Anti-Collagen Type II polyclonal antibody

Introduction: Osteoarthritis (OA) is a degenerative musculoskeletal disease, which affects approximately the 13% of western population. Nowadays, there is no effective treatment for OA to avoid disease progression or to promote cartilage regeneration. Connexin43 (Cx43) is a transmembrane protein increased in cartilage and synovium from OA patients. Cx43 forms membrane channels that allow the exchange of molecules and ions between two adjacent cells through gap junctions (GJs), or between a cell and its environment through hemichannels. In this study we investigated the involvement of Cx43 and GJ intercellular communication in the degradation of articular cartilage in chondrocytes from patients with OA. Material and methods: Primary chondrocytes were obtained from cartilage from OA and healthy donors. Protein levels were evaluated by western-blot, immunofluorescence and flow cytometry. RNA expression was evaluated by RT-qPCR. A scrape loading/dye transfer assay was used to evaluate cell communication. Cell senescence was analysed by flow cytometry or by light microscopy using beta-galactosidase assay. Results: Cx43 and GJs overactivities were correlated with the progression of OA, by promoting chronic cell dedifferentiation and senescence in vitro assays. We found that Cx43 overexpression activates factors involved in epithelial-to-mesenchymal transition, such as Twist-1. Increased levels of dedifferentiated cells, with high rates of cell proliferation, led to cell senescence via p53/p16(INK4a), activating the senescence-associated secretory phenotype (SASP) and promoting the synthesis and liberation of inflammatory factors, including the interleukin-6 (IL-6). Cx43 downregulation by using small molecules, such as oleuropein, or by genetic edition with CRISPR technology, led to the chondrocyte redifferentiation and an improved phenotype, with increased synthesis of extracellular matrix proteins such as Col2A1 and down-regulating the synthesis of MMPs, inflammation and senescence. Conclusions: Downregulation of Cx43 in OA chondrocytes restores regeneration by activating chondrocyte re-differentiation and decreasing cellular senescence. These results corroborate the use of Cx43 as an effective therapeutic target in order to restore cartilage regeneration and avoid OA progression.

Osteoarthritis (OA) is a common degenerative joint disease that affects people worldwide. The interaction between fibroblast-like synoviocytes (FLSs) and chondrocytes may play a vital role in OA disease pathology. However, the underlying mechanisms by which FLSs exert regulatory effects on chondrocytes still need to be elucidated. Exosomes, small membrane vesicles secreted from living cells, are known to play a variety of roles in mediating cell-to-cell communication through the transferring of biological components such as non-coding RNAs and proteins. Here, we investigate the cellular processes of chondrocytes regulated by FLS-derived exosomes and the mechanisms of action underlying the functions of exosomes in OA pathogenesis. We observed that exosome-mediated cartilage repair was characterized by increased cell viability and migration as well as alleviated matrix degradation. Using chondrocyte cultures, the enhanced cellular proliferation and migration during exosome-mediated cartilage repair was linked to the exosomal lncRNA H19-mediated regulation of the miR-106b-5p/TIMP2 axis. Transfection of miR-106-5p mimics in chondrocytes significantly decreased cell proliferation and migration, promoted matrix degradation characterized by elevated MMP13 and ADAMTS5 expression, and reduced the expression of COL2A1 and ACAN in chondrocytes. Furthermore, we found that TIMP2 was directly regulated by miR-106-5p. Co-transfections of miR-106-5p mimics and TIMP2 resulted in higher levels of COL2A1 and ACAN, but lower levels of MMP13 and ADAMTS5. Together, these observations demonstrated that the lncRNA H19 may promote chondrocyte proliferation and migration and inhibit matrix degradation in OA possibly by targeting the miR-106b-5p/TIMP2 axis. In the future, H19 may serve as a potential therapeutic target for the treatment of OA.