Identification of biomarkers in serum of early rheumatoid arthritis by proteomic methods

Abstract

To discover the biomarkers of early rheumatoid arthritis (RA) patients and healthy person were analyzed by proteomic methods to discover serum biomarkers. Samples of peripheral blood were collected form 10 newly diagnosed active RA patients, 5 males and 5 females, aged 54.3 +/- 12.78, with a disease course of 4.08 +/- 1.9 months, and 10 age and sex matched healthy persons. The samples were divided into 10 groups containing 1 sample of patient serum and 1 sample of healthy serum to undergo. High-molecular-weight protein (HMWP) was enriched by depletion of albumin with HiTrap Blue column and depletion of immunoglobulin G with HiTrap rProtein A column. Low-molecular-weight protein (LMWP) was enriched by C18 absorbent binding and elution. After comparative proteomic analysis, the different protein spots were identified using matrix-assisted laser desorption ionization-time of flight-ionization-mass spectrometry. (MALDI-TOF-MS). Marrow-related protein (MRP) 14, a protein of the S100 family was 100% positive in the RA patient sera and 100% negative in the sera of the healthy controls. MRP8, another protein of the S100 family, was 100% positive in the RA patient sera and 50% positive in the sera of the healthy controls. Ubiquitin was 90% positive in the RA patient sera and 10% positive in the sera of the healthy controls. The levels of apolipoprotein A-I (ApoA-I), serum amyloid A1 and A2 (SAA1/SAA2), and transthyretin of the RA patients were all significantly higher than those of the healthy controls. MRP14/MRP8, SAA1/SAA2 and ubiquitin may play important roles in development of RA and their determination may benefit early diagnosis, evaluation of disease activity and investigation of new therapy targets.