Bile Acids in Cholestasis and its Treatment

Differences in bile acid profiles between cholestatic diseases - Development of a high throughput assay for dried bloodspots

BACKGROUND

Cholestasis causes accumulation of bile acids (BAs) and changes the circulating bile acid profile. Quantification of circulating BAs in dried bloodspots (DBS) may demonstrate obstruction of bile flow and altered bile acid metabolism in the liver. High sample throughput enables rapid screening of cholestatic diseases.

MATERIALS AND METHODS

Ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was used for optimizing separation and detection of the primary unconjugated BAs cholic acid (CA) and chenodeoxycholic acid (CDCA); the secondary unconjugated BAs ursodeoxycholic acid (UDCA), hyodeoxycholic acid (HDCA) and deoxycholic acid (DCA), as well as the glycine- and taurine-conjugated variants of CA, CDCA, DCA and UDCA. Donor blood was obtained to prepare DBS calibrators and quality controls for method development and validation.

RESULTS

We developed a quantitative bile acid assay with a run-time of two minutes, and one-step sample preparation of 3.2 mm DBS discs. Validation results demonstrated overall good performance and was considered fit for purpose. Children with Alagille syndrome, Aagenaes syndrome and alpha-1 antitrypsin deficiency had increased BAs in DBS from newborn screening samples compared with age matched controls, and had different bile acids profiles.

CONCLUSION

We propose that our high throughput assay allows bile acid profiling in DBS that can be a valuable assessment tool for early screening of cholestasis in children. Assaying BAs in dried bloodspots is key for early detection of cholestasis, and provides transferability to a newborn screening setting.

Brain imaging in children with neonatal cholestatic liver disease: A systematic review

AIM

To determine if children with neonatal cholestatic liver disease had concurrent and later findings on brain imaging studies that could be attributed and the cholestasis to contribute to the understanding of the impaired neuropsychological development.

METHODS

Ovid MEDLINE and EMBASE were searched on July 21, 2022, and updated on March 26, 2023. Studies with children under 18 years of age with neonatal cholestasis and a brain scan at the time of diagnosis or later in life were included. Excluded studies were non-English, non-human, reviews or conference abstracts. Data were extracted on demographics, brain imaging findings, treatment and outcome. The results were summarised by disease categories. Risk of bias was assessed using JBI critical appraisal tools.

RESULTS

The search yielded 12 011 reports, of which 1261 underwent full text review and 89 were eligible for inclusion. Haemorrhage was the most common finding, especially in children with bile duct obstruction, including biliary atresia. Some findings were resolved after liver transplantation.

CONCLUSION

Children with neonatal cholestasis had changes in brain imaging, which might play a role in impaired neuropsychological development, but longitudinal clinical research with structured assessment is needed to better qualify the aetiology of the impairment.

The Effects of Aflatoxin B1 on Liver Cholestasis and Its Nutritional Regulation in Ducks

The aim of this study was to investigate the effects of aflatoxin B1 (AFB1) on cholestasis in duck liver and its nutritional regulation. Three hundred sixty 1-day-old ducks were randomly divided into six groups and fed for 4 weeks. The control group was fed a basic diet, while the experimental group diet contained 90 μg/kg of AFB1. Cholestyramine, atorvastatin calcium, taurine, and emodin were added to the diets of four experimental groups. The results show that in the AFB1 group, the growth properties, total bile acid (TBA) serum levels and total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and glutathione (GSH) liver levels decreased, while the malondialdehyde (MDA) and TBA liver levels increased (p < 0.05). Moreover, AFB1 caused cholestasis. Cholestyramine, atorvastatin calcium, taurine, and emodin could reduce the TBA serum and liver levels (p < 0.05), alleviating the symptoms of cholestasis. The qPCR results show that AFB1 upregulated cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and cytochrome P450 family 8 subfamily B member 1 (CYP8B1) gene expression and downregulated ATP binding cassette subfamily B member 11 (BSEP) gene expression in the liver, and taurine and emodin downregulated CYP7A1 and CYP8B1 gene expression (p < 0.05). In summary, AFB1 negatively affects health and alters the expression of genes related to liver bile acid metabolism, leading to cholestasis. Cholestyramine, atorvastatin calcium, taurine, and emodin can alleviate AFB1-induced cholestasis.

Glucocorticoid receptor-dependent therapeutic efficacy of tauroursodeoxycholic acid in preclinical models of spinocerebellar ataxia type 3

Spinocerebellar ataxia type 3 (SCA3) is an adult-onset neurodegenerative disease caused by a polyglutamine expansion in the ataxin-3 (ATXN3) gene. No effective treatment is available for this disorder, other than symptom-directed approaches. Bile acids have shown therapeutic efficacy in neurodegenerative disease models. Here, we pinpointed tauroursodeoxycholic acid (TUDCA) as an efficient therapeutic, improving the motor and neuropathological phenotype of SCA3 nematode and mouse models. Surprisingly, transcriptomic and functional in vivo data showed that TUDCA acts in neuronal tissue through the glucocorticoid receptor (GR), but independently of its canonical receptor, the farnesoid X receptor (FXR). TUDCA was predicted to bind to the GR, in a similar fashion to corticosteroid molecules. GR levels were decreased in disease-affected brain regions, likely due to increased protein degradation as a consequence of ATXN3 dysfunction being restored by TUDCA treatment. Analysis of a SCA3 clinical cohort showed intriguing correlations between the peripheral expression of GR and the predicted age at disease onset in presymptomatic subjects and FKBP5 expression with disease progression, suggesting this pathway as a potential source of biomarkers for future study. We have established a novel in vivo mechanism for the neuroprotective effects of TUDCA in SCA3 and propose this readily available drug for clinical trials in SCA3 patients.

Distinct bile acid alterations in response to a single administration of PFOA and PFDA in mice

Per- and polyfluoroalkyl substances (PFASs), a group of synthetic chemicals that were once widely used for industrial purposes and in consumer products, are widely found in the environment and in human blood due to their extraordinary resistance to degradation. Once inside the body, PFASs can activate nuclear receptors such as PPARα and CAR. The present study aimed to investigate the impact of perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA) on liver structure and functions, as well as bile acid homeostasis in mice. A single administration of 0.1 mmole/kg of PFDA, not PFOA, elevated serum ALT and bilirubin levels and caused cholestasis in WT mice. PFDA increased total and various bile acid species in serum but decreased them in the liver. Furthermore, in mouse livers, PFDA, not PFOA, down-regulated mRNA expression of uptake transporters (Ntcp, Oatp1a1, 1a4, 1b2, and 2b1) but induced efflux transporters (Bcrp, Mdr2, and Mrp2-4). In addition, PFDA, not PFOA, decreased Cyp7a1, 7b1, 8b1, and 27a1 mRNA expression in mouse livers with concomitant hepatic accumulation of cholesterol. In contrast, in PPARα-null mice, PFDA did not increase serum ALT, bilirubin, or total bile acids, but produced prominent hepatosteatosis; and the observed PFDA-induced expression changes of transporters and Cyps in WT mice were largely attenuated or abolished. In CAR-null mice, the observed PFDA-induced bile acid alterations in WT mice were mostly sustained. These results indicate that, at the dose employed, PFDA has more negative effects than PFOA on liver function. PPARα appears to play a major role in mediating most of PFDA-induced effects, which were absent or attenuated in PPARα-null mice. Lack of PPARα, however, exacerbated hepatic steatosis. Our findings indicate separated roles of PPARα in mediating the adaptive responses to PFDA: protective against hepatosteatosis but exacerbating cholestasis.

A feasible protocol to profile bile acids in dried blood spots from rats using a UHPLC-MS/MS method combining a surrogate matrix

Dried blood spot (DBS) sampling is a promising method for microliter blood sample collection with the advantages of convenient transportation, storage and clinical operations. However, it is challenging to develop an analytical protocol to determine endogenous metabolites, such as bile acids (BAs) in DBSs, due to the low-blood-volume character of DBSs and the complex features of filter paper. Herein, we developed a method of fast ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) to profile and quantify BAs in DBSs. The pretreatment methods were optimized and a two-step solvent addition method, where a small amount of water was firstly added to moisten the DBS and then methanol was added, showed high extraction efficiency for multiple BAs in DBSs. The UHPLC-MS/MS conditions were optimized and 35BAs in different types could be profiled with good resolution and quantified with acceptable precision and accuracy. Preparation of a DBS surrogate matrix without endogenous BAs has been well developed using rat erythrocytes in BSA solution and showed good performance on both the signal suppression/enhancement percentage and parallelism assessment evaluation of three different stable-isotope-labeled (SIL) BAs. The established protocol was successfully applied to profile BAs in DBSs of intrahepatic cholestasis model and healthy control rats with good repeatability. To our knowledge, it is the first time that 35 BAs in DBSs could be well profiled and an appropriate DBS surrogate matrix has been developed. This protocol presents future-oriented applications of DBSs for relevant preclinical studies to profile BAs and probe biomarkers.

Taxonomic identification of bile salt hydrolase-encoding lactobacilli: Modulation of the enterohepatic bile acid profile

Bile salt hydrolases (BSHs) are enzymes that are essential for the enterohepatic metabolism of bile acids (BAs). BSHs catalyze the production of unconjugated BAs and regulate the homeostasis of BA pool. This study identified Lactobacillus as a crucial BSH-encoding genus, and 16 main species were obtained using metagenomic data from publicly available human gut microbiome databases. Then, the 16 species of lactobacilli were classified into four typical categories by BSH phylotypes, including five species encoding BSH-T0, six species encoding BSH-T2, four species encoding BSH-T3, and Ligilactobacillus salivarius encoding both BSH-T0 and BSH-T3. The lactobacilli with the highest in vitro deconjugation activities against seven conjugated BAs were the BSH-T3-encoding strains. Furthermore, in vivo studies in mice administered four representative lactobacilli strains encoding different BSH phylotypes showed that treatment with BSH-T3-encoding Limosilactobacillus reuteri altered the structure of the gut microbiome and metabolome and significantly increased the levels of unconjugated BAs and total BA excretion. Our findings facilitated the taxonomic identification of crucial BSH-encoding lactobacilli in human gut microbiota and shed light on their contributions toward modulation of the enterohepatic circulation of BAs, which will contribute to future therapeutic applications of BSH-encoding probiotics to improve human health.

Primary biliary cholangitis: Epidemiology, prognosis, and treatment

Primary biliary cholangitis (PBC) is a chronic cholestatic autoimmune liver disease characterized by a destructive, small duct, and lymphocytic cholangitis, and marked by the presence of antimitochondrial antibodies. The incidence and prevalence of PBC vary widely in different regions and time periods, and although disproportionally more common among White non-Hispanic females, contemporary data show a higher prevalence in males and racial minorities than previously described. Outcomes largely depend on early recognition of the disease and prompt institution of treatment, which, in turn, are directly influenced by provider bias and socioeconomic factors. Ursodeoxycholic acid remains the initial treatment of choice for PBC, with obeticholic acid and fibrates (off-label therapy) reserved as add-on therapy for the management of inadequate responders or those with ursodeoxycholic acid intolerance. Novel and repurposed drugs are currently at different stages of clinical development not only for the treatment of PBC but also for its symptomatic management. Here, we summarize the most up-to-date data regarding the epidemiology, prognosis, and treatment of PBC, providing clinically useful information for its holistic management.

Liquiritin alleviates alpha-naphthylisothiocyanate-induced intrahepatic cholestasis through the Sirt1/FXR/Nrf2 pathway

Liquiritin (LQ) is an important monomer active component in flavonoids of licorice. The objective of this study was to evaluate the hepatoprotective effects of LQ in cholestatic mice. LQ (40 or 80 mg/kg) was intragastrically administered to mice once daily for 6 days, and mice were treated intragastrically with a single dosage of ANIT (75 mg/kg) on the 5th day. On the 7th day, mice were sacrificed to collect blood and livers. The mRNA and protein levels were determined by qRT-PCR and western blot assay. We also conducted systematical assessments of miRNAs expression profiles in the liver. LQ ameliorated ANIT-induced cholestatic liver injury, as evidenced by reduced serum biochemical markers and attenuated pathological changes in liver. Pretreatment of LQ reduced the increase of malondialdehyde, TNF-α, and IL-1β induced by ANIT. Moreover, ANIT suppressed the expression of Sirt1 and FXR in liver tissue, which was weakened in the LQ pre-treatment group. LQ enhanced the nuclear expression of Nrf2, which was increased in the ANIT group. LQ also increased the mRNA expressions of bile acid transporters Bsep, Ntcp, Mrp3, and Mrp4. Furthermore, a miRNA deep sequencing analysis revealed that LQ had a global regulatory effect on the hepatic miRNA expression. Kyoto Encyclopedia of Genes and Genomes functional enrichment analysis showed that the differentially expressed miRNAs were mainly related to metabolic pathways, endocytosis, and MAPK signaling pathway. Collectively, LQ attenuated hepatotoxicity and cholestasis by regulating the expression of Sirt1/FXR/Nrf2 and the bile acid transporters, indicating that LQ might be an effective approach for cholestatic liver diseases.

Investigating bile acid-mediated cholestatic drug-induced liver injury using a mechanistic model of multidrug resistance protein 3 (MDR3) inhibition

Inhibition of the canalicular phospholipid floppase multidrug resistance protein 3 (MDR3) has been implicated in cholestatic drug-induced liver injury (DILI), which is clinically characterized by disrupted bile flow and damage to the biliary epithelium. Reduction in phospholipid excretion, as a consequence of MDR3 inhibition, decreases the formation of mixed micelles consisting of bile acids and phospholipids in the bile duct, resulting in a surplus of free bile acids that can damage the bile duct epithelial cells, i.e., cholangiocytes. Cholangiocytes may compensate for biliary increases in bile acid monomers via the cholehepatic shunt pathway or bicarbonate secretion, thereby influencing viability or progression to toxicity. To address the unmet need to predict drug-induced bile duct injury in humans, DILIsym, a quantitative systems toxicology model of DILI, was extended by representing key features of the bile duct, cholangiocyte functionality, bile acid and phospholipid disposition, and cholestatic hepatotoxicity. A virtual, healthy representative subject and population (n = 285) were calibrated and validated utilizing a variety of clinical data. Sensitivity analyses were performed for 1) the cholehepatic shunt pathway, 2) biliary bicarbonate concentrations and 3) modes of MDR3 inhibition. Simulations showed that an increase in shunting may decrease the biliary bile acid burden, but raise the hepatocellular concentrations of bile acids. Elevating the biliary concentration of bicarbonate may decrease bile acid shunting, but increase bile flow rate. In contrast to competitive inhibition, simulations demonstrated that non-competitive and mixed inhibition of MDR3 had a profound impact on phospholipid efflux, elevations in the biliary bile acid-to-phospholipid ratio, cholangiocyte toxicity, and adaptation pathways. The model with its extended bile acid homeostasis representation was furthermore able to predict DILI liability for compounds with previously studied interactions with bile acid transport. The cholestatic liver injury submodel in DILIsym accounts for several processes pertinent to bile duct viability and toxicity and hence, is useful for predictions of MDR3 inhibition-mediated cholestatic DILI in humans.

An integrated strategy combining metabolomics and machine learning for the evaluation of bioactive markers that differentiate various bile

Animal bile is an important component of natural medicine and is widely used in clinical treatment. However, it is easy to cause mixed applications during processing, resulting in uneven quality, which seriously affects and harms the interests and health of consumers. Bile acids are the major bioactive constituents of bile and contain a variety of isomeric constituents. Although the components are structurally similar, they exhibit different pharmacological activities. Identifying the characteristics of each animal bile is particularly important for processing and reuse. It is necessary to establish an accurate analysis method to distinguish different types of animal bile. We evaluated the biological activity of key feature markers from various animal bile samples. In this study, a strategy combining metabolomics and machine learning was used to compare the bile of three different animals, and four key markers were screened. Quantitative analysis of the key markers showed that the levels of Glycochenodeoxycholic acid (GCDCA) and Taurodeoxycholic acid (TDCA) were highest in pig bile; Glycocholic acid (GCA) and Cholic acid (CA) were the most abundant in bovine and sheep bile, respectively. In addition, four key feature markers significantly inhibited the production of NO in LPS-stimulated RAW264.7 macrophage cells. These findings will contribute to the targeted development of bile in various animals and provide a basis for its rational application.

Bile acid metabolism and signaling, the microbiota, and metabolic disease

The diversity, composition, and function of the bacterial community inhabiting the human gastrointestinal tract contributes to host health through its role in producing energy or signaling molecules that regulate metabolic and immunologic functions. Bile acids are potent metabolic and immune signaling molecules synthesized from cholesterol in the liver and then transported to the intestine where they can undergo metabolism by gut bacteria. The combination of host- and microbiota-derived enzymatic activities contribute to the composition of the bile acid pool and thus there can be great diversity in bile acid composition that depends in part on the differences in the gut bacteria species. Bile acids can profoundly impact host metabolic and immunological functions by activating different bile acid receptors to regulate signaling pathways that control a broad range of complex symbiotic metabolic networks, including glucose, lipid, steroid and xenobiotic metabolism, and modulation of energy homeostasis. Disruption of bile acid signaling due to perturbation of the gut microbiota or dysregulation of the gut microbiota-host interaction is associated with the pathogenesis and progression of metabolic disorders. The metabolic and immunological roles of bile acids in human health have led to novel therapeutic approaches to manipulate the bile acid pool size, composition, and function by targeting one or multiple components of the microbiota-bile acid-bile acid receptor axis.

An effective method for preventing cholestatic liver injury of Aucklandiae Radix and Vladimiriae Radix: Inflammation suppression and regulate the expression of bile acid receptors

ETHNOPHARMACOLOGICAL RELEVANCE

Aucklandiae Radix (AR) and Vladimiriae Radix (VR) were used to treat gastrointestinal, liver and gallbladder diseases at practice. In most conditions, VR was used to be a substitute of AR or a local habit may attribute to the same main active ingredients Costunolide and Dehydrocostus lactone, which presented many similar pharmacological activities. However, other different lactone compounds in AR and VR also play a role in disease treatment, so the difference in therapeutic effects of AR and VR in related diseases needs to be further studied.

AIMS OF THE STUDY

Revealing the differences between the chemical compounds of the total lactone extracts of AR and VR (TLE of AR and VR) and the differences in the protective effects of cholestatic liver injury to ensure rational use of AR and VR.

STUDY DESIGN AND METHODS

The macroporous adsorption resin was used to purify and enrich the lactone compounds to obtain the total lactone extracts of AR and VR. HPLC-PDA was used to obtain the data to establish chemical fingerprint and chemometric analysis to compare similarities and differences between TLE of AR and VR. The pharmacodynamic experiment revealed how TLE of AR and VR to show protect effects on cholestatic liver injury.

RESULTS

Similarity analysis results showed TLE of AR and VR had a high similarity (>0.9). Nevertheless, difference analysis results showed 4 compounds, Costunolide, Dehydrocostus lactone, 3β-acetoxy-11β-guaia-4 (15), 10 (14)-diene-12,6α-olide and vladinol F may contribute to the differences between them. The pharmacodynamics experiments results showed the TLE of AR and VR affected the different liver cholate-associated transporters mRNA expression (TLE of AR up-regulated CYP7A1, TLE of VR down-regulated FXR and BSEP), the TLE of AR and VR had an effect to regulate biochemical indicators (AST, ALT, ALP, TBA) of liver function, and TLE of VR was better than TLE of AR in reducing the expression of inflammatory factors (IL-6 and IL-1β).

CONCLUSION

The liver protection of AR and VR have been confirmed, but the differences of material basis and mechanism of drug efficacy needed further study to guarantee formulation research and provide theoretical references for clinical rational applications of AR and VR.

The neonatal liver: Normal development and response to injury and disease

The liver emerges from the ventral foregut endoderm around 3 weeks in human and 1 week in mice after fertilization. The fetal liver works as a hematopoietic organ and then develops functions required for performing various metabolic reactions in late fetal and neonatal periods. In parallel with functional differentiation, the liver establishes three dimensional tissue structures. In particular, establishment of the bile excretion system consisting of bile canaliculi of hepatocytes and bile ducts of cholangiocytes is critical to maintain healthy tissue status. This is because hepatocytes produce bile as they functionally mature, and if allowed to remain within the liver tissue can lead to cytotoxicity. In this review, we focus on epithelial tissue morphogenesis in the perinatal period and cholestatic liver diseases caused by abnormal development of the biliary system.

Approach to the patient with cholestasis and jaundice syndrome. Joint AMH, AMG, and AMEG scientific position statement

The term cholestasis refers to bile acid retention, whether within the hepatocyte or in the bile ducts of any caliber. Biochemically, it is defined by a level of alkaline phosphatase that is 1.67-times higher than the upper limit of normal. Cholestatic diseases can be associated with an inflammatory process of the liver that destroys hepatocytes (hepatitis), withjaundice (yellowing of the skin and mucus membranes, associated with elevated serum bilirubin levels), or with both, albeit the three concepts should not be considered synonymous. Cholestatic diseases can be classified as intrahepatic or extrahepatic, depending on their etiology. Knowing the cause of the condition is important for choosing the adequate diagnostic studies and appropriate treatment in each case. A complete medical history, together with a thorough physical examination and basic initial studies, such as liver ultrasound and liver function tests, aid the clinician in deciding which path to follow, when managing the patient with cholestasis. In a joint effort, the Asociación Mexicana de Hepatología (AMH), the Asociación Mexicana de Gastroenterología (AMG) and the Asociación Mexicana de Endoscopia Gastrointestinal (AMEG) developed the first Mexican scientific position statement on said theme.

Mechanism of cholangiocellular damage and repair during cholestasis

The mechanism of damage of the biliary epithelium remains partially unexplored. However, recently many works have offered new evidence regarding the cholangiocytes' damage process, which is the main target in a broad spectrum of pathologies ranging from acute cholestasis, cholangiopathies to cholangiocarcinoma. This is encouraging since some works addressed this epithelium's relevance in health and disease until a few years ago. The biliary tree in the liver, comprised of cholangiocytes, is a pipeline for bile flow and regulates key hepatic processes such as proliferation, regeneration, immune response, and signaling. This review aimed to compile the most recent advances on the mechanisms of cholangiocellular damage during cholestasis, which, although it is present in many cholangiopathies, is not necessarily a common or conserved process in all of them, having a relevant role cAMP and PKA during obstructive cholestasis, as well as Ca²⁺-dependent PKC in functional cholestasis. Cholangiocellular damage could vary according to the type of cholestasis, the aggressor, or the bile ducts' location where it develops and what kind of damage can favor cholangiocellular carcinoma development.

Roles of bile acids in enteric virus replication

Bile acids (BAs) are evolutionally conserved molecules synthesized in the liver from cholesterol to facilitating the absorption of fat-soluble nutrients. In the intestines, where enteric viruses replicate, BAs also act as signaling molecules that modulate various biological functions via activation of specific receptors and cell signaling pathways. To date, BAs present either pro-viral or anti-viral effects for the replication of enteric viruses in vivo and in vitro. In this review, we summarized current information on biosynthesis, transportation and metabolism of BAs and the role of BAs in replication of enteric caliciviruses, rotaviruses, and coronaviruses. We also discussed the application of BAs for cell culture adaptation of fastidious enteric caliciviruses and control of virus infection, which may provide novel insights into the development of antivirals and/or disinfectants for enteric viruses.

A UPLC-MS/MS-based metabolomics analysis of the pharmacological mechanisms of rabdosia serra against cholestasis

BACKGROUND

Rabdosia Serra, the dried aerial parts of Rabdosia serra (Maxim.) Hara (RS) from the Labiatae family, is a traditional Chinese herbal medicine called Xihuangcao. Although RS has been found to exert a therapeutic effect on cholestasis, the underlying molecular mechanism remains unclear.

PURPOSE

This study was designed to investigate the pharmacological effect and mechanism of RS on cholestatic rats using metabolomics platform.

METHODS

Histopathology and biochemical evaluations were performed to determine the therapeutic effect of RS and developed a rapid metabolite detection technology method based on UPLC-MS/MS to perform metabolomics research. Further, quantitative real-time polymerase chain reaction (RT-qPCR) was used to study the effect of RS on the bile acid metabolism pathway at the transcriptional level.

RESULTS

RS significantly reduced the bile flow rates in cholestatic rats and decreased the levels of ALT, AST, TBA, T-BIL, and LDH, which were increased in the model group. Histological analysis showed that RS alleviated the liver injury induced by ANIT. Serum metabolomics results revealed 33 of the 37 biomarkers were found to be significantly altered by ANIT, and 26 were considerably changed following treatment with RS. Metabolic pathway analysis revealed four pathways such as primary bile acid biosynthesis, biosynthesis of unsaturated fatty acids, and arachidonic acid and tryptophan metabolism. The bile acid secretion process and the inflammation and oxidative stress processes are the major biochemical reactions following treatment with ANIT and RS. Bile acid-targeted metabolomics study showed that TCA, GCA, GCDCA, and GDCA might be sensitive biomarkers that induced liver injury. we found that treatment with RS regulated the levels of bile acid in the serum and liver and restored the proportion of bile acids, especially CA and conjugated bile acids, such as TCA and GCA, in the bile duct. RS increased the mRNA expression levels of FXR, SHP, BSEP, and MRP2 in livers, and IBABP, OST-α, and OST-β in the ileum.

CONCLUSION

In this study, RS was found to protect the liver by regulating multiple metabolic pathways and promoting the excretion of bile acids. Simultaneously, RS played an essential role in reversing the imbalance of bile acids and protected against cholestasis by regulating the expression of transporters associated with bile acids. We demonstrated the correlation between molecular mechanisms and metabolites, provide a reference for the fabrication of extracts that can be used to treat cholestasis.

Glycyrrhetinic Acid Protects α-Naphthylisothiocyanate- Induced Cholestasis Through Regulating Transporters, Inflammation and Apoptosis

Glycyrrhetinic acid (GA), the active metabolic product of Glycyrrhizin (GL) that is the main ingredient of licorice, was reported to protect against α-naphthylisothiocyanate (ANIT)- induced cholestasis. However, its protective mechanism remains unclear. In our work, the cholestatic liver injury in mice was caused by ANIT and GA was used for the treatment. We assessed cholestatic liver injury specific indexes, histopathological changes, bile acid transporters, inflammation and apoptosis. The results of liver biochemical index and histopathological examination showed that GA markedly attenuated ANIT-induced liver injury. Mechanism research suggested that GA could activate the expression of farnesoid x receptor (FXR) and its downstream bile acids transporters Na+/taurocholate co-transporting polypeptide (NTCP), bile salt export pump (BSEP) and multidrug resistance-associated protein 2 (MRP2), as well as the nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream proteins MRP3, MRP4. These transporters play a vital role in mediating bile acid homeostasis in hepatocytes. Moreover, GA could significantly inhibit the ANIT-induced activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) inflammatory pathway and the increase of tumor necrosis factor-α (TNF-α) concentration in serum. Also, GA protected against ANIT-induced mitochondrial apoptosis by regulating the expression of Bcl-2, Bax, cleaved caspase 3 and cleaved caspase 9. In conclusion, GA alleviates the hepatotoxicity caused by ANIT by regulating bile acids transporters, inflammation and apoptosis, which suggests that GA may be a potential therapeutic agent for cholestasis.

The effect of Corvitin on the content of bile acids in the liver of rats under conditions of chronic social stress

The article looks at recent research dealing with changes in the bile acid composition of the bile of outbred male rats under chronic social stress (social defeat in daily male confrontations, 14 days) when administered Corvitin (1 mg/kg, intragastrically, 7 days). Chronic social stress was created by daily agonistic interactions between animals. The main fractions of conjugated bile acids – taurocholic, taurohenodeoxycholic and taurodeoxycholic, glycocholic, glycochenodeoxycholic and glycodeoxycholic and free ones – cholic, chenodeoxycholic and deoxycholic were determined by the method of thin layer chromatography of bile. The conjugation index (ratio of the sum of conjugated cholates to the sum of free ones) and hydroxylation (ratio of the sum of trihydroxycholanic bile acids to the sum of dihydroxycholanic ones) of bile acids were calculated. The research showed that in the conditions of experimental social stress, Corvitin enhances the conjugation of bile acids with taurine and glycine, i.e. stimulates detoxification processes in hepatocytes. In the conditions of chronic social stress in male rats, the processes that had provided the flow of glycoconjugates of bile acids from hepatocytes to the bile ducts were further suppressed. The concentrations of glycocholic acid and glycochenodeoxycholic and glycodeoxycholic acids in the bile of male intruders were lower than the control values. But, as seen in the experiment, the use of Corvitin normalized these indicators. The experiment showed that in the conditions of chronic social stress, the content of cholic acid in the bile of intruder rats decreased, and when correcting the pathological condition using Corvitin, it reached the control values. The use of Corvitin simultaneously with the simulation of experimental social stress normalized the biliary secretory function of the liver, indicating the high potential of using Corvitin as a corrective factor in chronic social stress. Correction of stress-induced pathologies of liver bile-secretory function by Corvitin requires further thorough experimental studies.

Compensatory hepatic adaptation accompanies permanent absence of intrahepatic biliary network due to YAP1 loss in liver progenitors

Yes-associated protein 1 (YAP1) regulates cell plasticity during liver injury, regeneration, and cancer, but its role in liver development is unknown. We detect YAP1 activity in biliary cells and in cells at the hepatobiliary bifurcation in single-cell RNA sequencing analysis of developing livers. Deletion of Yap1 in hepatoblasts does not impair Notch-driven SOX9+ ductal plate formation but does prevent the formation of the abutting second layer of SOX9+ ductal cells, blocking the formation of a patent intrahepatic biliary tree. Intriguingly, these mice survive for 8 months with severe cholestatic injury and without hepatocyte-to-biliary transdifferentiation. Ductular reaction in the perihilar region suggests extrahepatic biliary proliferation, likely seeking the missing intrahepatic biliary network. Long-term survival of these mice occurs through hepatocyte adaptation via reduced metabolic and synthetic function, including altered bile acid metabolism and transport. Overall, we show YAP1 as a key regulator of bile duct development while highlighting a profound adaptive capability of hepatocytes.

Efficacy and safety of obeticholic acid in liver disease-A systematic review and meta-analysis

BACKGROUND AND AIMS

Currently, there is no pharmacotherapy for non-alcoholic steatohepatitis (NASH), a common liver disorder. In contrast, primary biliary cholangitis (PBC) is a chronic cholestatic liver disease for which ursodeoxycholic acid (UDCA) is the drug of choice. However, 50% of PBC patients may not respond to UDCA. Obeticholic acid (OCA) is emerging as a vital pharmacotherapy for these chronic disorders. We aimed to analyse the safety and efficacy of OCA.

METHODS

We performed an extensive search of electronic databases from 01/01/2000 to 31/03/2020. We included randomized controlled trials of OCA in patients with NASH, PBC, and primary sclerosing cholangitis (PSC). We assessed the histological improvement in NASH, reduction in alkaline phosphatase (≤1.67 ULN) in PBC, and the adverse effects of OCA.

RESULTS

Seven RCTs (n = 2834) were included. Of the total RCTs, there were three on both NASH and PBC and one on PSC. OCA improved NASH fibrosis [OR: 1.95 (1.47-2.59; p < 0.001)]. With the 10 mg OCA dose, the odds of improvement was 1.61 (1.03-2.51; p = 0.03), while with the 25 mg dose, it was 2.23 (1.55-3.18; p < 0.001). However, 25 mg OCA led to significant adverse events and discontinuation of the drug [2.8 (1.42-3.02); p < 0.001)] compared with 10 mg OCA [0.95 (0.6-1.5); p = 0.84] in NASH patients. In PBC patients, the response to 5 mg OCA was better than with the higher doses [5 mg: 7.66 (3.12-18.81; p < 0.001), 10 mg: 5.18 (2-13.41; p = 0.001), 25 mg: 2.36 (0.94-5.93; p = 0.06), 50 mg: 4.08 (1.05-15.78; p = 0.04)]. The risk of pruritus was lowest with 5 mg OCA.

CONCLUSIONS

Lower doses of OCA are effective and safe in NASH and cholestatic liver disease. While 10 mg OCA is effective for NASH fibrosis regression, only 5 mg OCA is required for PBC.

Inhibition of heat shock protein 90 alleviates cholestatic liver injury by decreasing IL-1β and IL-18 expression

Severe cholestatic liver injury diseases, such as obstructive jaundice and the subsequent acute obstructive cholangitis, are induced by biliary tract occlusion. Heat shock protein 90 (HSP90) inhibitors have been demonstrated to be protective for various organs. The potential of HSP90 inhibitors in the treatment of cholestatic liver injury, however, remains unclear. In the present study, rat models of bile duct ligation (BDL) were established, the HSP90 inhibitor 17-dimethylamino-ethylamino-17-demethoxygeldanamycin (17-DMAG) was administered, and its ability to ameliorate the cholestasis-induced liver injuries was evaluated. In the BDL rat models and clinical samples, increased HSP90 expression was observed to be associated with cholestatic liver injury. Furthermore, 17-DMAG alleviated cholestasis-induced liver injury in the rat models, as revealed by the assessment of pathological changes and liver function. In addition, 17-DMAG protected hepatocytes against cholestatic injury in vitro. Further assays indicated that 17-DMAG administration prevented cholestasis-induced liver injury in the rats by decreasing the expression of interleukin (IL)-1β and IL-18. Moreover, 17-DMAG also decreased the cholestasis-induced upregulation of IL-1β and IL-18 in liver sinusoidal endothelial cells in vitro. In conclusion, the HSP90 inhibitor 17-DMAG is able to prevent liver injury in rats with biliary obstruction, and this phenomenon is associated with the reduction of IL-1β and IL-18 expression.

Bile acid metabolism and circadian rhythms

Circadian rhythms are biological systems that synchronize cellular circadian oscillators with the organism's daily feeding-fasting or rest-activity cycles in mammals. Circadian rhythms regulate nutrient absorption and utilization at the cellular level and are closely related to obesity and metabolic disorders. Bile acids are important modulators that facilitate nutrient absorption and regulate energy metabolism. Here, we provide an overview of the current connections and future perspectives between the circadian clock and bile acid metabolism as well as related metabolic diseases. Feeding and fasting cycles influence bile acid pool size and composition, and bile acid signaling can respond to acute lipid and glucose utilization and mediate energy balance. Disruption of circadian rhythms such as shift work, irregular diet, and gene mutations can contribute to altered bile acid metabolism and heighten obesity risk. High-fat diets, alcohol, and gene mutations related to bile acid signaling result in desynchronized circadian rhythms. Gut microbiome also plays a role in connecting circadian rhythms with bile acid metabolism. The underlying mechanism of how circadian rhythms interact with bile acid metabolism has not been fully explored. Sustaining bile acid homeostasis based on circadian rhythms may be a potential therapy to alleviate metabolic disturbance.

Bile Acids as a New Type of Steroid Hormones Regulating Nonspecific Energy Expenditure of the Body (Review)

The review is devoted to the systematization, classification, and generalization of the results of modern scientific research on the role of bile acids as a new class of steroid hormones. The paper presents the evidence for bile acid participation in the regulation of the body energy metabolism, body weight control, as well as the pathogenesis of obesity, diabetes mellitus, insulin resistance, and cardiovascular diseases. Particular attention is paid to the role of bile acids in the control of nonspecific energy expenditure of the body. The applied aspects of using the novel data about the membrane and intracellular receptors responsible for the development of hormonal regulatory effects of bile acids are analyzed. According to the authors, the modern data on the role of bile acids in the regulation of body functions allow a deeper understanding of the pathogenesis of body weight disorders and associated cardiovascular diseases. The review demonstrates promising directions in the search for specific methods of prevention and correction of these pathological conditions.

ASBT(SLC10A2): A promising target for treatment of diseases and drug discovery

Bile acids has gradually become a new focus in various diseases, and ASBT as a transporter responsible for the reabsorption of ileal bile acids, is a key hinge associated to the bile acids-cholesterol balance and bile acids of enterohepatic circulation. The cumulative studies have also shown that ASBT is a promising target for treatment of liver, gallbladder, intestinal and metabolic diseases. This article briefly reviewed the process of bile acids enterohepatic circulation, as well as the regulations of ASBT expression, covering transcription factors, nuclear receptors and gut microbiota. In addition, the relationship between ASBT and various diseases were discussed in this paper. According to the structural classification of ASBT inhibitors, the research status of ASBT inhibitors and potential ASBT inhibitors of traditional Chinese medicine (such resveratrol, jatrorrhizine in Coptis chinensis) were summarized. This review provides a basis for the development of ASBT inhibitors and the treatment strategy of related diseases.

Metabolomics research on the hepatoprotective effect of cultured bear bile powder in α-naphthylisothiocyanate-induced cholestatic mice

Natural bear bile powder (NBBP) is a famous traditional medicine and has been widely used in clinic. However, access to the sources of bear bile is restricted; hence, it is essential to discover new substitutes for NBBP. Cultured bear bile powder (CBBP) is transformed from chicken bile and contains main ingredients as to NBBP. In the present study, the effect and potential mechanism of action of CBBP on cholestatic liver injury in-naphthylisothiocyanate (ANIT)-induced mouse model was explored using metabolomics. CBBP treatment ameliorated impaired hepatic dysfunction and tissue damage that induced by ANIT. Metabolomics showed there were 28 different metabolites induced by ANIT as compared with control mice, and 18 of which was reversed by CBBP. Pathway analysis revealed that those 18 metabolites are mainly involved in bile acid (BA) biosynthesis and D-glutamine and D-glutamate metabolism. Further LC-MS/MS analysis showed that CBBP and NBBP both reduced serum and liver levels of BAs, but increased their biliary levels. Additionally, CBBP and NBBP upregulated expression of BA efflux transporters, Mrp2, Mrp3, and Mrp4, and metabolic enzymes, Cyp2b10 and Ugt1a1 of liver tissue of cholestatic mice, increased the BA excretion and metabolism. Moreover, CBBP and NBBP treatment upregulated GCLc/GCLm expression, and restored glutathione metabolism. In conclusion, the protective effects of CBBP against cholestatic liver injury were similar to those of NBBP. Mechanistically, both CBBP and NBBP reversed the disruption in homeostasis of BAs and glutathione, alleviating damage to hepatocytes.

Bile Composition as a Diagnostic and Prognostic Tool in Liver Transplantation

Bile secretion and composition reflects the functional status of hepatocytes and cholangiocytes. Bile composition can have a role in the assessment of donor grafts before implantation in the recipient. In addition, changes in bile composition after liver transplantation can serve as a diagnostic and prognostic tool to predict posttransplant complications, such as primary nonfunction, acute cellular rejection, or nonanastomotic biliary strictures. With the popularization of liver machine perfusion preservation in the clinical setting, there is a revisited interest in biliary biomarkers to assess graft viability before implantation. This review discusses current literature on biliary biomarkers that could predict or assess liver graft and bile duct viability. Bile composition offers an exciting and novel perspective in the search for reliable hepatocyte and cholangiocyte viability biomarkers.

Gut microbiota in non-alcoholic fatty liver disease and alcohol-related liver disease: Current concepts and perspectives

The term, gut-liver axis, is used to highlight the close anatomical and functional relationship between the intestine and the liver. It has been increasingly recognized that the gut-liver axis plays an essential role in the development and progression of liver disease. In particular, in non-alcoholic fatty liver disease and alcohol-related liver disease, the two most common causes of chronic liver disease, a dysbiotic gut microbiota can influence intestinal permeability, allowing some pathogens or bacteria-derived factors from the gut reaching the liver through the enterohepatic circulation contributing to liver injury, steatohepatitis, and fibrosis progression. Pathways involved are multiple, including changes in bile acid metabolism, intestinal ethanol production, generation of short-chain fatty acids, and other by-products. Bile acids act through dedicated bile acid receptors, farnesoid X receptor and TGR5, in both the ileum and the liver, influencing lipid metabolism, inflammation, and fibrogenesis. Currently, both non-alcoholic fatty liver disease and alcohol-related liver disease lack effective therapies, and therapeutic targeting of gut microbiota and bile acids enterohepatic circulation holds promise. In this review, we summarize current knowledge about the role of gut microbiota in the pathogenesis of non-alcoholic fatty liver disease and alcohol-related liver disease, as well as the relevance of microbiota or bile acid-based approaches in the management of those liver diseases.

Colestasis en el adulto: enfoque diagnóstico y terapéutico. Revisión de tema

La colestasis es uno de los motivos de consulta más frecuentes en hepatología. Se genera por una alteración en la síntesis, la secreción o el flujo de la bilis, a través del tracto biliar. Esta se define por una elevación de enzimas como la fosfatasa alcalina (Alkaline Phosphatase, ALP) y la gamma-glutamil transferasa, y en estadios tardíos con la hiperbilirrubinemia, al igual que con otras manifestaciones clínicas, tales como el prurito y la ictericia. El enfoque diagnóstico implica establecer el origen de dicha elevación, determinando si es intrahepática o extrahepática. Si es intrahepática, se debe esclarecer si proviene de los hepatocitos o de la vía biliar de pequeño y de gran calibre. El tratamiento dependerá de la etiología, por lo cual es importante un diagnóstico preciso. En esta revisión se presenta la fisiopatología y un enfoque diagnóstico y terapéutico.

Oleanolic acid reprograms the liver to protect against hepatotoxicants, but is hepatotoxic at high doses

Oleanolic acid (OA) is a triterpenoid that exists widely in fruits, vegetables and medicinal herbs. OA is included in some dietary supplements and is used as a complementary and alternative medicine (CAM) in China, India, Asia, the USA and European countries. OA is effective in protecting against various hepatotoxicants, and one of the protective mechanisms is reprogramming the liver to activate the nuclear factor erythroid 2-related factor 2 (Nrf2). OA derivatives, such as CDDO-Im and CDDO-Me, are even more potent Nrf2 activators. OA has recently been shown to also activate the Takeda G-protein-coupled receptor (TGR5). However, whereas a low dose of OA is hepatoprotective, higher doses and long-term use of OA can produce liver injury, characterized by cholestasis. This paradoxical hepatotoxic effect occurs not only for OA, but also for other OA-type triterpenoids. Dose and length of time of OA exposure differentiate the ability of OA to produce hepatoprotection vs hepatotoxicity. Hepatotoxicity produced by herbs is increasingly recognized and is of global concern. Given the appealing nature of OA in dietary supplements and its use as an alternative medicine around the world, as well as the development of OA derivatives (CDDO-Im and CDDO-Me) as therapeutics, it is important to understand not only that they program the liver to protect against hepatotoxic chemicals, but also how they produce hepatotoxicity.

UDCA, NorUDCA, and TUDCA in Liver Diseases: A Review of Their Mechanisms of Action and Clinical Applications

Bile acids (BAs) are key molecules in generating bile flow, which is an essential function of the liver. In the last decades, there have been great advances in the understanding of BA physiology, and new insights have emerged regarding the role of BAs in determining cell damage and death in several liver diseases. This new knowledge has helped to better delineate the pathophysiology of cholestasis and the adaptive responses of hepatocytes to cholestatic liver injury as well as of the mechanisms of injury of biliary epithelia. In this context, therapeutic approaches for liver diseases using hydrophilic BA (i.e., ursodeoxycholic acid, tauroursodeoxycholic, and, more recently, norursodeoxycholic acid), have been revamped. In the present review, we summarize current experimental and clinical data regarding these BAs and its role in the treatment of certain liver diseases.

Novel and emerging therapies for cholestatic liver diseases

While bile acids are important for both digestion and signalling, hydrophobic bile acids can be harmful, especially when in high concentrations. Mechanisms for the protection of cholangiocytes against bile acid cytotoxicity include negative feedback loops via farnesoid X nuclear receptor (FXR) activation, the bicarbonate umbrella, cholehepatic shunting and anti-inflammatory signalling, among others. By altering or overwhelming these defence mechanisms, cholestatic diseases such as primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) can further progress to biliary cirrhosis, end-stage liver disease and death or liver transplantation. While PBC is currently treated with ursodeoxycholic acid (UDCA) and obeticholic acid (OCA), many fail treatment, and we have yet to find an effective therapy for PSC. Novel therapies under evaluation target nuclear and surface receptors including FXR, transmembrane G-protein-coupled receptor 5 (TGR5), peroxisome proliferator-activated receptor (PPAR) and pregnane X receptor (PXR). Modulation of these receptors leads to altered bile composition, decreased cytotoxicity, decreased inflammation and improved metabolism. This review summarizes our current understanding of the role of bile acids in the pathophysiology of cholestatic liver diseases, presents the rationale for already approved medical therapies and discusses novel pharmacologic therapies under investigation.