晚期糖基化终产物加重静脉桥血管重构的作用和机制研究

High blood glucose may cause many structural or functional protein non-enzymatic glycation and ultimately generate advanced glycation end products (AGEs). The receptor for AGEs (RAGE) is a cell membrane receptor which locates mainly on the cell surface of vascular endothelial cells, smooth muscle cells (SMCs) and other cells. Some study found that RAGE combined with AGEs could induce oxidative stress, increase various cytokines and inflammatory cytokine production, promote inflammation, and cause atherosclerosis and microvascular complications in patients with diabetes mellitus (DM). DM is not only the specific risk factor for cardiovascular disease but severely reduces the benefits of coronary artery bypass grafting (CABG) by promoting vein graft disease. Vein graft failure occur secondary to the proliferation and migration of smooth muscle cells(SMCs) and deposition of extracellular matrix (ECM). The native biological behavior of SMCs and ECM milieu may significantly impact the tendency of a vessel for pathologic remodeling. But the influence of AGEs-RAGE on the phenotypic transformation, proliferation and migration of SMCs in SV is still not very clear. Moreover, the role of mitogen-activated protein kinase (MAPK) signaling pathway on matrix metalloproteinases-2 (MMP-2), MMP-9 gene expression in SMCs after the stimulation from AGEs-RAGE combination is still unknown. Therefore, the aims of this study is to clear the effect of AGEs-RAGE and MAPK signaling pathway on the phenotype and function SMCs in SV of patients with type 2 DM. We hope that this study for the role of AGEs-RAGE and MAPK signaling pathway on the phenotype and function of SMCs in SV may provide therapeutic targets to improve the remodeling of SV before coronary surgery and reduce or delay the occurrence of vein graft disease after CABG in patients with type 2 DM.

冠状动脉搭桥术（CABG）是冠心病重要的治疗手段，但2型糖尿病（DM）患者CABG效果较差，其原因尚有待阐明。我们前期研究发现DM使得CABG前大隐静脉（SV）中细胞外基质表达失衡，加重SV重构和桥血管病变，但机制不清。已知高血糖产生的晚期糖基化终产物（AGEs）通过其受体RAGE激活MAPK信号通路，引起血管平滑肌细胞（SMC）表型和功能改变，并产生多种因子参与动脉粥样硬化发生发展。据此推测，AGEs-RAGE通过MAPK信号通路促进SV血管SMC表型转化、增殖、迁移是DM加重静脉桥病变的重要机制。本项目通过体外培养SV血管SMC和在体建立DM小鼠动-静脉搭桥模型，观察AGEs对SMC表型、功能、静脉桥重构及MMP-2/9的影响，明确AGEs-RAGE-MAPK信号通路的调控机制，探讨吡多胺的干预作用，为阐明DM引起SV病变的分子机制、改善DM患者CABG后静脉桥血管病变提供新思路。

本项目主要是针对AGE（晚期糖基化终产物）/RAGE（晚期糖基化终产物受体）在参与心脏搭桥手术（CABG）后静脉桥血管动脉粥样硬化的发生发展机制，并尝试在动物模型和临床药物上进行探究。在课题预实验过程中，我们首先在研究中发现，和动脉桥血管（乳内动脉）相比，只有静脉桥血管在AGE/RAGE的通路的激活条件下通过MAPK途径发生血管平滑肌的增殖。之后，我们继续抓住科研前沿热点，发现了环状RNAHIPK3（circRNA HIPK3）和微小RNA637（miRNA-637）在动脉粥样硬化中对平滑肌细胞的增殖和凋亡起到的作用。以上结果解决了部分动脉粥样硬化和CABG术后血管重构的机制问题。并在一项针对接受CABG手术的患者中发现，吸烟和被动吸烟通过MMP2和MMP9分子参与大隐静脉的重构和动脉粥样硬化的发生发展。在上述的研究基础的支持下，我们同时研究了在二叶式主动脉瓣畸形（BAV）及胸主动脉瘤（TAA）的发病机制和辅助诊断策略。由于BAV伴TAA的高发性以及其发生夹层和破裂风险的不可预知性，我们尝试研究sRAGE（可溶性晚期糖基化终产物受体）这一分子作为这一疾病风险性的血清标志物，也在体外实验中证实了其参与致病的潜在细胞通路。以上科研成果，首先在动脉粥样硬化的机制及桥血管的远期预后提供了科学依据，在其中发现的潜在细胞通路可以作为未来临床药物开发的新方向。第二，对于BAV这一高发的异常心脏瓣膜表型（全人口发病率1%-2%），以及其高风险性并发症TAA的研究可以在一定程度上为BAV伴TAA的外科手术时机提供科学的辅助决策。针对其发病机制的研究也可以作为延缓胸主动脉瘤进展药物研发的参考。