KIR及其配体HLA-I多态性与HCV感染自然转归和Peg-IFN/RBV疗效的相关性研究

It has been shown that the natural killer (NK) cell plays a key role in the antiviral immune response in HCV spontaneous clearance and Peg-IFN/RBV therapy. However, the underlying mechanisms have not been completely understood yet. Our preliminary data demonstrated the frequency of KIR2DS3 expressed in NK cells surface was higher in chronically HCV infected blood donors than in healthy controls, while KIR2DS4 was more frequent in blood donors with spontaneous viral clearance than in those with chronic infection. We also found two HLA-B alleles were positively correlated with HCV chronic infection. These results suggested that KIR and its ligands, HLA -I molecule, are probably involved in the immune response of HCV infection or clearance. In this proposal, we intend to perform a case-control study on 420 blood donors with HCV chronic infection or spontaneous viral clearance, and 320 patients with Sustained Viral Response (SVR) or non SVR to Peg-IFN/RBV therapy. KIR/HLA-I genotyping will be performed by PCR-SSO method basing on the luminex fluorescent-bead assay. The association analysis will be applied to explore the correlation between the polymorphisms of KIR/HLA-I or the combination of KIR-HLA-I and the natural outcomes of HCV infection as well as the efficacy to achieve SVR to Peg-IFN/RBV treatment. The data obtained from this study will help to elucidate the mechanism of the antiviral immune response of NK cells, and to provide help for prevention of HCV infection and individualized treatment.

NK细胞在HCV自然清除和Peg-IFN/RBV治疗的免疫应答中起重要作用，但其作用机制尚未完全清楚。我们前期研究发现NK细胞表面受体KIR2DS3在HCV感染者中的频率显著高于健康人群，KIR2DS4在自然清除HCV者中的频率高于慢性感染者，而2个HLA-B等位基因与慢性HCV感染显著关联，提示KIR和配体HLA-I类基因多态性及其不同组合可能与HCV感染转归相关。在此基础上，本项目拟采用病例对照的研究方法，对420名慢性HCV感染和自然清除HCV献血者，及320名Peg-IFN/RBV治疗有持续病毒应答和无持续病毒应答患者，用PCR-SSO流式荧光磁珠法进行KIR和HLA-I基因分型，通过关联分析揭示KIR/HLA-I类配体遗传多态性与HCV感染自然转归及Peg-IFN/RBV疗效的相关性，了解NK细胞在抗HCV免疫应答中的作用，进而为HCV感染预防和个体化治疗方案的制定提供科学依据。

全世界携带丙型肝炎病毒的人数约1.85亿，每年约3~4百万人为新发感染。其中中国有大约3000万HCV抗体阳性者和20万/年新发感染。人体感染HCV后，有15%-40%的个体能在6个月之内自发清除病毒，其余转为慢性感染。NK细胞在HCV自然清除的免疫应答中起重要作用，NK细胞在先天免疫中发挥着重要作用， 其中NK细胞表面的免疫球蛋白样受体（KIRs）和其配体HLA-1类分子共同作用调节NK细胞的免疫活化/抑制功能，但KIR和HLA与中国人群自发清除HCV的关联性还不清楚。本项目中，我们收集了660例抗HCV抗体阳性的献血者标本，其中包括429例HCV慢性感染者和231例自发清除HCV者，HLA和白介素28B分型和分析，对其中203名清除者和204例感染者进行了KIR基因分型和分析，识别靶点，本项目采用病例对照的研究方法，对420名慢性HCV感染和自然清除HCV献血者，进行KIR和HLA-I和基因分型，并通过SPSS(16.0）软件对关联性进行了分析。 结果发现，KIR2DL2, 2DS2, 2DL2/2DL3 and 2DL5A-/2DL5B+ 与HCV自发清除相关 (odds ratio [OR] OR=1.640, P=0.034; OR=1.664, P=0.032; OR=1.636, P=0.040 and OR=2.601, P=0.012). 多因素回归分析表明， KIR2DL5A-/2DL5B+ 是独立于性别、IL28B and 其他KIR基因型与HCV的自发清除相关联的因素 (OR=2.448, P=0.027),而 KIR2DL3/2DL3 (OR=0.610, P=0.034)和2DL3/2DL3+HLA-C1 或 C1C1 (OR=0.580, P=0.017 and OR=0.639, P=0.025) 与HCV的慢性感染相关联。我们还发现 单纯KIR2DL3 或KIR2DL3/2DL3+HLA-C1或C1C1配体组合，都有利于HCV慢性感染化。 综上，KIR2DL5A-/2DL5B+ 与 HCV 的自发清除显著性关联，而KIR2DL3/2DL3, 2DL3/2DL3+HLA-C1 or C1C1 与HCV的慢性感染相关。我们的研究提示了NNK细胞通过KIR和 KIR-HLA在HCV的感染转归中发生作用，这些数据将为HCV疫苗的研制和个体