Reproduction de : Thèse de doctorat : Médecine. Sciences de la vie et de la santé. Immunologie - Virologie : Nantes : 2008. / Bibliogr.

Approximately two-thirds of US adults are overweight or obese, and obesity is also becoming more prevalent in children and adolescents. Similar to adults, obese children are at a higher risk of developing health problems due in part to dysfunctional immune surveillance. Obesity has been shown reduce the generation of new T-cells by accelerating thymic aging in an adult mouse. This study therefore aimed at determining whether similar diet induced obesity (DIO) changes can be induced in a young mouse. Comparisons made between lean and DIO C57Bl/6 mice showed a significant increase in thymic weight, decrease in thymic cellularity and thymic output, and impaired T-cell development at the double negative stage. We associate these alterations with changes in thymic architecture and accumulation of lipid droplets within the thymic cortex and medulla of the obese mice. The above observations indicate that DIO can induce fat accumulation and reduce thymic function at a young age. Resveratrol, a natural polyphenolic compound, was then used to regulate fat metabolism in an attempt to reduce these DIO changes we observed. Resveratrol induces fat oxidation via 5' adenosine monophosphate-activated protein kinase (AMPK), and its reciprocal regulation of glycerol-3-phosphate acyltransferase-1 (GPAT-1) and carnitine palmitoyltransferase-1 (CPT-1), the rate-limiting enzymes required for glycerophospholipid biosynthesis and oxidation, respectively. Through resveratrol feeding, we were able to prevent the effects of DIO on thymic architecture and thymic T-cell proliferation. This was achieved by manipulating AMPK into inhibiting GPAT-1 and enhancing CPT-1 activity. Since the expression of GPAT-1 was upregulated in the obese mice, we investigated whether deleting GPAT-1 altogether might prevent the thymic involution, by inhibiting synthesis of glycerophospholipids and triacylglycerol. Instead, we found that GPAT-1 deletion slowed thymic growth and reduced cellularity in young mice, which we associated with impaired thymic T-cell function and development, suggesting that the deleterious effects of GPAT-1 deficiency may be due to perturbations in thymic T-cell activation and signaling. These data provide a novel link between lipid metabolism and T-cell development, and identify the use of the naturally-occurring resveratrol to reduce lipid accumulation within the involution-prone thymus, thus providing a useful approach to preventing a decline in thymic function in childhood. / text

The finding that more than 152 tissue-restricted antigens are expressed by thymic medullary epithelial cells is redefining the importance of thymic central tolerance induction in the prevention of autoimmune diseases. One of the tissue-restricted antigens in the thymus is proinsulin, and in both mice and humans, reduced thymic proinsulin levels have been shown to predispose to Type 1 diabetes. Using transgenic mice expressing a functional beta-Galactosidase gene under the regulation of the Ins2 promoter we have determined that between 1-3% of all medullary thymic epithelial cells express proinsulin and that these cells are frequently part of the Hassall's Corpuscles like structures in mice. Using a cross between the beta-Galactosidase expressing mice and Immortomice (expressing SV40 large T Antigen under the regulation of the MHC I promoter), we have isolated and cultured two proinsulin and two non-proinsulin producing medullary epithelial cell lines. Microarray analysis and RT-PCR analysis of the cell lines revealed the over-expression of approximately 50 genes (>4 fold or more) in the proinsulin producing lineage, versus the non proinsulin producing lineage, and approximately half the over-expressed genes can be considered tissue-restricted antigens. We do not find any evidence for chromosomal clustering of the over-expressed genes nor do we report the expression of any other pancreatic n-cell antigens or specific pancreatic proinsulin regulatory proteins (Pdx-1, Glut-2 or GCK) within the proinsulin producing cell lines but we do detect their expression in whole thymus. Our results suggest that chromosomal clustering is not a phenomenon associated with thymic tissue-restricted antigen expression and that the mechanisms allowing for thymic tissue-restricted antigen expression are not related to the expression mechanisms of such antigens in peripheral tissues.

Thymus genties rūšims būdingas moteriškasis dvinamiškumas, kai rūšies populiaciją sudaro drauge augantys dvilyčiai ir vienalyčiai moteriški individai. Tiek skirtingose rūšyse, tiek tos pačios rūšies skirtingose augavietėse dvilyčių ir vienalyčių moteriškų individų santykis gali labai skirtis. Iki šiol nėra pilnai išaiškinta, kokie veiksniai ir kaip gali įtakoti šiuos skirtumus. Šio darbo tikslas buvo įvertinti Lietuvos floros Thymus genties rūšių Thymus pulegioides L., Thymus serpyllum L. bei jų tarprūšinio hibrido Thymus × oblongifolius Opiz lyties polimorfizmą nulemiančio moteriškojo dvinamiškumo pasireiškimą natūraliose augavietėse, besiskiriančiose ekologinėmis sąlygomis bei amžiumi; taip pat įvertinti dvilyčių ir vienalyčių moteriškų individų žiedų skirtumus pagal kai kuriuos morfologinius požymius. Viso buvo ištirta 51 T. × oblongifolius, 48 T. pulegioides, 39 T. serpyllum augavietės. Bendrijų su čiobreliais aprašymai buvo atlikti pagal laukelinį maršrutinį aprašomąjį metodą, taikant J. Braun-Blanquet mokyklos augalijos tyrimo ir klasifikavimo principus. Kiekvienoje augavietėje suskaičiuoti Thymus genties rūšių vienalyčiai moteriški ir dvilyčiai individai ir suskaičiuotas jų santykis. Naudojantis išmatuotų augaviečių dydžiu bei jose augusių Thymus genties individų skaičiumi, buvo apskaičiuotas T. pulegioides, T. serpyllum bei T. × oblongifolius individų tankis tirtose augavietėse. Buvo įvertintas augaviečių santykinis apšviestumo laipsnis, reljefas, ekspozicija, žolių... [toliau žr. visą tekstą] / The Thymus genus is characterised by gynodioecy, when population of the same species is comprised of hermaphrodites and females individuals. The proportion of hermaphrodite and female individuals can differ both in different species and in different populations within the same species. The aim of this work was to evaluate the occurrance of gynodioecy, that determines sex polymorphism within Thymus genus (Thymus pulegioides L., Thymus serpyllum L. and their interspecific hybrid Thymus × oblongifolius Opiz), in natural populations of Lithuania biota, wich differ in ecological conditions and age; and also to establish differences between hermaphrodite and female individuals blossoms using particular morphological features. There was totally 51 T. × oblongifolius, 48 T. pulegioides and 39 T. serpyllum populations explored. The communities with Thymus descriptions were made according to squares shuttle descriptive approach, using J. Braun-Blanquet school of vegetation survey and classification principles. In each population all the Thymus sp. hermaphrodites and females individuals, and their proportions in the population were counted. In order to calculate the density of T. pulegioides, T. serpyllum and T. × oblongifolius individuals, populations size was measured and Thymus sp. individuals were counted. And finally the illumination, relief, exposition, coverage of the herbs, shrubs, trees, mosses and lichens was valued. In this work from each species totally 300 hermaphrodites... [to full text]

The generation of the cytotoxic CD8 T cell response is dependent on the functional outcomes imposed by the intrathymic constraints of differentiation and self-tolerance. Although thymic function can be partly replicated in vitro using OP9-DL1 cell cultures to yield CD8 αβ T cell receptor (TCR)-bearing cells from hematopoietic progenitor cells, a comprehensive and functional assessment of entirely in-vitro generated CD8 T cells derived from bone marrow hematopoietic stem cells (BM-HSCs) has not been established and remains controversial. Here we demonstrate that a phenotypic, molecular, and functional signature of in vitro-derived CD8 T cells is akin to that of ex vivo CD8 T cells. Transfer of in vitro-derived CD8 T cells into syngeneic and immunodeficient host mice showed no graft-versus-host response, while a robust homeostatic proliferation was observed, respectively. These findings, along with a diverse and broad TCR repertoire expressed by the in vitro-derived CD8 T cells, allowed for the successful generation of antigen (Ag)-specific T cells to be obtained from an entirely in vitro-generated CD8 T cell pool, which calls for further tailoring of their use against viral infections or malignancies. Furthermore, I demonstrate that Notch signaling regulates the expression of the cytolytic molecule Granzyme A in CD8+ T cells. This is supported by the inability of Notch-deprived TCR-signaled CD8 T cells to express Granzyme A, while CD8 T cells that received Notch signals readily expressed Granzyme A, suggesting that Notch signaling is a prerequisite for induction of this cytolytic molecule. We further demonstrate that Notch signaling by OP9 cells allows for efficient differentiation of conventional effector CD8 T cells from SAP-/- BM-derived HSCs and restricts differentiation of innate CD8 T cells while allowing for differentiation of IL17-producing CD8 T cells from BM-HSCs isolated from Itk-/-Rlk-/- (DKO) mice. Moreover, we reveal that the process of positive and negative selection in vitro is constrained by peptide-MHC (pMHC) class I expressed by the OP9 cells and disclose that the commitment of DP precursors to the CD8 T cell lineage is facilitated by Notch signaling. Our findings further establish the requirement for Notch receptor-ligand interactions throughout intrathymic T cell differentiation.

No description available.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

The generation of the cytotoxic CD8 T cell response is dependent on the functional outcomes imposed by the intrathymic constraints of differentiation and self-tolerance. Although thymic function can be partly replicated in vitro using OP9-DL1 cell cultures to yield CD8 αβ T cell receptor (TCR)-bearing cells from hematopoietic progenitor cells, a comprehensive and functional assessment of entirely in-vitro generated CD8 T cells derived from bone marrow hematopoietic stem cells (BM-HSCs) has not been established and remains controversial. Here we demonstrate that a phenotypic, molecular, and functional signature of in vitro-derived CD8 T cells is akin to that of ex vivo CD8 T cells. Transfer of in vitro-derived CD8 T cells into syngeneic and immunodeficient host mice showed no graft-versus-host response, while a robust homeostatic proliferation was observed, respectively. These findings, along with a diverse and broad TCR repertoire expressed by the in vitro-derived CD8 T cells, allowed for the successful generation of antigen (Ag)-specific T cells to be obtained from an entirely in vitro-generated CD8 T cell pool, which calls for further tailoring of their use against viral infections or malignancies. Furthermore, I demonstrate that Notch signaling regulates the expression of the cytolytic molecule Granzyme A in CD8+ T cells. This is supported by the inability of Notch-deprived TCR-signaled CD8 T cells to express Granzyme A, while CD8 T cells that received Notch signals readily expressed Granzyme A, suggesting that Notch signaling is a prerequisite for induction of this cytolytic molecule. We further demonstrate that Notch signaling by OP9 cells allows for efficient differentiation of conventional effector CD8 T cells from SAP-/- BM-derived HSCs and restricts differentiation of innate CD8 T cells while allowing for differentiation of IL17-producing CD8 T cells from BM-HSCs isolated from Itk-/-Rlk-/- (DKO) mice. Moreover, we reveal that the process of positive and negative selection in vitro is constrained by peptide-MHC (pMHC) class I expressed by the OP9 cells and disclose that the commitment of DP precursors to the CD8 T cell lineage is facilitated by Notch signaling. Our findings further establish the requirement for Notch receptor-ligand interactions throughout intrathymic T cell differentiation.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Submitted by WAGNER GARCEZ DE MELLO (wagnergarcez@foa.unesp.br) on 2016-05-19T11:31:47Z No. of bitstreams: 1 TESE - WAGNER GARCEZ DE MELLO.pdf: 3737001 bytes, checksum: e1ec14f336cc47469d8097ff9f7d4d47 (MD5) / Rejected by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br), reason: Troca solicitada pelo autor, por favor realize uma nova submissão com o arquivo correto on 2016-05-19T14:28:25Z (GMT) / Submitted by WAGNER GARCEZ DE MELLO (wagner_garcez@hotmail.com) on 2016-05-19T14:44:43Z No. of bitstreams: 1 TESE - WAGNER GARCEZ DE MELLO.pdf: 3729799 bytes, checksum: 31766ebe878f0096a9110e22b5aa8e50 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-05-19T18:05:09Z (GMT) No. of bitstreams: 1 mello_wg_foa.pdf: 3729799 bytes, checksum: 31766ebe878f0096a9110e22b5aa8e50 (MD5) / Made available in DSpace on 2016-05-19T18:05:09Z (GMT). No. of bitstreams: 1 mello_wg_foa.pdf: 3729799 bytes, checksum: 31766ebe878f0096a9110e22b5aa8e50 (MD5) Previous issue date: 2016-03-21 / O presente trabalho avaliou os efeitos da timectomia neonatal sobre o dimorfismo sexual esquelético e qualidade óssea, bem como, determinou se as alterações causadas por este modelo podem influenciar as secreções de leptina em animais pré-púberes, púberes e adultos-jovens. Para isso, Ratos Wistar, neonatos foram divididos em grupo controle e grupo timectomizado, de ambos os sexos, totalizando quatro grupos experimentais (n = 06-08 por grupo). Os animais foram timectomizados no terceiro dia pós-natal. Os grupos foram eutanasiados aos 20, 40 e 120 dias pós-natais, que correspondem, respectivamente, às fases pré-púbere, púbere e adultos-jovens. Foram coletados sangue e ambos os fêmures. Os fêmures esquerdos foram usados para determinação do comprimento, realizado com auxílio de um paquímetro. Avaliação das propriedades biofísicas do fêmur foram determinadas por meio do teste de densitometria óssea, e o comportamento biomecânico avaliado por meio do o ensaio mecânico de compressão da cabeça do fêmur. Os fêmures direitos foram usados para avaliação histométrica da base do colo femoral. As amostras sanguíneas foram utilizadas para determinar as concentrações plasmáticas de leptina. Em conjunto os dados do presente trabalho demonstram que em animais controle, as diferenças sexualmente dimórficas em relação ao desenvolvimento corporal e esquelético, bem como na secreção de leptina, existem durante o período pré-púbere, mas são consolidadas após a puberdade. Demonstram ainda, que a timectomia neonatal causa alterações sexo- e tempo-dependentes no desenvolvimento corporal, propriedades estruturais e biomecânicas do tecido ósseo, além de modular a secreção plasmática de leptina, sugerindo uma comunicação bidirecional entre o Timo e esse hormônio. Estes resultados fornecem uma nova visão sobre a complexidade dinâmica da homeostase da massa óssea e sugerem que a presença do Timo durante o período perinatal é importante para o desenvolvimento esquelético normal. / This study evaluates the effects of neonatal thymectomy on skeletal sexual dimorphism and bone quality. In addition, we verified whether the changes caused by this model may influence the leptin secretion in prepubertal, puberty and adulthood. For this, Wistar, newborns were divided into control group and thymectomized group, of both sexes, totaling four experimental groups (n = 08 per group). The animals were thymectomized at the third postnatal day. The groups were euthanized at 20, 40 and 120 days’ postnatal life, which correspond respectively to the prepuberty, puberty and adulthood periods. Blood and both femurs were collected. The left femurs were used to determine the length, conducted with the aid of a caliper. The biophysical properties of the femur were evaluated using dual-energy x-ray absorptiometry, and the biomechanical properties assessed by the mechanical compression of the femoral head. In the right femurs, the base of the femoral neck was used to quantitative histometric analysis. The blood samples were used to determine plasma concentrations of leptin. Taken together, the data of the present study demonstrates that control animals, sexually dimorphic differences in relation to body and skeletal development as well as the secretion of leptin, there during the prepubertal period but are consolidated after puberty. Demonstrate further that the neonatal thymectomy causes changes sex- and time-dependent on body development, structural and biomechanical properties of bone tissue, as well as plasma leptin secretion, suggesting a cross-talk between Thymus and this hormone. These findings provide new insight into the dynamic complexity of bone homeostasis and suggest that the presence of Thymus during the perinatal period is important for normal skeletal development.