Crosstalk Control of Thymic Epithelial Development

描述（由申请人提供）：胸腺上皮细胞（TEC）负责调节未成熟胸腺细胞发育为功能性自身耐受性成熟T细胞。一种常见的内胚层来源的TEC祖细胞最近被证明会产生皮质和髓质TEC亚群，然而，调节这一过程的信号传导途径和细胞间相互作用的定义很差。TEC的发育和组织依赖于从发育中的胸腺细胞通过上皮网络迁移时接收的串扰信号。本研究的目的是确定SP胸腺细胞/TEC相互作用的性质和功能，调节胸腺髓质的发育，胸腺微环境是至关重要的中央耐受性。通过将成熟T细胞过继转移到T细胞发育受阻的小鼠中诱导的髓质重建将用于测试特异性T细胞/TEC相互作用的贡献。 我们建议：（1）使用MHC I类/ MHC II类双KO小鼠来确定胸腺髓质的扩增和分化是否依赖于TCR/MHC相互作用，并鉴定在该过程中CD 4 SP、CD 8 SP和TCR的特异性贡献;（2）在新开发的Wnt信号转导报告小鼠品系中使用胎儿胸腺器官培养物和髓质重建测定，评估Wnt信号传导在mTEC发育中的作用，并确定SP胸腺细胞分泌的可溶性Wnt抑制分子是否抑制TEC中的经典Wnt信号传导途径，从而提供mTEC从前体细胞发育所必需的分子开关。充分理解有助于TEC发育和组织的信号通路和细胞相互作用对于设计合理的治疗策略以对抗与年龄相关的胸腺退化和与自身免疫相关的胸腺结构缺陷至关重要。这些策略还将通过抵消与包括化疗和放疗在内的准备性细胞消融治疗以及移植后GVHD相关的严重过早胸腺变性，显著影响骨髓移植用于癌症治疗的有效性。

DESCRIPTION (provided by applicant): The thymic epithelial cells (TECs) are responsible for regulating the development of immature thymocytes into functional self-tolerant mature T cells. A common endoderm-derived TEC progenitor was recently shown to give rise to both cortical and medullary TEC subsets, however, the signaling pathways and cell-to-cell interactions that regulate this process are poorly defined. TEC development and organization is dependent on crosstalk signals received from developing thymocytes as they migrate through the epithelial network. The goal of this study will be to define both the nature and function of the SP thymocyte/TEC interactions that regulate development of the thymic medulla, the thymic microenvironment that is critically responsible for central tolerance. The medullary reconstitution induced by adoptive transfer of mature T cells into mice with blocks in T cell development will be used to test the contribution of specific T cell/TEC interactions. We propose to: (1) use MHC class I / MHC class II double KO mice to determine if the expansion and differentiation of the thymic medulla is dependent on TCR/MHC interactions and identify the specific contributions of CD4 SP, CDS SP and Tregs, in this process; (2) use both fetal thymic organ cultures and medullary reconstitution assays in a newly developed Wnt signaling reporter mouse strain, to access the contribution of Wnt signaling in mTEC development and determine if soluble Wnt inhibitory molecules secreted by SP thymocytes inhibit the canonical Wnt signaling pathway in TECs, thereby providing a molecular switch that is necessary for mTEC development from precursor cells. Fully understanding the signaling pathways and cellular interactions which contribute to TEC development and organization will be critical to designing rational therapeutic strategies to counteract age-associated thymic involution and thymic architecture defects associated with autoimmunity. These strategies will also significantly impact the effectiveness of bone marrow transplantation for cancer treatment by counteracting the severe premature thymic degeneration associated with preparative cytoablative treatments including chemotherapy and radiation, as well as post-transplant GVHD.