PD-1/PD-L1抑制途径诱导人乳头瘤病毒16型感染的免疫逃逸机制研究

Human papilloma virus type 16(HPV16) escaping from cellular immune clearance plays the most important role in persistent infection and subsequent carcinomatous change in cervix, and it is urgent to explore the mechanism that induces the immunologic escape in the study on early prevention and cure of cervical cancer. Although the existing related researches have indicated that cellular immunological dysfunction of HPV specific T lymphocytes resulted in the escaping, the inner signal mechanism remained to be indentified. Our prior research has demonstrated that increased expression of PD-1 and PD-L1 protein had close correlation with the negative regulation on cellular immunity in cervical lesion caused by HPV16 infection. In order to confirm this hypothesis, this project plans to explore the molecular mechanism in which the inhibitory PD-1/PD-L1 pathway negatively regulates cellular immune response specific to HPV16 and induces the escaping from immune clearance using cell biology and molecular immunology techniques and methods. In addition, we try to reverse the cellular immunologic dysfunction specific to HPV16 by blocking the inhibitory PD-1/PD-L1 pathway. This project will develop new orientation directing study on early prevention and cure of cervical cancer, and it is prospective to acquire new target for HPV infection treatment.

人乳头瘤病毒16型（HPV16）逃逸细胞免疫清除是其持续感染并最终诱发宫颈癌的关键环节，探明这种免疫逃逸现象的发生机制是宫颈癌防治研究中亟待解决的重要问题。已有研究虽然明确了病毒特异性T细胞免疫功能异常是HPV感染免疫逃逸的根本原因，但其内在的分子机制仍不清楚。申请者前期研究发现HPV相关子宫颈病变中PD-1和PD-L1蛋白过表达与细胞免疫功能异常密切相关，我们推测PD-1/PD-L1抑制途径通过负向调控细胞免疫应答诱导HPV16感染发生免疫逃逸。为验证这一假说，本课题拟运用细胞生物学与分子免疫学技术，探讨PD-1/PD-L1抑制途径负性调节HPV16特异性细胞免疫应答，诱导病毒逃逸免疫清除的分子机制，并试图通过实验性阻断PD-1/PD-L1抑制途径"逆转"病毒特异性细胞免疫功能障碍，获得HPV感染防治的新靶点，为宫颈癌的早期防治开拓新的思路和方向。

宫颈癌是全球妇女第二大常见恶性肿瘤，在正常宫颈上皮发生宫颈上皮内瘤变（cervical intraepithelial neoplasia, CIN）及宫颈癌的进展过程中，人乳头瘤病毒（human papillomavirus, HPV）感染扮演着重要的角色。高危型HPV持续感染导致宫颈粘膜细胞免疫功能障碍是诱导CIN和宫颈癌发生的重要机制。程序性细胞死亡分子-1/程序性细胞死亡分子配体-1（programmed death-1/programmed death ligand-1, PD-1/PD-L1）抑制途径能够降低抗原提呈细胞和T淋巴细胞对肿瘤的免疫清除，促进肿瘤的发生和发展。然而，HPV感染是否会导致宫颈免疫微环境PD-1/PD-L1抑制途径的激活，其负性免疫调节作用对肿瘤免疫逃逸及肿瘤进展的影响仍未阐明。在前期工作的基础上，本项目运用组织病理学、分子生物学及细胞免疫学技术，通过体外及体内实验研究高危型HPV感染相关CIN及宫颈癌PD-1/PD-L1蛋白表达与HPV感染、CIN分级及宫颈癌转移间的相关性，并通过调控PD-1/PD-L1信号通路对高危型HPV阳性宫颈癌细胞免疫功能进行影响与干预治疗。研究结果表明，PD-L1和PD-1表达升高与宫颈HPV阳性、CIN级别升高和肿瘤转移呈正相关，初步阐明PD-1/PD-L1信号通路负性调节T淋巴细胞功能及诱导病毒逃逸免疫的分子机制，同时提出PD-L1和PD-1表达水平可以作为CIN和宫颈癌临床预后指标，并通过调节PD L1表达改变PD-1/PD-L1活化状态达到对宫颈癌细胞的免疫治疗效果，获得了HPV感染防治的新靶点，为宫颈癌的早期防治开拓新的方向，为HPV治疗药物及高效疫苗的研制提供理论依据，具有一定的临床价值及应用前景。