Effect of BMI on the constitutive expression of TGFβ, aggrecan, MMP-13, type 2 collagen, IGF-1, TIMP-2 and COX-2 in chondrocytes obtained from OA patients. mRNA levels were determined 24 hours after culture medium change by quantitative real-time PCR. For every patient, experiments was performed in triplicate. Results were expressed as mean ± standard error of the mean of variation found in obese osteoarthritis (OA) patients (body mass index (BMI) >30 kg/m2, n = 13) over values obtained in normal or overweight OA patients (BMI <30 kg/m2, n = 12). * P < 0.05 between obese and normal or overweight patients. COX-2, cyclooxygenase-2; IGF-1, insulin growth factor-1; MMP, matrix metalloproteinase; TGFβ, transforming growth factor-β; TIMP, tissue inhibitor of metalloproteinase.