Does chylomicron composition differ in broad-beta disease compared to other hyperlipidemias before and after an oral fat load?
Cholesterol-rich chylomicrons in fasting broad-beta disease likely originate as normal triglyceride-rich particles in the intestine and become cholesterol-enriched through lipolysis and transfer processes.
Chylomicron (primary particles) were detected by polyvinylpyrollidone (PVP) flocculation in plasma collected after an overnight fast from eight hyperlipemic subjects with broad-beta disease (type III hyperlipoproteinemia). The composition of these chylomicrons was abnormal: relatively poor in triglyceride and rich in cholesterol, giving rise to a triglyceride/cholesterol ratio of 400 with S(f) < 400 lipoproteins from subjects with the different forms of hyperlipoproteinemia revealed equal cholesterol enrichment of chylomicrons from a subject with mixed lipemia and from a subject with broad-beta disease in media of equivalent cholesterol content. These experiments suggested neither excessive avidity of chylomicrons for cholesterol uptake nor excessive influence of S(f) < 400 lipoproteins upon chylomicron composition in broad-beta disease.Thus, results in this study suggest that the cholesterol-rich chylomicrons observed in subjects with broad-beta disease after an overnight fast may originate in the intestine as particles of normal composition (chiefly dietary triglyceride) but assume a composition which is relatively rich in cholesterol through processes of lipolysis and cholesterol transfer among circulating lipoproteins which may not be unique to broad-beta disease.
Hazzard et al. (Thu,) studied this question.