Les patients SLA et les souris modèles présentent un dysfonctionnement métabolique qui coïncide avec le changement de concentration de différentes espèces lipidiques. Notre hypothèse est qu’un tel dysfonctionnement métabolique au niveau musculaire conduirait aux premiers changements observés dans la SLA. Nous avons montré que l’expression de la stéaroyl-coenzyme A désaturase 1 (SCD1), une enzyme clé de la synthèse des acides gras mono-insaturés à partir des acides gras saturés, est diminuée dans le muscle avant les premiers symptômes moteurs observés chez les souris modèles de SLA. Dans ce modèle murin, les altérations en acides gras au niveau circulant et hépatique, traduisant les changements de SCD1,apparaissent lors des premiers symptômes de la pathologie. De plus, l’inhibition pharmacologique de l’activité de SCD1 mime le phénotype métabolique des souris modèles de SLA. Notre étude a ainsi montré que la diminution de la SCD1 joue un rôle important pour l’activité neuromusculaire. Elle module les besoins énergétiques, maintien l’activité musculaire par augmentation du métabolisme oxydatif et agit sur l’expression de gènes impliqués dans le développement et le fonctionnement de la jonction neuromusculaire. De plus, l’ablation du gène SCD1 stimule la récupération fonctionnelle musculaire après lésion du nerf. L’inhibition pharmacologique de SCD1 apporte également une protection au muscle. Nous avons pu conclure de cette étude qu’une modification de l’expression de SCD1 ainsi que du profil d’acides gras peut apporter une protection au muscle pour lutter contre la pathologie. En outre, des inhibiteurs de l’activité enzymatique de la SCD1 pourraient être développés comme traitement thérapeutique dans la SLA. / ALS patients and mouse model manifest metabolic dysfunctions that coincide with the modified levels of various lipid species. We postulated that metabolic dysfunctions in muscles function as a leading preliminary change in ALS. We have noted that the expression of stearoyl-CoA desaturase 1 (SCD1), a key enzyme that synthesises monounsaturated fatty acids (MUFAs) from saturated fatty acids (SFAs), is diminished even at pre-symptomatic stage in the muscles of an ALS mouse model. In these mice, alterations in circulating and hepatic fatty acid composition, resulting from SCD1 modification, arise at a critical stage of disease onset. Of note, inhibition of SCD1 enzymatic activity by a specific pharmacological agent mimics the metabolicphenotype of the ALS mouse model. Our study also elucidates that the lack of SCD1 plays a vital role in neuromuscular function. It modulates energy supply, and maintains muscle activity by increasing oxidative metabolism and the expression of genes involved in neuromuscular junction development and function. In addition, ablation of SCD1 gene stimulates functional recovery of muscles after a nerve lesion. Pharmacological SCD1 inhibition also provides a protection to muscle function. We conclude that alteration in SCD1 expression and related altered fatty acid profile may protect muscles against pathology. Therefore, SCD1 inhibitors can be developed as a therapeutic intervention.

La sclérose latérale amyotrophique est une maladie neurodégénérative associée à un dysfonctionnement métabolique. Des altérations du métabolisme des lipides, décrites chez les patients SLA et les animaux modèles, pourraient participer à la mise en place des premières étapes de la maladie. L’objectif de cette thèse était d’étudier le rôle de la stéaroyl-coenzyme A désaturase 1 (SCD1), une enzyme clé du métabolisme des lipides, dans la SLA. En étudiant le profil d’acides gras périphériques dans un modèle de souris SLA, les souris SOD1m, nous avons vu une diminution de l’activité de la SCD1 dès les stades précoces (subcliniques) de la maladie. Cette diminution pourrait expliquer, à elle seule, les altérations du métabolisme des lipides caractéristiques de la SLA. La répercussion de la perte de l’activité de la SCD1 sur l’axe moteur a été étudiée. Une délétion du gène ou une inhibition pharmacologique de la SCD1 améliore la récupération fonctionnelle après lésion du nerf sciatique chez la souris sauvage. Nous avons cherché à voir si la perte d’activité de la SCD1 trouvée chez les souris SOD1m est un mécanisme de protection mis en place pour lutter contre l’évolution de la SLA. Nous avons traité des souris SOD1m avec un inhibiteur de l’activité de la SCD1. Le traitement a conduit à une augmentation du métabolisme oxydatif, une préservation de l’intégrité neuromusculaire ainsi qu’une amélioration de la survie des motoneurones. Nousconcluons que l’inhibition de la SCD1 représente une cible thérapeutique prometteuse dans la SLA. / Amyotrophic lateral sclerosis is a neurodegenerative disease, associated with metabolic dysfunction. Alteration of lipid metabolism has been documented in ALS patients and animal models, and could participate to the first pathological steps of the disease. The objective of this thesis was to study the role of stearoyl-CoA desaturase 1 (SCD1), a key enzyme of lipid metabolism, in ALS. By studying the profile of peripheral fatty acids in an animal model of ALS, the SOD1 mice, we found that SCD1 activity was strongly reduced at early (sub-clinical) disease stage, and that this reduction could explain in itself the alteration of lipid metabolism characteristic of ALS. The impact of loss of SCD1 activity for the motor axis was then studied. Genetic deletion or pharmacological inhibition of SCD1 enhanced functional recovery after sciatic nerve injury in mice. Wefurther explored if the loss of SCD1 activity found in SOD1 mice is a protective mechanism elicited in response to ALS. We treated SOD1 mice with an inhibitor of SCD1 activity. The treatment resulted in exacerbated muscular oxidative metabolism,preservation of neuromuscular integrity and enhanced motor neuron survival. We conclude that inhibition of SCD1 represents a promising therapeutic target for ALS.

Introdução: A esclerose lateral amiotrófica (ELA) é uma doença neurodegenerativa progressiva, de etiologia desconhecida, que envolve os neurônios motores do córtex cerebral, do tronco encefálico e da medula espinhal. O comprometimento dos neurônios motores inferiores causa disfagia, distúrbios de fala e outros sintomas, como fraqueza muscular global e sintomas respiratórios. A dificuldade de deglutição ou disfagia pode causar complicações, como pneumonia aspirativa, má nutrição e desidratação, e afeta a qualidade de vida destes pacientes, sendo necessária a indicação de via alternativa de nutrição. Atualmente, esta indicação é dada subjetivamente pelo exame clínico e funcional realizado pela equipe multidisciplinar, de acordo com a deterioração dos parâmetros da função respiratória, do estado nutricional e de comprometimentos na deglutição. Objetivos: objetivo geral: verificar se a redução de pressão de língua pode ser indicadora de necessidade de gastrostomia (GEP) como via alternativa de nutrição em pacientes com diagnóstico de ELA. Objetivos específicos: verificar se há redução significativa nas medidas funcionais e de pressão de lábio, de língua e de bochecha entre o momento da primeira avaliação e da indicação da GEP; avaliar o tempo desde o primeiro sintoma da doença até a indicação da GEP; verificar se o tempo de indicação da GEP foi influenciado por variáveis demográficas, manifestação clínica inicial (espinhal ou bulbar), condições clínicas, medidas funcionais globais e de deglutição, com destaque para pressão de língua, de lábios e de bochechas. Métodos: Foram estudados longitudinalmente 63 pacientes, avaliados do ponto de vista fonoaudiológico com os instrumentos: escala ASHA, escala ALSFRS, avaliação funcional, medida de pressão dos órgãos fonoarticulatórios com o aparelho IOPI, encaminhamento para videoendoscopia da deglutição (VED) e capacidade vital forçada (CVF) no momento da indicação da GEP. Resultados: Os pacientes tinham faixa etária entre 28 e 79 anos (média de 58 anos de idade), com média de 7,04 anos de escolaridade, tempo médio de doença no momento da avaliação inicial de 34,96 meses, 32% manifestação clínica inicial da forma bulbar, 39,5% espinhal membros superiores e 28,5% espinhal membros inferiores, porém, na avaliação fonoaudiológica inicial, todos apresentavam alguma queixa de acometimento bulbar. Cinquenta pacientes foram encaminhados à GEP, 1 foi a óbito e 12 mantiveram dieta via oral exclusiva até o término do estudo. Medidas funcionais e de pressão de língua, lábio e bochecha apresentaram redução significativa no agravamento da ELA (p < 0,001). Dificuldades com líquido espessado: de contenção (p=0,001), de transporte (p=0,005) e de proteção de vias aéreas inferiores (p =0,003), e com a consistência pastosa: contenção na cavidade oral, (p < 0,001) observadas em avaliações clínicas fonoaudiológicas, e a idade (p =0,014) influenciam na indicação de GEP. Conclusão: A medida de pressão de língua pode, portanto, servir como um indicador adicional, objetivo e prático para o exame do prognóstico da funcionalidade da deglutição, e, em particular, da possibilidade ou não de manutenção de vias tradicionais em pacientes com diagnóstico de ELA / Introduction: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of unknown etiology that involves motor neurons from the cerebral cortex, from the brainstem and from the spinal cord. The damage on the lower motor neurons causes dysphagia, speech disorders and other symptoms such as overall muscle weakness and respiratory symptoms. The difficulty in swallowing, or dysphasia, may cause complications such as aspiration pneumonia, malnutrition and dehydration and affects the quality of live of these patients. Thus, it is necessary to indicate and alternative form of nutrition. This indication is currently given subjectively by the clinical and functional evaluation performed by the multidisciplinary team, according to deterioration of respiratory function parameters, nutritional status and swallowing impairments. Objectives: general objective: verify if reduced tongue pressure could indicate the need for gastrostomy (PEG) as an alternative form of nutrition for patients who have been diagnosed with ALS. Specific objectives: verify if there is significant reduction on tongue, lips, and cheeks pressure as well as functional measures between the moment of the first evaluation and the indication of PEG; evaluate the time between the first symptom of the disease and the indication of PEG; verify if the time of the indication of PEG was influenced by demographic variables, initial clinical manifestation (spinal or bulbar forms), clinical conditions, global and swallowing functional measures, highlighting tongue, lips and cheeks pressure. Methods: 63 patients have been longitudinally studied. They have been assessed from the speech-language therapy point of view with the following instruments: ASHA, ALSFRS, functional evaluation, pressure measurement of the phono-articulatory organs with the IOPI, referral to videoendoscopy of swallowing and FVC at the moment of the indication of PEG. Results: The patients, whose ages ranged from 28 to 79 years old (average of 58 years old), had, on average, 7.04 years of education. They had been suffering from the disease for an average of 34.96 months at the time of the first evaluation. 32% showed initial clinical manifestation of the bulbar form, 39.5% upper limbs spinal form and 28.5% lower limbs spinal form. At the initial speech-language therapy assessment, however, all of them showed some sort of complaint regarding bulbar impairment. 50 patients were sent to PEG, 1 died and 12 continued with an oral exclusive diet until the end of this study. Tongue, lips and cheeks as well as functional measures showed significant decrease with the aggravation of ALS (p < 0,001). Difficulties with thickened liquid: with containment (p=0,001), with transport (p=0,005) and with protection of lower airways (p =0,003) and with pasty consistencies: containment in the oral cavity, (p < 0,001) observed in speech-language therapy clinical assessments, as well as age (p =0,014) have influence on the indication of PEG. Conclusion: The measure of the tongue pressure can, therefore, serve as an additional, objective and practical indicator for the evaluation of the prognosis of swallowing functionality, particularly of the possibility or not of maintenance of traditional forms in patients who have been diagnosed with ALS

A Esclerose Lateral Amiotrófica (ELA) é uma doença progressiva e fatal causada pela degeneração seletiva dos neurônios motores do cérebro e medula. Dos casos familiares de ELA (fELA), 20% são causados por mutações pontuais no gene da sod1. O ácido docosahexaenoico (C22:6, n-3, DHA) é um ácido graxo altamente insaturado, sendo um dos principais ácidos graxos da massa cinzenta do cérebro. Estudos têm correlacionado mutações de SOD1 com a formação de agregados que poderiam ser induzidos por ácidos graxos insaturados. O objetivo deste estudo foi avaliar os efeitos e mecanismos do DHA e de seus hidroperóxidos (DHAOOH) na agregação de SOD1 in vitro. As análises de dicroísmo circular (CD) mostraram mudanças na estrutura secundária de ambas as proteínas apo-SOD1WT e G93A promovidas pelo DHA, resultando em aumento de superfície hidrofóbica e formação de estruturas do tipo beta-amilóide, como mostrado pelos ensaios do bis- ANS e Tioflavina, respectivamente. Estas mudanças resultam na formação de agregados amorfos como observado por microscopia eletrônica de varredura (MEV). Espécies de alto peso molecular foram observadas nas incubações do DHA com as formas apo da SOD1 por SDS-PAGE sob condições não redutoras e também por cromatografia de exclusão por tamanho. A formação dos agregados mostrou-se dependente de resíduos de Cys na sua forma desprotonada, visto que agregados não foram observados na presença de beta-mercaptoetanol e sua formação foi inibida na presença de bloqueador de tióis e em pH ácido. Além disso, análises por cromatografia de exclusão mostraram que a agregação é dependente da insaturação e conformação cis dos ácidos graxos. Comparativamente ao DHA, os hidroperóxidos do DHA tiveram um efeito menor na agregação de SOD1, porém revelaram a propriedade de induzir a dimerização covalente de SOD1. No geral, os dados mostram que o DHA induz a agregação de SOD1, através de um processo envolvendo a exposição de superfícies hidrofóbicas, formação de pontes dissulfeto e também de possíveis cross-links envolvendo reações do tipo \"ene-tiol\". / ALS is a progressive and fatal disease caused by selective degeneration of motor neurons in the brain and spinal cord. Twenty percent of familial ALS (fALS) cases are caused mainly by point mutations in the sod1 gene. Docosahexaenoic acid (C22:6, n-3, DHA) is a highly unsaturated fatty acid, wich is one of the main fatty acids in the cerebral gray matter. Studies have linked SOD1 mutations to the formation of aggregates that could be induced by unsaturated fatty acids. The aim of this study was to evaluate the effect of DHA on aggregation of SOD1 fALS mutants in vitro and its mechanisms. CD analysis shows changes in the secondary structure of both apo-SOD1WT and G93A promoted by DHA resulting in an increase in the surface hydrophobicity and formation of structures such as beta amyloid, which was also confirmed by bis-ANS assay and Thioflavin, respectively. These changes enhance the interaction of SOD1 and DHA, leading to amorphous aggregates as revealed by FESEM. Incubation of DHA with apo-SOD1 forms results in high-molecular weight species as detected by SDS-PAGE analyses under non-reducing conditions and also by size exclusion chromatography. This appears to require Cys residues in their thiolate forms because high aggregates are not observed under reducing conditions and also by size exclusion chromatography or at acidic pH. Also, size-exclusion chromatography indicates that the mutant apo-SOD1 aggregation is dependent on the unsaturation and cis-conformation of fatty acids. Compared to the DHA, DHAOOH had a minor effect on SOD1 aggregation, however revealed the ability to induce covalent dimerization of SOD1. Overall, the data suggest a mechanism of DHA aggregation, by a process involving exposure to hydrophobic surfaces, formation of disulfide bonds and also for possible cross-links involving reactions such \"thiol-ene\".

O presente trabalho teve como objetivo geral descrever e analisar os processos de luto e perdas progressivas, vividos por uma pessoa idosa com Esclerose Lateral Amiotrófica (ELA), consciente destas perdas. Foi realizada uma pesquisa qualitativa, sob o enfoque fenomenológico, a partir de um estudo de caso. Como dados de análise, foram utilizados os relatos de sessões de psicoterapia domiciliar, com o consentimento livre e esclarecido da participante. Por meio desse material, foram selecionados os relatos em que se observavam a temática perda em decorrência da doença. Esses relatos compuseram quatro unidades de significado: Os Movimentos, A Fala, A Segurança e A Independência, caracterizadas pelas perdas mais significativas vividas pela participante durante o processo evolutivo da doença. As duas primeiras unidades estão relacionadas diretamente à doença, uma vez que figuram como características da ELA. As perdas da segurança e da independência estão presentes na maioria das situações de adoecimento. Sobre a vivência descrita nesse trabalho, destacam-se o vínculo familiar, o cuidador principal, a religião e o atendimento domiciliar como fatores que contribuem para o alívio do sofrimento da pessoa com ELA. Com relação à atuação do psicólogo, destacam-se, entre outras ações, a busca de recursos alternativos ao paciente diante das sucessivas perdas, considerando suas idiossincracias e necessidades específicas. A aproximação e o vínculo afetivo entre o profissional e o paciente, bem como o respeito aos seus valores e a sua história de vida são fatores fundamentais para a obtenção desses recursos. Além disso, o psicólogo deve oferecer ajuda e amparo aos familiares que também podem adoecer, necessitando de carinho e atenção profissional. Além da psicoterapia pessoal, para que essa experiência de atendimento tenha resultados positivos e satisfatórios para o estudante, para o profissional e, principalmente, para o paciente e seus familiares, são fundamentais os estudos sobre a morte e o morrer, as supervisões dos casos atendidos, o compartilhamento das vivências / The general objective from this work is to describe and analyze the mourning and progressive losses processes experienced by an elder person with Amyotrophic Lateral Sclerosis (ALS), provided that such person was aware of these losses. Starting from a case study, a qualitative research has been conducted focused on phenomenological aspects. Data from home psychotherapy sessions reports were used, and the participant has consented this usage in a free and informed way. Through this material, a selection process has separated the reports in which the loss theme has been mentioned as a consequence of the disease. These reports have formed four meaning units: Movements, Speech, Safety and Independence, characterized by the most significant losses experienced by the participant during the diseases evolutionary process. The first two units are directly related to the disease, as they are listed as ALS characteristics. Safety and independence issues are experienced by most of the people affected by the disease. Regarding the experience described in this work, its possible to list the family support, the main caretaker, the religion and the home attention as the main factors which may help the person to ease the sufferings caused by ALS. Regarding the psychologist aid, the most important aspect is to seek alternative resources for the patient to help him/her to deal with successive losses, considering the specific idiosyncrasies and needs. The approximation and the emotional connection between the professional and the patient, as well as the respect to the patients values and life story, are vital factors to obtain these resources. Besides, the psychologist shall offer help and support to the family members who are also subject to getting sick. They may also need professional care. Besides the personal psychotherapy, for this attention experience to be successful regarding the student, the professional and specially the patients and their families, the following aspects are vital: studies about death and losses, the supervisions on specific cases, the sharing of experiences and the knowledge about the physical and emotional aspects connected to the disease.

A Esclerose Lateral Amiotrófica (ELA) é uma doença neurodegenerativa progressiva e incurável, caracterizada pela perda seletiva dos neurônios motores (NM) superiores e inferiores com uma sobrevida média de 3 anos. As manifestações clínicas dependem da topografia e comprometimento dos NM. De causa desconhecida, descrições apontam para a participação das células gliais (astrócitos, microglia e célula de Schwann) na toxicidade neuronal. A retração precoce do axônio no músculo esquelético sugere a participação da célula de Schwann na morte neuronal retrógrada (dying back). Este estudo descreveu as alterações na expressão gênica no nervo motor extensor curto do hálux ainda funcionante dos pacientes ELA e o ramo motor do nervo acessório de sujeitos-controle (19 ELA, sendo 9 ELA espinhal e 5 ELA bulbar; 5 controles), utilizando-se plataformas expandidas de microarranjos de DNA (microarray) e análises de bioinformática (DAVID e os seus bancos de dados Kyoto Encyclopedia of Genes and Genomes e o Gene Onthology Consorciun Anottation). Os resultados foram validados por PCRq e Redes de Interação de Proteínas foram geradas pelo Cytoscape. Foram encontrados 138 genes diferencialmente expressos entre esses grupos. O ribossomo e a síntese proteica foram apontados como elementos centrais no estudo em eventos relacionados tanto à neurotoxicidade quanto a protetivos. As Redes destacaram o gene EPS8 na ELA (ambas as formas, ELA bulbar e espinhal) em relação aos controles e o gene FAU na ELA bulbar em relação à ELA espinhal. Os genes e as vias apontados neste estudo deverão ser testados como alvos terapêuticos em estudos futuros envolvendo a ELA / Amyotrophic lateral sclerosis (ALS) is an incurable progressive neurodegenerative disease characterized by the selective loss of upper and lower motor neurons (MN), with a median survival of 3 years. Clinical manifestations depend on onset site and involvement of the MN. Although the cause of ALS is unknown, reports point towards the participation of glial cells (astrocytes, microglia and Schwann cells) in the neuronal toxicity. The early retraction of the axonium indicates a participation of the Schwann cells in retrograde neuronal death (dying back). The current study described the abnormalities in the genic expression of the functioning extensor hallucis brevis motor neuron from ALS subjects, and the motor branch of the accessory nerve from control subjects (19 ALS, being 9 spinal and 5 bulbar types; 5 controls), through an expanded platform of DNA microarrays and bioinformatics analyses (DAVID, Kyoto Encyclopedia of Genes and Genomes, and Gene Onthology Consortium Annotation databases). The results were validated by Quantitative PCR (PCRq) and Protein-Protein interaction network generated by Cytoscape. A total of 138 differentially expressed genes were found in these groups. In this study, the ribosome and protein synthesis were pointed as central elements related both to neurotoxicity and protective events. These networks highlighted the EPS8 gene in ALS (in both types, bulbar and spinal) when correlated to controls, and the FAU gene in bulbar ALS in relation to spinal ALS. The genes and pathways identified in this study should be tested as therapeutic targets in future studies approaching ALS

La sclérose latérale amyotrophique (SLA) est une maladie neurodégénérative incurable caractérisée par la perte sélective des motoneurones du cerveau et de la moelle épinière. Elle se manifeste par une faiblesse musculaire qui évolue vers une paralysie, entrainant la mort du patient dans les 3 à 5 ans après l’apparition des symptômes. Une réponse inflammatoire associée à l'accumulation de cellules immunitaire dans le système nerveux central (SNC) est une signature de la SLA. Ce travail propose d'étudier le rôle des cellules résidentes du SNC, notamment les astrocytes, et des cellules immunitaires périphériques, notamment les lymphocytes T CD8+, dans la SLA. Nous montrons qu'une fois infiltrées dans le SNC des souris mutantes modèles de la SLA (lignée SOD1G93A) des cellules T CD8+ s'activent et subissent une expansion de type oligoclonale. In vitro, les cellules T CD8+ issues de souris SOD1G93A sont capables d'induire la mort des motoneurones spécifiquement, par un mécanisme dépendant de la liaison du TCR avec le CMH de classe I. Nous rapportons que la déplétion périphérique des cellules T CD8+ chez les souris modèles de SLA permet de protéger une partie des motoneurones des processus neurodégénératifs. Une approche génétique permettra de confirmer l'implication des lymphocytes cytotoxiques dans l'évolution de la maladie. / Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that is characterized by the selective loss of upper and lower motoneurons. Symptoms appears as muscular weakness, which irrevocably leads to muscle paralysis and death of patients within 3 to 5 years after onset of symptoms. An inflammatory response, along with the accumulation of blood-derived immune cells in the central nervous system (CNS) is a hallmark of the disease. This work proposes to investigate the role of resident cells of the brain, such as astrocytes and especially peripheral immune cells such as T CD8+ lymphocytes, in ALS pathogenesis. We show that once infiltrated in the CNS of SOD1G93A mice, CD8+ T cells become activated and undergo an oligoclonal expansion. In vitro, CD8+ T cells isolated from ALS mouse model (SOD1G93A strain) can trigger motoneuron death, in a manner that is dependent on the recognition of the MHC class I by TCR. We report that peripheral immunodepletion of CD8+ T cells is not sufficient to improve lifespan of SOD1G93A mice, but still permit to protect motoneurons from neurodegeneration. A genetic approach will confirm implication of CD8+ T lymphocytes in the disease.

La Sclérose Latérale Amyotrophique (SLA) est une maladie neurodégénérative due à la dégénérescence des motoneurones supérieurs et inférieurs. La perte des neurones moteurs entraine une atrophie puis une paralysie progressive des muscles. En plus de la perte musculaire, une perte de poids est importante chez les patients SLA. Ce symptôme apparaît avant les premiers symptômes moteurs et est corrélé avec la survie. Ce défaut du métabolisme énergétique est en partie dû à un hypermétabolisme associé à des problèmes de prise alimentaire. L’hypothalamus est la partie du cerveau contrôlant l’ensemble du métabolisme énergétique. L’objectif de ma thèse a été de caractériser les altérations hypothalamiques dans la SLA. Nous avons tout d’abord mis en évidence une anomalie du système mélanocortine de l’hypothalamus, et montré que cette anomalie était associée à des modifications du comportement alimentaire. Ensuite, nos travaux ont mis en évidence une atrophie de la partie postérieure de l’hypothalamus, comprenant l’aire hypothalamique latérale (LHA), des patients SLA, corrélée à la perte de poids. Finalement, nous démontré que les neurones produisant le MCH, situés dans le LHA, sont atteints dans la SLA et qu’une complémentation en MCH empêche la perte de poids dans un modèle animal de SLA. / Amyotrophic Lateral Sclerosis (ALS) is a major neurodegenerative disease characterised by a loss of upper and lower motor neurons. The loss of motor neurons leads to muscle atrophy and paralysis. Besides motor loss, weight loss is important in ALS patients. This symptom appears before first muscular symptoms and is correlated with survival. This defect of energetic metabolism is partially due to hypermetabolism associated with food intake problems. Hypothalamus is the part of brain controlling the energetic metabolism. The aim of my Ph.D. was to characterise hypothalamic alterations in ALS. First, we have shown a default in the melanocortin system of hypothalamus, and shown that this melanocortin defect correlates with alterations in food intake behaviour. Second, we demonstrated the existence of hypothalamic atrophy in ALS patients in the posterior part of the hypothalamus, including the lateral hypothalamic area (LHA). This atrophy was correlated with weight loss. Finally, we observed that hypothalamic MCH neurons, located in the LHA, are affected in ALS, and that MCH complementation rescues weight loss in a mouse model of ALS.

Injury and neurodegenerative conditions of the spinal cord can lead to paralysis and loss of sensation. Cell therapeutic approaches can restore sensory innervation of the spinal cord following injury and protect spinal cord cells from degeneration. This thesis primarily focuses on the restoration of deaffarented sensory fibres following injury to the dorsal root and spinal cord. These injuries lead to the formation of a non-permissive glial scar that prevents sensory axons from reinnervating spinal cord targets. It takes advantage of a dorsal root injury model that closely mimics spinal root avulsion injuries occurring in humans. In the first part of the thesis, three different neural progenitor types from human or murine sources are tested for their regenerative properties following their transplantation to the site of dorsal root avulsion injury. In the second part, the ability of murine neural progenitors to protect spinal motor neurons from a neurodegenerative process is tested. In the first original research article, I show that human embryonic stem cell derived neural progenitors are able to restore sensorimotor functions, mediated by the formation of a tissue bridge that allows ingrowth of sensory axons into the spinal cord. In the second research article, I present that murine boundary cap neural crest stem cells, a special type of neural progenitor that governs the entry of sensory axons into the spinal cord during development, are unable to form a permissive tissue bridge. This is possibly caused by the contribution of transplant derived ingrowth non-permissive glial cells. In the third research article, I show that human neural progenitors derived from foetal sources are capable of stimulating sensory ingrowth and that they ameliorate the glial scar. When this approach is combined with the delivery of sensory outgrowth stimulating neurotrophic factors, these cells fail to form a permissive tissue bridge and fail to modify the glial scar. In the final research article, murine boundary cap neural crest stem cells are shown to protect motor neurons, which harbor an amyotrophic lateral sclerosis causing mutation, from oxidative stress. Oxidative stress is a pathological component of amyotrophic lateral sclerosis in human patients. Taken together, this thesis provides first evidence that sensory regeneration following a spinal root avulsion injury can be achieved by transplantation of human neural progenitors. In addition, it introduces murine boundary cap neural crest stem cells as interesting candidates for the cell therapeutic treatment of amyotrophic lateral sclerosis.

La sclérose latérale amyotrophique (SLA) est une maladie neurodégénérative incurable, qui touche les motoneurones de la moelle épinière et du cerveau. Elle se manifeste par une faiblesse musculaire qui évolue rapidement vers une paralysie générale, entrainant la mort du patient. Les principes moléculaires conduisant à la dégénérescence sélective des motoneurones demeurent encore mal connus, entravant le développement de nouvelles thérapies. Mon travail de thèse a permis l'identification d'une nouvelle voie de mort spécifique aux motoneurones, qui dépend du récepteur LT-&#946;R et de son ligand LIGHT. De plus, cette voie de mort peut être déclenchée par une cytokine pro-inflammatoire, qui est l'interféron gamma (IFN&#947;). Nous avons pu montrer des signes d'activation de cette voie de mort chez des souris modèles de la SLA ainsi que dans les tissus de patients atteints de la maladie. En effet, on observe au cours de la maladie une augmentation des niveaux d'IFN&#947; dans les astrocytes et les motoneurones. Une approche génétique a par la suite permis de démontrer l'implication fonctionnelle de cette voie de mort dans le processus pathologique. / Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease affecting primarily motoneurons in the brain and spinal cord. Symptoms of the disease include general muscle weakness, rapidly evolving in an overall paralysis, leading to the death of the patient. The precise mechanisms responsible for the selective vulnerability of motoneurons remain largely unknown, impeding therefore the development of effective therapies. My thesis work led to the discovery of a novel motoneuron selective death pathway dependent on the activation of LT-&#946;R by LIGHT. This death pathway might also be triggered by the pro-inflammatory cytokine interferon gamma (IFN&#947;). Interestingly, we have documented signs of activation of this pathway in ALS mice and sporadic ALS patients, with IFN&#947; being upregulated in astrocytes and motoneurons. Furthermore, a genetic approach has provided evidence of the functional involvement of this death pathway in the pathogenic process.