Li-dong Wu

Effects of Alendronate on the Proliferation and Osteogenic Differentiation of MG-63 Cells

Previous studies of the direct actions of bisphosphonates on bone have mainly been limited to their effects on bone-resorbing osteoclasts and little is known about the direct effects of bisphosphonates on osteoblasts. Here we report the direct effects of alendronate on the proliferation and osteogenic differentiation of the MG-63 osteoblast-like cell line. Cell proliferation was determined with the MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay, osteogenic differentiation was evaluated with an alkaline phosphatase bioassay and by analysis of gene expression by reverse transcription-polymerase chain reaction, and the extent of calcium deposition was measured using Alizarin Red S staining. Alendronate significantly increased cell numbers over control values, with the greatest effect at 10−8 M. Alkaline phosphatase activity and gene expression of bone morphogenetic protein 2, type I collagen and osteocalcin were increased after alendronate treatment. Alendronate also stimulated calcium deposition. We conclude that alendronate, apart from inhibiting osteoclastic bone resorption, is also a promoter of osteoblast proliferation and maturation.

Lubricin: a novel potential biotherapeutic approaches for the treatment of osteoarthritis

Osteoarthritis (OA) is a multi-factor disorder of sinovial joints, which characterized by escalated degeneration and loss of articular cartilage. Treatment of OA is a critical unmet need in medicine for regeneration of damaged articular cartilage in elderly. On the other hand, lubricin, a glycoprotein specifically synthesized by chondrocytes located at the surface of articular cartilage, has been shown to provide boundary lubrication of congruent articular surfaces under conditions of high contact pressure and near zero sliding speed. Lubrication of these surfaces is critical to normal joint function, while different gene expressions of lubricin had been found in the synovium of rheumatoid arthritis (RA) and OA. Moreover, mutations or lacking of lubricin gene have been shown to link to the joint disease such as camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP), synovial hyperplasia and failure of joint function, suggesting an important role of lubricin in the pathogenesis of these joint disease. Recent studies demonstrate that administration with recombinant lubricin in the joint cavity would be effective in the prevention of cartilage degeneration in animal OA models. Therefore, a treatment with lubricin which would protect cartilage in vivo would be desirable. This article reviews recent findings with regard to the possible role of lubricin in the progression of OA, and further discusses lubricin as a novel potential biotherapeutic approaches for the treatment of OA.

Increased serum concentrations of visfatin and its production by different joint tissues in patients with osteoarthritis

Abstract Background: The goal of this study was to investigate the distribution of visfatin in paired serum and synovial fluid (SF) samples from patients with osteoarthritis (OA), and in serum from healthy controls. In addition, we wished to determine the potential sources of visfatin in joint tissue. Methods: Twenty-three patients with OA requiring total knee arthroplasty (TKA), 17 healthy subjects and ten donors requiring amputation were included in the study. Concentrations of visfatin in serum and SF were analyzed using an enzyme-linked immunosorbent assay (ELISA). The concentration of visfatin was also measured in conditioned media from cultured joint tissues. Results: We found serum visfatin concentrations to be higher in patients with OA compared to healthy controls (p<0.05), and SF-visfatin concentrations exceeded those in paired serum (p=0.004). In addition, infrapatellar fat pad and synovium were important sources of visfatin, while osteophytes released largest amounts of visfatin. Therefore, osteophytes can be considered a major source of visfatin in the knee joint in patients with OA. Conclusions: These results suggest that visfatin may be involved in the pathophysiology of OA and may have local effects in the joint during the process of OA. Clin Chem Lab Med 2010;48:1141–5.

YKL-40: A Potential Biomarker for Osteoarthritis

Current pharmacotherapy for osteoarthritis (OA) alleviates pain and inflammation but does not protect the articular cartilage from further damage or affect disease progression. Biological markers such as YKL-40 may provide a snapshot of current events in joint tissues, allowing rapid assessment of treatments. This review discusses recent data regarding YKL-40, with an emphasis on the relationship between YKL-40 and OA. The presence of YKL-40 in cartilage and synovium in OA patients correlates with histopathological changes and may reflect local disease activity. In addition, the levels of YKL-40 in serum and synovial fluid also seem to correlate with disease severity. The functional role of YKL-40 is not yet clear, but its production as part of the inflammatory response in articular chondrocytes may modulate the cellular response to pro-inflammatory cytokines, acting to limit connective tissue degradation. Further elucidation of its roles and relationships may enable YKL-40 to act as a useful biomarker in the development of therapies for OA.

Anti-arthritic effects of chlorogenic acid in interleukin-1β-induced rabbit chondrocytes and a rabbit osteoarthritis model

Cartilage degradation is one of the pathological changes of osteoarthritis (OA), and accumulating evidence suggests an excess of matrix metalloproteinases (MMPs) plays a role in this cartilage breakdown. Here, we investigated the effects of chlorogenic acid (CGA) on the mRNA and protein expression of MMPs in interleukin (IL)-1β-induced rabbit chondrocytes and evaluated the in vivo effects of CGA in experimental OA induced by anterior cruciate ligament transection (ACLT) in rabbits. Using quantitative real-time PCR and ELISA to investigate the expression levels of MMP-1, MMP-3, MMP-13, and tissue inhibitors of metalloproteinase-1(TIMP-1) in IL-1β-induced rabbit chondrocytes, we showed that CGA inhibits the expression of these MMPs while increasing TIMP-1 expression, at both the mRNA and protein levels. In addition, IL-1β-induced activation of nuclear factor kappa B (NF-κB) and the degradation of inhibitor of κB (IκB)-α were suppressed by CGA. In rabbits, CGA decreased cartilage degradation as assessed by morphological and histological analyses. The down-regulation of MMP-1, MMP-3, and MMP-13 expression and up-regulation of TIMP-1 expression were also detected in CGA-treated cartilage compared with vehicle-treated cartilage, confirming these findings in an in vivo model. Taken together, these findings indicate that CGA may be considered as a possible candidate agent in the treatment of OA.

Variation patterns of two degradation enzyme systems in articular cartilage in different stages of osteoarthritis: Regulation by dehydroepiandrosterone

BACKGROUND Osteoarthritis (OA) is a multifactorial degenerative joint disease in which the cartilaginous matrix of the articular joint is destroyed in a continuous process. We evaluated mRNA levels of cysteine proteinases/cystatin C system and urokinase plasminogen activator/plasminogen activator inhibitor-1 (uPA/PAI-1) system in articular cartilage and regulation by dehydroepiandrosterone (DHEA) in different stages of osteoarthritis (OA). METHODS One hundred and eight rabbits underwent anterior cruciate ligament transection (ACLT) in the left knee, 54 received weekly intra-articular injections of DHEA (100 micromol/l) 0.3 ml 3 weeks after transaction as DHEA group. Thirty-six rabbits (18 from 2 groups respectively) were euthanized 6, 9, and 12 weeks after ACLT. All left knee joints were assessed by gross morphology and histology, meantime the gene expression from articular cartilage was analyzed. RESULTS Cathepsins and uPA gene increased significantly 6 weeks and reached peak in the 9th week, while declined to extremely low levels 12 weeks after ACLT. Cystatin C decreased accompanied by OA progression, while PAI-1 expressed in the same trend with uPA. Additionally, these 2 enzyme systems were markedly suppressed by DHEA 6 and 9 weeks after ACLT but not in the 12th week. CONCLUSION The variation of these 2 enzyme systems was closely related to the progression of OA, and could be regulated by DHEA especially in the early and medium stages of OA.

Visfatin: a potential therapeutic target for rheumatoid arthritis.

Rheumatoid arthritis (RA) is usually a chronic, systemic inflammatory disorder primarily targeting the synovium and articular cartilage. It is incurable, costly and responds poorly to treatment. Methotrexate alone or in combination with conventional and/or biological disease-modifying antirheumatic drugs (DMARDs) is often used to induce remission of active disease. The effectiveness of treatment is, however, limited and most patients develop chronic disability and require total knee arthroplasty or total hip replacement. Emerging therapies targeting specific cytokines and growth factors in the RA inflammatory cascade offer potent new means of modifying disease activity. Recently, increased concentrations of adipokines, including visfatin, mainly produced by adipocytes in serum and joint synovial fluid, were found in RA patients. Visfatin has important pro-inflammatory and catabolic roles in RA pathogenesis and is now being studied as a potential therapeutic target for RA. Here we discuss the relationship between visfatin and RA and its potential as a therapeutic target for RA.

Sphingosine-1-phosphate: a potential therapeutic target for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease, which has as its primary target, the synovial tissues and articular cartilage. The current pharmacological treatment of RA includes non-steroidal anti-inflammatory drugs, corticosteroids, and disease-modifying anti-rheumatic drugs. Newer biological agents that work by inactivation of proinflammatory cytokines are available for treatment of RA. Sphingosine-1-phosphate (S1P) is a bioactive lipid that is generated from phosphorylation of sphingosine by activation of sphingosine kinase, and has been implicated as an important mediator in pathophysiological processes, including cell growth, differentiation, migration and survival, and angiogenesis. Several studies have explored the role of S1P in the pathogenesis of RA. The aim of this article was to review the biology and distribution of S1P, together with its role in RA, and to discuss its potential as a therapeutic target for RA.

Effects of Diallyl Sulphide in Chondrocyte and Cartilage in Experimental Osteoarthritis in Rabbit

Diallyl sulphide (DAS) is known for its antioxidant, anticancer and detoxifying properties. The aim of this study was to investigate the effect of DAS on rabbit articular chondrocytes and cartilage in experimental osteoarthritis (OA) induced by anterior cruciate ligament transection (ACLT). DAS inhibited matrix metalloproteinase‐1 (MMP‐1), MMP‐3 and MMP‐13 expression in interleukin‐1beta (IL‐1β)‐induced chondrocytes. In an in vivo study, DAS ameliorated cartilage degradation as assessed by morphological and histological examination. Messenger RNA expression of MMP‐1, MMP‐3, MMP‐13 and IL‐1β was inhibited by DAS in cartilage. In addition, DAS increased the collagen II level in cartilage. The results suggest that DAS may protect cartilage in the development of OA. Copyright

Thymoquinone inhibits matrix metalloproteinase expression in rabbit chondrocytes and cartilage in experimental osteoarthritis

Thymoquinone (TQ) is the main constituent of Nigella sativa oil, which has been traditionally used against arthritis in the Middle East. In this study, we investigated the effect of TQ against matrix metalloproteinase (MMP) expression in both rabbit chondrocytes and animal mode of osteoarthritis (OA) induced by anterior cruciate ligament transection and tested whether or not nuclear factor kappa B (NF-κB) was involved in this process. TQ down-regulated MMP-1, MMP-3 and MMP-13 expression and up-regulated tissue inhibitors of metalloproteinase-1 expression as assessed by quantitative realtime polymerase chain reaction. In addition, NF-κB p65 protein level as well as its translocation induced by interleukin-1β were inhibited by TQ. Our findings suggest the potential of TQ in the treatment of OA.