姜黄素对铁超载造血干祖细胞损伤的逆转作用及机制研究

Iron overload is quite common in hematology department patients due to long term repeated red cell transfusion and so on. Increasing clinical evidence has indicated that iron overload has a suppressive effect on hematopoiesis and that iron chelation therapy could improve this situation. Recently, there are many side effect to iron chelation therapy. The damage mechanism of iron overload is due to the elevate of labile intracellular iron pools(LIP) in the cells,free iron generates hydroxide anions and hydroxyl radicals from hydrogen peroxide which can lead to cellular damages. But this mechanism can not explain all the clinical symsptom. Reactive oxygen species generation can induce autophagy.Does autophagy participate in the iron overload damage? What is the change to the mitochondrial antioxidant mechanism? Will curcumin with definite efficacy of antioxidation reverse the damage of iron overload? Our previous research had confirmed that SOD2 activity decreased, the cell activity decreased and the level of autophagy increased in iron overload hematopoietic stem progenitor cell, and curcumin can partially restore SOD2 activity and cell activity, reduce the level of autophagy.we put forward a hypothesis that curcumin can reduce the production of mitochondrial ROS through the SIRT3-SOD2-mROS pathway, thereby reduce the level of autophagy, and therefore prevent and even reverse the damage of iron overload on hematopoietic stem progenitor cell.Iron overload CD34 + cells model and animal model and clinical specimens will be employed in our study to evaluate the of efficacy of curcumin on iron overload hematopoietic stem progenitor cell, so as to provide innovative ideas for the treatment of iron overload.

因长期反复输血等导致铁超载在血液科非常常见。临床研究发现，铁超载患者造血受到抑制，去铁治疗后造血明显恢复。而目前去铁治疗措施各有其弊端。目前认为可变铁池的铁催化产生氧自由基以及由此导致氧化损伤是铁超载引发疾病的发病机制。然而这并不能解释所有临床现象。ROS是自噬的诱导剂。自噬是否参与铁超载所致造血损伤？线粒体的抗氧化机制又是如何改变？具有明确抗氧化作用的姜黄素对铁超载所致的损伤能否逆转？前期研究发现铁超载的造血干祖细胞SOD2活性下降，细胞自噬水平升高，细胞活性下降，而姜黄素能提升SOD2活性，降低细胞自噬水平，部分恢复细胞活性。本研究假说认为姜黄素是通过SIRT3-SOD2-mROS信号通路，减少mROS的产生，从而降低自噬水平达到治疗铁超载所致造血损伤。我们采用CD34+铁超载细胞模型和铁超载小鼠模型以及铁超载临床标本，全面评估姜黄素治疗铁超载造血损伤，为铁超载的治疗提供了创新的思路。

铁超载在临床上非常常见，铁超载导致骨髓造血功能下降。然而铁超载是如何损伤造血细胞的机制仍不明确。且铁超载的治疗仍然是一个有待解决的难题。本课题在明确铁超载引起骨髓损伤的条件下，研究铁超载是如何损伤造血细胞，探讨抗氧化剂姜黄素是如何保护铁超载所致的骨髓损伤作用。我们通过建立铁超载细胞模型及动物模型，以及临床铁超载标本，检测铁超载的毒性效应及线粒体内氧化水平及SIRT3-SOD2-mROS信号调控轴的变化，予以姜黄素干预后，评估姜黄素的作用及可能的机制。结果我们发现铁超载骨髓造血细胞的活力及细胞增殖活性下降。随着铁剂量的增加，自噬蛋白LC3II表达进行性升高，自噬流增加，mROS进行性升高。加入了自噬抑制剂后，细胞活力好转。线粒体抗氧化剂作用后产生相似效果。随着铁剂量增加，SOD2的活性下降，SOD2乙酰化水平升高，SIRT3活性下降。通过SIRT3过表达，降低了SOD2的乙酰化，有效地减少mROS的生成，同时降低细胞自噬水平，细胞活力增加。以上结果在动物模型及临床标本中也得到验证。予以姜黄素干预后，细胞内mROS水平下降，部分恢复细胞活性，降低细胞自噬水平， SIRT3活性部分恢复， SOD2乙酰化水平降低。在动物模型中得到验证。因此我们认为铁超载引起mROS过量产生导致细胞自噬造成骨髓造血功能损伤。铁超载导致线粒体内SIRT3-SOD2-mROS功能紊乱，导致mROS过量产生。姜黄素通过SIRT3-SOD2信号通路减少mROS的产生，降低细胞自噬水平，恢复造血细胞活性。总之，这些发现为姜黄素和自噬信号之间的联系提供了新的见解，这有助于更好地理解姜黄素对铁超载所致骨髓损伤的保护作用。