Linagliptin ameliorated interleukin-29-induced reduction of extracellular matrix genes through the nuclear factor erythroid 2-related factor 2 (Nrf2)/sry-type high-mobility-group box (SOX)-9 axis in an in vitro study on C-28/I2 chondrocytes

Figures & data

Figure 1. Interleukin-29 reduced Col2a1 and Acan genes in human C-28/I2 chondrocytes. (a). Cells were stimulated with 0, 5, 10, 15 ng/mL for 24 hours. Col2a1 and Acan mRNA were measured; (b). Cells were stimulated with 15 ng/mL IL-29 for 6, 12, and 24 hours. Col2a1 and Acan mRNA were measured (#, ##, ###, P < 0.05, 0.01, 0.005 vs. vehicle).

Figure 2. Interleukin-29 reduced the SRY-related high-mobility group box gene-9 expression in human C-28/I2 chondrocytes. Cells were stimulated with 0, 5, 10, 15 ng/mL IL-29 for 24 hours. (a). SOX-9 mRNA; (b). Immunostaining of SOX-9 protein (#, ##, ###, P < 0.05, 0.01, 0.005 vs. vehicle).

Figure 3. Overexpression of SRY-related high-mobility group box gene-9 restored interleukin-29- induced reduction in Col2a1 and Acan gene. Cells were transduced with lentiviral SOX-9, followed by stimulation with 15 ng/mL IL-29 for 24 hours. (a). Western blot analysis revealed successful overexpression of SOX-9; (b). Col2a1 mRNA; (c). Acan mRNA (##, P < 0.01 vs. vehicle; **, P < 0.01 vs. IL-29).

Figure 4. Interleukin-29 increased the expression of dipeptidyl peptidase-4 in human C-28/I2 chondrocytes. Cells were stimulated with IL-29 (0, 10, 15 ng/mL) for 24 hours. (a). DPP-4 mRNA expression; (b). DPP-4 protein expression (#, ##, P < 0.05, 0.01 vs. vehicle).

Figure 5. Linagliptin ameliorated interleukin-29-induced decrease in SRY-related high-mobility group box gene-9. Cells were incubated with 15 ng/mL IL-29 in the presence or absence of Linagliptin (100 nM) for 24 hours. (a). Molecular structure of Linagliptin; (b). SOX-9 mRNA; (c). SOX-9 protein (##, P < 0.01 vs. vehicle; **, P < 0.01 vs. IL-29).

Figure 6. Linagliptin attenuated interleukin-29-induced decrease in Col2a1 and Acan genes. Cells were incubated with 15 ng/mL IL-29 and Linagliptin (100 nM) for 24 hours. (a). Col2a1 mRNA; (b). Acan mRNA (##, P < 0.01 vs. vehicle; **, P < 0.01 vs. IL-29).

Figure 7. Interleukin-29 inactivated nuclear factor erythroid 2-related factor 2 signaling. Cells were stimulated with 0, 10, 15 ng/mL IL-29 for 6 hours. Protein levels of nuclear Nrf2 were measured (##, ###, P < 0.01, 0.005 vs. vehicle).

Figure 8. The protective effects of Linagliptin in the expression of SRY-related high-mobility group box gene-9, Col2a1, and Acan were dependent on nuclear factor erythroid 2-related factor 2. (a). Cells were stimulated with 15 ng/mL IL-29 in the presence or absence of Linagliptin (100 nM) for 24 hours. Levels of nuclear Nrf2 were measured. (b–d). Cells were transfected with Nrf2 siRNA, followed by stimulation with 15 ng/mL IL-29 and Linagliptin (100 nM) for 24 hours. SOX-9 mRNA, Col2a1 mRNA, and Acan mRNA were measured (##, P < 0.01 vs. vehicle; **, P < 0.01 vs. IL-29; $$, P < 0.01 vs. IL-29+ Linagliptin).