Research ReportAdministration of 2-arachidonoylglycerol ameliorates both acute and chronic experimental autoimmune encephalomyelitis
Research Highlights
► Exogenous 2AG-treatment is applied for the first time in PLP- and MOG-induced EAE. ► 2AG delayed disease onset and reduced relapse severity and long-term disability in EAE. ► 2AG inhibited lymphocyte-activation and induced apoptosis. ► 2AG-treatment reduced axonal pathology in the chronic EAE model. ► 2AG-induced neuroprotection may be microglia-related in acute EAE.
Introduction
Experimental autoimmune encephalomyelitis (EAE) is an experimental model of immune-mediated demyelination and axonopathy within the central nervous system (CNS) of susceptible animals, using the triggering of various myelin antigens (Grigoriadis et al., 2004, Grigoriadis et al., 2006).
Among the several factors that play a role in the pathogenesis of both EAE and MS is the endocannabinoid (eCB) system (Centonze et al., 2007a, Shohami and Mechoulam, 2006, Witting et al., 2006) which includes the endogenous cannabinoids (eCB) N-arachidonoylethanolamine (anandamide) (Devane et al., 1992) and 2-arachidonoylglycerol (2AG) (Mechoulam et al., 1995, Sugiura et al., 1995). Both compounds act via the CB1 and CB2 receptors (CB1R and CB2R, respectively) (Matsuda et al., 1990, Munro et al., 1993) or the recently described non-CB receptors (De Petrocellis and Di Marzo, 2010). The CB1R are expressed mainly in the brain, pituitary gland, immune cells, and reproductive tissues, whereas CB2R are found primarily on immune cells and brain as well (Onaivi et al., 2006). Anandamide binds with higher affinity to the brain CB1R than CB2R, whereas 2AG exhibits similar affinity for both receptors (Devane et al., 1992, Pandey et al., 2009). 2AG has been suggested to be the main natural ligand of both central (neural) and peripheral (immune) cannabinoid receptors (Berdyshev, 2000, Gonsiorek et al., 2000, Sugiura et al., 2000, Sugiura et al., 2004) with multiple effects on lymphocytes (Lee et al., 1995, Ouyang et al., 1998, Rockwell et al., 2006), microglial cells (Carrier et al., 2004), and macrophages function (Gallily et al., 2000). Based on these data, it has been assumed that 2AG could be a potent modulator of immune-mediated CNS diseases (Centonze et al., 2007b, Consroe, 1998).
Various pathological conditions increase the “eCB tone” (Franklin et al., 2003, Hashimotodani et al., 2007, Witting et al., 2004b, Witting et al., 2006), and it has been postulated that this response is neuroprotective (Franklin et al., 2003, Guzman et al., 2001, Mechoulam and Shohami, 2007, Nagayama et al., 1999, Panikashvili et al., 2001, Wallace et al., 2003). However, MS and EAE render a “dysregulation” of brain eCB response (Centonze et al., 2007a, Shohami and Mechoulam, 2006, Witting et al., 2006) and therefore constitute an exception from the “rule” of increased eCB tone noticed in other neuropathologies (Franklin et al., 2003, Panikashvili et al., 2001, Witting et al., 2004b).
Whatever the cause for this discrepancy, the rationale for interference with exogenously administered 2AG, an agonist of both CB1R and CB2R, is strongly supported by reports indicating that eCB receptor agonists or inhibitors have an impact on EAE (Baker et al., 2001, Cabranes et al., 2005). Moreover, based on the up-regulation of 2AG as a potential neuroprotective mechanism after mechanical CNS injury (Arevalo-Martin et al., 2010, Panikashvili et al., 2005, Shohami and Mechoulam, 2006), the exogenous administration of 2AG would confer a potential benefit in EAE and/or MS.
Based on previous findings (Shohami and Mechoulam, 2006, Witting et al., 2004a, Witting et al., 2006), the present study addressed the question of whether exogenously administered 2AG might have any effect on the clinical outcome in acute and chronic EAE models, the inflammatory or axonopathic processes, and the expression of CB1R and CB2R in the CNS. In addition, we used in vitro lymph node cell viability assays to test the effect of different 2AG doses under myelin-peptide-selective stimulation.
To our knowledge, this is the first time that exogenous 2AG is applied in acute PLP- and chronic MOG-induced EAE mouse models as an experimental therapy, apart from the study of Baker et al. (2001) in Biozzi mice and studies of endogenous eCD alterations (Centonze et al., 2007a, Witting et al., 2004a). Most importantly, the use of EAE models with either mild or severe clinical course highlights the spectrum of 2AG efficacy in autoimmune demyelination in the CNS.
Section snippets
2AG administration ameliorated clinical course of acute PLP-EAE in SJL/6 mice
The clinical course and disease characteristics of acute PLP-EAE are presented in Fig. 1 (panels A, C, and table included in the figure). Mice developed a monophasic disease without mortality. Control group developed the first clinical signs of EAE on days 11–12, reaching a clinical peak on day 16 (2.75 ± 1.47) (Fig. 1A) with high MMS (table included in the figure). 2AG-treated animals developed a milder disease (Fig. 1A), with significantly delayed disease onset until days 15–16 (Fig. 1C and
Discussion
In the present study, we demonstrated for the first time that exogenous administration of the endocannabinoid 2AG in EAE a) significantly ameliorated both acute and chronic EAE, indicating an impact on acute relapse severity and chronic progressive disability; b) significantly reduced mortality rate in severe MOG-EAE; c) had a significant antiproliferative effect on activated LNCs in vitro, concomitant with increased apoptosis of perivascular infiltrates in vivo; d) ameliorated the
Animal handling
Female SJL/6 and C57/Bl, 8 week-old mice, were purchased from Hellenic Pasteur Institute (Athens) and housed in the pathogen-free animal facility of the B' Neurological Department, AHEPA University Hospital. Animal experimentation was approved by Veterinary Directorate of Thessaloniki and was conducted under compliance with National Institutes of Health guidelines and European Community Directive 86/609/EEC, the Greek Government guidelines, and the local ethics committee. All possible adequate
Acknowledgments
This project has been funded by the General Secretariat for Research and Technology, Greek Ministry of Development, under a “PENED” research grant. Research in Jerusalem was supported by the US National Institute of Drug Abuse (DA-9789 to R.M.). The authors would like to thank Evangelia Nousiopoulou for excellent technical support.
References (79)
- et al.
The endocannabinoid 2-arachidonoylglycerol reduces lesion expansion and white matter damage after spinal cord injury
Neurobiol. Dis.
(2010) Cannabinoid receptors and the regulation of immune response
Chem. Phys. Lipids
(2000)- et al.
Decreased endocannabinoid levels in the brain and beneficial effects of agents activating cannabinoid and/or vanilloid receptors in a rat model of multiple sclerosis
Neurobiol. Dis.
(2005) - et al.
Changes in CB1 receptors in motor-related brain structures of chronic relapsing experimental allergic encephalomyelitis mice
Brain Res.
(2006) - et al.
Differential expression of the CB2 cannabinoid receptor by rodent macrophages and macrophage-like cells in relation to cell activation
Int. Immunopharmacol.
(2002) - et al.
The endocannabinoid system in targeting inflammatory neurodegenerative diseases
Trends Pharmacol. Sci.
(2007) Brain cannabinoid systems as targets for the therapy of neurological disorders
Neurobiol. Dis.
(1998)- et al.
Excitotoxicity in a chronic model of multiple sclerosis: neuroprotective effects of cannabinoids through CB1 and CB2 receptor activation
Mol. Cell. Neurosci.
(2007) - et al.
Transplanted neural precursor cells reduce brain inflammation to attenuate chronic experimental autoimmune encephalomyelitis
Exp. Neurol.
(2006) - et al.
Statistical analysis of data from studies on experimental autoimmune encephalomyelitis
J. Neuroimmunol.
(2005)
2-Arachidonylglycerol, an endogenous cannabinoid, inhibits tumor necrosis factor-alpha production in murine macrophages, and in mice
Eur. J. Pharmacol.
Cannabinoid CB2 receptors: immunohistochemical localization in rat brain
Brain Res.
Axonal damage in multiple sclerosis: a complex issue in a complex disease
Clin. Neurol. Neurosurg.
Neuroinflammation in multiple sclerosis: evidence for autoimmune dysregulation, not simple autoimmune reaction
Clin. Neurol. Neurosurg.
Specific detection of CB1 receptors; cannabinoid CB1 receptor antibodies are not all created equal!
J. Neurosci. Methods
Cannabinoids and cell fate
Pharmacol. Ther.
Amelioration of autoimmune neuroinflammation by recombinant human alpha-fetoprotein
Exp. Neurol.
Identification of an endogenous 2-monoglyceride, present in canine gut, that binds to cannabinoid receptors
Biochem. Pharmacol.
Cannabinoids and brain injury: therapeutic implications
Trends Mol. Med.
Protective effects of microglia in multiple sclerosis
Exp. Neurol.
Apoptosis of T cells in peripheral blood and cerebrospinal fluid is associated with disease activity of multiple sclerosis
J. Neuroimmunol.
Endocannabinoids and immune regulation
Pharmacol. Res.
Treating autoimmune demyelination by augmenting lymphocyte apoptosis in the central nervous system
J. Neuroimmunol.
R-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)-pyrrolo-[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphtalenylmethanone (WIN-2) ameliorates experimental autoimmune encephalomyelitis and induces encephalitogenic T cell apoptosis: partial involvement of the CB(2) receptor
Biochem. Pharmacol.
2-Arachidonoylglycerol: a possible endogenous cannabinoid receptor ligand in brain
Biochem. Biophys. Res. Commun.
Evidence that 2-arachidonoylglycerol but not N-palmitoylethanolamine or anandamide is the physiological ligand for the cannabinoid CB2 receptor. Comparison of the agonistic activities of various cannabinoid receptor ligands in HL-60 cells
J. Biol. Chem.
New perspectives in the studies on endocannabinoid and cannabis: 2-arachidonoylglycerol as a possible novel mediator of inflammation
J. Pharmacol. Sci.
Pathogenesis of tissue injury in MS lesions
J. Neuroimmunol.
Microglia in neuroregeneration
Microsc. Res. Tech.
CB2 cannabinoid receptors as an emerging target for demyelinating diseases: from neuroimmune interactions to cell replacement strategies
Br. J. Pharmacol.
Endocannabinoids control spasticity in a multiple sclerosis model
FASEB J.
Cannabinoid CB1 and CB2 receptors and fatty acid amide hydrolase are specific markers of plaque cell subtypes in human multiple sclerosis
J. Neurosci.
Cannabinoid CB2 receptors in human brain inflammation
Br. J. Pharmacol.
Role of macrophages/microglia in multiple sclerosis and experimental allergic encephalomyelitis
J. Mol. Med.
Development of microglia in the cerebral white matter of the human fetus and infant
J. Comp. Neurol.
Cultured rat microglial cells synthesize the endocannabinoid 2-arachidonylglycerol, which increases proliferation via a CB2 receptor-dependent mechanism
Mol. Pharmacol.
The endocannabinoid system is dysregulated in multiple sclerosis and in experimental autoimmune encephalomyelitis
Brain
Heterogeneity of microglial activation in the innate immune response in the brain
J. Neuroimmune Pharmacol.
Non-CB1, non-CB2 receptors for endocannabinoids, plant cannabinoids, and synthetic cannabimimetics: focus on G-protein-coupled receptors and transient receptor potential channels
J. Neuroimmune Pharmacol.
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These authors equally contributed to the study.