The role of the chemokine receptos CCR4 and CCR7 in graft-versus-host disease

描述(申请人提供)：移植物抗宿主病(GVHD)是造血干细胞移植(HSCT)后发病率和死亡率的主要原因之一。GVHD是由供者T细胞介导的，供者T细胞识别受者MHC的微小或主要差异。最近，我们的实验室和其他研究小组发现，当输注同种异体效应T细胞时，CD4+CD25+调节性T细胞(Tregs)可以阻断组织损伤，提高存活率。Tregs在GVHD过程中抑制效应细胞功能的过程还不完全清楚。发生这种情况的关键部位尚不清楚，Treg迁移到淋巴组织的机制只有部分了解，Treg迁移到靶器官(如胃肠道)是否对缓解GVHD具有重要作用尚不清楚。该项目的主要目标将是研究趋化因子受体CCR4和CCR7在GVHD期间Treg细胞迁移中的作用。为了实现这一点，我们将使用CCR4和CCR7基因敲除小鼠广泛回交到C57BL/6背景上。我们将从基因敲除动物和野生型动物中分离出CD4+CD25+Tregs，并比较它们在移植到单倍体相合的受者体内时预防GVHD的能力。在CCR4的案例中，我们将专门但不只关注Treg迁移到皮肤和肠道在预防这些部位的并发症和提高总体受体存活率方面的作用。我们还将重点研究CCR7是移植时原始Treg迁移到受体淋巴结所必需的假设，以及这一关键步骤对于先前未受刺激的Treg保护GVHD致死性是必要的。为了评估Treg细胞的运输，我们将使用流式细胞术和我们的开创性工作，使用EGFP转基因野生型、CCR4-/-和CCR7-/-动物进行体内立体荧光显微镜检查。这项工作的目标是确定预防和治疗移植物抗宿主病的潜在目标。

DESCRIPTION (provided by applicant): Graft-versus-host disease (GVHD) is one of the major causes of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). GVHD is mediated by donor T-cells that recognize minor or major MHC disparities in the recipient. Recently, our laboratory and other groups have shown that CD4+CD25+regulatory T cells (Tregs) when infused with allogeneic effector T-cells can block tissue damage and improve survival. The process by which Tregs inhibit effector cell function during GVHD is incompletely understood. The critical site at which this occurs is not clear, the mechanisms by which Tregs migrate into lymphoid tissue is only partly understood, and whether Treg migration to target organs such as the gastrointestinal tract is important in mitigating GVHD has not been explored. The principal goal of this project will be to examine the role of the chemokine receptors CCR4 and CCR7 in the migration of Treg cells during GVHD. To accomplish this, we will use CCR4 and CCR7 knockout mice extensively backcrossed onto a C57BL/6 background. We will isolate CD4+CD25+ Tregs from knockout and wild-type animals, and compare their ability to protect against GVHD when transferred into haplo-identical recipients. In the case of CCR4, we will focus specifically but not exclusively on the role of Treg migration to the skin and gut in preventing complications at these sites and improving overall recipient survival. We will also focus on the hypothesis that CCR7 is required for naive Treg migration into recipient lymph nodes at the time of transplantation, and that this critical step is necessary for previously unstimulated Tregs to protect against GVHD lethality. To evaluate the trafficking of Treg cells we will use flow cytometry and our pioneering work with in-vivo stereofluorescence microscopy using eGFP transgenic wild type, CCR4 -/-, and CCR7-/- animals. The goal of this work is to identify potential targets for the prevention and treatment of GVHD.