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The role of amentoflavone on cartilage injury in knee osteoarthritis (KOA) rats and the underlying mechanism were explored. KOA rat and IL-1β-stimulated chondrocyte models were constructed. MTT, colony formation, and ELISA were performed to determine the cytotoxicity, cell proliferation, and inflammatory factors. The role of PTGS2 in IL-1β-stimulated chondrocytes was also confirmed through transfecting PTGS2 overexpression and silencing plasmids. Further, we analyzed how amentoflavone regulated PTGS2 to improve IL-1β-stimulated chondrocytes in vitro. Additionally, we analyzed the expression of PTGS2 after amentoflavone treatment. In vivo, HE and Safranin-O staining were carried out, and the inflammatory response was detected by ELISA and HE staining. In addition, we also analyzed the regulatory effect of amentoflavone on PTGS2 and explored the mechanism effect of PTGS2 in vitro and in vivo. The results indicated that PTGS2 was the downstream molecule of amentoflavone, which was highly expressed in IL-1β-stimulated chondrocytes and KOA rats, and amentoflavone decreased PTGS2 expression. We also confirmed the potential role of amentoflavone on KOA, which was also characterized by the repair of cartilage injury, reduction of inflammatory infiltration, and improvement of functional disability. Consistent with in vivo results, in vitro experiments gave the same conclusions. Amentoflavone reduced PTGS2 expression in IL-1β-stimulated chondrocytes and inhibited inflammation of chondrocytes via PTGS2. Collectively, the results confirmed that this drug was the potential targeted drug for KOA, whose repair effect on cartilage injury was partly related to PTGS2., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

In this study, we aim to investigate the role of enolase 1 (ENO1) in osteoarthritis (OA) pathogenic process and to uncover the underlying mechanism. To this end, we used IL-1β to induce an in vitro OA‑like chondrocyte model in human immortalized chondrocyte C-28/I2 cells. We manipulated the expression of ENO1 and cytokine receptor-like factor 1 (CRLF1) in IL-1β-induced C-28/I2 cells using siRNA and/or overexpression and tested their effects on IL-1β-induced pathologies including cell viability, apoptosis and inflammatory cytokine levels (IL-6 and TNF-α), and the expression of extracellular matrix-related enzymes and major mediators in the NF-κB signaling pathway (p-p65, p65, p-IκBα and IκBα). We used co-immunoprecipitation and immunofluorescence imaging to study a possible binding between ENO1 and CRLF1. Our data showed that IL-1β induction elevated ENO1 and CRLF1 expression in C-28/I2 cells. Silencing ENO1 or CRLF1 inhibited the IL-1β-induced cell viability damage, apoptosis, inflammation, and extracellular matrix degradation. The inhibitory effect of silencing ENO1 was reversed by CRLF1 overexpression, suggesting a functional connection between ENO1 and CRLF1, which could be attributed to a binding between these two partners. Our study could help validate the role of ENO1 in OA pathogenies and identify novel therapeutic targets for OA treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Rheumatoid arthritis is characterized by a burst of inflammation, the destruction of cartilage and the abundant release of inflammatory factors such as IL-1β. Thus, the effect of IL-1β on cartilage was examined in this study. IL-1β could cause lipid peroxidation and disturbances in iron metabolism by increasing the expression of NCOA4 and decreasing the expression of FTH, which also induced ferritinophagy. In addition, the expression of the key antioxidant proteins SLC7A11 and GPX4 was inhibited by IL-1β, resulting in ferroptosis in chondrocytes. Spermidine (SPD), a low-molecular-weight aliphatic nitrogen-containing compound that widely exists in animals, has been reported to be an antioxidant. In our study, we found that SPD could inhibit ferritinophagy and reverse the decrease in the expression of SLC7A11 and GPX4. Therefore, we uncovered one of the molecular mechanisms of cartilage destruction and inflammation and provide a potential polyamine for the treatment of RA., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Osteoarthritis (OA) is a chronic disease that involves chondrocyte injury. ADAMTS5 has been confirmed to mediate chondrocyte injury and thus regulate OA progression, but its underlying molecular mechanisms remain unclear. In the present study, interleukin‑1β (IL‑1β)‑induced chondrocytes were used to mimic OA in vitro . Cell proliferation and apoptosis were assessed by MTT assay, EdU assay and flow cytometry, and protein levels of ADAMTS5, specificity protein 1 (SP1), matrix‑related markers and Wnt/β‑catenin pathway‑related markers were examined using western blotting. In addition, ELISA was performed to measure the concentrations of inflammation factors, and oxidative stress was evaluated by detecting SOD activity and MDA levels. The mRNA expression levels of ADAMTS5 and SP1 were determined by reverse transcription‑quantitative PCR, and the interaction between SP1 and ADAMTS5 was analyzed using a dual‑luciferase reporter assay and chromatin immunoprecipitation assay. IL‑1β suppressed proliferation, but promoted apoptosis, extracellular matrix degradation, inflammation and oxidative stress in chondrocytes. ADAMTS5 was upregulated in IL‑1β‑induced chondrocytes, and its knockdown alleviated IL‑1β‑induced chondrocyte injury. SP1 could bind to the ADAMTS5 promoter region to promote its transcription, and SP1 knockdown relieved IL‑1β‑induced chondrocyte injury by reducing ADAMTS5 expression. The SP1/ADAMTS5 axis activated the Wnt/β‑catenin pathway, and the Wnt/β‑catenin pathway agonist, SKL2001, reversed the protective effect of ADAMTS5 knockdown on chondrocyte injury induced by IL‑1β. To the best of our knowledge, the present study was the first to reveal the interaction between SP1 and ADAMTS5 in OA progression and indicated that the SP1/ADAMTS5 axis mediates OA progression by regulating the Wnt/β‑catenin pathway.

Chondrocyte apoptosis is recognized as one of the pathological features involved in cartilage degeneration driving the onset and progression of knee osteoarthritis (OA). This study aimed to determine the molecular mechanism underlying the effect of clusterin (CLU), anti-apoptotic molecule, in human knee OA chondrocytes. Primary knee OA chondrocytes were isolated from the cartilage of knee OA patients and divided into five groups: (1) the cells treated with interleukin (IL)-1β, (2) CLU alone, (3) a combination of IL-1β and CLU, (4) LY294002 (PI3K inhibitor) along with IL-1β and CLU, and (5) the untreated cells. Production of apoptotic, inflammatory, anabolic, and catabolic mediators in knee OA chondrocytes was determined after treatment for 24 h. Our in vitro study uncovered that CLU significantly suppressed the production of inflammatory mediators [nitric oxide (NO), IL6, and tumor necrosis factor (TNF)-α] and apoptotic molecule (caspase-3, CASP3). CLU significantly upregulated messenger ribonucleic acid (mRNA) expressions of anabolic factors [SRY-box transcription factor-9 (SOX9) and aggrecan (ACAN)], but significantly downregulated mRNA expressions of IL6, nuclear factor kappa-B (NF-κB), CASP3, and matrix metalloproteinase-13 (MMP13). Anti-apoptotic and anti-inflammatory effects of CLU were mediated through activating PI3K/Akt signaling pathway. The findings suggest that CLU might have beneficial effects on knee OA chondrocytes by exerting anti-apoptotic and anti-inflammatory functions via PI3K/Akt pathway, making CLU a promising target for potential therapeutic interventions in knee OA., (© 2024 The Author(s). Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

During osteoarthritis (OA), chondrocytes become highly active, with increased matrix synthesis and inflammatory cytokine‑induced catabolic pathways. Early intervention strategies targeting pathological changes may attenuate or halt disease progression. The present study aimed to reveal the role of glutathione peroxidase (GPX)7 in OA. For this purpose, a research model was established by inducing C28/I2 human chondrocytes with interleukin (IL)‑1β, and the expression level of GPX7 was determined. To explore its roles, C28/I2 cells were transfected to gain GPX7 overexpression. The effects of GPX7 overexpression on intracellular inflammation, extracellular matrix (ECM) degradation, apoptosis and ferroptosis were then evaluated. In addition, the cells were treated with the ferroptosis inducer, erastin, and its effects on the aforementioned phenotypes were assessed. The level of GPX7 was decreased in response to IL‑1β treatment, and GPX7 overexpression suppressed cellular inflammation, ECM degradation and apoptosis. Moreover, the reduction of lipid peroxidation, ferrous ions and transferrin indicated that GPX7 overexpression inhibited ferroptosis. Subsequently, inflammation, ECM degradation and apoptosis were found to be promoted in the cells upon treatment with erastin. These findings suggested that the regulatory role of GPX7 may be mediated by a pathway involving ferroptosis. On the whole, the present study revealed that GPX7 reduces IL‑1β‑induced chondrocyte inflammation, apoptosis and ECM degradation partially through a mechanism involving ferroptosis. The results of the present study lay a theoretical foundation for subsequent OA‑related research and may enable the development of translational strategies for the treatment of OA.

Objective: To explore the efficacy and potential mechanism of Fengshi Gutong capsule (FSGTC) in osteoarthritis (OA) inflammation., Methods: The impact of FSGTC on laboratory indicators of OA patients was explored using data mining technology and association rule analysis. Then, the OA cell model was constructed by inducing chondrocytes (CHs) with interleukin-1β (IL-1β). In the presence of FSGTC intervention, the regulatory mechanism of PACER/COX2/PGE2 in OA-CH viability and inflammatory responses was evaluated., Results: Retrospective data mining showed that FSGTC effectively reduced inflammation indexes (ESR, HCRP) of OA patients. Cell experiments showed that LncRNA PACER (PACER) silencing inhibited the proliferation activity of OA-CHs, increased the level of COX2 protein, elevated the levels of PGE2, TNF-α, and IL-1β, and decreased the levels of IL-4 and IL-10 (p < .01). On the contrary, FSGTC-containing serum reversed the effect of PACER silencing on OA-CHs (p < .01). After the addition of COX2 pathway inhibitor, the proliferation activity of OA-CHs was enhanced; the levels of PGE2, TNF-α, and IL-1β were decreased while the levels of IL-4 and IL-10 were increased (p < .01)., Conclusion: FSGTC inhibits IL-1β-induced inflammation in CHs and ameliorates OA by upregulating PACER and downregulating COX2/PGE2., (© 2024 The Author(s). Immunity, Inflammation and Disease published by John Wiley & Sons Ltd.)

Background: Osteoarthritis (OA) is a chronic inflammatory condition that affects the articular cartilage. Astragaloside IV (AS-IV) constitutes the primary active component of the Chinese herbal medicine Huangqi (Radix Astragali Mongolici). AS-IV demonstrates anti-inflammatory and anti-apoptotic attributes, exhibiting therapeutic potential across various inflammatory and apoptosis-related disorders. Nevertheless, its pharmaceutical effects in OA are yet to be fully defined., Objectives: This study aimed to investigate the protective impact of AS-IV on rat chondrocytes treated with IL-1β and ascertain whether autophagy plays a role in this effect., Methods: Chondrocytes were isolated and cultivated from the knee joints of neonatal SD mice. The study included the blank control group, the model group, and the AS-IV concentration gradient group (50, 100, 200 μmol/L) to intervene with chondrocytes. The MTT assay was employed to assess cell viability at varying culture periods, enabling the determination of suitable concentration and duration. Subsequently, chondrocytes were treated with the optimal AS-IV concentration and divided into three groups: the model group replicated IL-1β-induced inflammatory chondrocyte injury, the AS-IV group received a co-culture of AS-IV and IL-1β, and a blank control group was established. Changes in cell morphology and structure were observed using ghost pen cyclic peptide staining. ELISA was used to measure TNF-α and GAG levels in cell supernatants. RT-qPCR assessed p62 and LC3 mRNA expression, while Western Blot evaluated p62 and LC3Ⅱ/Ⅰ protein expression., Results: AS-IV promoted chondrocyte proliferation and concurrently inhibited cell apoptosis. An optimal AS-IV dose of 200 μmol/L and a suitable reaction time of 48 h were identified. Ghost pen cyclic peptide staining indicated that the model group's cytoskeleton exhibited fusiform changes with reduced immunofluorescence intensity, as opposed to the blank control group. The AS-IV group displayed more polygonal cytoskeletal morphology with increased immunofluorescence intensity. AS-IV reduced TNF-α levels and elevated GAG levels in the culture supernatant. Additionally, AS-IV lowered p62 mRNA and protein expression while increasing LC3 mRNA expression in cultured chondrocytes., Conclusion: Our findings suggest that AS-IV mitigates inflammatory chondrocyte injury, safeguarding chondrocytes through a potential autophagy suppression mechanism. These results imply that AS-IV could offer preventive advantages for OA., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Long non-coding RNA (lncRNA) prostate cancer gene expression marker 1 (PCGEM1) has been revealed to participate in the pathogenesis of osteoarthritis (OA). However, the molecular mechanism of PCGEM1 regulating OA progression has not been fully elucidated., Methods: Fibroblast-like synoviocytes (FLSs) were isolated from synovium tissues of OA patients (OA-FLSs) and trauma donors (Normal-FLSs). The size and morphology of the isolated exosomes were analyzed by transmission electron microscopy and nanoparticle tracking analysis. Protein levels were analyzed by western blotting. Expression levels of PCGEM1, microRNA-142-5p (miR-142-5p), runt-related transcription factor 2 (RUNX2) mRNA, and OA related genes were assessed by qRT-PCR. Cell proliferation, viability, and apoptosis were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide or flow cytometry assays. The relationship between miR-142-5p and PCGEM1 or RUNX2 was verified by dual-luciferase reporter and/or RNA pull down assays., Results: PCGEM1 was overexpressed in OA cartilages and exosomes from OA-FLSs. Exosomal PCGEM1 from OA-FLSs facilitated IL-1β-induced apoptosis and cartilage matrix degradation in chondrocytes. MiR-142-5p was downregulated while RUNX2 was upregulated in OA cartilages. Exosomal PCGEM1 from OA-FLSs regulated RUNX2 expression by sponging miR-142-5p in IL-1β-induced chondrocytes. MiR-142-5p inhibitor offset exosomal PCGEM1 knockdown-mediated effects on the apoptosis and cartilage matrix degradation of IL-1β-induced chondrocytes. RUNX2 overexpression counteracted the suppressive effect of miR-142-5p mimic on apoptosis and cartilage matrix degradation of IL-1β-induced chondrocytes., Conclusion: Exosomal PCGEM1 from OA-FLSs facilitated IL-1β-induced apoptosis and cartilage matrix degradation in chondrocytes by sequestering miR-142-5p and upregulating RUNX2, which offered new insights into the pathogenesis of OA.

Background: Osteoarthritis (OA) treatment aims to improve inflammation and delay cartilage degeneration. However, there is no effective strategy presently available. Ononin, a representative isoflavone glycoside component extracted from natural Chinese herbs, exerts anti-inflammatory and proliferative effects. However, the therapeutic effect of ononin on chondrocyte inflammation remains unclear., Methods: In this study, we explored the therapeutic effect and potential mechanism of ononin in OA by establishing an interleukin-1 beta (IL-1β)-induced chondrocyte inflammation model., Results: Our results verified that ononin alleviated the IL-1β-induced decrease in chondrocyte viability, attenuated the overexpression of the inflammatory factors tumour necrosis factor α (TNF-α) and interleukin 6 (IL-6), and simultaneously inhibited the expression of cartilage extracellular matrix (ECM)-degrading enzymes such as matrix metalloproteinase-13 (MMP-13). Furthermore, the decomposition of Collagen II protein could be alleviated in the OA model by ononin. Finally, ononin improved chondrocyte inflammation by downregulating the mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signalling pathways., Conclusion: Our findings suggested that ononin could inhibit the IL-1β-induced proinflammatory response and ECM degradation in chondrocytes by interfering with the abnormal activation of the MAPK and NF-κB pathways, indicating its protective effect against OA., (© 2022. The Author(s).)

Background: Osteoarthritis (OA) is the most common joint disease in the elderly and is characterized by the progressive degeneration of articular cartilage. It is necessary to study the molecular pathology of OA. This study aimed to explore the role and mechanism of BLNK in regulating interleukin-1β (IL-1β)-induced chondrocyte injury and OA progression., Methods: GSE1919 (5 normal samples and 5 OA samples) was downloaded from the Gene Expression Omnibus (GEO) database. The limma package in R software was used to identify differentially expressed genes (DEGs) between control and OA-affected cartilage. Gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of the differentially expressed genes were also performed. Apoptosis was assessed by flow cytometry. An OA rat model was established, and the relative expression of BLNK was assessed by real time quantitative PCR (qRT-PCR) and immunohistochemical staining. The expression of collagen II, MMP9, p65 and p-p65 was measured by Western blot analysis. Moreover, inflammatory factors (TNF-α and IL-18) were assessed by ELISA. The NF-κB inhibitor JSH-23 was used to assess the impact of BLNK on the NF-κB signaling pathway., Results: In total, 1318 DEGs were identified between normal and OA-affected cartilage according to the criteria (P-value <0.05 and |logFC > 1|). These DEGs were mainly enriched in the NF-κB pathway. BLNK was highly expressed in OA cartilage tissue and injured chondrocytes. Silencing BLNK significantly downregulated the IL-1β-induced apoptosis of chondrocytes. Silencing BLNK partially increased collagen II expression and downregulated MMP13 expression. Moreover, silencing BLNK partially decreased TNF-α and IL-18 expression. BLNK silencing inhibited the activation of NF-κB in OA. Silencing BLNK delayed OA progression through the NF-κB signaling pathway., Conclusion: Silencing BLNK delayed OA progression and IL-1β-induced chondrocyte injury by regulating the NF-κB pathway., (Copyright © 2021. Published by Elsevier Ltd.)

The effects of anti-inflammatory drug gossypol on osteoarthritis (OA) treatment were discussed in this paper. After identified using toluidine blue and immunofluorescence staining of type II collagen, chondrocytes from OA patients were treated with interleukin-1β (IL-1β), gossypol, and overexpressed connexin43 (CX43). In treated chondrocytes, according to MTT assay and flow cytometry, gossypol increased viability and reduced apoptosis of IL-1β induced chondrocytes. Enzyme linked immunosorbent assay (ELISA) suggested that gossypol downregulated inflammatory tumor necrosis factor (TNF)-α level. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot confirmed that gossypol downregulated CX43, nuclear factor-kappa B (NF-κB) p65, TNF-α, toll like receptor 4 (TLR4), myeloid differentiation primary response gene 88 (MyD88) and interleukin-6 (IL-6) expressions. Besides, overexpressed CX43 reversed the effects of gossypol on viability, apoptosis, and expressions of factors related to TLR4/MyD88/NF-κB pathway of IL-1β-induced chondrocytes. In conclusion, gossypol ameliorates IL-1β-induced apoptosis and inflammation in chondrocytes by suppressing TLR4/MyD88/NF-κB pathway via downregulating CX43., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Stigmasterol (STM), one of the main active components of Achyranthes bidentata , has been shown to effectively inhibit proinflammatory factors and matrix degradation in chondrocytes. However, the effect of STM on interleukin (IL)-1β-induced chondrocytes and its specific mechanism remain unclear. The purpose of the present study was to explore the effect and mechanism of sterol regulatory element binding transcription factor 2 (SREBF2) on IL-1β induced chondrocytes in the presence of STM. CCK-8 was used to detect the effect of STM on the cell viability of mouse chondrogenic cells (ATDC5). After ATDC5 cells were induced by IL-1β, the expression of SREBF2 in osteoarthritis cells was detected by RT-qPCR. The content of iron ion in the cells was detected by using an iron colorimetric assay kit. After further transfection of a SREBF2 overexpressing vector (Oe-SREBF2) or addition of a ferroptosis inhibitor, the expression levels of inflammation and matrix degradation-related proteins were detected via Western blotting. The levels of oxidative stress in cells were determined by using an ELISA kit. The results revealed that STM had no significant effect on the viability of ATDC5 cells. STM reduced IL-1β-induced ATDC5 cell damage and ferroptosis through SREBF2 and enhanced the inhibitory effect of ferroptosis inhibitors on IL-1β-induced ATDC5 cell injury. The present data suggest that STM attenuated chondrocyte injury induced by IL-1β by regulating ferroptosis via down-regulation of SREBF2, and may have potential as a novel therapeutic method for knee osteoarthritis.

Osteoarthritis (OA) is a prevailing chronic disease in Orthopedics that characterized with severely damaged cartilage and subchondral bone, thus leading to profound disorders of synovial joints. Platelet-rich plasma (PRP) has been applied as a popular non-operative treatment option for promoting musculoskeletal healing. Our previous work demonstrated that PRP protected chondrocytes from interleukin-1β (IL-1β)-induced apoptosis in vitro. However, the underlying mechanism behind the treatment remains unclear. The current study aimed to unveil the molecular signaling underlying its protective role in chondrocytes. Rat chondrocytes were isolated from newborn Sprague Dawley rats and treated with 5 ng/mL IL-1β for 24 h. The expression of hypoxia-inducible factor 2α (HIF-2α) was determined in both mRNA and protein levels. Next, loss- and gain-of-function assays for HIF-2α were performed using small-interfering RNA (siRNA) specific for HIF-2α and adenovirus-mediated HIF-2α overexpression, respectively. In addition, cell apoptosis markers, matrix metalloproteinase (MMP)-1, 3, -9 and -13, and extracellular matrix-related genes were evaluated. Our results demonstrated that IL-1β induced distinct inflammation in chondrocytes. In addition, HIF-2α upregulated in the IL-1β-treated chondrocytes compared to the untreated cells. Interestingly, 10% PRP protected chondrocytes against IL-1β-induced apoptosis and matrix degradation, and meanwhile suppressed the HIF-2α activation. Furthermore, HIF-2α siRNA and HIF-2α overexpression experiments indicated that PRP induced chondroprotection through targeting HIF-2α. Taken together, our findings indicated that PRP attenuates IL-1β-induced chondrocyte apoptosis and inflammation at least partially through inhibiting HIF-2α., (Copyright © 2021. Published by Elsevier Ltd.)

Chondrocyte dysregulation plays a critical role in the development of osteoarthritis (OA). The pro-inflammatory cytokine interleukin-1β (IL-1β) activates chondrocytes and degrades the structural extracellular matrix (ECM). These events are the important mechanism of OA. Trelagliptin, a selective inhibitor of dipeptidyl Peptidase 4 (DPP-4) used for the treatment of type 2 diabetes mellitus (T2DM), has displayed a wide range of anti-inflammatory capacities. The effects of Trelagliptin in OA and chondrocytes have not been tested before. Here, we show that Trelagliptin mitigates IL-1β-induced production of inflammatory cytokines such as interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor-alpha (TNF-α) in human chondrocytes. Trelagliptin ameliorates IL-1β-induced oxidative stress by reducing the generation of reactive oxygen species (ROS). Particularly, the presence of Trelagliptin prevents IL-1β-induced reduction of Acan genes and the protein Aggrecan. Moreover, we show that Trelagliptin restores IL-1β-induced reduction of SOX-9 and that the knockdown of SOX-9 abolishes the protective effects of Trelagliptin. Mechanistically, we demonstrate that AMPK is required for the amelioration of Trelagliptin on SOX-9- reduction by IL-1β. Collectively, our study demonstrates that the DPP-4 inhibitor Trelagliptin has a protective effect on chondrocyte function. Trelagliptin may have the potential role to antagonize chondrocyte-derived inflammation in OA., (Copyright © 2021. Published by Elsevier Ltd.)

Osteoarthritis (OA), a degenerative disorder, is considered to be one of the most common forms of arthritis. Limonin (Lim) is extracted from lemons and other citrus fruits. Limonin has been reported to have anti-inflammatory effects, while inflammation is a major cause of OA; thus, we propose that limonin may have a therapeutic effect on OA. In this study, the therapeutic effect of limonin on OA was assessed in chondrocytes in vitro in IL-1 β induced OA and in the destabilization of the medial meniscus (DMM) mice in vivo . The Nrf2/HO-1/NF- κ B signaling pathway was evaluated to illustrate the working mechanism of limonin on OA in chondrocytes. In this study, it was found that limonin can reduce the level of IL-1 β induced proinflammatory cytokines such as INOS, COX-2, PGE2, NO, TNF- α , and IL-6. Limonin can also diminish the biosynthesis of IL-1 β -stimulated chondrogenic catabolic enzymes such as MMP13 and ADAMTS5 in chondrocytes. The research on the mechanism study demonstrated that limonin exerts its protective effect on OA through the Nrf2/HO-1/NF- κ B signaling pathway. Taken together, the present study shows that limonin may activate the Nrf2/HO-1/NF- κ B pathway to alleviate OA, making it a candidate therapeutic agent for OA., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Jie Jin et al.)

Aims: Osteoarthritis (OA) is the leading cause of physical disability in middle-aged and elderly people globally. Previous studies have revealed that circular RNA (circRNA) is involved in the pathogenesis of OA. In this study, we studied the role of circ&#95;0001846 in interleukin-1β (IL-1β)-induced OA progression., Methods: Twenty-one patients with OA and 17 volunteers were recruited for the collection of articular cartilage tissues. The expression of circ&#95;0001846, microRNA-149-5p (miR-149-5p) and Wingless-type MMTV integration site family, member 5B (WNT5B) was detected by quantitative real-time polymerase chain reaction. The protein expression was determined by western blot analysis. Cell viability, apoptosis, invasion and migration were demonstrated by cell counting kit-8, flow cytometry analysis, transwell invasion and wound-healing assays, respectively. The levels of IL-6 and tumor necrosis factor-α were detected by Enzyme-linked immunosorbent assay. The interaction between miR-149-5p and circ&#95;0001846 or WNT5B was predicted by starbase online database, and proved by dual-luciferase reporter and RIP assays., Results: Circ&#95;0001846 and WNT5B expression were upregulated, while miR-149-5p expression was downregulated in articular cartilage tissues from patients with OA and IL-1β-treated CHON-001 cells compared with normal articular cartilage tissues or untreated CHON-001 cells. Circ&#95;0001846 expression was increased in IL-1β-treated CHON-001 cell exosomes. Circ&#95;0001846 knockdown reversed IL-1β-mediated cell proliferation, apoptosis, migration, invasion, inflammation and extracellular matrix (ECM) degradation in CHON-001 cells. Additionally, circ&#95;0001846 participated in IL-1β-induced chondrocyte cell damage by sponging miR-149-5p. MiR-149-5p mediated IL-1β-induced chondrocyte cell dysfunction by targeting WNT5B. Furthermore, circ&#95;0001846 secretion was mediated by exosomes in IL-1β-treated CHON-001 cells., Conclusion: Exosome-mediated transfer of circ&#95;0001846 modulated IL-1β-induced chondrocyte cell damage by miR-149-5p/WNT5B axis, providing a novel avenue for the therapy of OA., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Recently, mesenchymal stem cells (MSCs) have been the most explored cells for cell therapy for osteoarthritis (OA) that can be obtained from various sources. Synovial membrane MSCs (SMMSCs) provide best potential for OA therapy, however they are not widely explored. Conditioned medium of SMMSCs (SMMSCs-CM) rich in growth factors and cytokines can inhibit apoptosis and increase chondrocytes cell proliferation. The aim of the present study was to determine growth factors content in SMMSCs-CM as well as the chondrogenic and chondroprotective markers expression in OA model after insulin-like growth factor (IGF)1-induced and non-induced SMMSCs-CM treatments. Chondrocyte cell line (CHON002) was induced by IL1β as OA model (CHON002 with IL1β (IL1β-CHON002)) and treated with SMMSCs-CM with or without IGF1 induction to determine its effectiveness in repairing OA cells model. ELISA was used to assay BMP2, fibroblast growth factor 18 (FGF18) and transforming growth factor (TGF) β1 (TGFβ1) levels in SMMSCs-CM, matrix metalloproteinase (MMP) 13 (MMP13) and a disintegrin and metalloproteinase with thrombospondin motif 4 (ADAMTS4) levels in OA cells model treated with SMMSCs-CM. RT-qPCR analyses were used to investigate the gene expression of SOX9, COL2, and COL10. CM from SMMSCs cultured and induced by IGF1 150 ng/mL was the most effective concentration for increasing the content of growth factor markers of SMMSCs-CM, which had successfully increased negative cartilage hypertrophy markers (SOX9 and COL2) and reduced hypertrophy markers (COL10, MMP13, and ADAMTS4). Preconditioning with IGF1 has better and very significant results in lowering MMP13 and ADAMTS4 levels. The present study supports IGF1 pre-conditioned SMMSCs-CM to develop a new therapeutic approach in OA improvement through its chondrogenic and chondroprotective roles., (© 2021 The Author(s).)

In this study we investigated the role and mechanism of cardamonin on IL-1β induced injury in OA. CHON-001 cells were treated with cardamonin and IL-1β and transfected with silencing nuclear factor erythroid 2-related factor 2 (siNrf2). Cell viability was detected by Cell Counting Kit-8 assay and flow cytometer assay was utilized for cell apoptosis assessment. IL-6, IL-8, TNF-α and Nrf2 mRNA expression was tested by qRT-PCR. Western blot was employed to evaluate MMP-3, MMP-13, Collagen II, Nrf2, NQO-1, NLRP3, Caspase 1 and apoptosis-associated speck-like protein containing a caspase-1 recruitment domain (ASC) protein levels. In CHON-001 cells, IL-1β suppressed cell viability and Collagen II level while promoting cell apoptosis and expression of pro-inflammatory cytokines (IL-6, IL-8, TNF-α), MMPs (MMP-3, MMP-13), NQO-1, and NLRP3 inflammasome (NLRP3, Caspase 1 and ASC), with no significant influence on Nrf2. Cardamonin reversed the effect of IL-1β on cell viability, cell apoptosis, pro-inflammatory cytokines, MMPs, Collagen II, and NLRP3 inflammasome levels. In addition, cardamonin advanced Nrf2 and NQO-1 expression of CHON-001 cells. SiNrf2 reversed the function of cardamonin on IL-1β-induced cell apoptosis and expression of pro-inflammatory cytokines, Nrf2, NQO-1, and NLRP3 inflammasome in chondrocytes. Taken together Cardamonin inhibited IL-1β induced injury by inhibition of NLRP3 inflammasome via activating Nrf2/NQO1 signaling pathway in chondrocyte.

Background: MiR-24-3p has been reported to be involved in an osteoarthritis (OA)-resembling environment. However, the functional role and underlying mechanism of miR-24-3p in chondrocyte injury associated with OA remains unknown., Methods: The expression of miR-24-3p was determined using reverse transcription quantitative PCR analysis in OA cases and control patients, as well as IL-1β-stimulated chondrocyte cell line CHON-001. The cell viability was analyzed by CCK-8 assay. Apoptosis status was assessed by caspase-3 activity detection. The pro-inflammatory cytokines (TNF-α and IL-18) were determined using ELISA assay. The association between miR-24-3p and B cell leukemia 2-like 12 (BCL2L12) was confirmed by luciferase reporter assay., Results: We first observed that miR-24-3p expression level was lower in the OA cases than in the control patients and IL-1β decreased the expression of miR-24-3p in the chondrocyte CHON-001. Functionally, overexpression of miR-24-3p significantly attenuated IL-1β-induced chondrocyte injury, as reflected by increased cell viability, decreased caspase-3 activity, and pro-inflammatory cytokines (TNF-α and IL-18). Western blot analysis showed that overexpression of miR-24-3p weakened IL-1β-induced cartilage degradation, as reflected by reduction of MMP13 (Matrix Metalloproteinase-13) and ADAMTS5 (a disintegrin and metalloproteinase with thrombospondin motifs-5) protein expression, as well as markedly elevation of COL2A1 (collagen type II). Importantly, BCL2L12 was demonstrated to be a target of miR-24-3p. BCL2L12 knockdown imitated, while overexpression significantly abrogated the protective effects of miR-24-3p against IL-1β-induced chondrocyte injury., Conclusions: In conclusion, our work provides important insight into targeting miR-24-3p/BCL2L12 axis in OA therapy.

The inflammatory environment and excessive chondrocyte apoptosis have been demonstrated to play crucial roles in the onset of osteoarthritis (OA). Hydrogen sulfide (H 2 S), a gaseous signalling molecule, exerts an inhibitory effect on inflammation and apoptosis in several degenerative diseases. However, the protective effect of H 2 S against OA has not been fully clarified, and its underlying mechanism should be examined further. In the current study, the role of endogenous H 2 S in the pathogenesis of OA and its protective effects on interleukin (IL)-1β-induced chondrocytes were identified. Our data revealed decreased H 2 S expression in both human degenerative OA cartilage tissue and IL-1β-induced chondrocytes. Pretreatment with the H 2 S donor sodium hydrosulfide (NaHS) dramatically attenuated IL-1β-induced overproduction of inflammatory cytokines and improved the balance between anabolic and catabolic chondrocyte capacities, and these effects were dependent on PI3K/AKT pathway-mediated inhibition of nuclear factor kappa B (NF-κB). Moreover, mitochondrial dysfunction-related apoptosis was significantly reversed by NaHS in IL-1β-stimulated chondrocytes. Mechanistically, NaHS partially suppressed IL-1β-induced phosphorylation of the mitogen-activated protein kinase (MAPK) cascades. Furthermore, in the destabilization of the medial meniscus mouse model, OA progression was ameliorated by NaHS administration. Taken together, these results suggest that H 2 S may antagonize IL-1β-induced inflammation and mitochondrial dysfunction-related apoptosis via selective suppression of the PI3K/Akt/NF-κB and MAPK signalling pathways, respectively, in chondrocytes and may be a potential therapeutic agent for the treatment of OA., (© 2020 Wiley Periodicals LLC.)

Persistent hypotonic and inflammatory conditions in the joint cavity can lead to the loss of cartilage matrix and cell death, which are the important mechanisms of osteoarthritis (OA) onset. Previous studies have confirmed that the existence of a hypotonic environment is a red flag for inflammation, as hypotonic environment induces the opening of the chloride channel of the cell and promotes chloride ion efflux, which prompts the cell volume to increase. Chloride channels play an important role in the regulation of mineralization and chondrocyte death. Here, we reported that OA chondrocytes showed a significant increase of cell death rate and the imbalance of cartilage matrix catabolism. We found that the distribution of skeleton protein F-actin was disordered. In addition, the volume-sensitive chloride current of OA chondrocytes decreased significantly with the increase of the expression levels of inflammation-related proteins caspase-1, caspase-3, and NLRP3. Moreover, interleukin-1β (IL-1β) showed a potential to activate the chloride current of normal chondrocytes. These results indicate that IL-1β-induced chloride channel opening in chondrocytes may be closely related to the occurrence of OA. This chloride channel opening process may therefore be a potential target for the treatment of OA., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences.)

Osteoarthritis (OA) is a heterogeneous disease that is consistently difficult to treat due to the complexity of the regulatory network involved in OA pathogenesis, especially in terms of cartilage degeneration. As a C-2 epimer of glucose, d-mannose can alleviate bone loss and repress immunopathology by upregulating regulatory T cells; however, the role of d-mannose in OA-related cartilage degeneration remains unknown. In this study, we investigated the chondroprotective effect of d-mannose in vitro and in vivo on OA. We found that incubating interleukin (IL)-1β-treated rat chondrocytes with d-mannose restrained OA degeneration by elevating cell proliferation, strongly activating autophagy, reducing apoptosis, and downregulating catabolism. Additionally, oral gavage administration of d-mannose to monosodium iodoacetate (MIA)-treated rats revealed that a median (1.25 g/kg/day) rather than high or low dose of d-mannose suppressed OA progression and attenuated OA development based on lower macroscopic scores for cartilage, decreased histological scores for cartilage and synovium, strongly activated autophagy, and downregulated catabolism. In terms of a downstream mechanism, we showed that d-mannose might attenuate OA degeneration by activating autophagy in IL-1β-treated rat chondrocytes by promoting the phosphorylation of 5' AMP-activated protein kinase (AMPK). Our in vitro findings revealed that d-mannose delayed IL-1β-induced OA degeneration in rat chondrocytes by enhancing autophagy activation through the AMPK pathway. Furthermore, the in vivo results indicated that a median dose of d-mannose suppressed MIA-induced OA development. These results suggested that d-mannose exhibits chondroprotective effects and represents a potential disease-modifying drug and novel therapeutic agent for OA., (Copyright © 2021 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Interleukin (IL)-1β is an important pro-inflammatory cytokine in the progression of osteoarthritis (OA), which impairs mitochondrial function and induces the production of nitric oxide (NO) in chondrocytes. The aim was to investigate if blockade of NO production prevents IL-1β-induced mitochondrial dysfunction in chondrocytes and whether cAMP and AMP-activated protein kinase (AMPK) affects NO production and mitochondrial function. Isolated human OA chondrocytes were stimulated with IL-1β in combination with/without forskolin, L-NIL, AMPK activator or inhibitor. The release of NO, IL-6, PGE 2 , MMP3, and the expression of iNOS were measured by ELISA or Western blot. Parameters of mitochondrial respiration were measured using a seahorse analyzer. IL-1β significantly induced NO release and mitochondrial dysfunction. Inhibition of iNOS by L-NIL prevented IL-1β-induced NO release and mitochondrial dysfunction but not IL-1β-induced release of IL-6, PGE 2 , and MMP3. Enhancement of cAMP by forskolin reduced IL-1β-induced NO release and prevented IL-1β-induced mitochondrial impairment. Activation of AMPK increased IL-1β-induced NO production and the negative impact of IL-1β on mitochondrial respiration, whereas inhibition of AMPK had the opposite effects. NO is critically involved in the IL-1β-induced impairment of mitochondrial respiration in human OA chondrocytes. Increased intracellular cAMP or inhibition of AMPK prevented both IL-1β-induced NO release and mitochondrial dysfunction.

Background: Osteoarthritis (OA) is a chronic inflammatory disease caused by degenerative changes of articular cartilage, involving in the expression changes of special circular RNAs (circRNAs). This study aimed to explore the role of circ&#95;DHRS3 in OA cell models and provide a potential mechanism., Methods: OA cell models were constructed using human chondrocytes with Interleukin-1 beta (IL-1β) treatment. The expression of circ&#95;DHRS3, microRNA (miR)-183-5p and Gremlin 1 (GREM1) mRNA was detected using real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation was identified using 3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide (MTT) assay. Cell apoptosis was investigated using flow cytometry assay. The protein levels of proliferation- and apoptosis-related proteins were quantified by western blot. The levels of extracellular matrix (ECM)-associated proteins were quantified by western blot to assess ECM degradation. The relationship between miR-183-5p and circ&#95;DHRS3 or GREM1 was predicted and then verified by dual-luciferase reporter assay., Results: Circ&#95;DHRS3 expression was elevated in OA cartilage tissues and IL-1β-treated chondrocytes. Circ&#95;DHRS3 was resistant to RNase R and Actinomycin D. Circ&#95;DHRS3 knockdown promoted chondrocyte proliferation inhibited by IL-1β, and alleviated IL-1β-induced apoptosis and ECM degradation, which were reversed by the inhibition of miR-183-5p, a target of circ&#95;DHRS3. MiR-183-5p restoration also enhanced IL-1β-blocked cell proliferation, and relieved IL-1β-induced cell apoptosis and ECM degradation, while GREM1 (a target of miR-183-5p) overexpression abolished the effects of miR-183-5p restoration. Moreover, circ&#95;DHRS3 regulated GREM1 expression by targeting miR-183-5p., Conclusion: Circ&#95;DHRS3 mediated IL-1β-administered chondrocyte proliferation, apoptosis and ECM degradation by positively regulating GREM1 expression via competitively targeting miR-183-5p., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Osteoarthritis (OA) is an age-related, chronic degenerative disease. With the increasing median age of the population, this disease has become an important public health problem. New, disease-modifying therapies are needed. A potential novel molecular target is phospholipase Cγ1 (PLCγ1), a critical enzyme with important functions including calcium signaling regulation and cell proliferation. In rat chondrocytes treated with IL-1β (20 ng·mL -1 for 36 h), inhibition of PLCγ1 with U73122 (2 μm for 12 h) increased levels and expression of the cartilage matrix components Collagen2 and Aggrecan. This beneficial effect of PLCγ1 inhibition was counteracted by increased chondrocyte apoptosis and necroptosis, increased cell death, and increase levels of ROS, all potentially negative for OA. Combined treatment of IL-1β + U73122-treated chondrocytes with inhibitors of apoptosis (Z-VAD, 10 μm) and necroptosis (Nec-1, 30 μm) enhanced the increases in levels and expression of Collagen2 and Aggrecan, and prevented the increases in cell death and ROS levels. These results suggest that PLCγ1 inhibition may be a viable approach for an OA therapy, if combined with targeted inhibition of chondrocyte apoptosis and necroptosis., (© 2020 The Authors. FEBS Open Bio published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Osteoarthritis (OA) is a chronic joint disease with high prevalence. However, effective treatment options for OA are still lacking. It was previously reported that LINC00473 was upregulated in patients with OA and upregulated LINC00473 might be associated with the progression of OA; however, the role of LINC00473 in OA remains to be investigated. CHON-001 human chondrocyte cells stimulated with 10 ng/mL interleukin (IL)-1β were utilized to mimic OA in vitro. Protein expression, cell apoptosis and cell proliferation of CHON-001 cells were investigated by Western blot, Annexin V and propidium iodide (PI) double staining, cell counting-8 kit assay and immunofluorescence staining respectively. The result indicated IL-1β triggered viability decrease and apoptosis in CHON-001 cells, which was alleviated by LINC00473 knockdown. Meanwhile, IL-1β-induced upregulation of cleaved caspase 3 and Bax were ameliorated by LINC00473 knockdown. Likewise, IL-1β-induced downregulation of X-linked inhibitor of apoptosis protein was alleviated by LINC00473 knockdown. In addition, LINC00473 knockdown protected CHON-001 cells against IL-1β by inhibiting the methylation of LIM mineralization protein (LMP)-1 gene. Moreover, c-Jun N-terminal kinase (JNK)/nuclear factor-kappaB (NF-κB) signaling pathway was proved to be involved in the cell protective effect of LINC00473 knockdown in IL-1β treated CHON-001 cells. Taken together, LINC00473 knockdown defended CHON-001 cells from IL-1β induced cell injury via inhibition of the methylation of LMP-1. Thus, LINC00473 might possibly act as a novel therapeutic target for OA.

Introduction: Osteoarthritis (OA) is a common musculoskeletal disease characterized by pain, stiffness, limited activity, occasional effusion, and local inflammation. MiR-146 is one of the noncoding RNA closely related to OA, but the role of miR-146 in OA remains controversial. The tumour necrosis factor receptor OX40 is activated by its cognate ligand OX40L (TNFSF4) and functions as a T-cell costimulatory molecule. The T-cell functions, including cytokine production, expansion, and survival, are enhanced by the OX40 costimulatory signals., Methods: We established an inflammatory model of condylar chondrocytes induced by IL-1β and TNF-α and detected the expression of miRNA by miRNA sequencing. Then, cell transfection was used to study the role of miR146a-5p in OA. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and database analysis were used to screen out potential target genes of miR-146a-5p. A dual luciferase activity assay tested whether ox40l is the target gene of miR-146a-5p., Results: MiR-146a-5p and OX40L was upregulated after induced by IL-1β and TNF-α, miR-146a-5p reduced the production of inflammatory factors but had no effect on chondrophenotypic factors, and ox40l was targeted by miR-146a-5p., Conclusion: OX40L and miR-146a-5p of condylar chondrocytes in the inflammatory environment (induced by IL-1β and TNF-α) were significantly increased, miR-146a-5p is a protective factor in the inflammatory response, which can reduce the production of inflammatory factors, and miR-146a-5p may regulate T-cell-mediated immunity through targeting of ox40l in OA., (© 2020 S. Karger AG, Basel.)

Background: As a common joint disease, osteoarthritis (OA) is the main cause of limited joint mobility and disability. The role of lncRNAs in the regulation of OA is increasingly discovered. Therefore, further exploring the function of SNHG7 in OA is of great significance for understanding its occurrence and development., Methods: We used interleukin-1β (IL-1β) to treat to establish an OA model primary on chondrocytes in vitro, and gain- and loss of function assays of SNHG7 and miR-214-5p were conducted. The cell viability and apoptosis of chondrocytes were detected by CCK8 assay, BrdU assay and flow cytometry. The inflammatory cytokines (IL-1β, IL-6 and TNF-α), NLRP3 inflammasome, protein level of PPARGC1B, PPARγ, P38 and NF-κB were determined by RT-PCR and/or western blot., Results: The results showed that SNHG7 was distinctly downregulated, while miR-214-5p was significantly upregulated in OA patients and primary chondrocytes treated with IL-1β. In addition, SNHG7 enhanced cell viability, inhibited apoptosis and inflammation of IL-1β-mediated chondrocytes. In contrast, miR-214-5p upregulation reduced viability, promoted apoptosis and inflammation of chondrocytes. Mechanistically, SNHG7 served as a competitive endogenous RNA by sponging miR-214-5p, which targeted PPARGC1B. Besides, the results of the compensation experiment affirmed that miR-214-5p attenuates SNHG7-mediated protective effects on IL-1β-mediated chondrocytes against apoptosis and inflammation, and activating PPARγ pathway markedly dampened the cytotoxic effects of miR-214-5p., Conclusions: Collectively, The above results confirmed that SNHG7 prevents IL-1β induced OA by inhibiting NLRP3 inflammasome and apoptosis through miR-214-5p/PPARGC1B axis., (Copyright © 2020 Elsevier B.V. All rights reserved.)

METTL3 is an important regulatory molecule in the process of RNA biosynthesis. It mainly regulates mRNA translation, alternative splicing and microRNA maturation by mediating m6A-dependent methylation. Interleukin 1β (IL-1β) is an important inducer of cartilage degeneration that can induce an inflammatory cascade reaction in chondrocytes and inhibit the normal biological function of cells. However, it is unclear whether IL-1β is related to METTL3 expression or plays a regulatory role in endplate cartilage degeneration. In this study, we found that the expression level of METTL3 and methylation level of m6A in human endplate cartilage with different degrees of degeneration were significantly different, indicating that the methylation modification of m6A mediated by METTL3 was closely related to the degeneration of human endplate cartilage. Next, through a series of functional experiments, we found that miR-126-5p can play a significant role in IL-1β-induced degeneration of endplate chondrocytes. Moreover, we found that miR-126-5p can inhibit the PI3K/Akt signalling pathway by targeting PIK3R2 gene, leading to the disorder of cell vitality and functional metabolism. To further determine whether METTL3 could regulate miR-126-5p maturation, we first confirmed that METTL3 can bind the key protein underlying pri-miRNA processing, DGCR8. Additionally, when METTL3 expression was inhibited, the miR-126-5p maturation process was blocked. Therefore, we hypothesized that METTL3 can promote cleavage of pri-miR-126-5p and form mature miR-126-5p by combining with DGCR8., (© 2020 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

The dysregulated circular RNAs (circRNAs) are relevant to the development of osteoarthritis (OA). The circRNA serpin family E member 2 (circSERPINE2) is dysregulated in OA, while the role and mechanism of circSERPINE2 in OA are largely unknown. The aim of our research is to explore how and whether circSERPINE2 regulates interleukin-1β (IL-1β)-caused chondrocyte damage in OA. In the present study, the chondrocytes (CHON-001 cells) were exposed to IL-1β to mimic the injury in OA. CircSERPINE2, microRNA-495 (miR-495) and transforming growth factor-β receptor 2 (TGFBR2) abundances were detected via quantitative reverse-transcription polymerase chain reaction (qRT-PCR) or Western blot. Cell apoptosis was assessed via viability, apoptotic rate and caspase-3 activity. Extracellular matrix was investigated by levels of Sry-type high-mobility-group box 9 (SOX9), collagen type II α 1 (COL2A1) and Aggrecan using Western blot. The interaction among circSERPINE2, miR-495 and TGFBR2 was assessed via dual-luciferase reporter analysis and RNA immunoprecipitation (RIP). The results showed that circSERPINE2 expression was reduced in OA patients and IL-1β-treated chondrocytes. CircSERPINE2 overexpression mitigated IL-1β-caused apoptosis and extracellular matrix degradation. miR-495 was targeted by circSERPINE2 and up-regulated in OA patients and IL-1β-treated chondrocytes. miR-495 up-regulation reversed overexpression of circSERPINE2-mediated inhibition of apoptosis and extracellular matrix degradation. TGFBR2 was targeted by miR-495 and lowly expressed in OA patients and IL-1β-treated chondrocytes. CircSERPINE2 could mediate TGFBR2 expression by binding with miR-495. As a conclusion, circSERPINE2 attenuated IL-1β-caused apoptosis and extracellular matrix degradation of chondrocytes by regulating miR-495/TGFBR2 axis, indicating a new target for OA treatment., (© 2020 The Author(s).)

Osteoarthritis (OA) is an age-related chronic joint degenerative disease. Interleukin 1 beta (IL-1β) is considered a marker for the progression of OA. In this study, we found that Ubiquitin-Specific Peptidase 49 (USP49) was significantly less expressed in OA patients compared with healthy individuals. Treating primary rat chondrocytes with different concentrations of IL-1β resulted in decreased Usp49 expression, while Usp49 overexpression could attenuate IL-1β-induced chondrocyte apoptosis by promoting Axin deubiquitination. The deubiquitination of Axin led to the accumulation of the protein, which in turn resulted in β-catenin degradation and Wnt/β-catenin signaling cascade inhibition. Interestingly, we also found that [6]-gingerol, an anti-OA drug, could upregulate the protein level of Usp49 and suppress the Wnt/β-catenin signaling cascade in primary rat chondrocytes. Taken together, our study not only demonstrates that Usp49 can negatively regulate the progression of OA by inhibiting the Wnt/β-catenin signaling cascade, but also elucidates the underlying molecular mechanisms.

Background: Cobalt ions from some orthopaedic implants induce a dose-dependent cytotoxic and pro-inflammatory response. Recent studies show that sub-toxic levels of cobalt influence actin organisation regulating fibroblasts and macrophages behaviour. However little is known about the influence of sub-toxic levels of cobalt on articular cartilage biology and biomechanics. Previously, we have reported that IL-1β signalling in chondrocytes, is regulated by primary cilia and associated intraflagellar transport. Since primary cilia expression is modulated by actin organisation, we set out to test the hypothesis that sub-toxic levels of cobalt regulate cilia expression and IL-1β signalling thereby influencing articular cartilage degradation., Methods: Isolated chondrocytes and bovine cartilage explants were subjected to Co 2+ in the presence and absence of IL-1β. Primary cilia were monitored by confocal immunofluorescence. Nitric oxide and PGE 2 release were used to monitor IL-1β signalling. Degradation of cartilage matrix was assessed by the release of sGAG and the biomechanical properties of the tissue in uniaxial unconfined compression., Findings: Sub-toxic levels of Co 2+ (50 μM) blocked IL-1β-induced primary cilia elongation in isolated chondrocytes. This was associated with disruption of pro-inflammatory signalling in both isolated chondrocytes and cartilage explants, and inhibition of cartilage matrix degradation and loss of biomechanical properties., Interpretation: This study reveals that low levels of cobalt ions are anti-inflammatory, preventing cartilage degradation in response to IL-1β. This mechanism is associated with regulation of primary cilia elongation. These observations provide new insight into the potential beneficial role of cobalt and may lead to novel mechanisms for controlling cartilage inflammation., Competing Interests: Declaration of competing interest We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2019. Published by Elsevier Ltd.)

Background: Osteoarthritis (OA) is a regular age-related disease that affects millions of people. Resveratrol (RSV) is a flavonoid with a stilbene structure with different pharmacological effects. The purpose of the experiment was to evaluate the protective role of RSV against the human OA chondrocyte injury induced by interleukin-1β (IL-1β)., Methods: Chondrocytes were isolated from OA patients and identified by type II collagen, safranin O staining, and toluidine blue staining. Differentially expressed genes in chondrocytes treated RSV were identified by RNA sequencing. Kyoto encyclopedia of genes and genomes (KEGG) pathway as well as gene ontology (GO) were further conducted through Metascape online tool. A cell counting kit-8 (CCK-8) assay was applied to discover the viability of chondrocytes (6, 12, 24, and 48 μM). Many genes associated with inflammation and matrix degradation are evaluated by real-time PCR (RT-PCR) as well as western blot (WB). The mechanism of RSV for protecting IL-1β induced chondrocytes injury was further measured through immunofluorescence and WB assays., Results: A total of 845 differentially expressed genes (upregulated = 499, downregulated = 346) were found. These differentially expressed genes mainly enriched into negative regulation of catabolic process, autophagy, and cellular catabolic process, intrinsic apoptotic, apoptotic, and regulation of apoptotic signaling pathway, cellular response to abiotic stimulus, external stimuli, stress, and radiation. These differentially expressed genes were obviously enriched in NF-kB signaling pathway. RSV at the concentration of 48 μM markedly weakened the viability of the cells after 24 h of treatment (87% vs 100%, P < 0.05). No obvious difference was observed between the 6, 12, and 24 μM groups (106% vs 100%, 104% vs 100%, 103% vs 100%, P > 0.05). RSV (24 μM) also markedly depressed the levels of PGE2 and NO induced by IL-1β by 25% and 29% respectively (P < 0.05). Our experiment pointed out that RSV could dramatically inhibit the inflammatory response induced by IL-1β, including the MMP-13, MMP-3, and MMP-1 in human OA chondrocytes by 50%, 35%, and 33% respectively. On the other hand, RSV inhibited cyclooxygenase-2 (COX-2), matrix metalloproteinase-1 (MMP-1), MMP-3, MMP-13, and inducible nitric oxide synthase (iNOs) expression (P < 0.05), while increased collagen-II and aggrecan levels (P < 0.05). From a mechanistic perspective, RSV inhibited the degradation of IκB-α as well as the activation of nuclear factor-kappa B (NF-κB) induced by IL-1β., Conclusion: In summary, RSV regulates the signaling pathway of NF-κB, thus inhibiting inflammation and matrix degradation in chondrocytes. More studies should be focused on the treatment efficacy of RSV for OA in vivo.

The tripartite motif (TRIM) protein family are implicated in a wide array of cellular processes, including cell growth, differentiation, apoptosis and inflammation. This study aimed to investigate the specific function of TRIM59 in chondrocytes and its association with the pathophysiology of osteoarthritis (OA). We observed the downregulated TRIM59 expression in OA cartilage compared to normal tissues. Overexpression of TRIM59 suppressed interleukin 1 beta (IL-1β)-induced extracellular matrix (ECM) metabolic imbalance, proinflammatory cytokine production, apoptosis and decrease in cell viability. Mechanistic analyses further revealed that IL-1β-induced activation of the NF-κB and JAK2/STAT3 pathway is suppressed upon TRIM59 overexpression. TRIM59 expression was consistently decreased in a rat OA model in vivo, and its overexpression led to inhibition of matrix metallopeptidase-13 (MMP-13) production, proinflammatory cytokine levels and increased collagen type II (collagen II) and aggrecan synthesis. Our data collectively suggest that TRIM59 plays a critical in OA development through regulation of NF-κB and JAK2/STAT3 signaling pathway. Pharmacological upregulation of TRIM59 may therefore present an effective novel therapeutic approach for OA., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Osteoarthritis (OA) is one of the most prevalent and degenerative diseases with complicated pathology including articular cartilage degradation, subchondral sclerosis and synovitis. Chondrocytes play a crucial role in maintaining cartilage integrity., Methods: Primary chondrocytes were treated with 10 ng/mL IL-1β alone, or pre-treated with 20 μM baicalin for 5 h followed by co-treatment with 20 μM baicalin and 10 ng/mL IL-1β. CCK-8 assay was used to assess cell viability, and cell apoptosis was analyzed by both PI/FITC-Annexin V staining and quantitating apoptosis-related Bcl-2, Bax and cleaved-caspase-3 expression at both protein and mRNA level by Western blotting and qRT-PCR, respectively. Chondrocytes were transfected with miRNA-766-3p mimic and autophagy flux was examined by LC3, Beclin and p62 Western blotting and by Cyto-ID assay to quantify autophagic vacuoles., Results: Baicalin treatment decreased the apoptosis rate and the expressions of pro-apoptotic proteins induced by IL-1β, up-regulated anti-apoptotic Bcl-2 expression, and inhibited the degradation of ECM. Baicalin increased autophagy through up-regulating the autophagy markers Beclin-1 expression and LC3 Ⅱ/LC3 Ⅰ ratio and promoting autophagic flux. Contrarily, autophagy inhibition partially alleviated the beneficial effects of baicalin on ECM synthesis and anti-apoptosis in the chondrocytes treated with L-1β. Furthermore, the differential expressional profiles of miR-766-3p and apoptosis-inducing factor mitochondria-associated 1 (AIFM1) were determined in IL-1β and IL-1β + baicalin-treated chondrocytes, and we confirmed AIFM1 was a target of miR-766-3p. MiR-766-3p overexpression suppressed apoptosis and facilitated autophagy and ECM synthesis in the chondrocytes through decreasing AIFM1. Contrarily, silencing of miR-766-3p inhibited chondrocyte autophagy and promoted apoptosis, and this effect could be reversed by AIFM1 silence., Conclusion: Baicalin protects human OA chondrocytes against IL-1β-induced apoptosis and the degradation of ECM through activating autophagy via miR-766-3p/AIFM1 axis and serves as a potential therapeutic candidate for OA treatment., Competing Interests: The authors declare that they have no competing interests., (© 2020 Li et al.)

When aiming at cell-based therapies in osteoarthritis (OA), proinflammatory conditions mediated by cytokines such as IL-1β need to be considered. In recent studies, the phytoalexin resveratrol (RSV) has exhibited potent anti-inflammatory properties. However, long-term effects on 3D cartilaginous constructs under inflammatory conditions with regard to tissue quality, especially extracellular matrix (ECM) composition, have remained unexplored. Therefore, we employed long-term model cultures for cell-based therapies in an in vitro OA environment and evaluated effects of RSV. Pellet constructs made from expanded porcine articular chondrocytes were cultured with either IL-1β (1-10 ng/ml) or RSV (50 μM) alone, or a cotreatment with both agents. Treatments were applied for 14 days, either directly after pellet formation or after a preculture period of 7 days. Culture with IL-1β (10 ng/ml) decreased pellet size and DNA amount and severely compromised glycosaminoglycan (GAG) and collagen content. Cotreatment with RSV distinctly counteracted the proinflammatory catabolism and led to partial rescue of the ECM composition in both culture systems, with especially strong effects on GAG. Marked MMP13 expression was detected in IL-1β-treated pellets, but none upon RSV cotreatment. Expression of collagen type I was increased upon IL-1β treatment and still observed when adding RSV, whereas collagen type X, indicating hypertrophy, was detected exclusively in pellets treated with RSV alone. In conclusion, RSV can counteract IL-1β-mediated degradation and distinctly improve cartilaginous ECM deposition in 3D long-term inflammatory cultures. Nevertheless, potential hypertrophic effects should be taken into account when considering RSV as cotreatment for articular cartilage repair techniques., (© 2020 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons Ltd.)

Growing evidence has indicated that microRNAs (miRNAs) are modulators of osteoarthritis (OA) development and progression. In this study, we first evaluated the anti-apoptosis and chondroprotective effects of microRNA-675-3p (miR-675-3p) on interleukin-1β (IL-1β)-stimulated human chondrocytes. The overexpression of miR-675-3p inhibited apoptosis and cartilage matrix degradation and promoted cell proliferation in human chondrocytes. Target gene prediction and luciferase reporter assays suggested that G-protein subunit γ 5 (GNG5) may be the target gene of miR-675-3p. The overexpression of miR-675-3p inhibited IL-1β-stimulated chondrocyte apoptosis, and this effect was reversed by the overexpression of GNG5. Finally, we used bioinformatic tools and biological methods to show that the long noncoding RNA X-inactive specific transcript (lncRNA XIST) could bind to miR-675-3p, which affects the expression of GNG5 mRNA. Our findings may substantiate miR-675-3p as a new treatment for OA., Competing Interests: Declaration of competing interest The authors have declared no conflicts of interest., (Copyright © 2020 Elsevier Inc. All rights reserved.)

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.

Osteoarthritis (OA) is characterized by apoptosis of chondrocytes and an imbalance of extracellular matrix (ECM) synthesis and catabolism. Emerging evidence has demonstrated that miRNAs are involved in OA pathologies, but the role of miR-296-5p in OA remains unclear. The present study proposes to reveal the functions and mechanisms of miR-296-5p in a cell model of OA. In this study, human chondrocytes were treated with 5 ml interleukin-1 beta (IL-1β) to induce apoptosis and cartilage degradation. Our results showed that miR-296-5p was downregulated in chondrocytes stimulated with IL-1β. Overexpressed miR-296-5p enhanced cell proliferation and inhibited apoptosis and matrix degrading enzyme expression in response to IL-1β stimulation, and knockdown of miR-296-5p showed the opposite effect. Further, we found that miR-296-5p directly targeted the 3'-untranslated region (3'-UTR) of TGF-β1 mRNA, and miR-296-5p inactivated the TGF-β1/CTGF/p38MAPK signaling pathway. Overexpression of TGF-β1 alleviated the inhibition of miR-296-5p on chondrocyte apoptosis and cartilage degradation. In conclusion, miR-296-5p inhibited the progression of OA through the CTGF/p38MAPK pathway by directly targeting TGF-β1.

Introduction: Estrogen receptor α (ERα) plays important roles in the etiology of osteoarthritis (OA), in which cartilage degradation and cellular inflammation are involved. MiR-203 is reported to direct target ERα, but its roles in chondrocytes remain uncovered., Methods: In this study, ELISA showed that the level of estrogen hormone in the serum of postmenopausal OA patients was significantly lower than the one in patients without OA. RT-PCR revealed that the expression level of miR-203 was significantly up-regulated in the OA patients. Furthermore, western blotting demonstrated the lower expression levels of aggrecan, Col2A1, and ERα in the isolated articular cartilage tissues of OA patients. To decipher the association between ERα and miR-203 in the pathogenesis of OA, IL-1β stimulated cultured chondrocyte cell model was established to measure the cell viability, cellular inflammation, cell injury, as well as cartilage degradation with miR-203 inhibitor and ERα., Results: The results showed that IL-1β stimulation induced the expression of miR-203, which promoted cellular inflammation and cell injury, and caused down-regulation of aggrecan and Col2A1. Luciferase assay indicated the direct binding between miR-203 and ERα, and ERα-specific SiRNA inversed the protective role of miR-203 inhibitor in the progression of OA in the cell system., Conclusions: MiR-203 is critical in the onset and progression of OA, at least in part, caused by estrogen deficiency and ERα instability in OA patients, providing a novel therapeutic target for the treatment of OA.

Background: microRNA (miR)-mediated post-transcriptional repression has been reported in the process of chondrocyte dysfunction. The present study aimed to investigate the molecular mechanisms underlying in oleanolic acid (OLA)-prevented interleukin (IL)-1β-induced chondrocyte dysfunction via the miR-148-3p/fibroblast growth factor-2 (FGF-2) signaling pathway., Methods: Candidate miRs were filtrated using miR microarray assays in chondrocytes with or without IL-1β stimulation. Gene expression of candidate miRs and protein expression of FGF2 were analyzed using a quantitative reverse transcriptase-polymerase chain reaction and western blotting, respectively. Cell growth was evaluated using cell counting kit-8 assays. Cell apoptosis was detected using Annexin V-fluorescein isothiocyanate double staining., Results: Treatment with OLA counteracted IL-1β-evoked chondrocyte growth inhibition, apoptosis, caspase3 production, and release of malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine. Additionally, FGF2 protein expression levels elevated by IL-1β were down-regulated by OLA and transfection with miR-148-3p mimics. IL-1β-induced down-regulation of miR-148-3p in chondrocytes was evaluated by OLA administration. Bioinformatics algorithms and experimental measurements indicated that FGF2 might be a direct target of miR-148-3p. miR-148-3p mimics exhibited equal authenticity of OLA to protect against IL-1β-induced chondrocyte dysfunction., Conclusions: Our present findings highlight a protective effect of OLA on IL-1β-induced chondrocyte dysfunction, and a novel signal cascade comprising the miR-148-3p/FGF2 signaling pathway might be a potential therapeutic target of OLA with respect to preventing the progression of osteoarthritis., (© 2020 John Wiley & Sons, Ltd.)

Osteoarthritis (OA) is a clinical disease which seriously affects the quality of life of sufferers. Although the pathogenesis of OA has not been fully unraveled, it is may be due to increased levels of pro-inflammatory cytokines, activation of inflammation-related signaling pathways, and degradation of extracellular matrix. Osteoarthritis is characterized by chronic joint pain, swelling, stiffness, limited movement or joint deformity, all of which seriously affect the quality of life and health of the affected individuals. Myroside (Myr) is a polyphenolic hydroxyflavone glycoside extracted from the fruits, bark and leaves of myroside and other natural plants. It has many pharmacological properties, especially anti-inflammatory effects. In the present study, primary chondrocytes of IL-1β rats were used to simulate pathological environment of chondrocytes in OA, and to explore the effect of Myr on chondrocytes. It was found that Myr improved the viability and proliferation of chondrocytes, and also inhibited apoptosis in these cells. Moreover, Myr reduced the expressions of inflammatory factors, and inhibited inflammatory reactions in chondrocytes. These findings provide good experimental basis for the clinical application of Myr in the prevention and treatment of progressive degeneration of cartilage in OA.

Chondrocyte apoptosis and extracellular matrix (ECM) degeneration have been implicated in the pathogenesis of osteoarthritis (OA). Based on previously reported microarray analysis, HRAS (Harvey rat sarcoma viral oncogene homolog), a member of the RAS protein family, was chosen as a potential regulator of OA chondrocyte apoptosis and ECM degradation. HRAS expression was downregulated in OA tissues, particularly in mild-OA tissues. HRAS overexpression partially attenuated IL-1β-induced OA chondrocyte apoptosis and ECM degradation. Similar to HRAS, the long non-coding RNA LINC00623 was downregulated in OA tissues. LINC00623 knockdown enhanced IL-1β-induced OA chondrocyte apoptosis and ECM degradation, which could be partially reversed by HRAS overexpression. It has been reported that lncRNAs act as ceRNAs of miRNAs to exert their function. Herein, miR-101 was predicted to bind to both LINC00623 and HRAS, which was further confirmed by luciferase reporter and RIP assays. LINC00623 competed with HRAS for miR-101 binding, therefore reducing the inhibitory effect of miR-101 on HRAS expression. More importantly, the effect of LINC00623 was partially eliminated by miR-101 inhibition. Overall, the LINC00623/miR-101/HRAS axis modulates OA chondrocyte apoptosis, senescence and ECM degradation through MAPK signaling, which might play a critical role in OA development.

Osteoarthritis (OA) is a degenerative joint disease associated with inflammatory response. Tripartite motif 8 (TRIM8) is a member of TRIM family that has been found to regulate inflammation. The present study was aimed to evaluate the role of TRIM8 in OA chondrocytes. Our results showed that TRIM8 expression was significantly increased in interleukin 1 beta (IL-1β)-stimulated OA chondrocytes. To knock down the TRIM8 expression in chondrocytes, the chondrocytes were transfected with si-TRIM8. Knockdown of TRIM8 attenuated IL-1β-induced production of inflammatory mediators including nitric oxide and prostaglandin E 2 . The increased expression levels of inducible nitric oxide synthase and cyclooxygenase-2 in IL-1β-induced chondrocytes were suppressed by TRIM8 knockdown. The IL-1β-induced production of proinflammatory cytokines including TNF-α and IL-6 was significantly decreased after transfection with si-TRIM8. Besides, knockdown of TRIM8 mitigated the IL-1β-induced decrease in aggrecan and collagen-II proteins expression and increase in matrix-degrading enzymes in chondrocytes. Furthermore, TRIM8 knockdown prevented IL-1β-induced nuclear factor kappa B (NF-κB) activation in chondrocytes. Taken together, these findings indicated that knockdown of TRIM8 attenuates IL-1β-induced inflammatory response in OA chondrocytes through the inactivation of NF-κB pathway. Thus, targeting TRIM8 might provide therapeutic treatment for OA.

Osteoarthritis (OA) is a common joint disease characterized by the progressive degeneration of articular cartilage with no effective treatment methods available. Cartilage degeneration is closely related to an anabolic and catabolic imbalance in chondrocytes, and accumulating evidence has revealed that autophagy is a crucial protective mechanism that maintains the balance of anabolic and catabolic activities. Therefore, studies aiming to identify additional genes that regulate autophagy as a promising therapeutic strategy for OA are needed. In this study, we analyzed the GSE113825 datasets from Gene Expression Omnibus and validated that serum- and glucocorticoid-regulated kinase 1 (SGK1) was upregulated in OA cartilage. Based on the results from loss-of-function studies, SGK1 silencing promoted the deposition of glycosaminoglycans in interleukin 1 beta (IL-1β)-treated chondrocytes, and significantly alleviated IL-1β-induced downregulation of Collagen II and Aggrecan, as well as the upregulation of a disintegrin and metalloproteinase with thrombospondin motifs 5 and matrix metalloproteinase-13. Furthermore, SGK1 knockdown reversed the IL-1β-induced chondrocyte anabolic and catabolic imbalance by activating autophagy. Moreover, SGK1 directly bound to forkhead box protein O1 (FoxO1) and increased its phosphorylation, which in turn resulted in its translocation from the nucleus. The decreased FoxO1 levels led to a decrease in LC3-I/LC3-II conversion and Beclin-1 levels, subsequently inhibiting autophagosome formation and increasing P62 levels, thus indicating a downregulation of autophagy. Taken together, we identified a critical role of SGK1 in the IL-1β-induced chondrocyte anabolic and catabolic imbalance, which may represent a potential novel therapeutic target for OA., (© 2019 Federation of European Biochemical Societies.)

Osteoarthritis (OA), a type of joint diseases, could result in breakdown of joint cartilage and underlying bone. Accumulating evidences suggested that long non-coding RNAs play important roles in OA progression. However, the underlying mechanism of H19 in OA is still not fully explored. The expression levels of H19 and miR-106a-5p in OA samples from patients or cultured chondrocytes were examined by quantitative real time polymerase chain reaction. Cell proliferation and apoptosis were analysed by MTT assay and flow cytometry, respectively. Western blotting was employed to detect the expression levels of PCNA, CyclinD1, Caspase 3 and Cleaved Caspase 3. StarBase database, luciferase assay and RNA immunoprecipitation were introduced to confirm the relationship between H19 and miR-106a-5p. The correlation of H19 and miR-106a-5p was analysed by Spearman rank analysis. H19 expression was upregulated, while miR-106a-5p level was downregulated in OA samples and IL-1b-treated chondrocytes. H19 overexpression inhibited the proliferation and induced apoptosis in IL-1b-treated chondrocytes, while H19 knockdown induced the opposite effect. Luciferase and RIP assay demonstrated that miR-106a-5p was a direct target of H19. miR-106a-5p overexpression led to proliferation promotion and apoptosis inhibition in chondrocytes treated by IL-1β and it reversed the effect of H19 addition. We conclude that H19 could regulate proliferation and apoptosis of chondrocytes treated by IL-1β in OA via sponging miR-106a-5p.

Osteoarthritis (OA) is one of the most characterized joint diseases associated with chondrocyte apoptosis. Juglanin has been reported to have anti-inflammation activity. This study aimed to evaluate the protective anti-inflammatory effects of juglanin in human OA chondrocytes. Human OA chondrocytes were pretreated with juglanin (10, 20 and 40 μM) for 2 h and subsequently stimulated with IL-1β for 24 h. Nitric oxide (NO) production was determined using the Griess method and prostaglandin E2 (PGE2), matrix metalloproteinase-3, -9 and -13 (MMP-3, MMP-9 and MMP-13), TNF-α, and IL-6 were assessed using ELISA. The expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), a disintegrin and metalloproteinase with thrombospondin motifs-4 and -5 (ADAMTS-4 and ADAMTS-5) were detected by qRT-PCR and western blot analysis. NF-κB signalling molecules were detected by western blot analysis. The results showed that juglanin dose-dependently suppressed PGE2, NO, MMP-1, MMP3, MMP13, TNF-α and IL-6 production induced by IL-1β. The expression of COX-2, iNOS, ADAMTS-4 and ADAMTS-5 induced by IL-1β were also suppressed by juglanin pretreatment. Western blot analysis showed that juglanin suppressed IL-1β-induced NF-κB activation. Taken together, we found that juglanin inhibits IL-1β-induced inflammation through the regulation of NF-κB signalling. Juglanin might be used as a therapeutic agent for treating OA.

Background: Lycium barbarum polysaccharide (LBP) is a promising therapeutic drug in inflammation-related injuries, nevertheless the mechanism of LBP's action is still elusive. The study is to explore the effect of LBP on IL-1β-evoked ATDC5 cell inflammatory injury. Methods: ATDC5 cells were administrated with 10 ng/mL interleukin (IL)-1β to establish an in vitro model of cartilage damage. After management, cell viability was tested through CCK8 assay. The pro-inflammatory cytokines and cyclooxygenase (Cox)-2 were assessed through ELISA, western blot and qRT-PCR. MiR-124 expression in ATDC5 cells was silenced by transfecting with miR-124 inhibitor, and the pro-inflammatory cytokines and Cox-2 were re-assessed. NF-κB and JNK pathways were measured through western blot. Results: IL-1β stimulation accelerated the release of IL-1β, IL-6 and TNF-α, elevated Cox-2 expression. LBP significantly eased IL-1β-induced inflammation. MiR-124 expression was observed to enhance by LBP, and the impacts of LBP on ATDC5 cells were lightened via transfection with miR-124 inhibitor. NF-κB and JNK pathways were activated after IL-1β stimulation, nevertheless were inactivated by LBP administration. Besides, LBP-evoked the repression of NF-κB and JNK pathways were overturned by miR-124 inhibitor. Conclusions: Our study suggests that LBP protects ATDC5 cells from IL-1β-evoked injury through up-regulating miR-124 via blocking NF-κB and JNK pathways.

Osteoarthritis (OA) is a common joint disease for which a safe and reliable treatment has yet to be developed. Here, we demonstrated the potential benefit of treatment with paeonol, a derivative of Paeonia suffruticosa , in the treatment and prevention of OA. Chondrogenic cell line ATDC5 cells were cultured with IL-1β and the effects of paeonol were assessed through qRT-PCR, western blot analysis, MTT, ELISA, and NF-κB luciferase reporter gene assay. Our findings demonstrate a novel ability of paeonol to inhibit numerous factors of OA, including expressions of IL-6, TNF-α, NOX2, PTGS2, NUCB2/nesfatin-1, ICAM-1, VCAM-1, MMP-3/13, degradation of type II collagen, and NF-κB activation through the rescue of IκBα. Additionally, we assessed the effects of paeonol on cell viability to confirm its safety. These findings implicate a valuable potential role of paeonol in the treatment and prevention of OA.