New molecular targets for cholesterol-lowering therapy

The use of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) in randomized clinical trials has established that cholesterol-lowering treatment reduces the risk of both cardiovascular and total mortality. This reduction in risk occurs in patients with or without existing cardiovascular disease and in patients with high or average plasma cholesterol concentrations. Aggressive treatment to lower plasma cholesterol has been shown to slow progression of atherosclerosis and in some instances may be as successful as angioplasty in reducing ischemic events. These studies suggest that reduction of plasma cholesterol to levels even below 100 mg/dl might be desirable. New targets for cholesterol-lowering therapy with mechanisms of action different from the statins have been identified. One of these targets is the Na+-dependent bile acid transporter that is expressed in the terminal ileum. This protein is responsible for recycling bile acids from the intestine to the liver. Several compounds that demonstrate the ability to decrease transporter activity and to lower plasma cholesterol have been investigated. Absorption of cholesterol from the small intestine is another potential target. Compounds that inhibit cholesterol absorption may act by interacting stoichiometrically with cholesterol within the intestinal lumen or substoichiometrically, presumably within the enterocyte. Finally, the transcriptional regulation of cholesterol 7 alpha-hydroxylase by members of the nuclear receptor superfamily provides at least two other molecular targets for cholesterol-lowering drugs.