Apremilast

The ATDC5 chondrocyte cell line was obtained from the Cell Bank of the Cell Engineering Division, RIKEN BioResource Research Center. The cell line was maintained in DMEM/F12 medium (cat. no. 12634010) and supplied with 10% FBS (cat. no. 10100147; both from Gibco; Thermo Fisher Scientific, Inc.) in a 5% CO₂ humidified cell culture incubator at 37℃. For the treatment experiment, the cells were plated in 6-well cell culture plates and treated with IL-17 (10 ng/ml) (R&D Systems, Inc.) in the presence or absence of apremilast (0.5 and 1 µM) (MedChemExpress) at 37°C for 24 h.

AA6216 hydrochloride was synthesized by Meiji Seika Pharma Co., Ltd. Apremilast and roflumilast were purchased from MedChemExpress (Princeton, NJ, USA) and Toronto Research Chemicals (Toronto, Canada), respectively. Nintedanib was purchased from LC Laboratories (Woburn, MA, USA). A mouse TNF-α ELISA kit was purchased from R & D Systems (Minneapolis, MN, USA).