Wenzhou Central Hospital, Dingli Clinical College of Wenzhou Medical University, Wenzhou Sixth People’s Hospital, Wenzhou, Zhejiang, China.
Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, Linhai, Zhejiang, China.
Aging (Albany NY). 2024 Jul 17;16(14):11373-11384. doi: 10.18632/aging.206020.
To investigate the expression of programmed death ligand-1 (PD-L1) in circulating exosomes, and to define the role of exosomal PD-L1 in promoting immune escape mechanism during chronic hepatitis B infection (CHB) and related liver diseases.
The levels of PD-L1 expressed in exosomes were detected by ELISA. CD8+T cells were sorted and cytotoxicity test was assessed by flow cytometry. PD-L1 protein expression in hepatocellular carcinoma (HCC) and normal adjacent tissues were detected by immunohistochemistry.
Circulating exosomal PD-L1 levels were significantly higher in patients with CHB and HCC than in healthy controls (F =7.46, P=0.001). Levels of CD107a on CD8+T cells in patients with CHB receiving PD-L1 blocking antibody were significantly lower than in patients receiving isotype blocking antibody (t = 4.96, P < 0.01). Levels of TNF-α in cell culture supernatants of the PD-L1 blocking antibody group were significantly higher than in the isotype blocking antibody group (t =5.92, P < 0.01). Compared with patients receiving isotype blocking antibody, levels of CD107a on CD8+T cells significantly increased in patients with HCC receiving anti-PD-L1 antibody (t = 3.51, P<0.05). Compared with adjacent tissues, the levels of PD-L1 protein expression in HCC tissues were slightly higher; however, no significant difference between the two groups was observed.
PD-L1 blockade in exosomes might promote the cytotoxic function of CD8+T cells and inhibit immune evasion during progression of HCC. Blocking PD-L1 in exosomes reduced the cytotoxic function of CD8+T cells in patients with CHB while enhancing the production of proinflammatory cytokines.
研究程序性死亡配体-1（PD-L1）在循环外泌体中的表达，确定外泌体 PD-L1 在慢性乙型肝炎（CHB）感染及相关肝病中促进免疫逃逸机制中的作用。
采用 ELISA 法检测外泌体中 PD-L1 的表达水平，流式细胞术分选 CD8+T 细胞并进行细胞毒性检测，免疫组化法检测肝癌（HCC）及正常相邻组织中 PD-L1 蛋白的表达。
CHB 及 HCC 患者循环外泌体 PD-L1 水平明显高于健康对照组（F=7.46，P=0.001）。CHB 患者接受 PD-L1 阻断抗体治疗后 CD8+T 细胞上 CD107a 的水平明显低于接受同种型阻断抗体治疗的患者（t=4.96，P<0.01）。PD-L1 阻断抗体组细胞培养上清液中 TNF-α水平明显高于同种型阻断抗体组（t=5.92，P<0.01）。与接受同种型阻断抗体治疗的患者相比，接受抗 PD-L1 抗体治疗的 HCC 患者 CD8+T 细胞上 CD107a 的水平明显增加（t=3.51，P<0.05）。与相邻组织相比，HCC 组织中 PD-L1 蛋白表达水平略高，但两组间无明显差异。
外泌体 PD-L1 阻断可能促进 HCC 进展过程中 CD8+T 细胞的细胞毒性功能并抑制免疫逃逸。阻断外泌体中的 PD-L1 降低了 CHB 患者 CD8+T 细胞的细胞毒性功能，同时增强了促炎细胞因子的产生。
