HIV/HCV共感染对IFN-ɑ介导的PDC-NK细胞相互作用的影响及机制研究

HIV/HCV co-infection is associated with a reduced rate of response to IFN-α based HCV therapy. Impairment of innate immunity by viruses is considered as one reason for this reduced response, but the details are still unclear. Our preliminary data showed that there is interaction between plasmacytoid dendritic cells (PDC) and natural killer (NK) cells, with IFN-α being the key player to mediate the PDC-NK interaction and direct NK activation. We also found that HIV dramatically impairs the PDC-NK interaction, whereas HCV has little effect on the interaction. This study will investigate the effects of HIV/HCV co-infection on PDC-NK interaction and inhibitory activity of PDC-NK cells on HCV replication. This study will also determine the essential role of IFN-α in PDC-NK interaction as well as the impact of co-infection on critical regulating function of IFN-α. On this basis, this study will use a series of biological techniques including RT- PCR array to screen IFN-α-related genes including the genes involved in IFN-α production in PDC and those related to IFN-α response in NK cells and identify the key factors responsible for the impairment caused by HIV/HCV co-infection. In summary, this study will reveal the impact of HIV/HCV co-infection on PDC-NK interaction and lay the foundation for clarifying the molecular mechanism(s) of impairment of PDC-NK interaction by co-infection. Our proposed study will provide evidence for the scientific understanding of the reduced response rate to IFN-α therapy among HIV/HCV co-infection population. it is of great clinical significance for the development of innate immunity-based new strategy against HIV/HCV infection.

HIV/HCV共感染可引起临床上HCV IFN-α治疗应答率下降，天然免疫遭病毒破坏被认为是机制之一，但具体机制未明。我们前期研究发现浆细胞样树突状细胞（PDC）与自然杀伤（NK）细胞存在相互作用，IFN-α是其中的关键介导因子，同时发现HIV可显著损害PDC-NK细胞相互作用，HCV对其影响较小。本项目将研究共感染对PDC-NK细胞相互作用及PDC-NK抑制HCV复制的影响，同时研究IFN-ɑ在PDC-NK细胞系统中的作用以及共感染对IFN-ɑ介导作用的影响，还将采用RT-PCR阵列等技术确定共感染破坏PDC产生IFN-ɑ或NK细胞应答IFN-ɑ过程中的关键因子，为阐明共感染损害PDC-NK细胞相互作用的分子机制奠定基础。本项目期望为临床上HIV/HCV共感染者显著降低的HCV IFN-ɑ治疗应答率提供理论证据，为临床共感染治疗提供基于天然免疫的治疗新策略。

HIV/HCV共感染非常普遍，可引起临床上HCV IFN-α治疗应答率下降。天然免疫遭病毒破坏被认为是机制之一，但具体机制未明。pDC-NK细胞系统在免疫体系中有重要作用，本研究主要探讨HIV和HCV感染对pDC-NK细胞间作用的影响。研究首先建立了体外pDC-NK细胞系统，pDC细胞可在体外经TLR9通路激活大量表达IFN-α，并由此激活NK细胞；不同感染人群的结果发现，HIV和HCV感染对体内pDC有激活作用，pDC产生的细胞因子（IFN-α，TNF-α，TNF-β，IL-12，IL-18）显著高于健康人群，但在体外ODN2216激活条件下，HIV pDC产生的IFN-α显著低于健康激活组，而HCV pDC产生细胞因子与健康激活组相当；HIV和HCV感染对NK细胞的细胞毒作用以及细胞因子产生均没有显著影响，但对pDC-NK系统均有一定影响。HIV组和HCV组pDC-NK产生的细胞因子（IFN-γ，IL-10，GM-CSF，MIP-1α，RANTES等）显著低于健康对照；在pDC-NK系统体外激活条件下，HIV pDC-NK组多数细胞因子（IFN-γ，IL-10，IL-13，GM-CSF，RANTES）和HCV pDC-NK组多数细胞因子（IFN-γ，IL-5，IL-10，GM-CSF，MIP-1α，MIP-1β，RANTES）显著低于健康激活组。本研究表明HIV和HCV感染均可使体内pDC细胞处于激活状态，但HIV感染损害了pDC的体外激活，IFN-α产生受到显著抑制，进而损害pDC-NK细胞系统的体外激活；而HCV感染对pDC体外激活没有显著影响，但也抑制了pDC-NK细胞系统的体外激活，推测是由HCV对NK细胞的抑制作用实现。上述结果表明HIV感染和HCV感染均可抑制pDC-NK细胞系统的相互作用，但抑制机制不同，HIV和HCV在共感染发生中具有协同的促进作用。