Immunomodulator activity of 3-hydroxy-3-methilglutaryl-CoA inhibitors

Statins, inhibitors of 3-hydroxy-3-methylglutaryl-CoA are best known for their lipid-lowering effects but they also possess immunomodulatory properties that are, at least in part, independent of changes in serum cholesterol. Some recent clinical trials (eg. PROVE-IT) have shown that statins exert beneficial cardiovascular effects independently of the resultant level of LDL cholesterol. These "pleiotropic" effects seem to be due to inhibition of prenylation of several proteins such as the small GTP-binding proteins Ras and Rho, and to the disruption, or depletion, of cholesterol rich membrane micro-domains (membrane rafts). Through these pathways statins are able to modulate immune responses by modulating cytokine levels and by affecting the function of cells involved in both innate and adaptive responses. Over the past decade, a large number of studies reported a prominent role of inflammation and immune response in atherosclerosis, thus, the ability of statins to modulate immune-inflammatory processes could explain their cardiovascular beneficial effects beyond lipid-lowering effects. Moreover, various studies demonstrated beneficial effects of statins in inflammatory and auto-immune diseases, such as rheumatoid arthritis, multiple sclerosis and others. The purpose of this review is to summarize clinical and experimental evidence of immunomodulatory properties of these drugs, highlighting their clinical and, thus, therapeutic implications.