Although the link between high cholesterol and atherosclerosis has been known for a long time, the mechanism by which cholesterol actually causes atherosclerosis has been unknown.
New research performed by scientists at St. Louis University School of Medicine may shed some light on the answer. Scientists found that cholesterol reduces the protective effect of transforming growth factor beta (TGF-B), a protein known to prevent the development of atherosclerosis.
When high amounts of TGF-B are present, heart and blood vessel cells are protected against heart disease. However, the study showed that mice with high amounts of cholesterol experienced reduced interaction of TGF-B with cardiovascular cells. That causes plaques to build up on the lining of blood vessels, laying down the foundation for the development of atherosclerosis and, thus, heart disease.
Scientists also found that statins, such as fluvastatin and lovastatin, increased the amount of TGF-B circulating in the blood. Statins are already known for not only lowering cholesterol, but for preventing of heart disease. The scientists conducting this study suspect that this mechanism may be the reason they are so effective in preventing heart disease.
Another interesting thing to note is that some researchers contend that statins may hold another potential benefit: cancer prevention. Low levels of TGF-B are also linked to the development of cancer.
This is just the beginning, and more research is needed to understand how exactly atherosclerosis develops. Still, this finding gives us some insight as to why high cholesterol levels cause atherosclerosis and may open the door to newer options for preventing, or possibly halting, the development of atherosclerosis in the future.
Source:
Chen CL, Liu IH, Fliesler SJ, Han X et al. "Cholesterol suppresses cellular TGF-B responsiveness: implications in atherogenesis." J Cell Sci. e-pub 18 Sept 2007.
