Mechanisms involved in the remyelinating effect of sildenafil

Díaz-Lucena, D., Gutierrez-Mecinas, M., Moreno, B., Martínez-Sánchez, J. L., Pifarré, P. and García, A. (2018) Mechanisms involved in the remyelinating effect of sildenafil. Journal of Neuroimmune Pharmacology, 13(1), pp. 6-23. (doi: 10.1007/s11481-017-9756-3) (PMID:28776122)

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Remyelination occurs in demyelinated lesions in multiple sclerosis (MS) and pharmacological treatments that enhance this process will critically impact the long term functional outcome in the disease. Sildenafil, a cyclic GMP (cGMP)-specific phosphodiesterase 5 inhibitor (PDE5-I), is an oral vasodilator drug extensively used in humans for treatment of erectile dysfunction and pulmonary arterial hypertension. PDE5 is expressed in central nervous system (CNS) neuronal and glial populations and in endothelial cells and numerous studies in rodent models of neurological disease have evidenced the neuroprotective potential of PDE5-Is. Using myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) as a MS model, we previously showed that daily administration of sildenafil starting at peak disease rapidly ameliorates clinical symptoms while administration at symptoms onset prevents disease progression. These beneficial effects of the drug involved down-regulation of adaptive and innate immune responses, protection of axons and oligodendrocytes (OLs) and promotion of remyelination. In this work we have investigated mechanisms involved in the remyelinating effect of sildenafil. Using demyelinated organotypic cerebellar slice cultures we demonstrate that sildenafil stimulates remyelination by direct effects on CNS cells in a nitric oxide (NO)-cGMP-protein kinase G (PKG)-dependent manner. We also show that sildenafil treatment enhances OL maturation and induces expression of the promyelinating factor ciliary neurotrophic factor (CNTF) in spinal cord of EAE mice and in cerebellar slice cultures. Furthermore, we demonstrate that sildenafil promotes a M2 phenotype in bone marrow derived macrophages (BMDM) and increases myelin phagocytosis in these cells and in M2 microglia/macrophages in the spinal cord of EAE mice. Taken together these data indicate that promotion of OL maturation directly or through induction of growth factor expression, regulation of microglia/macrophage inflammatory phenotype and clearance of myelin debris may be relevant mechanisms involved in sildenafil enhancement of remyelination in demyelinated tissue and further support the contention that this well tolerated drug could be useful for ameliorating MS pathology.

Item Type:Articles
Keywords:CNTF, sildenafil, macrophage phenotypes, multiple sclerosis, myelin phagocytosis, remyelination.
Glasgow Author(s) Enlighten ID:Gutierrez-Mecinas, Dr Maria
Authors: Díaz-Lucena, D., Gutierrez-Mecinas, M., Moreno, B., Martínez-Sánchez, J. L., Pifarré, P., and García, A.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
Journal Name:Journal of Neuroimmune Pharmacology
ISSN (Online):1557-1904
Published Online:03 August 2017
Copyright Holders:Copyright © 2017 Springer Science+Business Media, LLC
First Published:First published in Journal of Neuroimmune Pharmacology 13(1): 6-23
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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