The MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, The Key Laboratory of Chemical Biology of Fujian Province, State Key Laboratory of Physical Chemistry of Solid Surfaces, Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian, 361005, China.
Small Methods. 2022 Sep;6(9):e2200549. doi: 10.1002/smtd.202200549. Epub 2022 Jul 10.
Exosomal programmed cell death ligand 1 (exoPD-L1) has emerged as a promising biomarker for cancer diagnosis and immunotherapy outcome prediction. However, the existing quantitation methods are incapable of addressing the heterogeneity of exoPD-L1 glycosylation, which has been demonstrated to be the institutional basis for PD-L1/PD-1 interaction and the crucial participant in inhibiting the activity of CD8 T cells. Herein, an aptamer- and lectin-induced proximity ligation assay combined with quantitative real-time polymerase chain reaction for precise quantitation of glycosylated exoPD-L1 is developed. Leveraging the metabolism-free lectin labeling of glycosylation, the glycosylation-independent aptamer tagging of PD-L1, and excellent selectivity of dual-recognition, this method enables glycosylated exoPD-L1 quantitation with high sensitivity and selectivity in a wash-free manner. As a result, this method is able to distinguish the levels of glycosylated exoPD-L1 between healthy donors and cancer patients with sensitivity and specificity of 100%. Compared with the total circulating exoPD-L1 level, glycosylated exoPD-L1 is for the first time identified to be a more reliable biomarker for tumor diagnosis. Overall, this strategy holds a great potential for revealing the significance of exoPD-L1 glycosylation and converting glycosylated exoPD-L1 into a reliable clinical indicator.
外泌体程序性细胞死亡配体 1（exoPD-L1）已成为癌症诊断和免疫治疗结果预测的有前途的生物标志物。然而，现有的定量方法无法解决 exoPD-L1 糖基化的异质性，已经证明这种异质性是 PD-L1/PD-1 相互作用的机构基础，也是抑制 CD8 T 细胞活性的关键参与者。在此，开发了一种适体和凝集素诱导的邻近连接测定法，结合定量实时聚合酶链反应，用于精确定量糖基化的外泌体 PD-L1。利用无代谢的凝集素对糖基化的标记、PD-L1 的糖基化独立适体标记以及双重识别的优异选择性，该方法能够以无洗涤的方式实现高灵敏度和选择性的糖基化外泌体 PD-L1 定量。因此，该方法能够以 100%的灵敏度和特异性区分健康供体和癌症患者之间糖基化外泌体 PD-L1 的水平。与总循环外泌体 PD-L1 水平相比，首次发现糖基化外泌体 PD-L1 是一种更可靠的肿瘤诊断生物标志物。总的来说，该策略具有揭示外泌体 PD-L1 糖基化意义并将糖基化外泌体 PD-L1 转化为可靠的临床指标的巨大潜力。
