Combination of nifedipine and subtherapeutic dose of cyclosporin additively suppresses mononuclear cells activation of patients with rheumatoid arthritis and normal individuals via Ca 2+ –calcineurin–nuclear factor of activated T cells pathway

Summary Abnormal Ca 2+ ‐mediated signalling contributes to the pathogenesis of rheumatoid arthritis (RA). However, the potential implication of calcium channel blocker in RA remained unknown. We hypothesized that nifedipine, an L‐type calcium channel blocker, combined with a calcineurin inhibitor, could suppress T cell activation via targeting different level of the Ca 2+ signalling pathway. The percentage of activated T cells and the apoptotic rate of mononuclear cells (MNCs) was measured by flow cytometry. The MNC viability, cytokine production, cytosolic Ca 2+ level and activity of the nuclear factor of activated T cells (NFAT) were measured by enzyme‐linked immunosorbent assay (ELISA). The NFAT‐regulated gene expression, including interleukin (IL)‐2, interferon (IFN)‐γ and granulocyte–macrophage colony‐stimulating factor (GM‐CSF), was measured by real‐time polymerase chain reaction (PCR). We found that the percentage of activated T cells in anti‐CD3 + anti‐CD28‐activated MNC was higher in RA patients. High doses of nifedipine (50 µM) increased MNCs apoptosis, inhibited T cell activation and decreased T helper type 2 (Th1) (IFN‐γ)/Th2 (IL‐10) cytokine production in both groups. The Ca 2+ influx was lower in anti‐CD3 + anti‐CD28‐activated MNC from RA patients than healthy volunteers and suppressed by nifedipine. When combined with a subtherapeutic dose (50 ng/ml) of cyclosporin, 1 µM nifedipine suppressed the percentage of activated T cells in both groups. Moreover, this combination suppressed more IFN‐γ secretion and NFAT‐regulated gene (GM‐CSF and IFN‐γ) expression in RA‐MNCs than normal MNCs via decreasing the activity of NFATc1. In conclusion, we found that L‐type Ca 2+ channel blockers and subtherapeutic doses of cyclosporin act additively to suppress the Ca 2+ ‐calcineurin‐NFAT signalling pathway, leading to inhibition of T cell activity. We propose that this combination may become a potential treatment of RA.