Apoptosis signaling pathways in osteoarthritis and possible protective role of melatonin

Myrislignan ameliorates the progression of osteoarthritis: An in vitro and in vivo study

Osteoarthritis (OA) is a prevalent disease of the musculoskeletal system that causes functional deterioration and diminished quality of life. Myrislignan (MRL) has a wide range of pharmacological characteristics, including an anti-inflammatory ability. Although inflammation is a major cause of OA, the role of MRL in OA treatment is still not well-understood. In this study, we analyze the anti-inflammatory and anti-ECM degradation effects of MRL both in vivo and in vitro. Rat primary chondrocytes were treated with interleukin-1β (IL-1β) to simulate inflammatory environmental conditions and OA in vitro. The in vivo OA rat model was established by anterior cruciate ligament transection (ACLT) on rat. Our investigation discovered that MRL lowers the IL-1β-activated tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX2) and inducible nitric-oxide synthase (iNOS) expression in chondrocytes. Moreover, MRL effectively alleviates IL-1β-induced extracellular matrix (ECM) degradation and promotes ECM synthesis in chondrocytes by upregulating the mRNA level expression of collagen-II and aggrecan (ACAN), downregulating the expression of matrix metalloproteinases-3,-13 (MMP-3, MMP-13), and a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5). Gene expression profiles of different groups identified DEGs that were mainly enriched in functions associated with NF-κB signaling pathway, and other highly enriched in functions related to TNF, IL-17, Rheumatoid arthritis and cytokine-cytokine receptor signaling pathways. Venn interaction of DEGs from the abovementioned five pathways showed that Nfkbia, Il1b, Il6, Nfkb1, Ccl2, Mmp3 were highly enriched DEGs. In addition, our research revealed that MRL suppresses NF-κB and modulates the Nrf2/HO-1/JNK signaling pathway activated by IL-1β in chondrocytes. In vivo research shows that MRL slows the progression of OA in rats. Our findings imply that MRL might be a viable OA therapeutic choice.

LncRNA NKILA attenuates the progression of osteoarthritis through the targeted inhibition of the NF-κB pathway

BACKGROUND

Interleukin-1β (IL-1β) plays a crucial role in cartilage degeneration by inducing inflammatory cascades in chondrocytes, impairing their normal biological functions. Long non-coding RNA NKILA (lncRNA NKILA) has been implicated in osteoarthritis (OA), but its specific molecular mechanisms remain unclear. This study aims to elucidate the function and molecular regulatory mechanism of lncRNA NKILA in articular chondrocytes under IL-1β stimulation.

METHODS

Primary human articular chondrocytes were cultured to investigate the effects of IL-1β on chondrocyte proliferation, apoptosis, and extracellular matrix metabolism. We employed Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR), western blot, flow cytometry, immunofluorescence, and nuclear mass separation assays to explore the interaction between lncRNA NKILA and the NFκB signaling pathway. Additionally, animal experiments were conducted to evaluate the therapeutic potential of modulating lncRNA NKILA expression in vivo.

RESULTS

IL-1β treatment led to decreased chondrocyte proliferation and increased apoptosis. Our study demonstrated that IL-1β downregulates lncRNA NKILA, which weakens its inhibitory effect on the NFκB (Nuclear Factor Kappa B) signaling pathway. This downregulation results in increased NFκB activity and exacerbates chondrocyte degeneration. Notably, the upregulation of lncRNA NKILA significantly alleviated OA symptoms, indicating that NKILA could be a promising therapeutic target.

CONCLUSION

IL-1β reduces lncRNA NKILA expression, weakening its inhibition of NFκB signaling and promoting articular chondrocyte degeneration. Enhancing lncRNA NKILA expression offers a promising approach to mitigating OA, suggesting that NKILA could serve as a potential therapeutic target for OA treatment.

Non-apoptotic cell death in osteoarthritis: Recent advances and future

Osteoarthritis (OA) is the most common degenerative joint disease. Multiple tissues are altered during the development of OA, resulting in joint pain and permanent damage to the osteoarticular joints. Current research has demonstrated that non-apoptotic cell death plays a crucial role in OA. With the continuous development of targeted therapies, non-apoptotic cell death has shown great potential in the prevention and treatment of OA. We systematically reviewed research progress on the role of non-apoptotic cell death in the pathogenesis, development, and outcome of OA, including autophagy, pyroptosis, ferroptosis, necroptosis, immunogenic cell death, and parthanatos. This article reviews the mechanism of non-apoptotic cell death in OA and provides a theoretical basis for the identification of new targets for OA treatment.

Anti-Inflammatory and Antioxidant Effects of Irigenen Alleviate Osteoarthritis Progression through Nrf2/HO-1 Pathway

BACKGROUND/OBJECTIVES

Osteoarthritis (OA) is a prevalent degenerative disease globally, characterized by cartilage degradation and joint dysfunction. Current treatments are insufficient for halting OA progression. Irigenin (IRI), a flavonoid extracted from natural plants with anti-inflammatory and antioxidant properties, has demonstrated potential in mitigating inflammation and oxidative stress in various diseases; however, its effects on OA remain unexplored. This study aims to evaluate the therapeutic effects of IRI on OA through in vivo and in vitro experiments and to elucidate the underlying molecular mechanisms.

METHODS

In vitro, chondrocytes were exposed to hydrogen peroxide (H2O2) to induce an oxidative stress environment and were then treated with IRI. Western blotting, RT-qPCR, immunofluorescence staining assays, flow cytometry, and apoptosis assays were employed to assess the effects of IRI on chondrocyte matrix homeostasis, inflammatory response, and apoptosis. In vivo, an OA rat model was treated with regular IRI injections, and therapeutic effects were evaluated using micro-CT, histological staining, and immunohistochemistry assays.

RESULTS

IRI treatment restored matrix homeostasis in chondrocytes and effectively suppressed H2O2-induced inflammation and apoptosis. Subsequent studies further revealed that IRI exerts its therapeutic effects by activating the Nrf2/HO-1 pathway. Inhibition of Nrf2 expression in chondrocytes partially blocked the anti-inflammatory and antioxidant effects of IRI. In the OA rat model, regular IRI injections effectively ameliorated cartilage degeneration.

CONCLUSIONS

This study identifies IRI as a promising strategy for OA treatment by modulating inflammation and apoptosis through the Nrf2/HO-1 pathway.

Liposomal sodium clodronate mitigates radiation-induced lung injury through macrophage depletion

Radiation-induced lung injury (RILI) is a severe complication arising from thoracic tumor radiotherapy, which constrains the possibility of increasing radiation dosage. Current RILI therapies provide only limited relief and may result in undesirable side effects. Therefore, there is an urgent demand for effective and low-toxicity treatments for RILI. Macrophages play a pivotal role in RILI, promoting inflammation in the initial stages and facilitating fibrosis in the later stages. Sodium clodronate, a bisphosphonate, can induce macrophage apoptosis when encapsulated in liposomes. In this study, we explored the potential of liposomal sodium clodronate (LC) as a specific agent for depleting macrophages to alleviate acute RILI. We assessed the impact of LC on macrophage consumption both in vitro and in vivo. In a mouse model of acute RILI, LC treatment group led to a reduction in alveolar macrophage counts, mitigated lung injury severity, and lowered levels of pro-inflammatory cytokines in both plasma and bronchoalveolar lavage fluid. Additionally, we further elucidated the specific effects and mechanism of LC on macrophages in vitro. Alveolar macrophages MHS cells were subjected to varying concentrations of LC (0, 50, 100, 200 μg/ml), and the results demonstrated its dose-dependent inhibition of cell proliferation and induction of apoptosis. Moreover, LC decreased the secretion of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Conditioned media from LC-treated macrophages protected alveolar epithelial cells MLE-12 from radiation-induced damage, as demonstrated by reduced apoptosis and DNA damage. These findings imply that LC-mediated macrophage depletion may present a promising therapeutic strategy for alleviating radiation-induced lung injury.

Microneedle-Delivered PDA@Exo for Multifaceted Osteoarthritis Treatment via PI3K-Akt-mTOR Pathway

Osteoarthritis (OA) is marked by cartilage deterioration, subchondral bone changes, and an inflammatory microenvironment. The study introduces the Microneedle-Delivered Polydopamine-Exosome (PDA@Exo MN), a therapeutic that not only preserves cartilage and promotes bone regeneration but also improves localized drug delivery through enhanced penetration capabilities. PDA@Exo MN shows strong reactive oxygen species (ROS) scavenging abilities and high biocompatibility, fostering osteogenesis and balancing anabolic and catabolic processes in cartilage. It directs macrophage polarization from M0 to the anti-inflammatory M2 phenotype. RNA sequencing of treated chondrocytes demonstrates restored cellular function and activated antioxidant responses, with modulated inflammatory pathways. The PI3K-AKT-mTOR pathway's activation, essential for PDA@Exo's effects, is confirmed via bioinformatics and Western blot. In vivo assessments robustly validate that PDA@Exo MN prevents cartilage degradation and OA progression, supported by histological assessments and micro-CT analysis, highlighting its disease-modifying impact. The excellent biocompatibility of PDA@Exo MN, verified through histological (H&E) and blood tests showing no organ damage, underscores its safety and efficacy for OA therapy, making it a novel and multifunctional nanomedical approach in orthopedics, characterized by organ-friendliness and biosecurity.

AFK-PD alleviated osteoarthritis progression by chondroprotective and anti-inflammatory activity

Osteoarthritis (OA) is the most prevalent cartilage degenerative and low-grade inflammatory disease of the whole joint. However, there are currently no FDA-approved drugs or global regulatory agency-approved treatments OA disease modification. Therefore, it's essential to explore novel effective therapeutic strategies for OA. In our study, we investigated the effects of AFK-PD, a novel pyridone agent, on the development of OA induced by destabilization of the medial meniscus (DMM) in vivo, and its impact on the function of chondrocytes treated with IL-1β in vitro. Our results demonstrated AFK-PD alleviated OA progression through inhibiting cartilage degeneration, articular inflammation and osteophyte formation. Notably, AFK-PD inhibited chondrocyte inflammation and synovial macrophage M1 polarization, leading to the attenuation of articular inflammation. Additionally, AFK-PD promoted chondrocyte anabolism while mitigating catabolism and apoptosis, effectively inhibiting cartilage degeneration. Mechanistically, AFK-PD suppressed the expression of key signaling molecules involved in the MAPK pathway, such as p-ERK1/2 and p-JNK, as well as the NF-κB signaling molecule p-p65, in IL-1β-induced chondrocytes. These findings suggest AFK-PD ameliorates the development of OA by protecting chondrocyte functions and inhibiting articular inflammation in chondrocytes and synovial macrophages. Overall, our study highlights AFK-PD as a promising therapeutic candidate for the treatment of OA.

Melatonin hyalurosomes in collagen thermosensitive gel as a potential repurposing approach for rheumatoid arthritis management via the intra-articular route

Despite the fact that several rheumatoid arthritis treatments have been utilized, none of them achieved complete joint healing and has been accompanied by several side effects that compromise patient compliance. This study aims to provide an effective safe RA treatment with minimum side effects through the encapsulation of melatonin (MEL) in hyalurosomes and loading these hyalurosomes in collagen thermos-sensitive poloxamer 407 (PCO) hydrogels, followed by their intra-articular administration in AIA model rats. In vitro characterization of MEL-hyalurosomes and PCO hydrogel along with in vivo evaluation of the selected formulation were conducted. Particle size, PDI and EE % of the selected formulation were 71.5 nm, 0.09 and 90 %. TEM micrographs demonstrated that the particles had spherical shape with no aggregation signs. Loading PCO hydrogels with MEL-hyalurosomes did not cause significant changes in pH although it increased its viscosity and injection time. FTIR analysis showed that no interactions were noted among the delivery system components. In vivo results revealed the superior effect of MEL-hyalurosomes PCO hydrogel over MEL-PCO hydrogel and blank PCO hydrogels in improving joint healing, cartilage repair, pannus formation and cell infiltrations. Also, MEL-hyalurosomes PCO hydrogel group showed comparable levels of TNF-α, IL1, MDA, NRF2 and HO-1 with the negative control group. These findings highlight the MEL encapsulation role in augmenting its pharmacological effects along with the synergistic effect of hyaluronic acid in hyalurosomes and collagen in PCO hydrogel in promoting joint healing.

GDF11 protects against mitochondrial-dysfunction-dependent NLRP3 inflammasome activation to attenuate osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a highly prevalent degenerative disease worldwide, and tumor necrosis factor (TNF-α) is closely associated with its development. Growth differentiation factor 11 (GDF11) has demonstrated anti-injury and anti-aging abilities in certain tissues; however, its regulatory role in OA remains unclear and requires further investigation.

OBJECTIVES

To identify whether GDF11 can attenuate osteoarthritis. To exploring the the potential mechanism of GDF11 in alleviating osteoarthritis.

METHODS

In this study, we cultured and stimulated mouse primary chondrocytes with or without TNF-α, analyzing the resulting damage phenotype through microarray analysis. Additionally, we employed GDF11 conditional knockout mice OA model to examine the relationship between GDF11 and OA. To investigate the target of GDF11's function, we utilized NLRP3 knockout mice and its inhibitor to verify the potential involvement of the NLRP3 inflammasome.

RESULTS

Our in vitro experiments demonstrated that endogenous overexpression of GDF11 significantly inhibited TNF-α-induced cartilage matrix degradation and inflammatory expression in chondrocytes. Furthermore, loss of GDF11 led to NLRP3 inflammasome activation, inflammation, and metabolic dysfunction. In an in vivo surgically induced mouse model, intraarticular administration of recombinant human GDF11 alleviated OA pathogenesis, whereas GDF11 conditional knockout reversed this effect. Additionally, findings from the NLRP3-knockout DMM mouse model revealed that GDF11 exerted its protective effect by inhibiting NLRP3.

CONCLUSION

These findings demonstrate the ability of GDF11 to suppress TNF-α-induced inflammation and cartilage degeneration by preventing mitochondrial dysfunction and inhibiting NLRP3 inflammasome activation, suggesting its potential as a promising therapeutic drug for osteoarthritis.

The Emerging Role of the Mitochondrial Respiratory Chain in Skeletal Aging

Maintenance of mitochondrial homeostasis is crucial for ensuring healthy mitochondria and normal cellular function. This process is primarily responsible for regulating processes that include mitochondrial OXPHOS, which generates ATP, as well as mitochondrial oxidative stress, apoptosis, calcium homeostasis, and mitophagy. Bone mesenchymal stem cells express factors that aid in bone formation and vascular growth. Positive regulation of hematopoietic stem cells in the bone marrow affects the differentiation of osteoclasts. Furthermore, the metabolic regulation of cells that play fundamental roles in various regions of the bone, as well as interactions within the bone microenvironment, actively participates in regulating bone integrity and aging. The maintenance of cellular homeostasis is dependent on the regulation of intracellular organelles, thus understanding the impact of mitochondrial functional changes on overall bone metabolism is crucially important. Recent studies have revealed that mitochondrial homeostasis can lead to morphological and functional abnormalities in senescent cells, particularly in the context of bone diseases. Mitochondrial dysfunction in skeletal diseases results in abnormal metabolism of bone-associated cells and a secondary dysregulated microenvironment within bone tissue. This imbalance in the oxidative system and immune disruption in the bone microenvironment ultimately leads to bone dysplasia. In this review, we examine the latest developments in mitochondrial respiratory chain regulation and its impacts on maintenance of bone health. Specifically, we explored whether enhancing mitochondrial function can reduce the occurrence of bone cell deterioration and improve bone metabolism. These findings offer prospects for developing bone remodeling biology strategies to treat age-related degenerative diseases.

METTL14 promotes chondrocyte ferroptosis in osteoarthritis via m6A modification of GPX4

BACKGROUND

Ferroptosis is caused by iron-dependent peroxidation of membrane phospholipids and chondrocyte ferroptosis contributes to osteoarthritis (OA) progression. Glutathione peroxidase 4 (GPX4) plays a master role in blocking ferroptosis. N6-methyladenosine (m6A) is an epigenetic modification among mRNA post-transcriptional modifications. This study investigated the effect of methyltransferase-like 14 (METTL14), the key component of the m6A methyltransferase, on chondrocyte ferroptosis via m6A modification.

METHODS

An OA rat model was established through an intra-articular injection of monosodium iodoacetate in the right knee. OA cartilages in rat models were used for gene expression analysis. Primary mouse chondrocytes or ADTC5 cells were stimulated with IL-1β or erastin. The m6A RNA methylation quantification kit was used to measure m6A level. The effect of METTL14 and GPX4 on ECM degradation and ferroptosis was investigated through western blotting, fluorescence immunostaining, propidium iodide staining, and commercially available kits. The mechanism of METTL14 action was explored through MeRIP-qPCR assays.

RESULTS

METTL14 and m6A expression was upregulated in osteoarthritic cartilages and IL-1β-induced chondrocytes. METTL14 depletion repressed the IL-1β or erastin-stimulated ECM degradation and ferroptosis in mouse chondrocytes. METTL14 inhibited GPX4 gene through m6A methylation modification. GPX4 knockdown reversed the si-METTL14-mediated protection in IL-1β-induced chondrocytes.

CONCLUSION

METTL14 depletion inhibits ferroptosis and ECM degradation by suppressing GPX4 mRNA m6A modification in injured chondrocytes.

Pain Relief, Functional Recovery, and Chondroprotective Effects of Angelica gigas Nakai in Osteoarthritis Due to Its Anti-Inflammatory Property: An In Vitro and In Vivo Study

Osteoarthritis (OA), characterized by chronic pain and joint degradation, is a progressive joint disease primarily induced by age-related systemic inflammation. Angelica gigas Nakai (AG), a medicinal plant widely used in East Asia, exhibits promising results for such conditions. This study aimed to evaluate the potential of AG as a drug candidate for modulating the multifaceted pathology of OA based on its anti-inflammatory properties. We evaluated the efficacy of AG in pain relief, functional improvement, and cartilage erosion delay using monosodium iodoacetate-induced OA rats and acetic acid-induced writhing mice, along with its anti-inflammatory effects on multiple targets in the serum and cartilage of in vivo models and lipopolysaccharide-stimulated RAW 264.7 cells. In vivo experiments demonstrated significant analgesic and chondroprotective effects of AG, along with functional recovery, in model animals compared with the active controls. AG dose-dependently modulated inflammatory OA pathology-related targets, including interleukin-1β, tumor necrosis factor-α, matrix metalloproteinase-13, and cyclooxygenase-2, both in vitro and in vivo. In conclusion, AG could be a potential drug candidate for modulating the multifaceted pathology of OA. Nevertheless, further comprehensive investigations, involving a broader range of compounds, pathologies, and mechanisms, are warranted to validate these findings.

Characterizing mitochondrial features in osteoarthritis through integrative multi-omics and machine learning analysis

Purpose

Osteoarthritis (OA) stands as the most prevalent joint disorder. Mitochondrial dysfunction has been linked to the pathogenesis of OA. The main goal of this study is to uncover the pivotal role of mitochondria in the mechanisms driving OA development.

Materials and methods

We acquired seven bulk RNA-seq datasets from the Gene Expression Omnibus (GEO) database and examined the expression levels of differentially expressed genes related to mitochondria in OA. We utilized single-sample gene set enrichment analysis (ssGSEA), gene set enrichment analysis (GSEA), and weighted gene co-expression network analysis (WGCNA) analyses to explore the functional mechanisms associated with these genes. Seven machine learning algorithms were utilized to identify hub mitochondria-related genes and develop a predictive model. Further analyses included pathway enrichment, immune infiltration, gene-disease relationships, and mRNA-miRNA network construction based on these hub mitochondria-related genes. genome-wide association studies (GWAS) analysis was performed using the Gene Atlas database. GSEA, gene set variation analysis (GSVA), protein pathway analysis, and WGCNA were employed to investigate relevant pathways in subtypes. The Harmonizome database was employed to analyze the expression of hub mitochondria-related genes across various human tissues. Single-cell data analysis was conducted to examine patterns of gene expression distribution and pseudo-temporal changes. Additionally, The real-time polymerase chain reaction (RT-PCR) was used to validate the expression of these hub mitochondria-related genes.

Results

In OA, the mitochondria-related pathway was significantly activated. Nine hub mitochondria-related genes (SIRT4, DNAJC15, NFS1, FKBP8, SLC25A37, CARS2, MTHFD2, ETFDH, and PDK4) were identified. They constructed predictive models with good ability to predict OA. These genes are primarily associated with macrophages. Unsupervised consensus clustering identified two mitochondria-associated isoforms that are primarily associated with metabolism. Single-cell analysis showed that they were all expressed in single cells and varied with cell differentiation. RT-PCR showed that they were all significantly expressed in OA.

Conclusion

SIRT4, DNAJC15, NFS1, FKBP8, SLC25A37, CARS2, MTHFD2, ETFDH, and PDK4 are potential mitochondrial target genes for studying OA. The classification of mitochondria-associated isoforms could help to personalize treatment for OA patients.

HDAC4 represses ER stress induced chondrocyte apoptosis by inhibiting ATF4 and attenuates cartilage degeneration in an osteoarthritis rat model

BACKGROUND

The present study evaluated whether the lack of histone deacetylase 4 (HDAC4) increases endoplasmic reticulum stress-induced chondrocyte apoptosis by releasing activating transcription factor 4 (ATF4) in human osteoarthritis (OA) cartilage degeneration.

METHODS

Articular cartilage from the tibial plateau was obtained from patients with OA during total knee replacement. Cartilage extracted from severely damaged regions was classified as degraded cartilage, and cartilage extracted from a relatively smooth region was classified as preserved cartilage. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining was used to detect chondrocyte apoptosis. HDAC4, ATF4, and C/EBP homologous protein (CHOP) expression levels were measured using immunohistochemistry staining and real-time quantitative PCR. Chondrocytes were transfected with HDAC4 or HDAC4 siRNA for 24 h and stimulated with 300 µM H2O2 for 12 h. The chondrocyte apoptosis was measured using flow cytometry. ATF4, CHOP, and caspase 12 expression levels were measured using real-time quantitative PCR and western blotting. Male Sprague-Dawley rats (n = 15) were randomly divided into three groups and transduced with different vectors: ACLT + Ad-GFP, ACLT + Ad-HDAC4-GFP, and sham + Ad-GFP. All rats received intra-articular injections 48 h after the operation and every three weeks thereafter. Cartilage damage was assessed using Safranin O staining and quantified using the Osteoarthritis Research Society International score. ATF4, CHOP, and collagen II expression were detected using immunohistochemistry, and chondrocyte apoptosis was detected using terminal deoxynucleotidyl transferase dUTP nick end labeling staining.

RESULTS

The chondrocyte apoptosis was higher in degraded cartilage than in preserved cartilage. HDAC4 expression was lower in degraded cartilage than in preserved cartilage. ATF4 and CHOP expression was increased in degraded cartilage. Upregulation of HDAC4 in chondrocytes decreased the expression of ATF4, while the expression of ATF4 was increased after downregulation of HDAC4. Upregulation of HDAC4 decreased the chondrocyte apoptosis under endoplasmic reticulum stress, and chondrocyte apoptosis was increased after downregulation of HDAC4. In a rat anterior cruciate ligament transection OA model, adenovirus-mediated transduction of HDAC4 was administered by intra-articular injection. We detected a stronger Safranin O staining with lower Osteoarthritis Research Society International scores, lower ATF4 and CHOP production, stronger collagen II expression, and lower chondrocyte apoptosis in rats treated with Ad-HDAC4.

CONCLUSION

The lack of HDAC4 expression partially contributes to increased ATF4, CHOP, and endoplasmic reticulum stress-induced chondrocyte apoptosis in OA pathogenesis. HDAC4 attenuates cartilage damage by repressing ATF4-CHOP signaling-induced chondrocyte apoptosis in a rat model of OA.

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.

Arrestin beta-2 deficiency exacerbates periodontal inflammation by mediating activating transcription factor 6 activation and abnormal remodelling of the extracellular matrix

AIM

To investigate the specific role of arrestin beta-2 (ARRB2) in the progression of periodontitis and the underlying mechanisms.

MATERIALS AND METHODS

Single-cell RNA sequencing data were used to analyse gene expression in periodontal tissues from healthy controls and patients with periodontitis. Real-time quantitative polymerase chain reaction, Western blotting and immunohistochemical staining were performed to detect the expression of ARRB2. Furthermore, a ligature-induced periodontitis model was created. Using radiographic and histological methods, RNA sequencing and luciferase assay, the role of ARRB2 in periodontitis and the underlying mechanisms were explored. Finally, the therapeutic effect of melatonin, an inhibitor of activating transcription factor 6 (ATF6), on periodontitis in mice was assessed in both in vivo and in vitro experiments.

RESULTS

ARRB2 expression was up-regulated in inflammatory periodontal tissue. In the ligature-induced mouse model, Arrb2 knockout exacerbated alveolar bone loss (ABL) and extracellular matrix (ECM) degradation. ARRB2 exerted a negative regulatory effect on ATF6, an essential targeted gene. Melatonin ameliorated ABL and an imbalance in ECM remodelling in Arrb2-deficient periodontitis mice.

CONCLUSIONS

ARRB2 mediates ECM remodelling via inhibition of the ATF6 signalling pathway, which ultimately exerts a protective effect on periodontal tissues.

Melatonin and oral diseases: possible therapeutic roles based on cellular mechanisms

Oral diseases, including periodontal disorders, oral cancer, periodontitis, and mucositis are the major challenges for both patients and healthcare providers. These conditions often involve inflammation, oxidative stress, and impaired cellular processes, leading to symptoms ranging from discomfort to severe debilitation. Conventional treatments for such oral diseases exhibit constraints, prompting the investigation of innovative therapeutic approaches. Considering the anti-inflammatory, anti-oxidant, and anti-cancer effects of melatonin, this study was carried out to investigate the potential protective effects of melatonin in mitigating the severity of oral diseases. Studies indicate that melatonin influences the differentiation of periodontal stem cells, inhibits oral cancer progression, reduces inflammation associated with periodontitis, and alleviates the severity of oral mucositis. Melatonin has demonstrated potential efficacy in both preclinical and clinical investigations; however, findings are frequently heterogeneous and contingent upon contextual factors. This review provides a comprehensiveoverview of current state of knowledge in this domain, elucidating the multifaceted role that melatonin may assume in combatingoral diseases. Further research should be directed toward determining the most effective dosing, timing, and administration methods for melatonin-based therapies for oral diseases.

Excessive load promotes temporomandibular joint chondrocyte apoptosis via Piezo1/endoplasmic reticulum stress pathway

Excessive load on the temporomandibular joint (TMJ) is a significant factor in the development of TMJ osteoarthritis, contributing to cartilage degeneration. The specific mechanism through which excessive load induces TMJ osteoarthritis is not fully understood; however, mechanically-activated (MA) ion channels play a crucial role. Among these channels, Piezo1 has been identified as a mediator of chondrocyte catabolic responses and is markedly increased in osteoarthritis. Our observations indicate that, under excessive load conditions, endoplasmic reticulum stress in chondrocytes results in apoptosis of the TMJ chondrocytes. Importantly, using the Piezo1 inhibitor GsMTx4 demonstrates its potential to alleviate this condition. Furthermore, Piezo1 mediates endoplasmic reticulum stress in chondrocytes by inducing calcium ion influx. Our research substantiates the role of Piezo1 as a pivotal ion channel in mediating chondrocyte overload. It elucidates the link between excessive load, cell apoptosis, and calcium ion influx through Piezo1. The findings underscore Piezo1 as a key player in the pathogenesis of TMJ osteoarthritis, shedding light on potential therapeutic interventions for this condition.

The metabolic characteristics and changes of chondrocytes in vivo and in vitro in osteoarthritis

Osteoarthritis (OA) is an intricate pathological condition that primarily affects the entire synovial joint, especially the hip, hand, and knee joints. This results in inflammation in the synovium and osteochondral injuries, ultimately causing functional limitations and joint dysfunction. The key mechanism responsible for maintaining articular cartilage function is chondrocyte metabolism, which involves energy generation through glycolysis, oxidative phosphorylation, and other metabolic pathways. Some studies have shown that chondrocytes in OA exhibit increased glycolytic activity, leading to elevated lactate production and decreased cartilage matrix synthesis. In OA cartilage, chondrocytes display alterations in mitochondrial activity, such as decreased ATP generation and increased oxidative stress, which can contribute to cartilage deterioration. Chondrocyte metabolism also involves anabolic processes for extracellular matrix substrate production and energy generation. During OA, chondrocytes undergo considerable metabolic changes in different aspects, leading to articular cartilage homeostasis deterioration. Numerous studies have been carried out to provide tangible therapies for OA by using various models in vivo and in vitro targeting chondrocyte metabolism, although there are still certain limitations. With growing evidence indicating the essential role of chondrocyte metabolism in disease etiology, this literature review explores the metabolic characteristics and changes of chondrocytes in the presence of OA, both in vivo and in vitro. To provide insight into the complex metabolic reprogramming crucial in chondrocytes during OA progression, we investigate the dynamic interaction between metabolic pathways, such as glycolysis, lipid metabolism, and mitochondrial function. In addition, this review highlights prospective future research directions for novel approaches to diagnosis and treatment. Adopting a multifaceted strategy, our review aims to offer a comprehensive understanding of the metabolic intricacies within chondrocytes in OA, with the ultimate goal of identifying therapeutic targets capable of modulating chondrocyte metabolism for the treatment of OA.

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.

Reactive oxygen species-scavenging nanomaterials for the prevention and treatment of age-related diseases

With increasing proportion of the elderly in the population, age-related diseases (ARD) lead to a considerable healthcare burden to society. Prevention and treatment of ARD can decrease the negative impact of aging and the burden of disease. The aging rate is closely associated with the production of high levels of reactive oxygen species (ROS). ROS-mediated oxidative stress in aging triggers aging-related changes through lipid peroxidation, protein oxidation, and DNA oxidation. Antioxidants can control autoxidation by scavenging free radicals or inhibiting their formation, thereby reducing oxidative stress. Benefiting from significant advances in nanotechnology, a large number of nanomaterials with ROS-scavenging capabilities have been developed. ROS-scavenging nanomaterials can be divided into two categories: nanomaterials as carriers for delivering ROS-scavenging drugs, and nanomaterials themselves with ROS-scavenging activity. This study summarizes the current advances in ROS-scavenging nanomaterials for prevention and treatment of ARD, highlights the potential mechanisms of the nanomaterials used and discusses the challenges and prospects for their applications.

Integrated Network Pharmacology and Experimental Validation Approach to Investigate the Mechanisms of Radix Rehmanniae Praeparata - Angelica Sinensis - Radix Achyranthis Bidentatae in Treating Knee Osteoarthritis

Background

Knee osteoarthritis (KOA) is a persistent degenerative condition characterized by the deterioration of cartilage. The Chinese herbal formula Radix Rehmanniae Praeparata- Angelica Sinensis-Radix Achyranthis Bidentatae (RAR) has often been used in effective prescriptions for KOA as the main functional drug, but its underlying mechanism remains unclear. Therefore, network pharmacology and verification experiments were employed to investigate the impact and mode of action of RAR in the treatment of KOA.

Methods

The destabilization of the medial meniscus model (DMM) was utilized to assess the anti-KOA effect of RAR by using gait analysis, micro-computed tomography (Micro-CT), and histology. Primary chondrocytes were extracted from the rib cartilage of a newborn mouse. The protective effects of RAR on OA cells were evaluated using a CCK-8 assay. The antioxidative effect of RAR was determined by measuring reactive oxygen species (ROS), superoxide dismutase (SOD), and glutathione (GSH) production. Furthermore, network pharmacology and molecular docking were utilized to propose possible RAR targets for KOA, which were further verified through experiments.

Results

In vivo, RAR significantly ameliorated DMM-induced KOA characteristics, such as subchondral bone sclerosis, cartilage deterioration, gait abnormalities, and the degree of knee swelling. In vitro, RAR stimulated chondrocyte proliferation and the expression of Col2a1, Comp, and Acan. Moreover, RAR treatment significantly reduced ROS accumulation in an OA cell model induced by IL-1β and increased the activity of antioxidant enzymes (SOD and GSH). Network pharmacology analysis combined with molecular docking showed that Mapk1 might be a key therapeutic target. Subsequent research showed that RAR could downregulate Mapk1 mRNA levels in IL-1β-induced chondrocytes and DMM-induced rats.

Conclusion

RAR inhibited extracellular matrix (ECM) degradation and oxidative stress response via the MAPK signaling pathway in KOA, and Mapk1 may be a core target.

Melatonin: Current evidence on protective and therapeutic roles in gynecological diseases

Melatonin, a potent antioxidant and free radical scavenger, has been demonstrated to be effective in gynecological conditions and female reproductive cancers. This review consolidates the accumulating evidence on melatonin's multifaceted protective effects in different pathological contexts. In gynecological conditions such as endometriosis, polycystic ovary syndrome (PCOS), and uterine leiomyoma, melatonin has shown promising effects in reducing oxidative stress, inflammation, and hormonal imbalances. It inhibits adhesion molecules' production, and potentially mitigates leukocyte adherence and inflammatory responses. Melatonin's regulatory effects on hormone production and insulin sensitivity in PCOS individuals make it a promising candidate for improving oocyte quality and menstrual irregularities. Moreover, melatonin exhibits significant antitumor effects by modulating various signaling pathways, promoting apoptosis, and suppressing metastasis in breast cancers and gynecological cancers, including ovarian, endometrial, and cervical cancers. Furthermore, melatonin's protective effects are suggested to be mediated by interactions with its receptors, estrogen receptors and other nuclear receptors. The regulation of clock-related genes and circadian clock systems may also contribute to its inhibitory effects on cancer cell growth. However, more comprehensive research is warranted to fully elucidate the underlying molecular mechanisms and establish melatonin as a potential therapeutic agent for these conditions.

Tanshinone IIA alleviates IL-1β-induced chondrocyte apoptosis and inflammation by regulating FBXO11 expression

OBJECTIVE

This study explored the pharmacological mechanism of Tanshinone IIA (TAN IIA) in the treatment of Osteoarthritis (OA), which provided a certain reference for further research and clinical application of Tan IIA in OA.

METHODS

CHON-001 cells were stimulated with 10 μg/mL IL-1β for 48 h and treated with 10 μM TAN IIA for 48 h. Cellular viability and apoptosis were evaluated by CCK-8 assay and flow cytometry, and Cleaved caspase-3 was measured by Immunoblot assay and RT-qPCR. TNF-α, IL-6, and iNOS in CHON-001 cells were determined by RT-qPCR and ELISA. To further verify the effect of TAN IIA on OA, a rat model of OA in vivo was established by right anterior cruciate ligament transection. TAN IIA was administered at 50 mg/kg or 150 mg/kg for 7 weeks. The degree of cartilage destruction in OA rats was observed by TUNEL and HE staining. Cleaved caspase-3 and FBXO11 were measured by immunohistochemical staining, RT-qPCR, and Immunoblot. TNF-α, IL-6, and iNOS in chondrocytes of OA rats were detected by ELISA.

RESULTS

IL-1β stimulated CHON-001 cell apoptosis and inflammation, and TAN IIA had anti-apoptosis and anti-inflammatory effects on IL-1β-regulated CHON-001 cells. TAN IIA down-regulated FBXO11 and inhibited PI3K/AKT and NF-κB pathways, thereby alleviating apoptotic and inflammatory reactions in CHON-001 cells under IL-1β treatment. Moreover, TAN IIA treatment improved chondrocyte apoptosis and inflammations in OA rats.

CONCLUSION

TAN IIA inhibits PI3K/Akt and NF-κB pathways by down-regulating FBXO11 expression, alleviates chondrocyte apoptosis and inflammation, and delays the progression of OA.

Mechanisms of chondrocyte regulated cell death in osteoarthritis: Focus on ROS-triggered ferroptosis, parthanatos, and oxeiptosis

Osteoarthritis (OA) is a common chronic inflammatory degenerative disease. Since chondrocytes are the only type of cells in cartilage, their survival is critical for maintaining cartilage morphology. This review offers a comprehensive analysis of how reactive oxygen species (ROS), including superoxide anions, hydrogen peroxide, hydroxyl radicals, nitric oxide, and their derivatives, affect cartilage homeostasis and trigger several novel modes of regulated cell death, including ferroptosis, parthanatos, and oxeiptosis, which may play roles in chondrocyte death and OA development. Moreover, we discuss potential therapeutic strategies to alleviate OA by scavenging ROS and provide new insight into the research and treatment of the role of regulated cell death in OA.

SIRT3 alleviates high glucose-induced chondrocyte injury through the promotion of autophagy and suppression of apoptosis in osteoarthritis progression

A growing amount of epidemiological evidence proposes diabetes mellitus (DM) to be an independent risk factor for osteoarthritis (OA). Sirtuin 3 (SIRT3), which is mainly located in mitochondria, belongs to the family of nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylases and is involved in the physiological and pathological processes of cell regulation. The aim of this study was to investigate the effects of SIRT3 on diabetic OA and underlying mechanisms in the prevention of type 2 DM (T2DM)-induced articular cartilage damage. High-fat and high-sugar diets combined with streptozotocin (STZ) injection were used for establishing an experimental T2DM rat model. The destabilization of medial meniscus (DMM) surgery was applied to induce the rat OA model. Primary rat chondrocytes were cultivated with a concentration of gradient glucose. Treatment with intra-articular injection of SIRT3 overexpression lentivirus was achieved in vivo, and intervention with SIRT3 knockdown was performed using siRNA transfection in vitro. High glucose content was found to activate inflammatory response, facilitate apoptosis, downregulate autophagy, and exacerbate mitochondrial dysfunction in a dose-dependent manner in rat chondrocytes, which can be deteriorated by SIRT3 knockdown. In addition, articular cartilage damage was found to be more severe in T2DM-OA rats than in DMM-induced OA rats, which can be mitigated by the intra-articular injection of SIRT3 overexpression lentivirus. Targeting SIRT3 is a potential therapeutic strategy for the alleviation of diabetic OA.

PPARδ agonist protects against osteoarthritis by activating AKT/mTOR signaling pathway-mediated autophagy

Osteoarthritis (OA) is the most prevalent degenerative joint disease, and PPARs are involved in its pathogenesis; however, the specific mechanisms by which changes in PPARδ impact the OA pathogenesis yet to be discovered. The purpose of this study was to ascertain how PPARδ affects the onset and development of OA. In vitro, we found that PPARδ activation ameliorated apoptosis and extracellular matrix (ECM) degradation in OA chondrocytes stimulated by IL-1β. In addition, PPARδ activation may modulate AKT/mTOR signaling to partially regulate chondrocyte autophagy and apoptosis. In vivo, injection of PPARδ agonist into the articular cavity improved ECM degradation, apoptosis and autophagy in rats OA models generated by destabilization medial meniscus (DMM), eventually delayed degeneration of articular cartilage. Thus, targeting PPARδ for OA treatment may be a possibility.

Recent understanding of the mechanisms of the biological activities of hesperidin and hesperetin and their therapeutic effects on diseases

Flavonoids are natural phytochemicals that have therapeutic effects and act in the prevention of several pathologies. These phytochemicals can be found in lemon, sweet orange, bitter orange, clementine. Hesperidin and hesperetin are citrus flavonoids from the flavanones subclass that have anti-inflammatory, antioxidant, antitumor and antibacterial potential. Preclinical studies and clinical trials demonstrated therapeutical effects of hesperidin and its aglycone hesperetin in various diseases, such as bone diseases, cardiovascular diseases, neurological diseases, respiratory diseases, digestive diseases, urinary tract diseases. This review provides a comprehensive overview of the biological activities of hesperidin and hesperetin, their therapeutic potential in various diseases and their associated molecular mechanisms. This article also discusses future considerations for the clinical applications of hesperidin and hesperetin.

Pt-Se Hybrid Nanozymes with Potent Catalytic Activities to Scavenge ROS/RONS and Regulate Macrophage Polarization for Osteoarthritis Therapy

The activation of pro-inflammatory M1-type macrophages by overexpression of reactive oxygen species (ROS) and reactive nitrogen species (RONS) in synovial membranes contributes to osteoarthritis (OA) progression and cartilage matrix degradation. Here, combing Pt and Se with potent catalytic activities, we developed a hybrid Pt-Se nanozymes as ROS and RONS scavengers to exert synergistic effects for OA therapy. As a result, Pt-Se nanozymes exhibited efficient scavenging effect on ROS and RONS levels, leading to repolarization of M1-type macrophages. Furthermore, the polarization of synovial macrophages to the M2 phenotype inhibited the expression of pro-inflammatory factors and salvaged mitochondrial function in arthritic chondrocytes. In vivo results also suggest that Pt-Se nanozymes effectively suppress the early progression of OA with an Osteoarthritis Research International Association score reduction of 68.21% and 82.66% for 4 and 8 weeks, respectively. In conclusion, this study provides a promising strategy to regulate inflammatory responses by macrophage repolarization processes for OA therapeutic.

Beyond Traditional Medicine: EVs-Loaded Hydrogels as a Game Changer in Disease Therapeutics

Extracellular vesicles (EVs), especially exosomes, have shown great therapeutic potential in the treatment of diseases, as they can target cells or tissues. However, the therapeutic effect of EVs is limited due to the susceptibility of EVs to immune system clearance during transport in vivo. Hydrogels have become an ideal delivery platform for EVs due to their good biocompatibility and porous structure. This article reviews the preparation and application of EVs-loaded hydrogels as a cell-free therapy strategy in the treatment of diseases. The article also discusses the challenges and future outlook of EVs-loaded hydrogels.

Evaluation of possible cytotoxic, genotoxic and epigenotoxic effects of titanium dioxide nanoparticles and possible protective effect of melatonin

Nanoparticles (NPs) are particles of matter that are between 1 to 100 nm in diameter. They are suggested to cause toxic effects in both humans and environment thorough different mechanisms. However, their toxicity profile may be different from the parent material. Titanium dioxide (TiO2) NPs are widely used in cosmetic, pharmaceutical and food industries. As a white pigment, the use of TiO2 is used in food coloring, industrial paints, clothing and UV filters has increased tremendously in recent years. Melatonin, on the other hand, is a well-known antioxidant and may prevent oxidative stress caused by a variety of different substances, including NPs. In the current study, we aimed to comparatively investigate the effects of normal-sized TiO2 (220 nm) and nano-sized TiO2 (21 nm) on cytopathology, cytotoxicity, oxidative damage (lipid peroxidation, protein oxidation and glutathione), genotoxicity (8-hydroxydeoxyguanosine), apoptosis (caspase 3, 8 and 9) and epigenetic alterations (global DNA methylation, H3 acetylation) on 3T3 fibroblast cells. In addition, the possible protective effects of melatonin, which is known to have strong antioxidant effects, against the toxicity of TiO2 were also evaluated. Study groups were: a. the control group; b. melatonin group; c. TiO2 group; d. nano-sized TiO2 group; e. TiO2 + melatonin group and f. nano-sized TiO2 + melatonin group. We observed that both normal-sized and nano-sized TiO2 NPs showed significant toxic effects. However, TiO2 NPs caused higher DNA damage and global DNA methylation compared to normal-sized TiO2 whereas normal-sized TiO2 led to lower H3 acetylation vs. TiO2 NPs. Melatonin showed partial protective effect against the toxicity caused by TiO2 NPs.

The protective effect of Ergolide in osteoarthritis: In vitro and in vivo studies

Osteoarthritis (OA), a prevalent degenerative condition, occurs due to the deterioration of joint tissues and cells. Consequently, safeguarding chondrocytes against damage caused by inflammation is an area of future research emphasis. There is growing evidence that Ergolide (ERG) has multiple biological functions. Nevertheless, it is still uncertain whether it can hinder the advancement of OA. In this study, we investigate the ERG's potential to reduce inflammation and protect cartilage. ERG treatment in vitro effectively inhibited the excessive production of pro-inflammatory substances, such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX2), and tumor necrosis factor-α (TNF-α), leading to their complete suppression. Furthermore, ERG suppressed the production of matrix-degrading enzymes (ADAMTS-5) and matrix metalloproteinase 13 (MMP13), consequently impeding the breakdown of extracellular matrix (ECM) and restraining the synthesis of collagenase II and Aggrecan. Through the P38/MAPK pathway, we discovered that ERG hinders the activation of NF-κB in chondrocytes induced by IL-1β. The protective effect of ERG was enhanced by the p38 MAPK inhibitor SB203580. In vivo, ERG further demonstrated protective effects on cartilage in animal models of DMM. In conclusion, the study has discovered that ERG exhibits innovative therapeutic potential in the context of OA.

Therapeutic targets and potential delivery systems of melatonin in osteoarthritis

Osteoarthritis (OA) is a highly prevalent age-related musculoskeletal disorder that typically results in chronic pain and disability. OA is a multifactorial disease, with increased oxidative stress, dysregulated inflammatory response, and impaired matrix metabolism contributing to its onset and progression. The neurohormone melatonin, primarily synthesized by the pineal gland, has emerged as a promising therapeutic agent for OA due to its potential to alleviate inflammation, oxidative stress, and chondrocyte death with minimal adverse effects. The present review provides a comprehensive summary of the current understanding regarding melatonin as a promising pharmaceutical agent for the treatment of OA, along with an exploration of various delivery systems that can be utilized for melatonin administration. These findings may provide novel therapeutic strategies and targets for inhibiting the advancement of OA.

Melatonin enhances captopril mediated cardioprotective effects and improves mitochondrial dynamics in male Wistar rats with chronic heart failure

Mitochondrial dysfunction is a recent emerging research scope that proved to be involved in many cardiovascular diseases culminating in chronic heart failure (CHF), which remains one of the primary causes of morbidity and mortality. This study investigated the added cardio-protective effects of exogenous melatonin administration to conventional captopril therapy in isoproterenol (ISO) exposed rats with CHF. Five groups of Wistar rats were recruited; (I): Control group, (II): (ISO group), (III): (ISO + captopril group), (IV): (ISO + melatonin group) and (V): (ISO + melatonin/captopril group). Cardiac function parameters and some oxidant, inflammatory and fibrotic markers were investigated. Moreover; mRNA expression of mitochondrial mitophagy [parkin & PTEN induced kinase 1 (PINK1)], biogenesis [Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α)], fusion [mitofusin 2 (Mfn2)] and fission [dynamin-related protein 1 (DRP-1)] parameters in rat's myocardium were evaluated. Rats' myocardium was histo-pathologically and immunohistochemically evaluated for Beclin1 and Sirt3 expression. The present study revealed that captopril and melatonin ameliorated cardiac injury, oxidative stress biomarkers, and pro-inflammatory cytokines in ISO-exposed rats. These protective effects could be attributed to mitochondrial dynamic proteins control (i.e. enhanced the mRNA expression of parkin, PINK1, PGC-1α and Mfn2, while reduced DRP-1 mRNA expression). Also, Beclin1 and Sirt3 cardiac immunoreactivity were improved. Combined captopril and melatonin therapy showed a better response than either agent alone. Melatonin enhanced myocardial mitochondrial dynamics and Sirt3 expression in CHF rats and may represent a promising upcoming therapy added to conventional heart failure treatment.

Integrated Analysis of DNA Methylation and Gene Expression Profiles in a Rat Model of Osteoarthritis

Osteoarthritis (OA) is common and affected by several factors, such as age, weight, sex, and genetics. The pathogenesis of OA remains unclear. Therefore, using a rat model of monosodium iodoacetate (MIA)-induced OA, we examined genomic-wide DNA methylation using methyl-seq and characterized the transcriptome using RNA-seq in the articular cartilage tissue from a negative control (NC) and MIA-induced rats. We identified 170 genes (100 hypomethylated and upregulated genes and 70 hypermethylated and downregulated genes) regulated by DNA methylation in OA. DNA methylation-regulated genes were enriched in functions related to focal adhesion, extracellular matrix (ECM)-receptor interaction and the PI3K-Akt and Hippo signaling pathways. Functions related to extracellular matrix organization, extracellular matrix proteoglycans, and collagen formation were involved in OA. A molecular and protein-protein network was constructed using methylated expression-correlated genes. Erk1/2 was a downstream target of OA-induced changes in DNA methylation and RNA expression. We found that the integrin subunit alpha 2 (ITGA2) gene is important in focal adhesion, alpha6-beta4 integrin signaling, and the inflammatory response pathway in OA. Overall, gene expression changes because DNA methylation influences OA pathogenesis. ITGA2, whose gene expression changes are regulated by DNA methylation during OA onset, is a candidate gene. Our findings provide insights into the epigenetic targets of OA processes in rats.

Exploration and breakthrough in the mode of chondrocyte death - A potential new mechanism for osteoarthritis

Osteoarthritis (OA) is a frequent chronic joint disease in orthopedics that effects individuals and society significantly. Obesity, aging, genetic susceptibility, and joint misalignment are all known risk factors for OA, but its pathomechanism is still poorly understood. Researches have revealed that OA is a much complex process related to inflammation, metabolic and chondrocyte death. It can affect all parts of the joint and is characterized by causing chondrocyte death and extracellular matrix descent. Previously, OA was thought to develop from excessive mechanical loading leading to the destruction of articular cartilage. Since some programmed cell deaths and OA share a pattern of chondrocyte destruction, it is likely that OA also involves programmed cell death. Even though chondrocyte apoptosis and pyroptosis have been investigated in OA, clarifing solely conventional cell death pathways is still insufficient to understand the pathophysiology of osteoarthritis. With more researches, it has been discovered that osteoarthritis and other new cell death processes, including PANoptosis, ferroptosis, and cell senescence, are strongly associated. Among these, PANoptosis combines the key traits of pyroptosis, cell apoptosis, and necrotic apoptosis into a highly coordinated and dynamically balanced programmed inflammatory cell death mechanism. Furthermore, we think that PANopotosis might obstruct necroptosis and cell senescence. Therefore, in order to offer direction for therapeutic treatment, we evaluate the development of research on multiple cell death of chondrocytes in OA.

Role of Apoptosis in the Pathogenesis of Osteoarthritis: An Explicative Review

Apoptosis is a complex regulatory, active cell death process that plays a role in cell development, homeostasis, and ageing. Cancer, developmental defects, and degenerative diseases are all pathogenic disorders caused by apoptosis dysregulation. Osteoarthritis (OA) is by far the most frequently diagnosed joint disease in the aged, and it is characterized by the ongoing breakdown of articular cartilage, which causes severe disability. Multiple variables regulate the anabolic and catabolic pathways of the cartilage matrix, which either directly or indirectly contribute to cartilage degeneration in osteoarthritis. Articular cartilage is a highly specialized tissue made up of an extracellular matrix of cells that are tightly packed together. As a result, chondrocyte survival is crucial for the preservation of an optimal cartilage matrix, and chondrocyte characteristics and survival compromise may result in articular cartilage failure. Inflammatory cytokines can either promote or inhibit apoptosis, the process of programmed cell death. Pro-apoptotic cytokines like TNF-α can induce cell death, while anti-apoptotic cytokines like IL-4 and IL-10 protect against apoptosis. The balance between these cytokines plays a critical role in determining cell fate and has implications for tissue damage and disease progression. Similarly, they contribute to the progression of OA by disrupting the metabolic balance in joint tissues by promoting catabolic and anabolic pathways. Their impact on cell joints, as well as the impacts of cell signalling pathways on cytokines and inflammatory substances, determines their function in osteoarthritis development. Apoptosis is evident in osteoarthritic cartilage; however, determining the relative role of chondrocyte apoptosis in the aetiology of OA is difficult, and the rate of apoptotic chondrocytes in osteoarthritic cartilage is inconsistent. The current study summarises the role of apoptosis in the development of osteoarthritis, the mediators, and signalling pathways that trigger the cascade of events, and the other inflammatory features involved.

Evaluating the Protective Effect of Melatonin on Atorvastatin-induced Mitochondrial Toxicity in Pancreatic Beta Cells

BACKGROUND

Atorvastatin and other statins belong to a category of cholesterollowering drugs, which may cause some damage to pancreatic cells despite their effectiveness.

AIMS

The present study investigated the effects of melatonin against atorvastatin-induced toxicity on islets of Langerhans and CRI-D2 cells.

METHODS

The MTT assay was used to determine cell viability. The effect of various concentrations of melatonin (0,10, 50, 100, 250, 500 and 1000 μM) on CRI-D2 cell viability was evaluated for 24 hours to determine the non-cytotoxic concentrations of melatonin. Additionally, cells were treated with different concentrations of atorvastatin (10, 100, and 150 ng/mL) for 24 hours to determine a concentration that could induce the maximum cell death. After selecting the appropriate concentrations for melatonin, cells were treated with atorvastatin (10, 100, and 150 ng/ml) and melatonin (10 and 100 μM) simultaneously for a period of 24 hours. Malondialdehyde (MDA), reactive oxygen species (ROS), superoxide dismutase, catalase, and glutathione peroxidase activity were assessed as indicators of oxidative stress. To assess mitochondrial function, the ratio of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP) were measured.

RESULTS

Atorvastatin markedly raised ROS and MDA levels. This result was associated with a decrease in MMP, an increase in the ADP/ATP ratio, and a change in the activity of antioxidant enzymes. Atorvastatin (150 ng/mL)-induced mitochondrial damage was alleviated by concurrent melatonin and atorvastatin therapy.

CONCLUSION

These results suggest that melatonin has a protective effect against atorvastatininduced toxicity in the mitochondria of pancreatic cells.

New insight of the pathogenesis in osteoarthritis: the intricate interplay of ferroptosis and autophagy mediated by mitophagy/chaperone-mediated autophagy

Ferroptosis, characterized by iron accumulation and lipid peroxidation, is a form of iron-driven cell death. Mitophagy is a type of selective autophagy, where degradation of damaged mitochondria is the key mechanism for maintaining mitochondrial homeostasis. Additionally, Chaperone-mediated autophagy (CMA) is a biological process that transports individual cytoplasmic proteins to lysosomes for degradation through companion molecules such as heat shock proteins. Research has demonstrated the involvement of ferroptosis, mitophagy, and CMA in the pathological progression of Osteoarthritis (OA). Furthermore, research has indicated a significant correlation between alterations in the expression of reactive oxygen species (ROS), adenosine monophosphate (AMP)-activated protein kinase (AMPK), and hypoxia-inducible factors (HIFs) and the occurrence of OA, particularly in relation to ferroptosis and mitophagy. In light of these findings, our study aims to assess the regulatory functions of ferroptosis and mitophagy/CMA in the pathogenesis of OA. Additionally, we propose a mechanism of crosstalk between ferroptosis and mitophagy, while also examining potential pharmacological interventions for targeted therapy in OA. Ultimately, our research endeavors to offer novel insights and directions for the prevention and treatment of OA.

Combination of curcumin and catalase protects against chondrocyte injury and knee osteoarthritis progression by suppressing oxidative stress

Knee Osteoarthritis (KOA) is an age-related progressive degenerative joint disease, which is featured with pain, joint deformity, and disability. Accumulating evidence indicated oxidative stress plays a crucial role in the occurrence and development of KOA. Curcumin is a polyphenolic compound with significant antioxidant activity among various diseases while catalase (CAT) is an enzyme degrading hydrogen peroxide in treating oxidative diseases. We previously showed that the expression of CAT was low in cartilage. However, the combination of curcumin and CAT in KOA is still elusive. In this study, we demonstrated that the combination of curcumin and CAT has the potential to inhibit the IL1β-induced chondrocyte apoptosis without cytotoxicity in vitro. Mechanistically, we found that the synergistic application curcumin and CAT not only promotes curcumin's regulation of the NRF2/HO-1 signaling pathway to enhance antioxidant enzyme expression to remove superoxide radicals, but also CAT can further remove downstream hydrogen peroxide which enhances the ability to scavenge reactive oxygen species (ROS). In vivo, studies revealed that combination of curcumin and catalase could better inhibit oxidative stress-induced chondrocyte injury by promoting the expression of ROS scavenging enzymes. In sum, the combination of curcumin and catalase can be used to treat KOA. Thus, combination of curcumin and catalase may act as a novel therapeutic agent to manage KOA and our research gives a rationale for their combined use in the therapeutic of KOA.

Retuning Mitochondrial Apoptosis/Mitophagy Balance via SIRT3-Energized and Microenvironment-Modulated Hydrogel Microspheres to Impede Osteoarthritis

Full-range therapeutic regimens for osteoarthritis (OA) should consider organs (joints)-tissues (cartilage)-cells (chondrocytes)-organelles cascade, of which the subcellular mitochondria dominate eukaryotic cells' fate, and thus causally influence OA progression. However, the dynamic regulation of mitochondrial rise and demise in impaired chondrocytes and the exact role of mitochondrial metronome sirtuins 3 (SIRT3) is not clarified. Herein, chondrocytes are treated with SIRT3 natural agonist dihydromyricetin (DMY) or chemical antagonist 3-TYP, respectively, to demonstrate the positive action of SIRT3 on preserving cartilage extracellular matrix (ECM). Molecular mechanical investigations disclose that SIRT3-induced chondroprotection depended on the repression of mitochondrial apoptosis (mtApoptosis) and the activation of mitophagy. Inspired by the high-level matrix proteinases and reactive oxygen species (ROS) in the OA environment, by anchoring gelatin methacrylate (GelMA) and benzenediboronic acid (PBA) to hyaluronic acid methacrylate (HAMA) with microfluidic technology, a dual-responsive hydrogel microsphere laden with DMY is tactfully fabricated and named as DMY@HAMA-GelMA-PBA (DMY@HGP). In vivo injection of DMY@HGP ameliorated cartilage abrasion and subchondral bone sclerosis, as well as promoted motor function recovery in post-traumatic OA (PTOA) model via recouping endogenous mtApoptosis and mitophagy balance. Overall, this study unveils a novel mitochondrial dynamic-oriented strategy, holding great promise for the precision treatment of OA.

Plumbagin alleviates temporomandibular joint osteoarthritis progression by inhibiting chondrocyte ferroptosis via the MAPK signaling pathways

AIMS

The acceleration of osteoarthritis (OA) development by chondrocytes undergoing ferroptosis has been observed. Plumbagin (PLB), known for its potent antioxidant and anti-inflammatory properties, has demonstrated promising potential in the treatment of OA. However, it remains unclear whether PLB can impede the progression of temporomandibular joint osteoarthritis (TMJOA) through the regulation of ferroptosis. The study aims to investigate the impact of ferroptosis on TMJOA and assess the ability of PLB to modulate the inhibitory effects of ferroptosis on TMJOA.

MATERIALS AND METHODS

The study utilized an in vivo rat model of unilateral anterior crossbite (UAC)-induced TMJOA and an in vitro study of chondrocytes exposed to H2O2 to create an OA microenvironment. Various experiments including cell viability assessment, quantitative RT-PCR, western blot analysis, histology, and immunofluorescence were conducted to examine the impact of ferroptosis on TMJOA and evaluate the potential of PLB to mitigate the inhibitory effects of ferroptosis on TMJOA. Additionally, RNA-seq and bioinformatics analysis were performed to investigate the underlying mechanism by which PLB regulates ferroptosis in TMJOA.

RESULTS

Fer-1 demonstrated its potential in mitigating the advancement of TMJOA through its inhibitory effects on ferroptosis and matrix degradation in chondrocytes, thereby substantiating the role of ferroptosis in the pathogenesis of TMJOA. Furthermore, the observed protective impact of PLB on cartilage implied that PLB can modulate the inhibition of ferroptosis in TMJOA by regulating the MAPK signaling pathways.

CONCLUSIONS

PLB alleviates TMJOA progression by suppressing chondrocyte ferroptosis via MAPK pathways, indicating PLB to be a potential therapeutic strategy for TMJOA.

ITGB1 alleviates osteoarthritis by inhibiting cartilage inflammation and apoptosis via activating cAMP pathway

OBJECTIVE

We aimed to screen novel biomarkers for osteoarthritis (OA) using bioinformatic methods and explore its regulatory mechanism in OA development.

METHODS

Differentially expressed genes were screened out from GSE98918 and GSE82107 datasets. Protein-protein interaction network and enrichment analysis were employed to search for hub gene and regulatory pathway. Hematoxylin-eosin, Safranin O-Fast green staining, and immunohistochemistry were performed to assess pathological damage. TNF-α, IL-1β, and IL-6 concentrations were determined by enzyme-linked immunosorbent assay. Real-time quantitative PCR was applied to verify expression of hub genes in OA model. The expression of key protein and pathway proteins was determined by western blot. Furthermore, Cell Counting Kit-8 and flow cytometry were conducted to explore the role of hub gene in chondrocytes.

RESULTS

We identified 6 hub genes of OA, including ITGB1, COL5A1, COL1A1, THBS2, LAMA1, and COL12A1, with high prediction value. ITGB1 was screened as a pivotal regulator of OA and cAMP pathway was selected as the key regulatory pathway. ITGB1 was down-regulated in OA model. ITGB1 overexpression attenuated pathological damage and apoptosis in OA rats with the reduced levels of TNF-α, IL-1β and IL-6. ITGB1 overexpression activated cAMP pathway in vivo and vitro models. In vitro model, ITGB1 overexpression promoted cell viability, while inhibited apoptosis. ITGB1 overexpression also caused a decrease of TNF-α, IL-1β, and IL-6 concentrations. cAMP pathway inhibitor reversed the positive effect of ITGB1 on OA cell model.

CONCLUSION

ITGB1 is a novel biomarker for OA, which inhibits OA development by activating the cAMP pathway.

Fusogenic liposomes encapsulating mitochondria as a promising delivery system for osteoarthritis therapy

Many attempts have been made to use mitochondria (MT) to treat human diseases; however, MT are large, making them difficult to deliver effectively. Therefore, a transfer strategy based on membrane fusion was established. Fusogenic mitochondrial capsules (FMCs) comprising a neutral lipid (PE), a cationic lipid (DOTAP), an aromatic lipid (Liss Rhod PE), and three types of liposome (FMC0, FMC1, and FMC2), were designed and synthesized. The amount of DOTAP, which affects membrane fusion efficiency, differed between FMC preparations. The characteristics of these FMCs were analyzed by DLS, TEM, and AFM, and the encapsulation and fusion efficiency between FMC-MT and FMC-chondrocytes were confirmed by FRET, mtDNA copy number, and CLSM, respectively. Compared with naked MT, delivery of FMCs to chondrocytes was faster and more efficient. Moreover, fusion was a more stable delivery method than endocytosis, as evidenced by reduced induction of mitophagy. In vitro and in vivo experiments revealed that FMCs reduced expression of inflammatory cytokines and MMP13, increased expression of extracellular matrix components, and promoted cartilage regeneration. These findings suggest that FMCs are a highly effective and promising strategy for delivery of MT to promote cartilage regeneration, and highlight their potential as a novel platform for MT transfer therapy.

Exploring the translational potential of PLGA nanoparticles for intra-articular rapamycin delivery in osteoarthritis therapy

Osteoarthritis (OA) is a prevalent joint disease that affects all the tissues within the joint and currently lacks disease-modifying treatments in clinical practice. Despite the potential of rapamycin for OA disease alleviation, its clinical application is hindered by the challenge of achieving therapeutic concentrations, which necessitates multiple injections per week. To address this issue, rapamycin was loaded into poly(lactic-co-glycolic acid) nanoparticles (RNPs), which are nontoxic, have a high encapsulation efficiency and exhibit sustained release properties for OA treatment. The RNPs were found to promote chondrogenic differentiation of ATDC5 cells and prevent senescence caused by oxidative stress in primary mouse articular chondrocytes. Moreover, RNPs were capable to alleviate metabolism homeostatic imbalance of primary mouse articular chondrocytes in both monolayer and 3D cultures under inflammatory or oxidative stress. In the mouse destabilization of the medial meniscus (DMM) model, intra-articular injection of RNPs effectively mitigated joint cartilage destruction, osteophyte formation, chondrocytes hypertrophy, synovial inflammation, and pain. Our study demonstrates the feasibility of using RNPs as a potential clinically translational therapy to prevent the progression of post-traumatic OA.

Consensus cluster analysis of apoptosis-related genes in patients with osteoarthritis and their correlation with immune cell infiltration

Background

Osteoarthritis (OA) progression involves multiple factors, including cartilage erosion as the basic pathological mechanism of degeneration, and is closely related to chondrocyte apoptosis. To analyze the correlation between apoptosis and OA development, we selected apoptosis genes from the differentially expressed genes (DEGs) between OA and normal samples from the Gene Expression Omnibus (GEO) database, used lasso regression analysis to identify characteristic genes, and performed consensus cluster analysis to further explore the pathogenesis of this disease.

Methods

The Gene expression profile datasets of OA samples, GSE12021 and GSE55235, were downloaded from GEO. The datasets were combined and analyzed for DEGs. Apoptosis-related genes (ARGs) were collected from the GeneCards database and intersected with DEGs for apoptosis-related DEGs (ARDEGs). Least absolute shrinkage and selection operator (LASSO) regression analysis was performed to obtain characteristic genes, and a nomogram was constructed based on these genes. A consensus cluster analysis was performed to divide the patients into clusters. The immune characteristics, functional enrichment, and immune infiltration statuses of the clusters were compared. In addition, a protein-protein interaction network of mRNA drugs, mRNA-transcription factors (TFs), and mRNA-miRNAs was constructed.

Results

A total of 95 DEGs were identified, of which 47 were upregulated and 48 were downregulated, and 31 hub genes were selected as ARDEGs. LASSO regression analysis revealed nine characteristic genes: growth differentiation factor 15 (GDF15), NAMPT, TLR7, CXCL2, KLF2, REV3L, KLF9, THBD, and MTHFD2. Clusters A and B were identified, and neutrophil activation and neutrophil activation involved in the immune response were highly enriched in Cluster B, whereas protein repair and purine salvage signal pathways were enriched in Cluster A. The number of activated natural killer cells in Cluster B was significantly higher than that in Cluster A. GDF15 and KLF9 interacted with 193 and 32 TFs, respectively, and CXCL2 and REV3L interacted with 48 and 82 miRNAs, respectively.

Conclusion

ARGs could predict the occurrence of OA and may be related to different degrees of OA progression.

Dapagliflozin suppress endoplasmic reticulum stress mediated apoptosis of chondrocytes by activating Sirt1

OBJECTIVE

Osteoarthritis (OA) is a common joint disease characterized by inflammation and cartilage degeneration. Accumulating evidences support that endoplasmic reticulum (ER) stress induced OA chondrocytes apoptosis. The hypoglycemic and anti-inflammatory properties render Dapagliflozin (DAPA) effective in reducing ER stress on cells. However, its impact and potential mechanisms on the OA pathology are still obscure. The present study aimed to investigate whether DAPA attenuates ER stress in chondrocytes by activating sirt1 and delays the progression of OA.

METHODS

In vitro, we first investigated the effect of DAPA on chondrocytes viability with IL-1β or not for 24 or 48 h. Then, chondrocytes were treated with 10 ng/ml IL-1β and 10 μM dapagliflozin with10 μM thapsigargin, 5 μM SRT1460 or not. Chondrocytes apoptosis in each group were detected by Tunel staining and flow cytometric. Immunofluorescence staining was applied to quantify the expression levels of cleaved caspase-3, Sirt1 and CHOP in chondrocytes. Inhibition of ER stress in chondrocytes associated with sirt1 activation were verified by PCR and western blotting. In addition, the effects of DAPA on cartilage were validated by a series of experiments in OA rat model, such as micro-CT, histological and immunohistochemical assay.

RESULTS

The data demonstrated that DAPA alleviates IL-1β induced ER stress related chondrocytes apoptosis, and PCR and western blotting data confirmed that DAPA inhibits the PERK-eIF2α-CHOP pathway by activating Sirt1. Besides, immunohistochemical results showed that DAPA enhanced the expression of Sirt1 and Collagen II in OA rats, and inhibited the expression of CHOP and cleaved caspase-3. Meanwhile, histological staining and micro-CT photography also confirmed that DAPA alleviated inflammation and cartilage degeneration in OA rat.

CONCLUSIONS

The study demonstrated the relationship of ER stress and inflammation in the progression of OA, and verified that DAPA could inhibit PERK-eIF2α-CHOP axis of the ER stress response by activating Sirt1 in IL-1β treated rat chondrocytes and potentially prevent the OA development.

Injectable mesoporous bioactive glass/sodium alginate hydrogel loaded with melatonin for intervertebral disc regeneration

Intervertebral disc degeneration (IDD) is a major contributing factor to both lower back and neck pain. As IDD progresses, the intervertebral disc (IVD) loses its ability to maintain its disc height when subjected to axial loading. This failure in the weight-bearing capacity of the IVD is a characteristic feature of degeneration. Natural polymer-based hydrogel, derived from biological polymers, possesses biocompatibility and is able to mimic the structure of extracellular matrix, enabling them to support cellular behavior. However, their mechanical performance is relatively poor, thus limiting their application in IVD regeneration. In this study, we developed an injectable composite hydrogel, namely, Mel-MBG/SA, which is similar to natural weight-bearing IVD. Mesoporous bioactive glasses not only enhance hydrogels, but also act as carriers for melatonin (Mel) to suppress inflammation during IDD. The Mel-MBG/SA hydrogel further provides a mixed system with sustained Mel release to alleviate IL-1β-induced oxidative stress and relieve inflammation associated with IDD pathology. Furthermore, our study shows that this delivery system can effectively suppress inflammation in the rat tail model, which is expected to further promote IVD regeneration. This approach presents a novel strategy for promoting tissue regeneration by effectively modulating the inflammatory environment while harnessing the mechanical properties of the material.

Targeting regulated chondrocyte death in osteoarthritis therapy

In vivo articular cartilage degeneration is an essential hallmark of osteoarthritis (OA), involving chondrocyte senescence, extracellular matrix degradation, chondrocyte death, cartilage loss, and bone erosion. Among them, chondrocyte death is one of the major factors leading to cartilage degeneration. Many studies have reported that various cell death modes, including apoptosis, ferroptosis, and autophagy, play a key role in OA chondrocyte death. Currently, there is insufficient understanding of OA pathogenesis, and there remains a lack of treatment methods to prevent OA and inhibit its progression. Studies suggest that OA prevention and treatment are mainly directed to arrest premature or excessive chondrocyte death. In this review, we a) discuss the forms of death of chondrocytes and the associations between them, b) summarize the critical factors in chondrocyte death, c) discuss the vital role of chondrocyte death in OA, d) and, explore new approaches for targeting the regulation of chondrocyte death in OA treatment.

Involvement of Oxidative Stress and Nutrition in the Anatomy of Orofacial Pain

Pain is a very important problem of our existence, and the attempt to understand it is one the oldest challenges in the history of medicine. In this review, we summarize what has been known about pain, its pathophysiology, and neuronal transmission. We focus on orofacial pain and its classification and features, knowing that is sometimes purely subjective and not well defined. We consider the physiology of orofacial pain, evaluating the findings on the main neurotransmitters; in particular, we describe the roles of glutamate as approximately 30-80% of total peripheric neurons associated with the trigeminal ganglia are glutamatergic. Moreover, we describe the important role of oxidative stress and its association with inflammation in the etiogenesis and modulation of pain in orofacial regions. We also explore the warning and protective function of orofacial pain and the possible action of antioxidant molecules, such as melatonin, and the potential influence of nutrition and diet on its pathophysiology. Hopefully, this will provide a solid background for future studies that would allow better treatment of noxious stimuli and for opening new avenues in the management of pain.