The Dual PDE7-GSK3ß Inhibitor, VP3.15, as Neuroprotective Disease-Modifying Treatment in a Model of Primary Progressive Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic, inflammatory, autoimmune and degenerative disease with axonal damage and demyelination as its main features. Its dual neurological and autoimmune nature makes it a disease that is difficult to treat. Treatments that simultaneously stop the immune response while protecting and repairing the nervous system are urgent. That is of utmost importance for the primary progressive multiple sclerosis (PPMS), a rare and severe variant of MS, characterized by worsening neurological function from the onset of symptoms. In this sense, inhibitors of glycogen synthase kinase 3ß (GSK3ß) and phosphodiesterase 7 (PDE7) have recently shown great therapeutic potential for the treatment of demyelinating diseases. Here we investigated a dual inhibitor of these two targets, the small molecule VP3.15, in a preclinical model, which resembles primary-progressive MS (PPMS), the Theiler's mouse encephalomyelitis virus-induced demyelinated disease (TMEV-IDD). In our study, VP3.15 ameliorates the disease course improving motor deficits of infected mice. Chronic treatment with VP3.15 also showed significant efficacy in the immunomodulation process, as well as in the proliferation and differentiation of oligodendroglial precursors, improving the preservation of myelin and axonal integrity. Therefore, our results support a treatment with the safe VP3.15 as an integrative therapeutic strategy for the treatment of PPMS.

2-arachidonoylglycerol reduces chondroitin sulphate proteoglycan production by astrocytes and enhances oligodendrocyte differentiation under inhibitory conditions.

The failure to remyelinate and regenerate is a critical impediment to recovery in multiple sclerosis (MS), resulting in severe dysfunction and disability. The chondroitin sulfate proteoglycans (CSPGs) that accumulate in MS lesions are thought to be linked to the failure to regenerate, impeding oligodendrocyte precursor cell (OPC) differentiation and neuronal growth. The potential of endocannabinoids to influence MS progression may reflect their capacity to enhance repair processes. Here, we investigated how 2-arachidonoylglycerol (2-AG) may affect the production of the CSPGs neurocan and brevican by astrocytes in culture. In addition, we studied whether 2-AG promotes oligodendrocyte differentiation under inhibitory conditions in vitro. Following treatment with 2-AG or by enhancing its endogenous tone through the use of inhibitors of its hydrolytic enzymes, CSPG production by rat and human TGF-ß1 stimulated astrocytes was reduced. These effects of 2-AG might reflect its influence on TGF-ß1/SMAD pathway, signaling that is involved in CSPG upregulation. The matrix generated from 2-AG-treated astrocytes is less inhibitory to oligodendrocyte differentiation and significantly, 2-AG administration directly promotes the differentiation of rat and human oligodendrocytes cultured under inhibitory conditions. Overall, the data obtained favor targeting the endocannabinoid system to neutralize CSPG accumulation and to enhance oligodendrocyte differentiation.

Effects of EHP-101 on inflammation and remyelination in murine models of Multiple sclerosis.

Multiple Sclerosis (MS) is characterized by a combination of inflammatory and neurodegenerative processes in the spinal cord and the brain. Natural and synthetic cannabinoids such as VCE-004.8 have been studied in preclinical models of MS and represent promising candidates for drug development. VCE-004.8 is a multitarget synthetic cannabidiol (CBD) derivative acting as a dual Peroxisome proliferator-activated receptor-gamma/Cannabinoid receptor type 2 (PPARγ/CB2) ligand agonist that also activates the Hypoxia-inducible factor (HIF) pathway. EHP-101 is an oral lipidic formulation of VCE-004.8 that has shown efficacy in several preclinical models of autoimmune, inflammatory, fibrotic, and neurodegenerative diseases. EHP-101 alleviated clinical symptomatology in EAE and transcriptomic analysis demonstrated that EHP-101 prevented the expression of many inflammatory genes closely associated with MS pathophysiology in the spinal cord. EHP-101 normalized the expression of several genes associated with oligodendrocyte function such as Teneurin 4 (Tenm4) and Gap junction gamma-3 (Gjc3) that were downregulated in EAE. EHP-101 treatment prevented microglia activation and demyelination in both the spinal cord and the brain. Moreover, EAE was associated with a loss in the expression of Oligodendrocyte transcription factor 2 (Olig2) in the corpus callosum, a marker for oligodendrocyte differentiation, which was restored by EHP-101 treatment. In addition, EHP-101 enhanced the expression of glutathione S-transferase pi (GSTpi), a marker for mature oligodendrocytes in the brain. We also found that a diet containing 0.2% cuprizone for six weeks induced a clear loss of myelin in the brain measured by Cryomyelin staining and Myelin basic protein (MBP) expression. Moreover, EHP-101 also prevented cuprizone-induced microglial activation, astrogliosis and reduced axonal damage. Our results provide evidence that EHP-101 showed potent anti-inflammatory activity, prevented demyelination, and enhanced remyelination. Therefore, EHP-101 represents a promising drug candidate for the potential treatment of different forms of MS.

Involvement of Wnt7a in the role of M2c microglia in neural stem cell oligodendrogenesis.

BACKGROUND: The participation of microglia in CNS development and homeostasis indicate that these cells are pivotal for the regeneration that occurs after demyelination. The clearance of myelin debris and the inflammatory-dependent activation of local oligodendrocyte progenitor cells in a demyelinated lesion is dependent on the activation of M2c microglia, which display both phagocytic and healing functions. Emerging interest has been raised about the role of Wnt/ß-catenin signaling in oligodendrogenesis and myelination. Besides, cytokines and growth factors released by microglia can control the survival, proliferation, migration, and differentiation of neural stem cells (NSCs), contributing to remyelination through the oligodendrocyte specification of this adult neurogenic niche. METHODS: TMEV-IDD model was used to study the contribution of dorsal SVZ stem cells to newly born oligodendrocytes in the corpus callosum following demyelination by (i) en-face dorsal SVZ preparations; (ii) immunohistochemistry; and (iii) cellular tracking. By RT-PCR, we analyzed the expression of Wnt proteins in demyelinated and remyelinating corpus callosum. Using in vitro approaches with microglia cultures and embryonic NSCs, we studied the role of purified myelin, Wnt proteins, and polarized microglia-conditioned medium to NSC proliferation and differentiation. One-way ANOVA followed by Bonferroni's post-hoc test, or a Student's t test were used to establish statistical significance. RESULTS: The demyelination caused by TMEV infection is paralleled by an increase in B1 cells and pinwheels in the dorsal SVZ, resulting in the mobilization of SVZ proliferative progenitors and their differentiation into mature oligodendrocytes. Demyelination decreased the gene expression of Wnt5a and Wnt7a, which was restored during remyelination. In vitro approaches show that Wnt3a enhances NSC proliferation, while Wnt7a and myelin debris promotes oligodendrogenesis from NSCs. As phagocytic M2c microglia secrete Wnt 7a, their conditioned media was found to induce Wnt/ß-Catenin signaling in NSCs promoting an oligodendroglial fate. CONCLUSIONS: We define here the contribution of microglia to Wnt production depending on their activation state, with M1 microglia secreting the Wnt5a protein and M2c microglia secreting Wnt7a. Collectively, our data reveal the role of reparative microglia in NSC oligodendrogenesis with the involvement of Wnt7a.

2-Arachidonoylglycerol Reduces Proteoglycans and Enhances Remyelination in a Progressive Model of Demyelination.

The failure to undergo remyelination is a critical impediment to recovery in multiple sclerosis. Chondroitin sulfate proteoglycans (CSPGs) accumulate at demyelinating lesions creating a nonpermissive environment that impairs axon regeneration and remyelination. Here, we reveal a new role for 2-arachidonoylglycerol (2-AG), the major CNS endocannabinoid, in the modulation of CSPGs deposition in a progressive model of multiple sclerosis, the Theiler's murine encephalomyelitis virus-induced demyelinating disease. Treatment with a potent reversible inhibitor of the enzyme monoacylglycerol lipase, which accounts for 85% of the 2-AG degradation in the mouse CNS, modulates neuroinflammation and reduces CSPGs accumulation and astrogliosis around demyelinated lesions in the spinal cord of Theiler's murine encephalomyelitis virus-infected mice. Inhibition of 2-AG hydrolysis augments the number of mature oligodendrocytes and increases MBP, leading to remyelination and functional recovery of mice. Our findings establish a mechanism for 2-AG promotion of remyelination with implications in axonal repair in CNS demyelinating pathologies.SIGNIFICANCE STATEMENT The deposition of chondroitin sulfate proteoglycans contributes to the failure in remyelination associated with multiple sclerosis. Here we unveil a new role for 2-arachidonoylglycerol, the major CNS endocannabinoid, in the modulation of chondroitin sulfate proteoglycan accumulation in Theiler's murine encephalomyelitis virus-induced demyelinating disease. The treatment during the chronic phase with a potent reversible inhibitor of the enzyme monoacylglycerol lipase, which accounts for 85% of the 2-arachidonoylglycerol degradation in the mouse CNS, modulates neuroinflammation and reduces chondroitin sulfate proteoglycan deposition around demyelinated lesions in the spinal cord of Theiler's murine encephalomyelitis virus-infected mice. The increased 2-arachidonoylglycerol tone promotes remyelination in a model of progressive multiple sclerosis ameliorating motor dysfunction.

2-AG limits Theiler's virus induced acute neuroinflammation by modulating microglia and promoting MDSCs.

The innate immune response is mediated by primary immune modulators such as cytokines and chemokines that together with immune cells and resident glia orchestrate CNS immunity and inflammation. Growing evidence supports that the endocannabinoid 2-arachidonoylglycerol (2-AG) exerts protective actions in CNS injury models. Here, we used the acute phase of Theiler's virus induced demyelination disease (TMEV-IDD) as a model of acute neuroinflammation to investigate whether 2-AG modifies the brain innate immune responses to TMEV and CNS leukocyte trafficking. 2-AG or the inhibition of its hydrolysis diminished the reactivity and number of microglia at the TMEV injection site reducing their morphological complexity and modulating them towards an anti-inflammatory state via CB2 receptors. Indeed, 2-AG dampened the infiltration of immune cells into the CNS and inhibited their egress from the spleen, resulting in long-term beneficial effects at the chronic phase of the disease. Intriguingly, it is not a generalized action over leukocytes since 2-AG increased the presence and suppressive potency of myeloid derived suppressor cells (MDSCs) in the brain resulting in higher apoptotic CD4+ T cells at the injection site. Together, these data suggest a robust modulatory effect in the peripheral and central immunity by 2-AG and highlight the interest of modulating endogenous cannabinoids to regulate CNS inflammatory conditions.

Hypoxia mimetic activity of VCE-004.8, a cannabidiol quinone derivative: implications for multiple sclerosis therapy.

BACKGROUND: Multiple sclerosis (MS) is characterized by a combination of inflammatory and neurodegenerative processes variously dominant in different stages of the disease. Thus, immunosuppression is the goal standard for the inflammatory stage, and novel remyelination therapies are pursued to restore lost function. Cannabinoids such as 9Δ-THC and CBD are multi-target compounds already introduced in the clinical practice for multiple sclerosis (MS). Semisynthetic cannabinoids are designed to improve bioactivities and druggability of their natural precursors. VCE-004.8, an aminoquinone derivative of cannabidiol (CBD), is a dual PPARγ and CB2 agonist with potent anti-inflammatory activity. Activation of the hypoxia-inducible factor (HIF) can have a beneficial role in MS by modulating the immune response and favoring neuroprotection and axonal regeneration. METHODS: We investigated the effects of VCE-004.8 on the HIF pathway in different cell types. The effect of VCE-004.8 on macrophage polarization and arginase 1 expression was analyzed in RAW264.7 and BV2 cells. COX-2 expression and PGE2 synthesis induced by lipopolysaccharide (LPS) was studied in primary microglia cultures. The efficacy of VCE-004.8 in vivo was evaluated in two murine models of MS such as experimental autoimmune encephalomyelitis (EAE) and Theiler's virus-induced encephalopathy (TMEV). RESULTS: Herein, we provide evidence that VCE-004.8 stabilizes HIF-1α and HIF-2α and activates the HIF pathway in human microvascular endothelial cells, oligodendrocytes, and microglia cells. The stabilization of HIF-1α is produced by the inhibition of the prolyl-4-hydrolase activity of PHD1 and PDH2. VCE-004.8 upregulates the expression of HIF-dependent genes such as erythropoietin and VEGFA, induces angiogenesis, and enhances migration of oligodendrocytes. Moreover, VCE-004.8 blunts IL-17-induced M1 polarization, inhibits LPS-induced COX-2 expression and PGE2 synthesis, and induces expression of arginase 1 in macrophages and microglia. In vivo experiments showed efficacy of VCE-004.8 in EAE and TMEV. Histopathological analysis revealed that VCE-004.8 treatments prevented demyelination, axonal damage, and immune cells infiltration. In addition, VCE-004.8 downregulated the expression of several genes closely associated with MS physiopathology, including those underlying the production of chemokines, cytokines, and adhesion molecules. CONCLUSIONS: This study provides new significant insights about the potential role of VCE-004.8 for MS treatment by ameliorating neuroinflammation and demyelination.

Development of a Fluorescent Bodipy Probe for Visualization of the Serotonin 5-HT1A Receptor in Native Cells of the Immune System.

Serotonin (5-HT) modulates key aspects of the immune system. However, its precise function and the receptors involved in the observed effects have remained elusive. Among the different serotonin receptors, 5-HT1A plays an important role in the immune system given its presence in cells involved in both the innate and adaptive immune responses, but its actual levels of expression under different conditions have not been comprehensively studied due to the lack of suitable tools. To further clarify the role of 5-HT1A receptor in the immune system, we have developed a fluorescent small molecule probe that enables the direct study of the receptor levels in native cells. This probe allows direct profiling of the receptor expression in immune cells using flow cytometry. Our results show that important subsets of immune cells including human monocytes and dendritic cells express functional 5-HT1A and that its activation is associated with anti-inflammatory signaling. Furthermore, application of the probe to the experimental autoimmune encephalomyelitis model of multiple sclerosis demonstrates its potential to detect the specific overexpression of the 5-HT1A receptor in CD4+ T cells. Accordingly, the probe reported herein represents a useful tool whose use can be extended to study the levels of 5-HT1A receptor in ex vivo samples of different immune system conditions.

Novel Insights into the Multiple Sclerosis Risk Gene ANKRD55.

An intronic variant in ANKRD55, rs6859219, is a genetic risk factor for multiple sclerosis, but the biological reasons underlying this association are unknown. We characterized the expression of ANKRD55 in human PBMCs and cell lines. Three ANKRD55 transcript variants (Ensembl isoforms 001, 005, and 007) could be detected in PBMCs and CD4(+) T cells but were virtually absent in CD8(+), CD14(+), CD19(+), and CD56(+) cells. Rs6859219 was significantly associated with ANKRD55 transcript levels in PBMCs and CD4(+) T cells and, thus, coincides with a cis-expression quantitative trait locus. The processed noncoding transcript 007 was the most highly expressed variant in CD4(+) T cells, followed by 001 and 005, respectively, but it was not detected in Jurkat, U937, and SH-SY5Y cell lines. Homozygotes for the risk allele produced more than four times more transcript copies than did those for the protective allele. ANKRD55 protein isoforms 005 and 001 were predominantly located in the nucleus of CD4(+) T cells and Jurkat and U937 cells. ANKRD55 was produced by primary cultures of murine hippocampal neurons and microglia, as well as by the murine microglial cell line BV2, and it was induced by inflammatory stimuli. ANKRD55 protein was increased in the murine mouse model of experimental autoimmune encephalomyelitis. Flow cytometric analysis of CNS-infiltrating mononuclear cells showed that CD4(+) T cells and monocytes expressed ANKRD55 in experimental autoimmune encephalomyelitis mice, with the higher fluorescence intensity found in CD4(+) cells. A low percentage of microglia also expressed ANKRD55. Together, these data support an important role for ANKRD55 in multiple sclerosis and neuroinflammation.

CD200R1 agonist attenuates glial activation, inflammatory reactions, and hypersensitivity immediately after its intrathecal application in a rat neuropathic pain model.

BACKGROUND: Interaction of CD200 with its receptor CD200R has an immunoregulatory role and attenuates various types of neuroinflammatory diseases. METHODS: Immunofluorescence staining, western blot analysis, and RT-PCR were used to investigate the modulatory effects of CD200 fusion protein (CD200Fc) on activation of microglia and astrocytes as well as synthesis of pro- (TNF, IL-1ß, IL-6) and anti-inflammatory (IL-4, IL-10) cytokines in the L4-L5 spinal cord segments in relation to behavioral signs of neuropathic pain after unilateral sterile chronic constriction injury (sCCI) of the sciatic nerve. Withdrawal thresholds for mechanical hypersensitivity and latencies for thermal hypersensitivity were measured in hind paws 1 day before operation; 1, 3, and 7 days after sCCI operation; and then 5 and 24 h after intrathecal application of artificial cerebrospinal fluid or CD200Fc. RESULTS: Seven days from sCCI operation and 5 h from intrathecal application, CD200Fc reduced mechanical and thermal hypersensitivity when compared with control animals. Simultaneously, CD200Fc attenuated activation of glial cells and decreased proinflammatory and increased anti-inflammatory cytokine messenger RNA (mRNA) levels. Administration of CD200Fc also diminished elevation of CD200 and CD200R proteins as a concomitant reaction of the modulatory system to increased neuroinflammatory reactions after nerve injury. The anti-inflammatory effect of CD200Fc dropped at 24 h after intrathecal application. CONCLUSIONS: Intrathecal administration of the CD200R1 agonist CD200Fc induces very rapid suppression of neuroinflammatory reactions associated with glial activation and neuropathic pain development. This may constitute a promising and novel therapeutic approach for the treatment of neuropathic pain.

A reversible and selective inhibitor of monoacylglycerol lipase ameliorates multiple sclerosis.

Monoacylglycerol lipase (MAGL) is the enzyme responsible for the inactivation of the endocannabinoid 2-arachidonoylglycerol (2-AG). MAGL inhibitors show analgesic and tissue-protecting effects in several disease models. However, the few efficient and selective MAGL inhibitors described to date block the enzyme irreversibly, and this can lead to pharmacological tolerance. Hence, additional classes of MAGL inhibitors are needed to validate this enzyme as a therapeutic target. Here we report a potent, selective, and reversible MAGL inhibitor (IC50=0.18 µM) which is active in vivo and ameliorates the clinical progression of a multiple sclerosis (MS) mouse model without inducing undesirable CB1 -mediated side effects. These results support the interest in MAGL as a target for the treatment of MS.

CD200-CD200R1 interaction contributes to neuroprotective effects of anandamide on experimentally induced inflammation.

The endocannabinoid anandamide (AEA) is released by macrophages and microglia on pathological neuroinflammatory conditions such as multiple sclerosis (MS). CD200 is a membrane glycoprotein expressed in neurons that suppresses immune activity via its receptor (CD200R) mainly located in macrophages/microglia. CD200-CD200R interactions contribute to the brain immune privileged status. In this study, we show that AEA protects neurons from microglia-induced neurotoxicity via CD200-CD200R interaction. AEA increases the expression of CD200R1 in LPS/IFN-γ activated microglia through the activation of CB(2) receptors. The neuroprotective effect of AEA disappears when microglial cells derive from CD200R1(-/-) mice. We also show that engagement of CD200R1 by CD200Fc decreased the production of the proinflammatory cytokines IL-1ß and IL-6, but increased IL-10 in activated microglia. In the chronic phases of Theiler's virus-induced demyelinating disease (TMEV-IDD) the expression of CD200 and CD200R1 was reduced in the spinal cord. AEA-treated animals up-regulated the expression of CD200 and CD200R1, restoring levels found in sham animals together with increased expression of IL-10 and reduced expression of IL-1ß and IL-6. Treated animals also improved their motor behavior. Because AEA up-regulated the expression of CD200R1 in microglia, but failed to enhance CD200 in neurons we suggest that AEA-induced up-regulation of CD200 in TMEV-IDD is likely due to IL-10 as this cytokine increases CD200 in neurons. Our findings provide a new mechanism of action of AEA to limit immune response in the inflamed brain.

Cannabidiol-induced apoptosis in murine microglial cells through lipid raft.

Cannabidiol (CBD), the major nonpsychotropic phytocannabinoid, induces apoptosis in both immortalized and primary lymphocytes and monocytes. However, contrasting effects of CBD on the apoptosis between normal and immortalized glial cells have been reported. This study investigated the proapoptotic effect of CBD on primary microglial cells. Treatment of murine primary microglial cultures with CBD resulted in a time- and concentration-dependent induction of apoptosis, as shown by increase in hypodiploid cells and DNA strand breaks, and marked activation of both caspase-8 and -9. Mechanistic studies revealed that antioxidants, including N-acetyl-L-cysteine and glutathione, the G protein-coupled receptor 55 agonist abnormal-CBD and specific antagonists for vanilloid, and CB1 and CB2 cannabinoid receptors did not counteract the apoptosis induced by CBD. In contrast, methyl-ß-cyclodextrin (MCD), a lipid raft disruptor, potently attenuated CBD-induced microglial apoptosis and caspase activation. Furthermore, CBD induced lipid raft coalescence and augmented the expression of GM1 ganglioside and caveolin-1, all of which were attenuated by MCD. Taken together, these results suggest that CBD induces a marked proapoptotic effect in primary microglia through lipid raft coalescence and elevated expression of GM1 ganglioside and caveolin-1.

Chemical probes for the recognition of cannabinoid receptors in native systems.

Receptors made visible: The described biotin-tagged small-molecule probes with excellent affinities for the CB(1) and CB(2) cannabinoid receptors (CB(1)R and CB(2)R) enable direct visualization of these receptors in native cellular systems, including neurons, microglia, and immune cells. This method could overcome some of the limitations of current methodologies and may help to dissect the complexity of the endogenous cannabinoid system.

Efficacy of Vafidemstat in Experimental Autoimmune Encephalomyelitis Highlights the KDM1A/RCOR1/HDAC Epigenetic Axis in Multiple Sclerosis.

Lysine specific demethylase 1 (LSD1; also known as KDM1A), is an epigenetic modulator that modifies the histone methylation status. KDM1A forms a part of protein complexes that regulate the expression of genes involved in the onset and progression of diseases such as cancer, central nervous system (CNS) disorders, viral infections, and others. Vafidemstat (ORY-2001) is a clinical stage inhibitor of KDM1A in development for the treatment of neurodegenerative and psychiatric diseases. However, the role of ORY-2001 targeting KDM1A in neuroinflammation remains to be explored. Here, we investigated the effect of ORY-2001 on immune-mediated and virus-induced encephalomyelitis, two experimental models of multiple sclerosis and neuronal damage. Oral administration of ORY-2001 ameliorated clinical signs, reduced lymphocyte egress and infiltration of immune cells into the spinal cord, and prevented demyelination. Interestingly, ORY-2001 was more effective and/or faster acting than a sphingosine 1-phosphate receptor antagonist in the effector phase of the disease and reduced the inflammatory gene expression signature characteristic ofEAE in the CNS of mice more potently. In addition, ORY-2001 induced gene expression changes concordant with a potential neuroprotective function in the brain and spinal cord and reduced neuronal glutamate excitotoxicity-derived damage in explants. These results pointed to ORY-2001 as a promising CNS epigenetic drug able to target neuroinflammatory and neurodegenerative diseases and provided preclinical support for the subsequent design of early-stage clinical trials.

Anandamide inhibits Theiler's virus induced VCAM-1 in brain endothelial cells and reduces leukocyte transmigration in a model of blood brain barrier by activation of CB(1) receptors.

BACKGROUND: VCAM-1 represents one of the most important adhesion molecule involved in the transmigration of blood leukocytes across the blood-brain barrier (BBB) that is an essential step in the pathogenesis of MS. Several evidences have suggested the potential therapeutic value of cannabinoids (CBs) in the treatment of MS and their experimental models. However, the effects of endocannabinoids on VCAM-1 regulation are poorly understood. In the present study we investigated the effects of anandamide (AEA) in the regulation of VCAM-1 expression induced by Theiler's virus (TMEV) infection of brain endothelial cells using in vitro and in vivo approaches. METHODS: i) in vitro: VCAM-1 was measured by ELISA in supernatants of brain endothelial cells infected with TMEV and subjected to AEA and/or cannabinoid receptors antagonist treatment. To evaluate the functional effect of VCAM-1 modulation we developed a blood brain barrier model based on a system of astrocytes and brain endothelial cells co-culture. ii) in vivo: CB(1) receptor deficient mice (Cnr1(-/-)) infected with TMEV were treated with the AEA uptake inhibitor UCM-707 for three days. VCAM-1 expression and microglial reactivity were evaluated by immunohistochemistry. RESULTS: Anandamide-induced inhibition of VCAM-1 expression in brain endothelial cell cultures was mediated by activation of CB(1) receptors. The study of leukocyte transmigration confirmed the functional relevance of VCAM-1 inhibition by AEA. In vivo approaches also showed that the inhibition of AEA uptake reduced the expression of brain VCAM-1 in response to TMEV infection. Although a decreased expression of VCAM-1 by UCM-707 was observed in both, wild type and CB(1) receptor deficient mice (Cnr1(-/-)), the magnitude of VCAM-1 inhibition was significantly higher in the wild type mice. Interestingly, Cnr1(-/-) mice showed enhanced microglial reactivity and VCAM-1 expression following TMEV infection, indicating that the lack of CB(1) receptor exacerbated neuroinflammation. CONCLUSIONS: Our results suggest that CB(1) receptor dependent VCAM-1 inhibition is a novel mechanism for AEA-reduced leukocyte transmigration and contribute to a better understanding of the mechanisms underlying the beneficial role of endocannabinoid system in the Theiler's virus model of MS.

The endocannabinoid anandamide downregulates IL-23 and IL-12 subunits in a viral model of multiple sclerosis: evidence for a cross-talk between IL-12p70/IL-23 axis and IL-10 in microglial cells.

Theiler's virus (TMEV) infection of the central nervous system (CNS) induces an immune-mediated demyelinating disease in susceptible mouse strains and serves as a relevant infection model for human multiple sclerosis (MS). The endocannabinoid system represents a novel therapeutic target for autoimmune and chronic inflammatory diseases due to its anti-inflammatory properties by regulating cytokine network. IL-12p70 and IL-23 are functionally related heterodimeric cytokines that play a crucial role in the pathogenesis of MS. In the present study we showed that the endocannabinoid anandamide (AEA) downregulated the gene expression of IL-12p70 and IL-23 forming subunits mRNAs in the spinal cord of TMEV-infected mice and ameliorated motor disturbances. This was accompanied by significant decreases on the serological levels of IL-12p70/IL-23 and more interestingly, of IL-17A. In contrast, serum levels of IL-10 resulted elevated. In addition, we studied the signalling pathways involved in the regulation of IL-12p70/IL-23 and IL-10 expression in TMEV-infected microglia and addressed the possible interactions of AEA with these pathways. AEA acted through the ERK1/2 and JNK pathways to downregulate IL-12p70 and IL-23 while upregulating IL-10. These effects were partially mediated by CB2 receptor activation. We also described an autocrine circuit of cross-talk between IL-12p70/IL-23 and IL-10, since endogenously produced IL-10 negatively regulates IL-12p70 and IL-23 cytokines in TMEV-infected microglia. This suggests that by altering the cytokine network, AEA could indirectly modify the type of immune responses within the CNS. Accordingly, pharmacological modulation of endocannabinoids might be a useful tool for treating neuroinflammatory diseases.

Aging and neuroinflammation: Changes in immune cell responses, axon integrity, and motor function in a viral model of progressive multiple sclerosis.

Although aggravated multiple sclerosis (MS) disability has been reported in aged patients, the aging impact on immune cells remodeling within the CNS is not well understood. Here, we investigated the influence of aging on immune cells and the neuroinflammatory and neurodegenerative processes that occur in a well-established viral model of progressive MS. We found an anomalous presence of CD4+ T, CD8+ T, B cells, and cells of myeloid lineage in the CNS of old sham mice whereas a blunted cellular innate and adaptive immune response was observed in Theiler's murine encephalomyelitis virus (TMEV) infected old mice. Microglia and macrophages show opposite CNS viral responses regarding cell counts in the old mice. Furthermore, enhanced expression of Programmed Death-ligand 1 (PD-L1) was found in microglia isolated from old TMEV-infected mice and not in isolated CNS macrophages. Immunocytochemical staining of microglial cells confirms the above differences between young and old mice. Age-related axonal loss integrity in the mouse spinal cord was found in TMEV mice, but a less marked neurodegenerative process was present in old sham mice compared with young sham mice. TMEV and sham old mice also display alterations in innate and adaptive immunity in the spleen compared to the young mice. Our study supports the need of new or adapted pharmacological strategies for MS elderly patients.

Selected Clostridia Strains from The Human Microbiota and their Metabolite, Butyrate, Improve Experimental Autoimmune Encephalomyelitis.

Gut microbiome studies in multiple sclerosis (MS) patients are unravelling some consistent but modest patterns of gut dysbiosis. Among these, a significant decrease of Clostridia cluster IV and XIVa has been reported. In the present study, we investigated the therapeutic effect of a previously selected mixture of human gut-derived 17 Clostridia strains, which belong to Clostridia clusters IV, XIVa, and XVIII, on the clinical outcome of experimental autoimmune encephalomyelitis (EAE). The observed clinical improvement was related to lower demyelination and astrocyte reactivity as well as a tendency to lower microglia reactivity/infiltrating macrophages and axonal damage in the central nervous system (CNS), and to an enhanced immunoregulatory response of regulatory T cells in the periphery. Transcriptome studies also highlighted increased antiinflammatory responses related to interferon beta in the periphery and lower immune responses in the CNS. Since Clostridia-treated mice were found to present higher levels of the immunomodulatory short-chain fatty acid (SCFA) butyrate in the serum, we studied if this clinical effect could be reproduced by butyrate administration alone. Further EAE experiments proved its preventive but slight therapeutic impact on CNS autoimmunity. Thus, this smaller therapeutic effect highlighted that the Clostridia-induced clinical effect was not exclusively related to the SCFA and could not be reproduced by butyrate administration alone. Although it is still unknown if these Clostridia strains will have the same effect on MS patients, gut dysbiosis in MS patients could be partially rebalanced by these commensal bacteria and their immunoregulatory properties could have a beneficial effect on MS clinical course.