Les glioblastomes (GBM) sont des tumeurs astrocytaires au pronostic défavorable. L’échec des thérapies actuelles (chimio et radiothérapies) est principalement lié à la résistance des cellules souches cancéreuses (CSCs). Ces cellules ont besoin de communiquer en permanence avec leur microenvironnement pour leur survie et pour maintenir une niche favorable à leur développement. Le transfert de matériel entre les CSC, les cellules tumorales et le microenvironnement contribue à l’échappement thérapeutique. Des travaux récents révèlent l’importance des récepteurs aux neurotrophines TrkB et TrkC dans la survie et la croissance des CSC de GBM. Nos travaux préliminaires dans le cancer bronchique démontrent que les récepteurs aux neurotrophines sont transférés aux cellules du microenvironnement via les exosomes afin de les contrôler. Cependant, le mécanisme de diffusion de récepteurs oncogéniques à partir de CSC n’a jamais été étudié. Notre objectif principal était donc de déterminer l’implication des récepteurs des neurotrophines dans le transfert du phénotype agressif des CSC vers les cellules du microenvironnement afin de favoriser la résistance thérapeutique du glioblastome. Nos résultats ont permis d’établir un lien entre le stade de différenciation des cellules tumorales, l’expression des neurotrophines et leur interaction avec le microenvironnement tumoral via les exosomes. Le transfert de TrkB au sein des exosomes joue un rôle clé dans la progression tumorale du GBM et dans l’agressivité cellulaire. Néanmoins, le transfert des récepteurs aux neurotrophines via les exosomes pourrait également être impliqué dans les mécanismes de radiorésistance. Des études menées sur des cellules de GBM humain irradiées et traitées par des exosomes démontrent l’implication de ces derniers dans l’échappement thérapeutique. Parmi les cellules du microenvironnement ciblées par les exosomes, les CSM sont celles qui ont été les moins étudiées bien qu’elles possèdent un tropisme spécifique pour le GBM. Nos travaux démontrent que les exosomes de GBM modifient le phénotype des CSM et augmentent leurs capacités prolifératives et migratoires. La fonction exacte du transfert des récepteurs des neurotrophines devra être analysée dans ces différents modèles afin de préciser son importance dans la physiopathologie du glioblastome et sa progression. L’expression des récepteurs aux neurotrophines dans ces exosomes permet d’envisager leur utilisation en tant que biomarqueurs diagnostiques et/ou pronostiques dans le GBM. Mots clés : Glioblastomes, cellules souches cancéreuses, neurotrophines, TrkB, radiothérapie, cellules souches mésenchymateuses, exosomes. / Glioblastoma are tumors derived from astrocytes with a dark prognosis. Current therapies fail to inhibit relapses due to radioresistant properties of cancer stem cells (CSC). Communication between CSC and their microenvironment is required for maintain “stem cells niche” and cell survival . The transfer of materials between CSC, tumor cells and microenvironment contributes to therapeutic resistance. In glioma, recent studies reveal the major role of TrkB and TrkC in survival of CSC. Our previous work, in lung cancer, have shown that neurotrophin receptors exhibits a control on microenvironment cells and angiogenesis through exosome transfer. However, similar mechanism of oncogenic receptor transfer from CSC has never been studied. Our main goal was to determine the involvement of neurotrophin receptors in the transfer of biological aggressiveness to microenvironment cells in order to promote therapeutic resistance in glioblastoma. Our findings suggest a relationship between cell differentiation status, expression of neurotrophin receptors and their interaction with the microenvironment through exosomes. TrkB-containing exosomes play a key role in the control of glioblastoma progression and cell aggressiveness. Mechanisms of radioresistance might also be dependent of the transfer of neurotrophin receptors through exosomes. Indeed, our results on irradiated human GBM cells and treated by exosomes demonstrate the involvement of exosome in radioresistance mechanisms. Although mesenchymal stem cells (MSCs) are considered as stromal components of glioblastoma, their communication with CSC, particularly through exosomes, remain largely undefined. Our results show that GBM-derived exosomes modify the phenotype of MSCs and increase their proliferative and migratory abilities. The putative function of neurotrophin receptors transfer should be analyzed in these models to determine their prime role in glioblastoma pathogenesis and progression. This finding suggest that the neurotrophin receptor expression in exosomes could be used as diagnostis and prognosis biomarkers of GBM.

Grâce à la production de nanoparticules lipidiques, les SELN (Synthetic Exosomes-Like Nanoparticles), mimant la composition des exosomes produits par les cellules tumorales pancréatiques humaines SOJ-6, nous avons démontré que les effets apoptotiques des exosomes naturels étaient dus aux lipides. En effet, nous avons montré que les SELN dont le rapport rafts/phospholipides est le plus élevé, interagissent avec les cellules SOJ-6 au niveau des rafts et perturbent la voie Notch. Cela conduit à la diminution de l'expression du facteur de survie Hes-1, qui est accentuée par la perte d'activité du complexe PTEN-GSK-3β. Ces dérégulations induisent l'apoptose dépendante de la mitochondrie des cellules SOJ-6, caractérisée par l'augmentation du ratio Bax/Bcl-2, l'activation de la caspase 9 et la dégradation de l'ADN. En revanche, les cellules MiaPaCa-2 résistent aux SELN, ce qui s'explique par leur caractère indifférencié. Ainsi la surexpression de marqueurs de cellules souches tels que l'ALDH et CXCR4 leur confèrent une grande résistance. Elles sont toutefois sensibles à la cyclopamine un inhibiteur de la voie Hedgehog, dont les effets sont atténués si les cellules MiaPaCa-2 sont préincubées avec les SELN, prouvant que ces cellules mettent en place des voies de survie leur permettant d'échapper à l'apoptose. Nos investigations ont montré que dans les cellules MiaPaCa-2, sous l'effet des SELN, l'activation de la voie canonique NF-кB permet d'induire la transcription du gène codant SDF-1α, seul ligand connu du récepteur CXCR4. Le facteur produit et sécrété active de manière auto et paracrine une voie de survie Akt-dépendante. / It has been previously reported that exosomes released by the human pancreatic tumoral cell line SOJ-6 could induce their own apoptosis. Thanks to the production of lipid nanoparticles, SELN (Synthetic Exosomes-Like Nanoparticles) mimicking the lipid composition of natural exosomes, we have shown that lipids were responsible for the observed effects. Indeed, we showed that SELN with the higher ratio rafts/phospholipids could interact with SOJ-6 cells at the level of the rafts to perturb the Notch pathway, preferentially localized in these lipid microdomains. This induces a decreased expression of the main target of this pathway, the survival factor Hes-1. This decrease is intensified by the activation of the complex PTEN-GSK-3β. These deregulations drive cells towards the mitochondria-dependent apoptosis as shown by the increase of the ratio Bax/Bcl-2, the caspase 9 activity and the DNA fragmentation. Whereas MiaPaCa-2 cells are resistant to SELN, which is explained by their stem-like cell phenotype, contrarily to the well-differentiated SOJ-6 cell line. Although the over-expression of some stem cell markers, such as ALDH and CXCR4 is responsible for their resistance, they remain sensitive to the cyclopamine, a Hedgehog inhibitor. We found out that MiaPaCa-2 cells pre-incubation with SELN could protect them from the inhibitory effect of the cyclopamine, meaning that upon SELN incubation, a survival pathway is triggered in MiaPaCa-2 cells. So we showed that, upon SELN incubation, the canonical NF-кB pathway is activated in MiaPaCa-2 cells to promote SDF-1α expression. Once released, SDF-1α interacts with its receptor CXCR4 to activate an Akt-dependent survival pathway.

Chez les espèces aviaires, le stockage des spermatozoïdes s’étend sur plusieurs semaines principalement au niveau du réservoir de la jonction utéro-vaginale, contenant les tubules de stockage des spermatozoïdes (SST). Les mécanismes impliqués dans ce processus restent indéterminés. L’effet de l’insémination artificielle (IA) a été évalué sur le protéome du fluide utérin (FU), des protéines cibles et des glycanes dans les SST, provenant de poules possédant une longue (F+) ou courte (F-) durée de stockage. La longue durée de stockage est associée à une abondance relative dans le FU après IA des protéines exosomales (ANXA4, ANXA5), des protéoglycanes (TSKU), des protéines liant les protéoglycanes (HAPLN3, FN1, VTN), des transporteurs de lipides (VTG1, VTG2, APOA1, APOA4, APOH), et des protéines matricielles de la coquille (OCX32). Au contraire, la faible capacité de stockage est associée à la régulation après IA des protéines immunitaires (PIGR, immunoglobulines) ou pro-inflammatoire (LTA4H), des protéases (XPNPEP1), des chaperones (HSPA8), des mucines (MUC5AC, MUC5B), et de l’ovalbumine (OVALY). Au niveau des SST, les protéines matricielles de la coquille (OC-116, OCX36, OC-17) ont été identifiées dans l’épithélium et la lumière. La longue durée de stockage est associée à la sécrétion luminale de résidus Glc/GlcNAc, à la mobilisation apicale de protéines exosomales (ANXA4), et la non-activation des voies métaboliques impliquant les protéines PIGR, HSPA8, et ANXA5 dans les SST. En conclusion, la composition protéique du FU et des SST requièrent des régulations spécifiques après IA certainement pour garantir le stockage des spermatozoïdes. / In avian species, the sperm storage mainly takes place in uterovaginal sperm storage tubules (SST) during several weeks. Mechanisms implied in this process are not fully understood. The effect of artificial insemination (AI) has been evaluated on the uterine fluid (UF) proteomic composition, and on SST candidate proteins, from hens exhibiting long (F+) or short (F-) sperm storage duration. Long sperm storage duration was associated with the relative abundance in UF after AI of proteoglycans (TSKU), proteoglycan binding proteins (HAPLN3, FN1, VTN), lipid transporters (VTG1, VTG2, APOA1, APOA4, APOH), and eggshell matrix proteins (OCX32). In contrast, poor sperm storage ability was associated with the regulation of immune factors (PIGR, immunoglobulins), pro-inflammatory factors (LTA4H), proteases (XPNPEP1), chaperone (HSPA8), mucins (MUC5AC, MUC5B), and ovalbumin related protein Y (OVALY). At the level of SST, eggshell matrix proteins (OC-116, OCX36, OC-17) were identified in SST cells and lumen. Long sperm storage duration was associated in SST with the luminal secretion of Glc/GlcNAc residues, ANXA4 apical mobilization, and non-activation of metabolic pathway implying PIGR, HSPA8, and ANXA5. In conclusion, the proteomic composition of UF and SST require specific regulation after insemination, most probably to guarantee the success of sperm storage process.

Les vésicules extracellulaires (VE), incluant exosomes et microparticules (MP), vecteurs d’information biologique, peuvent moduler la fonction de cellules cibles. Une élévation du taux de VE circulantes est observée dans les pathologies cardiovasculaires dont l’obésité est l’un des facteurs de risque majeur. Cependant, il existe peu de données concernant la production de VE adipocytaires et leur capacité à moduler le métabolisme des adipocytes. Tout d’abord, nous avons caractérisé de manière morphologique et biochimique les MP et les exosomes adipocytaires. Nous montrons une production accrue de ces VE dans un contexte d’obésité murine. L’analyse protéomique des VE adipocytaires révèle un enrichissement spécifique des MP et des exosomes en protéines clé du métabolisme énergétique et de l’inflammation, respectivement. Dans une seconde partie, nous avons étudié l’effet de MP lymphocytaires portant le morphogène Hedgehog (MPHh+) sur la différenciation adipocytaire. A l’instar d’une activation classique de la voie de signalisation Hh, les MPHh+ inhibent l’adipogenèse. Bien que dépendant du récepteur Smoothened (Smo), cet effet inhibiteur est indépendant des facteurs de transcription Gli. Nous montrons que les MPHh+ activent un axe anti-adipogénique Smo/Lkb1/Ampk pouvant être stimulé par un nouvel agoniste de Smo, le GSA-10. Nos résultats démontrent, d’une part, la capacité des adipocytes à sécréter des VE, et d’autre part, le potentiel fonctionnel des MPHh+ à inhiber l’adipogenèse par une voie de signalisation Hhnon-canonique. Les VE pourraient contribuer aux dysfonctions métaboliques associées à l’obésité en véhiculant des messages métaboliques à l’échelle de l’organisme. / Extracellular vesicles (EV), including microparticles (MP) and exosomes, are able to modulate target cell function through exchange or transfer of biological material. Although EV are present in the blood of healthy individuals, an elevated quantity of circulating EV is associated with cardiovascular diseases, which obesity is a major cardiovascular risk factor. Nevertheless, few studies have reported the ability of adipocytes to release EV and their implication in adipose tissue metabolism. First of all, we could determine morphological and biochemical features of adipocyte-derived exosomes and MP through a combination of methods. We were able to demonstrate an increase in adipocyte EV production in a murine model of obesity. Proteomic analysis of adipocyte EV further revealed a specific enrichment of proteins crucial for glucose and lipid metabolism and related to inflammation in MP and exosomes respectively. We then evaluated the ability of lymphocytes-derived MP harboring the Sonic Hedgehog morphogen to control adipocyte differentiation. Activation of the Hedgehog canonical pathway inhibited adipogenesis, as did MPHh+. Surprisingly, although Smo dependent, inhibitory potential of such MP did not involve the Gli transcription factors. We show that MPHh+ inhibit adipocyte differentiation through a Smo/Lkb1/Ampk axis as does a new agonist of Smo, GSA-10. Our results demonstrate, on one hand, the ability of adipocyte to release EV and on the other hand, the capacity of MPHh+ to control adipogenesis through a non-canonical Hh signaling pathway. In conclusion, EV might contribute to obesity related metabolic dysfunctions through systemic regulation of metabolic pathways.

Membrane-bound vesicle secretion provides a novel intercellular communication mechanism, whose roles and regulation remain poorly characterised, particularly in vivo. I have identified two classes of lipid-containing, vesicle-like structures secreted into seminal fluid by epithelial cells of the Drosophila male accessory gland (AG). Exosomes, one class of membrane-bound vesicle formed inside late endosomal multivesicular bodies, are specifically secreted by secondary cells (SCs). The unusual cell biology of SCs allowed me to develop a powerful new high resolution in vivo system to characterise the mechanisms underlying intracellular membrane trafficking events underlying exosome biogenesis using real-time live imaging. I characterise how specific ESCRTs (endosomal sorting complexes required for transport) control SC exosome biogenesis, and identify a novel role for BMP signalling in regulating endolysosomal trafficking events necessary for exosome secretion. I also identify roles for epidermal growth factor receptor (EGFR) and phosphatidylinositide 3-kinase (PI3K) signalling in exosome biogenesis. Importantly, SC exosomes are transferred to females during mating. Here, they fuse with sperm, mirroring in vitro interactions between human prostate exosomes and sperm, and interact with the female reproductive tract epithelium. Blocking SC exosome production specifically suppresses post-mating effects on female receptivity to remating, demonstrating that exosomes have an important reproductive signalling function in vivo, directly or indirectly reprogramming female cells. Finally, I show that main cells, the major epithelial AG cell type, shed lipid-containing microvesicle-like structures from their apical surface. Remarkably, these vesicles carry the seminal peptide, sex peptide, into females during mating and also contribute to the anterior mating plug. In summary, my data reveal previously unsuspected roles for exosomes and microvesicles in Drosophila reproduction that may be evolutionarily conserved. Since these vesicles mediate physiological processes previously thought to involve soluble peptides, my work suggests that current models explaining male reprogramming of female behaviours in flies and higher organisms need substantial revision.

Tau est une protéine associée aux microtubules enrichie dans l’axone. Dans la maladie d’Alzheimer, Tau devient anormalement hyperphosphorylée, s’accumule dans le compartiment somato-dendritique et s’agrège pour former des enchevêtrements neurofibrillaires (NFTs). Ces NFTs se propagent dans le cerveau dans un ordre bien précis. Ils apparaissent d’abord dans le cortex transenthorinal pour ensuite se propager là où ces neurones projettent, c’est-à-dire au cortex entorhinal. Les NFTs s’étendent ensuite à l’hippocampe puis à différentes régions du cortex et néocortex. De plus, des études récentes ont démontré que la protéine Tau peut être sécrétée par des lignées neuronales et que lorsqu’on injecte des agrégats de Tau dans un cerveau de souris, ceux-ci peuvent pénétrer dans les neurones et induire la pathologie de Tau dans le cerveau. Ces observations ont mené à l’hypothèse que la protéine Tau pathologique pourrait être sécrétée par les neurones, pour ensuite être endocytée par les cellules avoisinantes et ainsi propager la maladie. L’objectif de la présente étude était donc de prouver la sécrétion de la protéine Tau par les neurones et d’identifier par quelle voie elle est secrétée. Nos résultats ont permis de démontrer que la protéine Tau est sécrétée par des neurones corticaux de souris de type sauvage ainsi que dans un modèle de surexpression dans des cellules HeLa et PC12. Nos résultats indiquent que la sécrétion de Tau se ferait par les autophagosomes. Finalement, nous avons démontré que la protéine Tau sécrétée est déphosphorylée et clivée par rapport à la protéine Tau intracellulaire non sécrétée. / Tau, a microtubule-associated protein, is enriched in the axon. In Alzheimer’s disease, Tau becomes hyperphosphorylated, redistributes to the somato-dendritic compartment and forms aggregates called neurofibrillary tangles (NFTs). The NFTs propagates in a predictable manner in particular neuronal networks. Indeed, they appear in the trans-entorhinal region and then propagate to the entorhinal cortex where the trans-entorhinal cortex projects. Then, the NFTs propagate to the hippocampus and to different regions of the cortex and neocortex. Recent studies have reported that Tau can be secreted by neuronal cell lines. Besides, when aggregates of Tau protein were injected in mouse brain, they could enter neurons and induced Tau pathology. Based on those observations, it was speculated that Tau could be secreted by neurons and then captured by neighbouring cells to propagate Tau pathology in the brain. The goal of the present study was to prove that Tau can be secreted by neurons and to find the secretory pathway involved in Tau secretion. Moreover, the phosphorylation state of Tau protein was examined and compared to intracellular non-secreted Tau. Our results showed that Tau is secreted by cortical neurons isolated from wild-type mice and by HeLa and PC12 cells overexpressing human Tau. Our results also indicated that autophagosomes would be involved in Tau secretion. Finally, we found that secreted Tau was dephosphorylated and cleaved compared to the non-secreted intracellular Tau.

ADAM10 is a zinc-dependent metalloprotease. ADAM10 has emerged as a key regulator of cellular processes by cleaving and shedding extracellular domains of multiple transmembrane receptors and ligands. In this study, we examined the role of ADAM10 in the immune system. Here, we show that knocking out ADAM10 on the mature B2 cell causes a defect in the development of secondary lymphoid architecture that becomes more severe post-immunization. We also show that overexpression of ADAM10 leads to a defect in hematopoiesis, which eliminates B2 lymphocyte development. This defect additionally induces accumulation of myeloid derived suppressor cells, MDSCs. ADAM10Tg MDSCs function synonymous to tumor MDSCs. Of the two subpopulations of MDSCs, granulocytic MDSCs increase parasitic clearance in a model of N. brasiliensis. Monocytic MDSCs are more immunosuppressive in regards to tumor. Both subpopulations are dependent on the presence of mast cells for activity. It is thought that this relationship is mediated through histamine and IL-13. During N. brasiliensis infection, ADAM10Tg mice, lacking B2 B cells but having intact B1 B cells, makes increased IgE over WT mice. This production of IgE is thought to be produced by the B1 cells. Of the two types of B1 cells, B1a cells make the majority of the IgE. This IgE production is enhanced by MDSC accumulation and can be induced by MDSC adoptive transfer in a parasite-free mouse. Lastly, ADAM10 is the key sheddase for CD23 on B2 cells. When IgE is bound to its antigen to form an immune complex, IC, it binds CD23 and is internalized. After CD23 bound to IgE ICs is internalized, it is sorted into bexosomes. These bexosomes are transferred to dendritic cells which are responsible for presenting to T cells and inducing an increased antigen-specific immune response. Overall, ADAM10 is important for many aspects of the immune response.

Exosomen aus Zellen nehmen eine immer größere Rolle in aktuellen Erkenntnissen zu Tumorwachstum und Metastasierung ein. Die Funktionen dieser circa 40-100 nm großen, aktiv sezernierten Vesikel sind bisher noch weitesgehend ungeklärt. Für die Untersuchung von Exosomen sind optimierte und schonende Isolierungsmethoden notwendig. Zur Zeit gibt es jedoch weder eine standardisierte Methode zur routinemäßigen Isolation von Exosomen noch zur Isolation von funktionell intakten Exosomen für die anschließende Funktionsanalyse. Ziel dieser Arbeit war es, eine vereinfachte, größenbasierte und standardisierbare Methode zur Isolation von funktionell intakten Exosomen zu entwickeln und die isolierten Exosomen qualitativ und quantitativ zu charakterisieren. Die Ergebnisse dieser Arbeit konnten in einer internationalen Fachzeitschrift publiziert werden. Die Publikation liegt dieser Arbeit bei (Heinemann et al. 2014).

Infants born prematurely are a vulnerable population with diverse nutritional needs to battle their increased risk of gastrointestinal (GI) diseases. Human milk is considered the 'gold standard' of infant nutrition. Human milk not only provides nutrition for newborn growth, but contains bioactive components which contribute to GI maturation, immune protection and neurological development. Among these bioactive components are extracellular vesicles known as exosomes. Exosomes are double-lipid membrane vesicles containing mRNA, microRNA and proteins, secreted by cells as a form of cell-to-cell communication. Human milk exosomes contain immune-related microRNA and proteins that withstand in vitro simulated human digestion, suggesting that signals are being delivered to the cells residing in the GI tract of a newborn. In premature birth, disruption of GI tract maturation predisposes the infant to increased susceptibility of GI inflammatory diseases. To prevent inflammation, immune tolerance in the GI tract of premature infants should be promoted and I hypothesized that exosomes differ between preterm and term milk, and may contribute to the anti-inflammatory effects of human milk. Human milk exosomes from mothers who gave birth to term or preterm infants were characterized based on size, surface protein markers and total protein. Preterm milk exosomes contained a more diverse protein profile. The effects of milk exosomes on intestinal epithelial cells were observed in an in vitro model using Caco-2/15 cells. Milk exosomes were able to attenuate the inflammatory response induced by heat-killed bacteria as measured by the transcription of pro-inflammatory cytokines.

Duas patologias principais estão associadas ao HTLV-1: a leucemia/linfoma de células T do adulto (ATLL) e a mielopatia associada ao HTLV-1/paraparesia espástica tropical (HAM/TSP). O mecanismo pelo qual ocorre o desenvolvimento destas doenças em apenas 1 a 5% dos indivíduos infectados é desconhecido. Sabe-se que diversos fatores estão associados ao desenvolvimento destas patologias, como carga proviral, características celulares, genéticas e imunológicas do hospedeiro. No entanto, tais mecanismos não foram totalmente elucidados e novas abordagens de estudos são necessárias para a compreensão da patogênese viral. Nesse sentido, vários estudos relatam o papel dos exossomos no desenvolvimento de infecções virais como HIV, EBV e HCV através do transporte de componentes incluindo proteínas, RNAm e miRNA. A possibilidade da transferência do conteúdo viral por essas vesículas para células não infectadas na ausência de vírus é um mecanismo intrigante. Dessa forma, esse trabalho teve como objetivo isolar os exossomos diretamente do soro de indivíduos infectados pelo HTLV-1 e comparar o conteúdo dessas vesículas quanto à expressão dos genes virais tax e HBZ entre os grupos assintomático e sintomático. Para tanto, os exossomos foram isolados por precipitação polimérica (Exoquick(TM)) e caracterizados por Western Blot (expressão dos marcadores CD9, CD81, Alix e citocromo c) e Análise de Rastreamento de Nanopartículas (tamanho e concentração). Além disso, o conteúdo dos exossomos foi analisado por PCR em tempo real para quantificação dos genes virais regulatórios tax e HBZ. Por fim, no intuito de estabelecer o papel dos exossomos como biomarcadores para o desenvolvimento da HAM/TSP, os níveis de expressão destes genes foram associados à carga proviral do HTLV-1. Os transcritos de RNAm de tax e HBZ foram detectados apenas em exossomos isolados do soro dos indivíduos sintomáticos, com ausência nos assintomáticos. Além disso, a expressão de tax e HBZ nos exossomos dos indivíduos infectados pelo HTLV-1 foi correlacionada positivamente com a CPV. Dessa forma, os resultados sugerem que os exossomos podem desempenhar importante papel na patogênese da mielopatia, através do transporte de genes virais de uma célula infectada para não-infectada. No entanto, mais estudos que relacionam o papel dos exossomos na infecção pelo HTLV-1 são necessários. / Two major pathologies has been associated with HTLV-1 infection: adult T- cell leukemia/lymphoma (ATLL) and HTLV-1 associated myelopathy/ tropical spastic paraparesis (HAM / TSP). The mechanism which is responsible for the appearance of these diseases in only 1 to 5% of the infected individuals is unknown. Is known that several factors has been related to the development of these diseases, such as proviral load and cellular, genetic and immunological characteristics of the host. However, these mechanisms have not been fully elucidated and new approaches are necessary to understand the viral pathogenesis. Thus, several studies have reported the involvement of exosomes in the development of the HIV, HCV, and EBV viral infections carrying components including proteins, mRNA and miRNA. The possibility of transfer of viral content via these vesicles to uninfected cells in the absence of virus is an intriguing mechanism. Therefore, this proposal aimed to isolate exosomes from serum of HTLV-1 infected patients and compare the content of these vesicles regarding viral gene expression of tax and HBZ between asymptomatic and symptomatic group. For this, the exosomes were isolated by polymeric precipitation (Exoquick(TM)) and characterized by Western Blot (expression of markers CD9, CD81, and Alix) and Nanoparticle tracking Analysis (size and concentration). Furthermore, the exosomes content were analyzed by real-time PCR for the quantification of tax and HBZ regulatory viral genes. Finally, to establish the role of exosomes like biomarkers to HAM/TSP development, levels of these genes were associated with proviral load of HTLV-1. Viral mRNA transcripts including tax and HBZ were found only in exosomes isolated from serum of symptomatic individuals and absence in assymptomatic. Furthermore, tax and HBZ expression in exosomes from HTLV-1 infected individuals were positive correlated with proviral load. Thus, the results suggests that exosomes can able to develop important role in myelopathy pathogenesis carrying viral genes of infected cell to uninfected cell. However, more studies that relate the role of exosomes in HTLV-1 are needed