Serum CXCL10 levels are associated with better responses to abatacept treatment of rheumatoid arthritis.

Objectives: This study aimed to identify therapeutic predictors of abatacept (ABT) treatment in rheumatoid arthritis (RA) in vitro and in patients.
Methods: T cell cytokine, monokine, and chemokine levels in culture supernatants or serum were determined using flow cytometry bead-based immunoassays. CXCL10 mRNA and protein expressions were also assessed using qPCR and ELISA analyses, respectively. In the patient study, 25 ABT-treated patients were analysed retrospectively. The patients were divided into low disease activity (LDA) or non-low disease activity (non-LDA) groups at 24 weeks of ABT treatment. Seven T cell cytokines and CXCL10 levels were compared in these two groups.
Results: Peripheral blood mononuclear cells (PBMC) from healthy donors were stimulated by immobilised anti-CD3 with or without ABT for three days, and the levels of 13 T cell cytokines in culture supernatants were determined. ABT significantly inhibited anti-CD3-induced production of IFN-γ. To examine the effect of these T cell cytokines in rheumatoid synovial cells (RSC), RSCs were stimulated with 10% of culture supernatants from anti-CD3-stimulated PBMCs with or without ABT, and the levels of 23 cytokines were determined. Only CXCL10 was significantly reduced by ABT-treated supernatants. In the patient study, CXCL10 levels at baseline were not different between the LDA and non-LDA groups, whereas CXCL10 levels at 24 weeks were significantly decreased in the LDA group only.
Conclusions: ABT treatment significantly affected IFN-γ and CXCL10 cytokine levels in vitro. In addition, serum CXCL10 levels were associated with better responses in ABT treatment.