Cartilage Cell Apoptosis Research Articles

The Role of MicroRNAs in the Pathophysiology of Osteoarthritis.

Worldwide, osteoarthritis (OA) is the most common cause of joint pain in older people. Many factors contribute to osteoarthritis' development and progression, including secondary osteoarthritis' underlying causes. It is important to note that osteoarthritis affects all four tissues: cartilage, bone, joint capsule, and articular apparatus. An increasingly prominent area of research in osteoarthritis regulation is microRNAs (miRNAs), a small, single-stranded RNA molecule that controls gene expression in eukaryotes. We aimed to assess and summarize current knowledge about the mechanisms of the action of miRNAs and their clinical significance. Osteoarthritis (OA) is affected by the interaction between miRNAs and inflammatory processes, as well as cartilage metabolism. MiRNAs also influence cartilage cell apoptosis, contributing to the degradation of the cartilage in OA. Studies have shown that miRNAs may have both an inhibitory and promoting effect on osteoporosis progression through their influence on molecular mechanisms. By identifying these regulators, targeted treatments for osteoarthritis may be developed. In addition, microRNA may also serve as a biomarker for osteoarthritis. By using these biomarkers, the disease could be detected faster, and early intervention can be instituted to prevent mobility loss and slow deterioration.

Long Non-Coding RNA Plasmacytomavariant Translocation1 as ceRNA Adsorbs miR-195 to Relieve Osteoarthritis Symptoms

This study aimed to investigate the role of the long non-coding RNA plasmacytomavariant translocation1 (LncRNA PVT1) in the development of osteoarthritis (OA). The study used mice and performed DMM surgery to establish an OA model. PVT1 and miR-195 agomir were inhibited in the knee joints, and cartilage tissue specimens were collected for gene expression analysis, apoptotic protein detection, histopathological observation, and Mankin’s score evaluation. Enzymelinked immunosorbent assay (ELISA) was used to measure the levels of inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in peripheral blood and cartilage tissues. Terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) staining was used to detect cartilage cell apoptosis. The results indicated that the OA group had higher plasmacytomavariant translocation1 (PVT1) expression and lower miR-195 expression than the sham-operated group. PVT1 was found to act as a molecular sponge for miR-195 through a dual-luciferase reporter assay. Knocking down PVT1 or upregulating miR-195 significantly attenuated inflammation and apoptosis in the bone joints of OA mice. This study provides new insights into the mechanism of OA progression and suggests that regulating the PVT1-miR-195 axis may be beneficial for improving the inflammatory microenvironment of cartilage tissue and apoptosis.

Leptin differentially regulate cell apoptosis and cycle by histone acetylation in tibial and vertebral epiphyseal plates.

Leptin showed different apoptosis regulation effects on the chondrocytes from tibial and vertebral epiphyseal plates. However, the mechanism is still unclear. In this study, we tested the protein profile of tibial and vertebral epiphyseal plate chondrocytes with and without leptin stimulation by mass spectrometry and found that the histone acetylation level of tibial chondrocytes was decreased after leptin treatment, while increased in vertebral epiphyseal plates. COIP assay showed that leptin promoted H3, H4 histone acetylation by recruiting CREB binding protein (CBP)/P300 to activate histone acetyl transferases (HATs) activity in vertebral disc chondrocytes. But in tibial plate cartilage cells, leptin did not recruit CBP and p300, thus differently affect the apoptosis of epiphyseal plate chondrocytes. Through explored the mechanism of histone acetylation modulated by leptin, and its effect on cartilage cell apoptosis and cell cycle regulation, This provides a novel target therapy possibility therapeutic approach to for the related disease.

Retraction of: Upregulation of miR-98 Inhibits Apoptosis in Cartilage Cells in Osteoarthritis (doi: 10.1089/gtmb.2016.0011).

Genetic Testing and Molecular BiomarkersVol. 25, No. 10 RetractionOpen AccessRetraction of: Upregulation of miR-98 Inhibits Apoptosis in Cartilage Cells in Osteoarthritis (doi: 10.1089/gtmb.2016.0011)This article retracts the following:Upregulation of miR-98 Inhibits Apoptosis in Cartilage Cells in OsteoarthritisPublished Online:18 Oct 2021https://doi.org/10.1089/gtmb.2016.0011.retractAboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail Genetic Testing and Molecular Biomarkers officially retracts the paper entitled, “Upregulation of miR-98 Inhibits Apoptosis in Cartilage Cells in Osteoarthritis,” by Gui-Long Wang, Yu-Bo Wu, Jia-Tian Liu, and Cui-Yun Li (Genet Test Mol Biomarkers. 2016;20(11)645–653; doi: 10.1089/gtmb.2016.0011).In May of 2021, the authors of the article requested a correction to two figures and supplied new files, but the files were not workable. Over the course of several weeks, the Publisher contacted the authors on multiple occasions requesting new files, however the authors never responded to any of the requests. It is unclear what the specific errors were and if correcting the images in the article would be sufficient enough to properly address the problems. Readers were advised of the original communication from the authors: “In this article, there are picture typesetting errors. Figure 1B Normal group images, Figure 4B Anti-miR-98 NC and Anti-miR-98 miR-98 mimics NC group images misused the images of other groups. We are sorry for this error caused by our carelessness.”Four months after the publication of the Expression of Concern, further questions were raised via the PubPeer platform1 which led the Editor and Publisher to contact the corresponding author yet again, this time asking for the original raw data connected with their research for further evaluation. A response was not received.The lack of the authors' response in both instances, combined with the comments presented on PubPeer, have led to the conclusion that the paper was submitted from a paper mill. This is a violation of the journal's standard protocols and is considered an infraction against the rigorous standards of scientific publishing.The Editor and Publisher of Genetic Testing and Molecular Biomarkers are committed to preserving the scientific literature and the community it serves and does not tolerate any misconduct.Reference1. https://pubpeer.com/publications/57ECA4E2D33D331E74105D17257E13?utm_source=Firefox&utm_medium=BrowserExtension&utm_campaign=Firefox Google ScholarFiguresReferencesRelatedDetailsRelated articlesUpregulation of miR-98 Inhibits Apoptosis in Cartilage Cells in Osteoarthritis1 Nov 2016Genetic Testing and Molecular Biomarkers Volume 25Issue 10Oct 2021 InformationCopyright 2021, Mary Ann Liebert, Inc., publishersTo cite this article:Retraction of: Upregulation of miR-98 Inhibits Apoptosis in Cartilage Cells in Osteoarthritis (doi: 10.1089/gtmb.2016.0011).Genetic Testing and Molecular Biomarkers.Oct 2021.684-684.http://doi.org/10.1089/gtmb.2016.0011.retractcreative commons licensePublished in Volume: 25 Issue 10: October 18, 2021Online Ahead of Print:October 14, 2021PDF download

Downregulation of miR-34a Promotes Proliferation and Inhibits Apoptosis of Rat Osteoarthritic Cartilage Cells by Activating PI3K/Akt Pathway.

ObjectiveTo elucidate the expression and function of miR-34a in rat osteoarthritic cartilage cells, and further to explore its mechanism.Material and MethodsRat model of osteoarthritis was constructed and knee joint cartilage cells were isolated in vitro. Immunocytochemical staining was used for identification. qRT-PCR was used to detect the expression of miR-34a in cartilaginous tissues and cartilage cells. Cartilage cells were divided into blank control (BC), negative control (NC), miR-34a inhibitor (34aI), osteoarthritis model (OA), osteoarthritis model + negative control (OA + NC) and osteoarthritis model + miR-34a inhibitor (OA + 34aI) groups. Cell proliferation was detected by CCK-8 and colony formation assays. Cell apoptosis was studied by flow cytometry and Western blot. PI3K/AKT-pathway-related proteins were also analyzed by Western blot. To further validate the effect of miR-34a on the PI3K/Akt pathway, the cartilage cells were divided into blank control (BC), osteoarthritis model (OA), osteoarthritis model + miR-34a inhibitor (OA + 34aI), osteoarthritis model + PI3K activator (OA + IGF-1) and osteoarthritis model + miR-34a inhibitor + PI3K inhibitor (OA + 34aI + LY) groups, the experiments above were repeated.ResultsThe expression of miR-34a in cartilaginous tissues and cells of osteoarthritis model was significantly higher than that in normal (p < 0.05). After silencing miR-34a gene, the cell proliferation and proteins expression of PI3K/Akt pathway were increased, while the apoptosis rate and expression of apoptosis-related proteins were decreased. Addition of PI3K activator also evidently promoted proliferation and inhibited apoptosis. The protein expression of Bax, Cleaved caspase-3 and Cleaved caspase-9 were dramatically decreased, while the ratios of p-PI3K/PI3K and p-Akt/Akt were increased in OA + IGF-1 group.ConclusionDownregulation of miR-34a regulated proliferation and apoptosis of cartilage cells by activating PI3K/Akt pathway, providing a potential therapeutic approach for the treatment of osteoarthritis.

Gold Nanorods Combined with an Near Infrared Laser for the Establishment of a Precise Posttraumatic Osteoarthritis Model.

Objective: To investigate the innovative application of gold nanorods combined with a laser in posttraumatic osteoarthritis (PTOA) modeling and to discuss the possible mechanisms. Methods: Electron microscopy was used to characterize the gold nanorods. Cell counting kit-8 assay and enzyme-linked immunosorbent assay were used to evaluate cell proliferation and cytotoxicity. An infrared spectroscopy (IR) thermal camera was used to monitor the temperature changes of gold nanorods with or without the laser treatment. Furthermore, western blotting was used to evaluate the expression of related proteins in response to the indicated treatments. Finally, microcomputed tomography (micro-CT) was used to determine the structural changes in knee joints. Changes in the cartilage and various other tissues were assessed by histological examination. Results: The characteristics and biosafety of the gold nanorods were confirmed. Our study showed that gold nanorods combined with the laser inhibited cell viability, but the gold nanorods or laser alone did not affect cell viability. Moreover, the effect on cell viability was time dependent. Similarly, only gold nanorods with the laser caused the apoptosis of cartilage cells and the upregulation of IL-1β, MMP-13 and Comp. We injected gold nanorods and used laser irradiation to develop an osteoarthritis (OA) model. The temperature of the knees in the OA model increased to 60 °C and then remained at approximately 60 °C. As the time increased, gold nanorods combined with the laser caused more injuries and degeneration in the knee joints. Conclusion: OA models that were established using gold nanorods and a laser were precise, controllable, observable and stable and could be an excellent premise for investigating the exact mechanisms underlying OA and exploring new treatment strategies.

Downregulation of long noncoding RNA LOC101928134 inhibits the synovial hyperplasia and cartilage destruction of osteoarthritis rats through the activation of the Janus kinase/signal transducers and activators of transcription signaling pathway by upregulating IFNA1.

Osteoarthritis (OA) is the most common disease of arthritis, a chronic joint disease that is always correlated with massive destruction such as cartilage destruction, inflammation of the synovial membrane, and so on. This study aims to explore the role of long noncoding RNA (lncRNA) LOC101928134 in the synovial hyperplasia and cartilage destruction, more specifically, in the Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway in an OA rat model. Microarray-based gene expression analysis was conducted to screen out the lncRNA differentially expressed in OA and predict the target gene of the lncRNA with the involvement of the signaling pathway through Kyoto encyclopedia of genes and genomes (KEGG) analysis. A model of OA was established and treated with the small interfering RNA LOC101928134/inhibitor of JAK/STAT signaling pathway to investigate the relationship among LOC101928134, IFNA1, and the JAK/STAT signaling pathway in OA. The effect of LOC101928134 on the serum levels of IFNA1, interleukin-1β, and tumor necrosis factor-α, and the apoptosis of synovial and cartilage cells was evaluated. LOC101928134, which was found to be highly expressed in knee joint synovial tissues of OA rats, regulated the expression of IFNA1 gene and inhibited JAK/STAT signaling pathway. Downregulation of LOC101928134 resulted in reduced knee joint synovitis, relived inflammatory damage, and knee joint cartilage damage of OA rats. Besides, synovial cell apoptosis was enhanced upon LOC101928134 downregulation, while cartilage cell apoptosis of OA rats was suppressed. These results demonstrate that downregulation of LOC101928134 suppresses the synovial hyperplasia and cartilage destruction of OA rats via activation of JAK/STAT signaling pathway by upregulating IFNA1, providing a new candidate for the treatment of OA.

The Ex Vivo Time of Fresh Autologous Cartilage Before Transplantation and Cartilage Absorption Degree.

This study aims to determine the relationship between the time of autogenous cartilage in vitro and the degree of absorption in animal experiments. New Zealand white rabbits were randomly divided into 3 groups according to the time of cartilage in vitro: 1-hour group, 2-hour group, and 3-hour group. A volume of ear cartilage was taken and transplanted into the back, according to the group. After 1 month, the volume was taken out and remeasured. Then, these were compared by scanning electron microscopy and hematoxylin and eosin staining. The cartilage bulk absorption level of different groups is different (P < 0.05). There was statistical significance when the 3-hour group was compared with the other 2 groups (P < 0.05). This shows that cartilage volume absorption level becomes higher after 3 hours. Scanning electron microscopy revealed that before and after transplantation, the arrangement of collagen fibers and the gap between these fibers changed. Hematoxylin and eosin staining revealed that there were some morphological changes in chondrocytes, and the degree of chondrocyte apoptosis increased with time, which was accompanied by granulation tissue formation. In addition, the cartilage tissue survived after transplantation. The change in cartilage volume was more obvious after 3 hours of autogenous fresh cartilage transplantation, when compared with that of the first 2 hours. The longer the time of light microscopy was, the longer the apoptosis of cartilage cells, the more serious the destruction of collagen fibers and the cartilage matrix, and the greater the absorption of cartilage and the new chondrocytes.

Inhibition of microRNA-384-5p alleviates osteoarthritis through its effects on inhibiting apoptosis of cartilage cells via the NF-κB signaling pathway by targeting SOX9.

Osteoarthritis (OA), a major cause of pain and disability, is a serious public issue worldwide. Some microRNAs (miRNAs) and SOX9 have been found to be expressed in OA. Therefore, the aim of this study is to investigate effects of microRNA-384-5p (miR-384-5p) on cartilage cell proliferation and apoptosis in mice with OA by targeting SOX9 through the NF-κB signaling pathway. First, bioinformatics was used to predict the SOX9-mediated miRNA (miR-384-5p), and dual luciferase reporter gene assay was conducted to further verify the relationship between miR-384-5p and SOX9. Then, the expression of miR-384-5p, SOX9, and NF-kB in mice modeled with OA was detected. To investigate the specific mechanism of miR-384-5p in OA, mimic and inhibitor of miR-384-5p and siRNA against SOX9 were used to transfect cartilage cells. Finally, proliferation, cell cycle, and cell apoptosis were detected using MTT assay and flow cytometry, respectively. Our results indicated that OA mice exhibited decreased expression of SOX9 and NF-kB but higher miR-384-5p expression. In addition, over-expressed miR-384-5p or silenced SOX9 could inhibit cell proliferation, and block cell cycle entry and induces apoptosis. SOX9 was a target gene of miR-384-5p. The NF-kB signaling pathway was inactivated after overexpression of miR-384-5p. Furthermore, we also observed that the effect of miR-384-5p inhibition was rescued when SOX9 was knocked down. The results support the view that inhibition of miR-384-5p could impede apoptosis and promote proliferation of cartilage cells through activating the NF-κB signaling pathway by promoting SOX9, thereby preventing the development of OA.

An optical probe for detecting chondrocyte apoptosis in response to mechanical injury

Cartilage injury induced by acute excessive contact stress is common and mostly affects young adult. Although early detection of cartilage injury may prevent serious and lifelong arthritic complications, early detection and treatment is not possible due to the lack of a reliable detection method. Since chondrocyte injury and subsequent cell death are the early signs of cartilage injury, it is likely that cartilage cell apoptosis can be used to predict the extent of injury. To test this hypothesis, a near infrared probe was fabricated to have high affinity to apoptotic cells. In vitro tests show that this apoptosis probe has low toxicity, high specificity, and high affinity to apoptotic cells. In addition, there is a positive relationship between apoptotic cell numbers and fluorescence intensities. Using a mouse xiphoid injury model, we found significant accumulation of the apoptosis probes at the injured xiphoid cartilage site. There was also a positive correlation between probe accumulation and the number of apoptotic chondrocytes within the injured xiphoid cartilage, which was confirmed by TUNEL assay. The results support that the apoptosis probes may serve as a powerful tool to monitor the extent of mechanical force-induced cartilage injury in vivo.

Modeling the effect of blunt impact on mitochondrial function in cartilage: implications for development of osteoarthritis.

ObjectiveOsteoarthritis (OA) is a disease characterized by degeneration of joint cartilage. It is associated with pain and disability and is the result of either age and activity related joint wear or an injury. Non-invasive treatment options are scarce and prevention and early intervention methods are practically non-existent. The modeling effort presented in this article is constructed based on an emerging biological hypothesis—post-impact oxidative stress leads to cartilage cell apoptosis and hence the degeneration observed with the disease. The objective is to quantitatively describe the loss of cell viability and function in cartilage after an injurious impact and identify the key parameters and variables that contribute to this phenomenon.MethodsWe constructed a system of differential equations that tracks cell viability, mitochondrial function, and concentrations of reactive oxygen species (ROS), adenosine triphosphate (ATP), and glycosaminoglycans (GAG). The system was solved using MATLAB and the equations’ parameters were fit to existing data using a particle swarm algorithm.ResultsThe model fits well the available data for cell viability, ATP production, and GAG content. Local sensitivity analysis shows that the initial amount of ROS is the most important parameter.DiscussionThe model we constructed is a viable method for producing in silico studies and with a few modifications, and data calibration and validation, may be a powerful predictive tool in the search for a non-invasive treatment for post-traumatic osteoarthritis.

Upregulation of miR-98 Inhibits Apoptosis in Cartilage Cells in Osteoarthritis.

We aimed to investigate the effects of microRNA-98 (miR-98) on apoptosis in cartilage cells of osteoarthritis (OA) patients. Knee cartilage tissue samples were collected from 31 OA patients, 21 autopsies, and 26 amputation patients due to trauma. The clinicopathological data were recorded. Quantitative real-time polymerase chain reaction was performed to compare the miR-98 expression levels from cartilage cells obtained from the OA and non-OA patients. Clinicopathological characteristics of the patients were also analyzed. Primary chondrocytes were separated from cartilage tissues and transfected with plasmids or siRNA to overexpress or inhibit miR-98. Annexin V-PI double staining and TUNEL assays were used to examine apoptosis in the primary chondrocytes after transfection. Finally, a rat OA model was used to confirm the effects of miR-98 on apoptosis in cartilage cells in vivo. Compared with the normal cartilage tissues, miR-98 expression was reduced in the OA cartilage tissues (p < 0.01). The miR-98 expression levels were also significantly correlated with the OA stage (p < 0.05). In vitro, transfection with the miR-98 inhibitor increased apoptosis in the cartilage cells (p < 0.05), and transfection with a miR-98 mimic inhibited apoptosis in cartilage cells (p < 0.05). In the OA rat model, exogenous injection of the miR-98 mimic inhibited apoptosis in the rat cartilage cells thus alleviating OA. MiR-98 expression is reduced in the cartilage cells of OA patients and the overexpression of miR-98 inhibits cartilage cell apoptosis, while inhibition of microRNA-98 leads to cartilage cell apoptosis. These findings provide a theoretical basis for the development of novel targeted therapies for OA.

Expression and significance of apoptosis-related proteins in steroid induced by juvenile rabbit models with avascular necrosis of femoral head

Objective To detect the apoptosis of femoral head cartilage cells and to observe the expression of apoptosis-related proteins in the tissues of the femoral head, as well as to explore the main pathway for regulating the apoptosis in steroid induced by juvenile rabbit models with avascular necrosis of femoral head. Methods The models with avascular necrosis of the femoral head and the control group model were made in New Zealand infancy albino rabbits induced by glucocorticoid(GC). The immunohistochemical method was used to detect the expressions of Caspase-3, Caspase-8, apoptosis protease activating factor-1(apaf-1), calpain-1 in the femoral heads. Results 1.The integrated optical density(IOD) values of Caspase-3 in GC-induced subgroup, the subgroup that was not induced by GC and control group were 25 142.72±21 528.48, 2 069.63±1 096.96 and 301.80±99.66, respectively.The IOD values of Caspase-8 in GC-induced subgroup, the subgroup respectively and the control group were 24 942.63±18 942.99, 2 016.31±1 518.70, 236.85±97.94, respectively.The IOD values of apaf-1 in GC-induced subgroup, the subgroup that was not induced by GC and the control group were 8 514.23±6 384.20, 1 118.49±1 360.59, 95.13±38.05, respectively.The IOD values of calpain-1 in GC-induced subgroup, the subgroup that was not induced by GC and control group were 9 636.71±9 123.81, 1 881.10±3 277.86, 126.71±47.35, respectively.The IOD value differences of the Caspase-3 between GC-induced subgroup and the subgroup that was not induced by GC, the control group were extremely significant(H=11.470, 23.996, P<0.01). The IOD value differences of the Caspase-8, apaf-1, calpain-1 between GC-induced subgroup and the control group were extremely significant(H=22.178, 22.808, 13.553, P<0.01).2.The linear regression analysis results showed that under the joint action of Caspase-8, apaf-1, calpain-1, only the Caspase-8 could significantly predict Caspase-3, and its regression equation regression got significant effect and could explain 40.3% of the variance; while the regression effects of the apaf-1 and calpain-1 to Caspase-3 were not significant. Conclusion Death receptor pathway might play a major regulation role in the apoptotic process of avascular necrosis. Key words: Apoptosis-related proteins; Avascular necrosis; Animal models; Juvenile rabbit; Glucocorticoids

흰쥐의 MIA 유발 무릎 뼈관절염에 대한 840 nm LED의 효과

PURPOSE: The purpose of this study was to evaluate whether light-emitting diodes (LED) irradiation could be effective in a noninvasive, therapeutic device for the treatment of osteoarthritis(OA). METHODS: Twenty-four male Sprague-Dawley rats were divided into four groups: Vehicle control (saline); monosodium iodoacetate-injection (MIA); LED irradiation after MIA injection (MIA-LED); indomethacin-treatment after MIA injection (MIA-IMT). OA was induced by intra-articular injection of 3 mg MIA through the patellar ligament of the right knee. Vehicle control rats were injected with an equivalent volume of saline. The LED was irradiated for 15 min/day for a week after 7 days of MIA treatment. To compare with the effect of LED irradiation, the indomethacin was administrated 20 mg/kg twice a week orally after 7 days of MIA treatment. Knee joints were removed and fixed overnight in 10% neutral buffered formalin and decalcified by EDTA for 2 week before being embedded in paraffin. The assessment of OA induction were monitored by knee movement and radiographic finding. Histologic analysis were performed following staining with hematoxylin and eosin, safranin O-fast green, or toluidine blue, picrosirius red, and histologic changes were scored according to a modified Mankin system. Apoptotic cell in tissue sections was detected using TUNEL method. RESULTS: Radiographic examination could not show the differences between the MIA-treated and the MIA-LED-treated rats. In the histologic analysis, however, LED irradiation prevented cartilage damage and subchondral bone destruction, and significantly reduced mononuclear inflammatory cell infiltration and pannus formation. LED irradiation also reduced apoptosis of cartilage cells, but it prevented apoptosis of infiltrated inflammatory cells in synovium. In addition, LED irradiation showed an increase of collagen production in the meniscus. CONCLUSION: These results suggest that the 840 nm LED irradiation would be a suitable non-thermal phototherapy for the treatment of OA, as a cartilage protection and anti-inflammatory modality.

The cytotoxic effect and injury mechanism of deoxynivalenol on articular chondrocytes in human embryo

This study was to explore the cytotoxic effect and the related injury mechanism of deoxynivalenol (DON) on articular chondrocytes in human embryo. Articular cartilage cells were isolated from knees of human embryo and cultured in DMEM/F12 medium. The cells of the 4th generation were divided into five groups and incubated with varying concentrations of DON as the followings: control group and group with DON of 0.1, 0.2, 0.4, 1.0 µg/ml. The effects of DON were observed 72 hours after incubation. Cell apoptosis was assayed by flow cytometry (FCM) with Annexin V-FITC/PI staining; MMP-13 and PGE2 were detected by ELISA kits; NO was measured by Griess assay with spectrophotometer. Inducible nitric oxide synthase (iNOS) and collagen II in cells were detected by FCM. The expression levels of iNOS, mRNA and collagen II mRNA were measured with RT-PCR. The rates of cell apoptosis in DON groups were 6.78% - 19.05%, which were significantly higher than that in control (1.20%, F = 174.761, P < 0.05). The levels of NO in DON groups were 20.8 - 40.7 µmol/L, which were significantly higher than that in control (10.2 µmol/L, F = 91.966, P < 0.05). The levels of MMP-13 in DON groups were 0.25 - 0.56 µmol/L, which were significantly higher than that in control (0 µmol/L, F = 78.420, P < 0.05). The levels of PGE2 in DON groups were 3.2-20.6 µmol/L, which were significantly higher than that in control (11.6 µmol/L, F = 276.453, P < 0.05). The proportions of cells with positive iNOS in DON groups were 14.8% - 56.8% which were significantly higher than that in controls (7.1%, F = 214.614, P < 0.05). The proportions of cells with positive collagen II in groups with DON of 0.4 µg/ml and 1.0 µg/ml were 56.7% and 52.7%, which were significantly lower than that in control (62.2%, F = 5.134, P < 0.05). The relative absorbance values of iNOS mRNA in DON groups were 1.07 - 1.33, which were significantly higher than that in control (0.62, F = 8.358, P < 0.05). The levels of collagen II mRNA in groups with DON of 0.4 µg/ml and 1.0 µg/ml were 0.83 and 0.82, which were significantly lower than that in control (1.14, F = 7.887, P < 0.05). DON could promote anabolism of NO in articular cartilage cells by which up-regulated the expression of PGE2 and MMP-13, which both promoted resolution of articular cartilage matrix such as collagen II. DON induced apoptosis in articular cartilage cells.

Blood-Induced Joint Disease: The Confluence of Dysregulated Oncogenes, Inflammatory Signals, and Angiogenic Cues

Hemophilia is a congenital disorder that commonly results in musculoskeletal bleeding and orthopedic complications. After an acute joint hemorrhage, there is pain, swelling, and limited motion due to an increase in intra-articular pressure and inflammation. Increases in intra-articular pressure induce mechanical signals that lead to cartilage cell apoptosis. Repeated bleeding results in development of a target joint, which is characterized by painless swelling and limited motion. Blood in the joint space provokes a proliferative disorder termed hemophilic synovitis (HS), with characteristics resembling those of malignant tumors. It has been suspected that one or more of the many components of blood, particularly iron, may be responsible for initiating and sustaining the inflammatory and synovial/vascular cell proliferation response associated with recurrent joint hemorrhages. In this paper, we review the pathogenesis of HS and present experimental data from mice deficient in factor VIII or IX activity in order to clarify the pathways by which blood in the joint space results in arthropathy. Understanding these pathways and cataloguing their key components may identify new targets for therapy of HS.