Distribution Of Visfatin In Serum And Synovial Fluid And Its Production By Different Joint Tissues In Patients With Osteoarthritis

Objectives:1.To investigate the distribution of visfatin between paired serum and synovial fluid (SF) of osteoarthritis(OA) patients,and in serum from healthy controls.2.To study the ability of visfatin production by different joint tissues and determine the potential sources of visfatin in the joint tissues.Materials and Methods:1.Serum and SF was collected from 32 OA patients(female 21,male 11)(mean age 64.1±13.3 years) who required total knee arthroplasty(TKA) in this study.Knee OA was diagnosed from clinical and radiologic evaluation,based on the American College of Rheumatology criteria,the serum and SF were stroed in -70℃for research.Meanwhile,17 normal controls(female 12,male 5)(mean age 59.5±12.7 years) who showed no clinical and lab measurement features of osteoarthritis before this study were used as healthy controls group.Levels of visfatin in serum and SF were analyzed by enzyme-linked immunosorbent assay(ELISA).The age,height,and body weight of these patients were recorded and the body mass index(BMI) were calculated.We then analyzed the differences between this two groups.Besides,we also analyzed the relationship between the levels of serum and SF visfatin with the age,gender,and BMI. 2.Specimens of cartilage,meniscus,infrapatellar fat pad,synovium and osteophytes were collected from the operations of TKA in 12 patients for ex vivo culture.Different joint tissues were washed in phosphate buffered saline(PBS) and then carefully dissected into small pieces(100-150 mg).One explant of each tissue was placed in each well of 24-well plate.Explantes were first precultured in triplicate for 48 hours and then cultured in fresh serum-free medium and conditioned media were harvested on day 2 and stored at -70℃for research.Statistical analysis:The results are shown as mean±SD values.Statistical analysis was conducted with software SPSS 12.0 for Windows.The differences between patients with OA and healthy controls,female and male were analyzed by independent samples t-test.Comparisons of the levels between matched pairs of synovial fluid and serum samples were made by paired samples t-test.The data normality was tested with Kolmogorov-Smirnov test.The analysis of statistical correlation was performed by the Spearman test of rank correlation.A p value less than 0.05 was considered significant for differences and correlationsResults:1.Serum visfatin concentrations to be higher in OA patients(37.1±15.0 ng/ml) compared to healthy controls(27.3±13.9 ng/ml)(p＜0.05),and SF-visfatin levels(45.5±19.5 ng/ml) exceeded those in paired serum(37.1±15.0 ng/ml)(p = 0.001).The SF visfatin levels significantly correlated with the corresponding values in paired serum samples in OA patients(r = 0.79,p＜0.001) Visfatin levels in serum(OA and healthy controls groups) and in SF(OA group) were not related to the BMI or age.2.Osteophytes released largest amounts of visfatin,while infrapatellar fat pad and synovium were important sources of visfatin among these different joint tissues,,Conclusions:1.The increased serum levels of visfatin in patients with OA suggest that visfatin may be involved in the pathophysiology of OA.Besides,the higher levels of visfatin in SF than paired serum suggest that this adipokine may have local effects in the joint during the process of OA.2.The ability of visfatin production were different in these joint tissues,and osteophytes can be considered as the major source of visfatin in the knee joint in OA patients.