Human Keratin (K14)-MBP/MBP-TCR Transgenic Animal Model

描述（由申请方提供）：胸腺在自身耐受性的建立中起核心作用。尽管在胸腺上皮细胞中观察到广泛的异质性，但异位移植来自E15.5胚胎的纯化的MTS 24 +MHCII+ CD 45-TEC显示，具有这种表型的细胞足以形成启动和维持常规胸腺生成的表型和功能正常的胸腺微环境。这表明MTS 24+胸腺上皮细胞包含能够产生完全功能的皮质和髓质胸腺上皮的胸腺内干细胞群。这一信息表明，移植MTS 24+胸腺上皮干细胞具有治疗潜力，诱导自身反应性T细胞和同种异体T细胞的免疫耐受。CD 4 + CD 25 + Foxp 3+调节性T细胞（Treg）被认为在抑制和预防自身免疫性疾病（包括多发性硬化症、类风湿性关节炎和1型糖尿病）中起关键作用。当它们的同源抗原在胸腺上皮细胞中表达时，CD 4 + CD 25 + Foxp 3 + T淋巴细胞发育。重要的是，活化的蛋白脂质蛋白特异性CD 4 + CD 25+调节性T细胞抑制由其他髓鞘抗原如髓鞘少突胶质细胞糖蛋白和髓鞘碱性蛋白诱导的EAE的发展。糖尿病相关抗原特异性调节性T细胞也比多克隆CD 4 + CD 25+调节性T细胞更有效地抑制糖尿病的发展。这一证据表明，与自身免疫性疾病相关的自身抗原反应的CD 4 + CD 25 + Foxp 3 + T细胞可以通过旁观者抑制在自身免疫性疾病中表现出有效的抑制。我们将开发一种新的策略，通过使用胸腺上皮干细胞开发自身免疫性疾病相关的自身抗原特异性CD 4 + CD 25 + Foxp 3 + T细胞。我们假设移植表达MBP转基因的胸腺上皮干细胞，然后移植同基因骨髓来源的造血干细胞，可以促进MBP特异性CD 4 + CD 25 + Foxp 3 + T细胞的发展，在重建的免疫系统中具有更高的抑制活性，并使实验性自身免疫性脑脊髓炎（EAE）易感小鼠对EAE产生抗性。为了解决这一假设，我们建议产生Tg小鼠，表达MBP基因的胸腺上皮细胞。我们将研究在MBP-Tg小鼠中MBP特异性Foxp 3 + T细胞的发育。 髓鞘碱性蛋白（MBP）是实验性自身免疫性脑脊髓炎（EAE）的一种自身抗原。我们将产生表达MBP的小鼠，并研究MBP基因在胸腺上皮细胞中的表达是否可以抑制EAE的发展。

DESCRIPTION (provided by applicant): The thymus plays a central role in the establishment of self-tolerance. Although broad heterogeneity is observed in thymic epithelial cells, heterotopic transplantation of purified MTS24+MHCII+CD45-TECs derived from E15.5 embryo showed that cells of this phenotype are sufficient to form a phenotypically and functionally normal thymic microenvironment that initiate and sustain regular thymopoiesis. This indicates that MTS24+ thymic epithelia cells encompass a population of intrathymic stem cells capable of giving rise to fully functional cortical and medullary thymic epithelium. This information suggests that grafting of MTS24+ thymic epithelial stem cells possesses therapeutic potentials to induce immune tolerance in autoreactive T cells and allogenic T cells. CD4+CD25+ Foxp3+regulatory T cells (Tregs) have been suggested to play a critical role in the suppression and prevention of autoimmune diseases including multiple sclerosis, rheumatoid arthritis and type 1 diabetes. CD4+CD25+Foxp3+ Tregs develop when their cognate antigens are expressed in the thymic epithelial cells. Importantly, activated proteolipid protein-specific CD4+CD25+ regulatory T cells suppress the development of EAE induced by other myelin antigens such as myelin oligodendrocyte glycoprotein and myelin basic protein. Diabetes-associated antigen-specific regulatory T cells also suppress the development of diabetes more efficiently than polyclonal CD4+CD25+ regulatory T cells. This evidence suggests that CD4+CD25+ Foxp3+Tregs reacting with autoimmune disease-associated autoantigens could exhibit efficient suppression in autoimmune diseases via bystander suppression. We will develop a novel strategy to develop autoimmune disease-associated autoantigen-specific CD4+CD25+ Foxp3+Tregs by using thymic epithelial stem cells. We hypothesize that grafting of thymic epithelial stem cells expressing the MBP transgene followed by transplantation of syngeneic bone marrow-derived hematopoieticstem cells could facilitate the development of MBP-specific CD4+CD25+ Foxp3+Tregs with higher suppressive activity in the reconstituted immune system and render Experimental Autoimmune Encephalomyelitis (EAE) -susceptible mice resistant to EAE. To address this hypothesis, we propose to generate Tg mice that express MBP gene in the thymic epithelial cells. We will investigate development of MBP-specific Foxp3+ Tregs in the MBP-Tg mice. Myelin basic protein (MBP) is an autoantigen involved in development of experimental autoimmune encephalomyelitis (EAE). We will generate the mice expressing the MBP and examine whether expression of MBP gene in the thymic epithelial cells can suppress the development of EAE.