Lipoprotein pattern and plasma lecithin cholesterol acyl transferase activity in children with Alagille syndrome

Nutrition in Pediatric Liver Disease

In liver disease, there is derangement of appetite, digestion, absorption, assimilation, storage and metabolism of both macro and micronutrients. These derangements have an impact on mortality and morbidity associated with liver diseases. In infants, breast feeds should not be stopped unless there are compelling reasons such as underlying metabolic problem. Parenteral nutrition should be considered only if, oral or nasogastric feeding is not possible. The effect of malnutrition on liver disease and impact of liver failure on nutrition is vicious and nutritional intervention has to be done at the earliest to break that vicious cycle. This chapter gives an overview of nutritional management in acute and chronic liver diseases in children and also its impact on specific clinical scenarios including liver transplantation.

Case report: Unusual and extremely severe lipoprotein X-mediated hypercholesterolemia in extrahepatic pediatric cholestasis

BACKGROUND

Lipoprotein X (LpX) - mediated extremely severe hyperlipidemia is a possible feature detectable in children with syndromic paucity of intralobular bile ducts (Alagille syndrome) but rarely in other types of intra- and/or extrahepatic infantile cholestasis.

CASE PRESENTATION

Here we report on a previously well 18-month child admitted for cholestatic jaundice and moderate hepatomegaly. Laboratory tests at entry showed conjugated hyperbilirubinemia, elevated values of serum aminotransferases, gamma-glutamyl transpeptidase (GGT) and bile acids (100 folds upper normal values). Extremely severe and ever-increasing hypercholesterolemia (total cholesterol up to 1,730 mg/dl) prompted an extensive search for causes of high GGT and/or hyperlipidemic cholestasis, including an extensive genetic liver panel (negative) and a liver biopsy showing a picture of obstructive cholangitis, biliary fibrosis, and bile duct proliferation with normal MDR3 protein expression. Results of a lipid study showed elevated values of unesterified cholesterol, phospholipids, and borderline/low apolipoprotein B, and low high-density lipoprotein-cholesterol. Chromatographic analysis of plasma lipoproteins fractions isolated by analytical ultracentrifugation revealed the presence of the anomalous lipoprotein (LpX). Magnetic resonance cholangiopancreatography and percutaneous transhepatic cholangiography showed stenosis of the confluence of the bile ducts with dilation of the intrahepatic biliary tract and failure to visualize the extrahepatic biliary tract. Surgery revealed focal fibroinflammatory stenosis of the left and right bile ducts confluence, treated with resection and bilioenteric anastomosis, followed by the rapid disappearance of LpX, paralleling the normalization of serum lipids, bilirubin, and bile acids, with a progressive reduction of hepatobiliary enzymes.

CONCLUSION

We have described a unique case of focal non-neoplastic extrahepatic biliary stenosis of uncertain etiology, presenting with unusual extremely high levels of LpX-mediated hypercholesterolemia, a condition which is frequently mistaken for LDL on routine clinical tests.

Liver transplantation for rare liver diseases and rare indications for liver transplant

Liver transplantation (LT) is currently considered the gold standard treatment for end-stage liver failure. Compared to the first decades of its use, LT is associated with lower comorbidity and mortality, with a 5-year survival over 70%. Worldwide, liver cirrhosis and hepatocellular carcinoma represent the major indications to LT. However, almost 1% of LT is performed for rare diseases or rare indications, which include non-hepatocellular malignancy, vascular disorders, metabolic and congenital liver disorders. These diseases can lead to hepatocellular necrosis, biliary tree abnormality and/or hepatomegaly. Most of these diseases are not associated with liver failure but in highly selected patients, LT represent an effective therapy improving the overall survival and quality of life. Rare indications for LT often overlap with rare diseases. However, rare LT indications for non-rare diseases are rising in the last decades, especially for benign primary liver tumor, colon rectal liver metastasis, neuroendocrine liver metastasis, and cholangiocarcinoma (CCA). Non-rare diseases with rare indication for LT and rare adult disease with an indication for LT are categorized and discussed in detail, focusing on some disorders for which the literature provides a more definitive evidence base. Early referral to a transplant center is encouraged to provide an effective therapeutic option in these non-standard indications for LT.

Negative feedback loop of cholesterol regulation is impaired in the livers of patients with Alagille syndrome

AIM

To characterize cholesterol regulation in the liver of patients with Alagille syndrome (AGS).

METHODS

Serum total cholesterol (TC) and total bile acid (TBA) levels were measured in 23 AGS patients. The expressions of genes involved in cholesterol regulation, including low-density lipoprotein receptor (LDLR), scavenger receptor class B type I (SR-BI), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), cholesterol 7α-hydroxylase (CYP7A1), ATP-binding cassette transporter (ABC) A1, and ABCG1/5/8, were measured in liver tissues from five of these patients. Expression of regulators for these genes, including farnesoid X receptor/small heterodimer partner (SHP), liver X receptor α (LXRα) and mature Sterol regulatory element-binding protein 2 (SREBP2) was measured. The expression of mature SREBP2 protein was also examined.

RESULTS

Serum TC and TBA levels were correlated in the AGS patients. Liver cholesterol was also increased compared with controls, and correlated with bile acid contents. LDLR, SR-BI, HMGCR, and ABCGs mRNA expression were upregulated, while CYP7A1 mRNA expression was downregulated in AGS livers. SHP and LXRα mRNA expression was also increased, but maturation of SREBP2 was not suppressed in the patients.

CONCLUSIONS

The major upregulators of liver cholesterol might be increased in AGS patients, indicating an impaired negative feedback mechanism and accelerated liver cholesterol accumulation.

Medical management of Alagille syndrome

Alagille syndrome is a highly variable, autosomal dominant disorder that affects the liver, heart, eyes, face, skeleton, kidneys, and vascular system. Much has been learned about the genetics of this disorder, which is caused primarily by mutations in the Notch signaling pathway ligand JAGGED1; however, the medical management of this condition is complex and continues to generate controversy. The significant variability of organ involvement requires the managing physician to have an understanding of the breadth and interplay of the variable manifestations. Furthermore, the liver disease in particular requires an appreciation of the natural history and evolution of the profound cholestasis.

Bile composition in Alagille Syndrome and PFIC patients having Partial External Biliary Diversion

BACKGROUND

Partial External Biliary Diversion (PEBD) is a surgical intervention to treat children with Progressive Familial Intrahepatic Cholestasis (PFIC) and Alagille syndrome (AGS). PEBD can reduce disease progression, and examining the alterations in biliary lipid composition may be a prognostic factor for outcome.

METHODS

Biliary lipid composition and the clinical course of AGS and PFIC patients were examined before and after PEBD.

RESULTS

Pre-PEBD bile from AGS patients had greater chenodeoxycholic/cholic acid (CDCA/CA), bile salt, cholesterol and phospholipid concentrations than PFIC patients. AGS patients, and PFIC patients with familial intrahepatic cholestasis 1 (FIC1) genotype, responded better to PEBD than PFIC patients with bile salt export protein (BSEP) genotype. After successful PEBD, AGS patients have higher biliary lipid concentrations than PFIC patients and PEBD also increases biliary phospholipid concentrations in FIC1 patients.

CONCLUSION

Both AGS and FIC1 patients can benefit from PEBD, and preserved biliary phospholipid concentrations may be associated with better outcomes post-PEBD.

Fluctuation of lipoprotein metabolism linked with bile acid-activated liver nuclear receptors in Alagille syndrome

Alagille syndrome (AGS) is a rare hereditary disorder exhibiting fluctuating cholestasis and dyslipidemia. Farnesoid X receptor (FXR) and liver X receptor (LXR) are hepatic nuclear receptors that regulate bile acid and lipoprotein metabolism. To investigate whether cholestasis is related to dyslipidemia and hepatic nuclear receptor expression in AGS patients, we determined the blood levels of total bile acid (TBA) and lipoprotein parameters, and examined hepatic nuclear receptor expression in three AGS children and their three incomplete AGS parents repeatedly over several years. In the AGS children, TBA level showed significant positive correlations with low-density lipoprotein-cholesterol, apolipoprotein E (apoE)-rich high-density lipoprotein-cholesterol (HDL-C), apoA-I, apoE, and cholesteryl ester transfer protein (CETP) concentrations, but negative correlation with apoE-poor HDL-C concentration. Western blot analysis of liver biopsy specimens revealed that FXR and LXR expression increased in parallel with TBA level. CETP- and ATP-binding cassette transporter A1 expression also increased with TBA level, while scavenger receptor class B type-I expression showed the opposite response. However, apoA-I expression was similar to the control level at any TBA level. In the incomplete AGS parents, TBA and lipoprotein parameters showed little fluctuation. In summary, cholestasis is closely related to dyslipidemia and hepatic nuclear receptor expression in AGS patients.

Intense pruritus and failure to thrive in Alagille syndrome

A 4-year-old girl with failure to thrive and intense pruritus associated with Alagille syndrome is described. The clinical features of this autosomal dominant disorder are reviewed. This case highlights the importance of recognizing the severe pruritus as a manifestation of the disease.

SR-BI- and ABCA1-mediated cholesterol efflux to serum from patients with Alagille syndrome

Alagille syndrome is associated with bile duct paucity resulting in liver disease. Patients can be divided into mildly and severely icteric groups, with both groups having altered lipoproteins. The incidence of ischemic heart disease is rare in severely cholestatic children despite increased total cholesterol and decreased high density lipoprotein cholesterol (HDL-C). The present studies examine the impact of altered lipid and lipoproteins on scavenger receptor class B type I (SR-BI)- and ABCA1-mediated efflux to serum from both groups. Efflux was compared with serum from 29 patients (15 with normal plasma cholesteryl ester, 14 with low cholesteryl ester). Efflux via SR-BI and ABCA1 was studied using cell systems having either low or high expression levels of these receptors. SR-BI efflux was lower (P = 0.04) with serum from severely icteric patients (3.9 +/- 1.4%) compared with serum from mildly icteric patients (5.1 +/- 1.4%) and was positively correlated with HDL-C and its apolipoproteins. SR-BI-mediated efflux was not correlated with any particular mature HDL but was negatively correlated with small lipid-poor prebeta-1 HDL. Consistent with severely icteric patients having high prebeta-1 HDL levels, the ABCA1 efflux was significantly higher with their serum (4.8 +/- 2.2%) compared with serum from mildly icteric patients (2.0 +/- 0.6%) and was positively correlated with prebeta-1 HDL. These studies demonstrated that prebeta-1 HDL is the preferred acceptor for ABCA1 efflux, whereas many particles mediate SR-BI efflux.

Lack of cholesterol-lowering effect of graded doses of cholestyramine in children with Alagille syndrome: a pilot study

BACKGROUND

There is controversy about the potential risk of sustained high concentrations of cholesterol and triglyceride in patients with cholestatic chronic liver disease. However, it is currently accepted that cholesterol-lowering therapy may reduce morbidity and mortality rates in hypercholesterolemic patients without preexisting coronary heart disease, as well as in those with coronary heart disease. The objective of this study was to evaluate the effect of cholestyramine on the serum lipid profile of a group of children with Alagille syndrome and hypercholesterolemia.

METHODS

Five children with Alagille syndrome and basal serum cholesterol concentrations greater than 230 mg/dL were included. Total serum cholesterol, triglyceride, low-density, and high-density lipoprotein cholesterol concentrations were measured on days 0, 10, 20, and 30 after the administration of oral cholestyramine 100, 250, and 500 mg(kg.d), respectively. Lipid fractions were reported as mean +/- 1 SD. Statistical analysis was performed with Friedman analysis of variance.

RESULTS

The basal values and those of the three 10-day subsequent 100-, 250-, and 500-mg(kg.d) cholestyramine periods were as follows: total cholesterol: 327.6 +/- 77.1, 305.4 +/- 52.1, 290.6 +/- 24.1, and 320.6 +/- 32.3, respectively (P = 0.668); triglyceride: 136.4 +/- 14.6, 144.8 +/- 41.3, 161 +/- 30.9, and 165.4 +/- 40.7, respectively (P = 0.356); low-density lipoprotein cholesterol: 245.4 +/- 57.8, 239.8 +/- 48.6, 242.2 +/- 68.6, and 246.4 +/- 49.5, respectively (P = 0.782); and high-density lipoprotein cholesterol: 44.4 +/- 11.2, 41.8 +/- 12.8, 44.6.2 +/- 13.2, and 47 +/- 8.5, respectively (P = 0.431).

CONCLUSION

Under the conditions of the current study, no significant effect of variable doses of cholestyramine could be demonstrated on the serum lipid profile of a series of children with Alagille syndrome. While the controversy on the potential atherogenic risk of low-density lipoprotein hypercholesterolemia in patients with chronic liver disease persists, new, prospective pharmacologic or nutritional trials are required.

Arteriohepatic dysplasia (Alagille syndrome; Watson-Alagille syndrome)

Alagille syndrome (AS) (arteriohepatic dysplasia, Alagille-Watson syndrome) is a multi-system disorder with hepatic, skeletal, eye, cardiac and renal manifestations. It results from mutation of the JAG1 gene, located on chromosome 20, which encodes a ligand for Notch receptor(s). The interactions of Notch receptors and their ligands are crucial in controlling cell fate decisions in a variety of developmental processes. AS varies in its severity, even in the same family, from asymptomatic gene carriers through to lethality due to inoperable cardiac or end-stage liver disease. However, advances in medical and surgical therapy have improved the prognosis at the severe end of the spectrum. It is hoped that the enhanced understanding of the biology of AS resulting from the cloning of the JAG1 gene will enable us to develop additional strategies for more effective treatments.