Innate immune responses and IL-27: novel regulatory mechanisms of TLR7 expression and signaling

先天免疫反应的诱导是通过特定的细胞因子来完成的，这些细胞因子激活、招募和控制控制免疫反应所需的免疫细胞的分化。在先天免疫细胞上发现的前哨蛋白中，Toll样受体(TLR)模式识别受体家族与各种病原体上存在的分子模式结合。家族成员TLR7负责识别单链RNA，即许多病毒的遗传信息。细胞因子在先天免疫应答中调控TLR7表达和功能的分子机制尚未完全阐明。*最近定义的一种细胞因子IL-27参与了免疫反应的调节，但对IL-27在先天性免疫反应中的作用知之甚少。在我之前的发现基金的支持下，我们发现IL-27增强了TLR4的表达，TLR家族成员负责识别细菌脂多糖(LPS)，IL-27诱导细胞因子的表达以及增强LPS诱导的细胞因子的产生(Guzzo等人，JBC 2010；Guzzo等人JI 2012；Petes等人JLB2016正在修订中)。此外，我们发现IL-27诱导了抗病毒蛋白Tetherin的表达(Guzzo等人科学代表2012)。综上所述，这项工作确立了IL-27在启动感染免疫反应中的作用。在此，我们将通过研究IL-27诱导TLR7介导的抗病毒反应的分子机制来进一步探讨IL-27在先天性免疫中的作用。我们假设IL-27上调TLR7的表达并刺激髓系细胞的TLR7功能。事实上，我们的初步数据表明，IL-27上调TLR7在巨噬细胞中的特异性表达。为了充分解决这一假设，将使用最先进的技术，在原代人类细胞和细胞系中进行体外实验。将研究以下目标：*1)确定上调TLR7表达的IL-27依赖的调节介质*2)评估IL-27影响TLR7介导的信号和反应的机制*3)确定IL-27是否调节病毒感染/复制和先天免疫反应*意义：我的研究计划的首要目标是查明细胞因子用于控制先天免疫的新机制。我们将开发一个人类体外系统，该系统可以扩展到其他先天哨兵分子，以了解先天免疫系统如何依赖模式受体识别分子的激活，并启动免疫反应。这项工作将为HQP提供宝贵的免疫学研究培训，为我们未来的科学领导者提供促进自然科学研究和开发所需的技术专长和经验，从而使加拿大受益。*HQP培训：将雇用2名博士、2名硕士和5名NSERC-USRA学生来完成这项工作。

Induction of innate immune responses is accomplished by specific cytokines which activate, recruit, and control differentiation of immune cells necessary for control of immune responses. Of the sentinel proteins found on innate immune cells, the Toll-like receptor (TLR) family of pattern recognition receptors binds to molecular patterns present on a variety of pathogens. One family member, TLR7, is responsible for recognizing single-stranded RNA, genetic information for many viruses. The molecular mechanisms induced by cytokines to control TLR7 expression and function during an innate immune response have not been fully elucidated. ******A recently defined cytokine, IL-27, is involved in the regulation of immune responses however; the role of IL-27 in the innate immune response is poorly understood. Supported by my previous Discovery grant, we showed that IL-27 augmented TLR4 expression, the TLR family member responsible for recognizing bacterial lipopolysaccharide (LPS) and that IL-27 induced cytokine expression as well as enhanced LPS-induced cytokine production (Guzzo et al, JBC 2010; Guzzo et al JI 2012; Petes et al JLB 2016 under revision). Furthermore, we showed that IL-27 induced expression of the anti-viral protein, tetherin (Guzzo et al Sci Rep 2012). Taken together, this work establishes a role for IL-27 in priming immune responses to infection. Herein, we will further explore the role of IL-27 in innate immunity by examining molecular mechanisms regulated by IL-27 to induce TLR7-mediated anti-viral responses.******We hypothesize that IL-27 upregulates TLR7 expression and stimulates TLR7 function in myeloid cells. Indeed, our preliminary data demonstrates that IL-27 upregulates TLR7 expression specifically in macrophages. In order to fully address this hypothesis, in vitro experiments will be conducted in primary human cells and cell lines, using state-of-the-art techniques. The following aims will be investigated: ******1) Identify IL-27 dependent regulatory mediators that upregulate TLR7 expression***2) Evaluate the mechanism by which IL-27 impacts TLR7-mediated signaling and responses***3) Determine if IL-27 regulates virus infection/replication and innate immune responses******Significance: The overarching goal of my research program is to pinpoint novel mechanisms used by cytokines to control innate immunity. We will develop a human in vitro system that can be expanded to other innate sentinel molecules to understand how the innate immune system relies on activation by pattern receptor recognition molecules and initiate immune responses. This work will benefit Canada by providing valuable training to HQP in immunological research, giving our future scientific leaders the technical expertise and experience required for promoting research and development in the natural sciences. ******HQP training: A total of 2 PhD, 2 MSc, and 5 NSERC-USRA students will be hired to complete this work.