Importance of macrophage cholesterol content on the flux of cholesterol mass.
Net flux of cholesterol represents the difference between efflux and influx and can result in net cell-cholesterol accumulation, net cell-cholesterol depletion, or no change in cellular cholesterol content. We measured radiolabeled cell-cholesterol efflux and cell-cholesterol mass using cholesterol-normal and -enriched J774 and elicited mouse peritoneal macrophage cells. Net cell-cholesterol effluxes were observed when cholesterol-enriched J774 cells were incubated with 3.5% apolipoprotein (apo) B depleted human serum, HDL(3), and apo A-I. Net cell-cholesterol influxes were observed when cholesterol-normal J774 cells were incubated with the same acceptors except apo A-I. When incubated with 2.5% individual sera, cholesterol mass efflux in free cholesterol (FC)-enriched J774 cells correlated with the HDL-cholesterol (HDL-C) concentrations (r(2) = 0.4; P=0.003), whereas cholesterol mass influx in cholesterol-normal J774 cells correlated with the LDL cholesterol (LDL-C) concentrations (r(2) = 0.6; P<0.0001) of the individual sera. A positive correlation was observed between measurements of [(3)H]cholesterol efflux and reductions in cholesterol mass (r(2) = 0.4; P=0.001) in FC-enriched J774 cells. In conclusion, isotopic efflux measurements from cholesterol-normal or cholesterol-enriched cells provide an accurate measurement of relative ability of an acceptor to remove labeled cholesterol under a specific set of experimental conditions, i.e., efflux potential. Moreover, isotopic efflux measurements can reflect changes in cellular cholesterol mass if the donor cells are enriched with cholesterol.
Sankaranarayanan
Sandhya
S
Division of Gastroenterology, Hepatology, and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
de la Llera-Moya
Margarita
M
Drazul-Schrader
Denise
D
Asztalos
Bela F
BF
Weibel
Ginny L
GL
Rothblat
George H
GH
D000818:Animals; D002460:Cell Line; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D006801:Humans; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D051379:Mice; D015203:Reproducibility of Results
D002784:Cholesterol