Recent advances in factors that alter lipid metabolism in chronic renal failure

The following conclusions and speculations can be tentatively drawn from the changes in lipoprotein composition and metabolism: (1) The presence of apo B-48 in serum VLDL and the high serum apo A-IV concentrations indicate a greater than normal contribution of alimentary remnant particles to the hypertriglyceridemia of uremic patients. (2) The presence of apo E and C in triglyceride-enriched serum LDL, together with the triglyceride enrichment of all lipoproteins, probably stems from a deficiency of lipoprotein lipase (LPL) and hepatic lipase (HL) activity. (3) The decreased ratio of serum apo C-II/C-III in VLDL is at least in part responsible for the depressed activity of LPL. (4) The accumulation of lipoprotein particles with distorted apoprotein and lipid patterns (particularly β-VLDL with enrichment in cholesterol) could be associated with an increased atherogenesis because a recent study has demonstrated a strong association between raised serum IDL and VLDL concentrations and the degree of coronary atherosclerosis. (5) The increased apo E content of VLDL and HDL in uremic patients could particularly point to a disturbed cholesterol metabolism because such lipoproteins could interact with LDL at apo B, E receptors. (6) The decrease in serum HDL-cholesterol has been shown to be strongly associated with atheromatous vascular disease, and this could also hold for uremic patients; however, it is probable that low serum HDL-cholesterol together with a diminished capacity to form cholesterol-rich, apo E containing HDL represents a decrease in the antiatherogenic defense of the organism rather than an increased atherogenic potential.