Figure 6
The crosstalk among COX-2, IL-1β and FGF-2 is critical for the initiation and progression of OA.
T/C-28a2 chondrocytes were subjected to fluid shear stress (20 dyn/cm2) or static conditions (0 dyn/cm2) for 48 h in the absence or presence of QNZ (1 μM), SP600125 (5 μM) or HO-1 siRNA for 48 h (a-c) In select experiments, human T/C-28a2 cells were treated with 100 ng/ml IL-1β or 100 ng/ml FGF-2 for 48 h (d). In separate experiments, COX-2+/- transgenic mice at the age of 1 month old were administered with rofecoxib (2 mg/kg/d) for 2 months (e-i). COX-2 mRNA and protein levels were determined by qRT-PCR and western blots, respectively. The total amounts of GAPDH and β-actin served as internal controls in the qRT-PCR and western blots, respectively (a,d,f). mRNA and protein expression of IL-1β and FGF-2 were determined by qRT-PCR and ELISA, respectively. The total amounts of GAPDH and proteins served as internal controls in the qRT-PCR and ELISA, respectively (b,c,h,i). PGE2 and 15d-PGJ2 were determined by corresponding enzyme immunoassay kits (i). The total amount of proteins was used as internal control. The casein activity of MMP-1 was determined by zymography (g upper panel). The tissues of articular cartilage were MMP-1 antibody (e). *, p < 0.05 with respect to the static- or vehicle-treated control. #, p < 0.05 compared with the fluid shear stress treatment. (j) Proposed cascades of signaling events regulating the synthesis of MMP-1 in human chondrocytes that occurs with fluid shear stress, leading to the pathogenesis of OA.
