Cytokine profiles in the joint depend on pathology, but are different between synovial fluid, cartilage tissue and cultured chondrocytes

IntroductionThis study aimed to evaluate whether profiles of several soluble mediators in synovial fluid and cartilage tissue are pathology-dependent and how their production is related to in vitro tissue formation by chondrocytes from diseased and healthy tissue.MethodsSamples were obtained from donors without joint pathology (n¿=¿39), with focal defects (n¿=¿65) and osteoarthritis (n¿=¿61). A multiplex bead assay (Luminex) was performed measuring up to 21 cytokines: Interleukin (IL)-1¿, IL-1ß, IL-1RA, IL-4, IL-6, IL-6R¿, IL-7, IL-8, IL-10, IL-13, tumor necrosis factor (TNF)¿, Interferon (IFN)¿, oncostatin M (OSM), leukemia inhibitory factor (LIF), adiponectin, leptin, monocyte chemotactic factor (MCP)1, RANTES, basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF), vascular growth factor (VEGF).ResultsIn synovial fluid of patients with cartilage pathology, IL-6, IL-13, IFN¿ and OSM levels were higher than in donors without joint pathology (P ¿0.001). IL-13, IFN¿ and OSM were also different between donors with cartilage defects and OA (P <0.05). In cartilage tissue from debrided defects, VEGF was higher than in non-pathological or osteoarthritic joints (P ¿0.001). IL-1¿, IL-6, TNF¿ and OSM concentrations (in ng/ml) were markedly higher in cartilage tissue than in synovial fluid (P <0.01). Culture of chondrocytes generally led to a massive induction of most cytokines (P <0.001). Although the release of inflammatory cytokines was also here dependent on the pathological condition (P