Expression Of Cathepsin K And Its Inhibitor Cystatin C In Synovium Of Osteoarthritis

ObjectiveOsteoarthritis (OA) is a common multi-factor disease, which prevalence increases with age. It is characterized by cataplasis of articular cartilage, aseprtic inflammation of synovium and formation of osteophytes. The complex etiology and pathogenesis have not yet been fully understood. The main point is that protease expression mediated by cytokines was increased because of the systemic or local pathogenic factors, and eventually causes destruction of articular cartilage matrix, in which proteinases play a crucial role in cartilage degeneration. The results show that cathepsin K (cathepsin K) can degradation most of the cartilage matrix components, such as type II collagen, proteoglycans etc. And synovial proliferation response is an important participant in joint structural damage. Detecting expression of cathepsin K and its inhibitor cystatin C both in osteoarthritis and normal synovium, can explore the relationship between cathepsin K and cystatin C and osteoarthritis cartilage degeneration.Materials and Methods1. A collection of 32 cases of synovial specimens from surgical treatment of knee meniscus injury or arthritis. OA patients consistent with the American College of Rheumatology (American College of Rheumatology, ACR) OA diagnostic criteria published in 2001. The specimens were divided into three groups according to osteoarthritis X-ray Kellgren-Lawrence (K-L) grading criteria, normal group (K-L 0 level) of 10 cases,8 males and 2 females, aged 11-36 years (mean 17 years); early osteoarthritis degeneration group (K-LⅠ,Ⅱlevel) of 10 cases,5 males and 5 females, aged 43-62 years (mean agre 50 years); severe degeneration group (K-LⅢ,Ⅳ) of 12 cases,4 males and 8 females, aged 49-80 years (mean age 67 years). And normal group as control, early degeneration and severe degeneration group as the experimental groups.2. Each specimen was divided into two, one of which was immediately fixed with 4% paraformaldehyde, and the other into-80℃refrigerator spare. After 48 hours with 4% paraformaldehyde, synovial specimens went through dehydration, transparent, including wax, then cut into 5μm thick microtome sections. Immunohistochemical SP method colored cathepsin K and cystatin C expression in each group. First antibdies were an rabbit anti-human cathepsin K monoclonal antibody and mouse anti-human cystatin C polyclonal antibody. Took synovial specimens preserved in-80℃of bean size, extracted tissues'total RNA with the Trizol, then reversed transcription into cDNA,β-actin as an internal, amplified the target genes and internal genes, compared whether they were differential on the mRNA level.ResultsSynovial tissue in OA with inflammation in vary degrees were common, and the main performances were the synovial hyperplasia, dark red color changes and villous change. Cathepsin K in synovial tissue was significantly increased, especially in the early stage of osteoarthritis, but only a small amount in the normal synovial specimens. The expression of cathepsin K of osteoarthritis synovial tissue in early osteoarthritis degeneration group and severe degeneration group were significantly higher than normal, and the difference was statistically significant (p<0.01); the average optical density of cathepsin K in severe degeneration group was less than early degeneration group, but no significant difference (p>0.05). From normal to early degeneration group and then to severe degeneration group, the average optical density of cystatin C was gradually increased, but the differences were not statistically significant (p>0.05). On the mRNA level, the mRNA expression of cathepsin K in the two experimental groups were significantly higher than Control group, and the difference was statistically significant (p<0.01); and that of severe degeneration group was higher than early degeneration group, and the difference was statistically significant (p<0.05). The mRNA expression levels of cystatin C in early degeneration group were higher than in normal group and severe degeneration group, significantly different (p<0.01); the mRNA expression levels of cystatin C in normal group and severe degeneration group had no differences (p>0.05).ConclusionsSynovium of joint involves in the pathological process of osteoarthritis. Cathepsin K in synovial cells of osteoarthritis is significantly increased, especially in the early joint degeneration more significant, suggesting its close relationship with. degenerated cartilage, which provides new clues for the prevention and treatment of osteoarthritis. While the endogenous cathepsin K inhibitor cystatin C does not increase with cathepsin K and not play a compensatory role, lack of cystatin C aggravates cathepsin K'damage to articular cartilage.