One of the major limitations in drug development and gene therapy for brain diseases is the natural defensive structure called the blood brain barrier (BBB), which prevents therapeutic polypeptide drugs and viral vectors from entering the brain. Intranasal delivery of therapeutic gene products into the brain offers a non-invasive alternative towards a feasible gene and protein therapy for neurological diseases. From recent studies involving axonal transport, it is tempting to speculate that therapeutic macromolecules including neurotrophic factors and viral vectors can be delivered into the brain by peripheral neurons, such as olfactory receptor neurons (ORNs), which span the BBB. It is thought that the nasal pathway into the brain involves two general mechanisms; intracellular (intraneuronal) or extracellular routes of transport. However the pathways involved have not yet been fully characterized. In this study I firstly investigated the temporal and spatial localisation pattern of both biotinylated and I125 labelled ciliary neurotrophic factor (CNTF) following nasal delivery into Sprague-Dawley rats. Results showed that intranasal delivered CNTF was transported to several brain regions by both intracellular axonal pathway through ORNs and the extracellular trigeminal pathway. Excess unlabelled CNTF competed for receptor binding in the olfactory mucosa confirming receptor mediated intracellular transport to the olfactory bulb via ORNs. Denervation of the olfactory mucosa prior to CNTF delivery failed to prevent CNTF transport to trigeminal and hypothalamic brain regions. Intranasal delivered CNTF was biologically active, resulting in activation of the STAT3 signalling pathway in the thalamus and hypothalamus. To examine the functional activity of intranasal delivered CNTF, I conducted a weight loss trial using an obese Zucker rat (OZR) model to test whether CNTF treatment caused body weight loss. Intranasal administration of CNTF resulted in reduced body weight in the CNTF treated OZR group compared to the BSA control group during the 12 day trial and for 3 days after. Intranasal delivery of CNTF may be a valuable method for the treatment of obesity. In the second study, I investigated the temporal and spatial expression of Enhanced Green Fluorescent Protein (EGFP) transferred by a single nasal delivery of either a recombinant adenovirus vector (Ad5CMV-EGFP) or an adeno-associated virus vector (AAV2-EGFP) into Sprague-Dawley rats. Adenovirus mediated EGFP expression was localized in ORNs throughout the olfactory epithelium after 24 hours. EGFP in the ORNs appeared to be anterogradely transported along their axons to the olfactory bulb and transferred in glomeruli to second-order neurons. EGFP was transferred to several brain regions including the cortex, hippocampus, and brainstem after 7 days. EGFP expression co-localized with Olfactory Marker Protein and was confirmed with EGFP immunofluorescence labelling and western blotting. AAV expressed EGFP localized in similar olfactory and brain regions 6 weeks after delivery. mRNA levels suggested that the AAV-EGFP construct was only incorporated into olfactory mucosa cells and the viral vector was not present in olfactory bulb and brain regions. In conclusion, this simple and non-invasive polypeptide and gene delivery method provides ubiquitous macromolecule distribution throughout the rodent brain and may be useful for the treatment of neurological disorders.

Made available in DSpace on 2016-08-29T15:35:05Z (GMT). No. of bitstreams: 1 tese_7779_TESE LBF-2014.pdf: 10712510 bytes, checksum: 8a20db56f2fe6ca735be70a109f4ef61 (MD5) Previous issue date: 2014-06-04 / O câncer de colo uterino (CCU), cujo agente etiológico é o papilomavírus humano (HPV), é um dos tipos de câncer mais frequentes em mulheres em todo o mundo, não só em incidência como também em mortalidade. Alguns genótipos de HPV, denominados de alto risco (HR-HPV), e suas variantes gênicas, estão mais associados à indução de lesões malignas, sendo HPV16 e 18 os mais frequentes. Algumas infecções do trato genital podem atuar como cofatores da progressão carcinogênica do CCU, porém a infecção por vírus adeno-associado (AAV) parece estar inversamente relacionada, o que pode refletir em um papel protetor no desenvolvimento do CCU induzido pelo HPV. Portanto, este estudo objetivou investigar o papel da infecção mista AAV-HPV e das variantes oncogênicas de HPV na progressão das lesões intraepiteliais de colo de útero e acompanhar a eliminação /persistência viral em relação à progressão / regressão das lesões cervicouterinas. Exames citológicos foram realizados em amostras de espécime cervical, coletadas em dois momentos, de mulheres atendidas no Hospital Universitário Cassiano Antonio Moraes HUCAM e seguiram para tratamento conforme preconizado. DNA foi extraído pelo kit comercial QIAamp® DNA Mini Kit, seguindo instruções do fabricante. DNA de AAV foi investigado por PCR e nPCR e, de HPV, por PCR e Captura Híbrida® (CH). Genotipagem de AAV e HPV foram realizadas por RFLP e RLB, respectivamente. Dos casos encaminhados ao ambulatório de colposcopia, 57,3% tiveram citologia normal, 23,1% lesões de baixo grau e 19,6% lesões de alto grau. Dos casos com citologia normal, 78% permaneceram normais, enquanto 22% progrediram à lesão; dos casos com lesão de baixo grau, 74% regrediram para citologia normal, enquanto 78,6% dos casos com lesão de alto grau apresentaram lesão de baixo grau ou citologia normal na segunda coleta. Foram positivas para HPV, 56% e 36,5% das amostras da primeira e segunda coletas, respectivamente. Foi observada boa correlação (kappa= 0,66) entre os testes de PCR e CH para detecção de HPV. Os HR-HPV foram detectados em mais de 90% das amostras de ambas as coletas, sendo os mais frequentes os HPV16, 58, 51, 52 e 53. Variante não-europeia esteve associada ao desenvolvimento de lesão cervical de alto grau, enquanto a presença de AAV foi inversamente relacionada à progressão da lesão cervical induzida por HPV.

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Gene therapy for Hemophilia A (HA) using the recombinant Adeno-associated virus (rAAV) offers an alternative to classic treatment, which consists of FVIII protein infusions. However, due to limitations associated with rAAV and the FVIII protein itself, the end result is a transgene expression below therapeutic limits. One approach to improving the therapeutic value of rAAV gene therapy for HA is to engineer a more active FVIII protein through genetic modifications. Preliminary testing revealed that canine FVIII Light Chain (kLC) enhances coagulation activity, and that it would be possible to improve FVIII activity through modifications of the light chain. Through the process of engineering, evaluation, and negative selection of kLC, a final construct was engineered. The hLC-K12 is a human Light Chain (hLC) construct containing 12 amino acid changes that work together to enhance coagulation activity. A comparison of the FVIII clotting activity to the amount of protein produced determined that hLC-K12 produced a 3.28 fold increase in specific activity over hLC in vitro. Similar in vitro results were observed when hLC-k12 was tested with the X5 heavy chain (X5HC), a heavy chain that has been genetically modified to enhance production. CD4KO/HA mice were injected with a rAAV vector carrying the hLC-K12 gene in conjugation with a rAAV vector carrying the X5HC gene. Replacing the hLC vector with the hLC-K12 vector produced an average 7.43 fold increase in FVIII clotting activity. An ELISA assay revealed no significant difference between productions of the heavy or light chains at any time point. By comparing the clotting activity to the amount of protein produced, it was determined that the increase in coagulation activity was due to an increase in specific activity. In fact, replacing the hLC vector with the hLC-K12 vector resulted in an average 5.8 fold increase in FVIII specific activity. The K12 modifications were evaluated using a single chain FVIII conformation. In vitro, the addition of the K12 mutations to the human heavy chain, hHCK12BDD, resulted in a 4.3 fold increase in clotting activity, but no increase in protein production. There was however, a 3.3 fold increase in specific activity of the protein. Adding the K12 mutations to the X5 heavy chain, X5K12BDD, in vitro, resulted in a 2.7 fold increase in clotting activity and a 1.42 fold increase in specific activity of the protein. Single chain rAAV vectors were packaged and delivered to CD4KO/HA mice. Compared to mice injected with hFVIIIBDD, the hHCK12BDD produced an average 4.6 fold increase in clotting activity. An ELISA revealed no significant difference in production between these two groups. However, mice injected with hHCK12BDD produced FVIII with an average of 4.13 fold increase in specific activity. Similarly, when compared to mice injected with X5FVIIIBDD, the X5K12BDD produced an average 2.14 fold increase in clotting activity. An ELISA assay demonstrated no significant increase in protein production between these two groups. However, when compared to X5BDD, mice injected with the X5K12BDD vector produced FVIII with an average 1.98 fold increase in specific activity. Results demonstrate that the K12 light chain modifications are able to enhance clotting activity of hFVIII both in vitro and in vivo, using either a dual chain or single chain delivery method. In order to determine the mechanism of enhancement, hFVIIIBDD and hHCK12BDD protein was partially purified and tested for activity. Results demonstrated that the hHCK12BDD protein produced a specific activity of 39,153.69 Units/mg, which is a 6.28 fold increase over hFVIIIBDD specific activity, which was 6,237.92 Units/mg. Measurement of conversion from FX to FXa revealed that the hHCK12BDD protein generated a higher amount of FXa at a quicker rate. In conclusion, these results provide evidence that the K12 modifications enhance specific activity through an increase in FXa generation. / Microbiology and Immunology

L’ataxie de Friedreich (AF) est une maladie mitochondriale caractérisée par une ataxie sensitive et spinocérébelleuse, une cardiomyopathie et du diabète, pour laquelle il n’existe pas de traitement. L’AF résulte de niveaux réduits de frataxine (FXN), une protéine mitochondriale impliquée dans la biosynthèse des centres Fe-S. La neurophysiopathologie précise de la maladie n’est pas identifiée et malgré d’intenses progrès ces dernières années, il n’existait pas de bon modèle pour développer des approches thérapeutiques visant à stopper ou réverser l’atteinte sensitive de l’AF. Nous avons donc généré un nouveau modèle murin qui récapitule l’ataxie sensitive et la neuropathie associée au déficit en FXN. Plusieurs mécanismes moléculaires affectés en absence de FXN dans les neurones proprioceptifs, primairement affectés dans l’AF, ont été identifiés. Nous avons également démontré l’efficacité d’une approche de thérapie génique, basée sur l’utilisation de vecteur adéno-associés (AAV) exprimant la FXN humaine, pour réverser la neuropathie, établissant la preuve de concept du potentiel d’une telle approche pour l’atteinte sensitive de l’AF. / Friedreich ataxia (FA) is a rare mitochondrial disease characterized by sensory and spinocerebellar ataxia, hypertrophic cardiomyopathy, and diabetes, for which there is no treatment. FA is caused by reduced levels of frataxin (FXN), an essential mitochondrial protein involved in the biosynthesis of Fe-S clusters. To date, FA precise neuropathophysiology is not identified and despite significant progresses in recent the years, there was no good model to develop therapeutic approaches in order to stop or reverse the sensory ataxia associated to the FA. Thus, we have generated a new neuronal mouse model that recapitulates the sensory ataxia and the neuropathy associated to FXN deficiency. Several molecular mechanisms dysregulated in the absence of FXN in the proprioceptive neurons, primarily affected in FA, were identified. Furthermore, we have demonstrated the efficacy of a gene therapy (GT) approach, based on the delivery of adeno-associated vectors (AAV) expressing the human FXN, to reverse the sensitive neuropathy, thus establishing the preclinical proof of concept for the potential of GT in treating FA sensitive neuropathy.

Les circuits neuronaux responsables du sommeil paradoxal (SP) et de l'atonie musculaire qui le caractéristique sont l'objet de nombreuses recherches expérimentales, notamment en raison de l'existence de plusieurs pathologies invalidantes associées. Cette thèse de Neurobiologie s'inscrit plus spécifiquement dans la description anatomique et fonctionnelle du réseau neuronal responsable de l'atonie musculaire et son potentiel dysfonctionnement dans les troubles comportementaux en SP (RBD, REM sleep Behavior Disorder). Pour ce faire, nous avons combiné plusieurs techniques faisant appel à la neuroanatomie fonctionnelle, au traçage rétrograde de voies nerveuses, à l'hybridation in situ à la polysomnographie et à l'inactivation irréversible de populations neuronales ciblées moléculairement à l'aide de virus adéno-associés contenant des short hairpin RNAs (AAV-shRNA) chez le rat libre de ses mouvements. Nous avons ainsi montré que, contrairement à l'hypothèse généralement admise, le noyau sublatérodorsal pontique (SLD) n'est pas le générateur du SP. En effet, l'inactivation neurochimique de ses neurones glutamatergiques ou sa lésion totale diminuent les quantités de SP sans le supprimer, indiquant que le SLD n'est pas suffisant pour la genèse du SP. En revanche, ces expériences démontrent son implication directe dans la mise en place de l'atonie musculaire lors du SP. En effet, la déconnexion neurochimique des neurones glutamatergiques du SLD provoque pendant le SP l'apparition intermittente de tonus musculaire accompagné de comportements moteurs anormaux. En parallèle, nos travaux de thèse ont permis d'apporter des données expérimentales nouvelles sur la localisation, au sein de la formation réticulée bulbaire ventrale et non dans la moelle épinière, des interneurones GABA/glycine responsables de l'hyperpolarisation des motoneurones somatiques pendant le SP. En effet, ces neurones réticulaires sont exclusivement recrutés pendant le SP et envoient des projections monosynaptiques inhibitrices vers les motoneurones somatiques lombaires. De plus, leur déconnexion neurochimique ciblée déclenche des comportements moteurs anormaux sous-tendus par le maintien d'un tonus musculaire irrégulier pendant le SP. L'analyse actimétrique de ces comportements moteurs oniriques induits expérimentalement montre qu'ils sont très semblables à ceux observés après l'inactivation du SLD et à ceux décrits chez les patients RBD. Les données rapportées dans cette thèse permettent de mieux comprendre les mécanismes neurobiologiques générant le SP et ceux contribuant au contrôle moteur pendant le SP. Par la même occasion, nos travaux ont permis de valider deux modèles rongeurs du RBD humain, ouvrant ainsi des perspectives expérimentales pour l'élaboration de traitements ciblés de cette pathologie affectant le SP / A growing number of studies investigate the neuronal network responsible for paradoxical (PS) (or REM) sleep genesis and muscle atonia specific of this sleep state. The aim of this thesis was to characterize at the anatomical and functional levels the populations of neurons involved in generating muscle atonia during PS and their potential failure in REM sleep Behavior Disorder (RBD). For this purpose, we combined a large panel of experimental techniques such as functional neuroanatomy, retrograde tract-tracing, in situ hybridization, polysomnography and irreversible inactivation of genetically-targeted neurons with short-hairpin RNAs introduced in viral adenovectors (AAV-shRNA) in freely moving rats. We thus demonstrated for the first time that, in contrast to the currently admitted hypothesis, the pontine sublaterodorsal nucleus (SLD) is not the PS generator, since genetic inactivation of its glutamatergic neurons or its whole lesion diminish the quantities of but do not eliminate PS. This indicates that the SLD is not sufficient for PS generation. In contrast, our experiments clearly show that the SLD is responsible for muscle atonia because the specific inactivation of its glutamatergic neurons induces an irregular muscle tone concomitant to atypical motor behaviors during PS. In addition, we achieved original data about the location within the ventral medullary reticular formation, and not at spinal levels as often believed, of the glycine/GABA interneurons managing the sustained hyperpolarization of somatic motoneurons during PS. We indeed observed that these medullary neurons are selectively recruited during PS and send monosynaptic inhibitory efferents to the lumbar somatic motoneurons. Furthermore, their genetic inactivation is followed by an increase of abnormal motor behaviors underpinned by a sustained, although irregular, muscle tone. The actimetric analysis of these oneiric experimentally induced behaviors reveals that they are very similar to those observed after SLD inactivation or those reported in RBD patients. Taken together, data harvested during this Thesis help us to better understand the complex neurobiological mechanisms generating PS or specifically contributing to the control of the motor system during PS. At the same time, we validated two rodent models closely mimicking human RBD and thus opening new research fields for the development of targeted treatments for this pathology affecting REM sleep

L'encodage du signal acoustique en impulsions nerveuses se réalise au niveau des synapses à ruban des cellules ciliées internes (CCI) de la cochlée. Une dépolarisation déclenche l'exocytose des vésicules synaptiques suite à l'activation des canaux calciques CaV1.3 et à l'action d'un senseur calcique particulier, l'otoferline, une grande protéine se composant d'un domaine transmembranaire en C-terminal et de six domaines C2 (A-F) pouvant lier le Ca2+ et les phospholipides. Afin de caractériser le rôle de ces différents domaines C2, nous avons utilisé des vecteurs viraux (AAV) permettant l'expression de formes raccourcies de l'otoferline (mini-Otof) in vivo dans les CCI de souris dépourvues d'otoferline (Otof -/-). Nous montrons que les mini-Otof contenant les domaines C2-EF, C2-DEF ou C2-ACEF sont suffisantes pour restaurer l'exocytose rapide des CCI Otof -/-, sans toutefois restaurer l'audition car le recrutement des vésicules synaptiques reste altéré. Nous révélons pour la première fois la présence d'une endocytose ultra-rapide (t < 20 ms) dynamine- et otoferline-dépendante, une fonction certainement essentielle à l'homéostasie membranaire des CCI. L'expression des mini-Otof C2-EF et C2-DEF a également permis de restaurer partiellement la composante rapide de l'inactivation du courant calcique des CCI, celle-ci étant absente chez les souris Otof -/-. Cette inactivation rapide est réalisée par les isoformes courtes Cav1.3S qui ont leur partie C-terminale régulatrice tronquée, contrairement aux isoformes longues Cav1.3L dépourvues d'inactivation. Afin de différencier les rôles spécifiques de ces isoformes dans le cycle des vésicules synaptiques, nous avons utilisé la technologie CRISPR-Cas9, nous permettant d'éditer spécifiquement la partie C-terminale régulatrice des canaux Cav1.3L. Nos résultats montrent que les souris CRISPR-Cav1.3L présentent une surdité sévère expliquée au niveau des CCI par un défaut de recrutement vésiculaire aux zones actives, alors que les Cav1.3S inaltérés contrôlent la fusion rapide des vésicules synaptiques. / The precise encoding of acoustic signals into nerve impulses is achieved at the ribbon synapses of inner hair cells (IHC) of the cochlea. Exocytosis of synaptic vesicles by IHC is triggered by voltage-activation of Cav1.3 calcium channels and the action of a specific calcium sensor, otoferlin, a large protein with a single C-terminal transmembrane domain and six C2 (A-F) domains which binds Ca2+ and interacts with phospholipids. In order to characterize the function of the various otoferlin C2 domains, we used viral vectors (AAV) allowing the expression of shortened forms of otoferlin (mini-Otof), in vivo, in IHC from mice lacking otoferlin (Otof -/-). We show that mini-Otof containing C2-EF, C2-DEF or C2-ACEF domains are sufficient to restore fast synaptic vesicle exocytosis in Otof -/- IHC, but without restoring hearing because vesicular replenishment remains impaired. For the first time, we also uncover an ultra-fast endocytosis (t < 20 ms) dynamin- and otoferlin-dependant, a function that is certainly essential for a fast regulation of IHC membrane homeostasis. Furthermore, the expression of the mini-Otof C2-EF and C2-DEF also partially restored the fast component of the Ca2+ current inactivation in Otof -/- IHC. This rapid inactivation is carried out by Cav1.3S short isoforms which have a truncated C-terminal regulatory domain, unlike Cav1.3L long isoforms which display no inactivation. To characterize the specific role of these Cav1.3 isoforms, we used CRISPR-Cas9 technology, allowing a specific removal of the C-terminal regulatory part of the Cav1.3L channels in IHC. Our results show that CRSIPR- Cav1.3L mice display severe deafness explained at the IHC level by a defect in vesicular replenishment of the active zones, while Cav1.3S are sufficient to ensure fast and transient exocytosis of docked synaptic vesicles.

Les cellules souches hématopoïétiques (CSH) assurent la génération de toutes les lignées sanguines. Leur différenciation en cellules T matures se déroule dans un microenvironnement spécialisé, le thymus, orchestrée par des interactions complexes entre cytokines, chimiokines et cellules stromales. Les mutations bloquant la différenciation des cellules T ont un impact sur l'architecture du thymus, soulignant l’importance des interactions entre cellules T en développement et cellules stromales thymiques.Les déficits immunitaires combinés sévères sont généralement traités, avec succès, par transplantation de CSH allogénique par voie intraveineuse. Cependant, des complications peuvent survenir notamment en cas de greffe non compatible. Pour pallier à cela, la thérapie génique a été développée mais son efficacité et son innocuité restent à améliorer. Dans ce but, notre groupe a développé une approche par correction génique des progéniteurs T directement in vivo, via un vecteur lentiviral. Bien qu’efficace, là encore, l’efficacité de traitement reste insuffisante voire extrêmement limitée chez les macaques.Lors de ma thèse, j'ai donc évalué le potentiel de différents sérotypes de vecteur viraux adéno-associés (AAV) pour la transduction des thymocytes. L'administration IT de plusieurs sérotypes de AAV2 engendre une transduction des thymocytes >10 fois plus élevée que celle des vecteurs lentiviraux. Le sérotype AAV2/8 induit la transduction des thymocytes la plus efficace et les cellules transduites représentent jusqu'à 1% des cellules T périphériques d’une souris immunocompétente. En utilisant des souris immunodéficientes ZAP-70-/- comme paradigme, j'ai découvert que l'injection IT de l’AAV2/8-ZAP-70 entraîne une transduction et différentiation lymphocytaire T rapide, associée à la génération d’une medulla thymique. En effet, des cellules épithéliales thymiques de la médulla (mTEC) exprimant le régulateur auto-immun AIRE sont détectées en <2 semaines. Bien que cette reconstitution soit transitoire, les mTECs AIRE+ diminuant 10 semaines post-injection, les cellules T périphériques corrigées persistent >40 semaines et présentent environ 1 copie du vecteur AAV/cellule. Ces cellules T effectrices peuvent sécréter des niveaux élevés de cytokines et un nombre important de cellules T régulatrices est également généré. Ainsi, une seule vague de thymopoïèse à partir de progéniteurs transduits par l’AAV-ZAP-70, permet une restauration, rapide et transitoire de l'architecture thymique mais, à long terme de cellules T périphériques fonctionnelles.Pour évaluer les diverses populations de TEC régissant le développement et la sélection des cellules T, j'ai collaboré avec les groupes de P Jay/J Abramson/I Amit pour établir une cartographie de novo du compartiment stromal thymique. Nos analyses ont mis en évidence quatre populations majeures de mTEC (I-IV) avec des fonctions distinctes. Notamment, les mTEC-IV constituent une population unique présentant des similarités moléculaires et morphologiques avec les cellules tuft intestinales. Comme nous avions précédemment identifié la sécrétion d'IL-25 par les cellules tufts comme un régulateur des interactions entre compartiment épithélial et hématopoïétique dans l'intestin, nous avons évalué ce potentiel dans le thymus. Ainsi, des souris déficientes en cellules tuft intestinales présentent également une déficience spécifique en mTEC-IV et une homéostasie perturbée de diverses populations exprimant l'IL-25R dans le thymus. Notre recherche a donc permis d'identifier une nouvelle population de TEC tuft avec un rôle critique dans la formation de la niche immunitaire du thymus.L’ensemble de mes résultats montrent le potentiel thérapeutique de stratégie intrathymique de thérapie génique pour des patients ayant besoin d’une reconstitution rapide en cellules T et fournissent de nouvelles perspectives sur les populations stromales thymique et leur rôle dans l’équilibre de la niche immunitaire. / Hematopoietic stem cells (HSC) ensure the generation of all blood lineages. Their differentiation to mature T lymphocytes occurs in the specialized microenvironment of the thymus, orchestrated by complex interactions between cytokines, chemokines, and stromal cells. Mutations resulting in a block in T cell differentiation impact on the architecture of the thymus, pointing to the critical crosstalk between developing T cells and thymic stromal components.Genetic severe combined immunodeficiencies (SCID) are generally treated by the intravenous transplantation of healthy allogeneic HSCs. Although this therapy is often successful, complications can occur, especially for patients receiving non-histocompatible HSC transplants. To circumvent these problems , significant efforts have gone into developing gene therapy strategies but adverse events indicate the necessity of exploring other avenues. Our group hypothesized that in situ gene correction of T lymphoid progenitors in the thymus itself may overcome some of the drawbacks of ex vivo gene therapy. While intrathymic (IT) lentiviral vector administration corrected immunodeficient thymocyte precursors in mice, thymus transduction was inefficient and efficacy in macaques was limited.During my PhD, I assessed the in vivo potential of adeno-associated vectors (AAV) to transduce thymocyte precursors. Intrathymic administration of several different scAAV2 serotypes resulted in a >10-fold higher transduction of thymocytes (3-5%) as compared to lentiviral vectors. scAAV2/8 promoted the highest level of gene transfer and strikingly, transduced cells represented up to 1% of peripheral T lymphocytes in immunocompetent mice. Using ZAP-70-/- immunodeficient mice as a paradigm, I found that IT injection of an AAV2/8-ZAP-70 vector resulted in a rapid transduction and T cell differentiation, correlating with a dramatic generation of the thymus medulla. Indeed, medullary thymic epithelial cells (mTEC) expressing the AIRE autoimmune regulator were detected within <2 weeks. While this reconstitution was transient––AIRE+ mTECs decreased by 10 weeks post gene transfer––gene-corrected peripheral T cells, harboring approximately 1 AAV genome/ cell, persisted for >40 weeks. Effector T cells had the potential to secrete high levels of cytokines and significant numbers of gene-corrected regulatory T cells were also generated. Thus, a single wave of thymopoiesis, from intrathymic AAV-ZAP-70-transduced progenitors, allows for a rapid but transient restoration of the thymic architecture and long-term peripheral T cell function.To better assess the diverse TEC populations that orchestrate T cell development and selection, I collaborated with the groups of P. Jay/J. Abramson/I. Amit to combine single cell analysis and in-vivo fate-mapping to de novo characterize the entire stromal compartment of the thymus. Our analyses highlighted four major medullary TEC (mTEC I-IV) populations with distinct lineage regulator function and specifically, we found that mTEC-IV constitutes a highly divergent TEC subset that bears strong molecular and morphological characteristics to intestinal tuft cells. As we previously identified tuft cell secretion of IL-25 as a regulator of the crosstalk between the epithelial and hematopoietic compartments in the gut, we assessed the potential immune-modulatory function of mTEC-IV. Notably, mice deficient in intestinal tuft cells exhibited a specific depletion of mTEC-IV and a perturbed homeostasis of various IL25-R-expressing populations in the thymus. Taken together, our data identify a new tuft TEC population critical for shaping the thymus immune niche.In conclusion, the data generated during my PhD advance the therapeutic potential of intrathymic-based vector strategies for the treatment of patients requiring a rapid T cell reconstitution and provide new insights into thymic stromal subsets that are critical for shaping the thymus immune niche.