Objective: To investigate the role of CXCL5 in tumor immune of lung cancer and to explore the potential molecular mechanisms. Methods: A total of 62 cases of patients with lung cancer admitted in the First Affiliated Hospital of Henan University from May 2018 to December 2019 were recruited as study object. Another 20 cases of patients with pulmonary infectious diseases and 20 cases of healthy control were selected as control. Enzyme-linked immunosorbent assay (ELISA) was used to determine serum levels of CXCL5 in patients with lung cancer, pulmonary infectious diseases and healthy control. Immunohistochemical staining (IHC) was used to detect the expressions of CXCL5 and PD-1/PD-L1 in tumor and paracarcinoma tissues of patients with lung cancer. Pearson correlation analysis was used to evaluate the correlation between CXCL5 and PD-1 in tumor and paracarcinoma tissues of patients with lung cancer. Lewis cells either expressing CXCL5 or vector plasmids were used to establish C57BL/6J mice model of lung cancer, and all mice were then divided into vehicle and PD-1 antibody treatment groups, 10 mice for each group. The mice survival and tumor growth curves were recorded. IHC was used to evaluate the expressions of CXCL5, PD-1 as well as the proportions of CD8(+) T and Treg cells in xenograft tumor tissues. Results: In patients with lung cancer, the serum level of CXCL5 [(351.7±51.5) ng/L] was significant higher than that in patients with pulmonary infectious diseases and healthy control [(124.7±23.4) ng/L, P<0.001]. The expression levels of CXCL5 (0.136±0.034), CXCR2 (0.255±0.050), PD-1 (0.054±0.012) and PD-L1 (0.350±0.084) in tumor were significant higher than those in paracarcinoma normal tissues [(0.074±0.022), (0.112±0.023), (0.041±0.007) and (0.270±0.043) respectively, P<0.001]. CXCL5 was significant positively correlated with PD-1 in tumor tissues of lung cancer (r=0.643, P<0.001), but not correlated with PD-1 in paracarcinoma tissues(r=0.088, P=0.496). The vector control group, CXCL5 overexpression group, vector control + anti-PD-1 antibody treatment group and CXCL5 overexpression + anti-PD-1 antibody treatment group all successfully formed tumors in mice, while CXCL5 overexpression increased the tumor growth significantly (P<0.01), which was abrogated by the treatment of anti-PD-1 antibody. CXCL5 overexpression decreased the mice survival time significantly (P<0.01), this effect was also abrogated by the treatment of anti-PD-1 antibody. The proportion of CD8(+) T cells in CXCL5 overexpression group [(10.40±2.00)%] was significant lower than that in vector control group [(21.20±3.30)%, P=0.002]. The proportion of CD4(+) Foxp3(+) Treg cells in CXCL5 overexpression group [(38.40±3.70)%] was significant higher than that in vector control group [(23.30±2.25)%, P<0.001]. After the treatment of anti-PD-1 antibody, no significant difference were observed for the proportion of CD8(+) T cells [(34.10±5.00)% and (33.40±4.00)% respectively] and Treg cells [(14.70±3.50)% and (14.50±3.30)% respectively] in xenograft tumor tissues between CXCL5 overexpression+ anti-PD-1 antibody treatment group and vector control + anti-PD-1 antibody treatment group (P>0.05). Conclusion: The expressions of CXCL5 and PD-1/PD-L1 are all increased significantly in the tumor tissues of patients with lung cancer, CXCL5 may inhibit tumor immune of lung cancer via modulating PD-1/PD-L1 signaling.
目的： 探讨CXC趋化因子配体5(CXCL5)对肺癌肿瘤免疫的影响及其分子机制。 方法： 2018年5月至2019年12月河南大学第一附属医院收治的62例肺癌患者、20例感染性肺部疾病患者和同期20名健康人，采用酶联免疫吸附法检测其血清CXCL5水平，采用免疫组化(IHC)染色检测肺癌患者癌及癌旁正常组织中CXCL5、程序性死亡蛋白1(PD-1)/程序性死亡蛋白配体1(PD-L1)的表达水平。Pearson相关性分析肺癌患者肿瘤及癌旁正常组织中CXCL5与PD-1的相关性。分别用稳定过表达CXCL5和转染空载质粒的Lewis细胞建立C57BL/6J小鼠肺癌模型，并进一步分为未治疗组和PD-1抗体治疗组，每组10只小鼠。记录各组小鼠的移植瘤成瘤情况和小鼠的存活情况，IHC染色检测各组小鼠移植瘤组织中CXCL5和PD-1的表达水平、CD8(+)T和Treg细胞比例。 结果： 肺癌组的血清CXCL5水平为(351.7±51.5)ng/L，高于感染性肺部疾病组[(211.6±29.1)ng/L]和健康组[(124.7±23.4)ng/L，P<0.001]。肺癌组织中的CXCL5、CXCR2、PD-1和PD-L1的表达水平分别为0.136±0.034、0.255±0.050、0.054±0.012和0.350±0.084，均高于癌旁正常组织[分别为0.074±0.022、0.112±0.023、0.041±0.007和0.270±0.043，均P<0.001]。肺癌组织中CXCL5与PD-1的表达水平呈正相关(r＝0.643，P<0.001)，癌旁正常组织中CXCL5与PD-1的表达水平无相关关系(r＝0.088，P＝0.496)。空载对照组、CXCL5过表达组、空载对照+PD-1抗体治疗组和CXCL5过表达+PD-1抗体治疗组小鼠均成瘤，但CXCL5过表达组小鼠的移植瘤增长比空载对照组快(P<0.01)，使用PD-1抗体治疗后CXCL5过表达的这种作用消失。CXCL5过表达组小鼠的生存时间短于空载对照组(P<0.01)，使用PD-1抗体治疗后CXCL5过表达的这种作用也消失。CXCL5过表达组移植瘤组织中的CD8(+) T细胞比例为(10.40±2.00)%，低于空载对照组[(21.20±3.30)%，P＝0.002]；CD4(+) Foxp3(+) Treg细胞比例为(38.40±3.70)%，高于空载对照组[(23.30±2.25)%，P<0.001]。使用PD-1抗体治疗后，CXCL5过表达+PD-1抗体治疗组和空载对照+PD-1抗体治疗组移植瘤组织中的CD8(+) T细胞比例[分别为(34.10±5.00)%和(33.40±4.00)%]和Treg细胞比例[分别为(14.70±3.50)%和(14.50±3.30)%]差异均无统计学意义(均P>0.05)。 结论： 肺癌患者肿瘤组织中CXCL5和PD-1/PD-L1表达增高，CXCL5可能通过激活PD-1/PD-L1信号通路抑制肿瘤免疫进而促进肺癌的发生发展。.
Keywords: CXC chemokine ligand 5; Lung neoplasms; Programmed death-1; Programmed death-ligand 1; Tumor immune.