DISARMing the immunological barriers to regeneration in mammals

项目摘要/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极其有限的；大多数主要器官中的受损组织不能再生，而是 接受基于疤痕的修复。成人再生能力的缺乏是医疗保健的一个巨大负担 制度和社会作为一个整体。尽管人类和老鼠的指尖都可以经历真正的再生 反应时，这种再生仅限于末端远端指骨。重要的是，截肢 如果轴心点在末端远端指骨下方或太靠近甲床，则会导致再生失败。 值得注意的是，火蜥蜴的四肢具有与人类四肢相似的解剖结构，但在 在成年后从任何位置截肢。限制成人再生的生物学机制 人们对哺乳动物知之甚少。尽管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被严重地研究不足。在我们的 再生研究，包括这里提出的那些，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之后。这是一个强大的模型，因为再生是可以测量的 无创的高分辨率微型计算机断层扫描3D成像(骨/软组织体积)，以及 采用组织学和分子分析方法进行综合分析。我们鉴定了几种淋巴免疫细胞 通过对祖细胞的细胞毒活性来抑制小鼠指尖再生的类型，并表明T- 调节性细胞(Treg)在保护祖细胞免受这些细胞伤害方面起着关键作用。我们还在老鼠身上发现了这一点 缺乏淋巴免疫，诱导了新的再生，为识别促再生提供了新的模型 可用于治疗的细胞和分子途径。重要的是，我们还确定了几个 支持再生的淋巴细胞类型，表明有可能在治疗上增强人类修复 通过靶向免疫调节。这个项目的目的是确定和描述通过哪些机制 淋巴样细胞调节成人的再生。具体来说，我们将：目标1：解剖和表征淋巴样细胞 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 体外和体内分析。目的2：确定淋巴细胞促再生Treg抑制的机制 利用Treg特异性缺失体内功能基因的细胞毒性。目标3：测试以下假设 解除淋巴样细胞的武装可以促进体内的再生。我们将在体外测试耐受分子 细胞毒性检测，然后评估体内直接转基因和病毒的耐受性抗原的过度表达 方法，然后通过改进的Treg交付策略。该项目将融合发育生物学和 确定瞬变所需关键生物学途径和遗传修饰物的免疫学方法 旨在诱导哺乳动物成体组织潜在再生潜能的免疫调节策略。这 这项工作将为旨在加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.