基于代谢组学的碲化镉（CdTe）量子点对小胶质细胞神经毒性机制的研究

Quantum dots (QDs) are novel and effective nano-scale probes, which could be used in the field of biomedicine. It expects the demands will be more than 8.2 billion arriving in 2023. Although the toxicity of QDs has been gotten more and more attentions, the neurotoxicological study of QDs is relatively rare. The results from the previous program funded by NSFC showed that CdTe QDs exposure with a certain concentration could change the autonomic and special explosive behavior, and impair the learning and memory of animals by damaging their hippocampus. There were many signal pathways, especially the nuclear transcription factor NF-κB mediated inflammatory response pathway, in which the CdTe QDs were involved to causing these adverse effects. Therefore, this program would choose microglia, which play an important role on inflammation in the central nervous system, as the study subject and tried to investigate the neurotoxicity of CdTe QDs indicated by the animal behavior change and the injure of microglia structure and function in the whole animal and cell line levels. Meanwhile, the SMPDB would be used to comprehensively analyze the data from metabolomics and transcription sequence in order to screen key biomarkers relevant to neurotoxicity of CdTe QDs, which would be validated by BV-2 cells with a particular gene knockout or knockin. A model of predicting neurotoxicity of QDs would be built as well, which would guild the further safety application of QDs in biomedicine.

量子点是一种可用于生物医学领域的纳米级新型高效荧光探针，至2023年有82亿美元的市场需求；其生物毒性广受关注，但对其神经毒性的研究却相对较少。前一项基金的研究结果表明，碲化镉（CdTe）量子点可改变动物的自主和空间探索行为、损伤海马神经元从而影响学习记忆能力，并且其作用机制涉及多条信号通路，尤其是核转录因子NF-κB介导的炎症反应通路。因此，本课题选择中枢神经系统炎症反应中参与重要作用的小胶质细胞，从体内和体外的不同角度，通过活体动物行为改变、小胶质细胞结构和功能的损伤为观察值来反映CdTe量子点的神经毒性；结合分子生物学、代谢组学和转录组测序；通过小分子通路数据库（SMPDB）综合分析，筛选出量子点神经毒性相关的生物标志物，探讨量子点的毒作用机制；并通过目的基因沉默或过表达的小胶质细胞验证量子点毒作用参与的信号通路；建立量子点神经毒性预测模型，为其在生物医学的安全应用提供重要参考。

本课题从代谢组学的角度，探讨了CdTe量子点引起的海马体炎性反应及对中枢神经系统的毒性作用机制。实验证实，CdTe量子点可以透过血脑屏障，通过对大鼠海马体的高通量转录组测序数据的分析，比较2.2 nm和3.5 nm量子点的差异表达基因，筛选出的860个差异表达基因主要富集在与炎性反应相关的信号通路。CdTe量子点3 h可在颅内达到浓度峰值，并激活小胶质细胞向发挥促炎作用的M1型和发挥抑炎作用的M2型分化，mTOR通路在小胶质细胞的激活中发挥了重要作用。此外，CdTe量子点在体和离体小胶质细胞中均促使了炎性因子IL-1β的分泌，NLRP3炎性小体和NF-κB通路在其中发挥了关键的介导作用。运用GC-MS平台对CdTe/ZnS QDs时序染毒的BV2细胞进行代谢组学分析，发现在3 h、6 h、12 h均有代谢通路扰动的发生，其中有50种代谢物为3个时间点共有的差异代谢物，涉及11条通路，包括糖代谢、能量代谢、脂代谢、主动运输、氨基酸代谢和核酸代谢。用以上数据建立的量子点神经毒性的预测模型，可为量子点在生物医学的安全应用提供重要参考。