Mechanisms of airborne particulate matter induced thrombosis

描述（由申请人提供）：与污染最少的美国城市相比，暴露于环境颗粒物（PM）空气污染的城市最多可导致3.1年的寿命损失。与急性暴露于环境PM相关的死亡率主要是由于缺血性心血管事件。虽然PM暴露与急性心血管事件之间的联系机制尚不完全清楚，但人类和动物数据越来越多地表明，PM引起的肺部炎症和交感神经系统激活引起的止血改变起着因果作用。在该奖项的第一个周期中，我们报道了急性暴露于PM会导致肺巨噬细胞释放白细胞介素-6 (IL-6)，从而加速小鼠动脉血栓形成，这一发现得到了人体研究的支持。在我们的初步数据中，我们观察到pm诱导的钙释放活性钙（CRAC）通道开放和线粒体活性氧（ROS）在pm诱导的IL-6释放中起关键作用。我们还观察到，暴露于吸入PM的小鼠肺部和全身肾上腺素和去甲肾上腺素水平增加，直接证实了人类暴露研究的数据，即PM暴露激活交感神经系统。令人惊讶的是，β受体阻滞剂的使用或β -肾上腺素能受体（β - 2ar）的遗传缺失抑制了pm诱导的IL-6的释放和随后的血栓形成前状态。相反，吸入长效β - 2激动剂（福莫特罗）增加了pm诱导的IL-6释放和由此产生的血栓前状态。这些结果表明，PM对交感神经系统的激活增加了肺泡巨噬细胞IL-6的释放，并导致血栓形成前状态。在目前的提案中，我们制定了3个特定的目标来验证假设，即局部来源的儿茶酚胺刺激β 2AR增加pm诱导的肺泡巨噬细胞IL-6的释放，并通过CRAC通道和ROS介导的cAMP生成的增加导致血栓前状态。在目的1中，我们将确定pm诱导的IL-6释放和由此产生的血栓前状态是否需要肺泡巨噬细胞β 2ARs的激活。在目的2中，我们将确定pm诱导的CRAC通道打开和线粒体ROS的产生是否会放大β 2AR/ camp依赖性IL-6释放的增加。在目的3中，我们将确定肺泡巨噬细胞中自分泌儿茶酚胺信号是否会增加pm诱导的IL-6释放和由此产生的血栓前状态。我们的研究结果提供了一种新的机制范式，将pm诱导的肺部炎症和交感神经系统的激活与导致缺血性心血管事件的血栓形成风险增加联系起来。此外，我们观察到广泛使用的吸入长效β 2AR激动剂增加pm诱导的IL-6释放和血栓形成，这为解释越来越多的证据表明吸入β 2AR激动剂的使用与COPD和哮喘患者死亡率增加相关提供了潜在的机制。

DESCRIPTION (provided by applicant): Exposure to ambient particulate matter (PM) air pollution accounts up to 3.1 years of life lost in the most compared with the least polluted US cities. The mortality associated with acute exposure to ambient PM is largely due to ischemic cardiovascular events. While the mechanisms linking PM exposure with acute cardiovascular events are not fully understood, human and animal data increasingly suggest that PM-induced alterations in hemostasis resulting from lung inflammation and activation of the sympathetic nervous system play causal roles. In the first cycle of this award, we reported that acute exposure to PM causes lung macrophages to release interleukin-6 (IL-6), which accelerates arterial thrombosis in mice, a finding supported by human studies. In our preliminary data we observed that PM-induced opening of Calcium-Release Activated Calcium (CRAC) channels and mitochondrial reactive oxygen species (ROS) play a critical role in PM-induced IL-6 release. We also observed that mice exposed to inhaled PM had increased lung and systemic levels of epinephrine and norepinephrine, directly confirming data from human exposure studies suggesting that PM exposure activates the sympathetic nervous system. Surprisingly, the administration of a beta-blocker or genetic loss of the beta2-adrenergic receptor (beta2AR) inhibited the PM-induced release of IL-6 and the subsequent prothrombotic state. Conversely, inhalation of a long acting beta2-agonist (formoterol) augmented the PM-induced release of IL-6 and the resulting prothrombotic state. These results suggest that activation of the sympathetic nervous system in response to PM augments the release of IL-6 from alveolar macrophages and contributes to resulting prothrombotic state. In the current proposal, we have developed 3 specific aims to test the hypothesis that stimulation of the beta 2AR by locally derived catecholamines augments the PM-induced release of IL-6 from alveolar macrophages and the resulting prothrombotic state through CRAC channel and ROS- mediated augmentation of cAMP production. In aim 1, we will determine whether the activation of alveolar macrophage beta 2ARs is required for the PM-induced release of IL-6 and the resulting prothrombotic state. In aim 2, we will determine whether PM-induced opening of CRAC channels and generation of mitochondrial ROS amplify the beta 2AR/cAMP-dependent augmentation of IL-6 release. In aim 3, we will determine whether autocrine catecholamine signaling in alveolar macrophages augments PM-induced IL-6 release and the resulting prothrombotic state. Our findings provide a novel mechanistic paradigm linking PM-induced lung inflammation and activation of the sympathetic nervous system with an increased risk of thrombosis leading to ischemic cardiovascular events. In addition, our observation that the administration of a widely used inhaled long acting beta 2AR agonist augments PM-induced IL-6 release and thrombosis provides a potential mechanism to explain the increasing body of evidence showing that the use of inhaled beta2-agonists is associated with increased mortality in patients with COPD and asthma. PUBLIC HEALTH RELEVANCE: Exposure to ambient particulate matter (PM) air pollution accounts up to 3.1 years of life lost in the most compared with the least polluted US cities. This application seeks to determine how activation of the sympathetic nervous system worsens lung inflammation and the tendency toward clotting that follows exposure to PM. Understanding these mechanisms will help develop strategies to prevent PM associated deaths and may have important implications for patients with COPD and asthma that use inhaled beta-adrenergic agonists.