ABSTRACT
BACKGROUND:There is lack of effective diagnostic methods for early knee osteoarthritis. Proteomics refers to the large-scale experimental analysis of proteomes from the overal level of intracel ular protein compositioon, expression and modification, based on which, we can understand protein-protein interaction and relationship, thereby revealing protein functions and cel activity patterns. OBJECTIVE:To apply the isobaric tags for relative and absolute quantitation (iTRAQ) to identify proteins differential y in serums of osteoarthritis Kel gren-Lawrence classification at each stage, and to find out potential molecular markers at each stage of osteoarthritis. METHODS:Sixty patients with knee osteoarthritis were enrol ed, and according to Kel gren-Lawrence (K-L) grading, they were subdivided into K-L 0, II and IV groups. There were 10 males and 10 females randomly selected in each group. Proteins differential y regulated in serums were identified by the stable isotopes 116, 117, 118 of the iTRAQ labeled, reversed-phase column separation, mass spectrometry and Swissport database search, after the serums were subjected to high abundance proteins depletion. Final y, we analyzed the proteins identified by using bioinformatics software. RESULTS AND CONCLUSION:Total y 169 proteins were identified through iTRAQ peptides experiments of different sample tags, Q-star mass spectrum identification and MASCOT library search. 153 proteins were identified as K-L 0 to K-L IV, 153 proteins were identified as K-L 0 to K-L II, and 145 proteins were identified as K-L II to K-L IV. iTRAQ technology may help to identify novel serum markers for early diagnosis of knee osteoarthritis, indicating iTRAQ technology for proteomics serum biomarkers of osteoarthritis study has good application prospect.