Klotho改善慢性肾脏病加速性动脉粥样硬化的作用及机制研究

Chronic kidney disease (CKD) is associated with accelerated atherosclerosis (AS) and tends to form unstable AS plaques. However, the underlying mechanisms are still unclear. Recent studies reported that vascular smooth muscle cell (VSMC) senescence is the main contributor of AS progression and unstable plaque formation. Moreover, mitochondrial dysfunction-induced oxidative stress plays important roles in VSMC senescence. On the other hand, CKD is closely correlated with aging-like symptoms and oxidative stress. Interestingly, our preliminary study found that CKD can promote VSMC senescence, suggesting that CKD-induced VSMC senescence may participate in CKD-associated AS acceleration and unstable plaque formation. Meanwhile, CKD is associated with severe reduction of Klotho, which is an anti-aging humoral protein primarily expressed by kidneys and possesses a strong anti-oxidative property. Therefore, we presume that Klotho deficiency may participate in CKD-induced VSMC senescence, thereby contributing to CKD-associated AS acceleration and unstable plaque formation. Based on this, in this study, by adopting Apoe mice and Klotho mice, we will firstly reveal the role of CKD and Klotho deficiency in VSMC senescence, AS progression and unstable plaque formation and evaluate the rescue effects of exogenous Klotho administration on CKD-induced VSMC senescence, AS acceleration and unstable plaque formation. Then, by using primary VSMCs, we plan to explore the influence and mechanisms of CKD and CKD-induced Klotho deficiency in mitochondrial functions and VSMCs senescence. The aim of this study is to uncover the mechanism and provide a new insight into the treatment of CKD-associated AS acceleration and unstable plaque formation.

慢性肾脏病（CKD）时动脉粥样硬化（AS）进展加速，并易出现斑块不稳定性，但其机制不明。新近研究发现，血管平滑肌细胞（VSMC）衰老是AS进展和斑块不稳定的重要诱因，而线粒体异常导致的氧化应激是VSMC衰老的重要原因。CKD与衰老和氧化应激密切相关，我们前期发现CKD可以促进VSMC衰老。另外，Klotho是一种具有极强抗氧化应激能力的抗衰老蛋白，CKD时Klotho严重缺乏。我们推测Klotho缺乏可能参与了CKD诱导的VSMC衰老，从而导致AS斑块不稳定并加速AS的进展。为此，本项目拟采用Apoe小鼠和Klotho小鼠，明确CKD和Klotho缺失对VSMC衰老及AS进展和斑块不稳定性的影响，并评价上调Klotho对其救治作用，然后通过体外研究，探讨CKD及其诱导的Klotho缺乏对细胞线粒体功能和衰老的影响及机制，从而深入阐明CKD加速AS和斑块不稳定的机制，为其临床治疗提供新思路。

加速性动脉粥样硬化（AS）是慢性肾脏病（CKD）患者心血管疾病及恶性事件发生和发展的重要病理基础。AS不稳定斑块的形成是恶性心血管事件的关键环节，其中纤维帽变薄是斑块不稳定性的首要原因。纤维帽主要由血管平滑肌细胞（VSMC）组成，至今CKD内环境对VSMC的影响作用及其在CKD相关加速性AS中的作用尚不清楚。因此，本研究旨在探讨CKD内环境下VSMC损伤的深层机制，并寻找有效的救治措施。我们利用ApoE-/-小鼠制备CKD加速性动脉粥样硬化模型，发现CKD内环境下AS斑块不仅更大，而且更易出现不稳定性特征，表现为纤维帽更薄、斑块内出血等。组织病理学联用多组学分析发现，CKD可诱导VSMC早衰和炎性表型转换，尤其是表达和分泌I型干扰素（IFN-I）的能力显著增强，从而导致纤维帽VSMC数量显著减少。同时，本研究发现VSMC高表达固有免疫通路cGAS-STING通路，并使用基因敲除小鼠和VSMC特异性基因敲除小鼠证实cGAS-STING通路激活是诱导VSMC IFN-I产生的主要原因。进一步研究发现，CKD诱导的氧化应激可损害VSMC线粒体功能，导致mtDNA泄漏至胞浆而激活cGAS-STING通路。阻断cGAS-STING通路和IFN-I通路可有效防治CKD相关斑块不稳定性。另一方面，我们还发现肾源性抗衰老蛋白Klotho也可以通过减少活性氧（ROS）过量生成延缓CKD导致的VSMC衰老和AS斑块不稳定性。该研究深入阐明了CKD相关AS斑块不稳定性的发生机理，为CKD恶性心血管事件的防治提供了新思路和可能的临床治疗转化靶点。