Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, 38 Xueyuan Road, Beijing 100191, China.
Department of Cardiology, Peking University First Hospital, Beijing 100034, China.
Redox Biol. 2018 Jul;17:386-399. doi: 10.1016/j.redox.2018.04.021. Epub 2018 May 1.
The adaptive immune system plays a critical role in hyperhomocysteinemia (HHcy)-accelerated atherosclerosis. Recent studies suggest that HHcy aggravates atherosclerosis with elevated oxidative stress and reduced S-nitrosylation level of redox-sensitive protein residues in the vasculature. However, whether and how S-nitrosylation contributes to T-cell-driven atherosclerosis remain unclear. In the present study, we report that HHcy reduced the level of protein S-nitrosylation in T cells by inducing S-nitrosoglutathione reductase (GSNOR), the key denitrosylase that catalyzes S-nitrosoglutathione (GSNO), which is the main restored form of nitric oxide in vivo. Consequently, secretion of inflammatory cytokines [interferon-γ (IFN-γ) and interleukin-2] and proliferation of T cells were increased. GSNOR knockout or GSNO stimulation rectified HHcy-induced inflammatory cytokine secretion and T-cell proliferation. Site-directed mutagenesis of Akt at Cys224 revealed that S-nitrosylation at this site was pivotal for the reduced phosphorylation at Akt Ser473, which led to impaired Akt signaling. Furthermore, on HHcy challenge, as compared with GSNORApoE littermate controls, GSNORApoE double knockout mice showed reduced T-cell activation with concurrent reduction of atherosclerosis. Adoptive transfer of GSNOR T cells to ApoE mice fed homocysteine (Hcy) decreased atherosclerosis, with fewer infiltrated T cells and macrophages in plaques. In patients with HHcy and coronary artery disease, the level of plasma Hcy was positively correlated with Gsnor expression in peripheral blood mononuclear cells and IFN-γ T cells but inversely correlated with the S-nitrosylation level in T cells. These data reveal that T cells are activated, in part via GSNOR-dependent Akt denitrosylation during HHcy-induced atherosclerosis. Thus, suppression of GSNOR in T cells may reduce the risk of atherosclerosis.
适应性免疫系统在高同型半胱氨酸血症（HHcy）加速动脉粥样硬化中起着关键作用。最近的研究表明，HHcy 通过增加氧化应激和降低血管中氧化还原敏感蛋白残基的 S-亚硝基化水平来加重动脉粥样硬化。然而，S-亚硝基化是否以及如何促进 T 细胞驱动的动脉粥样硬化仍然不清楚。在本研究中，我们报告 HHcy 通过诱导 S-亚硝基谷胱甘肽还原酶（GSNOR）降低 T 细胞中的蛋白质 S-亚硝基化水平，GSNOR 是催化 S-亚硝基谷胱甘肽（GSNO）的关键去硝基酶，GSNO 是体内一氧化氮的主要还原形式。因此，炎症细胞因子[干扰素-γ（IFN-γ）和白细胞介素-2]的分泌和 T 细胞的增殖增加。GSNOR 敲除或 GSNO 刺激纠正了 HHcy 诱导的炎症细胞因子分泌和 T 细胞增殖。在 Akt 的 Cys224 处进行的定点突变显示，该位点的 S-亚硝基化对于 Akt Ser473 的磷酸化减少至关重要，这导致 Akt 信号转导受损。此外，与 GSNORApoE 同窝对照相比，在 HHcy 挑战时，GSNORApoE 双敲除小鼠显示 T 细胞激活减少，同时动脉粥样硬化减少。将 GSNOR T 细胞过继转移到喂食同型半胱氨酸（Hcy）的 ApoE 小鼠中，可减少斑块中浸润的 T 细胞和巨噬细胞，从而减少动脉粥样硬化。在 HHcy 患者和冠心病患者中，血浆 Hcy 水平与外周血单个核细胞和 IFN-γ T 细胞中 Gsnor 的表达呈正相关，与 T 细胞中的 S-亚硝基化水平呈负相关。这些数据表明，在 HHcy 诱导的动脉粥样硬化过程中，T 细胞通过 GSNOR 依赖性 Akt 去硝基化而被激活。因此，抑制 T 细胞中的 GSNOR 可能降低动脉粥样硬化的风险。
