Heterogeneity of the Endocannabinoid System Between Cerebral Cortex and Spinal Cord Oligodendrocytes.

In the last years, regional differences have been reported between the brain and spinal cord oligodendrocytes, which should be considered when designing therapeutic strategies for myelin repair. Promising targets to achieve myelin restoration are the different components of the endocannabinoid system (ECS) that modulate oligodendrocyte biology, but almost all studies have been focused on brain-derived cells. Therefore, we compared the ECS between the spinal cord and cerebral cortex-derived oligodendrocyte precursor cells (OPCs) and mature oligodendrocytes (OLs). Cells from both regions express synthesizing and degrading enzymes for the endocannabinoid 2-arachidonoylglycerol, and degrading enzymes increase with maturation, more notably in the spinal cord (monoglyceride lipase-MGLL, alpha/beta hydrolase domain-containing 6-ABHD6, and alpha/beta hydrolase domain-containing 12-ABHD12). In addition, spinal cord OPCs express higher levels of the synthesizing enzymes diacylglycerol lipases alpha (DAGLA) and beta (DAGLB) than cortical ones, DAGLA reaching statistical significance. Cells from both the cortex and spinal cord express low levels of NAEs synthesizing enzymes, except for the glycerophosphodiester phosphodiesterase 1 (GDE-1) but high levels of the degrading enzyme fatty acid amidohydrolase (FAAH) that increases with maturation. Finally, cells from both regions show similar levels of CB1 receptor and GPR55, but spinal cord-derived cells show significantly higher levels of transient receptor potential cation channel V1 (TRPV1) and CB2. Overall, our results show that the majority of the ECS components could be targeted in OPCs and OLs from both the spinal cord and brain, but regional heterogeneity has to be considered for DAGLA, MGLL, ABHD6, ABHD12, GDE1, CB2, or TRPV1.

Spinal cord injury induces a long-lasting upregulation of interleukin-1ß in astrocytes around the central canal.

Under inflammatory conditions, interleukin-1ß (IL-1ß) modulates neural stem cells at neurogenic niches. Here we show that spinal cord injury in rats increases IL-1ß expression in astrocytes located around the spinal cord ependyma, a region that also holds a neurogenic potential. IL-1ß increases from day 1 after lesion, reaches maximal levels between days 3 and 7, and declines from 14 days to low levels after 28 days. At the time of maximal expression, periependymal upregulation of IL-1ß extends beyond 5 mm from the epicenter of the lesion both rostral and caudally. Since IL-1ß controls proliferation and cell fate of neural stem/precursor cells, its modulation in periependymal astrocytes might create an appropriate environment for cell replacement after injury.

CB1 receptor antagonism/inverse agonism increases motor system excitability in humans.

CB1 receptor is highly expressed in cerebral structures related to motor control, such as motor cortex, basal ganglia and cerebellum. In the spinal cord, the expression of CB1 receptors has also been observed in ventral motor neurons, interneurons and primary afferents, i.e., in the cells that may be part of the circuits involved in motor control. It is known that the antagonist/inverse agonist of CB1 receptors Rimonabant penetrates the blood-brain barrier and produces a broad range of central psychoactive effects in humans. Based on the occurrence of central effects in humans treated with Rimonabant and on the location of CB1 receptors, we hypothesized that the application of Rimonabant can also affect the motor system. We tested the effects of a single dose of 20mg of Rimonabant on the excitability of motor cortex and of spinal motor neurons in order to detect a possible drug action on motor system at cortical and spinal levels. For this purpose we use classical protocols of transcranial magnetic and electrical stimulation (TMS and TES). Single and paired pulse TMS and TES were used to assess a number of parameters of cortical inhibition and cortical excitability as well as of the excitability of spinal motor neurons. We demonstrated that a single oral dose of 20mg of Rimonabant can increase motor system excitability at cortical and spinal levels. This opens new avenues to test the CB1R antagonists/inverse agonists for the treatment of a number of neurological dysfunctions in which can be useful to increase the excitability levels of motor system. Virtually all the disorders characterized by a reduced output of the motor cortex can be included in the list of the disorders that can be treated using CB1 antagonists/reverse agonists (e.g. stroke, traumatic brain injury, spinal cord injury, multiple sclerosis, fatigue syndromes, parkinsonisms, etc.).

CB2 cannabinoid receptors as an emerging target for demyelinating diseases: from neuroimmune interactions to cell replacement strategies.

Amongst the various demyelinating diseases that affect the central nervous system, those induced by an inflammatory response stand out because of their epidemiological relevance. The best known inflammatory-induced demyelinating disease is multiple sclerosis, but the immune response is a common pathogenic mechanism in many other less common pathologies (e.g., acute disseminated encephalomyelitis and acute necrotizing haemorrhagic encephalomyelitis). In all such cases, modulation of the immune response seems to be a logical therapeutic approach. Cannabinoids are well known immunomodulatory molecules that act through CB1 and CB2 receptors. While activation of CB1 receptors has a psychotropic effect, activation of CB2 receptors alone does not. Therefore, to bypass the ethical problems that could result from the treatment of inflammation with psychotropic molecules, considerable effort is being made to study the potential therapeutic value of activating CB2 receptors. In this review we examine the current knowledge and understanding of the utility of cannabinoids as therapeutic molecules for inflammatory-mediated demyelinating pathologies. Moreover, we discuss how CB2 receptor activation is related to the modulation of immunopathogenic states.

El sistema cannabinoide en situaciones de neuroinflamación: perspectivas terapéuticas en la esclerosis múltiple / Cannabinoid system and neuroinflammation: therapeutic perspectives in multiple sclerosis

Introducción. El sistema endocannabinoide está constituidopor los receptores cannabinoides, los ligandos endógenos y loselementos enzimáticos implicados en su síntesis y degradación.Objetivo. Describir el estado actual de conocimiento sobre la funcióndel sistema como modulador de los procesos neuroinflamatoriosasociados con enfermedades crónicas como la esclerosis múltiple.Desarrollo. Los cannabinoides se sintetizan y se liberan en demanda y su producción aumenta en situaciones de neuroinflamacióny de daño neural. En este contexto, sus acciones en la microglía y enlos astrocitos se caracterizan por una disminución en la expresión demediadores inflamatorios y de citocinas proinflamatorias. Además,los cannabinoides pueden ejercer acciones neuroprotectoras a travésde diferentes tipos de mecanismos y en modelos experimentalesde esclerosis múltiple atenúan la sintomatología, disminuyen lainflamación y pueden favorecer la remielinización. Conclusiones. Eluso clínico de cannabinoides o agentes farmacológicos que incidenen el sistema endógeno cannabinoide durante la inflamación del sistemanervioso central y en la esclerosis múltiple está actualmentesometido a consideración y debate. El análisis detallado de los resultadosobtenidos en la última década ha permitido establecer que sonmúltiples los mecanismos de actuación de los cannabinoides en patologíasdel sistema nervioso central que cursan con inflamación crónicay ponen de manifiesto el interés del sistema cannabinoide comonueva herramienta terapéutica

Introduction. The endocannabinoid system consists of cannabinoid receptors, endogenous ligands and the enzymaticelements involved in their synthesis and breakdown. Aim. To report on currently held knowledge about the functioning of thesystem as a modulator of the neuroinflammatory processes associated with chronic diseases such as multiple sclerosis.Development. Cannabinoids are synthesised and released on demand and their production increases in times of neuroinflammationand neural damage. In this context then, their actions in the microglial cells and in the astrocytes arecharacterised by a lowered expression of inflammatory mediators and pro-inflammatory cytokines. Furthermore,cannabinoids can play a role as neuroprotectors by means of different types of mechanisms and, in experimental models ofmultiple sclerosis, they slow down the symptoms, reduce inflammation and can favour remyelination. Conclusions. Theclinical use of cannabinoids or pharmacological agents that affect the endogenous cannabinoid system during inflammationof the central nervous system and in multiple sclerosis is currently under consideration and subject to debate. Detailedanalysis of the results obtained over the past decade has made it possible to establish the existence of several mechanisms ofaction of cannabinoids in pathologies affecting the central nervous system that are accompanied by chronic inflammation.Likewise, they also clearly show that the cannabinoid system is an interesting proposal as a new therapeutic tool

[Cannabinoid system and neuroinflammation:therapeutic perspectives in multiple sclerosis]. / El sistema cannabinoide en situaciones de neuroinflamación: perspectivas terapéuticas en la esclerosis múltiple.

INTRODUCTION: The endocannabinoid system consists of cannabinoid receptors, endogenous ligands and the enzymatic elements involved in their synthesis and breakdown. AIM: To report on currently held knowledge about the functioning of the system as a modulator of the neuroinflammatory processes associated with chronic diseases such as multiple sclerosis. DEVELOPMENT: Cannabinoids are synthesised and released on demand and their production increases in times of neuroinflammation and neural damage. In this context then, their actions in the microglial cells and in the astrocytes are characterised by a lowered expression of inflammatory mediators and pro-inflammatory cytokines. Furthermore, cannabinoids can play a role as neuroprotectors by means of different types of mechanisms and, in experimental models of multiple sclerosis, they slow down the symptoms, reduce inflammation and can favour remyelination. CONCLUSIONS: The clinical use of cannabinoids or pharmacological agents that affect the endogenous cannabinoid system during inflammation of the central nervous system and in multiple sclerosis is currently under consideration and subject to debate. Detailed analysis of the results obtained over the past decade has made it possible to establish the existence of several mechanisms of action of cannabinoids in pathologies affecting the central nervous system that are accompanied by chronic inflammation. Likewise, they also clearly show that the cannabinoid system is an interesting proposal as a new therapeutic tool.

[Theiler's virus encephalomyelitis infection as a model for multiple sclerosis: cytokines and pathogenic mechanisms]. / Encefalomielitis por infección con el virus de Theiler como modelo experimental de esclerosis múltiple: citocinas y posibles mecanismos patogénicos.

Theiler's murine encephalomyelitis virus (TMEV) disease is induced following intracerebral inoculation of TMEV, a member of picornavirus family, in susceptible animals. The pathogenesis of paralytic syndrome is associated with a chronic progressive demyelinating disease characterized by perivascular of immune inflammatory cells. Although TMEV induced demyelinating disease (TMEV IDD) is initiated by virus specific CD4+ T cells targeting CNS persistent virus, CD4+ T cell responses against self myelin epitopes activated via epitope spreading contribute to chronic disease pathogenesis. In the present report we delineated possible pathogenic mechanisms related with inflammatory process, leading to demyelination and axonal loss. The importance of proinflammatory cytokines in sustaining the inflammatory process and cause direct oligodendrotoxicity is emphasized. Different approaches in therapeutic strategies affecting cytokines are also presented.

Encefalomielitis por infección con el virus de Theilercomo modelo experimental de esclerosis múltiple:citocinas y posibles mecanismos patogénicos / Theiler's virus encephalomyelitis infection as a model for multiple sclerosis: cytokines and pathogenic mechanisms

La esclerosis múltiple (EM) es la enfermedad desmielinizante más frecuente en adultos jóvenes, y aunque su etiología es desconocida, estudios epidemiológicos apuntan a una infección vírica como posible causa de la enfermedad. La inoculación de cepas susceptibles de ratones con el virus de la encefalomielitis murina de Theiler (TMEV, del inglés Theiler's Murine Encephalomyelitis Virus) conduce al desarrollo de una enfermedad crónica desmielinizante caracterizada por lesiones multifocales en la sustancia blanca, con infiltrados inflamatorios similares a la patología observada en la EM en su fase crónica progresiva. Los oligodendrocitos o la mielina son diana de factores solubles citotóxicos liberados por linfocitos CD4+ del subtipo Th1, en respuesta a un fenómeno de hipersensibilidad retardada contra el virus, así como por la microglía y astroglía cerebral activada. En los estadios más avanzados de la infección, se produce una respuesta de inmunidad específica contra antígenos de la mielina, debido al fenómeno de la expansión de epítopos. En la presente revisión, tratamos de delinear los mecanismos patogénicos que conducen a la desmielinización y daño axonal en este modelo. Se destaca la importancia de las citocinas proinflamatorias para el mantenimiento del proceso inflamatorio, y se describen estrategias terapéuticas relacionadas con el sistema de citocinas pro y antiinflamatorias (AU)

LPS/IFN-gamma cytotoxicity in oligodendroglial cells: role of nitric oxide and protection by the anti-inflammatory cytokine IL-10.

Proinflammatory mediators have been implicated in demyelinating disorders, including multiple sclerosis, whereas it has been proposed that the anti-inflammatory cytokines interleukin- (IL-) 4 and IL-10 participate in disease recovery. The present study analysed the effect of interferon-gamma (IFN-gamma) and bacterial endotoxin (lipopolysaccharide, LPS) on proliferation and survival of progenitors and differentiated oligodendrocytes. We also investigated the presence of receptors for IL-4 and IL-10 in oligodendroglial cells and explored a possible protective action of IL-4 and IL-10 in cultures following LPS/IFN-gamma. Finally, the role of endogenous nitric oxide (NO) on cell viability and the modulatory action of IL-4 and IL-10 on inducible nitric oxide synthase (iNOS) expression were also analysed. We report that LPS and/or IFN-gamma reduced proliferation and viability of oligodendroglial cells. Cell death, presumably by apoptosis as evidence by TUNEL and Annexin V binding, was observed following LPS/IFN-gamma, progenitors being more sensitive than differentiated cells. At both developmental stages, LPS/IFN-gamma-treated cultures expressed iNOS protein and released micromolar concentrations of NO. In progenitors, LPS/IFN-gamma-mediated cell damage was partially dependent on endogenous NO production, whereas NO was fundamental for cytotoxicity of differentiated oligodendrocytes. Both cell types expressed mRNA for IL-4 and IL-10 receptors and expression of IL-10 receptors at the protein level was also demonstrated. Treatment with either cytokine inhibited the expression of iNOS resulting from the proinflammatory stimulation. IL-10 was more effective than IL-4 in suppressing iNOS expression and, interestingly, IL-10 conferred protection against oligodendroglial death evoked by LPS/IFN-gamma. Our data raise the question of whether IL-10 may play a protective role in demyelinating diseases, not only downregulating the function of inflammatory cells but also promoting survival of progenitors and differentiated oligodendrocytes.