Objective: To study the relationship between apolipoprotein (apo) CIII and apoE VLDL, IDL and LDL containing lipoproteins in hyperlipidemics.
Methods: 10hypercholesterolemics (HC) and 13 hypertriglyceridemics (HTG) were compared to 12 normolipidemics (N). 16 apoβ lipoprotein particle types were separated by first using anti-apoE and anti-apoCIII immunoaffinity chromatography in sequence and then ultracentrifugation [light VLDL, dense VLDL, IDL and LDL, with apo CIII with or without apo E (C+E+, C+E-), or without apoCIII with or without apoE (C-E+, C-E-)].
Results: HTG had 2-fold higher concentrations of C+E+ and C+E-. In HTG, most of the C+ particles were in VLDL (75-80%), while in N and HC most were in IDL and LDL. The VLDL C+E+ and C+E- were the most triglyceriderich and cholesterol rich of the particles , and had 1.5-2 fold higher lipid content in HTG than in other patient. HTG had similar concentration of E-C- particles to N, but the E-C- particles were distributed more to light VLDL than to denser fractions as in N and HC. HC compared to the others had 2 fold higher concentrations of C-E- in each density fraction. C-E+ particles were the least prevalent, comprising <10% of particles in all groups. Conclusion: Thus, HTG are distinguished from N and HC by increased apoCIII-containing light VLDL (C+E+, C+E-) that are rich in cholesterol and triglyceride. In contrast, HC are characterized by high concentrations of E-C- particles distributed to denser lipoproteins, particularly LDL, the overall particle type distribution is similar to that of N. The presence of absence of apoE on apoβ lipoproteins does not discriminate the lipoprotein pattern among the patient groups as well as apoCIII. Therefore, light VLDL particles with apoCIIII may play a central role in establishing the lipoprotein pattern of HTG, and have the potential of promoting atherosclerosis.
