HPS2-THRIVE, AIM-HIGH and dal-OUTCOMES: HDL-cholesterol under attack

Regulation of Platelet Function by HDL

Over the past decade, increasing the capacity of HDL (high-density lipoprotein) cholesterol to mediate macrophage reverse cholesterol transport has been a target of interest in the treatment of cardiovascular diseases (CVDs). However, clinical studies reporting the limited efficacy of HDL or its main apolipoprotein, APOA1, in reducing cardiovascular events have emerged. Although HDL cholesterol is unlikely to play a direct causal role in CVD, its inverse, albeit modest, association with CVD risk, consistently observed in large population studies, suggests it may influence alternative pathways beyond cholesterol metabolism. Given the diverse functions of HDL and its components, it is conceivable that its impact on CVD occurs through less direct mechanisms. A potential hypothesis is that HDL modulates platelet function, a crucial player in the initiation and progression of atherothrombosis, which may contribute to its observed relationship with CVD risk. In this review, we focus on how HDL and its components, with an emphasis on APOA1, interact with platelets (and their precursors or activation products) to modulate atherothrombotic responses.

CANHEART: Is HDL cholesterol a cardiovascular specific risk factor?

Initial observational studies have identified high-density lipoprotein cholesterol (HDL-C) as an independent predictor of cardiovascular (CV) risk, even in patients on optimal statin therapy. However, the notion that higher HDL-C is better, has been seriously challenged by the results from several recent clinical and genetic trials. Data from the CANHEART study serve to clarify the relation between HDL-C and cause-specific mortality. Individuals with lower HDL-C levels were independently associated with higher risk of CV, cancer, and non-CV/non-cancer mortality compared with individuals in the reference ranges of HDL-C levels. Given the similarities in associations between HDL-C and CV as swell as non-CV outcomes, it is likely that HDL-C level serve as a marker of risk rather than a causal CV specific risk factor.