Differences in presentation and progression between severe FIC1 and BSEP deficiencies

Molecular and computational characterization of ABCB11 and ABCG5 variants in Tunisian patients with neonatal/infantile low-GGT intrahepatic cholestasis: Genetic diagnosis and genotype-phenotype correlation assessment

Many inherited conditions cause hepatocellular cholestasis in infancy, including progressive familial intrahepatic cholestasis (PFIC), a heterogeneous group of diseases with highly overlapping symptoms. In our study, six unrelated Tunisian infants with PFIC suspicion were the subject of a panel-target sequencing followed by an exhaustive bioinformatic and modeling investigations. Results revealed five disease-causative variants including known ones: (the p.Asp482Gly and p.Tyr354 * in the ABCB11 gene and the p.Arg446 * in the ABCC2 gene), a novel p.Ala98Cys variant in the ATP-binding cassette subfamily G member 5 (ABCG5) gene and a first homozygous description of the p.Gln312His in the ABCB11 gene. The p.Gln312His disrupts the interaction pattern of the bile salt export pump as well as the flexibility of the second intracellular loop domain harboring this residue. As for the p.Ala98Cys, it modulates both the interactions within the first nucleotide-binding domain of the bile transporter and its accessibility. Two additional potentially modifier variants in cholestasis-associated genes were retained based on their pathogenicity (p.Gly758Val in the ABCC2 gene) and functionality (p.Asp19His in the ABCG8 gene). Molecular findings allowed a PFIC2 diagnosis in five patients and an unexpected diagnosis of sisterolemia in one case. The absence of genotype/phenotype correlation suggests the implication of environmental and epigenetic factors as well as modifier variants involved directly or indirectly in the bile composition, which could explain the cholestasis phenotypic variability.

Flipping the script: Advances in understanding how and why P4-ATPases flip lipid across membranes

Type IV P-type ATPases (P4-ATPases) are a family of transmembrane enzymes that translocate lipid substrates from the outer to the inner leaflet of biological membranes and thus create an asymmetrical distribution of lipids within membranes. On the cellular level, this asymmetry is essential for maintaining the integrity and functionality of biological membranes, creating platforms for signaling events and facilitating vesicular trafficking. On the organismal level, this asymmetry has been shown to be important in maintaining blood homeostasis, liver metabolism, neural development, and the immune response. Indeed, dysregulation of P4-ATPases has been linked to several diseases; including anemia, cholestasis, neurological disease, and several cancers. This review will discuss the evolutionary transition of P4-ATPases from cation pumps to lipid flippases, the new lipid substrates that have been discovered, the significant advances that have been achieved in recent years regarding the structural mechanisms underlying the recognition and flipping of specific lipids across biological membranes, and the consequences of P4-ATPase dysfunction on cellular and physiological functions. Additionally, we emphasize the requirement for additional research to comprehensively understand the involvement of flippases in cellular physiology and disease and to explore their potential as targets for therapeutics in treating a variety of illnesses. The discussion in this review will primarily focus on the budding yeast, C. elegans, and mammalian P4-ATPases.

UK guideline on the transition and management of childhood liver diseases in adulthood

INTRODUCTION

Improved outcomes of liver disease in childhood and young adulthood have resulted in an increasing number of young adults (YA) entering adult liver services. The adult hepatologist therefore requires a working knowledge in diseases that arise almost exclusively in children and their complications in adulthood.

AIMS

To provide adult hepatologists with succinct guidelines on aspects of transitional care in YA relevant to key disease aetiologies encountered in clinical practice.

METHODS

A systematic literature search was undertaken using the Pubmed, Medline, Web of Knowledge and Cochrane database from 1980 to 2023. MeSH search terms relating to liver diseases ('cholestatic liver diseases', 'biliary atresia', 'metabolic', 'paediatric liver diseases', 'autoimmune liver diseases'), transition to adult care ('transition services', 'young adult services') and adolescent care were used. The quality of evidence and the grading of recommendations were appraised using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

RESULTS

These guidelines deal with the transition of YA and address key aetiologies for the adult hepatologist under the following headings: (1) Models and provision of care; (2) screening and management of mental health disorders; (3) aetiologies; (4) timing and role of liver transplantation; and (5) sexual health and fertility.

CONCLUSIONS

These are the first nationally developed guidelines on the transition and management of childhood liver diseases in adulthood. They provide a framework upon which to base clinical care, which we envisage will lead to improved outcomes for YA with chronic liver disease.

Clinical symptoms, biochemistry, and liver histology during the native liver period of progressive familial intrahepatic cholestasis type 2

BACKGROUND

Progressive familial intrahepatic cholestasis type 2 (PFIC2) is an ultra-rare disease caused by mutations in the ABCB11 gene. This study aimed to understand the course of PFIC2 during the native liver period.

METHODS

From November 2014 to October 2015, a survey to identify PFIC2 patients was conducted in 207 hospitals registered with the Japanese Society of Pediatric Gastroenterology, Hepatology, and Nutrition. Investigators retrospectively collected clinical data at each facility in November 2018 using pre-specified forms.

RESULTS

Based on the biallelic pathogenic variants in ABCB11 and/or no hepatic immunohistochemical detection of BSEP, 14 Japanese PFIC2 patients were enrolled at seven facilities. The median follow-up was 63.2 [47.7-123.3] months. The median age of disease onset was 2.5 [1-4] months. Twelve patients underwent living donor liver transplantation (LDLT), with a median age at LDLT of 9 [4-57] months. Two other patients received sodium 4-phenylbutyrate (NaPB) therapy and survived over 60 months with the native liver. No patients received biliary diversion. The cases that resulted in LDLT had gradually deteriorated growth retardation, biochemical tests, and liver histology since the initial visit. In the other two patients, jaundice, growth retardation, and most of the biochemical tests improved after NaPB therapy was started, but pruritus and liver fibrosis did not.

CONCLUSIONS

Japanese PFIC2 patients had gradually worsening clinical findings since the initial visit, resulting in LDLT during infancy. NaPB therapy improved jaundice and growth retardation but was insufficient to treat pruritus and liver fibrosis.

Cav-1 regulates the bile salt export pump on the canalicular membrane of hepatocytes by PKCα-associated signalling under cholesterol stimulation

BACKGROUND AND AIMS

The secretion of bile salts transported by the bile salt export pump (BSEP) is the primary driving force for the generation of bile flow; thus, it is closely related to the formation of cholesterol stones. Caveolin-1 (Cav-1), an essential player in cell signalling and endocytosis, is known to co-localize with cholesterol-rich membrane domains. This study illustrates the role of Cav-1 and BSEP in cholesterol stone formation.

METHODS

Adult male C57BL/6 mice were used as an animal model. HepG2 cells were cultured under different cholesterol concentrations and BSEP, Cav-1, p-PKCα and Hax-1 expression levels were determined via Western blotting. Expression levels of BSEP and Cav-1 mRNA were detected using real-time PCR. Immunofluorescence and immunoprecipitation assays were performed to study BSEP and Hax-1 distribution. Finally, an ATPase activity assay was performed to detect BSEP transport activity under different cholesterol concentrations in cells.

RESULTS

Under low-concentration stimulation with cholesterol, Cav-1 and BSEP protein and mRNA expression levels significantly increased, PKCα phosphorylation significantly decreased, BSEP binding capacity to Hax-1 weakened, and BSEP function increased. Under high-concentration stimulation with cholesterol, Cav-1 and BSEP protein and mRNA expression levels decreased, PKCα phosphorylation increased, BSEP binding capacity to Hax-1 rose, and BSEP function decreased.

CONCLUSION

Cav-1 regulates the bile salt export pump on the canalicular membrane of hepatocytes via PKCα-associated signalling under cholesterol stimulation.

Neonatal cholestasis in children with Alpha-1-AT deficiency is a risk for earlier severe liver disease with male predominance

BACKGROUND

Our objective was to better understand the natural history and disease modifiers of Alpha-1-antitrypsin deficiency (AATD), a common genetic liver disease causing hepatitis and cirrhosis in adults and children. The clinical course is highly variable. Some infants present with neonatal cholestasis, which can resolve spontaneously or progress to cirrhosis; others are well in infancy, only to develop portal hypertension later in childhood.

METHODS

The Childhood Liver Disease Research Network has been enrolling AATD participants into longitudinal, observational studies at North American tertiary centers since 2004. We examined the clinical courses of 2 subgroups of participants from the several hundred enrolled; first, those presenting with neonatal cholestasis captured by a unique study, enrolled because of neonatal cholestasis but before specific diagnosis, then followed longitudinally (n=46); second, separately, all participants who progressed to liver transplant (n=119).

RESULTS

We found male predominance for neonatal cholestasis in AATD (65% male, p=0.04), an association of neonatal gamma-glutamyl transpeptidase elevation to more severe disease, and a higher rate of neonatal cholestasis progression to portal hypertension than previously reported (41%) occurring at median age of 5 months. Participants with and without preceding neonatal cholestasis were at risk of progression to transplant. Participants who progressed to liver transplant following neonatal cholestasis were significantly younger at transplant than those without neonatal cholestasis (4.1 vs. 7.8 years, p=0.04, overall range 0.3-17 years). Neonatal cholestasis had a negative impact on growth parameters. Coagulopathy and varices were common before transplant, but gastrointestinal bleeding was not.

CONCLUSIONS

Patients with AATD and neonatal cholestasis are at risk of early progression to severe liver disease, but the risk of severe disease extends throughout childhood. Careful attention to nutrition and growth is needed.

Postinfantile Giant Cell Hepatitis in Native and Allograft Livers: A Multi-Institutional Clinicopathologic Study of 70 Cases

Postinfantile giant cell hepatitis (PIGCH) is a rare hepatitis pattern in adults with variable etiologies and clinical outcomes. We conducted a multi-institutional retrospective study to define the clinicopathologic characteristics of patients with PIGCH. A total of 70 PIGCH cases were identified and reviewed for pathological features, including fibrosis, cholestasis, inflammation, steatosis, necrosis, and apoptosis, as well as the distribution of giant cells and the maximum number of giant cells per high-power field. Demographic and clinical data, including age, sex, laboratory results, etiologies, and follow-up results, were recorded. Among the 70 cases, 40% (28/70) were associated with autoimmune liver diseases, followed by 9 (13%) with unknown etiology, 8 (11%) with viral infection, 5 (7%) with medications, 5 with combined etiologies, and 4 (6%) with malignancies (mostly chronic lymphocytic leukemia). Notably, another 16% were de novo PIGCH in liver allografts, most of which occurred after a rejection event. During follow-up, 26 (37%) patients died of the disease and 44 (63%) were alive. Deceased patients were characterized by older age (mean age, 54.9 vs 45.5 years; P = .02), higher alkaline phosphatase level (mean value, 253.3U/L vs 166.3 U/L; P = .03), higher fibrosis stage (stage 3-4 vs stage 0-2, 57.7% vs 29.6%; P = .03), being more likely to have de novo PIGCH after transplantation (23.1% vs 11.4%; P = .04), and being less likely to have primary autoimmune liver disease etiology (26.9% vs 47.7%; P = .04). These results indicate that PIGCH is a rare pattern of liver injury associated with different etiologies and variable clinical outcomes. Autoimmune liver disease with PIGCH is associated with better survival, whereas de novo PIGCH in allografts is associated with poorer survival. Older age, higher alkaline phosphatase level, and advanced fibrosis are adverse prognostic factors.

Cholestasis: exploring the triangular relationship of gut microbiota-bile acid-cholestasis and the potential probiotic strategies

Cholestasis is a condition characterized by the abnormal production or excretion of bile, and it can be induced by a variety of causes, the factors of which are extremely complex. Although great progress has been made in understanding cholestasis pathogenesis, the specific mechanisms remain unclear. Therefore, it is important to understand and distinguish cholestasis from different etiologies, which will also provide indispensable theoretical support for the development of corresponding therapeutic drugs. At present, the treatment of cholestasis mainly involves several bile acids (BAs) and their derivatives, most of which are in the clinical stage of development. Multiple lines of evidence indicate that ecological disorders of the gut microbiota are strongly related to the occurrence of cholestasis, in which BAs also play a pivotal role. Recent studies indicate that probiotics seem to have certain effects on cholestasis, but further confirmation from clinical trials is required. This paper reviews the etiology of and therapeutic strategies for cholestasis; summarizes the similarities and differences in inducement, symptoms, and mechanisms of related diseases; and provides information about the latest pharmacological therapies currently available and those under research for cholestasis. We also reviewed the highly intertwined relationship between gut microbiota-BA-cholestasis, revealing the potential role and possible mechanism of probiotics in the treatment of cholestasis.

The phospholipid flippase ATP8B1 is required for lysosomal fusion in macrophages

ATP8B1 is a phospholipid flippase and member of the type 4 subfamily of P-type ATPases (P4-ATPase) subfamily. P4-ATPases catalyze the translocation of phospholipids across biological membranes, ensuring proper membrane asymmetry, which is crucial for membrane protein targeting and activity, vesicle biogenesis, and barrier function. Here we have investigated the role of ATP8B1 in the endolysosomal pathway in macrophages. Depletion of ATP8B1 led to delayed degradation of content in the phagocytic pathway and in overacidification of the endolysosomal system. Furthermore, ATP8B1 knockdown cells exhibited large multivesicular bodies filled with intraluminal vesicles. Similar phenotypes were observed in CRISPR-generated ATP8B1 knockout cells. Importantly, induction of autophagy led to accumulation of autophagosomes in ATP8B1 knockdown cells. Collectively, our results support a novel role for ATP8B1 in lysosomal fusion in macrophages, a process crucial in the terminal phase of endolysosomal degradation.

Genotype-phenotype relationships of truncating mutations, p.E297G and p.D482G in bile salt export pump deficiency

Background & Aims

Bile salt export pump (BSEP) deficiency frequently necessitates liver transplantation in childhood. In contrast to two predicted protein truncating mutations (PPTMs), homozygous p.D482G or p.E297G mutations are associated with relatively mild phenotypes, responsive to surgical interruption of the enterohepatic circulation (siEHC). The phenotype of patients with a compound heterozygous genotype of one p.D482G or p.E297G mutation and one PPTM has remained unclear. We aimed to assess their genotype-phenotype relationship.

Methods

From the NAPPED database, we selected patients with homozygous p.D482G or p.E297G mutations (BSEP1/1; n = 31), with one p.D482G or p.E297G, and one PPTM (BSEP1/3; n = 30), and with two PPTMs (BSEP3/3; n = 77). We compared clinical presentation, native liver survival (NLS), and the effect of siEHC on NLS.

Results

The groups had a similar median age at presentation (0.7-1.3 years). Overall NLS at age 10 years was 21% in BSEP1/3 vs. 75% in BSEP1/1 and 23% in BSEP3/3 (p <0.001). Without siEHC, NLS in the BSEP1/3 group was similar to that in BSEP3/3, but considerably lower than in BSEP1/1 (at age 10 years: 38%, 30%, and 71%, respectively; p = 0.003). After siEHC, BSEP1/3 and BSEP3/3 were associated with similarly low NLS, while NLS was much higher in BSEP1/1 (10 years after siEHC, 27%, 14%, and 92%, respectively; p <0.001).

Conclusions

Individuals with BSEP deficiency with one p.E297G or p.D482G mutation and one PPTM have a similarly severe disease course and low responsiveness to siEHC as those with two PPTMs. This identifies a considerable subgroup of patients who are unlikely to benefit from interruption of the enterohepatic circulation by either surgical or ileal bile acid transporter inhibitor treatment.

Impact and implications

This manuscript defines the clinical features and prognosis of individuals with BSEP deficiency involving the combination of one relatively mild and one very severe BSEP deficiency mutation. Until now, it had always been assumed that the mild mutation would be enough to ensure a relatively good prognosis. However, our manuscript shows that the prognosis of these patients is just as poor as that of patients with two severe mutations. They do not respond to biliary diversion surgery and will likely not respond to the new IBAT (ileal bile acid transporter) inhibitors, which have recently been approved for use in BSEP deficiency.

ATP8B1 Deficiency Results in Elevated Mitochondrial Phosphatidylethanolamine Levels and Increased Mitochondrial Oxidative Phosphorylation in Human Hepatoma Cells

ATP8B1 is a phospholipid flippase that is deficient in patients with progressive familial intrahepatic cholestasis type 1 (PFIC1). PFIC1 patients suffer from severe liver disease but also present with dyslipidemia, including low plasma cholesterol, of yet unknown etiology. Here we show that ATP8B1 knockdown in HepG2 cells leads to a strong increase in the mitochondrial oxidative phosphorylation (OXPHOS) without a change in glycolysis. The enhanced OXPHOS coincides with elevated low-density lipoprotein receptor protein and increased mitochondrial fragmentation and phosphatidylethanolamine levels. Furthermore, expression of phosphatidylethanolamine N-methyltransferase, an enzyme that catalyzes the conversion of mitochondrial-derived phosphatidylethanolamine to phosphatidylcholine, was reduced in ATP8B1 knockdown cells. We conclude that ATP8B1 deficiency results in elevated mitochondrial PE levels that stimulate mitochondrial OXPHOS. The increased OXPHOS leads to elevated LDLR levels, which provides a possible explanation for the reduced plasma cholesterol levels in PFIC1 disease.

New insights into the bile acid-based regulatory mechanisms and therapeutic perspectives in alcohol-related liver disease

Cholestasis is a key causative factor in alcohol-related liver disease (ALD) and variable degrees of cholestasis occur in all stages of ALD. However, the pathogenetic mechanisms and biomarkers associated with cholestasis are not well characterized. Cholestatic disease is marked by the disruption of bile acids (BA) transport and homeostasis. Consequently, in both human and experimental ALD, the disease shows a direct correlation with an imbalance in BA equilibrium, which in turn may also affect the severity of the disease. Modulation of BA metabolism or signaling pathways is increasingly considered as a potential therapeutic strategy for ALD in humans. In this paper, we highlight the key advances made in the past two decades in characterizing the molecular regulatory mechanisms of BA synthesis, enterohepatic circulation, and BA homeostasis. We summarize recent insights into the nature of the linkage between BA dysregulation and ALD, including the abnormal expression of genes involved in BA metabolism, abnormal changes in receptors that regulate BA metabolism, and disturbance in the gut flora engaged in BA metabolism caused by alcohol consumption. Additionally, we provide novel perspectives on the changes in BAs in various stages of ALD. Finally, we propose potential pharmacological therapies for ALD targeting BA metabolism and signaling.

Overview of Progressive Familial Intrahepatic Cholestasis

Bile acid transport is a complex physiologic process, of which disruption at any step can lead to progressive intrahepatic cholestasis (PFIC). The first described PFIC disorders were originally named as such before identification of a genetic cause. However, advances in clinical molecular genetics have led to the identification of additional disorders that can cause these monogenic inherited cholestasis syndromes, and they are now increasingly referred to by the affected protein causing disease. The list of PFIC disorders is expected to grow as more causative genes are discovered. Here forth, we present a comprehensive overview of known PFIC disorders.

Clinical phenotype of adult-onset liver disease in patients with variants in ABCB4, ABCB11, and ATP8B1

Variants in ATP8B1, ABCB11, and ABCB4 underlie the most prevalent forms of progressive familial intrahepatic cholestasis. We aim to describe variants in these genes in a cohort of patients with adult‐onset liver disease, and explore a genotype–phenotype correlation. Patients with onset of liver disease aged above 18 who underwent sequencing of cholestasis genes for clinical purposes over a 5‐year period were identified. Bioinformatic analysis of variants was performed. Liver histology was evaluated in patients with variants. Of the 356 patients tested, at least one variant was identified in 101 (28.4%): 46 ABCB4, 35 ABCB11, and 28 ATP8B1. Patients with ABCB4 variants had chronic liver disease (71.7%) and pregnancy‐associated liver dysfunction (75%), with a younger age of onset in more severe genotypes (p = 0.046). ABCB11 variants presented with pregnancy‐associated liver dysfunction (82.4%) and acute/episodic cholestasis (40%), with no association between age of onset and genotype severity. ATP8B1 variants were associated with chronic liver disease (75%); however, they were commonly seen in patients with an alternate etiology of liver disease and variants were of low predicted pathogenicity. In adults with suspected genetic cholestasis, variants in cholestasis genes were frequently identified and were likely to contribute to the development of liver disease, particularly ABCB4 and ABCB11. Variants were often in heterozygous state, and they should no longer be considered recessive Mendelian traits. Sequencing cholestasis genes in selected patients with adult‐onset disease should be considered, with interpretation in close collaboration with histopathologists and geneticists.

Variants in cholestasis genes were found in patients with adult‐onset liver disease. ABCB4 variants are associated with chronic biliary disease, variants in ABCB11 are seen in patients with acute cholestasis, and the clinical significance of ATP8B1 variants is not clear.

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.

The Effect of Sex and Obesity on the Gene Expression of Lipid Flippases in Adipose Tissue

Molecular mechanisms behind obesity and sex-related effects in adipose tissue remain elusive. During adipocyte expansion, adipocytes undergo drastic remodelling of lipid membrane compositions. Lipid flippases catalyse phospholipid translocation from exoplasmic to the cytoplasmic leaflet of membranes. The present study aimed to analyse the effect of sex, obesity, and their interactions on the gene expression of two lipid flippases—ATP8A1 and ATP8B1—and their possible microRNA (miR) modulators in visceral adipose tissue (VAT). In total, 12 normal-weight subjects (5 premenopausal women and 7 men) and 13 morbidly obese patients (7 premenopausal women and 6 men) were submitted to surgery, and VAT samples were obtained. Gene expression levels of ATP8A1, ATP8B1, miR-548b-5p, and miR-4643 were measured in VAT. Our results showed a marked influence of obesity on VAT ATP8A1 and ATP8B1, although the effects of obesity were stronger in men for ATP8A1. Both genes positively correlated with obesity and metabolic markers. Furthermore, ATP8B1 was positively associated with miR-548b-5p and negatively associated with miR-4643. Both miRs were also affected by sex. Thus, lipid flippases are altered by obesity in VAT in a sex-specific manner. Our study provides a better understanding of the sex-specific molecular mechanisms underlying obesity, which may contribute to the development of sex-based precision medicine.

Cholestatic liver diseases of genetic etiology: Advances and controversies

With the application of modern investigative technologies, cholestatic liver diseases of genetic etiology are increasingly identified as the root cause of previously designated "idiopathic" adult and pediatric liver diseases. Here, we review advances in the field enhanced by a deeper understanding of the phenotypes associated with specific gene defects that lead to cholestatic liver diseases. There are evolving areas for clinicians in the current era specifically regarding the role for biopsy and opportunities for a "sequencing first" approach. Risk stratification based on the severity of the genetic defect holds promise to guide the decision to pursue primary liver transplantation versus medical therapy or nontransplant surgery, as well as early screening for HCC. In the present era, the expanding toolbox of recently approved therapies for hepatologists has real potential to help many of our patients with genetic causes of cholestasis. In addition, there are promising agents under study in the pipeline. Relevant to the current era, there are still gaps in knowledge of causation and pathogenesis and lack of fully accepted biomarkers of disease progression and pruritus. We discuss strategies to overcome the challenges of genotype-phenotype correlation and draw attention to the extrahepatic manifestations of these diseases. Finally, with attention to identifying causes and treatments of genetic cholestatic disorders, we anticipate a vibrant future of this dynamic field which builds upon current and future therapies, real-world evaluations of individual and combined therapeutics, and the potential incorporation of effective gene editing and gene additive technologies.

Extrahepatic manifestations of progressive familial intrahepatic cholestasis syndromes: Presentation of a case series and literature review

BACKGROUND AND AIMS

Progressive familial intrahepatic cholestasis (PFIC) is a collective term for a heterogenous group of rare, inherited cholestasis syndromes. The number of genes underlying the clinical PFIC phenotype is still increasing. While progressive liver disease and its sequelae such as portal hypertension, pruritus and hepatocellular carcinoma determine transplant-free survival, extrahepatic manifestations may cause relevant morbidity.

METHODS

We performed a literature search for extrahepatic manifestations of PFIC associated with pathogenic gene variants in ATP8B1, ABCB11, ABCB4, TJP2, NR1H4 and MYO5B. To illustrate the extrahepatic symptoms described in the literature, PFIC cases from our centres were revisited.

RESULTS

Extrahepatic symptoms are common in PFIC subtypes, where the affected gene is expressed at high levels in other tissues. While most liver-associated complications resolve after successful orthotopic liver transplantation (OLT), some extrahepatic symptoms show no response or even worsen after OLT.

CONCLUSION

The spectrum of extrahepatic manifestations in PFIC highlights essential, non-redundant roles of the affected genes in other organs. Extrahepatic features contribute towards low health-related quality of life (HRQOL) and morbidity in PFIC. While OLT is often the only remaining, curative treatment, potential extrahepatic manifestations need to be carefully monitored and addressed.

Alcohol triggered bile acid disequilibrium by suppressing BSEP to sustain hepatocellular carcinoma progression

Bile acids (BAs), the most important components of bile, attribute predominately to maintain metabolic homeostasis. In hepatocellular carcinoma (HCC) patients, the BAs homeostasis was seriously disturbed, especially in those patients with alcohol-intake history. However, whether alcohol consumption could promote HCC progression via influencing BAs homeostasis and the precise mechanism underlying are still unclear. In our study, by collecting HCC specimens from both alcohol-drinkers (n = 15) and non-alcohol drinkers (n = 22), we found that compared to non-alcohol intake HCC patients, BAs homeostasis was disturbed in HCC patients who drank alcohol. Furthermore, ethanol treatment was also found to promote HCC progression by markedly activating oncogenes (RAS, MYC, MET, and HER2), while remarkably suppressing tumor suppressor genes (BRCA2 and APC). We evaluated 14 key functional genes that maintain the homeostasis of BAs and found that either in alcohol-intake HCC patients (n = 15), or in ethanol-treated mice, BSEP, rate-limiting transporter governing excreting BAs from liver into bile duct, was remarkably decreased when exposed to alcohol. Moreover, by screening for changes in the epigenetic landscape of liver cancer cells exposed to alcohol, we strikingly found that histone methyltransferases (RBBP-5, Suv39h1, ASH2L, and SET7/9) were increased, and KMT3B, KMT4, and KMT7 gene expression was also elevated, while histone demethyltransferases (JARID1a, JARID1b, JARID1c) were decreased. In summary, we found that alcohol could trigger BAs disequilibrium to initiate and promote HCC progression. Our study provided a novel and supplementary mechanism to determine the important role of alcohol-intake in HCC development regarding from the perspective of BAs homeostasis.

A Current Understanding of Bile Acids in Chronic Liver Disease

Chronic liver disease (CLD) is one of the leading causes of disability-adjusted life years in many countries. A recent understanding of nuclear bile acid receptor pathways has increased focus on the impact of crosstalk between the gut, bile acids, and liver on liver pathology. While conventionally used in cholestatic disorders and to dissolve gallstones, the discovery of bile acids' influence on the gut microbiome and human metabolism offers a unique potential for their utility in early and advanced liver diseases because of diverse etiologies. Based on these findings, preclinical studies using bile acid-based molecules have shown encouraging results at addressing liver inflammation and fibrosis. Emerging data also suggest that bile acid profiles change distinctively across various causes of liver disease. We summarize the current knowledge and evidence related to bile acids in health and disease and discuss culminated and ongoing therapeutic trials of bile acid derivatives in CLD. In the near future, further evidence in this area might help clinicians better detect and manage liver diseases.

Heterozygous mutations of ATP8B1, ABCB11 and ABCB4 cause mild forms of Progressive Familial Intrahepatic Cholestasis in a pediatric cohort

INTRODUCTION

Heterozygous defects in genes implicated in Progressive Familial Intrahepatic Cholestasis have been described in milder forms of cholestatic diseases. Our aim is to describe clinical, laboratory and imaging characteristics as well as treatment and outcome of a cohort of pediatric patients with heterozygous mutations in ATP8B1, ABCB11 or ABCB4.

PATIENTS AND METHODS

We present a retrospective descriptive study including pediatric patients with at least one heterozygosis defect in ATP8B1, ABCB11 or ABCB4 diagnosed after a cholestatic episode. Clinical, diagnostic and outcome data were collected including gene analysis (panel of PFIC NextGeneDx®).

RESULTS

7 patients showed a heterozygous mutation: 3 patients in ABCB4, 1 in ABCB11, 2 in ABCB4 and ABCB11 and 1 in ATP8B1. The median onset age was 5.5 years with a median time of follow-up of 6 years. The initial presentation was pruritus followed by asymptomatic hypertransaminasemia and persistent cholestasis. Two patients had family history of gallbladder stones and mild hepatitis. All showed elevated transaminases and bile acids, high gamma glutamyl-transferase (GGT) in 3 and conjugated bilirubin in 2 patients. Liver biopsy showed inflammatory infiltrate or mild fibrosis with normal immunohistochemistry. All patients were treated with ursodeoxycholic acid, two patients requiring the addition of resincholestyramine. During follow-up, 3 patients suffered limited relapses of pruritus. No disease progression was observed.

CONCLUSION

Heterozygous mutations in genes coding proteins of the hepatocellular transport system can cause cholestatic diseases with great phenotypic variability. The presence of repeated episodes of hypertransaminasemia or cholestasis after a trigger should force us to rule out the presence of these heterozygous mutations in genes involved in CIFP.

Liver tumors in children with chronic liver diseases

Liver tumors are rare in children, but the incidence may increase in some circumstances and particularly in chronic liver diseases. Most liver tumors consequent to chronic liver diseases are malignant hepatocellular carcinoma. Other liver tumors include hepatoblastoma, focal nodular hyperplasia, adenoma, pseudotumor, and nodular regenerative hyperplasia. Screening of suspected cases is beneficial. Imaging and surrogate markers of alpha-fetoprotein are used initially as noninvasive tools for surveillance. However, liver biopsy for histopathology evaluation might be necessary for patients with inconclusive findings. Once the malignant liver tumor is detected in children with cirrhosis, liver transplantation is currently considered the preferred option and achieves favorable outcomes. Based on the current evidence, this review focuses on liver tumors with underlying chronic liver disease, their epidemiology, pathogenesis, early recognition, and effective management.

Regulatory mechanisms of the bile salt export pump (BSEP/ABCB11) and its role in related diseases

The bile salt export pump (BSEP/ABCB11) is located on the apical membrane and mediates the secretion of bile salts from hepatocytes into the bile. BSEP-mediated bile salt efflux is the rate-limiting step of bile salt secretion and the main driving force of bile flow. BSEP drives and maintains the enterohepatic circulation of bile salts. In recent years, research efforts have been focused on understanding the physiological and pathological functions and regulatory mechanisms of BSEP. These studies elucidated the roles of farnesoid X receptor (FXR), AMP-activated protein kinase (AMPK), liver receptor homolog-1(LRH-1) and nuclear factor erythroid 2-related factor 2 (Nrf-2) in BSEP expression and discovered some regulatory factors which participate in its post-transcriptional regulation. A series of liver diseases have also been shown to be related to BSEP expression and dysfunction, such as cholestasis, drug-induced liver injury, and gallstones. Here, we systematically review and summarize recent literature on BSEP structure, physiological functions, regulatory mechanisms, and related diseases.

Reversal of portal gastropathy with partial internal biliary diversion in a case of progressive familial intrahepatic cholestasis

Progressive intrahepatic cholestasis is a rare, genetic disorder causing bile acid secretion or transport defects. It can result in intrahepatic cholestasis that can progress to end-stage liver disease. Diagnosis is made using a combination of clinical and biochemical approaches. Genetic testing is currently the gold standard for investigation.

We report a case of an 18-month-old male child with cholestatic pattern of jaundice from 16 months of life, which was associated with features suggestive of portal gastropathy. Detailed workup led to the diagnosis of progressive intrahepatic cholestasis (type 2). Early diagnosis prevented the need for liver transplant, and the child underwent surgical treatment with partial internal biliary diversion. Portal gastropathy and disease progression dramatically changed with corrective surgery. The patient was symptom-free at 10-week follow-up.

Detecting this rare genetic disorder early has very good therapeutic implications from the patient's perspective and their morbidity and mortality profile; if untreated, it has a high propensity to progress to end-stage liver disease. The requirement of surgical interventions and liver transplantation is individualized on a case-to-case basis. An early diagnosis and initiation of treatment can prevent the need for a liver transplant as shown in the present case.

The spectrum of Progressive Familial Intrahepatic Cholestasis diseases: Update on pathophysiology and emerging treatments

The Progressive Familial Intrahepatic Cholestasis (PFIC) disease spectrum encompasses a variety of genetic diseases that affect the bile production and the secretion of bile acids. Typically, the first presentation of these diseases is in early childhood, frequently followed by a severe course necessitating liver transplantation before adulthood. Except for transplantation, treatment modalities have been rather limited and frequently only aim at the symptoms of cholestasis, such as cholestatic pruritus. In recent years, progress has been made in understanding the pathophysiology of these diseases and new treatment modalities have been emerging. Herewith we summarize the latest developments in the field and formulate the current key questions and opportunities for further progress.

ATP8B1, ABCB11, and ABCB4 Genes Defects: Novel Mutations Associated with Cholestasis with Different Phenotypes and Outcomes

OBJECTIVES

To characterize the clinical, laboratory, histologic, molecular features, and outcome of gene-confirmed progressive familial intrahepatic cholestasis (PFIC) 1-3 among Arabs and to evaluate for "genotype-phenotype" correlations.

STUDY DESIGN

We retrospectively reviewed charts of 65 children (ATP8B1 defect = 5, ABCB11 = 35, ABCB4 = 25) who presented between 2008 and 2019 with cholestasis. The clinical phenotype of a disease was categorized based on response of cholestasis and itching to ursodeoxycholic acid and ultimate outcome, into mild (complete response), intermediate (partial response, nonprogressive), and severe (progression to end-stage liver disease).

RESULTS

Overall, 27 different mutations were identified (ATP8B1, n = 5; ABCB11, n = 11; ABCB4, n = 11), comprising 10 novel ones. Six patients with heterozygous missense mutations (ATP8B1, n = 2; ABCB11, n = 4) had transient cholestasis. Of the remaining 3 patients with PFIC1, 2 developed severe phenotype (splicing and frameshift mutations). Of the remaining 31 patients with PFIC2, 25 developed severe disease (15 due to frameshift and splicing mutations). Of 25 patients with PFIC3, 10 developed a severe phenotype (1 splicing and 3 frameshift mutations; 6 missense). Patients with PFIC2 had significantly shorter survival time and more rapid disease progression than patients with PFIC3 (P < .001). Patients with frameshift mutations in ABCB11 gene (p.Thr127Hisfs∗6) and ABCB4 gene (p.Phe210Serfs∗5) had significantly shorter survival time than missense mutations (P = .011; P = .0039, respectively).

CONCLUSIONS

We identified genotype-phenotype correlations among mutations in ABCB11 and ABCB4 genes, which underscore the prognostic value of early genetic diagnosis. The disease course in patients with PFIC3 could be favorably modified by ursodeoxycholic acid therapy.

Long-Term Outcome after Liver Transplantation for Progressive Familial Intrahepatic Cholestasis

Background and Objectives: Progressive familial intrahepatic cholestasis (PFIC) is a rare autosomal recessive inherited disease divided into five types (PFIC 1-5). Characteristic for all types is early disease onset, which may result clinically in portal hypertension, fibrosis, cirrhosis, hepatocellular carcinoma (HCC), and extrahepatic manifestations. Liver transplantation (LT) is the only successful treatment approach. Our aim is to present the good long-term outcomes after liver transplantation for PFIC1, focusing on liver function as well as the occurrence of extrahepatic manifestation after liver transplantation. Materials and Methods: A total of seven pediatric patients with PFIC1 underwent liver transplantation between January 1999 and September 2019 at the Department of Surgery, Charité Campus Virchow Klinikum and Charité Campus Mitte of Charité-Universitätsmedizin Berlin. Long-term follow-up data were collected on all patients, specifically considering liver function and extrahepatic manifestations. Results: Seven (3.2%) recipients were found from a cohort of 219 pediatric patients. Two of the seven patients had multilocular HCC in cirrhosis. Disease recurrence or graft loss did not occur in any patient. Two patients (male, siblings) had persistently elevated liver parameters but showed excellent liver function. Patient and graft survival during long-term follow-up was 100%, and no severe extrahepatic manifestations requiring hospitalization or surgery occurred. We noted a low complication rate during long-term follow-up and excellent patient outcome. Conclusions: PFIC1 long-term follow-up after LT shows promising results for this rare disease. In particular, the clinical relevance of extrahepatic manifestations seems acceptable, and graft function seems to be barely affected. Further multicenter studies are needed to analyze the clinically inhomogeneous presentation and to better understand the courses after LT.

Mutation Analysis and Disease Features at Presentation in a Multi-Center Cohort of Children With Monogenic Cholestasis

OBJECTIVES

To advance our understanding of monogenic forms of intrahepatic cholestasis.

METHODS

Analyses included participants with pathogenic biallelic mutations in adenosine triphosphate (ATP)-binding cassette subfamily B member 11 (ABCB11) (bile salt export pump; BSEP) or adenosine triphosphatase (ATPase) phospholipid transporting 8B1 (ATP8B1) (familial intrahepatic cholestasis; FIC1), or those with monoallelic or biallelic mutations in adenosine triphosphate (ATP)-binding cassette subfamily B member 4 (ABCB4) (multidrug resistance; MDR3), prospectively enrolled in the Longitudinal Study of Genetic Causes of Intrahepatic Cholestasis (LOGIC; NCT00571272) between November 2007 and December 2013. Summary statistics were calculated to describe baseline demographics, history, anthropometrics, laboratory values, and mutation data.

RESULTS

Ninety-eight participants with FIC1 (n = 26), BSEP (n = 53, including 8 with biallelic truncating mutations [severe] and 10 with p.E297G or p.D482G [mild]), or MDR3 (n = 19, including four monoallelic) deficiency were analyzed. Thirty-five had a surgical interruption of the enterohepatic circulation (sEHC), including 10 who underwent liver transplant (LT) after sEHC. Onset of symptoms occurred by age 2 years in most with FIC1 and BSEP deficiency, but was later and more variable for MDR3. Pruritus was nearly universal in FIC1 and BSEP deficiency. In participants with native liver, failure to thrive was common in FIC1 deficiency, high ALT was common in BSEP deficiency, and thrombocytopenia was common in MDR3 deficiency. sEHC was successful after more than 1 year in 7 of 19 participants with FIC1 and BSEP deficiency. History of LT was most common in BSEP deficiency. Of 102 mutations identified, 43 were not previously reported.

CONCLUSIONS

In this cohort, BSEP deficiency appears to be correlated with a more severe disease course. Genotype-phenotype correlations in these diseases are not straightforward and will require the study of larger cohorts.

Impact of Genotype, Serum Bile Acids, and Surgical Biliary Diversion on Native Liver Survival in FIC1 Deficiency

BACKGROUND AND AIMS

Mutations in ATPase phospholipid transporting 8B1 (ATP8B1) can lead to familial intrahepatic cholestasis type 1 (FIC1) deficiency, or progressive familial intrahepatic cholestasis type 1. The rarity of FIC1 deficiency has largely prevented a detailed analysis of its natural history, effects of predicted protein truncating mutations (PPTMs), and possible associations of serum bile acid (sBA) concentrations and surgical biliary diversion (SBD) with long-term outcome. We aimed to provide insights by using the largest genetically defined cohort of patients with FIC1 deficiency to date.

APPROACH AND RESULTS

This multicenter, combined retrospective and prospective study included 130 patients with compound heterozygous or homozygous predicted pathogenic ATP8B1 variants. Patients were categorized according to the number of PPTMs (i.e., splice site, frameshift due to deletion or insertion, nonsense, duplication), FIC1-A (n = 67; no PPTMs), FIC1-B (n = 29; one PPTM), or FIC1-C (n = 34; two PPTMs). Survival analysis showed an overall native liver survival (NLS) of 44% at age 18 years. NLS was comparable among FIC1-A, FIC1-B, and FIC1-C (% NLS at age 10 years: 67%, 41%, and 59%, respectively; P = 0.12), despite FIC1-C undergoing SBD less often (% SBD at age 10 years: 65%, 57%, and 45%, respectively; P = 0.03). sBAs at presentation were negatively associated with NLS (NLS at age 10 years, sBAs < 194 µmol/L: 49% vs. sBAs ≥ 194 µmol/L: 15%; P = 0.03). SBD decreased sBAs (230 [125-282] to 74 [11-177] μmol/L; P = 0.005). SBD (HR 0.55, 95% CI 0.28-1.03, P = 0.06) and post-SBD sBA concentrations < 65 μmol/L (P = 0.05) tended to be associated with improved NLS.

CONCLUSIONS

Less than half of patients with FIC1 deficiency reach adulthood with native liver. The number of PPTMs did not associate with the natural history or prognosis of FIC1 deficiency. sBA concentrations at initial presentation and after SBD provide limited prognostic information on long-term NLS.

A Report of 2 Infant Siblings with Progressive Intrahepatic Familial Cholestasis Type 1 and a Novel Homozygous Mutation in the ATP8B1 Gene Treated with Partial External Biliary Diversion and Liver Transplant

Case series

Patients: Male • Male / (siblings)

Final Diagnosis: Progressive intrahepatic familial cholestasis type 1 (PFIC-1)

Symptoms: Jaundice

Medication: —

Clinical Procedure: —

Specialty: Transplantology

Triggers of benign recurrent intrahepatic cholestasis and its pathophysiology: a review of literature

Benign recurrent intrahepatic cholestasis (BRIC) is a rare genetic disorder that is characterized by episodes of cholestasis followed by complete resolution. The episodic nature of BRIC raises concerns about its possible trigger factors. Indeed, case reports of this orphan disease have associated BRIC to some triggers. In the absence of any reviews, we reviewed BRIC trigger factors and its pathophysiology. The study consisted of a systematic search for case reports using PubMed. Articles describing a clear case of BRIC associated with a trigger were included resulting in 22 articles that describe 35 patients. Infection was responsible for 54.3% of triggered episodes, followed by hormonal, drugs, and miscellaneous causes reporting as 30%, 10%, and 5.7% respectively. Females predominated with 62.9%. The longest episode ranged between 3 months to 2 years with a mean of 32.37 weeks. The mean age of the first episode was 14.28 ranging between 3 months to 48 years. Winter and autumn were the major seasons during which episodes happened. Hence, BRIC is potentially triggered by infection, which is most commonly a viral infection, hormonal disturbances as seen in oral contraceptive pills and pregnancy state, and less commonly by certain drugs and other causes. The appearance of cholestasis during the first two trimesters of pregnancy compared to intrahepatic cholestasis of pregnancy could help to differentiate between the two conditions. The possible mechanism of BRIC induction implicates a role of BSEP and ATP8B1. While estrogen, drugs, and cytokines are known to affect BSEP, less is known about their action on ATP8B1.

Epidemiology and burden of progressive familial intrahepatic cholestasis: a systematic review

Background

Progressive familial intrahepatic cholestasis is a rare, heterogeneous group of liver disorders of autosomal recessive inheritance, characterised by an early onset of cholestasis with pruritus and malabsorption, which rapidly progresses, eventually culminating in liver failure. For children and their parents, PFIC is an extremely distressing disease. Significant pruritus can lead to severe cutaneous mutilation and may affect many activities of daily living through loss of sleep, irritability, poor attention, and impaired school performance.

Methods

Databases including MEDLINE and Embase were searched for publications on PFIC prevalence, incidence or natural history, and the economic burden or health-related quality of life of patients with PFIC. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed.

Results

Three systematic reviews and twenty-two studies were eligible for inclusion for the epidemiology of PFIC including a total of 2603 patients. Study periods ranged from 3 to 33 years. Local population prevalence of PFIC was reported in three studies, ranging from 9.0 to 12.0% of children admitted with cholestasis, acute liver failure, or splenomegaly. The most detailed data come from the NAPPED study where native liver survival of >15 years is predicted in PFIC2 patients with a serum bile  acid concentration below 102 µmol/L following bile diversion surgery. Burden of disease was mainly reported through health-related quality of life (HRQL), rates of surgery and survival. Rates of biliary diversion and liver transplant varied widely depending on study period, sample size and PFIC type, with many patients have multiple surgeries and progressing to liver transplant. This renders data unsuitable for comparison.

Conclusion

Using robust and transparent methods, this systematic review summarises our current knowledge of PFIC. The epidemiological overview is highly mixed and dependent on presentation and PFIC subtype. Only two studies reported HRQL and mortality results were variable across different subtypes. Lack of data and extensive heterogeneity severely limit understanding across this disease area, particularly variation around and within subtypes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01884-4.

Pediatric Hepatocellular Carcinoma

PURPOSE

Pediatric hepatocellular carcinoma is rarely seen in childhood. It constitutes approximately 1% of childhood solid organ malignancies. Pediatric hepatocellular carcinoma is the second most common malignant liver tumor after hepatoblastoma in children. In this review, we aimed to review the diagnosis and treatment of pediatric hepatocellular carcinoma in the light of the latest literature.

METHODS

We reviewed the literature in terms of the diagnosis and treatment of pediatric hepatocellular carcinoma.

RESULTS

Hepatocellular carcinoma (HCC) and hepatoblastoma constitute 0.5-1.5% of all childhood malignant tumors. HCC is responsible for 27% of all liver tumors and 4% of all pediatric liver transplantations. While 99.6% of HCC is seen in adults, only 0.4% of it is seen in pediatric patients. Etiological predisposition and biological behavior are different from adults. In a child with cirrhosis or liver disease, HCC should be suspected in the presence of a high level of AFP and an abnormal nodule on ultrasonography. Hepatoblastoma should be considered first in the differential diagnosis.

CONCLUSION

Treatment of pediatric HCC is challenging. Complete surgical resection is essential for the cure. To this end, different neoadjuvant chemotherapy protocols have been designed to convert non-resectable tumors into resectable tumors. For tumors that cannot be resected, liver transplantation for each patient with childhood HCC should be decided individually.

Cholestasis Due to USP53 Deficiency

OBJECTIVES

Although a number of genetic forms of cholestasis have been identified, the genetic etiology of disease remains unidentified in a subset of cholestasis patients.

METHODS

Whole exome sequencing (WES) was performed in DNA from patients diagnosed with cholestasis, at different points on the continuum from progressive familial intrahepatic cholestasis to benign recurrent intrahepatic cholestasis, in whom no disease mutations in known cholestasis genes had been identified. Candidate genes were then assessed in a larger patient sample, by targeted next-generation sequencing (NGS). Disease features at presentation and follow-up were collected from available medical records.

RESULTS

By WES, we identified 3 patients with homozygous mutations in USP53. Screening of USP53 in a larger set of patients identified 4 additional patients with homozygous mutations in USP53. Six of the 7 patients had deletion mutations, and 1 had a missense mutation; 3 of the patients were siblings, all bearing a deletion that also disrupted neighboring MYOZ2. Age of onset ranged from early infancy to adolescence. Cholestasis tended to be biochemically mild and intermittent, and responsive to medication. Liver fibrosis was, however, present in all 4 patients who were biopsied, and splenomegaly was apparent in 5 of 7 at last ultrasound.

CONCLUSIONS

Two groups recently identified patients with liver disease and mutation in USP53. We have now identified biallelic mutation in USP53 in 7 further patients with cholestasis, from 5 families. Most individuals had evidence of chronic liver disease, and long-term follow-up is recommended.

Neonatal-onset Progressive Familial Intrahepatic Cholestasis (PFIC): first molecular study in Tunisian patients

Progressive familial intrahepatic is a heterogeneous group of rare autosomal recessive liver disorders. Neonatal onset is characteristic of the PFIC 1 and PFIC 2, which result from mutations in genes respectivelyATP8B1 and ABCB11. Four Tunisian patients, three of them with PFIC 2 and one with PFIC1, were described. They all had typical clinical and biological features. However, they all had newly reported mutations. The same mutation was found in the patients with PFIC2, which could facilitate the diagnosis in Tunisian patients suspected in the future. The patient diagnosed with PFIC1 had also a newly described mutation, with a probable phenotypic particularity that is congenital hypothyroidism. Advances are being made to establish a molecular diagnosis in neonatal onset cholestasis. Indeed, next generation sequencing gene panels (NGSGP) potentially decrease the need for invasive procedures in these patients, enable early initiation of treatment and adequate genetic counseling.

Assessment of Adenosine Triphosphatase Phospholipid Transporting 8B1 (ATP8B1) Function in Patients With Cholestasis With ATP8B1 Deficiency by Using Peripheral Blood Monocyte-Derived Macrophages

Adenosine triphosphatase phospholipid transporting 8B1 (ATP8B1) deficiency, an ultrarare autosomal recessive liver disease, includes severe and mild clinical forms, referred to as progressive familial intrahepatic cholestasis type 1 (PFIC1) and benign recurrent intrahepatic cholestasis type 1 (BRIC1), respectively. There is currently no practical method for determining PFIC1 or BRIC1 at an early disease course phase. Herein, we assessed the feasibility of developing a diagnostic method for PFIC1 and BRIC1. A nationwide Japanese survey conducted since 2015 identified 25 patients with cholestasis with ATP8B1 mutations, 15 of whom agreed to participate in the study. Patients were divided for analysis into PFIC1 (n = 10) or BRIC1 (n = 5) based on their disease course. An in vitro mutagenesis assay to evaluate pathogenicity of ATP8B1 mutations suggested that residual ATP8B1 function in the patients could be used to identify clinical course. To assess their ATP8B1 function more simply, human peripheral blood monocyte-derived macrophages (HMDMs) were prepared from each patient and elicited into a subset of alternatively activated macrophages (M2c) by interleukin-10 (IL-10). This was based on our previous finding that ATP8B1 contributes to polarization of HMDMs into M2c. Flow cytometric analysis showed that expression of M2c-related surface markers cluster of differentiation (CD)14 and CD163 were 2.3-fold and 2.1-fold lower (95% confidence interval, 2.0-2.5 for CD14 and 1.7-2.4 for CD163), respectively, in patients with IL-10-treated HMDMs from PFIC1 compared with BRIC1. Conclusion: CD14 and CD163 expression levels in IL-10-treated HMDMs may facilitate diagnosis of PFIC1 or BRIC1 in patients with ATP8B1 deficiency.

Gene Therapy for Progressive Familial Intrahepatic Cholestasis: Current Progress and Future Prospects

Progressive Familial Intrahepatic Cholestasis (PFIC) are inherited severe liver disorders presenting early in life, with high serum bile salt and bilirubin levels. Six types have been reported, two of these are caused by deficiency of an ABC transporter; ABCB11 (bile salt export pump) in type 2; ABCB4 (phosphatidylcholine floppase) in type 3. In addition, ABCB11 function is affected in 3 other types of PFIC. A lack of effective treatment makes a liver transplantation necessary in most patients. In view of long-term adverse effects, for instance due to life-long immune suppression needed to prevent organ rejection, gene therapy could be a preferable approach, as supported by proof of concept in animal models for PFIC3. This review discusses the feasibility of gene therapy as an alternative for liver transplantation for all forms of PFIC based on their pathological mechanism. Conclusion: Using presently available gene therapy vectors, major hurdles need to be overcome to make gene therapy for all types of PFIC a reality.

Progressive Familial Intrahepatic Cholestasis Type 1 Associated with Cherry-Red Spots in an Infant: A First Case Report

Progressive familial intrahepatic cholestasis type 1 (PFIC1) associated with a cherry-red spot, to our knowledge, has never been reported in the literature. We report the case of a 10‑month‑old girl with prolonged cholestasis. A diagnosis of PFIC1 was made by whole‑exome sequencing. Fundus examination showed a cherry-red spot. Our case provides a new insight toward the first case of ocular manifestation of PFIC1. Further studies are required to elucidate FIC1 gene expression in the macula.

Longitudinal Outcomes in Young Patients with Alpha-1-Antitrypsin Deficiency with Native Liver Reveal that Neonatal Cholestasis is a Poor Predictor of Future Portal Hypertension

OBJECTIVES

To identify predictors of portal hypertension, liver transplantation, and death in North American youth with alpha-1-antitrypsin (AAT) deficiency, and compare with patients with AAT deficiency elsewhere.

STUDY DESIGN

The Childhood Liver Disease Research Network Longitudinal Observational Study of Genetic Causes of Intrahepatic Cholestasis is a prospective, cohort study of pediatric cholestatic liver diseases, including AAT deficiency, enrolling PIZZ and PISZ subjects 0-25 years of age seen since November 2007 at 17 tertiary care centers in the US and Canada. Data from standard-of-care baseline and annual follow-up visits were recorded from medical records, history, physical examination, and laboratory studies. Participants with portal hypertension were identified based on data collected.

RESULTS

We enrolled 350 participants (60% male) with a native liver; 278 (79%) entered the cohort without portal hypertension and 18 developed portal hypertension during follow-up. Thirty participants required liver transplantation; 2 patients died during 1077 person-years of follow-up. There was no difference in participants with or without preceding neonatal cholestasis progressing to transplantation or death during the study (12% vs 7%; P = .09), or in experiencing portal hypertension (28% vs 21%; P = .16); the hazard ratio for neonatal cholestasis leading to portal hypertension was P = .04. Development of portal hypertension was associated with a reduced height Z-score.

CONCLUSIONS

Portal hypertension in youth with AAT deficiency impacts growth measures. Progression to liver transplantation is slow and death is rare, but the risk of complications and severe liver disease progression persists throughout childhood. A history of neonatal cholestasis is a weak predictor of severe disease.

ABCB11 deficiency presenting as transient neonatal cholestasis: Correlation with genotypes and BSEP expression

BACKGROUND & AIMS

ABCB11 deficiency presenting in infancy is believed generally to manifest as persistent/progressive cholestasis. We describe a group of patients with biallelic ABCB11 variants whose disorder manifested as transient neonatal cholestasis (TNC).

METHODS

Neonatal intrahepatic cholestasis in 68 children (31 males) with biallelic predictedly pathogenic variants (PPV) in ABCB11 was classified as transient (TNC group, n = 23, 11 males), intermittent (benign recurrent intrahepatic cholestasis [BRIC] group, n = 3, 1 male) or persistent/ progressive (progressive familial intrahepatic cholestasis [PFIC] group, n = 42, 19 males). Clinical, genetic and bile salt export pump (BSEP) expression information was correlated with outcomes.

RESULTS

The median onset age of jaundice was 3 days (birth to 2 months) for the TNC group and 10.5 days (birth to 3 months) for the PFIC group (P = .034). The median length of follow-up of TNC patients was 44 months (12 months-168 months). At presentation, hepatobiliary-injury biomarker values were similar between the groups (P > .05). TNC patients (17/23) more often than PFIC patients (20/42, P = .041) harboured biallelic non-null variants (predicted not to terminate translation prematurely). TNC patient livers (7/7) more often than PFIC patient livers (5/16, P = .005) expressed immunohistochemically detectable BSEP. Kaplan-Meier analysis showed better prognosis for patients with BSEP expression (P = .009). Too few BRIC patients were available for statistical study.

CONCLUSIONS

Neonatal cholestasis associated with biallelic PPV in ABCB11 can resolve temporarily or persistently in one third of cases. Resolution is more likely in patients with biallelic non-null PPV or with liver BSEP expression.

New paradigms of USP53 disease: normal GGT cholestasis, BRIC, cholangiopathy, and responsiveness to rifampicin

Biallelic variants in the USP53 gene have recently been reported to segregate with normal gamma glutamyltransferase (GGT) cholestasis. Using whole-exome sequencing (WES), we detected two USP53 homozygous variants (c.951delT; p. Phe317fs and c.1744C>T; p. Arg582*) in five additional cases, including an unpublished cousin of a previously described family with intractable itching and normal GGT cholestasis. Three patients, a child and two adults, presented with recurrent episodes of normal GGT cholestasis, consistent with a diagnosis of benign recurrent intrahepatic cholestasis (BRIC). Cholangiopathic changes, possibly autoimmune in origin, were recognized in some patients. Additional phenotypic details in one patient included an enlarged left kidney, and speech/developmental delay. Notably, two patients exhibited a complete response to rifampicin, and one responded to ursodeoxycholic acid (UDCA). Two adult patients were suspected to have autoimmune liver disease and treated with steroids. This report describes new cases of USP53 disease presenting with normal GGT cholestasis or BRIC in three children and two adults. We also describe the novel finding of a dramatic response to rifampicin. The association of cholangiopathy with normal GGT cholestasis provides a diagnostic challenge and remains poorly understood.

Potential of ileal bile acid transporter inhibition as a therapeutic target in Alagille syndrome and progressive familial intrahepatic cholestasis

Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC) are rare, inherited cholestatic liver disorders that manifest in infants and children and are associated with impaired bile flow (ie cholestasis), pruritus and potentially fatal liver disease. There are no effective or approved pharmacologic treatments for these diseases (standard medical treatments are supportive only), and new, noninvasive options would be valuable. Typically, bile acids undergo biliary secretion and intestinal reabsorption (ie enterohepatic circulation). However, in these diseases, disrupted secretion of bile acids leads to their accumulation in the liver, which is thought to underlie pruritus and liver-damaging inflammation. One approach to reducing pathologic bile acid accumulation in the body is surgical biliary diversion, which interrupts the enterohepatic circulation (eg by diverting bile acids to an external stoma). These procedures can normalize serum bile acids, reduce pruritus and liver injury and improve quality of life. A novel, nonsurgical approach to interrupting the enterohepatic circulation is inhibition of the ileal bile acid transporter (IBAT), a key molecule in the enterohepatic circulation that reabsorbs bile acids from the intestine. IBAT inhibition has been shown to reduce serum bile acids and pruritus in trials of paediatric cholestatic liver diseases. This review explores the rationale of inhibition of the IBAT as a therapeutic target, describes IBAT inhibitors in development and summarizes the current data on interrupting the enterohepatic circulation as treatment for cholestatic liver diseases including ALGS and PFIC.

Ileal exclusion for pruritus treatment in children with progressive familial intrahepatic cholestasis and other cholestatic diseases

BACKGROUND

Pruritus is a major health-related quality-of-life burden in progressive familial intrahepatic cholestasis (PFIC) and other childhood cholestatic liver diseases. Several nontransplant surgical techniques were developed in an attempt to ameliorate symptoms and slow disease progression. Very few case-series have been published on a particular intervention, ileal exclusion (IE), which has been considered to be inferior to the other approaches.

METHODS

We conducted a single-center retrospective chart-review case-series of patients submitted to IE as the first-line surgical treatment at our institution from 1995 to 2018. The primary goal was pruritus relief, followed by survival with the native liver and improvement in biochemical parameters.

RESULTS

Eleven patients were submitted to IE, with a mean follow-up of 60 months. Complete resolution or significant reduction of pruritus was obtained in 72.7% (n = 8) of patients. One patient (9.1%) had a major postoperative complication that required surgery. No other morbidities were reported. Two cases progressed to end-stage liver disease (ESLD) within the short-term and one year after surgery.

CONCLUSIONS

This case series study shows that IE provided excellent results in pruritus control and permitted survival with the native liver. We believe IE is a safe procedure, with few associated morbidities, and should be considered more often as primary surgical treatment for PFIC and other cholestasis.

LEVEL OF EVIDENCE

IV.

Genotype correlates with the natural history of severe bile salt export pump deficiency

BACKGROUND & AIMS

Mutations in ABCB11 can cause deficiency of the bile salt export pump (BSEP), leading to cholestasis and end-stage liver disease. Owing to the rarity of the disease, the associations between genotype and natural history, or outcomes following surgical biliary diversion (SBD), remain elusive. We aimed to determine these associations by assembling the largest genetically defined cohort of patients with severe BSEP deficiency to date.

METHODS

This multicentre, retrospective cohort study included 264 patients with homozygous or compound heterozygous pathological ABCB11 mutations. Patients were categorized according to genotypic severity (BSEP1, BSEP2, BSEP3). The predicted residual BSEP transport function decreased with each category.

RESULTS

Genotype severity was strongly associated with native liver survival (NLS, BSEP1 median 20.4 years; BSEP2, 7.0 years; BSEP3, 3.5 years; p <0.001). At 15 years of age, the proportion of patients with hepatocellular carcinoma was 4% in BSEP1, 7% in BSEP2 and 34% in BSEP3 (p = 0.001). SBD was associated with significantly increased NLS (hazard ratio 0.50; 95% CI 0.27-0.94: p = 0.03) in BSEP1 and BSEP2. A serum bile acid concentration below 102 μmol/L or a decrease of at least 75%, each shortly after SBD, reliably predicted NLS of ≥15 years following SBD (each p <0.001).

CONCLUSIONS

The genotype of severe BSEP deficiency strongly predicts long-term NLS, the risk of developing hepatocellular carcinoma, and the chance that SBD will increase NLS. Serum bile acid parameters shortly after SBD can predict long-term NLS.

LAY SUMMARY

This study presents data from the largest genetically defined cohort of patients with severe bile salt export pump deficiency to date. The genotype of patients with severe bile salt export pump deficiency is associated with clinical outcomes and the success of therapeutic interventions. Therefore, genotypic data should be used to guide personalized clinical care throughout childhood and adulthood in patients with this disease.

Proposal of a liver histology-based scoring system for bile salt export pump deficiency

AIM

Bile salt export pump (BSEP) deficiency manifests a form of progressive intrahepatic cholestasis. This study aimed to establish a scoring system of liver histology for the uncommon genetic condition.

METHODS

After a roundtable discussion and histology review, a scoring system for BSEP deficiency was established. Eleven tissue samples were independently evaluated by three pathologists based on the proposed standard for an interobserver agreement analysis. In four cases with serial tissue samples available, correlation between changes in histology scores and clinical outcome was examined.

RESULTS

Of 14 initially listed histopathological findings, 12 were selected for scoring and grouped into the following four categories: cholestasis, parenchymal changes, portal tract changes and fibrosis. Each category consisted of two to four microscopic findings that were further divided into three to six scores; therefore, each category had a maximum score of 8-11. Interobserver agreement was highest for pericellular fibrosis (κ = 0.849) and lowest for hepatocellular cholestasis (κ = 0.241) with the mean and median κ values of the 12 parameters being 0.561 and 0.602, respectively. For two patients whose clinical features worsened, score changes between two time points were interpreted as deteriorated. In two patients, who showed a good clinical response to preprandial treatment with sodium 4-phenylbutyrate, histological changes were evaluated as improved or unchanged.

CONCLUSIONS

The proposed histology-based scoring system for BSEP deficiency with moderate interobserver agreement may be useful not only for monitoring microscopic changes in clinical practice but also for a surrogate endpoint in clinical trials.

Phenotype-Genotype Correlation of North Indian Progressive Familial Intrahepatic Cholestasis type2 Children Shows p.Val444Ala and p.Asn591Ser Variants and Retained BSEP Expression

Backgrounds and Aims: Progressive familial intrahepatic cholestasis type 2 (PFIC2) is caused by a defect or deficiency of bile salt export protein (BSEP) due to mutation in the ABCB11 gene. We intend to evaluate the phenotype-genotype correlation in 10 diagnosed cases of PFIC2 in a single tertiary care center in North India. Methods: The clinical, biochemical, histopathological, immunohistochemical, ultrastructural and genetic data of the 10 diagnosed cases of PFIC2 were recorded. Results: Icterus, pruritus and bleeding manifestations were the commonest clinical symptoms. Giant cell transformation was seen in 50% of the patients. Two predominant genetic variants were ABCB11 missense p.Val444Ala (c. 1331 T > C) and ABCB11 missense p.Asn591Ser (c. 1772 A > G) in their homozygous or compound heterozygous states and were associated with retained BSEP immunopositivity and reduced but retained BSEP immunopositivity respectively. Conclusion: Retention of BSEP is common in North Indian children of PFIC2 with no phenotype-genotype correlation.

Co-existence of ABCB11 and DCDC2 disease: Infantile cholestasis requires both next-generation sequencing and clinical-histopathologic correlation

A boy exhibiting conjugated hyperbilirubinemia from birth, with elevated serum gamma-glutamyl transpeptidase activity (GGT), developed liver failure unusually early (7mo); GGT concomitantly normalized. ABCB4 disease was suspected, but no ABCB4 lesion was found. The boy was instead homozygous for ABCB11 variant c.1213 T>C (p.(Cys405Arg)), which is predicted to affect protein function. Both ABCB4 and ABCB11 were normally expressed in the explanted liver, with intralobular cholestasis; however, large-duct sclerosing cholangiopathy and ductal-plate malformation also were present. The primary-cilium constituent doublecortin domain containing 2 (DCDC2) was not expressed. Co-existence of ABCB11 disease and DCDC2 disease was proposed. Further testing identified homozygosity for the canonical-receptor splice-site variant c.294-2A>G (p.?) in DCDC2. Our report emphasizes the need to integrate clinical, histological, and genetic data in patients with neonatal cholestasis.

Beyond an Obvious Cause of Cholestasis in a Toddler: Compound Heterozygosity for ABCB11 Mutations

A 27-month-old girl presented with a short history of jaundice initially attributed to drug-induced liver injury. During the preceding 20 days, she had received a 10-day course of cefprozil and 2 doses of a homeopathic preparation of cantharidin for cystitis. Severe conjugated hyperbilirubinemia was present with normal γ-glutamyl transpeptidase activity. Liver biopsy revealed marked canalicular and hepatocellular cholestasis, with moderate hepatocellular disarray, as well as evidence of chronicity, including moderate portal-tract and perisinusoidal fibrosis. Immunohistochemical studies revealed that bile salt export pump expression was preserved, whereas canalicular γ-glutamyl transpeptidase expression was largely absent. An inherited cholestatic disorder was suspected. The entire coding region of ABCB11, encoding bile salt export pump, was analyzed. The patient was found to be a compound heterozygote for the missense mutation c.3148C>T (p.Arg1050Cys) associated with benign recurrent intrahepatic cholestasis type 2 in the homozygous state and for the nonsense mutation c.3904G>T (p.Glu1302Ter) associated with progressive familial intrahepatic cholestasis type 2. Despite initial improvement with ursodeoxycholic acid, over the course of 5 years the patient developed cirrhosis that required liver transplant. Our report emphasizes the need for molecular studies even in patients with putatively "explained" cholestasis to reveal the entire spectrum of inherited cholestatic disorders.

Long-term outcomes after cholecystocolostomy for progressive familial intrahepatic cholestasis

AIM

To evaluate the long-term efficacy of cholecystocolostomy surgery for progressive familial intrahepatic cholestasis (PFIC).

METHODS

From August 2003 to November 2014, 34 clinically diagnosed children, including 11 with familial intrahepatic cholestasis-1 (FIC1), 13 with bile salt export pump (BSEP) disease, five with low γ-glutamyl transpeptidase (GGT) disease (levels <100 U/L), and five with multidrug resistance class III (MDR3) disease with high GGT (>100 U/L), were identified in our center. Data were collected retrospectively from individuals who collectively had 36 surgical operations and two orthotopic liver transplantations (OLT).

RESULTS

Serum total bilirubin (0 = 163.54 ± 106.02, 36 months = 23.38 ± 17.66 μmol/L) and bile acid (0 = 325.83 ± 153.09, 36 months = 48.36 ± 79.71 μmol/L) decreased after cholecystocolostomy in PFIC patients (P < 0.001). All patients experienced decreased severity of pruritus (88.2% vs. 16.1%, P < 0.001) and a greater freedom from growth retardation after cholecystocolostomy (-3.35 vs. -1.03, P < 0.001). Defecation frequency increased in PFIC patients after cholecystocolostomy (P = 0.002). Four patients (three with FIC1 and one with BSEP) experienced recurrence of cholestasis and two underwent reoperation. Two BSEP patients underwent OLT. One patient with BSEP and one patient with MDR3 died due to severe diarrhea and dehydration; one BSEP patient died of intractable constipation.

CONCLUSIONS

This is the first long-term, large-scale analysis of cholecystocolostomy approaches for PFIC. Approaches single and well tolerated, and generally result in improvement of pruritus and cholestasis.