Emodin ameliorates cartilage degradation in osteoarthritis by inhibiting NF-κB and Wnt/β-catenin signaling in-vitro and in-vivo

Protective effects of emodin on subchondral bone and articular cartilage in osteoporotic osteoarthritis rats: A preclinical study

BACKGROUND

Osteoporotic osteoarthritis (OP-OA) is a severe pathological form of OA, urgently requiring precise management strategies and more efficient interventions. Emodin (Emo), an effective ingredient found in the traditional Chinese medicine rhubarb, has been dEmonstrated to promote osteogenesis and inhibit extracellular matrix degradation. In this study, we aimed to investigate the interventional effects of Emo on the subchondral bone and cartilage of the knee joints in OP-OA model rats.

METHODS

Thirty-two SD rats were randomly and equally divided into sham, OP-OA, Emo low-dose, and Emo high-dose groups. Micro-CT scanning was conducted to examine the bone microstructure of the rat knee joints. H&E and Safranin O and Fast Green staining (SO&FG) were performed for the pathomorphological evaluation of the rat cartilage tissues. ELISA was used to estimate the rat serum expression levels of inflammatory factors, including interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Additionally, the CCK-8 assay was utilized for determining the viability of Emo-treated BMSCs. Western blot and real-time PCR analyses were also employed to measure the bone formation indexes and cartilage synthesis and decomposition indexes. Lastly, the osteogenic and chondrogenic differentiation efficiency of the BMSCs was investigated via Alizarin Red and Alcian Blue staining.

RESULTS

Emo intervention alleviated the bone microstructural disruption of the subchondral bone and articular cartilage in the OP-OA rats and up-regulated the expression of bone and cartilage anabolic metabolism indicators, decreased the expression of cartilage catabolism indicators, and diminished the expression of inflammatory factors in the rat serum (P<0.05). Furthermore, Emo reversed the decline in the osteogenic and chondrogenic differentiation ability of the BMSCs (P<0.05).

CONCLUSION

Emo intervention mitigates bone loss and cartilage damage in OP-OA rats and promotes the osteogenic and chondrogenic differentiation of BMSCs.

[Translated article] Infrapatellar fat pad resection effect on the osteoarthritis development: Experimental study in sheep

INTRODUCTION

The fat of the synovial joints can be used to maintain the joint structure. Our objective is to analyse the evolution of joint degeneration in knees with and without adipose pack.

MATERIAL AND METHODOLOGY

In six sheep, the anterior cruciate ligament was sectioned in both knees, to cause osteoarthritis. In one group the fat pack was preserved and in another group it was completely removed. We performed a histological and molecular biology study analyzing the expression, in the synovial membrane, subchondral bone, cartilage, fat, meniscus, and synovial fluid, of RUNX2, PTHrP, cathepsin-K, and MCP1.

RESULTS

We did not find morphological differences. We found increased expression of RUNX2 in synovial membrane, PTHrP and Cathepsin K in synovial fluid in the group without fat, and increased expression of RUNX2 in the meniscus and MCP1 in synovial fluid in the group with fat.

CONCLUSION

Infrapatellar fat participates in the inflammatory process that accompanies osteoarthritis, since Hoffa fat pad resection alters pro-inflammatory markers, while the model with intact fat increases the pro-inflammatory marker MCP1 in synovial fluid.

Infrapatellar Fat Pad resection effect on the osteoarthritis development: Experimental study in sheep

INTRODUCTION

The fat of the synovial joints can be used to maintain the joint structure. Our objective is to analyze the evolution of joint degeneration in knees with and without adipose pack.

MATERIAL AND METHODOLOGY

In six sheep, the anterior cruciate ligament was sectioned in both knees, to cause osteoarthritis. In one group the fat pack was preserved and in another group it was completely removed. We performed a histological and molecular biology study analyzing the expression, in the synovial membrane, subchondral bone, cartilage, fat, meniscus, and synovial fluid, of RUNX2, PTHrP, cathepsin-K, and MCP1.

RESULTS

We did not find morphological differences. We found increased expression of RUNX2 in synovial membrane, PTHrP and Cathepsin K in synovial fluid in the group without fat, and increased expression of RUNX2 in the meniscus and MCP1 in synovial fluid in the group with fat.

CONCLUSION

Infrapatellar fat participates in the inflammatory process that accompanies osteoarthritis, since Hoffa fat pad resection alters pro-inflammatory markers, while the model with intact fat increases the pro-inflammatory marker MCP1 in synovial fluid.

Natural products in osteoarthritis treatment: bridging basic research to clinical applications

Osteoarthritis (OA) is the most prevalent degenerative musculoskeletal disease, severely impacting the function of patients and potentially leading to disability, especially among the elderly population. Natural products (NPs), obtained from components or metabolites of plants, animals, microorganisms etc., have gained significant attention as important conservative treatments for various diseases. Recently, NPs have been well studied in preclinical and clinical researches, showing promising potential in the treatment of OA. In this review, we summed up the main signaling pathways affected by NPs in OA treatment, including NF-κB, MAPKs, PI3K/AKT, SIRT1, and other pathways, which are related to inflammation, anabolism and catabolism, and cell death. In addition, we described the therapeutic effects of NPs in different OA animal models and the current clinical studies in OA patients. At last, we discussed the potential research directions including in-depth analysis of the mechanisms and new application strategies of NPs for the OA treatment, so as to promote the basic research and clinical transformation in the future. We hope that this review may allow us to get a better understanding about the potential bioeffects and mechanisms of NPs in OA therapy, and ultimately improve the effectiveness of NPs-based clinical conservative treatment for OA patients.

Targeting WNT signalling pathways as new therapeutic strategies for osteoarthritis

Osteoarthritis (OA) is a highly prevalent chronic joint disease and the leading cause of disability. Currently, no drugs are available to control joint damage or ease the associated pain. The wingless-type (WNT) signalling pathway is vital in OA progression. Excessive activation of the WNT signalling pathway is pertinent to OA progression and severity. Therefore, agonists and antagonists of the WNT pathway are considered potential drug candidates for OA treatment. For example, SM04690, a novel small molecule inhibitor of WNT signalling, has demonstrated its potential in a recent phase III clinical trial as a disease-modifying osteoarthritis drug (DMOAD). Therefore, targeting the WNT signalling pathway may be a distinctive approach to developing particular agents helpful in treating OA. This review aims to update the most recent progress in OA drug development by targeting the WNT pathway. In this, we introduce WNT pathways and their crosstalk with other signalling pathways in OA development and highlight the role of the WNT signalling pathway as a key regulator in OA development. Several articles have reviewed the Wnt pathway from different aspects. This candid review provides an introduction to WNT pathways and their crosstalk with other signalling pathways in OA development, highlighting the role of the WNT signalling pathway as a key regulator in OA development with the latest research. Particularly, we emphasise the state-of-the-art in targeting the WNT pathway as a promising therapeutic approach for OA and challenges in their development and the nanocarrier-based delivery of WNT modulators for treating OA.

Emodin ameliorates matrix degradation and apoptosis in nucleus pulposus cells and attenuates intervertebral disc degeneration through LRP1 in vitro and in vivo

Low back pain (LBP) is the leading cause of disability worldwide, with a strong correlation to intervertebral disc degeneration (IDD). Inflammation-induced extracellular matrix (ECM) degradation plays a major role in IDD's progression. Emodin, known for its anti-inflammatory effects and ability to inhibit ECM degradation in osteoarthritis, but its role in IDD is unclear. Our study aimed to explore emodin's role and mechanisms on IDD both in vivo and in vitro. We discovered that emodin positively regulated anabolic markers (COL2A1, aggrecan) and negatively impacted catabolic markers (MMP3, MMP13) in nucleus pulposus cells, while also inhibiting cell apoptosis under inflammation environment. We revealed that emodin inhibits inflammation-induced NF-ĸB activation by suppressing the degradation of LRP1 via the proteasome pathway. Additionally, LRP1 was validated as essential to emodin's regulation of ECM metabolism and apoptosis, both in vitro and in vivo. Ultimately, we demonstrated that emodin effectively alleviates IDD in a rat model. Our findings uncover the novel pathway of emodin inhibiting ECM degradation and apoptosis through the inhibition of NF-κB via LRP1, thus alleviating IDD. This study not only broadens our understanding of emodin's role and mechanism in IDD treatment but also guides future therapeutic interventions.

Revealing the impact of TOX3 on osteoarthritis: insights from bioinformatics

Osteoarthritis, a prevalent long-term condition of the joints, primarily impacts older individuals, resulting in discomfort, restrictions in mobility, and a decrease in overall well-being. Although Osteoarthritis is widely spread, there is a lack of successful interventions to stop the advancement of the condition. Numerous signaling pathways have been emphasized in recent research on Osteoarthritis, yet the diagnostic significance of numerous genes has not been investigated. To identify genes that were expressed differently in osteoarthritis, we utilized the Gene Expression Omnibus database. To identify marker genes, we built machine learning models including Least Absolute Shrinkage and Selection Operator and Random Forest. We categorized Osteoarthritis samples and performed immune cell infiltration analysis based on the expression patterns of these characteristic genes. Both the Least Absolute Shrinkage and Selection Operator and Random Forest models selected six marker genes (TOX3, ARG1, CST7, RERGL, COL11A1, NCRNA00185) out of a total of 17 differentially expressed genes. The osteoarthritis samples were categorized into two groups, namely a high expression group and a low expression group, based on the median levels of TOX3 expression. Comparative analysis of these groups identified 85 differentially expressed genes, showing notable enrichment in pathways related to lipid metabolism in the group with high expression. Analysis of immune cell infiltration revealed noticeable differences in immune profiles among the two groups. The group with high expression of TOX3 showed a notable increase in Mast cells and Type II IFN Response, whereas B cells, Cytolytic activity, Inflammation-promoting cells, NK cells, pDCs, T cell co-inhibition, Th1 cells, and Th2 cells were significantly decreased. We constructed a ceRNA network for TOX3, revealing 57 lncRNAs and 18 miRNAs involved in 57 lncRNA-miRNA interactions, and 18 miRNA-mRNA interactions with TOX3. Validation of TOX3 expression was confirmed using an external dataset (GSE29746), revealing a notable increase in Osteoarthritis samples. In conclusion, our study presents a comprehensive analysis identifying TOX3 as a potential feature gene in Osteoarthritis. The distinct immune profiles and involvement in fat metabolism pathways associated with TOX3 expression suggest its significance in Osteoarthritis pathogenesis. The study establishes a basis for comprehending the intricate correlation between characteristic genes and Osteoarthritis, as well as for the formulation of individualized therapeutic approaches.

Natural anti-inflammatory products for osteoarthritis: From molecular mechanism to drug delivery systems and clinical trials

Osteoarthritis (OA) is a degenerative joint disease that affects millions globally. The present nonsteroidal anti-inflammatory drug treatments have different side effects, leading researchers to focus on natural anti-inflammatory products (NAIPs). To review the effectiveness and mechanisms of NAIPs in the cellular microenvironment, examining their impact on OA cell phenotype and organelles levels. Additionally, we summarize relevant research on drug delivery systems and clinical randomized controlled trials (RCTs), to promote clinical studies and explore natural product delivery options. English-language articles were searched on PubMed using the search terms "natural products," "OA," and so forth. We categorized search results based on PubChem and excluded "natural products" which are mix of ingredients or compounds without the structure message. Then further review was separately conducted for molecular mechanisms, drug delivery systems, and RCTs later. At present, it cannot be considered that NAIPs can thoroughly prevent or cure OA. Further high-quality studies on the anti-inflammatory mechanism and drug delivery systems of NAIPs are needed, to determine the appropriate drug types and regimens for clinical application, and to explore the combined effects of different NAIPs to prevent and treat OA.

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.

Rhein for treating diabetes mellitus: A pharmacological and mechanistic overview

With the extension of life expectancy and changes in lifestyle, the prevalence of diabetes mellitus is increasing worldwide. Rheum palmatum L. a natural botanical medicine, has been used for thousands of years to prevent and treat diabetes mellitus in Eastern countries. Rhein, the main active component of rhubarb, is a 1, 8-dihydroxy anthraquinone derivative. Previous studies have extensively explored the clinical application of rhein. However, a comprehensive review of the antidiabetic effects of rhein has not been conducted. This review summarizes studies published over the past decade on the antidiabetic effects of rhein, covering the biological characteristics of Rheum palmatum L. and the pharmacological effects and pharmacokinetic characteristics of rhein. The review demonstrates that rhein can prevent and treat diabetes mellitus by ameliorating insulin resistance, possess anti-inflammatory and anti-oxidative stress properties, and protect islet cells, thus providing a theoretical basis for the application of rhein as an antidiabetic agent.

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.

Potential role of nutraceuticals via targeting a Wnt/β-catenin and NF-κB pathway in treatment of osteoarthritis

Osteoarthritis (OA) is a disease due to the aging of the articular cartilage, a post-mitotic tissue that stays functioning until primary homeostatic processes fail. Because of pain and disability, OA significantly influences national healthcare expenses and patient quality of life. It is a whole-joint illness characterized by inflammatory and oxidative signaling pathways and significant epigenetic alterations that cause cartilage extracellular matrix degradation. The canonical Wnt pathway (Wnt/β-catenin pathway) and nuclear factor kappa B (NF-κB) signaling pathways may function in joint tissues by modulating the activity of synovial cells, osteoblasts, and chondrocytes. However, finding innovative ways to treat osteoarthritis and get the joint back to average balance is still a struggle. Nutraceuticals are dietary supplements that promote joint health by balancing anabolic and catabolic signals. New therapeutic methods for OA treatment have been developed based on many research findings that show nutraceuticals have strong anti-inflammation, antioxidant, anti-bone resorption, and anabolic properties. For the treatment of osteoarthritis, we explore the possible involvement of nutraceuticals that target the Wnt/β-catenin and NF-κB pathways. PRACTICAL APPLICATIONS: In keeping with the aging population, osteoarthritis is becoming more widespread. In this extensive research, we studied the role of the Wnt/β-catenin and NF-κB pathway in OA formation and progression. Nutraceuticals that target these OA-related signaling pathways are a viable therapy option. Wnt/β-catenin and NF-κB signaling pathway are inhibited by polyphenols, flavonoids, alkaloids, and vitamins from the nutraceutical category, making them possible therapeutic drugs for OA therapy.

A Study on the Potential Mechanism of Shujin Dingtong Recipe against Osteoarthritis Based on Network Pharmacology and Molecular Docking

Background. With the aging of the social population, Osteoarthritis (OA) has already become a vital health and economic problem globally. Shujin Dingtong recipe (SJDTR) is an effective formula to treat OA in China. Although studies have shown that SJDTR can significantly alleviate OA symptoms, its mechanism still remains unclear. Purpose. This study is aimed at investigating the potential mechanism of SJDTR for the treatment of OA based on network pharmacology and molecular docking. Methods. Main ingredients of SJDTR were retrieved from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. OA disease targets were obtained from the Gene Expression Omnibus (GEO) database. The overlapped targets and signaling pathways were explored using Protein-Protein Interaction (PPI) network, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG). Following this, the core targets were employed to dock with corresponding components via molecular docking in order to further explore the mechanism of SJDTR in the treatment of OA. Results. From network pharmacology, we found 100 active components of SJDTR, 31 drug and OA-related targets, 1161 GO items, and 91 signaling pathways. Based on the analysis with PPI network and molecular docking, TP53, CCNB1, and MMP-2 were selected for the core targets of SJDTR against OA. Molecular docking demonstrated that Quercetin, Baicalein, and Luteolin, had good binding with the TP53, CCNB1, and MMP-2 protein, respectively. Conclusion. To conclude, our study suggested the main ingredients of SJDTR might alleviate the progression of OA through multiple targets and pathways. Additionally, network pharmacology and molecular docking, as new approaches, were adopted for systematically exploring the potential mechanism of SJDTR for the treatment of OA.

Natural emodin reduces myocardial ischemia/reperfusion injury by modulating the RUNX1/miR‑142‑3p/DRD2 pathway and attenuating inflammation

Acute myocardial infarction is one of the leading causes of death worldwide. Although timely reperfusion could attenuate myocardial ischemia injury and reduce mortality, it causes severe secondary injury to the myocardium known as myocardial ischemia/reperfusion injury (MIRI) with unmet clinical needs. Emodin has a protective effect on MIRI in rodents. However, the precise mechanism underlying its pharmacological effect remains poorly understood. Accordingly, the present study used mRNA and microRNA (miRNA) sequencing based on MIRI mouse models to determine the mechanism involved. Emodin was found to prevent MIRI and attenuate the inflammation of myocardium in the MIRI model. In addition, by using an interdisciplinary approach, the present study uncovered that emodin suppressed the runt-related transcription factor 1 (RUNX1), which is a transcription factor of miR-142-3p, in either MIRI or the hypoxia/reoxygenation injury model. Furthermore, miR-142-3p can negatively regulate dopamine receptor D2 (DRD2), which acted as an anti-inflammatory factor to suppress NF-κB-dependent inflammation and prevent MIRI. These results were demonstrated by both cellular hypoxia/reoxygenation and mouse MIRI models. Overall, the present study provided an unrevealed molecular mechanism for emodin function. Emodin could inhibit NF-κB-triggered inflammation in MIRI by regulating the RUNX1/miR-142-3p/DRD2 pathway. Therefore, the RUNX1/miR-142-3p/DRD2 pathway presented a novel target for MIRI treatment, and the application of emodin in clinical practice may improve the treatment of MIRI.

LncRNAs in Osteoarthritis

Osteoarthritis (OA) is a progressive joint disease that affects millions of older adults around the world. With increasing rates of incidence and prevalence worldwide, OA has become an enormous global socioeconomic burden on healthcare systems. Long non-coding ribonucleic acids (lncRNAs), essential functional molecules in many biological processes, are a group of non-coding RNAs that are greater than approximately 200 nucleotides in length. Fast-growing and recent developments in lncRNA research are captivating and represent a novel and promising field in understanding the complexity of OA pathogenesis. The involvement of lncRNAs in OA's pathological processes and their altered expressions in joint tissues, blood and synovial fluid make them attractive candidates for the diagnosis and treatment of OA. We focus on the recent advances in major regulator mechanisms of lncRNAs in the pathophysiology of OA and discuss potential diagnostic and therapeutic uses of lncRNAs for OA. We investigate how upregulation or downregulation of lncRNAs influences the pathogenesis of OA and how we can use lncRNAs to elucidate the molecular mechanism of OA. Furthermore, we evaluate how we can use lncRNAs as a diagnostic marker or therapeutic target for OA. Our study not only provides a comprehensive review of lncRNAs regarding OA's pathogenesis but also contributes to the elucidation of its molecular mechanisms and to the development of diagnostic and therapeutic approaches for OA.

Adsorption Characteristics and Enrichment of Emodin from Marine-Derived Aspergillus flavipes HN4-13 Extract by Macroporous Resin XAD-16

Emodin, a hydroxyanthraquinone derivative, has been used as medicine for more than 2000 years due to its extensive pharmacological activities. Large-scale production of emodin has been achieved by optimizing the fermentation conditions of marine-derived Aspergillus flavus HN4-13 in a previous study. However, the fermentation broth contained complex unknown components, which adversely affected the study of emodin. Herein, the conditions for the enrichment of emodin from A. flavipes HN4-13 extract using XAD-16 resin were optimized, and a separation method with high efficiency, simple operation, a low cost, and a large preparative scale was established. The adsorption process of emodin on the XAD-16 resin conformed to pseudo-second-order kinetics and Langmuir models. The optimal conditions for the adsorption process were as follows: An emodin concentration, flow rate, and loading volume of 0.112 mg/mL, 2 BV/h, and 10 BV, respectively. For desorption, 50% ethanol was used to elute impurities and 80% ethanol was used to desorb emodin. After enrichment with XAD-16 resin, the emodin content increased from 1.16% to 11.48%, and the recovery rate was 75.53% after one-step treatment. These results demonstrate the efficiency of the simple adsorption–desorption strategy, using the XAD-16 resin for emodin enrichment.

Shikonin, a promising therapeutic drug for osteoarthritis that acts via autophagy activation

Osteoarthritis (OA) is a chronic joint degenerative disease characterised by narrowed articular space, formation of surrounding osteophytes, and subchondral bone sclerosis. OA is caused by cartilage degeneration, which is closely correlated with the disequilibrium of anabolism and catabolism in chondrocytes. Previous studies have revealed that autophagy plays a significant role in maintaining the balance of anabolic and catabolic activities. Thus, targeting autophagy may be a promising therapeutic strategy for OA. Shikonin, a traditional Chinese herbal medicine isolated from flavonoid glucuronide, has drawn focus for its role in activating autophagy. In this study, the mRNA and protein level of a disintegrin and metalloproteinase with thrombospondin motifs-5 and matrix metalloproteinases-1 decreased with shikonin treatment, in the IL-1β-induced OA cell model. On the contrary, IL-1β-induced downregulation of Aggrecan and Collagen II was ameliorated following shikonin treatment. In addition, the upregulation of autophagy-related marker genes Beclin-1 and LC3II/LC3I in chondrocytes indicated that autophagy could be activated upon shikonin treatment. Moreover, shikonin's promotion of anabolism in chondrocytes through autophagy activation corresponded with the results from the examination using chloroquine, an autophagy inhibitor. OA mouse cartilage tissues were stained with safranin O and fast green dyes. Results were analysed using the Osteoarthritis Research Society International (OARSI) score, and suggested that mice cartilage degeneration was alleviated after shikonin treatment. Altogether, we identified that shikonin might be a novel promising drug for OA treatment.

Emodin Attenuates the ECM Degradation and Oxidative Stress of Chondrocytes through the Nrf2/NQO1/HO-1 Pathway to Ameliorate Rat Osteoarthritis

Osteoarthritis (OA) substantially reduces the quality of life of the elderly. OA therapy remains a challenge since no treatment options for its causes are so far available. Over recent years, researchers have speculated that emodin may represent a potential treatment strategy for OA. However, it remains unclear whether the mechanism of action of emodin is associated with the inhibition of OA-induced oxidative stress. In the present study, the potential antioxidant mechanism of action of emodin and its protective properties against the development of OA were investigated both in vitro and in vivo. In vitro, emodin inhibited the production of reactive oxygen species (ROS) in chondrocytes induced by hydrogen peroxide (H2O2) and reduced the expression of matrix metalloproteinase (MMP)3 and MMP13 in a concentration-dependent manner. It was found that emodin upregulated the Nrf2/NQO1/HO-1 pathway, thereby attenuating the effects of oxidative stress caused by OA. In a rat model of posttraumatic OA induced by anterior cruciate ligament transection (ACLT), emodin reduced the extent of joint swelling. Emodin attenuated oxidative damage in the cartilage by upregulating superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) activity, reducing malondialdehyde (MDA) concentration and inhibiting the expression of the extracellular matrix (ECM) degradation biomarkers cartilage oligomeric matrix protein (COMP), and C-terminal telopeptide of type I collagen (CTX-I) and type II collagen (CTX-II), thereby reducing cartilage damage. In summary, the present study indicates that emodin reduces ECM degradation and oxidative stress in chondrocytes via the Nrf2/NQO1/HO-1 pathway, thereby ameliorating OA in rats.

Transcriptomics integrated with metabolomics reveals the effect of Lycium barbarum polysaccharide on apoptosis in Nile tilapia (Oreochromis niloticus)

Lycium barbarum polysaccharide (LBP) is one of the main active ingredients in the fruit of L. barbarum L. It has been used as herbal medicine for thousands of years in China. In this study, Nile tilapia (Oreochromis niloticus) was taken as the research object. After feeding tilapia with 5 different doses of LBP (0 mg/kg, 500 mg/kg, 1000 mg/kg, 1500 mg/kg, 2000 mg/kg) for 55 d, it was found that LBP could promote the growth of tilapia, and this effect was the strongest at Group 1500 mg/kg. Apoptosis analysis in the liver and spleen showed that dietary supplementation with 1000 mg/kg LBP had the best protective effect on the spleen and liver in tilapia. Combined transcriptomics and metabolomics of the spleen in tilapia at Group 0 mg/kg and 1000 mg/kg showed that the differentially expressed genes (DEGs) such as NT5C2L1, pmm1, FasL and the differentially metabolites such as xanthine, dGMP, guanine and glutamate were mainly concentrated in signaling pathways such as Purine metabolism and FoxO signaling pathway. In conclusion, LBP regulates the metabolic waste levels of tilapia mainly through Purine metabolism and the FoxO signaling pathway, thereby inhibiting cell apoptosis, improving the utilization of nutrients, and promoting the growth of tilapia. This study not only provides a theoretical basis for the application of LBP in aquatic animals but also provides useful information for the healthy development of the aquaculture.

Jiangzhi Granule attenuates non-alcoholic steatohepatitis by suppressing TNF/NFκB signaling pathway-a study based on network pharmacology

Jiangzhi Granule is a commonly used traditional Chinese medicine for treating non-alcoholic fatty liver disease. However, its key ingredients and underlying mechanisms for attenuating nonalcoholic steatohepatitis (NASH) remain unclear. To address this issue, UPLC-TOF-MS based chemical profiling, network pharmacology and animal experimental validation were employed. First, a total of 56 main ingredients of Jiangzhi Granule and 38 ingredients in the blood and liver (after oral administration) were identified. Then, 170 potential targets of the absorbed ingredients and 50 targets of NASH were identified, and 10 overlapped genes were identified as candidate targets of Jiangzhi Granule for NASH treatment. A Jiangzhi Granule-ingredients-targets-disease network was constructed using Cytoscape software, which included eight main ingredients (such as emodin, resveratrol and quercetin) and 10 candidate targets (such as TNF, IL6 and CCL2). Functional enrichment indicated that the candidate targets were enriched in multiple pathways (such as the TNF signaling pathway). Furthermore, a NASH mice model was constructed and intervened with Jiangzhi Granule. The results revealed that Jiangzhi Granule could ameliorate NASH characteristics, such as histopathological changes and liver cholesterol level. Meanwhile, Jiangzhi Granule significantly decreased the mRNA and protein expression of TNFα in NASH mice liver, suppressed NFκB activation, and inhibited the expression of macrophage activation marker F4/80 and M1-type polarization marker CD11b/CD11c. ELISA assay indicated that Jiangzhi Granule reduced pro-inflammatory cytokines (including TNFα, IL-1β and IL-6) in the liver. Collectively, our results suggested that Jiangzhi Granule could attenuate NASH by suppressing TNF/NFκB signaling mediated macrophage M1-type polarization.

Magnolin exhibits anti-inflammatory effects on chondrocytes via the NF-κB pathway for attenuating anterior cruciate ligament transection-induced osteoarthritis

Purpose: This study aimed to investigate whether magnolin (MGL) possesses the capability of suppressing inflammatory responses that can in turn alleviate osteoarthritis (OA).Methods: We investigated the effects of MGL on the viability of rat chondrocytes at concentrations of 5 to 100 µM, and selected 10 µM for further study. We elucidated the molecular mechanisms and signaling pathways mediating these effects via RNA sequencing, qRT-PCR, immunofluorescent staining, and Western blotting techniques. Following this, we established an anterior cruciate ligament (ACL) transection-induced OA rat model, and injected MGL into the knee articular cavities to verify the in vivo anti-inflammatory effects of MGL.Results: We found that MGL could recover the TNF-α-induced upregulation of IL-1β, COX2, ADAMTS-5, and MMP-1/3/13 at the gene/protein level, as well as the downregulation of cartilaginous ECM synthesis. Gene expression profiles of different groups identified 49 common differentially expressed genes (DEGs), which were mainly enriched in the structural constituents of the ribosome, the extracellular space, and inflammatory response. The NF-κB pathway was highly enriched, and the expression levels of DEGs associated with it (Nfkbia, Ptgs2, Rela, Tnfrsf1a, Tradd, Traf2) under TNF-α stimulation were reversed by MGL. Further studies proved that MGL simultaneously suppressed the cell nucleus translocation of p65 and the phosphorylation of IκBα. Moreover, in vivo, MGL suppressed cartilage matrix degradation, inhibited MMP-13 expression, and promoted cartilage matrix construction by upregulating SOX9 synthesis.Conclusion: MGL demonstrated significant anti-inflammatory bioactivity on chondrocytes by suppressing the activation of NF-κB pathway, which in turn exhibited a significant alleviation of OA.

Emodin Alleviates Severe Acute Pancreatitis-Associated Acute Lung Injury by Inhibiting the Cold-Inducible RNA-Binding Protein (CIRP)-Mediated Activation of the NLRP3/IL-1β/CXCL1 Signaling

Objective: Severe acute pancreatitis (SAP) can lead to acute lung injury (ALI). This study investigated the therapeutic effect of emodin and its molecular mechanisms in a rat model of SAP-ALI.

Methods: Forty male Sprague-Dawley rats were randomly divided into the groups: Control (CON), SAP (SAP), emodin (EMO), and C23 (C23). The latter three groups of rats were induced for SAP-ALI by retrograde injection of 5% sodium taurocholate into the biliary-pancreatic duct and were treated with vehicle, emodin or C23, respectively. One day post induction, their pancreatic and lung injury was assessed by histology and arterial blood gas analysis. In vitro, rat alveolar macrophages (NR8383 cells) were treated with recombinant rat CIRP in the presence or absence of TAK242 (a TLR4 inhibitor), C23 or emodin. The CIRP-mediated activation of the NLRP3/IL-1β/CXCL1 signaling in rat lungs and NR8383 cells was determined. Similarly, the role of IL-1β in the CIRP-induced CXCL1 expression was investigated.

Results: Emodin treatment significantly reduced inflammation and tissue damages in the pancreatic and lung tissues in rats with SAP-ALI, accompanied by decreasing serum amylase, CIRP and IL-1β levels and improving lung function. Furthermore, emodin significantly mitigated the SAP-up-regulated CIRP expression in the pancreatic islets and lung tissues, and attenuated the SAP-activated NF-κB signaling, NLRP3 inflammasome formation and CXCL1 expression in lung resident macrophages as well as neutrophil infiltration in the lungs of rats. In addition, treatment with CIRP significantly activated the NF-κB signaling and NLRP3 inflammasome formation and induced IL-1β and CXCL1 expression and pyroptosis in NR8383 cells, which were abrogated by TAK242 and significantly mitigated by C23 or emodin. Moreover, CIRP only induced very lower levels of CXCL1 expression in IL-1β-silencing NR8383 cells and treatment with IL-1β induced CXCL1 expression in NR8383 cells in a dose and time-dependent manner.

Conclusion: Emodin may inhibit the CIRP-activated NLRP3/IL-1β/CXCL1signaling to decrease neutrophil infiltration and ameliorate the SAP-ALI in rats.

Advanced oxidation protein products induce inflammatory responses and invasive behaviour in fibroblast-like synoviocytes via the RAGE-NF-κB pathway

Aims

Rheumatoid arthritis (RA), which mainly results from fibroblast-like synoviocyte (FLS) dysfunction, is related to oxidative stress. Advanced oxidation protein products (AOPPs), which are proinflammatory mediators and a novel biomarker of oxidative stress, have been observed to accumulate significantly in the serum of RA patients. Here, we present the first investigation of the effects of AOPPs on RA-FLSs and the signalling pathway involved in AOPP-induced inflammatory responses and invasive behaviour.

Methods

We used different concentrations of AOPPs (50 to 200 µg/ml) to treat RA-FLSs. Cell migration and invasion and the expression levels of tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), matrix metalloproteinase-3 (MMP-3), and MMP-13 were investigated. Western blot and immunofluorescence were used to analyze nuclear factor-κB (NF-κB) activation.

Results

AOPPs promoted RA-FLS migration and invasion in vitro and significantly induced the messenger RNA (mRNA) and protein expression of TNF-α, IL-6, MMP-3, and MMP-13 in dose- and time-dependent manners. Moreover, AOPPs markedly activated the phosphorylation of nuclear factor-κB (NF-κB) p65 protein, which triggered inhibitory kappa B-alpha (IκBα) degradation, NF-κB p65 protein phosphorylation, and NF-κB p65 translocation into the nucleus. Furthermore, treatment with a neutralizing antibody specific to receptor for advanced glycation end products (RAGE) significantly suppressed aggressive behaviour and inflammation, decreased TNF-α, IL-6, MMP-3, and MMP-13 expression, and blocked AOPP-induced NF-κB pathway activation.

Conclusion

The results indicate that AOPPs can enhance aggressive behaviour and the inflammatory response in RA-FLSs via the RAGE–NF-κB pathway. These results present AOPPs as a new class of potentially important mediators of progressive disease in RA patients.

Cite this article: Bone Joint Res 2021;10(4):259–268.

Emodin protects knee joint cartilage in rats through anti-matrix degradation pathway: An in vitro and in vivo study

AIMS

Osteoarthritis (OA) is a common joint disease and the main cause of disability. We sought to determine the effective concentration of emodin on chondrocytes and to identify the dosage of emodin that induces a comparable therapeutic effect with the COX-2 inhibitor drug, celecoxib that is currently used to treat OA.

MATERIAL AND METHODS

In vitro experiments induced inflammation of chondrocytes by IL-1β, and an osteoarthritis model was established in vivo by cutting rat anterior cruciate ligament. Western Blot, Real-time PCR, HE staining, Safranin O-green staining and immunohistochemistry were performed to detect MMP-3, MMP-13, ADAMTS-4, iNOS and COL2A1 on the chondrocytes or the tibial plateau. The cytokine activity and content in serum of six groups of rats were measured by kit.

RESULTS

It was found that the surface layer of the cartilage was thicker and smoother after the administration of emodin. Tissue expression of MMP-3, MMP-13, ADAMTS-4 and iNOS were significantly (p < 0.05) decreased in chondrocytes and cartilage treated with different doses of emodin, and the content of COL2A1 was reversed. Emodin also significantly decreased the blood levels of COX-2 and PGE2. The effective emodin in vitro was 5 μmol/L, whereas emodin at 80 mg/kg was equivalent to celecoxib in vivo.

CONCLUSION

Emodin reduces the expression of cartilage matrix degradation biomarkers, thereby reducing the degradation of cartilage matrix and protecting the knee joint cartilage. Emodin at 5 μmol/L shows the best concentration to treat chondrocytes, and the protective effect of emodin at 80 mg/kg is comparable to that of celecoxib.

Obtusifolin, an Anthraquinone Extracted from Senna obtusifolia (L.) H.S.Irwin & Barneby, Reduces Inflammation in a Mouse Osteoarthritis Model

Osteoarthritis (OA) is an age-related degenerative disease that causes cartilage dysfunction and inflammation. Obtusifolin, an anthraquinone extracted from Senna obtusifolia (L.) H.S.Irwin & Barneby seeds, has anti-inflammatory functions; it could be used as a drug component to relieve OA symptoms. In this study, we investigated the effects of obtusifolin on OA inflammation. In vitro, interleukin (IL)-1β (1 ng/mL)-treated mouse chondrocytes were co-treated with obtusifolin at different concentrations. The expression of matrix metalloproteinase (Mmp) 3, Mmp13, cyclooxygenase 2 (Cox2), and signaling proteins was measured by polymerase chain reaction and Western blotting; collagenase activity and the PGE₂ level were also determined. In vivo, OA-induced C57BL/6 mice were administered obtusifolin, and their cartilage was stained with Safranin O to observe damage. Obtusifolin inhibited Mmp3, Mmp13, and Cox2 expression to levels similar to or more than those after treatment with celecoxib. Additionally, obtusifolin decreased collagenase activity and the PGE₂ level. Furthermore, obtusifolin regulated OA via the NF-κB signaling pathway. In surgically induced OA mouse models, the cartilage destruction decreased when obtusifolin was administered orally. Taken together, our results show that obtusifolin effectively reduces cartilage damage via the regulation of MMPs and Cox2 expression. Hence, we suggest that obtusifolin could be a component of another OA symptom reliever.

Astilbin prevents osteoarthritis development through the TLR4/MD-2 pathway

Osteoarthritis has become one of the main diseases affecting the life of many elderly people with high incidence of disability, and local chronic inflammation in the joint cavity is the most crucial pathological feature of osteoarthritis. Astilbin is the main active component in a variety of natural plants such as Hypericum perforatum and Sarcandra glabra, which possess antioxidant and anti‐inflammatory effects. At present, there is no study about the protective effect of Astilbin for osteoarthritis. The purpose of this study was to investigate the effect of Astilbin in human OA chondrocytes and mouse OA model, which was established by surgery‐mediated destabilization of the medial meniscus (DMM). In vitro, we found that Astilbin pre‐treatment inhibited lipopolysaccharide (LPS)‐induced overproduction of inflammation‐correlated cytokines such as nitric oxide (NO), prostaglandin E2 (PGE2), tumour necrosis factor α (TNF‐α) and interleukin 6 (IL‐6), and suppressed overexpression of inflammatory enzymes such as inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX‐2). Astilbin, on the other hand, prevented the LPS‐induced degradation of extracellular matrix (ECM) by down‐regulating MMP13 (matrix metalloproteinases 13) and ADAMTS5 (a disintegrin and metalloproteinase with thrombospondin motifs 5). Moreover, by inhibiting the formation of the TLR4/MD‐2/LPS complex, Astilbin blocked LPS‐induced activation of TLR4/NF‐κB signalling cascade. In vivo, Astilbin showed the chondro‐protective effect in the surgical‐induced OA mouse models. In conclusion, our findings provided evidence that develops Astilbin as a potential therapeutic drug for OA patients.

An Update on the Emerging Role of Visfatin in the Pathogenesis of Osteoarthritis and Pharmacological Intervention

Osteoarthritis (OA) is one of the most common degenerative joint diseases that affects millions of people worldwide, mainly the aging population. Despite numerous published reports, little is known about the pathology of this disease, and no feasible treatment plan exists to stop OA progression. Recently, extensive basic and clinical studies have shown that adipokines play a key role in OA development. Moreover, some drugs associated with adipokines have shown chondroprotective and anti-inflammatory effects on OA. Visfatin has been shown to play a detrimental role in the progression of OA. It increases the production of matrix metalloproteinases and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), induces the production of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, affects the differentiation of mesenchymal stem cells to adipocytes, and induces osteophyte formation by inhibiting osteoclastogenesis. Although some side effects of chemical visfatin inhibitors have been reported, they were shown to be successful in the treatment of diabetes, cancer, and other diseases that can utilize Chinese herbs, further suggesting that similar therapeutic strategies could be used in OA prevention and treatment. Here, we describe the pathophysiological mechanism of visfatin in OA and discuss some potential pharmacological interventions using Chinese herbs.

Recent advance in treatment of osteoarthritis by bioactive components from herbal medicine

Osteoarthritis (OA) is a common chronic articular degenerative disease, and characterized by articular cartilage degradation, synovial inflammation/immunity, and subchondral bone lesion, etc. The disease affects 2-6% of the population around the world, and its prevalence rises with age and exceeds 40% in people over 70. Recently, increasing interest has been devoted to the treatment or prevention of OA by herbal medicines. In this paper, the herbal compounds with anti-OA activities were reviewed, and the cheminformatics tools were used to predict their drug-likeness properties and pharmacokinetic parameters. A total of 43 herbal compounds were analyzed, which mainly target the damaged joints (e.g. cartilage, subchondral bone, and synovium, etc.) and circulatory system to improve the pathogenesis of OA. Through cheminformatics analysis, over half of these compounds have good drug-likeness properties, and the pharmacokinetic behavior of these components still needs to be further optimized, which is conducive to the enhancement in their drug-likeness properties. Most of the compounds can be an alternative and valuable source for anti-OA drug discovery, which may be worthy of further investigation and development.

Nutraceutical Activity in Osteoarthritis Biology: A Focus on the Nutrigenomic Role

Osteoarthritis (OA) is a disease associated to age or conditions that precipitate aging of articular cartilage, a post-mitotic tissue that remains functional until the failure of major homeostatic mechanisms. OA severely impacts the national health system costs and patients' quality of life because of pain and disability. It is a whole-joint disease sustained by inflammatory and oxidative signaling pathways and marked epigenetic changes responsible for catabolism of the cartilage extracellular matrix. OA usually progresses until its severity requires joint arthroplasty. To delay this progression and to improve symptoms, a wide range of naturally derived compounds have been proposed and are summarized in this review. Preclinical in vitro and in vivo studies have provided proof of principle that many of these nutraceuticals are able to exert pleiotropic and synergistic effects and effectively counteract OA pathogenesis by exerting both anti-inflammatory and antioxidant activities and by tuning major OA-related signaling pathways. The latter are the basis for the nutrigenomic role played by some of these compounds, given the marked changes in the transcriptome, miRNome, and methylome. Ongoing and future clinical trials will hopefully confirm the disease-modifying ability of these bioactive molecules in OA patients.

An Evidence-based Review of Medicinal Plants used in Traditional Persian Medicine for Treatment of Osteoarthritis

Osteoarthritis (OA) is known to be the leading cause of pain and disability in the elderly. The prevalence of this disease in adults over 60 years was 9.6% in men and 18% in women. The therapeutic goals of this disease generally include pain relief with the least side effects, improvement of articular function and improvement of life, in which pharmacological and nonpharmacological treatments are performed in different protocols. Due to the common side effects of pain relievers and complaints after invasive joint surgeries, there is a growing interest in the use of Traditional and Complementary protocols in OA treatment. In this paper, different sources of Traditional Persian Medicine (TPM) were searched to obtain any evidence evaluating any medicinal plants in the management of OA. Over 250 effective medicinal plants for the treatment of OA have been introduced in these sources, and by searching electronic databases including PubMed and Scopus, we have found that of these plants, 39 have direct or indirect evidence in the treatment of this complication by different mechanism of actions such as effect on Body mass index (BMI), obesity and dyslipidemia, anti-inflammatory, anti-nociceptive and antioxidant activity. The most important medicinal plants with direct evidence in the management of OA are Allium sativum, Commiphora mukul, Linum usitatissimum, Matricaria chamomilla, Nigella sativa, Zingiber officinale, and Piper nigrum. Medicinal plants seem to be a valuable source for discovering and identifying new drugs for treatment of OA; however, since most of the studies are preclinical, further clinical trials are required to achieve more conclusive results.

The CRD of Frizzled 7 exhibits chondroprotective effects in osteoarthritis via inhibition of the canonical Wnt3a/β-catenin signaling pathway

Osteoarthritis (OA) is a chronic inflammatory joint disease without effective drugs. Frizzled 7 (FzD7) binds its ligand Wnt3a through an extracellular cysteine-rich domain (CRD) to transduce the canonical Wnt/β-catenin signaling pathway, which has been strongly implicated in OA pathogenesis. Effects of recombinant protein of FzD7 CRD on Wnt/β-catenin signaling and chondral destruction was evaluated in this study. Firstly, increased protein levels of FzD7, Wnt3a and β-catenin were detected in human OA cartilage implying that the canonical Wnt/β-catenin signaling mediated by Wnt3a and FzD7 executes an essential role in OA. Then we showed that FzD7 CRD antagonized the Wnt3a/β-catenin signaling pathway in a dose-dependent manner by binding Wnt3a. In addition, FzD7 CRD increased the expression of glycosaminoglycans (GAGs), Collagen II, aggrecan and reduced the expression of matrix metalloproteinase (MMP)-1, MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5) in Wnt3a-stimulated human chondrocytes. Furthermore, a single intra-articular injection of the FzD7 CRD was efficacious in destabilization of the medial meniscus (DMM) mouse OA model, significantly improving Osteoarthritis Research Society International (OARSI) histology scores compared to mice treated with PBS. The results indicate that the FzD7 CRD exhibits chondroprotective effects by binding Wnt3a to suppress the Wnt3a/β-catenin signaling. Targeting the FzD7 CRD may be a novel therapy for the treatment of OA.

Synthesis and anti-inflammatory effects of novel emodin derivatives bearing azole moieties

Twelve azole derivatives of emodin were designed to possess anti-inflammatory activity and synthesized via a two-step sequence composed of the Williamson ether reaction and N-alkylation. The anti-inflammatory properties of these compounds were evaluated in RAW264.7 cells by measuring lipopolysaccharide (LPS)-induced nitric oxide (NO) production. The introduction of imidazole and four carbons into the scaffold of emodin led to the discovery of the potent compound 7e, which showed the best inhibition of NO production among twelve analogs. In our experiential setting, the IC₅₀ of compound 7e in NO production is 1.35 µM, which is lower than that of indomethacin. Mechanically, compound 7e effectively inhibited the protein and messenger RNA expressions of cyclooxygenase-2 and inducible NO synthase, as well as that of the proinflammatory cytokine interleukin-6, and the cytokines interleukin-1β and tumor necrosis factor-α in the LPS-stimulated RAW 264.7 macrophages. Compound 7e exerted inhibitory effects on the nuclear factor κB pathway by reducing the LPS-induced phosphorylation of the inhibitor of NF-κB and the nuclear translation of p-p65. These results suggest the potential of compound 7e in improving inflammatory conditions and diseases.

Xanthan Gum Ameliorates Osteoarthritis and Mitigates Cartilage Degradation via Regulation of the Wnt3a/β-Catenin Signaling Pathway

Background

Osteoarthritis (OA) is a joint disease characterized by articular cartilage degeneration and inflammation. We have previously clarified that a xanthan gum (XG) preparation exerts ameliorating effect on a rabbit OA model by regulating matrix metalloproteinase (MMP)-1 and MMP-3, which are critical proteins in the Wnt3a/β-catenin pathway. Thus, it is reasonable to predict that the Wnt3a/β-catenin pathway is involved in the treatment of OA with XG.

Material/Methods

The effect of XG in OA model animals were observed by hematoxylin and eosin staining (HE), Safranin O staining, and Fast Green staining. Articular cartilage degradation on the medial plateau sides was quantified using the modified Pritzker OARSI score. The levels of IL-6, TNF-α, and IL-1β in synovial fluid were determined with ELISA. The protective effect of XG in rat chondrocytes was assessed by CCK8 assay. Moreover, activation of the Wnt3a/β-catenin pathway and the expression of MMP13, ADAMTS5, aggrecan, and collagen II under the influence of XG was measured by Western blot and qRT-PCR.

Results

Our results showed that XG reduced the OARSI score and the concentration of inflammatory cytokines in OA after intra-articular injection. XG acted on Wnt3a/β-catenin in ATDC5 cells in a dose-dependent manner and exhibited a protective effect. XG also decreased the expression of MMP13 and ADAMTS5 and rescued the inhibition of aggrecan and collagen II expression in SNP-stimulated chondrocytes.

Conclusions

These results indicate that the effects of XG are related to the Wnt3a/β-catenin pathway and XG suppresses matrix degradation by inhibiting the expression of MMPs and ADAMTS and promotes aggrecan and collagen II content in the ECM, indicating its favorable potential for use in OA therapy.

Dopamine delays articular cartilage degradation in osteoarthritis by negative regulation of the NF-κB and JAK2/STAT3 signaling pathways

BACKGROUND

The progressive loss of cartilage matrix and the breakdown of articular cartilage induced by inflammation play an essential role in osteoarthritis (OA) pathogenesis. Dopamine (DA) is a critical neurotransmitter that is not only involved in controlling exercise, emotion, cognition and neuroendocrine activity but also has anti-inflammatory effects. This study aimed to investigate the effects of DA on OA in vitro and in vivo.

METHODS

OA progression was evaluated in a mouse model with surgically induced destabilization of the medial meniscus. Cartilage degradation and OA were analyzed using Safranin O/Fast Green staining. Additionally, qRT-PCR and Western blotting were applied to detect catabolic and anabolic factors involved in cartilage degeneration and underlying mechanisms in OA chondrocytes treated with Interleukin-1β.

RESULTS

In vitro, DA treatment inhibited the production of inducible nitric oxide synthase, cyclooxygenase-2, matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13, while increasing type II collagen and glycosaminoglycan content. Mechanistically, DA reversed IL-1β-treated nuclear factor-kappa B activation and JAK2/STAT3 phosphorylation. Furthermore, DA suppressed the degradation of cartilage matrix and reduced Osteoarthritis Research Society International scores in the surgically induced OA models.

CONCLUSION

DA may be a novel therapeutic agent for OA treatment.

Wnt signaling: a promising target for osteoarthritis therapy

Osteoarthritis (OA) is the most common joint disease worldwide and a leading cause of disability. Characterized by degradation of articular cartilage, synovial inflammation, and changes in periarticular and subchondral bone, OA can negatively impact an individual's physical and mental well-being. Recent studies have reported several critical signaling pathways as key regulators and activators of cellular and molecular processes during OA development. Wnt signaling is one such pathway whose signaling molecules and regulators were shown to be abnormally activated or suppressed. As such, agonists and antagonists of those molecules are potential candidates for OA treatment. Notably, a recent phase I clinical trial (NCT02095548) demonstrated the potential of SM04690, a small-molecule inhibitor of the Wnt signaling pathway, as a disease-modifying oseoarthritis drug (DMOAD). This review summarizes the role and mechanism of Wnt signaling and related molecules in regulating OA progression, with a view to accelerating the translation of such evidence into the development of strategies for OA treatment, particularly with respect to potential applications of molecules targeting the Wnt signaling pathway.

Propolis Reduces the Expression of Autophagy-Related Proteins in Chondrocytes under Interleukin-1β Stimulus

Background: Osteoarthritis (OA) is a progressive and multifactorial disease that is associated with aging. A number of changes occur in aged cartilage, such as increased oxidative stress, decreased markers of healthy cartilage, and alterations in the autophagy pathway. Propolis extracts contain a mixture of polyphenols and it has been proved that they have high antioxidant capacity and could regulate the autophagic pathway. Our objective was to evaluate the effect of ethanolic extract of propolis (EEP) on chondrocytes that were stimulated with IL-1β. Methods: Rabbit chondrocytes were isolated and stimulated with IL-1β and treated with EEP. We evaluated cell viability, nitric oxide production, healthy cartilage, and OA markers, and the expression of three proteins associated with the autophagy pathway LC3, ATG5, and AKT1. Results: The EEP treatment reduces the expression of LC3, ATG5, and AKT1, reduces the production of nitric oxide, increases the expression of healthy markers, and reduces OA markers. Conclusions: These results suggest that treatment with EEP in chondrocytes that were stimulated with IL-1β has beneficial effects, such as a decrease in the expression of proteins associated with autophagy, MMP13, and production of nitric oxide, and also increased collagen II.

Knockdown of FOXM1 attenuates inflammatory response in human osteoarthritis chondrocytes

Osteoarthritis (OA) is the most common inflammatory joint disease that is mainly characterized by articular cartilage destruction. Forkhead box M1 (FOXM1) is a transcription factor that acts as a critical mediator of inflammatory response. However, the role of FOXM1 in OA has not been investigated. Interleukin (IL)-1β is a major proinflammatory cytokine, which is associated with cartilage destruction in the pathophysiology of OA. In the present study, we used IL-1β to stimulate chondrocytes for the establishment of OA in vitro model. We found that FOXM1 was up-regulated in IL-1β-induced chondrocytes. Knockdown of FOXM1 attenuated IL-1β-caused decrease in cell viability. Knockdown of FOXM1 suppressed the IL-1β-induced production of inflammatory cytokines including tumor necrosis factor (TNF)-α, and IL-6. Besides, several inflammatory mediators, such as nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthases (iNOS), and cyclooxygenase-2 (COX-2) were also repressed by knockdown of FOXM1. FOXM1 silencing also inhibited the production of matrix metalloproteinases (MMPs) including MMP-3 and MMP-13. Furthermore, we found that knockdown of FOXM1 blocked the IL-1β-induced NF-κB activation in chondrocytes. These findings indicated that FOXM1 might play an important role in the pathogenesis of OA, suggesting that FOXM1 might be a potential therapeutic target for the treatment of OA.