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Am J Pathol. 2012 Sep;181(3):993-1006. doi: 10.1016/j.ajpath.2012.05.028. Epub 2012 Jul 13.

Interference with RhoA-ROCK signaling mechanism in autoreactive CD4+ T cells enhances the bioavailability of 1,25-dihydroxyvitamin D3 in experimental autoimmune encephalomyelitis.

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  • 1Department of Pediatrics, Darby Children's Research Institute, Medical University of South Carolina, Charleston, USA.


Vitamin D deficiency is a major risk factor for central nervous system (CNS) demyelinating diseases including multiple sclerosis (MS) and its animal model, that of experimental autoimmune encephalomyelitis (EAE). Both vitamin D(3) and 1, 25-dihydroxyviatmin-D(3) (calcitriol) had beneficial effects in EAE/MS. However, the exact cause of vitamin D deficiency in EAE/MS is not clear. Previously, we documented that lovastatin (LOV) provides protection in EAE animals via inhibition of RhoA-ROCK signaling. Herein, we demonstrate that LOV prevents the lowering of circulating 25-hydroxyvitamin-D(3) and 1,25-dihydroxyviatmin-D(3) levels including 1,25-dihydroxyviatmin-D(3) levels in the peripheral lymphoid organs and CNS of treated EAE animals. These effects of LOV were attributed to enhanced expression of vitamin D synthesizing enzyme (1α-hydroxylase) in kidney and the CNS, with corresponding reduction of vitamin D catabolizing enzyme (24-hydorxylase) expression in the CNS of EAE animals via inhibition of RhoA-ROCK signaling. Ex vivo and in vitro studies established that autoreactive Th1/Th17 cells had higher expression of 24-hydroxylase than Th2/T regulatory cells, that was reverted by LOV or ROCK inhibitor. Interestingly, LOV-mediated regulation of vitamin D metabolism had improved vitamin D(3) efficacy to confer protection in EAE animals and that was ascribed to the LOV- and calcitriol-induced immunomodulatory synergy. Together, these data provide evidence that interfering with RhoA-ROCK signaling in autoreactive Th1/Th17 cells can improve vitamin D(3) efficacy in clinical trials of MS and related neurodegenerative disorders.

Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

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