Osteoarthritic Cartilage Research Articles

Metformin-Loaded Tannic Acid Nanoparticles Attenuate Osteoarthritis by Promoting Chondrocyte Mitochondria Homeostasis Based on Mitocytosis.

The oxidative stress microenvironment and mitochondrial dysfunction in chondrocytes are key mechanisms in the development of osteoarthritis (OA). Metformin (Met) has demonstrated multiple effects on mitochondria and is regarded as a potential therapeutic agent for OA. The low blood flow characteristics in the joint cavity make targeted local delivery of metformin crucial for its clinical application. In this study, tannic acid (TA), with its natural antioxidant and anti-inflammatory properties, was used to prepare self-assemble Met-loaded TA nanoparticles (NPs). The NPs exhibit excellent reactive oxygen scavenging capability, stability in various media, and an acid-responsive release of Met. In Vitro experiments showed that NPs possess excellent biocompatibility, effectively protecting chondrocyte viability in OA's pathological environment and preventing the senescence phenotype. In addition, NPs promoted the expression of antioxidant elements in chondrocytes, restored mitochondrial membrane potential, and enhanced mitocytosis to improve mitochondrial quality. In vivo experiments further confirmed that intra-articular injection of NPs in rats with post-traumatic OA improves cartilage matrix degradation, osteophyte formation, and subchondral bone sclerosis over 8 weeks. Tissue staining further confirmed the protective effects of NPs on chondrocyte mitochondria. Importantly, both in vivo and in vitro experiments revealed that NPs provided superior cellular protection compared to TA or Met alone. Overall, this study demonstrates that NPs effectively against OA cartilage degeneration, with the advantages of easy preparation, high efficiency, and biosafety.

The miR-6779/XIAP axis alleviates IL-1β-induced chondrocyte senescence and extracellular matrix loss in osteoarthritis.

Osteoarthritis (OA) is a long-term degenerative joint disease worsening over time. Aging and chondrocyte senescence contribute to OA progression. MicroRNAs have been confirmed to regulate different cellular processes. They contribute to OA pathology and may help to identify novel biomarkers and therapies for OA. This study used bioinformatics and experimental investigations to analyze and validate differentially expressed miRNAs in OA that might affect chondrocyte apoptosis and senescence. miR-6779 was found to be significantly down-regulated in OA. Seventy-six of the predicted and miR-6779 targeted genes and the OA-associated disease genes overlapped, and these were enriched in cell proliferation, cell apoptosis, and cell cycle. miR-6779 overexpression remarkably attenuated IL-1β effects on chondrocytes by reducing MMP3 and MMP13 levels, promoting cell apoptosis, suppressing cell senescence, and increasing caspase-3, caspase-9 and reducing P16 and P21 levels. miR-6779 targeted inhibition of X-linked inhibitor of apoptosis protein (XIAP) expression. XIAP knockdown partially improved IL-1β-induced chondrocyte senescence and dysfunction. Lastly, when co-transfected with a miR-6779 agomir, the XIAP overexpression vector partially attenuated the effects of miR-6779 overexpression on chondrocytes; miR-6779 improved IL-1β-induced senescence and dysfunction in chondrocytes through targeting XIAP. miR-6779 is down-regulated, and XIAP is up-regulated in OA cartilage and IL-1β-treated chondrocytes. miR-6779 inhibits XIAP expression, thereby promoting senescent chondrocyte cell apoptosis and reducing chondrocyte senescence and ECM loss through XIAP.

Regulation of senescence-associated secretory phenotypes in osteoarthritis by cytosolic UDP-GlcNAc retention and O-GlcNAcylation.

UDP-GlcNAc serves as a building block for glycosaminoglycan (GAG) chains in cartilage proteoglycans and simultaneously acts as a substrate for O-GlcNAcylation. Here, we show that transporters for UDP-GlcNAc to the endoplasmic reticulum (ER) and Golgi are significantly downregulated in osteoarthritic cartilage, leading to increased cytosolic UDP-GlcNAc and O-GlcNAcylation in chondrocytes. Mechanistically, upregulated O-GlcNAcylation governs the senescence-associated secretory phenotype (SASP) by stabilizing GATA4 via O-GlcNAcylation at S406, which compromises its degradation by p62-mediated selective autophagy. Elevated O-GlcNAcylation in the superficial layer of osteoarthritic cartilage coincides with increased GATA4 levels. The topical deletion of Gata4 in this cartilage layer ameliorates post-traumatic osteoarthritis (OA) in mice while inhibiting O-GlcNAc transferase mitigates OA by decreasing GATA4 levels. Excessive glucosamine-induced O-GlcNAcylation stabilizes GATA4 in chondrocytes and exacerbates post-traumatic OA in mice. Our findings elucidate the role of UDP-GlcNAc compartmentalization in regulating secretory pathways associated with chronic joint inflammation, providing a senostatic strategy for the treatment of OA.

Stromal Vascular Fraction of Adipose Tissue: Prospects for Use in the Treatment of Osteoarthritis and Articular Cartilage Injuries (Literature Review)

Summary. Osteoarthritis (OA) is a chronic, progressive, degenerative-dystrophic joint disease primarily caused by damage to the articular cartilage. Conservative pharmacological treatment of OA consists of prescribing nonsteroidal anti-inflammatory drugs, chondroprotectors, hyaluronic acid injections, and therapeutic blockades with glucocorticosteroids. The use of orthobiological agents represents an alternative method in OA treatment. Among the variety of orthobiological approaches, adipose tissue serves as a new and attractive source of stem cells for the treatment of OA. The stromal vascular fraction creates an environment where stem cells can interact and stimulate regeneration.

GelMA@APPA microspheres promote chondrocyte regeneration and alleviate osteoarthritis via Fgfr2 activation.

In the context of osteoarthritis (OA), a condition marked by joint degeneration, there is a notable absence of efficacious approaches to promote regenerative healing in chondrocytes. Novel therapeutic strategies like nanomicelles-hydrogel microspheres loaded with Astragalus polysaccharide (GelMA@APPA) offer promising avenues for promoting chondrocyte regeneration and mitigating OA progression. Astragalus polysaccharide (APS) has been shown to induce chondrocyte proliferation and promote cartilage matrix secretion, demonstrating biological activity associated with chondrocyte regeneration. However, the clinical efficacy of APS remains uncertain. Therefore, this investigation validated the beneficial impact of APS on reducing knee joint damage severity induced by destabilization of the medial meniscus (DMM) in mice. The application of bioinformatics analysis and in vitro experimentation revealed that fibroblast growth factor receptor 2 (Fgfr2) in chondrocytes is a key target protein for APS in ameliorating OA-induced cartilage injury, as the deletion of chondrocyte Fgfr2 resulted in the complete loss of the therapeutic effect of APS. To enhance the efficacy of APS, we incorporated APS into nanoparticle-laden hydrogel microspheres to further bolster its potential in chondrocyte regeneration therapy. Subsequently, we developed GelMA@APPA, which exhibited no significant cytotoxic effects on normal chondrocytes in vitro and could be efficiently internalized by chondrocytes. Following subsequent in vitro and in vivo experiments, we affirmed the beneficial effects of GelMA@APPA on OA mice and cartilage cells damaged by OA, as well as its enhancement of the therapeutic effects of APS. APS significantly improved knee joint injuries in OA mice. Bioinformatics and in vitro analyses identified Fgfr2 as a critical target protein for APS's regenerative effects. Disruption of Fgfr2 negated APS's benefits. GelMA@APPA demonstrated good biocompatibility, effective internalization by chondrocytes, and enhanced the therapeutic efficacy of APS in experiments conducted both in vitro and in vivo, improving chondrocyte proliferation and reducing apoptosis. This study demonstrates that GelMA@APPA microspheres effectively promote chondrocyte regeneration and OA treatment by activating Fgfr2. These findings suggest a novel therapeutic mechanism for OA and lay the groundwork for future clinical utilization of GelMA@APPA in regenerative medicine.

FSH enhances the inflammatory response of macrophages in the knee joint possibly through the NFκB pathway.

Previous studies have suggested that women with higher follicle-stimulating hormone (FSH) levels have a greater incidence of osteoarthritis (OA) compared to women with lower FSH despite normal estrogen levels. Our previous studies also showed that FSH has a negative effect on cartilage in postmenopausal OA. However, no studies have investigated the effect of FSH on the synovium. Here, we showed that the FSH receptor (FSHR) is expressed on RAW264.7 cells and BMDM (Bone Marrow-Derived Macrophages), and found that FSH stimulation promotes the production and secretion of inflammatory cytokines in synovial macrophages. In RAW264.7 cells, FSH stimulation enhances phosphorylation and nuclear translocation of P65, suggesting the activation of NFκB signaling, while the knockdown of FSHR eliminates the proinflammatory effect of FSH. To further validate these results, we used an ovariectomy mouse model supplemented with FSH and estrogen, and a mouse model with FSH neutralization. We noted that FSHR was expressed on mouse synovial joint membranes. Furthermore, in ovariectomy mice supplemented with estrogen and treated with FSH, synovial macrophages were significantly increased, while the opposite was the case in the FSH neutralizing group, which suggest that FSH triggers an inflammatory response in the synovial tissue in mice. Taken together, our results indicate that FSH is an important regulator in synovial inflammation via NFκB signaling activation and, to some extent, appears to accelerate the development of osteoarthritis.

Potential role of gut-related factors in the pathology of cartilage in osteoarthritis.

Osteoarthritis (OA) is a common progressive degenerative disease. Gut microbiota (GM) and their metabolites have been closely associated with the onset, progression, and pathology of OA. GM and their metabolites may influence the cartilage directly, or indirectly by affecting the gut, the immune system, and the endocrine system. They function through classical pathways in cartilage metabolism and novel pathways that have recently been discovered. Some of them have been used as targets for the prevention and treatment of OA. The current study sought to describe the major pathological signaling pathways in OA chondrocytes and the potential role of gut-related factors in these pathways.

Safety and efficacy of mesenchymal stromal cells mitochondria transplantation as a cell-free therapy for osteoarthritis

ObjectiveThe inflammatory responses from synovial fibroblasts and macrophages and the mitochondrial dysfunction in chondrocytes lead to oxidative stress, disrupt extracellular matrix (ECM) homeostasis, and accelerate the deterioration process of articular cartilage in osteoarthritis (OA). In recent years, it has been proposed that mesenchymal stromal cells (MSC) transfer their functional mitochondria to damaged cells in response to cellular stress, becoming one of the mechanisms underpinning their therapeutic effects. Therefore, we hypothesize that a novel cell-free treatment for OA could involve direct mitochondria transplantation, restoring both cellular and mitochondrial homeostasis.MethodsMitochondria were isolated from Umbilical Cord (UC)-MSC (Mito-MSC) and characterized based on their morphology, phenotype, functions, and their ability to be internalized by different articular cells. Furthermore, the transcriptional changes following mitochondrial uptake by chondrocytes were evaluated using an Affymetrix analysis, Lastly, the dose dependence therapeutic efficacy, biodistribution and immunogenicity of Mito-MSC were assessed in vivo, through an intra-articular injection in male C57BL6 mice in a collagenase-induced OA (CIOA) model.ResultsOur findings demonstrate the functional integrity of Mito-MSC and their ability to be efficiently transferred into chondrocytes, synovial macrophages, and synovial fibroblasts. Moreover, the transcriptomic analysis showed the upregulation of genes involved in stress such as DNA reparative machinery and inflammatory antiviral responses. Finally, Mito-MSC transplantation yielded significant reductions in joint mineralization, a hallmark of OA progression, as well as improvements in OA-related histological signs, with the lower dose exhibiting better therapeutic efficacy. Furthermore, Mito-MSC was detected within the knee joint for up to 24 h post-injection without eliciting an inflammatory response in CIOA mice.ConclusionCollectively, our results reveal that mitochondria derived from MSC are transferred to key articular cells and are retained in the joint without generating an inflammatory immune response mitigating articular cartilage degradation in OA, probably through a restorative effect triggered by the stress antiviral response within OA chondrocytes.

Engineered MSC‐sEVs as a Versatile Nanoplatform for Enhanced Osteoarthritis Treatment via Targeted Elimination of Senescent Chondrocytes and Maintenance of Cartilage Matrix Metabolic Homeostasis

AbstractChondrocyte senescence is an important pathogenic factor causing osteoarthritis (OA) progression through persistently producing pro‐inflammatory factors. Mesenchymal stem cells‐derived small extracellular vesicles (MSC‐sEVs) have shown anti‐inflammatory effects in OA models, while persistent existence of senescent chondrocytes still promotes cartilage destruction. Therefore, improving the targeted elimination ability on senescent chondrocytes is required to facilitate the translation of MSC‐sEVs in OA treatment. In this study, versatile engineered MSC‐sEVs are developed to targetedly clear senescent chondrocytes and maintain cartilage metabolic homeostasis. Specifically, MSC‐sEVs are loaded with siRNA mouse double minute 2 homologue (siMDM2) and modified with cartilage‐targeting peptide WYRGRL‐PEG2K‐DSPE (WPD), named WPD‐sEVssiMDM2. The results demonstrate versatile modification improves the cellular uptake of MSC‐sEVs in chondrocytes, and thus improves the antiaging effects. Importantly, multifunctional modification enhances cartilage penetration ability and extends joint retention time of MSC‐sEVs. In both post‐traumatic OA mice and naturally aged mice, WPD‐sEVssiMDM2 more effectively eliminates senescent chondrocytes and maintained matrix metabolic homeostasis. By using the P53 phosphorylation inhibitor, the essential role MDM2‐P53 pathway in the antiaging function of WPD‐sEVssiMDM2 on chondrocytes is verified. In ex vivo cultured human OA cartilage explants, it is confirmed that WPD‐sEVssiMDM2 alleviates senescent phenotype. Altogether, the findings suggest that WPD‐sEVssiMDM2 have promising translational potential for OA treatment.

MgO@SiO2 nanocapsules: a controlled magnesium ion release system for targeted inhibition of osteoarthritis progression.

Osteoarthritis (OA) is a chronic joint disease characterized by degenerative changes in articular cartilage and chronic inflammation. Recent studies suggest that intra-articular (i.a.) injection of magnesium salts holds promise as a therapeutic approach for OA. However, the rapid diffusion of magnesium ions limits their efficacy, resulting in a short duration of action. To overcome this limitation, we developed a nanoparticle delivery system using MgO@SiO2 core/shell nanoparticles, designed as a depot for the controlled release of magnesium ions. Electron microscopy confirmed the formation of the core/shell structure with silica shells of varying thickness. Release studies demonstrated that the silica coating effectively slows nanoparticle degradation, extending magnesium release to over 72 hours. In a rabbit OA model, i.a. injection of these nanocapsules significantly mitigated the pathological progression of OA within four weeks without inducing systemic toxicity. Immunohistochemical analysis further revealed that MgO@SiO2 nanocapsules alleviate the inflammatory response in OA cartilage by inhibiting the NF-κB/p65 signaling pathway. In summary, this study confirms the potential of intra-articular magnesium supplementation as a therapeutic option for OA and introduces a novel approach to enhance the delivery and efficacy of magnesium ions in OA treatment, addressing a relatively underexplored area in the field.

LncRNA-HHCP5 Regulates KLF5 in ceRNA and m6A Pathways to Inhibit the Progression of Osteoarthritis.

Osteoarthritis (OA) is one of the most common bone disorders and has a serious impact on the quality of life of patients. LncRNA-HCP5 (HCP5) is downregulated in OA tissues. However, the latent function and regulatory mechanisms of HCP5 in OA are unclear. In the current study, IL-1β-induced C28/I2 cells were used to establish an invitro model of OA. The expression of HCP5 in OA cartilage tissue and in the invitro model of OA was detected by RT-qPCR. Cell viability and apoptosis were assessed by CCK-8 and Annexin V-PI double staining. Western blotting was employed to detect the protein expression of MMP-13 and aggrecan. The results showed that the findings suggested that HCP5 was downregulated in OA cartilage tissue and IL-1β-induced C28/I2 cells. HCP5 overexpression greatly enhanced IL-1β-induced proliferation of C28/I2 cells, as well as prevented cell apoptosis and degradation of extracellular matrix (ECM). Besides, we have shown that HCP5 is a ceRNA that regulates KLF5 by sponging miR-375. Furthermore, KLF5 is also regulated by m6A regulation induced by HCP5. Finally, overexpression of miR-375, the m6A modification inhibitor, as well as KLF5 inhibition reversed the impact of HCP5 on IL-1β-induced C28/I2 cells. In summary, the present study demonstrated that the HCP5/KLF5 axis inhibited the progression of osteoarthritis.

Interaction Between YTH Domain-Containing Family Protein 2 and SET Domain-Containing Lysine Methyltransferase 7 Suppresses Autophagy in Osteoarthritis Chondrocytes, Exacerbating Cartilage Damage.

Osteoarthritis (OA) is characterized by progressive cartilage degeneration mediated by various molecular pathways, including inflammatory and autophagic processes. SET domain-containing lysine methyltransferase 7 (SETD7), a methyltransferase, has been implicated in OA pathology. This study investigates the expression pattern of SETD7 in OA and its role in promoting interleukin-1 beta (IL-1β)-induced chondrocyte injury through modulation of autophagy and inflammation. The expression of SETD7 in cartilage tissues from OA patients and healthy controls was quantified using quantitative reverse transcription PCR and Western blot analysis. Small interfering RNA targeting SETD7 (si-SETD7) was transfected into human articular chondrocytes (HACs) treated with IL-1β to examine its impact on cellular viability, apoptosis, inflammatory responses, and autophagy. Functional assays including Cell Counting Kit-8, flow cytometry, enzyme-linked immunosorbent assay, and commercial kits were employed to assess biochemical changes. Interaction between YTH N6-methyladenosine RNA binding protein 2 (YTHDF2) and SETD7 was explored using RNA immunoprecipitation and co-immunoprecipitation assays. SETD7 was overexpressed in OA cartilage compared with controls and increased further upon IL-1β treatment. Knockdown of SETD7 in IL-1β-treated HACs improved cellular viability, decreased apoptosis, and reversed the adverse effects on lactate dehydrogenase release and inflammatory markers (tumor necrosis factor-alpha and interleukin-6) while enhancing antioxidant enzymes (catalase, malondialdehyde, and superoxide dismutase). Additionally, autophagy was restored, as evidenced by changes in the levels of autophagy related 5, Beclin1, and sequestosome 1. Interfering with autophagy using chloroquine negated the protective effects of SETD7 knockdown. Furthermore, YTHDF2 was found to stabilize SETD7 mRNA, influencing its expression and enhancing IL-1β-induced chondrocyte injury. SETD7 plays a critical role in the pathogenesis of OA by modulating chondrocyte survival, apoptosis, inflammation, and autophagy. The interaction between YTHDF2 and SETD7 exacerbates chondrocyte injury under inflammatory conditions, highlighting potential therapeutic targets for OA treatment. The YTHDF2/SETD7 axis offers a novel insight into the molecular mechanisms governing cartilage degeneration in OA.

Harnessing Raman spectroscopy and multimodal imaging of cartilage for osteoarthritis diagnosis

Osteoarthritis (OA) is a complex disease of cartilage characterised by joint pain, functional limitation, and reduced quality of life with affected joint movement leading to pain and limited mobility. Current methods to diagnose OA are predominantly limited to X-ray, MRI and invasive joint fluid analysis, all of which lack chemical or molecular specificity and are limited to detection of the disease at later stages. A rapid minimally invasive and non-destructive approach to disease diagnosis is a critical unmet need. Label-free techniques such as Raman Spectroscopy (RS), Coherent anti-Stokes Raman scattering (CARS), Second Harmonic Generation (SHG) and Two Photon Fluorescence (TPF) are increasingly being used to characterise cartilage tissue. However, current studies are based on whole tissue analysis and do not consider the different and structurally distinct layers in cartilage. In this work, we use Raman spectroscopy to obtain signatures from the superficial (top) and deep (bottom) layer of healthy and osteoarthritic cartilage samples from 64 patients (19 control and 45 OA). Spectra were acquired both in the ‘fingerprint’ region from 700 to 1720 cm− 1 and high-frequency stretching region from 2500 to 3300 cm− 1. Principal component and linear discriminant analysis was used to identify the peaks that contributed significantly to classification accuracy of the different samples. The most pronounced differences were observed at the proline (855 cm− 1 and 921 cm− 1) and hydroxyproline (877 cm− 1 and 938 cm− 1), sulphated glycosaminoglycan (sGAG) (1064 cm− 1 and 1380 cm− 1) frequencies for both control and OA as well as the 1245 cm− 1 and 1272 cm− 1, 1320 cm− 1 and 1345 cm− 1, 1451 cm− 1 collagen modes were altered in OA samples, consistent with expected collagen structural changes. Classification accuracy based on Raman fingerprint spectral analysis of superficial and deep layer cartilage for controls was found to be 97% and 93% on using individual/all spectra and, 100% and 95% on using mean spectra per patient, respectively. OA diseased cartilage was classified with an accuracy of 88% and 84% for individual/all spectra, and 96% and 95% for mean spectra per patient based on analysis of the superficial and the deep layers, respectively. Raman spectra from the C-H stretching region (2500–3300 cm− 1) resulted in high classification accuracy for identification of different layers and OA diseased cartilage but low accuracy for controls. Differential changes in superficial and deep layer cartilage signatures were observed with age (under 60 and over 60 years), in contrast, less significant differences were observed with gender. Prominent chemical changes in the different layers of cartilage were preliminarily imaged using CARS, SHG and TPF. Cell clustering was observed in OA together with differences in pericellular matrix and collagen structure in the superficial and the deep layers correlating with the Raman spectral analysis. The current study demonstrates the potential of Raman Spectroscopy and multimodal imaging to interrogate cartilage tissue and provides insight into the chemical and structural composition of its different layers with significant implications for OA diagnosis for an increasing aging demographic.

In vivo impact on rabbit subchondral bone of viscosupplementation with a hyaluronic acid antioxidant conjugate

ObjectiveThis study aimed to assess the effects of an antioxidant-conjugated Hyaluronic Acid (HA), specifically HA-4-aminoresorcinol (HA4AR), on articular cartilage and subchondral bone in osteoarthritis (OA). We conducted a comparative analysis between HA4AR and a commercially available high molecular weight HA formulation in a rabbit model of OA.Materials and methodsEighteen rabbits underwent unilateral anterior cruciate ligament transection (ACLT) and were divided into three groups of six: Saline-group, HA-group, and HA4AR-group, based on the type of intra-articular injection received. Additionally, eight non-operated contralateral knees served as reference points (Contralateral-group). Six weeks post-surgery, iodine-enhanced micro-computed tomography imaging was used to evaluate articular cartilage volume and thickness, and to assess subchondral bone microarchitecture and mineral density.ResultsCartilage thickness in both the HA and HA4AR groups was comparable to that of the Contralateral group. Notably, there was a significant reduction in subchondral bone plate tissue mineral density in the HA-group when compared to both the HA4AR and Saline groups (p < 0.05). However, no significant differences in trabecular subchondral bone microarchitectural parameters and mineral densities were observed between the HA4AR-group and the Saline-group. When compared to the Contralateral, Saline, and HA4AR groups, the HA-group exhibited a marked decrease in subchondral bone plate tissue mineral density (p < 0.05). Additionally, a significant reduction in trabecular bone volume fraction was noted in the HA-group compared to the Contralateral-group (p < 0.05).ConclusionsThe HA-4AR hydrogel demonstrated significant preservation of subchondral bone plate tissue mineral density compared to HA alone, while other bone microarchitectural parameters remained largely unchanged. These findings indicate that HA-4AR may provide enhanced osteoprotective benefits in the treatment of osteoarthritis.

CRNDE alleviates IL-1β-induced chondrocyte damage by modulating miR-31/NF-κB pathway

BackgroundThe long non-coding RNA CRNDE (CRNDE) has been identified as a lncRNA associated with osteoarthritis (OA), playing a role the age-related degeneration of articular cartilage. However, the precise mechanism by which CRNDE affects the physiological functions of OA chondrocytes remains unclear.MethodsTo simulate the inflammatory conditions observed in OA, interleukin (IL)-1β-stimulated chondrocyte C-28/I2 cells were utilized. The expression levels of CRNDE and miR-31 were assessed using reverse transcription-polymerase chain reaction (RT-PCR). Chondrocyte viability and apoptosis were evaluated through CCK-8 assay and flow cytometry, respectively. The levels of IL-6, IL-1β and Tumor necrosis factor (TNF-α) were determined using enzyme-linked immunosorbent assay (ELISA). mRNA expression levels of MMP-13, Aggrecan and COL2A1 were detected by quantitative RT-PCR. Western blot analysis was performed to evaluate the protein levels of factors related to cartilage matrix degradation, including p-p65, p65 and p-IκBα of the NF-κB pathway.ResultsCRNDE expression was downregulated in both OA cartilage tissues and IL-1β-stimulated chondrocytes. Overexpression of CRNDE mitigated IL-1β-stimulated chondrocytes apoptosis, inflammatory responses, and cartilage matrix degradation. Compared with healthy controls, OA tissues exhibited reduced expression of miR-31, which was negatively correlated with the expression of CRNDE. Additionally, overexpression of miR-31 partially reversed the inhibitory effects of CRNDE on apoptosis, inflammation, cartilage matrix degradation, and the inactivation of Nuclear factor (NF)-κB pathway induced by IL-1β stimulation. Moreover, silencing of CRNDE exacerbated IL-1β-induced chondrocytes damage, which was aliviated by the NF-κB pathway inhibitor, Bay 11-7082.ConclusionCRNDE alleviated IL-1β-induced injuries in OA chondrocytes by suppressing the miR-31-mediated NF-κB signaling pathway.

Screening the phytochemical components of Ruta montana L. for their inhibitory activity to reduce the progress of osteoarthritis: an in silico study

The species Ruta montana L. is well known for its medicinal characteristics. It is employed in traditional medicine where its constituent parts include a variety of physiologically active chemicals that give it its therapeutic potential. Our in silico research on the ligand molecules of R. montana L. shows the inhibitory efficacy of these compounds on the enzymes aggrecanase-1 (ADAMTS-4) and aggrecanase-2 (ADAMTS-5) responsible for the degradation of human articular cartilage in osteoarthritis. By using molecular docking simulation, the interaction between the ligand molecules of the plant researched and these enzymes was identified. These compounds scored higher in the in silico research of the components 2-Undecanol acetate, 2-Nonanol acetate, Nonan-2-one, Psoralen, and Undecan-2-one, corresponding to a larger inhibitory activity when compared to those of the commercially available medications for osteoarthritis.

Defining the extracellular matrix in non-cartilage soft-tissues in osteoarthritis: a systematic review.

Extracellular matrix (ECM) is a critical determinant of tissue mechanobiology, yet remains poorly characterized in joint tissues beyond cartilage in osteoarthritis (OA). This review aimed to define the composition and architecture of non-cartilage soft joint tissue structural ECM in human OA, and to compare the changes observed in humans with those seen in animal models of the disease. A systematic search strategy, devised using relevant matrix, tissue, and disease nomenclature, was run through the MEDLINE, Embase, and Scopus databases. Demographic, clinical, and biological data were extracted from eligible studies. Bias analysis was performed. A total of 161 studies were included, which covered capsule, ligaments, meniscus, skeletal muscle, synovium, and tendon in both humans and animals, and fat pad and intervertebral disc in humans only. These studies covered a wide variety of ECM features, including individual ECM components (i.e. collagens, proteoglycans, and glycoproteins), ECM architecture (i.e. collagen fibre organization and diameter), and viscoelastic properties (i.e. elastic and compressive modulus). Some ECM changes, notably calcification and the loss of collagen fibre organization, have been extensively studied across osteoarthritic tissues. However, most ECM features were only studied by one or a few papers in each tissue. When comparisons were possible, the results from animal experiments largely concurred with those from human studies, although some findings were contradictory. Changes in ECM composition and architecture occur throughout non-cartilage soft tissues in the osteoarthritic joint, but most of these remain poorly defined due to the low number of studies and lack of healthy comparator groups.

Ferroptosis in Osteoarthritis: Towards Novel Therapeutic Strategy.

Osteoarthritis (OA) is a chronic, degenerative joint disease primarily characterised by damage to the articular cartilage, synovitis and persistent pain, and has become one of the most common diseases worldwide. In OA cartilage, various forms of cell death have been identified, including apoptosis, necroptosis and autophagic cell death. Ever-growing observations indicate that ferroptosis, a newly-discovered iron-dependent form of regulated cell death, is detrimental to OA occurrence and progression. In this review, we first analyse the pathogenetic mechanisms of OA by which iron overload, inflammatory response and mechanical stress contribute to ferroptosis. We then discuss how ferroptosis exacerbates OA progression, focusing on its impact on chondrocyte viability, synoviocyte populations and extracellular matrix integrity. Finally, we highlight several potential therapeutic strategies targeting ferroptosis that could be explored for the treatment of OA.

Fibroblast growth factor 7 (FGF7) causes cartilage destruction, subchondral bone remodeling, and the premature growth plate closure in mice

Fibroblast growth factor (FGF) signaling plays a significant role in osteoarthritis (OA) pathogenesis, though the OA-related functions of only a few FGFs have been fully elucidated. This study investigates the specific roles of FGF7 in OA development. FGF7 expression was analyzed in human (n=6) and mouse (n=10) cartilage. Experimental OA was induced by destabilization of the medial meniscus (DMM). The roles of FGF7 were explored using intra-articular (IA) injection of recombinant FGF7 (rFGF7) and whole-body Fgf7 knockout mice (Fgf7-/-). Subchondral bone remodeling and growth plate morphology were assessed micro computed tomography (µCT) and histological analysis. FGF7 was upregulated in OA cartilage. IA injection of rFGF7 led to OA cartilage destruction (OARSI [Osteoarthritis Research Society International] grade; 0.61 [95% CI 0.00-5.33]), while Fgf7-/- mice showed reduced DMM-induced cartilage erosion (OARSI grade; 1.89 [95% CI 1.08-3.00]) compared to wild-type mice (4.92 [95% CI 3.83-5.33]). These effects were associated with changes in matrix-degrading enzyme expression in chondrocytes. Mice receiving IA injection of rFGF7 (20μg) exhibited increased subchondral bone thickness (68.01µm [95% CI 61.55-74.46]) and decreased osteoclastogenesis (tartrate-resistant acid phosphatase positivity; 1.94% [95% CI 1.41-2.47]) compared to controls (38.33µm [95% CI 33.71-42.96]) and (4.23% [95% CI 3.28-5.19]), respectively. Additionally, rFGF7 treatment caused premature closure of growth plates, whereas Fgf7-/- mice exhibited significantly increased growth plate thickness. FGF7 exerts multiple functions in various joint tissues, including promoting cartilage destruction, inducing subchondral bone remodeling (SBP thickening), and triggering premature growth plate closure.

Knockdown of nuclear protein 1 delays pathological pro-gression of osteoarthritis through inhibiting chondrocyte ferroptosis

To investigate the effect of nuclear protein (Nupr) 1 on the pathological progression of osteoarthritis and its relationship with ferroptosis of chondrocytes. Chondrocytes from mouse knees were divided into small interfering RNA (siRNA) control group, small interfering RNA targeting Nupr1 (siNupr1) group, siRNA control+IL-1β group (siRNA control interference for 24 h followed by 10 ng/mL IL-1β) and siNupr1+IL-1β group (siNupr1 interference for 24 h followed by 10 ng/mL IL-1β). The protein and mRNA expressions of Nupr1 were detected by Western blotting and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Cell proliferation viabilities were measured using the cell counting kit-8 method. The levels of ferrous ions were detected by FerroOrange staining. Lipid peroxidation levels were detected by C11-BODIPY-591 fluorescence imaging. The contents of malondialdehyde (MDA) and glutathione (GSH) were detected by enzyme-linked immunosorbent assay. The protein expressions of acyl-CoA synthetase long-chain family (ACSL) 4, P53, glutathione peroxidase (GPX) 4 and solute carrier family 7 member 11 gene (SLC7A11) were detected by Western blotting. The osteoarthritis model was constructed by destabilization of the medial meniscus (DMM) surgery in 7-week-old male C57BL/6J mice. The mice were randomly divided into four groups with 10 animals in each group: sham surgery (Sham)+adeno-associated virus serotype 5 (AAV5)-short hairpin RNA (shRNA) control group, Sham+AAV5-shRNA control targeting Nupr1 (shNupr1) group, DMM+AAV5-shRNA control group, and DMM+AAV5-shNupr1 group. Hematoxylin and eosin staining and Safranin O-Fast Green staining were used to observe the morphological changes in cartilage tissue. The Osteoarthritis Research Society International (OARSI) osteoarthritis cartilage histopathology assessment system was used to evaluate the degree of cartilage degeneration in mice. The mRNA expressions of matrix metallopeptidase (MMP) 13, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) 5, cyclooxy-genase (COX) 2, and GPX4 were detected by qRT-PCR. In vitro experiments showed that knocking down Nupr1 alleviated the decrease of chondrocyte proliferation activity induced by IL-1β, reduced iron accumulation in mouse chondrocytes, lowered lipid peroxidation, downregulated ACSL4 and P53 protein expression and upregulated GPX4 and SLC7A11 protein expression (all P<0.01), thereby inhibiting ferroptosis in mouse chondrocytes. Meanwhile, in vivo animal experiments demonstrated that knocking down Nupr1 delayed the degeneration of articular cartilage in osteoarthritis mice, improved the OARSI score, slowed down the degradation of the extracellular matrix in osteoarthritis cartilage, and reduced the expression of the key ferroptosis regulator GPX4 (all P<0.01). Knockdown of Nupr1 can delay the pathological progression of osteoarthritis through inhibiting ferroptosis in mouse chondrocytes.