against Bariatric Surgery

Obesity in Adolescents and Youth: The Case for and against Bariatric Surgery

Targeting FXR in Cholestasis.

The farnesoid X receptor (FXR, NR1H4) is a bile acid (BA)-activated transcription factor, which is essential for BA homeostasis. FXR and its hepatic and intestinal target genes, small heterodimer partner (SHP, NR0B2) and fibroblast growth factor 15/19 (Fgf15 in mice, FGF19 in humans), transcriptionally regulate BA synthesis, detoxification, secretion, and absorption in the enterohepatic circulation. Furthermore, FXR modulates a large variety of physiological processes, such as lipid and glucose homeostasis as well as the inflammatory response. Targeted deletion of FXR renders mice highly susceptible to cholic acid feeding resulting in cholestatic liver injury, weight loss, and increased mortality. Combined deletion of FXR and SHP spontaneously triggers early-onset intrahepatic cholestasis in mice resembling human progressive familial intrahepatic cholestasis (PFIC). Reduced expression levels and activity of FXR have been reported in human cholestatic conditions, such as PFIC type 1 and intrahepatic cholestasis of pregnancy. Recently, two pairs of siblings with homozygous FXR truncation or deletion variants were identified. All four children suffered from severe, early-onset PFIC and liver failure leading to death or need for liver transplantation before the age of 2. These findings underscore the central role of FXR as regulator of systemic and hepatic BA levels. Therefore, targeting FXR has been exploited in different animal models of both intrahepatic and obstructive cholestasis, and the first FXR agonist obeticholic acid (OCA) has been approved for the treatment of primary biliary cholangitis (PBC). Further FXR agonists as well as a FGF19 analogue are currently tested in clinical trials for different cholestatic liver diseases. This chapter will summarize the current knowledge on the role of FXR in cholestasis both in rodent models and in human diseases.

Regulation of Hepatic Long Noncoding RNAs by Pregnane X Receptor and Constitutive Androstane Receptor Agonists in Mouse Liver.

Altered expression of long noncoding RNAs (lncRNAs) by environmental chemicals modulates the expression of xenobiotic biotransformation-related genes and may serve as therapeutic targets and novel biomarkers of exposure. The pregnane X receptor (PXR/NR1I2) is a critical xenobiotic-sensing nuclear receptor that regulates the expression of many drug-processing genes, and it has similar target-gene profiles and DNA-binding motifs with another xenobiotic-sensing nuclear receptor, namely, constitutive andronstrane receptor (CAR/Nr1i3). To test our hypothesis that lncRNAs are regulated by PXR in concert with protein-coding genes (PCGs) and to compare the PXR-targeted lncRNAs with CAR-targeted lncRNAs, RNA-Seq was performed from livers of adult male C57BL/6 mice treated with corn oil, the PXR agonist PCN, or the CAR agonist 1, 4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP). Among 125,680 known lncRNAs, 3843 were expressed in liver, and 193 were differentially regulated by PXR (among which 40% were also regulated by CAR). Most PXR- or CAR-regulated lncRNAs were mapped to the introns and 3'-untranslated regions (UTRs) of PCGs, as well as intergenic regions. Combining the RNA-Seq data with a published PXR chromatin immunoprecipitation coupled with high-throughput sequencing; cytochrome P450 (P450; ChIP-Seq) data set, we identified 774 expressed lncRNAs with direct PXR-DNA binding sites, and 26.8% of differentially expressed lncRNAs had changes in PXR-DNA binding after PCN exposure. De novo motif analysis identified colocalization of PXR with liver receptor homolog (LRH-1), which regulates bile acid synthesis after PCN exposure. There was limited overlap of PXR binding with an epigenetic mark for transcriptional activation (histone-H3K4-di-methylation, H3K4me2) but no overlap with epigenetic marks for transcriptional silencing [H3 lysine 27 tri-methylation (H3K27me3) and DNA methylation]. Among differentially expressed lncRNAs, 264 were in proximity of PCGs, and the lncRNA-PCG pairs displayed a high coregulatory pattern by PXR and CAR activation. This study was among the first to demonstrate that lncRNAs are regulated by PXR and CAR activation and that they may be important regulators of PCGs involved in xenobiotic metabolism.

Adaptive homeostasis of the vitamin D–vitamin D nuclear receptor axis in 8-methoxypsoralen-induced hepatotoxicity

8-methoxypsoralen (8-MOP) with ultraviolet A radiation therapy (PUVA) is the standard therapy for patients with psoriasis, despite the reported potential risks of 8-MOP-induced cholestatic liver injury in both humans and animals. Usually, patients with chronic cholestasis exhibit lower serum 25-hydroxy vitamin D (25(OH)D) levels. But those patients receiving PUVA for psoriasis showed an increase in serum 25(OH)D levels, probably highlighting that the vitamin D–vitamin D nuclear receptor (VD-VDR) axis play a protective role in 8-MOP-induced hepatotoxicity. The present study confirmed 8-MOP could increase serum 25(OH)D levels in conventional lighting and diet (CLD) and vitamin D deficient (VDD) Sprague-Dawley rats. Potential liver risks were also found in CLD and VDD rats after 8-MOP treatment. We proved that 8-MOP could be a potent ligand for VDR using molecular docking and luciferase report assay. Effect of 8-MOP on VDR subcellular distribution was determined using human liver cell line L02. We found 8-MOP could increase VDR protein expression in the nuclear and cytosol extracts and also total cell extracts in L02. siRNAs for VDR were used to determine the role of VDR in protecting 8-MOP-induced cholestasis and potential cellular mechanisms. The results showed 8-MOP could affect the CYP7A1, SHP and MRP3 expression via VDR, and such effects could be reversed by knockdown of VDR expression, suggesting a vital role of VDR involved in 8-MOP-regulated bile acid synthesis and transportation. In conclusion, these results revealed activation of VD–VDR axis may play a beneficial role in 8-MOP-mediated regulation of bile acid synthesis and transportation.

NGM282 for Treatment of Patients With Primary Biliary Cholangitis: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial.

Patients with primary biliary cholangitis (PBC) who had an inadequate response to ursodiol have few treatment options. Alkaline phosphatase (ALP) and bilirubin levels correlate with the risk of liver transplant or death in PBC patients. Fibroblast growth factor (FGF) 19 is a hormone that acts directly in the liver to regulate bile acid synthesis. We evaluated NGM282, an engineered analogue of FGF19, for the treatment of PBC. In this 28‐day, double‐blind, placebo‐controlled phase 2 trial, 45 PBC patients who had an inadequate response to ursodiol were randomly assigned 1:1:1 to receive subcutaneous daily doses of either NGM282 at 0.3 mg (n = 14), 3 mg (n = 16), or placebo (n = 15). The primary endpoint was a change in ALP from baseline after 28 days of treatment. At day 28, ALP was significantly reduced with NGM282 treatment at both 0.3 mg (least‐squares mean –51.0 IU/L [standard error (SE) 15.4]) and 3 mg (–66.0 IU/L [SE 16.0]) versus placebo (3.3 IU/L [SE 14.8]), with least‐squares mean differences of –54.3 IU/L (95% confidence interval –104.2 to –4.5; P = 0.0149) and –69.3 IU/L (95% confidence interval –120.5 to –18.3; P = 0.0030), respectively. Fifty percent (7 of 14) of patients receiving NGM282 0.3 mg and 46% (6 of 13) of those receiving NGM282 3mg achieved 15% or greater reduction in ALP levels from baseline, compared with 7% (1 of 15) of patients receiving placebo. NGM282 also significantly reduced serum concentrations of transaminases and immunoglobulins. Most adverse events were grade 1 (mild) to grade 2 (moderate) in severity, with gastrointestinal disorders more frequent in the NGM282 treatment groups. No worsening of pruritus was observed with NGM282 treatment. Conclusion: NGM282 administered for 28 days resulted in significant improvements in ALP and transaminase levels compared with placebo, with an acceptable safety profile in patients with PBC. (Hepatology Communications 2018; 00:000‐000)

Peroxisome Proliferator-Activated Receptor-γ Prevents Cholesterol Gallstone Formation in C57bl Mice by Regulating Bile Acid Synthesis and Enterohepatic Circulation.

To investigate the role of the peroxisome proliferator-activated receptor-γ (PPARγ) in the progression of cholesterol gallstone disease (CGD), C57bl/6J mice were randomized to the following groups (n=7/group): L (lithogenic diet, LGD), LM (LGD+pioglitazone), CM (chow diet+pioglitazone), and NC (normal control, chow diet). Gallbladder stones were observed by microscopy. Histological gallbladder changes were assessed. Bile acids (BA) and cholesterol were measured in the serum, bile, and feces. Proteins and mRNA expression of genes involved in BA metabolism and enterohepatic circulation were assessed by western blotting and real-time RT-PCR. PPARγ activation was performed in LO2 cell by lentivirus transfection and in Caco2 cell by PPARγ agonist treatment. Downregulation of farnesoid X receptor (FXR) by small interference RNA (siRNA) was performed in L02 cells and Caco2 cells, respectively. Results showed that pharmacological activation of PPARγ by pioglitazone prevents cholesterol gallstone formation by increasing biliary BA synthesis and enterohepatic circulation. Activated PPARγ induced the expression of genes involved in enterohepatic circulation and bile acid synthesis (like PCG1α, BSEP, MRP2, MRP3, MRP4, NTCP, CYP7A1, CYP27A1, ASBT, OSTα, and OSTβ). Downregulation of FXR repressed expression of partial genes involved in BA enterohepatic circulation. These findings suggest a new function of PPARγ in preventing CGD by handling BA synthesis and transport through a FXR dependent or independent pathway.