The influence of cholesteryl ester content on hepatocyte triolein emulsion uptake

When triolein emulsions are enriched with cholesteryl oleate they are more readily removed by primary rat hepatocytes and HepG2 cells via an apolipoprotein E-responsive pathway. The increment in the cholesteryl ester does not appreciably change the size of the emulsion or its affinity for the apo E protein. The cholesteryl ester enriched-emulsion demonstrates increased apo E-mediated HepG2-binding as well as endocytosis. The higher the content of cholesteryl ester of the particle, the greater was both the binding and the endocytosis. The increased endocytosis was associated with increased degradation of the apo E. Cholesteryl linoleate and palmitate produced the same effects as the oleate. Lecithin-cholesterol acyltransferase additions were also able to increase the HepG2 uptake of the emulsion. The data indicates that the increment in cholesterol ester occurring during maturation of plasma triacyglycerol-rich particles facilitates hepatic remnant assimilation by an apo E-dependent pathway.