Chen Shanze, Yin Renfu, Mutze Kathrin, Yu Youjia, Takenaka Shinji, Königshoff Melanie, Stoeger Tobias
Comprehensive Pneumology Center, Institute of Lung Biology and Disease, Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany.
Department of Pathophysiology, West China School of Preclinical Sciences and Forensic Medicine, Sichuan University, Chengdu, 610041, Sichuan Province, People's Republic of China.
Part Fibre Toxicol. 2016 Jun 21;13(1):33. doi: 10.1186/s12989-016-0144-6.
Carbonaceous nanoparticles (CNP) represent a major constituent of urban particulate air pollution, and inhalation of high CNP levels has been described to trigger a pro-inflammatory response of the lung. While several studies identified specific particle characteristics driving respiratory toxicity of low-solubility and low-toxicity particles such as CNP, the major lung cell type, which initiates and drives that response, remains still uncertain. Since alveolar macrophages (AM) are known to effectively phagocytose inhaled particles and play a crucial role for the initiation of pulmonary inflammation caused by invading microbes, we aimed to determine their role for sterile stimuli such as CNP by profiling the primary alveolar cell compartments of the lung. We exposed C57BL/6 mice to 20 μg CNP by intratracheal instillation and comprehensively investigated the expression of the underlying mediators during a time span of 3 to 72 h in three different lung cell populations: CD45- (negative) structural cells, CD45+ (positive) leukocytes, and by BAL recovered cells.
Bronchoalveolar lavage (BAL) analysis revealed an acute inflammatory response characterized by the most prominent culmination of neutrophil granulocytes from 12 to 24 h after instillation, which declined to basal levels by day 7. As early as 3 h after CNP exposure 50 % of the AM revealed particle laden. BAL concentrations and lung gene expression profiles of TNFα, and the neutrophil chemoattractants CXCL1,-2 and-5 preceded the neutrophil recruitment and showed highest levels after 12 h of CNP exposure, pointing to a significant activation of the inflammation-evoking lung cells at this point of time. AM, isolated from lungs 3 to 12 h after CNP instillation, however, did not show a pro-inflammatory signature. On the contrary, gene expression analysis of different lung cell populations isolated 12 h after CNP instillation revealed CD45-, mainly representing alveolar epithelial type II (ATII) cells as major producer of inflammatory CXCL cytokines. Particularly by CD45- cells expressed Cxcl5 proved to be the most abundant chemokine, being 12 h after CNP exposure 24 (±11) fold induced.
Our data suggests that AM are noninvolved in the initiation of the inflammatory response. ATII cells, which induced highest CXCL levels early on, might in contrast be the driver of acute neutrophilic inflammation upon pulmonary CNP exposure.
碳质纳米颗粒（CNP）是城市空气中颗粒物污染的主要成分，吸入高浓度的CNP会引发肺部的促炎反应。虽然多项研究确定了驱动低溶解度和低毒性颗粒（如CNP）产生呼吸毒性的特定颗粒特征，但引发并驱动该反应的主要肺细胞类型仍不明确。由于已知肺泡巨噬细胞（AM）能有效吞噬吸入的颗粒，并在由入侵微生物引起的肺部炎症起始过程中发挥关键作用，我们旨在通过分析肺的主要肺泡细胞区室来确定它们在诸如CNP这种无菌刺激中的作用。我们通过气管内滴注法让C57BL/6小鼠暴露于20μg CNP，并在3至72小时的时间段内，对三种不同肺细胞群体中潜在介质的表达进行了全面研究：CD45-（阴性）结构细胞、CD45+（阳性）白细胞以及通过支气管肺泡灌洗回收的细胞。
支气管肺泡灌洗（BAL）分析显示出一种急性炎症反应，其特征为在滴注后12至24小时中性粒细胞最为显著地聚集，到第7天降至基础水平。早在CNP暴露后3小时，50%的AM就显示有颗粒负载。TNFα以及中性粒细胞趋化因子CXCL1、-2和-5的BAL浓度和肺基因表达谱先于中性粒细胞募集出现，并在CNP暴露12小时后达到最高水平，表明此时引发炎症的肺细胞有显著激活。然而，在CNP滴注后3至12小时从肺中分离出的AM并未显示出促炎特征。相反，在CNP滴注12小时后分离出的不同肺细胞群体的基因表达分析显示，CD45-细胞（主要代表II型肺泡上皮细胞（ATII））是炎症性CXCL细胞因子的主要产生者。特别是由CD45-细胞表达的Cxcl5被证明是最丰富的趋化因子，在CNP暴露12小时后诱导倍数为24（±11）倍。
我们的数据表明，AM不参与炎症反应的起始。相比之下，早期诱导最高CXCL水平的ATII细胞可能是肺部暴露于CNP后急性中性粒细胞炎症的驱动因素。
