Division of BioMedical Sciences, Immunology and Infectious Diseases Program, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3V6, Canada.
J Immunol. 2013 Sep 15;191(6):3308-18. doi: 10.4049/jimmunol.1300164. Epub 2013 Aug 19.
Hepatitis C virus (HCV) successfully evades the immune system and establishes chronic infection in ∼80% of cases. Immune evasion may involve modulating NK cell functions. Therefore, we developed a short-term assay to assess immediate effects of HCV-infected cells on ex vivo NK cytotoxicity and cytokine production. Natural cytotoxicity, Ab-dependent cell-mediated cytotoxicity, IFN-γ production, and TNF-α production were all significantly inhibited by short-term direct exposure to HCV-infected hepatoma-derived Huh-7.5 cells. Inhibition required cell-to-cell contact and increased together with multiplicity of infection and HCV protein levels. Blocking potential interaction between HCV E2 and NK CD81 did not abrogate NK cell inhibition mediated by HCV-infected cells. We observed no change in expression levels of NKG2D, NKG2A, NKp46, or CD16 on NK cells exposed to HCV-infected Huh-7.5 cells for 5 h or of human histocompatibility-linked leukocyte Ag E on HCV-infected compared with uninfected Huh-7.5 cells. Inhibition of ex vivo NK functions did correspond with reduced surface expression of the natural cytotoxicity receptor NKp30, and downregulation of NKp30 was functionally reflected in reduced anti-NKp30 redirected lysis of P815 cells. Infection of Huh-7.5 cells with HCV JFH1(T) increased surface binding of an NKp30-IgG1 Fcγ fusion protein, suggesting upregulation of an antagonistic NKp30 ligand on HCV-infected cells. Our assay demonstrates rapid inhibition of critical NK cell functions by HCV-infected cells. Similar localized effects in vivo may contribute to establishment of chronic HCV infection and associated phenotypic and functional changes in the NK population.
丙型肝炎病毒 (HCV) 成功地逃避了免疫系统，导致 80%的病例发生慢性感染。免疫逃避可能涉及调节 NK 细胞的功能。因此，我们开发了一种短期测定法来评估 HCV 感染细胞对体外 NK 细胞细胞毒性和细胞因子产生的即时影响。自然细胞毒性、Ab 依赖性细胞介导的细胞毒性、IFN-γ 产生和 TNF-α 产生均被 HCV 感染的肝癌衍生细胞系 Huh-7.5 的短期直接暴露显著抑制。抑制需要细胞间接触，并且随着感染复数和 HCV 蛋白水平的增加而增加。阻断 HCV E2 和 NK CD81 之间的潜在相互作用并不能消除由 HCV 感染细胞介导的 NK 细胞抑制。我们观察到在将 NK 细胞暴露于 HCV 感染的 Huh-7.5 细胞 5 小时或在 HCV 感染的 Huh-7.5 细胞与未感染的 Huh-7.5 细胞相比，NK 细胞上的 NKG2D、NKG2A、NKp46 或 CD16 的表达水平没有变化。在体外 NK 功能抑制与自然细胞毒性受体 NKp30 的表面表达减少相对应，并且 NKp30 的下调在功能上反映为对 P815 细胞的抗 NKp30 重定向裂解减少。用 HCV JFH1(T)感染 Huh-7.5 细胞增加了 NKp30-IgG1 Fcγ 融合蛋白的表面结合，表明 HCV 感染细胞上 NKp30 拮抗配体的上调。我们的测定法证明了 HCV 感染细胞对关键 NK 细胞功能的快速抑制。体内类似的局部效应可能有助于 HCV 感染的建立以及 NK 细胞群体中相关的表型和功能变化。
