CCR5 in multiple sclerosis : expression, regulation and modulation by statins

Abstract

Activation of microglia, the macrophages of the central nervous system, is a key element in multiple sclerosis (MS) lesion development and is characterized by enhanced expression of both classes of major histocompatibility complex (MHC) molecules. This enhanced expression results from increased levels of several transcription factors involved in MHC gene expression. In addition, microglial activation in MS is characterized by enhanced motility. We show that the expression of the chemokine receptor CCR5, a mediator of cell movement, is increased on microglia, macrophages and astrocytes in MS lesions. Additionally, we have determined that CCR5 transcription is regulated by the transcription factor CREB-1, which is also involved in MHC gene expression, and is highly expressed in MS lesions. Because of their immunomodulatory properties, statins (cholesterol lowering drugs) are recently being considered as a possible treatment for MS. We have determined that statins decrease expression of amongst others MHC and CCR5 molecules by inhibiting the transport of these molecules to the cell surface. In addition, we show that statins reduce the motility of microglia and inhibit the differentiation of blood-derived monocytes into dendritic cells, indicating that statins indeed affect critical immune functions and might prove to be beneficial for treatment of MS patients.