Successful pregnancy after ileal exclusion in progressive familial intrahepatic cholestasis type 2

Progressive familial intrahepatic cholestasis type 2 (PFIC 2) results from mutations in ABCB11 gene coding bile salt export pump (BSEP). Medical treatment is usually unsuccessful and surgery intervention is necessary. Partial external biliary diversion (PEBD) is regarded as the first choice of surgical treatment. Ileal exclusion (IE) is an alternative operation if external stoma is not tolerated; however, a favorable outcome is uncertain. In chronic liver diseases pregnancy brings additional risk of deterioration of liver function and generally is not recommended. We present the first case report of successful pregnancy in a genetically confirmed PFIC 2 patient after surgical conversion from PEBD to IE.     

Atp8b1 deficiency in mice reduces resistance of the canalicular membrane to hydrophobic bile salts and impairs bile salt transport

Progressive familial intrahepatic cholestasis type 1 (PFIC1, Byler disease, OMIM 211600) is a severe inherited liver disease caused by mutations in ATP8B1. ATP8B1 is a member of the type 4 subfamily of P-type ATPases, which are phospholipid flippases. PFIC1 patients generally develop end-stage liver disease before the second decade of life. The disease is characterized by impaired biliary bile salt excretion, but the mechanism whereby impaired ATP8B1 function results in cholestasis is unclear. In a mouse model for PFIC1, we observed decreased resistance of the hepatocanalicular membrane to hydrophobic bile salts as evidenced by enhanced biliary recovery of phosphatidylserine, cholesterol, and ectoenzymes. In liver specimens from PFIC1 patients, but not in those from control subjects, ectoenzyme expression at the canalicular membrane was markedly deficient. In isolated mouse livers Atp8b1 deficiency impaired the transport of hydrophobic bile salts into bile. In conclusion, our study shows that Atp8b1 deficiency causes loss of canalicular phospholipid membrane asymmetry that in turn renders the canalicular membrane less resistant toward hydrophobic bile salts. The loss of phospholipid asymmetry may subsequently impair bile salt transport and cause cholestasis.     

Hepatocanalicular bile salt export pump deficiency in patients with progressive familial intrahepatic cholestasis

BACKGROUND & AIMS: Progressive familial intrahepatic cholestasis (PFIC), an inherited liver disease of childhood, is characterized by cholestasis and either normal or increased serum gamma-glutamyltransferase activity. Patients with normal gamma-glutamyltransferase activity have mutations of the FIC1 locus on chromosome 18q21 or mutations of the BSEP gene on chromosome 2q24. Also, patients with bile acid synthesis defects have low gamma-glutamyltransferase activity. We investigated expression of the bile salt export pump (BSEP) in liver samples from patients with a PFIC phenotype and correlated this with BSEP gene mutations. METHODS: BSEP and multidrug resistance protein 2 (MRP2) expressions were studied by immunohistochemistry in liver specimens of 28 patients and BSEP gene mutation analysis in 19 patients. Bile salt kinetics were studied in 1 patient. RESULTS: Sixteen of 28 liver samples showed no canalicular BSEP staining. Staining for MRP2 showed a normal canalicular pattern in all but 1 of these samples. Ten of 19 patients showed BSEP gene mutations; BSEP protein expression was lacking in all 10 patients. No mutations were found in 9 of 19 patients, and in all except 1, BSEP protein expression was normal. Bile salt concentration in bile of BSEP-negative/MRP2-positive PFIC patients was 0.2 +/- 0.2 mmol/L (n = 9; <1% of normal) and in BSEP-positive PFIC patients 18.1 +/- 9.9 mmol/L (n = 3; 40% of normal). The kinetic study confirmed the dramatic decrease of bile salt secretion in BSEP-negative patients. CONCLUSIONS: The findings show a close correlation between BSEP gene mutations and canalicular BSEP expression. Biliary secretion of bile salts is greatly reduced in BSEP-negative patients.     

Progressive familial intrahepatic cholestasis: A case with improvement in liver tests and growth following partial external biliary diversion

A 2½-year-old boy presented with pruritus and jaundice of 2 weeks duration. On investigation, serum total bilirubin was 23.4 mg/dL and gamma glutamyl transpeptidase was normal. Liver biopsy was consistent with progressive familial intrahepatic cholestasis (PFIC). A partial external biliary diversion (PEBD) was done. Pruritus disappeared, growth improved and serum total bilirubin became normal, 2 months after surgery. This is the first report from India, of PFIC treated with PEBD and suggests that PEBD should be considered in patients with PFIC even if bridging fibrosis is present.     

Progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC), also known as Byler disease, is an inherited disorder of childhood in which cholestasis of hepatocellular origin often presents in the neonatal period and leads to death from liver failure before adolescence. The pattern of appearance of affected children within families is consistent with autosomal recessive inheritance. Several studies have provided support for the heterogeneity of this clinical entity suggesting the existence of different types due to different disorders affecting the hepatocyte and related to defects of bile acid secretion or bile acid metabolism. Recent molecular and genetic studies have identified genes responsible for three types of PFIC and have shown that PFIC was related to mutations in hepatocellular transport system genes involved in bile formation. These findings now provide specific diagnostic tools for the investigation of children with PFIC and should allow prenatal diagnosis in the future. Genotype-phenotype correlations performed in patients treated with ursodeoxycholic acid or biliary diversion should allow those PFIC patients who could benefit from these therapies to be precisely identified. In the future, other therapies, such as cell and gene therapies, might be considered and could also represent an alternative to liver transplantation.     

Fifteen years single center experience in the management of progressive familial intrahepatic cholestasis of infancy

Recent advances in genetics and in physiopathology of bile composition and excretion have clarified the understanding of progressive familial intrahepatic cholestasis (PFIC). The aim of the present study is to review the experience of our center in terms of diagnosis, management and outcome of 49 pediatric PFIC patients, belonging to the three classical subtypes described. We analyse the clinical, biological, and histological patterns and review the response to the medical and surgical treatment and the global outcome. The only clinical difference between the different subtypes of PFIC patients was the intensity of pruritus. Serum gamma-glutamyltransferase (GGT) and liver histology allowed to differentiate PFIC III from PFIC I and II patients. High levels of biliary bile acids in 2 low-GGT patients was associated with favourable outcome. Response to ursodeoxycholic acid (UDCA) varies from patient to patient and was not associated to a particular subtype of PFIC. In five patients of this cohort, external biliary diversion was performed without improvement. Transplantation is indicated whenever medical treatment fails to restore normal social life, growth and well being of the child and it is associated with excellent survival (> 90%).     

Partial Internal Biliary Diversion: A Solution for Intractable Pruritus in Progressive Familial Intrahepatic Cholestasis Type 1

Biliary diversion offers a potential option for intractable pruritus in children with chronic cholestatic disorders. Progressive familial intrahepatic cholestasis (PFIC) is an inherited disorder of impaired bile acid transport and excretion, which presents with jaundice and pruritus in the first few months of life and progresses to cirrhosis by infancy or adolescence. We report a child with PFIC type 1 who underwent internal biliary diversion for intractable pruritus and was relieved of his symptoms.     

Cholestatic liver diseases: slow progress in understanding and treating slowly progressive disorders

BACKGROUND: Cholestatic liver diseases are characterized by failure of normal amounts of physiological bile to reach the gastrointestinal tract. Any interference with normal bile flow from the canalicular membrane of the hepatocyte to the distal common bile duct may result in cholestasis. METHODS: Literature review. RESULTS: In primary biliary cirrhosis (PBC), the small intrahepatic bile ducts are destructed, resulting in obstruction of intrahepatic bile flow, whereas extrahepatic and/or intrahepatic biliary strictures block the passage of bile towards the intestine in primary sclerosing cholangitis (PSC). In contrast, the biliary tree is morphologically unaffected in less common cholestatic liver diseases as benign recurrent intrahepatic cholestasis (BRIC) and progressive familiar intrahepatic cholestasis (PFIC1-4). Genetic defects in hepatic canalicular transport mechanisms and bile salt synthesis deficiencies seem to underlie these types of cholestatic disorders. CONCLUSION: Recent advances in understanding and treatment of cholestatic liver diseases may help in better diagnosing and treating the various conditions characterized by cholestasis.     

Progressive familial intrahepatic cholestasis and inborn errors of bile acid synthesis

Progressive familial intrahepatic cholestasis (PFIC), types 1, 2 and 3, are due to defects in genes involved in bile secretion (FIC1, BSEP, MDR3). PFIC and inborn errors of bile acid synthesis (IEBAS) often present in infancy with cholestasis. The distinctive feature of PFIC 1 and 2 and IEBAS is a normal level of GGT, while IEBAS are suspected in patients with low plasma bile acids concentration. Molecular testing, urinary bile acid analysis (IEBAS), liver biopsy and immuno-staining are used for the diagnosis. Some patients with PFIC can be successfully treated with ursodeoxycholic acid or partial external biliary diversion. IEBAS is treated with cholic acid. Liver transplantation is required for cirrhosis with liver failure. Hepatocarcinoma has been reported in PFIC2.     

Targeted inactivation of sister of P-glycoprotein gene (spgp) in mice results in nonprogressive but persistent intrahepatic cholestasis

Mutations in the sister of P-glycoprotein (Spgp) or bile salt export pump (BSEP) are associated with Progressive Familial Intrahepatic Cholestasis (PFIC2). Spgp is predominantly expressed in the canalicular membranes of liver. Consistent with in vitro evidence demonstrating the involvement of Spgp in bile salt transport, PFIC2 patients secrete less than 1% of biliary bile salts compared with normal infants. The disease rapidly progresses to hepatic failure requiring liver transplantation before adolescence. In this study, we show that the knockout of spgp gene in mice results in intrahepatic cholestasis, but with significantly less severity than PFIC2 in humans. Some unexpected characteristics are observed. Notably, although the secretion of cholic acid in mutant mice is greatly reduced (6% of wild-type), total bile salt output in mutant mice is about 30% of wild-type. Also, secretion of an unexpectedly large amount of tetra-hydroxylated bile acids (not detected in wild-type) is observed. These results suggest that hydroxylation and an alternative canalicular transport mechanism for bile acids compensate for the absence of Spgp function and protect the mutant mice from severe cholestatic damage. In addition, the spgp(-/-) mice display a significant increase in the secretion of cholesterol and phospholipids into the bile. This latter observation in spgp(-/-) mice suggests that intrahepatic, rather than intracanalicular, bile salts are the major driving force for the biliary lipid secretion. The spgp(-/-) mice thus provide a unique model for gaining new insights into therapeutic intervention for intrahepatic cholestasis and understanding mechanisms associated with lipid homeostasis.     

Recurrent intrahepatic cholestasis of pregnancy and chain-like choledocholithiasis in a female patient with stop codon in the ABDC4-gene of the hepatobiliary phospholipid transporter

We report the case of a 40-years-old female patient with recurrent cholestatic liver disease who presented twice with severe intrahepatic cholestasis of pregnancy and pronounced choledocholithiasis between pregnancies. Bile duct stones were removed endoscopically and a laparoscopic cholecystectomy was performed after the second pregnancy. Liver histology revealed intrahepatic cholestasis with portal inflammation and fibrosis, resembling progressive familial intrahepatic cholestasis (PFIC). Molecular genetic studies identified the heterozygous mutation c.957C > T in the ABCB4 gene encoding the hepatobiliary phospholipid transporter. This is the first report of this mutation that introduces a stop codon in an index patient with intrahepatic cholestasis of pregnancy and multiple bile duct stones. In addition, we detected the ABCB11 polymorphism V 444A, which is associated with a decreased expression of the bile salt export pump. Whereas homozygous carriers of the ABCB4 mutation develop PFIC type 3, the heterozygous ABC transporter mutations represent genetic risk factors for cholelithiasis and recurrent cholestatic hepatitis upon challenge with oral contraceptives or during pregnancy. Of note, the patient presented with normal serum gamma-glutamyltranspeptidase activities during pregnancy-associated cholestatic episodes but normal liver enzymes after delivery, whereas choledocholithiasis was associated with high gamma-glutamyl transpeptidase levels. It is unknown whether ursodeoxycholic acid prevents cholestasis or gallstones in patients with ABCB4 deficiency.     

FIC1, the protein affected in two forms of hereditary cholestasis, is localized in the cholangiocyte and the canalicular membrane of the hepatocyte.

BACKGROUND/AIMS: FIC1 (familial intrahepatic cholestasis 1) is affected in two clinically distinct forms of hereditary cholestasis, namely progressive familial intrahepatic cholestasis type 1 (PFIC1) and benign recurrent intrahepatic cholestasis. Here we examined the subcellular localization of this protein within the liver. METHODS: Antibodies raised against different epitopes of human FIC1 were used for immunoblot analysis and immunohistochemical detection of FICI. RESULTS: Immunoblot analysis of intestine and liver tissue extracts from human, rat and mouse origin indicated that the antibodies raised against FIC1 specifically detected FIC1 as a 140-kDa protein. In the liver homogenate of a PFIC1 patient, FIC1 could not be detected. Analysis of isolated rat liver membrane vesicles indicated that this protein is predominantly present in the canalicular membrane fraction. Immunohistochemical detection of the protein in liver sections confirmed that FIC1 was present in the canalicular membrane, whereas no staining was observed in the PFIC1 patients liver. Double label immunofluorescence of murine liver revealed that FIC1 colocalized with cytokeratin 7 in cholangiocytes. CONCLUSIONS: The localization of FIC1 in the canalicular membrane and cholangiocytes suggests that it may directly or indirectly play a role in bile formation since mutations in FICI are associated with severe symptoms of cholestasis.     

Hereditäre Defekte hepatobiliärer Transportproteine

Defects in transport proteins that are expressed at the hepatocyte canalicular membrane can cause severe impairment of hepatobiliary transport processes. Progressive familial intrahepatic cholestasis (PFIC) typically manifests in early childhood. Genetic variants in the aminophospholipid transporter FIC1 (ATP8B1 gene) cause PFIC1, characterized by elevated serum bile acids but normal or only mildly elevated gamma-GT levels. Benign recurrent intrahepatic cholestasis type 1 (BRIC1) is also caused by ATP8B1 mutations. Defects in the function of the bile salt efflux pump (BSEP; ABCB11) cause PFIC2 or BRIC2, depending on the degree of BSEP impairment. A common BSEP variant, the V444A polymorphism, is commonly found in various types of cholestatic liver injury, including drug-induced liver injury. Finally, dysfunction of the multidrug resistance gene product MDR3 (ABCB4) leads to PFIC3, characterized by low biliary phospholipids and high gamma-GT levels in serum due to bile duct injury. All three transporter genes are also associated with intrahepatic cholestasis of pregnancy. Treatment options include ursodeoxycholic acid for milder forms and liver transplantation for severe pediatric cases.     

Genetic cholestasis: lessons from the molecular physiology of bile formation.

Progressive familial intrahepatic cholestasis (PFIC) is a group of severe genetic cholestatic liver diseases of early life. PFIC types 1 and 2 are characterized by cholestasis and a low to normal serum gamma-glutamyltransferase (GGT) activity, whereas in PFIC type 3, the serum GGT activity is elevated. PFIC types 1 and 2 occur due to mutations in loci at chromosome 18 and chromosome 2, respectively. The pathophysiology of PFIC type 1 is not well understood. PFIC types 2 and 3 are caused by transport defects in the liver affecting the hepatobiliary secretion of bile acids and phospholipids, respectively. Benign recurrent intrahepatic cholestasis (BRIC) is linked to a mutation in the same familial intrahepatic cholestasis 1 locus at chromosome 18. Defects of bile acid synthesis may be difficult to differentiate from these transport defects. Intrahepatic cholestasis of pregnancy (ICP) appears to be related to these cholestatic diseases. For example, heterozygosity in families with PFIC type 3 is associated with ICP, but ICP has also been reported in families with BRIC. In Dubin-Johnson syndrome there is no cholestasis; only the hepatobiliary transport of conjugated bilirubin is affected. This, therefore, is a mild disease, and patients have a normal lifespan.     

Progressive familial intrahepatic cholestasis

BACKGROUND:Three types of progressive familial intrahepatic cholestasis(PFIC)have been identified,but their etiologies include unknown mechanisms. DATA SOURCES:A PubMed search on"progressive familial intrahepatic cholestasis"and"PFIC"was performed on the topic,and the relevant articles were reviewed. RESULTS:The etiologies of the three PFIC types still include unknown mechanisms.Especially in PFIC type 1,enterohepatic circulation of bile acid should be considered.Ursodeoxycholic acid,partial external biliary diversion and liver transplantation have been used for the treatment of PFIC patients according to disease course. CONCLUSIONS:Since the etiologies and disease mechanisms of PFIC are still unclear,detailed studies are urgently required. Strategies for more advanced therapies are also needed.These developments in the future are indispensable,especially for PFIC type 1 patients.     

The multiple facets of ABCB4 (MDR3) deficiency

Opinion statement ABCB4 (MDR3), a lipid translocator, moves phosphatidylcholine from the inner to the outer leaflet of the canalicular membrane. Genetic mutations of ABCB4 lead to three distinct but related hepatobiliary diseases. Progressive familial intrahepatic cholestasis (PFIC) type 3 is a chronic cholestatic syndrome characterized by a markedly elevated γ-glutamyltranspeptidase. Patients present with jaundice, pruritus, and hepatosplenomegaly. Periportal inflammation progresses to biliary cirrhosis and causes portal hypertension. Ursodeoxycholic acid (UDCA) normalizes liver function tests in approximately one half of treated PFIC type 3 patients. Partial responders or nonresponders eventually will require liver transplantation. Gallstone patients with ABCB4 mutations may have low phospholipid-associated cholelithiasis syndrome, characterized by cholesterol gallstones and intrahepatic microlithiasis, along with recurrent biliary symptoms, despite cholecystectomy. Patients with ABCB4 mutations also may develop intrahepatic brown pigment stones. UDCA may improve biliary symptoms even before the dissolution of stones occurs. Additional therapies such as farnesoid X receptor ligands/agonists and benzfibrates show future therapeutic promise. Intrahepatic cholestasis of pregnancy affects pregnant women with abnormal ABCB4. These women suffer from disabling pruritus and also may experience steatorrhea. Fetuses are at high risk for prematurity and stillbirths. The definitive treatment is delivery of the baby. In the interim, limited fat intake, fat-soluble vitamin supplementation, and UDCA with or without S-adenosylmethionine can provide symptomatic relief. Additional hepatobiliary diseases related to ABCB4 mutations are likely to be identified. This may result in the discovery of additional therapies for PFIC type 3, gallstones, and intrahepatic cholestasis of pregnancy.     

Advances in familial and congenital cholestatic diseases. Clinical and diagnostic implications

Recent progress in liver cell biology and molecular genetics revealed that a number of familial and congenital cholestatic disorders are caused by mutations in genes coding for hepatobiliary-transporter or for signalling proteins involved in morphogenesis. The status of the field is reviewed in the light of its impact on current diagnostic and clinical practice. The heterogeneous progressive familial intrahepatic cholestasis can now be separated into different genetic diseases. FIC1-defective progressive familial intrahepatic cholestasis (previously Byler disease) is determined by mutations in the FIC1 gene, coding for P-type ATPases of unknown physiological function, while a second form (bile salt export pump defective progressive familial intrahepatic cholestatis) is caused by a defective function of the canalicular bile salt export pump. Furthermore, a group of progressive familial intrahepatic cholestasis patients with high serum gamma glutamyltranspeptidase have mutations in the gene (PGY3) coding for the MDR3 protein, a canalicular ATP-dependent phopshatidylcholine translocator. Recurrent intrahepatic cholestasis (previously benign recurrent cholestasis), is also linked to specific mutations in the FIC1 gene. Finally, in Alagille syndrome, mutations in the JAG1 gene cause deficiency Jagged 1, a ligand for Notch 1, a receptor determining cell fate during early embryogenesis. Diagnosis of Alagille syndrome, a condition that should be suspected in all patients with unexplained cholestasis, will thus be confirmed by genetic analysis for mutations of JAG1. In children with cholestasis and low serum bile acid levels, an inborn error of bile acid synthesis should be excluded by urinary bile acid analysis by means of fast atom bombardment-ionization mass-spectrometry. In contrast, in children with cholestasis and high serum bile acid concentrations, a high serum gamma glutamyltranspeptidase value would indicate MDR3 deficiency, which should be excluded through biliary phospholipid determination and genetic analysis of PGY3 gene. Finally, in those children with cholestasis, high serum bile acids and low gamma glutamyltranspeptidase activity, analysis of mutation in FIC1 and bile salt export pump genes may lead to the diagnosis of progressive familial intrahepatic cholestasis either from bile salt export pump or FIC1 deficiency.     

Newer variants of progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of disorders characterized by defects in bile secretion and presentation with intrahepatic cholestasis in infancy or childhood. The most common types include PFIC 1 (deficiency of FIC1 protein, ATP8B1 gene mutation), PFIC 2 (bile salt export pump deficiency, ABCB11 gene mutation), and PFIC 3 (multidrug resistance protein-3 deficiency, ABCB4 gene mutation). Mutational analysis of subjects with normal gamma-glutamyl transferase cholestasis of unknown etiology has led to the identification of newer variants of PFIC, known as PFIC 4, 5, and MYO5B related (sometimes known as PFIC 6). PFIC 4 is caused by the loss of function of tight junction protein 2 (TJP2) and PFIC 5 is due to NR1H4 mutation causing Farnesoid X receptor deficiency. MYO5B gene mutation causes microvillous inclusion disease (MVID) and is also associated with isolated cholestasis. Children with TJP2 related cholestasis (PFIC-4) have a variable spectrum of presentation. Some have a self-limiting disease, while others have progressive liver disease with an increased risk of hepatocellular carcinoma. Hence, frequent surveillance for hepatocellular carcinoma is recommended from infancy. PFIC-5 patients usually have rapidly progressive liver disease with early onset coagulopathy, high alpha-fetoprotein and ultimately require a liver transplant. Subjects with MYO5 B-related disease can present with isolated cholestasis or cholestasis with intractable diarrhea (MVID). These children are at risk of worsening cholestasis post intestinal transplant (IT) for MVID, hence combined intestinal and liver transplant or IT with biliary diversion is preferred. Immunohistochemistry can differentiate most of the variants of PFIC but confirmation requires genetic analysis.     

Partial external biliary diversion in bile salt export pump deficiency: Association between outcome and mutation

AIM To investigate the relation of two different mutations to the outcome of partial external biliary diversion(PEBD)in severe bile salt export pump(BSEP) deficiency.METHODS Mutations in the gene encoding BSEP leading to severe BSEP deficiency in two unrelated patients were identified by genomic sequencing. Native liver biopsies and transiently transfected human embryonic kidney(HEK) 293 cells expressing either wild-type or mutated BSEP were subjected to immunofluorescence analysis to assess BSEP transporter localization. Bile acid profiles of patient and control bile samples were generated by ultra-performance liquid chromatographytandem mass spectrometry. Wild-type and mutant BSEP transport of [~3H]-labeled taurocholate(TC) and taurochenodeoxycholate(TCDC) was assessed by vesicular transport assays.RESULTS A girl(at 2 mo) presented with pruritus, jaundice and elevated serum bile salts(BS). PEBD stabilized liver function and prevented liver transplantation. She was heterozygous for the BSEP deletion p.T919 del and the nonsense mutation p.R1235 X. At the age of 17 years relative amounts of conjugated BS in her bile were normal, while total BS were less than 3% as compared to controls. An unrelated boy(age 1.5 years) presenting with severe pruritus and elevated serum BS was heterozygous for the same nonsense and another missense mutation, p.G1032 R. PEBD failed to alleviate pruritus, eventually necessitating liver transplantation. BS concentration in bile was about 5% of controls. BS were mainly unconjugated with an unusual low amount of chenodeoxycholate derivatives( 5%). The patients' native liver biopsies showed canalicular BSEP expression. Both BSEP p.T919 del and p.G1032 R were localized in the plasma membrane in HEK293 cells. In vitro transport assays showed drastic reduction of transport by both mutations. Using purified recombinant BSEP as quantifiable reference, per-molecule transport rates for TC and TCDC were determined to be 3 and 2 BS molecules per wild-type BSEP transporter per minute, respectively.CONCLUSION In summary, our findings suggest that residual function of BSEP as well as substrate specificity influence the therapeutic effectiveness of PEBD in progressive familial intrahepatic cholestasis type 2(PFIC-2).