Effect of tanshinone IIA in an in vitro model of Graves’ orbitopathy

PURPOSE. We investigated the therapeutic effect of nontoxic concentrations of tanshinone IIA (TanIIA) from Salvia miltiorrhiza in primary cultures of orbital fibroblasts from Graves’ orbitopathy (GO).

METHODS. The effect of TanIIA on IL-1β–induced proinflammatory cytokine (IL-6, IL-8, MCP-1) expression was determined by real-time PCR. Antioxidant activity was investigated by measuring intracellular reactive oxygen species (ROS) generation stimulated by cigarette smoke extract (CSE) and heme oxygenase-1 (HO-1) expression. To evaluate antiadipogenic activity, fibroblasts were subjected to a differentiation protocol, including peroxisome proliferator activator gamma (PPARγ) agonist, for 10 days, and exposed to TanIIA during adipocyte differentiation. Differentiated cells were stained with Oil Red O, and the expression of adipogenesis-related factors, PPARγ, and CCAAT-enhancer-binding proteins (C/EBP) α and β were determined by Western blot.

RESULTS. Expression of IL-6, IL-8, and MCP-1 mRNA was inhibited by TanIIA pretreatment in a dose-dependent manner in GO orbital fibroblasts (P < 0.05). Tanshinone IIA decreased CSE- or H₂O₂-induced ROS levels in a dose-dependent manner and upregulated HO-1 protein expression in a time- and dose-dependent manner (P < 0.001). Treatment of orbital fibroblasts with TanIIA increased phosphorylated extracellular signal-regulated kinase (pERK), and an ERK inhibitor significantly blocked TanIIA-induced HO-1 upregulation. Adipogenesis was inhibited by TanIIA in a dose-dependent manner (P < 0.001), as evidenced by Oil Red O stain and decreased PPARγ and C/EBPα expression in Western blot analysis.

CONCLUSIONS. Our study results suggest that TanIIA possesses significant anti-inflammatory, antioxidant, and antiadipogenic effects in primary orbital fibroblasts. These results provide the basis for further study of the potential use of TanIIA to treat GO. Tanshinone IIA showed significant anti-inflammatory, antioxidant, and antiadipogenic effects in primary orbital fibroblasts from Graves’ orbitopathy patients. These results provide the basis for further study of the potential use of tanshinone IIA to treat Graves’ orbitopathy.