| Background:Osteoarthritis(OA)is a chronic and progressive joint disorder characterized by degradation of cartilage, menisci and ligaments,synovial inflammation and changes to the subchondral bone. The clinical features of OA are manifested as severe pain, joint stiffness, reduced motion,swelling, and crepitation.OA is associated with reduced quality of life and impaired mobility in the aging population. Among the various joints in the human body, the knee is the most common site of primary OA. It is now well accepted that sex, age, mass body index, and joint injury are all risk factors for OA, but the exact causes of OA are still poorly understood. The socioeconomic impact of OA is high.Acompany with the increase of aging and obesity in the population, costs for OA management will also likely increase in the future. Current treatment options for OA are limited. In addition to physiotherapy, regular exercise and weight loss, pharmacological interventions are restricted to symptomatic relief with local(intraarticular) injections of corticosteroids and/or systemic administration of analgesics and non-steroidal anti-inflammatory drugs(NSAIDs). In the most severe cases, osteotomy(a surgical intervention aimed at changing the load pattern in the joint by altering leg alignment) or joint prosthesis(replacing the joint with an artificial device to take over its function and reduce pain) seem to be the only options to partially restore joint functionality and improve quality of life. OA can result from the dysregulation of biomechanical and biochemical interactions among multiple structures, which can disrupt the normal homeostasis of the joint. For example, progressive cartilage loss, subchondral bone remodelling, formation of osteophytes(bony outgrowths) at the joint margins and synovial inflammation(synovitis) attend in the processe of OA. These factors characterize the pathophysiology of OA and eventually contribute to increasing joint pain and functional impairment.The self repair capacity is very limited once articular cartilage is damaged. Although inflammation can take part in the osteoarthritic processes, it is not the dominant driving force of this disease. Other joint diseases, such as rheumatoid arthritis, are driven by inflammation in the first place, whereas damage to cartilage and bone is a secondary phenomenon. Further understanding of the molecular and cellular basis of OA is fundamental to guide the identification of new therapeutic targets and the development of specific strategies and interventions. The goal of OA research is to search for new therapeutic strategies that could prevent, reduce or stop the progression of the disease or, alternatively, resolve the existing damage to the joint.ObjectiveThe objective of this study is to investigate the effect of BMP-2 on chondrocyte, and the influence of its expression in chondrocyte to TGF beta, Sox9 and ERCC1,to lay a fadation for future study of BMP-2 in Osteoarthritis Chondrocytes in the mechanisms of gene regulation, and provide the basis for gene therapy of osteoarthritis.And we also investigate the bone morphogenetic protein-2(BMP-2) levels in serum and synovial fluid(SF) of patients with primary knee osteoarthritis(OA) and to exam its correlation with radiographic and symptomaticseverity of the disease.Material and Methods:We built a overexpressmodel by transfecting articular cartilage with the plasmid.We observed the morphology of cartilage chondrocyteby Microscope before and after transfection.Weobserved the apoptosis of cartilage chondrocyteby flow cytometry before and after transfection.Enzyme-linked immunosorbent assay was used to observe the expression of collagen II in chondrocytes before and after transfection. Western blot was used to invetigate the protein expressionof TGF beta, Sox9, ERCC1 before and after transfection.Fluorescence quantitative PCR was used to investigate the gene expressionof TGF beta, Sox9, ERCC1 before and after transfection.A total of 37 knee OA patients and 20 healthy controls were enrolled in this study. Knee OA radiographic grading wasperformedaccording to the KellgrenLawrence(KL)grading system by evaluating X-ray changes observed in anteroposterior knee radiography. Symptomatic severity of the disease was evaluated according to the Western Ontario Mc Master University Osteoarthritis Index(WOMAC) scores. BMP-2 levels in serum and SF were determinedusing enzyme-linked immunosorbent assay.Results:The expression of collagen type II after transfection of BMP-2 increased, compared with that of before transfection,P<0.05. The proliferation of chondrocytes transfected with BMP-2 increased, compared with that of before transfection,P<0.05. Apoptosis of chondrocytes can be induced by transfecting with BMP-2. TFGBeta, SOX9, ERCC1 protein expression increased after transfection with BMP-2. TFG Beta gene expression significantly increased after transfection with BMP-2, compared with that of before tansfection,P<0.05. The expression of SOX9 gene significantly increased after transfection with BMP-2 compared with that of before tansfection, P<0.01. ERCC1 gene expression increased after transfection with BMP-2compared with that of before tansfection,P>0.05.Serum BMP-2 level in patients with knee OA was higher than that in healthy controls. Knee OA patients with KL grade 4 showed significantly elevated BMP-2 levels in the serum and SF compared withthose with KL grade 2 and 3. Knee OA patients with KL grade 3 had significant higher SF levels of BMP-2 than those with KL grade 2. BMP-2 levels in theserum and SF of knee OA patients were both positivelycorrelated with KL gradesand WOMAC scores.Conclusion:BMP2 can increased the expression of collagen type II; BMP2 can induce apotosis of chondrocytes. BMP2 can promote the proliferation of chondrocytes.BMP2 can increase the expression of TFGBeta, SOX9, ERCC1 protein and gene.BMP2 levels in serum and SF were closely related to the radiographic and symptomaticseverity of knee OA and may serve as an alternativebiochemical parameter to determine disease severity of primary knee OA. |
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