Chondrocyte Extracellular Matrix Degradation Research Articles

DDIT3 aggravates TMJOA cartilage degradation via Nrf2/HO-1/NLRP3-mediated autophagy

ObjectiveDNA damage-inducible transcript 3 (DDIT3), as a downstream transcription factor of endoplasmic reticulum (ER) stress, is reported to regulate chondrogenic differentiation under physiological and pathological state. However, the specific involvement of DDIT3 in the degradation of condylar cartilage of TMJOA is unclarified. DesignThe expression patterns of DDIT3 in condylar cartilage from monosodium iodoacetate (MIA)-induced TMJOA mice were examined to uncover the potential role of DDIT3 in TMJOA. The Ddit3 knockout (Ddit3-/-) mice and their wildtype littermates (Ddit3+/+) were used to clarify the effect of DDIT3 on cartilage degradation. Primary condylar chondrocytes and ATDC5 cells were applied to explore the mechanisms of DDIT3 on autophagy and extracellular matrix (ECM) degradation in chondrocytes. The autophagy inhibitor chloroquine (CQ) was used to determine the effect of DDIT3-inhibited autophagy in vivo. ResultsDDIT3 were highly expressed in condylar cartilage from TMJOA mice. Ddit3 knockout alleviated condylar cartilage degradation and subchondral bone loss, compared with their wildtype littermates. In vitro study demonstrated that DDIT3 exacerbated ECM degradation in chondrocytes induced by TNF-α through inhibiting autophagy. The intraperitoneal injection of CQ further confirmed that Ddit3 knockout alleviated cartilage degradation in TMJOA through activating autophagy in vivo. ConclusionsOur findings identified the crucial role of DDIT3-inhibited autophagy in condylar cartilage degradation during the development of TMJOA.

Intermittent cyclic mechanical compression promotes endplate chondrocytes degeneration by disturbing Nrf2/PINK1 signaling pathway-dependent mitophagy.

An abnormal mechanical load is a pivotal inducer of endplate cartilage degeneration, which subsequently promotes intervertebral disc degeneration. Our previous study indicated that intermittent cyclic mechanical compression (ICMC) promotes endplate chondrocyte degeneration, but the mechanism underlying this effect is unclear. In this study, we investigated PTEN-induced kinase 1(PINK1) dependent mitophagy during ICMC-induced endplate chondrocyte degeneration. Furthermore, we determined whether NF-E2-related factor 2 (Nrf2) activation correlated with PINK1-dependent mitophagy regulation and increased oxidation resistance of endplate chondrocytes under ICMC application. First, we generated a mechanical compression-induced endplate chondrocyte degeneration model in vitro and in vivo. ICMC was found to promote endplate chondrocyte extracellular matrix degradation. PINK1-mediated mitophagy was suppressed in the ICMC-stimulated endplate chondrocytes, while increased mitochondrial reactive oxygen species generation suggested that mitophagy is involved in the protective effect of mechanical strain on endplate chondrocytes. Moreover, Nrf2 expression, interaction with Kelch-like ECH-associated protein (Keap1), and nuclear translocation were inhibited by ICMC. Nrf2 overexpression inhibited reactive oxygen species production and reversed ICMC-induced endplate chondrocyte degeneration. Transfection with PINK1 shRNA abolished this effect and partially blocked Nrf2-induced mitophagy. Our findings suggested that ICMC could inhibit the Nrf2/PINK1 signaling pathway to reduce the mitophagy levels which significantly promote oxidative stress and thereby endplate chondrocyte degeneration. Therapeutic regulation of the Nrf2/PINK1 signaling pathway may be an efficient anabolic strategy for inhibiting this process.

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.

Circular RNA CircDHRS3 Aggravates IL-1β-induced ECM Degradation, Apoptosis, and Inflammatory Response via Mediating MECP2 Expression.

Previous studies have reported that circular RNA hsa_circ_0010024 (circDHRS3), microRNA (miR)-193a-3p, and Methyl CpG binding protein 2 (MECP2) are unconventionally expressed in osteoarthritis (OA) cartilage samples. However, the regulatory mechanisms among circDHRS3, miR-193a-3p, and MECP2 in OA pathogenesis are unclear. Changes of circDHRS3, miR-193a-3p, and MECP2 mRNA were detected by qRT-PCR. Several protein levels were evaluated using western blotting. Cell proliferation was analyzed by 5-Ethynyl-2'-deoxyuridine (EdU) and cell counting assays. Cell apoptosis was determined by flow cytometry assay. Detection of pro-inflammatory cytokines was conducted using ELISA. The relationship between circDHRS3 or MECP2 and miR-193a-3p was validated by dual-luciferase reporter assay. We verified that circDHRS3 and MECP2 were overexpressed in OA cartilage samples, whereas miR-193a-3p was downregulated. CircDHRS3 silencing weakened IL-1β-induced chondrocyte cartilage extracellular matrix (ECM) degradation, apoptosis, and inflammatory response. CircDHRS3 adsorbed miR-193a-3p to modulate MECP2 expression. Also, silencing of miR-193a-3p impaired circDHRS3 silencing-mediated suppression on IL-1β-induced chondrocyte injury. Also, MECP2 overexpression alleviated miR-193a-3p mimic-mediated inhibition on IL-1β-prompted chondrocyte injury. CircDHRS3 silencing reduced MECP2 expression via sponging miR-193a-3p, thereby weakening IL-1β-induced chondrocyte ECM degradation, apoptosis, and inflammatory response.

Methyl gallate prevents oxidative stress induced apoptosis and ECM degradation in chondrocytes via restoring Sirt3 mediated autophagy and ameliorates osteoarthritis progression.

Osteoarthritis (OA) is a common age-related degenerative disease involving various pathological processes, among which apoptosis in chondrocyte and extracellular matrix (ECM) degradation are the main pathologies. Previous studies have shown that autophagy has a protective effect on apoptosis and ECM degradation in chondrocytes. Methyl gallate (MG) is a natural polyphenol from various medicinal and edible plants. Moreover, several studies have demonstrated that MG exerts multiple pharmacological effects in various diseases, including anti-inflammatory, antioxidant, and anti-apoptosis. Hence, in this study, we investigate the protective effect of MG on the pathological process of OA in cellular and mice OA model to elucidate the underlying molecular mechanism. In vitro, MG treatment inhibits the expression of pro-apoptotic proteins and promotes the expression of anti-apoptotic proteins under TBHP stimulation. Meanwhile, MG treatment promotes the expression of Collagen II and Aggrecan and inhibits the expression of matrix-degrading enzymes thrombospondin motifs 5 (ADAMTS5) and matrix metalloproteinase-13 (MMP13), which lead to ECM degradation. Furthermore, in terms of mechanism, MG treatment enhances autophagy by upregulating SIRT3 expression, and inhibition of autophagy could eliminate the protective effect of MG on chondrocytes in terms of anti-apoptosis and ECM synthesis. The protective effect of MG on OA has also been observed in mice OA model. In brief, our study suggests that MG could be a potential candidate for the treatment of OA.

LncRNA PVT1 regulates biological function of osteoarthritis cells by regulating miR-497/AKT3 axis.

Growing evidence indicates that lncRNAs are involved in the progression of several diseases, including osteoarthritis (OA). However, the role of the lncRNA PVT1 in OA is still unclear. The present study was aimed at exploring the impact of PVT1 on OA progression, along with potential underlying mechanisms. PVT1 expression levels in articular cartilage tissue of OA patients and non-OA patients were evaluated. To assess the proliferation and apoptosis of chondrocytes subject to treatment, PVT1, miR-497, and AKT3 were either knocked down or upregulated in IL-1β-induced chondrocytes. The variables detected were changes in levels of AKT3 and extracellular matrix (ECM)-related factors (including aggrecan, collagen Type II, and MMP-9). Elevated PVT1 levels were found in cartilage tissue of OA patients and IL-1β-induced chondrocytes. It was also observed that PVT1 knockdown and miR-497 upregulation led to enhanced cell proliferation and suppressed apoptosis. In addition, a decrease in aggrecan and collagen type II levels and an increase in MMP-9 levels were observed in IL-1β-induced chondrocytes. A dual luciferase reporter assay was performed to identify the factors that interacted with miR-497, PVT1, and AKT3. It was observed through rescue experiments that enhancing AKT3 expression or knocking down miR-497 could reverse the impacts of PVT1 knockdown in IL-1β-induced chondrocytes. An upregulation of PVT1 is observed in OA patients. On the other hand, PVT1 knockdown can decrease the effects of IL-1β on the proliferation, apoptosis, and expression of ECM-related proteins of chondrocytes through the regulation of the miR-497/AKT3 axis. PVT1 levels are elevated in the cartilage tissue of OA patients and IL-1β-induced chondrocytes. PVT1 knockdown alleviates the effects of IL-1β treatment on the proliferation and apoptosis of chondrocytes and ECM degradation in chondrocytes by regulating the miR-497/AKT3 axis.

Galangin ameliorates osteoarthritis progression by attenuating extracellular matrix degradation in chondrocytes via the activation of PRELP expression

Osteoarthritis (OA) is primarily characterized by progressive degeneration and destruction of articular cartilage. Currently, there is no effective method to treat OA. The metabolic disturbance of cartilage extracellular matrix (ECM) and oxidative stress are critical to promote OA progression. Galangin (Gal) is a small molecule compound that pertains to flavonoids. To determine the protective effect and mechanism of Gal against OA progression, various experiments were performed in vitro and in vivo. In vitro, Gal promoted ECM production and attenuated ECM degradation in human OA chondrocytes. The expression of ECM components from human OA cartilage explants was also stimulated by Gal treatment. As demonstrated from the in vivo study, the intra-articular injection of Gal delayed OA progression in rat models. Moreover, RNA sequencing analysis showed that proline/arginine-rich end leucine repeat protein (PRELP) was a molecular target of Gal activity. Gal inhibited oxidative stress and attenuated ECM degradation by activating PRELP expression. The study demonstrated that Gal could attenuate ECM degradation and ameliorate OA progression, and PRELP may be a potential candidate drug of Gal for treating OA.

Novel insights into the effect of deer IGF-1 on chondrocyte viability and IL-1β-induced inflammation response.

Clinical treatment of Osteoarthritis (OA) remains a challenge due to the poor self-regeneration ability of cartilage. Deer antler is the only cartilage tissue that can completely regenerate each year. Insulin-like growth factor 1 (IGF-1) is one of the major active components in the deer antler that participate in regulating the rapid regeneration of deer antler cartilage. This has led us to speculate that deer IGF-1 might potentially become a candidate drug for reducing damage and inflammation of OA. Thus, we aimed to explore the underlying mechanism of deer IGF-1 in chondrocyte proliferation, differentiation, and inflammation response.Deer, mouse, and human IGF-1 amino acid sequences and protein structures were aligned using CLUSTAL and PSIPRED. The underlying molecular mechanism of deer IGF-1 on primary chondrocytes was investigated by RNA-sequencing (RNA-seq) technology combined with various experiments. Cytokine interleukin-1β (IL-1β) was used to induce the inflammation response of primary chondrocytes.We found that deer IGF-1 was more similar to human IGF-1 than mouseIGF-1. qRT-PCR and immunofluorescence assayindicated that deer IGF-1 had stronger effects than mouse IGF-1. We also found that the deer IGF-1 enhanced the expression of cell proliferation, differentiation, and extracellular matrix (ECM)-related genes, but decreased the expression of ECM-degrading genes. Deer IGF-1 also attenuated the IL-1β-induced inflammatory and ECM degradation in chondrocytes.This study provides insight into the molecular mechanisms of deer IGF-1 on primary chondrocyte viability and presents a candidate for combatting inflammatory responses in OA development.

Metformin mitigates cholesterol accumulation via the AMPK/SIRT1 pathway to protect osteoarthritis chondrocytes

In this study, we aim to investigate the effect of metformin on cholesterol synthesis and efflux-related genes in chondrocytes during osteoarthritis (OA) and explore the underlying mechanisms. Primary chondrocytes were harvested from Wistar rat cartilage and divided into control and treatment groups. Chondrocytes in the treatment group were treated with interleukin-1β (IL-1β) mimicking the inflammatory environment of osteoarthritis. Subsequently, RT-qPCR, Western blotting, immunofluorescence staining, and Cell Counting Kit-8 (CCK-8) were conducted. Significant reductions in phosphorylated AMP-activated protein kinase (p-AMPK) and silent information regulator 1 (SIRT1) protein expression were observed in both human OA chondrocytes and cultured primary murine chondrocytes treated with IL-1β, while AMP-activated protein kinase (AMPK) was not inhibited. Moreover, in the presence of IL-1β, metformin significantly increased the expression of p-AMPK and SIRT1 at the protein and mRNA level. Meanwhile, metformin could reverse IL-1β-induced cartilage extracellular matrix degradation in chondrocytes from the rat model of OA (treated by IL-β) by activating the AMPK/SIRT1 pathway. Moreover, metformin activated AMPK and SIRT1, mediated by the activation of SREBP-2 and HMGCR in OA chondrocytes. Inhibiting AMPK/SIRT1 activity by its specific inhibitor could suppress IL-1β-induced expression of LXRα, ABCA1 and ApoA1 and cholesterol efflux. Thus, metformin inhibits cholesterol synthesis and promotes cholesterol efflux by activating the AMPK/SIRT1 pathway in OA chondrocytes. This study improves our understanding of the effect of metformin on cholesterol accumulation in OA chondrocytes.

MiR-3960 from Mesenchymal Stem Cell-Derived Extracellular Vesicles Inactivates SDC1/Wnt/β-Catenin Axis to Relieve Chondrocyte Injury in Osteoarthritis by Targeting PHLDA2.

Osteoarthritis (OA) is a serious disease of the articular cartilage characterized by excessive inflammation. Lately, mesenchymal stem cell- (MSC-) derived extracellular vesicles (EVs) have been proposed as a novel strategy for the treatment of OA. We aimed to investigate the effects of EV-encapsulated miR-3960 derived from MSCs on chondrocyte injury in OA. The cartilage tissues from OA patients were collected to experimentally determine expression patterns of miR-3960, PHLDA2, SDC1, and β-catenin. Next, luciferase assay was implemented to testify the binding affinity among miR-3960 and PHLDA2. EVs were isolated from MSCs and cocultured with IL-1β-induced OA chondrocytes. Afterwards, cellular biological behaviors and levels of extracellular matrix- (ECM-) related protein anabolic markers (collagen II and aggrecan), catabolic markers (MMP13 and ADAMTS5), and inflammatory factors (IL-6 and TNF-α) in chondrocytes were assayed upon miR-3960 and/or PHLDA2 gain- or loss-of-function. Finally, the effects of miR-3960 contained in MSC-derived EVs in OA mouse models were also explored. MSCs-EVs could reduce IL-1β-induced inflammatory response and extracellular matrix (ECM) degradation in chondrocytes. miR-3960 expression was downregulated in cartilage tissues of OA patients but enriched in MSC-derived EVs. miR-3960 could target and inhibit PHLDA2, which was positively correlated with SDC1 and Wnt/β-catenin pathway activation. miR-3960 shuttled by MSC-derived EVs protected against apoptosis and ECM degradation in chondrocytes. In vivo experiment also confirmed that miR-3960 alleviated chondrocyte injury in OA. Collectively, MSC-derived EV-loaded miR-3960 downregulated PHLDA2 to inhibit chondrocyte injury via SDC1/Wnt/β-catenin.

Calycosin prevents IL-1β-induced articular chondrocyte damage in osteoarthritis through regulating the PI3K/AKT/FoxO1 pathway.

Osteoarthritis (OA) is a joint disorder that is associated with chondrocyte damage under inflammatory environment. Calycosin is an astragalus extract with potential anti-inflammatory and anti-tumor activities. The purpose of this research is to explore the activity and mechanism of calycosin in interleukin-1beta (IL-1β)-induced chondrocyte injury. In the present study, the targets of calycosin and OA were analyzed according to HERB, DisGeNet, String, GO terms, and KEGG pathway enrichment assays. Human primary chondrocytes were treated with calycosin, and stimulated with IL-1β. Cell viability was detected by CCK-8 assay. Cell apoptosis was investigated by flow cytometry, and caspase-3 activity analyses. Inflammation was analyzed according to inflammatory cytokines levels by enzyme-linked immunosorbent assay (ELISA). The proteins associated with extracellular matrix (ECM) degradation and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/forkhead box O1 (FoxO1) signaling pathways were measured using Western blotting. The results showed that total of 25 overlapping targets of calycosin against OA were predicted. These targets might drive the FoxO pathway. Calycosin alone induced little cytotoxicity to chondrocytes, and it alleviated IL-1β-induced viability inhibition, cell apoptosis, inflammatory cytokine secretion, and ECM degradation in chondrocytes. Calycosin repressed IL-1β-induced activation of the PI3K/AKT/FoxO1 signaling. Activation of the PI3K/AKT/FoxO1 signaling mitigated the suppressive effect of calycosin on chondrocyte apoptosis, inflammation, and ECM degradation induced by IL-1β. As a conclusion, calycosin prevents IL-1β-induced chondrocyte apoptosis, inflammation, and ECM degradation through inactivating the PI3K/AKT/FoxO1 pathway.

Long noncoding RNA PVT1 promotes chondrocyte extracellular matrix degradation by acting as a sponge for miR-140 in IL-1\u03b2-stimulated chondrocytes

BackgroundOsteoarthritis (OA) is a common degenerative joint disease, and chondrocyte extracellular matrix (ECM) degradation is one vital pathological feature of OA. Long noncoding RNA (lncRNA), a new kind of gene regulator, plays an important role in pathogenesis of many diseases like OA. Recent studies have confirmed that lncRNA plasmacytoma variant translocation 1 (PVT1) expression was upregulated in OA patients; however, its effect on ECM degradation remained unknown.MethodsCartilage tissue samples were obtained from 6 OA patients admitted in Guangdong Second Traditional Chinese Medicine Hospital. Chondrocytes were isolated and cultured from the collected cartilage tissue. Plasmid construction, RNA interference, cell transfection, fluorescence in situ hybridization (FISH), and pull-down assay were carried out during the research.ResultsIn this study, PVT1 expression was significantly increased in chondrocytes stimulated by interleukin-1β (IL-1β). In addition, inhibition of PVT1 significantly downregulated the increased expressions of ADAM metallopeptidase with thrombospondin type 1 motif-5 (ADAMTS-5) and matrix metalloproteinase-13 (MMP-13) induced by IL-1β. Further investigation revealed that PVT1 was an endogenous sponge RNA, which directly bound to miR-140 and inhibited miR-140 expression.ConclusionTo sum up, this study showed that PVT1 promoted expressions of ADAMTS-5 and MMP-13 as a competing endogenous RNA (ceRNA) of miR-140 in OA, which eventually led to aggravation of ECM degradation, thus providing a new and promising strategy for the treatment of OA.

Silencing of circ_0000205 mitigates interleukin-1β-induced apoptosis and extracellular matrix degradation in chondrocytes via targeting miR-766-3p/ADAMTS5 axis.

The aim of this study was to explore the role of hsa_circRNA_0000205 (circ_0000205) in chondrocyte injury in osteoarthritis (OA) and the underlying mechanism. Expression of circ_0000205, microRNA (miR)-766-3p and a disintegrin and metalloproteinase with thrombospondin motif (ADAMTS)-5 was detected by quantitative real time (qRT)-polymerase chain reaction (PCR) and Western blot assays. Cell proliferation, apoptosis, and extracellular matrix (ECM) synthesis were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and 5-ethynyl-2-deoxyuridine assays, flow cytometry, and qRT-PCR and Western blot assays. The target relationship between miR-766-3p and circ_0000205 or ADAMTS5 was confirmed by luciferase reporter assay and RNA immunoprecipitation. IL-1β treatment could attenuate cell viability of primary chondrocytes and proliferating cell nuclear antigen (PCNA) and collagen II type alpha-1 (COL2A1) levels, and elevate apoptosis rate and cleaved caspase-3, ADAMTS5 and matrix metalloproteinase-13 (MMP13) levels, suggesting that IL-1β induced chondrocyte apoptosis and ECM degradation. Expression of circ_0000205 was up-regulated in OA tissues and IL-1β-induced primary chondrocytes, accompanied with miR-766-3p down-regulation and ADAMTS5 up-regulation. Knockdown of circ_0000205 could mitigate IL-1β-induced above effects and improve cell proliferation. Moreover, both depleting miR-766-3p and promoting ADAMTS5 could partially counteract circ_0000205 knockdown roles in IL-1β-cultured primary chondrocytes. Notably, circ_0000205 was verified as a sponge for miR-766-3p via targeting, and ADAMTS5 was a direct target for miR-766-3p. Silencing circ_0000205 could protect chondrocytes from IL-1β-induced proliferation reduction, apoptosis, and ECM degradation by targeting miR-766-3p/ADAMTS5 axis.

Ononin ameliorates inflammation and cartilage degradation in rat chondrocytes with IL-1\u03b2-induced osteoarthritis by downregulating the MAPK and NF-\u03baB pathways

BackgroundOsteoarthritis (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.MethodsIn 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.ResultsOur 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.ConclusionOur 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.

Tangeretin suppresses osteoarthritis progression via the Nrf2/NF-κB and MAPK/NF-κB signaling pathways

BackgroundOsteoarthritis (OA) is a globally prevalent degenerative disease characterized by extracellular matrix (ECM) degradation and inflammation. Tangeretin is a natural flavonoid that has anti-inflammatory properties. Studies have not explored whether tangeretin modulates OA development. PurposeThe aim of this study was to explore the potential effects and mechanism underlying the anti-OA properties of tangeretin. Study designEffects of tangeretin on OA were detected in chondrocytes and OA mouse model. MethodsProtective effects of tangeretin on murine articular chondrocytes treated with interleukin-1β (IL-1β) were evaluated using qPCR, western blot analysis, ELISA, ROS detection and immunofluorescent staining in vitro. Healing effect of tangeretin on cartilage degradation in mice was assessed through X-ray imaging, histopathological analysis, immunohistochemical staining and immunofluorescent staining in vivo. ResultsTangeretin suppressed IL-1β-mediated inflammatory mediator secretion and degradation of ECM in chondrocytes. The results showed that tangeretin abrogated destabilized medial meniscus (DMM)-induced cartilage degradation in mice. Mechanistic studies showed that tangeretin suppressed OA development by downregulating activation of NF-κB by activating Nrf2/HO-1 axis and suppressing MAPK signaling pathway. ConclusionTangeretin abrogates OA progression by inhibiting inflammation as well as ECM degradation in chondrocytes and animal models. Effects of tangeretin are mediated through Nrf2/NF-κB and the MAPK/NF-κB pathways. Thus, tangeretin is a potential therapeutic agent for osteoarthritis treatment.

CircPRKCH modulates extracellular matrix formation and metabolism by regulating the miR-145/HGF axis in osteoarthritis

BackgroundOsteoarthritis (OA) is a chronic degenerative joint disease. Extracellular matrix (ECM) degradation is essential for OA progression. Previous studies have shown that circular RNAs (circRNAs) are involved in the pathological process of OA. CircPRKCH has been shown to be upregulated in OA chondrocytes. The present study was aimed to explore the roles of circPRKCH in vivo and in vitro models of OA and its underlying molecular mechanisms.MethodsIL-1β-induced chondrocytes and mice injected with monosodium iodoacetate were used as OA models in vitro and in vivo, respectively. RT-qPCR was performed to measure the expression of circPRKCH, miR-145, and HGF in cartilage tissues and chondrocytes. The interaction between miR-145 and circPRKCH or HGF was verified by a dual-luciferase reporter assay. Chondrocyte apoptosis, viability, and ECM-related proteins were examined by flow cytometry, MTT assay, and Western blotting, respectively. Histopathological changes were detected by HE and Safranin O-fast green staining.ResultsThe expression of circPRKCH and HGF was increased in OA cartilage tissues and IL-1β-treated chondrocytes, while miR-145 expression was decreased. IL-1β induced chondrocyte apoptosis and ECM degradation in chondrocytes. Moreover, circPRKCH promoted HGF expression and activated HGF/c-MET by directly binding to miR-145. miR-145 knockdown or HGF overexpression significantly reversed circPRKCH knockdown-mediated inhibition of apoptosis and ECM degradation in IL-1β-induced chondrocytes. Besides, miR-145 overexpression alleviated IL-1β-induced chondrocyte apoptosis and ECM degradation by inhibiting HGF/c-MET. Finally, circPRKCH knockdown reduced ECM degradation by regulating the miR-145/HGF axis in an experimental OA model in mice.ConclusionOur study demonstrated that circPRKCH promoted chondrocyte apoptosis and ECM degradation via the miR-145/HGF axis in OA, which may provide a novel target for OA treatment.

Research Progress of Traditional Chinese Medicine Intervention on HIF-2α in the Prevention and Treatment of Knee Osteoarthritis

Knee osteoarthritis (KOA) is the most common chronic, degenerative and progressive osteoarthritis in clinical practice, which mainly manifests as knee pain, deformity and even joint function loss. With the advent of the global aging era, its incidence continues to increase, seriously occupying the medical resources of various countries. Its pathogenic factors are complex and its pathogenesis is not clear. How to effectively prevent and cure it has always been a hot topic in the medical field. Recent studies have found that the expression level of hypoxia inducible factor (HIIF) -2α plays an important role in regulating chondrocyte homeostasis, which is involved in the degradation of chondrocyte extracellular matrix and the generation of subchondral bone vessels, and accelerates cartilage degeneration. Studies have shown that the active ingredients of traditional Chinese medicine can regulate the expression of HIF-2α and slow down the development of knee osteoarthritis. This article reviews the related research on the prevention and treatment of knee osteoarthritis by the intervention of traditional Chinese medicine on HIF-2α expression, so as to provide scientific clinical basis and treatment plan for the later research on the treatment of KOA with traditional Chinese medicine.

MiR-125a-5p-abundant exosomes derived from mesenchymal stem cells suppress chondrocyte degeneration via targeting E2F2 in traumatic osteoarthritis

ABSTRACT miRNAs are broad participants in vertebrate biological processes, and they are also the major players in pathological processes. miR-125a-5p was recently found a modulator in the progression of osteoarthritis (OA). Our study was aimed to explore the role and underlying mechanisms of miR-125a-5p-abundant exosomes derived from mesenchymal stem cells (MSC) on OA progression. We separated bone marrow mesenchymal stem cells (BMSCs) as well as the exosomes from traumatic OA patients. The immunofluorescence and cartilage staining were implemented for the observation and the assessment on endocytosis of chondrocytes and exosomal miR-125a-5p efficacy to cartilage degradation. Dual luciferase reporter assay was performed to verified the relationship between miR-125a-5p and E2F2. Then, the function of exosomal miR-125a-5p were examined on chondrocyte degeneration in vitro and in vivo. Our findings indicated that E2F2 expression was elevated while the miR-125a-5p was down in traumatic OA cartilage tissue, showing a negative correlation of the former and the latter. miR-125a-5p targets E2F2 in traumatic OA cartilage tissue and leads to the down-expression of E2F2. The E2F2 expression in chondrocytes was decreased after internalization of exosomes. We additionally found that BMSCs-derived exosomes were rich in miR-125a-5p content and chondrocytes can have it internalized. miR-125a-5p is endowed with a trait of accelerating chondrocytes migration, which is going along with the up-expressions of Collagen II, aggrecan and SOX9 and the down-expression of MMP-13 in vitro. Besides that, the mice model with post-traumatic OA turned out that exosomal miR-125a-5p might beget an alleviation in chondrocyte extracellular matrix degradation. All these outcomes revealed that BMSCs-derived exosomal miR-125a-5p is a positive regulator for chondrocyte migration and inhibit cartilage degeneration We thus were reasonable to believe that transferring of exosomal miR-125a-5p is a prospective strategy for OA treatment.

DNA methyltransferase 3 beta mediates the methylation of the microRNA-34a promoter and enhances chondrocyte viability in osteoarthritis

ABSTRACT Osteoarthritis (OA) is characterized by destruction of articular cartilage with an imbalance between synthesis and degradation of extracellular matrix (ECM). In the current study, we explored the role of microRNA-34a (miR-34a) and the behind epigenetic mechanism in the degradation of ECM in OA. Using miRNA-based microarray analysis, we found that miR-34a was overexpressed in cartilage tissues of OA patients relative to patients with acute traumatic amputations. Moreover, its expression was positively correlated with the ECM degradation and inflammation. Mechanistically, miR-34a targeted MCL1, and possible target genes of miR-34a were enriched in the PI3K/AKT pathway. Furthermore, DNMT3B inhibited miR-34a by promoting miR-34a methylation. Functional experiments using CCK-8, flow cytometry, Safranin O staining, RT-qPCR, ELISA, Western blot, and HE staining revealed that miR-34a inhibitor suppressed ECM degradation and inflammatory response of chondrocytes and cartilage tissues. By contrast, downregulation of DNMT3B and MCL1 reversed the repressive effects of miR-34a inhibitor in vitro and in vivo. Altogether, our findings establish that silencing of miR-34a by DNMT3B could effectively reduce chondrocyte ECM degradation and inflammatory response in mice by targeting MCL1 and mediating the downstream PI3K/AKT pathway. This present study revealed that miR-34a knockdown might develop a novel intervention for OA treatment.

LINC00473 exacerbates osteoarthritis development by promoting chondrocyte apoptosis and proinflammatory cytokine production through the miR-424-5p/LY6E axis.

Osteoarthritis (OA) is a common degenerative joint disease that has been identified as one of the major health burdens in aging individuals. Long non-coding RNAs (lncRNAs) participate in the development of diverse diseases, including OA. Among them, lncRNA long intergenic non-protein coding RNA 473 (LINC00473) is one of the few upregulated lncRNAs. The present study aimed to explore the role of LINC00473 and its regulatory mechanism in OA development. Flow cytometry analyses and ELISA were carried out to detect chondrocyte apoptosis and the concentration of proinflammatory cytokines, respectively. The results suggested that LINC00473 knockdown significantly reduced chondrocyte apoptosis and the production of proinflammatory cytokines in IL-1β-stimulated C28/I2 cells compared with transfection with small interfering RNA-negative control (si-NC). Western blot analyses were performed to examine protein levels of apoptotic markers (caspase-3, Bax and Bcl-2) in C28/I2 cells. Subsequently, an OA rat model was established to explore the role of LINC00473 in vivo. The results indicated that, compared with the OA + adeno-associated virus si-NC group, LINC00473 knockdown significantly suppressed the degradation of chondrocyte extracellular matrix and the production of proinflammatory cytokines in OA model rats. Furthermore, bioinformatics analysis, luciferase reporter and RNA immunoprecipitation assays indicated that LINC00473 served as a microRNA (miR)-424-5p sponge in C28/I2 cells, and that lymphocyte antigen 6 locus E (LY6E) was the downstream target. In addition, the inhibitory effects of LINC00473 knockdown on chondrocyte apoptosis and the inflammatory response could be reversed by LY6E overexpression in IL-1β-stimulated C28/I2 cells. In summary, the findings indicated that LINC00473 contributed to OA progression by modulating the miR-424-5p/LY6E axis, which may serve as a potential therapeutic strategy for patients with OA.