Oxidative stress and inflammation in osteoarthritis pathogenesis: Role of polyphenols

Evaluation of Cartilage Integrity Following Administration of Oral and Intraarticular Nifedipine in a Murine Model of Osteoarthritis

Osteoarthritis (OA) ranks as the prevailing type of arthritis on a global scale, for which no effective treatments are currently available. Arterial hypertension is a common comorbidity in OA patients, and antihypertensive drugs, such as nifedipine (NIF), may affect the course of OA progression. The aim of this preclinical study was to determine the effect of nifedipine on healthy and OA cartilage, depending on its route of administration. In this study, we used the destabilization of medial meniscus to develop a mouse model of OA. Nifedipine was applied per os or intraarticularly (i.a.) for 8 weeks to both mice with OA and healthy animals. Serum biomarker concentrations were evaluated using the Luminex platform and alterations in the knee cartilage were graded according to OARSI histological scores and investigated immunohistochemically. Nifedipine treatment per os and i.a. exerted protective effects, as assessed by the OARSI histological scores. However, long-term nifedipine i.a. injections induced the deterioration of healthy cartilage. Lubricin, cartilage intermediate layer matrix protein (CILP), collagen type VI (COLVI), CILP, and Ki67 were upregulated by the nifedipine treatment. Serum biomarkers MMP-3, thrombospondin-4, and leptin were upregulated in the healthy groups treated with nifedipine, while only the levels of MMP-3 were significantly higher in the OA group treated with nifedipine per os compared to the untreated group. In conclusion, this study highlights the differential effects of nifedipine on cartilage integrity, depending on the route of administration and cartilage condition.

Lipid peroxidation in osteoarthritis: focusing on 4-hydroxynonenal, malondialdehyde, and ferroptosis

Osteoarthritis (OA) is a multifactorial and increasingly prevalent degenerative disease that affects the whole joint. The pathogenesis of OA is poorly understood and there is a lack of therapeutic interventions to reverse the pathological process of this disease. Accumulating studies have shown that the overproduction of reactive oxygen species (ROS) and ROS-induced lipid peroxidation are involved in the pathogenesis of OA. 4-Hydroxy-2-nonenal (4-HNE) and malondialdehyde (MDA) have received considerable attention for their role in cartilage degeneration and subchondral bone remodeling during OA development. Ferroptosis is a form of cell death characterized by a lack of control of membrane lipid peroxidation and recent studies have suggested that chondrocyte ferroptosis contributes to OA progression. In this review, we aim to discuss lipid peroxidation-derived 4-HNE and MDA in the progression of OA. In addition, the therapeutic potential for OA by controlling the accumulation of lipid peroxidation and inhibiting chondrocyte ferroptosis are discussed.

Investigation of the phytochemical composition, antioxidant, antibacterial, anti-osteoarthritis, and wound healing activities of selected vegetable waste

Agri-food wastes, produced following industrial food processing, are mostly discarded, leading to environmental hazards and losing the nutritional and medicinal values associated with their bioactive constituents. In this study, we performed a comprehensive analytical and biological evaluation of selected vegetable by-products (potato, onion, and garlic peels). The phytochemical analysis included UHPLC-ESI-qTOF-MS/MS in combination with molecular networking and determination of the total flavonoid and phenolic contents. Further, the antimicrobial, anti-osteoarthritis and wound healing potentials were also evaluated. In total, 47 compounds were identified, belonging to phenolic acids, flavonoids, saponins, and alkaloids as representative chemical classes. Onion peel extract (OPE) showed the higher polyphenolic contents, the promising antioxidant activity, the potential anti-osteoarthritis activity, and promising antimicrobial activity, especially against methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, OPE revealed to have promising in vivo wound healing activity, restoring tissue physiology and integrity, mainly through the activation of AP-1 signaling pathway. Lastly, when OPE was loaded with nanocapsule based hydrogel, the nano-formulation revealed enhanced cellular viability. The affinities of the OPE major metabolites were evaluated against both p65 and ATF-2 targets using two different molecular docking processes revealing quercetin-3,4'-O-diglucoside, alliospiroside C, and alliospiroside D as the most promising entities with superior binding scores. These results demonstrate that vegetable by-products, particularly, those derived from onion peels can be incorporated as natural by-product for future evaluation against wounds and osteoarthritis.

Effects of genus Epimedium in the treatment of osteoarthritis and relevant signaling pathways

Osteoarthritis (OA) is a common chronic degenerative joint disease in clinical practice with a high prevalence, especially in the elderly. Traditional Chinese Medicine (TCM) believes that OA belongs to the category of "Bi syndrome" and the "bone Bi syndrome". The etiology and pathogenesis lie in the deficiency of the liver and kidney, the deficiency of Qi and blood, and external exposure to wind, cold, and dampness. Epimedium is a yang-reinforcing herb in TCM, which can tonify the liver and kidney, strengthen muscles and bones, dispel wind, cold and dampness, and can treat both the symptoms and the root cause of "bone Bi syndrome". In addition, Epimedium contains a large number of ingredients. Through modern science and technology, more than 270 compounds have been found in Epimedium, among which flavonoids are the main active ingredients. Therefore, our study will review the effects and mechanisms of genus Epimedium in treating OA from two aspects: (1) Introduction of Epimedium and its main active ingredients; (2) Effects of Epimedium and its active ingredients in treating OA and relevant signaling pathways, in order to provide more ideas for OA treatment.

Drug Delivery Strategies and Nanozyme Technologies to Overcome Limitations for Targeting Oxidative Stress in Osteoarthritis

Oxidative stress is an important, but elusive, therapeutic target for osteoarthritis (OA). Antioxidant strategies that target oxidative stress through the elimination of reactive oxygen species (ROS) have been widely evaluated for OA but are limited by the physiological characteristics of the joint. Current hallmarks in antioxidant treatment strategies include poor bioavailability, poor stability, and poor retention in the joint. For example, oral intake of exogenous antioxidants has limited access to the joint space, and intra-articular injections require frequent dosing to provide therapeutic effects. Advancements in ROS-scavenging nanomaterials, also known as nanozymes, leverage bioactive material properties to improve delivery and retention. Material properties of nanozymes can be tuned to overcome physiological barriers in the knee. However, the clinical application of these nanozymes is still limited, and studies to understand their utility in treating OA are still in their infancy. The objective of this review is to evaluate current antioxidant treatment strategies and the development of nanozymes as a potential alternative to conventional small molecules and enzymes.

The molecular link between obstructive sleep apnea and osteoarthritis: based on bioinformatics analysis and experimental validation

BACKGROUND

Obstructive sleep apnea (OSA) and osteoarthritis (OA) are highly prevalent and seriously affect the patient's quality of life. Patients with OSA have a high incidence of OA, however, the underlying mechanism remains unclear. Here, we investigated the molecular link between OSA and OA via bioinformatics analysis and experimental validation.

METHODS

We downloaded a peripheral blood monocyte microarray profile (GSE75097) for patients with OSA and two synovial microarray profiles (GSE55235 and GSE55457) for patients with OA from the Gene Expression Omnibus database. We identified OSA-associated differentially expressed genes (OSA-DEGs) in patients with OA. Additionally, we constructed protein-protein interaction networks to identify the key genes involved in OA. Immunohistochemistry was performed to verify the expression of key genes in OA rat models. RNA interference assay was performed to validate the effects of key genes on synovial cells. Gene-miRNA, gene-transcription factor, and gene-drug networks were constructed to predict the regulatory molecules and drugs for OA.

RESULTS

Fifteen OSA-DEGs screened using the threshold criteria were enriched in the tumor necrosis factor (TNF) pathway. Combining the 12 algorithms of CytoHubba, we identified JUNB, JUN, dual specificity phosphatase 1 (DUSP1), and TNF-alpha-induced protein 3 (TNFAIP3) as the key OSA-DEGs involved in OA development. Immunohistochemistry and quantitative polymerase chain reaction revealed that these key genes were downregulated in the OA synovium, promoting TNF-α expression. Therefore, OSA-DEGs, JUN, JUNB, DUSP1, and TNFAIP3 function in OA by increasing TNF-α expression. Our findings provide insights on the mechanisms underlying the effects of OSA on OA.

Personalized Nutritional Strategies to Reduce Knee Osteoarthritis Severity and Ameliorate Sarcopenic Obesity Indices: A Practical Guide in an Orthopedic Setting

Knee osteoarthritis (KOA) is one of the most common joint diseases, especially in individuals with obesity. Another condition within this population, and which presents frequently, is sarcopenic obesity (SO), defined as an increase in body fat and a decrease in muscle mass and strength. The current paper aims to describe recent nutritional strategies which can generally improve KOA clinical severity and, at the same time, ameliorate SO indices. Searches were carried out in the PubMed and Science Direct databases and data were summarized using a narrative approach. Certain key findings have been revealed. Firstly, the screening and identification of SO in patients with KOA is important, and to this end, simple physical performance tests and anthropometric measures are available in the literature. Secondly, adherence to a Mediterranean diet and the achievement of significant body weight loss by means of low-calorie diets (LCDs) remain the cornerstone nutritional treatment in this population. Thirdly, supplementation with certain micronutrients such as vitamin D, essential and non-essential amino acids, as well as whey protein, also appear to be beneficial. In conclusion, in the current review, we presented a detailed flowchart of three different nutritional tracks that can be adopted to improve both KOA and SO based on joint disease clinical severity.

MATN3 delivered by exosome from synovial mesenchymal stem cells relieves knee osteoarthritis: Evidence from in vitro and in vivo studies

Background

Synovial mesenchymal stem cell (SMSC) exerts chondroprotective effects in osteoarthritis (OA) clinical models. However, the regulatory potentials of SMSC-derived exosomes (SMSC-Exo) in OA still need to be discovered, which attracted our attention.

Methods

The destabilization of the medial meniscus surgery was performed on the knee joints of a mouse OA model, followed by injection of SMSC-Exo. In addition, SMSC-Exo was administrated to mouse chondrocytes to observe the functional and molecular alterations.

Results

Both of SMSC-Exo and overexpression of Matrilin-3 (MATN3) alleviated cartilage destruction and suppressed degradation of extracellular matrix (ECM) in the OA rat model. In addition, assays concerning the in vitro OA model induced by IL-1β showed that SMSC-Exo could promote chondrocyte viability and inhibit autophagy defects. Furthermore, SMSC-Exo achieved the chondroprotective effects through the delivery of MATN3/IL-17A, and MATN3 could suppress the activation of PI3K/AKT/mTOR signaling through IL-17A.

Conclusion

SMSC-Exo exerts beneficial therapeutic effects on OA by preventing ECM degradation and autophagy defects by delivering MATN3/IL-17A.

The Translational Potential of this Article

The translational potential of this study is not only limited to the treatment of knee osteoarthritis but also provides new insights for the treatment of other joint diseases by exploring the mechanism of MATN3. In addition, SMSCExo, as a novel drug carrier, has great potential for treating and diagnosing other diseases. With further research, these findings will provide new directions for developing personalized and innovative treatment options.

Hyperbaric Oxygen Therapy Ameliorates Sperm Parameters in Apolipoprotein E Knockout Mice Testes by Attenuating Oxidative Stress and Inflammation

Apolipoprotein E (ApoE) is a member of apolipoprotein (apo) family and plays critical role in lipid metabolism. In this study, the relationship between abnormal lipid metabolism caused by ApoE-deficient and male reproduction was investigated. The effect of hyperbaric oxygen (HBO) therapy on 7-month-old ApoE-knockout male mice was assessed subsequently. Mice were randomly divided into 3 groups: control group (WT), ApoE (- / -) group (AP-CON), and ApoE (- / -) plus HBO group (AP-HBO), which received HBO treatment. We found that ApoE knockout caused a decrease in male reproductive capacity due to the reduced total sperm motility, progressive motility (PR), and lower blastocyst formation rate. HBO treatment could accelerate serum lipoprotein metabolism including LDL, T-CHO, and TG and semen quality. As a result, fertilization and blastocyst formation of AP-HBO group were higher than that of AP-CON, proving positive therapeutic effect. Mechanism exploration found that HBO treatment ameliorated the testicular microenvironment by attenuating inflammatory factor production and oxidative stress, eventually improved the sperm motility. Collectively, our study provided more evidences of HBO treatment for improving the semen quality of patients with abnormal lipid metabolism caused by ApoE-deficient.

Antioxidant and Anti-inflammatory Effects of α-Lipoic Acid on Lipopolysaccharide-induced Oxidative Stress in Rat Kidney

α-Lipoic acid (α-LA) is a naturally occurring organosulfur component. Oxidative stress plays an essential role in the pathogenesis of various diseases, such as kidney and cardiovascular diseases, diabetes, neurodegenerative disorders, cancer and aging. Kidneys are especially vulnerable to oxidative stress and damage. The aim of the study was to evaluate the effect of α-LA on lipopolysaccharide (LPS)-induced oxidative stress parameters in rat kidneys. The experimental rats were divided into four groups: I-control (0.9% NaCl i.v.); II-α-LA (60 mg/kg b.w. i.v.); III-LPS (30 mg/kg b.w. i.v.); and IV-LPS + LA (30 mg/kg b.w. i.v. and 60 mg/kg b.w. i.v., respectively). In kidney homogenates the concentration of thiobarbituric acid reactive substances (TBARS), hydrogen peroxide (H₂O₂), sulfhydryl groups (-SH), total protein, superoxide dismutase (SOD), total glutathione (tGSH), reduced glutathione (GSH), glutathione disulphide (GSSG) and the GSH/GSSG ratio were determined. In addition, the levels of tumour necrosis factor (TNF)-α, and interleukin (IL)-6 were measured to assess inflammation and was estimated kidney oedema. Studies have shown that α-LA administered after LPS administration attenuated kidney oedema and significantly decreased TBARS, H₂O₂, TNF-α, and IL-6 levels in rat kidneys. α-LA also resulted in increase -SH group, total protein, and SOD levels and ameliorated the GSH redox status when compared to the LPS group. The results suggest that α-LA plays an important role against LPS-induced oxidative stress in kidney tissue as well as downregulating the expression of pro-inflammatory cytokines.

Diet-derived circulating antioxidants and risk of knee osteoarthritis, hip osteoarthritis and rheumatoid arthritis: a two-sample Mendelian randomization study

Objective

To examine the causal associations of diet-derived circulating antioxidants with knee osteoarthritis (OA), hip OA, and rheumatoid arthritis (RA) within the two-sample Mendelian randomization (MR) framework.

Method

Independent single-nucleotide polymorphisms (SNPs) significantly associated with circulating levels of diet-derived antioxidants (retinol, β-carotene, lycopene, vitamin C and vitamin E) were extracted as genetic instruments. Summary statistics of genetic instruments associated with knee OA, hip OA, and RA were obtained from corresponding genome-wide association studies (GWASs). The inverse-variance weighted (IVW) was applied as the primary analysis method, with four sensitivity analysis approaches employed to evaluate the robustness of the primary results.

Results

Genetically determined per unit increment of absolute circulating levels of retinol was significantly associated with a reduced risk of hip OA [odds ratio (OR) = 0.45, 95% confidence interval (CI) 0.26-0.78, p = 4.43 × 10^-3], while genetically determined per unit increase in absolute circulating levels of β-carotene was suggestively associated with increased risk of RA (OR = 1.32, 95% CI 1.07-1.62, p = 9.10 × 10^-3). No other causal association was found. Significant evidence for heterogeneity and pleiotropic outlier was only identified when absolute circulating vitamin C was evaluated as the exposure, whereas all sensitive analysis provided consistently non-significant results.

Conclusion

Our results demonstrated that genetically determined lifelong higher exposure to absolute circulating levels of retinol is associated with a decreased risk of hip OA. Further MR study with more genetic instruments for absolute circulating levels of antioxidants are needed to confirm our results.

Osteoarthritic chondrocytes undergo a glycolysis-related metabolic switch upon exposure to IL-1b or TNF

BACKGROUND

Osteoarthritis is an age-related disease that currently faces a lack of symptomatic treatment. Inflammation, which is mainly sustained by pro-inflammatory cytokines such as IL-1b, TNF, and IL-6, plays an important role in osteoarthritis progression. In this context, pro-inflammatory cytokines are widely used to mimic the inflammatory component of osteoarthritis in vitro. However, the therapeutic failures of clinical trials evaluating anti-cytokines drugs highlight the lack of overall understanding of the effects of these cytokines on chondrocytes.

METHODS

Here, we generated a comprehensive transcriptomic and proteomic dataset of osteoarthritic chondrocytes treated with these cytokines to describe their pro-inflammatory signature and compare it to the transcriptome of non-osteoarthritic chondrocytes. Then, the dysregulations highlighted at the molecular level were functionally confirmed by real-time cellular metabolic assays.

RESULTS

We identified dysregulation of metabolic-related genes in osteoarthritic chondrocytes but not in non-osteoarthritic chondrocytes. A metabolic shift, toward increased glycolysis at the expense of mitochondrial respiration, was specifically confirmed in osteoarthritic chondrocytes treated with IL-1b or TNF.

CONCLUSION

These data show a strong and specific association between inflammation and metabolism in osteoarthritic chondrocytes, which was not found in non-osteoarthritic chondrocytes. This indicates that the link between inflammation and metabolic dysregulation may be exacerbated during chondrocyte damage in osteoarthritis. Video Abstract.

Protective and Pain-Killer Effects of AMC3, a Novel N-Formyl Peptide Receptors (FPRs) Modulator, in Experimental Models of Rheumatoid Arthritis

Rheumatoid arthritis is an autoimmune disorder that causes chronic joint pain, swelling, and movement impairment, resulting from prolonged inflammation-induced cartilage and bone degradation. The pathogenesis of RA, which is still unclear, makes diagnosis and treatment difficult and calls for new therapeutic strategies to cure the disease. Recent research has identified FPRs as a promising druggable target, with AMC3, a novel agonist, showing preclinical efficacy in vitro and in vivo. In vitro, AMC3 (1-30 µM) exhibited significant antioxidant effects in IL-1β (10 ng/mL)-treated chondrocytes for 24 h. AMC3 displayed a protective effect by downregulating the mRNA expression of several pro-inflammatory and pro-algic genes (iNOS, COX-2, and VEGF-A), while upregulating genes essential for structural integrity (MMP-13, ADAMTS-4, and COLIAI). In vivo, AMC3 (10 mg kg^-1) prevented hypersensitivity and restored postural balance in CFA-injected rats after 14 days. AMC3 attenuated joint alterations, reduced joint inflammatory infiltrate, pannus formation, and cartilage erosion. Chronic AMC3 administration reduced transcriptional changes of genes causing excitotoxicity and pain (EAATs and CCL2) and prevented morphological changes in astrocytes, including cell body hypertrophy, processes length, and thickness, caused by CFA in the spinal cord. This study demonstrates the usefulness of AMC3 and establishes the groundwork for further research.

Injectable hypoxia-preconditioned cartilage progenitor cells-laden GelMA microspheres system for enhanced osteoarthritis treatment

Osteoarthritis (OA) is the most common age-related degenerative joint disease mainly characterized by the destruction of articular cartilage. Owing to its native avascular property, intrinsic repair of articular cartilage is very limited. Thus, a chondrogenic microenvironment in the joint is essential to the preservation of healthy chondrocytes and OA treatment. Recently, cartilage progenitor cells (CPCs)-based therapy is emerging as a promising strategy to repair degenerated and damaged articular cartilage. In this study, injectable hypoxia-preconditioned three-dimensional (3D) cultured CPCs-laden gelatin methacryloyl (GelMA) microspheres (CGMs) were constructed and characterized. Compared to normoxia-pretreated 3D CPCs and two-dimensional (2D) cultured CPCs, hypoxia-preconditioned 3D cultured CPCs exhibited enhanced cartilage extracellular matrix (ECM) secretion and greater chondrogenic ability. In addition, hypoxia-preconditioned 3D cultured CPCs more effectively maintained cartilage matrix metabolism balance and attenuated articular cartilage degeneration in subacute and chronic rat OA models. Mechanistically, our results demonstrated hypoxia-preconditioned 3D cultured CPCs exerted chondro-protective effects by inhibiting inflammation and oxidative stress via NRF2/HO-1 pathway in vitro and in vivo. Together, through the 3D culture of CPCs using GelMA microspheres (GMs) under hypoxia environment, our results proposed an efficient articular cartilage regeneration strategy for OA treatment and could provide inspiration for other stem cells-based therapies.

Alleviating effect of lycorine on CFA‑induced arthritic pain via inhibition of spinal inflammation and oxidative stress

Chronic pain is the primary symptom of osteoarthritis affecting a patient's quality of life. Neuroinflammation and oxidative stress in the spinal cord contribute to arthritic pain and represent ideal targets for pain management. In the present study, a model of arthritis was established by intra-articular injection of complete Freund's adjuvant (CFA) into the left knee joint in mice. After CFA inducement, knee width and pain hypersensitivity in the mice were increased, motor disability was impaired, spinal inflammatory reaction was induced, spinal astrocytes were activated, antioxidant responses were decreased, and glycogen synthase kinase 3β (GSK-3β) activity was inhibited. To explore the potential therapeutic options for arthritic pain, lycorine was intraperitoneally injected for 3 days in the CFA mice. Lycorine treatment significantly reduced mechanical pain sensitivity, suppressed spontaneous pain, and recovered motor coordination in the CFA-induced mice. Additionally, in the spinal cord, lycorine treatment decreased the inflammatory score, reduced NOD-like receptor protein 3 inflammasome (NLRP3) activity and IL-1β expression, suppressed astrocytic activation, downregulated NF-κB levels, increased nuclear factor erythroid 2-related factor 2 expression and superoxide dismutase activity. Furthermore, lycorine was shown to bind to GSK-3β through three electrovalent bonds, to inhibit GSK-3β activity. In summary, lycorine treatment inhibited GSK-3β activity, suppressed NLRP3 inflammasome activation, increased the antioxidant response, reduced spinal inflammation, and relieved arthritic pain.

Anti-inflammatory labdane diterpenoids from the aerial parts of Leonurus japonicus

Twenty-two labdane-type diterpenoids, including ten pairs of 15-epimers and a pair of 13,15-epimers, were obtained from the aerial parts of a well-known medicinal plant Leonurus japonicus Houtt. While these epimers were separated by chiral HPLC, their structures were established mainly via spectroscopic methods especially NMR, X-ray crystallography and ECD techniques. Among them, seventeen compounds, encompassing three pairs of solvolysis artefacts likely due to the use of ethanol as extracting solvent, were reported for the first time in the current work. Our preliminary anti-inflammatory screening demonstrated that seven diterpenoids displayed noteworthy inhibitory effect on the NO production in LPS-induced RAW264.7 cells. In addition, the release of pro-inflammatory factors TNF-α, IL-1β and IL-6, as well as the expression of iNOS and COX-2 proteins, was also suppressed by the unreported 15,16-epoxy-6β-hydroxy-15α-methoxy-7,16-dioxolabd-8,13-diene. Further investigation into the preliminary anti-inflammatory mechanism of this compound indicated that it could block the activation of NF-κB signaling pathway.

The Protective Effect of Selenium Nanoparticles in Osteoarthritis: In vitro and in vivo Studies

Introduction

Osteoarthritis (OA) is a common chronic joint disease characterized by articular cartilage degeneration. OA usually manifests as joint pain, limited mobility, and joint effusion. Currently, the primary OA treatment is non-steroidal anti-inflammatory drugs (NSAIDs). Although they can alleviate the disease's clinical symptoms and signs, the drugs have some side effects. Selenium nanoparticles (SeNPs) may be an alternative to relieve OA symptoms.

Materials and Results

We confirmed the anti-inflammatory effect of selenium nanoparticles (SeNPs) in vitro and in vivo experiments for OA disease in this study. In vitro experiments, we found that SeNPs could significantly reduce the expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the major inflammatory factors, and had significant anti-inflammatory and anti-arthritic effects. SeNPs can inhibit reactive oxygen species (ROS) production and increased glutathione peroxidase (GPx) activity in interleukin-1beta (IL-1β)-stimulated cells. Additionally, SeNPs down-regulated matrix metalloproteinase-13 (MMP-13) and thrombospondin motifs 5 (ADAMTS-5) expressions, while up-regulated type II collagen (COL-2) and aggrecan (ACAN) expressions stimulated by IL-1β. The findings also indicated that SeNPs may exert their effects through suppressing the NF-κB p65 and p38/MAPK pathways. In vivo experiments, the prevention of OA development brought on by SeNPs was demonstrated using a DMM model.

Discussion

Our results suggest that SeNPs may be a potential anti-inflammatory agent for treating OA.

Polydopamine-Pd nanozymes as potent ROS scavengers in combination with near-infrared irradiation for osteoarthritis treatment

Excessive reactive oxygen species (ROS) in joints could lead to gradual degeneration of the extracellular matrix (ECM) and apoptosis of chondrocytes, contributing to the occurrence and development of osteoarthritis (OA). Mimicking natural enzymes, polydopamine (PDA)-based nanozymes showed great potential in treating various inflammatory diseases. In this work, PDA loaded with ultra-small palladium (PDA-Pd) nanoparticles (NPs) was employed to scavenge ROS for OA therapy. As a result, PDA-Pd effectively declined the intracellular ROS levels and exhibited efficient antioxidative and anti-inflammatory capacity with good biocompatibility in IL-1β stimulated chondrocytes. Significantly, assisted with near-infrared (NIR) irradiation, its therapeutic effect was further enhanced. Further, NIR-stimulated PDA-Pd suppressed the progression of OA after intra-articular injection in the OA rat model. With favorable biocompatibility, PDA-Pd exhibits efficient antioxidative and anti-inflammatory capacity, leading to the alleviation of OA in rats. Our findings may provide new insights into the treatment of various ROS-induced inflammatory diseases.

Alisol A 24-acetate ameliorates osteoarthritis progression by inhibiting reactive oxygen species and inflammatory response through the AMPK/mTOR pathway

INTRODUCTION

Osteoarthritis is a degenerative knee joint disease featured with articular cartilage degeneration and inflammation. Alisol A 24-acetate (ALA-24A) is an active triterpene that has antioxidant and anti-inflammatory pharmacological properties. However, its effect and molecular mechanism on osteoarthritis progression have not been reported.

METHODS

IL-1β-induced chondrocyte injury model and monosodium iodoacetate (MIA)-induced rat osteoarthritis model were used. The protective effects of ALA-24A on osteoarthritis were evaluated by determining cell viability, extracellular matrix (ECM) degradation, inflammatory response and oxidative stress using CCK-8 assay, Western blot, ELISA, and DCFH-DA fluorescent probe. The severity and matrix degradation of articular cartilage were assessed by histopathological and immunohistochemical examination.

RESULTS

We found that ALA-24A attenuated IL-1β-induced cell viability inhibition Moreover, ALA-24A suppressed expression levels of ECM degradation-related genes ADAMTS5 and MMP13, and promoted expression levels of ECM synthesis-related genes Aggrecan and Collagen II. In addition, ALA-24A treatment decreased reactive oxygen species (ROS) production and increased antioxidant enzymes (SOD, CAT, and GSH-px) activities, while increased MDA levels. The inflammatory levels of NO, PGE2, TNF-α, and IL-6 were also reduced following treatment with ALA-24A. Our data also revealed that ALA-24A treatment triggered p-AMPK upregulation and p-mTOR downregulation. In rat osteoarthritis model, ALA-24A treatment significantly alleviated the severity and matrix degradation of articular cartilage comparted with model group.

CONCLUSIONS

Our findings suggested a protective role of ALA-24A against osteoarthritis by inhibiting ROS and inflammatory response. Furthermore, ALA-24A might be a promising therapeutic option for osteoarthritis treatment.

An Integrated View of Stressors as Causative Agents in OA Pathogenesis

Cells in the body are exposed to dynamic external and internal environments, many of which cause cell damage. The cell's response to this damage, broadly called the stress response, is meant to promote survival and repair or remove damage. However, not all damage can be repaired, and sometimes, even worse, the stress response can overtax the system itself, further aggravating homeostasis and leading to its loss. Aging phenotypes are considered a manifestation of accumulated cellular damage and defective repair. This is particularly apparent in the primary cell type of the articular joint, the articular chondrocytes. Articular chondrocytes are constantly facing the challenge of stressors, including mechanical overloading, oxidation, DNA damage, proteostatic stress, and metabolic imbalance. The consequence of the accumulation of stress on articular chondrocytes is aberrant mitogenesis and differentiation, defective extracellular matrix production and turnover, cellular senescence, and cell death. The most severe form of stress-induced chondrocyte dysfunction in the joints is osteoarthritis (OA). Here, we summarize studies on the cellular effects of stressors on articular chondrocytes and demonstrate that the molecular effectors of the stress pathways connect to amplify articular joint dysfunction and OA development.

Therapeutic actions of tea phenolic compounds against oxidative stress and inflammation as central mediators in the development and progression of health problems: A review focusing on microRNA regulation

Many health problems including chronic diseases are closely associated with oxidative stress and inflammation. Tea has abundant phenolic compounds with various health benefits including antioxidant and anti-inflammatory properties. This review focuses on the present understanding of the impact of tea phenolic compounds on the expression of miRNAs, and elucidates the biochemical and molecular mechanisms underlying the transcriptional and post-transcriptional protective actions of tea phenolic compounds against oxidative stress- and/or inflammation-mediated diseases. Clinical studies showed that drinking tea or taking catechin supplement on a daily basis promoted the endogenous antioxidant defense system of the body while inhibiting inflammatory factors. The regulation of chronic diseases based on epigenetic mechanisms, and the epigenetic-based therapies involving different tea phenolic compounds, have been insufficiently studied. The molecular mechanisms and application strategies of miR-27 and miR-34 involved in oxidative stress response and miR-126 and miR-146 involved in inflammation process were preliminarily investigated. Some emerging evidence suggests that tea phenolic compounds may promote epigenetic changes, involving non-coding RNA regulation, DNA methylation, histone modification, ubiquitin and SUMO modifications. However, epigenetic mechanisms and epigenetic-based disease therapies involving phenolic compounds from different teas, and the potential cross-talks among the epigenetic events, remain understudied.

Comprehensive review on biosynthesis of hyaluronic acid with different molecular weights and its biomedical applications

Hyaluronic acid (HA), an anionic and nonsulfated glycosaminoglycan, is the main structural component of various tissues and plays an important role in various biological processes. Given the promising properties of HA, such as high cellular compatibility, moisture retention, antiaging, proper interaction with cells, and CD44 targeting, HA can be widely used extensively in drug delivery, tissue engineering, wound healing, and cancer therapy. HA can obtain from animal tissues and microbial fermentation, but its applications depend on its molecular weight. Microbial fermentation is a common method for HA production on an industrial scale and S. zooepidemicus is the most frequently used strain in HA production. Culture conditions including pH, temperature, agitation rate, aeration speed, shear stress, dissolved oxygen, and bioreactor type significantly affect HA biosynthesis properties. In this review all the HA production methods and purification techniques to improve its physicochemical and biological properties for various biomedical applications are discussed in details. In addition, we showed that how HA molecular weight can significantly affect its properties and applications.

Supplementation of hyaluronic acid injections with vitamin D improve knee function by attenuating synovial fluid oxidative stress in osteoarthritis patients with vitamin D insufficiency

Objectives

There is still controversy about the effect of vitamin D supplementation on osteoarthritis (OA). The purpose of this study was to investigate the effects of vitamin D supplementation with Hyaluronic acid (HA) injection on OA.

Methods

We investigated serum vitamin D levels and oxidative stress (OS) in synovial fluid from patients with OA who underwent total knee arthroplasty (grade IV, n = 24) and HA injection (grade II and III, n = 40). The effects of HA injection with or without oral vitamin D supplementation on synovial fluid OS and knee pain and function were then further investigated. Finally, patients underwent HA injection were divided into two groups according to vitamin D levels (vitamin D < or > 30 ng/ml), and the efficacy of the two groups were compared.

Results

The results showed that the levels of glutathione peroxidase (GSH-PX) (P < 0.05) in the synovial fluid were lower in patients with stage IV OA than that in patients with stage II-III OA, while the levels of malondialdehyde (MDA) (P < 0.05) and lactate dehydrogenase (LDH) (P < 0.01) were significantly higher. Moreover, we found that age, BMI and vitamin D levels were significantly associated with the levels of oxidants and/or antioxidants in synovial fluid, and that vitamin D was significantly negatively correlated with BMI (R = −0.3527, p = 0.0043). Supplementation of HA injections with vitamin D significantly reduced the OS status in synovial fluid, attenuated knee pain and improved knee function in OA patients with vitamin D insufficiency.

Conclusion

We conclude that maintenance of vitamin D sufficiency may be beneficial for the treatment of OA by improving OS in synovial fluid.

PD184352 exerts anti-inflammatory and antioxidant effects by promoting activation of the Nrf2/HO-1 axis

Osteoarthritis (OA) is a disabling joint disease characterized by cartilage degeneration. Reactive oxygen species (ROS)-induced oxidative stress is an important cause of early chondrocyte death. For this reason, we investigated PD184352, a small molecule inhibitor with potential anti-inflammatory and antioxidant activity. We evaluated the protective effect of PD184352 against destabilized medial meniscus (DMM)-induced OA in mice. The knee joints of the PD184352-treated group had higher Nrf2 expression and milder cartilage damage. Moreover, in in vitro experiments, PD184352 suppressed IL-1β-induced NO, iNOS, PGE2 production, and attenuated pyroptosis. PD184352 treatment promoted antioxidant protein expression and reduced the accumulation of ROS by activating the Nrf2/HO-1 axis. Finally, the anti-inflammatory and antioxidant effects of PD184352 were shown to be partially dependent on Nrf2 activation. Our study reveals the potential role of PD184352 as an antioxidant and provides a new strategy for OA treatment.

Smart Hydrogels for Bone Reconstruction via Modulating the Microenvironment

Rapid and effective repair of injured or diseased bone defects remains a major challenge due to shortages of implants. Smart hydrogels that respond to internal and external stimuli to achieve therapeutic actions in a spatially and temporally controlled manner have recently attracted much attention for bone therapy and regeneration. These hydrogels can be modified by introducing responsive moieties or embedding nanoparticles to increase their capacity for bone repair. Under specific stimuli, smart hydrogels can achieve variable, programmable, and controllable changes on demand to modulate the microenvironment for promoting bone healing. In this review, we highlight the advantages of smart hydrogels and summarize their materials, gelation methods, and properties. Then, we overview the recent advances in developing hydrogels that respond to biochemical signals, electromagnetic energy, and physical stimuli, including single, dual, and multiple types of stimuli, to enable physiological and pathological bone repair by modulating the microenvironment. Then, we discuss the current challenges and future perspectives regarding the clinical translation of smart hydrogels.

Daurisoline attenuates H2O2-induced chondrocyte autophagy by activating the PI3K/Akt/mTOR signaling pathway

BACKGROUND

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by cartilage degeneration and intra-articular inflammation. Daurisoline (DAS) is an isoquinoline alkaloid isolated from Rhizoma Menispermi, whose antitumor and anti-inflammatory pharmacological effects have been demonstrated, but the effects of DAS on OA have rarely been researched. In this study, we aimed to explore the potential role of DAS in OA and its partial mechanism.

MATERIALS AND METHODS

The cytotoxicity of H₂O₂ and DAS toward chondrocytes was detected by the Cell Counting Kit-8 assay. Safranin O staining was used to detect chondrocyte phenotype changes. Cell apoptosis was measured by both flow cytometry and quantitative analysis of the protein levels of the apoptosis-related factors Bax, Bcl-2 and cleaved caspase-3 by western blot. Western blotting and immunofluorescence were used to assess the expression of the autophagy-related proteins LC3, Beclin-1 and p62. In addition, key signal pathway targets and matrix-degrading indicators were measured by western blot.

RESULTS

Our results indicated that H₂O₂ induced human chondrocyte apoptosis and activated autophagy in a dose-dependent manner. DAS treatment dose-dependently reversed the expression of apoptosis-related proteins (Bax, Bcl-2 and cleaved caspase3) and the apoptosis rate induced by H₂O₂. Western blot and immunofluorescence analyses showed that DAS decreased the H₂O₂-induced upregulation of the autophagy marker Beclin-1 and the LC3 II/LC3 I ratio and upregulated the p62 protein level. Mechanistically, DAS inhibited autophagy through the activation of the classical PI3K/AKT/mTOR signaling pathway and protected chondrocytes from apoptosis. In addition, DAS alleviated the H₂O₂-induced degradation of type II collagen and the high expression of matrix metalloproteinase 3 (MMP3) and MMP13.

CONCLUSION

Our research demonstrated that DAS alleviated chondrocyte autophagy caused by H₂O₂ through activation of the PI3K/AKT/mTOR signaling pathway and protected chondrocytes from apoptosis and matrix degradation. In conclusion, these findings suggest that DAS may serve as a promising therapeutic strategy for OA.

Silencing of IRF7 ameliorates osteoarthritis by inhibiting chondrocyte pyroptosis via targeting FGF21

Osteoarthritis (OA) is the most common joint disease which can lead to serious disability. Interferon regulatory factor 7 (IRF7) is a member of the interferon regulatory factor family. This study aimed to explore the function and potential mechanism of IRF7 in OA. Our results found that IRF7 was increased in LPS-stimulated C28/I2 chondrocytes and in OA mice established with medial menisco-tibial ligament (MMTL) transection. IRF7 silencing enhanced cell viability, reduced IL-18 and IL-1β levels and suppressed cell apoptosis. IRF7 knockdown decreased ROS and LDH levels, and inhibited pyroptosis in LPS-treated chondrocytes. IRF7 negatively regulated FGF21 expression. FGF21 overexpression alleviated pyroptosis in LPS-stimulated chondrocytes. Knockdown of IRF7 improved OA injury in mice. In conclusion, our study demonstrates that silencing of IRF7 alleviates OA by inhibiting chondrocyte pyroptosis via upregulation of FGF21.

Circular RNA SLTM as a miR-421-competing endogenous RNA to mediate HMGB2 expression stimulates apoptosis and inflammation in arthritic chondrocytes

Osteoarthritis (OA) is the most common age-related joint disease characterized by chronic inflammation, progressive articular cartilage destruction, and subchondral sclerosis. Accumulating evidence suggests that circular RNAs (circRNAs) play key roles in OA, but the function of circSLTM in OA remains greatly unknown. Therefore, this study focused on interleukin-1β (IL-1β)-treated primary human chondrocytes as well as a rat model to investigate the expression pattern and functional role of circSLTM in OA in vitro and in vivo. CircSLTM and high mobility group protein B2 (HMGB2) were upregulated in IL-1β-induced chondrocytes, whereas miR-421 was downregulated. Knockdown of circSLTM or overexpression of miR-421 ameliorated IL-1β-induced chondrocyte apoptosis and inflammation. The regulatory relationship between circSLTM and miR-421, as well as that between miR-421 and HMGB2, was predicted by bioinformatics and then verified by the RNA immunoprecipitation experiment and dual-luciferase reporter gene assay. Furthermore, silencing of circSLTM increased cartilage destruction and decreased cartilage tissue apoptosis rate and inflammation in a rat model of OA. Taken together, our findings demonstrate the fundamental role of circSLTM in OA progression and provide a potential molecular target for OA therapy.

Chemical Composition of Hazelnut Skin Food Waste and Protective Role against Advanced Glycation End-Products (AGEs) Damage in THP-1-Derived Macrophages

Glycation and the accumulation of advanced glycation end-products (AGEs) are known to occur during aging, diabetes and neurodegenerative diseases. Increased glucose or methylglyoxal (MGO) levels in the blood of diabetic patients result in increased AGEs. A diet rich in bioactive food compounds, like polyphenols, has a protective effect. The aim of this work is to evaluate the capacity of hazelnut skin polyphenolic extract to protect THP-1-macrophages from damage induced by AGEs. The main polyphenolic subclass was identified and quantified by means of HPLC/MS and the Folin–Ciocalteu method. AGEs derived from incubation of bovine serum albumin (BSA) and MGO were characterized by fluorescence. Cell viability measurement was performed to evaluate the cytotoxic effect of the polyphenolic extract in macrophages. Reactive oxygen species’ (ROS) production was assessed by the H2-DCF-DA assay, the inflammatory response by real-time PCR for gene expression, and the ELISA assay for protein quantification. We have shown that the polyphenolic extract protected cell viability from damage induced by AGEs. After treatment with AGEs, macrophages expressed high levels of pro-inflammatory cytokines and ROS, whereas in co-treatment with polyphenol extract there was a reduction in either case. Our study suggests that hazelnut skin polyphenol-rich extracts have positive effects and could be further investigated for nutraceutical applications.

Ceria Nanoparticles Alleviated Osteoarthritis through Attenuating Senescence and Senescence-Associated Secretory Phenotype in Synoviocytes

Accumulation of senescent cells is the prominent risk factor for osteoarthritis (OA), accelerating the progression of OA through a senescence-associated secretory phenotype (SASP). Recent studies emphasized the existence of senescent synoviocytes in OA and the therapeutic effect of removing senescent synoviocytes. Ceria nanoparticles (CeNP) have exhibited therapeutic effects in multiple age-related diseases due to their unique capability of ROS scavenging. However, the role of CeNP in OA remains unknown. Our results revealed that CeNP could inhibit the expression of senescence and SASP biomarkers in multiple passaged and hydrogen-peroxide-treated synoviocytes by removing ROS. In vivo, the concentration of ROS in the synovial tissue was remarkably suppressed after the intra-articular injection of CeNP. Likewise, CeNP reduced the expression of senescence and SASP biomarkers as determined by immunohistochemistry analysis. The mechanistic study showed that CeNP inactivated the NFκB pathway in senescent synoviocytes. Finally, safranin O-fast green staining showed milder destruction of articular cartilage in the CeNP-treated group compared with the OA group. Overall, our study suggested that CeNP attenuated senescence and protected cartilage from degeneration via scavenging ROS and inactivating the NFκB signaling pathway. This study has potentially significant implications in the field of OA as it provides a novel strategy for OA treatment.

Comparing the healing properties of intra-articular injection of human dental pulp stem cells and cell-free-secretome on induced knee osteoarthritis in male rats

OBJECTIVE

Osteoarthritis (OA) is a common and painful joint disease with multifactorial causes. Stem cells, due to their high ability to reproduce and differentiate, have created a new horizon in tissue engineering of cartilage and bone. Secretions are one of the new therapies that can be used with stem cells or separately. This study aimed to compare the healing effects of human dental pulp stem cells, cell-free secretome, and human dental pulp mesenchymal stem cells with secretome in the induced OA in male rats.

METHODS

Dental pulp mesenchymal stem cells were isolated and prepared from human dental pulp. The collagenase type II was injected into the knee of twenty-five male Sprague-Dawley rats, and after 10 weeks, OA was confirmed. Rats were divided into five groups (n = 5): 1) Human dental pulp stem cells plus secretome (HDP+Sec); 2) Human dental pulp stem cells (HDP); 3) Secretome (Sec); 4) Hyalgan as the positive control (Hya); 5) No treatment as the negative control (Ctrl). After 12 weeks since OA was confirmed, the healing process was examined by histopathology and radiology evaluations.

RESULTS

Histopathological evaluations, radiological assessments, and matrix indexes in three treatment groups significantly improved compared to the Ctrl and Hya groups. Surface in HDP+Sec was significantly better than the Ctrl group. In radiological evaluations, a significant decrease in OA was observed in the three treatment groups in comparison with the Ctrl groups. There was no significant difference between the treatment groups in any radiological and histopathological evaluations. HDP + Sec group slightly records better results compared to Sec or HDP treatment groups.

CONCLUSION

It was concluded that human dental pulp stem cells and their secretome promote cartilage regeneration due to their cell protective potential as well as matrix degeneration reduction capacity.

The Role of Tocotrienol in Arthritis Management-A Scoping Review of Literature

Arthritis is a cluster of diseases impacting joint health and causing immobility and morbidity in the elderly. Among the various forms of arthritis, osteoarthritis (OA) and rheumatoid arthritis (RA) are the most common. Currently, satisfying disease-modifying agents for arthritis are not available. Given the pro-inflammatory and oxidative stress components in the pathogenesis of arthritis, tocotrienol, a family of vitamin E with both anti-inflammatory and antioxidant properties, could be joint-protective agents. This scoping review aims to provide an overview of the effects of tocotrienol on arthritis derived from the existing scientific literature. A literature search using PubMed, Scopus and Web of Science databases was conducted to identify relevant studies. Only cell culture, animal and clinical studies with primary data that align with the objective of this review were considered. The literature search uncovered eight studies investigating the effects of tocotrienol on OA (n = 4) and RA (n = 4). Most of the studies were preclinical and revealed the positive effects of tocotrienol in preserving joint structure (cartilage and bone) in models of arthritis. In particular, tocotrienol activates the self-repair mechanism of chondrocytes exposed to assaults and attenuates osteoclastogenesis associated with RA. Tocotrienol also demonstrated strong anti-inflammatory effects in RA models. The single clinical trial available in the literature showcases that palm tocotrienol could improve joint function among patients with OA. In conclusion, tocotrienol could be a potential anti-arthritic agent pending more results from clinical studies.

Polysaccharides as antioxidants and prooxidants in managing the double-edged sword of reactive oxygen species

Polysaccharides, a class of naturally occurring carbohydrates, were widely presented in animals, plants, and microorganisms. Recently, health benefits of polysaccharides have attracted much attention due to their unique characteristics in reactive oxygen species (ROS) management. ROS, by-products of aerobic metabolism linked to food consumption, exhibited a dual role in protecting cells and fostering pathogenesis collectively termed double-edged sword. Some interesting studies reported that polysaccharides could behave as prooxidants under certain conditions, besides antioxidant capacities. Potentiation of the bright side of ROS could contribute to the host defense that was vitally important for the polysaccharides acting as biological response modifiers. Correspondingly, disease prevention of polysaccharides linked to the management of ROS production was systematically described and discussed in this review. Furthermore, major challenges and future prospects were presented, aiming to provide new insight into applying polysaccharides as functional food ingredients and medicine.

Green tea actions on miRNAs expression – An update

Compounds derived from plants have been widely studied in the context of metabolic diseases and associated clinical conditions. In this regard, although the effects of Camellia sinensis plant, from which various types of teas, such as green tea, originate, have been vastly reported in the literature, the mechanisms underlying these effects remain elusive. A deep search of the literature showed that green tea's action in different cells, tissues, and diseases is an open field in the research of microRNAs (miRNAs). miRNAs are important communicator molecules between cells in different tissues implicated in diverse cellular pathways. They have emerged as an important linkage between physiology and pathophysiology, raising the issue of polyphenols can act also by changing miRNA expression. miRNAs are short, non-coding endogenous RNA, which silence the gene functions by targeting messenger RNA (mRNA) through degradation or translation repression. Therefore, the aim of this review is to present the studies that show the main compounds of green tea modulating the expression of miRNAs in inflammation, adipose tissue, skeletal muscle, and liver. We provide an overview of a few studies that have tried to demonstrate the role of miRNAs associated with the beneficial effects of compounds from green tea. We have emphasized that there is still a considerable gap in the literature investigating the role and likely involvement of miRNAs in the extensive beneficial health effects of green tea compounds already described, indicating miRNAs as potential polyphenols' mediators with a promising field to be investigated.

Integrated Cascade Nanozyme Remodels Chondrocyte Inflammatory Microenvironment in Temporomandibular Joint Osteoarthritis via Inhibiting ROS-NF-κB and MAPK Pathways

Temporomandibular joint osteoarthritis (TMJ OA) is a degenerative joint disease with no complete cure at present. Notably, the inflammatory microenvironment in TMJ OA is modulated by oxidative stress, which impacts cartilage metabolism, chondrocyte apoptosis, inflammatory cytokine release, and extracellular matrix (ECM) synthesis. Thus, it is reasoned that reducing excess reactive oxygen species (ROS) in the chondrocyte microenvironment may be an effective therapeutic strategy for TMJ OA. Recently, cascade nanozymes, including Pt@PCN222-Mn, have been exploited to treat ROS-associated diseases. Nevertheless, cascade nanozymes are not employed for TMJ OA therapy. To fill this gap, it is explored whether the Pt@PCN222-Mn cascade nanozyme could be applied to the treatment of TMJ OA. The in vitro results demonstrate that the Pt@PCN222-Mn nanozyme can inhibit the production of inflammatory factors, the degradation of ECM, and the apoptosis of chondrocytes by inhibiting the ROS-nuclear factor kappa-B (NF-κB_ and mitogen-activated protein kinase signaling pathways. The in vivo results further demonstrate that the Pt@PCN222-Mn nanozyme can delay the progression of TMJ OA in the rat unilateral anterior crossbite model. It is believed that insightful perspectives on the application of nanozymes in TMJ OA will be provided here.

Air pollution exposure and auto-inflammatory and autoimmune diseases of the musculoskeletal system: a review of epidemiologic and mechanistic evidence

Auto-inflammatory and autoimmune diseases of the musculoskeletal system can be perceived as a spectrum of rheumatic diseases, with the joints and connective tissues are eroded severely that progressively develop chronic inflammation and lesion. A wide range of risk factors represented by genetic and environmental factors have been uncovered by population-based surveys and experimental studies. Lately, the exposure to air pollution has been found to be potentially involved in the mechanisms of occurrence or development of such diseases, principally manifest in oxidative stress, local and systemic inflammation, and epigenetic modifications, as well as the mitochondrial dysfunction, which has been reported to participate in the intermediate links. The lungs might serve as a starting area of air pollutants, which would cause oxidative stress-induced bronchial-associated lymphoid tissue (iBALT) to further to influence T, B cells, and the secretion of pro-inflammatory cytokines. The binding of aromatic hydrocarbon receptor (AhR) to the corresponding contaminant ligands tends to regulate the reaction of Th17 and Tregs. Furthermore, air pollution components might spur on immune and inflammatory responses by damaging mitochondria that could interact with and exacerbate oxidative stress and pro-inflammatory cytokines. In this review, we focused on the association between air pollution and typical auto-inflammatory and autoimmune diseases of the musculoskeletal system, mainly including osteoarthritis (OA), rheumatoid arthritis (RA), spondyloarthritis (SpA) and juvenile idiopathic arthritis (JIA), and aim to collate the mechanisms involved and the potential channels. A complete summary and in-depth understanding of the autoimmune and inflammatory effects of air pollution exposure should hopefully contribute new perspectives on how to formulate better public health policies to alleviate the adverse health effects of air pollutants.

Pleiotropic Effects of Metformin in Osteoarthritis

The involvement of the knee joint is the most common localization of the pathological process in osteoarthritis (OA), which is associated with obesity in over 50% of the patients and is mediated by mechanical, inflammatory, and metabolic mechanisms. Obesity and the associated conditions (hyperglycemia, dyslipidemia, and hypertension) have been found to be risk factors for the development of knee OA, which has led to the emerging concept of the existence of a distinct phenotype, i.e., metabolic knee OA. Combined assessment of markers derived from dysfunctional adipose tissue, markers of bone and cartilage metabolism, as well as high-sensitivity inflammatory markers and imaging, might reveal prognostic signs for metabolic knee OA. Interestingly, it has been suggested that drugs used for the treatment of other components of the metabolic syndrome may also affect the clinical course and retard the progression of metabolic-associated knee OA. In this regard, significant amounts of new data are accumulating about the role of metformin-a drug, commonly used in clinical practice with suggested multiple pleiotropic effects. The aim of the current review is to analyze the current views about the potential pleiotropic effects of metformin in OA. Upon the analysis of the different effects of metformin, major mechanisms that might be involved in OA are the influence of inflammation, oxidative stress, autophagy, adipokine levels, and microbiome modulation. There is an increasing amount of evidence from in vitro studies, animal models, and clinical trials that metformin can slow OA progression by modulating inflammatory and metabolic factors that are summarized in the current up-to-date review. Considering the contemporary concept about the existence of metabolic type knee OA, in which the accompanying obesity and systemic low-grade inflammation are suggested to influence disease course, metformin could be considered as a useful and safe component of the personalized therapeutic approach in knee OA patients with accompanying type II diabetes or obesity.

Wheatgrass extract has chondroprotective and anti-inflammatory effects on porcine cartilage

Lameness is a commonly observed disorder in sows and negatively impacts both animal welfare and the profitability of the pig sector. The purpose of this study was to determine anti-inflammatory and/or chondroprotective effects of wheatgrass (WG) on porcine cartilage explants stimulated with lipopolysaccharide (LPS). Explants were aseptically prepared from the intercarpal joints of nine market-weight pigs and placed in culture at 37°C for a total of 120 hours. For the final 96 hours, explants were conditioned with an aqueous extract of WG (0, 5 or 15 μg/mL), and for the final 48 hours explants were stimulated with LPS (0 or 10 µg/mL). Media was removed and replaced every 24 hours. Samples from the final 48 hours were analyzed for biomarkers of cartilage inflammation [prostaglandin E2 (PGE2) and nitric oxide (NO)] and cartilage structure [glycosaminoglycan (GAG)], and cartilage explants were stained for an estimate of cell viability. Stimulation of explants with LPS significantly increased media concentrations of PGE2, GAG and NO compared with that from unstimulated explants. LPS stimulation did not significantly affect cell viability. Conditioning of explants with WG (5 μg/mL) significantly reduced LPS-stimulated cartilage release of PGE2, NO, and GAG (5 and 15 μg/mL), without impairing chondrocyte viability. These data provide evidence for a non-cytotoxic chondroprotective and anti-inflammatory effect of WG extract in cartilage and suggest a role of WG in protection against cartilage breakdown, inflammation, and pain associated with osteoarthritis.

Dendrobine Alleviates Cellular Senescence and Osteoarthritis via the ROS/NF-κB Axis

Osteoarthritis (OA) is a degenerative joint disease characterized by low-grade inflammation and cartilage degradation. Dendrobine (DEN) is reported to inhibit inflammation and oxidative stress in some diseases, but its role in chondrocyte senescence and OA progress has not yet been elucidated. Our study aimed to explore the protective effects of DEN on OA both in vitro and in vivo. We found that DEN inhibited extracellular matrix (ECM) degradation and promoted ECM synthesis. Meanwhile, DEN inhibited senescence-associated secretory phenotype (SASP) factors expression and senescence phenotype in IL-1β-treated chondrocytes. Furthermore, DEN improved mitochondrial function and reduced the production of intracellular reactive oxygen species (ROS). Also, DEN suppressed IL-1β-induced activation of the NF-κB pathway. Further, using NAC (ROS inhibitor), we found that DEN might inhibit NF-κB cascades by reducing ROS. Additionally, X-ray, micro-CT, and histological analyses in vivo demonstrated that DEN significantly alleviated cartilage inflammation, ECM degradation, and subchondral alterations in OA progression. In conclusion, DEN inhibits SASP factors expression and senescence phenotype in chondrocytes and alleviated the progression of OA via the ROS/NF-κB axis, which provides innovative strategies for the treatment of OA.

Potential Involvement of Oxidative Stress in Ligamentum Flavum Hypertrophy

Oxidative stress (OS) results in many disorders, of which degenerative musculoskeletal conditions are no exception. However, the interaction between OS and ligamentum flavum (LF) hypertrophy in lumbar spinal canal stenosis is not clearly understood. The first research question was whether OS was involved in LF hypertrophy, and the second was whether the antioxidant N-acetylcysteine (NAC) was effective on LF hypertrophy. In total, 47 LF samples were collected from patients with lumbar spinal disorders. The cross-sectional area of LF was measured on axial magnetic resonance imaging. Immunohistochemistry of 8-OHdG and TNF-α were conducted on human LF samples. A positive association was found between 8-OHdG or TNF-α expression and cross-sectional area of LF. Flow cytometry analysis showed that H₂O₂, buthionine sulfoximine, and TNF-α treatment significantly increased intracellular reactive oxygen species in primary LF cells. NAC inhibited the induction of LF hypertrophy markers by OS or TNF in a real-time reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay. Western blotting analysis indicated that p38, Erk, and p65 phosphorylation were involved in intracellular OS signaling in LF cells. In conclusion, our results indicated that OS could be a therapeutic target for LF hypertrophy. Although this study included no in vivo studies to examine the longitudinal efficacy of NAC on LF hypertrophy, NAC may have potential as a therapeutic agent against lumbar spinal canal stenosis.

Gardenoside ameliorates inflammation and inhibits ECM degradation in IL-1β-treated rat chondrocytes via suppressing NF-κB signaling pathways

Osteoarthritis (OA) places a significant burden on society and finance, and there is presently no effective treatment beside late replacement surgery and symptomatic relief. The therapy of OA requires additional research. Gardenoside is a naturally compound extracted from Gardenia jasminoides Ellis, which has a variety of anti-inflammatory effects. However, few studies have been conducted to determine the role of gardenoside in OA. This study aimed to explore whether gardenoside has effect in OA treatment. Rat primary chondrocytes were treated with IL-1β to simulate inflammatory environmental conditions and OA in vitro. We examined the effects of gardenoside at concentrations ranging from 0 to 200 μM on the viability of rat chondrocytes and selected 10 μM for further study. Via in vitro experiments, our study found that gardenoside lowers the gene expression of COX-2, iNOS, IL-6, and reduced the ROS production of chondrocytes induced by IL-1β. Moreover, it effectively alleviates ECM degradation caused by IL-1β and promotes the ECM synthesis in chondrocytes by upregulating collagen-II and the ACAN expression, downregulating the expression of MMP-3, MMP-13, and ADAMTS-5 expression. Further, our study showed that gardenoside inhibits NF-κB signaling pathway activated by IL-1β in chondrocytes. We established an OA rat model by anterior cruciate ligament transection (ACLT). The animals were then periodically injected with gardenoside into the knee articular cavity. In vivo study suggested that gardenoside attenuates OA progression in rats. As a whole, in vitro and in vivo results highlight gardenoside is a promising OA treatment agent.

Evaluation of the anti-inflammatory, antioxidant, and cytotoxic potential of Cardamine amara L. (Brassicaceae): A comprehensive biochemical, toxicological, and in silico computational study

Introduction: Cardamine amara L. (Brassicaceae) is an important edible plant with ethnomedicinal significance. This study aimed at evaluating the phytochemical composition, anti-inflammatory, antioxidant and cytotoxicity aspects of the hydro-alcoholic extract of C. amara (HAECA). Methods: The phytochemical composition was evaluated through total phenolic contents (TPC), total flavonoid contents (TFC) determination and UPLC-QTOF-MS profiling. Anti-inflammatory evaluation of HAECA was carried out through the carrageenan induced paw edema model. Four in vitro methods were applied in the antioxidant evaluation of HAECA. MTT assay was used to investigate the toxicity profile of the species against human normal liver cells (HL7702), human liver cancer cell lines (HepG2) and human breast cancer cell lines (MCF-7). Three major compounds (Gentisic acid, skullcapflavone and conidendrine) identified in UPLC-Q-TOF-MS analysis were selected for in silico study against cyclooxygenase (COX-I and COX-II). Results and Discussion: The findings revealed that HAECA is rich in TPC (39.32 ± 2.3 mg GAE/g DE) and TFC (17.26 ± 0.8 mg RE/g DE). A total of 21 secondary metabolites were tentatively identified in UPLC-Q-TOF-MS analysis. In the MTT cytotoxicity assay, the extract showed low toxicity against normal cell lines, while significant anticancer activity was observed against human liver and breast cancer cells. The carrageenan induced inflammation was inhibited by HAECA in a dose dependent manner and showed a marked alleviation in the levels of oxidative stress (catalase, SOD, GSH) and inflammatory markers (TNF-α, IL-1β). Similarly, HAECA showed maximum antioxidant activity through the Cupric reducing power antioxidant capacity (CUPRAC) assay (31.21 ± 0.3 mg TE/g DE). The in silico study revealed a significant molecular docking score of the three studied compounds against COX-I and COX-I. Conclusively the current study encourages the use of C. amara as a novel polyphenolic rich source with anti-inflammatory and antioxidant potential and warrants further investigations on its toxicity profile.

Sirtuins in osteoarthritis: current understanding

Osteoarthritis (OA) is a common disease characterized by severe chronic joint pain, that imposes a large burden on elderly people. OA is a highly heterogeneous disease, and multiple etiologies contribute to its progression. Sirtuins (SIRTs) are Class III histone deacetylases (HDACs) that regulate a comprehensive range of biological processes such as gene expression, cell differentiation, and organism development, and lifespan. Over the past three decades, increasing evidence has revealed that SIRTs are not only important energy sensors but also protectors against metabolic stresses and aging, and an increasing number of studies have focused on the functions of SIRTs in OA pathogenesis. In this review, we illustrate the biological functions of SIRTs in OA pathogenesis from the perspectives of energy metabolism, inflammation, autophagy and cellular senescence. Moreover, we offer insights into the role played by SIRTs in regulating circadian rhythm, which has recently been recognized to be crucial in OA development. Here, we provide the current understanding of SIRTs in OA to guide a new direction for OA treatment exploration.

Multiscale In Silico Modeling of Cartilage Injuries

Injurious loading of the joint can be accompanied by articular cartilage damage and trigger inflammation. However, it is not well-known which mechanism controls further cartilage degradation, ultimately leading to post-traumatic osteoarthritis. For personalized prognostics, there should also be a method that can predict tissue alterations following joint and cartilage injury. This chapter gives an overview of experimental and computational methods to characterize and predict cartilage degradation following joint injury. Two mechanisms for cartilage degradation are proposed. In (1) biomechanically driven cartilage degradation, it is assumed that excessive levels of strain or stress of the fibrillar or non-fibrillar matrix lead to proteoglycan loss or collagen damage and degradation. In (2) biochemically driven cartilage degradation, it is assumed that diffusion of inflammatory cytokines leads to degradation of the extracellular matrix. When implementing these two mechanisms in a computational in silico modeling workflow, supplemented by in vitro and in vivo experiments, it is shown that biomechanically driven cartilage degradation is concentrated on the damage environment, while inflammation via synovial fluid affects all free cartilage surfaces. It is also proposed how the presented in silico modeling methodology may be used in the future for personalized prognostics and treatment planning of patients with a joint injury.

Natural Compounds: Potential Therapeutics for the Inhibition of Cartilage Matrix Degradation in Osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease characterized by enzymatic degradation of the cartilage extracellular matrix (ECM) causing joint pain and disability. There is no disease-modifying drug available for the treatment of OA. An ideal drug is expected to stop cartilage ECM degradation and restore the degenerated ECM. The ECM primarily contains type II collagen and aggrecan but also has minor quantities of other collagen fibers and proteoglycans. In OA joints, the components of the cartilage ECM are degraded by matrix-degrading proteases and hydrolases which are produced by chondrocytes and synoviocytes. Matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS5) are the major collagenase and aggrecanase, respectively, which are highly expressed in OA cartilage and promote cartilage ECM degradation. Current studies using various in vitro and in vivo approaches show that natural compounds inhibit the expression and activity of MMP-13, ADAMTS4, and ADAMTS5 and increase the expression of ECM components. In this review, we have summarized recent advancements in OA research with a focus on natural compounds as potential therapeutics for the treatment of OA with emphasis on the prevention of cartilage ECM degradation and improvement of joint health.

Research progress on the mechanism of interleukin-1β on epiphyseal plate chondrocytes

Epiphyseal plate injury, a common problem in pediatric orthopedics, may result in poor bone repair or growth defects. Epiphyseal plate, also known as growth plate is a layer of hyaline cartilage tissue between the epiphysis and metaphyseal and has the ability to grow longitudinally. Under normal physiological conditions, the epiphyseal plate has a certain axial resistance to stress, but it is fragile in growth phase and can be damaged by excessive stress, leading to detachment or avulsion of the epiphysis, resulting in life-long devastating consequences for patients. There is an obvious inflammatory response in the phase of growth plate injury, the limited physiological inflammatory response locally favors tissue repair and the organism, but uncontrolled chronic inflammation always leads to tissue destruction and disease progression. Interleukin-1β (IL-1β), as representative inflammatory factors, not only affect the inflammatory phase response to bone and soft tissue injury, but have a potentially important role in the later repair phase, though the exact mechanism is not fully understood. At present, epiphyseal plate injuries are mainly treated by corrective and reconstructive surgery, which is highly invasive with limited effectiveness, thus new therapeutic approaches are urgently needed, so a deeper understanding and exploration of the pathological mechanisms of epiphyseal plate injuries at the cellular molecular level is an entry point. In this review, we fully introduced the key role of IL-1 in the progression of epiphyseal plate injury and repair, deeply explored the mechanism of IL-1 on the molecular transcript level and endocrine metabolism of chondrocytes from multiple aspects, and summarized other possible mechanisms to provide theoretical basis for the clinical treatment and in-depth study of epiphyseal plate injury in children.