Proteomic analysis of biomarkers predicting the response to triple therapy in patients with rheumatoid arthritis.

Objective: Patients with rheumatoid arthritis (RA) usually receive triple therapy with methotrexate (MTX), leflunomide (LEF) and infliximab (IFX), but nearly one-third of them do not respond to triple therapy. This study aimed to identify biomarkers for predicting the efficacy of triple therapy to optimize personalized treatment of RA.

Methods: All 20 enrolled patients met 2010 ACR/EULAR criteria for RA and were classified into good, moderate and non-responders (GR, MR, NR) for triple therapy. The Responders (R) were defined as the sum of GR and MR. Protein profiles of 4 responders and 4 non-responders were investigated via isobaric tags for relative and absolute quantification (iTRAQ), and differentially expressed proteins (DEPs) with high-confidence peptides were validated in 15 responders and 5 non-responders by parallel response monitoring (PRM).

Results: iTRAQ identified 51 DEPs between responders and non-responders (p < 0.05, fold change >±1.2). The top five up-regulated DEPs were B7Z7M2, A0A087WZR4, Q53FL1, P08254 and G3V2V8, while the top five down-regulated proteins were Q6MZX9, B3KP77, P0DJI9, P0DJI8 and P02787. Targeted mass spectrometry by PRM identified 10 candidate biomarkers, and 3 DEPs including fibrinogen beta chain, epididymal secretory protein Li 282 and testicular tissue protein Li 70 were confirmed as predictive biomarkers.

Conclusion: This study demonstrated the feasibility of exploring biomarkers by applying iTRAQ and PRM mass spectrometry techniques, and a panel of biomarkers were identified to predict clinical response of IFX + MTX + LEF treatment in active RA patients.