Objective
This study applies the data independent acquisition (DIA) technique combined with bioinformatics to identify differential proteins in sepsis patients and performed ELISA method to validate the candidate protein of clinical value, in an attempt to find new biomarkers for the diagnosis and prognosis of sepsis.
Methods
Blood samples from sepsis patients (Sepsis group, n = 50) and healthy individuals (NC group, n = 10) were collected from Affiliated Hospital of Southwest Medical University. Mass spectrometry analysis was designed for 22 sepsis samples (randomly selected) and 10 healthy controls by DIA method, and the obtained differential proteins were subjected to GO annotation, meta-analysis and survival analysis to identify the candidate biomarker protein. ELISA was applied to validate the protein expression in original cohorts. ROC curves based on ELISA data were plotted to discuss the diagnostic and prognostic performance of the candidate protein and several clinical indexes, including C-reactive protein (CRP), procalcitonin (PCT) and lactate (Lac).
Results
DIA data showed that there were 142 differential proteins in the Sepsis group versus the NC group, comprising 36 down-regulated and 106 up-regulated. GO annotation revealed that the differential proteins were significantly enriched in the biological functions involved in immune response, response to stress, inflammatory response, and cell activation. The top 11 proteins with the greatest difference were found according to the p-values in DIA (FUCO2, MGAT1, OAF, AACT, TFRC, CCL14, EXTL2, KLKB1, TETN,CRP,SAA1). Meta-analysis identified significant differential expression of TFRC in the NC versus Sepsis and in the Survival versus Non-survival groups based on GEO database. Survival analysis revealed that the low expression of TFRC indicated a higher survival rate in sepsis patients. ELISA found TFRC concentration in collected clinical samples were significant differential in the NC versus Sepsis and in the Survival versus Nonsurvival groups (p < 0.05). ROC curves gave an AUC of 0.790 for TFRC in distinguishing the normal individuals and sepsis patients, showing good diagnostic performance. Besides, the AUC for TFRC in distinguishing the survivors and deaths was 0.744, indicating good prognostic performance, which was superior to PCT, CRP and Lac.
Conclusion
This study identified TFRC through DIA, bioinformatics and ELISA analyses, which showed differential expression in sepsis patients as well as good diagnostic and prognostic value. TFRC is expected to be a potential biomarker for sepsis.