Les microparticules (MPs) sont des vésicules dérivées de la membrane plasmique lors de la vésiculation par les cellules stimulées. Les MPs interviennent dans l'inflammation, les communications intercellulaires et la coagulation. Tout d'abord, nous avons standardisé une méthode pour caractériser et quantifier des MPs par cytométrie en flux dans le plasma.L'implication des MPE est suggérée dans le psoriasis notamment par le rôle central du TNF-a qui est un puissant inducteur de vésiculation. Nous avons comparé les valeurs de MPs chez des patients psoriasiques à celles de donneurs sains. Les MPE étaient plus élevées chez les patients notamment les MPs de petite taille. Les MPs diminuaient sous traitements anti-TNF-a.Les MPs agissent sur la progression tumorale des cancers. Les MPs tumorales ou des cellules de l'hôte peuvent modifier les propriétés invasives de la tumeur par des propriétés transférées. Les MPs peuvent aussi interagir avec les cellules du système immunitaire. Dans le mélanome, le risque de thrombose est accru. Or, la libération de MPs conduit à un état d'hypercoagulabilité. Les MPP et les MPE étaient augmentés dans chaque stade de la maladie par rapport à une population témoin. De plus, les MPs des patients atteints de mélanome possédaient des propriétés procoagulantes. L'étude des MPs en Dermatologie permet d'appréhender de nouveaux angles de la physiopathologie des maladies inflammatoires ou en carcinogenèse. Le dosage des MPs pourrait devenir un outil intéressant de monitoring des biothérapies dans le psoriasis. Dans le mélanome, des études complémentaires permettront de déterminer si les taux de MPs constituent un facteur pronostique intéressant / Microparticles (MPs) are vesicles derived from the plasma membrane during vesiculation by the stimulated cells. MPsare involved in inflammation, intercellular communications and coagulation. First, we standardised a method tocharacterise and quantify MPs in plasma by flow cytometry.The implication of endothelial microparticles (EMPs) is suggested in psoriasis, in particular by the central role of TNF-a which is a powerful inducer of vesiculation. We compared the values of MPs in psoriatic patients to the values inhealthy donors. EMPs were higher in the patients, especially MPs of small size. MPs were reduced under anti-TNF-atreatments.MPs have an action on the tumoral development of cancers. Tumoral MPs or the host's cells can modify the invasiveproperties of the tumour through transferred properties. MPs can also interact with the cells of the immune System. Inmelanoma, the risk of thrombosis is increased, but the release of MPs leads to a state of hypercoagulability. Plateletsmicroparticles (PMPs) and EMPs were increased at each stage of the disease compared to a control population. Inaddition, MPs of patients with melanoma had procoagulant properties.The study of MPs in Dermatology allows to apprehend new approaches of the physiopathology of inflammatorydiseases or in carcinogenesis. The dosage of MPs could become an interesting tool in the monitoring of biotherapies inpsoriasis. In melanoma, additional studies will show if MPs rates are an interesting prognostic factor.

Submitted by Biblioteca do Instituto Biomédico BIB (uffbib@gmail.com) on 2017-06-05T19:47:11Z No. of bitstreams: 1 Helena Naly Miguens Rocha.pdf: 1130470 bytes, checksum: 43146823dc28af52b34aa41dd863ff95 (MD5) / Made available in DSpace on 2017-06-05T19:47:11Z (GMT). No. of bitstreams: 1 Helena Naly Miguens Rocha.pdf: 1130470 bytes, checksum: 43146823dc28af52b34aa41dd863ff95 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Mecanismos de ativação e reparo endoteliais em resposta ao fluxo sanguíneo retrógrado (FSR) exacerbado ainda não foram completamente elucidados, nem em condições fisiológicas, nem na hipertensão arterial sistêmica (HAS). O objetivo deste estudo foi determinar os efeitos do FSR exacerbado sobre biomarcadores endoteliaisem indivíduos saudáveis e com HAS. Oito homens saudáveis (grupo CT; 36±3) e oito pacientes com HAS(grupo HAS;39±5) foram submetidos a manobra de indução de FSR em um dos braços, através da insuflação de dois manguitos, um no antebraço a 75mmHg e outro manguito próximo ao ombro a 40 mmHg, por 30 minutos. A avaliação do fluxo sanguíneo (ultrassom vascular) e a coleta de sangue foram realizadas no momento basal e no 30º minuto de manobra em ambos os braços (contralateral e ipsilateral). Ativação endotelial, micropartículas endoteliais (MPE) e células progenitoras endoteliais (CPE) foram mensuradas por citometria de fluxo. Nitrito foi mensurado por NOA Sievers. Em condições basais, fluxo sanguíneo médio, condutância vascular, taxa de cisalhamento média (p<0,01) e MPE (p=0,03) foram maiores no grupo HAS quando comparado ao grupo CT. Níveis basais de CPE estavam reduzidos no grupo HAS, permanecendo assim durante a manobra (p<0,01). Ambos os grupos apresentaram redução no fluxo sanguíneo médio e na condutância vascular (p≤0,01), bem como aumento na taxa de cisalhamento retrógrado (p<0,01) e no índice de cisalhamento oscilatório (p<0,01) durante a manobra. Somente o grupo HAS aumentou o número de MPE (p=0,02) e a ativação endotelial (p=0,04) durante a manobra. A razão MPE/CPE foi maior em ambos os momentos no grupo HAS (p<0,02). A resposta dos níveis séricos de nitrito a manobra foi menor no grupo HAS (p=0,03). Conclui-se que pacientes com HAS apresentam um quadro subclínico de disfunção endotelial com comprometimento no reparo vascular, o que foi agravado pela indução de FSR. / Endothelial activation and repair mechanism in response to increased retrograde blood flow (RBF) have not beenfully elucidated, neither in physiological conditions nor in hypertension. We aimed to determinethe effects of increased RBF on endothelial biomarkers in healthy individuals and hypertensive patients. Eight healthy subjects (CT group; 36±3) and eight hypertensive men (HT group; 39±5) underwent a maneuver to increase RBF, using two pneumatic cuffs: one in the forearm, inflated to 75 mmHg and one near the shoulder, inflated to 40 mmHg, for 30 minutes.Blood flow measures (ultrasound doppler) and blood samples were obtained at baseline and during the last minute of the maneuver from both arms (ipsilateral and contralateral). Endothelial activation, endothelial microparticle (EMP) and endothelial progenitor cell (EPC) were measured by flow cytometry. Nitrite was measured through NOA Sievers.At baseline, mean blood flow, vascular conductance, mean shear rate (p<0.01) and EMP (p=0.03) were higher in HT group than CT group. Baseline EPCs levels were reduced in HT group, which was sustained during the maneuver (p<0.01). Both groups presented decreased mean blood flow and vascular conductance (p<0.01), along with increased retrograde shear rateand oscillatory shear index (p<0.01), during the maneuver. Only the HT group showed increased EMP (p=0.02) and endothelial activation levels (p=0.04). EMP/EPC was higher in HT group in both moments (p<0.02).Nitrite levels in response to the maneuver were lower in HT group (p=0.03).Hypertensive patients present a subclinical endothelial dysfunction along with impaired endothelial repair, which was worsened by the RBF induction.