REGULATORY T CELLS, MIXED CHIMERISM: A NOVEL TRANSPLANT STRATEGY FOR THALASSEMIAS

拟议研究的长期目标是确定调节性T细胞在保护中的作用 全淋巴照射/抗胸腺细胞血清宿主抗移植物抗宿主病(GVHD) 条件化(TLI/ATS)--成功的人类非清髓性骨移植方案的小鼠模型 骨髓移植(BMT)，并应用这一策略治疗地中海贫血。这项工作提出了 为了进一步阐明与供体调节性CD4+CD25+T细胞(CD4+CD25High)产生有关的因素 TLI/ATS后)，并确定TLI/ATS是否可被考虑用于治疗地中海贫血。这 这一建议源于TLI/ATS处理的宿主具有主要组织相容(MHC)- 不相合的骨髓移植可以预防致死性GVHD，而TLI/ATS治疗的NK T细胞缺陷和IL-4- 缺陷宿主会发展成致命性移植物抗宿主病，而来自CD4缺陷、IL-4缺陷和IL-10缺陷骨髓移植 对野生型TLI/ATS治疗宿主的捐赠者也会导致致命性GVHD。在调查这件事时，我们确定 野生型TLI/ATS处理的宿主骨髓移植后供者CD4+CD25High Tregs显著增加，丢失 在NK T细胞缺陷的宿主中进行骨髓移植，并通过过继转移NK T细胞到NK T部分恢复 缺乏细胞的宿主。这一建议的假设是：1)宿主调节性NK T细胞介导GVHD 通过分泌IL-4进行保护，2)宿主NK T细胞允许维持和/或扩大供者 3)TLI/ATS宿主治疗和异基因骨髓移植可以纠正 在人类(3-地中海贫血)小鼠模型中，无GVHD的地中海贫血表型。使用收养转移 在野生型和基因敲除小鼠中进行纯化的NK T细胞和MHC不匹配的小鼠移植，我们的特异性 目的：1)确定宿主NK T细胞IL-4分泌在抑制供者T细胞增殖中的作用 骨髓移植后，2)确定负责GVHD保护的特异性供者CD_4~+T细胞群(S)， 以及这些细胞是否是调节性的CD4+T细胞，3)决定宿主NK T细胞在产生 供体调节性CD4+T细胞，以及4)确定地中海贫血小鼠TLI/ATS后的BMT是否可以 稳定的供者植入，无需移植物抗宿主病，从而纠正地中海贫血表型。建议数 这项工作将为骨髓后供者T细胞反应的调节提供实质性的见解 移植，并将有助于确定先天(NK T)细胞和适应性之间的关键相互作用 (CD4*CD25h‘9h)免疫调节细胞。这可能为免疫调节提供新的策略。 用于治疗感染、自身免疫或癌症，以及用于血液疾病的移植。

The long-range objectives of the proposed study are to determine the role of regulatory T cells in protection against graft-versus-host disease (GVHD) in total lymphoid irradiation/anti-thymocyte serum host conditioning (TLI/ATS), the murine model of a successful human protocol for non-myeloablative bone marrow transplantation (BMT), and to apply this strategy for treatment of thalassemia. This work proposes to further elucidate factors involved in the generation of donor regulatory CD4+CD25+ T cells (CD4+CD25high Tregs) after TLI/ATS, and to determine whether TLI/ATS can be considered to treat thalassemias. This proposal stems from the finding that TLI/ATS-treated hosts given major histocompatibility (MHC)- mismatched BMT are protected from lethal GVHD, whereas TLI/ATS treated NK T cell-deficient and IL-4- deficient hosts develop lethal GVHD, and that BMT from CD4-deficient, IL-4 deficient, and IL-10-deficient donors to wild-type TLI/ATS treated hosts also results in lethal GVHD. In investigating this, we determined that donor CD4+CD25high Tregs are significantly increased after BMT in wild-type TLI/ATS-treated hosts, lost after BMT in NK T cell-deficient hosts, and partially regained upon adoptive transfer of NK T cells to NK T cell-deficient hosts. The hypotheses of this proposal are that: 1) Host regulatory NK T cells mediate GVHD protection via their secretion of IL-4, 2) Host NK T cells allow the maintenance and/or expansion of donor CD4+CD25high Tregs, and 3) TLI/ATS host treatment and allogeneic BMT can allow correction of the thalassemic phenotype without GVHD, in a mouse model of human (3-thalassemia. Using adoptive transfers of purified NK T cells and MHC-mismatched mouse transplants in wild-type and knockout mice, our specific aims are to: 1) Determine the role of host NK T cell IL-4 secretion in inhibition of donor T cell expansion following BMT, 2) Determine the specific donor CD4+ T cell population(s) responsible for GVHD protection, and whether these are regulatory CD4+ T cells, 3) Determine the role of host NK T cells in the generation of donor regulatory CD4+ T cells, and 4) Determine whether BMT after TLI/ATS in thalassemic mice can allow stable donor engraftment without GVHD, and thereby correct the thalassemic phenotype. The proposed work will provide substantial insights into the regulation of donor T cell responses after bone marrow transplantation, and will help define key interactions between innate (NK T) cells and adaptive (CD4*CD25h'9h) immune regulatory cells. This could provide new strategies for the modulation of immune function in treatment of infections, auto-immunity, or cancer, and in transplantation for blood diseases.