Department of Pediatric Pulmonology, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, China.
BMC Microbiol. 2014 Feb 7;14:27. doi: 10.1186/1471-2180-14-27.
Mycoplasma pneumoniae (M. pneumoniae) is one of the major etiological agents for community-acquired pneumonia (CAP) in all age groups. The early host response to M. pneumoniae infection relies on the concerted release of proteins with various biological activities. However, no comprehensive analysis of the secretory proteins has been conducted to date regarding the host response upon M. pneumoniae infection.
We employed the liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based label-free quantitative proteomic technology to identify and characterize the members of the human alveolar epithelial carcinoma A549 cell secretome during M. pneumoniae infection. A total of 256 proteins were identified, with 113 being differentially expressed (>1.5-fold change), among which 9 were only expressed in control cells, 10 only in M. pneumoniae-treated cells, while 55 were up-regulated and 39 down-regulated by M. pneumoniae. The changed expression of some of the identified proteins was validated by RT-PCR and immunoblot analysis. Cellular localization analysis of the secretome data revealed 59.38% of the proteins were considered as "putative secretory proteins". Functional analysis revealed that the proteins affected upon M. pneumoniae infection were mainly related to metabolic process, stress response, and immune response. We further examined the level of one up-regulated protein, IL-33, in clinical samples. The result showed that IL-33 levels were significantly higher in the plasma and bronchoalveolar lavage fluid (BALF) of M. pneumoniae pneumonia (MPP) patients.
The present study provided systematic information about the changes in the expression of secretory proteins during M. pneumoniae infection, which is useful for the discovery of specific biomarkers and targets for pharmacological intervention.
肺炎支原体（M. pneumoniae）是所有年龄段社区获得性肺炎（CAP）的主要病因之一。宿主对 M. pneumoniae 感染的早期反应依赖于具有各种生物学活性的蛋白质的协同释放。然而，迄今为止，尚未针对 M. pneumoniae 感染时宿主的反应进行过针对分泌蛋白的全面分析。
我们采用基于液相色谱-串联质谱（LC-MS/MS）的无标记定量蛋白质组学技术，鉴定并描述了 M. pneumoniae 感染期间人肺泡上皮癌细胞 A549 细胞分泌组中的成员。共鉴定出 256 种蛋白质，其中 113 种表达差异> 1.5 倍，其中 9 种仅在对照细胞中表达，10 种仅在 M. pneumoniae 处理的细胞中表达，而 55 种被 M. pneumoniae 上调，39 种下调。通过 RT-PCR 和免疫印迹分析验证了一些鉴定出的蛋白质的变化表达。分泌组数据的细胞定位分析显示，59.38％的蛋白质被认为是“推定分泌蛋白”。功能分析显示，感染 M. pneumoniae 后受影响的蛋白质主要与代谢过程、应激反应和免疫反应有关。我们进一步检查了一种上调蛋白 IL-33 在临床样本中的水平。结果表明，肺炎支原体肺炎（MPP）患者的血浆和支气管肺泡灌洗液（BALF）中 IL-33 水平显着升高。
本研究提供了有关 M. pneumoniae 感染期间分泌蛋白表达变化的系统信息，这对于发现特定的生物标志物和药理学干预的靶标很有用。
