Intrahepatic cholestasis: summary of an American Association for the Study of Liver Diseases single-topic conference

Pediatric Cholestatic Diseases: Common and Unique Pathogenic Mechanisms

Cholestasis is the predominate feature of many pediatric hepatobiliary diseases. The physiologic flow of bile requires multiple complex processes working in concert. Bile acid (BA) synthesis and excretion, the formation and flow of bile, and the enterohepatic reuptake of BAs all function to maintain the circulation of BAs, a key molecule in lipid digestion, metabolic and cellular signaling, and, as discussed in the review, a crucial mediator in the pathogenesis of cholestasis. Disruption of one or several of these steps can result in the accumulation of toxic BAs in bile ducts and hepatocytes leading to inflammation, fibrosis, and, over time, biliary and hepatic cirrhosis. Biliary atresia, progressive familial intrahepatic cholestasis, primary sclerosing cholangitis, and Alagille syndrome are four of the most common pediatric cholestatic conditions. Through understanding the commonalities and differences in these diseases, the important cellular mechanistic underpinnings of cholestasis can be greater appreciated.

Clinical Characterization of Alagille Syndrome in Patients with Cholestatic Liver Disease

Alagille syndrome (ALGS) is a multisystem condition characterized by cholestasis and bile duct paucity on liver biopsy and variable involvement of the heart, skeleton, eyes, kidneys, and face and caused by pathogenic variants in the JAG1 or NOTCH2 gene. The variable expressivity of the clinical phenotype and the lack of genotype-phenotype correlations lead to significant diagnostic difficulties. Here we present an analysis of 18 patients with cholestasis who were diagnosed with ALGS. We used an NGS panel targeting coding exons of 52 genes, including the JAG1 and NOTCH2 genes. Sanger sequencing was used to verify the mutation in the affected individuals and family members. The specific facial phenotype was seen in 16/18 (88.9%). Heart defects were seen in 8/18 (44.4%) patients (pulmonary stenosis in 7/8). Butterfly vertebrae were seen in 5/14 (35.7%) patients. Renal involvement was detected in 2/18 (11.1%) cases-one patient had renal cysts, and one had obstructive hydronephrosis. An ophthalmology examination was performed on 12 children, and only one had posterior embryotoxon (8.3%). A percutaneous liver biopsy was performed in nine cases. Bile duct paucity was detected in six/nine cases (66.7%). Two patients required liver transplantation because of cirrhosis. We identified nine novel variants in the JAG1 gene-eight frameshift variants (c.1619_1622dupGCTA (p.Tyr541X), c.1160delG (p.Gly387fs), c.964dupT (p.C322fs), c.120delG (p.L40fs), c.1984dupG (p.Ala662Glyfs), c.3168_3169delAG (p.R1056Sfs*51), c.2688delG (p.896CysfsTer49), c.164dupG (p.Cys55fs)) and one missense variant, c.2806T > G (p.Cys936Gly). None of the patients presented with NOTCH2 variants. In accordance with the classical criteria, only six patients could meet the diagnostic criteria in our cohort without genetic analysis. Genetic testing is important in the diagnosis of ALGS and can help differentiate it from other types of cholestasis.

Combining Panel-Based Next-Generation Sequencing and Exome Sequencing for Genetic Liver Diseases

OBJECTIVES

To determine how advanced genetic analysis methods may help in clinical diagnosis.

STUDY DESIGN

We report a combined genetic diagnosis approach for patients with clinical suspicion of genetic liver diseases in a tertiary referral center, using tools either tier 1: Sanger sequencing on SLC2SA13, ATP8B1, ABCB11, ABCB4, and JAG1 genes, tier 2: panel-based next generation sequencing (NGS), or tier 3: whole-exome sequencing (WES) analysis.

RESULTS

In a total of 374 patients undergoing genetic analysis, 175 patients received tier 1 Sanger sequencing based on phenotypic suspicion, and pathogenic variants were identified in 38 patients (21.7%). Tier 2 included 216 patients (39 of tier 1-negative patients) who received panel-based NGS, and pathogenic variants were identified in 60 (27.8%). In tier 3, 41 patients received WES analysis, and 20 (48.8%) obtained genetic diagnosis. Pathogenic variants were detected in 6 of 19 (31.6%) who tested negative in tier 2, and a greater detection rate in 14 of 22 (63.6%) patients with deteriorating/multiorgan disease receiving one-step WES (P = .041). The overall disease spectrum is comprised of 35 genetic defects; 90% of genes belong to the functional categories of small molecule metabolism, ciliopathy, bile duct development, and membrane transport. Only 13 (37%) genetic diseases were detected in more than 2 families. A hypothetical approach using a small panel-based NGS can serve as the first tier with diagnostic yield of 27.8% (98/352).

CONCLUSIONS

NGS based genetic test using a combined panel-WES approach is efficient for the diagnosis of the highly diverse genetic liver diseases.

Gentamicin alleviates cholestatic liver injury by decreasing gut microbiota-associated bile salt hydrolase activity in rats

Intrahepatic cholestasis lacks effective therapeutic drugs. The gut microbiota-associated bile salt hydrolases (BSH) may be a potential therapeutic target. In this study, oral administration of gentamicin (GEN) decreased the serum and hepatic levels of total bile acid in 17α-ethynylestradiol (EE)-induced cholestatic male rats, significantly improved the serum levels of hepatic biomarkers and reversed the histopathological changes in the liver. In healthy male rats, the serum and hepatic levels of total bile acid were also decreased by GEN, the ratio of primary to secondary bile acids, and conjugated to unconjugated bile acids was significantly increased, and the urinary excretion of total bile acid was elevated. 16S rDNA sequencing of the ileal contents revealed that GEN treatment substantially reduced the abundance of Lactobacillus and Bacteroides both of which expressed BSH. Consistently, BSH activity analysis by the generation of d5-chenodeoxycholic acid from d5-taurochenodeoxycholic acid in situ showed BSH was significantly inhibited in the ileal contents of rats treated with GEN. This finding led to an increased proportion of hydrophilic conjugated bile acids and facilitated the urinary excretion of total bile acids, thereby decreasing serum and hepatic total bile acids and reversing liver injury related to cholestasis. Our results provide important evidence that BSH can be a potential drug target for treating cholestasis.

UNC45A-related osteo-oto-hepato-enteric syndrome in a Chinese neonate

Unexplained diarrhea and cholestasis are common clinical phenotypes in newborns, indicating there is only a little common genetic basis for these conditions. However, it has been reported that defects in the UNC45A gene can lead to osteo-oto-hepato-enteric syndrome. However, to date, only 10 patients with this syndrome have been reported in 2 studies; therefore, there is still a lack of analysis regarding the correlation between disease phenotype and genotype. Trio-whole exome sequencing was conducted using DNA samples from a newborn with congenital diarrhea and cholestasis from a Chinese Han family. The UNC45A variants were verified using Sanger sequencing. In addition, we applied a crystal structure model to analyze the potential hazards associated with the variants. The plasmids were constructed in vitro and transfected into human 293T cells for Western blot (WB) analysis. After the mutant protein was fused with the Green Fluorescent Protein label, intracellular localization was observed using laser confocal microscopy. The gene detection results showed that the UNC45A gene of the newborn examined in the present study harbored the compound heterozygous variants p.Arg819Ter, and p.Leu237Pro; this was confirmed via Sanger sequencing. Analysis of the Leu237Pro crystal structure model suggested that this variant may decrease local structural stability and affect protein function. The Western blot and laser confocal microscopy observation results suggested that the Leu237Pro mutation leads to reduced protein expression, while the Arg819Ter mutation completely inhibits the expression of the protein. The compound heterozygous variants of UNC45A (p.Arg819Ter and p.Leu237Pro) may be pathogenic factors of congenital diarrhea and cholestasis in this neonatal patient. Therefore, UNC45A deficiency should be considered when intractable diarrhea and cholestasis occur in newborns.

Real-life Progression of the Use of a Genetic Panel in to Diagnose Neonatal Cholestasis

The study aimed to construct an advanced gene panel to ascertain the genetic etiology of patients with neonatal/infantile intrahepatic cholestasis (NIIC), and test patients with NIIC in a clinical setting.

Etiology of neonatal cholestasis after emerging molecular diagnostics

BACKGROUND

In the pediatric group, most cholestatic patients had disease onset at 0-3 months of age, and more and more are found to have specific genetic defects after failing to obtain a definite diagnosis by routine evaluation. To investigate the etiological diagnosis for the newborns with cholestasis during the neonatal period after emerging molecular tests comprehensively.

METHODS

We conducted a retrospective study to evaluate clinical characteristics, etiologies and outcomes in infants with neonatal cholestasis after emerging molecular diagnostics from January 1st to December 31st, 2019 in Children's Hospital of Fudan University.

RESULTS

There were 160 cases of neonatal cholestasis with mean gestational age (GA) 32.6±4.8 weeks and birth weight (BW) 1,880±991 g, composing 3.4% of total neonatal admissions in 2019. Overall 97.5% (n=156) patients had a definite diagnosis, including 9 obtaining a genetic diagnosis after adding molecular test in routine evaluation, which made the diagnosis rate for cholestasis increased by 5.6%. The most common etiology of cholestasis in the neonatal period was parenteral nutrition-associated cholestasis (PNAC) 48.8% (n=78), followed by cardiovascular and circulatory disorders 18.1%, biliary anatomic obstruction 12.5%, infection 8.7% and genetic disorders 5.6%. PNAC and biliary anatomic obstruction were the most common etiology of cholestasis for preterm and term infants respectively. The mortality rate is 2.5% (n=4) and 91.9% (n=147) patients totally recovery or improve in follow-up.

CONCLUSIONS

The causes of cholestasis in neonates are complicated, molecular diagnostics can improve the etiological diagnosis for newborns with cholestasis. But still, quite amount of causes are remediable and transient during the neonatal period, gene test may help to rule out genetic causes and enhance confidence in judging prognosis.

A Two-Tiered In Vitro Approach to De-Risk Drug Candidates for Potential Bile Salt Export Pump Inhibition Liabilities in Drug Discovery

Hepatocellular accumulation of bile salts by inhibition of bile salt export pump (BSEP/ABCB11) may result in cholestasis and is one proposed mechanism of drug-induced liver injury (DILI). To understand the relationship between BSEP inhibition and DILI, we evaluated 64 DILI-positive and 57 DILI-negative compounds in BSEP, multidrug resistance protein (MRP) 2, MRP3, and MRP4 vesicular inhibition assays. An empirical cutoff (5 μM) for BSEP inhibition was established based on a relationship between BSEP IC50 values and the calculated maximal unbound concentration at the inlet of the human liver (fu*Iin,max, assay specificity = 98%). Including inhibition of MRP2-4 did not increase DILI predictivity. To further understand the potential to inhibit bile salt transport, a selected subset of 30 compounds were tested for inhibition of taurocholate (TCA) transport in a long-term human hepatocyte micropatterned co-culture (MPCC) system. The resulting IC50 for TCA in vitro biliary clearance and biliary excretion index (BEI) in MPCCs were compared with the compound's fu*Iin,max to assess potential risk for bile salt transport perturbation. The data show high specificity (89%). Nine out of 15 compounds showed an IC50 value in the BSEP vesicular assay of <5μM, but the BEI IC50 was more than 10-fold the fu*Iin,max, suggesting that inhibition of BSEP in vivo is unlikely. The data indicate that although BSEP inhibition measured in membrane vesicles correlates with DILI risk, that measurement of this assay activity is insufficient. A two-tiered strategy incorporating MPCCs is presented to reduce BSEP inhibition potential and improve DILI risk. SIGNIFICANCE STATEMENT: This work describes a two-tiered in vitro approach to de-risk compounds for potential bile salt export pump inhibition liabilities in drug discovery utilizing membrane vesicles and a long-term human hepatocyte micropatterned co-culture system. Cutoffs to maximize specificity were established based on in vitro data from a set of 121 DILI-positive and -negative compounds and associated calculated maximal unbound concentration at the inlet of the human liver based on the highest clinical dose.

Recent developments in diagnostics and treatment of neonatal cholestasis

Neonatal cholestasis is characterized by conjugated hyperbilirubinemia in the newborn and young infant and is a sign common to over 100 hepatobiliary and/or metabolic disorders. A timely evaluation for its etiology is critical in order to quickly identify treatable causes such as biliary atresia, many of which benefit from early therapy. An expanding group of molecularly defined disorders involving bile formation, canalicular transporters, tight junction proteins and inborn errors of metabolism are being continuously discovered because of advances in genetic testing and bioinformatics. The advent of next generation sequencing has transformed our ability to test for multiple genes and whole exome or whole genome sequencing within days to weeks, enabling rapid and affordable molecular diagnosis for disorders that cannot be directly diagnosed from standard blood tests or liver biopsy. Thus, our diagnostic algorithms for neonatal cholestasis are undergoing transformation, moving genetic sequencing to earlier in the evaluation pathway once biliary atresia, "red flag" disorders and treatable disorders are excluded. Current therapies focus on promoting bile flow, reducing pruritus, ensuring optimal nutrition, and monitoring for complications, without addressing the underlying cause of cholestasis in most instances. Our improved understanding of bile formation and the enterohepatic circulation of bile acids has led to emerging therapies for cholestasis which require appropriate pediatric clinical trials. Despite these advances, the cause and optimal therapy for biliary atresia remain elusive. The goals of this review are to outline the etiologies, diagnostic pathways and current and emerging management strategies for neonatal cholestasis.

Investigation of cholestasis-related changes in characteristics of spermatogonial stem cells in testis tissue of male Wistar rats

Paternal metabolic status is an important factor in the health status of offspring. Cholestasis, as a metabolic disorder, significantly disrupts spermatogenesis. Spermatogonial stem cells (SSCs) are considered the dividing germ cells, which maintain spermatogenesis throughout the lifespan. Here, we investigated the in vivo and in vitro effect(s) of cholestasis on SSCs. Cholestasis was induced in rats by bile duct ligation. Four weeks after the cholestasis induction, testicular tissues were analysed using histopathological examinations. The expression of SSC markers, including Plzf and Thy-1, was determined using the immunofluorescent technique. Also, SSCs were isolated from animals, and their proliferation was examined in vitro. The histological examinations revealed that cholestasis caused irregularities in the structure of seminal tubes. Immunostaining showed that the total number of Thy-1- and Plzf-expressing cells was declined in the cholestasis group compared with the control group. In vitro culture of SSCs indicated that the number of SSC colonies and those expressing Plzf were significantly reduced in the culture medium of the cholestasis group. Our results indicated that cholestasis affects the functionality of SSCs and reduces the number and proliferation of them. This finding may be of interest to the effect of metabolic diseases such as cholestasis on spermatogenesis.

Diagnostic Yield of an Algorithm for Neonatal and Infantile Cholestasis Integrating Next-Generation Sequencing

OBJECTIVE

To evaluate the performance of a diagnostic protocol for neonatal/infantile cholestasis in which the main clinical patterns steered the early use of different genetic testing strategies.

STUDY DESIGN

An observational study was conducted between 2012 and 2017 in a tertiary care setting on a prospective cohort of children with cholestasis occurring at ≤1 year of age and persisting ≥6 weeks, to measure the detection rate of underlying monogenic diseases. After the exclusion of biliary atresia, a clinically driven genetic testing was performed, entailing 3 different approaches with different wideness: confirmatory single-gene testing; focused virtual panels; and wide search through trio whole-exome sequencing.

RESULTS

We enrolled 125 children (66 female, median age 2 months); 96 (77%) patients had hypocholic stools and were evaluated rapidly to exclude biliary atresia, which was the final diagnosis in 74 (59%). Overall, 50 patients underwent genetic testing, 6 with single confirmatory gene testing, 38 through panels, and 6 with trio whole-exome sequencing because of complex phenotype. The genetic testing detection rate was 60%: the final diagnosis was Alagille syndrome in 11, progressive familial intrahepatic cholestasis type 2 in 6, alpha-1-antitrypsin deficiency in 3, and progressive familial intrahepatic cholestasis type 3 in 2; a further 7 genetic conditions were identified in 1 child each. Overall, only 18 of 125 (14%) remained with an indeterminate etiology.

CONCLUSIONS

This protocol combining clinical and genetic assessment proved to be an effective diagnostic tool for neonatal/infantile cholestasis, identifying inherited disorders with a high detection rate. It also could allow a noninvasive diagnosis in children presenting with colored stools.

Neonatal cholestasis: emerging molecular diagnostics and potential novel therapeutics

Neonatal cholestasis is a group of rare disorders of impaired bile flow characterized by conjugated hyperbilirubinaemia in the newborn and young infant. Neonatal cholestasis is never physiological but rather is a sign of hepatobiliary and/or metabolic disorders, some of which might be fatal if not identified and treated rapidly. A step-wise timely evaluation is essential to quickly identify those causes amenable to treatment and to offer accurate prognosis. The aetiology of neonatal cholestasis now includes an expanding group of molecularly defined entities with overlapping clinical presentations. In the past two decades, our understanding of the molecular basis of many of these cholestatic diseases has improved markedly. Simultaneous next-generation sequencing for multiple genes and whole-exome or whole-genome sequencing now enable rapid and affordable molecular diagnosis for many of these disorders that cannot be directly diagnosed from standard blood tests or liver biopsy. Unfortunately, despite these advances, the aetiology and optimal therapeutic approach of the most common of these disorders, biliary atresia, remain unclear. The goals of this Review are to discuss the aetiologies, algorithms for evaluation and current and emerging therapeutic options for neonatal cholestasis.

The Protective Effects of Ciji-Hua'ai-Baosheng II Formula on Chemotherapy-Treated H22 Hepatocellular Carcinoma Mouse Model by Promoting Tumor Apoptosis

Ciji-Hua'ai-Baosheng II Formula (CHB-II-F) is a traditional Chinese medical formula that has been shown in clinical practice to relieve side effects of chemotherapy and improve quality of life for cancer patients. In order to understand the mechanism of its protective effects on chemotherapy, mice with transplanted H₂₂ hepatocellular carcinoma were employed in this study. Ninety-two mice were injected subcutaneously with H₂₂ HCC cell suspension into the right anterior armpit. After mice were treated with 5-fluorine pyrimidine (5-FU), they were divided into six groups as untreated group, 5-FU group, 5-FU plus Yangzheng Xiaoji Capsule group and three groups of 5-FU plus different concentrations of CHB-II-F. Twenty mice were euthanized after 7 days of treatment in untreated and medium concentration of CHB-II-F groups and all other mice were euthanized after 14 days of treatment. Herbal components/metabolites were analyzed by UPLC-MS. Tumors were evaluated by weight and volume, morphology of light and electron microscope, and cell cycle. Apoptosis were examined by apoptotic proteins expression by western blot. Four major components/metabolites were identified from serum of mice treated with CHB-II-F and they are β-Sitosterol, Salvianolic acid, isobavachalcone, and bakuchiol. Treatment of CHB-II-F significantly increased body weights of mice and decreased tumor volume compared to untreated group. Moreover, CHB-II-F treatment increased tumor cells in G₀-G₁ transition instead of in S phase. Furthermore, CHB-II-F treatment increased the expression of pro-apoptotic proteins and decreased the expression anti-apoptotic protein. Therefore, CHB-II-F could improve mice general condition and reduce tumor cell malignancy. Moreover, CHB-II-F regulates apoptosis of tumor cells, which could contribute its protective effect on chemotherapy.

Constitutive Androstane Receptor Differentially Regulates Bile Acid Homeostasis in Mouse Models of Intrahepatic Cholestasis

Bile acid (BA) homeostasis is tightly regulated by multiple transcription factors, including farnesoid X receptor (FXR) and small heterodimer partner (SHP). We previously reported that loss of the FXR/SHP axis causes severe intrahepatic cholestasis, similar to human progressive familial intrahepatic cholestasis type 5 (PFIC5). In this study, we found that constitutive androstane receptor (CAR) is endogenously activated in Fxr:Shp double knockout (DKO) mice. To test the hypothesis that CAR activation protects DKO mice from further liver damage, we generated Fxr;Shp;Car triple knockout (TKO) mice. In TKO mice, residual adenosine triphosphate (ATP) binding cassette, subfamily B member 11 (ABCB11; alias bile salt export pump [BSEP]) function and fecal BA excretion are completely impaired, resulting in severe hepatic and biliary damage due to excess BA overload. In addition, we discovered that pharmacologic CAR activation has different effects on intrahepatic cholestasis of different etiologies. In DKO mice, CAR agonist 1,4‐bis[2‐(3,5‐dichloropyridyloxy)]benzene (TCPOBOP; here on TC) treatment attenuated cholestatic liver injury, as expected. However, in the PFIC2 model Bsep knockout (BKO) mice, TC treatment exhibited opposite effects that reflect increased BA accumulation and liver injury. These contrasting results may be linked to differential regulation of systemic cholesterol homeostasis in DKO and BKO livers. TC treatment selectively up‐regulated hepatic cholesterol levels in BKO mice, supporting de novo BA synthesis. Conclusion: CAR activation in DKO mice is generally protective against cholestatic liver injury in these mice, which model PFIC5, but not in the PFIC2 model BKO mice. Our results emphasize the importance of the genetic and physiologic background when implementing targeted therapies to treat intrahepatic cholestasis.

Age-dependent glycosylation of the sodium taurocholate cotransporter polypeptide: From fetal to adult human livers

Sodium taurocholate cotransporter polypeptide (NTCP), mainly expressed on the sinusoidal membrane of hepatocytes, is one of the major transporters responsible for liver bile acid (BA) re-uptake. NTCP transports conjugated BA from the blood into hepatocytes and is crucial for correct enterohepatic circulation. Studies have shown that insufficient hepatic clearance of BA correlates with elevated serum BA in infants younger than 1 year of age. In the current study, we investigated human NTCP messenger RNA and protein expression by using reverse-transcription quantitative polymerase chain reaction and immunoblotting in isolated and cryopreserved human hepatocytes from two different age groups, below and above 1 year of age. Here, we show that NTCP messenger RNA expression is not modulated whereas NTCP protein posttranslational glycosylation is modulated in an age-dependent manner. These results were confirmed by quantification analysis of NTCP 55-kDa N-glycosylated bands, which showed significantly less total NTCP protein in donors below 1 year of age compared to donors older than 1 year. NTCP tissue localization was also analyzed by means of immunofluorescence. This revealed that NTCP cellular localization in fetal samples was mainly perinuclear, suggesting that NTCP is not glycosylated, while its postnatal localization on the plasma membrane is age dependent compared to multidrug resistant protein 2, which is apical starting in fetal life. Conclusion: After birth, the NTCP age-dependent maturation process requires approximately 1 year to complete NTCP glycosylation in human hepatocytes. Therefore, NTCP late posttranslational glycosylation appears to be important for correct NTCP membrane localization, which might explain physiologic cholestasis in neonatal life and might play a central role for HBV infection after birth. (Hepatology Communications 2018;2:693-702).

Clinical Features and Genetic Analysis of Pediatric Patients with Alagille Syndrome Presenting Initially with Liver Function Abnormalities

Alagille syndrome (AGS) is a multisystem disorder and caused by mutations in JAG1 or NOTCH2 gene. The diagnosis of AGS is hampered by its highly variable clinical manifestations. We performed a retrospective analysis on 16 children diagnosed as having AGS in recent five years in our hospital. Cholestasis was seen in 15 patients (93.8%), heart disease in 12 (75%), characteristic facies in 7 (43.8%), and butterfly vertebrae in 7 (43.8%). Ophthalmology examination was not performed on all the patients. Further, serum biochemical parameters were compared between AGS and 16 biliary atresia (BA) patients who were confirmed by surgery. Elevated liver enzymes were seen in all the patients. Serum total cholesterol (TC) (P=0.0007), alanine aminotransferase (ALT) (P=0.0056), aspartate aminotransferase (AST) (P=0.0114), gamma-glutamyl transferase (GGT) (P=0.035) and total bile acid (TBA) levels (P=0.042) were significantly elevated in AGS patients compared to those in BA cases. However, there were no significant differences in serum total bilirubin (TB), conjugated bilirubin (CB) and albumin (ALB) between the two groups. We identified 14 different JAG1 gene variations and 1 NOTCH2 gene mutation in 16 Chinese AGS patients. Our study suggested clinical features of AGS are highly variable and not all patients meet the classical diagnostic criteria. It was suggested that hypercholesterolaemia and significantly elevated GGT, TBA and ALT may be helpful to diagnose AGS. Genetic testing is integral in the diagnosis of AGS.

Next generation sequencing in pediatric hepatology and liver transplantation

Next generation sequencing (NGS) has revolutionized the analysis of human genetic variations, offering a highly cost-effective way to diagnose monogenic diseases (MDs). Because nearly half of the children with chronic liver disorders have a genetic cause and approximately 20% of pediatric liver transplantations are performed in children with MDs, NGS offers the opportunity to significantly improve the diagnostic yield in this field. Among the NGS strategies, the use of targeted gene panels has proven useful to rapidly and reliably confirm a clinical suspicion, whereas the whole exome sequencing (WES) with variants filtering has been adopted to assist the diagnostic workup in unclear clinical scenarios. WES is powerful but challenging because it detects a great number of variants of unknown significance that can be misinterpreted and lead to an incorrect diagnosis. In pediatric hepatology, targeted NGS can be very valuable to discriminate neonatal/infantile cholestatic disorders, disclose genetic causes of acute liver failure, and diagnose the subtype of inborn errors of metabolism presenting with a similar phenotype (such as glycogen storage disorders, mitochondrial cytopathies, or nonalcoholic fatty liver disease). The inclusion of NGS in diagnostic processes will lead to a paradigm shift in medicine, changing our approach to the patient as well as our understanding of factors affecting genotype-phenotype match. In this review, we discuss the opportunities and the challenges offered nowadays by NGS, and we propose a novel algorithm for cholestasis of infancy adopted in our center, including targeted NGS as a pivotal tool for the diagnosis of liver-based MDs. Liver Transplantation 24 282-293 2018 AASLD.

The coming of age of a young subspecialty: paediatric hepatology

Paediatric hepatology dates from the 1970s and it is the youngest of the organ-specific subspecialties. As then there have been impressive achievements in the fields of anatomical, metabolic, immunological and neoplastic diseases, and the advent of modern molecular biology has resulted in a marked increase in exact diagnoses. Liver transplants provided enormous stimulus for the discipline. Due to changing morbidity patterns, the discipline faces new challenges, such as environment- and lifestyle-induced liver diseases, but different forms of chronic viral hepatitis are diminishing.

CONCLUSION

High levels of competence require good clinical research, optimal results and a high degree of centralisation.

Glucuronidation: driving factors and their impact on glucuronide disposition

Glucuronidation is a well-recognized phase II metabolic pathway for a variety of chemicals including drugs and endogenous substances. Although it is usually the secondary metabolic pathway for a compound preceded by phase I hydroxylation, glucuronidation alone could serve as the dominant metabolic pathway for many compounds, including some with high aqueous solubility. Glucuronidation involves the metabolism of parent compound by UDP-glucuronosyltransferases (UGTs) into hydrophilic and negatively charged glucuronides that cannot exit the cell without the aid of efflux transporters. Therefore, elimination of parent compound via glucuronidation in a metabolic active cell is controlled by two driving forces: the formation of glucuronides by UGT enzymes and the (polarized) excretion of these glucuronides by efflux transporters located on the cell surfaces in various drug disposition organs. Contrary to the common assumption that the glucuronides reaching the systemic circulation were destined for urinary excretion, recent evidences suggest that hepatocytes are capable of highly efficient biliary clearance of the gut-generated glucuronides. Furthermore, the biliary- and enteric-eliminated glucuronides participate into recycling schemes involving intestinal microbes, which often prolong their local and systemic exposure, albeit at low systemic concentrations. Taken together, these recent research advances indicate that although UGT determines the rate and extent of glucuronide generation, the efflux and uptake transporters determine the distribution of these glucuronides into blood and then to various organs for elimination. Recycling schemes impact the apparent plasma half-life of parent compounds and their glucuronides that reach intestinal lumen, in addition to prolonging their gut and colon exposure.

Decreased dentin tubules density and reduced thickness of peritubular dentin in hyperbilirubinemia-related green teeth

Background

It is stated anecdotally that patients with liver diseases in childhood who develop green teeth have increased risk for rampant caries, which may be secondary to changes in dental structure. The aim of this study was to test the hypothesis that hyperbilirubinemia affects the dentin morphology of green teeth.

Material and Methods

Sixteen primary teeth were prepared and divided into two groups (green teeth, n = 8 and control, n = 8), which were transversely fractured across the cervical third of the dental crowns; dentin was prepared and sputter-coated with gold, and examined under a scanning electron microscope. The mean density and mean diameter of dentin tubules, as well as the thickness of peritubular dentin, were compared.

Results

Hyperbilirubinemia was associated with a decrease in the density of the dentin tubules (p< .01) and the thickness of peritubular dentin of green teeth (p< .01).

Conclusions

There was a correlation between childhood hyperbilirubinemia and changes in the dentin morphology, including a decrease in the density of the dentin tubules and a reduction in the thickness of peritubular dentin in green teeth.

Key words:Hyperbilirubinemia, liver disease, childhood, dentin tubules, human teeth, scanning electron microscopy.

A Predictive 3D Multi-Scale Model of Biliary Fluid Dynamics in the Liver Lobule

Bile, the central metabolic product of the liver, is transported by the bile canaliculi network. The impairment of bile flow in cholestatic liver diseases has urged a demand for insights into its regulation. Here, we developed a predictive 3D multi-scale model that simulates fluid dynamic properties successively from the subcellular to the tissue level. The model integrates the structure of the bile canalicular network in the mouse liver lobule, as determined by high-resolution confocal and serial block-face scanning electron microscopy, with measurements of bile transport by intravital microscopy. The combined experiment-theory approach revealed spatial heterogeneities of biliary geometry and hepatocyte transport activity. Based on this, our model predicts gradients of bile velocity and pressure in the liver lobule. Validation of the model predictions by pharmacological inhibition of Rho kinase demonstrated a requirement of canaliculi contractility for bile flow in vivo. Our model can be applied to functionally characterize liver diseases and quantitatively estimate biliary transport upon drug-induced liver injury.

A Specially Designed Multi-Gene Panel Facilitates Genetic Diagnosis in Children with Intrahepatic Cholestasis: Simultaneous Test of Known Large Insertions/Deletions

BACKGROUND AND AIMS

Large indels are commonly identified in patients but are not detectable by routine Sanger sequencing and panel sequencing. We specially designed a multi-gene panel that could simultaneously test known large indels in addition to ordinary variants, and reported the diagnostic yield in patients with intrahepatic cholestasis.

METHODS

The panel contains 61 genes associated with cholestasis and 25 known recurrent large indels. The amplicon library was sequenced on Ion PGM system. Sequencing data were analyzed using a routine data analysis protocol and an internal program encoded for large indels test simultaneously. The validation phase was performed using 54 patients with known genetic diagnosis, including 5 with large insertions. At implement phase, 141 patients with intrahepatic cholestasis were evaluated.

RESULTS

At validation phase, 99.6% of the variations identified by Sanger sequencing could be detected by panel sequencing. Following the routine protocol, 99.8% of false positives could be filtered and 98.8% of retained variations were true positives. Large insertions in the 5 patients with known genetic diagnosis could be correctly detected using the internal program. At implementation phase, 96.9% of the retained variations, following the routine protocol, were confirmed to be true. Twenty-nine patients received a potential genetic diagnosis when panel sequencing data were analyzed using the routine protocol. Two additional patients, who were found to harbor large insertions in SLC25A13, obtained a potential genetic diagnosis when sequencing data were further analyzed using the internal program. A total of 31 (22.0%) patients obtained a potential genetic diagnosis. Nine different genetic disorders were diagnosed, and citrin deficiency was the commonest.

CONCLUSION

Specially designed multi-gene panel can correctly detect large indels simultaneously. By using it, we assigned a potential genetic diagnosis to 22.0% of patients with intrahepatic cholestasis.

Urinary bile casts in bile cast nephropathy secondary to severe falciparum malaria

BACKGROUND

Severe cholestatic jaundice may complicate with bile cast nephropathy (BCN) causing severe acute kidney injury (AKI). In this study, we investigate BCN in severe falciparum malaria complicated with jaundice and AKI.

METHODS

This prospective study was conducted in a tertiary health care institution with high prevalence of malaria. A cohort of 110 patients with falciparum malaria complicated with cerebral malaria, jaundice and AKI were enrolled. Species diagnosis was made from peripheral blood smear or rapid diagnostic test. Severe malaria was diagnosed from WHO criteria. BCN was diagnosed with the detection of bile casts in urine or in biopsy. The recovery pattern and outcome with and without BCN was assessed.

RESULTS

Out of 110 patients, 20 (18.2%) patients had BCN and 15 (13.6%) patients had hepato-renal syndrome. Patients with BCN had high conjugated bilirubin (26.5 ± 4.1 mg/dL), urea (75.9 ± 10.3 mg/dL) and creatinine (7.2 ± 0.8 mg/dL), longer duration of illness (6.4 ± 1.1 days), higher mortality (25.0%) and prolonged recovery time of hepatic (9.6 ± 2.4 days) and renal dysfunction (15.1 ± 6.5 days) compared with patients without BCN.

CONCLUSIONS

Prolonged duration of illness and increased bilirubin cause BCN among patients with severe falciparum malaria with jaundice and AKI, which is associated with high mortality and morbidity.

Effects of 4-phenylbutyrate therapy in a preterm infant with cholestasis and liver fibrosis

The bile salt export pump is expressed at the canalicular membrane of hepatocytes and mediates biliary excretion of bile salts. 4-Phenylbutyrate (4 PB), a drug used to treat ornithine transcarbamylase deficiency, has been found to increase the hepatocanalicular expression of bile salt export pump. The beneficial effects of 4-phenylbutyrate therapy have been reported for patients with progressive familial intrahepatic cholestasis, an inherited autosomal recessive liver disease. This is the first study to show the therapeutic effect of 4 PB in a preterm infant with cholestasis and liver fibrosis. The preterm infant had severe cholestasis with jaundice and failure to thrive refractory to ursodeoxycholic acid. Histology indicated giant cell hepatitis, cholestasis, and severe fibrosis. Bile salt export pump immunostaining showed lower expression than in a control. Oral 4 PB was started at a daily dose of 200 mg/kg/day. After the start of 4 PB therapy, cholestasis improved.

Molecular Genetic Dissection and Neonatal/Infantile Intrahepatic Cholestasis Using Targeted Next-Generation Sequencing

OBJECTIVES

To ascertain a molecular genetic diagnosis for subjects with neonatal/infantile intrahepatic cholestasis (NIIC) by the use of next-generation sequencing (NGS) and to perform a genotype-phenotype correlation.

STUDY DESIGN

We recruited Japanese subjects with NIIC who had no definitive molecular genetic diagnosis. We developed a diagnostic custom panel of 18 genes, and the amplicon library was sequenced via NGS. We then compared clinical data between the molecular genetically confirmed subjects with NIIC.

RESULTS

We analyzed 109 patients with NIIC ("genetic cholestasis," 31 subjects; "unknown with complications" such as prematurity, 46 subjects; "unknown without complications," 32 subjects), and a molecular genetic diagnosis was made for 28 subjects (26%). The rate of positive molecular genetic diagnosis in each category was 22 of 31 (71%) for the "genetic cholestasis" group, 2 of 46 (4.3%) for the "unknown with complications" group, and 4 of 32 (12.5%) for the "unknown without complications" group. The grouping of the molecular diagnoses in the group with genetic cholestasis was as follows: 12 with Alagille syndrome, 5 with neonatal Dubin-Johnson syndrome, 5 with neonatal intrahepatic cholestasis caused by citrin deficiency, and 6 with progressive familial intrahepatic cholestasis or benign recurrent intrahepatic cholestasis with low gamma-glutamyl transpeptidase levels. Several clinical datasets, including age of onset, direct bilirubin, and aminotransferases, were significantly different between the disorders confirmed using molecular genetic diagnosis.

CONCLUSION

Targeted NGS can be used for molecular genetic diagnosis in subjects with NIIC. Clinical diagnosis should be accordingly redefined in the view of molecular genetic findings.

Biopsy-driven diagnosis in infants with cholestatic jaundice in Iran

AIM: To determine the frequencies of diagnoses confirmed by liver biopsy in infants with cholestasis in an Iranian pediatric hospital.

METHODS: This was a retrospective study conducted in a tertiary referral children’s hospital in Iran. We retrieved all pathology reports of liver biopsies from children less than two years of age who had presented for evaluation of cholestatic jaundice from March 2001 to March 2011. Additional specimen samples obtained from archived pathology blocks were reviewed by a pathologist blinded to the final diagnosis. These results were compared with the pathology reports from chart records to ensure consensus and eliminate any inconsistencies in final diagnoses. A structured checklist was used to gather information on multiple variables including age, sex, gestational age at birth, birth weight, age at which hyperbilirubinemia manifested, presence and identification of associated anomalies, clinical manifestations, and histological findings from liver biopsies. The baseline data are reported using descriptive statistics, and differences between groups were assessed by Fisher’s exact test and Student’s t test when indicated.

RESULTS: Fifty-five cases (28 females; 27 males) of infantile cholestasis (IC) were included in this study. The mean serum total bilirubin and direct bilirubin at presentation were 13.6 ± 5.9 and 7.3 ± 3.4, respectively. Forty cases (72.7%) were the product of term pregnancies. Common associated clinical findings were acholic stool in 33 cases (60.0%), hepatomegaly in 30 cases (54.5%), and dark-colored urine in 21 cases (38.2%). Biliary atresia (BA) was the most frequent diagnosis, found in 32 cases (58.2%), followed by intrahepatic bile duct paucity found in 6 cases (10.9%), metabolic disease in 6 cases (10.9%), idiopathic neonatal hepatitis in 5 cases (9.1%), choledochal cyst in 2 cases (3.6%), liver cirrhosis in 2 cases (3.6%), and progressive familial intrahepatic cholestasis and portal fibrosis each in 1 case (1.8%). The mean times for jaundice onset and liver biopsy were 43.8 and 102.0 d, respectively. In BA, the mean age at jaundice presentation was 21 d and for liver biopsy was 87.5 d, representing a mean delay of 66.5 d.

CONCLUSION: A significant delay was found between IC presentation and liver biopsy, which is detrimental in conditions that can cause irreversible liver damage, such as BA.

Growth and development of a new subspecialty: pediatric hepatology

Several major forces converged to catalyze the formal emergence of a body of knowledge and an organized focus on disorders of the liver in early life. Attendant to the development of a focused clinical subspecialty the pace of patient- and laboratory-based research in the field quickened in parallel to decipher the consequences of genetic or metabolic aberrations on immature liver structure and function. The key research observations that catalyzed the emergence and subsequent rapid growth of Pediatric Hepatology include: (1) an understanding of the dynamic events occurring during hepatobiliary development and the importance of these physiologic variables that occur during liver maturation; (2) the recognition of the unique nature of inherited and acquired liver diseases that affect infants and children-such as biliary atresia and Reye's syndrome; and (3) redefinition of the once obscure inherited intrahepatic cholestatic diseases of the liver, which, in turn, provided insight into normal and abnormal hepatobiliary physiology. The clinical advances were highlighted by the development of specific approaches to the diagnosis and management of liver disease in infants and children, including both liver transplantation and nontransplant treatment options. These seminal events led to the expansion of the workforce, creating a critical mass consisting of individuals with focused, specialized skills and techniques. In-depth expertise allowed more accurate diagnosis and highly effective treatment strategies for advanced hepatobiliary disease in children. The demand for pediatric clinicians with experience in advanced hepatology allowed sub-sub-specialization to flourish. Continued maturation of the field led to definition of hepatology-focused curricular elements and educational content for Pediatric Gastroenterology training programs, and subsequently the development of program requirements for those who wished to acquire additional training in Pediatric Hepatology. A significant rite of passage was marked by the election of pediatric hepatologists to leadership positions in the American Association for the Study of Liver Diseases (AASLD). Further validation of the field occurred with approval of the petition for establishing a Certificate of Added Qualification in Transplant Hepatology by the American Board of Pediatrics. Here I relate my perspective on the history of the advances in our field and the contributions of many of the clinicians and scientists whose efforts led to the development of focused clinical, research, and training programs that improved the care of children with diseases of the liver.

Genetic characterization to improve interpretation and clinical management of hepatotoxicity caused by tyrosine kinase inhibitors

Tyrosine kinase inhibitors (TKIs) represent important therapeutic alternatives to, or combinations with, traditional cytotoxic chemotherapy. Despite their selective molecular targeting and demonstrated clinical benefit, TKIs produce a range of serious adverse events, including drug-induced liver injury, that require careful patient management to maintain treatment benefit without harm. Genetic characterization of serious adverse events can identify mechanisms of injury and improve safety risk management. This review presents pharmacogenetic comparisons of two approved TKIs, lapatinib and pazopanib, which reveal different mechanisms of injury and inform the characteristics and risk of serious liver injury in treated patients. The data presented demonstrate the utility of genetic studies to investigate drug-induced liver injury and potentially support its management in patients.

Anti-tumor necrosis factor-α monoclonal antibody alleviates parenteral nutrition-associated liver disease in mice

BACKGROUND

The authors aimed to investigate the role of anti-tumor necrosis factor (TNF)-α monoclonal antibody treatment in a mouse model of parenteral nutrition-associated liver disease (PNALD).

METHODS

C57BL/6J male mice (aged 6-8 weeks) were randomly assigned to 3 groups: parenteral nutrition (PN), PN with anti-TNF-α monoclonal antibody treatment (PN + mAb), and controls. A central venous catheter was inserted for intravenous infusion of a PN solution (PN and PN + mAb groups) or saline (controls) for 7 days. Liver pathology, hepatic biochemical indicators, and serum TNF-α concentrations were analyzed. Levels of hepatic bsep, mdr1a/mdr1b, mdr2, and mrp2 mRNA were also evaluated in each group.

RESULTS

The PN group showed significant increases in serum transaminase, direct bilirubin, and bile acids relative to the control group (P < .05). Histopathological changes in this group were consistent with early stage cholestasis. The pathological score and serum alanine aminotransferase, total bilirubin, and direct bilirubin levels were improved in the PN + mAb group relative to the PN group (P < .05). The PN group showed significantly lower hepatic bsep, mdr1a/mdr1b, mdr2, and mrp2 mRNA expression than the controls (P < .05), but these were significantly increased compared to the PN group (P < .05).

CONCLUSIONS

Infliximab administered at a single dose of 5 mg/kg body weight ameliorated the progression of PNALD and improved the expression of hepatic ABC transporter genes. Therefore, anti-TNF-α monoclonal antibody may be a beneficial therapy for patients with PNALD.

Progressive familial intrahepatic cholestasis: a single-center experience of living-donor liver transplantation during two decades in Japan

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) results in liver cirrhosis. Therefore, some PFIC patients require liver transplantation (LT). Although three types of PFIC have been identified, their etiologies include unknown mechanisms.

PATIENTS

A total of 717 recipients who underwent living-donor LT (LDLT) at <20 yr old were enrolled in this study. Among these recipients, 14 PFIC recipients comprising 11 PFIC type 1 (PFIC1) and three PFIC type 2 (PFIC2) were evaluated.

RESULTS

Three of 11 PFIC1 recipients died, while all three PFIC2 recipients survived. Eight of 11 PFIC1 recipients showed steatosis after LDLT. Among the eight steatosis-positive PFIC1 recipients, seven showed severe steatosis and seven were complicated with steatohepatitis. Nine of 11 PFIC1 recipients showed fibrosis after LDLT, and eight of the nine fibrosis-positive PFIC1 recipients showed severe fibrosis. In contrast to the PFIC1 recipients, the PFIC2 recipients did not show any steatosis or fibrosis after LDLT.

CONCLUSIONS

The clinical courses and outcomes of PFIC1 recipients after LDLT are still not sufficient owing to steatosis/fibrosis, unlike the case for PFIC2 recipients. As PFIC1 patients will require LT during the long-term progression of the disease, further strategy improvements are required for PFIC1 patients.

Living-donor liver transplantation for progressive familial intrahepatic cholestasis

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) results in liver cirrhosis during the disease course, although the etiology includes unknown mechanisms. Some PFIC patients require liver transplantation (LT).

METHODS

In this study, 11 patients with PFIC type 1 (PFIC1) and 3 patients with PFIC type 2 (PFIC2) who underwent living-donor LT (LDLT) were evaluated.

RESULTS

Digestive symptoms after LDLT were confirmed in 10 PFIC1 recipients (90.9%); 8 PFIC1 recipients showed steatosis after LDLT (72.7%), which began during the early postoperative period (71.5±55.1 days). Seven of the eight steatosis-positive PFIC1 recipients (87.5%) showed a steatosis degree of ≥80%, which was complicated with steatohepatitis and resulted in fibrosis. Cirrhotic findings persisted in six PFIC1 recipients even after LDLT (54.5%), and three PFIC1 recipients finally died. The survival rates of the PFIC1 recipients at 5, 10, and 15 years were 90.9%, 72.7%, and 54.5%, respectively. In contrast, the PFIC2 recipients showed good courses and outcomes without any steatosis after LDLT.

CONCLUSIONS

The clinical courses and outcomes after LDLT are still not sufficient in PFIC1 recipients owing to steatosis/steatohepatitis and subsequent fibrosis, in contrast to PFIC2 recipients. PFIC2 is good indication for LDLT. PFIC1 patients require LT during the disease course; therefore, we suggest that the therapeutic strategies for PFIC1 patients, including the timing of LDLT, under the donor limitation should be reconsidered. The establishment of more advanced treatments for PFIC1 patients is required to improve the long-term prognosis of these patients.

Inflammatory pseudo-tumor of the liver: a rare pathological entity

Inflammatory pseudo-tumor (IPT) of the liver is a rare benign neoplasm and is often mistaken as a malignant entity. Few cases have been reported in the literature and the precise etiology of inflammatory pseudotumor remains unknown. Patients usually present with fever, abdominal pain and jaundice. The proliferation of spindled myofibroblast cells mixed with variable amounts of reactive inflammatory cells is characteristics of IPT. We reviewed the literature regarding possible etiology for IPT with a possible suggested etiology.

Serum and tissue transforming [corrected] growth factor β1 in children with biliary atresia

BACKGROUND

Biliary atresia (BA) is an infantile disorder characterized by the obstruction of a portion or the entirety of the extrahepatic bile ducts, leading to hepatic fibrosis and loss of liver function. The gold standard for diagnosing and grading fibrosis is liver biopsy, but there are many groups searching for noninvasive biomarkers that could replace and/or complement this procedure.

METHODS AND MATERIALS

In this study, we evaluated serum and tissue transforming growth factor β1 (TGFβ1) and aspartate aminotransferase [AST]-to-platelet ratio index (APRI) in patients with BA at the time of diagnosis and at liver transplantation and correlated these data with tissue collagen density, to verify if they could act as biomarkers for BA.

RESULTS

At the time of diagnosis, TGFβ1 levels were highly variable in BA patients. However, serum values at transplantation were significantly decreased (13.75 ± 3.68 ng/mL) as compared to controls (34.36 ± 9.35 ng/mL) (P = .01). No correlation was found between serum TGF1β1 and collagen density in both groups analyzed. Serum TGFβ1 showed no correlation with APRI at diagnosis. At the time of liver transplantation, all patients had low serum TGFβ1 and variable APRI, although all higher than 2.0. However, when platelet count was used, an inverse correlation with serum TGFβ1 was observed at the time of diagnostics (r(2) = 0.749; P = .03).

CONCLUSIONS

Our findings suggest that at the time of diagnosis the fibrogenic process is active, with higher levels of TGFβ1, whereas later on, there is scar tissue, with reduced TGFβ1 expression. Although our results should be confirmed in larger sets of patients with BA, the lack of TGFβ1 at the time of liver transplantation may have important consequences for the patient because it is a pleiotropic molecule, responsible for many functions in the body, mainly those related to immune response and cell growth.

Cholestasis in neonatal intensive care unit: incidence, aetiology and management

AIM

Prevalence, aetiology, management and outcome of cholestasis were evaluated in infants admitted to neonatal intensive care unit (NICU).

METHODS

Medical records of all infants admitted to two Italian level III NICUs from January 2005 to August 2007 were retrospectively reviewed. The role of ursodeoxycholic acid (UDCA) therapy was also investigated.

RESULTS

Twenty-seven of 1289 enrolled infants developed cholestasis. In 25 infants, cholestasis had a multifactorial basis, while in two, no aetiology was found. UDCA did not significantly affect clinical and biochemical course of cholestasis. During a period of 12 months, eight cholestatic infants died, one underwent liver transplantation and 18 fully recovered.

CONCLUSION

Infants admitted in NICU have a rate of cholestasis higher than that reported in the general population of live births; in most cases, cholestasis is associated to multiple risk factors and shows a favourable outcome. UDCA does not seem to affect clinical course of cholestasis in this setting.

Matrine improves 17alpha-ethinyl estradiol-induced acute cholestasis in rats

AIM

To explore the effects of matrine (MT) on acute intrahepatic cholestasis induced by 17alpha-ethinyl estradiol (EE) in rats.

METHODS

Acute intrahepatic cholestasis in rats were induced by EE, and the effects of MT on acute intrahepatic cholestasis were explored and compared with ursodeoxycholic acid (UDCA) by serum biochemical determination and bile excretion experiments.

RESULTS

The serum biochemical and bile biochemical results indicated that MT and UDCA had notable hepatoprotective effects by counteracting cholestasis induced by EE. The bile flow and the bile excretion of glycocholic acid (GC, a substrate of bile salt export pump [Bsep]), ketoprofen glucuronide (KPG) and rhodamine 123 (Rh123, a substrate of multidrug resistance protein 1 [MDR1]) decreased by EE, were significantly improved after administration of MT.

CONCLUSION

MT exhibited potential protection against EE-induced acute intrahepatic cholestasis.

Human herpesvirus type 6 hepatitis or familiar intrahepatic cholestasis: the importance of follow-up

A 1-month-old child presented to our unit with jaundice and raised aminotransferases, γ-glutamyltranspeptidase and bilirubin. Metabolic diseases were ruled out and ultrasound found no alterations. Human herpesvirus type 6 (HHV-6) DNA was found in blood and saliva and IgG anti-HHV-6 in serum, and a diagnosis of HHV-6 hepatitis was made. In the following weeks, aminotransferase values remained raised while γ-glutamyltranspeptidase levels returned to normal in 45 days. At the age of 5 months symptoms and elevated aminotransferases persisted and immunohistochemistry performed on liver tissue allowed a diagnosis of progressive familiar intrahepatic cholestasis type 2 to be made. The patient is now 7 months old, and cholestatic jaundice and pruritus continue to be present.

Alteration of canalicular transporters in a mouse model of total parenteral nutrition

OBJECTIVES

Parenteral nutrition-associated liver disease (PNALD) is a major problem with prolonged total parenteral nutrition (TPN) administration. Our laboratory previously demonstrated significant changes in the expression of multidrug resistance genes (MDRs) 1 and 2, hepatocyte transporters, in a TPN mouse model. The present study hypothesized that these changes would lead to functional changes in the liver, and would contribute to the development of liver dysfunction.

MATERIALS AND METHODS

Mice received either intravenous saline and standard chow or TPN with or without intravenous lipids. Functional assays were performed after 7 days of infusion.

RESULTS

TPN with lipids led to a significant increase in serum bile acid levels, consistent with an early state of PNALD. Use of TPN without lipids prevented an elevation in bile acid levels. In both TPN groups, MDR2 expression was significantly (68%) lower than controls and bile phosphatidylcholine content, a functional measure of MDR2, was 40% less than controls. MDR1 expression in the TPN with lipid group was 31% higher than controls, whereas in the TPN without lipids mice there was no significant change. Hepatocyte extrusion of rhodamine dye, a measure of MDR1 function, declined only in the TPN with lipid group. Peroxisome proliferator-activated receptor-alpha expression decreased in both TPN groups. Fenofibrate given with TPN resulted in an increased expression of MDR1 and MDR2, and functionally increased hepatocyte rhodamine extrusion and presence of bile phosphatidylcholine in the TPN with lipid group.

CONCLUSIONS

The study shows that TPN led to alterations in the function of MDR1- and MDR2-expressed proteins. The changes help in the understanding of the mechanisms leading to PNALD, and suggest that fibrate administration may palliate these changes.

Progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) refers to heterogeneous group of autosomal recessive disorders of childhood that disrupt bile formation and present with cholestasis of hepatocellular origin. The exact prevalence remains unknown, but the estimated incidence varies between 1/50,000 and 1/100,000 births.

Three types of PFIC have been identified and related to mutations in hepatocellular transport system genes involved in bile formation. PFIC1 and PFIC2 usually appear in the first months of life, whereas onset of PFIC3 may also occur later in infancy, in childhood or even during young adulthood. Main clinical manifestations include cholestasis, pruritus and jaundice. PFIC patients usually develop fibrosis and end-stage liver disease before adulthood. Serum gamma-glutamyltransferase (GGT) activity is normal in PFIC1 and PFIC2 patients, but is elevated in PFIC3 patients. Both PFIC1 and PFIC2 are caused by impaired bile salt secretion due respectively to defects in ATP8B1 encoding the FIC1 protein, and in ABCB11 encoding the bile salt export pump protein (BSEP). Defects in ABCB4, encoding the multi-drug resistant 3 protein (MDR3), impair biliary phospholipid secretion resulting in PFIC3.

Diagnosis is based on clinical manifestations, liver ultrasonography, cholangiography and liver histology, as well as on specific tests for excluding other causes of childhood cholestasis. MDR3 and BSEP liver immunostaining, and analysis of biliary lipid composition should help to select PFIC candidates in whom genotyping could be proposed to confirm the diagnosis. Antenatal diagnosis can be proposed for affected families in which a mutation has been identified. Ursodeoxycholic acid (UDCA) therapy should be initiated in all patients to prevent liver damage. In some PFIC1 or PFIC2 patients, biliary diversion can also relieve pruritus and slow disease progression. However, most PFIC patients are ultimately candidates for liver transplantation. Monitoring of hepatocellular carcinoma, especially in PFIC2 patients, should be offered from the first year of life. Hepatocyte transplantation, gene therapy or specific targeted pharmacotherapy may represent alternative treatments in the future.

Clinical and pathological characteristics of Alagille syndrome in Chinese children

BACKGROUND

Alagille syndrome (AS) is regarded as the most common cause of chronic cholestasis in childhood associated with specific phenotypic features in western countries. This study was undertaken to investigate the significance of AS in Chinese children with chronic cholestasis and to describe its clinical and histological features.

METHODS

From October 2004 to January 2007, 157 children who presented with conjugated jaundice from less than 3 months of age were admitted to a tertiary hospital in Shanghai. Investigations of the heart, spine, eyes and kidneys were conducted in 13 children who experienced prolonged cholestasis beyond 1 year of age after exclusion of biliary atresia and familial progressive intrahepatic cholestasis type 1 or 2. In patients with interlobular bile duct paucity, AS was diagnosed if 3 or more of the following 5 major features were present: cardiac murmur, posterior embryotoxon, butterfly-like vertebrae, renal abnormalities and characteristic faces. In patients without interlobular bile duct paucity or who did not receive liver biopsy, 4 or more features were required for the diagnosis.

RESULTS

Of the 13 children, 6 were diagnosed with AS at ages ranging from 1 year and 7 months to 3 years and 11 months. Jaundice was noticed in early infancy and then pruritus developed in all the 6 patients, of whom 5 presented with acholic stool and 4 had been misdiagnosed as having presumed biliary atresia by hepatobiliary scintigraphy or laparoscopic cholangiography. Biochemical examinations demonstrated increased concentration of total bile acid and hyperlipidemia. Interlobular bile duct paucity was demonstrated histologically in 5 patients who received liver biopsy. Vertebral abnormalities, heart murmur, characteristic faces and failure to thrive were found in all the 6 patients. Two patients had evidence of renal involvement. Micropenis, empty scrotum, and gall stone were seen in 1 patient.

CONCLUSION

AS is also an important cause of prolonged cholestasis in Chinese children. It is difficult to differentiate AS from biliary atresia. Liver biopsy and spine X-ray may be helpful in the early detection of AS.

Molecular pathogenesis of intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) occurs mainly in the third trimester and is characterised by pruritus and elevated serum bile acid levels. ICP is associated with an increased perinatal risk and higher rates of foetal morbidity and mortality. Although the pathogenesis of this disease is unknown, a genetic hypersensitivity to female hormones (oestrogen and/or progesterone) or their metabolites is thought to impair bile secretory function. Recent data suggest that mutations or polymorphisms of genes expressing hepatobiliary transport proteins or their nuclear regulators may contribute to the development and/or severity of ICP. Unidentified environmental factors may also influence pathogenesis of the disease. This review summarises current knowledge on the potential mechanisms involved in ICP at the molecular level.

Diagnosis and management of cholestatic liver disease

Cholestasis (slowing of bile flow) may be acute or chronic and affect any age group. In infants and children the causes often are congenital or inherited and as a result of improved management some affected children now survive to adulthood. Although jaundice is a hallmark of cholestasis it may be absent, particularly in adults with chronic cholestatic liver disease most of whom are entirely asymptomatic. A detailed history and physical are crucial to the diagnosis and noninvasive radiologic tests (ultrasound, computerized tomography scan, and magnetic resonance cholangiography) greatly facilitate diagnosis, particularly when the cause is extrahepatic. Only if sufficient portal tracts (>10) are present on liver biopsy examination can this test reliably evaluate damage to the small bile ducts. Therapy should address both the cause and the consequences of retained bile acids within the liver, and diminished delivery of bile to the gastrointestinal tract. Therapies should address symptoms, mostly pruritus and prevention, particularly osteoporosis and osteomalacia. Portal hypertension can be an early event in chronic cholestatic liver disease, sometimes occurring before the development of cirrhosis. Ursodeoxycholic acid improves the biochemical markers of cholestasis regardless of cause and may delay liver disease progression; only liver transplant is potentially curative.

Novel resequencing chip customized to diagnose mutations in patients with inherited syndromes of intrahepatic cholestasis

BACKGROUND & AIMS

Inherited syndromes of intrahepatic cholestasis commonly result from mutations in the genes SERPINA1 (alpha(1)-antitrypsin deficiency), JAG1 (Alagille syndrome), ATP8B1 (progressive familial intrahepatic cholestasis type 1 [PFIC1]), ABCB11 (PFIC2), and ABCB4 (PFIC3). However, the large gene sizes and lack of mutational hotspots make it difficult to survey for disease-causing mutations in clinical practice. Here, we aimed to develop a technological tool that reads out the nucleotide sequence of these genes rapidly and accurately.

METHODS

25-mer nucleotide probes were designed to identify each base for all exons, 10 bases of intronic sequence bordering exons, 280-500 bases upstream from the first exon for each gene, and 350 bases of the second intron of the JAG1 gene and tiled using the Affymetrix resequencing platform. We then developed high-fidelity polymerase chain reactions to produce amplicons using 1 mL of blood from each subject; amplicons were hybridized to the chip, and nucleotide calls were validated by standard capillary sequencing methods.

RESULTS

Hybridization of amplicons with the chip produced a high nucleotide sequence readout for all 5 genes in a single assay, with an automated call rate of 93.5% (range, 90.3%-95.7%). The accuracy of nucleotide calls was 99.99% when compared with capillary sequencing. Testing the chip on subjects with cholestatic syndromes identified disease-causing mutations in SERPINA1, JAG1, ATP8B1, ABCB11, or ABCB4.

CONCLUSIONS

The resequencing chip efficiently reads SERPINA1, JAG1, ATP8B1, ABCB11, and ABCB4 with a high call rate and accuracy in one assay and identifies disease-causing mutations.

Normal pancreatic secretion in children with progressive familial intrahepatic cholestasis type 1

OBJECTIVE

Progressive familial intrahepatic cholestasis type 1 (PFIC1) is a rare, autosomal, recessive, inherited disease resulting from mutations in the ATP8B1 gene which is expressed at high levels in the small intestine and pancreas and at lower levels in the liver. Given this expression pattern, patients might be expected to have a pancreatic phenotype. Although pancreatitis and steatorrhea have been reported in patients with PFIC1, the available data on pancreatic function are not fully convincing. Therefore, the objective of this study was to assess exocrine pancreatic function in patients with PFIC1.

MATERIAL AND METHODS

Three subjects with a diagnosis of PFIC1 were included in the study. The diagnosis was confirmed by molecular analysis of ATP8B1. Prior to surgical treatment (biliary diversion), two patients had steatorrhea and in the third patient, a borderline value for fecal fat excretion was documented. In one patient, liver transplantation also was subsequently performed. Exocrine pancreatic secretion was assessed by the use of fecal elastase-1 and chymotrypsin tests. Fecal lipase concentrations were determined in order to exclude isolated lipase deficiency. Other typical diagnostic procedures were performed annually.

RESULTS

The results of the fecal tests were within the normal range. None of the three patients experienced any episodes that could be related to acute or chronic pancreatitis. Laboratory tests including serum amylase and lipase tests were always normal. Abdominal ultrasonography findings did not show any pancreatic pathology.

CONCLUSIONS

Pancreatic secretion in the study patients with progressive familial intrahepatic cholestasis type 1 was normal. The observed steatorrhea was not related to pancreatic insufficiency.

The next challenge in pediatric cholestasis: deciphering the pathogenesis of biliary atresia

Cholestasis is a common presenting symptom of liver disease in infants. Chief among diseases presenting as neonatal cholestasis is biliary atresia, the most common cause of chronic liver disease in children, but little is known about the pathogenesis of this disease. In search for the molecular basis of biliary atresia, we began two areas of investigation. In the first, we interrogated the hepatic transcriptome of children with biliary atresia and found an interferon-gamma (IFNgamma)-rich proinflammatory footprint at the time of diagnosis. To directly explore if IFNgamma plays an important role in biliary injury and obstruction, we used a mouse model of experimental biliary atresia and found that inactivation of the murine Ifngamma gene decreases the tropism of lymphocytes to neonatal bile ducts and prevents the inflammatory obstruction of the duct lumen. Further analysis of the extrahepatic biliary tract also outlined a broader network of proinflammatory genes at the onset and during progression to duct obstruction, with the time-specific activation of IFNgamma-, apoptosis-, and complement-driven networks. In the second approach, we searched for molecular profiles that differentiate clinical forms of biliary atresia by analyzing the hepatic transcriptome of age-matched subjects at the time of diagnosis. We found a preliminary profile that differentiates the embryonic from the perinatal forms of biliary atresia. The profile contained the differential activation of genes involved in epigenetic mechanisms of disease. Collectively, these studies provide new insight into pathogenesis of biliary atresia and identify potential therapeutic targets to foster long-term outcome with the native liver.

A new ABCB11 mutation in two Italian children with familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) syndromes are characterized by defects in transporters of conjugated bile acids into the bile canaliculus. Three genes (ATP8B1, ABCB11, ABCB4) are associated with the different forms, but no easy genotype-phenotype correlations help in the prioritization for gene testing. We developed a denaturing high-performance liquid chromatography (DHPLC) method to screen patients with PFIC for mutations in ATP8B1 and ABCB11, and combined genetic analyses with immunolabeling in liver for the ABCB11 and ABCB4 gene products. Used in combination with commercially available antibodies on liver specimens, the DHPLC approach allowed us to confirm the clinical diagnosis in two Italian sisters and to identify a novel missesnse mutation in ABCB11. Our findings are expected to facilitate detection of the molecular cause of PFIC in affected families.