Figure 3

Validation of gene expression of stimulated chondrocytes by real-time RT-PCR. Semi-quantitative real-time RT-PCR of selected genes that were differentially expressed in chondrocytes stimulated with supernatant of a synovial fibroblast cell line derived from a patient with rheumatoid arthritis (RASFsn) as determined by microarray analysis was performed. Real-time RT-PCR gene expression analysis determined that the expression of cyclooxygenase-2 (COX-2), interferon-α inducible protein-6–16 (IFI-6–16) and chemokine (C-X-C motif) receptor 4 (CXCR4) was significantly induced during stimulation of cartilage-like cultures with RASFsn compared with stimulation with supernatant of a synovial fibroblast cell line derived from normal donor (NDSFsn). The gene expression of steroid sulfatase (STS), chondroitin sulfate proteoglycan 2 (CSPG2), cartilage oligomeric matrix protein (COMP) and thioredoxin interacting protein (TXNIP) was significantly repressed during stimulation with RASFsn. Consistent changes were observed between real-time RT-PCR and microarray analysis for all genes examined. The expression of selected genes was calculated as the percentage of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression. The mean of each triplicate well of both experimental groups is plotted and the error bars represent SD. For statistical analysis, Students t-test was applied (*, P ≤ 0.05; ***, P ≤ 0.001).