Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, the Netherlands.
HMC Westeinde, The Hague, the Netherlands.
Atherosclerosis. 2019 Jun;285:71-78. doi: 10.1016/j.atherosclerosis.2019.04.217. Epub 2019 Apr 11.
CD8 T-cells have been attributed both atherogenic and atheroprotective properties, but analysis of CD8 T-cells has mostly been restricted to the circulation and secondary lymphoid organs. The atherosclerotic lesion, however, is a complex microenvironment containing a plethora of inflammatory signals, which may affect CD8 T-cell activation. Here, we address how this environment affects the functionality of CD8 T-cells.
We compared the cytokine production of CD8 T-cells derived from spleens and enzymatically digested aortas of apoE mice with advanced atherosclerosis by flow cytometry. Aortic CD8 T-cells produced decreased amounts of IFN-γ and TNF-α compared to their systemic counterparts. The observed dysfunctional phenotype of the lesion-derived CD8 T-cells was not associated with classical exhaustion markers, but with increased expression of the ectonucleotidase CD39. Indeed, pharmacological inhibition of CD39 in apoE mice partly restored cytokine production by CD8 T-cells. Using a bone-marrow transplantation approach, we show that TCR signaling is required to induce CD39 expression on CD8 T-cells in atherosclerotic lesions. Importantly, analysis of human endarterectomy samples showed a strong microenvironment specific upregulation of CD39 on CD8 T-cells in the plaques of human patients compared to matched blood samples.
Our results suggest that the continuous TCR signaling in the atherosclerotic environment in the vessel wall induces an immune regulatory CD8 T-cell phenotype that is associated with decreased cytokine production through increased CD39 expression in both a murine atherosclerotic model and in atherosclerosis patients. This provides a new understanding of immune regulation by CD8 T-cells in atherosclerosis.
CD8 T 细胞具有致动脉粥样硬化和动脉保护作用，但对 CD8 T 细胞的分析大多局限于循环和次级淋巴器官。然而，动脉粥样硬化病变是一个包含大量炎症信号的复杂微环境，这可能会影响 CD8 T 细胞的激活。在此，我们探讨了这种环境如何影响 CD8 T 细胞的功能。
我们通过流式细胞术比较了源自载脂蛋白 E 小鼠晚期动脉粥样硬化的脾脏和酶消化主动脉的 CD8 T 细胞的细胞因子产生情况。与系统性 CD8 T 细胞相比，主动脉 CD8 T 细胞产生的 IFN-γ和 TNF-α 减少。病变衍生的 CD8 T 细胞观察到的功能障碍表型与经典衰竭标志物无关，但与外核苷酸酶 CD39 的表达增加有关。事实上，在载脂蛋白 E 小鼠中，用药物抑制 CD39 部分恢复了 CD8 T 细胞的细胞因子产生。通过骨髓移植方法，我们表明 TCR 信号在动脉粥样硬化病变中诱导 CD8 T 细胞表达 CD39 是必需的。重要的是，对人类动脉内膜切除术样本的分析表明，与匹配的血液样本相比，人类患者斑块中的 CD8 T 细胞上 CD39 的表达明显上调，这与斑块中 CD8 T 细胞的细胞因子产生减少有关。
我们的结果表明，在血管壁的动脉粥样硬化环境中持续的 TCR 信号诱导一种免疫调节性 CD8 T 细胞表型，这种表型与 CD39 表达增加导致细胞因子产生减少有关，这在小鼠动脉粥样硬化模型和动脉粥样硬化患者中均有体现。这为 CD8 T 细胞在动脉粥样硬化中的免疫调节提供了新的认识。
