T cell activation induces CuZn Superoxide Dismutase (SOD)-1) intracellular re-localization, production and secretion

Reactive Oxygen Species (ROS) behave as second messengers in signal transduction for a series of receptor/ligand interactions. A major regulatory role is played by hydrogen peroxide (H2O2), more stable and able to freely diffuse through cell membranes. CuZn Superoxide dismutase (SOD)-1 is a cytosolic enzyme involved in scavenging oxygen radicals to H2O2 and molecular oxygen, thus representing a major cytosolic source of peroxides. Previous studies suggested that superoxide anion and H2O2 generation are involved in T Cell Receptor (TCR)-dependent signaling. Here, we describe that antigen-dependent activation of human T lymphocytes significantly increased extracellular SOD-1 levels in lymphocyte cultures. This effect was accompanied by the synthesis of SOD-1-specific mRNA and by the induction of microvesicle SOD-1 secretion. It is of note that SOD-1 increased its concentration specifically in T cell population, while no significant changes were observed in the “non T” cell counterpart. Moreover, confocal microscopy showed that antigen-dependent activation was able to modify SOD-1 intracellular localization in T cells. Indeed, was observed a clear SOD-1 recruitment by TCR clusters. The ROS scavenger N-acetylcysteine (NAC) inhibited this phenomenon. Further studies are needed to define whether SOD-1-dependent superoxide/peroxide balance is relevant for regulation of T cell activation, as well as in the functional cross talk between immune effectors

Rôle de la signalisation astrocytaire dans le fonctionnement synaptique : implications dans les maladies neurodéveloppementales

Les astrocytes sont les cellules les plus nombreuses du système nerveux central. Ces cellules sont capables de recevoir des signaux de la microglie et des synapses via des récepteurs couplés aux protéines G (RCPG), présents à leur surface. De plus, les astrocytes se trouvent dans une position exceptionnelle pour répondre aux neurones et à la microglie. Les astrocytes sont aussi connus pour jouer un rôle essentiel dans la progression et la maintenance de l’inflammation du cerveau en répondant et en produisant des médiateurs de l’inflammation. Par ailleurs, des données de la littérature démontrent l’implication d’une inflammation post-natale au cours du développement cérébral dans l’étiologie des principales maladies psychiatriques comme l’autisme et la schizophrénie. Notre hypothèse est qu’une activation anormale des récepteurs Gs RCPG astrocytaires pendant le développement cérébral déclenche la production et la libération de facteurs impliqués dans la formation, maturation et élimination des synapses, qui peuvent altérer la transmission synaptique excitatrice. Pour tester notre hypothèse, nous utilisons la chemogenetique pour activer sélectivement et artificiellement la signalisation Gs RCPG astrocytaire dans le système modèle du cortex visuel murin au cours du développement. Techniques d’immunohistochimie, biochimie et électrophysiologie en vivo, sont également utiliser pour répondre à la question scientifique. Nous avons trouvé que l’activation chronique de la cascade Gs RCPG astrocytaire amène à une augmentation de la production d’une protéine impliquée dans l’élimination de synapses dans le cortex visuel primaire. De plus, nous avons détecté une diminution du numéro de synapses thalamocorticales excitatrices. Notre donnés pourront améliorer la connaissance de la signalisation astrocytaire Gs RCPG dans la physiopathologie du développement du system nerveux centrale. De plus, comme les récepteurs RCPGs sont des potentiels candidats intéressant pour la formulation de traitements, ces résultats pourront ainsi avoir des implications considérables pour le traitement de pathologie neurodéveloppentales.Several neurodevelopmental disorders such as autism and schizophrenia (SZ) are leading contributors to mental ill health, imposing burdens on families as well as individuals. We have studied the role of astrocyte Gs GPCR signaling during brain development, as this astrocyte signaling has been investigated only scarcely in the field, although astrocytes exhibit a wide range of Gs GPCRs on their surface, including those activated by inflammatory mediators. Furthermore, there is accumulating evidence that postnatal inflammation, during brain development, is involved in the etiology of neurodevelopmental disorders. Astrocytes play critical roles in the progression and maintenance of brain inflammation by producing and responding to inflammatory mediators. We hypothesize that perinatal/postnatal chronic inflammation can lead to abnormal activation of astrocytic Gs pathway, which may trigger the production and release of pro-inflammatory molecules and/or synaptogenic, maturation or pruning factors from astrocytes. These effects could subsequently alter excitatory synaptic transmission and plasticity contributing to abnormal long-term changes in excitatory network in adulthood. These mechanisms could underlie the pathogenesis of autism and SZ. We tested this hypothesis in vivo using the rodent primary visual cortex (V1) as a model system, whose maturation is strongly influenced by environmental factors and sensory experience during the critical period of postnatal cortical development. To address our question we used a powerful AAV-based chomogenetic tool combined with immunohistochemistry, biochemistry, and in vivo electrophysiology. We have found that chronic activation of Gs GPCR signaling in astrocytes induces the production of a protein, which is associated with a decrease in the number of thalamocortical excitatory synapses in V1. This study will provide a better understanding of the role of astrocytic Gs GPCR signaling in the physiopathology of brain development, which could have implication in the treatment of some neurodevelopmental diseases, such as autism and SZ

Characterization of transgenic mouse lines for selectively targeting satellite glial cells and macrophages in dorsal root ganglia.

The importance of glial cells in the modulation of neuronal processes is now generally accepted. In particular, enormous progress in our understanding of astrocytes and microglia physiology in the central nervous system (CNS) has been made in recent years, due to the development of genetic and molecular toolkits. However, the roles of satellite glial cells (SGCs) and macrophages-the peripheral counterparts of astrocytes and microglia-remain poorly studied despite their involvement in debilitating conditions, such as pain. Here, we characterized in dorsal root ganglia (DRGs), different genetically-modified mouse lines previously used for studying astrocytes and microglia, with the goal to implement them for investigating DRG SGC and macrophage functions. Although SGCs and astrocytes share some molecular properties, most tested transgenic lines were found to not be suitable for studying selectively a large number of SGCs within DRGs. Nevertheless, we identified and validated two mouse lines: (i) a CreERT2 recombinase-based mouse line allowing transgene expression almost exclusively in SGCs and in the vast majority of SGCs, and (ii) a GFP-expressing line allowing the selective visualization of macrophages. In conclusion, among the tools available for exploring astrocyte functions, a few can be used for studying selectively a great proportion of SGCs. Thus, efforts remain to be made to characterize other available mouse lines as well as to develop, rigorously characterize and validate new molecular tools to investigate the roles of DRG SGCs, but also macrophages, in health and disease

A differential role for the endocannabinoids anandamide and 2-arachidonoylglycerol in modulating the retrieval of cued- and contextual- fear memory

Dysfunctional processes in memory retrieval could be answerable for altered emotional responses and for the development of neuropsychiatric disorders, such as Post-traumatic stress disorder. The endocannabinoid system plays a crucial role in the regulation of memory functions and emotional responses. However, if much has been learned about its engagement in memory acquisition and memory consolidation, evidence on the role of the endocannabinoid system in the retrieval of memory for traumatic experiences are still limited. Here, we investigated the effects induced by pharmacological manipulation of the endocannabinoid signalling in the dorsal hippocampus or in the basolateral complex of the amygdala (BLA) on memory retrieval of fearful events. To this aim, adult male Sprague Dawley rats were trained in a Contextual or Auditory Fear Conditioning task. Sixty minutes before retrieval, they were bilaterally infused, into the BLA or into the dorsal CA1 sub-region of the hippocampus with the FAAH inhibitor, URB597, or the MAGL inhibitor, KML29, in order to increase endogenous levels of anandamide and 2-arachinoyglycerol (2-AG), respectively. We found that, depending on the brain areas committed to encoding the reminder values, anandamide and 2-AG differentially impaired retrieval of aversive memories. We provide evidence that the endogenous cannabinoids anandamide and 2-AG are a key players in regulating fear memory retrieval, opening the way to new potential therapeutic target for the treatment of behavioural disorders where a previous exposure to traumatic events could alter the response to trauma reminder leading to mental illness and neuropsychiatric disorders

Wolff-Parkinson-White syndrome and dilated cardiomyopathy: Not only an electrical issue?

The present case describes a dilated cardiomyopathy associated with both antidromic and orthodromic atrio-ventricular reentrant tachycardias supported by multiple right accessory pathways. Both right accessory path-ways were successfully eliminated by catheter ablation and the patient progressively recovered during the follow up. The following etiologies might be involved: 1) primitive dilated cardiomyopathy (or post-inflammatory); 2) septal dyssinchrony due to ventricular pre-excitation; 3) tachycardiomyopathy

Intraoperative Assessment of Coronary Resistances: A New Quality Marker and Potential Tool to Predict Early Graft Failure after Coronary Artery Bypass Grafting?

: Intraoperative assessment of graft patency is pivotal for successful coronary revascularization. In the present study we aimed to propose a new, easy to perform tool to assess anastomotic quality intraoperatively, and to investigate its potential reliability in predicting early graft failure. Intraoperative graft flowmetry of 63 consecutive patients undergoing CABG were prospectively collected. Transit time flowmetry and its derivatives were recorded. Coronary resistances were calculated according to Hagen-Poiseuille equation both during cardioplegic arrest and after withdrawal from cardiopulmonary bypass. Angiographic evidence of graft occlusion at follow-up was cross-checked with intraoperative recordings. After a mean follow-up of 10.4 ± 6.0 months, 22 grafts were studied, and occlusion was documented in five (22.7%). Occluded grafts showed lower flows and higher resistances recorded during aortic cross-clamping. Coronary resistances, recorded during aortic cross-clamping, greater than 2.0 mmHg/mL/min, showed a sensitivity of 80% and a specificity of 100% to predict graft failure. We propose the routine recording of coronary resistances during aortic cross-clamping as an additional tool to overcome the acknowledged limitation of TTF to predict graft occlusion at 1 year

T cell activation induces CuZn superoxide dismutase (SOD)-1 intracellular re-localization, production and secretion

Reactive oxygen species (ROS) behave as second messengers in signal transduction for a series of receptor/ligand interactions. A major regulatory role is played by hydrogen peroxide (H2O2), more stable and able to freely diffuse through cell membranes. Copper-zinc superoxide dismutase (CuZn-SOD)-1 is a cytosolic enzyme involved in scavenging oxygen radicals to H2O2 and molecular oxygen, thus representing a major cytosolic source of peroxides. Previous studies suggested that superoxide anion and H2O2 generation are involved in T cell receptor (TCR)-dependent signaling. Here, we describe that antigen-dependent activation of human T lymphocytes significantly increased extracellular SOD-1 levels in lymphocyte cultures. This effect was accompanied by the synthesis of SOD-1-specific mRNA and by the induction of microvesicle SOD-1 secretion. It is of note that SOD-1 increased its concentration specifically in T cell population, while no significant changes were observed in the "non-T" cell counterpart. Moreover, confocal microscopy showed that antigen-dependent activation was able to modify SOD-1 intracellular localization in T cells. Indeed, was observed a clear SOD-1 recruitment by TCR clusters. The ROS scavenger N-acetylcysteine (NAC) inhibited this phenomenon. Further studies are needed to define whether SOD-1-dependent superoxide/peroxide balance is relevant for regulation of T cell activation, as well as in the functional cross talk between immune effectors. © 2013 Elsevier B.V