Long-term outcome after partial external biliary diversion for intractable pruritus in patients with intrahepatic cholestasis

Treatment of the pruritus of cholestasis

The etiology of the pruritus of cholestasis is unknown. It is inferred that the pruritogen(s) is produced in the liver, excreted in bile, and as a result of cholestasis it accumulates in plasma. It may follow, logically, that the removal of the substance(s) that mediate pruritus leads to its resolution. The problem with this approach, however, is that the substance(s) is unknown; thus, it is not possible to reduce its serum levels specifically. Oral cholestyramine, a resin that is not absorbed, is associated with increased fecal excretion of certain substances, including cholesterol and bile acids. Many patients respond to treatment with cholestyramine with a relief of pruritus, which unfortunately may be temporary, but is well tolerated in general and it seems reasonable to prescribe it as an initial therapy. When pruritus is not relieved by resins, the use of opiate antagonists (eg, naloxone and naltrexone) is supported by data from controlled clinical trials. Butorphanol is an agonist at the kappa opioid receptor and an antagonist at the mu opioid receptor with minimal or absent abuse potential. The use of butorphanol spray in selective patients may be a therapeutic alternative. In uncontrolled observations dronabinol, an agonist at the cannabinoid B1 receptor, and sertraline, a serotonin reuptake inhibitor, have been reported to be associated with the relief of pruritus. The cannabinoidergic and serotoninergic systems participate in the mediation of nociception; therefore, there appears to be a rationale for the use of these drugs to treat pruritus. Data from controlled clinical trials on the use of dronabinol and sertraline, however, are not available at present.

Progressive intrahepatic cholestasis: mechanisms, diagnosis and therapy

Progressive intrahepatic cholestasis (PIHC, also known as progressive familial intrahepatic cholestasis) is a general term encompassing a devastating group of illnesses manifest by severe morbidity and potential mortality. By definition these diseases are characterized by persistent cholestasis that is the result of intra-hepatic rather than extra-hepatic pathology. Recent scientific advances have begun to clarify the molecular basis of many of these disorders. The morbidities of these diseases are primarily the result of profound cholestasis. This cholestasis is often associated with intractable pruritus, which leads to a very poor quality of life. Normal development and sleep are not possible for the affected individual and family dynamics are sometimes irreparably damaged. The cholestasis also leads to complications of fat soluble vitamin malabsorption including osteopenia and pathologic bone fractures, xeropthalmia, and peripheral neuropathy. End-stage liver disease and all of its attendant problems may develop in affected individuals by young adulthood. Optimal therapeutic approaches to PIHC are not well established and disease-specific approaches may be required.

Pruritus and fatigue in primary biliary cirrhosis

Pruritus and fatigue are the most common symptoms of patients with PBC, and both have marked negative impact on quality of life. Over the past decade, evidence has emerged supporting a role of the central nervous system in the pathogenesis of these two common manifestations of PBC. There is no evidence that the pruritus of cholestasis is mediated in the skin. Clinical and laboratory data do support a role of the opioid neurotransmitter system in the mediation of the pruritus of cholestasis; a central mechanism has been proposed. Treatment with opiate antagonist is thus a specific alternative. Studies of the behavioral consequence of the pruritus of cholestasis, scratching activity, allow for the design of clinical trials with objective end-points. The etiology of fatigue is unknown. A central component is being considered. The identification of objective alterations in fatigue and the adoption of a definition that incorporates the perception and the behavioral consequences of fatigue should facilitate the development of objective methodology. The potential role of various neurotransmitter systems, including the serotonin system and the opioid system, in the mediation of the fatigue of PBC seems to merit further investigation.

Treatment of Pediatric Cholestatic Liver Disease

Cholestatic liver disease affects a small percentage of children, but therapy results in millions of healthcare dollars being spent each year. Close monitoring of nutritional status, pruritus, and complications from portal hypertension should improve the patient's quality of life and survival without liver transplantation. Other comorbid conditions, such as cardiac or renal disease, must also be integrated into the care plan and will affect the overall prognosis of the patient. Portal hypertension leads to ascites, variceal hemorrhage, and infection, which can result in significant mortality if not promptly recognized and treated. Surgical shunts are being used less because the expertise to perform endoscopic sclerotherapy and endoscopic band ligation is available at most medical centers. However, many cholestatic diseases, including biliary atresia, progressive familial intrahepatic cholestasis (PFIC) I, II, and III, and Alagille syndrome, may still require liver transplantation (Table 1). The cost of this procedure can exceed several hundred thousand dollars per patient, without including the annual costs of immunosuppressant therapy and medical monitoring. Meticulous medical management of nutrition and the sequelae of portal hypertension may prolong survival and reduce the potential morbidity and mortality of liver transplantation.

Biliary diversion for progressive familial intrahepatic cholestasis: improved liver morphology and bile acid profile

BACKGROUND AND AIMS

Progressive familial intrahepatic cholestasis (PFIC) is characterized by pruritus, intrahepatic cholestasis, low serum gamma-glutamyltransferase levels, and characteristic "Byler bile" on electron microscopy. Many patients require liver transplantation, but partial external biliary diversion (PEBD) has shown therapeutic promise. However, the effect of PEBD on liver morphology and bile composition has not been evaluated.

METHODS

We reviewed liver biopsy specimens from 3 children with low gamma-glutamyltransferase PFIC before and after PEBD. Follow-up liver biopsies were performed 9-60 months after PEBD. Light and electron microscopic features were scored blindly. Biliary bile acid composition was analyzed by gas chromatography-mass spectrometry before and after PEBD in 1 patient and after PEBD in 2 patients.

RESULTS

Following PEBD, all patients improved clinically. Preoperative biopsy specimens showed characteristic features of PFIC, including portal fibrosis, chronic inflammation, cholestasis, giant cell transformation, and central venous mural sclerosis. Ultrastructural findings included coarse, granular canalicular Byler bile, effaced canalicular microvilli, and proliferative pericanalicular microfilaments. Following diversion, histology showed almost complete resolution of cholestasis, portal fibrosis, and inflammation with resolution of ultrastructural abnormalities. Biliary bile acids before PEBD consisted predominantly of cholic acid. After PEBD, the proportion of chenodeoxycholic acid increased significantly in 1 patient and was above the PFIC range in a second patient.

CONCLUSIONS

The resolution of hepatic morphologic abnormalities following PEBD supports PEBD as an effective therapy for PFIC. The improved biliary bile acid composition suggests enhanced bile acid secretion after PEBD, perhaps by induction of alternative canalicular transport proteins.

Effect of molecular adsorbent recirculating system in hepatitis C virus-related intractable pruritus

Intractable pruritus is more common in cholestatic liver diseases and may be the presenting symptom and/or major complaint of hepatitis C and/or hepatitic C virus-related cirrhosis. From September 2000 to May 2002, three patients affected by intractable pruritus secondary to hepatitis C cirrhosis that failed medical treatment were treated with a molecular adsorbent recirculating system (MARS). MARS is an artificial liver support system that aims to clear the blood of metabolic waste products normally metabolized by the liver. Each patient underwent seven MARS sessions. Liver function tests, the 36-Item Short Form quality-of-life test, visual analog scale for itching, and bile acid measurement in the serum, albumin circuit and ultrafiltrate were performed before and after each MARS session. Moreover, at hospital admission, each patient underwent a psychological workup and abdominal imaging study. Subjective improvement in pruritus and quality of life, along with a decrease in serum bile acid concentration, was observed in every patient; no patient underwent retreatment and/or liver transplantation up to a 9-month follow-up. One patient died 201 days after MARS treatment. Although we observed a decreased level of serum bile acids, one cannot conclude that this was the mechanism of action for the reduction in pruritus intensity in patients in our series. Different toxins and/or a placebo effect might have had a role in this setting.

Understanding and controlling hepatobiliary function

Over the past decade, enormous progress has been made in identifying the mechanisms that underlie hepatobiliary excretion. A set of transport proteins mediates the canalicular transport of most important bile constituents. With the discovery of these transporter genes, the mechanism of bile formation could be partly elucidated and genetic defects caused by mutations in these genes identified. This progress is crucial not only for paediatric and adult hepatology, but also for pharmacology, because the characterization of these transport systems provides tools for the prediction of the pharmacokinetics of drugs. Indeed, there is a growing interest on the part of the pharmaceutical industry for research into transport systems in general and hepatobiliary secretion in particular. For all of these transporter genes, knockout mice have been bred that allow one to assess the in vivo function of each of these transporters with regard to their role in physiology and drug elimination.

Partial external biliary diversion for intractable pruritus and xanthomas in Alagille syndrome

Alagille syndrome (AGS) causes intractable pruritus and disfiguring xanthomas because of retained bile acids and cholesterol. This study was performed to determine whether partial external biliary diversion (PEBD) is effective for relief of pruritus and xanthomas in AGS patients who fail conventional medical therapy. Between the years 1985 and 2001, 9 AGS patients underwent PEBD. Complete follow-up data were available for all patients. The average age at PEBD was 4.8 (range 1.4-10) years. The average duration of follow-up was 7.5 (range 0.5-16.0) years. All 9 patients had severe, mutilating pruritus (grade 4) prior to diversion. At 1 year post-PEBD, the average pruritus score was 1.1; 8 patients had only mild scratching when undistracted. Three patients with extensive xanthomas prior to PEBD had complete resolution within 1 year. Mean serum bile salt levels (n = 5) decreased from 136.5 to 37.1 micromol/L and mean cholesterol (n = 7) from 724 to 367 mg/dL 1 year after PEBD. A single 21-year-old patient with PEBD for 14 years experienced an increase in pruritus from grade 1 to grade 4 within 2 months of elective reversal of PEBD. In conclusion, PEBD is effective for treating severe pruritus and hypercholesterolemia in AGS patients without cirrhosis who did not respond to medical therapy. PEBD should be considered as a therapeutic option for these patients before referral for liver transplantation because of morbid complications.

Genetic defects in hepatobiliary transport

Bile formation, the exocrine function of the liver, represents a process that is unique to the hepatocyte as a polarized epithelial cell. The generation of bile flow is an osmotic process and largely depends on solute secretion by primary active transporters in the apical membrane of the hepatocyte. In recent years an impressive progress has been made in the discovery of these proteins, most of which belong to the family of ABC transporters. The number of identified ABC transporter genes has been exponentially increasing and the mammalian subfamily now counts at least 52. This development has been of crucial importance for the elucidation of the mechanism of bile formation, and it is therefore not surprising that the development in this field has run in parallel with the discovery of the ABC genes. With the identification of these transporter genes, the background of a number of inherited diseases, which are caused by mutations in these solute pumps, has now been elucidated. We now know that at least six primary active transporters are involved in canalicular secretion of biliary components (MDR1, MDR3, BSEP, MRP2, BCRP and FIC1). Four of these transporter genes are associated with inherited diseases. In this minireview we will shortly describe our present understanding of bile formation and the associated inherited defects.

Intestinal bile acid transport: biology, physiology, and pathophysiology

Intestinal reabsorption of bile salts plays a crucial role in human health and disease. This process is primarily localized to the terminal ileum and is mediated by a 48-kd sodium-dependent bile acid cotransporter (SLC10A2 = ASBT). ASBT is also expressed in renal tubule cells, cholangiocytes, and the gallbladder. Exon skipping leads to a truncated version of ASBT, which sorts to the basolateral surface and mediates efflux of bile salts. Inherited mutation of ASBT leads to congenital diarrhea secondary to bile acid malabsorption. Partial inhibition of ASBT may be useful in the treatment of hypercholesterolemia and intrahepatic cholestasis. During normal development in the rat ileum, ASBT undergoes a biphasic pattern of expression with a prenatal onset, postnatal repression, and reinduction at the time of weaning. The bile acid responsiveness of the ASBT gene is not clear and may be dependent on both the experimental model used and the species being investigated. Future studies of the transcriptional and posttranscriptional regulation of the ASBT gene and analysis of ASBT knockout mice will provide further insight into the biology, physiology, and pathophysiology of intestinal bile acid transport.