Differentially expressed proteins in serum immune complexes of rheumatoid arthritis: Analysis by mass spectrometry / 医学研究生学报

ABSTRACT

Objective Rheumatoid arthritis (RA) is a typical type Ⅲ hypersensitivity with a large number of immune complexes (IC) and complement deposits in the synovial tissue , but its specific pathogenesis is not yet clear.This article was to explore the expression of the antigenic profile of serum ICs in RA.Methods ICs were isolated from the serum of 55 patients with RA (41 cases of anti-CCP antibody [+] and 14 cases of anti-CCP antibody [-]), 41 with systemic lupus erythematosus (SLE), and another 41 healthy controls by polyethylene glycol (PEG) precipitation, separated by immunoprecipitation, digested with trypsin in gel, and then subjected to mass spectrometry for identification.The levels of total proteins were compared among different groups using Vennny 2.1.0.The protein expression was considered to be up-regulated when the total protein level of the RA group was >2 times and down-regulated when it was <0.5 times that of the control.Further functional analysis was performed on the differential proteins in RA using the STRING software.Results Totally, 277 proteins were identified in the serum ICs of the RA patients, including 162 in the anti-CCP (+) and 248 in the anti-CCP (-) RA group.Compared with the SLE and healthy control groups, only 129 proteins were found in the RA patients, including 38 in the anti-CCP (+), 109 in the anti-CCP (-) RA group, and 18 in both the two groups.Among the proteins identified in the RA patients and healthy controls, 2 and 11 were up-regulated while 17 and 21 down-regulated in the anti-CCP (+) and anti-CCP (-) RA group, respectively.Conclusion More differentially expressed proteins were identified in the anti-CCP (-) than in the anti-CCP (+) RA patients.The identification of differentially expressed proteins provides a new idea and direction for the investigation of the pathogenesis and new biomarkers of RA.