Thesis (Ph.D.)--University of Alabama at Birmingham, 2007. / Title from PDF title page (viewed on Sept. 16, 2009). Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 92-100).

Made available in DSpace on 2015-10-06T13:03:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-23. Added 1 bitstream(s) on 2015-10-06T13:18:56Z : No. of bitstreams: 1 000819087.pdf: 1423284 bytes, checksum: a89857bcef9822e82a34c2b6424c6064 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A leishmaniose visceral é uma doença que causa manifestações clínicas variadas em cães, que podem apresentar desde alterações subclínicas a desordens generalizadas, incluindo alterações neurológicas. Há evidências do comprometimento das barreiras encefálicas, como a presença de infiltrado inflamatório com predomínio de linfócitos T CD3+ no sistema nervoso central. Deste modo, o objetivo deste trabalho foi determinar e comparar os imunofenótipos de linfócitos T no sangue periférico e no liquor e avaliar as lesões encefálicas em cães infectados. Verificou-se que os linfócitos T presentes em maior quantidade no liquor foram os duplos negativos (DN) e os duplos positivos (DP), com predomínio de TCRαβ. Também verificou-se que as células sanguíneas não diferiram das células do liquor em quantidade, o que indica que pode estar havendo um comprometimento da barreira hematoliquórica, permitindo que as células do sangue migrem para o liquor. Ocorreu também o predomínio de infiltrado linfohistioplasmocitário no encéfalo, principalmente em leptomeninges. Porém, não houve correlação entre a inflamação nessa área e as células T. Além disso, a correlação positiva entre a inflamação no subepêndima e as células T DN do liquor indica que essas células chegam no encéfalo também pelos vasos subependimários. Em conjunto, os resultados contribuem para explicar a inflamação observada no encéfalo de cães com leishmaniose, sendo que as células T DN podem ser responsáveis pela progressão neurológica da doença / Visceral leishmaniasis (VL) is a disease causing several clinical manifestations in dogs, that can present from subclinical to generalized disorders, including neurological disorders. There are evidences of cerebral barriers involvement, such as the presence of inflammatory infiltrate with predominance of CD3+ T cells in the brain of infected dogs. Therefore, the aim of this study was to determine and to compare the immunophenotypes of T lymphocytes in the peripheral blood and in the cerebrospinal fluid (CSF) of dogs with VL and evaluate the brain lesions. It was detected that the double negative (DN) and double positive (DP) T cells were present in higher percentage in the CSF, with predominance of TCRαβ. Besides, the amount of blood T cells did not differ from those observed in the CSF, indicating that the blood-CSF barrier may be damaged, allowing the migration of cells from the blood to the CSF. Moreover, inflammatory infiltrate with predominance of lymphohistioplasmacytic cells was observed, mainly in leptomeninges. However, there was no correlation between the intensity of the inflammation in this area and the T cells. Furthermore, the positive correlation between intensity of the inflammation in the subependimal area and DN T cells in the CSF indicates that these cells also may reach the brain through the subependymal vessels. Together, the results contribute to explain the inflammation observed in the brain of dogs with VL, where the DN T cells may contribute to the neurological progression of the disease

Resumo: A leishmaniose visceral é uma doença que causa manifestações clínicas variadas em cães, que podem apresentar desde alterações subclínicas a desordens generalizadas, incluindo alterações neurológicas. Há evidências do comprometimento das barreiras encefálicas, como a presença de infiltrado inflamatório com predomínio de linfócitos T CD3+ no sistema nervoso central. Deste modo, o objetivo deste trabalho foi determinar e comparar os imunofenótipos de linfócitos T no sangue periférico e no liquor e avaliar as lesões encefálicas em cães infectados. Verificou-se que os linfócitos T presentes em maior quantidade no liquor foram os duplos negativos (DN) e os duplos positivos (DP), com predomínio de TCRαβ. Também verificou-se que as células sanguíneas não diferiram das células do liquor em quantidade, o que indica que pode estar havendo um comprometimento da barreira hematoliquórica, permitindo que as células do sangue migrem para o liquor. Ocorreu também o predomínio de infiltrado linfohistioplasmocitário no encéfalo, principalmente em leptomeninges. Porém, não houve correlação entre a inflamação nessa área e as células T. Além disso, a correlação positiva entre a inflamação no subepêndima e as células T DN do liquor indica que essas células chegam no encéfalo também pelos vasos subependimários. Em conjunto, os resultados contribuem para explicar a inflamação observada no encéfalo de cães com leishmaniose, sendo que as células T DN podem ser responsáveis pela progressão neurológica da doença / Abstract: Visceral leishmaniasis (VL) is a disease causing several clinical manifestations in dogs, that can present from subclinical to generalized disorders, including neurological disorders. There are evidences of cerebral barriers involvement, such as the presence of inflammatory infiltrate with predominance of CD3+ T cells in the brain of infected dogs. Therefore, the aim of this study was to determine and to compare the immunophenotypes of T lymphocytes in the peripheral blood and in the cerebrospinal fluid (CSF) of dogs with VL and evaluate the brain lesions. It was detected that the double negative (DN) and double positive (DP) T cells were present in higher percentage in the CSF, with predominance of TCRαβ. Besides, the amount of blood T cells did not differ from those observed in the CSF, indicating that the blood-CSF barrier may be damaged, allowing the migration of cells from the blood to the CSF. Moreover, inflammatory infiltrate with predominance of lymphohistioplasmacytic cells was observed, mainly in leptomeninges. However, there was no correlation between the intensity of the inflammation in this area and the T cells. Furthermore, the positive correlation between intensity of the inflammation in the subependimal area and DN T cells in the CSF indicates that these cells also may reach the brain through the subependymal vessels. Together, the results contribute to explain the inflammation observed in the brain of dogs with VL, where the DN T cells may contribute to the neurological progression of the disease / Orientador: Gisele Fabrino Machado / Banca: Valéria Marçal Felix de Lima / Banca: Antonio Carlos Alessi / Mestre

Environ, 60 % des personnes atteintes d’un cancer auront au moins une séance de radiothérapie au cours de la prise en charge thérapeutique de leur maladie. Les doses de radiothérapie sont limitées en raison du risque important de fibrose séquellaire des tissus sains. Les rayonnements ionisants (RI) peuvent induire différents types de mort cellulaire y compris l'apoptose et la sénescence. Les cellules sénescentes ont une sensibilité réduite à l'apoptose et un phénotype sécrétoire inflammatoire. De plus, les RI peuvent induire la production d’espèces réactives de l’oxygène (ERO) qui provoquent des lésions de l'ADN dans les tissus non ciblés, et des effets systémiques associés à l'inflammation. Différentes équipes ont proposé des tests prédictifs de la radiosensibilité individuelle des patients basés sur l’évaluation du taux d'apoptose radio-induite des lymphocytes T CD4+/CD8+ (LT). Cependant, l’impact des différences de sensibilité à l’apoptose/sénescence des sous-populations de LT sur le taux d’apoptose n’a pas été étudié. Notre hypothèse est que la sensibilité à l’apoptose/sénescence radio-induite des LT circulants est associée à la sur/sous-représentation de sous-populations particulières de LT CD4+ dont les fonctions sont en rapport avec la survenue de fibrose. Nos résultats chez le donneur sain montrent que les LT CCR6+Th17 pro-fibrogéniques sont moins sensibles à l’apoptose et plus sensibles à la sénescence que les LT CCR6negTh et les Treg. Cette sénescence peut être préjudiciable car les lymphocytes CCR6+Th17 situés dans les tissus irradiés peuvent sécréter de l'IL-8 et du VEGF-A. La modulation des voies ERO/MAPK ou mTOR pourrait être une cible potentielle pour la prévention de la radiotoxicité induite par les CCR6+Th17 sénescents. Enfin, le ratio de cellules circulantes H2A.J+CCR6+Th17 sénescentes / CCR6+Treg pourrait être utilisé comme marqueur potentiel de la radiosensibilité individuelle. / On average, 60% of cancer patients have at least one radiation session during their care throughout the history of their disease. The doses of radiotherapy are limited because of the high risk of fibrosis-type side effects of healthy tissues. Ionizing radiation can induce a variety of cell death responses including apoptosis, but also senescence. Senescent cells have reduced sensitivity to apoptosis, and a pro-inflammatory secretory phenotype. In addition, ionizing radiations can induce the production of reactive oxygen species (ROS) that cause DNA damage in non-target tissues, and systemic effects associated with inflammation. In order to improve the personalization of radiotherapy, different teams proposed predictive tests of the individual radiosensitivity of patients by establishing a relationship between a low rate of radio-induced apoptosis of CD4+/CD8+ T lymphocytes (LT) and a high risk of secondary fibrosis. However, the impact of the differences in individual cell sensitivity to radiation-induced senescence on the ratio between LT cell subpopulations has not been studied. Our results on healthy donors show that pro-fibrogenic CCR6+ Th17 cells are less sensitive to apoptosis and more susceptible to senescence compared to CCR6neg LT. This senescence can be detrimental as irradiated CCR6+Th17 lymphocytes located in the irradiated tissue can secrete IL-8 and VEGF-A. Modulation of ROS/MAPK or mTOR signaling pathways could be potential targets for the prevention of this CCR6+Th17-induced radiotoxicity. Finally, the ratio of circulating H2A.J+ senescent CCR6+ Th17/CCR6+Treg cells may be used as a potential marker of individual radiosensitivity.

Diss. (sammanfattning) Umeå : Umeå universitet, 2010.

Human γδ T cells expressing the Vγ2Vδ2 T cell antigen receptor play important roles in immune responses to microbial pathogens by monitoring prenyl pyrophosphate isoprenoid metabolites. Most adult Vγ2Vδ2 cells are memory cytotoxic cells that produce interferon-γ (IFN-γ). Recently, murine γδ T cells were found to be major sources of interleukin (IL)-17A in anti-microbial and autoimmune responses. To determine if primate γδ T cells play similar roles, we characterized IL-17A and IL-22 production by Vγ2Vδ2 T cells. IL-17A-producing memory Vγ2Vδ2 T cells exist at low but significant frequencies in adult humans (1:2,762 T cells) and at even higher frequencies in adult rhesus macaques. Higher levels of Vγ2Vδ2 T cells produce IL-22 (1:1,864 T cells) although few produce both IL-17A and IL-22. Unlike adult humans where many IL-17A+ V#947;2Vδ2 T cells also produce IFN-#947; (T#947;δ1/17), the majority of adult macaques IL-17A+ Vδ2 T cells (T#947;δ17) do not produce IFN-#947;. To define the cytokine requirements for T#947;δ17 cells, we stimulated human neonatal V#947;2Vδ2 T cells with the bacterial antigen, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate, and various cytokines and mAbs in vitro. We find that IL-6, IL-1β, and transforming growth factor-β (TGF-β) are required to generate T#947;δ17 cells in neonates whereas T#947;δ1/17 cells additionally required IL-23. In adults, memory T#947;δ1/17 and T#947;δ17 cells required IL-23, IL-1β, and TGF-β but not IL-6. IL-22-producing cells showed similar requirements. Both neonatal and adult IL-17A+ V#947;2Vδ2 T cells expressed elevated levels of retinoid-related orphan receptor-#947;t. Our data suggest that, like Th17 αβ T cells, V#947;2Vδ2 T cells can be polarized into T#947;δ17 and T#947;δ1/17 populations with distinct cytokine requirements for their initial polarization and later maintenance.

The peripheral naive CD4 T cell pool is homeostatically regulated through a balance of thymic production, delivery of survival signals and homeostatic proliferation. CD4 recent thymic emigrants (RTEs) have a high T cell receptor excision circle (TREC) content and express high levels of CD31. We report premature thymic involution in RRMS, initiated by reduced numbers of naive CD4 T cells and various naive CD4 T cell subsets in peripheral blood. Further, CXCR4, a receptor involved in emigration from the thymus, and CD127 and Bcl-2 (survival signals) are upregulated in various naive CD4 T cell subsets in RRMS. As a compensatory process, naive CD4 T cells undergo homeostatic proliferation. This proliferation is a form of peripheral positive selection through self-MHC/self-antigen interaction and thus can contribute to the expansion of autoreactive T cells and predispose to development of RRMS.

The immune system generates discrete lineages of cells that are designed to respond optimally to environmental cues and infectious agents. Two distinct lineages of T cells, distinguished by expression of either an αβ or γδ T cell receptor (TCR), arise from a common progenitor in the thymus. The type of pathogen and the cytokine milieu directs effector differentiation of αβ T cells in the periphery through the induction of specific transcriptional networks. γδ T cell development is distinct from that of αβ T cells in its ordered rearrangement of TCR genes and the pairing of Vγ and Vδ chains to generate γδ T cell subsets that home to specific tissues. Unlike conventional αβ T cells, γδ T cells express a preactivated or memory phenotype prior to pathogen encounter, and recent evidence indicates that effector functions may be programmed during thymic development. To better understand the development and function of γδ T cells, we analyzed the gene expression profiles of subsets of γδ T cells segregated by TCR repertoire and maturation state in the thymus. We also determined the impact of TCR signaling and trans-conditioning on γδ T cell subset-specific gene signatures by analysis of Itk-/- and Tcrb-/- γδ T cell subsets. Our analysis has defined three stages of γδ T cell subset-specific differentiation, and indicates that γδ T cells may consist of at least two separate lineages, distinguished by the expression of a Vγ2 or Vγ1.1 TCR, that arise from different precursors during thymic development. Key transcriptional networks are established in immature γδ T cells during the first phase of development, independent of TCR signaling and trans-conditioning, with Vγ2+ cells expressing modulators of WNT signaling, and Vγ1.1+ cells expressing high levels of inhibitor of DNA binding 3 (ID3), which regulates E2A/HEB proteins. The second stage involves the further specification of the Vγ2+ subset specific gene signature, which is dependent upon ITK-mediated signals. In the third stage, terminal maturation of γδ T cell subsets occurs, dependent on both TCR and trans-conditioning signals. The expression patterns of Vγ1.1+ subsets that differ in Vδ usage diverge, and all subsets further elaborate and reinforce their effector programming by the distinct expression of chemokine and cytokine receptors. Alteration of WNT signaling or E2A/HEB activity results in subset specific defects in effector programming, indicating that the transcriptional networks established at the immature stage are crucial for the functional maturation of γδ T cells. These data provide a new picture of γδ T cell development, regulated by multiple checkpoints that shape the acquisition of subset-specific molecular signatures and effector functions.

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