2 H 2 O-Based High-Density Lipoprotein Turnover Method for the Assessment of Dynamic High-Density Lipoprotein Function in Mice

Objective— High-density lipoprotein (HDL) promotes reverse cholesterol transport from peripheral tissues to the liver for clearance. Reduced HDL-cholesterol (HDLc) is associated with atherosclerosis; however, as a predictor of cardiovascular disease, HDLc has limitations because it is not a direct marker of HDL functionality. Our objective was to develop a mass spectrometry–based method for the simultaneous measurement of HDLc and ApoAI kinetics in mice, using a single 2 H 2 O tracer, and use it to examine genetic and drug perturbations on HDL turnover in vivo. Approach and Results— Mice were given 2 H 2 O in the drinking water, and serial blood samples were collected at different time points. HDLc and ApoAI gradually incorporated 2 H, allowing experimental measurement of fractional catabolic rates and production rates for HDLc and ApoAI. ApoE −/− mice displayed increased fractional catabolic rates ( P P Conclusions— 2 H 2 O-labeling can be used to measure HDLc and ApoAI flux in vivo, and to assess the role of genetic and pharmacological interventions on HDL turnover in mice. Safety, simplicity, and low cost of the 2 H 2 O-based HDL turnover approach suggest that this assay can be scaled for human use to study effects of HDL targeted therapies on dynamic HDL function.