Osteoarthritis year in review 2021: biology

Mitochondrial quality control dysfunction in osteoarthritis: Mechanisms, therapeutic strategies & future prospects

Osteoarthritis (OA) is a prevalent chronic joint disease characterized by articular cartilage degeneration, pain, and disability. Emerging evidence indicates that mitochondrial quality control dysfunction contributes to OA pathogenesis. Mitochondria are essential organelles to generate cellular energy via oxidative phosphorylation and regulate vital processes. Impaired mitochondria can negatively impact cellular metabolism and result in the generation of harmful reactive oxygen species (ROS). Dysfunction in mitochondrial quality control mechanisms has been increasingly linked to OA onset and progression. This review summarizes current knowledge on the role of mitochondrial quality control disruption in OA, highlighting disturbed mitochondrial dynamics, impaired mitochondrial biogenesis, antioxidant defenses and mitophagy. The review also discusses potential therapeutic strategies targeting mitochondrial Quality Control in OA, offering future perspectives on advancing OA therapeutic strategies.

Intra-articular sustained-release of pirfenidone as a disease-modifying treatment for early osteoarthritis

Osteoarthritis (OA) is a major clinical challenge, and effective disease-modifying drugs for OA are still lacking due to the complicated pathology and scattered treatment targets. Effective early treatments are urgently needed to prevent OA progression. The excessive amount of transforming growth factor β (TGFβ) is one of the major causes of synovial fibrosis and subchondral bone sclerosis, and such pathogenic changes in early OA precede cartilage damage. Herein we report a novel strategy of intra-articular sustained-release of pirfenidone (PFD), a clinically-approved TGFβ inhibitor, to achieve disease-modifying effects on early OA joints. We found that PFD effectively restored the mineralization in the presence of excessive amount of TGFβ1 (as those levels found in patients' synovial fluid). A monthly injection strategy was then designed of using poly lactic-co-glycolic acid (PLGA) microparticles and hyaluronic acid (HA) solution to enable a sustained release of PFD (the "PLGA-PFD + HA" strategy). This strategy effectively regulated OA progression in destabilization of the medial meniscus (DMM)- induced OA mice model, including preventing subchondral bone loss in early OA and subchondral bone sclerosis in late OA, and reduced synovitis and pain with cartilage preservation effects. This finding suggests the promising clinical application of PFD as a novel disease-modifying OA drug.

Cardamonin inhibits osteogenic differentiation by downregulating Wnt/beta-catenin signaling and alleviates subchondral osteosclerosis in osteoarthritic mice

Osteoarthritis (OA) is a common degenerative joint disease, and subchondral osteosclerosis is an important pathological change that occurs in its late stages. Cardamonin (CD) is a natural flavonoid isolated from Alpinia katsumadai that has anti-inflammatory activity. The objectives of this study were to investigate the therapeutic effects and potential mechanism of CD in regulating OA subchondral osteosclerosis at in vivo and in vitro settings. Eight-week-old male C57BL/6J mice were randomly divided into four groups: sham operation, anterior cruciate ligament transection (ACLT)-induced OA model, low-dose and high-dose CD treated ACLT-OA model groups. Histological assessment and immunohistochemical examinations for chondrocyte metabolism-related markers metalloproteinase-13, ADAMTS-4, Col II, and Sox-9 were performed. Microcomputed tomography was used to assess the sclerosis indicators in subchondral bone. Further, MC3T3-E1 (a mouse calvarial preosteoblast cell line) cells were treated with various concentrations of CD to reveal the influence and potential molecular pathways of CD in osteogenic differentiations. Animal studies suggested that CD alleviated the pathological changes in OA mice such as maintaining integrity and increasing the thickness of hyaline cartilage, decreasing the thickness of calcified cartilage, decreasing the Osteoarthritis Research Society International score, regulating articular cartilage metabolism, and inhibiting subchondral osteosclerosis. In vitro investigation indicated that CD inhibited alkaline phosphatase expression and production of calcium nodules during osteogenic differentiation of MC3T3-E1 cells. In addition, CD inhibited the expression of osteogenic differentiation-related indicators and Wnt/β-catenin pathway-related proteins. In conclusion, CD inhibits osteogenic differentiation by downregulating Wnt/β-catenin signaling and alleviating subchondral osteosclerosis in a mouse model of OA.

Intrauterine hyperglycemia induces SIRT3-mediated mitochondrial dysfunction: the fetal origin pathogenesis of precocious osteoarthritis

OBJECTIVE

Diabetes and other metabolic and inflammatory comorbidities are highly associated with osteoarthritis (OA). However, whether early-life hyperglycemia exposure affects susceptibility to long-term OA is still unknown. The purpose of this study was to explore the fetal origins of OA and provide insights into early-life safeguarding for individual health.

METHOD

This study utilized streptozotocin to induce intrauterine hyperglycemia and performed destabilization of the medial meniscus surgery on the knee joints of the offspring mice to induce accelerated OA. Cartilage degeneration-related markers, as well as the expression levels of mitochondrial respiratory chain complexes and mitophagy genes in the adult offspring mice, were investigated. In vitro, mitochondrial function and mitophagy of chondrocyte C28/I2 cells stimulated under high glucose conditions were also evaluated. The methylation levels of the sirt3 gene promoter region in the articular cartilage of intrauterine hyperglycemia-exposed offspring mice were further analyzed.

RESULTS

In this study, we found that the intrauterine hyperglycemic environment could lead to an increase in individual susceptibility to OA in late adulthood, mainly due to persistently low levels of Sirt3 expression. Downregulation of Sirt3 causes impaired mitophagy in chondrocytes and abnormal mitochondrial respiratory function due to a failure to clear aged and damaged mitochondria in a timely manner. Overexpressing Sirt3 at the cellular level or using Sirt3 agonists like Honokiol in mouse models can partially rescue mitophagy disorders caused by the hyperglycemic environment and thus alleviate the progression of OA.

CONCLUSION

Our study revealed a significantly increased susceptibility to OA in the gestational diabetes mellitus offspring, which is partly attributed to exposure to adverse factors in utero and ultimately to the onset of disease via epigenetic modulation.

Exosomes loaded a smart bilayer-hydrogel scaffold with ROS-scavenging and macrophage-reprogramming properties for repairing cartilage defect

Enhancing the regeneration of cartilage defects remains challenging owing to limited innate self-healing as well as acute inflammation arising from the overexpression of reactive oxygen species (ROS) in post-traumatic microenvironments. Recently, stem cell-derived exosomes (Exos) have been developed as potential cell-free therapy for cartilage regeneration. Although this approach promotes chondrogenesis, it neglects the emerging inflammatory microenvironment. In this study, a smart bilayer-hydrogel dual-loaded with sodium diclofenac (DC), an anti-inflammatory drug, and Exos from bone marrow-derived mesenchymal stem cells was developed to mitigate initial-stage inflammation and promote late-stage stem-cell recruitment and chondrogenic differentiation. First, the upper-hydrogel composed of phenylboronic-acid-crosslinked polyvinyl alcohol degrades in response to elevated levels of ROS to release DC, which mitigates oxidative stress, thus reprogramming macrophages to the pro-healing state. Subsequently, Exos are slowly released from the lower-hydrogel composed of hyaluronic acid into an optimal microenvironment for the stimulation of chondrogenesis. Both in vitro and in vivo assays confirmed that the dual-loaded bilayer-hydrogel reduced post-traumatic inflammation and enhanced cartilage regeneration by effectively scavenging ROS and reprogramming macrophages. The proposed platform provides multi-staged therapy, which allows for the optimal harnessing of Exos as a therapeutic for cartilage regeneration.

Deferoxamine alleviates chondrocyte senescence and osteoarthritis progression by maintaining iron homeostasis

BACKGROUND

Osteoarthritis (OA) is a prevalent age-related disease characterized by the gradual deterioration of cartilage. The involvement of chondrocyte senescence is crucial in the pathogenesis of OA. Desferoxamine (DFO) is an iron chelator with therapeutic potential in various diseases. However, the relationship of chondrocyte senescence and iron homeostasis is largely unknown.

METHODS

Chondrocyte senescence was induced using tert-butyl hydroperoxide (TBHP), and the impact of DFO on chondrocyte senescence and iron metabolism was assessed through techniques such as western blotting, qRT-PCR, and β-Galactosidase staining. To assess the impact of DFO on chondrocyte senescence and the progression of osteoarthritis (OA), the surgical destabilization of the medial meniscus model was established.

RESULTS

In chondrocytes, TBHP administration resulted in elevated expression of P16, P21, and P53, as well as alterations in SA-β-gal staining. Nevertheless, DFO effectively mitigated chondrocyte senescence induced by TBHP, and reversed the decrease in collagen II expression and increase in MMP13 expression caused by TBHP. Mechanismly, TBHP induced NCOA4 expression and iron release in chondrocytes. Excessive iron could induce chondrocyte senescence, whereas, DFO could inhibit NCOA4 expression and restore ferritin level, and chelate excessive iron. Importantly, intra-articular injection of DFO enhanced collagen II expression and reduced expression of P16, P21, and MMP13 of cartilage in OA mice, and delayed cartilage degeneration.

CONCLUSIONS

Overall, this study provides evidence that DFO has the potential to alleviate chondrocyte senescence induced by TBHP and slow down the progression of osteoarthritis (OA) by effectively chelating excessive iron. These findings suggest that iron chelation could be a promising therapeutic strategy for treating OA.

CKIP-1-Loaded Cartilage-Affinitive Nanoliposomes Reverse Osteoarthritis by Restoring Chondrocyte Homeostasis

Osteoarthritis (OA) is a chronic joint disease characterized by cartilage imbalance and disruption of cartilage extracellular matrix secretion. Identifying key genes that regulate cartilage differentiation and developing effective therapeutic strategies to restore their expression is crucial. In a previous study, we observed a significant correlation between the expression of the gene encoding casein kinase-2 interacting protein-1 (CKIP-1) in the cartilage of OA patients and OA severity scores, suggesting its potential involvement in OA development. To test this hypothesis, we synthesized a chondrocyte affinity plasmid, liposomes CKIP-1, to enhance CKIP-1 expression in chondrocytes. Our results demonstrated that injection of CAP-Lipos-CKIP-1 plasmid significantly improved OA joint destruction and restored joint motor function by enhancing cartilage extracellular matrix (ECM) secretion. Histological and cytological analyses confirmed that CKIP-1 maintains altered the phosphorylation of the signal transduction molecule SMAD2/3 of the transforming growth factor-β (TGF-β) pathway by promoting the phosphorylation of the 8T, 416S sit. Taken together, this work highlights a novel approach for the precise modulation of chondrocyte phenotype from an inflammatory to a noninflammatory state for the treatment of OA and may be broadly applicable to patients suffering from other arthritic diseases.

Therapeutic effect of San Bi Tang combined with glucosamine sulfate capsules in cold-dampness-type knee osteoarthritis

BACKGROUND

Cold-dampness-type knee osteoarthritis is a common middle-aged and elderly disease, but its pathogenesis is not fully understood, and its clinical treatment has limitations. Glucosamine sulfate capsules are commonly used for treating arthritis, and San Bi Tang is a classic formula of traditional Chinese medicine (TCM) that has the effects of warming yang, dispelling dampness, relaxing muscles, and activating collaterals. This research hypothesized that the combination of modified San Bi Tang and glucosamine sulfate capsules could enhance the clinical efficacy of treating cold-dampness-type knee osteoarthritis through complementary effects.

AIM

To analyze the clinical efficacy of San Bi Tang combined with glucosamine sulfate capsules when treating cold-dampness-type knee osteoarthritis.

METHODS

A total of 110 patients with cold-dampness-type knee osteoarthritis were selected as research subjects and randomly divided into a control group and an experimental group of 55 cases each. The control group received only treatment with glucosamine sulfate capsules, while the experimental group received additional treatment with modified San Bi Tang for a duration of 5 wk. The patients' knee joint functions, liver and kidney function indicators, adverse reactions, and vital signs were evaluated and analyzed using SPSS 26.0 software.

RESULTS

Before treatment, the two groups' genders, ages, and scores were not significantly different, indicating comparability. Both groups' scores improved after treatment, which could indicate pain and knee joint function improvement, but the test group had better scores. The TCM-specific symptoms and the clinical efficacy of the treatment in the test group were higher. Before and after treatment, there were no abnormalities in the patients' liver and kidney function indicators.

CONCLUSION

The combination of modified San Bi Tang and glucosamine sulfate capsules is superior to treatment with sulfated glucosamine alone and has high safety.

A Novel Dinuclear Complex-PLC Composite Material as Fluorescent Switch in Treatment on Osteoarthritis

In this study, we synthesized a novel Co(II)-containing coordination compound (CP) [Co2(MMBA)2(HPT)2(H2O)2]·2H2O (1) through a solvothermal reaction of Co(NO3)6·6H2O with 3-(pyridin-2-yl)-1 H-1,2,4-triazole (HPT) and 2-(4-methylbenzoyl)benzoic acid (HMMBA). Fluorescence spectroscopy confirmed that this compound exhibited superior blue fluorescence properties compared to the original ligands. Further, aspirin (ASA) was loaded onto this CP via physical adsorption to create CP-ASA. Interestingly, the fluorescence properties of the CP decreased with the loading of the drug but were restored upon drug release. Leveraging the unique optical properties and biocompatibility of Polymer Liquid Crystal (PLC), we further encapsulated CP-ASA, forming the CP-PLC@ASA composite. The target product was confirmed through various characterization techniques including Elemental Analysis (EA), Fourier-Transform Infrared Spectroscopy (FT-IR), Powder X-Ray Diffraction (PXRD), and Thermogravimetric Analysis (TGA). Moreover, the biological activity of this composite was evaluated in vitro for osteoarthritis, and its potential mechanisms were explored.

Injectable Ozone-Rich Nanocomposite Hydrogel Loaded with D-Mannose for Anti-Inflammatory and Cartilage Protection in Osteoarthritis Treatment

Osteoarthritis (OA) is a dynamic condition characterized by cartilage damage and synovial inflammation. Ozone (O3) shows potential therapeutic effects owing to its anti-inflammatory properties; however, its high reactivity and short half-life substantially limit its effectiveness in OA treatment. In this study, an ozone-rich thermosensitive nanocomposite hydrogel loaded with D-mannose is developed for OA treatment. Briefly, O3 is encapsulated in nanoparticles (NPs) composed of perfluorotributylamine and fluorinated hyaluronic acid to improve its stability. Next, D-mannose is conjugated with α-amino of the hydroxypropyl chitin (HPCH) via Schiff base to prepare MHPCH. These nanoparticles are encapsulated in MHPCH to produce O3 NPs@MHPCH. In vitro cell experiments demonstrate that the O3 NPs@MHPCH treatment significantly reduced VEGF and inflammation levels, accompanied by a decrease in inflammatory factors such as IL-1β, IL-6, TNF-α, and iNOS. Furthermore, O3 NPs@MHPCH promotes the expression of collagen II and aggrecan and stimulates chondrocyte proliferation. Additionally, in vivo studies show that O3 NPs@MHPCH significantly alleviated OA by reducing synovial inflammation, cartilage destruction, and subchondral bone remodeling. O3 NPs@MHPCH offers a promising option for improving the efficacy of O3 therapy and reducing the risk of synovial inflammation and cartilage degeneration in OA.

Animal Models of Osteoarthritis: Updated Models and Outcome Measures 2016-2023

Purpose

Osteoarthritis (OA) is a global musculoskeletal disorder that affects primarily the knee and hip joints without any FDA-approved disease-modifying therapies. Animal models are essential research tools in developing therapies for OA; many animal studies have provided data for the initiation of human clinical trials. Despite this, there is still a need for strategies to recapitulate the human experience using animal models to better develop treatments and understand pathogenesis. Since our last review on animal models of osteoarthritis in 2016, there have been exciting updates in OA research and models. The main purpose of this review is to update the latest animal models and key features of studies in OA research.

Method

We used our existing classification method and screened articles in PubMed and bibliographic search for animal OA models between 2016 and 2023. Relevant and high-cited articles were chosen for inclusion in this narrative review.

Results

Recent studies were analyzed and classified. We also identified ex vivo models as an area of ongoing research. Each animal model offers its own benefit in the study of OA and there are a full range of outcome measures that can be assessed. Despite the vast number of models, each has its drawbacks that have limited translating approved therapies for human use.

Conclusion

Depending on the outcome measures and objective of the study, researchers should pick the best model for their work. There have been several exciting studies since 2016 that have taken advantage of regenerative engineering techniques to develop therapies and better understand OA.

Lay Summary

Osteoarthritis (OA) is a chronic debilitating disease without any cure that affects mostly the knee and hip joints and often results in surgical joint replacement. Cartilage protects the joint from mechanical forces and degrades with age or in response to injury. The many contributing causes of OA are still being investigated, and animals are used for preclinical research and to test potential new treatments. A single consensus OA animal model for preclinical studies is non-existent. In this article, we review the many animal models for OA and provide a much-needed update on studies and model development since 2016.

Bone and Joint-on-Chip Platforms: Construction Strategies and Applications

Organ-on-a-chip, also known as "tissue chip," is an advanced platform based on microfluidic systems for constructing miniature organ models in vitro. They can replicate the complex physiological and pathological responses of human organs. In recent years, the development of bone and joint-on-chip platforms aims to simulate the complex physiological and pathological processes occurring in human bones and joints, including cell-cell interactions, the interplay of various biochemical factors, the effects of mechanical stimuli, and the intricate connections between multiple organs. In the future, bone and joint-on-chip platforms will integrate the advantages of multiple disciplines, bringing more possibilities for exploring disease mechanisms, drug screening, and personalized medicine. This review explores the construction and application of Organ-on-a-chip technology in bone and joint disease research, proposes a modular construction concept, and discusses the new opportunities and future challenges in the construction and application of bone and joint-on-chip platforms.

The potential for senotherapy as a novel approach to extend life quality in veterinary medicine

Cellular senescence, a condition where cells undergo arrest and can assume an inflammatory phenotype, has been associated with initiation and perpetuation of inflammation driving multiple disease processes in rodent models and humans. Senescent cells secrete inflammatory cytokines, proteins, and matrix metalloproteinases, termed the senescence associated secretory phenotype (SASP), which accelerates the aging processes. In preclinical models, drug interventions termed "senotherapeutics" selectively clear senescent cells and represent a promising strategy to prevent or treat multiple age-related conditions in humans and veterinary species. In this review, we summarize the current available literature describing in vitro evidence for senotheraputic activity, preclinical models of disease, ongoing human clinical trials, and potential clinical applications in veterinary medicine. These promising data to date provide further justification for future studies identifying the most active senotherapeutic combinations, dosages, and routes of administration for use in veterinary medicine.

Efficacy of Anti-Interleukin-1 Therapeutics in the Treatment of Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials from the Years 2000 to 2023

Objectives: This study aimed to evaluate the efficacy of anti-interleukin-1 therapeutics for treating knee osteoarthritis (KOA). Our research included interleukin-1 (IL-1) inhibitors, IL-1 antibodies and IL-1 receptor antagonists (IL-1 Ras). Methods: We systematically searched PubMed and Mendeley to find randomized control trials (RCTs) or clinical trials (CTs) of anti-interleukin-1 therapeutics in KOA from 2000 to 2023. The outcomes were changes in pain, function and stiffness scores. The research was conducted between November 2023 and January 2024. The risk of bias was assessed using Cochrane Risk of Bias tool RoB 2. Results: Analysis of the nine included studies showed a statistically significant difference in terms of the pain relief group (SMD = -0.20, 95% CI: -0.39 to -0.01, p = 0.0348), physical function improvement (SMD = -0.20, 95% CI: -0.39 to 0.00, p = 0.0479) and stiffness reduction (SMD = -0.22, 95% CI: -0.43 to 0.00, p = 0.0475) between anti-IL-1 therapeutics and placebo or nonsteroidal anti-inflammatory drugs (NSAIDs). However, when we separately analysed placebo and NSAIDs subgroups, the statistical significance was observed only in the placebo group. Our article was limited by the quality of the included RCTs. Two of the included trials were of poor methodological quality, and five showed selective reporting. Conclusions: The results of our study suggest that anti-IL-1 therapeutics might have better efficacy in KOA treatment than placebo or NSAIDs; yet, taking into account the limited availability of studies and data concerning anti-IL-1 in osteoarthritis treatment, we think that more high-quality RCTs on this subject are needed.

PUM2 promoted osteoarthritis progression through PTEN-mediated chondrocyte ferroptosis by facilitating NEDD4 mRNA degradation

Osteoarthritis (OA) is a prevalent degenerative joint disease with a lack of effective therapeutic. Chondrocyte ferroptosis contributes to the progression of OA. PUM2 is shown to exacerbate ischemia-reperfusion-induced neuroinflammation by promoting ferroptosis, but its role in OA remains unexplored. Here, primary mouse chondrocytes were stimulated with IL-1β to mimic OA chondrocyte injury in vitro. And PUM2 was upregulated in OA cartilage tissues and IL-1β-induced chondrocytes. Silencing PUM2 alleviated IL-1β-induced chondrocyte inflammation and ECM degradation. Mechanistically, PUM2 facilitated the degradation of NEDD4 mRNA by binding to the 3'UTR of NEDD4 mRNA, which in turn inhibited NEDD4 induced PTEN ubiquitination and degradation. Consistently, NEDD4 silencing reversed the ameliorative effect of PUM2 knockdown on chondrocyte injury, and overexpression of PTEN abolished the improved role of NEDD4 in chondrocyte injury. Moreover, PTEN aggravated IL-1β-induced ferroptosis in chondrocytes through the Nrf2/HO-1 pathway by increasing the levels of Fe2+, ROS, MDA, and ACSL4 protein, decreasing the activity of SOD and the levels of GSH and GPX4 protein, and aggravating mitochondrial damage. Additionally, destabilized medial meniscus (DMM) were conducted to establish the OA mouse model, and adenovirus-mediated PUM2 shRNA was administered intra-articularly. Silencing PUM2 attenuated OA-induced cartilage damage in vivo. In conclusion, PUM2 promoted OA progression through PTEN-mediated chondrocyte ferroptosis by facilitating NEDD4 mRNA degradation.

Novel insights into the role of ubiquitination in osteoarthritis

Ubiquitination (Ub) and deubiquitination are crucial post-translational modifications (PTMs) that precisely regulate protein degradation. Under the catalysis of a cascade of E1-E2-E3 ubiquitin enzymes, ubiquitination extensively regulates protein degradation exerting direct impact on various cellular processes, while deubiquitination opposes the effect of ubiquitination and prevents proteins from degradation. Notably, such dynamic modifications have been widely investigated to be implicated in cell cycle, transcriptional regulation, apoptosis and so on. Therefore, dysregulation of ubiquitination and deubiquitination could lead to certain diseases through abnormal protein accumulation and clearance. Increasing researches have revealed that the dysregulation of catalytic regulators of ubiquitination and deubiquitination triggers imbalance of cartilage homeostasis that promotes osteoarthritis (OA) progression. Hence, it is now believed that targeting on Ub enzymes and deubiquitinating enzymes (DUBs) would provide potential therapeutic pathways. In the following sections, we will summarize the biological role of Ub enzymes and DUBs in the development and progression of OA by focusing on the updating researches, with the aim of deepening our understanding of the underlying molecular mechanism of OA pathogenesis concerning ubiquitination and deubiquitination, so as to explore novel potential therapeutic targets of OA treatment.

Pannexins in the musculoskeletal system: new targets for development and disease progression

During cell differentiation, growth, and development, cells can respond to extracellular stimuli through communication channels. Pannexin (Panx) family and connexin (Cx) family are two important types of channel-forming proteins. Panx family contains three members (Panx1-3) and is expressed widely in bone, cartilage and muscle. Although there is no sequence homology between Panx family and Cx family, they exhibit similar configurations and functions. Similar to Cxs, the key roles of Panxs in the maintenance of physiological functions of the musculoskeletal system and disease progression were gradually revealed later. Here, we seek to elucidate the structure of Panxs and their roles in regulating processes such as osteogenesis, chondrogenesis, and muscle growth. We also focus on the comparison between Cx and Panx. As a new key target, Panxs expression imbalance and dysfunction in muscle and the therapeutic potentials of Panxs in joint diseases are also discussed.

Self-Reinforced MOF-Based Nanogel Alleviates Osteoarthritis by Long-Acting Drug Release

Intra-articular injection of drugs is an effective strategy for osteoarthritis (OA) treatment. However, the complex microenvironment and limited joint space result in rapid clearance of drugs. Herein, a nanogel-based strategy is proposed for prolonged drug delivery and microenvironment remodeling. Nanogel is constructed through the functionalization of hyaluronic acid (HA) by amide reaction on the surface of Kartogenin (KGN)-loaded zeolitic imidazolate framework-8 (denoted as KZIF@HA). Leveraging the inherent hydrophilicity of HA, KZIF@HA spontaneously forms nanogels, ensuring extended drug release in the OA microenvironment. KZIF@HA exhibits sustained drug release over one month, with low leakage risk from the joint cavity compared to KZIF, enhanced cartilage penetration, and reparative effects on chondrocytes. Notably, KGN released from KZIF@HA serves to promote extracellular matrix (ECM) secretion for hyaline cartilage regeneration. Zn2+ release reverses OA progression by promoting M2 macrophage polarization to establish an anti-inflammatory microenvironment. Ultimately, KZIF@HA facilitates cartilage regeneration and OA alleviation within three months. Transcriptome sequencing validates that KZIF@HA stimulates the polarization of M2 macrophages and secretes IL-10 to inhibit the JNK and ERK pathways, promoting chondrocytes recovery and enhancing ECM remodeling. This pioneering nanogel system offers new therapeutic opportunities for sustained drug release, presenting a significant stride in OA treatment strategies.

Oleic and linoleic acids promote chondrocyte apoptosis by inhibiting autophagy via downregulation of SIRT1/FOXO1 signaling

Osteoarthritis (OA) is a complex joint disease that currently has no cure. OA involves metabolic disorders in chondrocytes and an imbalance between autophagy and apoptosis. As a common risk factor for OA, obesity induces changes in the fatty acid composition of synovial fluid, thereby disturbing chondrocyte homeostasis. However, whether unsaturated fatty acids affect the development of OA by regulating chondrocyte autophagy remains unclear. This study aimed to determine the effects of oleic and linoleic acids on chondrocyte autophagy and related mechanisms. Based on the mass spectrometry results, the levels of multiple unsaturated fatty acids, including oleic and linoleic acids, in the synovial fluid of patients with OA and obesity were significantly higher than those in patients with OA only. Moreover, we found that FOXO1 and SIRT1 were downregulated after oleic and linoleic acids treatment of chondrocytes, which inhibited chondrocyte autophagy. Importantly, the upregulation of SIRT1 and FOXO1 expression not only increased the level of autophagy but also improved the expression of chondrocyte extracellular matrix proteins. Furthermore, upregulated SIRT1 and FOXO1 expression alleviated the destruction of the articular cartilage in an OA rat model. Our results suggest that SIRT1/FOXO1 signaling can alleviate oleic acid- and linoleic acid-induced cartilage degradation both in vitro and in vivo and that the SIRT1/FOXO1 pathway may serve as an effective treatment target for inhibiting OA progression.

Schisandrin B Alleviates LPS Induced Mitochondrial Damage in C28I2 Cells

Osteoarthritis is a common joint disease characterized by damage to the joint cartilage that occurs throughout the entire joint tissue. This damage primarily manifests as pain in the affected area. In clinical practice, medication is commonly used to relieve pain, but the treatment's effectiveness is poor and recurrent attacks are likely. Schisandrin B is the most abundant biphenylcyclohexene lignan found in the traditional Chinese medicine Schisandra chinensis, and it possesses various pharmacological effects. This study aims to investigate the protective effect of Schisandrin B on mitochondrial damage in osteoarthritis (C28I2 cells) under an inflammatory environment induced by LPS. Cell proliferation and activity, scratch tests, and LDH release tests are utilized to assess cell growth and migration ability. The immunofluorescence assay was used to detect the expression levels of proliferation and apoptosis proteins. The Western Blot assay was used to detect the expression levels of mitochondrial fusion and division proteins. The JC-1 assay was used to detect changes in mitochondrial membrane potential. The mitochondrial fluorescence probe assay was used to detect mitochondrial activity. Through research, it was found that Schisandrin B promotes the proliferation, growth, and migration of C28I2 cells, reduces apoptosis of C28I2 cells, balances mitochondrial fusion and division, stabilizes mitochondrial membrane potential, and promotes mitochondrial activity in an LPS induced inflammatory environment.

Structure-Guided Discovery of Potent and Selective CLK2 Inhibitors for the Treatment of Knee Osteoarthritis

Osteoarthritis is the most common joint disorder. However, there are no disease-modifying drugs approved for OA treatment. CDC2-like kinase 2 (CLK2) could modulate Wnt signaling via alternative splicing of Wnt target genes and further affect bone differentiation, chondrocyte function, and inflammation, making CLK2 an attractive target for OA therapy. In this study, we designed and synthesized a series of highly potent CLK2 inhibitors based on Indazole 1. Among them, compound LQ23 showed more elevated inhibitory activity against CLK2 than the lead compound (IC50, 1.4 nM) with high CLK2/CLK3 selectivity (>70-fold). Furthermore, LQ23 showed outstanding antiosteoarthritis effects in vitro and in vivo, with the roles specific in decreased inflammatory cytokines, downregulated cartilage degradative enzymes, and increased joint cartilage via suppressing CLK2/Wnt signaling pathway. Overall, these data support LQ23 as a potential candidate for intra-articular knee OA therapy, leveraging its unique mechanism of action for targeted treatment.

Involvement of Fgf2-mediated tau protein phosphorylation in cognitive deficits induced by sevoflurane in aged rats

OBJECTIVE

Anesthetics have been linked to cognitive alterations, particularly in the elderly. The current research delineates how Fibroblast Growth Factor 2 (Fgf2) modulates tau protein phosphorylation, contributing to cognitive impairments in aged rats upon sevoflurane administration.

METHODS

Rats aged 3, 12, and 18 months were subjected to a 2.5% sevoflurane exposure to form a neurotoxicity model. Cognitive performance was gauged, and the GEO database was employed to identify differentially expressed genes (DEGs) in the 18-month-old cohort post sevoflurane exposure. Bioinformatics tools, inclusive of STRING and GeneCards, facilitated detailed analysis. Experimental validations, both in vivo and in vitro, examined Fgf2's effect on tau phosphorylation.

RESULTS

Sevoflurane notably altered cognitive behavior in older rats. Out of 128 DEGs discerned, Fgf2 stood out as instrumental in regulating tau protein phosphorylation. Sevoflurane exposure spiked Fgf2 expression in cortical neurons, intensifying tau phosphorylation via the PI3K/AKT/Gsk3b trajectory. Diminishing Fgf2 expression correspondingly curtailed tau phosphorylation, neurofibrillary tangles, and enhanced cognitive capacities in aged rats.

CONCLUSION

Sevoflurane elicits a surge in Fgf2 expression in aging rats, directing tau protein phosphorylation through the PI3K/AKT/Gsk3b route, instigating cognitive aberrations.

Identification of therapeutic targets in osteoarthritis by combining heterogeneous transcriptional datasets, drug-induced expression profiles, and known drug-target interactions

BACKGROUND

Osteoarthritis (OA) is a multifactorial, hypertrophic, and degenerative condition involving the whole joint and affecting a high percentage of middle-aged people. It is due to a combination of factors, although the pivotal mechanisms underlying the disease are still obscure. Moreover, current treatments are still poorly effective, and patients experience a painful and degenerative disease course.

METHODS

We used an integrative approach that led us to extract a consensus signature from a meta-analysis of three different OA cohorts. We performed a network-based drug prioritization to detect the most relevant drugs targeting these genes and validated in vitro the most promising candidates. We also proposed a risk score based on a minimal set of genes to predict the OA clinical stage from RNA-Seq data.

RESULTS

We derived a consensus signature of 44 genes that we validated on an independent dataset. Using network analysis, we identified Resveratrol, Tenoxicam, Benzbromarone, Pirinixic Acid, and Mesalazine as putative drugs of interest for therapeutics in OA for anti-inflammatory properties. We also derived a list of seven gene-targets validated with functional RT-qPCR assays, confirming the in silico predictions. Finally, we identified a predictive subset of genes composed of DNER, TNFSF11, THBS3, LOXL3, TSPAN2, DYSF, ASPN and HTRA1 to compute the patient's risk score. We validated this risk score on an independent dataset with a high AUC (0.875) and compared it with the same approach computed using the entire consensus signature (AUC 0.922).

CONCLUSIONS

The consensus signature highlights crucial mechanisms for disease progression. Moreover, these genes were associated with several candidate drugs that could represent potential innovative therapeutics. Furthermore, the patient's risk scores can be used in clinical settings.

Relationship between dietary inflammation index and frailty in patients with osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a common chronic joint disease that significantly affects an individual's quality-of-life and frailty has become one of the common complications in OA patients as the disease progresses. The relationship between dietary patterns is not clear.

METHODS

All participants are from the National Health and Nutrition Examination Survey (NHANES) and have been diagnosed with OA. The dietary inflammation index (DII) is calculated based on the dietary intake reported by the participants. Logistic regression analysis is used to investigate the relationship between DII and frailty. Restricted cubic splines are utilised to explore their nonlinear relationship. Mediation analysis is conducted to explore the role of inflammation in this relationship.

RESULTS

A total of 2,530 OA patients were included in the study, with an average age of 64.46 (12.67) years. After adjusting for covariates, for each one standard deviation increase in DII, the risk of frailty increased by 15% (OR = 1.15, 95% CI = 1.03-1.28). Compared to patients with DII < -1, patients with DII > 1 had a significantly higher risk of frailty (OR = 1.50, 95% CI = 1.05-2.14).

CONCLUSIONS

The findings of this study indicate a positive association between DII and the risk of frailty in OA patients. These results underscore the potential impact of dietary interventions in improving the quality-of-life for OA patients.

κ-Opioid receptor activation attenuates osteoarthritis synovitis by regulating macrophage polarization through the NF-κB pathway

Osteoarthritis (OA) is a prevalent and chronic joint disease that affects the aging population, causing pain and disability. Macrophages in synovium are important mediators of synovial inflammatory activity and pathological joint pain. Previous studies have demonstrated the significant involvement of κ-opioid receptor (KOR) in the regulation of pain and inflammation. Our study reveals a significant reduction in synovial KOR expression among patients and mice with OA. Here, we find that KOR activation effectively inhibits the expressions of the LPS-induced-inflammatory cytokines TNF-α and IL-6 by inhibiting macrophage M1 phenotype. Mechanistically, KOR activation effectively suppresses the proinflammatory factor secretion of macrophages by inhibiting the translocation of NF-κB into the nucleus. Our animal experiments reveal that activation of KOR effectively alleviates knee pain and prevents synovitis progression in OA mice. Consistently, KOR administration suppresses the expressions of M1 macrophage markers and the NF-κB pathway in the synovium of the knee. Collectively, our study suggests that targeting KOR may be a viable strategy for treating OA by inhibiting synovitis and improving joint pain in affected patients.

Mesenchymal stem cell-derived exosomes as a promising cell-free therapy for knee osteoarthritis

Osteoarthritis (OA), as a degenerative disease, leads to high socioeconomic burdens and disability rates. The knee joint is typically the most affected and is characterized by progressive destruction of articular cartilage, subchondral bone remodeling, osteophyte formation and synovial inflammation. The current management of OA mainly focuses on symptomatic relief and does not help to slow down the advancement of disease. Recently, mesenchymal stem cells (MSCs) and their exosomes have garnered significant attention in regenerative therapy and tissue engineering areas. Preclinical studies have demonstrated that MSC-derived exosomes (MSC-Exos), as bioactive factor carriers, have promising results in cell-free therapy of OA. This study reviewed the application of various MSC-Exos for the OA treatment, along with exploring the potential underlying mechanisms. Moreover, current strategies and future perspectives for the utilization of engineered MSC-Exos, alongside their associated challenges, were also discussed.

CircIRAK3 exerts negative feedback regulation on inflammation by binding to HNRNP U and destabilizing proinflammatory cytokine mRNA in osteoarthritis and chondrogenesis

Osteoarthritis (OA) is the most prevalent age-related and degenerative joint disease with limited treatment options. Previous studies have identified the therapeutic effects of mesenchymal stem cells (MSCs) therapy. Nevertheless, chronic inflammation impedes MSCs therapeutic effect. There have been reports suggesting that circular RNAs (circRNAs) are involved in OA and chondrogenesis. The combination of MSCs and circRNAs in therapies appears to be a promising option. In this study, we identified circIRAK3 as a significant regulator in cartilage degeneration and chondrogenesis through high-throughput sequencing analyses. We observed increased circIRAK3 in OA cartilage and during MSCs chondrogenesis. Knockdown of circIRAK3 resulted in excessive apoptosis, inhibited proliferation, and degradation of chondrocytes, along with the inhibition of MSCs chondrogenesis. Mechanistically, circIRAK3 bound to HNRNP U and competitively prevented its binding to IL-1β, TNFα, and IL6 mRNA, thereby promoting mRNA degradation. Notably, circIRAK3 expression in plasma increased with higher OARSI scores. Intra-articular injection of adeno-associated virus-circIRAK3 delayed cartilage degeneration and reduced inflammation in DMM mouse model. Our study highlights a compensatory regulation network of circIRAK3 in chondrocytes in response to inflammation. CircIRAK3 has the potential to serve as a new therapeutic target for OA. Furthermore, therapies targeting circIRAK3 combined with MSCs hold promise.

Krüppel-like factor 15 deficiency exacerbates osteoarthritis through reduced expression of peroxisome proliferator-activated receptor gamma signaling in mice

OBJECTIVE

Krüppel-like zinc finger transcription factors (KLFs) play diverse roles in mammalian cell differentiation and development. In this study, we investigated the function of KLF15 in the progression of osteoarthritis (OA).

METHODS

0Destabilization of the medial meniscus (DMM) surgery was performed in 10-week-old male wild-type control (WT) mice and cartilage-specific KLF15 knockout (KO) mice. Histological analysis, immunohistochemistry, and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling staining were performed. Morphological changes were measured using microcomputed tomography. Six mice from each group were analyzed (total number of mice analyzed: 60). In vitro, immunofluorescence, quantitative reverse transcription-polymerase chain reaction, and western blot analyses were performed.

RESULTS

KLF15 KO DMM mice exhibited significant cartilage degradation compared to WT mice. According to the Osteoarthritis Research Society International cartilage OA-histopathology scoring system, the mean sum score in KLF15 KO mice was significantly higher than that in WT mice at 8 weeks after surgery. Immunohistochemistry results revealed KLF15 KO mice exhibited reduced peroxisome proliferator-activated receptor gamma (PPARγ) expression, increased pIKKα/β, a disintegrin-like and metalloproteinase with thrombospondin motifs (ADAMTS) 5, and Matrix metalloproteinases (MMP13) expression, and reduced Forkhead box O (FOXO1) and Light chain 3B (LC3B) expression. Inhibition of PPARγ phosphorylation accelerated the effects of interleukin (IL) 1β-treatment in both KLF15 KO and WT chondrocytes, and activation of PPARγ expression canceled the IL1β-induced catabolic effects.

CONCLUSION

Our results indicated that the OA phenotype of KLF15 KO DMM mice was influenced by reduced PPARγ expression, including enhanced pIKKα/β, ADAMTS5, and MMP13 expression, reduced autophagy, and increased apoptosis. KLF15 regulation may constitute a possible therapeutic strategy for the treating OA.

Cabozantinib prevents AGEs-induced degradation of type 2 collagen and aggrecan in human chondrocytes

Osteoarthritis (OA) is a joint degenerative disease commonly observed in the old population, lacks effective therapeutic methods, and markedly impacts the normal lives of patients. Degradation of extracellular matrix (ECM) is reported to participate in OA development, which is a potential target for treating OA. Cabozantinib is an inhibitor of tyrosine kinases and is recently claimed with suppressive properties against inflammation. Herein, the protective function of Cabozantinib on advanced glycation end products (AGEs)-induced damages to chondrocytes was tested. SW1353 chondrocytes were stimulated with 100 μg/ml AGEs with or without 10 and 20 μM Cabozantinib for 24 h. Signally increased reactive oxygen species (ROS) levels, declined reduced glutathione (GSH) levels, and elevated release of inflammatory cytokines were observed in AGEs-stimulated SW1353 chondrocytes, which were markedly reversed by Cabozantinib. Moreover, the notably reduced type II collagen and aggrecan levels, and increased matrix metalloproteinase-13 (MMP-13) and A Disintegrin and Metalloproteinase with Thrombospondin Motifs-5 (ADAMTS-5) levels in AGEs-stimulated SW1353 chondrocytes were largely rescued by Cabozantinib. The downregulated Sry-type high-mobility-group box 9 (SOX-9) observed in AGEs-stimulated SW1353 chondrocytes was abolished by Cabozantinib. Furthermore, the impact of Cabozantinib on type II collagen and aggrecan levels in AGEs-treated SW1353 chondrocytes was abrogated by silencing SOX-9. Collectively, Cabozantinib prevented AGEs-induced degradation of type 2 collagen and aggrecan in human chondrocytes by mediating SOX-9.

Fructose-bisphosphatase1 (FBP1) alleviates experimental osteoarthritis by regulating Protein crumbs homolog 3 (CRB3)

PURPOSE

To identify the role of gluconeogenesis in chondrocytes in osteoarthritis (OA).

MATERIALS AND METHODS

Cartilage samples were collected from OA patients and C57 mice and were stained with Safranin O-Fast Green to determine the severity of OA. Periodic acid Schiff staining was used to characterize the contents of polysaccharides and SA-βGal staining was used to characterize the aging of chondrocytes. Immunohistochemistry and western blotting were used to detect fructose-bisphosphatase1 (FBP1), SOX9, MMP13, P21, and P16 in cartilage or chondrocyte. The mRNA levels of fbp1, mmp13, sox9, colX, and acan were analyzed by qPCR to evaluate the role of FBP1 in chondrocytes.

RESULTS

The level of polysaccharides in cartilage was reduced in OA and the expression of FBP1 was also reduced. We treated the chondrocytes with IL-1β to cause OA in vitro, and then made chondrocytes overexpress FBP1 with plasma. It shows that FBP1 alleviated the degeneration and senescence of chondrocytes in vitro and that it also showed the same effects in vivo experiments. To further understand the mechanism of FBP1, we screened the downstream protein of FBP1 and found that CRB3 was significantly downregulated. And we confirmed that CRB3 suppressed the degeneration and delayed senescence of chondrocytes.

CONCLUSIONS

FBP1 promoted the polysaccharide synthesis in cartilage and alleviated the degeneration of cartilage by regulating CRB3, so FBP1 is a potential target in treating OA.

Injectable hydrogel with selenium nanoparticles delivery for sustained glutathione peroxidase activation and enhanced osteoarthritis therapeutics

Reactive oxygen burst in articular chondrocytes is a major contributor to osteoarthritis progression. Although selenium is indispensable role in the antioxidant process, the narrow therapeutic window, delicate toxicity margins, and lack of an efficient delivery system have hindered its translation to clinical applications. Herein, transcriptomic and biochemical analyses revealed that osteoarthritis was associated with selenium metabolic abnormality. A novel injectable hydrogel to deliver selenium nanoparticles (SeNPs) was proposed to intervene selenoprotein expression for osteoarthritis treatment. The hydrogels based on oxidized hyaluronic acid (OHA) cross-linked with hyaluronic acid-adipic acid dihydrazide (HA-ADH) was formulated to load SeNPs through a Schiff base reaction. The hydrogels were further incorporated with SeNPs, which exhibited minimal toxicity, mechanical properties, self-healing capability, and sustained drug release. Encapsulated with SeNPs, the hydrogels facilitated cartilage repair through synergetic effects of scavenging reactive oxygen species (ROS) and depressing apoptosis. Mechanistically, the hydrogel restored redox homeostasis by targeting glutathione peroxidase-1 (GPX1). Therapeutic outcomes of the SeNPs-laden hydrogel were demonstrated in an osteoarthritis rat model created by destabilization of the medial meniscus, including cartilage protection, subchondral bone sclerosis improvement, inflammation attenuation, and pain relief were demonstrated. These results highlight therapeutic potential of OHA/HA-ADH@SeNPs hydrogels, providing fundamental insights into remedying selenium imbalance for osteoarthritis biomaterial development.

Piezo1 transforms mechanical stress into pro senescence signals and promotes osteoarthritis severity

Osteoarthritis (OA) is a prevalent disease among elderly people and is often characterized by chronic joint pain and dysfunction. Recently, growing evidence of chondrocyte senescence in the pathogenesis of OA has been found, and targeting senescence has started to be recognized as a therapeutic approach for OA. Piezo1, a mechanosensitive Ca2+ channel, has been reported to be harmful in sensing abnormal mechanical overloading and leading to chondrocyte apoptosis. However, whether Piezo1 can transform mechanical signals into senescence signals has rarely been reported. In this study, we found that severe OA cartilage expressed more Piezo1 and the senescence markers p16 and p21. 24 h of periodic mechanical stress induced chondrocyte senescence in vitro. In addition, we demonstrated the pivotal role of Piezo1 in OA chondrocyte senescence induced by mechanical stress. Piezo1 sensed mechanical stress and promoted chondrocyte senescence via its Ca2+ channel ability. Moreover, Piezo1 promoted SASP factors production under mechanical stress, particularly in IL-6 and IL-1β. p38MAPK and NF-κB activation were two key pathways that responded to Piezo1 activation and promoted IL-6 and IL-1β production, respectively. Collectively, our study revealed a connection between abnormal mechanical stress and chondrocyte senescence, which was mediated by Piezo1.

Articular Cartilage Regeneration via Induced Chondrocyte Autophagy by Sustained Release of Leptin Inhibitor from Thermo-Sensitive Hydrogel through STAT3/REDD1/mTORC1 Cascade

The pathophysiology of osteoarthritis (OA) is closely linked to autophagy abnormalities in articular chondrocytes, the sole mature cell type in healthy cartilage. Nevertheless, the precise molecular mechanism remains uncertain. Previous research has demonstrated that leptin activates mTORC1 , thereby inhibiting chondrocyte autophagy during the progression of OA. In this study, it is demonstrated that the presence of leptin induces a substantial increase in the expression of STAT3, leading to a notable decrease in REDD1 expression and subsequent phosphorylation of p70S6K, a recognized downstream effector of mTORC1. Conversely, inhibition of leptin yields contrasting effects. Additionally, the potential advantages of utilizing a sustained intra-articular release of a leptin inhibitor (LI) via an injectable, thermosensitive poly(D,L-lactide)-poly(ethylene glycol)-poly(D,L-lactide) (PDLLA-PEG-PDLLA: PLEL) hydrogel delivery system for the purpose of investigating its impact on cartilage repair are explored. The study conducted on LI-loaded PLEL (PLEL@LI) demonstrates remarkable efficacy in inhibiting OA and displays encouraging therapeutic advantages in the restoration of subchondral bone and cartilage. These findings establish a solid foundation for the advancement of a pioneering treatment approach utilizing PLEL@LI for OA.

Effects of an enhanced recovery after surgery nursing programme on surgical site wound infection and postoperative complications in patients undergoing total knee arthroplasty: A meta-analysis

This meta-analysis aimed to investigate the effects of the enhanced recovery after surgery (ERAS) nursing program on surgical wound infection (SWI) and postoperative complications in patients undergoing total knee arthroplasty (TKA). The PubMed, Web of Science, Cochrane Library, Embase, China National Knowledge Infrastructure and Wanfang databases were searched from the date of establishment of the database until August 2023 for randomised controlled trials (RCTs) that assessed the effects of the ERAS nursing program on SWI and postoperative complications in patients undergoing TKA. The literature was screened, data were extracted by two independent investigators, and the literature quality was assessed using the methods recommended by the Cochrane Collaboration. Data analysis was performed using Stata 17.0 software. Nineteen RCTs with 1580 patients were included in the study. The meta-analysis results showed that the rates of SWI (odds ratio [OR] = 0.19, 95% confidence interval [CI]: 0.10-0.37, p < 0.001) and postoperative complications (OR = 0.18, 95% CI: 0.12-0.25, p < 0.001) were significantly lower in the ERAS intervention group than those in the control group. Therefore, ERAS intervention after TKA can significantly reduce the occurrence of SWI and postoperative complications. It has a remarkable rehabilitation effect and can be widely used in clinical settings.

Research of STEAP3 interaction with Rab7A and RACK1 to modulate the MAPK and JAK/STAT signaling in Osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation and inflammation. The molecular mechanisms underlying OA progression remain incompletely understood. In this study, we investigated the role of STEAP3 (Six Transmembrane Epithelial Antigen of the Prostate 3) in the development of OA. Our results demonstrated that STEAP3 was upregulated in OA cartilage tissues and contributes to the progression of the disease. To elucidate the mechanism, we employed transcriptomic and interaction proteomics analysis, and identified dysregulated genes and pathways associated with STEAP3 overexpression. Specifically, we found that STEAP3 interacted with Rab7A, a protein involved in intracellular trafficking and autophagy, and suppressed its activity. In addition, STEAP3 interacted with activated C kinase 1 (RACK1) and enhanced its activity. Furthermore, our data indicated that the suppression of Rab7A activity by STEAP3 promoted the activation of receptor tyrosine kinases (RTKs) and the promoting effects of RACK1 by STEAP3, both of which in turn activated the MAPK and JAK/STAT signaling pathways. In conclusion, our findings highlighted the role of STEAP3 in promoting OA progression. By inhibiting Rab7A activity and promoting RACK1 activity, STEAP3 enhanced inflammation through the activation of RTKs and subsequent activation of the MAPK and JAK/STAT signaling pathways. Targeting STEAP3 may provide a potential therapeutic strategy for the treatment of OA by modulating these interconnected pathways.

Effects of application of the clinical nursing pathway on surgical site wound infection and postoperative complication rates in patients with total knee arthroplasty: A meta-analysis

This study aimed to systematically evaluate the effects of clinical nursing on surgical site wound infections and postoperative complications in patients after undergoing total knee arthroplasty (TKA). Computerised searches of Embase, PubMed, Cochrane Library, China National Knowledge Infrastructure, VIP and Wanfang databases were conducted from inception to August 2023 to collect randomised controlled trials (RCTs) on patients with TKA who received clinical nursing pathway interventions. Literature screening, data extraction and quality assessment of the included studies were performed independently by two researchers. The meta-analysis was performed using Stata 17.0. A total of 14 RCTs with 1174 patients were included, including 587 patients each in the intervention and control groups. The meta-analysis results showed that the application of clinical nursing pathways to patients undergoing TKA significantly reduced surgical site wound infections (risk ratio [RR] = 0.28, 95% confidence interval [CI]: 0.15-0.54, p < 0.001) and postoperative complications (RR = 0.25, 95% CI: 0.17-0.37, p < 0.001). Therefore, clinical nursing pathway interventions in patients undergoing TKA should be promoted in clinical practice as they can effectively reduce the incidence of wound infection and postoperative complications.

Could Hyaluronic Acid Be Considered as a Senomorphic Agent in Knee Osteoarthritis? A Systematic Review

BACKGROUND

Knee osteoarthritis (KOA) is one of the most common causes of disability in elderly patients and tends to be a major burden on social and health care spending. Despite its severe socioeconomic impact, KOA remains, to date, an incurable disease. Due to its proper characteristics, KOA represents a favorable disease model for experimenting with senotherapeutics, a group of treatments that counteract the development of age-related disorders and chronic diseases. In recent years, the use of intra-articular hyaluronic acid (IAHA) in the treatment of diseases related to the wear and tear of the articular cartilage has been gaining popularity. Given its ability in joint lubrification, shock absorption, and cell signaling, our aim is to investigate, through the existing scientific literature, its potential role as a senomorphic agent, emphasizing its crucial function in KOA patients. Indeed, senomorphics are a particular group of senotherapeutics capable of modulating the functions and morphology of senescent cells to those of young cells or delaying the progression of young cells to senescent cells in tissues.

METHODS

A search in the scientific literature (PubMed, Cochrane Library, and Google Scholar) was carried out from 2019 to 2023, thus the last 5 years.

RESULTS

One hundred thirty-eight articles were found concerning the role of hyaluronic acid injections in KOA patients. In these studies, its therapeutic efficacy, its anti-inflammatory properties, and its low risk of side effects emerged.

CONCLUSION

IAHA injections are a valuable treatment option for KOA while they can provide pain relief, improve joint function, and slow the progression of joint degeneration. The inhibitory effect of HA on MMP13 and its action as a senomorphic agent suggests that it may have additional benefits beyond its lubricating and shock-absorbing properties. In order to clarify its mechanisms of action and to optimize its clinical use, further studies are definitely needed.

METTL3 Regulates the m6A Modification of NEK7 to Inhibit the Formation of Osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is a common degenerative joint disease. The occurrence of OA slowly destroys the soft tissue structure of the patient's joint. Severe cases could lead to disability. Current studies had shown that inhibition of chondrocytes pyroptosis could slow down the progression of OA. Our work aimed to explore the specific mechanisms and ways of regulating this process.

DESIGN

In this work, the level of N6-methyladenosine (m6A) in clinical tissues was detected by ribonucleic acid (RNA) m6A dot blot. qRT-PCR (quantitative real-time polymerase chain reaction) was used to detect the messenger RNA (mRNA) expression level of m6A modified enzyme in clinical tissues. MTT (3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromid) and flow cytometry were used to detect the effect of sh-METTL3 (methyltransferase like 3) and NIMA-related kinase 7 (NEK7) transfection on chondrocytes pyroptosis in OA. Western blot was used to detect the protein expression levels of pyroptosis-related proteins. ELISA (enzyme-linked immunosorbent assay) was used to measure the protein concentration of inflammatory cytokines. The SRAMP online database was used to predict the m6A site of NEK7. HE staining was used to assess the progression of OA in mice.

RESULTS

The level of m6A in clinical samples of OA patients was higher, and METTL3 was significantly higher expressed in clinical samples of OA patients. We provided evidence that low expression of METTL3 inhibited chondrocytes pyroptosis. In addition, Rescue experiments and in vivo experiments had shown that METTL3 in combination with NEK7 inhibited the progression of OA by promoting chondrocytes pyroptosis.

CONCLUSIONS

METTL3 regulates m6A modification of NEK7 and inhibits OA progression.

Efficacy of Transcutaneous 4.4 MHz Radiofrequency Diathermy versus Therapeutic Ultrasound for Pain Relief and Functional Recovery in Patients with Knee Osteoarthritis: A Randomized Controlled Study

Knee osteoarthritis (KOA) is a prevalent common cause of disability and pain among adults. Transcutaneous radiofrequency (RF) diathermy and therapeutic ultrasound (US) are commonly employed treatments for addressing musculoskeletal conditions. This study aims to evaluate and compare the clinical effectiveness of transcutaneous 4.4 MHz RF diathermy and therapeutic US therapy in individuals diagnosed with KOA. A total of 108 patients with KOA were randomly assigned to either the RF or US groups. Each participant underwent a series of 10 treatment sessions over four weeks and was evaluated at different time points. The assessments included physical evaluations, vital sign measurements, the Numeric Rating Scale (NRS) for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, the Lequesne index, gait analysis, the 36-Item Short Form Health Survey (SF-36), and analysis of adverse responses. Both groups showed significant differences in NRS, WOMAC scores, and Lequesne index compared to baseline values at both the 10th treatment session and the one-month follow-up assessment. However, no significant disparities were observed between the two groups at each assessment point. In the gait analysis, following the 10th treatment, the RF group showed significant changes in stride length and stride velocity compared to baseline. Four weeks after the completion of treatment, both groups exhibited significant alterations in stride length and stride velocity when compared to baseline measurements. However, regarding cadence, only the RF group exhibited a significant difference compared to baseline. The findings suggest that transcutaneous 4.4 MHz RF diathermy displays a comparable effectiveness to therapeutic US in reducing pain and enhancing functional capacity among individuals with KOA. Further research endeavors are warranted to advance the efficacy of noninvasive treatments for KOA.

Nanotechnology-Boosted Biomaterials for Osteoarthritis Treatment: Current Status and Future Perspectives

Osteoarthritis (OA) is a prevalent global health concern, posing a significant and increasing public health challenge worldwide. Recently, nanotechnology-boosted biomaterials have emerged as a highly promising strategy for OA therapy due to their exceptional physicochemical properties and capacity to regulate pathological processes. However, there is an urgent need for a deeper understanding of the potential therapeutic applications of these biomaterials in the clinical management of diseases, particularly in the treatment of OA. In this comprehensive review, we present an extensive discussion of the current status and future prospects concerning nanotechnology-boosted biomaterials for OA therapy. Initially, we discuss the pathophysiology of OA and the constraints associated with existing treatment modalities. Subsequently, various types of nanomaterials utilized for OA therapy, including nanoparticles, nanofibers, and nanocomposites, are thoroughly discussed and summarized, elucidating their respective advantages and challenges. Furthermore, we analyze recent preclinical and clinical studies that highlight the potential of nanotechnology-boosted biomaterials in OA therapy. Additionally, future research directions in this evolving field are highlighted. By establishing a link between the structural properties of nanotechnology-boosted biomaterials and their therapeutic functions in OA treatment, we aim to foster advances in designing sophisticated nanomaterials for OA, ultimately resulting in improved therapeutic efficacy of OA therapy through translation into clinical setting in the near future.

Exosomes derived from mesenchymal stem cells rescue cartilage injury in osteoarthritis through Ferroptosis by GOT1/CCR2 expression

Osteoarthritis is a prevalent joint disease that significantly affects the daily life of the elderly and is one of the primary causes of disability in this population. This study aims to evaluate the potential pro-inflammatory effects and molecular mechanism of Mesenchymal stem cells-derived exosomes (MSC-Exos) in Osteoarthritis. Bilateral ovariectomy was carried out to induce osteoporosis under anesthesia for the mice. MC3T3-E1 cells were induced for 14 days.HE staining, Safranin O staining and Biomechanical parameter analysis were used in this experiment. MSC-Exos improved osteoarthritis in a mouse model by reducing inflammation levels, preventing ferroptosis, and inducing expression of GOT1/CCR2 to regulate ferroptosis. MSC-Exos also promoted cell growth and osteogenic differentiation of bone cells in an in vitro model. Inhibition of GOT1 reduced the effects of MSC-Exos on cell growth and osteogenic differentiation in an osteoarthritis model. MSC-Exos induce Nrf2/HO-1 expression through the GOT1/CCR2 signaling pathway, resulting in the reduction of Ferroptosis. However, inhibition of Nrf2 reduces the effectiveness of MSC-Exos in treating Osteoarthritis.The results of this study suggest that the GOT1/CCR2/Nrf2/HO-1 signaling pathway plays a crucial role in MSC-Exos-mediated reduction of Ferroptosis in macrophages during Osteoarthritis. These findings may provide a potential therapeutic approach for Osteoarthritis and other orthopedic conditions.

Circ-NFKB1 sponges miR-203a-5p to regulate ERBB4 expression and promotes IL-1β induced chondrocytes apoptosis

BACKGROUND

Osteoarthritis (OA) is a chronic disease of the bones and joints that commonly affects middle-aged and elderly individuals, characterized by the degeneration of articular cartilage and inflammation of the joints. The molecular mechanisms of OA urgently need to be further examined. Our study intended to uncover circ-NFKB1/miR-203a-5p/ERBB4 axis in regulating interleukin-1β (IL-1β) induced chondrocytes apoptosis.

METHODS

GSE178724, GSE79258 and GSE169077 were downloaded from Gene Expression Omibus (GEO) database and differentially expressed circRNAs, miRNAs and mRNAs were obtained by R software. Annexin V assay was used to determine cell apoptosis rate. ELISA was further performed to identify the inflammation response. Dual-luciferase reporter gene assay was conducted to examine the combination among circ-NFKB1, miR-203a-5p and ERBB4.

RESULTS

Our research demonstrated that circ-NFKB1 and ERBB4 were significantly upregulated through bioinformatic analysis. MiR-203a-5p was significantly downregulated through bioinformatic analysis. Silencing of circ-NFKB1 notably inhibited the IL-1β induced chondrocytes apoptosis and upregulated ERBB4 expression. Through prediction on bioinformatics analysis, miR-203a-5p was the target binding circ-NFKB1, and ERBB4 was the potential target of miR-203a-5p. Subsequently, these changes induced by the silencing of circ-NFKB1 were reversed upon addition of pcDNA/ERBB4.

CONCLUSIONS

Silencing circ-NFKB1 could sponge miR-203a-5p to regulate ERBB4 expression and alleviate OA progression.

Crosstalk between ferroptosis and chondrocytes in osteoarthritis: a systematic review of in vivo and in vitro studies

Purpose

Recent scientific reports have revealed a close association between ferroptosis and the occurrence and development of osteoarthritis (OA). Nevertheless, the precise mechanisms by which ferroptosis influences OA and how to hobble OA progression by inhibiting chondrocyte ferroptosis have not yet been fully elucidated. This study aims to conduct a comprehensive systematic review (SR) to address these gaps.

Methods

Following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020, we conducted a comprehensive search of the Embase, Ovid, ProQuest, PubMed, Scopus, the Cochrane Library, and Web of Science databases to identify relevant studies that investigate the association between ferroptosis and chondrocytes in OA. Our search included studies published from the inception of these databases until January 31st, 2023. Only studies that met the predetermined quality criteria were included in this SR.

Results

In this comprehensive SR, a total of 21 studies that met the specified criteria were considered suitable and included in the current updated synthesis. The mechanisms underlying chondrocyte ferroptosis and its association with OA progression involve various biological phenomena, including mitochondrial dysfunction, dysregulated iron metabolism, oxidative stress, and crucial signaling pathways.

Conclusion

Ferroptosis in chondrocytes has opened an entirely new chapter for the investigation of OA, and targeted regulation of it is springing up as an attractive and promising therapeutic tactic for OA.

Systematic review registration

https://inplasy.com/inplasy-2023-3-0044/, identifier INPLASY202330044.

Plasma lipids, alcohol intake frequency and risk of Osteoarthritis: a Mendelian randomization study

BACKGROUD

Plasma lipids and alcohol intake frequency have been reported to be associated with the risk of osteoarthritis (OA). However, it remains inconclusive whether plasma lipids and alcohol intake frequency play a role in the development of OA.

METHODS

The study employed a comprehensive genome-wide association database to identify independent genetic loci strongly linked to plasma lipids and alcohol intake frequency, which were used as instrumental variables. The causal association between plasma lipids, alcohol intake frequency, and the risk of OA was then analyzed using two-sample Mendelian randomization methods such as inverse variance weighted (IVW), MR-Egger regression, and weighted median estimator (WME), with odds ratios (ORs) as the evaluation criteria.

RESULTS

A total of 392 SNPs were included as instrumental variables in this study, including 32 for total cholesterol (TC), 39 for triglycerides (TG), 170 for high-density lipoproteins (HDL), 60 for low-density lipoproteins (LDL), and 91 for alcohol intake frequency. Using the above two-sample Mendelian Randomization method to derive the causal association between exposure and outcome, with the IVW method as the primary analysis method and other MR analysis methods complementing IVW. The results of this study showed that four exposure factors were causally associated with the risk of OA. TC obtained a statistically significant result for IVW (OR = 1.207, 95% CI: 1.018-1.431, P = 0.031); TG obtained a statistically significant result for Simple mode (OR = 1.855, 95% CI: 1.107-3.109, P = 0.024); LDL obtained three statistically significant results for IVW, WME and Weighted mode (IVW: OR = 1.363, 95% CI: 1.043-1.781, P = 0.023; WME: OR = 1.583, 95% CI: 1.088-2.303, P = 0.016; Weighted mode: OR = 1.521, 95% CI: 1.062-2.178, P = 0.026). Three statistically significant results were obtained for alcohol intake frequency with IVW, WME and Weighted mode (IVW: OR = 1.326, 95% CI: 1.047-1.678, P = 0.019; WME: OR = 1.477, 95% CI: 1.059-2.061, P = 0.022; Weighted mode: OR = 1.641, 95% CI: 1.060-2.541, P = 0.029). TC, TG, LDL, and alcohol intake frequency were all considered as risk factors for OA. The Cochran Q test for the IVW and MR-Egger methods indicated intergenic heterogeneity in the SNPs contained in TG, HDL, LDL, and alcohol intake frequency, and the test for pleiotropy indicated a weak likelihood of pleiotropy in all causal analyses.

CONCLUSIONS

The results of two-sample Mendelian randomization analysis showed that TC, TG, LDL, and alcohol intake frequency were risk factors for OA, and the risk of OA increased with their rise.

Biomaterial-based scaffolds in promotion of cartilage regeneration: Recent advances and emerging applications

Osteoarthritis (OA) poses a significant burden for countless individuals, inflicting relentless pain and impairing their quality of life. Although traditional treatments for OA focus on pain management and surgical interventions, they often fall short of addressing the underlying cause of the disease. Fortunately, emerging biomaterial-based scaffolds offer hope for OA therapy, providing immense promise for cartilage regeneration in OA. These innovative scaffolds are ingeniously designed to provide support and mimic the intricate structure of the natural extracellular matrix, thus stimulating the regeneration of damaged cartilage. In this comprehensive review, we summarize and discuss current landscape of biomaterial-based scaffolds for cartilage regeneration in OA. Furthermore, we delve into the diverse range of biomaterials employed in their construction and explore the cutting-edge techniques utilized in their fabrication. By examining both preclinical and clinical studies, we aim to illuminate the remarkable versatility and untapped potential of biomaterial-based scaffolds in the context of OA.

Thetranslational potential of this article

By thoroughly examining the current state of research and clinical studies, this review provides valuable insights that bridge the gap between scientific knowledge and practical application. This knowledge is crucial for clinicians and researchers who strive to develop innovative treatments that go beyond symptom management and directly target the underlying cause of OA. Through the comprehensive analysis and multidisciplinary approach, the review paves the way for the translation of scientific knowledge into practical applications, ultimately improving the lives of individuals suffering from OA and shaping the future of orthopedic medicine.

Leukocyte-Rich Platelet-Rich Plasma Is Predominantly Anti-inflammatory Compared With Leukocyte-Poor Platelet-Rich Plasma in Patients With Mild-Moderate Knee Osteoarthritis: A Prospective, Descriptive Laboratory Study

BACKGROUND

Platelet-rich plasma (PRP) has been used extensively in clinical practice to treat patients with symptomatic knee osteoarthritis (OA). Leukocyte-poor PRP (LP-PRP) has been clinically preferred over leukocyte-rich PRP (LR-PRP); however, it is unclear which cytokine mediators of pain and inflammation are present in LR-PRP and LP-PRP from patients with mild to moderate knee OA in order to rationalize a specific formulation.

HYPOTHESIS

LP-PRP would be predominantly anti-inflammatory and have reduced nociceptive pain mediators compared with LR-PRP from the same individual with mild to moderate knee OA.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 24 unique samples of PRP were prepared in order to assess 48 samples of LR-PRP and LP-PRP taken from 12 patients (6 male and 6 female) with symptomatic knee OA of Kellgren-Lawrence grade 2 to 3. Patients underwent blood collection for LR-PRP and LP-PRP preparation through a double-spin protocol to obtain baseline whole blood, platelet concentration, and white blood cell subtypes. LR-PRP and LP-PRP from the same patient were produced at the same time and underwent a comprehensive panel through Luminex (multicytokine profiling) to assess key mediators of inflammation: interleukin 1 receptor antagonist (IL-1Ra), interleukin 4, 6, 8, and 10 (IL-4, IL-6, IL-8, and IL-10), IL-1β, tissue necrosis factor α (TNF-α), and matrix metalloproteinase 9 (MMP-9). To assess mediators of nociceptive pain, nerve growth factor (NGF) and tartrate resistant acid phosphatase 5 (TRAP5) were also assessed.

RESULTS

LR-PRP from patients with mild to moderate knee OA expressed significantly more IL-1Ra, IL-4, IL-8, and MMP-9 compared with LP-PRP formulations from the same patients. No significant differences were found between LR-PRP and LP-PRP in mediators of nociceptive pain-namely, NGF and TRAP5. Other mediators including TNF-α, IL-1β, IL-6, and IL-10 were also found to have no significant expression differences between LR-PRP and LP-PRP.

CONCLUSION

LR-PRP expressed significantly more IL-1Ra, IL-4, and IL-8, suggesting that LR-PRP may be more anti-inflammatory than LP-PRP. MMP-9 was expressed in higher concentrations in LR-PRP, suggesting that LR-PRP may be more chondrotoxic than LP-PRP.

CLINICAL RELEVANCE

LR-PRP was found to have a robust expression of anti-inflammatory mediators compared with LP-PRP and may be beneficial to patients with long-term knee OA where chronic low-grade inflammation is present. Mechanistic clinical trials are needed to elucidate the key mediators in both LR-PRP and LP-PRP to assess their effect on long-term progression of knee OA.

Du Huo Ji Sheng Tang inhibits Notch1 signaling and subsequent NLRP3 activation to alleviate cartilage degradation in KOA mice

BACKGROUND

Knee osteoarthritis (KOA) has a complex pathological mechanism and is difficult to cure. The traditional medicine Du Huo Ji Sheng Tang (DHJST) has been used for the treatment of KOA for more than one thousand years, but its mechanism for treating KOA has not been revealed. In our previous study, we confirmed that DHJST inhibited the activation of NLRP3 signaling in rats and humans. In the current study, we aimed to determine how DHJST inhibits NLRP3 to alleviate knee cartilage damage.

METHODS

Mice were injected with NLRP3 shRNA or Notch1-overexpressing adenovirus into the tail vein to construct systemic NLRP3 low-expressing or Notch1 high-expressing mice. Mice were injected with papain into the knee joint to replicate the KOA model. DHJST was used to treat KOA model mice with different backgrounds. The thickness of the right paw was measured to evaluate toe swelling. The pathohistological changes and the levels of IL-1β, MMP2, NLRP3, Notch1, collagen 2, collagen 4, HES1, HEY1, and Caspase3 were detected by HE staining, ELISA, immunohistochemical staining, western blotting, or real-time qPCR.

RESULTS

DHJST reduced tissue swelling and serum and knee cartilage IL-1β levels, inhibited cartilage MMP2 expression, increased collagen 2 and collagen 4 levels, decreased Notch1 and NLRP3 positive expression rates in cartilage, and decreased HES1 and HEY1 mRNA levels in KOA model mice. In addition, NLRP3 interference decreased cartilage MMP2 expression and increased collagen 2 and collagen 4 levels without affecting the expression levels of notch1, HES1 and HEY1 mRNA levels in the synovium of KOA mice. In KOA mice with NLRP interference, DHJST further reduced tissue swelling and knee cartilage damage in mice. Finally, Notch1-overexpressing mice not only showed more severe tissue swelling and knee cartilage degradation but also abolished the therapeutic effect of DHJST on KOA mice. Importantly, the inhibitory effects of DHJST on the mRNA expression of NLRP3, Caspase3 and IL-1β in the knee joint of KOA mice were completely limited after Notch1 overexpression.

CONCLUSION

DHJST significantly reduced inflammation and cartilage degradation in KOA mice by inhibiting Ntoch1 signaling and its subsequent NLRP3 activation in the knee joint.

Automated Prediction of Osteoarthritis Level in Human Osteochondral Tissue Using Histopathological Images

Osteoarthritis (OA) is the most common arthritis and the leading cause of lower extremity disability in older adults. Understanding OA progression is important in the development of patient-specific therapeutic techniques at the early stage of OA rather than at the end stage. Histopathology scoring systems are usually used to evaluate OA progress and the mechanisms involved in the development of OA. This study aims to classify the histopathological images of cartilage specimens automatically, using artificial intelligence algorithms. Hematoxylin and eosin (HE)- and safranin O and fast green (SafO)-stained images of human cartilage specimens were divided into early, mild, moderate, and severe OA. Five pre-trained convolutional networks (DarkNet-19, MobileNet, ResNet-101, NasNet) were utilized to extract the twenty features from the last fully connected layers for both scenarios of SafO and HE. Principal component analysis (PCA) and ant lion optimization (ALO) were utilized to obtain the best-weighted features. The support vector machine classifier was trained and tested based on the selected descriptors to achieve the highest accuracies of 98.04% and 97.03% in HE and SafO, respectively. Using the ALO algorithm, the F1 scores were 0.97, 0.991, 1, and 1 for the HE images and 1, 0.991, 0.97, and 1 for the SafO images for the early, mild, moderate, and severe classes, respectively. This algorithm may be a useful tool for researchers to evaluate the histopathological images of OA without the need for experts in histopathology scoring systems or the need to train new experts. Incorporating automated deep features could help to improve the characterization and understanding of OA progression and development.

Fibroblast growth factor 10 delays the progression of osteoarthritis by attenuating synovial fibrosis via inhibition of IL-6/JAK2/STAT3 signaling in vivo and in vitro

Synovial fibrosis is a driver in the progression of osteoarthritis (OA). Fibroblast growth factor 10 (FGF10) has prominent anti-fibrotic effects in many diseases. Thus, we explored the anti-fibrosis effects of FGF10 in OA synovial tissue. In vitro, fibroblast-like synoviocytes (FLSs) were isolated from OA synovial tissue and stimulated with TGF-β to establish a cell model of fibrosis. After treatment with FGF10, we assessed the effects on FLS proliferation and migration using CCK-8, EdU, and scratch assays, and collagen production was observed using Sirius Red Stain. The JAK2/STAT3 pathway and expression of fibrotic markers were evaluated through western blotting (WB) and immunofluorescence (IF). In vivo, we treated mice with OA induced by surgical destabilization of the medial meniscus (DMM) with FGF10 and assessed the anti-OA effect using histological and immunohistochemical (IHC) staining of MMP13, and fibrosis was evaluated using HE and Masson's trichrome staining. The expression of IL-6/JAK2/STAT3 pathway components was determined using ELISA, WB, IHC, and IF. In vitro, FGF10 inhibited TGF-β-induced FLS proliferation and migration, decreased collagen deposition, and improved synovial fibrosis. Moreover, FGF10 mitigated synovial fibrosis and improved the symptoms of OA in DMM-induced OA mice. Overall, FGF10 had promising anti-fibrotic effects on FLSs and improved OA symptoms in mice. The IL-6/STAT3/JAK2 pathway plays key roles in the anti-fibrosis effect of FGF10. This study is the first to demonstrate that FGF10 inhibited synovial fibrosis and attenuated the progression of OA by inhibiting the IL-6/JAK2/STAT3 pathway.

DHA attenuates cartilage degeneration by mediating apoptosis and autophagy in human chondrocytes and rat models of osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease that usually occurs in the elderly, and docosahexaenoic acid (DHA) plays a therapeutic role in cardiovascular disease, diabetes, and rheumatoid arthritis (RA) with its anti-inflammatory and antioxidant effects. The objective of this study is to investigate the effect and mechanism of DHA on hypertrophic differentiation and senescence of OA chondrocytes to provide a theoretical basis for the effect of OA clinical treatment. A human OA chondrocyte model was established by IL-1β, and a rat model of OA was established by anterior cruciate ligament (ACL) transection and medial meniscectomy. The result showed DHA promoted chondrocyte proliferation and reduced apoptosis. Transmission electron microscopy (TEM) analysis showed that there were more autophagosomes in the cytoplasm under the treatment of DHA. Compared to the OA group, samples from the OA + DHA group showed thickened cartilage, reduced degeneration, and an increased rate of collagen II-positive cells, while the Mankin score was significantly lower. In addition, DHA decreased the expression of phosphorylated mammalian target of rapamycin (p-mTOR) and the ratio of light chain 3-I/II (LC3-I/II) and increased the expression of Beclin-1 and Bcl-2 measured by western blot analysis. Therefore, DHA promotes chondrocyte proliferation, reduces apoptosis, and increases autophagy in OA chondrocytes, a process that is accomplished by inhibiting the expression of mTOR, c-Jun N-terminal kinase (JNK), and p38 signaling pathways, providing new perspectives and bootstrap points for the prevention and treatment of OA.