Chondrocyte Senescence Research Articles

Anti-aging effect of extracellular vesicles from mesenchymal stromal cells on senescence-induced chondrocytes in osteoarthritis.

Age is the most important risk factor for degenerative diseases such as osteoarthritis (OA). It is associated with the accumulation of senescent cells in joint tissues that contribute to the pathogenesis of OA, in particular through the release of senescence-associated secretory phenotype (SASP) factors. Mesenchymal stromal cells (MSCs) and their derived extracellular vesicles (EVs) are promising treatments for OA. However, the senoprotective effects of MSC-derived EVs in OA have been poorly investigated. Here, we used EVs from human adipose tissue-derived MSCs (ASC-EVs) in two models of inflammaging (IL1β)- and DNA damage (etoposide)-induced senescence in OA chondrocytes. We showed that the addition of ASC-EVs was effective in reducing senescence parameters, including the number of SA-β-Gal-positive cells, the accumulation of γH2AX foci in nuclei and the secretion of SASP factors. In addition, ASC-EVs demonstrated therapeutic efficacy when injected into a murine model of OA. Several markers of senescence, inflammation and oxidative stress were decreased shortly after injection likely explaining the therapeutic efficacy. In conclusion, ASC-EVs exert a senoprotective function both in vitro, in two models of induced senescence in OA chondrocytes and, in vivo, in the murine model of collagenase-induced OA.

The Annexin A1 Protein Mimetic Peptide Ac2-26 prevents cellular senescence of CHON-001 chondrocytes against tumor necrosis factor-α via the Nrf2/NF-κB pathway.

Osteoarthritis (OA) is a degenerative joint disorder characterized by progressive cartilage degradation. Excessive oxidative stress (OS), inflammatory responses, extracellular matrix breakdown, and cellular senescence of chondrocytes play crucial roles in the pathological development of OA. Currently, curing OA remains a significant challenge. In this study, we aimed to elucidate the protective effects of Annexin A1 protein Mimetic Peptide (Ac2-26) against tumor necrosis factor-α (TNF-α)-induced damage in CHON-001 chondrocytes by assessing cellular senescence, OS, and the expression levels of matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4. Our results show that Ac2-26 mitigated the reduction of telomerase activity and the exacerbation of cellular senescence induced by TNF-α in CHON-001 chondrocytes. Treatment with TNF-α led to decreased expression of the human telomerase reverse transcriptase gene and increased expression of the telomeric repeat-binding factor 2 gene, which were reversed by Ac2-26 treatment. The TNF-α-induced increases in the gene and protein expressions of p53 and p16 were restored by Ac2-26 in a dose-dependent manner. Additionally, we found that TNF-α caused elevations in the mRNA and protein levels of MMP-13 and ADAMTS-4, which were reduced by Ac2-26 in a dose-dependent fashion. Furthermore, TNF-α triggered the activation of nuclear factor κ-B (NF-κB) by increasing the levels of phosphorylated NF-κB p65 and the luciferase activity of NF-κB. Notably, Ac2-26 alleviated OS by reducing mitochondrial reactive oxygen species levels and promoting the activation of NF-E2-related factor 2 (Nrf2) in TNF-α-challenged CHON-001 chondrocytes. Silencing Nrf2 abolished the Ac2-26-induced activation of NF-κB and cellular senescence in CHON-001 chondrocytes. Collectively, these findings offer new insights into the potential therapeutic use of Ac2-26 for treating OA.

β-Hydroxybutyrate enhances chondrocyte mitophagy and reduces cartilage degeneration in osteoarthritis via the HCAR2/AMPK/PINK1/Parkin pathway.

Osteoarthritis (OA) is widely recognized as the prevailing joint disease associated with aging. The ketogenic diet (KD) has been postulated to impede the advancement of various inflammatory ailments. β-Hydroxybutyrate (βOHB), a prominent constituent of ketone bodies, has recently been proposed to possess crucial signaling capabilities. In this study, we propose to explore the role and mechanism of βOHB in OA. Tissue staining and inflammatory factor assay were employed to evaluate the impacts of KD and βOHB on OA rats. The oxidative stress conditions in chondrocytes were induced using tert-butyl hydroperoxide (TBHP). The mechanisms were determined using the siRNA of hydroxycarboxylic acid receptor 2 (HCAR2), the antagonist of adenosine monophosphate-activated protein kinase (AMPK), and the inhibitor of mitophagy. The administration of KD demonstrated a reduction in pathological damage to cartilage, as well as a decrease in plasma levels of inflammatory factors. Furthermore, it resulted in an increase in the concentration of βOHB in the blood and synovial fluid. Invitro experiments showed that βOHB facilitated mitophagy and adenosine triphosphate production. Besides, βOHB mitigated chondrocyte senescence, inflammatory factors secretion, extracellular matrix degradation, and apoptosis induced by TBHP. Subsequent investigations indicated that the protective effects of βOHB were no longer observed following the knockdown of HCAR2, the antagonist of AMPK, or the inhibitor of mitophagy. Moreover, invivo studies suggested that βOHB played a protective role by targeting the HCAR2-AMPK-PINK1 axis. In conclusion,βOHB enhanced chondrocyte mitophagy through the HCAR2/AMPK/PINK1/Parkin pathway, offering a potential therapeutic approach for the treatment of OA.

Targeting FAP-positive chondrocytes in osteoarthritis: a novel lipid nanoparticle siRNA approach to mitigate cartilage degeneration

BackgroundOsteoarthritis (OA) is a common joint disease that leads to chronic pain and functional limitations. Recent research has revealed soluble fibroblast activation protein (FAP) secreted from OA synovium could degrade type II collagen (Col2) in cartilage to promote the progression of OA. This study aimed to reveal the role of FAP from chondrocytes in OA and develop a novel lipid nanoparticle (LNP)-FAP siRNA delivery system for OA treatment.MethodsThe expression of FAP in the cartilage of knee OA patients was investigated using [68 Ga]Ga-FAPI-04 PET in vivo and immunofluorescence, western blotting, and RT-qPCR in vitro. Cell senescence was determined by senescence-associated β-galactosidase (SA-β-Gal) assay after FAP overexpressing or knockdown in chondrocytes. An OA model with chondrocyte-specific FAP knockout mice was applied to investigate the role of FAP in chondrocyte senescence and OA development. The therapeutic effects of lipid nanoparticle (LNP) @FAP siRNA on cartilage degeneration were evaluated in the rat OA model.ResultsOur study found that higher [68 Ga]Ga-FAPI-04 uptake was detected in knee OA patients by PET/CT scan. FAP mRNA and protein levels were highly expressed in OA-damaged cartilage. Moreover, we found that overexpression of FAP promotes chondrocyte senescence, and the genetic knockout of FAP in chondrocytes alleviates OA. Knockdown FAP by siRNA could alleviate chondrocyte senescence and suppress the NF-κB pathway to reduce the senescence-associated secretory phenotype (SASP). In the rat model of OA, intraarticular injection of LNP@FAP siRNA can reduce senescent cells and ameliorate cartilage destruction.ConclusionFAP-positive chondrocytes play a significant role in the pathogenesis of OA. Targeting these cells selectively has the potential to mitigate the progression of the disease. Our study provides valuable insights into the intraarticular injection of LNP@FAP siRNA as a promising strategy for the treatment of OA.Graphical abstract

Chondrocyte autophagy mechanism and therapeutic prospects in osteoarthritis.

Osteoarthritis (OA) is the most common type of arthritis characterized by progressive cartilage degradation, with its pathogenesis closely related to chondrocyte autophagy. Chondrocytes are the only cells in articular cartilage, and the function of chondrocytes plays a vital role in maintaining articular cartilage homeostasis. Autophagy, an intracellular degradation system that regulates energy metabolism in cells, plays an incredibly important role in OA. During the early stages of OA, autophagy is enhanced in chondrocytes, acting as an adaptive mechanism to protect them from various environmental changes. However, with the progress of OA, chondrocyte autophagy gradually decreases, leading to the accumulation of damaged organelles and macromolecules within the cell, prompting chondrocyte apoptosis. Numerous studies have shown that cartilage degradation is influenced by the senescence and apoptosis of chondrocytes, which are associated with reduced autophagy. The relationship between autophagy, senescence, and apoptosis is complex. While autophagy is generally believed to inhibit cellular senescence and apoptosis to promote cell survival, recent studies have shown that some proteins are degraded by selective autophagy, leading to the secretion of the senescence-associated secretory phenotype (SASP) or increased SA-β-Gal activity in senescent cells within the damaged region of human OA cartilage. Autophagy activation may lead to different outcomes depending on the timing, duration, or type of its activation. Thus, our study explored the complex relationship between chondrocyte autophagy and OA, as well as the related regulatory molecules and signaling pathways, providing new insights for the future development of safe and effective drugs targeting chondrocyte autophagy to improve OA.

Molybdenum nanodots act as antioxidants for photothermal therapy osteoarthritis

Osteoarthritis (OA) manifests as the degradation of cartilage and remodeling of subchondral bone. Restoring homeostasis within the joint is imperative for alleviating OA symptoms. Current interventions primarily target singular aspects, such as anti-aging, inflammation inhibition, free radical scavenging, and regeneration of cartilage and subchondral bone. Herein, we developed molybdenum nanodots (MNDs) as bionic photothermal nanomaterials to mimic the antioxidant synthase to concurrently protected cartilage and facilitate subchondral bone regeneration. With near-infrared (NIR) irradiation, MNDs effectively eliminate reactive oxygen and nitrogen species (ROS/RNS) from OA chondrocytes, thereby reversed mitochondrial dysfunction, mitigating chondrocyte senescence, and simultaneously suppresses inflammation, hence preserving the inherent homeostasis between cartilage matrix synthesis and degradation while circumventing safety concerns. RNA sequencing of OA chondrocytes treated with MNDs-NIR revealed the reinstatement of chondrocyte functionality, activation of antioxidant enzymes, anti-aging properties, and regulation of inflammation. NIR irradiation induces thermogenesis and synergistically promotes subchondral bone regeneration via MNDs, as validated through histological assessments and microcomputed tomography (Micro-CT) scans. MNDs-NIR effectively attenuate cellular senescence and inhibit inflammation in vivo, while also remodeling mitochondrial dynamics by upregulating fusion proteins and inhibiting fission proteins, thereby regulating the oxidative stress microenvironment. Additionally, MNDs-NIR exhibited remarkable therapeutic effects in alleviating articular cartilage degeneration in an OA mouse model, evidenced by a 1.67-fold reduction in subchondral bone plate thickness, an 88.57 % decrease in OARSI score, a 5.52-fold reduction in MMP13 expression, and a 6.80-fold increase in Col II expression. This novel disease-modifying approach for OA utilizing MNDs-NIR offers insight and a paradigm for improving mitochondrial dysfunction by regulating the accumulation of mitochondrial ROS and ultimately alleviating cellular senescence. Moreover, the dual-pronged therapeutic approach of MNDs-NIR, which addresses both cartilage erosion and subchondral bone lesions in OA, represents a highly promising strategy for managing OA.

Insufficient Mechanical Loading Downregulates Piezo1 in Chondrocytes and Impairs Fracture Healing Through ApoE-Induced Senescence.

Insufficient mechanical loading impairs fracture healing; however, the underlying mechanisms remain unclear. Increasing evidence indicates that Piezo1 plays an important role in fracture healing, although the effect of Piezo1 on the endochondral ossification of chondrocytes has been overlooked. This study reports that mechanical unloading down-regulates the expression of Piezo1 in chondrocytes and leads to fracture nonunion. Single-cell sequencing of calluses revealed that specific deletion of Piezo1 in chondrocytes upregulated the expression of apolipoprotein E (ApoE) in hypertrophic chondrocytes, resulting in delayed cartilage-to-bone transition due to enhanced chondrocyte senescence. Based on these results, an injectable and thermosensitive hydrogel is developed, which released an ApoE antagonist in situ at the fracture site. This hydrogel effectively attenuated chondrocyte senescence and, thus, promoted cartilage-to-bone transition as well as the fracture healing process. Overall, this data provide a new perspective on the activity of chondrocytes in fracture healing and a new direction for the treatment of fracture nonunion caused by insufficient mechanical loading.

Jianpi qingre tongluo prescription alleviates the senescence-associated secretory phenotype with osteoarthritis by regulating STAG1/TP53/P21 signaling pathway

Ethnopharmacological relevanceJianpi Qingre Chubi prescription primarily consists of a compound formula, also known as Huangqin Qingre Chubi Capsules (HQC), which strengthens the spleen and resolves dampness, clear heat, and collaterals. Long-term clinical use has shown that HQC improves joint swelling and pain in patients with osteoarthritis. Mechanistically, we demonstrated that HQC inhibits inflammatory responses, extracellular matrix degradation, and delays chondrocyte senescence. AimTo determine the bioactivity and mechanism of action of Jianpi Qingre Tongluo prescription (HQC) on osteoarthritis (OA). Materials and methodsFirst, the chondroprotective effects of HQC were assessed using histopathology, immunohistochemical staining and protein blotting in an OA rat model. Additionally, we identified key targets for crucial targets of HQC in OA using the Network Pharmacology and Gene Expression Omnibus (GEO) dataset (GSE98918 and GSE152805). In vitro conditions, IL-1β-treated chondrocytes served to study the impact of HQC on OA development and the senescence-associated secretory phenotype (SASP). This was evaluated using a series of approaches, such as flow cytometry assays, and immunofluorescence staining, and then verified by rescue experiments. ResultsTherapy with HQC attenuated the severity of osteoarthritis (demonstrated by histopathology, OARSI grading scores, and Mankin scores) and SASP factors (as indicated by IL-1β, IL-6, IL-4, IL-37, MMP13, ADAMTS5, COL2A1, and ACAN levels, and apoptotic cell death). HQC might treat osteoarthritis via four important targets (STAG1, TP53, P21, and P16), with the p53 signalling pathway representing one of the main pathways. The HQC acts primarily on chondrocyte clusters. In vitro experiments indicated that STAG1 overexpression accelerates chondrocyte apoptosis, promotes SASP factor expression and extracellular matrix (ECM) degradation, and facilitates OA progression. HQC-containing serum suppressed the expression of the STAG1/TP53/P21 pathway, regulated SASP factors, and restored ECM balance. ConclusionJianpi Qingre Tongluo prescription modulated SASP factors by regulating the STAG1/TP53/P21 signal transduction axis and decelerating cartilage senescence and degradation in patients with OA. Jianpi Qingre Tongluo may be an effective drug candidate.

Gene therapy for fat-1 prevents obesity-induced metabolic dysfunction, cellular senescence, and osteoarthritis

Obesity is one of the primary risk factors for osteoarthritis (OA), acting through cross talk among altered biomechanics, metabolism, adipokines, and dietary free fatty acid (FA) composition. Obesity and aging have been linked to cellular senescence in various tissues, resulting in increased local and systemic inflammation and immune dysfunction. We hypothesized that obesity and joint injury lead to cellular senescence that is typically associated with increased OA severity or with aging and that the ratio of omega-6 (ω-6) to omega-3 (ω-3) FAs regulates these pathologic effects. Mice were placed on an ω-6-rich high-fat diet or a lean control diet and underwent destabilization of the medial meniscus to induce OA. Obesity and joint injury significantly increased cellular senescence in subcutaneous and visceral fat as well as joint tissues such as synovium and cartilage. Using adeno-associated virus (AAV) gene therapy for fat-1, a fatty acid desaturase that converts ω-6 to ω-3 FAs, decreasing the serum ω-6:ω-3 FA ratio had a strong senomorphic and therapeutic effect, mitigating metabolic dysfunction, cellular senescence, and joint degeneration. In vitro coculture of bone marrow-derived macrophages and chondrocytes from control and AAV8-fat1-treated mice were used to examine the roles of various FA mediators in regulating chondrocyte senescence. Our results suggest that obesity and joint injury result in a premature "aging" of the joint as measured by senescence markers, and these changes can be ameliorated by altering FA composition using fat-1 gene therapy. These findings support the potential for fat-1 gene therapy to treat obesity- and/or injury-induced OA clinically.

Epidemiology and pathogenesis of osteoarthritis

Background: Osteoarthritis (OA) is the most common form of arthritis and poses a considerable socioeconomic burden, contributing to disability and decreased quality of life, particularly in older adults. However, the current treatment for OA is limited to pain relief, and it is necessary to develop disease-modifying OA drugs that target specific molecular mechanisms of its pathogenesis.Current Concepts: The prevalence of OA increases with age, with the incidence being higher in individuals aged over 60 years. Furthermore, women are more likely to develop knee and hand OA, whereas hip OA is more common in men. The global burden of OA is increasing, driven by an aging population and increasing obesity. The main pathological feature of OA is the degradation of the cartilage extracellular matrix by catabolic proteases such as matrix metalloproteinase 13 (MMP13) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (Adamts5), which are regulated by various signaling pathways and transcription factors. The metabolic shift towards glycolysis, which is associated with mitochondrial dysfunction, increases oxidative stress, ultimately leading to chondrocyte senescence and apoptosis. Chondrocytes in the superficial zone have stem cell-like properties and secrete anabolic proteins such as lubricin and fibulin-3. Subchondral bone remodeling and chondrocyte senescence have emerged as critical mechanisms of OA progression.Discussion and Conclusion: The understanding of OA has markedly evolved in recent years, shifting from the traditional view of OA as a “wear and tear” disease to a multifaceted condition with a complex pathogenesis. This paradigm shift could contribute to the development of novel strategies to halt OA progression.

Forsythoside A mitigates osteoarthritis and inhibits chondrocyte senescence by promoting mitophagy and suppressing NLRP3 inflammasome via the Nrf2 pathway

BackgroundChondrocyte senescence and inflammation are hallmarks of osteoarthritis (OA). Forsythiaside A (FTA), a phenylethanol glycoside isolated from air-dried fruits of Forsythia, has been reported to have significant anti-inflammatory and antioxidant properties. However, its protective effects against OA have not been elucidated. PurposeWe explored the therapeutic efficacy of FTA in inhibiting chondrocyte senescence and inflammation during OA, as well as the potential underlying mechanisms. Study designThis study aimed to investigate the novel mechanism of FTA in alleviating OA in both cell and animal models. MethodsThe protective effect of FTA against tert-butyl hydroperoxide-induced chondrocyte damage was assessed, and the effects of FTA on cartilage aging and OA progression were evaluated using a medial meniscus (DMM)-induced knee OA mouse model. The regulatory effects of FTA on the NLRP3 Inflammasome, mitophagy, and the PKC/Nrf2 pathway were also explored. ResultsIn vitro, FTA improved mitochondrial function, enhanced mitophagy, suppressed NLRP3 inflammasome activation, and inhibited chondrocyte senescence; however, these chondroprotective effects were partially reversed after mitophagy inhibition, NLRP3 inflammasome activation, and Nrf2 pathway inhibition. Furthermore, we found that FTA directly interacts with Nrf2 and enhances its phosphorylation by protein kinase C (PKC). In vivo, FTA attenuated the pathological signs of knee OA in a DMM-model mouse model, which was partially reversed by ML385. ConclusionFTA inhibited chondrocyte senescence and OA progression by activating the PKC–Nrf2 pathway. Thus, FTA is a potential novel therapeutic agent for OA.

LTF ameliorates cartilage endplate degeneration by suppressing calcification, senescence and matrix degradation through the JAK2/STAT3 pathway.

Intervertebral disc degeneration (IDD)-induced cervical and lumbar herniations are debilitating diseases. The function of intervertebral disc (IVD) mainly depends on the cartilage endplate (CEP), which provides support and waste removal. Therefore, IDD stems from the degeneration of CEP. Our study shows that the expression of lactotransferrin (LTF), an iron-binding protein, is significantly decreased in degenerated human and rat CEP tissues. In addition, we found that LTF knockdown promoted calcification, senescence, and extracellular matrix (ECM) degradation in human endplate chondrocytes. Furthermore, the invivo experiment results confirmed that the JAK2/STAT3 pathway inhibitor AG490 significantly reversed these effects. In addition to investigating the role and mechanism of LTF in CEP degeneration, this study provides a theoretical basis and experimental evidence to improve IDD treatment.

Panaxatriol exerts anti-senescence effects and alleviates osteoarthritis and cartilage repair fibrosis by targeting UFL1

IntroductionOsteoarthritis (OA), the most common degenerative joint disease, can eventually lead to disability. However, no safe or effective intervention is currently available. Therefore, there is an urgent need to develop effective drugs that reduce cartilage damage and treat OA. ObjectivesThis study aimed to ascertain the potential of panaxatriol, a natural small molecule, as a therapeutic drug for alleviating the progression of OA. MethodsAn in vitro culture of human cartilage explants and C28/I2 human chondrocytes and an in vivo surgically induced OA mouse model were used to evaluate the chondroprotective effect of panaxatriol. The Drug Affinity Responsive Target Stability assay, CRISPR-Cas9 assay, Whole-transcriptome RNA sequencing analysis and agonist or antagonist assays were used to identify the target and potential signaling pathways of panaxatriol. Poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG) was used to construct the sustained-release system of panaxatriol. ResultsPanaxatriol protected against OA by regulating chondrocyte metabolism. Ubiquitin-fold modifier 1-specific E3 ligase 1 (UFL1) was identified as a novel target of panaxatriol. Whole transcriptome RNA sequencing showed that UFL1 was closely related to cell senescence. Panaxatriol inhibited chondrocyte senescence through UFL1/forkhead box O1 (FOXO1)/P21 and UFL1/NF-κB/SASPs signaling pathways. It also could inhibit fibrocartilage formation during cartilage repair via the UFL1/FOXO1/Collagen 1 signaling pathway. Finally, we constructed a sustained-release system for panaxatriol based on PLGA-PEG, which reduced the number of intra-articular injections, thereby alleviating joint swelling and injury. ConclusionsPanaxatriol exerts anti-senescence effects and has the potential to delay OA progression and reduce cartilage repair fibrosis by targeting UFL1.

ESC-sEVs alleviate non-early-stage osteoarthritis progression by rejuvenating senescent chondrocytes via FOXO1A-autophagy axis but not inducing apoptosis

Osteoarthritis (OA) is a common joint degenerative disease which currently lacks satisfactory disease-modifying treatments. Oxidative stress-mediated senescent chondrocytes accumulation is closely associated with OA progression, which abrogates cartilage metabolism homeostasis by secreting senescence-associated secretory phenotype (SASP) factors. Numerous studies suggested mesenchymal stem cells-derived small extracellular vesicles (MSC-sEVs) have been regarded as promising candidates for OA therapy. However, MSC-sEVs were applied before the occurrence of cartilage degeneration or at early-stage OA, while in clinical practice, most OA patients who present with pain are already in non-early-stage. Recently, embryonic stem cells-derived sEVs (ESC-sEVs) have been reported to possess powerful anti-aging effects. However, whether ESC-sEVs could attenuate non-early-stage OA progression remains unknown. In this study, we demonstrated ESC-sEVs ameliorated senescent phenotype and cartilage destruction in both mechanical stress-induced non-early-stage posttraumatic OA and naturally aged mice. More importantly, we found ESC-sEVs alleviated senescent phenotype by rejuvenating aged chondrocytes but not inducing apoptosis. We also provided evidence that the FOXO1A-autophagy axis played an important role in the anti-aging effects of ESC-sEVs. To promote clinical translation, we confirmed ESC-sEVs reversed senescent phenotype in ex-vivo cultured human end-stage OA cartilage explants. Collectively, our findings reveal that ESC-sEVs-based therapy is of high translational value in non-early-stage OA treatment.

Blockade of endothelin receptors mitigates SARS-CoV-2-induced osteoarthritis.

Joint pain and osteoarthritis can occur as coronavirus disease 2019 (COVID-19) sequelae after infection. However, little is known about the damage to articular cartilage. Here we illustrate knee joint damage after wild-type, Delta and Omicron variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in vivo. Rapid joint injury with cystic lesions at the osteochondral junction was observed in two patients with post-COVID osteoarthritis and recapitulated in a golden Syrian hamster model. SARS-CoV-2-activated endothelin-1 signalling increased vascular permeability and caused viral spike proteins leakage into the subchondral bone. Osteoclast activation, chondrocyte dropout and cyst formation were confirmed histologically. The US Food and Drug Administration-approved endothelin receptor antagonist, macitentan, mitigated cystic lesions and preserved chondrocyte number in the acute phase of viral infection in hamsters. Delayed macitentan treatment at post-acute infection phase alleviated chondrocyte senescence and restored subchondral bone loss. It is worth noting that it could also attenuate viral spike-induced joint pain. Our work suggests endothelin receptor blockade as a novel therapeutic strategy for post-COVID arthritis.

Nanoparticle-delivered quercetin exhibits enhanced efficacy in eliminating iron-overloaded senescent chondrocytes.

Aim: The therapeutic potential of senolytic drugs in osteoarthritis (OA) is poorly known. Quercetin, a senolytic agent exhibits promising potential to treat OA, having limited bioavailability. We investigated the effects of Quercetin-loaded nanoparticles (Q-NP) with enhanced bioavailability in human chondrocytes mimicking OA phenotype.Materials & methods: The C-20/A4 chondrocytes were exposed to ferric ammonium citrate to induce OA phenotype, followed by treatment with free Quercetin/Q-NP for 24 and 48-h. Q-NP were synthesized by nanoprecipitation method. Following treatment chondrocytes were assessed for drug cellular bioavailability, viability, cell cycle, apoptosis, oxidative stress and expression of key senescence markers.Results: Q-NP exhibited 120.1±1.2nm particle size, 81±2.4% encapsulation efficiency, increased cellular bioavailability and selective apoptosis of senescent chondrocytes compared with free Quercetin. Q-NP treatment also induced oxidative stress and reduced the expressions of senescence markers, including TRB3, p16, p62 and p21 suggesting their ability to eliminate senescent cells. Last, Q-NP arrested the cell cycle in the sub-G0 phase, potentially creating a beneficial environment for tissue repair.Conclusion: Q-NP propose a promising delivery system for treating OA by eliminating senescent chondrocytes through apoptosis. Furthermore, their enhanced cellular bioavailability and capacity to modify cell cycle and senescent pathways warrant further investigations.

Senolytics Cocktail Dasatinib and Quercetin alleviate chondrocyte senescence and facet joint osteoarthritis in mice

Background contextLow back pain (LBP) is a pervasive issue, causing substantial economic burden and physical distress worldwide. Facet joint osteoarthritis (FJ OA) is believed to be a significant contributor to this problem. However, the precise role of chondrocyte senescence in FJ OA remains unclear, as does whether the clearance of chondrocyte senescence can alleviate the progression of FJ OA. PurposeThe goal of this study was to understand the potential of Dasatinib (D) and Quercetin (Q) as a treatment to clear chondrocyte senescence during the progression of FJ OA. Study designWe used a preclinical bipedal standing mice model with the administration of Dasatinib (D) (5 mg/kg) and Quercetin (Q) (50 mg/kg) after 10 weeks of bipedal standing. Materials and methodsHuman degenerative lumbar facet joint (LFJ) samples were obtained to investigate the relationship between chondrocyte cellular senescence and LFJ osteoarthritis (OA). Subsequently, we established an in vitro model of excessive mechanical stress on chondrocytes and an in vivo bipedal standing mice model to induce LFJ OA. IHC (immunohistochemistry) staining in vivo and SA-β-gal staining, qRT-PCR and Western blot analysis were applied to test the senolytic effect of the combination of Dasatinib (D) and Quercetin (Q). IHC staining and X-ray microscope were also performed to examine the contribution of D+Q to the anabolism in cartilage and subchondral bone recoupling. Immunofluorescence and Western blot analysis in vitro and IHC staining in vivo were conducted to assess the impact of D+Q on the regulation of the NF-κB pathway activation during chondrocyte senescence. ResultsWe observed that facet joint cartilage degeneration is associated with chondrocyte cellular senescence in both human and mouse degenerative samples. Following treatment with D+Q in vitro, cellular senescence was significantly reduced. Upon oral gavage administration of D+Q in the bipedal standing mice model, decreased cellular senescence and reversed chondrocyte anabolism were observed. Furthermore, administration of D+Q maintained subchondral bone remodeling homeostasis and potentially reversed the activation of the NF-κB pathway in chondrocytes of the lumbar facet joint. ConclusionsIn summary, our investigation unveiled a significant correlation between chondrocyte senescence and LFJOA. Treatment with the senolytic combination of D+Q in FJ OA yielded a notable reduction in chondrocyte senescence, along with a decrease in the release of SASP factors. Additionally, it facilitated the promotion of cartilage anabolism, maintenance of subchondral bone coupling, and amelioration of NF-κB pathway activation. Clinical significanceOur outcomes revealed that D+Q, the renowned combination used for senolytic treatment, alleviate the progression of LFJ OA. The utilization of D+Q as a senolytic demonstrates a novel and promising alternative for LFJ OA treatment.

Kongensin A targeting PI3K attenuates inflammation-induced osteoarthritis by modulating macrophage polarization and alleviating inflammatory signaling

The inflammatory microenvironment, polarization of macrophages towards the M1 phenotype, and consequent matrix degradation and senescence of chondrocytes are primary contributors to the degeneration of knee joint cartilage, further exacerbating the progression of osteoarthritis (OA). Kongensin A (KA) is a recently identified natural plant extract exhibiting anti-necrotic apoptosis and anti-inflammatory properties, but the potential efficacy in alleviating OA remains uncertain. The current research lucubrated the effect of KA on the inflammatory microenvironment and macrophage polarization, as well as its regulatory function in extracellular matrix (ECM) metabolism and chondrocyte senescence. Our findings demonstrated that KA can suppress inflammatory signaling, maintain homeostasis between ECM anabolism and catabolism, and suppress chondrocytes senescence. Further investigation elucidated that the mechanism involves the suppression of the PI3K/AKT/NF-κB axis in chondrocytes under inflammatory conditions. Moreover, KA impeded M1 polarization of macrophages via inhibiting PI3K/AKT/NF-κB axis. Subsequently, we treated chondrocytes with macrophages-derived conditioned medium (CM) and revealed that KA can promote ECM anabolism and alleviate chondrocytes senescence by reprogramming macrophage polarization. Consistent with in vitro experiments, in vivo administration of KA demonstrated alleviated cartilage degeneration and delayed progression of OA. Collectively, through obstructing the PI3K/AKT/NF-κB axis, KA can reprogram macrophage polarization, promote matrix metabolism equilibrium, and alleviate chondrocytes senescence, thereby attenuating the pathology of OA. In conclusion, KA may emerge as a promising therapy for OA.

Memantine attenuates the development of osteoarthritis by blocking NMDA receptor mediated calcium overload and chondrocyte senescence

BackgroundMemantine, which is an FDA-proven drug for the treatment of dementia, exerts its function by blocking the function of NMDA (N-methyl-D-aspartate) receptor, a calcium-permeable ion channel that reduces cytotoxic calcium overload. Chondrocyte senescence is a crucial cellular event that contributes to articular cartilage degeneration during osteoarthritis (OA) development. To date, the effects of memantine and its downstream NMDA receptor on chondrocyte senescence and OA have been rarely reported. MethodsThe protein levels of NMDA receptor and its agonistic ligand, glutamate, were compared between normal and OA chondrocytes. The quantity of intracellular calcium ions and the level of mitochondrial damage were evaluated using specific fluorescent probes and transmission electron microscopy (TEM), respectively. Chondrocyte senescence was evaluated by senescence-associated β-galactosidase (SA-β-Gal) staining and p16INK4a analysis. The function of NMDA receptor in chondrocyte senescence and OA was tested via agonists activation and gene knockdown experiments. The therapeutic effects of memantine on OA were examined both in vitro and in vivo. Additionally, to verify the findings from animal samples, a propensity score-matched cohort study was conducted using data from a United Kingdom primary care database (i.e., IQVIA Medical Research Database [IMRD]) to compare the risk of OA-related joint replacement involved in memantine initiators versus active comparators (i.e., acetylcholinesterase [AchE] initiators) in patients with dementia. ResultsThe protein expression of NMDA receptor and the secretion of glutamate were both significantly increased in OA chondrocytes. NMDA receptor activation was found to stimulate chondrocyte calcium overload, which further led to mitochondrial fragmentation and chondrocyte senescence. Blocking the NMDA receptor with memantine and N-methyl-D-aspartate receptor subunit 1(NR1, the gene encoding NMDA receptor) knockdown resulted in reduced calcium influx, mitochondrial fragmentation, as well as cellular senescence in OA chondrocytes. Intra-articular injection of memantine in OA mice also exhibited protective effects against cartilage degeneration. Moreover, in the 1:5 propensity score-matched cohort study consisting of 6218 patients (n = 1435 in the memantine cohort; n = 4783 in the AchE cohort), the memantine initiator was associated with a lower risk of OA-related joint replacement than AchE initiators (Hazard ratio = 0.56, 95 % confidence interval: 0.34 to 0.99). ConclusionNMDA receptor plays an important role in inflammatory-induced cytotoxic calcium overload in chondrocytes, while memantine can effectively block the NMDA receptor to reduce chondrocyte senescence and retard the development of OA. The translational potential of this articleAs a clinically licensed drug used for the treatment of dementia, memantine has shown promising therapeutic effects on OA. Mechanistically, it functions by blocking NMDA receptor from mediating chondrocyte senescence. The protective effects of memantine against OA were verified not only by in vivo and in vitro experiments but also via a propensity score-matched human cohort study. These findings presented robust evidence for repurposing memantine for the treatment of OA.

TDP-43 ameliorates aging-related cartilage degradation through preventing chondrocyte senescence

Senescent chondrocytes or signaling mechanisms leading to senescence are promising new therapeutic approaches for ameliorating cartilage degradation. Herein, we show that the transactive response DNA/RNA-binding protein (TDP-43) regulates chondrocyte senescence and ameliorates cartilage degradation. First, a significant decrease in TDP-43 was observed in 16-month-old mice compared with younger mice. Immunohistochemistry (IHC) analysis of mouse articular cartilage showed that p21, p16, p53, and matrix metalloprotein-13 (MMP13) were increased, but laminB1 and Collagen type II alpha1 1 chain (Col2a1) were decreased in 16-month-old mice. Furthermore, TDP-43 levels were decreased in vivo following D-galactose (D-gal) induction. Therefore, we investigated the role of TDP-43 in the senescent chondrocytes. ATDC5 cells were induced to overexpress TDP-43. Western blot analysis showed increased expression of laminB1, Ki67, and PCNA but decreased expression of p21, p16, p53, and MMP13. Senescence-associated-β-galactosidase (SA-β-Gal) assay, γH2AX staining, and EdU were performed to assess changes in chondrocytes, showing weaker SA-β-Gal and γH2AX staining but stronger EdU and Alican Blue staining. However, TDP-43 deficiency had opposing effects, and similar to D-gal stimulation results. Taken together, our data verified that TDP-43 negatively correlated with senescence markers, positively correlated with cell proliferation markers, and could alleviate cartilage degradation induced by D-gal. This may be an essential mechanism of cellular senescence and cartilage degradation.