Progressive familial intrahepatic cholestasis

Molecular characterization of exons 6, 8 and 9 of ABCB4 gene in children with Progressive Familial Intrahepatic Cholestasis type 3

AIM OF WORK

To estimate the frequency of mutations involving exons 6, 8 and 9 of Adenosine triphosphate-binding cassette, subfamily B, member 4 (ABCB4) gene among children with progressive intrahepatic cholestasis with high γ-GT activity (PFIC3).

SUBJECTS AND METHODS

Cross sectional study was conducted on 30 children with PFIC3. Genotyping was performed by sequencing analysis of exons 6, 8 and exon 9 of ABCB4 gene.

RESULTS

Heterozygous synonymous polymorphic variant was detected in exon 6 (rs 1202283) and in exon 8 (rs 2109505). No mutations in studied exons were detected.

CONCLUSION

Exons 6, 8 and 9 mutations of ABCB4 gene are not common among Egyptian children with PFIC3.

Cholestasis beyond the Neonatal and Infancy Periods

Cholestasis results from impairment in the excretion of bile, which may be due to mechanical obstruction of bile flow or impairment of excretion of bile components into the bile canaliculus. When present, cholestasis warrants prompt diagnosis and treatment. The differential diagnosis of cholestasis beyond the neonatal period is broad and includes congenital and acquired etiologies. It is imperative that the clinician differentiates between intrahepatic and extrahepatic origin of cholestasis. Treatment may be supportive or curative and depends on the etiology. Recent literature shows that optimal nutritional and medical support also plays an integral role in the management of pediatric patients with chronic cholestasis. This review will provide a broad overview of the pathophysiology, diagnostic approach, and management of cholestasis beyond the neonatal and infancy periods.

Different techniques for biliary diversion in progressive familial intrahepatic cholestasis

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) is a cholestatic liver disease of childhood. Pruritus resulting from increased bile salts in serum might not respond to medical treatment, and internal or external biliary drainage methods have been described. In this study, we aimed to evaluate different internal drainage techniques in patients with PFIC.

PATIENTS AND METHODS

Between 2009 and 2014, seven children (4 male, 3 female, 3months-5years old), (median 2years of age) with PFIC were evaluated. The patients were reviewed according to age, gender, complaints, surgical technique, laboratory findings and outcome. In each two patients, cholecystoileocolonic anastomosis, cholecystojejunocolonic anastomosis and cholecystocolostomy were performed. Cholecysto-appendico-colonic anastomosis was the technique used in one patient.

RESULTS

Jaundice and excessive pruritus were the main complaints. One of the patients with cholecystoileocolonic anastomosis died of comorbid pathologies (cirrhosis, adhesive obstruction and severe sepsis). Temporary rectal bleeding was observed in all the patients postoperatively. Regardless of the surgical technique, pruritus was dramatically decreased in all the patients in the postoperative period.

CONCLUSION

Regardless of the technique, internal biliary diversion methods are beneficial for the relief of pruritus in PFIC patients. Selection of the surgical method might vary depending on the surgeon's preference and the surgical anatomy of the gastrointestinal system of the patient.

Mutations in the nuclear bile acid receptor FXR cause progressive familial intrahepatic cholestasis

Neonatal cholestasis is a potentially life-threatening condition requiring prompt diagnosis. Mutations in several different genes can cause progressive familial intrahepatic cholestasis, but known genes cannot account for all familial cases. Here we report four individuals from two unrelated families with neonatal cholestasis and mutations in NR1H4, which encodes the farnesoid X receptor (FXR), a bile acid-activated nuclear hormone receptor that regulates bile acid metabolism. Clinical features of severe, persistent NR1H4-related cholestasis include neonatal onset with rapid progression to end-stage liver disease, vitamin K-independent coagulopathy, low-to-normal serum gamma-glutamyl transferase activity, elevated serum alpha-fetoprotein and undetectable liver bile salt export pump (ABCB11) expression. Our findings demonstrate a pivotal function for FXR in bile acid homeostasis and liver protection.

Neonatal cholestasis is a result of elevated bile acid levels, and is associated with mutations in genes regulating bile acid homeostasis. Here the authors identify mutations in the bile acid sensing farnesoid X receptor in four individuals with neonatal cholestasis from two unrelated families.

Elevation of gamma-glutamyl transferase in adult: Should we think about progressive familiar intrahepatic cholestasis?

BACKGROUND

There are three types of progressive familial intrahepatic cholestasis (PFIC). Type 3 is characterized by elevated gamma-glutamyl transferase (γ-GT) and it can be diagnosed in adolescence/adulthood. The genetic defect of PFIC 3 appears to explain the pathogenesis of intrahepatic cholestasis of pregnancy (ICP).

AIMS

Draw attention to this rare disease, especially in adulthood, and clarify the association between ICP and PFIC 3.

RESULTS

We describe a series of cases from a Portuguese northern family with two brothers presenting chronic cholestasis since adolescence. Brother 1: since 15-years-old with pruritus and elevated γ-GT ∼6x. Brother 2: pre-term, due to severe maternal pruritus and jaundice, since 13-years-old with pruritus, jaundice and ∼8x γ-GT elevation. Common causes of cholestasis were excluded and liver histologies were nonspecific. Research for mutation on ABCB4 gene showed mutations in both alleles.

CONCLUSION

Disease and mechanisms that determine cholestasis are complex and their understanding may provide new therapeutics.

Bile salt export pump-reactive antibodies form a polyclonal, multi-inhibitory response in antibody-induced bile salt export pump deficiency

Progressive familial intrahepatic cholestasis type 2 (PFIC-2) is caused by mutations in ABCB11, encoding the bile salt export pump (BSEP). In 2009, we described a child with PFIC-2 who developed PFIC-like symptoms after orthotopic liver transplantation (OLT). BSEP-reactive antibodies were demonstrated to account for disease recurrence. Here, we characterize the nature of this antibody response in 7 more patients with antibody-induced BSEP deficiency (AIBD). Gene sequencing and immunostaining of native liver biopsies indicated absent or strongly reduced BSEP expression in all 7 PFIC-2 patients who suffered from phenotypic disease recurrence post-OLT. Immunofluorescence, western blotting analysis, and transepithelial transport assays demonstrated immunoglobulin (Ig) G-class BSEP-reactive antibodies in these patients. In all cases, the N-terminal half of BSEP was recognized, with reaction against its first extracellular loop (ECL1) in six sera. In five, antibodies reactive against the C-terminal half also were found. Only the sera recognizing ECL1 showed inhibition of transepithelial taurocholate transport. In a vesicle-based functional assay, transport inhibition by anti-BSEP antibodies binding from the cytosolic side was functionally proven as well. Within 2 hours of perfusion with antibodies purified from 1 patient, rat liver showed canalicular IgG staining that was absent after perfusion with control IgG.

CONCLUSIONS

PFIC-2 patients carrying severe BSEP mutations are at risk of developing BSEP antibodies post-OLT. The antibody response is polyclonal, targeting both extra- and intracellular BSEP domains. ECL1, a unique domain of BSEP, likely is a critical target involved in transport inhibition as demonstrated in several patients with AIBD manifest as cholestasis.

Autoimmune BSEP disease: disease recurrence after liver transplantation for progressive familial intrahepatic cholestasis

Severe cholestasis may result in end-stage liver disease with the need of liver transplantation (LTX). In children, about 10 % of LTX are necessary because of cholestatic liver diseases. Apart from bile duct atresia, three types of progressive familial intrahepatic cholestasis (PFIC) are common causes of severe cholestasis in children. The three subtypes of PFIC are defined by the involved genes: PFIC-1, PFIC-2, and PFIC-3 are due to mutations of P-type ATPase ATP8B1 (familial intrahepatic cholestasis 1, FIC1), the ATP binding cassette transporter ABCB11 (bile salt export pump, BSEP), or ABCB4 (multidrug resistance protein 3, MDR3), respectively. All transporters are localized in the canalicular membrane of hepatocytes and together mediate bile salt and phospholipid transport. In some patients with PFIC-2 disease, recurrence has been observed after LTX, which mimics a PFIC phenotype. It could be shown by several groups that inhibitory anti-BSEP antibodies emerge, which most likely cause disease recurrence. The prevalence of severe BSEP mutations (e.g., splice site and premature stop codon mutations) is very high in this group of patients. These mutations often result in the complete absence of BSEP, which likely accounts for an insufficient auto-tolerance against BSEP. Although many aspects of this "new" disease are not fully elucidated, the possibility of anti-BSEP antibody formation has implications for the pre- and posttransplant management of PFIC-2 patients. This review will summarize the current knowledge including diagnosis, pathomechanisms, and management of "autoimmune BSEP disease."

Deficiency of multidrug resistance 2 contributes to cell transformation through oxidative stress

Multidrug resistance 2 (Mdr2), also called adenosine triphosphate-binding cassette B4 (ABCB4), is the transporter of phosphatidylcholine (PC) at the canalicular membrane of mouse hepatocytes, which plays an essential role for bile formation. Mutations in human homologue MDR3 are associated with several liver diseases. Knockout of Mdr2 results in hepatic inflammation, liver fibrosis and hepatocellular carcinoma (HCC). Whereas the pathogenesis in Mdr2 (-/-) mice has been largely attributed to the toxicity of bile acids due to the absence of PC in the bile, the question of whether Mdr2 deficiency per se perturbs biological functions in the cell has been poorly addressed. As Mdr2 is expressed in many cell types, we used mouse embryonic fibroblasts (MEF) derived from Mdr2 (-/-) embryos to show that deficiency of Mdr2 increases reactive oxygen species accumulation, lipid peroxidation and DNA damage. We found that Mdr2 (-/-) MEFs undergo spontaneous transformation and that Mdr2 (-/-) mice are more susceptible to chemical carcinogen-induced intestinal tumorigenesis. Microarray analysis in Mdr2-/- MEFs and cap analysis of gene expression in Mdr2 (-/-) HCCs revealed extensively deregulated genes involved in oxidation reduction, fatty acid metabolism and lipid biosynthesis. Our findings imply a close link between Mdr2 (-/-) -associated tumorigenesis and perturbation of these biological processes and suggest potential extrahepatic functions of Mdr2/MDR3.

Genetics and Molecular Modeling of New Mutations of Familial Intrahepatic Cholestasis in a Single Italian Center

Familial intrahepatic cholestases (FICs) are a heterogeneous group of autosomal recessive disorders of childhood that disrupt bile formation and present with cholestasis of hepatocellular origin. Three distinct forms are described: FIC1 and FIC2, associated with low/normal GGT level in serum, which are caused by impaired bile salt secretion due to defects in ATP8B1 encoding the FIC1 protein and defects in ABCB11 encoding bile salt export pump protein, respectively; FIC3, linked to high GGT level, involves impaired biliary phospholipid secretion due to defects in ABCB4, encoding multidrug resistance 3 protein. Different mutations in these genes may cause either a progressive familial intrahepatic cholestasis (PFIC) or a benign recurrent intrahepatic cholestasis (BRIC). For the purposes of the present study we genotyped 27 children with intrahepatic cholestasis, diagnosed on either a clinical or histological basis. Two BRIC, 23 PFIC and 2 BRIC/PFIC were identified. Thirty-four different mutations were found of which 11 were novel. One was a 2Mb deletion (5’UTR- exon 18) in ATP8B1. In another case microsatellite analysis of chromosome 2, including ABCB11, showed uniparental disomy. Two cases were compound heterozygous for BRIC/PFIC2 mutations. Our results highlight the importance of the pathogenic role of novel mutations in the three genes and unusual modes of their transmission.

Structural and functional hepatocyte polarity and liver disease

Hepatocytes form a crucially important cell layer that separates sinusoidal blood from the canalicular bile. They have a uniquely organized polarity with a basal membrane facing liver sinusoidal endothelial cells, while one or more apical poles can contribute to several bile canaliculi jointly with the directly opposing hepatocytes. Establishment and maintenance of hepatocyte polarity is essential for many functions of hepatocytes and requires carefully orchestrated cooperation between cell adhesion molecules, cell junctions, cytoskeleton, extracellular matrix and intracellular trafficking machinery. The process of hepatocyte polarization requires energy and, if abnormal, may result in severe liver disease. A number of inherited disorders affecting tight junction and intracellular trafficking proteins have been described and demonstrate clinical and pathophysiological features overlapping those of the genetic cholestatic liver diseases caused by defects in canalicular ABC transporters. Thus both structural and functional components contribute to the final hepatocyte polarity phenotype. Many acquired liver diseases target factors that determine hepatocyte polarity, such as junctional proteins. Hepatocyte depolarization frequently occurs but is rarely recognized because hematoxylin-eosin staining does not identify the bile canaliculus. However, the molecular mechanisms underlying these defects are not well understood. Here we aim to provide an update on the key factors determining hepatocyte polarity and how it is affected in inherited and acquired diseases.

Transition of gastroenterological patients from paediatric to adult care: A position statement by the Italian Societies of Gastroenterology

In 2013, four Italian Gastroenterological Societies (the Italian Society of Paediatric Gastroenterology, Hepatology and Nutrition, the Italian Society of Hospital Gastroenterologists and Endoscopists, the Italian Society of Endoscopy, and the Italian Society of Gastroenterology) formed a joint panel of experts with the aim of preparing an official statement on transition medicine in Gastroenterology. The transition of adolescents from paediatric to adult care is a crucial moment in managing chronic diseases such as celiac disease, inflammatory bowel disease, liver disease and liver transplantation. Improved medical treatment and availability of new drugs and surgical techniques have improved the prognosis of many paediatric disorders, prolonging survival, thus making the transition to adulthood possible and necessary. An inappropriate transition or the incomplete transmission of data from the paediatrician to the adult Gastroenterologist can dramatically decrease compliance to treatment and prognosis of a young patient, particularly in the case of severe disorders. For these reasons, the Italian gastroenterological societies decided to develop an official shared transition protocol. The resulting document discusses the factors influencing the transition process and highlights the main points to accomplish to optimize compliance and prognosis of gastroenterological patients during the difficult transition from childhood to adolescence and adulthood.

Promoting expression of transporters for treatment of progressive familial intrahepatic cholestasis disease

Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of autosomal recessive genetic diseases with a major clinical manifestation of severe intrahepatic cholestasis and an incidence rate of 1/10000 to 1/5000. PFIC is usually first diagnosed in infancy or childhood and eventually develops into liver failure and death. Based on clinical manifestations, laboratory tests, and genetic defects in liver tissue, PFIC is roughly divided into three types: PFIC-1, PFIC-2 and PFIC-3. Studies have demonstrated that all three types of PFIC are associated with the mutations of bile transport system genes in the liver. Promoting transporter expression has important clinical significance for the treatment of PFIC. In this paper, we summarize the etiology and treatment status of PFIC and discuss the treatment of PFIC by promoting the expression of transporters.

Management of pruritus in chronic liver disease

Background. There continues to be uncertainty on the ideal treatment of pruritus in chronic liver disease. The aim of this study was to gather the latest information on the evidence-based management of pruritus in chronic liver disease. Methodology. A literature search for pruritus in chronic liver disease was conducted using Pubmed and Embase database systems using the MeSH terms “pruritus,” “chronic liver disease,” “cholestatic liver disease,” and “treatment.” Results. The current understanding of the pathophysiology of pruritus is described in addition to detailing research into contemporary treatment options of the condition. These medical treatments range from bile salts, rifampicin, and opioid receptor antagonists to antihistamines. Conclusion. The burden of pruritus in liver disease patients persists and, although it is a common symptom, it can be difficult to manage. In recent years there has been greater study into the etiology and treatment of the condition. Nonetheless, pruritus remains poorly understood and many patients continue to suffer, reiterating the need for further research to improve our understanding of the etiology and treatment for the condition.

Novel mutation in a Chinese patient with progressive familial intrahepatic cholestasis type 3

Genotyping is conclusive for the diagnosis of progressive familial intrahepatic cholestasis type 3 (PFIC3). Here we report a Chinese patient of PFIC3 with compound mutations in the ABCB4 gene. Liver biopsy was performed on a 17-year-old male patient with intrahepatic cholestasis of unknown etiology. Liver histology findings are indicative of intrahepatic cholestasis with extensive fibrosis. Genotyping revealed c.175C>T (p.L59L) mutation in exon 4, c.504C>T (p.N168N) mutation in exon 6, c.711A>T (p.I237I) mutation in exon 8, c.874A>T (p.K292X) in exon 9 and a novel mutation, c.1804G>T (p.G602W) in exon 15. Based on these findings, the patient was diagnosed with PFIC3. The novel mutation p.G602W in exon 15 was predicted as probably damaging by PolyPhen-2 with a score of 0.986 (sensitivity: 0.54; specificity: 0.94) and was predicted to affect protein function with a SIFT score of 0.01.

Neonatal Cholestasis - Differential Diagnoses, Current Diagnostic Procedures, and Treatment

Cholestatic jaundice in early infancy is a complex diagnostic problem. Misdiagnosis of cholestasis as physiologic jaundice delays the identification of severe liver diseases. In the majority of infants, prolonged physiologic jaundice represent benign cases of breast milk jaundice, but few among them are masked and caused by neonatal cholestasis (NC) that requires a prompt diagnosis and treatment. Therefore, a prolonged neonatal jaundice, longer than 2 weeks after birth, must always be investigated because an early diagnosis is essential for appropriate management. To rapidly identify the cases with cholestatic jaundice, the conjugated bilirubin needs to be determined in any infant presenting with prolonged jaundice at 14 days of age with or without depigmented stool. Once NC is confirmed, a systematic approach is the key to reliably achieve the diagnosis in order to promptly initiate the specific, and in many cases, life-saving therapy. This strategy is most important to promptly identify and treat infants with biliary atresia, the most common cause of NC, as this requires a hepatoportoenterostomy as soon as possible. Here, we provide a detailed work-up approach including initial treatment recommendations and a clinically oriented overview of possible differential diagnoses in order to facilitate the early recognition and a timely diagnosis of cholestasis. This approach warrants a broad spectrum of diagnostic procedures and investigations including new methods that are described in this review.

Progressive Familial Intrahepatic Cholestasis: A Rare Cause of Cirrhosis in Young Adult Patients

Hepatic cirrhosis is an important cause of morbidity and mortality. An unusual case of cirrhosis and portal hypertension in an 18-year-old patient secondary to Progressive Intrahepatic Cholestasis is discussed. The clinical and biochemical findings are discussed and a clinical approach to determining the underlying etiology of cirrhosis is outlined. Significant complications of portal hypertension include ascites, spontaneous bacterial peritonitis, hepatorenal syndrome, varices, and hepatic encephalopathy. A clinical approach to these complications of cirrhosis is presented. Progressive Familial Intrahepatic Cholestasis (PFIC) is a rare congenital metabolic abnormality. There are 3 subtypes and Type 3 PFIC commonly presents in late adolescence and early adulthood. Clinical and laboratory findings as well as management for the condition are described.

Morphological changes in the liver and kidneys of rats subjected to terminal ileum exclusion during obstructive cholestasis

PURPOSE

To investigate the effects of ileal exclusion on hepatic and renal morphology in extra-hepatic cholestasis.

METHODS

Twenty four rats were distributed into three groups. Group 1 (control) underwent laparotomy and laparorrhaphy. The animals in groups 2 and 3 underwent hepatic duct ligature and kept in cholestasis for four weeks. After this period, the rats in groups 2 and 3 underwent internal biliary derivation. In Group 3, the last ten centimeters of the terminal ileum were by passed and excluded. Four weeks later, histological and biochemical analysis were performed in all animals of the three groups.

RESULTS

In Group 1, no abnormalities regarding hepatic morphology were observed. All animals from groups 2 and 3 presented hepatic fibrosis. No difference was observed between the two groups. No morphological differences in renal histology could be identified among the three groups. There were differences in AST (p<0.05), ALT (p<0.05), direct bilirubin (p<0.05), ƔGT (p<0.05), urea (p<0.05) and creatinine (p<0.05) in Group 3 compared to control.

CONCLUSION

The distal ileum exclusion had no influence upon the hepatic and renal morphological alterations, and biochemical liver and kidney tests have worsened.

Protein kinase Cδ protects against bile acid apoptosis by suppressing proapoptotic JNK and BIM pathways in human and rat hepatocytes

Retained bile acids, which are capable of inducing cell death, activate protein kinase Cδ (PKC-δ) in hepatocytes. In nonhepatic cells, both pro- and antiapoptotic effects of PKC-δ are described. The aim of this study was to determine the role of PKC-δ in glycochenodeoxycholate (GCDC)-induced apoptosis in rat hepatocytes and human HUH7-Na-taurocholate-cotransporting polypeptide (Ntcp) cells. Apoptosis was monitored morphologically by Hoechst staining and biochemically by immunoblotting for caspase 3 cleavage. The role of PKC-δ was evaluated with a PKC activator (phorbol myristate acetate, PMA) and PKC inhibitors (chelerythrine, H-7, or calphostin), PKC-δ knockdown, and wild-type (WT) or constitutively active (CA) PKC-δ. PKC-δ activation was monitored by immunoblotting for PKC-δ Thr505 and Tyr311 phosphorylation or by membrane translocation. JNK and Akt phosphorylation and the amount of total bisindolylmaleimide (BIM) were determined by immunoblotting. GCDC induced the translocation of PKC-δ to the mitochondria and/or plasma membrane in rat hepatocytes and HUH7-Ntcp cells and increased PKC-δ phosphorylation on Thr505, but not on Tyr311, in HUH7-Ntcp cells. GCDC-induced apoptosis was attenuated by PMA and augmented by PKC inhibition in rat hepatocytes. In HUH-Ntcp cells, transfection with CA or WT PKC-δ attenuated GCDC-induced apoptosis, whereas knockdown of PKC-δ increased GCDC-induced apoptosis. PKC-δ silencing increased GCDC-induced JNK phosphorylation, decreased GCDC-induced Akt phosphorylation, and increased expression of BIM. GCDC translocated BIM to the mitochondria in rat hepatocytes, and knockdown of BIM in HUH7-Ntcp cells decreased GCDC-induced apoptosis. Collectively, these results suggest that PKC-δ does not mediate GCDC-induced apoptosis in hepatocytes. Instead PKC-δ activation by GCDC stimulates a cytoprotective pathway that involves JNK inhibition, Akt activation, and downregulation of BIM.

Phospholipid flippase activities and substrate specificities of human type IV P-type ATPases localized to the plasma membrane

Type IV P-type ATPases (P4-ATPases) are believed to translocate aminophospholipids from the exoplasmic to the cytoplasmic leaflets of cellular membranes. The yeast P4-ATPases, Drs2p and Dnf1p/Dnf2p, flip nitrobenzoxadiazole-labeled phosphatidylserine at the Golgi complex and nitrobenzoxadiazole-labeled phosphatidylcholine (PC) at the plasma membrane, respectively. However, the flippase activities and substrate specificities of mammalian P4-ATPases remain incompletely characterized. In this study, we established an assay for phospholipid flippase activities of plasma membrane-localized P4-ATPases using human cell lines stably expressing ATP8B1, ATP8B2, ATP11A, and ATP11C. We found that ATP11A and ATP11C have flippase activities toward phosphatidylserine and phosphatidylethanolamine but not PC or sphingomyelin. By contrast, ATPase-deficient mutants of ATP11A and ATP11C did not exhibit any flippase activity, indicating that these enzymes catalyze flipping in an ATPase-dependent manner. Furthermore, ATP8B1 and ATP8B2 exhibited preferential flippase activities toward PC. Some ATP8B1 mutants found in patients of progressive familial intrahepatic cholestasis type 1 (PFIC1), a severe liver disease caused by impaired bile flow, failed to translocate PC despite their delivery to the plasma membrane. Moreover, incorporation of PC mediated by ATP8B1 can be reversed by simultaneous expression of ABCB4, a PC floppase mutated in PFIC3 patients. Our findings elucidate the flippase activities and substrate specificities of plasma membrane-localized human P4-ATPases and suggest that phenotypes of some PFIC1 patients result from impairment of the PC flippase activity of ATP8B1.

Outcome of partial internal biliary diversion for intractable pruritus in children with cholestatic liver disease

PURPOSE

Children with cholestatic disorders have undergone liver transplantation for intractable pruritus unresponsive to medical therapy even in the absence of liver failure. Biliary diversion procedures interrupt the entero-hepatic circulation of bile acids allowing them to be excreted in the feces thereby lowering the total bile acid pool. We evaluated the outcome of partial internal biliary diversion (PIBD) in children with intractable pruritus from inherited cholestatic disorders.

METHODS

The records of children who underwent PIBD over a 4-year period were reviewed for etiology of liver disease, demographic data, preoperative and postoperative biochemical profile and improvement of pruritus. Standard statistical methods were used for analysis.

RESULTS

Of the 12 children, 10 had progressive familial intrahepatic cholestasis (PFIC) and 2 had Alagille syndrome (AS). PIBD was done using an isolated jejunal loop as a conduit from gall bladder to mid ascending colon. Median period of follow up was 30 months. Pruritus resolved in nine children with significant reduction of serum bile acids (P < 0.02).

CONCLUSION

To our knowledge, this is the largest reported series of children with PIBD. PIBD is a safe, well-tolerated and effective alternative to liver transplant in children with PFIC and AS who have intractable pruritus in the absence of synthetic liver failure.

Amyloid goiter due to familial mediterranean Fever in a patient with byler syndrome: a case report

BACKGROUND

Familial Mediterranean Fever (FMF), also inherited with autosomal recessive trait, is characterized by recurrent episodes of fever, arthritis, and serositis. Congenital Byler Syndrome (Progressive Familial Intrahepatic Cholestasis) inherited with autosomal recessive trait and characterized by defective secretion of bile acids. FMF associated Amyloid A deposition occurs in many tissues and organs, but amyloid goiter is a rare entity that leads to enlargement and dysfunction of the thyroid.

CASE REPORT

We present a rare case of 24 year old male patient who had liver and kidney transplantation due to Byler Syndrome and secondary amyloidosis related to FMF, diagnosed as rapidly growing large amyloid goiter. Deposits of extracellular amyloid and dense adipose metaplasia diagnostic for amyloid goiter are determined upon histopathological examination of thyroidectomy material.

CONCLUSION

When goiter was detected in cases with history of systemic amyloidosis and rapidly growing goitre, amyloid goiter should be remembered at first. This case is unique since two autosomal genetic disorders are together in the same patient and important as it emphasizes the consequences of consanguineous marriage, early diagnosis and treatment compliance of FMF and the awareness of amyloid goiter in patients followed by primary care physicians and healthcare professionals.

Atypical causes of cholestasis

Cholestatic liver disease consists of a variety of disorders. Primary sclerosing cholangitis and primary biliary cirrhosis are the most commonly recognized cholestatic liver disease in the adult population, while biliary atresia and Alagille syndrome are commonly recognized in the pediatric population. In infants, the causes are usually congenital or inherited. Even though jaundice is a hallmark of cholestasis, it is not always seen in adult patients with chronic liver disease. Patients can have “silent” progressive cholestatic liver disease for years prior to development of symptoms such as jaundice and pruritus. In this review, we will discuss some of the atypical causes of cholestatic liver disease such as benign recurrent intrahepatic cholestasis, progressive familial intrahepatic cholestasis, Alagille Syndrome, biliary atresia, total parenteral nutrition induced cholestasis and cholestasis secondary to drug induced liver injury.

Biosynthesis and trafficking of the bile salt export pump, BSEP: therapeutic implications of BSEP mutations

The bile salt export pump (BSEP, ABCB11) is the primary transporter of bile acids from the hepatocyte to the biliary system. This rate-limiting step in bile formation is essential to the formation of bile salt dependent bile flow, the enterohepatic circulation of bile acids, and the digestion of dietary fats. Mutations in BSEP are associated with cholestatic diseases such as progressive familial intrahepatic cholestasis type 2 (PFIC2), benign recurrent intrahepatic cholestasis type 2 (BRIC2), drug-induced cholestasis, and intrahepatic cholestasis of pregnancy. Development of clinical therapies for these conditions necessitates a clear understanding of the cell biology of biosynthesis, trafficking, and transcriptional and translational regulation of BSEP. This chapter will focus on the molecular and cell biological aspects of this critical hepatic membrane transporter.

Massive gene amplification drives paediatric hepatocellular carcinoma caused by bile salt export pump deficiency

Hepatocellular carcinoma (HCC) is almost invariably associated with an underlying inflammatory state, whose direct contribution to the acquisition of critical genomic changes is unclear. Here we map acquired genomic alterations in human and mouse HCCs induced by defects in hepatocyte biliary transporters, which expose hepatocytes to bile salts and cause chronic inflammation that develops into cancer. In both human and mouse cancer genomes, we find few somatic point mutations with no impairment of cancer genes, but massive gene amplification and rearrangements. This genomic landscape differs from that of virus- and alcohol-associated liver cancer. Copy-number gains preferentially occur at late stages of cancer development and frequently target the MAPK signalling pathway, and in particular direct regulators of JNK. The pharmacological inhibition of JNK retards cancer progression in the mouse. Our study demonstrates that intrahepatic cholestasis leading to hepatocyte exposure to bile acids and inflammation promotes cancer through genomic modifications that can be distinguished from those determined by other aetiological factors.

Management of adults with paediatric-onset chronic liver disease: strategic issues for transition care

Advances in the management of children with chronic liver disease have enabled many to survive into adulthood with or without their native livers, so that the most common of these conditions are becoming increasingly common in adult hepatology practice. Because the aetiologies of chronic liver disease in children may vary significantly from those in adulthood, adults with paediatric-onset chronic liver disease may often present with clinical manifestations unfamiliar to their adulthood physician. Transition of medical care to adult practice requires that the adulthood medical staff (primary physicians and subspecialists) have a comprehensive knowledge of childhood liver disease and their implications, and of the differences in caring for these patients. Pending still unavailable Scientific Society guidelines, this article examines causes, presentation modes, evaluation, management, and complications of the main paediatric-onset chronic liver diseases, and discusses key issues to aid in planning a program of transition from paediatric to adult patients.

Progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) is a group of rare disorders which are caused by defect in bile secretion and present with intrahepatic cholestasis, usually in infancy and childhood. These are autosomal recessive in inheritance. The estimated incidence is about 1 per 50,000 to 1 per 100,000 births, although exact prevalence is not known. These diseases affect both the genders equally and have been reported from all geographical areas. Based on clinical presentation, laboratory findings, liver histology and genetic defect, these are broadly divided into three types-PFIC type 1, PFIC type 2 and PFIC type 3. The defect is in ATP8B1 gene encoding the FIC1 protein, ABCB 11 gene encoding BSEP protein and ABCB4 gene encoding MDR3 protein in PFIC1, 2 and 3 respectively. The basic defect is impaired bile salt secretion in PFIC1/2 whereas in PFIC3, it is reduced biliary phospholipid secretion. The main clinical presentation is in the form of cholestatic jaundice and pruritus. Serum gamma glutamyl transpeptidase (GGT) is normal in patients with PFIC1/2 while it is raised in patients with PFIC3. Treatment includes nutritional support (adequate calories, supplementation of fat soluble vitamins and medium chain triglycerides) and use of medications to relieve pruritus as initial therapy followed by biliary diversion procedures in selected patients. Ultimately liver transplantation is needed in most patients as they develop progressive liver fibrosis, cirrhosis and end stage liver disease. Due to the high risk of developing liver tumors in PFIC2 patients, monitoring is recommended from infancy. Mutation targeted pharmacotherapy, gene therapy and hepatocyte transplantation are being explored as future therapeutic options.

Therapeutic hepatocyte transplant for inherited metabolic disorders: functional considerations, recent outcomes and future prospects

The applications, outcomes and future strategies of hepatocyte transplantation (HTx) as a corrective intervention for inherited metabolic disease (IMD) are described. An overview of HTx in IMDs, as well as preclinical evaluations in rodent and other mammalian models, is summarized. Current treatments for IMDs are highlighted, along with short- and long-term outcomes and the potential for HTx to supplement or supplant these treatments. Finally, the advantages and disadvantages of HTx are presented, highlighted by long-term challenges with interorgan engraftment and expansion of transplanted cells, in addition to the future prospects of stem cell transplants. At present, the utility of HTx is represented by the potential to bridge patients with life-threatening liver disease to organ transplantation, especially as an adjuvant intervention where severe organ shortages continue to pose challenges.

The role of canalicular ABC transporters in cholestasis

Cholestasis, a hallmark feature of hepatobiliary disease, is characterized by the retention of biliary constituents. Some of these constituents, such as bile acids, inflict damage to hepatocytes and bile duct cells. This damage may lead to inflammation, fibrosis, cirrhosis, and eventually carcinogenesis, sequelae that aggravate the underlying disease and deteriorate clinical outcome. Canalicular ATP-binding cassette (ABC) transporters, which mediate the excretion of individual bile constituents, play a key role in bile formation and cholestasis. The study of these transporters and their regulatory nuclear receptors has revolutionized our understanding of cholestatic disease. This knowledge has served as a template to develop novel treatment strategies, some of which are currently already undergoing phase III clinical trials. In this review we aim to provide an overview of the structure, function, and regulation of canalicular ABC transporters. In addition, we will focus on the role of these transporters in the pathogenesis and treatment of cholestatic bile duct and liver diseases.

Diversity of disorders causing neonatal cholestasis - the experience of a tertiary pediatric center in Germany

BACKGROUND AND OBJECTIVE

Rapidly establishing the cause of neonatal cholestasis is an urgent matter. The aim of this study was to report on the prevalence and mortality of the diverse disorders causing neonatal cholestasis in an academic center in Germany.

METHODS

Clinical chemistry and cause of disease were retrospectively analyzed in 82 infants (male n = 42, 51%) that had presented with neonatal cholestasis to a tertiary medical center from January 2009 to April 2013.

RESULTS

Altogether, 19 disorders causing neonatal cholestasis were identified. Biliary atresia was the most common diagnosis (41%), followed by idiopathic cases (13%), progressive familial intrahepatic cholestasis (PFIC, 10%), cholestasis in preterm infants (10%), α1AT deficiency, Alagille syndrome, portocaval shunts, mitochondriopathy, biliary sludge (all 2%), and others. Infants with biliary atresia were diagnosed with a mean age of 62 days, they underwent Kasai portoenterostomy ~66 days after birth. The majority of these children (~70%) received surgery within 10 weeks of age and 27% before 60 days. The 2-year survival with their native liver after Kasai procedure was 12%. The time span between Kasai surgery and liver transplantation was 176 ± 73 days. Six children (7%), of whom three patients had a syndromic and one a non-syndromic biliary atresia, died prior to liver transplantation. The pre- and post-transplant mortality rate for children with biliary atresia was ~12 and ~17%, respectively.

CONCLUSION

Neonatal cholestasis is a severe threat associated with a high risk of complications in infancy and it therefore requires urgent investigation in order to initiate life saving therapy. Although in the last 20 years new causes such as the PFICs have been identified and newer diagnostic tools have been introduced into the clinical routine biliary atresia still represents the major cause.

Sodium-dependent bile salt transporters of the SLC10A transporter family: more than solute transporters

The SLC10A transporter gene family consists of seven members and substrates transported by three members (SLC10A1, SLC10A2 and SLC10A6) are Na(+)-dependent. SLC10A1 (sodium taurocholate cotransporting polypeptide [NTCP]) and SLC10A2 (apical sodium-dependent bile salt transporter [ASBT]) transport bile salts and play an important role in maintaining enterohepatic circulation of bile salts. Solutes other than bile salts are also transported by NTCP. However, ASBT has not been shown to be a transporter for non-bile salt substrates. While the transport function of NTCP can potentially be used as liver function test, interpretation of such a test may be complicated by altered expression of NTCP in diseases and presence of drugs that may inhibit NTCP function. Transport of bile salts by NTCP and ASBT is inhibited by a number of drugs and it appears that ASBT is more permissive to drug inhibition than NTCP. The clinical significance of this inhibition in drug disposition and drug-drug interaction remains to be determined. Both NCTP and ASBT undergo post-translational regulations that involve phosphorylation/dephosphorylation, translocation to and retrieval from the plasma membrane and degradation by the ubiquitin-proteasome system. These posttranslational regulations are mediated via signaling pathways involving cAMP, calcium, nitric oxide, phosphoinositide-3-kinase (PI3K), protein kinase C (PKC) and protein phosphatases. There appears to be species difference in the substrate specificity and the regulation of plasma membrane localization of human and rodent NTCP. These differences should be taken into account when extrapolating rodent data for human clinical relevance and developing novel therapies. NTCP has recently been shown to play an important role in HBV and HDV infection by serving as a receptor for entry of these viruses into hepatocytes.

Sodium-dependent bile salt transporters of the SLC10A transporter family: more than solute transporters

The SLC10A transporter gene family consists of seven members and substrates transported by three members (SLC10A1, SLC10A2 and SLC10A6) are Na(+)-dependent. SLC10A1 (sodium taurocholate cotransporting polypeptide [NTCP]) and SLC10A2 (apical sodium-dependent bile salt transporter [ASBT]) transport bile salts and play an important role in maintaining enterohepatic circulation of bile salts. Solutes other than bile salts are also transported by NTCP. However, ASBT has not been shown to be a transporter for non-bile salt substrates. While the transport function of NTCP can potentially be used as liver function test, interpretation of such a test may be complicated by altered expression of NTCP in diseases and presence of drugs that may inhibit NTCP function. Transport of bile salts by NTCP and ASBT is inhibited by a number of drugs and it appears that ASBT is more permissive to drug inhibition than NTCP. The clinical significance of this inhibition in drug disposition and drug-drug interaction remains to be determined. Both NCTP and ASBT undergo post-translational regulations that involve phosphorylation/dephosphorylation, translocation to and retrieval from the plasma membrane and degradation by the ubiquitin-proteasome system. These posttranslational regulations are mediated via signaling pathways involving cAMP, calcium, nitric oxide, phosphoinositide-3-kinase (PI3K), protein kinase C (PKC) and protein phosphatases. There appears to be species difference in the substrate specificity and the regulation of plasma membrane localization of human and rodent NTCP. These differences should be taken into account when extrapolating rodent data for human clinical relevance and developing novel therapies. NTCP has recently been shown to play an important role in HBV and HDV infection by serving as a receptor for entry of these viruses into hepatocytes.

Detergent screening and purification of the human liver ABC transporters BSEP (ABCB11) and MDR3 (ABCB4) expressed in the yeast Pichia pastoris

The human liver ATP-binding cassette (ABC) transporters bile salt export pump (BSEP/ABCB11) and the multidrug resistance protein 3 (MDR3/ABCB4) fulfill the translocation of bile salts and phosphatidylcholine across the apical membrane of hepatocytes. In concert with ABCG5/G8, these two transporters are responsible for the formation of bile and mutations within these transporters can lead to severe hereditary diseases. In this study, we report the heterologous overexpression and purification of human BSEP and MDR3 as well as the expression of the corresponding C-terminal GFP-fusion proteins in the yeast Pichia pastoris. Confocal laser scanning microscopy revealed that BSEP-GFP and MDR3-GFP are localized in the plasma membrane of P. pastoris. Furthermore, we demonstrate the first purification of human BSEP and MDR3 yielding ∼1 mg and ∼6 mg per 100 g of wet cell weight, respectively. By screening over 100 detergents using a dot blot technique, we found that only zwitterionic, lipid-like detergents such as Fos-cholines or Cyclofos were able to extract both transporters in sufficient amounts for subsequent functional analysis. For MDR3, fluorescence-detection size exclusion chromatography (FSEC) screens revealed that increasing the acyl chain length of Fos-Cholines improved monodispersity. BSEP purified in n-dodecyl-β-D-maltoside or Cymal-5 after solubilization with Fos-choline 16 from P. pastoris membranes showed binding to ATP-agarose. Furthermore, detergent-solubilized and purified MDR3 showed a substrate-inducible ATPase activity upon addition of phosphatidylcholine lipids. These results form the basis for further biochemical analysis of human BSEP and MDR3 to elucidate the function of these clinically relevant ABC transporters.

Immunohistochemical profile of ezrin and radixin in human liver epithelia during fetal development and pediatric cholestatic diseases

AIM

Ezrin and radixin are actin-binding proteins that contribute to the integrity of epithelia. Abnormalities of bile secretion occur primarily in cholestatic liver diseases and are associated with changes in cell cytoskeleton. Expression of these proteins during liver development and in cholestatic liver diseases remains poorly investigated.

METHODS

Ezrin and radixin expression was analyzed in fetal, adult and pediatric cholestatic human liver (i.e. biliary atresia, sclerosing cholangitis) by immunohistochemistry.

RESULTS

In adult and fetal livers, ezrin was expressed exclusively in the cells of the biliary lineage (i.e. biliary epithelial cells and ductal cells) whereas radixin was located not only in hepatocytes but also in cells of the biliary lineage. In the lobule of mature livers, radixin displayed a zonal distribution with predominant expression in the periportal region. In cholestatic diseases, both proteins were expressed in cells of the ductular reaction. An aberrant expression of ezrin was detected in hepatocytes of cirrhotic nodules with a CK7-positive pattern and in malignant hepatocytes in a course of cholestatic disease toward cancer.

CONCLUSIONS

Among the components of the liver epithelial cells, ezrin was exclusively expressed in biliary phenotype cells, while radixin was found in biliary and hepatocytic lineages, with a periportal zonal expression. In cholestatic diseases, ezrin was expressed in hepatocytes supporting the appearance of a biliary phenotype.