Activation of the P38/CREB/MMP13 axis is associated with osteoarthritis

Blocking IL-33 decelerates cartilage degeneration in knee osteoarthritis through mice model

INTRODUCTION

Osteoarthritis (OA) is a chronic inflammatory disease where pro-inflammatory cytokines, damage-associated molecular patterns and macrophages play a crucial role. However, the interaction of these mediators, the exact cause, and the treatment of knee osteoarthritis (KOA) are still unclear. Moreover, the interaction of interleukin (IL)-33, platelet-derived growth factor-BB (PDGF-BB), and matrix metalloproteinase-9 (MMP-9) with other factors in the pathogenesis of KOA has not been elaborately explored.

METHOD

Therefore, in this study, we analyzed the expression of IL-33, PDGF-BB, and MMP-9 in the knee cartilage tissue of model mice, murine KOA was induced by using the destabilization of the medial meniscus (DMM) model.

RESULTS

Compared with the sham operation control group, the expression levels of PDGF-BB, IL-33, and MMP-9 were increased significantly, and the pathological sections showed obvious cartilage damage. Additionally, we assessed the levels of IL-33 and MMP-9 expression in the knee joint of KOA model mice following intervention with PDGF-BB antibody, and we found that the expression level of MMP-9 was reduced following intervention with IL-33 antibody. When the effects of the three antibodies were compared in a mouse disease model, it was discovered that the IL-33 antibody could dramatically lower the relative expression level of MMP-9, resulting in the least amount of cartilage damage and improved protection. In conclusion, inhibiting IL-33 can significantly lower inflammatory factor levels in the knee joint, including IL-33 and MMP-9, and it can improve cartilage breakdown in osteoarthritis of the knee.

CONCLUSION

Overall, the results indicate that IL-33 has a therapeutic function in the treatment of knee osteoarthritis and may be a novel target for treatment of the underlying causes of KOA. Additionally, PDGF-BB might be an upstream pathway of IL-33, and KOA's MMP-9 is an downstream pathway of IL-33.

Clinical Outcome of Multiple Platelet-Rich Plasma Injection and Correlation with PDGF-BB in the Treatment of Knee Osteoarthritis

(1) Background: Current treatments for knee osteoarthritis (KOA), such as intra-articular corticosteroids or hyaluronic acid (HA) injections, are controversial due to their ineffectiveness in preventing disease progression. Platelet-rich plasma (PRP) has become a promising and possible treatment for KOA. It is thought to enhance articular cartilage regeneration and reduce OA-related impairment. PRP contains growth factors such as PDGF-BB, which stimulates growth and inhibits joint damage. Based on numerous studies, after a certain amount of time, it was found that multiple PRP treatments reduced pain more than a single injection. This study evaluates the efficacy of multiple PRP (m-PRP) injections compared to multiple HA (m-HA) injections for KOA treatment, focusing on their correlation with PDGF-BB levels. (2) Methods: In this single-center, open-label, randomized, comparative clinical trial, 30 KOA patients received m-PRP and m-HA injections. VAS and WOMAC were used to evaluate clinical outcomes and PDGF-BB concentrations. (3) Results: The study analysis revealed a statistically significant reduction in pain indices. In both the m-PRP and m-HA groups after 12 weeks, m-PRP showed superior results. PDGF-BB concentrations also increased, with a strong negative correlation and statistical significance using Spearman's rho. (4) Conclusions: Multiple PRP injections are safe and associated with elevated PDGF-BB, reduced VAS and WOMAC scores, providing the potential for articular cartilage regeneration and inhibiting knee osteoarthritis progression.

Glycolysis: an emerging regulator of osteoarthritis

Osteoarthritis (OA) has been a leading cause of disability in the elderly and there remains a lack of effective therapeutic approaches as the mechanisms of pathogenesis and progression have yet to be elucidated. As OA progresses, cellular metabolic profiles and energy production are altered, and emerging metabolic reprogramming highlights the importance of specific metabolic pathways in disease progression. As a crucial part of glucose metabolism, glycolysis bridges metabolic and inflammatory dysfunctions. Moreover, the glycolytic pathway is involved in different areas of metabolism and inflammation, and is associated with a variety of transcription factors. To date, it has not been fully elucidated whether the changes in the glycolytic pathway and its associated key enzymes are associated with the onset or progression of OA. This review summarizes the important role of glycolysis in mediating cellular metabolic reprogramming in OA and its role in inducing tissue inflammation and injury, with the aim of providing further insights into its pathological functions and proposing new targets for the treatment of OA.

The CREB1 inhibitor 666-15 maintains cartilage homeostasis and mitigates osteoarthritis progression

Aims

cAMP response element binding protein (CREB1) is involved in the progression of osteoarthritis (OA). However, available findings about the role of CREB1 in OA are inconsistent. 666-15 is a potent and selective CREB1 inhibitor, but its role in OA is unclear. This study aimed to investigate the precise role of CREB1 in OA, and whether 666-15 exerts an anti-OA effect.

Methods

CREB1 activity and expression of a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4) in cells and tissues were measured by immunoblotting and immunohistochemical (IHC) staining. The effect of 666-15 on chondrocyte viability and apoptosis was examined by cell counting kit-8 (CCK-8) assay, JC-10, and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) staining. The effect of 666-15 on the microstructure of subchondral bone, and the synthesis and catabolism of cartilage, in anterior cruciate ligament transection mice were detected by micro-CT, safranin O and fast green (S/F), immunohistochemical staining, and enzyme-linked immunosorbent assay (ELISA).

Results

CREB1 was hyperactive in osteoarthritic articular cartilage, interleukin (IL)-1β-treated cartilage explants, and IL-1β- or carbonyl cyanide 3-chlorophenylhydrazone (CCCP)-treated chondrocytes. 666-15 enhanced cell viability of OA-like chondrocytes and alleviated IL-1β- or CCCP-induced chondrocyte injury through inhibition of mitochondrial dysfunction-associated apoptosis. Moreover, inhibition of CREB1 by 666-15 suppressed expression of ADAMTS4. Additionally, 666-15 alleviated joint degeneration in an ACLT mouse model.

Conclusion

Hyperactive CREB1 played a critical role in OA development, and 666-15 exerted anti-IL-1β or anti-CCCP effects in vitro as well as joint-protective effects in vivo. 666-15 may therefore be used as a promising anti-OA drug.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Multiple roles of ALK3 in osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease characterized by progressive cartilage degradation, synovial membrane inflammation, osteophyte formation, and subchondral bone sclerosis. Pathological changes in cartilage and subchondral bone are the main processes in OA. In recent decades, many studies have demonstrated that activin-like kinase 3 (ALK3), a bone morphogenetic protein receptor, is essential for cartilage formation, osteogenesis, and postnatal skeletal development. Although the role of bone morphogenetic protein (BMP) signalling in articular cartilage and bone has been extensively studied, many new discoveries have been made in recent years around ALK3 targets in articular cartilage, subchondral bone, and the interaction between the two, broadening the original knowledge of the relationship between ALK3 and OA. In this review, we focus on the roles of ALK3 in OA, including cartilage and subchondral bone and related cells. It may be helpful to seek more efficient drugs or treatments for OA based on ALK3 signalling in future.

LncRNA SNHG5 Suppresses Cell Migration and Invasion of Human Lung Adenocarcinoma via Regulation of Epithelial-Mesenchymal Transition

Long noncoding RNAs (lncRNAs) are gradually being annotated as important regulators of multiple cellular processes. The goal of our study was to investigate the effects of the lncRNA small nucleolar RNA host gene 5 (SNHG5) in lung adenocarcinoma (LAD) and its underlying mechanisms. The findings revealed a substantial drop in SNHG5 expression in LAD tissues, which correlated with clinical-pathological parameters. Transcriptome sequencing analysis demonstrated that the inhibitory effect of SNHG5 was associated with cell adhesion molecules. Moreover, the expression of SNHG5 was shown to be correlated with epithelial-mesenchymal transition (EMT) markers in western blots and immunofluorescence. SNHG5 also had significant effects of antimigration and anti-invasion on LAD cells in vitro. Furthermore, the migration and invasion of A549 cells were suppressed by overexpressed SNHG5 in the EMT progress induced by transforming growth factor β1 (TGF-β1), and this might be due to the inhibition of the expression of EMT-associated transcription factors involving Snail, SLUG, and ZEB1. In LAD tissues, the expression of SNHG5 exhibited a positive association with E-cadherin protein expression but a negative correlation with N-cadherin and vimentin, according to the results of quantitative real-time PCR (qRT-PCR). In summary, the current work demonstrated that the lncRNA SNHG5 might limit cell migration and invasion of LAD cancer via decreasing the EMT process, indicating that SNHG5 might be used as a target for LAD therapeutic methods.

LTBP1 Gene Expression in the Cerebral Cortex and its Neuroprotective Mechanism in Mice with Postischemic Stroke Epilepsy

OBJECTIVE

This study aimed at exploring the expression level of LTBP1 in the mouse model of epilepsy. The mechanism of LTBP1 in epileptic cerebral neural stem cells was deeply investigated to control the occurrence of epilepsy with neuroprotection.

METHODS

qRT-PCR was conducted for the expression levels of LTBP1 in clinical human epileptic tissues and neural stem cells, as well as normal cerebral tissues and neural stem cells. The mouse model of postischemic stroke epilepsy (PSE) was established by the middle cerebral artery occlusion (MCAO). Then, qRT-PCR was conducted again for the expression levels of LTBP1 in mouse epileptic tissues and neural stem cells as well as normal cerebral tissues and neural stem cells. The activation and inhibitory vectors of LTBP1 were constructed to detect the effects of LTBP1 on the proliferation of cerebral neural stem cells in the PSE model combined with CCK-8. Finally, Western blot was conducted for the specific mechanism of LTBP1 affecting the development of epileptic cells.

RESULTS

Racine score and epilepsy index of 15 mice showed epilepsy symptoms after the determination with MCAO, showing a successful establishment of the PSE model. LTBP1 expression in both diseased epileptic tissues and cells was higher than that in normal clinical epileptic tissues and cells. Meanwhile, qRT-PCR showed higher LTBP1 expression in both mouse epileptic tissues and their neural stem cells compared to that in normal tissues and cells. CCK-8 showed that the activation of LTBP1 stimulated the increased proliferative capacity of epileptic cells, while the inhibition of LTBP1 expression controlled the proliferation of epileptic cells. Western blot showed an elevated expression of TGFβ/SMAD signaling pathway-associated protein SMAD1/5/8 after activating LTBP1. The expression of molecular MMP-13 associated with the occurrence of inflammation was also activated.

CONCLUSION

LTBP1 can affect the changes in inflammation-related pathways by activating the TGFβ/SMAD signaling pathway and stimulate the development of epilepsy, and the inhibition of LTBP1 expression can control the occurrence of epilepsy with neuroprotection.

HU308 Mitigates Osteoarthritis by Stimulating Sox9-Related Networks of Carbohydrate Metabolism

Osteoarthritis (OA) is characterized by progressive, irreversible erosion of articular cartilage accompanied by severe pain and immobility. This study aimed to assess the effect and mechanism of action of HU308, a selective cannabinoid receptor type 2 (CB2) agonist, in preventing OA-related joint damage. To test the assumption that HU308 could prevent OA-related joint damage, Cnr2 null mice and wild type (WT) mice were aged to reach 20 months and analyzed for joint structural features. OA was induced in WT mice via a post-traumatic procedure or aging, followed by HU308 local (intra-articular) or systemic (intraperitoneal) administration, respectively. Additional analyses of time and dose courses for HU308 were carried out in human primary chondrocytes, analyzed by RNA sequencing, RT-PCR, chromatin immunoprecipitation, and immunoblotting. Our results showed that Cnr2 null mice exhibited enhanced age-related OA severity and synovitis compared to age-matched WT mice. Systemic administration of HU308 to 16-month-old mice improved pain sensitivity and maintained joint integrity, which was consistent with the intra-articular administration of HU308 in post-traumatic OA mice. When assessing human chondrocytes treated with HU308, we uncovered a dose- and time-related increase in ACAN and COL2A1 expression, which was preceded by increased SOX9 expression due to pCREB transcriptional activity. Finally, transcriptomic analysis of patient-derived human chondrocytes identified patient subpopulations exhibiting HU308-responsive trends as judged by enhanced SOX9 expression, accompanied by enriched gene networks related to carbohydrate metabolism. Collectively, the results showed that HU308 reduced trauma and age-induced OA via CB2-pCREB dependent activation of SOX9, contributing to augmented gene networks related to carbohydrate metabolism. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

One session of 20 ​N cyclic compression induces chronic knee osteoarthritis in rats: A long-term study

Objective

Mechanical stimulation is a risk factor for knee osteoarthritis. Non-surgical compression has been used to study the effects of mechanical stimulation in vivo. However, the long-term effects of low-force compression on knee joint had not been studied. Therefore, we sought to identify the long-term effects of low-force cyclic compression on the rat knee joint.

Design

In this study, we applied one session cyclic compression with a peak load of 20 ​N for 60 cycles to the rat knee joint in an approximately 140-degree flexion position (Wistar, male, 12 weeks old), followed by 1 year of observation (including data from 1 week, 2 weeks, 4 weeks, 8 weeks, 6 months, and 1 year after compression), and then performed a sub-regional analysis with hematoxylin-eosin, Safranin O and Fast Green, and MMP13 immunohistochemical staining.

Results

We observed osteoarthritis-like cartilage damage, synovial inflammation, and high expression of MMP13 within 1 year after compression. However, these changes progressed slowly, with obvious matrix cracks that did not appear until 1 year after compression. In the regional analysis, we found that low-force compression caused a much slower development of injury at the compression contact site, and no significant structural cartilage damage was observed after 1 year of compression. In contrast, the non-contact site during compression at tibial cartilage in the same joint was the first to show significant structural damage.

Conclusion

This study demonstrates that one session of 20 ​N cyclic compression induces a chronic osteoarthritis-like phenotype in the rat knee in the long term.

MiR-19b-3p Attenuates Chondrocytes Injury by Inhibiting MAPK/NF-Κb Axis via Targeting SOCS1

In this study, miR-19b-3p was downregulated in osteoarthritic cartilage tissues and IL-1β-stimulated primary chondrocytes, and miR-19b-3p overexpression reversed the inhibitory effect of IL-1β on cell viability, the promotion effects of apoptosis, inflammatory factor secretion and extracellular matrix degradation, whereas the opposite effect was observed with miR-19b-3p inhibitor. Moreover, SOCS1 is a target gene of miR-19b-3p. Furthermore, SOCS1 overexpression enhanced cell injury compared with IL-1β alone treatment, whereas knockdown of SOCS1 restored cell damage caused by IL-1β. Further studies revealed that miR-19b-3p promoted chondrocyte injury repair by suppressing SOCS1 expression, and we found that was mediated by blocking the MAPK/NF-κB axis. Taken together, our findings may provide a new therapeutic strategy for osteoarthritis.

CREB Ameliorates Osteoarthritis Progression Through Regulating Chondrocytes Autophagy via the miR-373/METTL3/TFEB Axis

Osteoarthritis (OA) is a degenerative joint disease characterized by articular cartilage degradation. Dysregulated autophagy is a major cause of OA. However, the underlying mechanism is unclear. Here, we found that the expression of element-binding protein (CREB) was downregulated in both cartilage tissues of OA patients and mouse OA model. In tert-butyl hydroperoxide solution-treated chondrocytes, increased apoptosis and autophagic blockage were attenuated by CREB overexpression. Mechanically, MiR-373 directly targeted the 3′UTR of methyltransferase-like 3 (METTL3) and led to its downregulation. METTL3 epigenetically suppressed TFEB. The upregulation of miR-373 by CREB overexpression induced the release of TFEB from METTL3 and restored the autophagy activity of chondrocytes. Taken together, our study showed that CREB alleviates OA injury through regulating the expression of miR-373, which directly targeted METTL3, and finally relieved TFEB from METTL3-mediated epigenetic suppression. The CREB/miR-373/METTL3/TFEB axis may be used as a potential target for the treatment of OA.

Platelet-rich plasma inhibits inflammation, apoptosis, and the NLRP3/Caspase-1 pathway and induces matrix metalloproteinases and proliferation of IL-1β-induced articular chondrocytes by downregulating T-box transcription factor 3

Objectives

Osteoarthritis (OA) is a chronic joint disease characterized by osteoproliferation and the degeneration and destruction of articular cartilage. Platelet-rich plasma (PRP) is rich in various growth factors that have been reported to promote bone defect repair. This study examined the specific role and mechanism of PRP in OA.

Methods

OA model cells were created by treating articular chondrocytes with IL-1β. After treatment of the model cells with PRP or/and a T-box transcription factor 3 (TBX3)-overexpression plasmid, TBX3 expression was monitored via RT-qPCR, western blotting, and immunofluorescence assays. IL-1β, IL-33, and Caspase-3 levels were detected with ELISA kits. Levels of NLRP3, Caspase-1, MMP9, MMP13, and COL2A1 expression were evaluated by western blotting, and cell proliferation was assessed by the CCK-8 assay.

Results

Our results showed that TBX3 expression was upregulated in IL-1β-induced articular chondrocytes. IL-1β stimulation induced inflammation and the production of matrix metalloproteinases, activated Caspase-3 and the NLRP3/Caspase-1 pathway, inhibited the proliferation of articular chondrocytes; however, all those affects mediated by IL-1β could be markedly reversed by PRP. We also found that PRP alleviated IL-1β-induced inflammation, apoptosis, and extracellular matrix degradation in articular chondrocytes by inhibiting TBX3. Our findings suggest that PRP alleviates OA progression in vitro by downregulating TBX3.

Conclusion

PRP suppressed OA progression in vitro by inhibiting TBX3, which may be its mechanism of action in treating OA.

Chaenomeles Fructus (CF), the Fruit of Chaenomeles sinensis Alleviates IL-1β Induced Cartilage Degradation in Rat Articular Chondrocytes

Osteoarthritis (OA) causes persistent pain, joint dysfunction, and physical disability. It is the most prevalent type of degenerative arthritis, affecting millions of people worldwide. OA is currently treated with a focus on pain relief, inflammation control, and artificial joint surgery. Hence, a therapeutic agent capable of preventing or delaying the progression of OA is needed. OA is strongly associated with the degeneration of the articular cartilage and changes in the ECM, which are primarily associated with a decrease in proteoglycan and collagen. In the progress of articular cartilage degradation, catabolic enzymes, such as matrix metalloproteinases (MMPs), are activated by IL-1β stimulation. Given the tight relationship between IL-1β and ECM (extra-cellular matrix) degradation, this study examined the effects of Chaenomeles Fructus (CF) on IL-1β-induced OA in rat chondrocytes. The CF treatment reduced IL-1β-induced MMP3/13 and ADAMTS-5 production at the mRNA and protein levels. Similarly, CF enhanced col2a and aggrecan accumulation and chondrocyte proliferation. CF inhibited NF-κB (nuclear factor kappa B) activation, nuclear translocation induced by IL-1β, reactive oxygen species (ROS) production, and ERK phosphorylation. CF demonstrated anti-OA and articular regeneration effects on rat chondrocytes, thus, suggesting that CF is a viable and fundamental therapeutic option for OA.

Exploring the role of monocyte chemoattractant protein-1 in fibroblast-like synovial cells in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease with persistent synovitis. In the present study, the impact of monocyte chemoattractant protein-1 (MCP-1) was explored to determine methods for the diagnosis and treatment of RA.

Methods

First, fibroblast-like synoviocytes (FLSs) were obtained from a collagen-induced rat RA model. Next, MCP-1-overexpression plasmid and small interfering RNA were transfected into human and rat FLSs. Cell Counting Kit-8 (CCK-8), Transwell migration and flow cytometry assays were used to analyze cell proliferation, migration and apoptosis of FLSs following MCP-1 transfections, respectively. Furthermore, western blotting was used to analyze the expression levels of p-P38, p-PI3K, PI3K, CD31, VEGF, TNF-α and IL-β in FLSs following MCP-1 transfection. In addition, reverse transcription-quantitative PCR and ELISAs were used to analyze the expression levels of C-reactive protein (CRP), estrogen receptor, MCP-1 and pentraxin-3 in patients with clinical RA, followed by correlation analysis of clinical data. Finally, expression validation, diagnostic and protein-protein interaction (PPI) network analysis of MCP-1 were performed.

Results

MCP-1 promoted FLS proliferation and migration, and affected the apoptosis of FLSs. In addition, the expression levels of p-P38, p-PI3K, PI3K, CD31, VEGF, TNF-α and IL-β were also affected by MCP-1. In patients with clinical RA, the expression level of MCP-1 was increased. Moreover, CRP expression level was significantly up-regulated in RA. Clinically, MCP-1 was strongly correlated with tender joint count, swollen joint count, visual analog scale for general health and disease activity score 28 (DAS28)-MCP-1, and was moderately correlated with DAS28 and DAS28-CRP. PPI analysis showed that MCP-1 mainly interacted with other inflammatory cytokines.

Conclusion

In conclusion, MCP-1 may play a significant regulatory role in RA, and could be used as a measurement index of clinical RA activity.

Recombinant platelet-derived growth factor-BB alleviates osteoarthritis in a rat model by decreasing chondrocyte apoptosis in vitro and in vivo

Osteoarthritis (OA) is a common joint disease that mainly affects the diarthrodial joints. Treatments for OA include non‐pharmacological interventions, topical and oral therapies, intra‐articular therapies and joint surgery. However, all the treatments mentioned above mainly aim to control the symptoms instead of improving or reversing the joint condition. In this research, we observed the effect of recombinant platelet‐derived growth factor (PDGF)‐BB on OA in a monosodium iodoacetate (MIA)–induced rat model and revealed the possible mechanisms. In vitro, the level of inflammation in the chondrocytes was gradually alleviated, and the apoptosis rate was gradually decreased by PDGF‐BB at increasing concentrations. The levels of p‐p38, Bax and caspase‐3 decreased, and the level of p‐Erk increased with increasing PDGF‐BB concentration. In vivo, PDGF‐BB could significantly reverse chondrocyte and matrix loss. Furthermore, high concentrations of PDGF‐BB could alleviate cartilage hyperplasia to remodel the tissue. The level of collagen II was up‐regulated, and the levels of collagen X and apoptosis were down‐regulated by increasing concentrations of PDGF‐BB. In conclusion, recombinant PDGF‐BB alleviated OA by down‐regulating caspase‐3‐dependent apoptosis. The effects of PDGF‐BB on OA mainly include inhibiting chondrocyte loss, reducing cartilage hyperplasia and osteophyte formation, and regulating collagen anabolism.

Modified Simiaowan prevents articular cartilage injury in experimental gouty arthritis by negative regulation of STAT3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Modified Simiaowan (MSW) is a traditional Chinese medicine formula that is composed of six herbs. It has been widely used in the treatment of gouty arthritis.

AIM OF THE STUDY

This study was designed to investigate the effect of MSW on gouty arthritis and explore the possible mechanisms.

MATERIAL AND METHODS

The rat gouty arthritis model was established by intra-articular injection of Monosodium Urate (MSU) crystal, and then treated with MSW for 5 days. The perimeter of the knee joints was measured in a time-dependent manner and serum samples were collected for the detection of TNF-α, IL-1β, and IL-6 protein levels by ELISA. The protein expressions of MMP-3, TIMP-3, STAT3, and p-STAT3 in cartilage tissues and C28/I2 cells were detected by Western blot, and the levels of proteoglycan in primary chondrocytes and cartilage tissues were determined by toluidine blue staining. In addition, AG490 and IL-6 were used in vitro to explore the function of IL-6/STAT3 pathway in the protective effect of MSU.

RESULTS

MSW reduced the joint swelling rate in gouty arthritis model and inhibited MSU induced up-regulation of IL-1β, TNF-α, and IL-6 protein levels in serum and synovial fluid. IL-1β induced an increase in p-STAT3 and MMP-3 protein expression in C28/I2 cells, as well as a decrease in TIMP-3. MSW serum inhibited the protein expression changes induced by IL-1β in vitro. Furthermore, inhibition of STAT3 signaling negated the effect of MSW serum on p-STAT3, MMP-3, and TIMP-3 protein levels in C28/I2 cells. MSW also increased the content of proteoglycan significantly both in vivo and in vitro.

CONCLUSION

Our data indicated that MSW protected rats from MSU-induced experimental gouty arthritis and IL-1β/IL-6/STAT3 pathway played an essential role in the protective effect of MSU against GA.

Silencing SGK1 alleviates osteoarthritis through epigenetic regulation of CREB1 and ABCA1 expression

AIM

Osteoarthritis (OA) is the most common joint disorder and a leading cause of disability. While early proactive management is crucial in alleviating symptoms in OA patients, currently available therapeutic approaches are yet to achieve an ideal level of efficacy. The path to the development of a potent treatment begins with the thorough understanding of the pathophysiology of OA. The present study aims to explore the mechanism by which SGK1 is involved in OA progression.

METHODS

Firstly, the potential target gene of SGK1 was screened and SGK1 expression was determined in OA through bioinformatics analysis. Mouse OA model was then established and chondrocytes were extracted, after which inflammation was induced with lipopolysaccharide (LPS). Following LPS treatment, the chondrocytes were transfected with synthesized plasmids to explore the impact of SGK1, CREB1, and ABCA1 on apoptosis, proliferation and inflammation in OA. ChIP-PCR and dual-luciferase reporter gene assay were conducted to determine the binding relation between SGK1 and CREB1 as well as between CREB1 and ABCA1.

RESULTS

OA mice presented with high expression of SGK1. Interestingly, we found that SGK1 inhibited CREB1 expression in chondrocytes, thereby inducing inflammation and suppressing chondrocyte proliferation. CREB1 was found to have a positive correlation with ABCA1 expression, while down-regulation of CREB1 resulted in the inhibition of cell proliferation and aggravated inflammation, which could be reversed by overexpressed ABCA1.

CONCLUSION

Taken altogether, silencing of SGK1 alleviated OA through epigenetic regulation of CREB1 and ABCA1 expression. These findings may provide novel insight into SGK1-based strategy for OA treatment.

Transcriptional response of human articular chondrocytes treated with fibronectin fragments: an in vitro model of the osteoarthritis phenotype

OBJECTIVE

Fibronectin is a matrix protein that is fragmented during cartilage degradation in osteoarthritis (OA). Treatment of chondrocytes with fibronectin fragments (FN-f) has been used to model OA in vitro, but the system has not been fully characterized. This study sought to define the transcriptional response of chondrocytes to FN-f, and directly compare it to responses traditionally observed in OA.

DESIGN

Normal human femoral chondrocytes isolated from tissue donors were treated with either FN-f or PBS (control) for 3, 6, or 18 h. RNA-seq libraries were compared between time-matched FN-f and control samples in order to identify changes in gene expression over time. Differentially expressed genes were compared to a published OA gene set and used for pathway, transcription factor motif, and kinome analysis.

RESULTS

FN-f treatment resulted in 3,914 differentially expressed genes over the time course. Genes that are up- or downregulated in OA were significantly up- (P < 0.00001) or downregulated (P < 0.0004) in response to FN-f. Early response genes were involved in proinflammatory pathways, whereas many late response genes were involved in ferroptosis. The promoters of upregulated genes were enriched for NF-κB, AP-1, and IRF motifs. Highly upregulated kinases included CAMK1G, IRAK2, and the uncharacterized kinase DYRK3, while growth factor receptors TGFBR2 and FGFR2 were downregulated.

CONCLUSIONS

FN-f treatment of normal human articular chondrocytes recapitulated many key aspects of the OA chondrocyte phenotype. This in vitro model is promising for future OA studies, especially considering its compatibility with genomics and genome-editing techniques.

lncRNA SNHG16 promotes the occurrence of osteoarthritis by sponging miR‑373‑3p

Osteoarthritis (OA) is a common age‑related joint disorder, for which no effective disease‑modifying drugs are currently available. Long non‑coding RNAs (lncRNAs) are involved in the occurrence of OA. lncRNA small nucleolar RNA host gene 16 (SNHG16) has been reported to regulate inflammation; however, the exact biological function of SNHG16 in OA and its underlying mechanism of action remain unclear. In this study, gene and protein expression levels were detected using reverse transcription‑quantitative PCR and western blotting, respectively. Cell apoptosis was analyzed using flow cytometry and ELISA was performed to detect TNF‑α levels. The interactions between lncRNA SNHG16 and microRNA (miR)‑373‑3p were examined using the dual‑luciferase reporter assay. lncRNA SNHG16 was upregulated in OA tissue compared with normal joint tissue. The expression levels of collagen II were significantly reduced in OA tissue compared with normal tissue. Similarly, aggrecan expression levels were significantly reduced in IL‑1β‑treated CHON‑001 cells compared with the controls. In addition, the protein expression levels of MMP13 were significantly increased in OA tissues and IL‑1β‑treated CHON‑001 cells compared with the controls. SNHG16 knockdown significantly increased the expression levels of aggrecan, and decreased the expression levels of MMP13, cleaved caspase‑3 and p21 in IL‑1β‑treated CHON‑001 cells. In addition, IL‑1β induced CHON‑001 cell apoptosis, while SNHG16 knockdown decreased IL‑1β‑induced apoptosis. Furthermore, the luciferase activity assay suggested that SNHG16 negatively regulated miR‑373‑3p in OA. Finally, the results suggested that the proinflammatory effect of IL‑1β on CHON‑001 cells was significantly reduced by SNHG16 knockdown. In conclusion, lncRNA SNHG16 knockdown significantly limited the progression of OA by sponging miR‑373‑3p in vitro, which suggested that SNHG16 may serve as a potential therapeutic target for OA.

Effects of Edible Oils with Different n-6/n-3 PUFA Ratios on Articular Cartilage Degeneration via Regulating the NF-κB Signaling Pathway

Osteoarthritis (OA), a common chronic disease, is characterized by articular cartilage degeneration and inflammation. Recent studies report that n-3 polyunsaturated fatty acids (PUFAs) exhibit protective effects against OA, while n-6 PUFAs are more likely to damage cartilage. However, the effects of edible oils with different n-6/n-3 PUFA ratios on OA are rarely reported. This study investigates the effect of linseed oil (LO), soybean oil (SO), and peanut oil (PO) on cartilage changes in mice joints following destabilization of the medial meniscus. We determined the n-6/n-3 PUFA ratios of LO, SO, and PO used in this experiment to be 1:3.85, 9.15:1, and 372.73:1, respectively. After 12 weeks of LO or SO feeding, OA mice showed increased cartilage thickness and decreased TNF-α in both the serum and cartilage, whereas no improvement was found in the PO group. This may be due to the fact that LO and SO optimized the fatty acid composition of articular cartilage. We further demonstrated that LO or SO activated GPR120 and attenuated EP4, which was followed by inhibition of the NFκB pathway and its downstream matrix-degrading enzymes: MMP13 and ADAMTS5. In conclusion, edible oils with low n-6/n-3 PUFA retard OA progression via inhibiting the NFκB pathway. This study provides a dietary guidance for OA patients.

LncRNA MIR4435-2HG inhibits the progression of osteoarthritis through miR-510-3p sponging

Osteoarthritis (OA) is a disorder of diarthrodial joints that can have multiple causes. Long non-coding RNAs (lncRNAs) participate in multiple diseases, including OA. It has recently been reported that the lncRNA microRNA 4435-2HG (MIR4435-2HG) is downregulated in OA tissues; however, the biological role of MIR4435-2HG during OA progression remains unclear. In the present study, interleukin (IL)-1β was used to establish an in vitro model of OA. Protein expressions of matrix metallopeptidase (MMP) 1, MMP13, collagen II, interleukin (IL)-17A, p65, phosphorylated (p)-p65, IκB and p-IκB in CHON-001 cells were detected by western blotting. Gene expressions of IL-17A, MIR4435-2HG and miR-510-3p in tissues or CHON-001 cells were measured by reverse transcription-quantitative PCR and western blotting, respectively. Cell Counting Kit-8 assay and immunofluorescence staining were used to investigate cell proliferation, and cell apoptosis was detected by flow cytometry. The association between MIR4435-2HG, miR-510-3p and IL-17A was investigated using the dual luciferase report assay. MIR4435-2HG and miR-510-3p overexpression were transfected into CHON-001 cells. The results demonstrated that miR4435-2HG overexpression significantly increased proliferation and inhibited apoptosis of CHON-001 cells. In addition, miR-510-3p was identified as the downstream target of MIR4435-2HG, and miR-510-3p directly targeted IL-17A. The results from the present study suggested that MIR4435-2HG could mediate the progression of OA by inactivating the NF-κB signaling pathway. In addition, miR4435-2HG overexpression inhibited OA progression, suggesting that miR4435-2HG may be considered as a potential therapeutic target in OA.

LDHA-mediated ROS generation in chondrocytes is a potential therapeutic target for osteoarthritis

The contribution of inflammation to the chronic joint disease osteoarthritis (OA) is unclear, and this lack of clarity is detrimental to efforts to identify therapeutic targets. Here we show that chondrocytes under inflammatory conditions undergo a metabolic shift that is regulated by NF-κB activation, leading to reprogramming of cell metabolism towards glycolysis and lactate dehydrogenase A (LDHA). Inflammation and metabolism can reciprocally modulate each other to regulate cartilage degradation. LDHA binds to NADH and promotes reactive oxygen species (ROS) to induce catabolic changes through stabilization of IκB-ζ, a critical pro-inflammatory mediator in chondrocytes. IκB-ζ is regulated bi-modally at the stages of transcription and protein degradation. Overall, this work highlights the function of NF-κB activity in the OA joint as well as a ROS promoting function for LDHA and identifies LDHA as a potential therapeutic target for OA treatment.

Agonism of GPR120 prevented IL-1β-induced reduction of extracellular matrix through SOX-9

Osteoarthritis (OA) is a whole-joint disease with extremely high prevalence. In all treatment approaches of OA, blocking the degradation of the cartilage extracellular matrix is an important treatment. In OA, overexpression of derivative enzymes leads to excessive catabolism and reduced synthesis of cartilage including type II collagen and aggrecan, which results in irreversible destruction of the joint. SOX9 is a transcription factor that regulates the synthesis of type II collagen and aggrecan and is significantly downregulated in OA. GPR120 has been reported to affect the pathophysiology of OA. In this study, we used the GPR120 agonist GW9508 and TUG891 in ATDC5 chondrocytes exposed to interleukin (IL)-1β to investigate the involvement of GPR120 in SOX9-mediated expression of type II collagen and aggrecan. Our findings show that agonism of GPR120 can reduce inflammation by inhibiting the expression of IL-6 and IL-8 induced by IL-1β. We also show that GW9508 and TUG891 rescue the expression of type II collagen and aggrecan by preventing the reduction of SOX9 expression. Additionally, we demonstrate that the effects of GW9508 on SOX9 expression are mediated through CREB and that GPR120 is indeed required for this effect. Thus, agonism of GPR120 by GW9508 might be a potential therapeutic strategy to halt or prevent cartilage degradation.

Early-Onset Osteoarthritis originates at the chondrocyte level in Hip Dysplasia

Subjects with developmental dysplasia of the hip (DDH) often show early-onset osteoarthritis (OA); however, the molecular mechanisms underlying this pathology are not known. We investigated whether cellular changes in chondrocytes from OA cartilage can be detected in chondrocytes from DDH cartilage before histological manifestations of degeneration. We characterized undamaged and damaged articular cartilage from 22 participants having hip replacement surgery with and without DDH (9 DDH-OA, 12 OA-only, one femoral fracture). Tissue immunostaining revealed changes in damaged OA-only cartilage that was also found in undamaged DDH-OA cartilage. Chondrocytes in situ from both groups show: (i) thicker fibers of vimentin intermediate filaments, (ii) clusters of integrin α₅β₁, (iii) positive MMP13 staining and (iv) a higher percentage of cells expressing the serine protease HtrA1. Further characterization of the extracellular matrix showed strong aggrecan and collagen II immunostaining in undamaged DDH cartilage, with no evidence of augmented cell death by activation of caspase 3. These findings suggest that early events in DDH cartilage originate at the chondrocyte level and that DDH cartilage may provide a novel opportunity to study these early changes for the development of therapeutic targets for OA.

Scutellarin suppresses cartilage destruction in osteoarthritis mouse model by inhibiting the NF-κB and PI3K/AKT signaling pathways

Osteoarthritis (OA), a common and severe disease, is predominantly characterized by cartilage destruction, which results in the degeneration of joint surfaces. Nowadays, it is accepted that TNFα plays a critical role in OA. Scutellarin, the main bioactive flavonoid glycoside extracted form Erigeron breviscapus, has been reported to exert positive effects on anti-inflammatory reactions. However, the effect of scutellarin in OA is still unknown. In this study, we isolated and cultured primary murine chondrocytes, stimulating TNF-α, in the presence or absence of scutellarin treatment. We found that the inflammatory response stimulated by TNF-α was significantly inhibited by the addition of scutellarin. Moreover, we established OA mouse models induced by surgery. In this mouse model, both inflammatory reaction and cartilage degeneration were markedly inhibited by oral administration of scutellarin. Furthermore, the cellular mechanism underlying the protective effect of scutellarin in OA was clearly associated with the NF-κB and PI3K/AKT signaling pathways. Collectively, this study proposes scutellarin as a potential therapeutic to treat joint degenerative diseases, including OA.

[Mechanical stress promotes cartilage repair in inflammatory environment]

OBJECTIVE

To investigate the effect and mechanism of mechanical stress on cartilage repair in inflammatory environment.

METHODS

The chondrogenic progenitor cells (CPCs) were isolated from the knee joint cartilage of patients with osteoarthritis (OA) undergoing total knee arthroplasty. The CPCs were cultured and expanded in a 3-D scaffold constructed with alginate. Intermittent hydrostatic pressure (IHP) was applied in a inflammatory environment induced by IL-1β, and Western blot was used to detect the expression of MAPK signaling pathway proteins. Cell proliferation was detected by CCK-8 method, and the expression of related genes like matrix metallo-proteinases 13 (MMP-13) and a disintegrins and metalloproteinase with thrombospondin motif 5 (ADAMTS-5) was detected by real-time RT-PCR. The anterior cruciate ligament of the rats was cut to construct the knee joint OA model, and the appropriate mechanical stress was constructed with external fixation to distract the knee joint in order to observe the repair of the cartilage and to explore its mechanism.

RESULTS

Adding 0.01 ng/ml IL-1β in cell culture inhibited the proliferation of CPCs. After IHP application, the expression of MAPK pathway protein was decreased, the mRNA expression of MMP-13 and ADAMTS-5 was reduced. The inhibition of IL-1β on CPCs was counteracted by IHP. Four weeks after the anterior cruciate ligament resected, the articular cartilage degeneration was observed in rats. The Mankin score in the OA treatment (joint distraction) group was lower, and the cartilage repair was better than that of the control group (P<0.01). Animal experiments found that the suitable mechanical stress reduced the expression of P-p38, MMP-13 and COLL-X, inhibited cartilage cells apoptosis and promoted the repair of OA cartilage.

CONCLUSIONS

Mechanical stress can promote the proliferation of CPCs, reduce the expression of matrix degrading enzymes, and promote the repair of OA cartilage by inhibiting MAPK signaling pathway.