Upon activation, T cells shift towards a metabolic program characterized by increased glucose metabolism in order to sustain proliferation and effector function. Surprisingly, while resting T lymphocytes degrade glucose aerobically to CO2, proliferating T cells metabolize glucose almostentirely to lactate in the presence of oxygen through aerobic glycolysis (the Warburg effect). This metabolic switch comprises the upregulation of glycolytic enzymes and glucose transporters to the cell membrane, leading to an increase of glycolytic flux and the concomitant production of lactate. Despite many decades of research, we still do not fully understand the mechanisms that make proliferating T cells choose glycolysis rather than oxidation of glucose to produce energy. Since activated T lymphocytes depend on a glycolytic metabolism, they must release lactate, which inthese cells is facilitated by the proton-linked monocarboxylate transporter MCT1. The transporter is part of a protein family of 14 members among which MCT1–4 facilitate the passive transmembrane transport of monocarboxylates such as lactate, pyruvate and ketone bodies. The observation that pharmacological MCT1 inhibition has shown anti-proliferative effect on T cells suggests that lactate transport is essential to T cell expansion triggered after antigen recognition. The aim of our research is to investigate the importance of MCT1-dependent regulation in T cellmetabolism. Following TCR stimulation, MCT1 was expressed early in T cells unlike MCT4 whose significant expression was detected at later time point. To investigate the role played by MCT1 in the early steps of T cell activation, we generated a transgenic mouse model where conditional deletion of the MCT1 gene was achieved specifically in T cells. Phenotype and T cell distribution in thymus and peripheral organs were normal in MCT1fl/fl CD4Cre mice. However, lack of MCT1 expression decreased the proliferative capacity of in vitro activated CD4+ or CD8+ T cells without altering their viability. We observed that the IL-2 production was also affected by the lack of MCT1 expression, in line with decreased proliferative ability. Moreover, in vivo, T cell expansion that followed antigenic stimulation as well as T cell-mediated immune response to infection were deficient in MCT1fl/flCD4Cre mice. Our data indicate that this situation resulted from a cellular energy shortage caused by reduced glycolytic activity soon after activation. Moreover, energy crisis was amplified by the necessity to use ATP-consuming mechanisms for excluding H+ protons from the cytosol of activated MCT1-deficient T cells. Thus, in T cells, early MCT1 expression after activation ensures an energy saving mechanism for regulating cytoplasm acidification. Our observations also indicate that a high glycolytic flux is required in dividing T cells to maintain pH homeostasis. / Doctorat en Sciences biomédicales et pharmaceutiques (Médecine) / info:eu-repo/semantics/nonPublished

京都大学 / 新制・課程博士 / 博士(医科学) / 甲第23609号 / 医科博第132号 / 新制||医科||9(附属図書館) / 京都大学大学院医学研究科医科学専攻 / (主査)教授 濵﨑 洋子, 教授 森信 暁雄, 教授 上野 英樹 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Immune-brain-endocrine communication influences behaviour and contributes to the development of the central nervous system (CNS) in a sexually dimorphic manner. The bed nucleus of the stria terminalis (BST) is a highly sexually dimorphic brain region; in most mammalian species the male BST is larger than the female BST. Previously, our lab has shown that male and female mice lacking T cells due to knock out of the beta (b) and delta (d) chains of the T cell receptor (TCRb-/-d-/-) have reduced anxiety-like behaviour. This was shown with increased time spent in the open arms of the elevated plus maze by TCRb-/-d-/- mice compared to wild type (WT) mice of both sexes. T cell deficient mice also show differences in brain volume compared to WT, including a lack of sexual dimorphism in volume of the BST. The present study explored the impact of T cell deficiency on immune and endocrine factors implicated in sex differences of the CNS. The first analysis was of serum Anti-Müllerian hormone (AMH). AMH is a key determinant of the male phenotype during fetal development. It has also been shown by others to contribute to sexual dimorphic development of the BST. Our postnatal analysis of serum AMH using ELISA demonstrated an age and genotype effect, where a peak in serum AMH levels in WT mice of both sexes was absent in both male and female TCRb-/-d-/- mice at postnatal day (P) 7. These results suggest that T cells have an impact on the endocrine system in early life but the process does not appear to be sexually dimorphic. The present study also explored the impact of TCR knockout on microglia, the resident immune cells of the brain. Other have shown microglia contribute to sexual dimorphic brain development. This contribution occurs through interaction with endocrine factors, making them a key player in the immune-brain-endocrine crosstalk. Using immunohistochemistry and the microglial marker, anti-Iba1, microglia were examined in adult and P7 WT and TCRb-/-d-/ mice. To quantify microglia, soma were traced using AxioVision microscope software, and microglia cell number, perimeter, radius, feret ratio, and area in dorsal and ventral BST were assessed. Our results show sex differences in microglia number in dorsal BST in adult WT mice, where female WT mice had a lower number of microglia compared to WT males, however this difference was absent in TCRb-/-d-/- adult mice. There were no effects on microglia number in the ventral BST and morphology analysis did not reveal any effects in the dorsal or ventral BST. Furthermore, the difference in microglia number was absent in all groups of P7 mice and analysis of soma morphology did not reveal any significant effects. This study explored the impact of TCR knockout on the BST by exploring the immune and endocrine factors shown to contribute to its sexual dimorphic development. The results suggest a non-dimorphic impact on the endocrine system in the postnatal period and a dimorphic impact on microglia that is age and region-specific. The findings reveal a complex network emphasizing the importance of a systems-wide approach to the study of sex differences in the CNS. / Thesis / Master of Science (MSc)

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Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 106-125).

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 89-102).