基于序贯递药体系实现对非酒精性脂肪肝的高渗给药和长效治疗

To construction of an effective drug delivery system for NAFLD, there are two challenges needs to be overcome: 1) the accumulation of extracellular matrix hinders the effective accumulation of drugs in target cells; 2) the high metabolism of drug in the liver inhibit the therapeutic effect. Basing on the interaction between CD47 and SIRPα expressed on macrophages can inhibit phagocytosis of macrophages, Our previous research found that modifying the Self peptide (CD47 function mimic peptide) on the surface of liposomes (SLip) can significantly reduce the phagocytosis and metabolism of SLip by macrophages and thus prolong the retention of SLip in liver. Based on this result, we proposed a new double-deck sequential drug delivery system, the SLip with different modification amounts of Self peptide is used as core, a hyaluronan (HA) shell containing metal matrix protease 1 (MMP 1) was constructed on the outer layer. After enters the liver, the HA shell will be degraded by reactive oxygen species (ROS) in the liver of NAFLD and MMP1 will be released to liver and clear the over-accumulated extracellular matrix, and then the SLip can be successfully targeted to liver macrophages. After Self peptide degraded by protein enzyme, SLip will gradually be endocytosed by liver macrophages, thereby achieving long-term treatment of NAFLD. This project will provide new ideas for the application of the sequential drug delivery system in the treatment of liver diseases, and provide a new direction and experimental basis for the development of safe and long-acting NAFLD treatment drugs.

针对非酒精性脂肪肝（NAFLD）的药物递送主要面临两个挑战：1）沉积的胞外基质阻碍了药物在靶细胞的有效蓄积；2）肝脏的高代谢速率抑制了药效的发挥。申请人前期研究发现：基于CD47和表达于巨噬细胞上的SIRPα互作可抑制巨噬细胞的吞噬作用，将CD47功能模拟肽—Self肽修饰在脂质体表面后（SLip），可显著降低巨噬细胞对SLip的内吞实现其在肝脏的长期滞留。以此为基础，申请人提出：制备不同Self肽修饰量的脂质体，并在外层构建含金属基质蛋白酶1（MMP1）的透明质酸（HA）外壳。其中，HA会被NAFLD肝中的活性氧降解并释放MMP1清除胞外沉积基质，而暴露的SLip则可与肝巨噬细胞作用，随着Self肽的降解，使SLip逐步被巨噬细胞内吞，实现对NAFLD的长效控释给药。本项目将为序贯给药体系在肝脏疾病治疗中的应用提供新的思路，为开发安全长效的NAFLD治疗药物提供新的方向和实验依据。

巨噬细胞是非酒精性脂肪肝(NAFLD)等慢性代谢性疾病的重要治疗靶标。然而，基于巨噬细胞的高吞噬代谢速率，对其的持续性药效受到限制。传统聚乙二醇表面修饰策略在延长了纳米药物体内循环的时间的同时也抑制了其和靶细胞的亲和力。CD47和巨噬细胞表面的SIRPα互做后可引发“别吃我”信号抑制巨噬细胞的吞噬作用。有基于此，本项目提出将普通脂质体（Lip）及CD47衍生的Self修饰的脂质体（SLip）按不同比例混合实现对巨噬细胞递送速率的调控，并进而优化体内的治疗效果。本项目取得主要进展如下：1）“别吃我”信号会基于血小板反应蛋白-1对Self肽的竞争结合在M1及M2型巨噬细胞实现不同的选择；2）Lip/SLip混合比例的改变可以显著影响巨噬细胞内吞脂质体的速率，并增强脂质体溶酶体逃逸；3）以水飞蓟宾为模型药物，并在脂质体表面吸附1型胶原酶，在Lip/SLip比例为1:1时，可更好的抑制脂多糖诱导的M1型巨噬细胞极化，以高脂饲料喂养的Lep ob/ob小鼠为模型，Lip/SLip（1:1）更显著的抑制了肝脂肪化病变。本项目的设计实现了在长效递药及靶向亲和力两方面的平衡，为开发安全长效的NAFLD治疗药物提供的新的方向和实验依据。通过本课题的研究，在国际著名学术期刊ACS Nano发表了高水平研究型论文一篇，申请了发明专利2项，参加了药物递送相关著名会议两次，待发表SCI论文一篇。圆满完成项目目标。