Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Peking University Health Science Center, Beijing, 100191, People's Republic of China.
Cardiovascular Division, BHF Centre for Vascular Regeneration, King's College London, London, SE5 9NU, UK.
J Mol Med (Berl). 2018 Jun;96(6):585-600. doi: 10.1007/s00109-018-1645-6. Epub 2018 May 7.
Inflammation mediated by activated T cells plays an important role in the initiation and progression of hyperhomocysteinemia (HHcy)-accelerated atherosclerosis in ApoE mice. Homocysteine (Hcy) activates T cells to secrete proinflammatory cytokines, especially interferon (IFN)-γ; however, the precise mechanisms remain unclear. Metabolic reprogramming is critical for T cell inflammatory activation and effector functions. Our previous study demonstrated that Hcy regulates T cell mitochondrial reprogramming by enhancing endoplasmic reticulum (ER)-mitochondria coupling. In this study, we further explored the important role of glycolysis-mediated metabolic reprogramming in Hcy-activated CD4 T cells. Mechanistically, Hcy-activated CD4 T cell increased the protein expression and activity of pyruvate kinase muscle isozyme 2 (PKM2), the final rate-limiting enzyme in glycolysis, via the phosphatidylinositol 3-kinase/AKT/mechanistic target of rapamycin signaling pathway. Knockdown of PKM2 by small interfering RNA reduced Hcy-induced CD4 T cell IFN-γ secretion. Furthermore, we generated T cell-specific PKM2 knockout mice by crossing LckCre transgenic mice with PKM2 mice and observed that Hcy-induced glycolysis and oxidative phosphorylation were both diminished in PKM2-deficient CD4 T cells with reduced glucose and lipid metabolites, and subsequently reduced IFN-γ secretion. T cell-depleted apolipoprotein E-deficient (ApoE) mice adoptively transferred with PKM2-deficient CD4 T cells, compared to mice transferred with control cells, showed significantly decreased HHcy-accelerated early atherosclerotic lesion formation. In conclusion, this work indicates that the PKM2-dependent glycolytic-lipogenic axis, a novel mechanism of metabolic regulation, is crucial for HHcy-induced CD4 T cell activation to accelerate early atherosclerosis in ApoE mice.
Metabolic reprogramming is crucial for Hcy-induced CD4 T cell inflammatory activation. Hcy activates the glycolytic-lipogenic pathway in CD4 T cells via PKM2. Targeting PKM2 attenuated HHcy-accelerated early atherosclerosis in ApoE mice in vivo.
在载脂蛋白 E 小鼠的高同型半胱氨酸血症（HHcy）加速动脉粥样硬化的起始和进展中，激活的 T 细胞介导的炎症起着重要作用。同型半胱氨酸（Hcy）激活 T 细胞分泌促炎细胞因子，特别是干扰素（IFN）-γ；然而，确切的机制尚不清楚。代谢重编程对于 T 细胞炎症激活和效应功能至关重要。我们之前的研究表明，Hcy 通过增强内质网（ER）-线粒体偶联来调节 T 细胞线粒体重编程。在这项研究中，我们进一步探讨了糖酵解介导的代谢重编程在 Hcy 激活的 CD4 T 细胞中的重要作用。在机制上，Hcy 激活的 CD4 T 细胞通过磷脂酰肌醇 3-激酶/AKT/雷帕霉素靶蛋白信号通路增加糖酵解的终末限速酶丙酮酸激酶肌肉同工酶 2（PKM2）的蛋白表达和活性。通过小干扰 RNA 敲低 PKM2 可减少 Hcy 诱导的 CD4 T 细胞 IFN-γ的分泌。此外，我们通过将 LckCre 转基因小鼠与 PKM2 小鼠杂交，生成了 T 细胞特异性 PKM2 敲除小鼠，并观察到 PKM2 缺陷的 CD4 T 细胞中的 Hcy 诱导的糖酵解和氧化磷酸化均减少，葡萄糖和脂质代谢物减少，随后 IFN-γ分泌减少。与转染对照细胞的小鼠相比，用 PKM2 缺陷的 CD4 T 细胞过继转移的 T 细胞耗尽的载脂蛋白 E 缺陷（ApoE）小鼠的 HHcy 加速的早期动脉粥样硬化病变形成明显减少。总之，这项工作表明，PKM2 依赖性糖酵解-生脂轴是代谢调节的新机制，对于 Hcy 诱导的 CD4 T 细胞激活以加速 ApoE 小鼠的早期动脉粥样硬化至关重要。
代谢重编程对于 Hcy 诱导的 CD4 T 细胞炎症激活至关重要。Hcy 通过 PKM2 在 CD4 T 细胞中激活糖酵解-生脂途径。靶向 PKM2 可减轻体内 HHcy 加速的 ApoE 小鼠早期动脉粥样硬化。
