OBJECTIVE: To investigate the effects and underlying mechanisms of VX765 on osteoarthritis (OA) and chondrocytes inflammation in rats. METHODS: Chondrocytes were isolated from the knee joints of 4-week-old Sprague Dawley (SD) rats. The third-generation cells were subjected to cell counting kit 8 (CCK-8) analysis to assess the impact of various concentrations (0, 1, 5, 10, 20, 50, 100 μmol/L) of VX765 on rat chondrocyte activity. An in vitro lipopolysaccharide (LPS) induced cell inflammation model was employed, dividing cells into control group, LPS group, VX765 concentration 1 group and VX765 concentration 2 group without obvious cytotoxicity. Western blot, real-time fluorescence quantitative PCR, and ELISA were conducted to measure the expression levels of inflammatory factors-transforming growth factor β ₁ (TGF-β ₁), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α). Additionally, Western blot and immunofluorescence staining were employed to assess the expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1). Thirty-two SD rats were randomly assigned to sham surgery group (group A), OA group (group B), OA+VX765 (50 mg/kg) group (group C), and OA+VX765 (100 mg/kg) group (group D), with 8 rats in each group. Group A underwent a sham operation with a medial incision, while groups B to D underwent additional transverse incisions to the medial collateral ligament and anterior cruciate ligament, with removal of the medial meniscus. One week post-surgery, groups C and D were orally administered 50 mg/kg and 100 mg/kg VX765, respectively, while groups A and B received an equivalent volume of saline. Histopathological examination using HE and safranin-fast green staining was performed, and Mankin scoring was utilized for evaluation. Immunohistochemical staining technique was employed to analyze the expressions of matrix metalloproteinase 13 (MMP-13) and collagen type Ⅱ. RESULTS: The CCK-8 assay indicated a significant decrease in cell viability at VX765 concentrations exceeding 10 μmol/L ( P<0.05), so 4 μmol/L and 8 μmol/L VX765 without obvious cytotoxicity were selected for subsequent experiments. Following LPS induction, the expressions of TGF-β ₁, IL-6, and TNF-α in cells significantly increased when compared with the control group ( P<0.05). However, intervention with 4 μmol/L and 8 μmol/L VX765 led to a significant decrease in expression compared to the LPS group ( P<0.05). Western blot and immunofluorescence staining demonstrated a significant upregulation of Nrf2 pathway-related molecules Nrf2 and HO-1 protein expressions by VX765 ( P<0.05), indicating Nrf2 pathway activation. Histopathological examination of rat knee joint tissues and immunohistochemical staining revealed that, compared to group B, treatment with VX765 in groups C and D improved joint structural damage in rat OA, alleviated inflammatory reactions, downregulated MMP-13 expression, and increased collagen type Ⅱ expression. CONCLUSION VX765 can improve rat OA and reduce chondrocyte inflammation, possibly through the activation of the Nrf2 pathway.
Rats ; Animals ; Chondrocytes/metabolism* ; Matrix Metalloproteinase 13/metabolism* ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha/metabolism* ; Collagen Type II/metabolism* ; Interleukin-6 ; Lipopolysaccharides/pharmacology* ; NF-E2-Related Factor 2/pharmacology* ; Inflammation/drug therapy* ; Osteoarthritis/metabolism* ; Transforming Growth Factor beta1/metabolism* ; Dipeptides ; para-Aminobenzoates

OBJECTIVES: This study aims to investigate the effects and mechanisms of chondroitin sulfate (CS), dermatan sulfate (DS), and heparin (HEP) on chondrogenesis of murine chondrogenic cell line (ATDC5) cells and the maintenance of murine articular cartilage in vitro. METHODS: ATDC5 and articular cartilage tissue explant were cultured in the medium containing different sulfated glycosaminoglycans. Cell proliferation, differentiation, cartilage formation, and mechanism were observed using cell proliferation assay, Alcian blue staining, real-time quantitative polymerase chain reaction (RT-qPCR), and Western blot, respectively. RESULTS: Results showed that HEP and DS primarily activated the bone morphogenetic protein (BMP) signal pathway, while CS primarily activated the protein kinase B (AKT) signal pathway, further promoted ATDC5 cell proliferation and matrix production, and increased Sox9, Col2a1, and Aggrecan expression. CONCLUSIONS This study investigated the differences and mechanisms of different sulfated glycosaminoglycans in chondrogenesis and cartilage homeostasis maintenance. HEP promotes cartilage formation and maintains the normal state of cartilage tissue in vitro, while CS plays a more effective role in the regeneration of damaged cartilage tissue.
Animals ; Mice ; Cartilage/metabolism* ; Cell Differentiation ; Cells, Cultured ; Chondrocytes/metabolism* ; Chondrogenesis/physiology* ; Glycosaminoglycans/pharmacology*

To investigate the mechanism by which Cangxi Tongbi Capsules promote chondrocyte autophagy to inhibit knee osteoarthritis(KOA) progression by regulating the circRNA＿0008365/miR-1271/p38 mitogen-activated protein kinase(MAPK) pathway. The cell and animal models of KOA were established and intervened with Cangxi Tongbi Capsules, si-circRNA＿0008365, si-NC, and Cangxi Tongbi Capsules combined with si-circRNA＿0008365. Flow cytometry and transmission electron microscopy were employed to determine the level of apoptosis and observe autophagosomes, respectively. Western blot was employed to reveal the changes in the protein levels of microtubule-associated protein light chain 3(LC3)Ⅱ/Ⅰ, Beclin-1, selective autophagy junction protein p62/sequestosome 1, collagen Ⅱ, a disintegrin and metalloproteinase with thrombospondin motifs 5(ADAMTS-5), and p38 MAPK. The mRNA levels of circRNA＿0008365, miR-1271, collagen Ⅱ, and ADAMTS-5 were determined by qRT-PCR. Hematoxylin-eosin staining was employed to reveal the pathological changes of the cartilage tissue of the knee, and enzyme-linked immunosorbent assay to measure the levels of interleukin-1β(IL-1β) and tumor necrosis factor-alpha(TNF-α). The chondrocytes treated with IL-1β showed down-regulated expression of circRNA＿0008365, up-regulated expression of miR-1271 and p38 MAPK, lowered autophagy level, increased apoptosis rate, and accelerated catabolism of extracellular matrix. The intervention with Cangxi Tongbi Capsules up-regulated the expression of circRNA＿0008365, down-regulated the expression of miR-1271 and p38 MAPK, increased the autophagy level, decreased the apoptosis rate, and weakened the catabolism of extracellular matrix. However, the effect of Cangxi Tongbi Capsules was suppressed after interfering with circRNA＿0008365. The in vivo experiments showed that Cangxi Tongbi Capsules dose-dependently inhibited the p38 MAPK pathway, enhanced chondrocyte autophagy, and mitigated articular cartilage damage and inflammatory response, thereby inhibiting the progression of KOA in rats. This study indicated that Cangxi Tongbi Capsules promoted chondrocyte autophagy by regulating the circRNA＿0008365/miR-1271/p38 MAPK pathway to inhibit the development of KOA.
Rats ; Animals ; Chondrocytes ; Osteoarthritis, Knee/pathology* ; RNA, Circular/pharmacology* ; p38 Mitogen-Activated Protein Kinases/metabolism* ; MicroRNAs/metabolism* ; Apoptosis ; Autophagy/genetics* ; Collagen/metabolism*

Mechanical signal transduction are crucial for chondrocyte in response to mechanical cues during the growth, development and osteoarthritis (OA) of articular cartilage. Extracellular matrix (ECM) turnover regulates the matrix mechanical microenvironment of chondrocytes. Thus, understanding the mechanotransduction mechanisms during chondrocyte sensing the matrix mechanical microenvironment can develop effective targeted therapy for OA. In recent decades, growing evidences are rapidly advancing our understanding of the mechanical force-dependent cartilage remodeling and injury responses mediated by TRPV4 and PIEZOs. In this review, we highlighted the mechanosensing mechanism mediated by TRPV4 and PIEZOs during chondrocytes sensing mechanical microenvironment of the ECM. Additionally, the latest progress in the regulation of OA by inflammatory signals mediated by TRPV4 and PIEZOs was also introduced. These recent insights provide the potential mechanotheraputic strategies to target these channels and prevent cartilage degeneration associated with OA. This review will shed light on the pathogenesis of articular cartilage, searching clinical targeted therapies, and designing cell-induced biomaterials.
Chondrocytes ; TRPV Cation Channels ; Mechanotransduction, Cellular ; Biocompatible Materials ; Cartilage, Articular

OBJECTIVE: To investigate whether Salvianolic acid A (SAA) can restore cartilage endplate cell degeneration of intervertebral discs and to identify the mechanism via regulation of micro-RNA. METHODS: Cartilage endplate cells were isolated from lumbar intervertebral disc surgical samples and were treated with serum containing a series of concentrations of SAA (2, 5, and 10 ?M) for 24, 48, and 72 h to identify a proper dose and treatment time of SAA. The effect SAA on interlenkin-1β (IL-1β)-induced extracellular matrix degradation of cartilage endplate cells were analyzed by Alcian blue staining and assessment of the expression levels of ADAMTS-5, MMP3 and Col2a1. Further, the potential target miRNAs were preliminarily screened by micro-RNA sequencing combining qRT-PCR and Western blot, and then, the miRNAs mimics and inhibitors were used to verify the regulatory effect of SAA on potential target miRNAs. RESULTS: The 10 μM SAA treatment for 48 h significantly enhanced the viability of cartilage endplate cells, and increased Col2a1 expression and glycosaminoglycan accumulation that were repressed by IL-1β, and reduced the effect of IL-1β on ADAMTS-5, and MMP3. Screening analysis based on micro-RNA sequencing and Venny analysis identified the downstream micro-RNAs, including miR-940 and miR-576-5p. Then, the miR-940-mimic or miR-576-5p-mimic were transfected into CEPCs. Compared with the SAA group, the expression of ADAMTS-5 and MMP3 increased significantly and the expression of COL2A1 obviously decreased after overexpression of miR-940 or miR-576-5p in CEPCs. CONCLUSION Salvianolic acid A attenuated the IL-1β-induced extracellular matrix degradation of cartilage endplate cells by targeting regulate the miR-940 and the miR-576-5p.
Humans ; Apoptosis ; Cartilage/metabolism* ; Chondrocytes/metabolism* ; Interleukin-1beta/metabolism* ; Matrix Metalloproteinase 3/metabolism* ; MicroRNAs/metabolism*

OBJECTIVE: To explore and verify that transient receptor potential vanilloid 4(TRPV4) affects chondrocyte degeneration. METHODS: Neonatal SD rats were selected, primary chondrocytes were extracted, and identified by toluidine blue staining and alcian blue staining;an in vitro chondrocyte inflammation model was constructed by IL-1β, and TRPV4 inhibitor was used to treat chondrocytes under inflammatory conditions, and the chondrocytes were treated by RT-PCR method was used to detect matrix metallopeptidase 13(MMP-13), a disintegrin and metalloproteinase with thrombospondin 5, (ADAMTS-5)、nitric oxide synthase 2(NOS2)、Collagen, type II alpha 1(Col2α1)and aggrecan (Acan) mRNA in chondrocytes; primary chondrocytes were treated with different concentrations of TRPV4 overexpression plasmid, and the optimal overexpression dose was screened. The mRNA expressions of TRPV4, MMP-13, ADAMTS-5, NOS2, Col2α1 and Acan in chondrocytes under the optimal TRPV4 overexpression dose were detected. RESULTS: Toluidine blue staining and Alcian blue staining identified the extracted cells as primary chondrocytes;RT-PCR showed that TRPV4, MMP-13, ADAMTS-5, NOS2 mRNA in chondrocytes treated with TRPV4 inhibitor under inflammatory conditions. The expression of Col2α1 mRNA was significantly decreased (P<0.05), and the expression of Col2α1 mRNA was increased (P<0.05). Although there was no significant difference in the expression of Acan mRNA, the overall trend was also increasing. The expression of Col2α1 and Acan mRNA in chondrocytes was significantly decreased (P<0.05), and the expression of NOS2 mRNA was increased(P<0.05), but there was no significant difference in MMP-13 and ADAMTS-5 (P>0.05). CONCLUSION Inhibiting the expression of TRPV4 can down-regulate the expression of genes related to chondrocyte degeneration.
Animals ; Rats ; Aggrecans/metabolism* ; Cartilage, Articular ; Cells, Cultured ; Chondrocytes ; Interleukin-1beta/metabolism* ; Matrix Metalloproteinase 13/metabolism* ; Rats, Sprague-Dawley ; RNA, Messenger/metabolism* ; TRPV Cation Channels/metabolism*

Objective To explore the protective mechanism of transdifferentiation of glomerular endothelial cells based on the differentiated embryonic chondrocyte gene 2 (DEC2) via the TGF-β/ROCK1 signaling pathway. Methods The 24 mice were randomly divided into sham group, UUO group, UUO combined with vector group and UUO combined with DEC2 group, with 6 mice in each group. A unilateral ureteral obstruction (UUO) model was established in each group, except for the sham group. In the UUO combined with vector group and UUO combined with DEC2 group, 10 μL (10⁸ PFU) of vector or DEC2 was injected into each kidney on day 0 (immediately after UUO) under the guidance of the ultrasound system. The mice were sacrificed 14 days after the operation, and the kidneys were collected for histological examination and Western blot analysis: HE staining was used to observe the histological changes of kidneys, Masson staining to observe the renal fibrosis, and Western blot analysis to detect the protein expression. In vitro, normal human glomerular endothelial cells (GEnCs) was selected as the research objects. GEnCs stimulated with TGF-β were treated with ROCK1 inhibitor Y-27632 or DEC2 transfection. Western blot analysis was used to detect the expression of ROCK1, α-SMA, DEC2 and E-cadherin in GEnC exposed to transforming growth factor β (TGF-β). The localization of ROCK1 and DEC2 in GEnCs cells was detected by immunofluorescence cytochemistry. The relationship between the ROCK1 and DEC2 was confirmed by co-immunoprecipitation. Results Compared with the sham group, the UUO groups showed significant renal fibrosis and collagen accumulation on the 14th day. In the UUO groups, the expression of DEC2 and E-cadherin in the kidney tissue of the mice was significantly reduced, and the expression of α-SMA significantly increased. Compared with the UUO combined with vector group, the kidney fibrosis and collagen accumulation in the UUO combined with DEC2 group decreased, and the expression of ROCK1 and α-SMA decreased and the expression of DEC2 and E-cadherin increased in the kidney tissue. TGF-β enhanced the expression of ROCK1 and α-SMA in GEnCs cells in a time-dependent manner, and the levels of DEC2 and E-cadherin decreased. Treatment with the ROCK1 inhibitor Y-27632 partially abrogated the TGF-β-induced increase in the expression of ROCK1 and α-SMA and decrease in the expression of DEC2 and E-cadherin. In addition, transfection of GEnCs cells with DEC2 before TGF-β stimulation reduced the expression of ROCK1 and α-SMA, and increased the expression of DEC2 and E-cadherin. Immunofluorescence cytochemical staining showed that DEC2 co-localized with ROCK1 in GEnCs, and the co-immunoprecipitation showed that DEC2 and ROCK1 pulled down each other. Conclusions DEC2 is down-regulated in fibrotic renal tissue, while up-regulated DEC2 inhibits epithelial myofibroblast transdifferentiation and renal fibrosis of GEnC by blocking TGF-β/ROCK1 signaling pathway.
Humans ; Animals ; Mice ; Cell Transdifferentiation ; Chondrocytes ; Endothelial Cells ; Cadherins ; Signal Transduction ; rho-Associated Kinases

The study aims to explore the effect of mesenchymal stem cells-derived exosomes (MSCs-Exo) on staurosporine (STS)-induced chondrocyte apoptosis before and after exposure to pulsed electromagnetic field (PEMF) at different frequencies. The AMSCs were extracted from the epididymal fat of healthy rats before and after exposure to the PEMF at 1 mT amplitude and a frequency of 15, 45, and 75 Hz, respectively, in an incubator. MSCs-Exo was extracted and identified. Exosomes were labeled with DiO fluorescent dye, and then co-cultured with STS-induced chondrocytes for 24 h. Cellular uptake of MSC-Exo, apoptosis, and the protein and mRNA expression of aggrecan, caspase-3 and collagenⅡA in chondrocytes were observed. The study demonstrated that the exposure of 75 Hz PEMF was superior to 15 and 45 Hz PEMF in enhancing the effect of exosomes in alleviating chondrocyte apoptosis and promoting cell matrix synthesis. This study lays a foundation for the regulatory mechanism of PEMF stimulation on MSCs-Exo in inhibiting chondrocyte apoptosis, and opens up a new direction for the prevention and treatment of osteoarthritis.
Animals ; Rats ; Apoptosis ; Chondrocytes ; Electromagnetic Fields ; Exosomes/physiology* ; Mesenchymal Stem Cells/metabolism*

Objective: To preliminarily explore the mechanism of tensile stress regulating endochondral osteogenesis of condyle by analyzing the expression profiles of significantly different microRNAs (miRNAs) in exosomes of rat mandibular condylar chondrocytes (MCC) under quiescent and cyclic tensile strain (CTS) conditions. Methods: Rat condylar chondrocytes were cultured under static and CTS conditions respectively (10 SD rats, male, 2 weeks old), and exosomes were extracted. The two groups of exosomes were named as control group and CTS group respectively. The differential expression miRNAs were screened by high-throughput sequencing. Bioinformatics analysis and prediction of target genes related to osteogenesis were performed by TargetScan and miRanda website. Results: The exosomes of rat condylar chondrocytes cultured under tensile stress showed a "double concave disc" monolayer membrane structure, the expression of CD9 and CD81 were positive, and the particle size distribution accorded with the characteristics of exosomes, which was consistent with that of static cultured rat condylar chondrocytes. A total of 85 miRNAs with significantly different expression were detected by high-throughput sequencing (P<0.05). The main biological processes and molecular functions of differential miRNAs were biological processes and protein binding, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) database pathway enrichment analysis showed that there was significant enrichment in mammalian target of rapamycin (mTOR) signal pathway. The candidate target genes of miR-199a-5p include bone morphogenetic protein 3 (BMP3), endothelin converting enzyme 1, and miR-186-5p may target Smad8 and BMP3 to exert osteogenesis-related functions. Conclusions: Compared with static state, tensile stress stimulation can change the expression of miRNAs such as miR-199a-5p, miR-186-5p in the exocrine body of rat condylar chondrocytes, which can be considered as a mean to regulate the application potential of the exosomes.
Animals ; Male ; Rats ; Bone Morphogenetic Protein 3 ; Chondrocytes/metabolism* ; Mandibular Condyle ; MicroRNAs/metabolism* ; Rats, Sprague-Dawley ; Signal Transduction ; Stress, Mechanical

Osteoarthritis is a prevalent global joint disease, which is characterized by inflammatory reaction and cartilage degradation. Cyasterone, a sterone derived from the roots of Cyathula officinalis Kuan, exerts protective effect against several inflammation-related diseases. However, its effect on osteoarthritis remains unclear. The current study was designed to investigate the potential anti-osteoarthritis activity of cyasterone. Primary chondrocytes isolated from rats induced by interleukin (IL)-1β and a rat model stimulated by monosodium iodoacetate (MIA) were used for in vitro and in vivo experiments, respectively. The results of in vitro experiments showed that cyasterone apparently counteracted chondrocyte apoptosis, increased the expression of collagen II and aggrecan, and restrained the production of the inflammatory factors inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), metalloproteinase-3 (MMP-3), and metalloproteinase-13 (MMP-13) induced by IL-1β in chondrocytes. Furthermore, cyasterone ameliorated the inflammation and degenerative progression of osteoarthritis potentially by regulating the nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. For in vivo experiments, cyasterone significantly alleviated the inflammatory response and cartilage destruction of rats induced by monosodium iodoacetate, where dexamethasone was used as the positive control. Overall, this study laid a theoretical foundation for developing cyasterone as an effective agent for the alleviation of osteoarthritis.
Animals ; Rats ; Chondrocytes ; NF-kappa B ; Iodoacetic Acid ; Inflammation ; MAP Kinase Signaling System ; Apoptosis