Inflammation In Chondrocytes Research Articles

Amelioration of Osteoarthritis via Tetrahedral Framework Nucleic Acids Delivering Microrna‐124 for Cartilage Regeneration

AbstractMicroRNAs (miRNAs) regulate several physiological and pathological processes involved in various diseases, including osteoarthritis (OA). OA is the most common global musculoskeletal disorder, characterized by the irreversible progressive destruction of articular cartilage. Supplementation with exogenous miRNAs may represent a promising therapeutic OA treatment, with miRNA‐124 (miR‐124) being a prime candidate for its anti‐inflammatory ability; however, an effective drug delivery system is urgently required to enhance miR‐124 stability and capacity to enter chondrocytes. To this end, tetrahedral framework nucleic acids’ (tFNAs) self‐assembled 3D DNA nanostructures possess superior inherent biocompatibility, versatile functionality, unsurpassed editability, and strong cellular internalization ability. In this study, tFNAs carrying one or three miR‐124 (T‐miR1 or T‐miR3) are successfully synthesized. T‐miR3 is largely absorbed via induced inflammatory chondrocytes by IL‐1β. With reactive oxygen species’ scavenging ability and inflammation‐suppressive miR‐124 release behavior, T‐miR3 efficiently protects chondrocytes against IL‐1β injury in vitro. Additionally, T‐miR3 effectively prevents OA progression by inhibiting chondrocyte apoptosis, smoothing cartilage surfaces, suppressing extracellular matrix degradation, and increasing synovial thickness, effectively protecting in vivo articular cartilage, and illustrating the therapeutic ability of T‐miR3 in OA treatment. This study provides experimental evidence and novel therapeutic strategies for OA treatment in the clinical setting.

Epigenetic regulatory mechanism of ADAMTS12 expression in osteoarthritis

BackgroundOsteoarthritis (OA) is a degenerative joint disease with lacking effective prevention targets. A disintegrin and metalloproteinase with thrombospondin motifs 12 (ADAMTS12) is a member of the ADAMTS family and is upregulated in OA pathologic tissues with no fully understood molecular mechanisms.MethodsThe anterior cruciate ligament transection (ACL-T) method was used to establish rat OA models, and interleukin-1 beta (IL-1β) was administered to induce rat chondrocyte inflammation. Cartilage damage was analyzed via hematoxylin-eosin, Periodic Acid-Schiff, safranin O-fast green, Osteoarthritis Research Society International score, and micro-computed tomography assays. Chondrocyte apoptosis was detected by flow cytometry and TdT dUTP nick-end labeling. Signal transducer and activator of transcription 1 (STAT1), ADAMTS12, and methyltransferase-like 3 (METTL3) levels were detected by immunohistochemistry, quantitative polymerase chain reaction (qPCR), western blot, or immunofluorescence assay. The binding ability was confirmed by chromatin immunoprecipitation-qPCR, electromobility shift assay, dual-luciferase reporter, or RNA immunoprecipitation (RIP) assay. The methylation level of STAT1 was analyzed by MeRIP-qPCR assay. STAT1 stability was investigated by actinomycin D assay.ResultsThe STAT1 and ADAMTS12 expressions were significantly increased in the human and rat samples of cartilage injury, as well as in IL-1β-treated rat chondrocytes. STAT1 is bound to the promoter region of ADAMTS12 to activate its transcription. METTL3/ Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) mediated N6-methyladenosine modification of STAT1 promoted STAT1 mRNA stability, resulting in increased expression. ADAMTS12 expression was reduced and the IL-1β-induced inflammatory chondrocyte injury was attenuated by silencing METTL3. Additionally, knocking down METTL3 in ACL-T-produced OA rats reduced ADAMTS12 expression in their cartilage tissues, thereby alleviating cartilage damage.ConclusionMETTL3/IGF2BP2 axis increases STAT1 stability and expression to promote OA progression by up-regulating ADAMTS12 expression.

CircTBX5 knockdown modulates the miR-558/MyD88 axis to alleviate IL-1β-induced inflammation, apoptosis and extracellular matrix degradation in chondrocytes via inactivating the NF-κB signaling

BackgroundIt has been widely shared that the dysregulation of circular RNA (circRNA) may contribute to the progression of osteoarthritis (OA). OA is characterized by persistent chondrocyte injury. We aimed to clarify the role of circTBX5 in IL-1β-induced chondrocyte injury.MethodsThe expression of circTBX5, miR-558 and MyD88 mRNA was measured using quantitative real-time PCR (qPCR). Cell viability, proliferation and apoptosis were assessed by CCK-8, EdU or flow cytometry assay. The protein levels of extracellular matrix (ECM)-associated markers, MyD88, IkBα, p65 and phosphorylated IkBα were measured by western blot. The release of inflammatory factors was assessed by ELISA. The targets of circTBX5 were screened by RIP and pull-down assay. The putative binding between miR-558 and circTBX5 or MyD88 was validated by dual-luciferase reporter assay.ResultsCircTBX5 and MyD88 were enhanced, while miR-558 was downregulated in OA cartilage tissues and IL-1β-treated C28/I2 cells. IL-1β induced C28/I2 cell injury by impairing cell viability and proliferation and promoting cell apoptosis, ECM degradation and inflammatory response, while circTBX5 knockdown alleviated IL-1β induced injury. CircTBX5 bound to miR-558 to regulate IL-1β induced cell injury. In addition, MyD88 was a target of miR-558, and circTBX5 targeted miR-558 to positively regulate MyD88 expression. MiR-558 enrichment attenuated IL-1β induced injury by sequestering MyD88 expression. Moreover, circTBX5 knockdown weakened the activity of NF-κB signaling, while miR-558 inhibition or MyD88 overexpression recovered the activity of NF-κB signaling.ConclusionCircTBX5 knockdown modulated the miR-558/MyD88 axis to alleviate IL-1β induced chondrocyte apoptosis, ECM degradation and inflammation via inactivating the NF-кB signaling pathway.

Protective effects of hsa_circ_0072568 on interleukin‑1β‑stimulated human chondrocytes are mediated via the miR‑382‑5p/TOP1 axis.

Circular RNA (circRNA) dysregulation has been linked to osteoarthritis (OA). The present study investigated the involvement of hsa_circ_0072568 (circ0072568) in OA. The expression of circ0072568 was detected in OA tissues and interleukin (IL)-1β-stimulated human chondrocytes. After performing dual-luciferase reporter and RNA immunoprecipitation assays, MTT, enzyme-linked immunosorbent assay and western blot analysis were used to assess the functions of circ0072568 in IL-1β-induced inflammation in chondrocytes in vitro. Circ0072568 was inhibited in OA tissues and the cell model in vitro. Circ0072568 overexpression protected the chondrocytes against IL-1β-induced inflammation and extracellular matrix (ECM) breakdown. Circ0072568 directly attached to microRNA (miR)-382-5p and enhanced the production of topoisomerase 1 (TOP1). Furthermore, miR-382-5p overexpression or TOP1 knockdown attenuated the effects of circ0072568 in IL-1β-stimulated human chondrocytes. On the whole, the present study demonstrates that the Circ0072568/miR-382-5p/TOP1 axis is involved in inflammation and ECM degradation in OA. These findings may contribute to the development of potential therapeutic strategies for OA.

Gremlin-1 promotes IL-1β-stimulated chondrocyte inflammation and extracellular matrix degradation via activation of the MAPK signaling pathway.

The role and mechanism of Gremlin-1 in osteoarthritis (OA) were expected to be probed in this study. Firstly, an in vitro OA model was constructed by stimulating human chondrocyte cell line CHON-001 with IL-1β. Next, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) were utilized for assessing the effect of IL-1β with different concentrations (5, 10, and 20 ng/mL) on the activity and Gremlin-1 messenger RNA of CHON-001 cells, respectively. Besides, the influence of knocking down/over-expressing Gremlin-1 on the inflammatory factors (IL-6, TNF-α, IL-18 and PGE2), oxidative stress-related substances (malondialdehyde [MDA]; superoxide dismutase [SOD]; lactate dehydrogenase [LDH]), extracellular matrix (ECM) degradation-related proteins, and mitogen-activated protein kinase (MAPK) pathway proteins in IL-1β-stimulated CHON-001 cells were tested by enzyme-linked immunosorbent assay, related kits, qRT-PCR, and western blot, respectively. IL-1β inhibited CHON-001 cell proliferation and upregulated Gremlin-1 expression in a concentration-dependent manner. Overexpression of Gremlin-1 increased the IL-6, TNF-α, IL-18, PGE2, and MDA levels, enhanced the LDH activity, and decreased the SOD activity in IL-1β-induced CHON-001 cells; while the effect of Gremlin-1 knockdown on the above factors was in contrast with that of the overexpression. Furthermore, overexpression of Gremlin-1 upregulated protein expression of matrix metalloproteinase (MMP)-3, MMP-13, and ADAMTS4 while downregulated protein expression of collagen III, aggrecan, and SOX-9 in IL-1β-stimulated CHON-001 cells. Besides, overexpression of Gremlin-1 increased the p-p38/p38 value while decreased the p-JNK/JNK value in L-1β-stimulated CHON-001 cells; however, knockdown of Gremlin-1 reversed the above results. Gremlin-1 may promote IL-1β-stimulated CHON-001 cell inflammation and ECM degradation by activating the MAPK signaling pathway.

Retracted: Sappanone A Alleviated IL-1β-Induced Inflammation in OA Chondrocytes through Modulating the NF-κB and Nrf2/HO-1 Pathways.

[This retracts the article DOI: 10.1155/2022/2380879.].

An Injectable Sustained Release Hydrogel of Hyaluronic Acid Loaded with β‐Ecdysterone Ameliorates Cartilage Damage in Osteoarthritis via Activating Autophagy

AbstractThis study uses the knee Osteoarthritis (OA) rat (constructed by the anterior cruciate ligament transection) and the inflammatory chondrocyte (constructed by 20 ng mL−1 tumor necrosis factor‐α (TNF‐α)) to study the improvement effect of injectable β‐ecdysterone (β‐Ec) hydrogel consisting of poly (D, L‐lactic‐co‐glycolic acid)‐hyaluronate (HA‐β‐Ec‐Gel) on cartilage damage. The results show that the HA‐β‐Ec‐Gel improves the three‐dimensional of bone structure. The HA‐β‐Ec‐Gel treatment improves cartilage tissue injury of OA rats. It advances the levels of autophagic factor Beclin1 (Beclin1) and microtubule–associated protein 1 light chain 3 (LC3) in cartilage tissue. The lysyl oxidase like 3 (LOXL3), ras homologue enriched (Rheb), phosphorylated (p)‐V–akt murine thymoma viral oncogene homolog (AKT)/AKT, and p‐mechanistic target of rapamycin (mTOR)/mTOR signal expression are inhibited by HA‐β‐Ec‐Gel intervention. In inflammatory chondrocytes, β‐Ec improves the cell viability, autophagosome numbers, and Beclin1 and LC3 II/I levels, also inhibits apoptotic rate, LOXL3 and Rheb expression levels, and the AKT/mTOR pathway. The 3‐methyladenine addition reverses these effects of β‐Ec. The Rheb or LOXL3 knockdown chondrocytes aren't sensitive to TNF–α‐induced damage. Their autophagy level is high. This study reveals the improvement effects of injectable HA‐β‐Ec‐Gel on OA, which provides a scientific basis and new direction for the development of OA treatment strategies.

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

BackgroundOsteoarthritis is an age-related disease that currently faces a lack of symptomatic treatment. Inflammation, which is mainly sustained by pro-inflammatory cytokines such as IL-1b, TNF, and IL-6, plays an important role in osteoarthritis progression. In this context, pro-inflammatory cytokines are widely used to mimic the inflammatory component of osteoarthritis in vitro. However, the therapeutic failures of clinical trials evaluating anti-cytokines drugs highlight the lack of overall understanding of the effects of these cytokines on chondrocytes.MethodsHere, we generated a comprehensive transcriptomic and proteomic dataset of osteoarthritic chondrocytes treated with these cytokines to describe their pro-inflammatory signature and compare it to the transcriptome of non-osteoarthritic chondrocytes. Then, the dysregulations highlighted at the molecular level were functionally confirmed by real-time cellular metabolic assays.ResultsWe identified dysregulation of metabolic-related genes in osteoarthritic chondrocytes but not in non-osteoarthritic chondrocytes. A metabolic shift, toward increased glycolysis at the expense of mitochondrial respiration, was specifically confirmed in osteoarthritic chondrocytes treated with IL-1b or TNF.ConclusionThese data show a strong and specific association between inflammation and metabolism in osteoarthritic chondrocytes, which was not found in non-osteoarthritic chondrocytes. This indicates that the link between inflammation and metabolic dysregulation may be exacerbated during chondrocyte damage in osteoarthritis.Ah55iVufqkh9_Bh-mmovkiVideo

LncRNA OIP5-AS1 attenuates the osteoarthritis progression in IL-1β-stimulated chondrocytes.

In view of the association between long noncoding RNA OIP5-AS1 and osteoarthritis (OA) pathology, the corresponding potential mechanism is worthy of exploration. Primary chondrocytes were identified by morphological observation and immunohistochemical staining of collagen II. The association between OIP5-AS1 and miR-338-3p was analyzed by StarBase and dual-luciferase reporter assay. After the expression of OIP5-AS1 or miR-338-3p in interleukin (IL)-1β-stimulated primary chondrocytes and CHON-001 cells was manipulated, cell viability, proliferation, apoptosis rate, apoptosis-related protein (cleaved caspase-9, Bax) expressions, extracellular matrix (ECM) (matrix metalloproteinase (MMP)-3, MMP-13, aggrecan, and collagen II), PI3K/AKT pathway, and mRNA expressions of inflammatory factors (IL-6 and IL-8), OIP5-AS1, and miR-338-3p were determined by cell counting kit-8, EdU, flow cytometry, Western blot, and quantitative reverse transcription-polymerase chain reaction. As a result, the expression of OIP5-AS1 was downregulated in IL-1β-activated chondrocytes, while miR-338-3p was overexpressed. OIP5-AS1 overexpression reversed the effects of IL-1β on viability, proliferation, apoptosis, ECM degradation, and inflammation in chondrocytes. However, OIP5-AS1 knockdown exhibited opposite effects. Interestingly, the effects of OIP5-AS1 overexpression were partially offset by miR-338-3p overexpression. Furthermore, OIP5-AS1 overexpression blocked the PI3K/AKT pathway by modulating miR-338-3p expression. In sum, OIP5-AS1 promotes viability and proliferation, and inhibits apoptosis and ECM degradation in IL-1β-activated chondrocytes by targeting miR-338-3p through blocking the PI3K/AKT pathway, indicating an attractive strategy for OA treatment.

Endocan Knockdown Down-Regulates the Expression of Angiogenesis-Associated Genes in Il-1ß Activated Chondrocytes.

Endocan is a small soluble proteoglycan (PG) known to be involved in inflammation and angiogenesis. Increased endocan expression was found in the synovia of arthritic patients and chondrocytes stimulated with IL-1ß. Considering these findings, we aimed to investigate the effects of endocan knockdown on the modulation of pro-angiogenic molecules expression in a model of IL-1ß-induced inflammation in human articular chondrocytes. Endocan, VEGF-A, MMP-9, MMP-13, and VEGFR-2 expression was measured in both normal and endocan knockdown chondrocytes stimulated with IL-1ß. VEGFR-2 and NF-kB activation were also measured. Results have shown that endocan, VEGF-A, VEGFR-2, MMP-9, and MMP-13 were significantly up-regulated during IL-1ß-induced inflammation; interestingly, the expression of such pro-angiogenic molecules and NF-kB activation were significantly reduced by endocan knockdown. These data support the hypothesis that endocan released by activated chondrocytes may be involved in the mechanisms that stimulate cell migration and invasion, as well as angiogenesis, in the pannus of arthritic joints.

Suramin ameliorates osteoarthritis by acting on the Nrf2/HO-1 and NF-κB signaling pathways in chondrocytes and promoting M2 polarization in macrophages

Osteoarthritis (OA)—the most prevalent of arthritis diseases—is a complicated pathogenesis caused by cartilage degeneration and synovial inflammation. Suramin has been reported to enhance chondrogenic differentiation. However, the therapeutic effect of suramin on OA-induced cartilage destruction has remained unclear. Suramin is an anti-parasitic drug that has potent anti-purinergic properties. This study investigated the protective effects and underlying mechanisms of suramin on articular cartilage degradation using an in vitro study and mice model with post-traumatic OA. We found that suramin markedly suppressed the IL-1β increased expression of matrix destruction proteases—such as ADAMT4, ADAMTS5, MMP3, MMP13, and inflammatory mediators—including the iNOS, COX2, TNFα, and IL-1β; while greatly enhancing the synthesis of cartilage anabolic factors—such as COL2A1, Aggrecan and SOX9 in IL-1β-induced porcine chondrocytes. In vivo experiments showed that intra-articular injection of suramin ameliorated cartilage degeneration and inhibited synovial inflammation in an anterior cruciate ligament transection (ACLT)-induced OA mouse model. In mechanistic studies, we found that exogenous supplementation of suramin can activate Nrf2, and accordingly inhibit the nuclear factor kappa-light-chain-enhancer of activated B cells (NF- κB) and mitogen-activated protein kinase (MAPK) pathways, thereby alleviating the inflammation and ECM degeneration of chondrocytes stimulated by IL-1β. In addition, suramin also repolarized M1 macrophages to the M2 phenotype, further reducing the apoptosis of chondrocytes. Collectively, the results of the study suggests that suramin is a potential drugs which could serve as a facilitating drug for the application of OA therapy toward clinical treatment.

Orientin inhibits inflammation in chondrocytes and attenuates osteoarthritis through Nrf2/NF-κB and SIRT6/NF-κB pathway.

Osteoarthritis (OA) is the most common form of degenerative joint disease. and chondrocyte inflammation plays an important role in OA development. The natural flavonoid compound Orientin (Orientin) has anti-inflammatory bioactive properties in the treatment of various diseases. Studies have not explored whether Orientin modulates OA progression. In our study, we researched the anti-osteoarthritis effects of Orientin, as well as the potential mechanisms that underlie its action. Effects of Orientin on OA were detected in chondrocytes and OA mouse model. Effects of Orientin on murine chondrocytes treated with interleukin-1β (IL-1β) were evaluated using qPCR, western blot analysis, ELISA and immunofluorescent staining in vitro. In vivo, We established a standard OA model by performing the destabilized medial meniscus (DMM) surgery on C57BL/6 mice, and assessed healing effect of Orientin by X-ray imaging, histopathological analysis, immunohistochemical staining. A significant suppression in IL-1β-mediated pro-inflammatory mediators and the degradation of cartilage extracellular matrix (ECM) was observed in vitro after a treatment with Orientin. In addition, Orientin abrogated DMM surgery induced cartilage degradation in mice. Mechanistic studies showed that Orientin suppressed OA development by downregulating activation of NF-κB by activating Nrf2/HO-1 axis and SIRT6 signaling pathway. The study indicates that Orientin inhibits inflammation of chondrocytes and ECM degradation, which are key contributors to OA progression. Effects of Orientin are mediated through Nrf2/NF-κB and the SIRT6/NF-κB pathways. These results provide evidence that Orientin serves as a potentially viable compound for the treatment of OA. This article is protected by copyright. All rights reserved.

JNK-JUN-NCOA4 axis contributes to chondrocyte ferroptosis and aggravates osteoarthritis via ferritinophagy.

Interruption of iron homeostasis is correlated with cell ferroptosis and degenerative diseases. Nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy has been reported as a vital mechanism to control cellular iron levels, but its impact on osteoarthritis (OA) pathology and the underline mechanism are unknown. Herein we aimed to investigate the role and regulatory mechanism of NCOA4 in chondrocyte ferroptosis and OA pathogenesis. We demonstrated that NCOA4 was highly expressed in cartilage of patients with OA, aged mice, post-traumatic OA mice, and inflammatory chondrocytes. Importantly, Ncoa4 knockdown inhibited IL-1β-induced chondrocyte ferroptosis and extracellular matrix degradation. Contrarily, overexpression of NCOA4 promoted chondrocyte ferroptosis and the delivery of Ncoa4 adeno-associated virus 9 into knee joint of mice aggravated post-traumatic OA. Mechanistic study revealed that NCOA4 was upregulated in a JNK-JUN signaling-dependent manner in which JUN could directly bind to the promoter of Ncoa4 and initial the transcription of Ncoa4. NCOA4 could interact with ferritin and increase autophagic degradation of ferritin and iron levels, which caused chondrocyte ferroptosis and extracellular matrix degradation. In addition, inhibition of JNK-JUN-NCOA4 axis by SP600125, a specific inhibitor of JNK, attenuated development of post-traumatic OA. This work highlights the role of JNK-JUN-NCOA4 axis and ferritinophagy in chondrocyte ferroptosis and OA pathogenesis, suggesting this axis as a potential target for OA treatment.

Inhibition of Leukotriene A4 Hydrolase Suppressed Cartilage Degradation and Synovial Inflammation in a Mouse Model of Experimental Osteoarthritis.

Chronic inflammation plays an important role in the osteoarthritis (OA) pathology but how this influence OA disease progression is unclear. Leukotriene B4 (LTB4) is a potent proinflammatory lipid mediator generated from arachidonic acid through the sequential activities of 5-lipoxygenase, 5-lipoxygenase-activating protein, Leukotriene A4 hydrolase (LTA4H) and its downstream product LTB4. The aim of this study is to investigate the involvement and the potential therapeutic target of the LTB4 pathway in OA disease progression. Both clinical human cartilage samples (n = 7) and mice experimental OA models (n = 6) were used. The levels of LTA4H and leukotriene B4 receptor 1 were first examined using immunostaining in human OA/non-OA cartilage and mice experimental OA models. We also determined whether the LTA4H pathway was associated with cartilage degeneration and synovitis inflammation in OA mice models and human articular chondrocytes. We found that both LTA4H and LTB4 receptor (BLT1) were highly expressed in human and mice OA cartilage. Inhibition of LTA4H suppressed cartilage degeneration and synovitis in OA mice model. Furthermore, inhibition of LTA4H promoted cartilage regeneration by upregulating chondrogenic genes expression such as aggrecan (ACAN), collagen 2A1 (COL2A1), and SRY-Box transcription factor 9 (SOX9). Our results indicate that the LTA4H pathway is a crucial regulator of OA pathogenesis and suggest that LTA4H could be a therapeutic target in combat OA.

Tannic acid, an IL-1β-direct binding compound, ameliorates IL-1β-induced inflammation and cartilage degradation by hindering IL-1β-IL-1R1 interaction.

Interleukin-1β (IL-1β) is one of the most potent pro-inflammatory cytokines implicated in a wide range of autoinflammatory, autoimmune, infectious, and degenerative diseases. Therefore, many researchers have focused on developing therapeutic molecules that inhibit IL-1β-IL-1 receptor 1 (IL-1R1) interaction for the treatment of IL-1-related diseases. Among IL-1-related diseases, osteoarthritis (OA), is characterized by progressive cartilage destruction, chondrocyte inflammation, and extracellular matrix (ECM) degradation. Tannic acid (TA) has been proposed to have multiple beneficial effects, including anti-inflammatory, anti-oxidant, and anti-tumor activities. However, it is unclear whether TA plays a role in anti-IL-1β activity by blocking IL-1β-IL-1R1 interaction in OA. In this study, we report the anti-IL-1β activity of TA in the progression of OA in both in vitro human OA chondrocytes and in vivo rat OA models. Herein, using-ELISA-based screening, natural compound candidates capable of inhibiting the IL-1β-IL-1R1 interaction were identified. Among selected candidates, TA showed hindering IL-1β-IL-1R1 interaction by direct binding to IL-1β using surface plasmon resonance (SPR) assay. In addition, TA inhibited IL-1β bioactivity in HEK-Blue IL-1-dependent reporter cell line. TA also inhibited IL-1β-induced expression of inducible nitric oxide synthase (NOS2), cyclooxygenase-2 (COX-2), IL-6, tumor necrosis factor-alpha (TNF-α), nitric oxide (NO), and prostaglandin E2 (PGE2) in human OA chondrocytes. Moreover, TA downregulated IL-1β-stimulated matrix metalloproteinase (MMP)3, MMP13, ADAM metallopeptidase with thrombospondin type 1 motif (ADAMTS)4, and ADAMTS5, while upregulating collagen type II (COL2A1) and aggrecan (ACAN). Mechanistically, we confirmed that TA suppressed IL-1β-induced MAPK and NF-κB activation. The protective effects of TA were also observed in a monosodium iodoacetamide (MIA)-induced rat OA model by reducing pain and cartilage degradation and inhibiting IL-1β-mediated inflammation. Collectively, our results provide evidence that TA plays a potential role in OA and IL-1β-related diseases by hindering IL-1β-IL-1R1 interaction and suppressing IL-1β bioactivity.

Dihydrocaffeic acid improves IL-1β-induced inflammation and cartilage degradation via inhibiting NF-κB and MAPK signalling pathways.

Osteoarthritis (OA) is a prevalent joint disorder with inflammatory response and cartilage deterioration as its main features. Dihydrocaffeic acid (DHCA), a bioactive component extracted from natural plant (gynura bicolor), has demonstrated anti-inflammatory properties in various diseases. We aimed to explore the chondroprotective effect of DHCA on OA and its potential mechanism. In vitro, interleukin-1 beta (IL-1β) was used to establish the mice OA chondrocytes. Cell counting kit-8 evaluated chondrocyte viability. Western blotting analyzed the expression levels of collagen II, aggrecan, SOX9, inducible nitric oxide synthase (iNOS), IL-6, matrix metalloproteinases (MMPs: MMP1, MMP3, and MMP13), and signalling molecules associated with nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. Immunofluorescence analysis assessed the expression of aggrecan, collagen II, MMP13, and p-P65. In vivo, a destabilized medial meniscus (DMM) surgery was used to induce mice OA knee joints. After injection of DHCA or a vehicle into the injured joints, histological staining gauged the severity of cartilage damage. DHCA prevented iNOS and IL-6 from being upregulated by IL-1β. Moreover, the IL-1β-induced upregulation of MMPs could be inhibited by DHCA. Additionally, the administration of DHCA counteracted IL-1β-induced downregulation of aggrecan, collagen II, and SOX9. DHCA protected articular cartilage by blocking the NF-κB and MAPK pathways. Furthermore, DHCA mitigated the destruction of articular cartilage in vivo. We present evidence that DHCA alleviates inflammation and cartilage degradation in OA chondrocytes via suppressing the NF-κB and MAPK pathways, indicating that DHCA may be a potential agent for OA treatment.

Cardamonin alleviates chondrocytes inflammation and cartilage degradation of osteoarthritis by inhibiting ferroptosis via p53 pathway.

Osteoarthritis (OA) is a common degenerative joint disease, mainly presented by the deterioration of articular cartilage. Amounts of data demonstrated this deterioration is composed of oxidative stress, pro-inflammation and chondrocyte death events. Ferroptosis is a novel form of cell death that differs from apoptosis and autophagy, recent studies have shown that chondrocyte ferroptosis contributes to the development of osteoarthritis. Cardamonin (CAD) has been demonstrated to possess antioxidant and anti-inflammatory properties in several diseases, whether CAD may influence the OA progression is still obscure. Therefore, we aimed to determine whether CAD alleviates chondrocyte ferroptosis and its effect on OA with potential mechanism. In this study, we found that inflammation, cartilage degradation and ferroptosis induced by interleukin-1β (IL-1β) were significantly alleviated by CAD. Moreover, the administration of the ferroptosis inhibitor, Deferoxamine (DFO) reversed the inflammatory and cartilage degradation effects of IL-1β as well. Chondrocyte mitochondrial morphology and function were alleviated by both CAD and DFO. We found that CAD increased collagen II, p53, SLC7A11 GPX4 expression and decreased MMP13, iNOS, COX2 expression in chondrocytes, further investigation showed that the P53 signaling pathway was involved. In vivo, intra-articular injection of CAD significantly ameliorated cartilage damage in a rat OA model, induced collagen II and SLC7A11 expression by immunohistochemistry. Our study proves that CAD ameliorated OA cartilage degradation by regulating ferroptosis via P53 signaling pathway, suggesting a potential role of CAD in OA treatment.

Apigenin Inhibits the Progression of Osteoarthritis by Mediating Macrophage Polarization.

The overall purpose of this study was to investigate the mechanism of macrophage polarization on chondrocyte injury in osteoarthritis and the protective effect of apigenin on chondrocytes in osteoarthritis. Primary chondrocytes were isolated from the knee cartilage of three-day-old mice, and cells positive for Alsine blue staining and type II collagen immunocytochemical staining were identified and used in followup experiments. Transwell coculture was performed. Chondrocytes were inoculated in the inferior compartment, and macrophages were inoculated in the upper compartment. The experimental groups were the N group, LPS group, and LPS+ apigenin group. The effect of macrophage polarization on chondrocyte inflammation and the protective effect of apigenin on chondrocytes were verified by the drug administration. Real-time quantitative PCR (qPCR) and Western blot were used to detect the expression of RNA and protein. Experimental OA was induced by modified Hulth surgery in mice. Modified Hulth surgery was performed on the mouse's right knee to induce experimental osteoarthritis in mice, with the nonoperative right knee serving as an ipsilateral control. The mice were randomly assigned to three groups (six mice per group): the sham group, the modified Hulth group, and the modified Hulth + apigenin group. Animals were given gavage for four weeks. The protective effect of apigenin on articular cartilage was verified by histological staining and immunohistochemical analysis. Histological staining showed that apigenin had a protective effect on cartilage degeneration induced by modified Hulth surgery. The PCR results showed that apigenin significantly reduced the expression levels of IL-1, IL-6, MMP3, and MMP13 in the articular cartilage of OA mice, and it had a protective effect on articular cartilage. Apigenin reduced the levels of IL-1, IL-6, TNF-α, and IL-12 in macrophages and increased the levels of MG-L1, MG-L2, ARG-1, and IL-10, which can inhibit the M1 polarization of macrophages and promote M2 polarization. In the coculture system, apigenin decreased the protein levels of TRPM7, P-mTOR, BAX, and c-caspase3 in macrophages, while significantly increasing the protein levels of Bcl2. The levels of IL-1, IL-6, MMP13, TNF-α, P38, JNK, and ERK phosphorylation were reduced in chondrocytes. Apigenin alleviates cartilage injury in OA mice induced by modified Hulth. Apigenin inhibits chondrocyte inflammation through the MAPK pathway. Apigenin alleviates macrophage-polarization-induced inflammatory response and chondrocyte apoptosis in the macrophage-chondrocyte coculture system through the TRPM7-mTOR pathway.

E3 Ubiquitin Ligase Constitutive Photomorphogenic 1 Regulates Differentiation and Inflammation via MAPK Signaling Pathway in Rabbit Articular Chondrocytes

Constitutive photomorphogenic 1 (COP1), is an E3 ubiquitin ligase that plays a role in the regulation of various cellular processes including cell growth, differentiation, and survival in mammals. In certain conditions such as overexpression or loss of function, COP1 acts either as an oncogenic protein or as a tumor suppressor by targeting specific proteins for ubiquitination-mediated degradation. However, the precise role of COP1 has not been well studied in primary articular chondrocytes. In this study, we investigated the role of COP1 in chondrocyte differentiation. Western blotting and reverse transcription-polymerase chain reaction analysis demonstrated that COP1 overexpression reduced type II collagen expression, promoted cyclooxygenase 2 (COX-2) expression, and reduced sulfated proteoglycan synthesis, as detected by Alcian blue staining. Upon siRNA treatment, revived type II collagen, sulfated proteoglycan production, and decreased COX-2 expression. Phosphorylation of p38 kinase and ERK-1/-2 signaling pathways was regulated by COP1 upon cDNA and siRNA transfection in chondrocytes. The inhibition of the p38 kinase and ERK-1/-2 signaling pathways with SB203580 and PD98059 ameliorated the expression of type II collagen and COX-2 in transfected chondrocytes, thus suggesting that COP1 regulates differentiation and inflammation in rabbit articular chondrocytes via the p38 kinase and ERK-1/-2 signaling pathway.

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

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