PURPOSE: Multiple causative factors complicate the pathogenesis in Graves' orbitopathy (GO). It has been suggested that oxidative stress contributes to the development and progression of GO. Therefore, we investigated the therapeutic effect of resveratrol, a potent antioxidant, upon oxidative stress levels in GO orbital fibroblasts in vitro.
METHODS: Orbital fibroblasts were cultured from orbital connective tissues obtained from GO patients. Intracellular reactive oxygen species (ROS) levels and the expression of heme oxygenase-1 (HO-1), superoxide dismutase (SOD), catalase, and thioredoxin (Trx), were measured after resveratrol treatment. Adipogenesis was induced, and ROS levels were examined during adipogenic differentiation. Western blot assay was performed to evaluate the effects of resveratrol on the expression of antioxidants levels and transcriptional regulators.
RESULTS: Treatment with 30 or 50 μM resveratrol reduced ROS production and HO-1 level induced by oxidative stress. Levels of Cu/Zn-SOD, catalase, and Trx were also reduced, while Mn-SOD increased with 50 μM resveratrol treatment. Resveratrol suppressed adipogenesis, reducing the number of adipocytes and suppressing the accumulation of lipid droplets. Treatment with 50 μM resveratrol also decreased ROS levels during adipogenesis. Expression of the transcriptional regulators phosphor-extracellular signal-regulated kinase and phospho-c-Jun NH(2)-terminal kinase significantly increased after treatment with 50 μM resveratrol, and decreased in response to inhibitors of each protein. Phosphonuclear factor kappa-light-chain-enhancer of activated B cells p65 levels also increased after treatment with 50 μM resveratrol.
CONCLUSIONS: Resveratrol reduced ROS levels and inhibited adipogenesis in GO orbital fibroblasts in vitro. This study supports the potential use of resveratrol in GO treatment.