SEATTLE - U.S. scientists say they've discovered cholesterol causes atherosclerosis by disrupting a network of interacting immune system proteins. University of Washington researchers studied the role of macrophages, immune-system cells that destroy proteins derived from cholesterol. They discovered that when macrophages become overloaded with such proteins, they become what scientists have called foam cells, due to their foamy appearance, and contribute to the development of atherosclerosis. The researchers also found drugs that lower cholesterol levels and inflammation help restore the macrophage network to more normal functioning. The scientists said their findings should change the way heart disease is treated, making the goal of treatment the restoration of functioning of a disrupted protein network, rather than the reduction of cholesterol levels. The study that included Lev Becker, Sina Gharib, Angela Irwin, Ellen Wijsman, Tomas Vaisar, John Oram, and Jay Heineckeappears in the journal Cell Metabolism.