Abnormal lipid and apolipoprotein composition of major lipoprotein density classes in patients with chronic renal failure.

BACKGROUND AND METHODS To characterize the abnormalities of lipoprotein composition in patients with chronic renal failure (CRF), the lipid and apolipoprotein (apo) concentrations and compositions of major lipoprotein density classes were determined in 20 subjects with moderate to advanced renal failure (GFR 5-59 ml/min) and nine controls. Patients were divided in 14 normotriglyceridaemic (NTG) subjects with triglyceride (TG) levels < or = 1.7 mmol/l (150 mg/dl) and six hypertriglyceridaemic (HTG) subjects with TG > or = 1.7 mmol/l. Lipoproteins were isolated by preparative ultracentrifugation: very low density (VLDL), intermediate density (IDL), low density (LDL) and high density (HDL) lipoproteins. RESULTS Although all density classes were characterized by abnormal concentration and composition of some lipid and apo constituents, the most profound changes occurred in IDL and HDL. Cholesterol levels were elevated in VLDL and IDL with little change in LDL and reduced in HDL. TG levels were increased in all density classes. ApoB levels were increased in VLDL, IDL and LDL of all CRF patients reaching the significance levels in VLDL and IDL of HTG (P < 0.01). In IDL, the levels of apoC-peptides and apoE were increased (P < 0.01). ApoC-peptides and apo E were also elevated in VLDL of NTG and HTG, but their increase was only significant in HTG (P < 0.01). In LDL, the concentration of apoC-II and apoC-III was significantly increased (P < 0.05). However, in HDL there was significant (P < 0.01) reduction of apoA-I, apoA-II and apoC-peptides in both patient groups. The major compositional change was a significant increase in the relative contents of apoC-II and apoC-III in VLDL, IDL and LDL (P < 0.01). CONCLUSIONS Results indicate that the characteristic feature of dyslipoproteinemia in CRF is the accumulation of partially delipidized TG-rich apoB-containing lipoproteins enriched in apoC-peptides and distributed characteristically in the IDL density-range irrespective of fasting TG concentrations. Increased levels of these ¿remnant lipoproteins' and reduced levels of HDL may represent risk factors for atherogenesis and progressive renal disease.