紫草素羟丙基-β-环糊精包合物对allo-HSCT后aGVHD的预防作用及机制研究

Acute graft-versus-host disease (aGVHD) is one of the leading causes of death for patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Prevention is the key point for successful management of aGVHD. Although there are a series of drug-based and immune cell-based tactics for preventing aGVHD post allo-HSCT, many problems still exist. Therefore, new aGVHD prevention strategies are urgently needed to further improve the prognoses of patients after allo-HSCT. In our previous experiments in vivo and in vitro, we found that shikonin not only could inhibit the immune responses of T cells, but also may induce immune tolerance (preserve regulatory T cells and expand myeloid-derived suppressor cells). Our previous experiment also indicated that shikonin hydroxypropyl-β-cyclodextrin (SHK/HD-β-CD) inclusion complex (intravenous injection of SHK) could inhibit the occurrence of aGVHD (prolong the survival of recipient mice, and block aGVHD-related target organ damage). In this project, MHC mismatched and haplo-identical allo-HSCT mouse models will be established to identify the best dose of SHK/HD-β-CD inclusion complex for aGVHD prevention. The influence of SHK/HD-β-CD inclusion complex on engraftment and graft-versus-leukemia effect will be evaluated. Finally, the underlying mechanisms will be explored. The results of this study may offer new strategy for aGVHD prevention after allo-HSCT.

急性移植物抗宿主病（aGVHD）是异基因造血干细胞移植（allo-HSCT）患者的主要死亡原因之一，预防是成功管理aGVHD的关键所在。尽管有多种药物及细胞用于aGVHD的预防，但仍然存在诸多问题，临床迫切需求新的aGVHD预防策略以进一步改善患者预后。申请人前期体内外研究表明紫草素（SHK）不仅可抑制T细胞免疫应答，而且具有诱导免疫耐受可能（保留调节性T细胞、扩增髓源抑制性细胞）。预实验发现SHK羟丙基-β-环糊精（SHK/HP-β-CD）包合物（静脉给药剂型）可抑制allo-HSCT后aGVHD发生：延长受体小鼠生存期、抑制aGVHD相关靶器官损伤。本课题拟通过构建小鼠MHC错配与半相合allo-HSCT模型，研究SHK/HP-β-CD包合物预防aGVHD的最佳剂量及其对移植后供体细胞植入与GVL效应的影响。最后将探索其细胞分子机制。本项目研究结果可能为aGVHD的预防提供新的思路。

异基因造血干细胞移植（allo-HSCT）是目前唯一有望彻底治愈某些恶性血液病的治疗手段。然而，急性移植物抗宿主病（aGVHD）与复发是限制移植成功的瓶颈所在。本项目旨在研究预防aGVHD与复发的新策略。课题组发现紫草素（SHK）可显著抑制allo-HSCT后aGVHD、延长小鼠存活期、改善aGVHD靶器官损伤；机制涉及抑制T细胞免疫应答及效应T细胞的生成；嵌合体研究发现SHK可明显影响供体细胞的植入。因而，SHK可能并不是理想的aGVHD预防药物。课题组进而关注SHK作为实体器官移植的免疫抑制剂。结果发现SHK可删除快速增殖的T细胞，可促进髓系细胞及免疫抑制细胞扩增；SHK可抑制同种异基因皮肤移植免疫排异反应，其机制可能与扩增髓源抑制性细胞有关。课题组研究了淫阳藿苷（ICA）对移植后aGVHD的预防作用及机制。结果发现ICA（100 mg/kg及以上）可显著抑制免疫应答、延长小鼠生存期、降低aGVHD临床评分及靶器官损伤；机制研究发现ICA可明显降低受体小鼠脾脏中CD4/CD8细胞比例，抑制初始T细胞向效应T细胞转变。此外，ICA不会影响移植物抗白血病（GVL）效应与供体造血细胞的植入。移植后骨髓微环境的保护作用是白血病复发的根源所在，而CXCR4信号是白血病细胞向骨髓归巢及定植的关键所在。课题组通过患者来源疾病动物模型及小鼠allo-HSCT模型证实，阻断CXCR4可明显增强GVL效应，且对GVHD病程无明显影响；移植后短时间阻断CXCR4可促进供体造血细胞的植入。综上，本课题研究结果揭示紫草素与淫羊藿苷可作为实体器官移植与allo-HSCT后预防排异的潜在药物。此外，阻断CXCR4增强GVL效应研究目前正在准备开展临床试验，结果可能为移植后复发干预提供新的治疗手段，甚至有望彻底清除残留白血病细胞，进一步改善allo-HSCT治疗白血病的整体疗效。