Transcriptional suppression by interleukin-1 and interferon-gamma of type II collagen gene expression in human chondrocytes

Substance P promotes transforming growth factor-β-induced collagen synthesis in human corneal fibroblasts

Corneal fibroblasts maintain homeostasis of the corneal stroma by mediating the synthesis and degradation of extracellular collagen, and these actions are promoted by transforming growth factor-β (TGF-β) and interleukin-1β (IL-1β), respectively. The cornea is densely innervated with sensory nerve fibers that are not only responsible for sensation but also required for physiological processes such as tear secretion and wound healing. Loss or dysfunction of corneal nerves thus impairs corneal epithelial wound healing and can lead to neurotrophic keratopathy. The sensory neurotransmitter substance P (SP) promotes corneal epithelial wound healing by enhancing the stimulatory effects of growth factors and fibronectin. We have now investigated the role of SP in collagen metabolism mediated by human corneal fibroblasts in culture. Although SP alone had no effect on collagen synthesis or degradation by these cells, it promoted the stimulatory effect of TGF-β on collagen type I synthesis without affecting that of IL-1β on the expression of matrix metalloproteinase-1. This effect of SP on TGF-β-induced collagen synthesis was accompanied by activation of p38 mitogen-activated protein kinase (MAPK) signaling and was attenuated by pharmacological inhibition of p38 or of the neurokinin-1 receptor. Our results thus implicate SP as a modulator of TGF-β-induced collagen type I synthesis by human corneal fibroblasts, and they suggest that loss of this function may contribute to the development of neurotrophic keratopathy.NEW & NOTEWORTHY This study investigates the role of substance P (SP) in collagen metabolism mediated by human corneal fibroblasts in culture. We found that, although SP alone had no effect on collagen synthesis or degradation by corneal fibroblasts, it promoted the stimulatory effect of transforming growth factor-β on collagen type I synthesis without affecting that of interleukin-1β on the expression of matrix metalloproteinase-1.

Bergamottin (Ber) ameliorates the progression of osteoarthritis via the Sirt1/NF-κB pathway

Osteoarthritis (OA) is a common chronic disease characterized by progressive cartilage degeneration and secondary synovial inflammation. Bergamottin (Ber) is an important natural derivative of the furanocoumarin compound, extracted from natural foods, such as the pulp of grapefruits and pomelos. Ber exhibits several characteristicsthat are beneficial to human health, such as anti-inflammation, antioxidant, and anti-cancer effects. However, the role of Ber in the treatment of OA has not been elucidated to date. Therefore, in the present study, in vitro experiments were conducted, which demonstrated that Ber reduces the secretion of inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase-2 (COX2), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and prostaglandin E2 (PGE2) under the stimulation of interleukin-1β (IL-1β). Ber also reversed the IL-1 β-mediated aggrecan and type II collagen degradation within the extracellular matrix (ECM). In addition, in vivo experiments were conducted, in which Ber ameliorated the progression of OA in mice. It was revealed that Ber exerted its cellular effect by activating the Sirt1/NF-kB pathways. In conclusion, the present study demonstrated the therapeutic potential of Ber in the context of OA.

CHMP5 attenuates osteoarthritis via inhibiting chondrocyte apoptosis and extracellular matrix degradation: involvement of NF-κB pathway

BACKGROUND

Osteoarthritis (OA), the most common joint disease, is linked with chondrocyte apoptosis and extracellular matrix (ECM) degradation. Charged multivesicular body protein 5 (CHMP5), a member of the multivesicular body, has been reported to serve as an anti-apoptotic protein to participate in leukemia development. However, the effects of CHMP5 on apoptosis and ECM degradation in OA remain unclear.

METHODS

In this study, quantitative proteomics was performed to analyze differential proteins between normal and OA patient articular cartilages. The OA mouse model was constructed by the destabilization of the medial meniscus (DMM). In vitro, interleukin-1 beta (IL-1β) was used to induce OA in human chondrocytes. CHMP5 overexpression and silencing vectors were created using an adenovirus system. The effects of CHMP5 on IL-1β-induced chondrocyte apoptosis were investigated by CCK-8, flow cytometry, and western blot. The effects on ECM degradation were examined by western blot and immunofluorescence. The potential mechanism was explored by western blot and Co-IP assays.

RESULTS

Downregulated CHMP5 was identified by proteomics in OA patient cartilages, which was verified in human and mouse articular cartilages. CHMP5 overexpression repressed cell apoptosis and ECM degradation in OA chondrocytes. However, silencing CHMP5 exacerbated OA chondrocyte apoptosis and ECM degradation. Furthermore, we found that the protective effect of CHMP5 against OA was involved in nuclear factor kappa B (NF-κB) signaling pathway.

CONCLUSIONS

This study demonstrated that CHMP5 repressed IL-1β-induced chondrocyte apoptosis and ECM degradation and blocked NF-κB activation. It was shown that CHMP5 might be a novel potential therapeutic target for OA in the future.

A programmable arthritis-specific receptor for guided articular cartilage regenerative medicine

Objective

Investigational cell therapies have been developed as disease-modifying agents for the treatment of osteoarthritis (OA), including those that inducibly respond to inflammatory factors driving OA progression. However, dysregulated inflammatory cascades do not specifically signify the presence of OA. Here, we deploy a synthetic receptor platform that regulates cell behaviors in an arthritis-specific fashion to confine transgene expression to sites characterized by cartilage degeneration.

Methods

An scFv specific for type II collagen (CII) was used to produce a synthetic Notch (synNotch) receptor that enables "CII-synNotch" mesenchymal stromal cells (MSCs) to recognize CII fibers exposed in damaged cartilage. Engineered cell activation by both CII-treated culture surfaces and on primary tissue samples was measured via inducible reporter transgene expression. TGFβ3-expressing cells were assessed for cartilage anabolic gene expression via qRT-PCR. In a co-culture with CII-synNotch MSCs engineered to express IL-1Ra, ATDC5 chondrocytes were stimulated with IL-1α, and inflammatory responses of ATDC5s were profiled via qRT-PCR and an NF-κB reporter assay.

Results

CII-synNotch MSCs are highly responsive to CII, displaying activation ranges over 40-fold in response to physiologic CII inputs. CII-synNotch cells exhibit the capacity to distinguish between healthy and damaged cartilage tissue and constrain transgene expression to regions of exposed CII fibers. Receptor-regulated TGFβ3 expression resulted in upregulation of Acan and Col2a1 in MSCs, and inducible IL-1Ra expression by engineered CII-synNotch MSCs reduced pro-inflammatory gene expression in chondrocytes.

Conclusion

This work demonstrates proof-of-concept that the synNotch platform guides MSCs for spatially regulated, disease-dependent delivery of OA-relevant biologic drugs.

Syringaresinol attenuates osteoarthritis via regulating the NF-κB pathway

Osteoarthritis (OA) is a now regarded as a worldwide whole joint disease with synovial inflammation, cartilage degeneration, and subchondral sclerosis. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used drugs for OA treatment which only relieve the symptoms and restrain the progression of OA. However, various severe adverse effects often occur in patients with long-term NSAIDs use, which heavily burdens the healthcare system and impacts the quality of life. Therefore, it is much imperative to identify alternative drugs with increased efficacy. Syringaresinol (Syr), a naturally occurring phytochemical which belonging to the lignan group of polyphenols, shows anti-tumor and anti-oxidant activities, which to benefit human health. Studies has shown Syr can regulate the inflammatory response by modulating the secretion and expression level of cytokines IL-6, IL-8, and tumor necrosis factor (TNF)-α. it also shows the inhibitory effect on NF-κB pathway in mouse cells. In the present study, we aimed to demonstrate the anti-inflammatory effects of Syr in OA. In vitro Syr treatment in IL-1β-activated mouse chondrocytes significantly restrained the expression of NO, PGE2, IL-6, TNF-α, INOS, COX-2 and MMP-13. Moreover, it considerably ameliorated the degradation of aggrecan and collagen II. Furthermore, the phosphorylation of the NF-kB signaling pathway was significantly suppressed by Syr. Moreover, in vivo, the cartilage degeneration was attenuated and the increased Osteoarthritis Research Society International (OARSI) scores were reversed in the DMM + Syr group, comprared to those in the DMM group. In sum, our study demonstrated that Syr can attenuate the inflammation in vitro and further verified its effect on OA in vivo. Thus, Syr might be a potent therapeautic alternative for OA treatment.

Tenacissoside G alleviated osteoarthritis through the NF-κB pathway both in vitro and in vivo

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease characterized by the destruction of articular cartilage. Tenacissoside G is a flavonoid isolated from the dry roots of Marsdenia tenacissima (Roxb) and has been shown to have anti-inflammatory effects. However, there is no report on the protective effects of Tenacissoside G on OA.

OBJECTIVES

To identify the effects and mechanism of Tenacissoside G on OA.

METHODS

In vitro, primary mouse chondrocytes were induced with IL-1β to establish OA model. mRNA expression of MMP-13, MMP-3, TNF-α, IL-6 and iNOS, was detected by PCR. Protein expression of Collagen-II, MMP-13, p65, p-p65, and IκBα was detected by Western blot. Collagen-II in chondrocytes was also detected by immunofluorescence. In vivo, we established DMM OA mice model. The preventive effect of Tenacissoside G on OA was observed by micro-CT and histological analysis.

RESULTS

In vitro, Tenacissoside G significantly inhibited the expression of iNOS, TNF-α, IL-6, MMP-3, MMP-13 and the degradation of collagen-II, Tenacissoside G also significantly suppressed NF-κB activation in chondrocytes by IL-1β-stimulated. In vivo, we demonstrated Tenacissoside G can decrease articular cartilage damage and reduce OARSI score.

CONCLUSION

These results suggest that Tenacissoside G may serve as a potential drug for the prevention and treatment of OA.

Stevioside targets the NF-κB and MAPK pathways for inhibiting inflammation and apoptosis of chondrocytes and ameliorates osteoarthritis in vivo

Osteoarthritis (OA) is a joint disease that is characterized by articular cartilage degeneration and destruction. Stevioside (SVS) is a diterpenoid glycoside extracted from Stevia rebaudiana Bertoni with some specific effects against inflammatory and apoptotic, whereas it is still unclear what function SVS has in osteoarthritis. This study focuses on the anti-inflammatory and anti-apoptosis functions of SVS on chondrocytes induced by interleukin (IL)-1beta, and the role of SVS in an osteoarthritis model for mice. We can detect the production of inflammatory factors such as nitric oxide (NO) and prostaglandin E2 (PGE2) using real-time quantitative polymerase chain reaction (RT-qPCR), the Griess reaction, and enzyme linked immunosorbent assay (ELISA). On the basis of Western blot, we have observed the protein expressions of cartilage matrix metabolism, inflammatory factors, and apoptosis of chondrocytes. Simultaneously, the pharmacological effects of SVS in mice were evaluated by hematoxylin and eosin (HE), toluidine blue, Safranin O, and immunohistochemical staining. The results show that SVS slows extracellular matrix degradation and chondrocyte apoptosis. In addition, SVS mediates its cellular effect by inhibiting the activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways. Meanwhile, molecular docking studies revealed that SVS has excellent binding capabilities to p65, extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK). The study suggests that SVS can be developed as a potential osteoarthritis treatment.

The Protective Effect of Evodiamine in Osteoarthritis: An In Vitro and In Vivo Study in Mice Model

Osteoarthritis (OA) is a chronic disease with high economic burden characterized by cartilage degradation and joint inflammation. Evodiamine (EV), which can be extracted from Evodia rutaecarpa (Rutaceae), is a traditional Chinese medicine to treat inflammation, cardiovascular disorders, infection, and obesity. Studies have shown that EV can suppress the activation of immune cells and restrain the secretion of pro-inflammatory cytokines. However, it is still not well known about its role in the treatment of OA. In this study, we utilized interleukin-1β (IL-1β)–stimulated mouse chondrocytes in vitro and the destabilization of the medial meniscus (DMM) model in vivo to demonstrate the anti-inflammatory properties of EV in OA. The results suggested that EV decreased the generation of NO, IL-6, TNF-α, and PGE2. Meanwhile, the increased expression of iNOS, COX-2, and MMP-13 and the degradation of aggrecan and Col-II were significantly alleviated by EV in IL-1β–activated mouse chondrocytes. Moreover, EV can inhibit the considerable IL-1β–stimulated phosphorylation of the NF-κB signaling pathway and nuclear translocation of p65, compared with the control group. Furthermore, EV alleviated cartilage degeneration and reversed the increased Osteoarthritis Research Society International (OARSI) scores in the OA model in vivo. Our study demonstrates that EV can suppress inflammation in vitro and cartilage degeneration in vivo in OA, which implies that EV may be a potential candidate for the treatment of OA.

Immunologic Contributions Following Rotator Cuff Injury and Development of Cuff Tear Arthropathy

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Rotator cuff tear arthropathy (RCTA) describes a pattern of glenohumeral degenerative changes following chronic rotator cuff tears that is characterized by superior humeral head migration, erosion of the greater tuberosity of the humeral head, contouring of the coracoacromial arch to create a socket for the humeral head, and eventual glenohumeral arthritis.

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Acute and chronic inflammatory changes following rotator cuff tears are thought to contribute to cartilage damage, muscle fibrosis, and fatty infiltration in the glenohumeral joint.

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In vitro animal studies targeting various inflammatory modulators, including macrophages, insulin-like growth factor-I, and transforming growth factor-beta pathways, provide promising therapeutic targets to improve healing after rotator cuff tears.

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The role of platelet-rich plasma in the treatment and prevention of RCTA has been investigated, with conflicting results.

Gene expression profiling of primary fibrochondrocyte cultures in traumatic and degenerative meniscus lesions

PURPOSE

This study aimed to investigate how fibroblastic and chondrocytic properties of human meniscal fibrochondrocytes are affected in culture conditions according to the type of meniscal pathology and localization, and to provide basic information for tissue-engineering studies.

METHODS

Primary fibrochondrocyte cultures were prepared from meniscus samples of patients who had either traumatic tear or degeneration due to osteoarthritis. Cultures were compared in terms of mRNA expression levels of COL1A1, COL2A1, COMP1, HIF1A, HIF2A, and SOX9 and secreted total collagen and sulfated sGAG levels according to the type of meniscal pathology, anatomical localization, and the number of subcultures.

RESULTS

mRNA expression levels of COL1A1, COMP1, HIF1A, HIF2A, and SOX9 were found to be increased in subsequent subcultures in all specimens. COL1A1 mRNA expression levels of both lateral and medial menisci of patients with traumatic tear were significantly higher than in patients with degenerative pathology, indicating a more fibroblastic character. P1 subculture of lateral and P3 or further subculture of medial meniscus showed more fibroblastic characteristics in patients with degenerative pathology. Furthermore, in patients with degenerative pathology, the subcultures of the lateral meniscus (especially on the inner part) presented more chondrocytic characteristics than did those of medial meniscus.

CONCLUSIONS

The mRNA expression levels of the cultures showed significant differences according to the anatomical localization and pathology of the meniscus, indicating distinct chondrocytic and fibroblastic features. This fundamental knowledge would help researchers to choose more efficient cell sources for cell-seeding of a meniscus scaffold, and to generate a construct resembling the original meniscus tissue.

Hydrogen (H2) Alleviates Osteoarthritis by Inhibiting Apoptosis and Inflammation via the JNK Signaling Pathway

BACKGROUND

Osteoarthritis (OA) is a very common condition and leads to joint pain, disability, and price tag all over the world. Pathogenesis of OA is closely related to numerous inflammatory and apoptosis cytokines. Hydrogen (H2) reportedly exhibits a diversity of effects such as anti-apoptotic, anti-inflammatory, and anti-oxidative properties via the JNK pathway. However, it is unknown whether H2 has a protective effect against OA via the JNK signaling pathway. Therefore, the aim of this study was to figure out whether hydrogen has protective effect on chondrocyte and further explore the possible underlying mechanism.

METHODS

The chondrocytes were obtained from the human cartilage tissues. Cells were stimulated by TBHP and treated with hydrogen. In vitro treatment effects were evaluated by Western blot assay, real-time PCR, immunofluorescence and TUNEL method. We conducted mice model of destabilization of the medial meniscus (DMM) and treated with hydrogen. In vivo treatment effects were evaluated by X-ray imaging assay, safranin O (SO) staining, TUNEL staining and immunohistochemical assay.

RESULTS

Our results showed that hydrogen can inhibit inflammatory factors (ADAMTS5 and MMP13) and apoptosis factors (cleaved caspase-3, cytochrome c, and Bax) in TBHP-induced chondrocytes. Furthermore, hydrogen can suppress the activation of JNK signaling pathway, whereas the effect of hydrogen can be abolished by anisomycin (a JNK activator). In vivo results showed that hydrogen can down-regulate the expression of p-JNK and cleaved caspase-3 expression.

CONCLUSION

We uncovered that hydrogen (H2) could alleviate apoptosis response and ECM degradation in human chondrocytes via inhibiting the activation of the JNK signaling pathway. Meanwhile, in the surgically-induced DMM mice model, treatment with hydrogen (H2) performed a significant role in OA progression.

Maltol prevents the progression of osteoarthritis by targeting PI3K/Akt/NF-κB pathway: In vitro and in vivo studies

Osteoarthritis (OA), a prevalent degenerative arthritis disease, principle characterized by the destruction of cartilage and associated with the inflammatory response. Maltol, a product formed during the processing of red ginseng (Panax ginseng, CA Meyer), has been reported to have the potential effect of anti-inflammatory. However, its specific mechanisms are not demonstrated. We investigated the protective effect of maltol in the progression of OA both in vitro and in vivo experiments. Human chondrocytes were pre-treated with maltol (0, 20, 40, 60 μM, 24 hours) and incubated with IL-1β (10 ng/mL, 24 hours) in vitro. Expression of PGE2, TNF-α and NO was measured by the ELISA and Griess reaction. The expression of iNOs, COX-2, aggrecan, ADAMTS-5, MMP-13, IκB-α, p65, P-AKT, AKT, PI3K and P-PI3K was analysed by Western blotting. The expression of collagen II and p65-active protein was detected by immunofluorescence. Moreover, the serious level of OA was evaluated by histological analysis in vivo. We identified that maltol could suppress the IL-1β-stimulated generation of PGE2 and NO. Besides, maltol not only suppressed the production of COX-2, iNOs, TNF-α, IL-6, ADAMTS-5, MMP-13, but also attenuated the degradation of collagen II and aggrecan. Furthermore, maltol remarkably suppressed the phosphorylation of PI3K/AKT and NF-κB induced by IL-1β in human OA chondrocytes. Moreover, maltol could block the cartilage destroy in OA mice in vivo. To date, all data indicate maltol is a potential therapeutic agent by inhibiting inflammatory response via the regulation of NF-κB signalling for OA.

Baicalin promotes extracellular matrix synthesis in chondrocytes via the activation of hypoxia-inducible factor-1α

Chinese herbal extracts are being used increasingly to treat osteoarthritis (OA) in recent years. Baicalin (BA) is an active component of Scutellaria baicalensis Georgi extracts and protects chondrocytes against damage. The aim of the present study was to examine the mechanism of action of BA on chondrocytes from mouse articular cartilage. In total, 44 µM BA and 10 µM hypoxia-inducible-factor-1α (HIF-1α) inhibitor BAY-87-2243 were screened by the [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] method. Alcian blue and Safran O staining were used to investigate the synthesis of extracellular matrix (ECM) in chondrocytes treated with BA. The expression of HIF-1α and chondrogenic marker genes including SOX9, AGG and Col2α was detected by western blotting or reverse-transcription quantitative (RT-qPCR), the expression of PHD1,2,3 and catabolic genes including ADAMTS5, MMP9 and MMP13 were detected by RT-qPCR. To investigate the effect of BA on the ECM synthesis of chondrocytes, 44 µM BA and 10 µM BAY were chosen for further experimentation. It was confirmed that BA at a concentration of 44 µM could significantly promote the secretion of ECM. The expressions of genes including HIF-1α, SOX9, collagen type 2 (Col2α) and aggrecan (AGG) were elevated following BA pretreatment and decreased by subsequent BAY-87-2243 stimulation for 24 h. Compared with untreated chondrocytes, the expressions of genes including ADAMTS5, MMP9, MMP13, PHD1, PHD2 and PHD3 in chondrocytes treated by BA were downregulated, however, BAY-87-2243 reversed the effect of BA on the genes including ADAMTS5, MMP9, MMP13, PHD1, PHD2 and PHD3 in chondrocytes. The findings of the present study suggest that BA may promote ECM synthesis and marker gene expression in chondrocytes by activating HIF-1α. Therefore, BA may represent a novel clinical drug for OA.

Geraniol-mediated osteoarthritis improvement by down-regulating PI3K/Akt/NF-κB and MAPK signals: In vivo and in vitro studies

Osteoarthritis (OA) is a degenerative disease that has received increasing attention among the elderly. Its clinical manifestation is primarily long-term joint pain. Evidence for the pharmacological effects of geraniol in various diseases is accumulating. However, whether geraniol has a therapeutic effect against OA remains to be determined. In this study, we discussed the anti-inflammatory effects of geraniol in IL-1β-induced chondrocytes and the anti-cartilage degradation effects in a mouse model of destabilization of the medial meniscus (DMM). In cell experiments, we found that the treatment of geraniol inhibited the expression of IL-1β-induced PGE2, NO, COX-2, iNOS, TNF-α and IL-6 by western blot, qRT-PCR and immunofluorescence staining. Besides, geraniol inhibited the expression of MMP-9 and ADAMTS-5, and reversed the degradation of aggrecan and type II collagen. Mechanistically, we revealed that geraniol suppressed IL-1β-stimulated PI3K/Akt/NF-κB and MAPK activation. Importantly, we have found in animal experiments that oral treatment of geraniol was beneficial in protecting articular cartilage from degradation. Overall, these data indicated that geraniol may have the potential to be developed as an effective treatment for OA.

Proline-dependent regulation of collagen metabolism

This review is focused on recent data on the role of proline (Pro) in collagen biosynthesis and cellular metabolism. It seems obvious that one of the main substrates for collagen biosynthesis Pro is required to form collagen molecule. The question raised in this review is whether the Pro for collagen biosynthesis is synthesized "de novo", comes directly from degraded proteins or it is converted from other amino acids. Recent data provided evidence that extracellular Pro (added to culture medium) had significant, but relatively little impact on collagen biosynthesis in fibroblasts (the main collagen synthesized cells) cultured in the presence of glutamine (Gln). However, extracellular Pro drastically increased collagen biosynthesis in the cells cultured in Gln-free medium. It suggests that Pro availability determines the rate of collagen biosynthesis and demand for Pro in fibroblasts is predominantly met by conversion from Gln. The potential mechanism of this process as well as possible implication of this knowledge in pharmacotherapy of connective tissue diseases is discussed in this review.

The protective effect of Ellagic acid (EA) in osteoarthritis: An in vitro and in vivo study

Osteoarthritis (OA), a progressive joint disorder, is principally characterized by the degeneration and destruction of the articular cartilage. Ellagic acid (EA), a natural polyphenol found in berries and nuts has shown potent anti-inflammatory effects, however, its effects and underlying mechanisms on OA have seldom been systematically illuminated. In this study, we reported the anti-inflammatory effects of Ellagic acid (EA) in the progression of OA in both in vitro and in vivo experiments. in vitro study, IL-1β-induced expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), Nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), prostaglandin E2 (PGE2), and interleukin-6 (IL-6) were inhibited by Ellagic acid (EA). Moreover, Ellagic acid (EA) down-regulated the IL-1β-stimulated matrix metalloproteinase-13 (MMP-13) and thrombospondin motifs 5 (ADAMTS-5) while up-regulated the collagen of type II and aggrecan. Mechanistically, we revealed that Ellagic acid (EA) suppressed nuclear factor kappa B (NF-κB) signaling in IL-1β -induced chondrocytes. And Ellagic acid (EA)-induced protectiveness in OA development was also shown by the DMM model. Taken together, our data indicate that Ellagic acid (EA) may serve as a potential drug for OA treatment.

The Function of PPARγ/AMPK/SIRT-1 Pathway in Inflammatory Response of Human Articular Chondrocytes Stimulated by Advanced Glycation End Products

Accumulation of advanced glycation end products (AGEs) in the articular cartilage is a major risk factor for osteoarthritis (OA). To determine the mechanistic basis of AGE action in OA, we treated human articular chondrocytes with AGEs, and found that they not only up-regulated the pro-inflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α, but also inhibited AMP-activated protein kinase (AMPK) phosphorylation and decreased sirtuin 1 (SIRT-1) levels in a concentration- and time-dependent manner. Pioglitazone, a peroxisome proliferator-activated receptor-γ (PPARγ) agonist restored the inhibited AMPK and SIRT-1 by AGEs. Pre-treatment of the cells with the agonists or antagonists of AMPK and SIRT-1 respectively abolished and augmented the inflammatory state induced by AGEs. Furthermore, AMPK agonist also restored the levels of SIRT-1 in the AGE-stimulated chondrocytes. Our findings indicate AGEs induce an inflammatory response in human articular chondrocytes via the PPARγ/AMPK/SIRT-1 pathway, which is therefore a potential target in OA therapy.

Specific, Sensitive, and Stable Reporting of Human Mesenchymal Stromal Cell Chondrogenesis

IMPACT STATEMENT

The promoter characterized in this study has been made accessible as a resource for the skeletal tissue engineering and regenerative medicine community. When combined with suitable reporter vectors, the resulting tools can be used for noninvasive and/or high-throughput screening of test conditions for stimulating chondrogenesis by candidate stem/progenitor cells. As demonstrated in this study, they can also be used with small animal imaging platforms to monitor the chondrogenic activity of implanted progenitors within orthotopic models of bone and cartilage repair.

Akebia Saponin D suppresses inflammation in chondrocytes via the NRF2/HO-1/NF-κB axis and ameliorates osteoarthritis in mice

Akebia Saponin D promotes the translocation of NRF2 into nucleus, activates NRF2/HO-1 pathway and inhibits NF-κB pathway in chondrocytes, and ultimately alleviates osteoarthritis development.

Remodeling of Human Osteochondral Defects via rAAV-Mediated Co-Overexpression of TGF-β and IGF-I from Implanted Human Bone Marrow-Derived Mesenchymal Stromal Cells

The application of chondrogenic gene sequences to human bone marrow-derived mesenchymal stromal cells (hMSCs) is an attractive strategy to activate the reparative activities of these cells as a means to enhance the processes of cartilage repair using indirect cell transplantation procedures that may improve the repopulation of cartilage lesions. In the present study, we examined the feasibility of co-delivering the highly competent transforming growth factor beta (TGF-β) with the insulin-like growth factor I (IGF-I) in hMSCs via recombinant adeno-associated virus (rAAV) vector-mediated gene transfer prior to implantation in a human model of osteochondral defect (OCD) ex vivo that provides a microenvironment similar to that of focal cartilage lesions. The successful co-overexpression of rAAV TGF-β/IGF-I in implanted hMSCs promoted the durable remodeling of tissue injury in human OCDs over a prolonged period of time (21 days) relative to individual gene transfer and the control (reporter lacZ gene) treatment, with enhanced levels of cell proliferation and matrix deposition (proteoglycans, type-II collagen) both in the lesions and at a distance, while hypertrophic, osteogenic, and catabolic processes could be advantageously delayed. These findings demonstrate the value of indirect, progenitor cell-based combined rAAV gene therapy to treat human focal cartilage defects in a natural environment as a basis for future clinical applications.

Nobiletin Inhibits IL-1β-Induced Inflammation in Chondrocytes via Suppression of NF-κB Signaling and Attenuates Osteoarthritis in Mice

Osteoarthritis (OA), a common degenerative joint disease, is principally characterized by inflammation and destruction of cartilage. Nobiletin, an extract of the peel of citrus fruits, is known to have anti-inflammatory properties. However, the mechanisms by which nobiletin plays a protective role in osteoarthritis (OA) are not completely understood. In the present study, we investigated the anti-inflammatory effects of nobiletin in the progression of OA in both in vitro and in vivo experiments. Mouse chondrocytes were pretreated with nobiletin (0, 10, 20, 40 μM) for 24 h and then incubated with IL-1β (10 ng/ml, 24 h) in vitro. The generation of PGE2 and NO was evaluated by the Griess reaction and ELISAs. The protein expression of inducible nitric oxide synthase, matrix metalloproteinase-3, matrix metalloproteinase-13, A disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS5), cyclooxygenase-2, collagen II, and aggrecan was analyzed by Western blotting. Immunofluorescence and Western blot analysis were used to detect nuclear factor-κB (NF-κB) signaling molecules. Induction of proinflammatory and catabolic mediators by IL-1β stimulation of mouse chondrocytes could be partially blocked by treatment with nobiletin or ammonium pyrrolidine dithiocarbamate (an NF-κB inhibitor). Furthermore, our results indicated that nobiletin exhibited a therapeutic effect through active inhibition of the NF-κB signaling pathway. In a mouse model of OA, injection of nobiletin (20 mg/kg) every 2 days for 8 weeks after surgery inhibited cartilage destruction and synovitis. Taken together, our findings suggest that nobiletin may be a potential therapeutic agent for the treatment of OA.

Peptides from Antarctic Krill ( Euphausia superba) Improve Osteoarthritis via Inhibiting HIF-2α-Mediated Death Receptor Apoptosis and Metabolism Regulation in Osteoarthritic Mice

Osteoarthritis (OA) is a prevalent debilitating disease which is predominantly characterized by cartilage degeneration. In the current study, destabilization of the medial meniscus (DMM) mouse model was used to investigate the effects of Antarctic krill peptides (AKP) on cartilage protection. As observed, AKP clearly ameliorate cartilage degeneration as evidenced by increased cartilage thickness and cartilage area and decreased histological Osteoarthritis Research Society International (OARSI) scores. Toluidine blue staining showed that AKO remarkably inhibited the loss of cartilage matrix in mice with OA. Hypoxia-inducible factor-2α (HIF-2α) has a key role in catabolic regulation and inflammation cascades which are the main causes of OA. AKP can down-regulate the expression of HIF-2α and its downstream genes such as MMP-13, Adamts-5, IL-1β, iNOS, CXCL-1, and NOS₂. Consistent with this, anabolic genes such as Acan and Col2α1 were restored after treatment with AKP. Chondrocyte apoptosis and the reduction in cartilage cell viability are also involved in the process of OA. The HIF-2α-mediated death receptor apoptosis signaling pathway has been involved in the regulation of chondrocyte apoptosis. AKP can reduce the expressions of key pro-apoptosis genes in Fas-FasL and DR3-DR3L signaling pathways such as Fas, FasL, FADD, caspase8, caspase3, DR3, DR3L, RIP, and NF-κB. In addition, expressions of antiapoptosis genes such as c-AIP and c-FLIP were increased significantly. These findings indicate that AKP can be used as a new functional factor in the development of functional foods and chondroprotective drugs.

The antiviral protein viperin regulates chondrogenic differentiation via CXCL10 protein secretion

Viperin (also known as radical SAM domain–containing 2 (RSAD2)) is an interferon-inducible and evolutionary conserved protein that participates in the cell's innate immune response against a number of viruses. Viperin mRNA is a substrate for endoribonucleolytic cleavage by RNase mitochondrial RNA processing (MRP) and mutations in the RNase MRP small nucleolar RNA (snoRNA) subunit of the RNase MRP complex cause cartilage-hair hypoplasia (CHH), a human developmental condition characterized by metaphyseal chondrodysplasia and severe dwarfism. It is unknown how CHH-pathogenic mutations in RNase MRP snoRNA interfere with skeletal development, and aberrant processing of RNase MRP substrate RNAs is thought to be involved. We hypothesized that viperin plays a role in chondrogenic differentiation. Using immunohistochemistry, real-time quantitative PCR, immunoblotting, ELISA, siRNA-mediated gene silencing, plasmid-mediated gene overexpression, label-free MS proteomics, and promoter reporter bioluminescence assays, we discovered here that viperin is expressed in differentiating chondrocytic cells and regulates their protein secretion and the outcome of chondrogenic differentiation by influencing transforming growth factor β (TGF-β)/SMAD family 2/3 (SMAD2/3) activity via C-X-C motif chemokine ligand 10 (CXCL10). Of note, we observed disturbances in this viperin–CXCL10–TGF-β/SMAD2/3 axis in CHH chondrocytic cells. Our results indicate that the antiviral protein viperin controls chondrogenic differentiation by influencing secretion of soluble proteins and identify a molecular route that may explain impaired chondrogenic differentiation of cells from individuals with CHH.

UP1306: A Composition Containing Standardized Extracts of Acacia catechu and Morus alba for Arthritis Management

Osteoarthritis (OA) is characterized by progressive articular cartilage degradation. Although there have been significant advances in OA management, to date, there are no effective treatment options to modify progression of the disease. We believe these unmet needs could be bridged by nutrients from natural products. Collagen induced arthritis in rats was developed and utilized to evaluate anti-inflammatory and cartilage protection activity of orally administered botanical composition, UP1306 (50 mg/kg) and Methotrexate (75 µg/kg) daily for three weeks. Objective arthritis severity markers, urine, synovial lavage, and serum were collected. At necropsy, the hock joint from each rat was collected for histopathology analysis. Urinary cartilage degradation marker (CTX-II), pro-inflammatory cytokines (tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and IL-6), and proteases (Matrix Metallopeptidase 3 (MMP3) and 13) were measured. Rats treated with UP1306 showed statistically significant improvements in arthritis severity markers, including uCTX-II (91.4% vs. collagen-induced arthritis (CIA)), serum IL-1β, TNF-α, and IL-6 levels as well as synovial MMP-13. The histopathology data were also well aligned with the severity score of arthritis for both UP1306 and Methotrexate. UP1306, a botanical composition that contains a standardized blend of extracts from the heartwood of Acacia catechu and the root bark of Morus alba, could potentially be considered as a dietary supplement product for the management of arthritis.

Urolithin A targets the PI3K/Akt/NF-κB pathways and prevents IL-1β-induced inflammatory response in human osteoarthritis: in vitro and in vivo studies

Osteoarthritis (OA) is a degenerative joint disease, whose progression is closely related to the inflammatory environment.

Recently highlighted nutraceuticals for preventive management of osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disease of articular cartilage with limited treatment options. This reality encourages clinicians to suggest preventive measures to delay and contain the outbreak of the pathological conditions. Articular cartilage and synovium suffering from OA are characterised by an inflammatory state and by significant oxidative stress, responsible for pain, swelling and loss of mobility in the advanced stages. This review will focus on the ability of olive oil to exert positive effects on the entire joint to reduce pro-inflammatory cytokine release and increase lubricin synthesis, olive leaf extract, since it maintains lubrication by stimulating high molecular weight hyaluronan synthesis in synovial cells, curcumin, which delays the start of pathological cartilage breakdown, sanguinarine, which downregulates catabolic proteases, vitamin D for its capacity to influence the oxidative and pro-inflammatory environment, and carnosic acid as an inducer of heme oxygenase-1, which helps preserve cartilage degeneration. These molecules, considered as natural dietary supplements, appear like a cutting-edge answer to this tough health problem, playing a major role in controlling homeostatic balance loss and slowing down the pathology progression. Natural or food-derived molecules that are able to exert potential therapeutic effects are known as “nutraceutical”, resulting from the combination of the words “nutrition” and “pharmaceutical”. These compounds have gained popularity due to their easy availability, which represents a huge advantage for food and pharmaceutical industries. In addition, the chronic nature of OA implies the use of pharmacological compounds with proven long-term safety, especially because current treatments like nonsteroidal anti-inflammatory drugs and analgesics improve pain relief but have no effect on degenerative progression and can also cause serious side effects.

Effects of TGF-β Overexpression via rAAV Gene Transfer on the Early Repair Processes in an Osteochondral Defect Model in Minipigs

BACKGROUND

Application of the chondrogenic transforming growth factor beta (TGF-β) is an attractive approach to enhance the intrinsic biological activities in damaged articular cartilage, especially when using direct gene transfer strategies based on the clinically relevant recombinant adeno-associated viral (rAAV) vectors.

PURPOSE

To evaluate the ability of an rAAV-TGF-β construct to modulate the early repair processes in sites of focal cartilage injury in minipigs in vivo relative to control (reporter lacZ gene) vector treatment.

STUDY DESIGN

Controlled laboratory study.

METHODS

Direct administration of the candidate rAAV-human TGF-β (hTGF-β) vector was performed in osteochondral defects created in the knee joint of adult minipigs for macroscopic, histological, immunohistochemical, histomorphometric, and micro-computed tomography analyses after 4 weeks relative to control (rAAV- lacZ) gene transfer.

RESULTS

Successful overexpression of TGF-β via rAAV at this time point and in the conditions applied here triggered the cellular and metabolic activities within the lesions relative to lacZ gene transfer but, at the same time, led to a noticeable production of type I and X collagen without further buildup on the subchondral bone.

CONCLUSION

Gene therapy via direct, local rAAV-hTGF-β injection stimulates the early reparative activities in focal cartilage lesions in vivo.

CLINICAL RELEVANCE

Local delivery of therapeutic (TGF-β) rAAV vectors in focal defects may provide new, off-the-shelf treatments for cartilage repair in patients in the near future.

Piceatannol inhibits the IL-1β-induced inflammatory response in human osteoarthritic chondrocytes and ameliorates osteoarthritis in mice by activating Nrf2

Osteoarthritis (OA) is a complex process, to which an inflammatory environment contributes markedly. Piceatannol exerts anti-inflammatory effects on several diseases. In the current study, we explored the protective effects of piceatannol on the progression of OA and investigated its molecular target. In vitro, piceatannol not only attenuated the over-production of inflammatory mediators and cytokines-such as nitric oxide (NO), prostaglandin E2 (PGE₂), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6)-but also suppressed the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) at both the mRNA and protein levels. Piceatannol also decreased the expression of metalloproteinase 13 (MMP13) and thrombospondin motifs 5 (ADAMTS5), which mediate extracellular matrix degradation. Mechanistically, we found that piceatannol inhibited IL-1β-induced nuclear factor kappa B (NF-κB) activation by activating the nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway. Furthermore, piceatannol exerted protective effects in a mouse model of OA. Taken together, these findings indicate that piceatannol may be a potential therapeutic agent for OA.

α2-Macroglobulin: Autologous Protease Inhibition Technology

α₂-Macroglobulin (A2M) is a plasma glycoprotein best known for its ability to inhibit a broad spectrum of serine, threonine, and metalloproteases as well as inflammatory cytokines by a unique bait-and-trap method. A2M has emerged as a unique potential treatment of cartilage-based pathology and inflammatory arthritides. This article describes the unique method by which A2M not only inhibits the associated inflammatory cascade but also disrupts the catabolic process of cartilage degeneration. Autologous concentrated A2M from plasma is currently in use to successfully treat various painful arthritides. Future directions will focus on recombinant variants that enhance its anti-inflammatory and disease-modifying potential.

PPAR-δ Agonist With Mesenchymal Stem Cells Induces Type II Collagen-Producing Chondrocytes in Human Arthritic Synovial Fluid

Osteoarthritis (OA) is an inflammatory joint disease characterized by degeneration of articular cartilage within synovial joints. An estimated 27 million Americans suffer from OA, and the population is expected to reach 67 million in the United States by 2030. Thus, it is urgent to find an effective treatment for OA. Traditional OA treatments have no disease-modifying effect, while regenerative OA therapies such as autologous chondrocyte implantation show some promise. Nonetheless, current regenerative therapies do not overcome synovial inflammation that suppresses the differentiation of mesenchymal stem cells (MSCs) to chondrocytes and the expression of type II collagen, the major constituent of functional cartilage. We discovered a synergistic combination that overcame synovial inflammation to form type II collagen-producing chondrocytes. The combination consists of peroxisome proliferator–activated receptor (PPAR) δ agonist, human bone marrow (hBM)-derived MSCs, and hyaluronic acid (HA) gel. Interestingly, those individual components showed their own strong enhancing effects on chondrogenesis. GW0742, a PPAR-δ agonist, greatly enhanced MSC chondrogenesis and the expression of type II collagen and glycosaminoglycan (GAG) in hBM-MSC-derived chondrocytes. GW0742 also increased the expression of transforming growth factor β that enhances chondrogenesis and suppresses cartilage fibrillation, ossification, and inflammation. HA gel also increased MSC chondrogenesis and GAG production. However, neither GW0742 nor HA gel could enhance the formation of type II collagen-producing chondrocytes from hBM-MSCs within human OA synovial fluid. Our data demonstrated that the combination of hBM-MSCs, PPAR-δ agonist, and HA gel significantly enhanced the formation of type II collagen-producing chondrocytes within OA synovial fluid from 3 different donors. In other words, the novel combination of PPAR-δ agonist, hBM-MSCs, and HA gel can overcome synovial inflammation to form type II collagen cartilage within human OA synovial fluid. This novel articularly injectable formula could improve OA treatment in the future clinical application.

Chrysin Attenuates IL-1β-Induced Expression of Inflammatory Mediators by Suppressing NF-κB in Human Osteoarthritis Chondrocytes

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation and inflammation. Chrysin, a natural flavonoid extracted from honey and propolis, has been reported to have anti-inflammatory effects. However, the anti-inflammatory effects of chrysin on OA have not been reported. This study aimed to assess the effects of chrysin on human OA chondrocytes. Human OA chondrocytes were pretreated with chrysin (1, 5, 10 μM) for 2 h and subsequently stimulated with IL-1β for 24 h. Production of NO, PGE2, MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5 was evaluated by the Griess reaction and ELISAs. The messenger RNA (mRNA) expression of COX-2, iNOS, MMP-1, MMP-3, MMP-13, ADAMTS-4, ADAMTS-5, aggrecan, and collagen-II was measured by real-time PCR. The protein expression of COX-2, iNOS, p65, p-p65, IκB-α, and p-IκB-α was detected by Western blot. The protein expression of collagen-II and p65 nuclear translocation was evaluated by immunofluorescence. We found that chrysin significantly inhibited the IL-1β-induced production of NO and PGE2; expression of COX-2, iNOS, MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5; and degradation of aggrecan and collagen-II. Furthermore, chrysin dramatically blocked IL-1β-stimulated IκB-α degradation and NF-κB activation. Taken together, these results suggest that chrysin may be a potential agent in the treatment of OA.

Polydatin inhibits the IL-1β-induced inflammatory response in human osteoarthritic chondrocytes by activating the Nrf2 signaling pathway and ameliorates murine osteoarthritis

Osteoarthritis (OA), which is characterized by progressive degradation of the articular cartilage, is the most prevalent form of human arthritis. Accumulating evidence has shown that polydatin (PD) exerts special biological functions in a variety of diseases. However, whether it protects against OA development has remained unknown. Here, we investigated the anti-inflammatory and chondroprotective effects of PD on interleukin (IL)-1β-induced human osteoarthritic chondrocytes and in the surgical destabilization of medial meniscus mouse (DMM) OA models. In vitro, PD treatment completely suppressed the over-production of pro-inflammatory mediators, including prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), nitric oxide (NO), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and IL-6 in IL-1β-induced human OA chondrocytes. Moreover, PD exerted a suppressive effect on the expression of matrix-degrading proteases, including matrix metalloproteinase 13 (MMP13) and thrombospondin motifs 5 (ADAMTS-5), which leads to the degradation of the extracellular matrix (ECM). Meanwhile, specific inhibition of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) level by short-interfering RNA (siRNA) strongly reversed the anti-inflammatory and chondroprotective effects of PD in human OA chondrocytes. The protective effects of PD were also observed in vivo. In conclusion, our studies demonstrate that PD holds novel therapeutic potential for the development of OA.

Baicalin suppresses IL-1β-induced expression of inflammatory cytokines via blocking NF-κB in human osteoarthritis chondrocytes and shows protective effect in mice osteoarthritis models

Osteoarthritis (OA) is a degenerative joint disease with an inflammatory component that drives the degradation of cartilage extracellular matrix. Baicalin, a predominant flavonoid isolated from the dry root of Scutellaria baicalensis Georgi, has been reported to have anti-inflammatory effects. However, the anti-inflammatory effects of baicalin on OA have not been reported. Our study aimed to investigate the effect of baicalin on OA both in vitro and in vivo. In vitro, human OA chondrocytes were pretreated with baicalin (10, 50, 100μM) for 2h and subsequently stimulated with IL-1β for 24h. Production of NO and PGE2 were evaluated by the Griess reaction and ELISAs. The mRNA expression of COX-2, iNOS, MMP-3, MMP-13, ADAMTS-5, aggrecan and collagen-II were measured by real-time PCR. The protein expression of COX-2, iNOS, MMP-3, MMP-13, ADAMTS-5, p65, p-p65, IκBα and p-IκBα was detected by Western blot. The protein expression of collagen-II was evaluated by immunofluorescence. Luciferase activity assay was used to assess the relative activity of NF-kB. In vivo, the severity of OA was determined by histological analysis. We found that baicalin significantly inhibited the IL-1β-induced production of NO and PGE2, expression of COX-2, iNOS, MMP-3, MMP-13 and ADAMTS-5 and degradation of aggrecan and collagen-II. Furthermore, baicalin dramatically suppressed IL-1β-stimulated NF-κB activation. In vivo, treatment of baicalin not only prevented the destruction of cartilage but also relieved synovitis in mice OA models. Taken together, these results suggest that baicalin may be a potential agent in the treatment of OA.

Developing anti-inflammatory therapeutics for patients with osteoarthritis

OA is the most common joint disorder in the world, but there are no approved therapeutics to prevent disease progression. Historically, OA has been considered a wear-and-tear joint disease, and efforts to identify and develop disease-modifying therapeutics have predominantly focused on direct inhibition of cartilage degeneration. However, there is now increasing evidence that inflammation is a key mediator of OA joint pathology, and also that the link between obesity and OA is not solely due to excessive load-bearing, suggesting therefore that targeting inflammation in OA could be a rewarding therapeutic strategy. In this review we therefore re-evaluate historical clinical trial data on anti-inflammatory therapeutics in OA patients, highlight some of the more promising emerging therapeutic targets and discuss the implications for future clinical trial design.

Anemonin attenuates osteoarthritis progression through inhibiting the activation of IL-1β/NF-κB pathway

The osteoarthritis (OA) progression is now considered to be related to inflammation. Anemonin (ANE) is a small natural molecule extracted from various kinds of Chinese traditional herbs and has been shown to inhibiting inflammation response. In this study, we examined whether ANE could attenuate the progression of OA via suppression of IL‐1β/NF‐κB pathway activation. Destabilization of the medial meniscus (DMM) was performed in 10‐week‐old male C57BL/6J mice. ANE was then intra‐articularly injected into joint capsule for 8 and 12 weeks. Human articular chondrocytes and cartilage explants challenged with interleukin‐1β (IL‐1β) were treated with ANE. We found that ANE delayed articular cartilage degeneration in vitro and in vivo. In particular, proteoglycan loss and chondrocyte hypertrophy were significantly decreased in ANE ‐treated mice compared with vehicle‐treated mice. ANE decreased the expressions of matrix metalloproteinase‐13 (MMP13), A disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5), collagen X (Col X) while increasing Aggrecan level in murine with DMM surgery. ANE treatment also attenuated proteoglycan loss in human cartilage explants treated with IL‐1β ex vivo. ANE is a potent protective molecule for OA; it delays OA progression by suppressing ECM loss and chondrocyte hypertrophy partially by suppressing IL‐1β/NF‐κB pathway activation.

MicroRNA-29b Contributes to Collagens Imbalance in Human Osteoarthritic and Dedifferentiated Articular Chondrocytes

Objective

Decreased expression of collagen type II in favour of collagen type I or X is one hallmark of chondrocyte phenotype changes in osteoarthritic (OA) cartilage. MicroRNA- (miR-) 29b was previously shown to target collagens in several tissues. We studied whether it could contribute to collagen imbalance in chondrocytes with an impaired phenotype.

Methods

After preliminary microarrays screening, miR-29b levels were measured by RT- quantitative PCR in in vitro models of chondrocyte phenotype changes (IL-1β challenge or serial subculturing) and in chondrocytes from OA and non-OA patients. Potential miR-29b targets identified in silico in 3′-UTRs of collagens mRNAs were tested with luciferase reporter assays. The impact of premiR-29b overexpression in ATDC5 cells was studied on collagen mRNA levels and synthesis (Sirius red staining) during chondrogenesis.

Results

MiR-29b level increased significantly in IL-1β-stimulated and weakly in subcultured chondrocytes. A 5.8-fold increase was observed in chondrocytes from OA versus non-OA patients. Reporter assays showed that miR-29b targeted COL2A1 and COL1A2 3′-UTRs although with a variable recovery upon mutation. In ATDC5 cells overexpressing premiR-29b, collagen production was reduced while mRNA levels increased.

Conclusions

By acting probably as a posttranscriptional regulator with a different efficacy on COL2A1 and COL1A2 expression, miR-29b can contribute to the collagens imbalance associated with an abnormal chondrocyte phenotype.

Anti-IL-20 monoclonal antibody inhibited inflammation and protected against cartilage destruction in murine models of osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease characterized by progressive destruction of articular cartilage. Interleukin (IL)-20 is a proinflammatory cytokine involved in the pathogenesis of rheumatoid arthritis. We investigated the role of IL-20 in OA and evaluated whether anti-IL-20 antibody (7E) treatment attenuates disease severity in murine models of surgery-induced OA. Immunohistochemical staining was used to detect IL-20 and its receptors expression in synovial tissue and cartilage from OA patients, and in OA synovial fibroblasts (OASFs) and chondrocytes (OACCs) from rodents with surgery-induced OA. RTQ-PCR and western blotting were used to determine IL-20-regulated OA-associated gene expression in OASFs and OACCs. OA rats and OA mice were treated with 7E. Arthritis severity was determined based on the degree of cartilage damage and the arthritis severity score. We found that IL-20 and its receptors were expressed in OASFs and OACCs. IL-20 induced TNF-α, IL-1β, MMP-1, and MMP-13 expression by activating ERK-1/2 and JNK signals in OASFs. IL-20 not only upregulated MCP-1, IL-6, MMP-1, and MMP-13 expression, but also downregulated aggrecan, type 2 collagen, TGF-β, and BMP-2 expression in OACCs. Arthritis severity was significantly lower in 7E-treated OA rats, and 7E- or MSC-treated OA mice. Therefore, we concluded that IL-20 was involved in the progression and development of OA through inducing proinflammatory cytokines and OA-associated gene expression in OASFs and OACCs. 7E reduced the severity of arthritis in murine models of surgery-induced OA. Our findings provide evidence that IL-20 is a novel target and that 7E is a potential therapeutic agent for OA.

Low-grade inflammation as a key mediator of the pathogenesis of osteoarthritis

Osteoarthritis (OA) has long been viewed as a degenerative disease of cartilage, but accumulating evidence indicates that inflammation has a critical role in its pathogenesis. Furthermore, we now appreciate that OA pathogenesis involves not only breakdown of cartilage, but also remodelling of the underlying bone, formation of ectopic bone, hypertrophy of the joint capsule, and inflammation of the synovial lining. That is, OA is a disorder of the joint as a whole, with inflammation driving many pathologic changes. The inflammation in OA is distinct from that in rheumatoid arthritis and other autoimmune diseases: it is chronic, comparatively low-grade, and mediated primarily by the innate immune system. Current treatments for OA only control the symptoms, and none has been FDA-approved for the prevention or slowing of disease progression. However, increasing insight into the inflammatory underpinnings of OA holds promise for the development of new, disease-modifying therapies. Indeed, several anti-inflammatory therapies have shown promise in animal models of OA. Further work is needed to identify effective inhibitors of the low-grade inflammation in OA, and to determine whether therapies that target this inflammation can prevent or slow the development and progression of the disease.

The role of progranulin in arthritis

Progranulin (PGRN) is a growth factor with a unique beads-on-a-string structure that is involved in multiple pathophysiological processes, including anti-inflammation, tissue repair, wound healing, neurodegenerative diseases, and tumorigenesis. This review presents up-to-date information concerning recent studies on the role of PGRN in inflammatory arthritis and osteoarthritis, with a special focus on the involvement of the interactions and interplay between PGRN and tumor necrosis factor receptor (TNFR) family members in regulating such musculoskeletal diseases. In addition, this paper highlights the applications of atsttrin, an engineered protein comprising three TNFR-binding fragments of PGRN, as a promising intervention in treating arthritis.

The Expression of Osteopontin and Wnt5a in Articular Cartilage of Patients with Knee Osteoarthritis and Its Correlation with Disease Severity

Objectives. This study is undertaken to investigate the relation between osteopontin (OPN) and Wnt5a expression in the progression and pathogenesis of osteoarthritis (OA). Methods. 50 cartilage tissues from knee OA patients and normal controls were divided into four groups of severe, moderate, minor, and normal lesions based on the modified grading system of Mankin. Immunohistochemistry and real-time PCR were utilized to analyze the OPN and Wnt5a expression in articular cartilage. Besides, the relations between OPN and Wnt5a expression and the severity of OA were explored. Results. OPN and Wnt5a could be identified in four groups' tissues. Amongst the groups, the intercomparisons of OPN expression levels showed statistical differences (P < 0.01). Besides, the intercomparisons of Wnt5a expression degrees showed statistical differences (P < 0.05), except that between the minor and normal groups (P > 0.05). The scores of Mankin were demonstrated to relate to OPN expression (r = -0.847, P < 0.01) and Wnt5a expression in every group (r = -0.843, P < 0.01). Also, a positive correlation can be observed between the OPN and Wnt5a expression (r = 0.769, P < 0.01). Conclusion. In articular cartilage, the expressions of OPN and Wnt5a are positively related to progressive damage of knee OA joint. The correlation between Wnt5a and OPN might be important to the progression and pathogenesis of knee OA.

Medical ozone therapy as a potential treatment modality for regeneration of damaged articular cartilage in osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease and a growing health problem affecting more than half of the population over the age of 65. It is characterized by inflammation in the cartilage and synovium, resulting in the loss of joint structure and progressive damage to the cartilage. Many pro-inflammatory mediators are elevated in OA, including reactive oxygen species (ROS) such as nitric oxide (NO) and hydrogen peroxide (H₂O₂). Damaged articular cartilage remains a challenge to treat due to the limited self-healing capacity of the tissue and unsuccessful biological interventions. This highlights the need for better therapeutic strategies to heal damaged articular cartilage. Ozone (O₃) therapy has been shown to have positive results in the treatment of OA; however the use of O₃ therapy as a therapeutic agent is controversial. There is a perception that O₃ is always toxic, whereas evidence indicates that when it is applied following a specified method, O₃ can be effective in the treatment of degenerative diseases. The mechanism of action of O₃ therapy in OA is not fully understood and this review summarizes the use of O₃ therapy in the treatment of damaged articular cartilage in OA.

Cartilage stem/progenitor cells are activated in osteoarthritis via interleukin-1β/nerve growth factor signaling

INTRODUCTION

Interleukin-1β (IL-1β) and nerve growth factor (NGF) are key regulators in the pathogenesis of inflammatory arthritis; specifically, IL-1β is involved in tissue degeneration and NGF is involved in joint pain. However, the cellular and molecular interactions between IL-1β and NGF in articular cartilage are not known. Cartilage stem/progenitor cells (CSPCs) have recently been identified in osteoarthritic (OA) cartilage on the basis of their migratory properties. Here we hypothesize that IL-1β/NGF signaling is involved in OA cartilage degeneration by targeting CSPCs.

METHOD

NGF and NGF receptor (NGFR: TrkA and p75NTR) expression in healthy and OA human articular cartilage and isolated chondrocytes was determined by immunostaining, qRT-PCR, flow cytometry and western blot. Articular cartilage derived stem/progenitor cells were collected and identified by stem/progenitor cell characteristics. 3D-cultured CSPC pellets and cartilage explants were treated with NGF and NGF neutralizing antibody, and extracellular matrix changes were examined by sulfated glycosaminoglycan (GAG) release and MMP expression and activity.

RESULTS

Expression of NGF, TrkA and p75NTR was found to be elevated in human OA cartilage. Cellular changes upon IL-1β and/or NGF treatment were then examined. NGF mRNA and NGFR proteins levels were upregulated in cultured chondrocytes exposed to IL-1β. NGF was chemotactic for cells isolated from OA cartilage. Cells isolated on the basis of their chemotactic migration towards NGF demonstrated stem/progenitor cell characteristics, including colony-forming ability, multi-lineage differentiation potential, and stem cell surface markers. The effects of NGF perturbation in cartilage explants and 3D-cultured CSPCs were next analyzed. NGF treatment resulted in extracellular matrix catabolism indicated by increased sGAG release and MMP expression and activity; conversely, treatment with NGF neutralizing antibody inhibited increased MMP levels, and enhanced tissue inhibitor of matrix metalloprotease-1 (TIMP1) expression in OA cartilage explants. NGF blockade with neutralizing antibody also affected cartilage matrix remodeling in 3D-CSPC pellet cultures.

CONCLUSION

Our results strongly suggest that NGF signaling is a contributing factor in articular cartilage degeneration in OA, which likely targets a specific subpopulation of progenitor cells, the CSPCs, affecting their migratory and matrix remodeling activities. These findings provide novel cellular/signaling therapeutic targets in osteoarthritic cartilage.

New developments in the treatment of osteoarthritis - focus on biologic agents

Osteoarthritis (OA) is one of the most common diseases around the world. Medical, social, and financial consequences oblige clinicians, surgeons, and researchers to focus on finding the best treatment option, to eradicate and stop this degenerative joint disease, in order to avoid surgical options which in many instances are over-indicated. Noninvasive treatments, such as anti-inflammatory drugs, physiotherapy, orthotic devices, dietary supplements, have demonstrated lack of effectiveness. The possibility to perform intra-articular injections with hyaluronic acid, corticosteroids, or the newest but criticized treatment based on platelet-rich plasma (PRP) has changed the management of OA disease. The use of PRP has led to many differences in treatment since there is a lack of consensus about protocols, indications, number of doses, cost-effectiveness, and duration of the treatment. Many publications have suggested efficacy in tendon injuries, but when PRP has been indicated to treat cartilage injuries, things are more inconsistent. Some authors have reported their experience treating OA with PRP, and it seems that, if well indicated, it is an option as a supplementary therapy. Therefore, we need to understand that OA is a mechanical disease which not only produces changes in radiographs, but also affects the quality of life. Pathogenesis of OA has been well explained, providing us new knowledge and future possibilities to improve the clinical approach. From basic science to surgery, there is a great field we all need to contribute to, because the general population is aging and total joint replacements should not be the only solution for OA. So herein is an actual review of the developments for treating OA with biologics, intended to be useful for the population inside orthopedics who could be called bio-orthopedists, since OA is a molecular homeostasis disbalance between catabolism and anabolism triggered by mechanical stress.

Determination of effective rAAV-mediated gene transfer conditions to support chondrogenic differentiation processes in human primary bone marrow aspirates

The genetic modification of freshly aspirated bone marrow may provide convenient tools to enhance the regenerative capacities of cartilage defects compared with the complex manipulation of isolated progenitor cells. In the present study, we examined the ability and safety of recombinant adeno-associated virus (rAAV) serotype 2 vectors to deliver various reporter gene sequences in primary human bone marrow aspirates over time without altering the chondrogenic processes in the samples. The results demonstrate that successful rAAV-mediated gene transfer and expression of the lacZ and red fluorescent protein marker genes were achieved in transduced aspirates at very high efficiencies (90-94%) and over extended periods of time (up to 125 days) upon treatment with hirudin, an alternative anticoagulant that does not prevent the adsorption of the rAAV-2 particles at the surface of their targets compared with heparin. Application of rAAV was safe, displaying neither cytotoxic nor detrimental effects on the cellular and proliferative activities or on the chondrogenic processes in the aspirates especially using an optimal dose of 0.5 mg ml(-1) hirudin, and application of the potent SOX9 transcription factor even enhanced these processes while counteracting hypertrophic differentiation. The current findings demonstrate the clinical value of this class of vector to durably and safely modify bone marrow aspirates as a means to further develop convenient therapeutic approaches to improve the healing of cartilage defects.

Acquiring chondrocyte phenotype from human mesenchymal stem cells under inflammatory conditions

An inflammatory milieu breaks down the cartilage matrix and induces chondrocyte apoptosis, resulting in cartilage destruction in patients with cartilage degenerative diseases, such as rheumatoid arthritis or osteoarthritis. Because of the limited regenerative ability of chondrocytes, defects in cartilage are irreversible and difficult to repair. Mesenchymal stem cells (MSCs) are expected to be a new tool for cartilage repair because they are present in the cartilage and are able to differentiate into multiple lineages of cells, including chondrocytes. Although clinical trials using MSCs for patients with cartilage defects have already begun, its efficacy and repair mechanisms remain unknown. A PubMed search conducted in October 2014 using the following medical subject headings (MeSH) terms: mesenchymal stromal cells, chondrogenesis, and cytokines resulted in 204 articles. The titles and abstracts were screened and nine articles relevant to “inflammatory” cytokines and “human” MSCs were identified. Herein, we review the cell biology and mechanisms of chondrocyte phenotype acquisition from human MSCs in an inflammatory milieu and discuss the clinical potential of MSCs for cartilage repair.

Needle-knife therapy improves the clinical symptoms of knee osteoarthritis by inhibiting the expression of inflammatory cytokines

Knee osteoarthritis (KOA) is a degenerative joint disease that occurs mainly in the elderly population. However, there are currently no effective treatments for treating this condition. In this study, the efficacy of needle-knife therapy, a technique of traditional Chinese medicine that has been widely used to treat KOA was investigated. Patients (n=170) with KOA were randomly divided for needle-knife therapy (treatment group) and acupuncture therapy (control group). Outcome evaluation included stiffness, pain, physiological function, overall changes, total symptom score, clinical curative effects and the concentrations of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) in the synovial fluid. The trial was completed in 151 patients (233 knees) from a total of 170 patients (264 knees); the treatment group comprised 76 patients (117 knees) who completed the trial and 9 patients (14 knees) who were removed from the study, and the control group comprised 75 patients (116 knees) who completed the trial and 10 patients (17 knees) who were removed from the study. The symptom scores of KOA in stages I–IV were reduced significantly in the treatment group and those of stages I–III were decreased significantly in the control group. The effective rate of the KOA therapy in the patients of stages III and IV in the treatment group was significantly higher than that in the control group. After treatment, the decrements of IL-1β, IL-6 and TNF-α in the treatment group were greater than those in the control group. These results showed that the use of needle-knife therapy to treat KOA effectively improved the clinical symptoms by inhibiting the expression of inflammatory cytokines.

The roles of catabolic factors in the development of osteoarthritis

Osteoarthritis (OA) is the most prevalent disease of articular joints characterized by joint space narrowing on X-ray, joint pain, and a loss of joint function through progressive cartilage degradation and intermittent synovial inflammation. Current in vitro models of OA are often monolayer cultured primary cells exposed to high concentrations of cytokines or chemokines, usually IL-1β or TNF-α. IL-1β could play a role in the early progression or even initiation of OA as evidenced by many of the in vitro studies. However, the inconsistent or outright lack of detectable IL-1β combined with high concentrations of the natural inhibitor IL-1Ra in the OA synovial fluid makes the idea of OA being IL-1β-driven questionable. Further, other stimulants, including IL-6 and matrix fragments, have been shown in vitro to cause many of the effects seen in OA at relevant concentrations found in the OA synovial fluid. More work with these stimulants and IL-1β-independent models needs to be done. Concurrently, research should be conducted with patients with OA as early as possible in the progression of their disease to be able to potentially identify, target, and treat the initiation of the disease.

Nutraceuticals: potential for chondroprotection and molecular targeting of osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease and a leading cause of adult disability. There is no cure for OA, and no effective treatments which arrest or slow its progression. Current pharmacologic treatments such as analgesics may improve pain relief but do not alter OA disease progression. Prolonged consumption of these drugs can result in severe adverse effects. Given the nature of OA, life-long treatment will likely be required to arrest or slow its progression. Consequently, there is an urgent need for OA disease-modifying therapies which also improve symptoms and are safe for clinical use over long periods of time. Nutraceuticals-food or food products that provide medical or health benefits, including the prevention and/or treatment of a disease-offer not only favorable safety profiles, but may exert disease- and symptom-modification effects in OA. Forty-seven percent of OA patients use alternative medications, including nutraceuticals. This review will overview the efficacy and mechanism of action of commonly used nutraceuticals, discuss recent experimental and clinical data on the effects of select nutraceuticals, such as phytoflavonoids, polyphenols, and bioflavonoids on OA, and highlight their known molecular actions and limitations of their current use. We will conclude with a proposed novel nutraceutical-based molecular targeting strategy for chondroprotection and OA treatment.