Eicosanoids and lung macrophage antimicrobial mechanisms

描述（由申请人提供）：肺部感染对全球健康的影响比任何其他类别的疾病都大，迫切需要更好地了解肺部的抗菌防御。肺泡巨噬细胞（AM）是远端肺的固有免疫防御者，这些细胞的免疫库通常与其他吞噬细胞的免疫库有很大不同。在感染过程中产生的物质中，来自花生四烯酸（类花生酸）的脂质介质，包括白三烯（LTs）B4（LTB 4）和D4（LTD 4）以及前列腺素E2（PGE 2），已成为先天免疫功能的重要调节剂。类二十烷酸通过连接细胞表面上的特异性G蛋白偶联受体并启动信号传导事件来起作用。我们已经表明，LTBB 4（通过B LT受体1 [BLT 1]）和LTD 4（通过半胱氨酰LT受体1 [cysLT 1]）促进AM吞噬和杀死IgG调理微生物的能力，而PGE 2（通过E前列腺素受体2和4 [EP 2和EP 4]）抑制AM吞噬和杀死IgG调理微生物的能力。然而，这些类二十烷酸的细胞内机制尚未完全了解。虽然这两种LT类促进AM中的先天免疫功能，但它们通过不同的信号通路起作用。同样，EP 2和EP 4连接后AM先天免疫功能的抑制由不同的途径介导。随着靶向特异性类花生酸受体的药理学药物的快速发展，了解此类靶向治疗对肺的抗微生物防御的作用是很重要的。该项目旨在了解这些类花生酸影响由调理素IgG受体-Fc 3受体（FcR）触发的AM信号通路中的关键事件的机制。为了进行比较，将研究与通过甘露糖受体（MR）摄入酵母菌白色念珠菌相关的事件。我们将关注的中心信号事件是：1）磷酸肌醇3-激酶（PI 3 K）/10号染色体上缺失的磷酸酶和张力蛋白同源物（PTEN）; 2）蛋白激酶C（PKC）的同种型;和3）小GTP酶的激活。该假说是，通过连接BLT 1与cysLT 1和EP 2与EP 4对这些吞噬细胞受体触发的信号传导组分的不同影响反映了这些受体对脂筏膜微结构域的差异定位及其与两种不同的环AMP效应物-蛋白激酶A（PKA）和由环AMP激活的交换蛋白（Epac-1）的差异偶联。利用原代大鼠AM，我们将致力于确定以下具体目标：1）PKA和Epac-1对FcR和MR诱导的信号事件的调节：2）FcR、MR及其下游信号组分在脂筏上的定位以及脂筏在吞噬和杀伤中的作用; 3）PKA与Epac-1和脂筏定位在解释BLT 1与cysLT 1连接对FcR和MR信号的不同调节中的作用; 4）PKA与Epac-1和脂筏定位在解释EP 2与EP 4连接对FcR和MR信号转导的不同调节中的作用。这些拟议的研究将提供AM抗菌功能的基本见解，并为理解和调节肺部先天免疫提供临床相关框架。公共卫生相关性：肺炎对全球健康的影响比任何其他类别的疾病都大，因此必须了解肺部如何保护自己免受感染。称为类二十烷酸的脂质介质，包括白三烯和白藜芦醇对肺中关键免疫细胞（肺泡巨噬细胞）的抗菌防御功能发挥有效和相反的作用。拟议的研究旨在了解这些类花生酸对肺泡巨噬细胞影响的细胞内事件，从而为肺防御机制的调节提供新的临床相关见解。

DESCRIPTION (provided by applicant): Infections of the lung have a greater impact on global health than any other category of disease, and there is an urgent need to better understand antimicrobial defense of the lung. Alveolar macrophages (AMs) are the resident innate immune defenders of the distal lung, and the immunologic repertoire of these cells often differs substantially from that of other phagocytic cells. Among the substances elaborated during infection, lipid mediators derived from arachidonate (eicosanoids), including leukotrienes (LTs) B4 (LTB4) and D4 (LTD4) as well as prostaglandin E2 (PGE2), have emerged as important modulators of innate immune function. Eicosanoids act by ligating specific G protein-coupled receptors on the cell surface and initiating signaling events. We have shown that both LTBB4 (via B LT receptor 1 [BLT1]) and LTD4 (via cysteinyl LT receptor 1 [cysLT1]) promote, while PGE2 (via E prostanoid receptors 2 and 4 [EP2 and EP4]) inhibits, AM capacity for phagocytosis and killing of IgG-opsonized microbes. However, the intracellular mechanisms by which these eicosanoids act are incompletely understood. Although both LT classes promote innate immune functions in AMs, they act via distinct signaling pathways. Likewise, suppression of AM innate immune functions following ligation of EP2 and EP4 is mediated by distinct pathways. As development of pharmacologic agents targeting specific eicosanoid receptors is proceeding rapidly, it is important that the effects of such targeted therapies on antimicrobial defenses of the lung are understood. This project seeks to understand the mechanisms by which these eicosanoids influence key events in the AM signaling pathway triggered by the receptor for opsonic IgG - the Fc3 receptor (FcR). For comparison, events associated with ingestion of the yeast Candida albicans via the mannose receptor (MR) will be studied. The central signaling events we will focus on are activation of: 1) phosphoinositide 3-kinase (PI3K)/phosphatase and tensin homolog deleted on chromosome 10 (PTEN); 2) isoforms of protein kinase C (PKC); and 3) small GTPases. The hypothesis is that divergent effects on these phagocytic receptor-triggered signaling components by ligation of BLT1 vs. cysLT1 and EP2 vs. EP4 reflect the differential localization of these receptors to lipid raft membrane microdomains and their differential coupling to two distinct cyclic AMP effectors - protein kinase A (PKA) and exchange protein activated by cyclic AMP (Epac-1). Employing primary rat AMs, we will address specific aims to determine: 1) regulation by PKA and Epac-1 of FcR- and MR-induced signaling events; 2) localization to lipid rafts of FcR, MR, and their downstream signaling components and the role of rafts in phagocytosis and killing; 3) the roles of PKA vs. Epac-1 and of lipid raft localization in explaining divergent modulation of FcR and MR signaling by BLT1 vs. cysLT1 ligation; 4) the roles of PKA vs Epac-1 and of lipid raft localization in explaining divergent modulation of FcR and MR signaling by EP2 vs. EP4 ligation. These proposed studies will provide fundamental insights into AM antimicrobial function, and a clinically relevant framework for understanding and modulating innate immunity in the lung. PUBLIC HEALTH RELEVANCE: Pneumonia has more of an impact on global health than any other category of disease, making it imperative to understand how the lung defends itself from infection. Lipid mediators termed eicosanoids and including leukotrienes and prostaglandins exert potent and opposing effects on the antimicrobial defense functions of the key immune cell in the lung, the alveolar macrophage. The proposed research aims to understand the intracellular events that underlie these eicosanoid effects on alveolar macrophages, thereby providing new clinically relevant insights into regulation of lung defense mechanisms.