Atherosclerosis: Lipoproteins, cell biology and vascular physiology

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The world is confronting a major new epidemic of premature heart disease that is being driven by a global increase in obesity. There are several factors that contribute to the increased risk of heart disease in overweight and obese people. One is a low blood level of the “good” HDL cholesterol that normally protects against heart disease. Another relates to a decreased ability to remove cholesterol from the walls of arteries where it builds up to cause heart disease. A third is the fact that obesity is associated with a state of chronic inflammation of the blood vessels. This inflammation not only accelerates the development of heart disease but also makes people who have cholesterol accumulated in their arteries more likely to actually have a heart attack. And a fourth is the fact that the lining of blood vessels does not function normally in overweight and obese people. This loss of normal function is a very early sign of future heart disease. These factors are closely inter-related, with the “good” HDL playing a central role in removing cholesterol from arteries, inhibiting arterial inflammation and promoting normal function and repair of the lining of blood vessels. HDL is complex, consisting of a mixture of several subpopulations of particles that vary in shape, size and composition. Furthermore, these HDL subpopulations are continually remodelled as they circulate in blood in reactions promoted by a number of blood factors that change their size and composition. A major component of the research to be conducted in this program relates to understanding how the HDL subpopulations in human blood are regulated and how they protect against heart disease. The applicants have already made major contributions to understanding the functions of the “good” HDLs, how they take cholesterol out of cells in the artery wall, how they inhibit inflammation of the arteries and how they improve the function of the artery lining. We propose to extend these studies to establish how these protective functions can be enhanced, to find out which of the HDL subpopulations are most protective, and to identify how to increase the most protective HDLs in people at risk of heart disease.