Wnt/β-catenin and Hedgehog pathways are involved in the inflammatory effect of Interleukin 18 on rat chondrocytes

To investigate the inflammatory effect of Interleukin 18 (IL-18) on rat chondrocytes and the involvement of Wnt/β-catenin and Hedgehog pathways, the mRNA and protein level of matix-degrading enzymes (MMP-2, 3, 9,13 and aggrecanses) and chondrocyte-specific proteins (Collagen II and aggrecan) were evaluated by qRT-PCR and Western blot, and key protein level of Wnt/β-catenin and Hedgehog pathways including β-catenin, GSK-3β, DKK-1, IHH, SHH, and Gli-2 were evaluated by Western blot. Dickkopf-1 (DKK-1) and Cyclopamine were used as antagonist of Wnt/β-catenin and Hedgehog pathways to perform pathway inhibition tests. In addition, location and expression of β-catenin, GSK-3β, Gli-2 and Smo were assessed by Immunofluorescence microscopy. The results showed up-regulation of matix-degrading enzymes (MMP-2, 3, 9,13 and aggrecanses) and down-regulation of chondrocyte-specific proteins (Collagen II and aggrecan) at both mRNA and protein level and activation of Wnt/β-catenin and Hedgehog pathways in the inflammatory reaction on rat chondrocytes caused by IL-18 treatment was observed. As conclusion, Wnt/β-catenin and Hedgehog pathways are involved in the inflammatory effect of IL-18 in vitro.