Mast Cells and the Host Response in the Lung

描述(申请人提供)：我们研究的长期目标是确定肥大细胞调节宿主对细菌肺部感染的反应的机制，并能够改变肥大细胞如何以有利于宿主的方式协调这种反应。最近，我们发现肥大细胞蛋白酶二肽基肽酶I(DPPI)参与了感染性腹膜炎宿主的死亡，并且似乎是通过调节肥大细胞IL-6的水平来实现的。这表明肥大细胞DPPI或其他受DPPI调控的肥大细胞蛋白以损害宿主的方式改变了宿主对细菌感染的反应。我们的中心假设是：肥大细胞蛋白酶和细胞因子协调肺对细菌感染的防御。在协调这种防御的同时，这些介体中的一些保护宿主并提高存活率，而另一些则伤害宿主并恶化存活率。具体目标是：#1.确定肥大细胞DPPI调节宿主反应和细菌肺部感染存活的机制。这将通过应用一种新的方法来创建肥大细胞特异性基因敲除小鼠，并确定接种肺炎克雷伯菌后存活的生理机制。2.确定肥大细胞蛋白水解酶在细菌感染过程中调节细胞因子水平的机制。我们将通过将细胞因子与纯化的DPPI、类胰蛋白酶或糜酶孵育并鉴定切割产物来测试肥大细胞蛋白水解酶是否能降解细胞因子。将通过测量特定肺细胞对DPPI、类胰蛋白酶或糜酶的反应释放的细胞因子来研究蛋白酶介导的细胞因子的产生。#3.确定肥大细胞TNF-α、IL-6或IL-10是否调节宿主对细菌性肺部感染的反应和存活。我们将使用肥大细胞特异性的-TNF-α、-IL-6或-IL-10基因敲除小鼠来测试这些细胞因子的肥大细胞来源是否在宿主防御中发挥重要作用。通过了解特定的肥大细胞介质如何调节宿主防御，我们将更深入地了解这些细胞如何影响宿主生存。然后，这些知识可以应用于细菌性肺炎的新治疗方法的开发，以提高存活率的方式调节特定肥大细胞蛋白的活性。

DESCRIPTION (provided by applicant): The long-term objective of our research is to determine the mechanisms by which mast cells regulate the host response to bacterial lung infections and to be able to modify how mast cells coordinate this response in ways that benefit the host. Recently, we made the discovery that the mast cell protease dipeptidyl peptidase I (DPPI) contributes to death of the host from septic peritonitis and that it appears to do so by regulating levels of mast cell IL-6. This suggests that mast cell DPPI, or other mast cell proteins regulated by DPPI, modify the host response to bacterial infection in ways that harm the host. Our central hypothesis is that: Mast cell proteases and cytokines coordinate lung defense against bacterial infections. While coordinating this defense, some of these mediators protect the host and improve survival while others harm the host and worsen survival. Specific aims are: #1. To determine the mechanism by which mast cell DPPI modulates the host response and survival from bacterial lung infections. This will be accomplished by applying a new method for creating mast cell-specific knockout mice and determining the physiologic mechanism for survival following inoculation with Klebsiella pneumoniae. #2. To define mechanisms by which mast cell proteases regulate cytokine levels during bacterial infections. We will test whether mast cell proteases hydrolyze cytokines by incubating cytokines with purified DPPI, tryptase or chymase and identifying cleavage products. Protease mediated cytokine production will be studied by measuring cytokines released by specific lung cells in response to DPPI, tryptase or chymase. #3. To determine whether mast cell TNF-alpha, IL-6, or IL-10 modulate the host response and survival from bacterial lung infections. We will use mast cell-specific-TNF-alpha, -IL-6, or -IL-10 knockout mice to test if mast cell sources of these cytokines play important roles in host defense. By understanding how specific mast cell mediators regulate host defense, we will gain greater insight into how these cells influence host survival. This knowledge can then be applied to the development of new treatments for bacterial pneumonia that modulate the activity of specific mast cells proteins in ways that improve survival.