Seinen Jolien, Engelke Rudolf, Abdullah Mohammed R, Voß Franziska, Michalik Stephan, Dhople Vishnu M, Dieperink Willem, de Smet Anne Marie G A, Völker Uwe, van Dijl Jan Maarten, Schmidt Frank, Hammerschmidt Sven
Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, Center for Functional Genomics of Microbes, University of Greifswald, Greifswald, Germany.
mSystems. 2021 Mar 2;6(2):e00702-20. doi: 10.1128/mSystems.00702-20.
Mechanically ventilated patients are at risk of contracting pneumonia. Therefore, these patients often receive prophylactic systemic antimicrobial therapy. Intriguingly however, a previous study showed that antimicrobial activity in bronchoalveolar aspirates (here referred to as "sputa") from ventilated patients was only partially explained by antibiotic therapy. Here we report that sputa from these patients presented distinct proteome signatures depending on the presence or absence of antimicrobial activity. Moreover, we show that the same distinction applied to antibodies against , which is a major causative agent of pneumonia. Specifically, the investigated sputa that inhibited growth of , while containing subinhibitory levels of the antibiotic cefotaxime, presented elevated levels of proteins implicated in innate immune defenses, including complement and apolipoprotein-associated proteins. In contrast, -inhibiting sputa with relatively high cefotaxime concentrations or noninhibiting sputa contained higher levels of proteins involved in inflammatory responses, such as neutrophil elastase-associated proteins. In an immunoproteomics analysis, 18 out of 55 antigens tested showed significantly increased levels of IgGs in inhibiting sputa. Hence, proteomics and immunoproteomics revealed elevated levels of antimicrobial host proteins or antigen-specific IgGs in pneumococcal growth-inhibiting sputa, thus explaining their anti-pneumococcal activity. Respiratory pathogens like can cause severe pneumonia. Nonetheless, mechanically ventilated intensive care patients, who have a high risk of contracting pneumonia, rarely develop pneumococcal pneumonia. This suggests the presence of potentially protective antimicrobial agents in their lung environment. Our present study shows for the first time that bronchoalveolar aspirates, "sputa," of ventilated patients in a Dutch intensive care unit were characterized by three distinct groups of proteome abundance signatures that can explain their anti-pneumococcal activity. Importantly, this anti-pneumococcal sputum activity was related either to elevated levels of antimicrobial host proteins or to antibiotics and -specific antibodies. Further, the sputum composition of some patients changed over time. Therefore, we conclude that our study may provide a novel tool to measure changes that are indicative of infection-related conditions in the lungs of mechanically ventilated patients.
机械通气患者有感染肺炎的风险。因此，这些患者常接受预防性全身抗菌治疗。然而，有趣的是，先前的一项研究表明，机械通气患者支气管肺泡灌洗液（此处称为“痰液”）中的抗菌活性仅部分可由抗生素治疗来解释。在此我们报告，这些患者的痰液根据有无抗菌活性呈现出不同的蛋白质组特征。此外，我们表明同样的区别也适用于针对肺炎主要病原体肺炎链球菌的抗体。具体而言，所研究的能抑制肺炎链球菌生长的痰液，虽含有亚抑菌浓度的抗生素头孢噻肟，但与先天免疫防御相关的蛋白质水平升高，包括补体和载脂蛋白相关蛋白。相比之下，头孢噻肟浓度相对较高的抑制肺炎链球菌生长的痰液或无抑制作用的痰液中，参与炎症反应的蛋白质水平较高，如中性粒细胞弹性蛋白酶相关蛋白。在免疫蛋白质组学分析中，所检测的55种肺炎链球菌抗原中有18种在抑制肺炎链球菌生长的痰液中显示IgG水平显著升高。因此，蛋白质组学和免疫蛋白质组学揭示了在抑制肺炎链球菌生长的痰液中抗菌宿主蛋白或肺炎链球菌抗原特异性IgG水平升高，从而解释了它们的抗肺炎链球菌活性。像肺炎链球菌这样的呼吸道病原体可导致严重肺炎。尽管如此，机械通气的重症监护患者肺炎感染风险高，但很少发生肺炎链球菌肺炎。这表明其肺部环境中存在潜在的保护性抗菌剂。我们目前的研究首次表明，荷兰一家重症监护病房中机械通气患者的支气管肺泡灌洗液（“痰液”）具有三组不同的蛋白质组丰度特征，这些特征可解释其抗肺炎链球菌活性。重要的是，这种抗肺炎链球菌的痰液活性与抗菌宿主蛋白水平升高、抗生素或肺炎链球菌特异性抗体有关。此外，一些患者的痰液组成会随时间变化。因此，我们得出结论，我们的研究可能提供一种新工具，用于测量表明机械通气患者肺部感染相关状况的变化。
