Lung Inflammation and Fibrosis After Asbestosis Exposure is Regulated by Rac1

描述（由申请人提供） 大量暴露于石棉的患者的肺部反应的特征是长时间的、强烈的炎症反应，通常导致肺纤维化。TNF-？肺泡巨噬细胞的吞噬在石棉肺患者肺部发生的炎症反应中起着不可或缺的作用。肺泡巨噬细胞的一个特征是它们自发地释放TNF-？它们类似于单核细胞。来自研究者的数据显示，单核细胞产生大量的TNF-？在体外受到石棉的刺激。与大多数刺激相比，我们的新数据表明，p38 MAP激酶是一个积极的调节和ERK MAP激酶是一个负调节TNF-？生产应对石棉刺激。然而，有限的数据是在上游信号通路连接石棉与TNF-？表情GTCRac 1是上游第二信使，在炎症中起重要作用。在这方面，我们的新数据还表明，TNF-？在过表达Rac 1的单核细胞中产生增加，并且Rac 1缺失小鼠在暴露于石棉后免于发生肺纤维化。研究人员假设，Rac 1发挥了关键作用，在差异调节MAP激酶激活，这种差异激活是至关重要的TNF-？石棉刺激人单核细胞的基因表达。除了我们的体外模型，我们将探讨这在肺泡巨噬细胞从石棉肺患者和石棉肺的动物模型。在目标1中，我们将把我们的研究重点放在Rac 1差异调节MAP激酶通路的机制上。这些研究还将确定p38是否通过激活双特异性磷酸酶抑制ERK激酶的表达。在石棉肺小鼠模型中使用野生型和Rac 1缺失小鼠将提供生物学相关性。在目的2，我们将首先确定如果Rac 1调节TATA结合蛋白（TBP）磷酸化，这是必不可少的TNF-？基因表达。由于Rac 1对MAP激酶活化有不同的影响，我们将确定是否增加p38和减少ERK活性是必要的最佳TNF-？生产研究人员还将比较石棉肺患者与正常受试者的肺泡巨噬细胞的Rac 1、p38和ERK活性。将野生型和Rac 1缺失小鼠暴露于石棉以确定对间质性纤维化发展的影响将提供额外的生物学相关性。

DESCRIPTION (provided by applicant) The response of the lungs in patients with significant exposure to asbestos is characterized by a prolonged, intense inflammatory response that often results in pulmonary fibrosis. The release of TNF-? by alveolar macrophages plays an integral role in the inflammatory response that occurs in the lungs of patients with asbestosis. A characteristic feature of the alveolar macrophages is that they spontaneously release TNF-? and they resemble monocytes. Data from the investigators show that monocytes produce a significant amount of TNF-? when stimulated in vitro with asbestos. In contrast to most stimuli, our novel data demonstrates that the p38 MAP kinase is a positive regulator and the ERK MAP kinase is a negative regulator of TNF-? production in response to asbestos stimulation. However, limited data is available on the upstream signaling pathways linking asbestos with TNF-? expression. The GTPase Rac1 is an upstream second messenger that plays an important role in inflammation. In this regard, our novel data also show that TNF-? production is augmented in monocytes over expressing Rac1, and Rac1 null mice are protected from developing pulmonary fibrosis after exposure to asbestos. The investigators hypothesize that Rac1 plays a pivotal role in differentially modulating MAP kinase activation and that this differential activation is critical for TNF-? gene expression in human monocytes stimulated with asbestos. In addition to our in vitro model, we will explore this in alveolar macrophages obtained from asbestosis patients and in an animal model of asbestosis. In Aim 1 we will focus most of our studies on the mechanism(s) by which Rac1 differentially modulates MAP kinase pathways. These studies will also determine if p38 inhibits expression of the ERK kinase by activating a dual specificity phosphatase. The use of wild-type and Rac1 null mice in a murine model of asbestosis will provide biological relevance. In Aim 2, we will first determine if Rac1 modulates TATA-binding protein (TBP) phosphorylation, which is essential for TNF-? gene expression. Since Rac1 has differential effects on MAP kinase activation, we will determine if an increase in p38 and a decrease in ERK activity are necessary for optimal TNF-? production. The investigators will also compare alveolar macrophages from asbestosis patients to normal subjects in regard to Rac1, p38, and ERK activity. The exposure of wild-type and Rac1 null mice to asbestos to determine the effect on the development of interstitial fibrosis will provide additional biological relevance.