title: Endocannabinoids drive the acquisition of an alternative phenotype in microglia.
abstract: The ability of microglia to acquire diverse states of activation, or phenotypes, reflects different features that are determinant for their contribution to homeostasis in the adult CNS, and their activity in neuroinflammation, repair or immunomodulation. Despite the widely reported immunomodulatory effects of cannabinoids in both the peripheral immune system and the CNS, less is known about how the endocannabinoid signaling system (eCBSS) influence the microglial phenotype. The general aim of the present study was to investigate the role of endocannabinoids in microglia polarization by using microglia cell cultures. We show that alternative microglia (M2a) and acquired deactivated microglia (M2c) exhibit changes in the eCB machinery that favor the selective synthesis of 2-AG and AEA, respectively. Once released, these eCBs might be able to act through CB1 and/or CB2 receptors in order to influence the acquisition of an M2 phenotype. We present three lines of evidence that the eCBSS is critical for the acquisition of the M2 phenotype: (i) M2 polarization occurs on exposure to the two main endocannabinoids 2-AG and AEA in microglia cultures; (ii) cannabinoid receptor antagonists block M2 polarization; and (iii) M2 polarization is dampened in microglia from CB2 receptor knockout mice. Taken together, these results indicate the interest of eCBSS for the regulation of microglial activation in normal and pathological conditions.
authors.affiliation: Department of Functional and Systems Neurobiology, Neuroimmunology Group, Instituto Cajal, CSIC, Madrid, Spain. Electronic address: miriammecha@cajal.csic.es.
authors.forename: M
authors.initials: M
authors.lastname: Mecha
authors.affiliation: Department of Functional and Systems Neurobiology, Neuroimmunology Group, Instituto Cajal, CSIC, Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Feliú
authors.affiliation: Department of Functional and Systems Neurobiology, Neuroimmunology Group, Instituto Cajal, CSIC, Madrid, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Carrillo-Salinas
authors.affiliation: Department of Organic Chemistry, Chemistry Faculty, University Complutense of Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Rueda-Zubiaurre
authors.affiliation: Department of Organic Chemistry, Chemistry Faculty, University Complutense of Madrid, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Ortega-Gutiérrez
authors.affiliation: Clinical Neurophysiology Service, Hospital Universitario la Princesa, Madrid, Spain.
authors.forename: R García
authors.initials: RG
authors.lastname: de Sola
authors.affiliation: Department of Functional and Systems Neurobiology, Neuroimmunology Group, Instituto Cajal, CSIC, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Guaza
mesh_terms: D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism*; D016764:Cell Polarity; D002478:Cells, Cultured; D063388:Endocannabinoids / Q000378:metabolism*; D005989:Glycerides / Q000378:metabolism*; D008071:Lipoprotein Lipase / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000378:metabolism / Q000502:physiology*; D010641:Phenotype; D053284:Polyunsaturated Alkamides / Q000378:metabolism*; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors; D043885:Receptor, Cannabinoid, CB2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001095:Arachidonic Acids; D063388:Endocannabinoids; D005989:Glycerides; D053284:Polyunsaturated Alkamides; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; C094503:glyceryl 2-arachidonate; D008071:Lipoprotein Lipase; C078814:anandamide
keywords: 2-AG; AEA; CB2 receptors; M2 polarization; Microglia