Free cholesterol transfer to high-density lipoprotein (HDL) upon triglyceride lipolysis underlies the U-shape relationship between HDL-cholesterol and cardiovascular disease

Background: Low concentrations of high-density lipoprotein cholesterol (HDL-C) represent a well-established cardiovascular risk factor. Paradoxically, extremely high HDL-C levels are equally associated with elevated cardiovascular risk, resulting in the U-shape relationship of HDL-C with cardiovascular disease. Mechanisms underlying this association are presently unknown. We hypothesised that the capacity of high-density lipoprotein (HDL) to acquire free cholesterol upon triglyceride-rich lipoprotein (TGRL) lipolysis by lipoprotein lipase underlies the non-linear relationship between HDL-C and cardiovascular risk. Methods: To assess our hypothesis, we developed a novel assay to evaluate the capacity of HDL to acquire free cholesterol (as fluorescent TopFluor® cholesterol) from TGRL upon in vitro lipolysis by lipoprotein lipase. Results: When the assay was applied to several populations markedly differing in plasma HDL-C levels, transfer of free cholesterol was significantly decreased in low HDL-C patients with acute myocardial infarction (−45%) and type 2 diabetes (–25%), and in subjects with extremely high HDL-C of >2.59 mmol/L (>100 mg/dL) (−20%) versus healthy normolipidaemic controls. When these data were combined and plotted against HDL-C concentrations, an inverse U-shape relationship was observed. Consistent with these findings, animal studies revealed that the capacity of HDL to acquire cholesterol upon lipolysis was reduced in low HDL-C apolipoprotein A-I knock-out mice and was negatively correlated with aortic accumulation of [3H]-cholesterol after oral gavage, attesting this functional characteristic as a negative metric of postprandial atherosclerosis. Conclusions: Free cholesterol transfer to HDL upon TGRL lipolysis may underlie the U-shape relationship between HDL-C and cardiovascular disease, linking HDL-C to triglyceride metabolism and atherosclerosis. Fil: Feng, Ma. Inserm; Francia. Université Pierre et Marie Curie; Francia Fil: Darabi, Maryam. Université Pierre et Marie Curie; Francia. Inserm; Francia Fil: Tubeuf, Emilie. Inserm; Francia. Université Pierre et Marie Curie; Francia Fil: Canicio, Aurélie. Université Pierre et Marie Curie; Francia. Inserm; Francia Fil: Lhomme, Marie. Institute Of Cardiometabolism And Nutrition; Francia Fil: Frisdal, Eric. Inserm; Francia. Université Pierre et Marie Curie; Francia Fil: Lanfranchi Lebreton, Sandrine. Université Pierre et Marie Curie; Francia Fil: Matheron, Lucrèce. Université Pierre et Marie Curie; Francia Fil: Rached, Fabiana. Université Pierre et Marie Curie; Francia. Inserm; Francia Fil: Ponnaiah, Maharajah. Institute Of Cardiometabolism And Nutrition; Francia Fil: Serrano, Carlos V.. Instituto Do Coracao Do Hospital Das Clinicas; Brasil Fil: Santos, Raul D.. Instituto Do Coracao Do Hospital Das Clinicas; Brasil Fil: Brites, Fernando Daniel. Universidad de Buenos Aires; Argentina. Instituto Do Coracao Do Hospital Das Clinicas; Brasil Fil: Bolbach, Gerard. Université Pierre et Marie Curie; Francia Fil: Gautier, Emmanuel. Université Pierre et Marie Curie; Francia. Inserm; Francia Fil: Huby, Thierry. Inserm; Francia. Université Pierre et Marie Curie; Francia Fil: Carrie, Alain. Inserm; Francia. Université Pierre et Marie Curie; Francia Fil: Bruckert, Eric. Inserm; Francia. Université Pierre et Marie Curie; Francia Fil: Guerin, Maryse. Université Pierre et Marie Curie; Francia. Inserm; Francia Fil: Couvert, Philippe. Inserm; Francia. Université Pierre et Marie Curie; Francia Fil: Giral, Philippe. Université Pierre et Marie Curie; Francia. Inserm; Francia Fil: Lesnik, Philippe. Université Pierre et Marie Curie; Francia. Inserm; Francia Fil: Le Goff, Wilfried. Université Pierre et Marie Curie; Francia. Inserm; Francia Fil: Guillas, Isabelle. Inserm; Francia. Université Pierre et Marie Curie; Francia Fil: Kontush, Anatol. Inserm; Francia. Université Pierre et Marie Curie; Francia