Knee synovial fluid complement C3-β chain levels correlate with clinical symptoms of knee osteoarthritis

Identification of crucial salivary proteins/genes and pathways involved in pathogenesis of temporomandibular disorders

Temporomandibular disorder (TMD) is a collective term for a group of conditions that lead to impairment of the function of the temporomandibular joint. The proteins/genes and signaling pathways associated with TMD are still poorly understood. The aim of this study was to identify key differentially expressed salivary proteins/genes (DEGs) associated with TMD progression using LC-MS/MS coupled with a bioinformatics approach. The protein–protein interaction network was obtained from the STRING database and the hub genes were identified using Cytoscape including cytoHubba and MCODE plug-ins. In addition, enrichment of gene ontology functions and the Reactome signaling pathway was performed. A total of 140 proteins/genes were differentially expressed. From cluster analysis, a set of 20 hub genes were significantly modulated: ALB, APOA1, B2M, C3, CAT, CLU, CTSD, ENO1, GSN, HBB, HP, HSPA8, LTF, LYZ, MMP9, S100A9, SERPINA1, TF, TPI1, and TXN. Two enriched signaling pathways, glycolysis and gluconeogenesis, and tryptophan signaling pathway involving the hub genes CAT, ENO1, and TPI1 have been identified. The rest of the hub genes were mainly enriched in the innate immune system and antimicrobial peptides signaling pathways. In summary, hub DEGs and the signaling pathways identified here have elucidated the molecular mechanisms of TMD pathogenesis.

Complement C3-α and C3-β Levels in Synovial Fluid But Not in Blood Correlate With the Severity of Osteoarthritis Research Society International Histopathological Grades in Primary Knee Osteoarthritis

BACKGROUND

Primary osteoarthritis (OA) is the most common cause of knee arthritis worldwide. The knee synovial fluid complement C3-β chain levels have been shown to correlate with clinical symptoms of knee OA. It is not known whether the complement C3 in the synovial fluid is derived from the circulation or is produced locally in the knee.

METHODS

Fifty primary OA patients undergoing a total knee arthroplasty procedure were evaluated for biochemical analyses of C3-α and C3-β chains in the synovial fluid and blood plasma. These levels were corelated with the severity of corresponding knee OA based on the Osteoarthritis Research Society International (OARSI) grade.

RESULTS

Both synovial C3-α and C3-β levels correlated significantly with the severity of OA. Neither plasma C3-α levels nor C3-β levels significantly correlated with OARSI grading. Neither synovial C3-α levels nor C3-β correlated significantly with plasma C3-α or C3-β levels, respectively. Synovial C3-α chain and C3-β chain levels were significantly higher in the grade >6 group. In plasma, neither C3-α chain levels nor C3-β chain levels were significantly different between the groups. Neither synovial C3-α nor C3-β levels significantly correlated with plasma erythrocyte sedimentation rate or C-reactive protein levels.

CONCLUSION

In knee primary OA, C3 seems to be produced and released locally into the synovial fluid instead of being derived from blood in the circulation. Synovial C3 levels, but not blood plasma C3, correlate with the histopathological severity of primary OA in the knee. Synovial C3 may be an important factor in the pathogenesis of primary OA clinical symptoms and a potential target for therapeutic intervention.

Proteomic Analysis of Synovial Fibroblasts and Articular Chondrocytes Co-Cultures Reveals Valuable VIP-Modulated Inflammatory and Degradative Proteins in Osteoarthritis

Osteoarthritis (OA) is the most common musculoskeletal disorder causing a great disability and a reduction in the quality of life. In OA, articular chondrocytes (AC) and synovial fibroblasts (SF) release innate-derived immune mediators that initiate and perpetuate inflammation, inducing cartilage extracellular matrix (ECM) degradation. Given the lack of therapies for the treatment of OA, in this study, we explore biomarkers that enable the development of new therapeutical approaches. We analyze the set of secreted proteins in AC and SF co-cultures by stable isotope labeling with amino acids (SILAC). We describe, for the first time, 115 proteins detected in SF-AC co-cultures stimulated by fibronectin fragments (Fn-fs). We also study the role of the vasoactive intestinal peptide (VIP) in this secretome, providing new proteins involved in the main events of OA, confirmed by ELISA and multiplex analyses. VIP decreases proteins involved in the inflammatory process (CHI3L1, PTX3), complement activation (C1r, C3), and cartilage ECM degradation (DCN, CTSB and MMP2), key events in the initiation and progression of OA. Our results support the anti-inflammatory and anti-catabolic properties of VIP in rheumatic diseases and provide potential new targets for OA treatment.