Li Jinhu, Chen Yi, Fan Yimin, Wang Hongqin, Mu Wei, Liu Xiaodong
Department of Neurosurgery, The First Hospital of Shanxi Medical University, 85 Jiefang South Road, Taiyuan, Shanxi, China.
Department of Interventional Radiology, Shanxi Provincial People's Hospital, Taiyuan, China.
Discov Oncol. 2023 Mar 16;14(1):32. doi: 10.1007/s12672-023-00638-x.
We aimed to observe the effect of radiotherapy on the expression of immune checkpoint molecule CEACAM1 in patients with glioma and the therapeutical effect of radiotherapy combined with blockade of CEACAM1 in mice with intracranial gliomas.
The expression of CEACAM1 on T-lymphocytes in the peripheral blood of patients with glioma was detected before and after radiotherapy; GL261 murine glioma cells (stably transfected with the luciferase gene) were implanted in the right caudate nucleus of C57BL/6 mice, and tumour growth was observed using the small animal in vivo imaging system. Mice were divided into 4 groups: (1) the isotype control; (2) the radiotherapy; (3) the anti-CEACAM1 treatment; and (4) the combination therapy. The survival of mice after treatment was recorded; the expression of CEACAM1 on murine glioma cells was detected by immunohistochemistry before and after radiotherapy; flow cytometry was adopted to detect CD8 T-cells (Treg) (CD4FoxP3CD25) among mouse brain-infiltrating T-cells; serum levels of IFN-γ and IL-10 were detected by ELISA; proliferation and apoptosis were observed by immunohistochemistry; Retrospective RNA-seq data analysis was conducted in a cohort of 325 patients with glioma in the Chinese Glioma Genome Atlas (CGGA) database and 702 patients in The Cancer Genome Atlas (TCGA) database.
The expression of CEACAM1 on CD4 and CD8 T-cells in the peripheral blood of patients with glioma was significantly higher 1 week after radiotherapy than before radiotherapy and was further increased 1 month after radiotherapy. Combined therapy notably inhibited the growth of intracranial tumours in mice and prolonged their survival time, with some mice being capable of surviving long-term (> 90 d). Immunohistochemistry revealed that the expression of CEACAM1 in murine glioma tissues after radiotherapy was elevated in a time-dependent manner. Flow cytometry analysis showed an increase in mouse brain-infiltrating CD8 T-lymphocytes, a decrease in Treg cells, and an increase in CD8 T/Treg cells after treatment. ELISA demonstrated the elevated levels of IFN and decreased levels of IL-10 in the serum of mice in the combination therapy group.
Radiotherapy combined with CEACAM1 inhibitors resulted in strong and durable anti-tumour immune responses against murine glioma and long-term survival of some mice. Hence, this study is expected to offer new effective immunotherapy strategies against glioma.
我们旨在观察放疗对胶质瘤患者免疫检查点分子癌胚抗原相关细胞黏附分子1（CEACAM1）表达的影响，以及放疗联合阻断CEACAM1对颅内胶质瘤小鼠的治疗效果。
检测胶质瘤患者放疗前后外周血中T淋巴细胞上CEACAM1的表达；将稳定转染荧光素酶基因的GL261小鼠胶质瘤细胞植入C57BL/6小鼠的右侧尾状核，使用小动物活体成像系统观察肿瘤生长情况。将小鼠分为4组：（1）同型对照；（2）放疗组；（3）抗CEACAM1治疗组；（4）联合治疗组。记录治疗后小鼠的存活情况；放疗前后通过免疫组化检测小鼠胶质瘤细胞上CEACAM1的表达；采用流式细胞术检测小鼠脑浸润性T细胞中CD8 T细胞（调节性T细胞（Treg）（CD4FoxP3CD25））；通过酶联免疫吸附测定（ELISA）检测血清中干扰素-γ（IFN-γ）和白细胞介素-10（IL-10）的水平；通过免疫组化观察增殖和凋亡情况；对中国胶质瘤基因组图谱（CGGA）数据库中的325例胶质瘤患者队列以及癌症基因组图谱（TCGA）数据库中的702例患者进行回顾性RNA测序数据分析。
胶质瘤患者外周血中CD4和CD⑧ T细胞上CEACAM1的表达在放疗后1周显著高于放疗前，且在放疗后1个月进一步升高。联合治疗显著抑制了小鼠颅内肿瘤的生长并延长了其存活时间，部分小鼠能够长期存活（>90天）。免疫组化显示放疗后小鼠胶质瘤组织中CEACAM1的表达呈时间依赖性升高。流式细胞术分析显示治疗后小鼠脑浸润性CD8 T淋巴细胞增加，Treg细胞减少，CD8 T/Treg细胞增加。ELISA表明联合治疗组小鼠血清中IFN水平升高，IL-10水平降低。
放疗联合CEACAM1抑制剂可对小鼠胶质瘤产生强烈且持久的抗肿瘤免疫反应，并使部分小鼠长期存活。因此，本研究有望为胶质瘤提供新的有效免疫治疗策略。
