Label-Free Mass Spectrometry-Based Plasma Proteomics Identified LY6D, DSC3, CDSN, SERPINB12, and SLURP1 as Novel Protein Biomarkers For Pulmonary Tuberculosis

Aim: We aimed to identify new plasma biomarkers for the diagnosis of Pulmonary Tuberculosis (PTB). Background: Tuberculosis is an ancient infectious disease that remains one of the major global health problems. Until now, effective, convenient, and affordable methods for diagnosis of PTB were still lacking. Objective: This study focused on constructing a label-free LC-MS/MS-based comparative proteomics between six tuberculosis patients and six healthy controls to identify Differentially Expressed Proteins (DEPs) in plasma. Methods: To reduce the influences of high-abundant proteins, albumin and globulin were removed from plasma samples using affinity gels. Then DEPs from the plasma samples were identified using a label-free Quadrupole-Orbitrap LC-MS/MS system. The results were analyzed by the protein database search algorithm SEQUEST-HT to identify mass spectra to peptides. The predictive abilities of combinations of host markers were investigated by General Discriminant Analysis (GDA), with Leave-One-Out Cross- Validation (LOOCV). Results: A total of 572 proteins were identified and 549 proteins were quantified. The threshold for DEPs was set as adjusted p-value< 0.05 and fold change ≥1.5 or ≤0.6667, 32 DEPs were found. ClusterVis, TBtools, and STRING were used to find new potential biomarkers of PTB. Six proteins, LY6D, DSC3, CDSN, FABP5, SERPINB12, and SLURP1, which performed well in the LOOCV method validation, were termed as potential biomarkers. The percentage of cross-validated grouped cases correctly classified and original grouped cases correctly classified is greater than or equal to 91.7%. Conclusion: We successfully identified five candidate biomarkers for immunodiagnosis of PTB in plasma, LY6D, DSC3, CDSN, SERPINB12, and SLURP1. Our work supported this group of proteins as potential biomarkers for PTB, and be worthy of further validation.