Diagnosis of diabetes mellitus, presence of hyperglycemia, and/or insulin resistance confer cardiovascular risk, particularly for diastolic dysfunction. Diabetes is associated with elevated myocardial norepinephrine (NE) content, enhanced sympathetic nervous system (SNS) activity, altered resting heart rate, and depressed heart rate variability. Positron emission tomography (PET) using the NE analogue [11C]meta-hydroxyephedrine ([11C]HED) provides an index of myocardial sympathetic neuronal integrity at the NE reuptake transporter (NET). The hypothesis of this project is that (i) hyperglycemia imparts heightened sympathetic tone and NE release, leading to abnormal sympathetic neuronal function in the hearts of diabetic rats, and (ii) these abnormalities may be reversed or prevented by treatments to normalize glycemia. Sprague Dawley rats were rendered insulin resistant by high fat feeding and diabetic by a single dose of streptozotocin (STZ). Diabetic rats were treated for 8 weeks with insulin, metformin or rosiglitazone, starting from either 1 week (prevention) or 8 weeks (reversal) after STZ administration. Sympathetic neuronal integrity was evaluated longitudinally by [11C]HED PET. Echocardiography measures of systolic and diastolic function were completed at serial timepoints. Plasma NE levels were evaluated serially and expression of NET and β-adrenoceptors were tested at the terminal endpoints. Diabetic rats exhibited a 52-57% reduction of [11C]HED standardized uptake value (SUV) at 8 weeks after STZ, with a parallel 2.5-fold elevation of plasma NE and a 17-20% reduction in cardiac NET expression. These findings were confirmed by ex vivo biodistribution studies. Transmitral pulse wave Doppler echocardiography established an extension of mitral valve deceleration time and elevated early to atrial velocity ratio, suggesting diastolic dysfunction. Subsequent treatment with insulin but not metformin restored glycemia, reduced plasma NE by 50%, normalized NET expression, and recovered [11C]HED SUV towards non-diabetic age-matched control. Diastolic dysfunction in these rats persisted. By contrast, early treatment with insulin, metformin, or rosiglitazone delayed the progression of diastolic dysfunction, but had no effect on elevated NE and reduced [11C]HED SUV in diabetic rats, potentially owing to a latent decrease in blood glucose. In conclusion, diabetes is associated with heightened circulating and tissue NE levels which can be effectively reversed by lowering glycemia with insulin. Noninvasive interrogation of sympathetic neuronal integrity using [11C]HED PET may have added value in the stratification of cardiovascular risk among diabetic patients and in determining the myocardial effects of glycemic therapy.

In subclinical hypothyroidism (SH), high levels of circulating thyroid stimulating hormone (TSH) maintain normal thyroid hormone levels, despite mild thyroid failure. SH is associated with cardiovascular disease and insulin resistance, although the underlying pathophysiology is not fully understood. We hypothesized that TSH may inhibit insulin action in adipocytes. To investigate this relationship, we studied primary human differentiated adipocytes. Abdominal subcutaneous adipose tissue samples were obtained (approved by OHSN-REB) from 16 weight-stable patients undergoing elective abdominal surgery. We stimulated adipocytes differentiated from stromal preadipocytes with 5 mU/ml TSH and/or 100 nM insulin, and assessed acute insulin signaling, lipogenesis and glucose uptake. Immunoblot analysis revealed that TSH suppressed insulin-stimulated Akt phosphorylation by 45% (n=5; p = 0.01). When adipocytes were pre-incubated with conventional protein kinase C (cPKC) inhibitor Gö6976, TSH inhibition was blocked. Our data indicate that TSH inhibits insulin-stimulated lipogenesis (up to 37%), but depends on BMI. Insulin-stimulated glucose uptake was enhanced by 36% and also correlated with BMI. This data suggests that TSH can modulate adipocyte insulin signaling.

Haemophilus ducreyi is a gram-negative and heme-dependent bactreia. H. ducreyi is the responsible of causing chancroid, a sexually transmitted infection forming genital ulcers. Infection with H. ducreyi is associated with an increased risk of acquiring HIV-1 as well as increasing the risk of the HIV-1 transmission. Heme acquisition in H. ducreyi occur through a receptor mediated process in which it start with binding of hemoglobin and heme to their cognate outer membrane receptors, HgbA and TdhA, respectively. The receptors are energized by the TonB complex. Following that the deposition of heme into the periplasmic area is unclear. Profiling of the periplasmic proteome of the H. ducreyi resulted in the identification of a periplasmic- binding protein that highly expressed in heme limitation conditions, and it has been called hHbp. This protein is encoded by a gene resides in a locus of four genes displaying genetic features of an ABC transporter. The gene cluster is organized as an operon comprising an internal membrane protein (IntPro), a sulphate reductase gamma subunit (dsvC), a heme dependant periplasmic bind-ing protein (hHBP), and an ATPase. The purified periplasmic binding protein, hHbp, bind heme in a dose-dependent and saturable manner. Moreover, the binding between heme and hHbp was specifically competitively inhibited by heme. The proposal planned to cre-ate an isogenic hhbp mutant by insertional inactivation using a kanamycin cassette, to genotypically and phenotypically characterize the mutant and thereby to confirm the cru-cial role of the hhbp gene in heme transport in H. ducreyi. Several attempts to ligate a kanamycin resistance cassette into hhbp to construct such a mutant were unsuccessful de-spite the systematic alteration of the ligation conditions and the use of kanamycin re-sistant genes derived from a variety of different plasmids. The explanations for this fail-ure are uncertain. In future work, two other approaches to construct an hhbp mutant in-clude the FRT-FLP recombinase technology and the use of overlapping extension PCR with a chloramphenicol cassette.

The complexity of the processes whereby organic species are degraded in the atmosphere prevents many of the individual species (intermediates or products) from being unambiguously identified. Laboratory work necessarily focuses therefore on studies of idealised proxies with the aim of increasing general understanding of the physical and chemical processes which occur on particles and the types of species which they produce. Studies of the ubiquitous proxy oleic acid have resulted in the development of complex reaction schemes describing the various products and intermediates. These schemes include a diverse range of reactions and rates, thus highlighting the complications associated even with a relatively simple system. This thesis describes novel experimental studies designed to increase understanding of heterogeneous ozonolysis reactions of organic species in the aerosol phase using infrared spectroscopy as the principal analytical method. Reactions have been studied in solution (supported by off-line mass spectrometry), in thin films and in aerosols. The sensitivity of the infrared technique has also enabled the kinetics of reactions in thin films and aerosols to be followed. These methods were applied to both single- and mixed-component systems. Product studies successfully identified a number of primary and secondary species in the ozonised systems, with the secondary products formed from association reactions of the Criegee Intermediates with other species present (including self-reaction). In the mixed organic system these products were found to have originated from both a single reactant and from cross reactions between moieties from two different reactants. At low relative humidity, the ozonolysis reaction rates were monitored through the loss of the reactant species by infrared spectroscopy in the thin film and aerosol phase to give reactive uptake coefficients (gamma). At high relative humidity, the formation of products was followed. For the single-component thin films, the values obtained were gamma = 7.8 x 10-5 for stilbene and gamma = 2.0 x 10-7 for anthracene. In thin mixed films of oleic acid and stilbene, segregation occurred which prevented the effect of mixing upon the rate to be measured. A reactive uptake of gamma = 6.8 x 10-5 was obtained, identical to that of pure oleic acid. In the particle phase, the functional form of the reaction kinetics was found to be dependent on the type of particle. Pure stilbene and mixed oleic/stilbene aerosols were highly reactive and it proved necessary to treat reactive uptake coefficients under both diffusion-limited and surface-only reaction scenarios. For stilbene, the values obtained were gamma = 1.5 x 10-3 and gamma = 5.3 x 10-3 respectively. Spectral limitations in the mixed system meant that only the reaction of stilbene could be followed, giving gamma = 4.4 x 10-3 and gamma = 10.0 x 10-3 respectively. The enhanced rate in the mixture was attributed to secondary reactions. Anthracene and oleic acid coated particles were treated using a Langmuir-Hinshelwood mechanism from which the parameters KO3 (ozone partitioning coefficient) and kImax (maximum pseudo-first-order rate coefficient) could be extracted. For anthracene ozonolysis KO3 = 1.4 x 10-16 cm3 molecule-1 and kImax = 3.5x10-2 s-1. For oleic acid coated onto ammonium sulfate aerosols, values obtained were KO3 = 2.35 x 10-15 cm3 molecule-1 and kImax = 0.56 s-1 at low RH% and KO3 = 1.71 x 10-16 cm3 molecule-1 and kImax =0.33 s-1 at high RH%. The reduction in reactivity with increased RH% is principally attributed to the effect of surface polarity on ozone absorption.

Irgarol 1051 is a common antifoulant toxic to certain marine organisms. Submerged aquatic vegetation (SAV) are exposed to this herbicide when it leaches into the marine environment from painted structures, making SAVs ideal candidates to function as sentinel indicator of contamination. In the initial stage of this study, Coconut Grove and Key Largo Harbor were assessed for environmental exposure to Irgarol. Water, sediment and SAVs were collected, the latter two subject to automated solid phase extraction, and all samples analyzed by GC/MS-SIM for Irgarol and its metabolite, M1. Of the vegetation analyzed, Halodule and Syringodium had the highest capacity to bioaccumulate Irgarol and M1. The root system and leaf contributed negligibly and significantly, respectively, to Irgarol uptake. In the final stage, a transplant between Coconut Grove and Chicken Key showed that the biota Thalassia and Halodule were able to uptake and depurate Irgarol, respectively, over a period of 30 days.

Diversos estudos buscam identificar novas moléculas com ações regulatórias sobre a via de sinalização da insulina e consequentemente na homeostase da glicose. Assim, este trabalho visa avaliar o potencial de extratos de frutos no controle da homeostase glicêmica. Os frutos avaliados foram o morango (cv. Toianoca, Camarosa, Oso Grande e Camino Real), a amora-preta e a framboesa vermelha, em dois tempos de amostragem, sendo considerado como tempo A1 e tempo A2. As amostras foram caracterizadas quanto ao seu conteúdo de fenólicos totais, conteúdo de antocianinas monoméricas, capacidade antioxidante, avaliada pelos métodos DPPH e ORAC, ácido elágico total, capacidade de inibição da alfa-glicosidase e captação de glicose e lipólise em tecido adiposo de camundongos (ensaio explante). Dentre os frutos, no primeiro tempo de amostragem, a amora-preta e o morango, cv Oso Grande, foram os que apresentaram maior conteúdo de fenólicos totais (62,36 e 34,89 mg AG/g, respectivamente) no entanto não foram mantidos esses valores no segundo tempo de amostragem, com concentração 30% e 60% inferior, respectivamente; e maior concentração de antocianinas monoméricas (45,33 mg/g e 3,09 mg/g, respectivamente). Em relação a inibição da enzima alfa-glicosidase, avaliado em extrato metanólico, o fruto framboesa vermelha e o morango cv. Camino Real foram as que apresentaram alto potencial inibitório nos dois tempos de amostragem (IC50 0,47 mg FT e IC50 0,57 mg FT para framboesa vermelha e IC50 0,50 mg FT e IC50 0,46 mg FT para Camino Real). Quando avaliado os extratos enriquecidos em fenólicos, o valor de IC50 com maior potencial dentre os frutos avaliados foi da amora-preta, nos dois tempos A1 e A2 (0,0023 mg FT e 0,0021 mg FT, respectivamente). Para captação de glicose em tecido adiposo explate, ao utilizar a insulina para estimular a captação de glicose juntamente com o tratamento (extrato), esse estimulo foi efetivo no aumento da captação de glicose somente com as amostras cv. Camino Real e cv. Oso Grande. Isso pode ser explicado pela alta correlação encontrada de antocianinas identificadas no fruto, como pelargonidina-3-O-glicosídeo. Por outro lado, somente a amora-preta A1 aumentou a lipólise em condição basal, mas nenhuma fruta foi eficiente para reduzir a lipólise em condição estimulada pelo isoproterenol. Sendo assim, frutas vermelhas podem ser boas fontes de compostos bioativos, principalmente antocianinas, as quais podem ter corroborado positivamente com os resultados. / Several studies seek to identify new molecules with regulatory actions on the insulin signaling pathway and consequently on glucose homeostasis. Thus, this work aims to evaluate the potential of fruit extracts in the control of glycemic homeostasis. The fruits evaluated were strawberry (cv. Toianoca, Camarosa, Oso Grande and Camino Real), blackberry and red raspberry, in two sampling times, being considered as time A1 and time A2. Fruits were evaluated for total phenolic, monomeric anthocyanins and contents, antioxidant capacity, evaluated by DPPH and ORAC methods, alpha-glycosidase inhibition capacity and glucose uptake and lipolysis in adipose tissue of mice (explant assay). Among the fruits, in the first sampling period, blackberry and strawberry, cv. Oso Grande, showed the highest total phenolic content (62.36 and 34.89 mg AG / g, respectively), with a decrease of the 30% and 60%, respectively, in the second sampling time; and higher monomeric anthocyanins concentration (45.33 mg/g and 3.09 mg/g, respectively). The methanolic extracts of raspberry and the strawberry cv Camino Real (A1 and A2) presented the highest alpha-glucosidase inhibitory potential. Otherwise, the enriched-polyphenol extract of blackberry (A1 and A2) presented the highest potential among the evaluated fruits. Adipose tissue treated with strawberry cv. Camino Real and cv. Oso Grande was effective in increasing glucose uptake stimulated by insulin. This can be explained by the high correlation with the anthocyanins pelargonidin-3-O-glycoside identified in this fruit. In addition, blackberry A1 was the only sample to increase the lipolysis in basal condition, but all other fruits were not effective to decrease lipolysis in stimulated condition. Thus, berries could be a good sources of bioactive compounds to maintain the glucose homeostasis.

Submitted by Nadir Basilio (nadirsb@uninove.br) on 2016-05-24T19:40:59Z No. of bitstreams: 1 Carina Silveira Mariano Nunes.pdf: 797183 bytes, checksum: 9e449a0364075a44c5f95faf739146f3 (MD5) / Made available in DSpace on 2016-05-24T19:40:59Z (GMT). No. of bitstreams: 1 Carina Silveira Mariano Nunes.pdf: 797183 bytes, checksum: 9e449a0364075a44c5f95faf739146f3 (MD5) Previous issue date: 2014-12-15 / Introduction: Physiological responses during activities of daily living (ADLs) have never been studied in adult patients with bronchiectasis (BCT). Aim: To compare the metabolic and ventilatory demands, gas exchange and perception of effort during five ADLs between adults with BCT and healthy subjects. Methods: Thirty-nine subjects [27 women; FEV1 61 ± 26, %pred, MRC 3 (2 – 3)] and twenty healthy subjects (14 women) performed the following five ADL: (1) putting on socks, shoes, and vest, (2) putting away different weights on a rack, (3) sweeping a floor, (4) carrying weight while walking (5Kg), and (5) climbing stairs during a minute. Activities 2, 3, and 4 were performed by five minutes. Pulmonary gas exchange was measured during all ADLs. Results: Patients used a higher proportion of metabolic and ventilatory demands, and had a higher perception of effort when compared with healthy subjects. The distance walked in ADL4 was similar between groups; however patients climbed lower number of steps than control group. Conclusions: Patients with BCT have high metabolic and ventilatory demands, with a higher perception of effort to perform simple daily activities when compared to healthy subjects. / Introdução: As respostas fisiológicas durante atividades de vida diária (AVD) nunca foram estudadas em pacientes adultos com bronquiectasia (BCQ). Objetivo: Comparar as respostas cardiopulmonares, metabólicas, de trocas gasosas e de percepção de esforço durante atividades de vida diária entre pacientes com bronquiectasia e indivíduos saudáveis. Método: 39 pacientes [27 mulheres; VEF1 61 ± 26 %prev; MRC 3 (2 – 3)] e 20 indivíduos saudáveis (14 mulheres) realizaram as seguintes AVD: (1) vestir um par de meias e um par de sapatos sentado em uma cadeira e vestir uma camisa em pé; (2) colocar pesos de 0,5 Kg, 1 Kg, 2 Kg, 3 Kg, 4 Kg e 5 Kg em uma prateleira ao nível da cabeça e depois retornar os mesmos ao nível da cintura; (3) varrer o chão; (4) caminhar carregando 5Kg divididos em duas sacolas; e (5) subir escadas durante um minuto. As atividades 2, 3 e 4 foram realizadas durante cinco minutos. As variáveis metabólicas e ventilatórias foram registradas durante todas as AVD. Resultados: Os pacientes com BCQ tiveram maior demanda metabólica e ventilatória e maior percepção de esforço durante todas AVD quando comparados ao grupo controle (p < 0,05). A distância percorrida na AVD4 não diferiu entre os grupos, mas os pacientes realizaram menor número de degraus na AVD5 em relação ao grupo controle. Análise intra-grupo (BCQ) demonstrou aumento progressivo (p < 0,05) no VO2, VE/VVM e percepção do esforço da AVD1 até a AVD5. Conclusão: Pacientes com BCQ utilizam elevada proporção da capacidade aeróbia e ventilatória máxima para realizarem atividades simples do dia a dia e com maior percepção de esforço (dispneia e fadiga) quando comparados a indivíduos saudáveis.

El presente trabajo destaca la simulación numérica como herramienta capaz de reproducir y predecir los principales procesos que producen y mantienen los ecosistemas de llanuras de inundación. Para ello, la dinámica del flujo, la actividad geomorfológica, la sedimentación y la captura de nutrientes de la llanura de inundación, son evaluadas experimentalmente. Seguidamente, los datos experimentales son incluidos en un modelo numérico para desarrollar una herramienta completa de simulación capaz de predecir la dinámica del flujo, la actividad geomorfológica, la sedimentación, el aporte de nutrientes del río a la llanura de inundación así como la captación de los mismos. El estudio se desarrolla en un segmento del río Ebro (NE España), representativo de su tramo medio meandriforme. El estudio emplea un modelo numérico bidimensional (2D), basado en las ecuaciones 2D de las aguas poco profundas y calculado a partir del método de los volúmenes finitos. La calibración del modelo se basa en medidas experimentales realizadas en la llanura de inundación bajo dos caudales estacionarios. La validación del modelo se llevó a cabo comparando los resultados numéricos con las medidas experimentales de nivel de agua y extensión del área inundada realizadas durante los cinco eventos de riada ocurridos en el año 2007 (79+13 % área; 0.27+0.05m nivel de agua). Las simulaciones fueron utilizadas para analizar la dinámica actual de inundación de la llanura así como su actividad geomorfológica. Como resultado, se obtuvo que el presente régimen de caudales y sobretodo la estructura morfológica de la llanura, no resulta suficiente para generar una actividad geomorfológica tal que mantenga el mosaico cambiante de hábitats característico de los ecosistemas de llanura de inundación. La nueva formulación que describe la retención de nutrientes se ha desarrollado mediante la utilización de los datos experimentales, en condiciones de flujo controladas, semi-controladas y en el propio río Ebro. / González Sanchis, MDC. (2012). Flooding dynamics and nutrient retention in the middle Ebro floodplain: experimental assessment and numerical modeling [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/15242 / Palancia

Aerosols are important atmospheric constituents that impact the Earth's radiative balance and climate. The detailed knowledge of the aerosol optical properties is required for a comprehensive analysis of the impacts of aerosols on climate. Mie theory is often used in satellite and ground-based retrieval algorithms to account for atmospheric mineral dust. However, the approximations used in Mie theory are often not appropriate for mineral dust and can lead to errors in the optical properties modeling. Analytic models based on Rayleigh theory that account for particle shapes can offer significant advantages when used to model infrared (IR) extinction of mineral dust. Here, the IR optical properties of some components of mineral dust, authentic dust samples and minerals processed with organic acids were investigated. Detailed characterization of the particles through online and offline methods of analysis that include IR extinction spectroscopy, micro-Raman spectroscopy and scanning electron microscopy was performed. Analysis of the IR extinction spectra and spectral simulations showed that the positions of the peaks and the shapes of the bands of the IR characteristic features are not well simulated by Mie theory in any of the samples studied. The resonance peaks were consistently shifted relative to the experimental spectrum in the Mie simulation. Rayleigh model solutions derived for different particle shapes better predicted the peak positions and band shapes of experimental spectra. To fill the gaps in the refractive index data for atmospherically relevant organic compounds in the IR region optical properties of atmospherically relevant carboxylic acids and humic-like substances using the IR extinction spectra and size distributions measured in the laboratory were determined. In addition to properties of mineral dust this dissertation focuses on properties of sea spray aerosol. Chemical and elemental composition of individual sea spray aerosol particles were studies using micro-Raman spectroscopy, mass-spectrometry and X-ray spectroscopy to provide insights into the biochemical processes that give rise to classes of organic molecules that make up these aerosol particles. The results suggested that degradation of biota (bacteria and diatoms) present in sea water led to lipopolysaccharides and extracellular polymeric substances that further degraded down to carbohydrates and fatty acids. Solubility of the resulting organic species seemed to play a role in their transfer to the aerosol phase. Furthermore, water uptake and hygroscopic growth of multi-component particles were studied. Understanding the interactions of water with atmospheric aerosols is crucial for determining their size, physical state, reactivity, and therefore for aerosol interactions with electromagnetic radiation and clouds. It was determined that particles composed of ammonium sulfate with succinic acid and of mixture of chlorides typical for marine environment show size dependent hygroscopic behavior. Microscopic analysis of the distribution of components within the aerosol particles showed that the observed size dependence is due to the differences in the mixing state. The composition and water uptake properties of sea spray aerosol particles were also measured during a phytoplankton bloom. The results showed that water uptake properties were directly related to the chemical composition of the particles and hygroscopicity decreased with increase in the fraction of water insoluble organic matter emitted during phytoplankton bloom. Finally, multiple methods of particle size, phase and shape analysis were compared and the results showed that the techniques that operate under ambient conditions provide the most relevant and robust measurement of particle size. Additionally, several storage methods for substrate deposited aerosol particles were evaluated and it was determined that storing samples at low relative humidity led to irreversible changes due to sample dehydration while sample freezing and thawing leads to irreversible changes due to phase changes and water condensation. Therefore it is suggested that samples used for single-particles analysis should be stored at ambient laboratory conditions, or near conditions which they were collected, in order to preserve the sample phase and hydration state. The results presented in this dissertation provide insight into physicochemical properties of atmospheric aerosols and help us better understand the role of aerosol particles in the Earth's atmosphere.

Les cellules dendritiques (DC) sont les cellules professionnelles de la capture et de la présentation antigènique et font l'interface entre l'immunité innée et l'immunité adaptative. Suite à la reconnaissance de divers signaux de dangers (PAMP/DAMP), les DC s'activent et dégradent l'antigène afin de le présenter aux LT naïfs dans les organes lymphoïdes secondaires et ainsi initient une réponse immunitaire immunogène ou tolérogène. Le contrôle de la réponse immunitaire est notamment possible grâce aux lymphocytes T régulateurs. Il en existe deux types : les nTreg qui se différencient dans le thymus et les pTreg qui se différencient dans les organes lymphoïdes secondaires et/ou dans les tissus. Les DC sont indispensables à leur activation et à leur différenciation respectivement. Les Treg possédent un arsenal variés de mécanismes qui leur conférent leur fonction régulatrice : sécrétion de cytokines immunosuppressives (IL-10, TGF-β et IL-35), activité cytotoxique, déprivation de l'environnement en IL-2….Selon la nature des réponses lymphocytaires T CD4 qu'elles induisent, les DC peuvent être classées fonctionnellement en DC activatrices/immunogènes (DCact) versus DC tolérogènes (DCreg). Les DCact sont définies par leur capacité à induire des lymphocytes T CD4 effecteurs et CD8 cytotoxiques. Les DCreg sont caractérisées par leur capacité à induire des Treg qui vont contrôler la réponse immunitaire. Ces DCreg peuvent être induites par des cytokines (IL-10 et TGF- β produites par exemple par certains Treg), sous l'effet sous l'effet de vitamines anti-oxydantes ou de la vitamine D3, de l'acide rétinoïque, par traitement aux glucocorticoïdes (GC) ou encore sous l'effet de facteurs produits par des pathogènes comme la toxine cholérique. Durant mes travaux de thèse je me suis intéressé aux conséquences physiologiques de l'expression de la protéine Glucocorticoid-Induced Leucine Zipper dans les DC. En effet, les DC humaines et murines surexpriment cette protéine sous l'effet des GC, de l'IL-10, du TGF-β, de la mitomycin C, de la rapamycine, de la vitamine D3 et enfin de l'environnement tumoral. Sur des DC dérivées de monocytes, ils avait été montré que GILZ est nécessaire et suffisant pour induire un phénotype (diminution de l'expression membranaire de CD40, CD80, CD86, CMH-II et augmentation de PD-L1 et ILT-3) et une fonction (sécrétion d'IL-10 et diminution de la production de CCL3, CCL5 et CXCL8) tolérogènes chez ces cellules. De plus, les DC GILZhi sécrètent de l'IL-10 et induisent la différenciation de Treg CTLA-4+IL-10+, spécifiques de l'antigène, dont certains expriment le facteur de transcription FoxP3 et qui inhibent la prolifération de LT CD4 autologues. Mes travaux ont pour finalité d'évaluer l'importance physiologique de l'expression de GILZ par les DC in vivo, et en particulier sa contribution à l'induction et au maintien de la tolérance immunologique à l'homéostasie ou dans un contexte pathologique. Pour atteindre ces objectifs, je disposais de deux modèles de souris complémentaires, créés au laboratoire, les souris CD11c-GILZhi, surexprimant GILZ spécifiquement dans les DC, et les souris CD11c-GILZko, conditionnellement déficientes pour GILZ dans leurs DC. Les travaux que j'ai effectués jusqu'à présent ont permis d'établir que la surexpression de GILZ dans les DC leur confère un phénotype tolérogène in vivo (faible expression des molécules de CMH II et production d'IL-10) et est suffisante pour induire une accumulation de Treg à l'homéostasie et une expansion de nTreg suite à une stimulation antigénique. De plus, L'absence de GILZ dans les DC leur confère une capacité de capture antigènique par macropinocytose accrue. In vivo, cet accroissement de la capture est sélectif et ne touche que les DC CD8α+.Finement régulée par des signaux antigéniques, biologiques ou chimiques, GILZ est un puissant régulateur de la balance immunogénicité/tolérogénicité dans les fonctions de la DC. / Dendritic cells (DC) are professionnal antigen-presenting cells and interface between innate immunity and adaptative immunity. After danger signals recognition, DC activate and process antigen to present to naive T cells in the secondary lymphoid organs (SLO) and thus, initiate the immune response, immunogenic or tolerogenic. Control of immunitary response is possible by regulatory T cells (Treg). There are two types of Treg : nTreg that differenciate in the thymus, and pTre that differenciate in SLO and/or in tissues. DC are essential for their activation or their differenciation respectively. Treg possess a large arsenal of regulatory mechanisms : cytokines secretion (IL-10, TGF-B and IL-35), cytotoxic activity, IL-2 environnement deprivation…According to theT CD4 lymphocytary responses, DC are functionnaly classified in activator/immunogenic DC (DCact) versus tolerogenic DC (DCreg). DCact induce effector CD4 T cells and cytotoxic CD8 T cells. DCreg induce Treg controlling the immune response. DCreg can be induce by cytokines (IL-10 and TGF-B produce by Treg for example), by anti-oxidant vitamin or vitamin D3, by retinoic acid, by glucocorticoid (GC) treatment and by various product of pathogens. During my thesis work, I focused on the physiological consequences of GILZ expression in DC. Human and murin DC overexpress GILZ after GC treatment and after treatment with IL-10, TGF-B, mitomicyn C, rapamycin, vitamin D3 and under the influence of the tumoral microenvironnement. On monocytes derived-DC, it has been demonstrated that GILZ is necessary and sufficient to induce a tolerogen phenotype (decrease of CD40, CD80, CD86, MHC-II expression and increase of PD-L1 and ILT-3 expression) and functionnality (IL-1à secretion and decrease of CCL3, CCL5 and CXCL8 production). So, GILZhi DC induce the differenciation of antigen-specific CTLA-4+IL-10+ Treg whose a part express FoxP3 and inhibit the proliferation of CD4 autologous T cells. My work evaluate the physiological importance of GILZ expression by DC in vivo, and more particularlythe contribution of this expression on the induction and the support of the immune tolerance at homeostasis and in pathologic context. To reach my objectives, I haved two complementary murin models, created in the laboratory : the CD11c-GILZhi mice, overexpress GILZ specifically in the DC, and the CD11c-GILZko mice, deficient for GILZ expression in mice. Studies I have done show that overexpression of GILZ in vivo in DC induce a tolerogenic phenotype in these cells (decrease of MHC-II expression and IL-10 production) and is sufficient to induce accumulation of Treg at homeostasis and expansion of nTreg after antigenic stimulation. Thus, lack of GILZ in DC increase their macropinocytic antigen uptake capacity. In vivo, this increase is selective of CD8a+ DC. Being strongly regulated by antigen, biologic or chemicals signals, these work show GILZ like a powerful regulator of the immunogenecity/tolerogenicity balance in the DC functionnalities.