Neutrophil extracellular traps (NETs) in ventillator induced lung injury

摘要 机械通气(MV)是治疗呼吸衰竭的一种挽救生命的疗法，但也会导致严重的 肺的生理和形态改变，称为呼吸机诱导的肺损伤(VILI)。 炎症是急性肺损伤(ALI)的一个关键组成部分，我们小组和其他人的工作已经 显示MV会导致低氧血症、细胞因子的产生、中性粒细胞募集和肺损伤，甚至 在低潮潮量的时候。虽然中性粒细胞最常与VILI的病理联系在一起，但我们的 拟议的研究旨在证明中性粒细胞的调节、组织修复功能在 VILI的背景和感染的易感性。事实上，MV的免疫调节作用与 关于感染的情况仍不清楚。我们实验室的初步数据显示，MV刺激迅速 但中性粒细胞在空气中的短暂招募、激活和细胞外DNA的沉积， 称为中性粒细胞胞外陷阱(Net)，我们发现这些Net提供保护 抗铜绿假单胞菌感染。特别是，中性粒细胞的这种保护作用 MV后活动持续数天，此时中性粒细胞在 空域。因此，我们提出了MV诱导中性粒细胞活化和Net的新假说。 呼吸道中的沉积构成了对组织损伤的先天免疫反应， 抵消创伤后对感染的敏感性。在具体目标1中，我们将演示 利用耗竭、过继转移和聚合酶链式反应，证明中性粒细胞是MV诱导的Net的来源。 基于网络DNA的检测方法，以及对空中网络的半衰期进行量化。尽管 已知的Net的抗菌特性及其对MV的诱导作用，目前还没有研究 调查了网络对后续感染的影响。因此，在具体目标2中，我们将 在体内和体外实验消融网络和网络组件，以确定它们的影响 关于肺部的细菌感染。因此，使用MV作为一过性中性粒细胞无菌ALI的模型 渗入空气，我们的工作旨在确定迄今尚未确定的保护作用 净产量，从而改进未来临床治疗的设计，以提高肺功能 并防止感染。

ABSTRACT Mechanical ventilation (MV) is a life-saving therapy for respiratory failure but also leads to severe physiological and morphological alterations in the lung, known as ventilator-induced lung injury (VILI). Inflammation is a key component of acute lung injury (ALI), and work from our group and others has shown that MV leads to hypoxemia, cytokine production, neutrophil recruitment, and lung injury, even at low tidal volumes. Although neutrophils are most often associated with the pathology of VILI, our proposed study aims to demonstrate a regulatory, tissue-reparative function of neutrophils in the context of VILI and susceptibility to infection. Indeed, the immunomodulatory effects of MV with regards to infection remain unknown. Preliminary data from our lab show that MV stimulates rapid but transient neutrophil recruitment, activation and deposition of extracellular DNA in the airspaces, termed neutrophil extracellular traps (NETs), and we found that these NETs provide protection against infection with Pseudomonas aeruginosa. In particular, this protective effect of neutrophil activity lasts several days after MV, at a time when neutrophils can no longer be detected in the airspaces. Thus, we propose the novel hypothesis that MV-induced neutrophil activation and NET deposition in the airways constitute an innate immune response to tissue damage that counterbalances post-trauma susceptibility to infection. In Specific Aim 1, we will demonstrate that neutrophils are the source of MV-induced NETs using depletion, adoptive transfer and PCR- based methods to detect NET-DNA, as well as quantify the half-life of NETs in the airspaces. Despite the known antibacterial properties of NETs and their induction in response to MV, no study has investigated the impact of NETs on subsequent infection. Thus, in Specific Aim 2, we will experimentally ablate NETs and NET components, both in vivo and in vitro, to determine their impact on bacterial infection of the lung. Thus, using MV as a model of sterile ALI with transient neutrophil extravasation into the air spaces, our work aims to identify an as-yet-unidentified protective effect of NET production and thereby improve the design of future clinical treatments to increase lung function and prevent infection.