DISARMing the immunological barriers to regeneration in mammals

项目总结/摘要 这项工作的长期目标是促进受损人体组织的忠实再生。再生 在成年哺乳动物中是非常有限的;大多数主要器官中受损的组织无法再生， 进行疤痕修复成人再生能力的缺乏是医疗保健的巨大负担 制度和社会作为一个整体。虽然人类和老鼠的指尖都能经历真正的再生， 由于这种再生反应，这种再生在位置上局限于末端远端指骨。重要的是，截肢 轴点低于末端远节指骨或太靠近甲床导致再生失败。 值得注意的是，蝾螈的四肢具有与人类四肢相似的解剖结构，但独特的是， 在整个成年生活中从任何位置截肢。限制成体再生的生物学机制 对哺乳动物了解甚少。虽然免疫系统是伤口修复的强大调节器，但确切的 免疫细胞网络作为再生成功的决定因素的作用一直没有得到充分的研究。在我们 再生研究，包括这里提出的，我们使用小鼠指尖模型，检查再生 在不同的手指位置切除组织后。这是一个强大的模型，因为再生可以测量 采用高分辨率微型计算机断层扫描3D成像（骨/软组织体积）进行非侵入性检查，以及 用组织学和分子分析进行了全面分析。我们鉴定了几种淋巴免疫细胞 通过对祖细胞的细胞毒性活性抑制小鼠趾尖再生的类型，并表明T- 调节细胞（TCFs）在保护祖细胞免受这些细胞的影响中起关键作用。我们还发现， 由于缺乏淋巴免疫，新的再生被诱导，提供了新的模型来识别促再生 细胞和分子途径，可以利用治疗。重要的是，我们还发现了几个 支持再生的淋巴细胞类型，这表明有可能在治疗上增强人类修复 通过靶向免疫调节。该项目旨在确定和描述 淋巴样细胞调节成体再生。具体而言，我们将：目的1：解剖和表征淋巴细胞 抑制再生的机制。我们将使用一系列具有细胞毒性功能突变的小鼠品系， 离体和体内分析。目的2：明确促再生Treg抑制淋巴细胞增殖的机制 在体内使用Treg特异性缺失功能基因的细胞毒性。目标3：检验目标是否为 解除淋巴细胞的武装可以增强体内再生。我们将在体外测试致耐受性分子 细胞毒性测定，然后评价直接转基因和病毒的体内致耐受性抗原过表达 方法，然后通过修改的Treg递送策略。该项目将融合发育生物学和 免疫学方法，以确定关键的生物学途径和遗传修饰所需的短暂 免疫调节策略旨在诱导哺乳动物成体组织中的潜在再生潜力。这 这项工作将为旨在增强人类患者组织修复的翻译研究奠定基础。

PROJECT SUMMARY/ABSTRACT The long-term goal of this work is to facilitate the faithful regeneration of damaged human tissues. Regeneration in adult mammals is extremely limited; damaged tissue in most major organs fails to regenerate, and instead undergoes scar-based repair. The lack of adult regenerative capacity is an enormous burden on the healthcare system and society as a whole. Although both human and mouse digit tips can undergo a true regenerative response, this regeneration is positionally restricted to the terminal distal phalanx bone. Importantly, amputations with an axis point below the terminal distal phalanx bone or too close to the nail bed result in regeneration failure. Notably, salamander limbs have an anatomy similar to that of human limbs, but uniquely regenerate after amputation from any position throughout adult life. The biological mechanisms limiting regeneration in adult mammals is poorly understood. Although the immune system is a powerful regulator of wound repair, the exact role of immune-cell networks as a determinant of regenerative success has been grossly understudied. In our regeneration studies, including those proposed here, we use the mouse digit-tip model, examining regeneration following tissue removal at different digit locations. This is a powerful model, as regeneration can be measured non-invasively with high-resolution micro-computed tomography 3D-imaging (bone/soft tissue volume), and analyzed comprehensively using histology and molecular analysis. We identified several lymphoid immune-cell types that inhibit mouse digit-tip regeneration via cytotoxic activity against progenitor cells and showed that T- regulatory cells (Tregs) play a critical role in protecting progenitors from these cells. We also found that in mice lacking lymphoid immunity, novel regeneration is induced, providing new models to identify pro-regenerative cells and molecular pathways that can be exploited therapeutically. Importantly, we also identified several lymphoid-cell types that support regeneration, suggesting the potential to therapeutically enhance human repair through targeted immunomodulation. This project aims to identify and characterize the mechanisms by which lymphoid cells regulate adult regeneration. Specifically, we will: Aim 1: Dissect and characterize lymphoid-cell mechanisms inhibiting regeneration. We will use a range of mouse strains with mutations in cytotoxic function in ex vivo and in vivo analyses. Aim 2: Define mechanisms of pro-regenerative Treg suppression of lymphoid-cell cytotoxicity using Treg-specific deletion of functional genes in vivo. Aim 3: Test the hypothesis that targeted disarming of lymphoid cells could enhance regeneration in vivo. We will test tolerogenic molecules in ex vivo cytotoxicity assays and then evaluate tolerogenic antigen overexpression in vivo both direct transgenic and viral approaches and then via a modified Treg delivery strategy. This project will fuse developmental biology and immunological methods to identify the critical biological pathways and genetic modifiers required for transient immunomodulation strategies directed at inducing latent regenerative potential in adult tissues in mammals. This work will lay the groundwork for translation studies aimed at enhancing tissue repair in human patients.