Quercetin alleviates rat osteoarthritis by inhibiting inflammation and apoptosis of chondrocytes, modulating synovial macrophages polarization to M2 macrophages

Serum and synovial fluid levels of CSF-1 and in knee osteoarthritis and its clinical significance

OBJECTIVE

To investigate the serum and synovial fluid levels of CSF-1 in patients with knee osteoarthritis (KOA) and evaluate its clinical significance.

METHODS

We selected 143 patients with KOA who received treatment at our hospital from June 2021 to August 2024. Enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of CSF-1, IL-6, IL-1β, CRP, and HIF-1α in the serum of all study subjects, as well as the levels of these markers in the synovial fluid of all KOA patients. The Kellgren and Lawrence (KL) grading system was used to assess the radiographic severity of all KOA patients. Additionally, we also collected the Visual Analog Scale (VAS) scores and the Western Ontario McMaster University Osteoarthritis Index (WOMAC). Western blot (WB) was used to detect the expression levels of inflammatory factors in macrophages after CSF-1 stimulation.

RESULTS

Compared to healthy volunteers, KOA patients exhibited significantly elevated levels of serum CSF-1, IL-6, IL-1β, CRP, and HIF-1α (p < 0.05). The advanced group of KOA patients had significantly higher levels of serum and synovial fluid CSF-1 compared to the early group. Synovial fluid CSF-1 levels were associated with inflammation and disease severity in KOA patients. CSF-1 stimulation significantly increased the expression of CSF-1R, IL-6, TNF-α, IL-1β, HIF-1α, and MMP-3 in macrophages. Moreover, synovial fluid and serum CSF-1, synovial fluid HIF-1α, and synovial fluid IL-6 were identified as risk factors for advanced KOA.

CONCLUSION

Our findings indicated that the serum and synovial fluid levels of CSF-1 were significantly increased in KOA patients, even higher in patients with KL grade 3-4. Moreover, CSF-1 was identified as a risk factor associated with advanced stage KOA.

Blocking the LRH-1/LCN2 axis by ML-180, an LRH-1 inverse agonist, ameliorates osteoarthritis via inhibiting the MAPK pathway

Osteoarthritis (OA) is a chronic and degenerative disease marked by inflammation and extracellular matrix (ECM) degeneration, contributing to synovial inflammation and cartilage destruction. Accumulating evidence has demonstrated that Liver receptor homolog-1 (LRH-1), an orphan nuclear receptor, mediates inflammatory response. However, there is a lack of evidence regarding the regulatory role of LRH-1 in OA pathogenesis. In this study, we confirmed that chondrocytes expressed LRH-1, and observed its upregulation in both IL-1β-treated chondrocytes and cartilage of destabilization of the medial meniscus (DMM)-operated mice. Overexpression of LRH-1 promoted inflammation and dysregulation of ECM metabolism in IL-1β-induced chondrocytes, reversed by inhibition of LRH-1 with ML-180 or gene silencing to protect chondrocytes. Moreover, ML-180 treatment in vivo improved the deteriorated OA phenotypes in mouse models, alleviating OA development. Mechanistically, RNA sequencing revealed that Lipocalin-2 (LCN2), a member of the lipocalin family associated with inflammation, is located downstream of LRH-1 and is positively regulated by it. Furthermore, the LRH-1/LCN2 axis mainly relied on activating the mitogen-activated protein kinase (MAPK) signaling pathway to promote inflammation and dysregulation of ECM metabolism, ultimately damaging chondrocytes. Our findings demonstrate that LRH-1 positively modulates LCN2,activating the MAPK pathway, indicating that targeting the LRH-1/LCN2/MAPK axis may represent a potential therapeutic strategy for OA.

New Advances in Periodontal Functional Materials Based on Antibacterial, Anti-Inflammatory, and Tissue Regeneration Strategies

With the global population aging, awareness of oral health is rising. Periodontitis, a widespread bacterial infectious disease, is gaining attention. Current novel biomaterials address key clinical issues like bacterial infection, gum inflammation, tooth loosening, and loss, focusing on antibacterial, anti-inflammatory, and tissue regeneration properties. However, strategies that integrate the advantages of these biomaterials to achieve synergistic therapeutic effects by clearing oral biofilms, inhibiting inflammation activation, and restoring periodontal soft and hard tissue functions remain very limited. Recent studies highlight the link between periodontitis and systemic diseases, underscoring the complexity of the periodontal disease. There is an urgent need to find comprehensive treatment plans that address clinical requirements. Whether by integrating new biomaterials to enhance existing periodontal treatments or by developing novel approaches to replace traditional therapies, these efforts will drive advancements in periodontitis treatment. Therefore, this review compares novel biomaterials with traditional treatments. It highlights the design concepts and mechanisms of these functional materials, focusing on their antibacterial, anti-inflammatory, and tissue regeneration properties, and discusses the importance of developing comprehensive treatment strategies. This review aims to provide guidance for emerging periodontitis research and to promote the development of precise and efficient treatment strategies.

Primed IFN-γ-Umbilical Cord Stem Cells Ameliorate Temporomandibular Joint Osteoarthritis

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disorder affecting the temporomandibular joint (TMJ), marked by persistent inflammation and structural damage to the joint. Only symptomatic treatment is available for managing TMJOA. Human umbilical cord mesenchymal stem cells (hUC-MSCs) show potential for treating TMJOA via their immune-modulating actions in the disease area. In addition, stimulation of inflammatory cytokines such as interferon-gamma in hUC-MSCs improves the therapeutic activity of naïve stem cells. Emerging evidence indicates that macrophages play significant roles in regulating joint inflammation through diverse secreted mediators in the pathogenesis of TMJOA. This study was conducted to evaluate the effects of inflammatory cytokine-stimulated hUC-MSCs in repairing TMJOA-induced cartilage lesions and the role of macrophages in the disease. Our in vitro data showed that stimulated hUC-MSCs induce M2 polarization of macrophages and enhance the expression of anti-inflammatory molecules. These effects were subsequently validated in vivo. In a rat model of TMJOA, stimulated hUC-MSCs ameliorated inflammation and increased M2 macrophages ratio. Our results indicate that hUC-MSCs stimulated by inflammatory cytokines modulate the activation of M2 macrophages, thereby shifting the local osteoarthritis microenvironment toward a prochondrogenic state and facilitating cartilage repair in inflammatory conditions. Stimulating hUC-MSCs with inflammatory cytokines could potentially offer an effective therapeutic approach for TMJOA, with macrophages playing a pivotal role in immune modulation.

Exploring the mechanisms of PANoptosis in osteoarthritis and the therapeutic potential of andrographolide through bioinformatics and single-cell analysis

BACKGROUND

Osteoarthritis (OA) is a degenerative joint disease marked by the breakdown of cartilage, where apoptosis plays a key role. Although apoptosis-related genes in OA have been studied, a detailed analysis of PANoptosis-related genes and the search for therapeutic drugs remains limited.

METHODS

We performed a bioinformatics analysis combined with single-cell RNA sequencing to examine PANoptosis-related gene expression in OA cartilage. Key PANoptosis genes and critical cell populations involved in OA progression were identified. Drug prediction led to the selection of Andrographolide (AG), whose effects were validated through molecular docking, Western blotting, and qRT-PCR in chondrocyte models.

RESULTS

Several PANoptosis-related genes, including CASP8, TLR3, CASP1, and IL18, were significantly differentially expressed in OA. These genes are linked to processes such as apoptosis, pyroptosis, and the inflammasome complex. Pathway analysis revealed necroptosis, Toll-like receptor, and apoptosis signaling pathways as important in OA pathology. Single-cell analysis identified HomC, EC, and preHTC as key cell populations. AG was predicted to regulate PANoptosis genes, which was confirmed experimentally, demonstrating AG's potential to modulate key genes involved in cartilage degeneration.

CONCLUSION

This study highlights PANoptosis-related genes in OA and identifies Andrographolide as a promising therapeutic drug, offering new insights into OA treatment strategies.

Interplay between lipid dysregulation and ferroptosis in chondrocytes and the targeted therapy effect of metformin on osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a devastating whole-joint disease affecting a large population worldwide; the role of lipid dysregulation in OA and mechanisms underlying targeted therapy effect of lipid-lowering metformin on OA remains poorly defined.

OBJECTIVES

To investigate the effects of lipid dysregulation on OA progression and to explore lipid dysregulation-targeting OA treatment of metformin.

METHODS

RNA-Seq data, biochemical, and histochemical assays in human and murine OA cartilage as well as primary chondrocytes were utilized to determine lipid dysregulation. Effects of metformin, a potent lipid-lowering medication, on ACSL4 expression and chondrocyte metabolism were determined. Further molecular experiments, including RT-qPCR, western blotting, flow cytometry, and immunofluorescence staining, were performed to investigate underlying mechanisms. Mice with intra-articular injection of metformin were utilized to determine the effects on ACLT-induced OA progression.

RESULTS

ACSL4 and 4-HNE expressions were elevated in human and ACLT-induced mouse OA cartilage and IL-1β-treated chondrocytes (P < 0.05). Ferrostatin-1 largely rescued IL-1β-induced MDA, lipid peroxidation, and ferroptotic mitochondrial morphology (P < 0.05). Metformin decreased the levels of OA-related genes (P < 0.05) and increased the levels of p-AMPK and p-ACC in IL-1β-treated chondrocytes. Intra-articular injection of metformin alleviated ACLT-induced OA lesions in mice, and reverted the percentage of chondrocytes positive for MMP13, Col2a1, ACSL4 and 4-HNE in ACLT mice (P < 0.05). Ferroptotic chondrocytes promoted the recruitment and chemotaxis of RAW264.7 cells via CCL2, which was blocked by metformin in vitro (P < 0.05).

CONCLUSION

We establish a critical role of polyunsaturated fatty acids metabolic process in OA cartilage degradation and define metformin as a potential OA treatment. Metformin reshapes lipid availability and ameliorates chondrocyte ferroptosis sensitivity via the AMPK/ACC pathway. In the future, gene-edited animals and extensive omics technologies will be utilized to reveal detailed lipids' involvement in cartilage lesions.

A MnO2 nanosheets doping double crosslinked hydrogel for cartilage defect repair through alleviating inflammation and guiding chondrogenic differentiation

The inflammatory microenvironment and inferior chondrogenesis are major symptoms after cartilage defect. Although various modifications strategies associated with hydrogels exhibit remarkable capacity of pro-cartilage regeneration, the adverse effect by prolonging inflammation is still formidable to hamper potential biomedical applications of different hydrogel implants. Herein, inspired by the repair microenvironment of articular cartilage defects, an injectable, immunomodulatory, and chondrogenic L-MNS-CMDA hydrogel is prepared through grafting vinyl and catechol groups to chitosan macromolecules using amide reaction, then further loading MnO2 nanosheets (MNS). The double crosslinking of photopolymerization and catechol oxidative polymerization endows L-MNS-CMDA hydrogel with preferable mechanical property, affording a suitable mechanical support for cartilage defect repair. Additionally, the robust tissue adhesion capability stemming from catechol groups guarantees the long-term retention of the hydrogel in the defect site. Meanwhile, L-MNS-CMDA hydrogel decomposes exogenous and intracellular H2O2 into O2 and H2O, to effectively alleviate cellular oxidative stress caused by long-term hypoxia. Under the synergies of catechol groups and MNS, L-MNS-CMDA hydrogel not only inhibits macrophages polarizing into M1 phenotype, but encourages them turn into M2 phenotype, thereby, reconstructing an immunization friendly microenvironment to ultimately enhance cartilage regeneration. Predictably, the hydrogel markedly induces rat bone marrow mesenchymal stem cells differentiating into chondrocytes by expressing abundant glycosaminoglycan and type II collagen. A cartilage defect model of rat knee joint indicates that L-MNS-CMDA hydrogel visually regulate the early inflammatory response of post-implantation, and facilitate cartilage regeneration and recovery of joint function after 12 weeks of post-implantation. All in all, this multifunctional L-MNS-CMDA hydrogel exhibits superior immunomodulatory and chondrogenic properties, holding immense clinical potential in the treatment of cartilage defects.

Recent development of mitochondrial metabolism and dysfunction in osteoarthritis

Osteoarthritis is a degenerative joint disorder characterized by cartilage degradation, synovial inflammation, and altered subchondral bone structure. Recent insights have identified mitochondrial dysfunction as a pivotal factor in OA pathogenesis, contributing to chondrocyte apoptosis, oxidative stress, and extracellular matrix degradation. Disruptions in mitochondrial dynamics, including impaired biogenesis, mitophagy, and metabolic shifts from oxidative phosphorylation to glycolysis, exacerbate cartilage damage by promoting the production of reactive oxygen species and matrix-degrading enzymes such as ADAMTS and MMPs. This review explores the molecular mechanisms underlying mitochondrial dysfunction in OA, emphasizing its role in cartilage homeostasis and inflammation. Furthermore, it highlights emerging therapeutic strategies targeting mitochondrial pathways, including antioxidants, mitophagy enhancers, and metabolic modulators, as potential interventions to mitigate disease progression, which offer promising avenues for advancing personalized and disease-modifying treatments in OA.

Blocking the CCL5/CCL7-CCR1 axis regulates macrophage polarization through NF-κB pathway to alleviate the progression of osteoarthritis

OBJECTIVE

To study the effect of CCR1 and its ligands on macrophage polarization and evaluate its effect on chondrocytes in relieving the progression of osteoarthritis.

METHODS

RAW cells were polarized to M1/M2 subtype, and then different concentrations of BX471 were added to selectively inhibit CCR1. The polarization of the cells was detected by RT-qPCR, immunofluorescence and flow cytometry. CCL5 and CCL7 genes were silenced by SiRNA and its role in macrophage polarization was analyzed. Macrophage conditioned medium was further used to stimulate chondrocytes. Histological observation was carried out on models of medial meniscus (DMM) with or without BX471 treatment.

RESULTS

We found that blocking of CCR1 and silencing of its ligand, CCL5 and CCL7, reduced the polarization of M1 macrophages. In terms of mechanism, we found that blocking CCR1 could reduce the activation of NF-κB pathway and inhibit the phosphorylation of IKK, IκBα and P65. In addition, blocking of CCR1 could also reduce cartilage injury induced by macrophage conditioned medium. In vivo, blocking of CCR1 reduced the infiltration and accumulation of M1 macrophages and alleviated articular cartilage injury.

CONCLUSION

CCL5/CCL7-CCR1 axis was involved in macrophage polarization, and blocking it could reduce synovitis and alleviate the process of OA.

Skatole Alleviates Osteoarthritis by Reprogramming Macrophage Polarization and Protecting Chondrocytes

Osteoarthritis (OA) is the most prevalent joint disease, yet effective disease-modifying OA drugs (DMOADs) remain elusive. Targeting macrophage polarization has emerged as a promising avenue for OA treatment. This study identified skatole through high-throughput screening as an efficient modulator of macrophage polarization. In vivo experiments demonstrated that skatole administration markedly reduced synovitis and cartilage damage in both destabilization of medial meniscus (DMM)-induced OA mice and monosodium iodoacetate (MIA)-induced OA rats. Mechanistically, skatole activated signal transducer and activator of transcription 6 (Stat6) signaling, promoting M2 macrophage polarization, while inhibiting nuclear factor-κB (NFκB) and mitogen-activated protein kinase (MAPK) signaling pathways to suppress M1 polarization. RNA-sequencing analysis, targeted metabolomics, and mitochondrial stress tests further revealed that skatole treatment shifted macrophages toward oxidative phosphorylation for energy production. Additionally, it up-regulated genes associated with glutathione metabolism and reactive oxygen species (ROS) pathways, reducing intracellular ROS production. The CUT&Tag assay results indicated that the downstream transcription factor p65 of NFκB can directly bind to gene loci related to inflammation, oxidative phosphorylation, and glutathione metabolism, thereby modulating gene expression. This regulatory process is inhibited by skatole. At the chondrocyte level, conditional medium from skatole-treated M1 macrophages balanced anabolism and catabolism in mouse chondrocytes and inhibited apoptosis. In IL1β-treated chondrocytes, skatole suppressed inflammation and catabolism without affecting apoptosis or anabolism. Overall, skatole maintains immune microenvironment homeostasis by modulating macrophage polarization in joints and preserves cartilage function by balancing chondrocyte anabolism and catabolism, effectively alleviating OA. These findings suggest skatole's potential as a DMOAD.

Mesenchymal Stem Cells Injection Is More Effective Than Hyaluronic Acid Injection in the Treatment of Knee Osteoarthritis With Similar Safety: A Systematic Review and Meta-analysis

PURPOSE

To evaluate the efficacy and safety of intra-articular injection of mesenchymal stem cells (MSCs) versus hyaluronic acid (HA) in the treatment of knee osteoarthritis (KOA).

METHODS

Eligible randomized controlled trials (RCTs) were identified through a search of PubMed, Embase, the Cochrane Library, Web of Science, SinoMed, and CNKI databases from inception to March 2024. For meta-analysis, data on clinical outcomes were measured using visual analog scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and data on cartilage repair were measured using the Whole-Organ Magnetic Resonance Imaging Score (WORMS); data on safety were evaluated by the incidence of adverse events. Two researchers independently read the included literature, extracted data and evaluated the quality, used the Cochrane risk bias assessment tool for bias risk assessment, and used RevMan5.3 software for meta-analysis.

RESULTS

Ten RCTs involving 818 patients with KOA ranging from I to Ⅲ on the Kellgren-Lawrence grading scale were included in this meta-analysis. Meta-analysis results showed that at 12 months, the WOMAC total score (mean difference [MD] = -10.22, 95% confidence interval [CI]: -14.86 to -5.59, P < .0001, Z = 4.32), VAS score (MD = -1.31, 95% CI: -1.90 to -0.73, P < .0001, Z = 4.40); and WORMS score (MD = -26.01, 95% CI: -31.88 to -20.14, P < .001, Z = 8.69) of the MSCs group all decreased significantly (P < .05) compared with the HA control group and reached the minimal clinically important differences. Furthermore, there was no significant difference in the incidence of adverse events (relative risk = 1.54, 95% CI: 0.85-2.79, P = .16, I2 = 0) between the 2 groups (P > .05).

CONCLUSIONS

In terms of efficacy, the clinical effects of intra-articular injection therapy using MSCs for KOA are superior to those of HA, and the cartilage repair effect of MSCs is also markedly better than that of HA. Although the clinical effects varied across time periods, the functional score reached the minimum clinically significant difference at both 6 and 12 months. In terms of safety, adverse reactions mainly manifest as joint pain, swelling, and joint effusion. Both intra-articular injections of MSCs and HA did not result in severe adverse reactions, indicating that MSCs and HA have similar safety profiles.

LEVEL OF EVIDENCE

Level I, meta-analysis of Level I studies.

NEK2 promotes the progression of osteoarthritis by stabilizing ATF2 through phosphorylation at Ser-112 and inhibiting autophagy

NEK2 (NIMA-related kinase 2) has recently gained attention for its potential role in osteoarthritis (OA) chondrocytes, however, its specific involvement remains unclear. This study aimed to investigate the role of NEK2 in OA progression and the underlying molecular mechanisms. Primary mouse knee chondrocytes were stimulated with IL-1β to establish an in vitro OA model, followed by the knockdown of NEK2 or ATF2. The results indicated that silencing NEK2 or ATF2 impeded the IL-1β-induced decrease in cell proliferation and increase in inflammation, extracellular matrix (ECM) degradation, and apoptosis in chondrocytes. NEK2 or ATF2 knockdown restored IL-1β-induced autophagy defects. Mechanistically, NEK2 interacts with ATF2 to reduce its ubiquitylation level and enhance its stability by phosphorylating ATF2 at Ser-112. Consistently, ATF2 overexpression reversed the protective effect of NEK2 silencing on IL-1β-induced autophagy defects and chondrocyte injury. Additionally, a mouse OA model was established using medial meniscus destabilization (DMM) surgery, and NEK2 was knocked down by intra-articular injection of an adenovirus-mediated NEK2 interference vector. Downregulation of NEK2 mitigated cartilage degradation andautophagy defects ina mouse OA model. In conclusion, NEK2 promoted OA progression by enhancing ATF2 stability by phosphorylating it at Ser-112.

Senolytic therapy combining Dasatinib and Quercetin restores the chondrogenic phenotype of human osteoarthritic chondrocytes by the release of pro-anabolic mediators

Cellular senescence is associated with various age-related disorders and is assumed to play a major role in the pathogenesis of osteoarthritis (OA). Based on this, we tested a senolytic combination therapy using Dasatinib (D) and Quercetin (Q) on aged isolated human articular chondrocytes (hACs), as well as in OA-affected cartilage tissue (OARSI grade 1-2). Stimulation with D + Q selectively eliminated senescent cells in both, cartilage explants and isolated hAC. Furthermore, the therapy significantly promoted chondroanabolism, as demonstrated by increased gene expression levels of COL2A1, ACAN, and SOX9, as well as elevated collagen type II and glycosaminoglycan biosynthesis. Additionally, D + Q treatment significantly reduced the release of SASP factors (IL6, CXCL1). RNA sequencing analysis revealed an upregulation of the anabolic factors, inter alia, FGF18, IGF1, and TGFB2, as well as inhibitory effects on cytokines and the YAP-1 signaling pathway, explaining the underlying mechanism of the chondroanabolic promotion upon senolytic treatment. Accordingly, stimulation of untreated hAC with conditioned medium of D + Q-treated cells similarly induced the expression of chondrogenic markers. Detailed analyses demonstrated that chondroanabolic effects could be mainly attributed to Dasatinib, while monotherapeutical application of Quercetin or Navitoclax did not promote the chondroanabolism. Overall, D + Q therapy restored the chondrogenic phenotype in OA hAC most likely by creating a pro-chondroanabolic environment through the reduction of SASP factors and upregulation of growth factors. This senolytic approach could therefore be a promising candidate for further testing as a disease-modifying osteoarthritis drug.

Biocompatible ionized air alleviates rat osteoarthritis by modulating polarization from M1 to M2 macrophages

The imbalance in the proportion of M1/M2 macrophage polarization is a crucial contributor to the persistent progression of osteoarthritis (OA). This study aimed to evaluate the effects of low-dose biocompatible ionized air (BIA) on macrophage polarization and its subsequent chondroprotective effects, thereby validating the potential of BIA in slowing the progression of OA. In vitro experiments demonstrated that BIA modulates the polarization of M1 macrophages toward the M2 phenotype via the ROS-mediated STAT6 pathway. This shift reduces the expression of pro-inflammatory mediators while increasing the expression of anti-inflammatory mediators and pro-chondrogenic factors, leading to an improved microenvironment surrounding chondrocytes. The direct benefits of this improved microenvironment include enhanced chondrocyte viability, inhibition of apoptosis, and reduced degradation of the extracellular matrix. In vivo studies in rats showed that BIA inhibited M1 macrophage infiltration in the synovium, upregulated the proportion of M2 macrophages, alleviated cartilage degeneration, and delayed OA progression. This gas-based regulatory strategy may open new avenues for the treatment of OA.

Ferroptosis in Osteoarthritis: Current Understanding

Osteoarthritis (OA) is a prevalent degenerative disease in elderly people that is characterized by cartilage loss and abrasion, leading to joint pain and dysfunction. The aetiology of OA is complicated and includes abnormal mechanical stress, a mild inflammatory environment, chondrocyte senescence and apoptosis, and changes in chondrocyte metabolism. Ferroptosis is a regulated cell death modality characterized by the excessive accumulation of lipid peroxidation and mitochondrial dysfunction. The role of ferroptosis in OA pathogenesis has aroused researchers' attention in the past two years, and there is mounting evidence indicating that ferroptosis is destructive. However, the impact of ferroptosis on OA and how the regulators of ferroptosis affect OA development are unclear. Here, we reviewed the current understanding of ferroptosis in OA pathogenesis and summarized several drugs and compounds targeting ferroptosis in OA treatment. The accumulation of intracellular iron, the trigger of Fenton reaction, the excessive production of ROS, the peroxidation of PUFA-PLs, and mitochondrial and membrane damage are involved in chondrocyte ferroptosis. System Xc - and GPX4 are the most important regulators that control ferroptosis. Several compounds, such as DFO and Fer-1, have been proven effective in preventing ferroptosis and slowing OA progression on animal models. Collectively, targeting ferroptosis shows great potential in treating OA.

Macrophage and chondrocyte phenotypes in inflammation

Inflammation is a complex biological process protecting the body from diverse external threats. Effectively performing this task requires an intricate, well-regulated interplay of different cells and tissues. Furthermore, several cells participating in inflammation can assume diverse phenotypes. A classic and relatively well-studied example of phenotypic diversity in inflammation is macrophage polarization. Based on the TH1/TH2 phenotypes of T helper cells, this scheme has proinflammatory "classical/M1" activation contrasted with the anti-inflammatory and healing-promoting "alternative/M2" phenotype. Some authors have extended the concept into an M17 phenotype induced by the classic TH17 cytokine IL-17. Phenotypic changes in chondrocytes have also been studied especially in the context of osteoarthritis (OA), and there are indications that these cells can also assume polarized phenotypes at least partly analogous to those of TH cells and macrophages. The therapeutic success of biological agents targeting TH1/TH2/TH17 inductor and/or effector cytokines displays the utility of the concept of polarization. The aim of this focused review is to survey the internal and external factors affecting macrophage and chondrocyte phenotypes (such as inflammatory cytokines, widely used medications and natural products) and to explore the possibility of ameliorating pathological states by modulating these phenotypes.

Quercetin prevents methylmercury-induced mitochondrial dysfunction in the cerebral cortex of mice

Methylmercury (MeHg) exposure can cause nerve damage and mitochondrial dysfunction. Mitochondrial dysfunction is mainly mediated by mitochondrial biogenesis and mitochondrial dynamics disorders. Quercetin (QE) plays an important role in activating silencing information regulator 2 related enzyme 1 (SIRT1), and SIRT1 activates peroxisome-proliferator-activated receptor-γ co-activator 1α (PGC-1α), which can regulate mitochondrial biogenesis and mitochondrial dynamics. The main purpose of this study was to explore the alleviating effects of QE on MeHg-induced nerve damage and mitochondrial dysfunction. The results showed that QE could reduce the excessive production of reactive oxygen species (ROS) and the loss of membrane potential induced by MeHg. Meanwhile, QE activated SIRT1 activity and SIRT1/PGC-1α signaling pathway, improved mitochondrial biogenesis and fusion and reduced mitochondrial fission. In summary, we hypothesized that QE prevents MeHg-induced mitochondrial dysfunction by activating SIRT1/PGC-1α signaling pathway.

Edge advances in nanodrug therapies for osteoarthritis treatment

As global population and lifestyles change, osteoarthritis (OA) is becoming a major healthcare challenge world. OA, a chronic condition characterized by inflammatory and degeneration, often present with joint pain and can lead to irreversible disability. While there is currently no cure for OA, it is commonly managed using nonsteroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, and glucosamine. Although these treatments can alleviate symptoms, it is difficult to effectively deliver and sustain therapeutic agents within joints. The emergence of nanotechnology, particularly in form of smart nanomedicine, has introduced innovative therapeutic approaches for OA treatment. Nanotherapeutic strategies offer promising advantages, including more precise targeting of affected areas, prolonged therapeutic effects, enhanced bioavailability, and reduced systemic toxicity compared to traditional treatments. While nanoparticles show potential as a viable delivery system for OA therapies based on encouraging lab-based and clinical trials results, there remails a considerable gap between current research and clinical application. This review highlights recent advances in nanotherapy for OA and explore future pathways to refine and optimize OA treatments strategies.

Smart Hydrogel Dressing Enhances the Healing of Chronic Infectious Diabetic Wounds through Dual-Barrier Drug Delivery Action

Chronic diabetic wounds struggle to heal due to drug-resistant bacterial infections, oxidative stress microenvironment, and immune dysfunction. At present, the disease has become a huge clinical challenge. Multifunctional hydrogels with antibacterial, antioxidant, and anti-inflammatory properties are becoming an emerging trend in the treatment of chronic wounds. However, matching different bioactive functions with the wound healing process to sequentially exert antibacterial, antioxidant, anti-inflammatory, and immunomodulatory functions remains a significant challenge. In this research, a hydrogel dressing with bactericidal and anti-inflammatory properties was synthesized by crafting a pH/ROS-responsive scaffold from phenylboronic acid-grafted hyaluronic acid (HA-PBA) and 4-arm-PEG-dopamine (4A-PEG-Dopa), employing dynamic borate ester bonds. This structure was then infused with the antimicrobial peptide (AMP) and ROS-sensitive micelle mPEG-TK-PLGA loaded with quercetin (QC). This dressing embodied a dual-barrier drug delivery mechanism, engineered for the prolonged and consistent liberation of QC. In the experiment, the hydrogel dissociated within the acidic microenvironment of diabetic wounds, thereby liberating the encapsulated micelles and AMP. Upon further dissociation, the micelles release QC due to the ROS-abundant microenvironment, which could relieve oxidative stress and encourage M2 polarization of macrophage via the Akt/STAT6 signaling pathway. Therefore, this smart delivery system, developed through our innovative approach, holds promise for treating chronic infectious diabetic wounds.

Mechanistic Exploration of Smilax glabra Roxb. in Osteoarthritis: Insights from Network Pharmacology, Molecular Docking, and In Vitro Validation

Background: Arthritis, a debilitating joint disease, remains a significant global health burden. This study uncovers the therapeutic potential of the medicinal plant Smilax glabra Roxb. (SGR) in attenuating progression of disease by modulating immune responses. Methods: Through computational approaches, key bioactive compounds in SGR were identified by using freely available databases: TCMSP, TCMID, HIT2.0, HERB, and INPUT in order to elucidate their underlying mechanisms of action. Therapeutic targets for the disease have been retrieved by TTD, GeneCard, and OMIM databases. The STRING database was used to analyze the protein-protein interactions (PPI) of intersecting genes. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to reveal the functional roles of genes. Mcule was used for molecular docking and binding affinity of compounds and targets were evaluated by DeepPurpose model. ALP activity, cell viability assay, TRAP staining were also performed. Results: A total of 14 active SGR compounds with 59 common targets for arthritis have been identified. These targets have a major role in controlling biological processes such as wound healing, oxygen responses, and chemical stimuli. Molecular docking by Mcule platform demonstrated that quercetin and β-sitosterol showed higher binding energy affinities with TNF, TP53, PTGS2, and JUN as compared to other targets. To explore the complex relationship between compounds and targets, pre-trained Davis and KIBA models were used to predict the affinity values of selected compounds. In MC3T3-E1 cells, ALP activity was significantly increased and bone marrow macrophages (BMM) showed a low number of TRAP-positive cells in SGR-treated cells. Conclusions: Our findings demonstrate that SGR effectively inhibits/regulates inflammatory responses, prevents cartilage degradation, promotes bone regeneration, and can be used as a promising candidate for the development of novel arthritis treatment.

IGF signaling pathway in bone and cartilage development, homeostasis, and disease

The skeleton plays a fundamental role in the maintenance of organ function and daily activities. The insulin-like growth factor (IGF) family is a group of polypeptide substances with a pronounced role in osteoblast differentiation, bone development, and metabolism. Disturbance of the IGFs and the IGF signaling pathway is inextricably linked with assorted developmental defects, growth irregularities, and jeopardized skeletal structure. Recent findings have illustrated the significance of the action of the IGF signaling pathway via growth factors and receptors and its interactions with dissimilar signaling pathways (Wnt/β-catenin, BMP, TGF-β, and Hh/PTH signaling pathways) in promoting the growth, survival, and differentiation of osteoblasts. IGF signaling also exhibits profound influences on cartilage and bone development and skeletal homeostasis via versatile cell-cell interactions in an autocrine, paracrine, and endocrine manner systemically and locally. Our review summarizes the role and regulatory function as well as a potentially integrated gene network of the IGF signaling pathway with other signaling pathways in bone and cartilage development and skeletal homeostasis, which in turn provides an enlightening insight into visualizing bright molecular targets to be eligible for designing effective drugs to handle bone diseases and maladies, such as osteoporosis, osteoarthritis, and dwarfism.

Copper metabolism in osteoarthritis and its relation to oxidative stress and ferroptosis in chondrocytes

Ferroptosis, an iron-ion-dependent process of lipid peroxidation, damages the plasma membrane, leading to non-programmed cell death. Osteoarthritis (OA), a prevalent chronic degenerative joint disease among middle-aged and older adults, is characterized by chondrocyte damage or loss. Emerging evidence indicates that chondrocyte ferroptosis plays a role in OA development. However, most research has concentrated on ferroptosis regulation involving typical iron ions, potentially neglecting the significance of elevated copper ions in both serum and joint fluid of patients with OA. This review aims to fill this gap by systematically examining the interplay between copper metabolism, oxidative stress, ferroptosis, and copper-associated cell death in OA. It will provide a comprehensive overview of copper ions' role in regulating ferroptosis and their dual role in OA. This approach seeks to offer new insights for further research, prevention, and treatment of OA.

Legumain-Guided Ferulate-Peptide Self-Assembly Enhances Macrophage-Endotheliocyte Partnership to Promote Therapeutic Angiogenesis After Myocardial Infarction

Promoting angiogenesis and modulating the inflammatory microenvironment are promising strategies for treating acute myocardial infarction (MI). Macrophages are crucial in regulating inflammation and influencing angiogenesis through interactions with endothelial cells. However, current therapies lack a comprehensive assessment of pathological and physiological subtleties, resulting in limited myocardial recovery. In this study, legumain-guided ferulate-peptide nanofibers (LFPN) are developed to facilitate the interaction between macrophages and endothelial cells in the MI lesion and modulate their functions. LFPN exhibits enhanced ferulic acid (FA) aggregation and release, promoting angiogenesis and alleviating inflammation. The multifunctional role of LFPN is validated in cells and an MI mouse model, where it modulated macrophage polarization, attenuated inflammatory responses, and induces endothelial cell neovascularization compare to FA alone. LFPN supports the preservation of border zone cardiomyocytes by regulating inflammatory infiltration in the ischemic core, leading to significant functional recovery of the left ventricle. These findings suggest that synergistic therapy exploiting multicellular interaction and enzyme guidance may enhance the clinical translation potential of smart-responsive drug delivery systems to treat MI. This work emphasizes macrophage-endothelial cell partnerships as a novel paradigm to enhance cell interactions, control inflammation, and promote therapeutic angiogenesis.

Biomacromolecules as Immunomodulators: Utilizing Nature’s Tools for Immune Regulation

Although there are numerous available immunomodulators, those of natural origin would be preferable based on their safety profile and effectiveness. The research and clinical interest in immunomodulators have increased in the last decades, especially in the immunomodulatory properties of plant-based therapies. Innovative technologies and extensive study on immunomodulatory natural products, botanicals, extracts, and active moieties with immunomodulatory potential could provide us with valuable entities to develop as novel immunomodulatory medicines to enhance current chemotherapies. This review focuses on plant-based immunomodulatory drugs that are currently in clinical studies. However, further studies in this area are of utmost importance to obtain complete information about the positive effects of medicinal plants and their chemical components and molecules as an alternative to combatting various diseases and/or prevention.

Nutritional Epigenomics: Bioactive Dietary Compounds in the Epigenetic Regulation of Osteoarthritis

Nutritional epigenomics is exceptionally important because it describes the complex interactions among food compounds and epigenome modifications. Phytonutrients or bioactive compounds, which are secondary metabolites of plants, can protect against osteoarthritis by suppressing the expression of inflammatory and catabolic mediators, modulating epigenetic changes in DNA methylation, and the histone or chromatin remodelling of key inflammatory genes and noncoding RNAs. The combination of natural epigenetic modulators is crucial because of their additive and synergistic effects, safety and therapeutic efficacy, and lower adverse effects than conventional pharmacology in the treatment of osteoarthritis. In this review, we have summarized the chondroprotective properties of bioactive compounds used for the management, treatment, or prevention of osteoarthritis in both human and animal studies. However, further research is needed into bioactive compounds used as epigenetic modulators in osteoarthritis, in order to determine their potential value for future clinical applications in osteoarthritic patients as well as their relation with the genomic and nutritional environment, in order to personalize food and nutrition together with disease prevention.

Cellular Senescence: The Driving Force of Musculoskeletal Diseases

The aging of the world population is closely associated with an increased prevalence of musculoskeletal disorders, such as osteoporosis, sarcopenia, and osteoarthritis, due to common genetic, endocrine, and mechanical risk factors. These conditions are characterized by degeneration of bone, muscle, and cartilage tissue, resulting in an increased risk of fractures and reduced mobility. Importantly, a crucial role in the pathophysiology of these diseases has been proposed for cellular senescence, a state of irreversible cell cycle arrest induced by factors such as DNA damage, telomere shortening, and mitochondrial dysfunction. In addition, senescent cells secrete pro-inflammatory molecules, called senescence-associated secretory phenotype (SASP), which can alter tissue homeostasis and promote disease progression. Undoubtedly, targeting senescent cells and their secretory profiles could promote the development of integrated strategies, including regular exercise and a balanced diet or the use of senolytics and senomorphs, to improve the quality of life of the aging population. Therefore, our review aimed to highlight the role of cellular senescence in age-related musculoskeletal diseases, summarizing the main underlying mechanisms and potential anti-senescence strategies for the treatment of osteoporosis, sarcopenia, and osteoarthritis.

Quercetin-Loaded Zeolitic Imidazolate Framework-8 (ZIF-8) Nanoparticles Attenuate Osteoarthritis by Activating Autophagy via the Pi3k/Akt Signaling

Osteoarthritis treatment remains a significant clinical challenge. Quercetin, a natural flavonoid with anti-inflammatory and antiapoptotic properties, might be utilized to treat OA. However, poor water solubility and short joint retention duration limit its bioavailability and translation to clinical applications. A one-step self-assembly method was utilized to fabricate quercetin-loaded zeolitic imidazolate framework-8 (Qu@ZIF-8) nanoparticles using zinc ions, 2-methylimidazole, and quercetin. In vitro tests showed that Qu@ZIF-8 nanoparticles released pH-responsive agents into chondrocytes, effectively protecting them from interleukin (IL)-induced inflammation and apoptosis, thereby promoting cartilage anabolic activities. These underlying mechanisms revealed a remarkable increase of autophagy in IL-β-treated chondrocytes, followed by the inhibition of the Pi3k/Akt signaling pathway, which contributed to the protective effect of Qu @ZIF-8. By the establishment of medial meniscus instability (DMM) in OA mice, Qu@ZIF-8 substantially improved cartilage structural integrity and chondrocyte status, as well as attenuated OA progression. Importantly, Qu@ZIF-8 outperformed quercetin alone in the treatment of OA due to its control release. The combined research findings indicate that Qu@ZIF-8 shields chondrocytes from inflammation and apoptosis by activating autophagy and repressing the Pi3k/Akt pathway. This investigation may provide new insights for clinically extending the therapy of OA.

Quercetin-Loaded Bioglass Injectable Hydrogel Promotes m6A Alteration of Per1 to Alleviate Oxidative Stress for Periodontal Bone Defects

Periodontal disease ranks third among noncommunicable illnesses, behind cancer and cardiovascular disease, and is closely related to the occurrence and progression of various systemic diseases. However, elucidating the processes of periodontal disease and promoting periodontal bone regeneration remains a challenge. Here, quercetin is demonstrated to reduce the oxidative stress state of orofacial mesenchymal stem cells (OMSCs) in vitro and to affect the osteogenic growth of OMSCs through molecular mechanisms that mediate the m6A change in Per1. Nevertheless, the limited therapeutic efficacy of systemic medication and the limitations of local medication resulting from the small, moist, and highly dynamic periodontal environment make it challenging to treat periodontal tissues with medication. Herein, a biosafe injectable hydrogel drug-controlled delivery system is constructed as a bone-enhancing factory and loaded with quercetin to treat oxidative stress injury in periodontal tissues. This drug-carrying system made up of nanoscale bioglass microspheres and a light-cured injectable hydrogel, allows effective drug particle loading and cementation in the dynamic and moist periodontal environment. Furthermore, the system demonstrates the ability to stimulate OMSCs osteogenic differentiation in a Per1-dependent manner, which ultimately promotes periodontal bone repair, suggesting that this system has potential for clinical periodontal therapy.

Validation of Jianpi Qingre Tongluo Recipe in Reducing Inflammation and Dyslipidemia in Osteoarthritis via Lnc RNA HOTAIR/APN/PI3K/AKT

Objective

Jianpi Qingre Tongluo Recipe (JQP) has been widely used in clinical practice, and its anti-Osteoarthritis (OA) effectiveness and specific mechanism have been concerned. This study aims to explore the clinical effect of JQP in reducing inflammation and dyslipidemia in OA and the molecular mechanism.

Methods

The clinical efficacy of JQP in OA treatment was assessed through data mining. Through the network pharmacology technology, the interactive network of "active component-target-disease" was developed, the interaction relationship of the related proteins was analyzed, and enrichment analysis of gene pathway biological process was conducted. Molecular docking was carried out with PyMOL and AutodockTools-1.5.7. Finally, cell experiments were used to verify JQP's delay of immune inflammation in OA.

Results

We found that JQP could ameliorate the immune inflammatory and lipid metabolism indicators; reduce VAS and SAS score in OA. A total of 98 genes overlapped between target genes of JQP and OA. TNF, IL-6, IL-1β, and AKT1 shared the highest centrality among all target genes. KEGG analysis unveiled that 98 intersection genes were predominantly enriched in PI3K/AKT pathway in the anti-OA system. In vitro, after peripheral blood mononuclear cell (PBMC) stimulation, inflammatory cytokines imbalances and the expressions of adiponectin (APN) were decreased in osteoarthritis-chondrocytes (OA-CH). Furthermore, JQP-containing serum protected OA-CHs through down-regulating HOTAIR levels, thereby up-regulating APN and depressing PI3K/AKT pathway.

Conclusion

This study suggests that JQP might reduce inflammation and improve lipid metabolism of OA by regulating HOTAIR/APN/PI3K/AKT. Our results bring a new solution for OA.

Quercetin Modulates Ferroptosis via the SIRT1/Nrf-2/HO-1 Pathway and Attenuates Cartilage Destruction in an Osteoarthritis Rat Model

Osteoarthritis (OA) is the most common joint disease, causing symptoms such as joint pain, swelling, and deformity, which severely affect patients' quality of life. Despite advances in medical treatment, OA management remains challenging, necessitating the development of safe and effective drugs. Quercetin (QUE), a natural flavonoid widely found in fruits and vegetables, shows promise due to its broad range of pharmacological effects, particularly in various degenerative diseases. However, its role in preventing OA progression and its underlying mechanisms remain unclear. In this study, we demonstrated that QUE has a protective effect against OA development both in vivo and in vitro, and we elucidated the underlying molecular mechanisms. In vitro, QUE inhibited the expression of IL-1β-induced chondrocyte matrix metalloproteinases (MMP3 and MMP13) and inflammatory mediators such as INOS and COX-2. It also promoted the expression of collagen II, thereby preventing the extracellular matrix (ECM). Mechanistically, QUE exerts its protective effect on chondrocytes by activating the SIRT1/Nrf-2/HO-1 and inhibiting chondrocyte ferroptosis. Similarly, in an OA rat model induced by anterior cruciate ligament transection (ACLT), QUE treatment improved articular cartilage damage, reduced joint pain, and normalized abnormal subchondral bone remodeling. QUE also reduced serum IL-1β, TNF-α, MMP3, CTX-II, and COMP, thereby slowing the progression of OA. QUE exerts chondroprotective effects by inhibiting chondrocyte oxidative damage and ferroptosis through the SIRT1/Nrf-2/HO-1 pathway, effectively alleviating OA progression in rats.

Reversing Aging and Improving Health Span in Glaucoma Patients: The Next Frontier?

How to cite this article: Dada T, Mahalingam K, Bhartiya S. Reversing Aging and Improving Health Span in Glaucoma Patients: The Next Frontier? J Curr Glaucoma Pract 2024;18(3):87-93.

Quercetin attenuates inflammation in rosacea by directly targeting p65 and ICAM-1

AIMS

Rosacea is an inflammatory skin disease with immune and vascular dysfunction. Although there are multiple treatment strategies for rosacea, the clinical outcomes are unsatisfactory.

MAIN METHODS

Combining transcriptome data and the Connectivity Map database quercetin was identified as a novel candidate for rosacea. Next, the therapeutic efficacy of quercetin was substantiated through proteomic analyses, in vivo experiments, and in vitro assays. Additionally, the utilization of DARTS, molecular docking and experimental verification revealed the therapeutic mechanisms of quercetin.

KEY FINDINGS

Treatment with quercetin resulted in the following effects: (i) it effectively ameliorated rosacea-like features by reducing immune infiltration and angiogenesis; (ii) it suppressed the expression of inflammatory mediators in HaCaT cells and HDMECs; (iii) it interacted with p65 and ICAM-1 directly, and this interaction resulted in the repression of NF-κB signal and ICAM-1 expression in rosacea.

SIGNIFICANCE

We show for the first time that quercetin interacted with p65 and ICAM-1 directly to alleviated inflammatory and vascular dysfunction, suggesting quercetin is a novel, promising therapeutic candidate for rosacea.

Inflammation-Targeted Nanomedicines Alleviate Oxidative Stress and Reprogram Macrophages Polarization for Myocardial Infarction Treatment

Myocardial infarction (MI) is a critical global health challenge, with current treatments limited by the complex MI microenvironment, particularly the excessive oxidative stress and intense inflammatory responses that exacerbate cardiac dysfunction and MI progression. Herein, a mannan-based nanomedicine, Que@MOF/Man, is developed to target the inflammatory infarcted heart and deliver the antioxidative and anti-inflammatory agent quercetin (Que), thereby facilitating a beneficial myocardial microenvironment for cardiac repair. The presence of mannan on the nanoparticle surface enables selective internalization by macrophages rather than cardiomyocytes. Que@MOF/Man effectively neutralizes reactive oxygen species in macrophages to reduce oxidative stress and promote their differentiation into a reparative phenotype, reconciling the inflammatory response and enhancing cardiomyocyte survival through intercellular communication. Owing to the recruitment of macrophages into inflamed myocardium post-MI, in vivo, administration of Que@MOF/Man in MI rats revealed the specific distribution into the injured myocardium compared to free Que. Furthermore, Que@MOF/Man exhibited favorable results in resolving inflammation and protecting cardiomyocytes, thereby preventing further myocardial remodeling and improving cardiac function in MI rats. These findings collectively validate the rational design of an inflammation-targeted delivery strategy to mitigate oxidative stress and modulate the inflammation response in the injured heart, presenting a therapeutic avenue for MI treatment.

The role and intervention of mitochondrial metabolism in osteoarthritis

Osteoarthritis (OA), a prevalent degenerative joint disease, affects a substantial global population. Despite the elusive etiology of OA, recent investigations have implicated mitochondrial dysfunction as a significant factor in disease pathogenesis. Mitochondria, pivotal cellular organelles accountable for energy production, exert essential roles in cellular metabolism. Hence, mitochondrial dysfunction can exert broad-ranging effects on various cellular processes implicated in OA development. This comprehensive review aims to provide an overview of the metabolic alterations occurring in OA and elucidate the diverse mechanisms through which mitochondrial dysfunction can contribute to OA pathogenesis. These mechanisms encompass heightened oxidative stress and inflammation, perturbed chondrocyte metabolism, and compromised autophagy. Furthermore, this review will explore potential interventions targeting mitochondrial metabolism as means to impede or decelerate the progression of OA. In summary, this review offers a comprehensive understanding of the involvement of mitochondrial metabolism in OA and underscores prospective intervention strategies.

Harnessing the Power of Polyphenols: A New Frontier in Disease Prevention and Therapy

There are a wide variety of phytochemicals collectively known as polyphenols. Their structural diversity results in a broad range of characteristics and biological effects. Polyphenols can be found in a variety of foods and drinks, including fruits, cereals, tea, and coffee. Studies both in vitro and in vivo, as well as clinical trials, have shown that they possess potent antioxidant activities, numerous therapeutic effects, and health advantages. Dietary polyphenols have demonstrated the potential to prevent many health problems, including obesity, atherosclerosis, high blood sugar, diabetes, hypertension, cancer, and neurological diseases. In this paper, the protective effects of polyphenols and the mechanisms behind them are investigated in detail, citing the most recent available literature. This review aims to provide a comprehensive overview of the current knowledge on the role of polyphenols in preventing and managing chronic diseases. The cited publications are derived from in vitro, in vivo, and human-based studies and clinical trials. A more complete understanding of these naturally occurring metabolites will pave the way for the development of novel polyphenol-rich diet and drug development programs. This, in turn, provides further evidence of their health benefits.

Unraveling the path to osteoarthritis management: targeting chondrocyte apoptosis for therapeutic intervention

Osteoarthritis (OA) is a chronic disease affecting joints and further causing disabilities. This disease affects around 240 million people worldwide. It is a multifactorial disease, and its etiology is difficult to determine. Although numerous therapeutic strategies are available, the therapies are aimed at reducing pain and improving patients' quality of life. Hence, there is an urgent need to develop disease-modifying drugs (DMOAD) that can reverse or halt OA progression. Apoptosis is a cell removal process that is important in maintaining homeostatic mechanisms in the development and sustaining cell population. The apoptosis of chondrocytes is believed to play an important role in OA progression due to poor chondrocytes self-repair abilities to maintain the extracellular matrix (ECM). Hence, targeting chondrocyte apoptosis can be one of the potential therapeutic strategies in OA management. There are various mediators and targets available to inhibit apoptosis such as autophagy, endoplasmic reticulum (ER) stress, oxidative stress, and inflammation. As such, this review highlights the importance and potential targets that can be aimed to reduce chondrocyte apoptosis.

Osteoarthritis: Insights into Diagnosis, Pathophysiology, Therapeutic Avenues, and the Potential of Natural Extracts

Osteoarthritis (OA) stands as a prevalent and progressively debilitating clinical condition globally, impacting joint structures and leading to their gradual deterioration through inflammatory mechanisms. While both non-modifiable and modifiable factors contribute to its onset, numerous aspects of OA pathophysiology remain elusive despite considerable research strides. Presently, diagnosis heavily relies on clinician expertise and meticulous differential diagnosis to exclude other joint-affecting conditions. Therapeutic approaches for OA predominantly focus on patient education for self-management alongside tailored exercise regimens, often complemented by various pharmacological interventions primarily targeting pain alleviation. However, pharmacological treatments typically exhibit short-term efficacy and local and/or systemic side effects, with prosthetic surgery being the ultimate resolution in severe cases. Thus, exploring the potential integration or substitution of conventional drug therapies with natural compounds and extracts emerges as a promising frontier in enhancing OA management. These alternatives offer improved safety profiles and possess the potential to target specific dysregulated pathways implicated in OA pathogenesis, thereby presenting a holistic approach to address the condition's complexities.

BMSC-Derived Exosomes Attenuate Rat Osteoarthritis by Regulating Macrophage Polarization through PINK1/Parkin Signaling Pathway

OBJECTIVE

Exosomes derived from bone marrow mesenchymal stem cells (BMSC-Exos) may modulate the M1/M2 polarization of macrophages during osteoarthritis (OA). However, the underlying mechanisms of BMSC-Exos in this process still need to be elucidated. In this study, we explored the role of BMSC-Exos in the polarization of macrophages in vitro and the OA rats in vivo.

METHODS

The effects of BMSC-Exos on RAW264.7 cells were determined, including the production of reactive oxygen species (ROS) and the protein expression of Akt, PINK1, and Parkin. We prepared an OA model by resecting the anterior cruciate ligament and medial meniscus of Sprague-Dawley (SD) rats. Hematoxylin-eosin (H&E) and safranin O-fast green staining, immunohistochemistry and immunofluorescence analyses, and the examination of interleukin 6 (IL-6), interleukin 1β (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 10 (IL-10) were performed to assess changes in cartilage and synovium.

RESULTS

BMSC-Exos inhibited mitochondrial membrane damage, ROS production, and the protein expression of PINK1 and Parkin. Akt phosphorylation was downregulated under lipopolysaccharide (LPS) induction but significantly recovered after treatment with BMSC-Exos. BMSC-Exos alleviated cartilage damage, inhibited M1 polarization, and promoted M2 polarization in the synovium in OA rats. The expression of PINK1 and Parkin in the synovium and the levels of IL-6, IL-1β, and TNF-α in the serum decreased, but the level of IL-10 increased when BMSC-Exos were used in OA rats.

CONCLUSION

BMSC-Exos ameliorate OA development by regulating synovial macrophage polarization, and one of the underlying mechanisms may be through inhibiting PINK1/Parkin signaling.

IDN5706 Inhibits Synovial Inflammation via Inducing M2 Polarization of Synovial Macrophages in Osteoarthritis Rats

INTRODUCTION

IDN5706 is a tetrahydro derivative of hyperforin. In this study, we aimed to explore the effect of IDN5706 on synovial macrophages in osteoarthritis (OA) rats and the underlying mechanisms.

METHODS

OA rats were employed for the in vivo experiments, and RAW264.7 cells were employed for the in vitro experiments. Histopathological changes in synovium were examined using hematoxylin-eosin staining. Cell apoptosis in synovium was assessed by TUNEL staining. Macrophage polarization was determined by immunohistochemical analysis and flow cytometry. The mRNA expression and protein level of genes were detected by qRT-PCR and Western blot. The efferocytosis of macrophages was assessed by flow cytometry.

RESULTS

IDN5706 reversed the increased CD86-positive cells (M1 macrophages) and decreased CD206-positive cells (M2 macrophages), both in synovium and synovial fluid of OA rats. The in vitro experiments further confirmed the promotion effect of IDN5706 on M2 macrophages, accompanied by the elevated Arg-1 and reduced iNOS. Also, the upregulated p-mTOR in synovium and synovial fluid of OA rats were reversed by IDN5706, and the decreased M1 macrophages and increased M2 macrophages induced by IDN5706 were reversed by the mTOR activator. IDN5706 enhanced the efferocytosis of IL-4-treated RAW264.7 cells, and the animal experiments further revealed the involvement of efferocytosis in the improvement of OA by IDN5706.

CONCLUSIONS

IDN5706 enhanced the efferocytosis of synovial macrophages by inducing M2 polarization via inhibiting p-mTOR, thus suppressing synovial inflammation and OA development, providing a theoretical basis for IDN5706 as a clinical drug for inflammatory diseases.

Efficacy of IFN-γ-Primed Umbilical Cord-Derived Mesenchymal Stem Cells on Temporomandibular Joint Osteoarthritis

BACKGROUND

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disease affecting the cartilage and subchondral bone, leading to temporomandibular joint pain and dysfunction. The complex nature of TMJOA warrants effective alternative treatments, and mesenchymal stem cells (MSCs) have shown promise in regenerative therapies. The aim of this study is twofold: firstly, to ascertain the optimal interferon-gamma (IFN-γ)-primed MSC cell line for TMJOA treatment, and secondly, to comprehensively evaluate the therapeutic efficacy of IFN-γ-primed mesenchymal stem cells derived from the human umbilical cord matrix in a rat model of TMJOA.

METHODS

We analyzed changes in the expression of several key genes associated with OA protection in MSC-secreted compounds. Following this, we performed co-culture experiments using a transwell system to predict gene expression changes in primed MSCs in the TMJOA environment. Subsequently, we investigated the efficacy of the selected IFN-γ-primed human umbilical cord matrix-derived MSCs (hUCM-MSCs) for TMJOA treatment in a rat model.

RESULTS

IFN-γ-primed MSCs exhibited enhanced expression of IDO, TSG-6, and FGF-2. Moreover, co-culturing with rat OA chondrocytes induced a decrease in pro-inflammatory and extracellular matrix degradation factors. In the rat TMJOA model, IFN-γ-primed MSCs with elevated IDO1, TSG-6, and FGF2 expression exhibited robust anti-inflammatory and therapeutic capacities, promoting the improvement of the inflammatory environment and cartilage regeneration.

CONCLUSION

These findings underscore the importance of prioritizing the mitigation of the inflammatory milieu in TMJOA treatment and highlight IFN-γ-primed MSCs secreting these three factors as a promising, comprehensive therapeutic strategy.

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

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

Phytochemicals against Osteoarthritis by Inhibiting Apoptosis

Osteoarthritis (OA) is a chronic joint disease that causes pathological changes in articular cartilage, synovial membrane, or subchondral bone. Conventional treatments for OA include surgical and non-surgical methods. Surgical treatment is suitable for patients in the terminal stage of OA. It is often the last choice because of the associated risks and high cost. Medication of OA mainly includes non-steroidal anti-inflammatory drugs, analgesics, hyaluronic acid, and cortico-steroid anti-inflammatory drugs. However, these drugs often have severe side effects and cannot meet the needs of patients. Therefore, safe and clinically appropriate long-term treatments for OA are urgently needed. Apoptosis is programmed cell death, which is a kind of physiologic cell suicide determined by heredity and conserved by evolution. Inhibition of apoptosis-related pathways has been found to prevent and treat a variety of diseases. Excessive apoptosis can destroy cartilage homeostasis and aggravate the pathological process of OA. Therefore, inhibition of apoptosis-related factors or signaling pathways has become an effective means to treat OA. Phytochemicals are active ingredients from plants, and it has been found that phytochemicals can play an important role in the prevention and treatment of OA by inhibiting apoptosis. We summarize preclinical and clinical studies of phytochemicals for the treatment of OA by inhibiting apoptosis. The results show that phytochemicals can treat OA by targeting apoptosis-related pathways. On the basis of improving some phytochemicals with low bioavailability, poor water solubility, and high toxicity by nanotechnology-based drug delivery systems, and at the same time undergoing strict clinical and pharmacological tests, phytochemicals can be used as a potential therapeutic drug for OA and may be applied in clinical settings.

Gentiopicroside ameliorates the lipopolysaccharide-induced inflammatory response and hypertrophy in chondrocytes

PURPOSE

This study aimed to evaluate the protective effects of gentiopicroside against lipopolysaccharide-induced chondrocyte inflammation.

METHODS

SW 1353 chondrosarcoma cells were stimulated with LPS (5 μg/ml) for 24 h and treated with different concentrations of gentiopicroside (GPS) for 24 h. The toxic effects of GPS on chondrocytes were determined using a CCK-8 assay and EdU staining. Western blotting, qPCR, and immunofluorescence analysis were used to examine the protective effect of GPS against the inflammatory response in chondrocytes induced by lipopolysaccharide (LPS). One-way ANOVA was used to compare the differences between the groups (significance level of 0.05).

RESULTS

The CCK-8 results showed that 10, 20 and 40 μM GPS had no significant toxic effects on chondrocytes; GPS effectively reduced the production of IL-1β and PGE2, reversed LPS-induced extracellular matrix degradation in cartilage by inhibiting the Stat3/Runx2 signaling pathway, and suppressed the hypertrophic transformation of SW 1353 chondrosarcoma cells.

CONCLUSION

Our study demonstrated that GPS significantly inhibited the LPS-induced inflammatory response and hypertrophic cellular degeneration in SW 1353 chondrosarcoma cells and is a valuable traditional Chinese medicine for the treatment of knee osteoarthritis.

Quercetin-loaded mesoporous nano-delivery system remodels osteoimmune microenvironment to regenerate alveolar bone in periodontitis via the miR-21a-5p/PDCD4/NF-κB pathway

BACKGROUND

Impaired osteo-/angiogenesis, excessive inflammation, and imbalance of the osteoimmune homeostasis are involved in the pathogenesis of the alveolar bone defect caused by periodontitis. Unfortunately, there is still a lack of ideal therapeutic strategies for periodontitis that can regenerate the alveolar bone while remodeling the osteoimmune microenvironment. Quercetin, as a monomeric flavonoid, has multiple pharmacological activities, such as pro-regenerative, anti-inflammatory, and immunomodulatory effects. Despite its vast spectrum of pharmacological activities, quercetin's clinical application is limited due to its poor water solubility and low bioavailability.

RESULTS

In this study, we fabricated a quercetin-loaded mesoporous bioactive glass (Quercetin/MBG) nano-delivery system with the function of continuously releasing quercetin, which could better promote the bone regeneration and regulate the immune microenvironment in the alveolar bone defect with periodontitis compared to pure MBG treatment. In particular, this nano-delivery system effectively decreased injection frequency of quercetin while yielding favorable therapeutic results. In view of the above excellent therapeutic effects achieved by the sustained release of quercetin, we further investigated its therapeutic mechanisms. Our findings indicated that under the periodontitis microenvironment, the intervention of quercetin could restore the osteo-/angiogenic capacity of periodontal ligament stem cells (PDLSCs), induce immune regulation of macrophages and exert an osteoimmunomodulatory effect. Furthermore, we also found that the above osteoimmunomodulatory effects of quercetin via macrophages could be partially blocked by the overexpression of a key microRNA--miR-21a-5p, which worked through inhibiting the expression of PDCD4 and activating the NF-κB signaling pathway.

CONCLUSION

In summary, our study shows that quercetin-loaded mesoporous nano-delivery system has the potential to be a therapeutic approach for reconstructing alveolar bone defects in periodontitis. Furthermore, it also offers a new perspective for treating alveolar bone defects in periodontitis by inhibiting the expression of miR-21a-5p in macrophages and thereby creating a favorable osteoimmune microenvironment.

Quercetin-3-O-β-D-glucuronide attenuates osteoarthritis by inhibiting cartilage extracellular matrix degradation and inflammation

Objective

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by cartilage damage. In order to find a safer and more effective drug to treat OA, we investigated the role of quercetin-3-O-β-D-glucuronide (Q3GA) in OA.

Methods

We used qRT-PCR and western blots to detect the effects of Q3GA on extracellular matrix (ECM) and inflammation related genes and proteins in interleukin-1β (IL-1β) induced chondrocytes. We determined the effect of Q3GA on the NF-κB pathway using western blots and immunofluorescence. Moreover, the effect of Q3GA on the Nrf2 pathway was evaluated through molecular docking, western blots, and immunofluorescence experiments and further validated by transfection with Nrf2 siRNA. Subsequently, we established a rat model of OA and injected Q3GA into the joint cavity for treatment. After 5 weeks of Q3GA administration, samples were obtained for micro-computed tomography scanning and histopathological staining to determine the effects of Q3GA on OA rats.

Results

We found that Q3GA reduced the degradation of ECM and the expression of inflammatory related proteins and genes in primary chondrocytes of rats induced by IL-1β, as well as the expression of nitric oxide (NO) and reactive oxygen species (ROS). It inhibited the activation of the NF-κB pathway by increasing the expression of Nrf2 in the nucleus. In addition, Q3GA inhibited cartilage degradation in OA rats and promoted cartilage repair.

Conclusion

Q3GA attenuates OA by inhibiting ECM degradation and inflammation via the Nrf2/NF-κB axis.

The translational potential of this article

The results of our study demonstrate the promising potential of Q3GA as a candidate drug for the treatment of OA and reveal its key mechanisms.

Emerging Roles of Macrophage Polarization in Osteoarthritis: Mechanisms and Therapeutic Strategies

Osteoarthritis (OA) is the most common chronic degenerative joint disease in middle-aged and elderly people, characterized by joint pain and dysfunction. Macrophages are key players in OA pathology, and their activation state has been studied extensively. Various studies have suggested that macrophages might respond to stimuli in their microenvironment by changing their phenotypes to pro-inflammatory or anti-inflammatory phenotypes, which is called macrophage polarization. Macrophages accumulate and become polarized (M1 or M2) in many tissues, such as synovium, adipose tissue, bone marrow, and bone mesenchymal tissues in joints, while resident macrophages as well as other stromal cells, including fibroblasts, chondrocytes, and osteoblasts, form the joint and function as an integrated unit. In this study, we focus exclusively on synovial macrophages, adipose tissue macrophages, and osteoclasts, to investigate their roles in the development of OA. We review recent key findings related to macrophage polarization and OA, including pathogenesis, molecular pathways, and therapeutics. We summarize several signaling pathways in macrophage reprogramming related to OA, including NF-κB, MAPK, TGF-β, JAK/STAT, PI3K/Akt/mTOR, and NLRP3. Of note, despite the increasing availability of treatments for osteoarthritis, like intra-articular injections, surgery, and cellular therapy, the demand for more effective clinical therapies has remained steady. Therefore, we also describe the current prospective therapeutic methods that deem macrophage polarization to be a therapeutic target, including physical stimulus, chemical compounds, and biological molecules, to enhance cartilage repair and alleviate the progression of OA.

A multifunctional quercetin/polycaprolactone electrospun fibrous membrane for periodontal bone regeneration

Image 1.

Quercetin inhibits mesothelial-mesenchymal transition and alleviates postoperative peritoneal adhesions by blocking the TGF-β1/PI3K/AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Carthami flos is a dried flower of the Asteraceae plant Carthamus tinctorius (L.). Danhong injection, composed of Carthami flos and Danshen can prevent the formation of postoperative peritoneal adhesions. Quercetin (QUE), an active compound of Carthami flos, has also been proved to prevent postoperative abdominal and uterine cavity adhesions. However, whether QUE is the key component in Carthami flos and the mechanism in preventing postoperative peritoneal adhesions has not been studied.

AIM OF THE STUDY

To predict whether QUE is the key molecule in Carthami flos and explore the effect and mechanism of QUE in preventing postoperative peritoneal adhesions.

MATERIALS AND METHODS

Drug composition and target analysis was used to predict the key component in Carthami flos. The method of cecum-sidewall abrasion was used to establish adhesion models, and the antiadhesion effect of QUE was evaluated with the adhesion scoring system. Network pharmacology was used to predict the targets and potential mechanism of QUE in preventing adhesion. The mechanism was further verified by immunofluorescence, Western blot, wound healing experiment, and molecular docking.

RESULTS

Quercetin was predicted to be the key to preventing postoperative peritoneal adhesions in Carthami flos. Animal experiments revealed that QUE effectively ameliorated adhesions and reduced the expression of mesothelial-mesenchymal transition (MMT) related markers and TGF-β1. Moreover, the TGF-β1/PI3K/AKT pathway was predicted via protein-protein interaction and Kyoto encyclopedia of Genes and Genomes enrichment analysis to play a crucial part in preventing adhesion by QUE. Furthermore, in vitro experiments and molecular docking demonstrated that QUE could block the TGF-β1/PI3K/AKT pathway through forming a stable combination with TβR-II, thereby inhibiting MMT and ameliorating peritoneal adhesion.

CONCLUSIONS

QUE can not only reduce postoperative TGF-β1 but also block the TGF-β1/PI3K/AKT pathway to inhibit MMT of mesothelial cells, and finally alleviate postoperative peritoneal adhesions. These findings may provide insights towards development of a safe and effective anti-adhesive drug for prevention of postoperative peritoneal adhesions.

Pharmacological and mechanistic aspects of quercetin in osteoporosis

Osteoporosis (OP) is a bone disease associated with increasing age. Currently, the most common medications used to treat OP are anabolic agents, anti-resorptive agents, and medications with other mechanisms of action. However, many of these medications have unfavorable adverse effects or are not intended for long-term use, potentially exerting a severe negative impact on a patient's life and career and placing a heavy burden on families and society. There is an urgent need to find new drugs that can replace these and have fewer adverse effects. Quercetin (Que) is a common flavonol in nature. Numerous studies have examined the therapeutic applications of Que. However, a comprehensive review of the anti-osteoporotic effects of Que has not yet been conducted. This review aimed to describe the recent studies on the anti-osteoporotic effects of Que, including its biological, pharmacological, pharmacokinetic, and toxicological properties. The outcomes demonstrated that Que could enhance OP by increasing osteoblast differentiation and activity and reducing osteoclast differentiation and activity via the pathways of Wnt/β-catenin, BMP/SMAD/RUNX2, OPG/RANKL/RANK, ERK/JNK, oxidative stress, apoptosis, and transcription factors. Thus, Que is a promising novel drug for the treatment of OP.

ADAM8 silencing suppresses the migration and invasion of fibroblast-like synoviocytes via FSCN1/MAPK cascade in osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is a degenerative joint disease that affects elderly populations worldwide, causing pain and disability. Alteration of the fibroblast-like synoviocytes (FLSs) phenotype leads to an imbalance in the synovial inflammatory microenvironment, which accelerates the progression of OA. Despite this knowledge, the specific molecular mechanisms of the synovium that affect OA are still unclear.

METHODS

Both in vitro and in vivo experiments were undertaken to explore the role of ADAM8 playing in the synovial inflammatory of OA. A small interfering RNA (siRNA) was targeting ADAM8 to intervene. High-throughput sequencing was also used.

RESULTS

Our sequencing analysis revealed significant upregulation of the MAPK signaling cascade and ADAM8 gene expression in IL-1β-induced FLSs. The in vitro results demonstrated that ADAM8 blockade inhibited the invasion and migration of IL-1β-induced FLSs, while also suppressing the expression of related matrix metallomatrix proteinases (MMPs). Furthermore, our study revealed that inhibiting ADAM8 weakened the inflammatory protein secretion and MAPK signaling networks in FLSs. Mechanically, it revealed that inhibiting ADAM8 had a significant effect on the expression of migration-related signaling proteins, specifically FSCN1. When siADAM8 was combined with BDP-13176, a FSCN1 inhibitor, the migration and invasion of FLSs was further inhibited. These results suggest that FSCN1 is a crucial downstream factor of ADAM8 in regulating the biological phenotypes of FLSs. The in vivo experiments demonstrated that ADAM8 inhibition effectively reduced synoviocytes inflammation and alleviated the progression of OA in rats.

CONCLUSIONS

ADAM8 could be a promising therapeutic target for treating OA by targeting synovial inflammation.