S-腺苷同型半胱氨酸在缺血性卒中的发病作用机制研究

S-adenosylhomocysteine (SAH) has attracted extensive attention as a more reliable cardiovascular disease risk factor than homocysteine (Hcy). Some research showed that increased SAH concentrations were associated with the increase in risk for CVT. However, its exact mechanism in ischemic stroke pathogenesis and reliability as a stroke risk predictor remains unveiled. This project will evaluate the effect of SAH on ischemic stroke based on a three-tier system, focusing at vascular endothelial cell damage as the major initiation factor of ischemic stroke pathogenesis: cell line, animal model and population studies. Firstly, clarify the effects of SAH-induced brain microvascular endothelial cell (bEnd.3) DNA hypomethylation and corresponding mechanism of cellular damage. Secondly, determine SAH and Hcy levels and their correlation with relevant clinical manifestations in stroke rat brain. Finally, investigate the effects of SAH and its relevant metabolites on ischemic stroke by measuring levels of inflammation related factors in stroke patients and comparing with serum SAH to demonstrate any association and its reliability as a screening indicator. In-depth study of the role of SAH in ischemic stroke pathogenesis, and the mechanism of SAH-induced bEnd.3 damage could provide further, relatively more reliable scientific evidence for the prevention, diagnosis and treatment for ischemic stroke.

S-腺苷同型半胱氨酸（SAH）作为比同型半胱氨酸（Hcy）更敏感的心血管病危险因子已引起人们的广泛关注，研究发现SAH水平增加可增加脑静脉血栓的患病风险，但其确切的作用机制及在缺血性卒中发生中的影响尚不明确。本项目紧紧围绕脑血管内皮细胞损伤这一缺血性卒中发生的主要始动环节，从细胞、动物和人群三个层面探讨SAH对缺血性卒中影响。首先利用小鼠脑微血管内皮细胞株bEnd.3，从分子水平上研究SAH对bEnd.3甲基化的影响及细胞损伤机制；接着利用胱硫醚合成酶抑制剂羟胺（HA）及SAH阻断剂（ADA）饲喂自发性高血压自发性脑卒中大鼠（SHRsp），分析大鼠SAH及Hcy水平与临床表现的关系；最后利用已有人群开展病例对照研究，探讨其作为脑卒中筛检指标的可行性。该研究对进一步认识SAH在缺血性卒中中的作用、推动脑卒中预防和诊治、提高脑卒中患者及高危人群生活质量、减轻脑卒中造成的社会负担具有重要意义。

近年来，作为比同型半胱氨酸（Hcy）更敏感的心脑血管病危险因子，S-腺苷同型半胱氨酸（SAH）与脑卒中相关研究收到了广泛关注。研究发现SAH水平增加可增加脑静脉血栓的患病风险，但其在缺血性卒中发生中的影响及确切的作用机制尚不明确。本课题从细胞、动物和人群三个层面进行研究。细胞实验结果证实了SAH通过JNK通路的激活介导细胞凋亡发生，造成b.End3细胞损伤并导致b.End3细胞内凋亡率升高和相关促凋亡蛋白表达的升高以及抑凋亡蛋白表达的下降。大鼠MCAO手术激活了JNK通路介导的细胞凋亡，同时脑组织内凋亡蛋白的表达和炎症反应随着蛋氨酸浓度的升高而增加。人群分析结果表明，血清Hcy和SAM浓度增加可能是急性缺血性脑卒中（AIS）发病的独立危险因素。炎症因子、NLR和PLR在AIS的发生发展过程中发挥重要作用。结合人群脂肪酸代谢组学实验结果表明，血清中TNF-α、hs-CRP、顺-9-肉豆蔻烯酸、反-9-棕榈油酸、芥酸、反-10-十九碳烯酸、岩芹酸可能成为脑卒中高危人群血清标志物。本研究还建立了一种尿液中SAH和SAM准确、快速、经济、简单的新方法阐明了Bond Elut PBA、Bond Elut CBA、Bond Elut PRS三种固相萃取小柱与SAH和SAM之间的作用机制。本课题研究结论对进一步认识SAH在缺血性卒中发病及预后中的作用、推动脑卒中预防和诊治、提高脑卒中患者及高危人群生活质量、减轻脑卒中造成的社会负担具有重要意义。