Irisin抑制慢性肾衰竭血管钙化作用及机制研究

Irisin, as a newly identified hormone-like myokine mainly originated from skeletal muscle tissue. In our previous study, we found that lower serum irisin levels were associated with increased vascular calcification in hemodialysis patients. Our pilot study showed that irisin could prevent vascular smooth muscle cells (VSMCs) under high phosphate load condition from calcification in vitro. We presume that irisin is endogenous inhibitor of vascular calcification in chronic renal failure according to previous study and others study, We applied irisin treating vascular smooth muscle cells (VSMCs) or irisin precursor gene transfection in VSMCs in vitro study, animal model such as wild type C57Bl/6 mice and irisin precursor FNDC5 gene knockout mice combined with 5/6 renalrectomy fed with high phosphorus diet in order to verify our hypothesis. From our study, we demonstrate that irisin can inhibit vascular calcification in chronic renal failure, the main mechanisms are to inhibit expression of III type sodium-phosphate transporter 1, then inhibits VSMCs de-differentate to osteogenic transformation induced by exposure of high phosphorus , moreover, irisin can inhibit apoptosis and improving mitochondria dysfunction induced by high phosphate, and MAPK ,P38 signal pathways are involved. From our study, hint that application of irisin, or excise increasing irisin will be the new pathway for treatment and prevention of vascular calcification in chronic renal failure.

Irisin（鸢尾素）是近期新发现骨骼肌分泌为主的肌肉因子。我们前期研究证实,慢性肾衰竭的血液透析患者血清Irisin水平与血管钙化负相关，预实验结果显示:Irisin能显著拮抗高磷介导的体外血管平滑肌细胞（VSMCs）钙化。我们推测在慢性肾衰竭时,Irisin是内源性的血管钙化负性调节因子。本研究通过Irisin直接处理,以及Irisin前体基因转染至高磷孵育的VSMCs;动物实验应用野生型C57Bl/6小鼠和Irisin前体基因敲除小鼠做5/6肾切除并加高磷饲料饲喂,证实Irisin能抑制血管钙化。主要机制是Irisin抑制III型钠磷转运体1的表达,继而拮抗高磷介导的VSMCs成骨样转化,涉及调节MAPK及P38信号通路;抑制高磷介导的VSMCs凋亡及线粒体功能障碍,共同参与抑制血管钙化。本研究提示通过运动康复及补充irisin,可能防治慢性肾衰竭血管钙化。

慢性肾脏病（CKD）患者血管中膜钙化高发，发病机制复杂，尚未被阐明。鸢尾素（Irisin）是骨骼肌运动时分泌的肌肉细胞因子，对机体具有多种生物学效应。根据前期研究基础，我们提出假想：Irisin能抑制CKD相关的血管钙化。本项目通过体外培养的小鼠和人血管平滑肌细胞（VSMCs）细胞实验、结合VSMCs全转录组测序，体内动物实验：腺嘌呤饲喂加高磷饲喂制作CKD小鼠血管钙化模型、Irisin处理CKD小鼠血管钙化模型、以及Irisin前体FNDC5基因敲除小鼠再制作CKD小鼠主动脉钙化模型等研究方法，首次证实：Irisin能抑制CKD血管钙化，干预Irisin的作用，加重CKD血管钙化，机制涉及（1）Irisin抑制高磷（β-GP）诱导的小鼠VSMCs的活性氧（ROS）及丙二醛（MDA）水平的升高，并增加抗氧化剂SOD和ATP含量，抑制线粒体分裂，保护线粒体正常形态和功能，抑制VSMCs的成骨样转化和钙化，经兴奋AMPK信号实现。（2）Irisin抑制高磷诱导的体外小鼠VSMCs细胞凋亡，抑制CKD小鼠主动脉钙化及细胞凋亡。（3）首次证实高磷介导VSMCs细胞焦亡，高磷能够抑制VSMCs细胞自噬阻滞自噬流畅通，从而增加了活性氧的产生，继而活化炎症小体NLRP3，caspase1被剪切，GSDMD-N端表达上调，白细胞介素1β释放，细胞焦亡，导致VSMCS钙化。我们通过转录组技术进行了差异表达基因的分析，并对这些基因进行KEGG 通路富集分析，表达最高的10个通路就包含了自噬，经过realtime PCR验证Irisin能消除高磷下调的VSMCs多个自噬相关基因的表达，Irisin能促进VSMCs细胞自噬，继而减少活性氧释放，抑制NLRP3炎症小体激活，防止Procaspase1 剪切成cleaved caspase1，抑制GSDMD-N形成，从而抑制细胞焦亡。体内动物实验也证实Irisin处理能启动自噬，减少活性氧水平，从而抑制腺嘌呤饲喂介导的CKD小鼠血管中膜钙化，抑制NLRP3途径依赖的细胞焦亡。.通过本项目阐明Irisin 是机体内源性血管类激素样物质,能够抑制CKD 相关的血管钙化。今后在临床上补充Irisin，或者通过运动产生Irisin，可能是防治CKD血管钙化的有潜力的治疗策略。