HCV resolution correlates with patterned KIR expressions on lymphocytes.

描述（由申请人提供）：在急性丙型肝炎病毒（HCV）感染中，15-30%的病毒清除，70%以上的病毒进展为慢性感染。HCV分辨率受宿主杀伤免疫球蛋白样受体（KIR）及其人类白细胞抗原（HLA） I类配体多态性的影响。已发表的基因组分析表明，KIR和HLA的弱抑制性组合（因此更强的免疫力）与HCV解决率的增加有关，而强抑制性KIR/配体基因型与HCV的慢性相关。然而，单独的基因组分型无法检查KIR生物学的关键重要特征。首先，在不同的个体中，kir定义的NK细胞亚群的大小存在显著的可变性。其次，个体KIR基因的等位基因多态性可以显著影响受体密度和功能。第三，多个KIR的联合抑制作用，以及激活KIR的混杂效应，可以稀释离散抑制KIR/配体对的作用。在目前的建议中，我们采用流式细胞术结合基因组分析来检测NK细胞KIR表达和复合KIR/HLA类型对HCV分辨率的影响。我们的初步研究数据表明，自发的HCV分解与弱抑制受体（如KIR2DL3）在其同源HLA-C配体的背景下的强大NK细胞表达相关。此外，我们证明了抑制性KIR3DL受体及其HLA-A和-B配体与HCV的慢性性密切相关。在没有混杂抑制KIR3DL1/HLA-A或-B对的情况下，具有弱抑制性KIR2DL/HLA-C对的复合表型的分辨率最高。这些弱抑制性KIR/HLA类型的患者解决HCV的比率超过50- 70%，而我们研究人群的总清除率为16%。此外，我们发现激活KIR与选定HLA类型的病毒清除率相关，其HCV清除率几乎是整个队列的两倍。最后，我们的初步数据显示，KIR/HLA类型与HCV自发消退相关，可能使未能清除病毒的患者易患肝硬化。基于这些令人信服的初步数据，我们提出了一项更广泛的研究来验证不同NK细胞活化是HCV感染不同结果的基础假设。我们将(i)在大量HCV患者中确定KIR/HLA基因型和表型与HCV消退的相关性；（ii）确定慢性感染患者中与治疗诱导的HCV根除相关的KIR/HLA类型；（iii）确定慢性感染患者中HCV肝硬化的KIR/HLA相关性；（iv）确定KIR/HLA相互作用对NK细胞激活和NK细胞记忆的功能影响，以应对体外刺激，以及体内急性和慢性HCV感染。本提案中概述的研究验证了这样的假设，即KIR/HLA相互作用对HCV免疫有深远的影响，而不是适度的影响，并且KIR和HLA的多态性是宿主对选定感染因子反应的基础。这些研究也将有助于确定KIR作为药物抗病毒治疗的有吸引力的药物靶点。

DESCRIPTION (provided by applicant): In acute infection with hepatitis C virus (HCV), 15-30% clear the virus and more than 70% progress to chronic infection. HCV resolution is influenced by host polymorphisms of killer immunoglobulin-like receptors (KIR) and their human leukocyte antigen (HLA) class I ligands. Published genomic analyses suggest that weak inhibitory combinations of KIR and HLA (and hence stronger immunity) are associated with increasing rates of HCV resolution, while strong inhibitory KIR/ligand genotypes are associated with HCV chronicity. Genomic typing alone fails to examine critically important features of KIR biology, however. First, there is marked variability in the size of KIR-defined NK cell subsets among different individuals. Second, allelic polymorphisms in individual KIR genes can markedly affect receptor density and function. Third, the combined inhibitory effects of multiple KIR, as well as confounding effects of activating KIR, can dilute effects of discrete inhibitory KIR/ligand pairs. In the current proposal, we employ flow cytometry combined with genomic analyses to examine the effects of NK cell KIR expression and compound KIR/HLA types on HCV resolution. Data from our preliminary studies show that spontaneous HCV resolution is associated with the robust NK cell expression of weakly inhibitory receptors such as KIR2DL3 in the context of their cognate HLA-C ligands. In addition, we demonstrate that inhibitory KIR3DL receptors and their HLA-A and -B ligands are strongly associated with HCV chronicity. The highest resolution rates are in compound phenotypes with weak inhibitory KIR2DL/HLA-C pairs in the absence of confounding inhibitory KIR3DL1/HLA-A or -B pairs. Patients with these weak inhibitory KIR/HLA types resolve HCV at rates exceeding 50- 70%, compared with an overall clearance rate of 16% in our study population. Further, we find that activating KIR correlate with viral clearance in selected HLA types, with HCV resolution rates nearly twice those of the overall cohort. Finally, our preliminary data show that KIR/HLA types associated with spontaneous HCV resolution may predispose to cirrhosis among patients who fail to clear the virus. Based upon these compelling preliminary data, we propose a broader study to test the fundamental hypothesis that differential NK cell activation underlies diverse outcomes of HCV infection. We will (i) define KIR/HLA genotypic and phenotypic correlates of HCV resolution in a large cohort of HCV patients; (ii) define KIR/HLA types correlated with treatment induced HCV eradication among chronically infected patients; (iii) define KIR/HLA correlates of HCV cirrhosis among chronically infected patients; and (iv) define the functional effects of selected KIR/HLA interactions on NK cell activation and NK cell memory in response to in vitro stimuli, and in response to acute and chronic HCV infection in vivo. The studies outlined in this proposal test the hypothesis that KIR/HLA interactions have profound, rather than modest effects on HCV immunity, and that polymorphisms of KIR and HLA underlie host responses to selected infectious agents. These studies also will help to identify KIR as attractive drug targets for pharmacologic antiviral therapies. PUBLIC HEALTH RELEVANCE: Previous reports showed that different genes known as KIR influence the clearance of hepatitis C, a virus that typically causes chronic infection that can lead to liver cirrhosis, liver cancer and the need for liver transplantation. This study will define the effects of KIR genes on the outcome of hepatitis C infection, which could help identify the patients most likely to benefit from treatment and also could lead to the development of new, more effective drugs to treat this serious infectious disease.