The effect of taurine on the cholestatic potential of sulfated lithocholate and its conjugates

New insights into intestinal failure-associated liver disease in adults: A comprehensive review of the literature

Intestinal failure-associated liver disease (IFALD) remains one of the most common and serious complications of parenteral nutrition (PN), causing a wide spectrum of hepatic manifestations from steatosis and mild cholestasis to portal hypertension and end-stage liver failure. The prevalence of IFALD depends on the diagnostic criteria and ranges from 4.3% to 65%. Moreover, many factors are shown to contribute to its development, including nutrient deficiencies, toxicity of PN, infections, and alterations of bile acid metabolism and gut microbiota. Prevention and management of IFALD aim at ameliorating or eliminating the risk factors associated with IFALD. The use of PN formulations with a lower ratio omega-6-to-omega-3 polyunsaturated fatty acids, cycle PN, optimization of enteral stimulation and prevention and early treatment of infections constitute the main therapeutic targets. However, failure of improvement and severe IFALD with end-stage liver failure should be considered as the indications of intestinal transplantation. The aim of this review is to provide an update of the epidemiology, pathophysiology, and diagnosis of IFALD in the adult population as well as to present a clinical approach of the therapeutic strategies of IFALD and present novel therapeutic targets.

Abnormal liver function tests in the parenteral nutrition fed patient

Liver dysfunction is common in individuals receiving parenteral nutrition (PN) and particularly in neonates and infants. Abnormalities of liver function tests in patients receiving short term PN are usually transient but in individuals receiving long term PN, substantial liver damage and ultimately end stage liver disease may occur. The aetiology is complex, involving a large number of patient related and nutrition related factors. The terminology intestinal failure associated liver disease (IFALD) is therefore more appropriate than PN associated liver disease. Effort should be made to prevent liver dysfunction by managing sepsis, avoiding parenteral overfeeding, employing cyclical parenteral feeding and encouraging enteral nutrition where possible. Intake of soybean based parenteral lipid emulsions should be reduced in individuals with established IFALD, possibly to be replaced by lipid emulsions containing medium chain triacylglycerol, monounsaturated fatty acids or fish oil although larger clinical studies are needed. Similarly, evidence supporting the widespread use of parenteral choline and taurine supplementation in the prevention or treatment of IFALD remains limited. There are more data to support the use of oral antibiotics to treat bacterial overgrowth and oral ursodeoxycholic acid in neonates. Ultimately, severe IFALD may necessitate referral for small intestine and/or liver transplantation.

Managing liver dysfunction in parenteral nutrition

Parenteral nutrition is life saving in patients with intestinal failure but liver dysfunction is commonly encountered, especially in neonates. Although abnormal liver function tests associated with short-term parenteral nutrition are usually benign and transient, liver dysfunction in both children and adults receiving long-term parenteral nutrition can progress to end-stage liver disease and liver failure. The aetiology of parenteral nutrition-associated liver disease is complex and multifactorial, with a range of patient, disease and nutrition-related factors implicated. Sepsis is of particular importance, as is the lack of enteral nutrition and overfeeding with intravenous glucose and/or lipid. Deficiencies of a number of amino acids including choline and taurine have also been implicated. Management of hepatic dysfunction in parenteral nutrition should initially focus on preventing its occurrence. Sepsis should be managed appropriately, enteral nutrition should be encouraged and maximised where possible and parenteral overfeeding should be avoided. Provision of parenteral lipid should be optimised to prevent the adverse effects of both deficiency and excess, and cyclical rather than continuous parenteral feeding should be administered. There is some evidence of benefit in neonates from oral antibiotics to prevent intestinal bacterial overgrowth and from oral ursodeoxycholic acid, but less to support their use in adults. Similarly, data to support widespread use of parenteral choline or taurine supplementation are lacking at present. Ultimately, severe parenteral nutrition-associated liver disease may necessitate referral for small intestine and/or liver transplantation.

Effect of Taurine on Biliary Excretion and Metabolism of Acetaminophen in Male Hamsters

The effect of taurine intake on the biliary disposition and toxicity of acetaminophen (APAP) was examined in male Golden-Syrian hamsters. Animals were provided with taurine (5 mM) in drinking water for 1 week followed by APAP treatment (250 mg/kg, i.p.). Biliary excretion and plasma concentrations of APAP and its major metabolites were determined for up to 360 min. Taurine increased the bile flow, whereas the concentration of APAP or the metabolites in bile was not altered significantly. Accordingly the total biliary excretion of APAP and the metabolites was increased in hamsters fed taurine. Taurine increased the plasma concentrations of APAP-glutathione (GSH) and APAP-mercapturate, but the APAP-glucuronide or APAP-sulfate concentration was not changed. The area under the curve of the plasma APAP concentration was reduced significantly, suggesting that the elimination of APAP was enhanced by taurine intake. However, the hepatotoxicity resulting from a dose of APAP (450 mg/kg, i.p.) was not altered by taurine intake as determined by the elevation of serum alanine aminotransferase, aspartate aminotransferase, and sorbitol dehydrogenase activities. The results suggest that taurine administration could affect the disposition of APAP by enhancing its metabolism through the GSH-dependent pathway and also by increasing the biliary excretion of this drug and its metabolites. The pharmacological significance of this finding remains to be examined.

Improvement in cholestasis associated with total parenteral nutrition after treatment with an antibody against tumour necrosis factor alpha

BACKGROUND

Many patients receiving long-term total parenteral nutrition (TPN) develop liver disease; cholestasis is common and may be severe. Antitumour necrosis factor alpha (TNFalpha) antibodies have recently been used in order to treat Crohn's disease, but their effect on cholestasis in humans has not been previously described.

CASE REPORT

A 45-year-old woman had complicated Crohn's disease with multiple fistulae and only 1 m of residual small bowel. She had been receiving TPN for 2.5 years when she developed cholestasis which worsened despite adjustments to her TPN regimen. Infliximab, an anti-TNFalpha antibody, was given with the aim of treating an enterocutaneous fistula, but it also produced a marked biochemical and histological improvement in the TPN-related cholestasis.

CONCLUSIONS

Anti-TNFalpha antibodies appeared in this case to improve TPN-related cholestasis. This implies that TNFalpha may play an important role in the development of this condition.

Total parenteral nutrition and cholestasis

Hepatobiliary dysfunction is recognized as a major adverse effect of total parenteral nutrition (TPN). It is unknown if this is caused by a deficiency or toxicity of the TPN solution or the underlying pathophysiology of disease processes that require TPN therapy. This article presents algorithms for evaluating abnormal liver tests in patients on TPN and discusses treatment options and the current status of intestinal transplantation.

Liver complications of pediatric parenteral nutrition--epidemiology

Total parenteral nutrition (TPN)-induced liver disease develops in 40-60% of infants who require long-term TPN for intestinal failure. The clinical spectrum includes cholestasis, cholelithiasis, hepatic fibrosis with progression to biliary cirrhosis, and the development of portal hypertension and liver failure in a significant number of children who are totally parenterally fed. The pathogenesis is multifactorial and is related to prematurity, low birth weight, and duration of TPN. The degree and severity of the liver disease is related to recurrent sepsis including catheter sepsis, bacterial translocation, and cholangitis. Lack of enteral feeding leading to reduced gut hormone secretion, reduction of bile flow, and biliary stasis may be important mechanisms in the development of cholestasis, biliary sludge, and cholelithiasis. Although it is unlikely that modern TPN solutions have a major role in the etiology of TPN liver disease, manganese toxicity recently has been recognized in children with hepatic dysfunction on TPN. Although there is a definite relationship with the degree of manganese toxicity and hepatic decompensation, it is not yet clear whether this is a primary mechanism or whether the high levels are related to reduced biliary excretion of manganese. The management strategies for the prevention of TPN-induced liver disease include early enteral feeding, a multidisciplinary approach to the management of parenteral nutrition, and aseptic catheter techniques to reduce sepsis. The administration of ursodeoxycholic acid may improve bile flow and reduce gall bladder and intestinal stasis. As survival from isolated intestinal transplantation improves, this therapeutic option should be considered before TPN liver disease becomes irreversible and combined liver and small bowel transplantation is required.

Liver and biliary tract changes and injury associated with total parenteral nutrition: pathogenesis and prevention

Total parenteral nutrition (TPN), now widely used, is successful in preventing and reversing malnutrition in individuals with various diseases and conditions. However, hepatic and biliary complications of TPN are encountered in both adult and pediatric patients. Certain complications, such as sepsis and TPN-associated cholestasis, occur more frequently in very young infants. Continuing problems commonly seen in adults are steatosis and steatonecrosis. Reasons for the development of these complications are multifactorial. Etiologies of hepatic complications, especially the role of deficiency/excess of nutrients in the pathogenesis of hepatobiliary disorders, are summarized. Complications caused by the duration of TPN are discussed with emphasis on prevention and management. Evidence now suggests that prompt enteral feeding, even in minimal amounts, may prevent many of the metabolic complications associated with TPN. TPN should be used only in amounts meeting needs and for a duration essential to survival.

Hepatobiliary complications of total parenteral nutrition

The relationships between various hepatobiliary disorders and the administration of total parenteral nutrition (TPN) were reviewed and, in particular, the role of TPN in their pathogenesis was critically evaluated. Several clinical and pathological entities including steatosis, steatohepatitis, cholestasis, and cholelithiasis have been commonly linked to TPN, and instances of chronic decompensated liver disease have been reported. However, it is concluded that it is often difficult to extricate the effects of TPN on hepatobiliary function from many other hepatotoxic factors that may be operative in these patients. Thus, whereas considerable evidence exists to support a role fro carbohydrate or calorie excess in TPN solutions in the pathogenesis of steatosis, a loss of enteric stimulation and not TPN per se may be the primary factor in the development of cholestasis, biliary sludge, and gallstones. The apparent predilection of infants to TPN-related cholestasis may be based on the relative immaturity of the neonatal biliary excretory system.