The present study was designed to investigate the effects of a novel CaMKII inhibitor SMP-114, which was effective in a collagen-induced arthritis model in rats, on rheumatoid synovial fibroblasts.
Rheumatoid synovial fibroblasts (RSF) were cultured under pro-inflammatory (IL-1beta stimulation) and hypoxic conditions. Protein and mRNA expression of HIF-1alpha and the effects of inhibitors of the CaMKII-, PI3K-, and ERK pathway on VEGF and IL-6 production were analyzed.
Stimulation under hypoxic conditions induced higher expression of HIF-1alpha and VEGF mRNA than treatment with either IL-1beta or hypoxia alone. However, incubation with a specific CaMKII inhibitor did not result in reduced VEGF production in RSF.
CaMKII activation has been reported to be involved in HIF-1alpha stabilization, but incubation with SMP-114, a specific CaMKII inhibitor, had no effect on HIF-1-induced VEGF production by rheumatoid synovial fibroblasts.