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

先天性免疫应答的诱导通过特异性细胞因子来完成，所述细胞因子激活、募集和控制控制免疫应答所必需的免疫细胞的分化。在先天性免疫细胞上发现的哨兵蛋白中，模式识别受体的Toll样受体（TLR）家族与多种病原体上存在的分子模式结合。家族成员之一，TLR 7，负责识别单链RNA，许多病毒的遗传信息。在先天免疫应答期间由细胞因子诱导以控制TLR 7表达和功能的分子机制尚未完全阐明。然而，最近定义的细胞因子IL-27参与免疫应答的调节; IL-27在先天免疫应答中的作用知之甚少。在我之前的发现资助的支持下，我们发现IL-27增强了TLR 4表达，TLR家族成员负责识别细菌脂多糖（LPS），IL-27诱导细胞因子表达以及增强LPS诱导的细胞因子产生（Guzzo et al，JBC 2010; Guzzo et al JI 2012; Petes et al JLB 2016，修订中）。此外，我们显示IL-27诱导抗病毒蛋白质系链蛋白的表达（Guzzo等Sci Rep 2012）。总之，这项工作确立了IL-27在引发对感染的免疫应答中的作用。在此，我们将进一步探讨IL-27在先天免疫中的作用，通过检测IL-27调节TLR 7介导的抗病毒反应的分子机制，我们假设IL-27上调TLR 7表达并刺激髓样细胞中TLR 7的功能。事实上，我们的初步数据表明，IL-27上调TLR 7的表达，特别是在巨噬细胞。为了完全解决这一假设，将使用最先进的技术在原代人细胞和细胞系中进行体外实验。本研究的主要目的如下：1）鉴定IL-27依赖的上调TLR 7表达的调节介质2）评价IL-27影响TLR 7介导的信号转导和应答的机制3）确定IL-27是否调节病毒感染/复制和先天免疫应答。我们将开发一种人类体外系统，该系统可以扩展到其他先天性哨兵分子，以了解先天免疫系统如何依赖于模式受体识别分子的激活并启动免疫反应。这项工作将使加拿大受益，为HQP提供免疫学研究方面的宝贵培训，为我们未来的科学领导人提供促进自然科学研究和发展所需的技术专长和经验。HQP培训：共有2名博士，2名硕士和5名NSERC-USRA学生将被雇用来完成这项工作。

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 expression2) Evaluate the mechanism by which IL-27 impacts TLR7-mediated signaling and responses3) Determine if IL-27 regulates virus infection/replication and innate immune responsesSignificance: 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.