title: Global secretome characterization of A549 human alveolar epithelial carcinoma cells during Mycoplasma pneumoniae infection.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Shuxian
authors: S
authors: Li
authors: Xuejing
authors: X
authors: Li
authors: Yingshuo
authors: Y
authors: Wang
authors: Department of Pediatric Pulmonology, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, China. gastate@zju.edu.cn.
authors: Jun
authors: J
authors: Yang
authors: Zhimin
authors: Z
authors: Chen
authors: Shigang
authors: S
authors: Shan
mesh_terms: D002460:Cell Line; D002648:Child; D002675:Child, Preschool; D002853:Chromatography, Liquid; D004847:Epithelial Cells / Q000276:immunology* / Q000382:microbiology*; D020869:Gene Expression Profiling; D006801:Humans; D015151:Immunoblotting; D053858:Metabolic Networks and Pathways; D009177:Mycoplasma pneumoniae / Q000254:growth & development* / Q000276:immunology*; D011506:Proteins / Q000378:metabolism*; D020543:Proteome / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013312:Stress, Physiological; D053719:Tandem Mass Spectrometry
chemical_list: D011506:Proteins; D020543:Proteome