EGFR Signaling in Macrophages: A Novel Regulator of Immune Responses to H. pylori

 描述(申请人提供)：幽门螺杆菌仍然是一个主要的公共卫生威胁，因为世界上有一半的人口受到感染。感染这种病原体是导致胃癌的主要因素，胃癌是全球癌症死亡的第三大原因。巨噬细胞对幽门螺杆菌引起高度炎症但无效的免疫反应，从而直接导致胃癌的发生。我已经确定巨噬细胞可以利用表皮生长因子受体(EGFR)信号，这是一种在上皮细胞中研究得很好的途径，但之前并未被怀疑在巨噬细胞中具有重要意义。我的初步数据表明，幽门螺杆菌感染足以诱导egfr磷酸化，egfr信号在巨噬细胞的激活、极化和功能中发挥着重要的全球作用，所有这些都是至关重要的。 对病原体的反应中的步骤。抑制EGFR反式激活导致几个关键基因的下调，包括白介素1？、肿瘤坏死因子和白介素10。此外，抑制pEGFR显著削弱巨噬细胞产生一氧化氮的能力，一氧化氮是一种有效的抗菌分子。我将确定幽门螺杆菌在巨噬细胞中诱导EGFR信号传递的机制。此外，我还将阐明EGFR信号的下游靶点，以及抑制EGFR激活对巨噬细胞多种功能的影响，包括极化、细胞因子/趋化因子的产生、吞噬、抗菌效应器的产生以及与T细胞的相互作用。利用髓系特异性EGFR基因敲除的小鼠模型，我将研究EGFR信号在幽门螺杆菌免疫发病机制中的体内作用。此外，我将利用来自哥伦比亚和洪都拉斯人类队列的组织样本来评估EGFR信号在人类疾病中对巨噬细胞的参与。拟议的研究将提供对细胞内巨噬细胞信号转导的基本见解，并更好地了解幽门螺杆菌的致病机制。我在幽门螺杆菌模型中对巨噬细胞的发现可能适用于一般巨噬细胞对各种病原体的反应，开辟了巨噬细胞领域的新研究方向。此外，这项建议试图确定针对巨噬细胞EGFR信号的有效性，用于炎症驱动的疾病和胃癌的治疗干预。这个项目将是我在学术博士后奖学金中继续宿主-病原体相互作用领域计划的理想培训工具。假设：EGFR的激活和信号在调节巨噬细胞对幽门螺杆菌的反应中的激活和功能方面具有新的和以前未被怀疑的作用。目的1：明确幽门螺杆菌感染诱导EGFR反式激活的机制。目的2：确定EGFR信号在巨噬细胞激活、极化和功能中的作用。目的3：探讨巨噬细胞内EGFR信号在幽门螺杆菌体内致病机制中的作用。

 DESCRIPTION (provided by applicant): Helicobacter pylori remains a major public health threat, as half of the world's population is infected. Infection with the pathogen is the primary rsk factor for developing gastric cancer, the third leading cause of cancer death worldwide. Macrophages elicit a highly inflammatory, yet futile immune response to H. pylori, and thereby contribute directly to gastric carcinogenesis. I have determined that macrophages can utilize epidermal growth factor receptor (EGFR) signaling, a well-studied pathway in epithelial cells, but previously unsuspected to be of significance in macrophages. My preliminary data indicate that H. pylori infection is sufficient to induce EGFR phosphorylation and that EGFR signaling plays a major and global role in macrophage activation, polarization and function, all of which are crucial steps in the response to a pathogen. Inhibition of EGFR transactivation results in the downregulation of several key genes, including interleukin (IL)-1ß, tumor necrosis factor (TNF)-a and IL-10. Moreover, inhibiting pEGFR significantly impairs the ability of macrophages to produce nitric oxide, a potent antimicrobial molecule. I will determine the mechanism by which H. pylori induces EGFR signaling in macrophages. Additionally, I will elucidate the downstream targets of EGFR signaling and the effects that inhibition of EGFR activation has on a wide variety of macrophage functions, including polarization, cytokine/chemokine production, phagocytosis, antimicrobial effector production and interactions with T-cells. Using a mouse model with myeloid-specific knockout of EGFR, I will investigate the in vivo effects of EGFR signaling on H. pylori immunopathogenesis. Additionally, I will utilize tissue samples from human cohorts in Colombia and Honduras to assess the involvement of EGFR signaling in macrophages in human disease. The proposed studies will provide fundamental insights into intracellular macrophage signaling and a better understanding of H. pylori pathogenesis. My findings in macrophages in the H. pylori model are potentially applicable to general macrophage function in response to a wide variety of pathogens, opening a new direction of research within the macrophage field. Furthermore, this proposal seeks to ascertain the efficacy of targeting macrophage EGFR signaling for therapeutic intervention in inflammation-driven diseases and in gastric cancer development. This project will be an ideal training vehicle for my plan of continuing in the field of host-pathogen interactions in an academic postdoctoral fellowship. Hypothesis: EGFR activation and signaling has a novel and previously unsuspected role in regulating macrophage activation and function in response to H. pylori. Aim 1: Define the mechanism by which H. pylori infection induces EGFR transactivation. Aim 2: Determine the role of EGFR signaling in macrophage activation, polarization and function. Aim 3: Determine the function of EGFR signaling in macrophages on H. pylori pathogenesis in vivo.