ObjectiveTo investigate the role of CXCL13 in the onset and development of knee osteoarthritis by observing and comparing the expression of CXCL13 between osteoarthritis and normal synovium. MethodsThe synovium samples were collected from 30 patients with osteoarthritis who received total knee replacement (osteoarthritis group), including 11 males and 19 females with an average age of 66.7 years (range, 62-76 years). The synovium samples were collected from 22 patients without osteoarthritis who underwent traumatic amputation (control group), including 15 males and 7 females with an average age of 51.3 years (range, 48-56 years). The NimbleGen microarray detection was used to defect differentially expressed genes; the immunohistochemistry staining, Western blot, and real-time quantitative PCR (qRT-PCR) were used to detect the expressions of CXCL13 mRNA and protein. ResultsThere were 451 up-regulated genes and 810 down-regulated genes in the 22 885 genes which contained by mRNA gene chip, and CXCL13 gene expression was down-regulated. Immunohistochemistry staining and Western blot assay showed that the expression of CXCL13 protein was significantly lower in osteoarthritis group (0.408 0±0.101 8) than in control group (0.785 9±0.057 9) (t=15.630, P=0.000). qRT-PCR results showed that the expression of CXCL13 mRNA was significantly lower in osteoarthritis group (0.011 7±0.003 2) than in control group (1.041 4±0.129 7) (t=43.634, P=0.000). ConclusionLow expression of CXCL13 in the knee osteoarthritis synovium tissue may be associated with the onset and development of knee osteoarthritis.