Study On The Mechanisms Of ADAMTS-modulated Cartilage Degenerantion And Matrix Degradation In Human Osteoarthritis

Cartilage degeneraion-causing diseases, characterized by cartilage destruction, synovitis and subchondral bone alteration, can be triggered by inflammation, immune system disorders and trauma, making disability of the joint. However, in talking to osteoarthritis (OA), reports have been recently heard that the inhabilitation of hyaline cartilage cannot be achieved neither through oral supplement and nutrition drugs (glucosamine chondroitin, chondroitin sulfate) and intra-articular injection of lubricants (sodium hyaluronate in various forms) nor arthroscopic cartilage transplantation and micro fracture approaches in clinically specific approaches. Therefore, mechanisms associated with degeneration and novel targets for intervention remain the mainstays of OA treatment.Extracellular matrix degradation (ECM) breakdown is a cardinal event of cartilage degeneraion-causing diseases. The vital enzymes triggering structural damage, including matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), represent an attractive target in OA. Currently, an increasing number of studies related to MMPs-mediated OA have been identified. To the contrast, limited strategies have been discussed to the ADAMTS-modulated catabolic effects, and the molecular pathways involved in underlying pathobiology using Outerbridge Classification via arthroscopy are under study to circumvent these mechanisms.The objective of these present studies towards ADAMTS-mediated cartilage degeration in OA is to elucidate the molecular mechanisms of ADAMTS involed in crosstalk of signaling pathways in OA, simultaneously promoting new therapies able to clinical drugs application and pragmatic’entry point’ for cartilage degeneration through interventional therapyMETHODS:In Part 1, OA patients were evaluated using Outerbridge Classification via arthroscopy. Histopathological assessment were performed to identify the specimens. The expression of cartilage biomarkers, SOX9 and ADAMTSs were also examined. The association between SOX9 production and ADAMTSs, was established on full-depth cartilage biopsies. In Part 2, Human OA chondrocytes were obtained from patients who were undergoing arthroplasty surgery. miR-30a and ADAMTS-5 expression from pairs of OA and relatively normal tissues were detected and immunohistochemistry and analyzed for correlation. Cultured human chondrocytes were treated with IL-1β. Luciferase assay and Chromatin immunoprecipitation (ChIP) were performed to identify the transcriptional factor that regulates miR-30a expression. In Part 3, Human chondrocytes in vitro were treated with bFGF. Immunoblotting were performed to determine the protein expression. Tube formation experiment and micro-CT were applied to examine angiogenesis or degrees of cartilage destruction in OA.RESULTS:1) ADAMTSs levels were diminished in stage 1, while a gained significant increase was observed in the progressive stage of OA. SOX9 was upregulated in stage 1 and suppressed in the later stage of cartilage, particularly in cartilage of severe grade; In addition, SOX9 diminished ADAMTSs levels; SOX9 was negatively related to ADAMTSs production and was positively related to cartilage biomarkers expression.2) miR-30a inhibited ADAMTS-5 expression through directly targeting its 3’ untranslated region. miR-30a expression was downregulated in OA patients and was correlated with ADAMTS-5 expression negatively and Hospital for Special Surgery (HSS) scores positively. IL-1β suppressed miR-30a expression by recruiting the activator protein (AP-1) transcription factor c-jun/c-fos to miR-30a promoter. IL-1β-induced AP-1 expression regulated ADAMTS-5 expression and cartilage matrix degradation via miR-30a in human chondrocytes.3) Overexpression of Runx2 in miR-93-transfected chondrocytes effectively rescued the suppression of ADAMTS activity caused by miR-93. Knockdown of Runx2 mimicked the ADAMTS production. bFGF suppressed the miR-93 expression and induced Runx2 activation and pro-catabolic responses by recruiting NF-κB p65 to the miR-93 promoter. Moreover, miR-93 production was diminished in OA patients and was correlated with Runx2 expression inversely, ADAMTSs, which was upregulated in OA patients. bFGF/NF-KB could promote the angiogenesis through inhibition of miR-93 exression. Besides, degrees of OA cartilage destruction were aggravated by intra-articular injection of bFGFR inhibitor and/or miR-93 in mice.CONCLUSIONS:The current data indicated SOX9 upregulation may modulate ADAMTSs suppression in the early stage, identifying this stage as the generation period. In addition, indicating that SOX9 could be a potential agent for the management of human OA at the early stage. IL-1β/AP-1/miR-30a/ADAMTS-5 pathway contributes to IL-1β-induced cartilage matrix degradation in human OA chondrocytes. miR-30a may act as a pivotal regulator of homeostasis. bFGF/NF-κB signaling may be of the utmost importantance in ADAMTS-mediated cartilage degeneration, and that miR-93 activation may be a useful strategy for OA treatment.