PLASMALOGEN PHOSPHOLIPIDS ARE INVOLVED IN HDL-MEDIATED CHOLESTEROL EFFLUX - INSIGHTS FROM INVESTIGATIONS WITH PLASMALOGEN-DEFICIENT CELLS

Plasmalogens are ether-glycerophospholipids that exist in all mammalia n cells, but their physiologcal function remains thus far an enigma. I t has been previously suggested that the association of high-density l ipoprotein (HDL) with cellular phospholipid is a prerequisite for the process of HDL-mediated cholesterol efflux (HDL-MCE). To investigate o ur hypothesis that plasmalogens might play a role in HDL-MCE, we used a model composed of plasmalogen-deficient cells including RAW mutant m acrophages and fibroblasts from patients with rhizomelic chondrodyspla sia punctata type II. In mutant macrophages, HDL-MCE was reduced by 57 % compared to control macrophages, after 16 hours. A similar phenomeno n was observed in plasmalogen-deficient patients fibroblasts. Incubati on of plasmalogen-deficient fibroblasts with 1-0-hexadecyl-sn-glycerol , which restored plasmalogen levels to that of control cells, resulted in a 35% increase in HDL-MCE, compared to a 10% increment in controls . The novel finding that HDL-MCE is reduced in plasmalogen-deficient c ells and increases following plasmalogen restoration leads us to sugge st that plasmalogen has an important function in the mediation of cell ular cholesterol efflux, (C) 1998 Academic Press.