Statistical analysis One way ANOVA and unpaired t test were used to analyze differences in levels of cyto kines. P values less than 0. 05 were considered significant. Results and Discussion We first used mass spectrometry to survey the proteins present in the synovial fluid of patients with knee OA. Synovial fluid proteins from except five OA Inhibitors,Modulators,Libraries patients were sepa rated by 1D or 2D PAGE and then identified by LCMS. Analysis of all five samples identified a total of 111 unique proteins, three of these were keratin proteins, skin proteins most likely obtained as a result of the cutaneous puncture performed during aspiration of the synovial joints. Eliminating these keratins left 108 unique proteins, most of which were detected in all synovial fluid samples analyzed.

Of these, 44 Inhibitors,Modulators,Libraries were identified in a previous proteomic survey of highly abundant proteins in OA synovial fluid. Thus, we confirmed the presence of serine protease inhibitors and of proteins important in regulating proteases that degrade cartilage ECM. We also confirmed the presence of pro teins involved in cartilage and or collagen metabolism, and of proteins involved in inflammation or immunity, findings consistent with the inflamma tion, ECM degradation, and immune cell infiltration that characterize OA. Among the 64 proteins Inhibitors,Modulators,Libraries that we newly identified were histone related proteins, macrophage Inhibitors,Modulators,Libraries related proteins, proinflammatory receptors, and proteins related to the proinflammatory transcrip tion factor nuclear factor kappa B, presumably reflecting the turnover of resident synovial cells or infil trating inflammatory cells.

Our mass spectrometric findings revealed the presence of many molecules associated with inflammation. Although cytokines are also classically associated with inflammation, PAGE based mass spectrometry is not well suited to the detection of small proteins such as cytokines. We therefore used a multiplex immunoassay to measure Inhibitors,Modulators,Libraries levels of inflammatory cytokines and chemo kines in synovial fluid samples from 12 patients with knee OA and 14 patients with RA, as well as in serum samples from 24 patients with knee OA, 23 patients with RA, and 35 healthy individuals. selleck screening library Samples from patients with RA, a classic inflammatory arthritis, were used as a comparator. Figure 1 shows a heatmap of the relative levels of cytokines in the five groups of samples. Compared with cytokine levels in normal sera, cytokine levels in OA sera were generally slightly higher, and those in RA sera were much higher. SAM analysis revealed that levels of several inflammatory cytokines, chemokines, MCP 1, IL 8, MIG, and MIP 1b and growth factors were significantly higher in OA sera than in normal sera, consis tent with previous reports of the association of OA with such inflammatory mediators.