Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark.
Sci Rep. 2017 Jan 13;7:40354. doi: 10.1038/srep40354.
HIV-specific CD8 T cells demonstrate an exhausted phenotype associated with increased expression of inhibitory receptors, decreased functional capacity, and a skewed transcriptional profile, which are only partially restored by antiretroviral treatment (ART). Expression levels of the inhibitory receptor, T cell immunoglobulin and ITIM domain (TIGIT), the co-stimulatory receptor CD226 and their ligand PVR are altered in viral infections and cancer. However, the extent to which the TIGIT/CD226/PVR-axis is affected by HIV-infection has not been characterized. Here, we report that TIGIT expression increased over time despite early initiation of ART. HIV-specific CD8 T cells were almost exclusively TIGIT, had an inverse expression of the transcription factors T-bet and Eomes and co-expressed PD-1, CD160 and 2B4. HIV-specific TIGIT cells were negatively correlated with polyfunctionality and displayed a diminished expression of CD226. Furthermore, expression of PVR was increased on CD4 T cells, especially T follicular helper (Tfh) cells, in HIV-infected lymph nodes. These results depict a skewing of the TIGIT/CD226 axis from CD226 co-stimulation towards TIGIT-mediated inhibition of CD8 T cells, despite early ART. These findings highlight the importance of the TIGIT/CD226/PVR axis as an immune checkpoint barrier that could hinder future "cure" strategies requiring potent HIV-specific CD8 T cells.
HIV 特异性 CD8 T 细胞表现出衰竭表型,与抑制性受体表达增加、功能能力下降和转录谱偏斜有关,这些表型仅部分通过抗逆转录病毒治疗 (ART) 恢复。在病毒感染和癌症中,抑制性受体 T 细胞免疫球蛋白和 ITIM 结构域(TIGIT)、共刺激受体 CD226 及其配体 PVR 的表达水平发生改变。然而,HIV 感染对 TIGIT/CD226/PVR 轴的影响程度尚未确定。在这里,我们报告尽管早期开始 ART,但 TIGIT 的表达随着时间的推移而增加。HIV 特异性 CD8 T 细胞几乎完全是 TIGIT,其转录因子 T-bet 和 Eomes 的表达呈反式,并且共表达 PD-1、CD160 和 2B4。HIV 特异性 TIGIT 细胞与多功能性呈负相关,并表现出 CD226 表达降低。此外,在 HIV 感染的淋巴结中,CD4 T 细胞(尤其是滤泡辅助性 T 细胞[Tfh])上的 PVR 表达增加。这些结果描绘了 TIGIT/CD226 轴从 CD226 共刺激向 TIGIT 介导的 CD8 T 细胞抑制的倾斜,尽管早期进行了 ART。这些发现强调了 TIGIT/CD226/PVR 轴作为免疫检查点障碍的重要性,这可能会阻碍未来需要有效 HIV 特异性 CD8 T 细胞的“治愈”策略。