O RAGE é um receptor transmembrana, imunoglobulina-like que existe em múltiplas isoformas e interage com um amplo repertório de ligantes extracelulares. O RAGE é expresso em níveis baixos na maioria das células, porém o aumento da presença de seus ligantes no domínio extracelular faz com que o RAGE inicie uma cascata de sinalização intracelular complexa, resultando em estresse oxidativo, ativação do fator de transcrição NF-B, aumento da expressão de citocinas, além da indução de sua própria expressão. O envolvimento do RAGE neste amplo espectro de sinalização vincula este receptor a diversas condições patológicas. Nesta tese utilizamos 3 modelos experimentais que induzem inflamação sistêmica (Leishmania amazonensis, Lipopolissacarídeo e sepse) e 1 modelo experimental que mimetiza a denervação neuronal (modelos experimentais in vivo). Além disso utilizamos diferentes abordagens de bloqueio do RAGE a fim de elucidar a função deste receptor. Com base em nossos resultados os modelos experimentais foram eficientes em induzir o aumento do RAGE e sua sinalização no sistema nervoso central, desencadeando a síntese e liberação de moléculas pró-inflamatórias e o aumento do estresse oxidativo, culminando em neuroinflamação e neurodegeneração. As intervenções de bloqueio do RAGE foram eficientes em inibir as vias de sinalização intracelular mediadas pelo receptor, comprovando a via de ação. Levando em conta nossos principais resultados concluímos que: a) RAGE atua como mediador da perda neuronal em resposta ao insulto inflamatório em diversas estruturas do SNC, b) está presente no corpo dos neurônios dopaminérgicos e envolvido na morte destes neurônios; c) o aumento do RAGE é tempo-dependente e a morte dos neurônios está vinculada a ação deste receptor. / RAGE is a transmembrane, immunoglobulin-like receptor that exists in multiple isoforms and interacts with a broad repertoire of extracellular ligands. RAGE is expressed at low levels in most cells, but the increased presence of its ligands initiates a complex intracellular signaling cascade resulting in oxidative stress, activation of transcription factor NF-B, increased expression of cytokines in addition to concomitant upregulation of RAGE itself. In this thesis we used 3 experimental models which induce systemic inflammation (Leishmania amazonensis, Lipopolysaccharide and sepsis) and 1 experimental model that mimics neuronal denervation (experimental models in vivo). In addition, different approaches to block RAGE were used to elucidate the function of this receptor. Based on our results the experimental models were efficient in inducing the increase of RAGE and its signaling in the central nervous system, triggering the synthesis and release of proinflammatory molecules and the increase of oxidative stress, culminating in neuroinflammation and neurodegeneration. The RAGE blocking interventions were effective in inhibiting receptor-mediated signaling, proving the signaling pathway. Considering our main results, we conclude that: a) RAGE acts as a mediator of neuronal loss triggered by inflammatory insults in various CNS structures; b) RAGE is present in the body of dopaminergic neurons and is involved in the death of these neurons; c) the increase of RAGE is time-dependent, and the neuronal death is dependent on the action of this receptor.

A neurodegeneração é o resultado da destruição progressiva e irreversível dos neurônios no sistema nervoso central, apresentando causas desconhecidas e mecanismos patológicos não totalmente elucidados. Fatores como a idade, o aumento da formação de radicais livres e/ou estresse oxidativo, defeito no metabolismo energético, a inflamação e acúmulo de elementos neurotóxicos e de proteínas malformadas no lúmen do retículo endoplasmático (RE) contribuem para o desenvolvimento dos processos neurodegenerativos. O sistema canabinoide tem sido proposto como neuroprotetor em diversos modelos de neurodegeneração como hipóxia aguda e epilepsia, isquemia cerebral, lesão cerebral e modelos de estresse oxidativo. Assim, este trabalho teve como objetivo investigar o papel do sistema canabinoide em uma linhagem de neuroblastoma (Neuro 2a) submetida a condições de estresse oxidativo (H2O2), inflamação (LPS) e estresse do RE (tunicamicina), avaliando parâmetros de viabilidade celular e vias de sinalização envolvidas. Nossos resultados mostram que o agonista canabinoide ACEA foi capaz de proteger as células da morte celular causada pela inflamação e pelo estresse de retículo endoplasmático, mas não pelo estresse oxidativo. Esse efeito neuroprotetor exercido pelo ACEA parece pelo menos em parte ocorrer via receptor CB1 no modelo de inflamação e ser independente deste receptor no modelo de estresse de RE. Os efeitos neuroprotetores observados envolveram a modulação dos níveis de proteínas pré-apoptóticas, CHOP e Caspase 12, e da proteína relacionada à sobrevivência celular ERK 1/2. Nossos dados sugerem um papel neuroprotetor do sistema canabinoide em mecanismos relacionados aos processos neurodegenerativos e propõem a manipulação desse sistema como possível alvo terapêutico. / Neurodegeneration is the result of progressive and irreversible destruction of neurons in the central nervous system, with unknown causes and pathological mechanisms not fully elucidated. Factors such as age, increased formation of free radicals and/or oxidative stress, defects in energetic metabolism, inflammation and accumulation of neurotoxic factors and misfolded proteins in the lumen of the endoplasmic reticulum (ER) contribute to the development of neurodegenerative processes. The cannabinoid system has been proposed as neuroprotector in several models of neurodegeneration such as acute hypoxia and epilepsy, cerebral ischaemia, brain injury and oxidative stress models. This work aimed to investigate the role of the cannabinoid system in a neuroblastoma line (Neuro 2a) submitted to oxidative stress (H2O2), inflammation (LPS) and ER stress (tunicamycin) conditions, assessing cell viability parameters and signaling pathways involved. Our results show that the ACEA cannabinoid agonist was able to protect cells from cell death caused by inflammation and ER stress, but not from oxidative stress. This neuroprotective effect exerted by ACEA appears to occur at least in part via the CB1 receptor in inflammation model and it seems to be independent of this receptor in the ER stress model. The neuroprotective effects observed involved the modulation of the levels of pre-apoptotic proteins CHOP and Caspase 12 and the cell survival related protein ERK 1/2. Our data suggest a neuroprotective role of the cannabinoid system in mechanisms related to neurodegenerative processes and propose it as possible therapeutic target.

No description available.

Microglia activity has been detected in Parkinson’s disease (PD) post-mortem brains and experimental animal models; however the precise interplay between microglia and dopamine neurons of the SNpc is not well understood. In the blood plasma of PD patients, our laboratory found elevated levels of interferon-gamma (IFN-γ), a proinflammatory cytokine and potent activator of microglia. Given this, we sought to untangle the immune responses relevant to PD in mice, examining IFN-γ’s involvement and signaling mechanism using an inflammatory co-culture model of microglia and midbrain neurons treated with rotenone. By means of RT-PCR, we discovered IFN-γ mRNA transcripts are produced by microglia, and this expression increases upon exposure to rotenone. We delineated IFN-γ’s signaling mechanism in co-cultures using different IFN-γ receptor deficient cells, and showed it engages receptors in an autocrine (not paracrine) manner to further microgliosis and dopamine cell loss. After exploring the innate immune response in a model of PD, we subsequently shifted focus to an in vivo system to better investigate any involvement of the delayed humoral arm of the adaptive immune system. Needing a time appropriate death paradigm, we developed a protracted low dose regimen of MPTP, which elicits dopaminergic cell death after 2 weeks of treatment. Subjected to this paradigm, Rag 2 mutant mice (deficient in both T and B cells) exhibit resistance to dopamine cell loss, microglia activation and motor impairments. Further evidence in support of immune involvement came with the resensitization of Rag2 mice to MPTP after reconstitution with WT splenocytes. Additionally, mice deficient in Fcγ receptors exhibited neuroprotection in our protracted degeneration model. Taken together, these data indicate the innate and humoral arm can modulate the microglial response to dopaminergic degeneration and may participate in Parkinson's disease.

La maladie d’Alzheimer (MA) est la pathologie neurodégénérative entraînant une démence la plus fréquente. Elle touche plus de 3% des plus de 65 ans. Les lésions cérébrales qui la constituent sont les dépôts de substance β amyloïde (Aβ) et les dégénérescences neurofibrillaires responsables de la mort neuronale, en particulier dans le cortex et l’hippocampe. Ces lésions s’accompagnent d’une réaction inflammatoire centrale qui participe au processus de neurodégénérescence. Les modèles murins d’endotoxémie reproduisent une réaction inflammatoire du système nerveux central comme observé chez l’homme. Nous avons utilisé un modèle murin d’endotoxémie par injections périphériques de LPS et mis en évidence une activation microgliale, une augmentation de la production d’Aβ et de l’expression de BACE1 ainsi qu’une altération du métabolisme dans l’hippocampe des animaux en réponse au LPS. Ces réactions sont contrôlées par la kinase de stress PKR (double-stranded RNA-dependant protein kinase) dont l’invalidation exerce in vivo un effet neuroprotecteur. La production d’Aβ serait régulée dans ce modèle par l’activation PKR-dépendante du facteur de transcription STAT3, responsable du contrôle transcriptionnel de BACE1. L’activation de PKR a été retrouvée à plusieurs niveaux du processus dégénératif associé à la MA et a été identifiée comme un potentiel biomarqueur diagnostique et pronostique de la maladie. Nos résultats confirment le rôle de PKR dans la pathogénèse de la MA et l’intérêt de l’inhibition de PKR pour la recherche thérapeutique. / Alzheimer's disease (AD) is the most common neurodegenerative disease leading to dementia. More than 3% of those over 65 years are affected. Pathological features of AD are β amyloid (Aβ) deposition and neurofibrillary tangles resulting in neuronal death, specifically in cortex and hippocampus. Brain inflammation is associated and involved in the neurodegeneration process. Murine models of endotoxemia show inflammation in the central nervous system as observed in humans. Using a model of endotoxemia by peripheral LPS injections in mice, we observed an activation of microglia, an increase of Aβ production and BACE1 expression and a decreased metabolism in the hippampus of LPS treated animals. These reactions are controlled by the stress kinase PKR (double stranded RNA-dependent protein kinase) whose invalidation exerts a neuroprotective effect in vivo. Aβ production in this model would be regulated by the PKR-dependent activation of the transcription factor STAT3, responsible for transcriptional control of BACE1. Activation of PKR is involved at several levels of the degenerative process associated with AD and has been identified as a potential diagnostic and prognostic biomarker of AD. These results confirm the role of PKR in the pathogenesis of AD and the interest of PKR down-regulation for therapeutic research.

Affecting 1 in 68 children, Autism Spectrum Disorder (ASD) is one of the most prevalent cognitive disorders in the global population. Symptoms of ASD, although typically not life-threatening, have a large impact on the social wellbeing of diagnosed individuals. Inflammation in the brain, or neuroinflammation, has previously been shown to increase the severity of the behavioral deficits associated with ASD. The exact etiology of the neuroinflammation observed in ASD remains unclear, especially in regards to protein expression that initiates the inflammatory pathway. This experiment examines two specific markers of neuroinflammation, glial fibrillary acidic protein (GFAP) and myelin-associated glycoprotein (MAG) in a previously characterized mouse model of ASD. GFAP is astrocyte-specific, cytoplasmic, and has been shown to be upregulated in trauma or disease pathologies in the brain. MAG is found in the membrane of oligodendrocytes and is a major regulator of development and regeneration of nervous tissue. Control C57bl/6j mice and ASD-representative BTBR T+tf/J (BTBR) mice were sacrificed twenty-one days after birth. Immunoblotting was performed on cingulate cortical tissue using anti-GFAP and anti-MAG primary antibodies to quantify levels of GFAP and MAG protein expression between the control and ASD models. These findings provide further evidence that changes in GFAP and MAG expression may alter the neuroinflammatory pathways observed in ASD-representative mice.

Schizophrenia is a devastating mental illness characterized by a broad range of clinical manifestations including hallucinations, social cognitive impairments, and disordered thinking and behavior, all of which impair daily functioning. The immune molecule complement component 4 (C4), located in the major histocompatibility locus (MHC) on chromosome 6 in humans, is highly associated with schizophrenia such that specific structural variants and regulatory regions increase the expression of C4 and confer greater risk for this brain disorder. Besides their established role in brain immune defense, complement proteins play a role in various stages of brain development including neurogenesis, migration and synaptic development. However, C4 has never been experimentally upregulated to determine the impact of increased expression of this immune gene on brain development. Here, I study the role of C4 in layer 2/3 pyramidal neurons in the medial prefrontal cortex of mice to study the hypothesis that C4 overexpression causes circuit dysfunction by leading to the pathological elimination of synapses. Specifically, neuronal connectivity was assayed by measuring dendritic spine density using confocal microscopy and functional connectivity through whole-cell electrophysiology recordings. Additionally, the role of microglia in altering the developmental wiring of the brain was examined by quantifying microglia engulfment in the medial prefrontal cortex. Lastly, complement-induced changes to the prefrontal cortex were accompanied by deficits in social behavior in both juvenile and adult mice. Overall, these studies show that C4 affects brain connectivity by reducing dendritic spine density and excitatory drive through enhanced microglia-engulfment of synaptic material which was sufficient to cause lasting deficits in mouse social behavior.

The principles of neurosurgical and neurointensive care liquorology We observed the development of the cerebrospinal fluid (CSF) patterns in 120 patients after bleeding in the CNS (central nervous system). We used our original cytological- energetic principle to investigate 1453 samples of the CSF from these patients. The principal aim of our investigation is the detection of immunocompetitive cells in the CSF and the specification of their activation via the coefficient of energy balance (KEB). Furthermore we evaluated the numbers of erythrocytes and leucocytes in the CSF and also the catalytic activities of the aspartate aminotranspherase (AST) in the CSF as biomarkers of structural disorder of the CNS. Our goal was to evaluate a three week long development of the CSF patterns to gain more accurate information for a more effective therapy and for a better prediction of further clinical development of these patients. We confirmed that following biomarkers were unfavourable for the development of the CSF compartment and probably the CNS as a whole: higher extent of bleeding in the CNS; higher frequency of the neutrophile granulocytes in the CSF compartment; higher extent of anaerobic metabolism in the CSF compartment; higher level of the catalytic activity of the AST in the CSF; higher age...

Despite the number of therapeutic interventions currently available for treating hypertension, approximately one-third of adult patients in the United States currently being treated remain hypertensive (43). As the number of hypertensive patients continues to grow, it is becoming increasingly important to investigate the different types of hypertension in order to have a greater understanding of the pathogenesis and identify potential targets for treatment. Neurogenic hypertension refers to hypertension resulting from a centrally mediated mechanism, likely involving a sustained increase in sympathetic nervous system activity. The renin-angiotensin aldosterone system (RAAS) is a physiological cascade responsible for restoring blood pressure when it drops. The rate-limiting step involves the enzyme renin. Although there is evidence of local RAAS activity in the brain, expression of renin in the brain is very low (125). The (pro)renin receptor ((P)RR) is able to bind and activate both renin and (pro)renin. Because the (P)RR and (pro)renin expression is high in the brain, it is possible that local RAAS activity is orchestrated by the (P)RR. In this study, we investigated if neuroinflammatory conditions could foster an environment that would allow for a rise in sympathetic nervous system activity (SNA) resulting from brain RAAS activity and the (P)RR. By treating neuronal cell cultures with proinflammatory cytokines, an anti-inflammatory agent, and (pro)renin, we explored any changes or differences in mRNA expression levels. Additionally, the effects of antioxidants were investigated. The results of this study showed that cells lacking antioxidants were more vulnerable to cellular stress and inflammation in the presence of increased (pro)renin. Proinflammatory stress was correlated with increased mRNA expression of proinflammatory and immune system regulatory genes in addition to increased expression of angiotensin II type I receptor, a vital component of RAAS. This could indicate that neuroinflammatory stress can be exacerbated and contribute to increased RAAS activity in the brain mediated by the (P)RR.

Background: Major depressive disorder is associated with elevated levels of DNA oxidation, DNA damage, and gene expression of DNA repair enzymes including poly (ADP-ribose) polymerase-1 (PARP1). Elevated PARP1 activity is directly linked to neuroinflammation and PARP inhibitors are anti-inflammatory and neuroprotective. We previously showed that PARP inhibitors produce antidepressant-like effects equivalent to fluoxetine in rodent models. Here, we examined whether the PARP inhibitor 3-aminobenzamide (3AB) is effective in a rat model of treatment-resistant depression. Methods: Treatment-resistant depression was modeled with injections of lipopolysaccharide (LPS; 0.1 ug/kg/day) and daily chronic unpredictable stress (CUS) for 28 days. Anhedonia and helplessness were indexed with sucrose preference and forced swim tests, respectively, in 5 groups of rats (n¼6-8 rats/group) including unstressed, CUS, and CUS+LPS rats treated with saline, and CUS+LPS rats treated with either 3AB or fluoxetine. Results: Anhedonia induced by CUS+LPS was significantly attenuated by 3AB (p¼0.01), while fluoxetine failed to do so. Likewise, 3AB was superior to fluoxetine in reducing helplessness, where latency to immobility times were significantly lower in CUS+LPS rats treated with fluoxetine (p¼0.001) compared to unstressed rats, but not significantly different for 3AB-treated CUS+LPS rats. Conclusions: The PARP inhibitor 3AB demonstrated robust and unique antidepressant activity superior to fluoxetine in the TRD rat model. PARP is linked to neuroinflammation through release of microglia-activating factors including poly (ADP-ribose) and HMGB1, and through NF-kB activation, pathways under investigation by our lab. PARP inhibitors are currently used clinically to facilitate cytotoxicity of DNA-damaging anti-cancer treatments. Further research could implicate re-purposing non-cytotoxic PARP inhibitors for treatment-resistant depression.