Fig 2: Impact of KGN on oxidative stress of IL-1ß-stimulated NPCs. (A) Immunofluorescence staining indicated the effect of KGN on intracellular ROS in IL-1ß-stimulated cells. (B–D) The gene expression of Nrf2, Gpx1, and Hmox1 was quantified using RT-PCR, n ?= ?4. (E–F) The effects of KGN on the protein levels of antioxidant enzymes in IL-1ß-stimulated NPCs, n ?= ?3. Data are presented as the mean ?± ?standard deviation. Statistically significant differences are indicated by # where P ?< ?0.05 or ## where P ?< ?0.01 compared to the control (CTRL) group; * where P ?< ?0.05 or ** where P ?< ?0.01 between the indicated groups.

Fig 3: The role of NRF2 in KGN-modulated antioxidant functions in IL-1ß-stimulated NPCs. Prior to exposure to 5 ?ng/mL IL-1ß and 1 ?µM KGN, NPCs were pre-treated with an NRF2-specific inhibitor, ML385. (A) Immunofluorescence staining revealed intracellular ROS in NPCs. (B) The gene expression of Nrf2, Gpx1, and Hmox1 was quantified using RT-PCR, n ?= ?4. (C) The protein levels of NRF2, GPX1, and HO-1 were measured using Western blot, n ?= ?3. (D–E) The gene expression of Col2a1, Acan, Sox9, Mmp13, and Adamts5 was quantified using RT-PCR, n ?= ?4. (C) The protein levels of COL II, ACAN, SOX9, MMP13, and ADAMTS5 were measured using Western blot. Data are presented as the mean ?± ?standard deviation. Statistically significant differences are indicated by # where P ?< ?0.05 or ## where P ?< ?0.01 compared to the control (CTRL) group; * where P ?< ?0.05 or ** where P ?< ?0.01 between the indicated groups.