脂肪间充质干细胞外泌体调节巨噬细胞SIRT1/Notch信号途径在烧伤脓毒症中的作用及机制研究

Excessive activation of macrophages plays an important role in the development of sepsis. Recently, it has been reported that exosomes derived from mesenchymal stem cells (MSCs) can regulate macrophage polarization and function, but the specific regulation mechanism remains largely unknown. Our previous studies have confirmed that exosomes derived from adipose mesenchymal stem cells (ADMSCs) could significantly reduce the mortality of sepsis mice, upregulate SIRT1 expression, and inhibite Notch signaling pathway activation and proinflammatory effects of macrophages. Based on these findings, we hypothesize that in burn sepsis, ADMSCs exosomes would regulate the expression of SIRT1 and Notch signaling molecules in macrophages, and affect the polarization and function of macrophages through the interaction mechanism, and ultimately inhibit the occurrence and development of sepsis. In this project, we intend to study the following issues from animal, cell and molecule levels: 1 in burn sepsis, the regulatory effects of ADMSCs exosomes on the expression of SIRT1 and Notch signaling molecules; 2 the effects of ADMSCs exosomes on the polarization and function of macrophages; 3 the interaction mechanism of SIRT1 and Notch signaling molecules during the regulatory process of ADMSCs exosomes. The present study is expected to lay the theoretical foundation for improving uncontrolled inflammation and treating burn sepsis by utilizing ADMSCs exosomes.

巨噬细胞过度活化在脓毒症发生发展过程中扮演着重要角色。近期文献报道，间充质干细胞（MSCs）外泌体可调控巨噬细胞极化状态和功能，但其具体调控机制不清。课题组前期研究证实，脂肪间充质干细胞（ADMSCs）外泌体可显著降低脓毒症小鼠死亡率,上调SIRT1，并抑制Notch信号途径活化及巨噬细胞促炎作用。据此课题组提出假设：在烧伤脓毒症时，ADMSCs外泌体可调控巨噬细胞SIRT1/Notch途径相关分子表达，并通过交互调节机制影响巨噬细胞的极化状态和功能，最终抑制脓毒症的发生发展。本课题拟从动物、细胞和分子三个层面研究烧伤脓毒症发生时：1ADMSCs外泌体对SIRT1/Notch途径相关分子表达的调控作用；2其调控作用对巨噬细胞细胞极化状态和功能的影响；3在其调控过程中SIRT1/Notch途径的内在交互调节机制。从而为临床利用ADMSCs外泌体改善失控制性炎症，防治烧伤脓毒症奠定理论基础。

巨噬细胞过度活化在脓毒症发生发展过程中扮演着重要角色。文献报道间充质干细胞（MSCs）外泌体可调控巨噬细胞极化状态和功能，但其具体调控机制不清。课题组前期研究证实，脂肪间充质干细胞（ADMSCs）外泌体可显著降低脓毒症小鼠死亡率,上调SIRT1，并抑制Notch信号途径活化及巨噬细胞促炎作用。据此课题组提出假设：在烧伤脓毒症时，ADMSCs外泌体可调控巨噬细胞SIRT1/Notch途径相关分子表达，并通过交互调节机制影响巨噬细胞的极化状态和功能，最终抑制脓毒症的发生发展。本课题在前期研究的基础上，通过动物、细胞和分子实验研究证明：1. ADMSCs外泌体干预可显著减少脓毒症小鼠死亡率；2. ADMSCs外泌体干预可调控脓毒症小鼠心脏组织及脑组织中SIRT1及Notch通路相关分子的表达；3. ADMSCs外泌体依赖SIRT1调控小鼠胶质细胞活性减轻脑组织中氧化应激损伤并降低炎症反应强度；4. ADMSCs外泌体对SIRT1的作用与Notch通路NICD相关联，抑制SIRT1后NICD及其下游分子Hes1表达均增加。本课题初步证实了利用ADMSCs外泌体改善失控制性炎症，防治脓毒症的可行性，为临床治疗脓毒症提供了新的理论基础。