Lipoproteins in liver disease

Profoundly Disturbed Lipoproteins in Cirrhotic Patients: Role of Lipoprotein-Z, a Hepatotoxic LDL-like Lipoprotein

Detailed information regarding lipoprotein concentrations and subfractions in cirrhotic patients before and after orthotopic liver transplantation (OLT) is lacking. Lipoprotein-Z (LP-Z) is a recently characterised abnormal, hepatotoxic free cholesterol-rich low-density lipoprotein (LDL)-like lipoprotein. We determined the lipoprotein profiles, including LP-Z, in cirrhotic patients and OLT recipients and assessed the prognostic significance of LP-Z on the OLT waiting list. We performed analyses in cirrhotic transplant candidates and non-cirrhotic OLT recipients. A population-based cohort was used as reference. The setting was a University hospital. Lipoprotein particle concentrations and subfractions were measured by nuclear magnetic resonance spectroscopy. In the cirrhotic patients (N = 130), most measures of triglyceride-rich lipoproteins (TRL), LDL, and high-density lipoproteins (HDL) were much lower compared to the OLT recipients (N = 372) and controls (N = 6027) (p < 0.01). In the OLT recipients, many lipoprotein variables were modestly lower, but HDL-cholesterol, triglycerides, and TRL and HDL size were greater vs. the control population. LP-Z was measurable in 40 cirrhotic patients and 3 OLT recipients (30.8% vs. 0.8%, p < 0.001). The cirrhotic patients with measurable LP-Z levels had profoundly lower HDL-cholesterol and particle concentrations (p < 0.001), and worse Child Pugh Turcotte classifications and MELD scores. The presence of LP-Z (adjusted for age, sex, and MELD score) predicted worse survival in cirrhotic patients (HR per 1 LnSD increment: 1.11, 95%CI 1.03−1.19, p = 0.003). In conclusion, cirrhotic patients have considerably lower plasma concentrations of all major lipoprotein classes with changes in lipoprotein subfraction distribution. After OLT, these lipoprotein abnormalities are in part reversed. LP-Z is associated with cirrhosis. Its presence may translate in disturbed HDL metabolism and worse survival.

Management of lipoprotein X and its complications in a patient with primary sclerosing cholangitis

Lipoprotein X (LpX) is an abnormal lipoprotein found in conditions such as lecithin:cholesterol acyltransferase deficiency and cholestatic states (e.g., primary biliary cirrhosis and primary sclerosing cholangitis). Management of severe hypercholesterolemia due to LpX with drugs and physical removal methods is not well established in the literature. A case is discussed of a 51-year-old woman who presented with multiple electrolyte abnormalities, xanthomas and neuropathy found to be secondary to LpX in the setting of primary sclerosing cholangitis. This case highlights that oral medications, including statins, may be insufficient to normalize lipid levels or improve clinical symptoms of LpX and presents therapeutic plasma exchange as a safe and effective therapeutic option to treat the morbid sequela of LpX hyperlipidemia.

The effect of the severity of liver cirrhosis on the level of lipids and lipoproteins

The effect of severity of liver cirrhosis, an alcoholic and non-alcoholic genesis, on the results of serum lipids and lipoproteins was evaluated. Serum cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-Ch), and low-density lipoprotein cholesterol (LDL-Ch) were measured in the sera of 59 patients suffering from alcoholic cirrhosis and 34 patients with non-alcoholic cirrhosis. The level of serum triglycerides depends on the severity of liver damage in alcoholic liver cirrhosis, being the highest in Child-Pugh score B. The severity of liver damage significantly affects the HDL-Ch and LDL-Ch levels in cirrhosis of non-alcoholic origin, reaching the highest value for LDL-Ch and the lowest for HDL-Ch in score C. It should not be generalized that the levels of lipids and lipoproteins in liver cirrhosis progressively diminished with the deterioration of liver function. The serum HDL-Ch and LDL-Ch may be considered as markers of severity of liver damage in non-alcoholic cirrhosis, but the triglycerides only in disease of alcoholic origin.

Association of apolipoprotein b/apolipoprotein A1 ratio and coronary artery stenosis and plaques detected by multi-detector computed tomography in healthy population

Despite the noninvasiveness and accuracy of multidetector computed tomography (MDCT), its use as a routine screening tool for occult coronary atherosclerosis is unclear. We investigated whether the ratio of apolipoprotein B (apoB) to apolipoprotein A1 (apoA1), an indicator of the balance between atherogenic and atheroprotective cholesterol transport could predict occult coronary atherosclerosis detected by MDCT. We collected the data of 1,401 subjects (877 men and 524 women) who participated in a routine health screening examination of Asan Medical Center. Significant coronary artery stenosis defined as > 50% stenosis was detected in 114 subjects (8.1%). An increase in apoB/A1 quartiles was associated with increased percentages of subjects with significant coronary stenosis and noncalcified plaques (NCAP). After adjustment for confounding variables, each 0.1 increase in serum apoB/A1 was significantly associated with increased odds ratios (ORs) for coronary stenosis and NCAP of 1.23 and 1.18, respectively. The optimal apoB/A1 ratio cut off value for MDCT detection of significant coronary stenosis was 0.58, which had a sensitivity of 70.2% and a specificity of 48.2% (area under the curve, 0.61; 95% CI, 0.58-0.63, P < 0.001). Our results indicate that apoB/A1 ratio is a good indicator of occult coronary atherosclerosis detected by coronary MDCT.

Tolerance of mixed lipid emulsion in neonates: effect of concentration

AIMS

To compare the effect of concentration of a mixed lipid emulsion (50:50 medium chain triglyceride/long chain triglyceride) (MCT/LCT) on lipid tolerance in neonates.

METHODS

A prospective randomised controlled trial of 75 neonates requiring prolonged parenteral nutrition was conducted in the neonatal intensive care units of the Royal Maternity Hospital, Belfast, and the Waveney Hospital, Ballymena. Thirty eight infants received 10% and 37 20% lipid emulsion. Infants were randomly assigned to groups at the start of parenteral nutrition and studied if they required seven or more days of this. Lipid tolerance was assessed by twice weekly measurements of plasma triglyceride and cholesterol concentrations and weekly measurement of non-esterified fatty acids and beta hydroxy butyrate. Anthropometry was carried out weekly.

RESULTS

The mean cholesterol in the 10% group was significantly higher within the first seven days of the study compared with the 20% group (3.5 vs 2.87 mmol/l), and continued to rise over the study period in contrast to the 20% group. A similar pattern was observed with the triglyceride concentrations. There was no significant difference in non-esterified fatty acids, beta hydroxy butyrate, or growth between the two groups.

CONCLUSION

Sick neonates show better biochemical tolerance to 20% MCT/LCT emulsion than to 10% emulsion.

Pseudohyponatraemia, hypercholesterolaemia, and primary biliary cirrhosis

A 62 year old woman with primary biliary cirrhosis was found to have a plasma sodium concentration of 115 mmol/l. Follow up showed this to be a "pseudohyponatraemia" due to a massively raised serum cholesterol concentration of 78 mmol/l. Electrophoresis of serum lipoproteins and of the lipoproteins and apolipoproteins in fractions isolated on density-gradient ultracentrifugation showed that the major portion of the serum cholesterol was being transported with lipoprotein-X. Low density lipoprotein-cholesterol concentration was also raised. Lipoprotein-X contained, in addition to albumin and apolipoprotein C, apolipoprotein E. This case is of interest because of the degree of hypercholesterolaemia, its association with pseudohyponatraemia, and the unequivocal demonstration of apolipoprotein E associated with lipoprotein-X.