The aim of this study was to investigate the efficacy and safety of YM-58483, a small molecular antagonist of Ca2+ release-activated Ca2+ (CRAC) channels, for the treatment of rheumatoid arthritis (RA), in vivo and ex vivo.
YM-58483 was continuously injected subcutaneously in a collagen-induced arthritis (CIA) mouS.E.M.odel using an implanted osmotic pump. The severity of CIA was evaluated using the following parameters: body weight, hind paw volume, clinical score, histological analysis, cytokine levels, Ca2+ influx, and specific IgG production. The efficacy of long-term application of YM-58483 was also verified ex vivo in RA patient-derived peripheral blood monocytes.
Assessment of the clinical severity of CIA, cytokine profile in serum and joint protein extracts, and specific IgG production showed that continuous application of YM-58483 suppressed synovial inflammation by inhibiting immune cell activity. Chemical screening and hepatography indicated that long-term subcutaneous delivery of YM-58483 was safer than oral administration for systemic application. Moreover, constant preincubation with YM-58483 at an IC50 of 0.1–1 nM altered proinflammatory cytokine production ex vivo in peripheral T cells derived from RA patients.
Our findings suggest that continuous long-term application of appropriate CRAC inhibitors such as YM-58483 is a potential therapeutic strategy for global immunosuppression in RA.