有这样的“朋友”:中性粒细胞在重症肺炎进展中的复杂作用
With Friends Like These: The Complex Role of Neutrophils in the Progression of Severe Pneumonia.
作者信息
Pechous Roger D
机构信息
Department of Microbiology and Immunology, University of Arkansas for Medical SciencesLittle Rock, AR, USA.
出版信息
Front Cell Infect Microbiol. 2017 May 1;7:160. doi: 10.3389/fcimb.2017.00160. eCollection 2017.
Pneumonia is a leading cause of death from infection in the United States and across the globe. During pulmonary infection, clear resolution of host inflammatory responses occurs in the absence of appreciable lung damage. Neutrophils are the first wave of leukocytes to arrive in the lung upon infection. After activation, neutrophils traffic from the vasculature via transendothelial migration through the lung interstitium and into the alveolar space. Successful pulmonary immunity requires neutrophil-mediated killing of invading pathogens by phagocytosis and release of a myriad of antimicrobial molecules, followed by resolution of inflammation, neutrophil apoptosis, and clearing of dead or dying neutrophils by macrophages. In addition to their antimicrobial role, it is becoming clear that neutrophils are also important modulators of innate and adaptive immune responses, primarily through the release of cytokines and recruitment of additional waves of neutrophils into the airways. Though typically essential to combating severe pneumonia, neutrophil influx into the airways is a double-edged sword: Overzealous neutrophil activation can cause severe tissue damage as a result of the release of toxic agents including proteases, cationic polypeptides, cytokines, and reactive oxygen species (ROS) aimed at killing invading microbes. In extreme cases, the damage caused by neutrophils and other innate immune mediators become the primary source of morbidity and mortality. Here, we review the complex role of neutrophils during severe pneumonia by highlighting specific molecules and processes that contribute to pulmonary immunity, but can also drive progression of severe disease. Depending on the identity of the infectious agent, enhancing or suppressing neutrophil-mediated responses may be key to effectively treating severe and typically lethal pneumonia.
在美国及全球范围内,肺炎是感染性死亡的主要原因。在肺部感染期间,宿主炎症反应可在无明显肺损伤的情况下得到明显缓解。中性粒细胞是感染后首批抵达肺部的白细胞。激活后,中性粒细胞通过跨内皮迁移从血管系统进入肺间质,再进入肺泡腔。成功的肺部免疫需要中性粒细胞通过吞噬作用杀死入侵病原体并释放多种抗菌分子,随后炎症消退、中性粒细胞凋亡,巨噬细胞清除死亡或濒死的中性粒细胞。除了其抗菌作用外,越来越明显的是,中性粒细胞也是先天性和适应性免疫反应的重要调节因子,主要通过释放细胞因子以及将更多批次的中性粒细胞募集到气道中来实现。虽然中性粒细胞流入气道通常对于抗击严重肺炎至关重要,但这也是一把双刃剑:过度活跃的中性粒细胞激活会因释放包括蛋白酶、阳离子多肽、细胞因子和活性氧(ROS)等有毒物质而导致严重的组织损伤,这些物质旨在杀死入侵的微生物。在极端情况下,中性粒细胞和其他先天性免疫介质造成的损伤成为发病和死亡的主要原因。在此,我们通过强调有助于肺部免疫但也可能推动严重疾病进展的特定分子和过程,综述中性粒细胞在严重肺炎中的复杂作用。根据感染病原体的特性,增强或抑制中性粒细胞介导的反应可能是有效治疗严重且通常致命的肺炎的关键。