Lung Inflammation and Fibrosis After Asbestosis Exposure is Regulated by Rac1

描述(由申请人提供) 大量接触石棉的患者的肺部反应的特点是持续的、强烈的炎症反应，通常会导致肺纤维化。释放肿瘤坏死因子-？肺泡巨噬细胞在石棉肺患者肺部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自发释放肿瘤坏死因子？它们类似于单核细胞。研究人员的数据显示，单核细胞产生大量的肿瘤坏死因子？当体外用石棉刺激时。与大多数刺激物不同的是，我们的新数据表明，p38 MAP是一种正向调节因子，ERK MAP是一种负向调节因子。生产对石棉刺激的反应。然而，关于连接石棉和肿瘤坏死因子的上游信号通路的数据有限。表情。GTPase rac1是上游的第二信使，在炎症中发挥重要作用。在这方面，我们的新数据也表明，肿瘤坏死因子？在单核细胞中过量表达rac1的产量增加，rac1基因缺失的小鼠在暴露于石棉后免受肺纤维化的影响。研究人员假设，rac1在差异性调节MAPK活性中起着关键作用，这种差异性激活对肿瘤坏死因子？石棉对人单核细胞基因表达的影响。除了我们的体外模型，我们还将在石棉肺患者的肺泡巨噬细胞和石棉肺的动物模型中探索这一点。在目标1中，我们将把大部分研究集中在Rac1差异调节MAP激酶通路的机制上(S)。这些研究还将确定p38是否通过激活双特异性磷酸酶来抑制ERK激酶的表达。在石棉肺小鼠模型中使用野生型和rac1缺失的小鼠将提供生物学上的相关性。在目标2中，我们将首先确定rac1是否调节TATA结合蛋白(TBP)的磷酸化，而TBP是肿瘤坏死因子？基因表达。由于rac1对MAP激酶的激活有不同的影响，我们将确定p38的增加和ERK活性的降低是否是最佳的肿瘤坏死因子？制作。研究人员还将比较石棉肺患者的肺泡巨噬细胞和正常受试者的rac1、p38和ERK活性。野生型和rac1基因缺失的小鼠暴露于石棉，以确定石棉对间质纤维化发展的影响，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.