The Rise and Fall "ing" of the HDL Hypothesis

Area of Science:

• Cardiovascular Science
• Lipid Metabolism
• Pharmacology

Background:

• Epidemiological studies initially suggested high-density lipoprotein cholesterol (HDLc) inversely correlates with coronary heart disease (CHD), supporting a cardioprotective role for HDL.
• Recent data indicate a U-shaped correlation between HDLc and CHD, and clinical trials with HDLc-raising drugs have failed to reduce cardiovascular events.

Purpose of the Study:

• To challenge the established hypothesis that HDL has a cardioprotective role.
• To investigate the role of HDL quality and de novo synthesis of apolipoprotein A-I (apo A-I) in reverse cholesterol transport.
• To propose new therapeutic strategies for cardiovascular disease.

Main Methods:

• Review of epidemiological data and randomized clinical trials.
• Analysis of the relationship between HDLc levels, HDL function, and cardiovascular outcomes.
• Hypothesis formulation regarding HDL quality and apo A-I synthesis.

Main Results:

• Existing evidence challenges the direct cardioprotective role of elevated HDLc.
• Drugs increasing HDLc or inhibiting HDL turnover did not consistently reduce adverse cardiovascular events.
• Current therapies may produce ineffective HDL particles lacking optimal reverse cholesterol transport function.

Conclusions:

• The cardioprotective role of HDL may depend on its quality and function, particularly de novo apo A-I synthesis, rather than solely on plasma HDLc levels.
• Future therapeutic strategies should aim to enhance HDL quality and de novo apo A-I production.
• Clinical trials should evaluate novel drugs targeting HDL synthesis and function for cardiovascular disease prevention.