Osteoarthritis year 2010 in review: pharmacological therapies

Integrin αVβ3 Signaling in the Progression of Osteoarthritis Induced by Excessive Mechanical Stress

Osteoarthritis (OA) is believed to be linked with cartilage degeneration, subchondral bone sclerosis, and synovial inflammation that lead to joint failure, and yet treatment that can effectively reverse the pathological process of the disease still not exists. Recent evidence suggests excessive mechanical stress (eMS) as an essential role in the pathogenesis of OA. Increased levels of integrin αVβ3 have been detected in osteoarthritic cartilage and were previously implicated in OA pathogenesis. However, the role of integrin αVβ3 in the process of eMS-induced OA remains unclear. Here, histologic and proteomic analyses of osteoarthritic cartilage in a rat destabilization of the medial meniscus model demonstrated elevated expression of integrin αVβ3 as well as more serious cartilage degeneration in the medial weight-bearing area. Furthermore, results of in vitro study demonstrated that eMS led to a significant increase of integrin αVβ3 expression and phosphorylation of downstream signaling molecules such as FAK and ERK, as well as upregulated expressions of inflammatory and degradative mediators. In addition, we found that inhibition of integrin αVβ3 could alleviate chondrocyte inflammation triggered by eMS both in vivo and in vitro. Our findings suggest a central role for upregulation of integrin αVβ3 signaling in OA pathogenesis and demonstrate that activation of integrin αVβ3 signaling in cartilage contributes to inflammation and joint destruction in eMS-induced OA. Taken together, our data presented here provide a possibility for targeting integrin αVβ3 signaling pathway as a disease-modifying therapy.

Stem cell-based therapies for temporomandibular joint osteoarthritis and regeneration of cartilage/osteochondral defects: a systematic review of preclinical experiments

OBJECTIVES

The aim of this systematic review was to assess the effects of stem cell-based therapies on the treatment of Temporomandibular Joint Osteoarthritis (TMJ-OA) and the regeneration of cartilage/osteochondral defects.

METHODS

Data on preclinical studies evaluating the effectiveness of stem cell-based therapies for treating Temporomandibular Disorders (TMDs) were extracted from PubMed, Web of Science, and Cochrane Library and the grey literature by three independent reviewers. A manual search was performed in the databases, the reference list of review studies, and relevant journals in the field. Compliance with the ARRIVE guidelines was evaluated for quality assessment. SYRCLE's risk of bias tool for animal experimental studies was assessed to define internal validity.

RESULTS

After applying the inclusion and exclusion criteria, 10 studies were included in the qualitative synthesis. Regardless of cell origin, stem cell-based therapeutic approaches induced protective, anti-inflammatory, and chondroregenerative potential in the treatment of TMJ-OA. Regeneration of the cartilage layer on the surface of the condyle was achieved when stem cells were directly flushed into the defect or when delivered within a carrier.

CONCLUSION

Stem cell-based therapies may be considered a promising approach for the treatment of TMJ-OA and for the regeneration of full-thickness cartilage and osteochondral defects in the TMJ. Human studies shall be performed to validate these results found in animals.

CircRNA_0092516 regulates chondrocyte proliferation and apoptosis in osteoarthritis through the miR-337-3p/PTEN axis

The dysregulation of circular RNAs (circRNAs) has been identified in various human diseases. Here, we probed into the potential mechanism of circRNA_0092516 in osteoarthritis (OA). The expression of circRNA_0092516 was tested by quantitative real-time PCR. MTT, flow cytometry and western blot were applied to confirm the functions of circRNA_0092516 in vitro. Besides, RNA pull-down and dual-luciferase reporter gene experiments were applied to probe into the mechanism. circRNA_0092516 was raised in the tissues of OA patients and chondrocytes stimulated by IL-1β. The potential mechanism analysis expounded that circRNA_0092516 bound to miR-337-3p, and the interference with circRNA_0092516 boosted chondrocyte proliferation and restrained cell apoptosis through the miR-337-3p/phosphatase and tensin homolog (PTEN) axis, thereby improving OA. In-vivo experiments expounded that circRNA_0092516 regulated cartilage production through miR-337-3p. Overall, our data expounded that the interference with circRNA_0092516 boosted chondrocyte proliferation and restrained cell apoptosis through the miR-337-3p/PTEN axis, eventually slowed down the progress of OA.

Inhibition of SDF-1/CXCR4 Axis to Alleviate Abnormal Bone Formation and Angiogenesis Could Improve the Subchondral Bone Microenvironment in Osteoarthritis

The pathogenesis of the osteoarthritis (OA) is complex. Abnormal subchondral bone metabolism is an important cause of this disease. Further understanding on the pathology of the subchondral bone in OA may provide a new therapy. This research is about to investigate the role of SDF-1 in the subchondral bone during the pathological process of OA. In vitro, Transwell was used to test the migratory ability of bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs). Western blot presented the protein level after SDF-1 treatment in BMSCs and HUVESs. Alizarin red was used to assess the ability of osteogenic differentiation. To inhibit SDF-1 signaling pathway in vivo, AMD3100 (SDF-1 receptor blocker) was continuously delivered via miniosmotic pump for 4 weeks in mice after performing anterior cruciate ligament transaction surgery. Micro-CT, histology staining, immunofluorescence, immunohistochemistry, and TRAP staining were used to assess the role of SDF-1 on osteogenesis and angiogenesis in the subchondral bone. Our results showed that SDF-1 could recruit BMSCs, activate the p-ERK pathway, and enhance osteogenic differentiation. SDF-1 promoted the ability of proliferation, migration and tube formation of HUVECs by activating the ERK and AKT signaling pathways. In an animal study, inhibition of SDF-1/CXCR4 axis could significantly reduce subchondral osteogenesis differentiation and H-type vessel formation. Furthermore, the AMD3100-treated group showed less cartilage destruction and bone resorption. Our research shows that SDF-1 alters the microenvironment of the subchondral bone by promoting osteoid islet formation and abnormal H-type angiogenesis in the subchondral bone, resulting in articular cartilage degeneration.

Cissus quadrangularis (veldt grape) attenuates disease progression and anatomical changes in mono sodium iodoacetate (MIA)-induced knee osteoarthritis in the rat model

The Cissus quadrangularis (CQ) stem has interesting nutritional and pharmacological properties to promote the health of the skeletal system. It is a well-recognized plant in the conventional system of medicine in India for treating bone and joint-associated complications. This study focuses on identifying the active constituents from the stem and root extracts of CQ and validating its anti-osteoarthritic activity by the in vivo model. Notable levels of phenolics and flavonoids were found in the ethanol extracts of both CQ stem (CQSE) and root (CQRE), among other solvent fractions. UPLC-MS/MS analysis of these selective extracts resulted in different classes of active compounds from both positive and negative ionization modes. By analyzing their mass spectra and fragmentation pattern, 25 active compounds were identified. The CQSE and CQRE extracts, along with the standard drug (naproxen), were further tested in mono-sodium iodoacetate-induced experimental OA animals. The modulatory effects of the test extracts were assessed by haematology, synovial and cartilage marker profiling, radiology and histopathological analysis. The in vivo findings from the biochemical and physiological studies have led to the conclusion that the CQSE extract is a good choice for the management of OA. The results were substantially better than CQ root extract and naproxen drug-treated groups. Thus, CQS has bioactive constituents, which could facilitate recovery from joint tissue damage, cellular metabolism and associated risk factors attributable to dysfunctions in OA incidence and progression.

Mechanical stress determines the configuration of TGFβ activation in articular cartilage

Our incomplete understanding of osteoarthritis (OA) pathogenesis has significantly hindered the development of disease-modifying therapy. The functional relationship between subchondral bone (SB) and articular cartilage (AC) is unclear. Here, we found that the changes of SB architecture altered the distribution of mechanical stress on AC. Importantly, the latter is well aligned with the pattern of transforming growth factor beta (TGFβ) activity in AC, which is essential in the regulation of AC homeostasis. Specifically, TGFβ activity is concentrated in the areas of AC with high mechanical stress. A high level of TGFβ disrupts the cartilage homeostasis and impairs the metabolic activity of chondrocytes. Mechanical stress stimulates talin-centered cytoskeletal reorganization and the consequent increase of cell contractile forces and cell stiffness of chondrocytes, which triggers αV integrin–mediated TGFβ activation. Knockout of αV integrin in chondrocytes reversed the alteration of TGFβ activation and subsequent metabolic abnormalities in AC and attenuated cartilage degeneration in an OA mouse model. Thus, SB structure determines the patterns of mechanical stress and the configuration of TGFβ activation in AC, which subsequently regulates chondrocyte metabolism and AC homeostasis.

The functional relationship between subchondral bone and articular cartilage is unclear. Here, the authors show that transforming growth factor-beta propagates the mechanical impact of subchondral bone on articular cartilage through αV integrin–talin mechanical transduction system in chondrocytes.

Alterations in Anandamide Synthesis and Degradation during Osteoarthritis Progression in an Animal Model

Osteoarthritis (OA) is a degenerative joint disease manifested by movement limitations and chronic pain. Endocannabinoid system (ECS) may modulate nociception via cannabinoid and TRPV1 receptors. The purpose of our study was to examine alterations in the spinal and joint endocannabinoid system during pain development in an animal model of OA. Wistar rats received intra-articular injection of 3mg of sodium monoiodoacetate (MIA) into the knee joint. Animals were sacrificed on day 2, 7, 14, 21, 28 after injection and lumbar spinal cord, cartilage and synovium were collected. Changes in the transcription levels of the ECS elements were measured. At the spinal level, gene expression levels of the cannabinoid and TRPV1 receptors as well as enzymes involved in anandamide synthesis and degradation were elevated in the advanced OA phase. In the joint, an important role of the synovium was demonstrated, since cartilage degeneration resulted in attenuation of the changes in the gene expression. Enzymes responsible for anandamide synthesis and degradation were upregulated particularly in the early stages of OA, presumably in response to early local joint inflammation. The presented study provides missing information about the MIA-induced OA model and encourages the development of a therapy focused on the molecular role of ECS.

Specific inhibition of FAK signaling attenuates subchondral bone deterioration and articular cartilage degeneration during osteoarthritis pathogenesis

Osteoarthritis (OA), a disease of the entire joint, is characterized by abnormal bone remodeling and coalescent degradation of articular cartilage. We have previously found that elevated levels of H-type vessels in subchondral bone correlate with OA and that focal adhesion kinase (FAK) is critical for H-type vessel formation in osteoporosis. However, the potential role of FAK in OA remains unexplored. Here, we demonstrate that the p-FAK level was dramatically elevated in subchondral bone following anterior cruciate ligament transection (ACLT) in rats. Specific inhibition of FAK signaling with Y15 in subchondral bone resulted in the suppression of subchondral bone deterioration and this effect was mediated by H-type vessel-induced ectopic bone formation. Further, articular cartilage degeneration was also alleviated after Y15 treatment. In vitro, the p-FAK level was significantly elevated in mesenchymal stem cells (MSCs) from vehicle-treated ACLT rats as compared to that in MSCs from sham controls and Y15-treated ACLT rats. Elevated p-FAK level in MSCs promoted vascular endothelial growth factor (VEGF) expression, as demonstrated from the high VEGF level in the blood, subchondral bone, and conditioned medium (CM) of MSCs from vehicle-treated ACLT rats. The CM of MSCs from vehicle-treated ACLT rats might promote the angiogenesis of endothelial cells and the catabolic response of chondrocytes through the FAK-growth factor receptor-bound protein 2-mitogen-activated protein kinase-mediated expression of VEGF. The effect of the CM from MSCs of Y15-treated ACLT rats or that treated with a VEGF-neutralizing antibody on vessel formation and the catabolic response was lowered. Thus, the specific inhibition of FAK signaling may be a promising avenue for the prevention or early treatment of OA.

Advanced oxidation protein products increase TNF-α and IL-1β expression in chondrocytes via NADPH oxidase 4 and accelerate cartilage degeneration in osteoarthritis progression

Interleukin (IL)-1β and tumor necrosis factor (TNF)-α, in particular, control the degeneration of articular cartilage, making them prime targets for osteoarthritis (OA) therapeutic strategies. Advanced oxidation protein products (AOPPs) are prevalent in numerous diseases. Our previous work demonstrates that intra-articular injections of AOPPs accelerate regression of cartilage in OA models. Whether AOPPs exist in the course of OA and their effects on TNF-α and IL-1β expression in chondrocytes are still unclear. This study confirmed that AOPPs levels in human synovial fluid were positively associated with severity of OA. We also found AOPPs deposition in articular cartilage in anterior cruciate ligament transection (ACLT) induced rodent OA models. AOPPs increased expression of TNF-α and IL-1β in chondrocytes in vitro, which was inhibited by pre-treatment with SB202190 (p38-MAPK inhibitor) or apocynin (NADPH oxidase inhibitor) or NOX4 knockdown by siRNAs. Subsequently, we further verified in vivo that exogenous injection of AOPPs in OA mice up-regulated expression of TNF-α and IL-1β in cartilage, which was blocked by treatment with apocynin. In parallel, apocynin attenuated articular cartilage degeneration resulting in substantially lower OARSI scores. Specifically, apocynin reduced NOX4, p-P38, TNF-α and IL-1β and increased collagen II and glycosaminoglycan (GAG). This study demonstrated that AOPPs increased expression of TNF-α and IL-1β in chondrocytes via the NADPH oxidase4-dependent and p38-MAPK mediated pathway, and accelerated cartilage degeneration in OA progression. These findings suggest an endogenous pathogenic role of AOPPs in OA progression. Targeting AOPPs-triggered cellular mechanisms might be a promising therapeutic option for patients with OA.

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AOPPs present in OA joint.

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AOPPs increased TNF-α and IL-1β expression in chondrocytes and accelerates progression of OA.

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NADPH oxidase inhibitor decreased TNF-α and IL-1β expression and attenuates progression of OA.

SDF-1/CXCR4 axis coordinates crosstalk between subchondral bone and articular cartilage in osteoarthritis pathogenesis

Crosstalk between subchondral bone and articular cartilage is considered a central feature of osteoarthritis (OA) initiation and progression, but its underlying molecular mechanism remains elusive. Meanwhile, specific administration of drugs in subchondral bone is also a great challenge during investigation of the process. We here explore the role of stromal cell-derived factor 1 (SDF-1)/C-X-C chemokine receptor type 4 (CXCR4) axis in the crosstalk between subchondral bone and articular cartilage in OA pathogenesis, using osmotic infusion pumps implanted in tibial subchondral bone directly to ensure quantitative, continuous and steady drug delivery over the entire experiment. We found that increased SDF-1 in subchondral bone firstly induced subchondral bone deterioration by erroneous Mesenchymal Stem Cells (MSCs) recruitment and excessive bone resorption in anterior cruciate ligament transection (ACLT) mice. Deterioration of subchondral bone then led to the traverse of SDF-1 from subchondral bone to overlying cartilage. Finally, SDF-1 from underlying subchondral bone combined with CXCR4 in chondrocytes to induce articular cartilage degradation by promoting the shift of transforming growth factor-β receptor type I (TβRI) in chondrocytes from activin receptor-like kinase 5 (ALK5) to activin receptor-like kinase 1 (ALK1). More importantly, specific inhibition of SDF-1/CXCR4 axis in ACLT rats attenuated OA by stabilizing subchondral bone microarchitecture, reducing SDF-1 in cartilage and abrogating the shift of TβRI in chondrocytes. Our data demonstrate that the SDF-1/CXCR4 axis may coordinate the crosstalk between subchondral bone and articular cartilage in OA pathogenesis. Therefore, specific inhibition of SDF-1/CXCR4 axis in subchondral bone or intervention in SDF-1 traverse may be therapeutic targets for OA.

Early growth response 1 reduction in peripheral blood involving condylar subchondral bone loss

OBJECTIVES

To detect whether early growth response 1 (EGR1) in peripheral blood leucocytes (PBLs) indicates temporomandibular joint (TMJ) osteoarthritis (OA) lesions.

MATERIALS AND METHODS

Egr1 mRNA expression levels in PBLs were detected in eight malocclusion patients without temporomandibular disorder (TMD) signs and 16 malocclusion patients with clinical TMD signs with (eight) or without (eight) imaging signs of TMJ OA. Twelve 6-week-old rats were randomized to a control group and a unilateral anterior crossbite (UAC) group and were sampled at 4 weeks. The Egr1 mRNA expression levels in PBLs and protein expression levels in different orofacial tissues were measured.

RESULTS

Patients with TMD signs with/without TMJ OA diagnosis showed lower Egr1 mRNA expression levels in PBLs than patients without TMD signs. The lower Egr1 mRNA expression was also found in the PBLs of UAC rats, which were induced to exhibit early histo-morphological signs of TMJ OA lesions. In subchondral bone of UAC rats, EGR1 protein expression was decreased, co-localization of EGR1 with osterix or dentin matrix protein-1 was identified, and the number of EGR1 and osterix double-positive cells was reduced (all p < .05).

CONCLUSION

Egr1 reduction in PBLs potentially indicates subchondral bone OA lesions at an early stage.

CircSERPINE2 protects against osteoarthritis by targeting miR-1271 and ETS-related gene

Objectives

Circular RNAs (circRNA) expression aberration has been identified in various human diseases. In this study, we investigated whether circRNAs could act as competing endogenous RNAs to regulate the pathological process of osteoarthritis (OA).

Methods

CircRNA deep sequencing was performed to the expression of circRNAs between OA and control cartilage tissues. The regulatory and functional role of CircSERPINE2 upregulation was examined in OA and was validated in vitro and in vivo, downstream target of CircSERPINE2 was explored. RNA pull down, a luciferase reporter assay, biotin-coupled microRNA capture and fluorescence in situ hybridisation were used to evaluate the interaction between CircSERPINE2 and miR-1271-5 p, as well as the target mRNA, E26 transformation-specific-related gene (ERG). The role and mechanism of CircSERPINE2 in OA was also explored in rabbit models.

Results

The decreased expression of CircSERPINE2 in the OA cartilage tissues was directly associated with excessive apoptosis and imbalance between anabolic and catabolic factors of extracellular matrix (ECM). Mechanistically, CircSERPINE2 acted as a sponge of miR-1271-5 p and functioned in human chondrocytes (HCs) through targeting miR-1271-5 p and ERG. Intra-articular injection of adeno-associated virus-CircSERPINE2-wt alleviated OA in the rabbit model.

Conclusions

Our results reveal an important role for a novel circRNA-CircSERPINE2 in OA progression. CircSERPINE2 overexpression could alleviate HCs apoptosis and promote anabolism of ECM through miR-1271-ERG pathway. It provides a potentially effective therapeutic strategy for OA progression.

Activation of β-catenin in Col2-expressing chondrocytes leads to osteoarthritis-like defects in hip joint

Although osteoarthritis (OA) in the hip joint is a common and debilitating degenerative disease, the precise molecular mechanisms underlying its pathological process remains unclear. This study sets out to investigate whether β-catenin plays a critical role in hip OA pathogenesis. Here, we showed overexpressed β-catenin protein in human OA cartilage tissues. Then, we analyzed β-cat(ex3)^Col2ER mice, in which β-catenin gene was conditionally activated in femoral head chondrocytes. At 2 months of age, β-cat(ex3)^Col2ER mice already showed a phenotype of severe cartilage degeneration in the femoral head. More changes observed in β-cat(ex3)^Col2ER mice with age included subchondral sclerosis and osteophyte formation along joint margins, resembling a hip OA phenotype in humans. In addition, cartilage degradation and chondrocyte apoptosis as the results of β-catenin activation possibly contributed to this hip OA-like phenotype. Overall our findings provide direct evidence about the importance of β-catenin in hip OA pathogenesis.

Tyrosine kinase Fyn promotes osteoarthritis by activating the β-catenin pathway

OBJECTIVES

To investigate the role of tyrosine kinase Fyn in the development of osteoarthritis (OA) and the underlying mechanisms, and to define whether targeting Fyn could prevent OA in mice.

METHODS

Cartilage samples from normal and aged mice were analysed with proteome-wide screening. Fyn expression was examined with immunofluorescence in human and age-dependent or experimental mouse OA cartilage samples. Experimental OA in Fyn-knockout mice was induced by destabilisation of the medial meniscus. Primary cultured mouse chondrocytes were treated with proinflammatory cytokine interleukin-1β. The inhibitor of Src kinase family, AZD0530 (saracatinib), and inhibitor of Fyn, PP1, were used to treat experimental OA in mice.

RESULTS

Fyn expression was markedly upregulated in human OA cartilage and in cartilage from aged mice and those with post-traumatic OA. Fyn accumulates in articular chondrocytes and interacts directly with and phosphorylates β-catenin at Tyr142, which stabilises β-catenin and promotes its nuclear translocation. The deletion of Fyn effectively delayed the development of post-traumatic and age-dependent OA in mice. Fyn inhibitors AZD0530 and PP1 significantly attenuated OA progression by blocking the β-catenin pathway and reducing the levels of extracellular matrix catabolic enzymes in the articular cartilage.

CONCLUSIONS

Fyn accumulates and activates β-catenin signalling in chondrocytes, accelerating the degradation of the articular cartilage and OA development. Targeting Fyn is a novel and potentially therapeutic approach to the treatment of OA.

Subchondral Trabecular Rod Loss and Plate Thickening in the Development of Osteoarthritis

Developing effective treatment for osteoarthritis (OA), a prevalent and disabling disease, has remained a challenge, primarily because of limited understanding of its pathogenesis and late diagnosis. In the subchondral bone, rapid bone loss after traumatic injuries and bone sclerosis at the advanced stage of OA are well-recognized hallmarks of the disease. Recent studies have further demonstrated the crucial contribution of subchondral bone in the development of OA. However, the microstructural basis of these bone changes has not been examined thoroughly, and the paradox of how abnormal resorption can eventually lead to bone sclerosis remains unanswered. By applying a novel microstructural analysis technique, individual trabecula segmentation (ITS), to micro-computed tomography (μCT) images of human OA knees, we have identified a drastic loss of rod-like trabeculae and thickening of plate-like trabeculae that persisted in all regions of the tibial plateau, underneath both severely damaged and still intact cartilage. The simultaneous reduction in trabecular rods and thickening of trabecular plates provide important insights to the dynamic and paradoxical subchondral bone changes observed in OA. Furthermore, using an established guinea pig model of spontaneous OA, we discovered similar trabecular rod loss and plate thickening that preceded cartilage degradation. Thus, our study suggests that rod-and-plate microstructural changes in the subchondral trabecular bone may play an important role in the development of OA and that advanced microstructural analysis techniques such as ITS are necessary in detecting these early but subtle changes. With emerging high-resolution skeletal imaging modalities such as the high-resolution peripheral quantitative computed tomography (HR-pQCT), trabecular rod loss identified by ITS could potentially be used as a marker in assessing the progression of OA in future longitudinal studies or clinical diagnosis. © 2017 American Society for Bone and Mineral Research.

A putative Chondroprotective role for IL-1β and MPO in herbal treatment of experimental osteoarthritis

BACKGROUND

Herbal treatment may have a chondroprotective and therapeutic effect on Osteoarthritis (OA). We investigated the mechanism of action of ginger and curcumin rhizomes cultivated in Egypt in treatment of OA in rat model.

METHODS

Thirty-five albino rats were intra-articularly injected with Monosodium Iodoacetate in the knee joint. Ginger and curcumin was orally administered at doses of 200 and 400 mg/kg (F200 and F400). Serum levels of cartilage oligomeric matrix protein (COMP), hyaluronic acid (HA), malondialdehyde (MDA), myeloperoxidase (MPO), Interleukin-1 beta (IL-1β) and superoxide dismutase activity (SOD) were measured using ELISA. The composition of the herbal formula hydro-ethanolic extract was characterized using UPLC-ESI-MS. Histopathological changes in injected joints was examined using routine histopathology. Statistical analysis was performed using one-way ANOVA.

RESULTS

Serum levels of COMP, HA, MPO, MDA, and IL-1β were significantly decreased in F 200, F 400 and V groups when compared to OA group (P value <0.0001). On the other hand SOD levels were significantly elevated in treated groups compared to OA groups (P value <0.0001).

CONCLUSIONS

The ginger/curcumin at 1:1 had chondroprotective effect via anti-inflammatory and antioxidant effect in rat OA model. Further pharmacological and clinical studies are needed to evaluate this effect.

Anti-inflammatory and anti-osteoarthritis effects of tectorigenin

Osteoarthritis (OA) is a common and dynamic disease of the joints, including the articular cartilage, underlying bones and synovium. In particular, OA is considered as the degeneration of the cartilage. Tectorigenin (Tec) is known to affect many biological processes; however, its effects on articular chondrocytes remain unclear. This study aimed to assess the effects of Tec on articular cartilage. In vitro, Tec inhibited the expression levels of type X collagen, cyclooxigenase-2, matrix metalloproteinase (MMP)-3 and MMP-13, but enhanced the expression of Runx1, type II collagen and aggrecan in the presence of IL-1β. Meanwhile, Tec inhibited apoptosis through the Bax/Bcl-2/caspase-3 pathway, upregulating p-Bad, downregulating the Bax/Bcl-2 ratio, and activating caspase-3 compared with IL-1β treatment only. Moreover, this process was partially regulated by NF-κB P65. In vivo, the chondroprotective effects of Tec were assessed by establishing a model of surgically induced OA. Tec-treated joints exhibited fewer osteoarthritic changes than saline-treated joints. Meanwhile, 1.5 μg/kg Tec treatment produced a greater protective effect than 0.75 μg/kg Tec. The Osteoarthritis Research Society International (OARSI) scoring system, employed to assess histopathological grading of the models, as well immunohistochemistry for Aggrecan Neoepitope and MMP-3, further confirmed the results. In conclusion, this study showed that Tec plays a chondroprotective role in the OA process by preventing articular cartilage degeneration and chondrocyte apoptosis via the NF-κB P65 pathway.

Summary: Tectorigenin exerts anti-inflammatory and anti-osteoarthritis effects by inhibiting apoptosis in chondrocytes via the NF-κB P65 pathway.

Efficacy and safety of aceclofenac in osteoarthritis: A meta-analysis of randomized controlled trials

OBJECTIVE

To analyze the effects on pain, function, and safety of aceclofenac compared with other nonsteroidal anti-inflammatory drugs (NSAIDs) or pain relief medications in patients with osteoarthritis.

MATERIAL AND METHODS

Two investigators independently searched the database. We included randomized controlled trials evaluating efficacy and/or safety of aceclofenac compared with control interventions (NSAIDs or acetaminophen) in patients with osteoarthritis. We did not include placebo, opioid analgesics, NSAID combinations, and topical analgesics for the control groups. We summarized the efficacy data as standardized mean differences (SMD) with 95% confidence intervals (CI) and safety outcomes as risk ratios (RR) with 95% CI using the inverse variance random effect model. We assessed the heterogeneity by the I² test. We used the GRADE approach to evaluate the quality of the evidence for all outcome parameters.

RESULTS

We included 9 trials (8 double blind and 1 single blind) that evaluated pain (7 trials), function (8 trials) and safety (7 trials). We observed no significant difference in pain reduction between aceclofenac and control interventions [SMD: -0.30 (-0.62, 0.01); I²=88%; GRADE evidence- low]. Aceclofenac was more beneficial than control interventions in improving physical function [SMD: -0.27 (-0.50, -0.03); I²=88%; GRADE evidence- low]. We observed less gastrointestinal adverse events for aceclofenac than in control interventions [RR 0.69 (95% CI: 0.57, 0.83); I²=12%; GRADE evidence- moderate]. We observed no difference in overall adverse events occurrence and dropout rate between aceclofenac and control interventions.

CONCLUSION

We observed that aceclofenac was beneficial over control analgesics for function improvement and to minimize gastrointestinal adverse events. Our findings could be biased due to the heterogeneity of the sample, the fact that the trials were small and methodological issues.

P2X3 and P2X2/3 Receptors Play a Crucial Role in Articular Hyperalgesia Development Through Inflammatory Mechanisms in the Knee Joint Experimental Synovitis

Osteoarthritis (OA) is a degenerative and progressive disease characterized by cartilage breakdown and by synovial membrane inflammation, which results in disability, joint swelling, and pain. The purinergic P2X3 and P2X2/3 receptors contribute to development of inflammatory hyperalgesia, participate in arthritis processes in the knee joint, and are expressed in chondrocytes and nociceptive afferent fibers innervating the knee joint. In this study, we hypothesized that P2X3 and P2X2/3 receptors activation by endogenous ATP (adenosine 5'-triphosphate) induces articular hyperalgesia in the knee joint of male and female rats through an indirect sensitization of primary afferent nociceptors dependent on the previous release of pro-inflammatory cytokines and/or on neutrophil migration. We found that the blockade of articular P2X3 and P2X2/3 receptors significantly attenuated carrageenan-induced hyperalgesia in the knee joint of male and estrus female rats in a similar manner. The carrageenan-induced knee joint inflammation increased the expression of P2X3 receptors in chondrocytes of articular cartilage. Further, the blockade of articular P2X3 and P2X2/3 receptors significantly reduced the increased concentration of TNF-α, IL-6, and CINC-1 and the neutrophil migration induced by carrageenan. These findings indicate that P2X3 and P2X2/3 receptors activation by endogenous ATP is essential to hyperalgesia development in the knee joint through an indirect sensitization of primary afferent nociceptors dependent on the previous release of pro-inflammatory cytokines and/or on neutrophil migration.

Systemic neutralization of TGF-β attenuates osteoarthritis

Osteoarthritis (OA) is a major source of pain and disability worldwide with no effective medical therapy due to poor understanding of its pathogenesis. Transforming growth factor β (TGF-β) has been reported to play a role in subchondral bone pathology and articular cartilage degeneration during the progression of OA. In this study, we demonstrated that systemic use of a TGF-β-neutralizing antibody (1D11) attenuates OA progression by targeting subchondral bone pathological features in rodent OA models. Systemic administration of 1D11 preserves the subchondral bone microarchitecture, preventing articular cartilage degeneration by inhibition of excessive TGF-β activity, in both subchondral bone and the circulation. Moreover, the aberrant increases in the numbers of blood vessels, nestin(+) mesenchymal stromal/stem cells, and osterix(+) osteoblast progenitors were normalized by 1D11 systemic injection. Thus, systemic neutralization of excessive TGF-β ligands effectively prevented OA progression in animal models, with promising clinical implications for OA treatment.

Identifying Patient-Specific Pathology in Osteoarthritis Development Based on MicroCT Analysis of Subchondral Trabecular Bone

The goal of this study was to identify alternative mechanisms of osteoarthritis pathology by analyzing subchondral bone. Femoral condyle samples were collected from post-menopausal female patients with knee osteoarthritis undegoing total knee arthroplasty. In the majority of patients, subchondral trabecular bone volume doubled under a region of the medial femoral condyle with full-thickness cartilage deterioration. However, in a subset of patients the bone volume in this region remained constant. This subset also had larger areas of vascular penetration in the calcified cartilage of the lateral condyle concurrent with increased vascular endothelial growth factor expression. Subtyping by subchondral bone characteristics identified a unique population, which lacked the sclerotic bone characteristic of late-stage osteoarthritis. Identification of subtypes within the osteoarthritis population allows investigation of alternate disease pathologies.

Halofuginone attenuates osteoarthritis by inhibition of TGF-β activity and H-type vessel formation in subchondral bone

Objectives

Examine whether osteoarthritis (OA) progression can be delayed by halofuginone in anterior cruciate ligament transection (ACLT) rodent models.

Methods

3-month-old male C57BL/6J (wild type; WT) mice and Lewis rats were randomised to sham-operated, ACLT-operated, treated with vehicle, or ACLT-operated, treated with halofuginone. Articular cartilage degeneration was graded using the Osteoarthritis Research Society International (OARSI)-modified Mankin criteria. Immunostaining, flow cytometry, RT-PCR and western blot analyses were conducted to detect relative protein and RNA expression. Bone micro CT (μCT) and CT-based microangiography were quantitated to detect alterations of microarchitecture and vasculature in tibial subchondral bone.

Results

Halofuginone attenuated articular cartilage degeneration and subchondral bone deterioration, resulting in substantially lower OARSI scores. Specifically, we found that proteoglycan loss and calcification of articular cartilage were significantly decreased in halofuginone-treated ACLT rodents compared with vehicle-treated ACLT controls. Halofuginone reduced collagen X (Col X), matrix metalloproteinase-13 and A disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS 5) and increased lubricin, collagen II and aggrecan. In parallel, halofuginone-attenuated uncoupled subchondral bone remodelling as defined by reduced subchondral bone tissue volume, lower trabecular pattern factor (Tb.pf) and increased thickness of subchondral bone plate compared with vehicle-treated ACLT controls. We found that halofuginone exerted protective effects in part by suppressing Th17-induced osteoclastic bone resorption, inhibiting Smad2/3-dependent TGF-β signalling to restore coupled bone remodelling and attenuating excessive angiogenesis in subchondral bone.

Conclusions

Halofuginone attenuates OA progression by inhibition of subchondral bone TGF-β activity and aberrant angiogenesis as a potential preventive therapy for OA.

RANTES and SDF-1 Are Keys in Cell-based Therapy of TMJ Osteoarthritis

The present study aimed to investigate the therapeutic effect of injections of local bone marrow mesenchymal stem cells (BMSCs) on osteoarthritis (OA) of the temporomandibular joint (TMJ) and to explore the role of stromal cell-derived factor 1 (SDF-1) and regulated on activation, normal T-cell expressed and secreted (RANTES) in this effect. Fundamentally, OA of the TMJ was induced by unilateral anterior crossbite in mice. Exogenous green fluorescent protein-labeled BMSCs (GFP-BMSCs) were weekly injected into the TMJ region for 4, 8, and 12 wk. The reparative effects of exogenous GFP-BMSCs were investigated by morphological observation and micro-computed tomography. The differentiation of GFP-BMSCs in the cartilage was examined by double immunofluorescence of GFPs with type II collagen, and the expression of related factors in the condylar cartilage was quantified by real-time polymerase chain reaction. The role of RANTES and SDF-1 in the therapeutic effect of exogenous BMSCs was examined by both in vitro and in vivo studies. The OA cartilage of the TMJ displays a synchronous increase in SDF-1 and RANTES expression and a higher capability of attracting the migration of GFP-BMSCs. The implanted GFP-BMSCs differentiated into type II collagen-positive cells and reversed cartilage degradation and subchondral bone loss in mice with OA of the TMJ. The migration of GFP-BMSCs towards OA cartilage and the rescuing effect of GFP-BMSC injections were impaired by the inhibitors of C-X-C chemokine receptor type 4 (CXCR4) and C-C chemokine receptor type 1 (CCR1), which are the receptors of SDF-1 and RANTES, respectively. Our data indicated that SDF-1/CXCR4 and RANTES/CCR1 signals are pivotal and function synergistically in the recruitment of GFP-BMSCs towards degraded cartilage in mice OA of the TMJ.

The potential utility of high-intensity ultrasound to treat osteoarthritis

Osteoarthritis (OA) is a widespread musculoskeletal disease that reduces quality of life and for which there is no cure. The treatment of OA is challenging since cartilage impedes the local and systemic delivery of therapeutic compounds (TCs). This review identifies high-intensity ultrasound (HIU) as a non-contact technique to modify articular cartilage and subchondral bone. HIU enables new approaches to overcome challenges associated with drug delivery to cartilage and new non-invasive approaches for the treatment of joint disease. Specifically, HIU has the potential to facilitate targeted drug delivery and release deep within cartilage, to repair soft tissue damage, and to physically alter tissue structures including cartilage and bone. The localized, non-invasive ultrasonic delivery of TCs to articular cartilage and subchondral bone appears to be a promising technique in the immediate future.

Angelica Sinensis polysaccharides stimulated UDP-sugar synthase genes through promoting gene expression of IGF-1 and IGF1R in chondrocytes: promoting anti-osteoarthritic activity

BACKGROUND

Osteoarthritis (OA) is a chronic joints disease characterized by progressive degeneration of articular cartilage due to the loss of cartilage matrix. Previously, we found, for the first time, that an acidic glycan from Angelica Sinensis Polysaccharides (APSs), namely the APS-3c, could protect rat cartilage from OA due to promoting glycosaminoglycan (GAG) synthesis in chondrocytes. In the present work, we tried to further the understanding of ASP-3c's anti-OA activity.

METHODOLOGY/PRINCIPAL FINDINGS

Human primary chondrocytes were treated with APS-3c or/and recombinant human interleukin 1β (IL-1β). It turned out that APS-3c promoted synthesis of UDP-xylose and GAG, as well as the gene expression of UDP-sugar synthases (USSs), insulin like growth factor 1 (IGF1) and IGF1 receptor (IGF1R), and attenuated the degenerative phenotypes, suppressed biosynthesis of UDP-sugars and GAG, and inhibited the gene expression of USSs, IGF1 and IGF1R induced by IL-1β. Then, we induced a rat OA model with papain, and found that APS-3c also stimulated GAG synthesis and gene expression of USSs, IGF1 and IGF1R in vivo. Additionally, recombinant human IGF1 and IGF1R inhibitor NP-AEW541 were applied to figure out the correlation between stimulated gene expression of USSs, IGF1 and IGF1R induced by APS-3c. It tuned out that the promoted GAG synthesis and USSs gene expression induced by APS-3c was mediated by the stimulated IGF1 and IGF1R gene expression, but not through directly activation of IGF1R signaling pathway.

CONCLUSIONS/SIGNIFICANCES

We demonstrated for the first time that APS-3c presented anti-OA activity through stimulating IGF-1 and IGF1R gene expression, but not directly activating the IGF1R signaling pathway, which consequently promoted UDP-sugars and GAG synthesis due to up-regulating gene expression of USSs. Our findings presented a better understanding of APS-3c's anti-OA activity and suggested that APS-3c could potentially be a novel therapeutic agent for OA.

What about strontium ranelate in osteoarthritis? Doubts and securities

Abstract Osteoarthritis (OA) is the most common disabling joint disease worldwide and its treatment is based on a combination of non-pharmacological and pharmacological modalities. Commonly prescribed OA medications include symptomatic drugs (non-steroidal anti-inflammatory drugs, analgesics, locally administered corticosteroids, viscosupplementation) and new compounds that are potentially able to reduce or stop the disease progression, called "Disease Modifying Osteoarthritis Drugs (DMOADs)". Strontium ranelate (SR) is an anti-osteoporotic treatment that increases bone formation, while decreasing bone resorption and it potentially acts as a new DMOAD. The objective of this review is to summarize the currently available information on clinical effects and mechanism of action of SR in OA. We have examined two post hoc analysis conducted on the large, randomized Treatment of Peripheral Osteoporosis study and the double-blind, randomized, controlled trial about SR in knee OA. Furthermore, we analyzed three studies in animal models and two in vitro experiments to better understand the mechanism of action of SR in OA. The available data demonstrate that SR could be considered a new promising symptomatic and disease-modifying agent in the treatment of OA and was safe and well tolerated. Additionally, there is a need for further investigations to establish the optimal dosage and to better clarify the mechanism of action of SR in OA.

A three-dimensionally engineered biomimetic cartilaginous tissue model for osteoarthritic drug evaluation

Osteoarthritis (OA) is primarily characterized by focal cartilage destruction and synovitis. Presently, the pathogenesis of OA remains unclear, and an effective treatment methodology is an unmet need. To this end, a plethora of animal models and monolayer models have been developed, but they are faced with the limitation of high cost and inability to recapitulate a pure hyaline cartilaginous phenotype, which is important in studying the efficacy of therapeutic agents. We have previously developed a living hyaline cartilage graft (LhCG) that accurately presented a pure hyaline cartilage phenotype. Here, through the coculture of lipopolysaccharide (LPS)-activated macrophages with LhCG, we hypothesized that an accurate OA disease model may be developed. Subsequently, this model was evaluated for its accuracy for in vitro drug testing. Results indicated that chondrocyte proliferation and apoptosis were increased in the disease model. Additionally, extracellular matrix (ECM) synthesis increased as indicated by the increased anabolic gene expression levels, such as collagen type II and aggrecan. Up-regulation of matrix metalloproteinase-1 (MMP-1) and MMP-3 genes suggested increased degradative activity, while chondrocytic hypertrophic differentiation was observed. Furthermore, extensive degradation of collagen type II and glycosaminoglycans (GAGs) were also observed. The results of celecoxib treatment on our model showed inhibition of nitric oxide (NO) and prostaglandin E2 (PGE2) production, as well as down-regulation of MMP-1 and MMP-3 expression. Taken together, the results suggested that this coculture model was able to sufficiently mimic the native, diseased OA cartilage, while drug testing results confirmed its suitability as an in vitro model for predicting native cartilage response to drug treatment.

Cannabinoid CB2 receptors regulate central sensitization and pain responses associated with osteoarthritis of the knee joint

Osteoarthritis (OA) of the joint is a prevalent disease accompanied by chronic, debilitating pain. Recent clinical evidence has demonstrated that central sensitization contributes to OA pain. An improved understanding of how OA joint pathology impacts upon the central processing of pain is crucial for the identification of novel analgesic targets/new therapeutic strategies. Inhibitory cannabinoid 2 (CB2) receptors attenuate peripheral immune cell function and modulate central neuro-immune responses in models of neurodegeneration. Systemic administration of the CB2 receptor agonist JWH133 attenuated OA-induced pain behaviour, and the changes in circulating pro- and anti-inflammatory cytokines exhibited in this model. Electrophysiological studies revealed that spinal administration of JWH133 inhibited noxious-evoked responses of spinal neurones in the model of OA pain, but not in control rats, indicating a novel spinal role of this target. We further demonstrate dynamic changes in spinal CB2 receptor mRNA and protein expression in an OA pain model. The expression of CB2 receptor protein by both neurones and microglia in the spinal cord was significantly increased in the model of OA. Hallmarks of central sensitization, significant spinal astrogliosis and increases in activity of metalloproteases MMP-2 and MMP-9 in the spinal cord were evident in the model of OA pain. Systemic administration of JWH133 attenuated these markers of central sensitization, providing a neurobiological basis for analgesic effects of the CB2 receptor in this model of OA pain. Analysis of human spinal cord revealed a negative correlation between spinal cord CB2 receptor mRNA and macroscopic knee chondropathy. These data provide new clinically relevant evidence that joint damage and spinal CB2 receptor expression are correlated combined with converging pre-clinical evidence that activation of CB2 receptors inhibits central sensitization and its contribution to the manifestation of chronic OA pain. These findings suggest that targeting CB2 receptors may have therapeutic potential for treating OA pain.

Cartilage Protective and Chondrogenic Capacity of WIN-34B, a New Herbal Agent, in the Collagenase-Induced Osteoarthritis Rabbit Model and in Progenitor Cells from Subchondral Bone

We sought to determine the cartilage repair capacity of WIN-34B in the collagenase-induced osteoarthritis rabbit model and in progenitor cells from subchondral bone. The cartilage protective effect of WIN-34B was measured by clinical and histological scores, cartilage area, and proteoglycan and collagen contents in the collagenase-induced osteoarthritis rabbit model. The efficacy of chondrogenic differentiation of WIN-34B was assessed by expression of CD105, CD73, type II collagen, and aggrecan in vivo and was analyzed by the surface markers of progenitor cells, the mRNA levels of chondrogenic marker genes, and the level of proteoglycan, GAG, and type II collagen in vitro. Oral administration of WIN-34B significantly increased cartilage area, and this was associated with the recovery of proteoglycan and collagen content. Moreover, WIN-34B at 200 mg/kg significantly increased the expression of CD105, CD73, type II collagen, and aggrecan compared to the vehicle group. WIN-34B markedly enhanced the chondrogenic differentiation of CD105 and type II collagen in the progenitor cells from subchondral bone. Also, we confirmed that treatment with WIN-34B strongly increased the number of SH-2(CD105) cells and expression type II collagen in subchondral progenitor cells. Moreover, WIN-34B significantly increased proteoglycan, as measured by alcian blue staining; the mRNA level of type II α 1 collagen, cartilage link protein, and aggrecan; and the inhibition of cartilage matrix molecules, such as GAG and type II collagen, in IL-1 β -treated progenitor cells. These findings suggest that WIN-34B could be a potential candidate for effective anti-osteoarthritic therapy with cartilage repair as well as cartilage protection via enhancement of chondrogenic differentiation in the collagenase-induced osteoarthritis rabbit model and progenitor cells from subchondral bone.

Inhibition of TGF-β signaling in mesenchymal stem cells of subchondral bone attenuates osteoarthritis

Osteoarthritis is a highly prevalent and debilitating joint disorder. There is no effective medical therapy for osteoarthritis due to limited understanding of osteoarthritis pathogenesis. We show that TGF–β1 is activated in the subchondral bone in response to altered mechanical loading in an anterior cruciate ligament transection (ACLT) osteoarthritis mouse model. TGF–β1 concentrations also increased in human osteoarthritis subchondral bone. High concentrations of TGF–β1 induced formation of nestin⁺ mesenchymal stem cell (MSC) clusters leading to aberrant bone formation accompanied by increased angiogenesis. Transgenic expression of active TGF–β1 in osteoblastic cells induced osteoarthritis. Inhibition of TGF–β activity in subchondral bone attenuated degeneration of osteoarthritis articular cartilage. Notably, knockout of the TGF–β type II receptor (TβRII) in nestin⁺ MSCs reduced development of osteoarthritis in ACLT mice. Thus, high concentrations of active TGF–β1 in the subchondral bone initiated the pathological changes of osteoarthritis, inhibition of which could be a potential therapeutic approach.