Osteoarthritis Model Research Articles

OGT-induced O-GlcNAcylation of NEK7 protein aggravates osteoarthritis progression by enhancing NEK7/NLRP3 axis

Backgrounds The role of O-GlcNAc transferase (OGT)-induced O-linked N-acetylglucosaminylation (O-GlcNAcylation) has been reported in multiple human diseases. However, its specific functions in osteoarthritis (OA) progression remain undetermined. Objective This study focused on the target proteins of OGT-induced O-GlcNAcylation in OA and the specific functional mechanism. Methods The levels of total O-GlcNAc and OGT were measured in both in vitro and in vivo OA models using western blot. The effects of OGT knockout on OA progression were detected through Safranin O staining, immunohistochemical staining and OARSI score evaluation. The effects of OGT silencing on LPS-induced chondrocyte injury were assessed by performing loss-of function assays. Co-immunoprecipitation (co-IP) was conducted to verify the effect of OGT-induced O-GlcNAcylation on the interaction between NEK7 and NLRP3. The role of OGT in modulating the O-GlcNAcylation and phosphorylation levels of NEK7 was analysed using western blot. Results The OGT-indued O-GlcNAcylation level was increased in both in vitro and in vivo OA models. Knockout of OGT mitigated OA progression in model mice. Additionally, silencing of OGT suppressed LPS-induced chondrocyte pyroptosis. Moreover, silencing of OGT inhibited the O-GlcNAcylation and enhanced the phosphorylation of NEK7 at S260 site, thereby blocking the binding of NEK7 with NLRP3. Conclusion OGT-induced NEK7 O-GlcNAcylation promotes OA progression by promoting chondrocyte pyroptosis via the suppressing interaction between NEK7 and NLRP3.

Saikosaponin D alleviates inflammatory response of osteoarthritis and mediates autophagy via elevating microRNA-199-3p to target transcription Factor-4

ObjectiveThis study was to investigate the underlying mechanism by which Saikosaponin D (SSD) mitigates the inflammatory response associated with osteoarthritis (OA) and regulates autophagy through upregulation of microRNA (miR)-199-3p and downregulation of transcription Factor-4 (TCF4).MethodsA mouse OA model was established. Mice were intragastrically administered with SSD (0, 5, 10 μmol/L) or injected with miR-199-3p antagomir into the knee. Then, pathological changes in cartilage tissues were observed. Normal chondrocytes and OA chondrocytes were isolated and identified. Chondrocytes were treated with SSD and/or transfected with oligonucleotides or plasmid vectors targeting miR-199-3p and TCF4. Cell viability, apoptosis, inflammation, and autophagy were assessed. miR-199-3p and TCF4 expressions were measured, and their targeting relationship was analyzed.ResultsIn in vivo experiments, SSD ameliorated cartilage histopathological damage, decreased inflammatory factor content and promoted autophagy in OA mice. miR-199-3p expression was downregulated and TCF4 expression was upregulated in cartilage tissues of OA mice. miR-199-3p expression was upregulated and TCF4 expression was downregulated after SSD treatment. Downregulation of miR-199-3p attenuated the effect of SSD on OA mice. In in vitro experiments, SSD inhibited the inflammatory response and promoted autophagy in OA chondrocytes. Downregulation of miR-199-3p attenuated the effect of SSD on OA chondrocytes. In addition, upregulation of miR-199-3p alone inhibited inflammatory responses and promoted autophagy in OA chondrocytes. miR-199-3p targeted TCF4. Upregulation of TCF4 attenuated the effects of miR-199-3p upregulation on OA chondrocytes.ConclusionsSSD alleviates inflammatory response and mediates autophagy in OA via elevating miR-199-3p to target TCF4.

Chondrocyte membrane-coated nanoparticles promote drug retention and halt cartilage damage in rat and canine osteoarthritis.

Osteoarthritis (OA) is a chronic joint disease characterized by progressive degeneration of articular cartilage. A challenge in the development of disease-modifying drugs is effective delivery to chondrocytes. The unique structure of the joint promotes rapid clearance of drugs through synovial fluid, and the dense and avascular cartilage extracellular matrix (ECM) limits drug penetration. Here, we show that poly(lactide-co-glycolic acid) nanoparticles coated in chondrocyte membranes (CM-NPs) were preferentially taken up by rat chondrocytes ex vivo compared with uncoated nanoparticles. Internalization of the CM-NPs was mediated primarily by E-cadherin, clathrin-mediated endocytosis, and micropinocytosis. These CM-NPs adhered to the cartilage ECM in rat knee joints in vivo and penetrated deeply into the cartilage matrix with a residence time of more than 34 days. Simulated synovial fluid clearance studies showed that CM-NPs loaded with a Wnt pathway inhibitor, adavivint (CM-NPs-Ada), delayed the catabolic metabolism of rat and human chondrocytes and cartilage explants under inflammatory conditions. In a surgical model of rat OA, drug-loaded CM-NPs effectively restored gait, attenuated periarticular bone remodeling, and provided chondroprotection against cartilage degeneration. OA progression was also mitigated by CM-NPs-Ada in a canine model of anterior cruciate ligament transection. These results demonstrate the feasibility of using chondrocyte membrane-coated nanoparticles to improve the pharmacokinetics and efficacy of anti-OA drugs.

Synovia tissue-specific exosomes participate in the dual variation of the osteoarthritis microenvironment via miR-182

Osteoarthritis (OA) is the most common type of joint disease and the leading cause of chronic disability among older adults. As an important component of the joint, synovium influences the inflammatory and degenerative process of OA. This study found that miRNA 182 (miR-182) in synovium-specific exosomes can modulate inflammation and apoptotic signaling. It also regulated different biological functions to promote the progression of OA. Experiments based on rat OA model and synovium samples from OA patients, we found that synovium-derived miR-182 regulates inflammatory response in the early stage of OA by regulating the expression level of forkhead box O-3 (FOXO3). However, the expression of miR-182 was significantly increased in synovial tissue of advanced OA, which was involved in the apoptotic signal of severe OA. These findings suggest that miR-182 may directly regulate OA progression by modulating FOXO3 production inflammation, and apoptosis.

Quercetin as a promising intervention for rat osteoarthritis by decreasing M1-polarized macrophages via blocking the TRPV1-mediated P2X7/NLRP3 signaling pathway.

Osteoarthritis (OA) is characterized by an imbalance between M1 and M2 polarized synovial macrophages. Quercetin has shown protective effects against OA by altering M1/M2-polarized macrophages, but the underlying mechanisms remain unclear. In this study, rat chondrocytes were treated with 10 ng/mL of IL-1β. To create M1-polarized macrophages in vitro, rat bone marrow-derived macrophages (rBMDMs) were treated with 100 ng/mL LPS. To mimic OA conditions observed in vivo, a co-culture system of chondrocytes and macrophages was established. ATP release assays, immunofluorescence assays, Fluo-4 AM staining, Transwell assays, ELISA assays, and flow cytometry were performed. Male adult Sprague-Dawley (SD) rats were used to create an OA model. Histological analyses, including H&E, and safranin O-fast green staining were performed. Our data showed a quercetin-mediated suppression of calcium ion influx and ATP release, with concurrent downregulation of TRPV1 and P2X7 in the chondrocytes treated with IL-1β. Activation of TRPV1 abolished the quercetin-mediated effects on calcium ion influx and ATP release in chondrocytes treated with IL-1β. In the co-culture system, overexpression of P2X7 in macrophages attenuated the quercetin-mediated effects on M1 polarization, migration, and inflammation. Either P2X7 or NLRP3 knockdown attenuated IL-1β-induced M1/M2 polarization, migration, and inflammation. Moreover, overexpression of TRPV1 reduced the quercetin-mediated suppressive effects on OA by promoting M1/M2-polarized macrophages in vivo. Collectively, our data showed that quercetin-induced suppression of TRPV1 leads to a delay in OA progression by shifting the macrophage polarization from M1 to M2 subtypes via modulation of the P2X7/NLRP3 pathway.

Spermidine ameliorates osteoarthritis via altering macrophage polarization

ObjectiveSpermidine (SPD) is an anti-aging natural substance, and it exerts effects through anti-apoptosis and anti-inflammation. However, the specific protective mechanism of SPD in osteoarthritis (OA) remains unclear. Here, we explored the role of SPD on the articular cartilage and the synovial tissue, and tested whether the drug would regulate the polarization of synovial macrophages by in vivo and in vitro experiments. MethodsBy constructing an OA model in mice, we preliminarily explored the protective effect of SPD on the articular cartilage and the synovial tissue. Meanwhile, we isolated and cultured human primary chondrocytes and bone marrow-derived macrophages (BMDMs), and prepared a conditioned medium (CM) to explore the specific protective effect of SPD in vitro. ResultsWe found that SPD alleviated cartilage degeneration and synovitis, increased M2 polarization and decreased M1 polarization in synovial macrophages. In vitro experiments, SPD inhibited ERK MAPK and p65/NF-κB signaling in macrophages, and transformed macrophages from M1 to M2 subtypes. Interestingly, SPD had no direct protective effect on chondrocytes in vitro; however, the conditioned medium (CM) from M1 macrophages treated with SPD promoted the anabolism and inhibited the catabolism of chondrocytes. Moreover, this CM markedly suppressed IL-1β-induced p38/JNK MAPK signaling pathway activation in chondrocytes. ConclusionsThis work provides new perspectives on the role of SPD in OA. SPD does not directly target chondrocytes, but can ameliorate the degradation of articular cartilage through regulating M1/M2 polarization of synovial macrophages. Hence, SPD is expected to be the potential therapy for OA.

Songorine modulates macrophage polarization and metabolic reprogramming to alleviate inflammation in osteoarthritis.

Osteoarthritis (OA) is a prevalent joint disorder characterized by multifaceted pathogenesis, with macrophage dysregulation playing a critical role in perpetuating inflammation and joint degeneration. This study focuses on Songorine, derived from Aconitum soongaricum Stapf, aiming to unravel its therapeutic mechanisms in OA. Comprehensive analyses, including PCR, Western blot, and immunofluorescence, were employed to evaluate Songorine's impact on the joint microenvironment and macrophage polarization. RNA-seq analysis was conducted to unravel its anti-inflammatory mechanisms in macrophages. Metabolic alterations were explored through extracellular acidification rate monitoring, molecular docking simulations, and PCR assays. Oxygen consumption rate measurements were used to assess mitochondrial oxidative phosphorylation, and Songorine's influence on macrophage oxidative stress was evaluated through gene expression and ROS assays. Songorine effectively shifted macrophage polarization from a pro-inflammatory M1 phenotype to an anti-inflammatory M2 phenotype. Notably, Songorine induced metabolic reprogramming, inhibiting glycolysis and promoting mitochondrial oxidative phosphorylation. This metabolic shift correlated with a reduction in macrophage oxidative stress, highlighting Songorine's potential as an oxidative stress inhibitor. In an in vivo rat model of OA, Songorine exhibited protective effects against cartilage damage and synovial inflammation, emphasizing its therapeutic potential. This comprehensive study elucidates Songorine's multifaceted impact on macrophage modulation, metabolic reprogramming, and the inflammatory microenvironment, providing a theoretical foundation for its therapeutic potential in OA.

One-step stromal vascular fraction therapy in osteoarthritis with tropoelastin-enhanced autologous stromal vascular fraction gel.

Background: Osteoarthritis (OA) is a debilitating degenerative joint disease, leading to significant pain and disability. Despite advancements, current regenerative therapies, such as mesenchymal stem cells (MSCs), face challenges in clinical efficacy and ethical considerations. This study aimed to evaluate the therapeutic potential of stromal vascular fraction gel (SVF-gel) in comparison to available treatments like hyaluronic acid (HA) and adipose-derived stem cells (ADSCs) and to assess the enhancement of this potential by incorporating tropoelastin (TE). Methods: We conducted a comparative laboratory study, establishing an indirect co-culture system using a Transwell assay to test the effects of HA, ADSCs, SVF-gel, and TE-SVF-gel on osteoarthritic articular chondrocytes (OACs). Chondrogenic and hypertrophic markers were assessed after a 72-hour co-culture. SVF-gel was harvested from rat subcutaneous abdominal adipose tissue, with its mechanical properties characterized. Cell viability was specifically analyzed for SVF-gel and TE-SVF-gel. The in vivo therapeutic effectiveness was further investigated in a rat model of OA, examining MSCs tracking, effects on cartilage matrix synthesis, osteophyte formation, and muscle weight changes. Results: Cell viability assays revealed that TE-SVF-gel maintained higher cell survival rates than SVF-gel. In comparison to the control, HA, and ADSCs groups, SVF-gel and TE-SVF-gel significantly upregulated the expression of chondrogenic markers COL 2, SOX-9, and ACAN and downregulated the hypertrophic marker COL 10 in OACs. The TE-SVF-gel showed further improved expression of chondrogenic markers and a greater decrease in COL 10 expression compared to SVF-gel alone. Notably, the TE-SVF-gel treated group in the in vivo OA model exhibited the most MSCs on the synovial surface, superior cartilage matrix synthesis, increased COL 2 expression, and better muscle weight recovery, despite the presence of fewer stem cells than other treatments. Discussion: The findings suggest that SVF-gel, particularly when combined with TE, provides a more effective regenerative treatment for OA by enhancing the therapeutic potential of MSCs. This combination could represent an innovative strategy that overcomes limitations of current therapies, offering a new avenue for patient treatment. Further research is warranted to explore the long-term benefits and potential clinical applications of this combined approach.

Protective effects of pulsed electromagnetic field therapy attenuates autophagy and apoptosis in osteoporotic osteoarthritis model rats by activating PPARγ

ABSTRACT Osteoporotic osteoarthritis (OPOA) is a specific phenotype of OA with high incidence and severe cartilage damage. This study aimed to explore the protective efficacy of PEMF on the progression of OPOA and observed the effects of PEMF on PPARγ, autophagy- and apoptosis-related proteins in OPOA rats. Rats were randomly divided into three groups: control group, OPOA group, and PEMF group (n = 6). One week after surgery, the rats in PEMF group were subjected to PEMF (3.82 mT, 8 Hz, 40 min/day and 5 day/week) for 12 weeks. Results showed that PEMF retarded cartilage degeneration and bone loss, as evidenced by pathological staining image, decreased MMP-13 expression and increased bone mineral density. PEMF inhibited the serum levels of inflammatory cytokines, and the expressions of caspase-3 and caspase-8, while upregulated the expression of PPARγ. Moreover, PEMF significantly improved the autophagy disorders, represented by decrease expressions of Beclin-1, P62, and LC3B. The research demonstrates that PEMF can effectively prevent cartilage and subchondral bone destruction in OPOA rats. The potential mechanism may be related to upregulation of PPARγ, inhibition of chondrocyte apoptosis and inflammation, and improvement of autophagy disorder. PEMF therapy thus shows promising application prospects in the treatment of postmenopausal OA.

Green synthesis of gold nanoparticles mediated by extract of Curcuma longa under ultrasonic condition: Investigation of its application for reduction of dye pollutants and repairing the articular cartilage in an animal model of osteoarthritis of the knee

For environmental remediation, it is crucial to find effective heterogeneous catalysts that can remove organic contaminants or convert them into chemicals that are safe and even valuable. Here, we present the synthesis of a green gold-based catalyst using an extract of Curcuma longa (Au NPs@C. longa) under ultrasonic condition. This nanocatalyst demonstrated good performance for reduction of organic dyes including methyl orange, methylene blue, and 4-nitrophenol. FE-SEM in conjunction with EDS, TEM, and UV–visible spectroscopy were used to evaluate the produced nanocatalyst. The Au NPs@C. longa should show great promise for wastewater treatment since it has the advantages of good activity, good kinetics and suitable stability for dye reduction. In the orthopedic experiments, the efficacy of Au NPs@C. longa on chondrogenesis was assessed by the primary cultured chondrocytes. Western blot, PCR, and histological assays were done to follow the underlying mechanisms. We evaluated the functional recovery after Au NPs@C. longa transplantation by an osteoarthritis articular cartilage injury model in knee. In immunological section, the Au NPs@C. longa reduced the levels of TNF-α, IL-1β, MMPs, and p-p65 expression. This may be caused by adjusting cellular redox homeostasis related to the Nrf2. The data indicated the positive efficacy of Au NPs@C. longa on stimulating chondrogenesisin vitro. It was revealed that the Au NPs@C. longa application speeded up the injury-induced dysfunction recovery after 21 days. The Au NPs@C. longa application suppressed the abnormal fibrosis and angiogenesis at the injury site.

Collagen type II solution extracted from supercritical carbon dioxide decellularized porcine cartilage: regenerative efficacy on post-traumatic osteoarthritis model

Osteoarthritis (OA) of the knee is a common degenerative articular disorder and is one of the main causes of pain and functional disability. Cartilage damage is frequently linked to elevated osteoarthritis incidence. Supercritical carbon dioxide (scCO2) decellularized cartilage graft produced from the porcine cartilage is an ideal candidate for cartilage tissue engineering. In the present study, we derived collagen type II (Col II) solution from the scCO2 decellularized porcine cartilage graft (dPCG) and compared its efficacy with hyaluronic acid (HA) in the surgical medial meniscectomy (MNX) induced post-traumatic osteoarthritis (PTOA) model. Dose-dependent attenuation of the OA (12.3 ± 0.8) progression was observed in the intra‐articular administration of Col II solution (7.3 ± 1.2) which significantly decreased the MNX-induced OA symptoms similar to HA. The pain of the OA group (37.4 ± 2.7) was attenuated dose-dependently by Col II solution (45.9 ± 4.1) similar to HA (43.1 ± 3.5) as evaluated by a capacitance meter. Micro‐CT depicted a dose-dependent attenuation of articular cartilage damage by the Col II solution similar to HA treatment. A significant (p < 0.001) dose-dependent elevation in the bone volume was also observed in Col II solution-treated OA animals. The protective competence of Col II solution on articular cartilage damage is due to its significant (p < 0.001) increase in the expression of type II collagen, aggrecan and SOX‐9 similar to HA. To conclude, intra‐articular administration of type II collagen solution and HA reestablished the injured cartilage and decreased osteoarthritis progression in the experimental PTOA model.Graphical

Ligusticum cycloprolactam inhibits IL-1β-induced apoptosis and inflammation of rat chondrocytes via HMGB1/TLR4/NF-κB signaling pathway

Chondrocytes are unique resident cells in the articular cartilage, and the pathological changes of them can lead to the occurrence of osteoarthritis(OA). Ligusticum cycloprolactam(LIGc) are derivatives of Z-ligustilide(LIG), a pharmacodynamic marker of Angelica sinensis, which has various biological functions such as anti-inflammation and inhibition of cell apoptosis. However, its protective effect on chondrocytes in the case of OA and the underlying mechanism remain unclear. This study conducted in vitro experiments to explore the molecular mechanism of LIGc in protecting chondrocytes from OA. The inflammation model of rat OA chondrocyte model was established by using interleukin-1β(IL-1β) to induce. LIGc alone and combined with glycyrrhizic acid(GA), a blocker of the high mobility group box-1 protein(HMGB1)/Toll-like receptor 4(TLR4)/nuclear factor-kappa B(NF-κB) signaling pathway, were used to intervene in the model, and the therapeutic effects were systematically evaluated. The viability of chondrocytes treated with different concentrations of LIGc was measured by the cell counting kit-8(CCK-8), and the optimal LIGc concentration was screened out. Annexin V-FITC/PI apoptosis detection kit was employed to examine the apoptosis of chondrocytes in each group. The enzyme-linked immunosorbent assay(ELISA) was employed to measure the expression of cyclooxygenase-2(COX-2), prostaglandin-2(PGE2), and tumor necrosis factor-alpha(TNF-α) in the supernatant of chondrocytes in each group. Western blot was employed to determine the protein levels of B-cell lymphoma-2(Bcl-2), Bcl-2-associated X protein(Bax), caspase-3, HMGB1, TLR4, and NF-κB p65. The mRNA levels of HMGB1, TLR4, NF-κB p65, and myeloid differentiation factor 88(MyD88) in chondrocytes were determined by real-time fluorescent quantitative PCR(RT-qPCR). The safe concentration range of LIGc on chondrocytes was determined by CCK-8, and then the optimal concentration of LIGc for exerting the effect was clarified. Under the intervention of IL-1β, the rat chondrocyte model of OA was successfully established. The modeled chondrocytes showed increased apoptosis rate, promoted expression of COX-2, PGE2, and TNF-α, up-regulated protein levels of Bax, caspase-3, HMGB1, TLR4, and NF-κB p65 and mRNA levels of HMGB1, TLR4, NF-κB p65, and MyD88, and down-regulated protein level of Bcl-2. However, LIGc reversed the IL-1β-induced changes of the above factors. Moreover, LIGc combined with GA showed more significant reversal effect than LIGc alone. These fin-dings indicate that LIGc extracted and derived from the traditional Chinese medicine A. sinensis can inhibit the inflammatory response of chondrocytes and reduce the apoptosis of chondrocytes, and this effect may be related to the HMGB1/TLR4/NF-κB signaling pathway. The pharmacological effect of LIGc on protecting chondrocytes has potential value in delaying the progression of OA and improving the clinical symptoms of patients, and deserves further study.

Systematic Pharmacology and Experimental Validation to Reveal the Alleviation of Astragalus membranaceus Regulating Ferroptosis in Osteoarthritis.

Astragalus membranaceus (AM) shows promise as a therapeutic agent for osteoarthritis (OA), a debilitating condition with high disability rates. OA exacerbation is linked to chondrocyte ferroptosis, yet the precise pharmacological mechanisms of AM remain unclear. We validated AM's protective efficacy in an anterior cruciate ligament transection (ACLT) mouse model of OA. The Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) database was utilized to identify AM's active components and their targets. FerrDb (a database for regulators and markers of ferroptosis and ferroptosis-disease associations) pinpointed ferroptosis-related targets, while GeneCards, Online Mendelian Inheritance in Man (OMIM), Pharmacogenomics Knowledgebase (PharmGKB), Therapeutic Target Database (TTD), and DrugBank sourced OA-related genes. Molecular docking analysis further validated these targets. Ultimately, the validation of the results was accomplished through in vitro experiments. AM exhibited anabolic effects and suppressed catabolism in OA chondrocytes. Network pharmacology identified 19 common genes, and molecular docking suggested quercetin, an AM constituent, interacts with key proteins like HO-1 and NRF2 to inhibit chondrocyte ferroptosis. In vitro experiments confirmed AM's ability to modulate the NRF2/HO-1 pathway via quercetin, mitigating chondrocyte ferroptosis. This study elucidates how AM regulates chondrocyte ferroptosis, impacting OA progression, providing a theoretical basis and experimental support for AM's scientific application.

Blocking Runx2 Inhibits the Caspase-1 Dependent Pyroptosis in Lipopolysaccharide-Treated Chondrocyte

Pyroptosis is a new type of cell death in the development of osteoarthritis (OA), but the underlying mechanism is not fully understood. This study aimed to investigate the role of Runx2 in the pyroptosis of chondrocyte (CH) and explore its effect on Caspase-1 expression. Human knee tissues from the fracture patients without OA history were collected. Human CHs isolated from the tissue were treated by lipopolysaccharide (LPS) to establish the model of OA. siRNA and CADD522 were used to block the function of Runx2. The cell viability was tested by MTT. The expression levels of Runx2, Caspase1/4/5/11, GSDMD, collagen-II, aggrecan, IL-1β, IL-8, and MMP3/9 were detected by RT-PCR, immunofluorescence, or western blot. Besides, the transcriptional association between Runx2 and Caspase-1 was confirmed by DNA immunoprecipitation and luciferase reporter assay. Runx2 and Caspase-1 expression were increased in LPS-treated CHs. Runx2 bound to the promoter of Caspase-1 and activated its expression. Moreover, silencing Runx2 or disrupting the DNA-binding ability of Runx2 attenuated the LPS-induced pyroptotic phenotype, containing Caspase-1 activation, collagen-II and aggrecan degradation, viability suppression, IL-1β and IL-8 upregulation. Blocking the expression or function of Runx2 alleviated the LPS-caused pyroptosis in CHs in the Caspase-1 manner, indicating a novel understanding of the pathology of OA.

α-Solanine attenuates chondrocyte pyroptosis to improve osteoarthritis via suppressing NF-κB pathway.

α-Solanine has been shown to exhibit anti-inflammatory and anti-tumour properties; however, its efficacy in treating osteoarthritis (OA) remains ambiguous. The study aimed to evaluate the therapeutic effects of α-solanine on OA development in a mouse OA model. The OA mice were subjected to varying concentrations of α-solanine, and various assessments were implemented to assess OA progression. We found that α-solanine significantly reduced osteophyte formation, subchondral sclerosis and OARSI score. And it decreased proteoglycan loss and calcification in articular cartilage. Specifically, α-solanine inhibited extracellular matrix degradation by downregulating collagen 10, matrix metalloproteinase 3 and 13, and upregulating collagen 2. Importantly, α-solanine reversed chondrocyte pyroptosis phenotype in articular cartilage of OA mice by inhibiting the elevated expressions of Caspase-1, Gsdmd and IL-1β, while also mitigating aberrant angiogenesis and sensory innervation in subchondral bone. Mechanistically, α-solanine notably hindered the early stages of OA progression by reducing I-κB phosphorylation and nuclear translocation of p65, thereby inactivating NF-κB signalling. Our findings demonstrate the capability of α-solanine to disrupt chondrocyte pyroptosis and sensory innervation, thereby improving osteoarthritic pathological progress by inhibiting NF-κB signalling. These results suggest that α-solanine could serve as a promising therapeutic agent for OA treatment.

Hsa_circ_0004662 Accelerates the Progression of Osteoarthritis via the microRNA-424-5p/VEGFA Axis.

Circular RNAs (circRNAs) have been extensively implicated in osteoarthritis (OA) progression. Therefore, this study explores the impact of hsa_circ_0004662 on OA progression and the related molecular mechanism. Human articular chondrocyte injury was induced by IL-1β to construct the OA model in vitro. Hsa_circ_0004662 and microRNA (miR)-424-5p expression in chondrocytes was evaluated with qRT-PCR. Vascular endothelial growth factors A (VEGFA) expression was examined with qRT-PCR and western blot after hsa_circ_0004662 knockdown or miR-424-5p overexpression in chondrocytes. Subsequent to loss- and gain-of-function assays in IL-1β-induced chondrocytes, the proliferation and apoptosis of chondrocytes were assessed with CCK-8 assay and flow cytometry, respectively. The expression of MMP13, Aggrecan, and apoptosis-related proteins Bax and Bcl-2 was measured with western blot. The binding of miR-424-5p to hsa_circ_0004662 and VEGFA was assessed with a dual-luciferase reporter gene assay. Hsa_circ_0004662 was up-regulated, but miR-424-5p was down-regulated in IL-1β-induced chondrocytes. Mechanistically, both hsa_circ_0004662 and VEGFA bound to miR-424-5p, and hsa_circ_0004662 enhanced VEGFA expression by downregulating miR-424-5p. Hsa_circ_0004662 knockdown elevated cell proliferation, decreased apoptosis and MMP13 and Bax expression, and increased Aggrecan and Bcl- 2 expression in IL-1β-induced chondrocytes, which was counteracted by further miR- 424-5p down-regulation or VEGFA overexpression. Hsa_circ_0004662 facilitates OA progression via the miR-424-5p/ VEGFA axis.

Protocatechuic aldehyde attenuates chondrocyte senescence via the regulation of PTEN-induced kinase 1/Parkin-mediated mitochondrial autophagy.

This study aimed to investigate whether the beneficial effects of PCA on chondrocyte senescence are mediated through the regulation of mitophagy. Chondrocyte senescence plays a significant role in the development and progression of knee osteoarthritis (OA). The compound protocatechuic aldehyde (PCA), which is abundant in the roots of Salvia miltiorrhiza, has been reported to have antioxidant properties and the ability to protect against cellular senescence. To achieve this goal, a destabilization of the medial meniscus (DMM)-induced mouse OA model and a lipopolysaccharide (LPS)-induced chondrocyte senescence model were used, in combination with PINK1 gene knockdown or overexpression. After treatment with PCA, cellular senescence was assessed using Senescence-Associated β-Galactosidase (SA-β-Gal) staining, DNA damage was evaluated using Hosphorylation of the Ser-139 (γH2AX) staining, reactive oxygen species (ROS) levels were measured using Dichlorodihydrofluorescein diacetate (DCFH-DA) staining, mitochondrial membrane potential was determined using a 5,5',6,6'-TETRACHLORO-1,1',3,3'-*. TETRAETHYBENZIMIDA (JC-1) kit, and mitochondrial autophagy was examined using Mitophagy staining. Western blot analysis was also performed to detect changes in senescence-related proteins, PINK1/Parkin pathway proteins, and mitophagy-related proteins. Our results demonstrated that PCA effectively reduced chondrocyte senescence, increased the mitochondrial membrane potential, facilitated mitochondrial autophagy, and upregulated the PINK1/Parkin pathway. Furthermore, silencing PINK1 weakened the protective effects of PCA, whereas PINK1 overexpression enhanced the effects of PCA on LPS-induced chondrocytes. PCA attenuates chondrocyte senescence by regulating PINK1/Parkin-mediated mitochondrial autophagy, ultimately reducing cartilage degeneration.

Protective and Anti-Inflammatory Effects of Avocado and Soybean Unsaponifiables in Primary Rat Chondrocytes and an MIA-Induced Osteoarthritis Model

Protective and Anti-Inflammatory Effects of Avocado and Soybean Unsaponifiables in Primary Rat Chondrocytes and an MIA-Induced Osteoarthritis Model

Protopine protects chondrocytes from undergoing ferroptosis by activating Nrf2 pathway

Osteoarthritis is a highly prevalent joint disease; however, effective treatments are lacking. Protopine (PTP) is an isoquinoline alkaloid with potent anti-inflammatory and antioxidant properties; however, it has not been studied in osteoarthritis. This study aimed to investigate whether PTP can effectively protect chondrocytes from ferroptosis. Primary mouse chondrocytes were treated with tert-butyl hydroperoxide (TBHP) to simulate oxidative stress in an in vitro model of osteoarthritis. Two concentrations of PTP (10 and 20 μg/mL) were validated for in vitro experiments. Cellular inflammation and metabolism were detected using RT-qPCR and western blotting (WB). Ferroptosis was assessed via WB, qPCR, reactive oxygen species (ROS) levels, lipid ROS, and immunofluorescence staining. In vitro, PTP significantly ameliorated chondrocyte inflammation and cytolytic metabolism and significantly suppressed chondrocyte ferroptosis through the activation of the Nrf2 pathway. The anterior cruciate ligament transection (ACLT) mouse model was used to validate the in vivo effects of PTP. The joint cartilage was assessed using the Osteoarthritis Research Society International (OARSI) score, Safranin O staining, and immunohistochemistry. The intra-articular administration of PTP alleviated cartilage inflammation and ferroptosis, as evidenced by the expression of MMP3, MMP13, COL2A1, GPX4, and Nrf2. Overall, we find that PTP exerted anti-ferroptosis and anti-inflammatory effects on chondrocytes to protect the articular cartilage.

Microbiome dysbiosis by antibiotics protects cartilage degradation in OAOP mice.

The role of this study was to evaluate the impact of gut microbiota depletion on the progression of osteoarthritis (OA) and osteoporosis (OP). We conducted an experimental mouse model of OA and OP over an 8-week period. The model involved destabilization of the medial meniscus and bilateral ovariectomy (OVX). To deplete the gut microbiota, we administered a course of antibiotics for 8 weeks. The severity of OA was assessed through micro-CT scanning, X-rays, and immunohistochemical staining. Microbiome analysis was performed using PCR of 16S DNA on fecal samples, and the levels of serum lipopolysaccharide, interleukin 6, tumor necrosis factor-α (TNF-α), osteocalcin, and estrogen were measured using enzyme-linked immunosorbent assay. We found that in comparison to the OVX+OA group, the OVX+OA+ABT group exhibited increased bone mineral density (P < 0.0001), bone volume fraction (P = 0.0051), and trabecular number (P = 0.0023) in the metaphyseal bone. Additionally, cartilage injury and levels of matrix metalloproteinase 13 were reduced in the OVX+OA+ABT group compared to the OVX+OA group. Moreover, the OVX+OA+ABT group demonstrated decreased relative abundance of Bacteroidetes, serum lipopolysaccharide (P = 0.0005), TNF-α (P < 0.0001), CTX-1 (P = 0.0002), and increased expression of bone formation markers. These findings were further supported by correlation network analyses. Depletion of gut microbiota was shown to protect against bone loss and cartilage degradation by modulating the composition of the gut microbiota in osteoporosis and osteoarthritis.