Antioxidants, cell suicide and coronary heart disease – University of Reading
18 July 2001The underlying cause of coronary heart disease is the build up of cholesterol in atherosclerotic lesions in the walls of arteries in the heart. This cholesterol comes from low density lipoprotein (LDL) in the blood. The main theory to explain why atherosclerotic lesions form is that LDL gets into the arterial wall and is then made 'rancid' by an oxidative process involving free radicals, in a similar way to old fat becoming rancid.
There is currently a great deal of interest in the ways in which cells in the body actually actively decide to commit suicide, which has the scientific name of apoptosis. Apoptosis occurs in atherosclerotic lesions and macrophages and smooth muscle cells are two of the cells that are affected. Oxidised LDL is known to be capable of persuading both of these types of cells to commit suicide. Ms Lynda Harris and Dr David Leake in the School of Animal and Microbial Sciences at Reading, in collaboration with Professor Giovanni Mann at King's College London, are looking at the effects of vitamin C on apoptosis caused by oxidised LDL. They have shown that vitamin C protects smooth muscle cells against apoptosis caused by oxidised LDL, but that it actually makes it worse in macrophages.
If may be that the suicide of smooth muscle cells is a bad thing in atherosclerotic lesions, because it weakens the arterial wall and may lead to the tearing of the wall that leads to a heart attack. The suicide of macrophages may arguably be a good thing, however, because it would stop the macrophages from releasing dangerous enzymes that would break down the arterial wall. Vitamin C may therefore in theory have a beneficial effect by decreasing the suicide of smooth muscle cells, but increasing the suicide of macrophages, in atherosclerotic lesions.
The team is now trying to work out the exact details of how vitamin C affects apoptosis in these cells. Clinical trials are currently underway elsewhere into the effects of giving patients with coronary heart disease vitamin C and the results of these trials should be very interesting, whatever they show.
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