PIKfyve抑制剂Apilimod防治骨髓型急性放射病的机制研究

Despite great achievements has been made in prophylaxis and treatment of acute radiation sickness (ARS) in recent years, many problems still exist in this area. Based on the previous research findings and latest advance, we put forward the idea that the damage to the haematopoietic stem cells and haematopoietic microenvironment coexist in the pathogenesis of the acute radiation sickness, paying equal attention to the protection against radiation injury of haematopoietic stem cells and the mitigation of damage to haematopoietic microenvironment for the treatment of acute radiation sickness. In search of measures to alleviate radiation-induced microenvironment damage, the role of PIKfyve inhibitor Apilimod for prophylaxis and treatment of Bone Marrow form Acute Radiation Sickness (BM-ARS) was found. According to our preliminary work, it is suggested that PIKfyve may be the target of Apilimod for the treatment of BM-ARS. Hence, in this project, the therapeutic effect of Apilimod for the treatment of BM-ARS will be evaluated using various species of animal models, including mice and monkeys. Chemical probes for PIKfyve, such as its inhibitors or inactive analogues, will be used to find the role of PIKfyve in the treatment of BM-ARS with Apilimod. It will be thoroughly investigated that the mechanism of Apilimod in regulating hematopoietic function reconstruction. It will be further examined that the role of PIKfyve-regulated immunogical and inflammatory responses in the the pathogenesis of the BM-ARS. Total these findings will reveal the mechanisms of Apilimod for the prophylaxis and treatment of BM-ARS. Theoretical basis will be eventually provided for the study of novel therapeutic schedules and strategies against BM-ARS.

急性放射病(ARS)防治研究近年来虽取得一定成果，但仍然存在较多问题。本课题提出“造血干细胞与造血微环境损伤在ARS发病中并存，在救治上并重”的理念；并在该理念的指导下首次发现了PIKfyve抑制剂Apilimod对骨髓型急性放射病（BM-ARS）的防治作用。前期工作提示，PIKfyve可能是Apilimod防治BM-ARS的药靶。据此，本课题拟应用小鼠、猕猴等多种动物模型评价Apilimod防治BM-ARS的疗效；应用靶向PIKfyve的活性化学小分子探针及其无活性结构类似物，对比研究其防治BM-ARS的疗效，发现Apilimod防治BM-ARS的作用靶点；深入研究Apilimod调节放射损伤后造血功能重建的机制，并探讨受PIKfyve调节的免疫和炎症反应在BM-ARS发生中的作用，最终揭示Apilimod防治BM-ARS的作用机制，为BM-ARS防治新措施和新策略研究提供理论依据。

前期工作中，我们首次发现了PIKfyve抑制剂Apilimod对骨髓型急性放射病（BM-ARS）的防治作用。据此，本课题应用致死剂量和亚致死剂量照射小鼠模型系统研究了Apilimod防治骨髓型急性放射病（BM-ARS）的疗效、作用靶点和作用机制。.研究结果表明，Apilimod单次预防给药即显示出明显的辐射防护作用，照前3h腹腔注射Apilimod 40mg/kg将致死剂量9.0Gyγ射线全身照射小鼠存活率提高100%，Apilimod的剂量减低系数DRF值为1.21。研究证明PIKfyve抑制剂YM201636、APY0201和结构类似物API09对BM-ARS均有一定程度的防治作用，提示PIKfyve可能是BM-ARS防治新靶点。作用机制研究发现，Apilimod可减轻6.5Gy γ射线全身照射小鼠的造血损伤，并能促进白细胞、红细胞和血小板等多系造血细胞恢复。Apilimod能够明显改善放射引起的骨髓组织破坏，增加骨髓腔造血实质细胞数量。Apilimod不仅能够显著增加受照小鼠骨髓中造血干祖细胞的数量，还能改善放射引起的造血干细胞重建造血能力下降。Apilimod能够刺激内源性细胞因子G-CSF和IL-6的生成，诱导内源性G-CSF生成是Apilimod发挥保护造血干细胞，促进放射损伤造血功能重建，防治骨髓型急性放射病的关键作用机制。以上研究结果不仅为急性放射病防治提供了候选药物(Apilimod等PIKfyve调节剂及其结构类似物)，还为BM-ARS防治新措施和新策略研究提供了理论依据。