Modulation of adhesion molecule expression on endothelial cells: to be or not to be?

The role of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors (statins) in modern rheumatology

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase commonly known as statins are widely used for treating hypercholesterolemia. However, there is much evidence to suggest that statins may have other properties in addition to their cholesterol-lowering effect. In particular, statins may neutralize post-translational prenylation of vitally important regulatory small GTPases, which are involved in several processes such as tissue fibrosis, cell maturation, apoptosis, immune cell maturation, and immune response. The beneficial effect of statins has been reported in animal and in vitro models as well as in some clinical studies. As they have an acceptable safety profile, statins may be considered, in selected cases, as a valuable concomitant therapy in the treatment of rheumatic and autoimmune disorders.

Immunomodulation by statins: Inhibition of cholesterol vs. isoprenoid biosynthesis

Due to their ability to inhibit the synthesis of cholesterol, statins are widely used in medical practice and are the principal therapy for hypercholesterolemia. In addition, various findings suggest that statins also exert anti-inflammatory properties and may so play a role in modulating the immune system. Because of these properties, statins could provide a potential treatment for various chronic inflammatory diseases, including neuroinflammatory disorders such as multiple sclerosis. Here, we will review the effect of statins on the expression and function of a variety of immune relevant molecules and the underlying mechanisms that contribute to the immunomodulatory properties of statins. In this discussion we will also evaluate the effects of statins on central nervous system cells to emphasize the potential of these agents in the treatment of neuroinflammatory disorders.

Statins and autoimmune diseases

Besides the well-known lipid-lowering effect, statins display nonlipid-lowering pharmacological activities. In vitro and in vivo studies suggest that statins have direct anti-inflammatory, anti-thrombotic and plaque-stabilizing effects via a number of mechanisms. A direct immunomodulatory effect has been also demonstrated in in vitro and in vivo experimental models. In addition to traditional risk factors, systemic inflammation, immune-mediated responses and thrombophilia have been suggested to play a major role in sustaining the premature atherosclerosis in autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus. This review focuses on the anti-inflammatory and immunomodulating mechanisms of statins as demonstrated in in vitro and in vivo experimental models, providing new insights for the use of statins in treating systemic autoimmune diseases both for their anti-atherosclerotic activity and for their pleiotropic effects on inflammation, haemostasis and the immune responses.