1. Introduction
The clinical presentation of mycoplasma pneumoniae (MP) pneumonia (MPP) includes pulmonary symptoms like bronchiolitis and pneumonia even necrotizing pneumonia, thrombosis, and the extra-pulmonary symptoms such as encephalitis, and hemolytic anemia. Persistent MP infection, airway obstruction and airway remodeling have been concerned in human airway epithelium, BALB/c mice, and SMPP children1-3. MPP patients may develop into severe life-threatening pneumonia (severe MPP, SMPP) with features of respiratory failure and acute respiratory distress syndrome, and sequelae such as atelectasis and bronchiectasis due to bronchiolitis/bronchitis obliterans (BO) resulting from airway remodeling 2,4-7.
Due to the side effects of tetracyclines and quinolones, macrolides are used as first‐line antibiotics for the treatment of MPP in young children. However, high presence of macrolide resistance has been reported and MP clearance is difficult even by sensitive antibiotics in refractory MPP (RMPP) and SMPP 2 . Evidence showed the incidence of SMPP has increased in recent years, particularly in East Asia, posing serious threat to children’s health. Corticosteroid could effectively initiate the rapid improvement of clinical symptoms and chest radiographic findings, however its resistant has been reported in some RMPP patients with more severe presentations and more serious radiological finding 8 . In the near ten years, RMPP and SMPP are very common in North China particularly in our hospital, which have much higher sequelae rate mainly BO2,4-6 . Thus, there is an urgent need to discover serum biomarkers and target drugs for monitoring the progress and prevent airway remodeling of SMPP.
Numerous studies have been performed to explore biomarkers in order to detect RMPP or SMPP early. Several have been discovered for the severity evaluation of RMPP or SMPP in children, such as cytokines. However, variations and these biomarkers cannot predict severity or sequelae completely, limiting their clinical applications. In recent years, proteomics has emerged as a powerful method to investigate novel diagnostic and therapeutic targets. The consistency of peptide identification and protein sequence coverage in complex biological samples has been improved substantially with rapid advances in mass spectrometry technology. The label-free proteomic technology has been considered as a superior choice due to its high proteome coverage and labeling efficiency, particularly to obtain information not accessible using two-dimensional electrophoresis, and is employed widely in quantitative proteomics.
In the present study, initially we applied label-free proteomic analysis in general MPP (GMPP) and SMPP children, tried to find out differentially expressed proteins. Fc Fragment of IgG Binding Protein (FCGBP) was the identified protein with the highest expression difference and Enzyme-linked immunosorbent assay (ELISA) was then performed to verify the expression levels in GMPP and SMPP patients, respectively. In order to identify potential useful drugs that can be applied to the treatment of SMPP patients and deepen the understanding of the mechanism of SMPP, we adopt the Connectivity Map tool to identify potential useful drugs. To our knowledge, this is the first such study in the progress of MP infection related disease.