PD-1抑制剂联合高剂量照射对肺癌小鼠的抑瘤作用及对其免疫系统的影响

Antitumor Effect of PD-1 Inhibitor Combined with High-dose Irradiation on Lung Cancer Mice and Its Effect on Immune System

目的 探讨程序性死亡1(PD-1)抑制剂联合高剂量照射对肺癌荷瘤小鼠肿瘤生长的抑制作用及对免疫系统的影响。方法 选取40只小鼠建立肺癌模型,造模成功小鼠随机分为模型组、PD-1抑制剂组、高剂量照射组、联合组(PD-1抑制剂联合高剂量照射),各10只,另设对照组10只。PD-1抑制剂组和联合组小鼠腹腔注射2 mg/mL的PD-1抑制剂100μL,对照组及模型组注射等量PBS,连续注射14 d;高剂量照射组和联合组小鼠肿瘤部位接受单次剂量10 Gy的电离照射。观察各组小鼠一般情况并记录体质量;ELISA法检测各组小鼠血清干扰素γ(IFN-γ)、白细胞介素-2(IL-2)、肿瘤坏死因子-α(TNF-α)水平;称取瘤质量并计算抑瘤率;检测各组小鼠胸腺指数、脾脏指数;HE染色观察肿瘤组织学变化;RT-PCR和Western blot分别检测小鼠肿瘤组织中PD-1、程序性死亡受体1(PD-L1)mRNA和蛋白表达情况。结果 与模型组比较,PD-1抑制剂组、高剂量照射组和联合组小鼠体质量、肿瘤生长抑制率、IFN-γ、IL-2、TNF-α、胸腺指数、脾脏指数水平升高,瘤质量、PD-1、PD-L1 mRNA和蛋白表达水平均降低(P<0.05)。与PD-1抑制剂组和高剂量照射组比较,联合组小鼠体质量、肿瘤生长抑制率、IFN-γ、IL-2、TNF-α、胸腺指数、脾脏指数水平升高,瘤质量、PD-1、PD-L1 mRNA和蛋白表达水平均降低(P<0.05)。结论 PD-1抑制剂可调节肺癌荷瘤小鼠免疫功能,对肿瘤生长有一定的抑制作用,联合高剂量照射可以提高疗效,可能是通过抑制PD-1/PD-L1信号通路发挥作用。

Objective To investigate the effect of programmed death 1(PD-1) inhibitor combined with high dose of irradiation on tumor inhibition and immune system in lung cancer mice.Methods 40 mice were selected to establish lung cancer model.The successful mice were randomly divided into model group,PD-1 inhibitor group,high dose of irradiation group and combined group(PD-1 inhibitor combined with high dose of radiation),with 10 in each group and 10 in the control group.Mice in PD-1 inhibitor group and combined group were intraperitoneally injected with 2 mg/ml PD-1 inhibitor 100 μL.The control group and model group were injected with the same amount of PBS for 14 days;The tumor sites of mice in high-dose irradiation group and combined group received a single dose of 10 Gy ionizing irradiation.The general conditions of mice in each group were observed and the body mass was recorded;The levels of serum γ interferon(IFN-γ),interleukin-2(IL-2) and tumor necrosis factor-α(TNF-α) were detected by ELISA;The weight of tumor and the tumor inhibition rate were calculated;The thymus index and spleen index of mice in each group were detected;The histological changes of tumors were observed by HE staining;The mRNA and protein expression of PD-1 and programmed death receptor 1(PD-L1) in mice tumor tissues were detected by RT-PCR and Western blot.Results Compared with the model group,the body weight,tumor growth inhibition rate and IFN-γ,IL-2,TNF-α,thymus index and spleen index were increased,and the tumor mass,PD-1,PD-L1 mRNA and protein expression were decreased of PD-1 inhibitor group,high dose of irradiation group and combined group(P<0.05).Compared with PD-1 inhibitor and high dose of irradiation group,the body weight,tumor growth inhibition rate and IFN-γ,IL-2,TNF-α,thymus index and spleen index were increased,and the tumor mass,PD-1,PD-L1 mRNA and protein expression were decreased of combined group(P<0.05).Conclusion PD-1 inhibitor can inhibit the tumor growth,and regulate immune function of lung cancer bearing mice,combined with high dose of irradiation can improve the curative effect,which may play a role by inhibiting PD-1/PD-L1 signal pathway.