Mechanisms of airborne particulate matter induced thrombosis

描述（由申请人提供）：与污染最轻的美国城市相比，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，我们报道了急性接触 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 诱导的钙释放激活钙 (CRAC) 通道和线粒体活性氧 (ROS) 的开放在 PM 诱导的 IL-6 释放中发挥着关键作用。我们还观察到，暴露于吸入 PM 的小鼠肺部和全身的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，表明 PM 暴露会激活交感神经系统。令人惊讶的是，使用β受体阻滞剂或β2肾上腺素能受体（β2AR）的遗传缺失抑制了PM诱导的IL-6释放以及随后的血栓前状态。相反，吸入长效 β2 激动剂（福莫特罗）会增强 PM 诱导的 IL-6 释放以及由此产生的血栓前状态。这些结果表明，交感神经系统响应 PM 的激活增加了肺泡巨噬细胞的 IL-6 释放，并有助于产生血栓前状态。在当前的提案中，我们制定了 3 个具体目标来测试以下假设：局部衍生的儿茶酚胺刺激 β2AR 会增强 PM 诱导的肺泡巨噬细胞中 IL-6 的释放，并通过 CRAC 通道和 ROS 介导的 cAMP 产生增强而产生血栓前状态。在目标 1 中，我们将确定 PM 诱导的 IL-6 释放以及由此产生的血栓前状态是否需要激活肺泡巨噬细胞 β2AR。在目标 2 中，我们将确定 PM 诱导的 CRAC 通道开放和线粒体 ROS 的产生是否会放大 β2AR/cAMP 依赖性的 IL-6 释放增强。在目标 3 中，我们将确定肺泡巨噬细胞中的自分泌儿茶酚胺信号传导是否会增强 PM 诱导的 IL-6 释放以及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引起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，广泛使用的吸入性长效 β2AR 激动剂会增加 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使用吸入性 β2 激动剂与 COPD 和哮喘患者死亡率增加有关提供了潜在的机制。 公共卫生相关性：与污染最轻的美国城市相比，暴露在环境颗粒物 (PM) 空气污染中的城市最多可减少 3.1 年的寿命。该应用旨在确定交感神经系统的激活如何加剧肺部炎症以及暴露于 PM 后的凝血倾向。了解这些机制将有助于制定预防 PM 相关死亡的策略，并可能对使用吸入 β-肾上腺素能激动剂的慢性阻塞性肺病和哮喘患者产生重要影响。

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.