Novel Gene Therapy for Restoration of Aged Thymopoiesis

描述(申请人提供)：随着年龄的增长，哺乳动物的胸腺经历退缩，逐渐丧失结构完整性和淋巴细胞，导致T淋巴细胞生成减少。胸腺退化经常与免疫缺陷状态有关，如活动性艾滋病毒感染，或严重营养不良以及高龄。免疫恢复似乎需要恢复正常的胸腺生成。虽然已知有许多方法可以增加T细胞的整体分化，但针对胸腺而对外周免疫系统没有影响的治疗方法一直很少。我们的目标是开发一种针对胸腺的定制基因治疗递送系统，可用于减缓或逆转胸腺退化过程。胸腺内T细胞的发育需要发育中的淋巴样细胞和胸腺基质之间的双向相互作用。T细胞前体细胞从血液进入胸腺髓质，通过皮质和髓质进行定向迁移，从独特的胸腺内基质微环境中接收关键的分化信号。随着年龄的增长，胸腺的结构和细胞成分会发生变化，基质基因的表达也会发生变化。胸腺上皮基质将成为我们基因治疗方法的靶点。第一个具体目标是基于我们实验室开发的新方法优化基因治疗递送系统：胸腺内注射整合到胸腺结构中的工程细胞系，并在局部表达感兴趣的基因产物。将对几种细胞系和启动子进行最有效的载体构建测试，目标是开发一种整合到胸腺结构中的细胞递送载体，在较长的时间内产生高水平的治疗性蛋白，并且不会以其他方式干扰胸腺结构或T细胞的发育。第二个特定目的是使用这种基因传递方法来靶向老化的胸腺上皮。植入的细胞将被改造成表达形态因子WNT4或角质细胞生长因子，这两种蛋白质都会影响基质细胞的功能。这些研究将确定胸腺上皮功能是否可以通过这两种蛋白质中的任何一种的局部增加而增强，从而防止或逆转退化过程。这种递送系统可以用来评估任何数量的其他治疗性蛋白质的潜力，以实现增加胸腺T细胞输出的最终目标，从而改善老年人的免疫功能。

DESCRIPTION (provided by applicant): With advancing age the mammalian thymus undergoes involution, a progressive loss of architectural integrity and lymphoid cellularity, that results in reduced T lymphopoiesis. Thymic involution is frequently associated with states of immune deficiency, such as active HIV infection, or severe malnutrition as well as advanced age. Immune recovery appears to require restoration of normal thymopoiesis. While a number of means are known to increase overall T cell differentiation, there has been a paucity of treatments that target the thymus while having no effect on the peripheral immune system. Our goal here is to develop a customized gene therapy delivery system targeting the thymus that can be employed to slow or reverse the thymic involution process. Intrathymic T cell development requires mutual, two-way interactions between developing lymphoid cell and the thymic stroma. T cell progenitors enter the thymic medulla from the blood and undergo directed migration through the cortex and the medulla, receiving key differentiative cues from unique intrathymic stromal microenvironments. With advancing age the thymic architecture and cellular composition change, as does stromal gene expression. The thymic epithelial stroma will be the target of our gene therapy approach. The first specific aim is to optimize a gene therapy delivery system based on the novel approach developed in our lab: intrathymic injection of engineered cell lines that integrate into the thymic structure and express the gene product of interest locally. Several cell lines and promoters will be tested for the most effective vector construction, with the goal of developing a cell delivery vehicle that integrates into the thymic architecture, produces high levels of the therapeutic protein over an extended period and does not otherwise disrupt thymic structure or T cell development. The second specific aim will use this gene delivery method to target the aged thymic epithelium. Implanted cells will be engineered to express either the morphogen Wnt4 or keratinocyte growth factor, both proteins that affect stromal cell function. These studies will determine whether thymic epithelial function can be enhanced by a local increase in either of these proteins and thereby prevent or reverse the involution process. This delivery system can be employed to assess the potential of any number of other therapeutic proteins, to achieve the ultimate goal of increasing thymic T cell output and thereby improving immune function in the elderly.