Influence of remnant accumulation markers on plasma concentrations of two lipoprotein(a) subspecies (containing or free of apoE)

Lipoprotein(a) [Lp(a)], an atherosclerosis marker, has 2 subspecies differi ng in structure and composition that can easily be distinguished by the pre sence or absence of apolipoprotein E (apoE). The subspecies containing apo E [Lp(a):B:E] is found mainly in the very-low-density lipoprotein (VLDL) si ze range, while that free of apoE [Lp(a):B] is found mainly in the LDL size range. As little is known about the physiologic function of these subspeci es, this study investigated Lp(a):B and Lp(a):B:E concentrations in a popul ation of normotriglyceridemic and moderately hypertriglyceridemic subjects in fasting state and attempted to determine the parameters influencing thei r plasma concentrations. The subjects studied (n = 98) had a mean total Lp( a) concentration of 108 mg/dL (28 to 252, minimum to maximum), a mean Lp(a) :B concentration of 92.6 mg/dL (5 to 254), and a mean Lp(a):B:E concentrati on of 15.6 mg/dL (0 to 137). These results indicate that Lp(a):B:E, even in normolipidemic subjects, constitutes a detectable part of total Lp(a), ie, a mean percentage of 16.2% (0% to 96%). Multiple stepwise regression analy ses showed that triacylglycerol has no independent effect on the concentrat ion of Lp(a) subspecies, and that remnant accumulation markers, such as the E/LpB:E molar ratio (number of apoE per particle containing both apoB and apoE) and apoE-LpB (mass of apoE bound to particles containing both apoB an d apoE), have a strong independent effect on this concentration. A strong p ositive influence of E/LpB:E on Lp(a):B:E subspecies was noted, as well as a negative influence of apo E-LpB on Lp(a):B subspecies. Taken together, th ese results suggest that the apoE bound to LpB:E particles plays a dominant role in the concentration of Lp(a) subspecies and that a redistribution of Lp(a) subspecies occurs under the influence of the apoE content of triacyl glycerol-rich lipoprotein particles. Copyright (C) 2001 by W.B. Saunders Co mpany.