Cholestatic liver diseases of genetic etiology: Advances and controversies

Isoastragaloside I attenuates cholestatic liver diseases by ameliorating liver injury, regulating bile acid metabolism and restoring intestinal barrier

ETHNOPHARMACOLOGICAL RELEVANCE

Cholestatic liver diseases (CLD) are liver disorders resulting from abnormal bile formation, secretion, and excretion from various causes. Due to the lack of suitable and safe medications, liver transplantation is the ultimate treatment for CLD patients. Isoastragaloside I (IAS I) is one of the main saponin found in Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao or Astragalus membranaceus (Fisch.) Bge, which has been demonstrated to obviously alleviate CLD. Nevertheless, the IAS I's specific anti-CLD mechanism remains undecipherable.

AIM OF THE STUDY

This study's purpose was to elucidate the protective consequence of IAS I on 0.1% 3, 5-diethoxycarbonyl-1,4-dihydroxychollidine (DDC) diet-induced CLD mice, and to reveal its potential mechanism.

MATERIALS AND METHODS

In this study, mice with CLD that had been fed a 0.1% DDC diet were distributed two doses of IAS I (20 mg/kg, 50 mg/kg). The effects of IAS I on CLD models were investigated by assessing blood biochemistry, liver histology, and Hyp concentrations. We investigated markers of liver fibrosis and ductular reaction using immunohistochemistry, western blot, and qRT-PCR. Liver inflammation indicators, arachidonic acid (ARA), and ω-3 fatty acid (FA) metabolites were also analyzed. Quantitative determination of 39 bile acids (BAs) in different organs employing UHPLC-Q-Exactive Orbitrap HRMS technology. Additionally, the H&E and western blot analysis were used to evaluate differences in intestinal barrier function in DDC-induced mice before and after administering IAS I.

RESULTS

After treatment with IAS I, serum biochemical indicators and liver hydroxyproline (Hyp) increased in a dose-dependent manner in CLD mice. The IAS I group showed significant improvement in indicators of liver fibrosis and ductular response, including as α-smooth muscle actin (α-SMA) and cytokeratin 19 (CK19), and transforming growth factor-β (TGF-β)/Smads signaling pathway. And inflammatory factors: F4/80, tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β), ARA and ω-3 FA metabolites showed significant improvement following IAS I treatment. Moreover, IAS I significantly ameliorated liver tau-BAs levels, particularly TCA, THCA, THDCA, TCDCA, and TDCA contents, which were associated with enhanced expression of hepatic farnesoid X receptor (FXR), small heterodimer partner (SHP), cholesterol 7α-hydroxylase (Cyp7a1), and bile-salt export pump (BSEP). Furthermore, IAS I significantly improved pathological changes and protein expression related to intestinal barrier function, including zonula occludens protein 1 (ZO-1), Muc2, and Occludin.

CONCLUSIONS

IAS I alleviated cholestatic liver injury, relieved inflammation, improved the altered tau-BAs metabolism and restored intestinal barrier function to protect against DDC-induced cholestatic liver diseases.

Analysis of UGT1A1 genotype-phenotype correlation in Chinese patients with gilbert and crigler-Najjar II syndrome

The spectrum of UDP-glucuronosyltransferase (UGT1A1) variants, which are associated with Gilbert syndrome (GS) and Crigler-Najjar syndrome (CNS-II), has been reported in Chinese and western countries. However, the genotype-phenotype correlation of the individual UGT1A1 variants in GS and CNS-II remains to be clarified. To explore the UGT1A1 variant pattern and genotype-phenotype correlations, we enrolled 310 Chinese patients, including 232 patients with GS and 78 with CNS-II. Peripheral blood samples were collected for screening variants in the gene UGT1A1 by a polymerase chain reaction and Sanger sequencing. The correlation between different UGT1A1 variants and clinical phenotypes was analyzed. A total of 21 UGT1A1 variants were identified, including nine novel variants, and constituted 42 UGT1A1 genotypes in the GS and CNS-II patients. The most common UGT1A1 variants were A (TA)7TAA, p.G71R, p.Y486D, p.P364L, and p.P229Q, which were different from western countries. The p.Y486D variant had higher minor allele frequency in CNS-II than in GS whereas the A (TA)7TAA variant had higher minor allele frequency in GS than in CNS-II. The serum total bilirubin and triglyceride had significant differences among 14 recurrent genotypes of UGT1A1, in which the serum total bilirubin in patients with compound p.Y486D (homozygous)/p.G71R variant was significantly higher compared with homozygous A (TA)7TAA, homozygous p.G71R, compound heterozygous A (TA)7TAA/p.G71R and A (TA)7TAA/p.P364L, and combined heterozygous A (TA)7TAA/p.G71R/p.P229Q, while the serum triglyceride in patients with combined A (TA)7TAA (homozygous)/p.P229Q variant was significantly higher compared with compound heterozygous A (TA)7TAA/p.G71R, single heterozygous A (TA)7TAA, single heterozygous p.G71R, and homozygous A (TA)7TAA. The spectrum of UGT1A1 genotypes in Chinese patients was distinct from western countries. There were differential levels of serum total bilirubin and triglyceride in patients with recurrent genotypes of UGT1A1.

What's new in pediatric genetic cholestatic liver disease: advances in etiology, diagnostics and therapeutic approaches

PURPOSE OF REVIEW

To highlight recent advances in pediatric cholestatic liver disease, including promising novel prognostic markers and new therapies.

FINDINGS

Identification of additional genetic variants associated with progressive familial intrahepatic cholestasis (PFIC) phenotype and new genetic cholangiopathies, with an emerging role of ciliopathy genes. Genotype severity predicts outcomes in bile salt export pump (BSEP) deficiency, and post-biliary diversion serum bile acid levels significantly affect native liver survival in BSEP and progressive familial intrahepatic cholestasis type 1 (FIC1 deficiency) patients. Heterozygous variants in the MDR3 gene have been associated with various cholestatic liver disease phenotypes in adults. Ileal bile acid transporter (IBAT) inhibitors, approved for pruritus in PFIC and Alagille Syndrome (ALGS), have been associated with improved long-term quality of life and event-free survival.

SUMMARY

Next-generation sequencing (NGS) technologies have revolutionized diagnostic approaches, while discovery of new intracellular signaling pathways show promise in identifying therapeutic targets and personalized strategies. Bile acids may play a significant role in hepatic damage progression, suggesting their monitoring could guide cholestatic liver disease management. IBAT inhibitors should be incorporated early into routine management algorithms for pruritus. Data are emerging as to whether IBAT inhibitors are impacting disease biology and modifying the natural history of the cholestasis.

Genetics of liver disease in adults

Chronic liver disease stands as a significant global health problem with an estimated 2 million annual deaths across the globe. Combining the use of next-generation sequencing technologies with evolving knowledge in the interpretation of genetic variation across the human genome is propelling our understanding, diagnosis, and management of both rare and common liver diseases. Here, we review the contribution of risk and protective alleles to common forms of liver disease, the rising number of monogenic diseases affecting the liver, and the role of somatic genetic variants in the onset and progression of oncological and non-oncological liver diseases. The incorporation of genomic information in the diagnosis and management of patients with liver disease is driving the beginning of a new era of genomics-informed clinical hepatology practice, facilitating personalized medicine, and improving patient care.

Causal associations between gut microbiota and Cholestatic liver diseases: a Mendelian randomization study

Background

The etiological factors of Cholestatic Liver Diseases especially primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) are not fully illustrated. It has been reported in previous observational studies that gut microbiota are associated with cholestatic liver diseases. However, there is uncertainty regarding the causality of this association. By using Mendelian randomization, this study aimed to examine the causal impact of gut microbiota on cholestatic liver diseases.

Methods

From large-scale genome-wide association studies, genetic instruments for each gut microbiota taxa as well as primary biliary cholangitis and primary sclerosing cholangitis were developed. Subsequently, we conducted a two-sample Mendelian randomization analysis, supplemented by multiple post hoc sensitivity analyses. Additionally, we performed reverse MR analyses to investigate the possibility of the reverse causal association.

Result

This two-sample MR study indicated that the order Bacillales, family Peptostreptococcaceae, family Ruminococcaceae, genus Anaerotruncu was associated with a decreased risk of developing PBC, and that order Selenomonadales, family Bifidobacteriaceae may be factors that increase the risk of PBC. On the other hand, we also identified order Selenomonadales, family Rhodospirillaceae, and genus RuminococcaceaeUCG013 were positively associated with PSC. The order Actinomycetales, family Actinomycetaceae, genus Actinomyces, genus Alloprevotella, genus Barnesiella, and genus Peptococcus were found negative associations with the risk of PSC. The reverse MR analysis demonstrated no statistically significant relationship between PBC, PSC and these specific gut microbial taxa.

Conclusion

Our findings offered novel evidence that the abundance of particular bacteria contributes to the risk of PBC and PSC, which may contribute to more effective approaches to PBC and PSC therapy and prevention.

Melatonin improves cholestatic liver disease via the gut-liver axis

Cholestatic liver disease is characterized by disturbances in the intestinal microbiota and excessive accumulation of toxic bile acids (BA) in the liver. Melatonin (MT) can improve liver diseases. However, the underlying mechanism remains unclear. This study aimed to explore the mechanism of MT on hepatic BA synthesis, liver injury, and fibrosis in 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed and Mdr2-/- mice. MT significantly improved hepatic injury and fibrosis with a significant decrease in hepatic BA accumulation in DDC-fed and Mdr2-/- mice. MT reprogramed gut microbiota and augmented fecal bile salt hydrolase activity, which was related to increasing intestinal BA deconjugation and fecal BA excretion in both DDC-fed and Mdr2-/- mice. MT significantly activated the intestinal farnesoid X receptor (FXR)/fibroblast growth factor 15 (FGF-15) axis and subsequently inhibited hepatic BA synthesis in DDC-fed and Mdr2-/- mice. MT failed to improve DDC-induced liver fibrosis and BA synthesis in antibiotic-treated mice. Furthermore, MT provided protection against DDC-induced liver injury and fibrosis in fecal microbiota transplantation mice. MT did not decrease liver injury and fibrosis in DDC-fed intestinal epithelial cell-specific FXR knockout mice, suggesting that the intestinal FXR mediated the anti-fibrosis effect of MT. In conclusion, MT ameliorates cholestatic liver diseases by remodeling gut microbiota and activating intestinal FXR/FGF-15 axis-mediated inhibition of hepatic BA synthesis and promotion of BA excretion in mice.

Loss of SLC27A5 Activates Hepatic Stellate Cells and Promotes Liver Fibrosis via Unconjugated Cholic Acid

Although the dysregulation of bile acid (BA) composition has been associated with fibrosis progression, its precise roles in liver fibrosis is poorly understood. This study demonstrates that solute carrier family 27 member 5 (SLC27A5), an enzyme involved in BAs metabolism, is substantially downregulated in the liver tissues of patients with cirrhosis and fibrosis mouse models. The downregulation of SLC27A5 depends on RUNX family transcription factor 2 (RUNX2), which serves as a transcriptional repressor. The findings reveal that experimental SLC27A5 knockout (Slc27a5-/- ) mice display spontaneous liver fibrosis after 24 months. The loss of SLC27A5 aggravates liver fibrosis induced by carbon tetrachloride (CCI4 ) and thioacetamide (TAA). Mechanistically, SLC27A5 deficiency results in the accumulation of unconjugated BA, particularly cholic acid (CA), in the liver. This accumulation leads to the activation of hepatic stellate cells (HSCs) by upregulated expression of early growth response protein 3 (EGR3). The re-expression of hepatic SLC27A5 by an adeno-associated virus or the reduction of CA levels in the liver using A4250, an apical sodium-dependent bile acid transporter (ASBT) inhibitor, ameliorates liver fibrosis in Slc27a5-/- mice. In conclusion, SLC27A5 deficiency in mice drives hepatic fibrosis through CA-induced activation of HSCs, highlighting its significant implications for liver fibrosis treatment.

Geniposide alleviated bile acid-associated NLRP3 inflammasome activation by regulating SIRT1/FXR signaling in bile duct ligation-induced liver fibrosis

BACKGROUND

Geniposide (GE), the active compound derived from Gardeniae Fructus, possesses valuable bioactivity for liver diseases, but GE effects on bile duct ligation (BDL)-induced cholestasis remain unclear. This study aimed to elucidate the influence of GE on BDL-induced liver fibrosis and to investigate the underlying mechanisms.

METHODS

GE (25 or 50 mg/kg) were intragastrical administered to C57BL/6 J mice for two weeks to characterize the hepatoprotective effect of GE on BDL-induced liver fibrosis. NLRP3 inflammasome activation was detected in vivo, and BMDMs were isolated to explore whether GE directly inhibited NLRP3 inflammasome activation. Serum bile acid (BA) profiles were assessed utilizing UPLC-MS/MS, and the involvement of SIRT1/FXR pathways was identified to elucidate the role of SIRT1/FXR in the hepaprotective effect of GE. The veritable impact of SIRT1/FXR signaling was further confirmed by administering the SIRT1 inhibitor EX527 (10 mg/kg) to BDL mice treated with GE.

RESULTS

GE treatment protected mice from BDL-induced liver fibrosis, with NLRP3 inflammasome inhibition. However, development in vitro experiments revealed that GE could not directly inhibit NLRP3 activation under ATP, monosodium urate, and nigericin stimulation. Further mechanistic data showed that GE activated SIRT1, which subsequently deacetylated FXR and restored CDCA, TUDCA, and TCDCA levels, thereby contributing to the observed hepaprotective effect of GE. Notably, EX527 treatment diminished the hepaprotective effect of GE on BDL-induced liver fibrosis.

CONCLUSION

This study first proved the hepaprotective effect of GE on liver fibrosis in BDL mice, which was closely associated with the restoration of BA homeostasis and NLRP3 inflammasome inhibition. The activation of SIRT1 and the subsequent FXR deacetylation restored the BA profiles, especially CDCA, TUDCA, and TCDCA contents, which was the main contributor to NLRP3 inhibition and the hepaprotective effect of GE. Overall, our work provides novel insights that GE as well as Gardeniae Fructus might be the potential attractive candidate for ameliorating BDL-induced liver fibrosis.

Exome sequencing reveals IFT172 variants in patients with non-syndromic cholestatic liver disease

BACKGROUND AND AIM

Gene defects contribute to the aetiology of intrahepatic cholestasis. We aimed to explore the outcome of whole-exome sequencing (WES) in a cohort of 51 patients with this diagnosis.

PATIENTS AND METHODS

Both paediatric (n = 33) and adult (n = 18) patients with cholestatic liver disease of unknown aetiology were eligible. WES was used for reassessment of 34 patients (23 children) without diagnostic genotypes in ABCB11, ATP8B1, ABCB4 or JAG1 demonstrable by previous Sanger sequencing, and for primary assessment of additional 17 patients (10 children). Nasopharyngeal swab mRNA was analysed to address variant pathogenicity in two families.

RESULTS

WES revealed biallelic variation in 3 ciliopathy genes (PKHD1, TMEM67 and IFT172) in 4 clinically unrelated index subjects (3 children and 1 adult), heterozygosity for a known variant in PPOX in one adult index subject, and homozygosity for an unreported splice-site variation in F11R in one child. Whereas phenotypes of the index patients with mutated PKHD1, TMEM67, and PPOX corresponded with those elsewhere reported, how F11R variation underlies liver disease remains unclear. Two unrelated patients harboured different novel biallelic variants in IFT172, a gene implicated in short-rib thoracic dysplasia 10 and Bardet-Biedl syndrome 20. One patient, a homozygote for IFT172 rs780205001 c.167A>C p.(Lys56Thr) born to first cousins, had liver disease, interpreted on biopsy aged 4y as glycogen storage disease, followed by adult-onset nephronophthisis at 25y. The other, a compound heterozygote for novel frameshift variant IFT172 NM_015662.3 c.2070del p.(Met690Ilefs*11) and 2 syntenic missense variants IFT172 rs776310391 c.157T>A p.(Phe53Ile) and rs746462745 c.164C>G p.(Thr55Ser), had a severe 8mo cholestatic episode in early infancy, with persisting hyperbilirubinemia and fibrosis on imaging studies at 17y. No patient had skeletal malformations.

CONCLUSION

Our findings suggest association of IFT172 variants with non-syndromic cholestatic liver disease.

Exploration of the Molecular Basis of Forsythia Fruit in the Prevention and Treatment of Cholestatic Liver Injury through Network Pharmacology and Molecular Docking

Forsythia fruit, edible fruit of Forsythia suspensa (Thunb.) Vahl, which has been found to be effective in treating cholestasis. However, its key component for alleviating cholestasis has not been determined. In this study, four representative active ingredients in forsythia fruit were selected. Through network pharmacology and molecular docking technology, we tried to find the key component for its treatment of cholestasis. Furthermore, the model of cholestasis in mice was established to verify the protective effect of the key component on cholestasis. Network pharmacology and molecular docking showed that forsythoside A (FTA) is the key component of forsythia fruit in the treatment of cholestasis. In vivo experiments revealed that FTA treatment could alleviate liver injury, dysfunction, and collagen deposition induced by cholestasis in mice. At the same time, FTA treatment inhibited inflammatory factor release and fibrosis-related factor expression. In addition, FTA treatment also reduced MMP-2, TLR4, MYD88, NF-κB p65, and p-NF-κB p65 protein expression. In conclusion, FTA, a key component of forsythia fruit, alleviated liver damage and fibrosis caused by cholestasis via inhibiting the TLR4/NF-κB pathway, extracellular matrix accumulation, and inflammatory cytokine expression. The research results could provide a scientific reference for the development of forsythia fruit as a drug or functional food to prevent and treat cholestasis.

Gut microbiota alters host bile acid metabolism to contribute to intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a female pregnancy-specific disorder that is characterized by increased serum bile acid and adverse fetal outcomes. The aetiology and mechanism of ICP are poorly understood; thus, existing therapies have been largely empiric. Here we show that the gut microbiome differed significantly between individuals with ICP and healthy pregnant women, and that colonization with gut microbiome from ICP patients was sufficient to induce cholestasis in mice. The gut microbiomes of ICP patients were primarily characterized by Bacteroides fragilis (B. fragilis), and B. fragilis was able to promote ICP by inhibiting FXR signaling via its BSH activity to modulate bile acid metabolism. B. fragilis-mediated FXR signaling inhibition was responsible for excessive bile acid synthesis and interrupted hepatic bile excretion to ultimately promote the initiation of ICP. We propose that modulation of the gut microbiota-bile acid-FXR axis may be of value for ICP treatment.

The Landscape of HNF1B Deficiency: A Syndrome Not Yet Fully Explored

The hepatocyte nuclear factor 1β (HNF1B) gene is involved in the development of specialized epithelia of several organs during the early and late phases of embryogenesis, performing its function mainly by regulating the cell cycle and apoptosis pathways. The first pathogenic variant of HNF1B (namely, R177X) was reported in 1997 and is associated with the maturity-onset diabetes of the young. Since then, more than 230 different HNF1B variants have been reported, revealing a multifaceted syndrome with complex and heterogenous genetic, pathologic, and clinical profiles, mainly affecting the pediatric population. The pancreas and kidneys are the most frequently affected organs, resulting in diabetes, renal cysts, and a decrease in renal function, leading, in 2001, to the definition of HNF1B deficiency syndrome, including renal cysts and diabetes. However, several other organs and systems have since emerged as being affected by HNF1B defect, while diabetes and renal cysts are not always present. Especially, liver involvement has generally been overlooked but recently emerged as particularly relevant (mostly showing chronically elevated liver enzymes) and with a putative relation with tumor development, thus requiring a more granular analysis. Nowadays, HNF1B-associated disease has been recognized as a clinical entity with a broader and more variable multisystem phenotype, but the reasons for the phenotypic heterogeneity are still poorly understood. In this review, we aimed to describe the multifaceted nature of HNF1B deficiency in the pediatric and adult populations: we analyzed the genetic, phenotypic, and clinical features of this complex and misdiagnosed syndrome, covering the most frequent, unusual, and recently identified traits.

Surgical and Medical Aspects of the Initial Treatment of Biliary Atresia: Position Paper

Biliary atresia, a fibro-obliterative disease of the newborn, is usually initially treated by Kasai portoenterostomy, although there are many variations in technique and different options for post-operative adjuvant medical therapy. A questionnaire on such topics (e.g., open vs. laparoscopic; the need for liver mobilisation; use of post-operative steroids; use of post-operative anti-viral therapy, etc.) was circulated to delegates (n = 43) of an international webinar (Biliary Atresia and Related Diseases-BARD) held in June 2021. Respondents were mostly European, but included some from North America, and represented 18 different countries overall. The results of this survey are presented here, together with a commentary and review from an expert panel convened for the meeting on current trends in practice.

Odevixibat: a promising new treatment for progressive familial intrahepatic cholestasis

INTRODUCTION

Progressive familial intrahepatic cholestasis (PFIC) refers to a group of heterogeneous, mostly autosomal recessive disorders resulting from the inability to properly form and excrete bile from hepatocytes. The resulting shared phenotype is one of hepatocellular cholestasis. Clinical management targeting refractory itch and surgical interventions to interrupt the enterohepatic circulation are often pursued with variable efficacy. Recent development of the family of IBAT inhibitor therapeutics has introduced a novel tool in the armamentarium for the treatment of PFIC.

AREAS COVERED

Data from Phase 3 and 3 clinical trials were reviewed. The primary endpoints in most studies included effect on pruritus, serum bile acid levels, and quality of life metrics, with the duration of the study ranging between 24 and 72 weeks. Most common adverse events included diarrhea, vomiting, and elevation in transaminases.

EXPERT OPINION

IBAT inhibition with therapeutics such as odevibixat have shown that it is well-tolerated and efficacious in mitigating itch and reducing serum bile acid levels. While the few early published trials with odevixibat have shown good efficacy, what remains to be seen is long-term, sustainable improvement and if or how these medications will supplement or replace the current medical and surgical therapies available for managing PFIC disorders.

Protocols of Investigation of Neonatal Cholestasis-A Critical Appraisal

Neonatal cholestasis (NC) starts during the first three months of life and comprises extrahepatic and intrahepatic groups of diseases, some of which have high morbimortality rates if not timely identified and treated. Prolonged jaundice, clay-colored or acholic stools, and choluria in an infant indicate the urgent need to investigate the presence of NC, and thenceforth the differential diagnosis of extra- and intrahepatic causes of NC. The differential diagnosis of NC is a laborious process demanding the accurate exclusion of a wide range of diseases, through the skillful use and interpretation of several diagnostic tests. A wise integration of clinical-laboratory, histopathological, molecular, and genetic evaluations is imperative, employing extensive knowledge about each evaluated disease as well as the pitfalls of each diagnostic test. Here, we review the difficulties involved in correctly diagnosing the cause of cholestasis in an affected infant.

Genetics in Familial Intrahepatic Cholestasis: Clinical Patterns and Development of Liver and Biliary Cancers: A Review of the Literature

The family of inherited intrahepatic cholestasis includes autosomal recessive cholestatic rare diseases of childhood involved in bile acids secretion or bile transport defects. Specific genetic pathways potentially cause many otherwise unexplained cholestasis or hepatobiliary tumours in a healthy liver. Lately, next-generation sequencing and whole-exome sequencing have improved the diagnostic procedures of familial intrahepatic cholestasis (FIC), as well as the discovery of several genes responsible for FIC. Moreover, mutations in these genes, even in the heterozygous status, may be responsible for cryptogenic cholestasis in both young and adults. Mutations in FIC genes can influence serum and hepatic levels of bile acids. Experimental studies on the NR1H4 gene have shown that high bile acids concentrations cause excessive production of inflammatory cytokines, resistance to apoptosis, and increased cell regeneration, all risk conditions for developing hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). NR1H4 gene encodes farnesoid X-activated receptor having a pivotal role in bile salts synthesis. Moreover, HCC and CCA can emerge in patients with several FIC genes such as ABCB11, ABCB4 and TJP2. Herein, we reviewed the available data on FIC-related hepatobiliary cancers, reporting on genetics to the pathophysiology, the risk factors and the clinical presentation.