THE ROLE OF PULMONARY SUBPOPULATIONS AND TH2 IMMUNITY IN BALB/C SILICOSIS MODEL

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 具体目标和假设 在职业和环境环境中长期接触结晶二氧化硅会导致慢性肺部炎症，进而发展为纤维化，即矽肺。肺巨噬细胞与二氧化硅的相互作用被认为是疾病过程中的关键事件(1，2)。此外，肺的环境被认为是免疫抑制的；因此，像矽肺这样的慢性炎症的诱导是典型的肺免疫调节环境被破坏的结果。虽然这种破坏的一部分很可能是由于二氧化硅颗粒的细胞毒性特性，但并不是所有的肺巨噬细胞都会在与颗粒相互作用后死亡。事实上，我们已经记录了在小鼠模型中一些巨噬细胞的激活增加。小鼠(Balb/c或C57BL/6常见野生型菌株)呼吸道暴露于结晶二氧化硅会导致肺纤维化，并已被证明是人类疾病的有效模型。我们的实验室和其他人已经证明，Balb/c矽肺模型需要Th2免疫才能进展为纤维化(3-5)。到目前为止，我们的实验室已经发现，接触结晶二氧化硅后，与Th2免疫相关的几种成分显著增加，包括交替激活的巨噬细胞(AaMac)、白细胞介素4+间质细胞和胰岛素样生长因子(IGF)-1的标志物。此外，我们还发现肺巨噬细胞亚群表达Akt，Akt是IGF-1启动的生存途径的关键组成部分，并且似乎易于在疾病的早期阶段存活。我们建议检验这一中心假设，即与Th2免疫相关的多种细胞类型和可溶性因子在Balb/c矽肺模型中显著增加，并且它们都有助于改变疾病的免疫激活环境。我们将使用以下两个目的来检验这一假设(如图1示意图所示)： 具体目标1：评估暴露于结晶性二氧化硅后肺巨噬细胞亚群中的炎性小体激活。假设：在矽肺模型中，肺巨噬细胞亚群诱导与IL-33产生相关的炎症体途径，并促进促纤维化环境。结合使用流式细胞术和信使核糖核酸分析，将根据炎症小体的激活和IL-33的产生来确定肺巨噬细胞亚群。 具体目标2：明确接触结晶二氧化硅后炎症体与生存(IGF-1-Akt)通路的相互作用。假设：二氧化硅诱导死亡和存活，特别是巨噬细胞亚群，两者协同作用，为矽肺模型的促纤维化环境做出贡献。使用体外培养系统(原代AM和骨髓源性巨噬细胞)，在结晶性二氧化硅颗粒存在的情况下，炎症体和生存通路都将被各种刺激剂激活，以评估它们在促纤维化环境发展中的相互作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Specific Aims and Hypothesis Prolonged exposure to crystalline silica in occupational and environmental settings induces chronic lung inflammation that can progress to fibrosis, i.e. silicosis. The interaction of pulmonary macrophages with silica is considered a key event in the disease process (1, 2). Furthermore, the environment of the lung is considered immunosuppressive; therefore, the induction of a chronic inflammatory condition like silicosis is the result of a disruption of the typical immunomodulatory environment of the lung. While a portion of this disruption is most likely due to the cytotoxic properties of silica particles, not all pulmonary macrophages die following interaction with the particulates. In fact we have documented increased activation of some macrophages in the mouse model. Respiratory exposure of mice (either Balb/c or C57Bl/6 common wild type strains) to crystalline silica results in pulmonary fibrosis, and has proven an effective model of the human disease. The Balb/c silicosis model has been shown, by our laboratory and others, to require Th2 immunity for progression to fibrosis (3-5). To date our laboratory has found several components associated with Th2 immunity to be significantly increased following exposure to crystalline silica including markers of alternatively activated macrophages (aaMac), interleukin (IL)-4+ interstitial cells, and insulin-like growth factor (IGF)-1. In addition, we have found a subset of pulmonary macrophages that express Akt, a key component of the survival pathway instigated by IGF-1, and appear to be predisposed to survival in the early stages of the disease. We propose to test the central hypothesis that multiple cells types and soluble factors that are associated with Th2 immunity are significantly increased in the Balb/c model of silicosis and that they all contribute to altered immune-activated environment of the disease. We will use the following two aims to test this hypothesis (as depicted in Fig. 1 schematic): Specific Aim 1: Evaluation of inflammasome activation in macrophage subsets of the lung following exposure to crystalline silica. Hypothesis: A subset of pulmonary macrophages induces the inflammasome pathway associated with IL-33 production and promotes a pro-fibrotic environment in the silicosis model. Using a combination of flow cytometry and mRNA analysis, pulmonary macrophage subsets will be defined based on inflammasome activation and IL-33 production. Specific Aim 2: Define the interaction of the inflammasome and survival (IGF-1-Akt) pathways following exposure to crystalline silica. Hypothesis: Silica induces both death and survival in particular macrophage subsets, both of which act synergistically to contribute to the pro-fibrotic environment of the silicosis model. Using in vitro culture systems (primary AM and bone marrow-derived macrophages) both the inflammasome and survival pathways will be activated with various stimulants in the presence of crystalline silica particles to assess their interaction in the development of a pro-fibrotic environment.