髓母细胞瘤分子亚型中CD8+T淋巴细胞浸润的临床病理特点

Clinicopathological characteristics of the CD8+T lymphocytes infiltration and its mechanism in distinct molecular subtype of medulloblastoma

目的:研究CD8+T细胞在髓母细胞瘤(medulloblastoma,MB)各个分子亚型中的浸润特点,分析CD8+T细胞浸润与患者预后的关系,以及C-X-C基序趋化因子11(C-X-C motif chemokine ligand 11)的表达及其受体CXCR3在CD8+T细胞中的表达情况,为进一步探索MB中CD8+T细胞浸润可能的调节机制提供临床病理依据。方法:筛选2012—2019年间来自多所医学中心、具有完整临床资料的MB患者共48例(4个分子亚型各12例),利用NanoString PanCancer IO360 TM基因表达检测平台对48例MB患者的肿瘤标本进行转录组学分析,对患者肿瘤组织的石蜡切片进行CD8免疫组织化学染色分析,验证各亚型MB中CD8+T细胞数量的差异。通过数据库生物信息学分析,探讨CD8+T细胞浸润与患者预后的关系及各种趋化因子在各亚型MB中的表达差异,并采用双重免疫荧光染色验证MB中CD8+T细胞表面CXCR3受体的表达情况,探讨CD8+T细胞浸润至肿瘤内的可能分子机制。结果:MB的WNT亚型中的CD8+T细胞特征指数相对较高,提示WNT亚型中的CD8+T细胞数量显著高于其他三个亚型,这一现象通过CD8免疫组织化学染色方法以及R2在线数据分析平台对美国基因表达数据库Gene Expression Omnibus(GEO)进行数据挖掘得到了证实,且CD8+T细胞增多与患者的生存期呈正相关。数据库分析显示,CXCL11在WNT亚型MB中的表达量明显高于其他三个亚型。免疫荧光染色结果显示,CD8+T细胞表面存在CXCL11的受体CXCR3,提示CD8+T细胞可能通过表面受体CXCR3受CXCL11趋化至MB的微环境中。结论:CD8+T细胞在WNT亚型MB中的浸润相对多于其他亚型,其机制可能与CXCL11-CXCR3趋化因子系统的激活相关,且肿瘤内CD8+T细胞浸润较多的患者预后较好,此结果可能为MB中CD8+T细胞浸润调节机制提供有益的临床病理依据,为未来MB的免疫治疗提供新的潜在治疗靶点。

Objective:To investigate the characteristics of the CD8+T cells infiltration from the 4 subtypes in medulloblastoma(MB),to analyze the relationship between CD8+T cells infiltration and prognosis,to study the function of C-X-C motif chemokine ligand 11(CXCL11)and its receptor in CD8+T cells infiltration into tumors and to explore the potential mechanism,and to provide the necessary clinicopathological basis for exploring the immunotherapy of MB.Methods:In the study,48 clinical MB samples(12 cases in each of 4 subtypes)were selected from the multiple medical center from 2012 to 2019.The transcriptomics analysis for the tumor of 48 clinical samples was conducted on the NanoString PanCancer IO360 TM Panel(NanoString Technologies).Immunohistochemistry(IHC)staining of formalin-fixed,paraffin-embedded sections from MB was carried out using CD8 primary antibody to analyze diffe-rential quantities of CD8+T cells in the MB four subtypes.Through bioinformatics analysis,the relationship between CD8+T cells infiltration and prognosis of the patients and the expression differences of various chemokines in the different subtypes of MB were investigated.The expression of CXCR3 receptor on the surface of CD8+T cells in MB was verified by double immunofluorescence staining,and the underlying molecular mechanism of CD8+T cells infiltration into the tumor was explored.Results:The characteristic index of CD8+T cells in the WNT subtype of MB was relatively high,suggesting that the number of CD8+T cells in the WNT subtype was significantly higher than that in the other three subtypes,which was confirmed by CD8 immunohistochemical staining and Gene Expression Omnibus(GEO)database analysis by using R2 online data analysis platform.And the increase of CD8+T cells infiltration was positively correlated with the patient survival.The expression level of CXCL11 in the WNT subtype MB was significantly higher than that of the other three subtypes.Immunofluorescence staining showed the presence of CXCL11 receptor,CXCR3,on the surface of CD8+T cells,suggesting that the CD8+T cells might be attracted to the MB microenvironment by CXCL11 through CXCR3.Conclusion:The CD8+T cells infiltrate more in the WNT subtype MB than other subtypes.The mechanism may be related to the activation of CXCL11-CXCR3 chemokine system,and the patients with more infiltration of CD8+T cells in tumor have better prognosis.This finding may provide the necessary clinicopathological basis for the regulatory mechanism of CD8+T cells infiltration in MB,and give a new potential therapeutic target for the future immunotherapy of MB.