Prednisolone increases enterohepatic cycling of bile acids by induction of Asbt and promotes reverse cholesterol transport

Exploring bile acid transporters as key players in cancer development and treatment: Evidence from preclinical and clinical studies

Bile acid transporters (BATs) are integral membrane proteins belonging to various families, such as solute carriers, organic anion transporters, and ATP-binding cassette families. These transporters play a crucial role in bile acid transportation within the portal and systemic circulations, with expression observed in tissues, including the liver, kidney, and small intestine. Bile acids serve as signaling molecules facilitating the absorption and reabsorption of fats and lipids. Dysregulation of bile acid concentration has been implicated in tumorigenesis, yet the role of BATs in this process remains underexplored. Emerging evidence suggests that BATs may modulate various stages of cancer progression, including initiation, development, proliferation, metastasis, and tumor microenvironment regulation. Targeting BATs using siRNAs, miRNAs, and small compound inhibitors in preclinical models and their polymorphisms are well-studied for transporters like BSEP, MDR1, MRP2, OATP1A2, etc., and have shed light on their involvement in tumorigenesis, particularly in cancers such as those affecting the liver and gastrointestinal tract. While BATs' role in diseases like Alagille syndrome, biliary atresia, and cirrhosis have been extensively studied, their implications in cancer warrant further investigation. This review highlights the expression and function of BATs in cancer development and emphasizes the potential of targeting these transporters as a novel therapeutic strategy for various malignancies.

Exploring potential plasma drug targets for cholelithiasis through multiancestry Mendelian randomization

BACKGROUND

Cholelithiasis poses significant health and economic burdens, necessitating novel pharmacological targets to enhance treatment efficacy.

METHOD

Based on genome-wide association analysis studies, the authors performed a two-sample Mendelian randomization (MR) analysis based on plasma proteomics to explore potential drug targets in European (n Case =40 191 and n Control =361 641) and Asian (n Case =9305 and n Control =168 253) populations. The authors confirmed the directionality and robust correlation of the drug targets with the results through reverse MR analysis, Steiger filtering, Bayesian colocalization, phenotype scanning, and replication in multiple databases. Further exploration of the safety and possible mechanisms of action of phenome-wide MR analysis and protein-protein interactions (PPIs) as individual drug targets was performed.

RESULTS

Our proteomics-based MR analyses suggested that FUT3 (OR=0.87; 95% CI: 0.84-0.89; P =4.70×10 -32 ), NOE1 (OR=0.58; 95% CI: 0.52-0.66; P =4.21×10 -23 ), UGT1A6 (OR=0.68; 95% CI: 0.64-0.73; P =9.58×10 -30 ), and FKBP52 (OR=1.75; 95% CI: 1.37-2.24; P =8.61×10 -6 ) were potential drug targets in Europeans, whereas KLB (OR=1.11; 95% CI: 1.07-1.16; P =7.59×10 -7 ) and FGFR4 (OR=0.94; 95% CI: 0.91-0.96; P =4.07×10 -6 ) were valid targets in East Asians. There was no reverse causality for these drug targets. Evidence from Bayesian colocalization analyses supported that exposure and outcome shared consistent genetic variables. Phenome-wide MR analysis suggested the potential deleterious effects of NOE1 and FGFR4. PPI analysis confirmed the pathways associated with the potential targets involved in bile acid metabolism.

CONCLUSIONS

Genetically predicted levels of the plasma proteins FUT3, NOE1, UGT1A6, and FKBP52 have the potential as prospective targets in Europeans. Moreover, the plasma levels of KLB and FGFR4 may serve as potential targets for the treatment of cholelithiasis in East Asians.

Development of novel liver-targeting glucocorticoid prodrugs

Background

Glucocorticoids (GCs) are widely used in the treatment of inflammatory liver diseases and sepsis, but GC's various side effects on extrahepatic tissues limit their clinical benefits. Liver-targeting GC therapy may have multiple advantages over systemic GC therapy. The purpose of this study was to develop novel liver-targeting GC prodrugs as improved treatment for inflammatory liver diseases and sepsis.

Methods

A hydrophilic linker or an ultra-hydrophilic zwitterionic linker carboxylic betaine (CB) was used to bridge cholic acid (CA) and dexamethasone (DEX) to generate transporter-dependent liver-targeting GC prodrugs CA-DEX and the highly hydrophilic CA-CB-DEX. The efficacy of liver-targeting DEX prodrugs and DEX were determined in primary human hepatocytes (PHH), macrophages, human whole blood, and/or mice with sepsis induced by cecal ligation and puncture.

Results

CA-DEX was moderately water soluble, whereas CA-CB-DEX was highly water soluble. CA-CB-DEX and CA-DEX displayed highly transporter-dependent activities in reporter assays. Data mining found marked dysregulation of many GR-target genes important for lipid catabolism, cytoprotection, and inflammation in patients with severe alcoholic hepatitis. These key GR-target genes were similarly and rapidly (within 6 h) induced or down-regulated by CA-CB-DEX and DEX in PHH. CA-CB-DEX had much weaker inhibitory effects than DEX on endotoxin-induced cytokines in mouse macrophages and human whole blood. In contrast, CA-CB-DEX exerted more potent anti-inflammatory effects than DEX in livers of septic mice.

Conclusions

CA-CB-DEX demonstrated good hepatocyte-selectivity in vitro and better anti-inflammatory effects in vivo. Further test of CA-CB-DEX as a novel liver-targeting GC prodrug for inflammatory liver diseases and sepsis is warranted.

Altered lipid metabolism in patients with acute graft-versus-host disease after allogeneic hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (allo-HCT) remains the sole curative option for many hematological malignancies and other diseases. Nevertheless, its application is limited due to the risk of life-threatening complications, mainly graft-versus-host disease (GVHD). Currently, in clinical practice, the risk of developing GVHD is estimated for every patient based on factors related to the donor and the host. In our prospective, observational study, we analyzed serum from 38 patients undergoing allo-HCT at our institution. We compared the metabolic profiles of patients who developed acute GVHD (aGVHD) with those without such complication by identification and comparison of metabolites masses on the XCMS platform. We observed that patients diagnosed with aGVHD had different metabolic profiles compared to the remaining patients and this alteration was noticeable already 7 days before the procedure. We identified dysregulated metabolites involved in bile acid transformation and cholesterol synthesis. Our study of the untargeted metabolome in allo-HCT recipients has revealed a potential link between lipid metabolism, specifically involving bile acid transformation and cholesterol synthesis, and the development of aGVHD. This finding might be an important indication for future research focused on understanding GVHD development, discovering prediction models, and investigating possible prophylactic interventions.

Altered fecal bile acid composition in active ulcerative colitis

BACKGROUND

Disturbed bile acid homeostasis associated with a rise of primary and a decline of secondary bile acids is a consistent finding in inflammatory bowel diseases (IBDs). Whether fecal bile acids may emerge as biomarkers for IBD diagnosis and disease severity is less clear. Our study aimed to identify associations of 18 fecal bile acid species with IBD entity and disease activity.

METHODS

Stool samples of 62 IBD patients and 17 controls were collected. Eighteen fecal bile acid species were quantified by LC-MS/MS using stable isotope dilution. Lipid levels normalized to a dry weight of the fecal homogenates and ratios of single bile acid species to total bile acid levels were used for calculations.

RESULTS

IBD patients exhibited altered primary and secondary bile acid ratios in stool, with notable distinctions between ulcerative colitis (UC) compared to Crohn's disease (CD) and healthy controls. Fecal calprotectin was negatively correlated with glycolithocholic acid (GLCA) and hyodeoxycholic acid (HDCA) in UC. These bile acids were reduced in stool of UC patients with fecal calprotectin levels > 500 µg/g compared to UC patients with low calprotectin levels. Moreover, negative associations of six secondary bile acids with C-reactive protein (CRP) existed in UC. In CD patients, fecal bile acids did not correlate with CRP or fecal calprotectin. Diarrhoea is common in IBD, and UC patients with diarrhoea had reduced deoxycholic acid (DCA), glycine conjugated DCA (GDCA) and lithocholic acid in stool in contrast to patients with normal stool consistency. Fecal bile acid levels were not associated with diarrhoea in CD patients. UC patients treated with mesalazine had increased levels of fecal GDCA whereas no such changes were observed in CD patients. Bile acid levels of CD and UC patients treated with biologicals or corticosteroids did not change. Relative levels of GHDCA (specificity: 79%, sensitivity: 67%) and glycochenodeoxycholic acid (specificity: 74%, sensitivity: 63%) were the most specific to distinguish UC from CD.

CONCLUSION

Disrupted fecal bile acid homeostasis is associated with disease severity and disease symptoms in UC but not in CD, potentially aiding in distinguishing IBD subtypes and classifying the pathophysiology of diarrhoea in UC.

Treatment of ursodeoxycholic acid with glucocorticoids and immunosuppressants may improve the long-term survival rate in primary biliary cholangitis patients

Primary biliary cholangitis (PBC) is an autoimmune cholestatic liver disease. The clinical effectiveness of ursodeoxycholic acid (UDCA) plus glucocorticoids and/or immunosuppressants remains controversial in PBC patients. The study aimed to compare the efficacy of monotherapy and combination therapy in patients with PBC and to assess the factors affecting the efficacy. In this retrospective study, 266 patients diagnosed with PBC were divided into monotherapy group (UDCA), double therapy group (UDCA plus glucocorticoids or immunosuppressants), and triple therapy group (UDCA plus glucocorticoids and immunosuppressants) according to different treatments. Demographic characteristics, immune parameters, biochemistry profiles, and other indicators were evaluated at baseline, 6 months, and 1 year following treatment. The prognosis was evaluated using the Paris II standard. The liver transplant-free survival at 3, 5, 10, and 15 years was predicted by GLOBE score. All statistical analyses were conducted using SPSS (version 24) software (SPSS Inc, Chicago, IL). The long-term survival rate of the triple therapy group was significantly improved compared with the monotherapy group (P = .005). In addition, multivariate analysis showed that abnormal platelet count, alkaline phosphatase, and albumin levels were risk factors for poor response. When IgG levels were elevated but below twice the upper limit of normal, the clinical benefit was not significant compared with monotherapy (P > .05). Compared with monotherapy and double therapy, triple therapy may improve the long-term survival rate of PBC patients. Abnormal platelet count, alkaline phosphatase, and albumin levels were associated with a poor prognosis.

Narrative Review: Glucocorticoids in Alcoholic Hepatitis—Benefits, Side Effects, and Mechanisms

Alcoholic hepatitis is a major health and economic burden worldwide. Glucocorticoids (GCs) are the only first-line drugs recommended to treat severe alcoholic hepatitis (sAH), with limited short-term efficacy and significant side effects. In this review, I summarize the major benefits and side effects of GC therapy in sAH and the potential underlying mechanisms. The review of the literature and data mining clearly indicate that the hepatic signaling of glucocorticoid receptor (GR) is markedly impaired in sAH patients. The impaired GR signaling causes hepatic down-regulation of genes essential for gluconeogenesis, lipid catabolism, cytoprotection, and anti-inflammation in sAH patients. The efficacy of GCs in sAH may be compromised by GC resistance and/or GC’s extrahepatic side effects, particularly the side effects of intestinal epithelial GR on gut permeability and inflammation in AH. Prednisolone, a major GC used for sAH, activates both the GR and mineralocorticoid receptor (MR). When GC non-responsiveness occurs in sAH patients, the activation of MR by prednisolone might increase the risk of alcohol abuse, liver fibrosis, and acute kidney injury. To improve the GC therapy of sAH, the effort should be focused on developing the biomarker(s) for GC responsiveness, liver-targeting GR agonists, and strategies to overcome GC non-responsiveness and prevent alcohol relapse in sAH patients.

Impaired Bile Acid Metabolism and Gut Dysbiosis in Mice Lacking Lysosomal Acid Lipase

Lysosomal acid lipase (LAL) is the sole enzyme known to be responsible for the hydrolysis of cholesteryl esters and triglycerides at an acidic pH in lysosomes, resulting in the release of unesterified cholesterol and free fatty acids. However, the role of LAL in diet-induced adaptations is largely unexplored. In this study, we demonstrate that feeding a Western-type diet to Lal-deficient (LAL-KO) mice triggers metabolic reprogramming that modulates gut-liver cholesterol homeostasis. Induction of ileal fibroblast growth factor 15 (three-fold), absence of hepatic cholesterol 7α-hydroxylase expression, and activation of the ERK phosphorylation cascade results in altered bile acid composition, substantial changes in the gut microbiome, reduced nutrient absorption by 40%, and two-fold increased fecal lipid excretion in LAL-KO mice. These metabolic adaptations lead to impaired bile acid synthesis, lipoprotein uptake, and cholesterol absorption and ultimately to the resistance of LAL-KO mice to diet-induced obesity. Our results indicate that LAL-derived lipolytic products might be important metabolic effectors in the maintenance of whole-body lipid homeostasis.

Congenital gallbladder agenesis in a 9-month-old Bull Terrier

Congenital gallbladder agenesis is an extremely rare disorder, which has, to the best of our knowledge, only been reported in seventeen dogs (mainly in Japan). In almost all of these cases, gallbladder agenesis or hypoplasia was detected in small dogs. In this report, we present a case of gallbladder agenesis in a 9-month-old intact female Bull Terrier. The clinical signs included diarrhoea, sporadic vomiting, apathy and decreased appetite. The serum biochemistry revealed an increased liver enzyme activity, an increased concentration of serum bile acids and mild hyperbilirubinaemia. A diagnostic laparotomy demonstrated the lack of a gallbladder and dilation of the common bile duct, which was misinterpreted as the gallbladder in the ultrasonographic examination. The histological examination of the liver revealed degenerative changes in the hepatocytes with glycogen accumulation and some necrotic hepatocytes. The therapy included a low protein diet, fluids, silymarin and ursodeoxycholic acid. After nine weeks of therapy, the dog was in good condition, the diarrhoea and vomiting ceased, and the liver function parameters, such as the AST and GLDH activities, and the concentration of bile acids had decreased to reference intervals.

Stress can attenuate hepatic lipid accumulation via elevation of hepatic β-muricholic acid levels in mice with nonalcoholic steatohepatitis

Stress can affect our body and is known to lead to some diseases. However, the influence on the development of nonalcohol fatty liver disease (NAFLD) remains unknown. This study demonstrated that chronic restraint stress attenuated hepatic lipid accumulation via elevation of hepatic β-muricholic acid (βMCA) levels in the development of nonalcoholic steatohepatitis (NASH) in mice. Serum cortisol and corticosterone levels, i.e., human and rodent stress markers, were correlated with serum bile acid levels in patients with NAFLD and methionine- and choline-deficient (MCD) diet-induced mice, respectively, suggesting that stress is related to bile acid (BA) homeostasis in NASH. In the mouse model, hepatic βMCA and cholic acid (CA) levels were increased after the stress challenge. Considering that a short stress enhanced hepatic CYP7A1 protein levels in normal mice and corticosterone increased CYP7A1 protein levels in primary mouse hepatocytes, the enhanced Cyp7a1 expression was postulated to be involved in the chronic stress-increased hepatic βMCA level. Interestingly, chronic stress decreased hepatic lipid levels in MCD-induced NASH mice. Furthermore, βMCA suppressed lipid accumulation in mouse primary hepatocytes exposed to palmitic acid/oleic acid, but CA did not. In addition, Cyp7a1 expression seemed to be related to lipid accumulation in hepatocytes. In conclusion, chronic stress can change hepatic lipid accumulation in NASH mice, disrupting BA homeostasis via induction of hepatic Cyp7a1 expression. This study discovered a new βMCA action in the liver, indicating the possibility that βMCA is available for NAFLD therapy.

Altered bile acid kinetics contribute to postprandial hypoglycaemia after Roux-en-Y gastric bypass surgery

BACKGROUND/OBJECTIVES

Bile acids (BA) act as detergents in intestinal fat absorption and as modulators of metabolic processes via activation of receptors such as FXR and TGR5. Elevated plasma BA as well as increased intestinal BA signalling to promote GLP-1 release have been implicated in beneficial health effects of Roux-en-Y gastric bypass surgery (RYGB). Whether BA also contribute to the postprandial hypoglycaemia that is frequently observed post-RYGB is unknown.

METHODS

Plasma BA, fibroblast growth factor 19 (FGF19), 7α-hydroxy-4-cholesten-3-one (C4), GLP-1, insulin and glucose levels were determined during 3.5 h mixed-meal tolerance tests (MMTT) in subjects after RYGB, either with (RYGB, n = 11) or without a functioning gallbladder due to cholecystectomy (RYGB-CC, n = 11). Basal values were compared to those of age, BMI and sex-matched obese controls without RYGB (n = 22).

RESULTS

Fasting BA as well as FGF19 levels were elevated in RYGB and RYGB-CC subjects compared to non-bariatric controls, without significant differences between RYGB and RYGB-CC. Postprandial hypoglycaemia was observed in 8/11 RYGB-CC and only in 3/11 RYGB. Subjects who developed hypoglycaemia showed higher postprandial BA levels coinciding with augmented GLP-1 and insulin responses during the MMTT. The nadir of plasma glucose concentrations after meals showed a negative relationship with postprandial BA peaks. Plasma C4 was lower during MMTT in subjects experiencing hypoglycaemia, indicating lower hepatic BA synthesis. Computer simulations revealed that altered intestinal transit underlies the occurrence of exaggerated postprandial BA responses in hypoglycaemic subjects.

CONCLUSION

Altered BA kinetics upon ingestion of a meal, as frequently observed in RYGB-CC subjects, appear to contribute to postprandial hypoglycaemia by stimulating intestinal GLP-1 release.

Biliary atresia: Potential for a new decade

Biliary atresia is characterised as an obliterative cholangiopathy of both extra-and intra-hepatic bile ducts. There is marked aetiological heterogeneity with a number of different variants, some syndromic and others perhaps virally-mediated. Current research aims to try and define possible mechanisms and pathogenesis though an actual breakthrough remains elusive. There has been little in the way of surgical advances beyond subtle variations in the Kasai portoenterostomy and laparoscopic equivalents have no declared advantage and have yet to prove equivalence in measures of outcome. The next target has been to maximise potential with better adjuvant therapy, though the evidence base for most currently available therapies such as steroids and ursodeoxycholic acid remains limited. Still high-dose steroid use is widespread, certainly in Europe and the Far East. Clearance of jaundice can be achieved in 50-60% of those subjected to portoenterostomy at <70 days and should be an achievable benchmark. Transplantation is a widely available "rescue" therapy though whether it should be an alternative as a primary procedure is arguable but becoming increasingly heard. The aim of clinical practice remains to get these infants for surgery as early as is possible though this can be difficult to accomplish in practice, and "low-cost" screening projects using stool colour charts have been limited outside of Taiwan and Japan. Centralisation of resources (medical and surgical) is associated with a diminution of time to portoenterostomy but application has been limited by entrenched health delivery models or geographical constraints.

Glucocorticoids regulate AKR1D1 activity in human liver in vitro and in vivo

Steroid 5β-reductase (AKR1D1) is highly expressed in human liver where it inactivates endogenous glucocorticoids and catalyses an important step in bile acid synthesis. Endogenous and synthetic glucocorticoids are potent regulators of metabolic phenotype and play a crucial role in hepatic glucose metabolism. However, the potential of synthetic glucocorticoids to be metabolised by AKR1D1 as well as to regulate its expression and activity has not been investigated. The impact of glucocorticoids on AKR1D1 activity was assessed in human liver HepG2 and Huh7 cells; AKR1D1 expression was assessed by qPCR and Western blotting. Genetic manipulation of AKR1D1 expression was conducted in HepG2 and Huh7 cells and metabolic assessments were made using qPCR. Urinary steroid metabolite profiling in healthy volunteers was performed pre- and post-dexamethasone treatment, using gas chromatography-mass spectrometry. AKR1D1 metabolised endogenous cortisol, but cleared prednisolone and dexamethasone less efficiently. In vitro and in vivo, dexamethasone decreased AKR1D1 expression and activity, further limiting glucocorticoid clearance and augmenting action. Dexamethasone enhanced gluconeogenic and glycogen synthesis gene expression in liver cell models and these changes were mirrored by genetic knockdown of AKR1D1 expression. The effects of AKR1D1 knockdown were mediated through multiple nuclear hormone receptors, including the glucocorticoid, pregnane X and farnesoid X receptors. Glucocorticoids down-regulate AKR1D1 expression and activity and thereby reduce glucocorticoid clearance. In addition, AKR1D1 down-regulation alters the activation of multiple nuclear hormone receptors to drive changes in gluconeogenic and glycogen synthesis gene expression profiles, which may exacerbate the adverse impact of exogenous glucocorticoids.

Intestinal Absorption of Bile Acids in Health and Disease

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

Prednisone and Its Active Metabolite Prednisolone Attenuate Lipid Accumulation in Macrophages

BACKGROUND

Synthetic forms of glucocorticoids (GCs; eg, prednisone, prednisolone) are anti-inflammatory drugs that are widely used in clinical practice. The role of GCs in cardiovascular diseases, including atherosclerosis, is highly controversial, and their impact on macrophage foam cell formation is still unknown. We investigated the effects of prednisone and prednisolone on macrophage oxidative stress and lipid metabolism.

METHODS AND RESULTS

C57BL/6 mice were intraperitoneally injected with prednisone or prednisolone (5 mg/kg) for 4 weeks, followed by lipid metabolism analyses in the aorta and peritoneal macrophages. We also analyzed the effect of serum samples obtained from 9 healthy human volunteers before and after oral administration of prednisone (20 mg for 5 days) on J774A.1 macrophage atherogenicity. Finally, J774A.1 macrophages, human monocyte-derived macrophages, and fibroblasts were incubated with increasing concentrations (0-200 ng/mL) of prednisone or prednisolone, followed by determination of cellular oxidative status, and triglyceride and cholesterol metabolism. Prednisone and prednisolone treatment resulted in a significant reduction in triglyceride and cholesterol accumulation in macrophages, as observed in vivo, ex vivo, and in vitro. These effects were associated with GCs' inhibitory effect on triglyceride- and cholesterol-biosynthesis rates, through downregulation of diacylglycerol acyltransferase 1 and HMG-CoA reductase expression. Glucocorticoid-induced reduction of cellular lipid accumulation was mediated by the GC receptors on the macrophages, because the GC-receptor antagonist (RU486) abolished these effects. In fibroblasts, unlike macrophages, GCs showed no effects.

CONCLUSION

Prednisone and prednisolone exhibit antiatherogenic activity by protecting macrophages from lipid accumulation and foam cell formation.

Effect of combined ursodeoxycholic acid and glucocorticoid on the outcome of Kasai procedure: A systematic review and meta-analysis

INTRODUCTION

Multiple studies have investigated the effect of ursodeoxycholic acid (UDCA) or glucocorticoid (GC) on the outcome of the hepatoportoenterostomy (Kasai procedure) in patients with biliary atresia (BA). However, the combined effect of these drugs (UDCA + GC) is little understood.

METHODS

This meta-analysis specifically evaluated the effect of UDCA + GC after the Kasai procedure in patients with BA. A comprehensive literature search was conducted for all relevant articles in the electronic databases Medline, PubMed, Cochrane, Excerpta Medica Database (EMBASE), China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database on Disc (CBM-disc), and Vendor Information Pages (VIP).

RESULTS

Eight studies with BA patients were finally included in our meta-analysis. The 8 identified studies consisted of 3 case-control, 3 cohort, and 2 randomized controlled trials (RCTs) with overall 530 subjects (144, 152, and 234 subjects, respectively). Among them, 312 patients were treated with UDCA + GC, while 218 received placebo or other intervention. The meta-analysis indicated that groups that received UDCA + GC had significantly lower rates of postoperative jaundice relative to the controls (pooled, odds ratio [OR] = 2.41; 95% confidence interval [CI] 1.44-4.04; Z = 3.34; P = .0008), while rates of cholangitis were similar (pooled, OR = 0.87; 95% CI 0.43-1.74; Z = 0.40; P = .69).

CONCLUSIONS

Combined UDCA and GC intervention was superior to that of the control in accelerating the clearance of serum bilirubin in patients with BA after the Kasai procedure. However, this conclusion requires further confirmation using RCTs of high methodological quality.

Interaction of glucocorticoids with FXR/FGF19/FGF21-mediated ileum-liver crosstalk

At high doses, glucocorticoids (GC) have been associated with enhanced serum bile acids and liver injury. We have evaluated the effect of GC, in the absence of hepatotoxicity, on FXR/FGF91(Fgf15)/FGF21-mediated ileum-liver crosstalk. Rats and mice (wild type and Fxr^-/-, Fgf15^-/- and int-Gr^-/- strains; the latter with GC receptor (Gr) knockout selective for intestinal epithelial cells), were treated (i.p.) with dexamethasone, prednisolone or budesonide. In both species, high doses of GC caused hepatotoxicity. At a non-hepatotoxic dose, GC induced ileal Fgf15 down-regulation and liver Fgf21 up-regulation, without affecting Fxr expression. Fgf21 mRNA levels correlated with those of several genes involved in glucose and bile acid metabolism. Surprisingly, liver Cyp7a1 was not up-regulated. The expression of factors involved in transcriptional modulation by Fxr and Gr (p300, Drip205, CBP and Smrt) was not affected. Pxr target genes Cyp3a11 and Mrp2 were not up-regulated in liver or intestine. In contrast, the expression of some Pparα target genes in liver (Fgf21, Cyp4a14 and Vanin-1) and intestine (Vanin-1 and Cyp3a11) was altered. In mice with experimental colitis, liver Fgf21 was up-regulated (4.4-fold). HepG2 cells transfection with FGF21 inhibited CYP7A1 promoter (prCYP7A1-Luc2). This was mimicked by pure human FGF21 protein or culture in medium previously conditioned by cells over-expressing FGF21. This response was not abolished by deletion of a putative response element for phosphorylated FGF21 effectors present in prCYP7A1. In conclusion, GC interfere with FXR/FGF19-mediated intestinal control of CYP7A1 expression by the liver and stimulate hepatic secretion of FGF21, which inhibits CYP7A1 promoter through an autocrine mechanism.

Adjuvant therapy in biliary atresia: hopelessly optimistic or potential for change?

Given that the aetiology of biliary atresia (BA) is complex and that there is a multiplicity of possible pathogenic mechanisms then it is perhaps not surprising that the evidence for effect of a number of different agents is contradictory. Post-operative cholangitis for instance is common, bacterial in origin and various antibiotic regimens have been tested (although none in a randomized trial) but continuation beyond the early post-operative period does not appear to offer any greater protection. There is an inflammatory reaction in about 25-35% of cases of BA illustrated by abnormal expression of class II antigen and upregulation of ICAM, VCAM and E-selectin with an infiltrate of immune-activated T cells (predominantly CD4 + Th1 and Th17) and NK cells and a systemic surge in inflammatory cytokines (e.g. TNF-α, IL-2, IL-12). This has potential as a therapeutic target and is the main hypothesis behind the rationale use of steroids. The first report of steroids was published in 1985 by Karrer and Lilly as "blast" therapy to treat recalcitrant cholangitis, followed by a multiplicity of small-scale uncontrolled studies suggesting benefit. To date there has been one randomized placebo-controlled study with a low-dose (prednisolone 2 mg/kg/day) regimen (2007); one with a high-dose (IV prednisolone 4 mg/kg/day regimen) (2014); two prospective high-dose open-label studies (2013); a prospective comparison of low- and high-dose regimen and a large (380 infants) retrospective comparison. The most recent meta-analysis (2016) identified a significant difference in clearance of jaundice at 6 months (OR 1.59, 95% CI 1.03-2.45, P = 0.04), in patients treated with high-dose steroids, particularly if < 70 days at surgery. Ursodeoxycholic acid (UDCA) may increase choleresis or change the ratio of endogenous bile acids to a less hydrophobic and, therefore, less toxic millieu. UDCA may protect cholangiocyte membranes against damage and perhaps reduce the tendency to fibrogenesis. Biochemical benefit has been shown in a single crossover trial in older BA children who had cleared their jaundice. Other potential adjuvant therapies include immunoglobulin therapy, anti-viral agents and Chinese herbs although real evidence of benefit is lacking.

An important intestinal transporter that regulates the enterohepatic circulation of bile acids and cholesterol homeostasis: The apical sodium-dependent bile acid transporter (SLC10A2/ASBT)

The enterohepatic circulation of bile acids (BAs) is governed by specific transporters expressed in the liver and the intestine and plays a critical role in the digestion of fats and oils. During this process, the majority of the BAs secreted from the liver is reabsorbed in intestinal epithelial cells via the apical sodium-dependent bile acid transporter (ASBT/SLC10A2) and then transported into the portal vein. Previous studies revealed that regulation of the ASBT involves BAs and cholesterol. In addition, abnormal ASBT expression and function might lead to some diseases associated with disorders in the enterohepatic circulation of BAs and cholesterol homeostasis, such as diarrhoea and gallstones. However, decreasing cholesterol or BAs by partly inhibiting ASBT-mediated transport might be used for treatments of hypercholesterolemia, cholestasis and diabetes. This review mainly discusses the regulation of the ASBT by BAs and cholesterol and its relevance to diseases and treatment.

Formula Feeding Predisposes Gut to NSAID-Induced Small Intestinal Injury

Objectives

Breast feeding protects infants from many diseases, including necrotizing enterocolitis, peptic ulceration and infectious diarrhea. Conversely, maternal separation stress and Non-Steroidal Anti-Inflammatory Drugs (NSAID's) can induce intestinal injury and bleeding. This study aimed to evaluate in suckling rats if maternal separation/formula feeding leads to increased intestinal sensitivity to indomethacin (indo)-induced intestinal injury and to look at potential mechanisms involved.

Methods

Nine-day-old rats were dam-fed or separated/trained to formula-feed for 6 days prior to indo administration (5 mg/kg/day) or saline (control) for 3 days. Intestinal bleeding and injury were assessed by measuring luminal and Fecal Hemoglobin (Hob) and jejunal histology. Maturation of the intestine was assessed by measuring luminal bile acids, jejunal sucrase, serum corticosterone, and mRNA expression of ileal Apical Sodium-Dependent Bile Acid Transporter (ASBT).

Results

At 17 days, formula-fed indo-treated pups had a 2-fold increase in luminal Hb compared to formula-fed control pups and had evidence of morphological injury to the small intestinal mucosa as observed at the light microscopic level, whereas indo had no effect on dam-fed littermates. In addition, formula-fed rats had significant increases in luminal bile acid, sucrase specific activity, serum corticosterone, and expression of ASBT mRNA compared to dam-fed rats.

Conclusion

Maternal separation stress may cause early intestinal maturational changes induced by corticosteroid release, including increased epithelial exposure to bile acids. These maturational changes may have a sensitizing rather than protective effect against indo-induced injury in the new-born.

Oral treatment with Eubacterium hallii improves insulin sensitivity in db/db mice

An altered intestinal microbiota composition is associated with insulin resistance and type 2 diabetes mellitus. We previously identified increased intestinal levels of Eubacterium hallii, an anaerobic bacterium belonging to the butyrate-producing Lachnospiraceae family, in metabolic syndrome subjects who received a faecal transplant from a lean donor. To further assess the effects of E. hallii on insulin sensitivity, we orally treated obese and diabetic db/db mice with alive E. hallii and glycerol or heat-inactive E. hallii as control. Insulin tolerance tests and hyperinsulinemic-euglycemic clamp experiments revealed that alive E. hallii treatment improved insulin sensitivity compared control treatment. In addition, E. hallii treatment increased energy expenditure in db/db mice. Active E. hallii treatment was found to increase faecal butyrate concentrations and to modify bile acid metabolism compared with heat-inactivated controls. Our data suggest that E. hallii administration potentially alters the function of the intestinal microbiome and that microbial metabolites may contribute to the improved metabolic phenotype.

Glucocorticoid treatment alters systemic bile acid homeostasis by regulating the biosynthesis and transport of bile salts

BACKGROUND

Dysregulation of systemic bile acid homeostasis can lead to cholestatic liver diseases and metabolic syndromes. As important anti-inflammatory and immunosuppressive drugs, synthetic glucocorticoids (GCs) are used to treat several cholestatic disorders, including biliary atresia (BA), because of their effects on the regulation of bile acid metabolism. However, the molecular mechanisms that underlie GCs regulation of bile acid homeostasis remain unclear.

AIMS

To provide a mechanistic basis for the effects of GCs on bile acid homeostasis.

METHODS

Male rats were treated with methylprednisolone for 7 days with slow-release osmotic pumps under physiological and cholestatic status that was induced by bile duct ligation (BDL). Expression of glucocorticoid receptor (GR) and genes related to bile acid metabolism was investigated using western blotting, qRT-PCR and immunohistochemistry.

RESULTS

We show here that sustained treatment with GCs in rats disrupts the normal changes in systemic bile acid distribution by elevating plasma bile acid levels and reducing faecal bile acid loss. Treatment with GCs stimulated bile acid absorption in the ileum by increasing expression of the apical sodium-dependent bile acid transporter (Asbt). Concomitantly, administration of GCs enhanced liver bile acid uptake by increasing the expression of the major hepatocyte basolateral bile transporter (Ntcp). The reduced expression of a bile acid synthesis rate-controlling enzyme, Cyp7a1, suggests that treatment with GCs suppressed hepatic bile acid synthesis.

CONCLUSION

Our study provides evidence that GCs can increase enterohepatic bile acid circulation through regulation of the biosynthesis and transport of bile salts, which suggests that plasma bile acid levels should be monitored during treatment with GCs in patients with BA.

Rare Variants Association Analysis in Large-Scale Sequencing Studies at the Single Locus Level

Genetic association analyses of rare variants in next-generation sequencing (NGS) studies are fundamentally challenging due to the presence of a very large number of candidate variants at extremely low minor allele frequencies. Recent developments often focus on pooling multiple variants to provide association analysis at the gene instead of the locus level. Nonetheless, pinpointing individual variants is a critical goal for genomic researches as such information can facilitate the precise delineation of molecular mechanisms and functions of genetic factors on diseases. Due to the extreme rarity of mutations and high-dimensionality, significances of causal variants cannot easily stand out from those of noncausal ones. Consequently, standard false-positive control procedures, such as the Bonferroni and false discovery rate (FDR), are often impractical to apply, as a majority of the causal variants can only be identified along with a few but unknown number of noncausal variants. To provide informative analysis of individual variants in large-scale sequencing studies, we propose the Adaptive False-Negative Control (AFNC) procedure that can include a large proportion of causal variants with high confidence by introducing a novel statistical inquiry to determine those variants that can be confidently dispatched as noncausal. The AFNC provides a general framework that can accommodate for a variety of models and significance tests. The procedure is computationally efficient and can adapt to the underlying proportion of causal variants and quality of significance rankings. Extensive simulation studies across a plethora of scenarios demonstrate that the AFNC is advantageous for identifying individual rare variants, whereas the Bonferroni and FDR are exceedingly over-conservative for rare variants association studies. In the analyses of the CoLaus dataset, AFNC has identified individual variants most responsible for gene-level significances. Moreover, single-variant results using the AFNC have been successfully applied to infer related genes with annotation information.

Next-generation sequencing technologies have allowed genetic association studies of complex traits at the single base-pair resolution, where most genetic variants have extremely low mutation frequencies. These rare variants have been the focus of modern statistical-computational genomics due to their potential to explain missing disease heritability. The identification of individual rare variants associated with diseases can provide new biological insights and enable the precise delineation of disease mechanisms. However, due to the extreme rarity of mutations and large numbers of variants, significances of causative variants tend to be mixed inseparably with a few noncausative ones, and standard multiple testing procedures controlling for false positives fail to provide a meaningful way to include a large proportion of the causative variants. To address the challenge of detecting weak biological signals, we propose a novel statistical procedure, based on false-negative control, to provide a practical approach for variant inclusion in large-scale sequencing studies. By determining those variants that can be confidently dispatched as noncausative, the proposed procedure offers an objective selection of a modest number of potentially causative variants at the single-locus level. Results can be further prioritized or used to infer disease-associated genes with annotation information.

Sarcopenia in Advanced COPD Affects Cardiometabolic Risk Reduction by Short-Term High-intensity Pulmonary Rehabilitation

OBJECTIVES

Sarcopenia is common in chronic obstructive pulmonary disease (COPD) and may contribute to increased cardiometabolic risk. Interventions to reduce cardiometabolic risk in advanced COPD have been scarcely studied. We have investigated the cardiometabolic effect of a short-term high-intensity rehabilitation program in sarcopenic and nonsarcopenic patients with advanced COPD.

DESIGN

Prospective observational study.

SETTING

Inpatient 4-week short-term high-intensity pulmonary rehabilitation program at the University Clinic Golnik, Slovenia.

PARTICIPANTS

112 stable COPD patients (66 ± 8 years, 85% GOLD III/IV, 66% men).

MEASUREMENTS

Blood biomarkers were assessed at baseline and after rehabilitation. Sarcopenia was assessed at baseline (skeletal muscle index <7.23 kg/m(2) for men and <5.67 kg/m(2) for women, as measured by whole-body dual energy X-ray absorptiometry. Insulin resistance (IR) was defined as homeostasis model assessment of insulin resistance (HOMA-IR) above 2.5.

RESULTS

IR and sarcopenia were detected in 59% and 55% of patients, respectively. In contrast to sarcopenic patients, rehabilitation decreased HOMA-IR (2.8 to 1.9, P = .031), fat mass index (10.1 to 9.7 kg/m(2), P = .013), waist circumference (103 to 101 cm, P = .002), and low-density lipoprotein cholesterol (3.2 to 3.0 mmol/L, P = .034) in nonsarcopenic patients. A decrease in total cholesterol levels was observed in both groups.

CONCLUSIONS

Sarcopenia affects the modification of cardiometabolic risk markers by short-term high-intensity pulmonary rehabilitation in advanced COPD patients.

Chronic intermittent psychological stress promotes macrophage reverse cholesterol transport by impairing bile acid absorption in mice

Psychological stress is a risk factor for atherosclerosis, yet the pathophysiological mechanisms involved remain elusive. The transfer of cholesterol from macrophage foam cells to liver and feces (the macrophage-specific reverse cholesterol transport, m-RCT) is an important antiatherogenic pathway. Because exposure of mice to physical restraint, a model of psychological stress, increases serum levels of corticosterone, and as bile acid homeostasis is disrupted in glucocorticoid-treated animals, we investigated if chronic intermittent restraint stress would modify m-RCT by altering the enterohepatic circulation of bile acids. C57Bl/6J mice exposed to intermittent stress for 5 days exhibited increased transit through the large intestine and enhanced fecal bile acid excretion. Of the transcription factors and transporters that regulate bile acid homeostasis, the mRNA expression levels of the hepatic farnesoid X receptor (FXR), the bile salt export pump (BSEP), and the intestinal fibroblast growth factor 15 (FGF15) were reduced, whereas those of the ileal apical sodium-dependent bile acid transporter (ASBT), responsible for active bile acid absorption, remained unchanged. Neither did the hepatic expression of cholesterol 7α-hydroxylase (CYP7A1), the key enzyme regulating bile acid synthesis, change in the stressed mice. Evaluation of the functionality of the m-RCT pathway revealed increased fecal excretion of bile acids that had been synthesized from macrophage-derived cholesterol. Overall, our study reveals that chronic intermittent stress in mice accelerates m-RCT specifically by increasing fecal excretion of bile acids. This novel mechanism of m-RCT induction could have antiatherogenic potential under conditions of chronic stress.

Intestinal nuclear receptors in HDL cholesterol metabolism

The intestine plays a pivotal role in cholesterol homeostasis by functioning as an absorptive and secretory organ in the reverse cholesterol transport pathway. Enterocytes control cholesterol absorption, apoAI synthesis, HDL biogenesis, and nonbiliary cholesterol fecal disposal. Thus, intestine-based therapeutic interventions may hold promise in the management of diseases driven by cholesterol overload. Lipid-sensing nuclear receptors (NRs) are highly expressed in the intestinal epithelium and regulate transcriptionally the handling of cholesterol by the enterocytes. Here, we discuss the NR regulation of cholesterol fluxes across the enterocytes with special emphasis on NR exploitation as a bona fide novel HDL-raising strategy.