Correlation between interleukin-6 expression in articular cartilage bone and osteoarthritis

This study aimed to investigate the expressional profile of interleukin-6 (IL-6) in articular cartilage bone of osteoarthritis (OA) patients and its correlation with OA. A total of 30 articular cartilage bone samples from knee OA patients, which were collected by knee arthroscopy or articular surgery, comprised the study group, and 30 samples of normal articular cartilage tissue comprised the control group. Both mRNA (messenger ribonucleic acid) and protein levels of IL-6 and matrix metalloproteinase-9 (MMP-9) were measured and compared, and a correlation analysis was performed between the two. The integral optical density (IOD) values of MMP-9 and IL-6 proteins in the study group were 9.21 ± 3.22 and 8.94 ± 3.17, respectively; these were significantly higher (P < 0.05) than those in the control group at 3.14 ± 1.48 and 6.64 ± 1.53, respectively. The IOD values of mRNA transcripts for MMP-9 and IL-6 in the study group were 8.31 ± 2.28 and 8.78 ± 3.43, respectively; these were significantly higher than the values in the control group at 3.52 ± 1.37 and 5.21 ± 1.72 (P < 0.05), respectively. Further, the correlation analysis revealed significantly positive relationships for both protein (r = 0.434, P = 0.001) and mRNA (r = 0.413, P = 0.002) levels between MMP-9 and IL-6. In conclusion, articular cartilage tissues in knee OA patients have higher levels of MMP-9 and IL-6 expression, and these may play a synergistic role in OA pathogenesis.