Serum proteomic-based analysis by iTRAQ of damp-heat impeding syndrome of rheumatoid arthritis

In this study we aim to investigate the characteristic proteins in rheumatoid arthritis (RA) by using iTRAQ-based proteomics approach to explore the possible inherent molecular mechanisms, disease monitoring and therapeutic targets of damp-heat impeding syndrome. The iTRAQ analyses combined with liquid chromatography–tandem mass spectrometry (LC–MS/MS) was performed to compare serum protein expression patterns of damp-heat impeding syndrome of RA with that of cold-damp impeding syndrome of RA, and healthy volunteers. Gene-ontology (GO) analysis of these differentially expressed proteins were performed using WEB based bioinformatics tools (DAVID v6.7, UniProtKB/Swiss-Prot, and Ingenuity Pathway Analysis). Ingenuity Pathways Analysis (IPA) was also used to interpret the interaction network and predominant canonical pathways involved in these differentially expressed proteins. By iTRAQ analyses and mass spectroscopic identification, 6 proteins including FLJ00382, Ig lambda chain V-I region WAH, Myosin-reactive immunoglobulin light chain variable region, C-reactive protein, S100A9, and Cathepsin G were found significantly overexpressed in damp-heat impeding syndrome. Bioinformatics analyses showed that these proteins were involved in inflammatory response, suggesting that RA patients with damp-heat impeding syndrome have severe inflammatory responses and high RA inflammatory activity. This preliminary work provides a better understanding of the proteomic alterations of serum from RA patients with damp-heat impeding syndrome and may provide us insights into the pathophysiology and potential diagnostic biomarkers for early detection, disease monitoring and therapeutic targets for damp-heat impeding syndrome.