端粒酶激活调控单核巨噬细胞亚型的分化及其在动脉粥样硬化血管重塑中的作用机制

Atherosclerosis，highly correlated with cardiovascular disease mortality, is recognized as an age- associated inflammation. Telomere length and telomerase activity has emerged as a marker that represents biological aging which is the key to age-related diseases. Our previous work showed that telomerase reverse transcriptase (TERT) expression was particularly observed in the macrophage-rich region of human carotid atherosclerotic lesions. Interestingly, we have identified that a particular microRNA, miR-216a, was remarkably up-regulated in macrophages differentiation in PMA-stimulated THP-1 monocyte cells, regulating telomerase activity in this process. Different macrophage subtypes-M1 and M2 differentiated from monocytes have adverse influence on the formation of unstable plaques, however, the molecular mechanism in the pathogenesis of plaque stability has rarely been investigated. Telomerase activity regulated by miR-216a may contribute to the process of macrophages differentiation，and play an important role in atherosclerotic vascular remodeling. ..Therefore, in the present study, we aimed to (1) study the regulatory role of miR-216a in telomerase activity, macrophage differentiation and inflammatory response, via in vitro cell culture and in vivo ApoE-/- atherosclerotic mice model; (2) explore the mechanisms that telomerase activity regulates vascular remodeling via the macrophage subtype differentiation and inflammatory response; (3) investigate the relation between telomerase activity，miR-216a and the development and progression of atherosclerotic plaques, vascular calcification and the incidence of cardiovascular events in a large case-control study and a prospective cohort.

动脉粥样硬化是衰老相关的慢性炎症反应。前期工作发现，人颈动脉粥样硬化不稳定斑块中的巨噬细胞大量表达端粒酶、炎症反应活跃，且巨噬细胞的端粒酶激活过程受miR-216a/NF-κB的调控。因此，提出科学假说：端粒酶激活可能介导M1型巨噬细胞（促炎表型）的分化，促进平滑肌钙化、炎症反应和脂质核心扩大，诱发斑块不稳定。本项目拟解决关键科学问题1：通过细胞模型和TERT-/-、miR-216a-/-和 ApoE-/-等动脉粥样硬化小鼠模型，分析单核/巨噬细胞中端粒酶活性的调控机制-miR-216a/ NF-κB通路，阐明端粒酶激活是否通过影响巨噬细胞M1型分化，加速斑块进展和炎性重塑。问题2：以冠脉钙化患者队列为研究对象，分析单核细胞端粒酶活性和血浆miR-216a与动脉粥样硬化斑块易损性、血管钙化和心血管事件的关系。本项目将为阐明端粒酶激活调控单核巨噬细胞亚型分化及其炎性重塑的机制提供新的靶点。

不同表型的单核-巨噬细胞在动脉粥样硬化斑块形成、血管重塑和钙化过程中发挥着互补作用，与老龄化密切相关，是导致斑块破裂和急性心血管事件的重要原因。我们的前期工作发现，炎症刺激诱导的端粒酶活性可调控单核-巨噬细胞亚型分化（促炎或抗炎），这一过程通过与NF-kB信号的反馈激活作用而实现。本项目中，研究内容以炎性衰老和细胞生物钟“端粒”为切入点，探讨microRNA-216a（miR-216a）介导端粒酶激活促进巨噬细胞分化参与动脉粥样硬化进程的作用机制，评估外周血单核细胞端粒长度和端粒酶活性与中国人群血管钙化、进展及心血管事件中的预警价值。. 本项目首次鉴别到miR-216a与血管内皮细胞衰老过程密切相关，通过靶向抑制Smad3/NF-κB信号通路促进内皮细胞衰老和炎症反应，发表在Journal of Cellular and Molecular Medicine杂志（2018, 22:2739-2749），被多次引用。进而，通过细胞、动物和人群水平的系列研究，揭示miR-216a激活端粒酶、诱导M1型巨噬细胞分化、衰老，促进巨噬细胞的脂质摄取能力和泡沫细胞形成，加速动脉粥样硬化斑块进展。此外，血浆miR-216a水平与50岁以上老年人群的冠心病发生风险相关，且在具有冠脉易损斑块的人群中显著升高。发表在BBA-Molecular Basis of Disease杂志（2019,1865:1772-1781），被多次引用。申请专利2项。. 上述一系列研究首次阐明了microRNA-216a在血管细胞衰老、炎症和动脉粥样硬化斑块进展中的新机制，提示该分子在治疗动脉粥样硬化和预测相关心血管事件发生风险中的重要作用。