ABSTRACT

Asthma is a complex airway inflammatory disease that can be roughly classified into eosinophilic phenotype and non-eosinophilic phenotype. Most of the latter manifested as airway inflammation dominated by neutrophil infiltration, namely neutrophil-dominated asthma (NA). Neutrophil extracellular trapping (NETs) is a newly discovered antimicrobial mechanism of neutrophils; however, NETs can not only resist killing pathogenic microorganisms, but also promote tissue damage and autoimmune response. In the present study, we successfully established NA model in C57BL/6 mice and observed the increased formation of NETs. In NA mice, the free DNA abundance, the airway resistance, the cell numbers (total cell number, macrophage number, and neutrophil number), and inflammatory cytokine levels were significantly increased while the lung dynamic compliance was significantly reduced. After DNase I treatment, the above indexes in NA mice were all improved. In NA mice, either treatment with macrophage scavenger or IL-1β neutralizing antibody also improved the above-described indexes. In vitro, in human peripheral blood-derived neutrophils, PMA treatment significantly increased the formation of NETs. Furthermore, in macrophages differentiated from THP-1 monocytes, LPS or isolated NETs both significantly increased the levels of cytokines. In conclusion, NETs can stimulate macrophages to secrete IL-1β, which promotes neutrophils infiltration in the airway; infiltrated neutrophils, in turn, generates NETs, which can amplify the tissue damage caused by NETs and macrophages, inducing and aggravating NA.

摘要

哮喘是一种复杂的气道炎症性疾病，大致可分为嗜酸性粒细胞表型和非嗜酸性粒细胞表型。后者多表现为以中性粒细胞浸润为主的气道炎症，即中性粒细胞为主的哮喘（NA）。中性粒细胞胞外捕获（NETs）是一种新发现的中性粒细胞抗菌机制；然而，NETs不仅可以抵抗杀死病原微生物，还可以促进组织损伤和自身免疫反应。在本研究中，我们成功地在 C57BL/6 小鼠中建立了 NA 模型，并观察到 ​​NETs 的形成增加。在 NA 小鼠中，游离 DNA 丰度、气道阻力、细胞数（总细胞数、巨噬细胞数和中性粒细胞数）、和炎性细胞因子水平显着升高，而肺动态顺应性显着降低。经DNase I处理后，NA小鼠上述指标均有改善。在 NA 小鼠中，无论是用巨噬细胞清除剂还是用 IL-1β 中和抗体治疗也改善了上述指标。在体外，在人外周血来源的中性粒细胞中，PMA 处理显着增加了 NET 的形成。此外，在从 THP-1 单核细胞分化而来的巨噬细胞中，LPS 或分离的 NET 都显着增加了细胞因子的水平。总之，NETs可以刺激巨噬细胞分泌IL-1β，促进中性粒细胞在气道中的浸润；浸润的中性粒细胞反过来产生 NETs，可以放大 NETs 和巨噬细胞引起的组织损伤，诱导和加重 NA。