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Objective To investigate the role of KAT7 in cartilage cell and tissue ageing by establishing an over-replicating-induced primary mouse cartilage cell ageing model and a mouse natural ageing model.Methods Chon-drocytes of the mouse knee joint were obtained by type Ⅱ collagenase digestion and identified by toluidine blue stai-ning and Col Ⅱ staining.The age-related proteins and KAT7 expression levels in cartilage cells from different gener-ations of mice were discovered using Western blot and cellular immunofluorescence techniques,and the aging of the cells was assessed by SA-β-Gal coloring.The pathological alterations were examined in the joints of 22-month-old mice compared to 2-month-old mice using HE staining and safranin O-solid green staining.Additionally,immuno-histochemical analysis was done to observe the expression of KAT7 and p53 in mouse joint tissue.Results Com-pared with the control group,the expression levels of KAT7 protein and p21 and p53 in aged mouse chondrocytes significantly increased.WM-3835,a commonly inhibitor of KAT7 that possess the capacity on halting the protein expression procedure of gene KAT7 as well as p21 in ageing chondrocytes.SA-β-Gal staining showed a significant increase in positive staining of chondrocytes in the eighth generation(P8)compared to the first generation(P1).Compared with the cartilage tissue of young mice,the cartilage tissue of elderly mice presents a near-bone distribu-tion,with a decrease in cartilage surface integrity,a significant increase in the number of hypertrophic chondro-cytes,and more KAT7 and p53 cells that were positive.Conclusion The expression of KAT7 increases in the ageing chondrocytes and the cartilage tissue of ageing mice,reveales the potential significance of KAT7 correlated to cellular aging process in cartilage.
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Objective:To discuss the regulatory effect of physiological tensile stress on the differentiation of chondrocytes,and to clarify the associated signaling pathway mechanism.Methods:The ATDC5 chondrocytes were cultured in vitro and subjected to physiological tensile stress by four-point bending cell mechanical loading device.Initially,the cells were divided into control group and tensile stress group(2 000 μstrain/2 h group),and further divided into different stress magnitudes(1 000,2 000,and 3 000 μstrain)for 2 h,and 2 000 μstrain for different duration time(1,2,and 4 h)groups;the cells without tensile stress were used as control group.Real-time fluorescence quantitative PCR(RT-qPCR)method was used to detect the expression levels of type Ⅱ collagen(Col-Ⅱ),type Ⅹ collagen(Col-Ⅹ),aggregated proteoglycom(Aggrecan),sex-determining region Y-box protein 9(SOX9),vascular endothelial growth factor(VEGF),proliferating cell nuclear antigen(PCNA),Nel-like molecule tyep 1(Nell-1),Runt-related transcription factor 2(Runx2),Indian hedgehog(Ihh),patched homolog 1(Ptch-1),GLI family zinc finger protein 1(Gli-1),and hedgehog interacting protein 1(Hhip-1)mRNA in the cells in various groups;Western blotting method was used to detect the expression levels of Nell-1,Runx2,and Ihh proteins in the cells in various groups.The ATDC5 cells were divided into control group,cyclopamine group,tensile stress group,and cyclopamine + tensile stress group.RT-qPCR method was used to detect the expression levels of Nell-1,Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in various groups;Western blotting method was used to detect the expression levels of Nell-1 and Ihh proteins in the cells in various groups.Results:Compared with control group,the expression levels of Col-Ⅱ,Col-Ⅹ,Aggrecan,SOX9,VEGF,and PCNA mRNA in the cells in 2 000 μstrain/2 h group were significantly increased(P<0.01);after treated with 2 000 μstrain tensile stress for different duration time(1,2,and 4 h)or different tensile stresses(1 000,2 000,and 3 000 μstrain)for 2 h,compared with control group,the expression levels of Runx2 mRNA in the cells in other groups were increased with the prolongation of time or the increasing of tensile stress(P<0.01),and the expression levels of Nell-1,Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA were gradually increased(P<0.01),the expression levels reached the peaking at 2 000 μstrain/2 h,and then decreased but remained significantly higher than that in control group(P<0.01).The Western blotting results showed that the expression levels of Nell-1,Runx2,and Ihh proteins in the cells were consistent with the change trend of mRNA expression levels.After pre-treated with cyclopamine,compared with control group,the expression levels of Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in cyclopamine group were significantly decreased(P<0.01),and the expression levels of Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in tensile stress and cyclopamine+tensile stress groups were significantly increased(P<0.01);compared with cyclopamine group,the expression levels of Nell-1,Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in cyclopamine+tensile stress group were significantly increased(P<0.01);compared with tensile stress group,the expression levels of Ihh,Ptch-1,Gli-1,and Hhip-1 mRNA in the cells in cyclopamine + tensile stress group were significantly decreased(P<0.01).Compared with control group,the expression level of Ihh protein in the cells in cyclopamine group was significantly decreased(P<0.01),but there was no significant difference in expression level of Nell-1 protein in the cells between control group and cyclopamine group(P>0.05),while the expression levels of Nell-1 and Ihh proteins in the cells in tensile stress group and cyclopamine + tensile stress group were significantly increased(P<0.01);compared with cyclopamine group,the expression levels of Nell-1 and Ihh proteins in the cells in tensile stress group and cyclopamine + tensile stress group were significantly increased(P<0.01);compared with tensile stress group,in the expression levels of Nell-1 and Ihh proteins in the cells in cyclopamine + tensile stress group had no significant differences(P>0.05).Conclusion:After stimulated with physiological tensile stress,Nell-1 can activate the Ihh signaling pathway upstream,and regulate the differentiation of the ATDC5 chondrocytes.
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BACKGROUND:Circular RNAs(circRNAs)play important roles in a variety of diseases or tumors,and recent findings have revealed that circRNAs are abnormally expressed in knee osteoarthritis and are involved in disease progression through microRNA/mRNA regulation. OBJECTIVE:To investigate the effect of circRNA WD repeat containing protein 1(circ-BRWD1)/miR-488-3p/DNA methyltransferase 3A(DNMT3A)on the proliferation and apoptosis of chondrocytes in knee osteoarthritis. METHODS:Real-time fluorescence quantitative PCR was performed to detect the expression of circ-BRWD1,miR-488-3p,DNMT3A in knee osteoarthritis chondrocytes.Cells were divided into si-NC group,si-circ-BRWD1 group,vector group,circ-BRWD1 group,si-circ-BRWD1+anti-miR-NC group,si-circ-BRWD1+anti-miR-488-3p group,miR-NC group,miR-488-3p group,anti-miR-NC group,anti-miR-488-3p group,miR-488-3p+vector group,miR 488-3p+DNMT3A group.Real-time fluorescence quantitative PCR was used to detect circ-BRWD1,miR-488-3p,DNMT3A expression,MTT and flow cytometry assay were used to detect cell proliferation and apoptosis.Western blot assay was used to detect DNMT3A and proliferation/apoptosis-related protein expression.Dual luciferase reporter assay was used to Dual luciferase reporter assay to detect the targeting relationship of circ-BRWD1 with miR-488-3p and miR-488-3p with DNMT3A. RESULTS AND CONCLUSION:circ-BRWD1 and DNMT3A were highly expressed and miR-488-3p was lowly expressed in knee osteoarthritis chondrocytes compared with normal chondrocytes.Knockdown of circ-BRWD1 or overexpression of miR-488-3p inhibited proliferation and induced apoptosis in knee osteoarthritis chondrocytes.circ-BRWD1 targeted negative regulation of miR-488-3p and inhibition of miR-488-3p reversed the effect of circ-BRWD1 knockdown on chondrocyte proliferation and apoptosis in knee osteoarthritis.miR-488-3p targeted negative regulation of DNMT3A and upregulation of DNMT3A reversed the effect of miR-488-3p overexpression on chondrocyte proliferation and apoptosis in knee osteoarthritis.circ-BRWD1 could regulate the expression of DNMT3A by regulating miR-488-3p.To conclude,knockdown of circ-BRWD1 inhibits chondrocyte proliferation and induces apoptosis in knee osteoarthritis,and the mechanism of action may be related to the regulation of miR-488-3p/DNMT3A axis.
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BACKGROUND:Establishing a chondrocyte model of osteoarthritis is of great significance for further explaining the pathological process of osteoarthritis and evaluating and screening the therapeutic drugs of osteoarthritis. OBJECTIVE:To evaluate the effect of interleukin-1β to induce osteoarthritis models in rat chondrocyte models,thereby providing a reference for further exploration of drug treatment of osteoarthritis. METHODS:Chondrocytes were isolated from the hip cartilage of 3-week-old Sprague-Dawley rats by mechanical shearing and enzymatic digestion,and then identified.Chondrocytes were randomly divided into three groups:control group,5 ng/mL interleukin-1β-induced group,10 ng/mL interleukin-1β-induced group,with induction times of 24 and 48 hours.Chondrocyte proliferation activity was detected by MTT.Real-Time PCR was used to detect the expression of type Ⅱ collagen,Aggrecan,sex-determining region Y-box protein 9(Sox9),matrix metalloproteinase 13,and a disintegrin and metaloproteinase with thrombospondin-like motifs-5(Adamts5)mRNA.Western blot was used to detect the expression of type Ⅱ collagen,Sox9,matrix metalloproteinase 13 and Adamts5. RESULTS AND CONCLUSION:Primary rat chondrocytes were successfully isolated and cultured.Induction of chondrocytes by interleukin-1β at 10 ng/mL for 24 hours could significantly reduce cell proliferation and viability(P＜0.05),while the 5 ng/mL interleukin-1β-induced group required 48 hours of induction to cause a significant decrease in cell proliferation and viability.Real-Time PCR results showed that compared with the control group,5 or 10 ng/mL interleukin-1β induction for 24 and 48 hours significantly reduced the expression levels of type Ⅱ collagen,Aggrecan,Sox9 mRNAs(P＜0.05)and increased the expression levels of matrix metalloproteinase 13 and Adamts5 mRNAs(P＜0.05).Compared with the 10 ng/mL interleukin-1β-induced group,5 ng/mL interleukin-1β induction significantly increased the mRNA expression of matrix metalloproteinase 13 and Adamts5 in chondrocytes after 48 hours of induction(P＜0.05).Western blot results showed that compared with the control group,10 ng/mL interleukin-1β induction for 24 hours and 5 ng/mL interleukin-1β induction for 48 hours significantly decreased the protein expression of type Ⅱ collagen and Sox9 in chondrocytes(P＜0.05),and significantly increased the protein expression of matrix metalloproteinase 13 and Adamts5(P＜0.05).To conclude,compared with 5 ng/mL interleukin-1β,10 ng/mL interleukin-1β may have more obvious effects on chondrocytes for 24 hours,while 5 and 10 ng/mL interleukin-1β have similar effects after 48 hours of intervention.
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BACKGROUND:Increasing evidence suggests that N6-methyladenosine(m6A)regulators are closely associated with osteoarthritis and are considered to be a new direction in the prevention and treatment of osteoarthritis,but their specific mechanism of action is unknown. OBJECTIVE:To conduct a bioinformatics analysis of the osteoarthritis gene microarray dataset in order to explore the role of m6A in osteoarthritis and analyze the pathogenesis of osteoarthritis. METHODS:The m6A regulators associated with osteoarthritis and their expression were first extracted from the GSE1919 dataset in the GEO database using R software,and then the results were analyzed by gene difference analysis and GO and KEGG enrichment analyses.Subsequently,the results of protein-protein interaction network topology analysis and machine learning results were intersected to obtain the m6A Hub regulators,which were validated by in vitro cellular experiments. RESULTS AND CONCLUSION:A total of 16 osteoarthritis-related m6A regulators were extracted and 11 m6A differential regulators,including ZC3H13,YTHDC1,YTHDF3 and HNRNPC,were obtained by differential analysis.GO enrichment analysis showed that osteoarthritis-related m6A differential regulators played a role in the biological processes such as mRNA transport,RNA catabolism,and regulation of insulin-like growth factor receptor signaling pathway.(3)KEGG enrichment analysis showed that the differential regulators were mainly involved in the p53,interleukin-17 and AMPK signaling pathways.The combined protein-protein interaction network topology analysis and machine learning results obtained the m6A Hub regulator-YTHDC1.(5)The results of in vitro cellular experiments showed that there was a significant difference in the expression of m6A key regulator between the control and experimental groups(P<0.05).To conclude,YTHDC1 is closely related to the development of osteoarthritis,which is expected to be a molecular target of m6A for the treatment of osteoarthritis.
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BACKGROUND:Growth differentiation factor 5 is a member of the transforming growth factor superfamily and one of the earliest markers of joint development.Growth differentiation factor 5 has an important role in cartilage repair. OBJECTIVE:To explore the action mechanism of growth differentiation factor 5-induced chondrogenic differentiation of bone marrow mesenchymal stem cells. METHODS:Rabbit bone marrow mesenchymal stem cells were isolated and cultured.CCK-8 assay was used to detect the effect of different mass concentrations of growth differentiation factor 5 on the proliferation activity of bone marrow mesenchymal stem cells.RT-PCR was utilized to detect the expression of genes related to chondrogenic differentiation of bone marrow mesenchymal stem cells induced by different mass concentrations of growth differentiation factor 5.To further investigate the action mechanism of growth differentiation factor 5-induced chondrogenic differentiation of bone marrow mesenchymal stem cells,we added inhibitor XAV-939 and activator Laduviglusib of Wnt/β-catenin signaling pathways to induce cell culture for 14 days.RT-PCR and western blot assay were performed to detect the expression of cartilage-related genes and Wnt/β-catenin signaling pathway proteins. RESULTS AND CONCLUSION:(1)CCK-8 results showed no significant effect of growth differentiation factor 5 on the proliferation of bone marrow mesenchymal stem cells.(2)Growth differentiation factor 5 promoted the expression of cartilage-related genes type Ⅱ collagen,aggrecan and Sox9,among which growth differentiation factor 5 induced a significant upregulation of cartilage-related genes in the 50 ng/mL group.(3)Addition of Laduviglusib,an activator of Wnt/β-catenin signaling pathway,upregulated Sox9,β-catenin and type Ⅱ collagen expression(P<0.05).Addition of XAV939,an inhibitor of Wnt/β-catenin signaling pathway,down-regulated Sox9,β-catenin and type Ⅱ collagen expression(P<0.05).(4)Taken together,growth differentiation factor 5-induced chondrogenic differentiation of bone marrow mesenchymal stem cells may be associated with the activation of the Wnt/β-catenin signaling pathway.
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BACKGROUND:Studies have found that chondrocyte ferroptosis can be used as an important pathogenesis to induce the occurrence and development of osteoarthritis.With the continuous development of Chinese medicine,some scholars have found that some traditional Chinese medicine monomers and traditional Chinese medicine compounds can inhibit chondrocyte ferroptosis through various mechanisms of action,and finally play a role in the treatment of osteoarthritis. OBJECTIVE:To explore the relationship between ferroptosis and osteoarthritis and the mechanism by which traditional Chinese medicine deals with ferroptosis in the treatment of osteoarthritis,in order to provide new ideas for the treatment and prevention of osteoarthritis. METHODS:With"osteoarthritis,ferroptosis,chondrocytes,lipid metabolism,traditional Chinese medicine,ROS,GPX 4"as the English and Chinese search terms,CNKI,PubMed,WanFang,and VIP databases were searched for relevant articles regarding the relationship between ferroptosis and osteoarthritis and its traditional Chinese medicine intervention until 2022.Then,a systematic analysis was conducted. RESULTS AND CONCLUSION:Intracellular iron overload will cause lipid peroxidation,resulting in the accumulation of reactive oxygen species and eventually the occurrence of ferroptosis,while excessive iron will accelerate the apoptosis of chondrocytes and affect chondrocyte homeostasis,thereby inducing the development of osteoarthritis.When amino acid metabolism is abnormal,an imbalance in glutamate and cystine exchange causes the accumulation of glutamate outside the cells,and high extracellular concentration of glutamate will cause the depletion of glutathione,indirectly inhibiting the function of ferroptosis-related factors,and contributing to ferroptosis.When cellular lipid metabolism is abnormal,unsaturated fatty acids,an important component of the cell membrane,lose their diallyl hydrogen atoms,leading to the destruction of cells to induce ferroptosis,while lipid metabolism is closely involved in the progression of osteoarthritis.Traditional Chinese medicine can play a role in the prevention and treatment of osteoarthritis by inducing the occurrence of ferroptosis.The research on iron death is still immature,and further research on its action mechanism is expected to open up new ways for the clinical treatment of osteoarthritis.
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BACKGROUND:Grape seed extract can inhibit chondrocyte apoptosis and aging,and improve osteoarthritis.However,the effects of grape seed extract on the apoptosis of chondrocytes in the growth plate and tibial growth are still unclear. OBJECTIVE:To investigate the effect of grape seed extract on interleukin-1β-induced apoptosis in rat growth plate cells and on tibial bone growth. METHODS:(1)Cell experiment:Growth plate chondrocytes from Sprague-Dawley rats were isolated,cultured,and identified.The cells were then randomly divided into control group,model group,grape seed extract group,miR-138-5p NC group and miR-138-5p inhibitor group.In the model group,20 ng/mL interleukin-1β was used to induce apoptosis in rat growth plate chondrocytes.In the grape seed extract group,20 ng/mL interleukin 1β was added along with 10 μmol/L grape seed extract solution for 48 hours.Cells in the miR-138-5p NC and inhibitor groups were transfected with 5 nmol/L miR-138-5p NC and 5 nmol/L miR-138-5p inhibitor for 12 hours,respectively,followed by addition of 20 ng/mL interleukin-1β.qRT-PCR was used to detect miR-138-5p and caspase-3 expression.Luciferase reporter assay was used to analyze the relationship between miR-138-5p and caspase-3 targeting.Cell counting kit-8 was used to detect cell proliferation activity.Flow cytometry was used to detect cell apoptosis.Caspase-3 and Bcl-2 protein expressions were detected by western blot.(2)Animal experiment:The animals were divided into normal control group,grape seed extract group and miR-138-5p inhibitor group.The effects of grape seed extract on epiphyseal closure and tibial growth of the tibial plateau in rats were observed. RESULTS AND CONCLUSION:miR-138-5p had a targeting relationship with caspase-3.Compared with the control group,cell proliferation was significantly reduced,apoptosis was significantly increased(P＜0.01),miR-138-5p,Bcl-2 expression was reduced(P＜0.01),and caspase-3 expression was increased(P＜0.01)in the model group.Compared with the mod group,the grape seed extract group showed a significant increase in cell proliferation,a significant decrease in apoptosis(P＜0.01),an increase in miR-138-5p and Bcl-2 expression(P＜0.01)and a decrease in caspase-3 expression(P＜0.01).Compared with the grape seed extract group,the miR-138-5p inhibitor group showed a significant decrease in cell proliferation,a significant increase in apoptosis(P＜0.01),a decrease in miR-138-5p and Bcl-2 expression(P＜0.05 or P＜0.01),and an increase in caspase-3 expression(P＜0.05).Intragastric administration of grape seed extract could delay epiphyseal closure of the tibial plateau and promote tibial bone growth in rats,whereas miR-138-5p inhibitor intervention inhibited the effect of grape seed extract on tibial bone growth in rats.To conclude,grape seed extract can inhibit apoptosis of rat growth plate chondrocytes through regulating the miR-138-5p/caspase-3 pathway,improve epiphyseal closure of rat tibial plateau and promote tibial bone growth.
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BACKGROUND:With the deepening of the aging of the world population,the prevalence rate of osteoarthritis is increasing.In recent years,more and more attention has been paid to the study of osteoarthritis.Studies have shown that autophagy and apoptosis are strongly associated with the occurrence and development of osteoarthritis,and play an important role in it. OBJECTIVE:To review the molecular mechanisms of the interaction between autophagy and apoptosis in osteoarthritis,aiming to explore the relationship between autophagy and apoptosis in osteoarthritis and the coupling mechanism of the two to mediate the occurrence and development of osteoarthritis,so as to provide new ideas for the treatment of osteoarthritis. METHODS:The Chinese and English key words"osteoarthritis,autophagy,apoptosis"were searched in the CNKI and PubMed.After screening by reading the title,abstract and key words,the relevant literature was carefully read.After excluding studies unrelated to the content of the paper and repetitive studies,68 articles were finally included for the summary. RESULTS AND CONCLUSION:(1)The occurrence and development of osteoarthritis are related to autophagy and apoptosis of chondrocytes.Autophagy protects chondrocytes from stress damage,but excessive autophagy also induces or promotes chondrocyte apoptosis and reduces the survival rate of chondrocytes.The two perturb each other to regulate the degeneration of articular cartilage.(2)miRNA,Beclin-1 and oxidative stress are all involved in the regulation of autophagy and apoptosis on osteoarthritis,and affect the development of osteoarthritis.
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BACKGROUND:Grape seed extract has been shown to be effective in inhibiting the growth of androgen-dependent tumors(e.g.,breast cancer),and thus grape seed extract could theoretically inhibit epiphyseal closure induced by estrogen in late adolescence. OBJECTIVE:To screen the effects of grape seed extract on apoptosis of growth plate chondrocytes and epiphyseal closure in rats. METHODS:(1)In vitro experiment:Growth plate chondrocytes from rat large tibia and femur at logarithmic growth stage were obtained and cultured in groups:normal control group,model control group(adding 17β-estradiol to induce apoptosis),positive control group(adding letrozole and 17β-estradiol),grape seed extract group(adding 17β-estradiol and 10 μg/mL grape seed extract),Caspase-9 inhibitor group(adding 17β-estradiol and Caspase-9 inhibitor),Caspase-9 agonist group(adding 17β-estradiol and Caspase-9 agonist).Cell apoptosis was detected by flow cytometry after 48 hours of culture.(2)In vivo experiment:Thirty 3-month-old Sprague-Dawley rats were randomly divided into model control group,positive control group and low-,medium-and high-dose groups,with five rats in each group.All rats were injected subcutaneously with 17β-estradiol(3 times per week)to establish epiphyseal closure models,followed by intragastric administration of letrozole in positive control group and 0.05,0.2 and 0.8 g/kg grape seed extract in low-,medium-and high-dose groups,respectively,once a day until over 2/3 of the epiphyseal plate in the model control group was closed.The length of the tibia was then observed.Another 18 Sprague-Dawley rats were randomly divided into model control group,positive control group,and medium-dose group,with 6 rats in each group,treated as above for 1.5 continuous months.The expression of Caspase-9 protein in rat growth plate cartilage was detected by western blot. RESULTS AND CONCLUSION:(1)In vitro experiment:17β-estradiol could induce apoptosis in growth plate chondrocytes,and letrozole,grape seed extract,and caspase-9 inhibitors could all inhibit apoptosis in growth plate chondrocytes.(2)In vivo experiment:When more than 2/3 of the epiphyseal plate in the model control group was closed,the number of rats with epiphysis closure in the positive control and medium-dose groups was less than that in the model control group(P＜0.05),and the tibial length was longer than that in the model control group(P＜0.05),and the Caspase-9 protein expression in the tibial growth plate was lower than that in the model control group(P＜0.05).To conclude,the appropriate dose of grape seed extract can effectively inhibit the apoptosis of growth plate chondrocytes and delay epiphyseal closure,which has the potential to promote bone growth.
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BACKGROUND:Hypoxia is strongly associated with the development and progression of osteoarthritic chondrocyte injury,but the specific targets and regulatory mechanisms are unclear. OBJECTIVE:A machine learning approach was used to identify KDEL(Lys-Asp-Glu-Leu)receptor 3(KDELR3)as a characteristic gene for osteoarthritis hypoxia and immune infiltration analysis,to provide new ideas and methods for the treatment of osteoarthritis. METHODS:The osteoarthritis-related datasets were downloaded from the GEO database and the GSEA website to obtain hypoxia-related genes.The osteoarthritis datasets were batch-corrected and immune infiltration analyzed using R language,and osteoarthritis hypoxia genes were extracted for differential analysis.Differentially expressed genes were analyzed for GO function and KEGG signaling pathway.Weighted correlation network analysis(WGCNA)and machine learning were also used to screen osteoarthritis hypoxia signature genes,and in vitro cellular experiments were performed to validate expression and correlate immune infiltration analysis using the datasets and qPCR. RESULTS AND CONCLUSION:(1)8492 osteoarthritis genes were obtained by batch correction and principal component analysis,mainly strongly associated with immune cells such as Macrophages M2 and Mast cells resting;200 hypoxia genes were also obtained,resulting in 41 osteoarthritis hypoxia differentially expressed genes.(2)GO analysis involved mainly biological processes such as response to nutrient levels and glucocorticoids;cellular components such as lysosomal lumen and Golgi lumen;and molecular functions such as 14-3-3 protein binding and DNA-binding transcriptional activator activity.(3)KEGG analysis of osteoarthritis hypoxia differentially expressed genes was associated with signaling pathways such as PI3K-Akt,FoxO,and microRNAs in cancer.(4)The characteristic gene KDELR3 was obtained after using WGCNA analysis and machine learning screening.(5)The gene expression of KDELR3 was found to be higher in the test group than in the control group in the synovium(P=0.014)but lower in the meniscus(P=0.024)after validation by gene microarray.(6)In vitro chondrocyte assay showed that the expression of KDELR3 was higher in cartilage than in the control group(P=0.005),while KDELR3 was closely associated with Macrophages M0(P=0.014)and T cells follicular helper(P=0.014).Using a machine learning approach,we confirmed that KDELR3 can be used as a hypoxic signature gene for osteoarthritis and may intervene in osteoarthritis pathogenesis by improving hypoxia,expecting to provide a new direction for better treatment of osteoarthritis.
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BACKGROUND:The Yi people have used Sambucus adnata Wall to treat fractures,bruises,arthritis,etc.The author's group found that the active site aqueous extract(SAW-A)and dichloromethane extract(SAW-B)can promote fracture healing by promoting the expression of genes related to osteoblast proliferation,differentiation and maturation,differentiation and maturation.However,the therapeutic effect of methanol extract(SAW-C)at its active site on osteoarthritis is unclear. OBJECTIVE:To investigate the therapeutic effect of Sambucus adnata Wall extract on osteoarthritis,and to identify the effective targets of Sambucus adnata Wall extract in the treatment of osteoarthritis by network pharmacology technology. METHODS:A rat osteoarthritis model was replicated by anterior cruciate ligamentectomy and model rats were then treated with methanol extract of Sambucus adnata Wall by gavage for 21 days.On the 21st day after modeling,the knee joint of rats was detected by X-ray,the width of the knee joint was measured,oxidative stress indexes and inflammatory factors levels in serum and joint lavage fluid were detected,the morphology of the knee joint was observed by hematoxylin-eosin staining,full-thickness cartilage and hyaline cartilage thickness were measured,and the content of articular cartilage proteoglycan was observed by safranin O-fast green staining.The"drug-component-disease-target"network was constructed.Gene ontology enrichment analysis and Kyoto encyclopedia of genes and genomes enrichment analysis of effective targets were performed,and protein-protein interaction network maps were constructed using cytoscape software. RESULTS AND CONCLUSION:Sambucus adnata Wall extract could reduce tumor necrosis factor-α level in joint lavage fluid and serum levels of prostaglandin E2 and malondialdehyde,while increase the level of superoxide dismutase;relieve joint swelling caused by osteoarthritis;improve the histopathological state of articular cartilage,maintain the thickness of full-thickness articular cartilage,hyaline cartilage and the area of bone trabeculae in subchondral bone;and effectively prevent the loss of proteoglycans in articular cartilage and have a chondroprotective effect.Network pharmacological results showed that the methanol extract of Sambucus adnata Wall may have some targets related to inhibition of tumor necrosis factor,AKT1,interleukin-6,MAPK3,and SRC as well as inhibition of over-activation of EGFR signaling pathway and AGE-RAGE signaling pathway.
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BACKGROUND:Heterotopic ossification of skeletal muscle is a clinically serious complication.For heterotopic ossification of skeletal muscles,the cells involved in the process of heterotopic ossification remain unclear. OBJECTIVE:To investigate the involvement of myocytes,fascia cells,and endothelial cells in the process of heterotopic ossification in skeletal muscle and to observe the cell origin of heterotopic ossification in skeletal muscle induced by bone morphogenetic protein 4. METHODS:Both C2C12 cells and the myotubes formed by the C2C12 cells in the induction medium were cultured,and 500 ng/mL bone morphogenetic protein 4 was added to the medium respectively,and whether the C2C12 cells and myotubes continued to proliferate within 10 days under the treatment were observed under a microscope.Myogenic cells(L6,derived from rats)and fibroblast-derived cells(derived from human)were co-cultured.After treatment with 500 ng/mL bone morphogenetic protein 4 and 10 ng/mL transforming growth factor-β,osteogenic and chondrogenic differentiation potential within 21 days were observed using Safranine O staining and Alcian blue staining.Using transgenic animal FVB/N-TgN(TIE2-LacZ)182Sato mice,15 μL of adeno-associated virus-bone morphogenetic protein 4(5×1010 PFU/mL)were implanted in the thigh muscle space of genetic mice for 10 and 14 days.X-gal staining was used to observe the formation of new blood vessel endothelium in the differentiated bone. RESULTS AND CONCLUSION:(1)Bone morphogenetic protein 4 caused myotube breakdown and increased C2C12 cell proliferation.Compared with other groups,the pure fibroblast-derived cell group had a higher area of positive alcian blue and safarin O staining(P<0.05)and a lower area of alkaline phosphatase staining(P<0.05),while the pure L6 group had a bigger area of alkaline phosphatase staining(P<0.05)but a smaller area of positive alcian blue and safarin O staining(P<0.05).(2)Transplantation of adeno-associated virus-bone morphogenetic protein 4-adsorbed gelatin sponge into FVB/N-TgN(TIE2-LacZ)182Sato mice resulted in heterotopic ossification.(3)X-gal staining results demonstrated that there was no obvious staining in chondrocytes and differentiated bones and Tie2+ endothelial cells did not participate in the formation of the alienated bone.(4)These findings verify that fibroblasts are the primary source of osteoblasts during the adeno-associated virus-bone morphogenetic protein 4-induced ectopic endochondral ossification in skeletal muscle,but myogenic cells are the main source of osteoblasts.Tie2+ endothelial cells might not be the cell source for cartilage and bone.
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BACKGROUND:Studies have shown that hesperetin exerts protective effects on chondrocytes through a variety of mechanisms or signaling pathways,but the protective mechanisms have not been fully elucidated. OBJECTIVE:To investigate the effect of hesperetin on lipopolysaccharide-induced inflammatory degeneration of chondrocytes. METHODS:Knee joint chondrocytes from suckling Sprague-Dawley rats were isolated and cultured in vitro,and identified by Safranine O staining.The cytotoxicity of hesperetin on chondrocytes was determined by the MTT assay to ensure the optimal concentration of hesperetin.Chondrocytes were randomly divided into three groups,including the control group,model group,and experimental group.The cellular model of osteoarthritis was established in the latter two groups by simulating chondrocytes with lipopolysaccharide.Chondrocytes in the experimental group was then intervened with hesperetin for 24 hours.Calcein-AM/EthD-I staining was used to detect cell viability.Immunohistochemical staining was performed to determine the expression of type Ⅱ collagen in chondrocytes.Intracellular reactive oxygen species level was detected by a reactive oxygen species detection kit.Total glutathione level was detected by ELISA.Real-time fluorescent PCR was employed to detect the expression of interleukin 1β,interleukin 6,tumor necrosis factor α and type Ⅱ collagen. RESULTS AND CONCLUSION:Safranine O staining results showed that the cells extracted were chondrocytes.Cytotoxicity test results showed 0.5 μmol/L hesperetin had the most significant effect on chondrocyte vitality.Compared with the control group,the model group showed a decrease in chondrocyte proliferation ability,an increase in reactive oxygen species levels,a decrease in total glutathione levels,an increase in type Ⅱ collagen degradation,an increase in the levels of interleukin 1β,interleukin 6,and tumor necrosis factor α,and a decrease in the expression of type Ⅱ collagen(P＜0.05).Compared with the model group,in the experimental group,the proliferation ability of chondrocytes increased,reactive oxygen species levels decreased,total glutathione levels increased,and type Ⅱ collagen degradation decreased,levels of interleukin 1β,interleukin 6,and tumor necrosis factor α downregulated,and the expression of type Ⅱ collagen upregulated(P＜0.05).To conclude,hesperetin has a protective effect on lipopolysaccharide-induced inflammatory degeneration of osteoarthritic chondrocytes,and the mechanism may be associated with inhibition of reactive oxygen species-mediated oxidative stress.
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BACKGROUND:Upregulation of hedgehog protein signaling can increase the expression of osteoarthritis markers,Runx2,a disintegrin and metalloproteinase with thrombospondin motifs,collagen type X alpha 1,and matrix metalloproteinase 13,while inhibition of hedgehog proteins attenuates the severity of osteoarthritis.It is speculated that osteoarthritic chondrocytes can influence bone formation by affecting osteoblasts through the Indian hedgehog protein(IHH)signaling pathway. OBJECTIVE:To investigate the effect of human osteoarthritic chondrocytes on subchondral osteoblasts. METHODS:Tibial plateau specimens from patients with osteoarthritis were collected.Chondrocytes were extracted using enzymatic digestion,and osteoblasts were extracted using enzymatic pre-digestion + bone block method.Chondrocytes were identified by toluidine blue staining and immunofluorescence and osteoblasts were identified by alkaline phosphatase staining and immunofluorescence.Chondrocytes were cultured in sodium alginate beads to maintain chondrocyte phenotype and co-cultured with osteoblasts.The co-culture system was added with IHH signaling pathway inhibitor(cyclopamine,10 nmol/L)and activator(purmorphamine,10 nmol/L)separately.After 48 hours of co-culture,osteoblasts from each group were collected,mRNA expressions of Gli1,osteoprotegerin,Runx2,parathyroid hormone-related peptide,alkaline phosphatase,receptor activator of nuclear factor-kB ligand(RANKL)and osteocalcin were detected by qRT-PCR,and protein expressions of GLi1,oseoprotegerin and RANKL in osteoblasts were detected by western blot. RESULTS AND CONCLUSION:The mRNA expression levels of GLi1,osteoprotegerin and RUNX2 in osteoblasts were significantly increased,while the mRNA expression levels of parathyroid hormone-related peptide were decreased(P＜0.05)when co-cultured with human osteoarthritic chondrocytes.The mRNA and protein levels of Gli1 were significantly decreased after the addition of IHH signaling pathway inhibitor(cyclopamine)(P＜0.05),and the mRNA and protein levels of Gli1 were significantly increased after the addition of IHH signaling pathway activator(purmorphamine)(P＜0.05).Osteoprotegerin showed the same trend as Gli1 in the experiment.The osteoprotegerin/RANKL ratio followed the same trend as osteoprotegerin.To conclude,human osteoarthritic chondrocytes can promote the expression of Gli1,osteoprotegerin,Runx2 and other proteins in osteoblasts.The upregulation of osteoprotegerin is related to the IHH signaling pathway.Osteoarthritic chondrocytes can up-regulate the expression of osteoprotegerin in osteoblasts through the IHH signaling pathway and thus up-regulate the osteoprotegerin/RANKL ratio,which will contribute to bone formation in subchondral bone.
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BACKGROUND:Previous studies have shown that silent mating-type information regulator 2 homolog 1(SIRT1)-mechanistic target of rapamycin(mTOR)signaling plays an important role in the progression of osteoarthritis.Emodin has a protective effect on osteoarthritic chondrocytes. OBJECTIVE:To investigate the effects of emodin on the proliferation,apoptosis and oxidative stress of osteoarthritic chondrocytes based on the SIRT1-mTOR signaling. METHODS:Rat chondrocytes were isolated and cultured in vitro.Osteoarthritic chondrocyte model in vitro was induced by 10 ng/mL interleukin-1β.Cell counting kit-8 method was used to determine the viability of rat chondrocytes treated with 0,20,40,80,120,160 μmol/L emodin,and the appropriate concentration of emodin was selected.Rat chondrocytes isolated and cultured in vitro were randomly divided into control group,model group,low-dose emodin group,high-dose emodin group,EX527 group,and high-dose emodin+EX527 group.In vitro osteoarthritis model was constructed by induction of 10 ng/mL interleukin 1β in all groups except the control group.The cells in the latter four groups were correspondingly treated with emodin or/and EX527.The proliferation and apoptosis of chondrocytes in each group were detected by cell counting kit-8,Edu staining and flow cytometry respectively.The relative content of reactive oxygen species and the levels of malondialdehyde,superoxide dismutase,catalase,and glutathione peroxidase in chondrocytes of rats in each group were measured with the kit.The expression of proteins related to cell matrix degradation,apoptosis and the SIRT1-mTOR pathway-related proteins in each group were detected by western blot. RESULTS AND CONCLUSION:Compared with the control group,the survival rate of chondrocytes,the positive rate of Edu,the levels of superoxide dismutase,catalase,and glutathione peroxidase,and the expression of Bcl-2 and SIRT1 proteins in the model group were decreased,while the apoptosis rate,the relative content of reactive oxygen species,the level of malondialdehyde,the expression of Bax,matrix metalloproteinase 3,matrix metalloproteinase 9 proteins,and p-mTOR/mTOR were increased(P<0.05).Compared with the model group,the survival rate of chondrocytes,the positive rate of Edu,the levels of superoxide dismutase,catalase,and glutathione peroxidase,and the expression of Bcl-2 and SIRT1 proteins in the low-and high-dose emodin groups were increased,while the apoptosis rate,the relative content of reactive oxygen species,the level of malondialdehyde,the expression of Bax,matrix metalloproteinase 3,matrix metalloproteinase 9 proteins,and p-mTOR/mTOR were decreased(P<0.05).Compared with the low-and high-dose emodin groups,the indexes of EX527 group showed the opposite trend(P<0.05).Compared with the high-dose emodin group,the survival rate of chondrocytes,the positive rate of Edu,the levels of superoxide dismutase,catalase,and glutathione peroxidase,and the expression of Bcl-2 and SIRT1 proteins in the high-dose emodin+EX527 group were decreased,while the apoptosis rate,the relative content of reactive oxygen species,the level of malondialdehyde,the expression of Bax,matrix metalloproteinase 3,matrix metalloproteinase 9 proteins,and p-mTOR/mTOR were increased(P<0.05).To conclude,emodin can inhibit oxidative stress of osteoarthritic chondrocytes by activating the SIRT1-mTOR signaling,thereby promoting chondrocyte proliferation and reducing apoptosis.
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BACKGROUND:Long intergenic non-protein coding RNA 00707(LINC00707)and microRNA-423-5p(miR-423-5p)are both involved in the occurrence and development of osteoarthritis.Starbase predicts that LINC00707 and miR-423-5p have complementary sequences,but whether LINC00707 and miR-423-5p interact to regulate the progress of osteoarthritis still needs further research. OBJECTIVE:To investigate whether LINC00707 targets miR-423-5p to affect chondrocyte injury and inflammatory factor secretion in osteoarthritis. METHODS:Articular chondrocytes were divided into eight groups:(1)blank control group was given no treatment;(2)interleukin(IL)-1β group was cultured with 10 ng/mL IL-1β for 48 hours;(3)IL-1β+si-NC group was transfected with si-NC and then treated with 10 ng/mL IL-1β for 48 hours;(4)IL-1β+si-LINC00707 group was transfected with si-LINC00707 and then treated with 10 ng/mL IL-1β for 48 hours;(5)IL-1β+miR-NC group was transfected with miR-NC and then treated with 10 ng/mL IL-1β for 48 hours;(6)IL-1β+miR-423-5p group was transfected with miR-423-5p mimic and then treated with 10 ng/mL IL-1β for 48 hours;(7)IL-1β+si-LINC00707+anti-miR-NC group was co-transfected with si-LINC00707 and anti-miR-NC and then treated with 10 ng/mL IL-1β for 48 hours;(8)IL-1β+si-LINC00707+anti-miR-423-5p group was co-transfected with si-LINC00707 and anti-miR-423-5p and then treated with 10 ng/mL IL-1β for 48 hours.Relevant tests were performed at the end of the intervention. RESULTS AND CONCLUSION:Compared with the blank control group,the mRNA expression of LINC00707,apoptosis rate,protein expression of C-caspase3 and C-caspase9,and levels of tumor necrosis factor-α and IL-6 in articular chondrocytes were increased in the IL-1β group,while there was a decrease in miR-423-5p expression and IL-10 level(P<0.05).Compared with the IL-1β group,the mRNA expression of LINC00707,apoptosis rate,protein expression of C-caspase3 and C-caspase9,and levels of tumor necrosis factor-α and IL-6 in articular chondrocytes were decreased in the IL-1β+si-LINC00707 group,while miR-423-5p expression and IL-10 level increased(P<0.05).Compared with the IL-1β+miR-NC group,the protein expression of C-caspase3 and C-caspase9 and levels of tumor necrosis factor-α and IL-6 in articular chondrocytes were decreased in the IL-1β+miR-423-5p group,while miR-423-5p expression and IL-10 level increased(P<0.05).Compared with the IL-1β+si-LINC00707+anti-miR-NC group,apoptosis rate,protein expression of C-caspase3 and C-caspase9,and levels of tumor necrosis factor-α and IL-6 in articular chondrocytes were increased in the IL-1β+si-LINC00707+anti-miR-423-5p group,while miR-423-5p expression and IL-10 level decreased(P<0.05).To conclude,inhibiting LINC00707 by targeting miR-423-5p can reduce IL-1β-induced apoptosis and inflammation in articular chondrocytes.
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BACKGROUND:The content of serum thrombin in patients with osteoarthritis is significantly higher than that in normal individuals,and thrombin can induce inflammatory degeneration of rat chondrocytes,suggesting that inhibiting the function of thrombin may become a method for treating osteoarthritis.Celecoxib is a common therapeutic drug for the clinical treatment of osteoarthritis.It is not yet known whether it improves chondrocyte degeneration by inhibiting the activity of thrombin. OBJECTIVE:To investigate the effect of celecoxib on thrombin-induced degeneration of rat chondrocytes. METHODS:Thrombin levels in the serum of osteoarthritis patients and normal individuals were detected by an ELISA kit.Primary chondrocytes of neonatal Sprague-Dawley rats were isolated,and all experiments were performed with cells from passage one.Chondrocytes were randomly divided into three groups:control group,thrombin group,and celecoxib group.The cell morphology of the three groups was observed under an inverted microscope,and an Edu kit was used to detect the cell proliferation.qRT-PCR was used to detect the expression of extracellular matrix components(aggrecan,elastin,cartilage oligomeric matrix proteins),inflammatory factors(interleukin-1,interleukin-6,and tumor necrosis factor-α),and chemokines(monocyte chemotactic protein 2,monocyte chemotactic protein 7,granulocyte chemotactic protein 6).The expression of type 2 collagen α1 was detected by immunofluorescence.Western blot method was used to detect the expression of catabolic metabolism genes,such as matrix metalloproteinase 9,matrix metalloproteinase 13,and cyclooxygenase 2. RESULTS AND CONCLUSION:Patients with osteoarthritis had higher levels of thrombin in the serum compared with normal individuals.Under the microscope,celecoxib was found to significantly inhibit fibroid changes in chondrocytes.Compared with the thrombin group,celecoxib inhibited the proliferation of chondrocytes.The downregulation of extracellular matrix gene expression,such as type II collagen α1,in the thrombin group was inhibited by celecoxib(P<0.05).Thrombin promoted the expression of inflammatory factors(interleukin-1,interleukin-6,and tumor necrosis factor-α),chemokines(monocyte chemotactic protein 2,monocyte chemotactic protein 7,granulocyte chemotactic protein 6),as well as catabolic genes(matrix metalloproteinase 9,matrix metalloproteinase 13,and cyclooxygenase 2),and under the intervention of celecoxib,the expression of these genes could be downregulated(P<0.05).Overall,these findings indicate that celecoxib inhibits the pro-inflammatory effects of thrombin and thereby ameliorates chondrocyte degeneration in rats.
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BACKGROUND:Acupotomy is an effective method for the clinical treatment of osteoarthritis,with affirmed clinical outcomes,but the specific mechanisms remain unclear OBJECTIVE:To investigate the role of acupotomy in modulating chondrocyte autophagy to promote chondrocyte homeostasis in osteoarthritis. METHODS:Twenty-eight New Zealand rabbits were randomly divided into control group,osteoarthritis group,acupotomy group,and hyaluronic acid group,with seven rabbits in each group.The knee osteoarthritis rabbit model was prepared using the Videman method in the latter three groups.After modeling,the control group and osteoarthritis group received no interventions.The acupotomy group received acupotomy treatment 15 minutes per time,once a week,while the hyaluronic acid group received intra-articular injection of hyaluronic acid once a week,with a continuous treatment duration of 5 weeks.The day after the final intervention,knee joint macrostructure was observed using DR imaging,chondrocyte ultrastructure was examined through transmission electron microscopy,apoptosis of chondrocytes was assessed using Tunel staining,and western blot analysis was used to detect the expression of proteins related to the PI3K/Akt/mTOR pathway. RESULTS AND CONCLUSION:The DR imaging results revealed that the osteoarthritis group exhibited narrowed knee joint spaces and the formation of periarticular osteophytes,while the hyaluronic acid group and acupotomy group showed widened knee joint spaces with a reduction in periarticular osteophytes.Transmission electron microscopy results demonstrated a decreased number of autophagosomes in chondrocytes in the osteoarthritis group,along with nuclear shrinkage,nuclear membrane rupture,incomplete organelle morphology,and a clear tendency towards cell death.In contrast,both the hyaluronic acid group and acupotomy group exhibited a significant increase in autophagosomes,intact nuclear membranes,and a well-preserved cellular state.Tunel staining results indicated a considerable decrease in the number of apoptotic cells in the hyaluronic acid group and acupotomy group compared with the osteoarthritis group.Western blot results revealed that,compared with the control group,the expression levels of Beclin1,Cath D,and LC3II/LC3I were significantly decreased in the osteoarthritis group(P<0.05),while the expression levels of p-Akt/Akt and p-mTOR/mTOR were significantly increased(P<0.05);compared with the osteoarthritis group,the expression levels of Beclin1,Cath D,and LC3II/LC3I were significantly increased in both the hyaluronic acid group and acupotomy group(P<0.05),while the expression levels of p-Akt/Akt and p-mTOR/mTOR were significantly decreased(P<0.05).To conclude,acupotomy intervention can modulate the PI3K/Akt/mTOR signaling pathway to enhance the autophagic level in chondrocytes,thereby maintaining chondrocyte homeostasis.This ultimately leads to a slowdown in cartilage degeneration.
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BACKGROUND:The results of in vivo and in vitro studies showed that catalpol from Rehmannia glutinosa can significantly reduce the level of inflammatory indexes in the synovial tissue of rats with knee osteoarthritis,and meanwhile,it can delay the progression of knee osteoarthritis.But whether catalpol from Rehmannia glutinosa affects chondrocyte senescence and then delay the progression of knee osteoarthritis has not yet been clarified. OBJECTIVE:To investigate investigate whether catalpol from Rehmannia glutinosa could regulate ATDC5 chondrocyte senescence and the possible mechanisms. METHODS:ATDC5 chondrocytes were divided into blank group(0.1%bovine serum albumin),model group(0.1%bovine serum albumin+1 μmol/L adriamycin),low-dose catalpol group(0.1%bovine serum albumin+1 μmol/L adriamycin+20 μmol/L catalpol from Rehmannia glutinosa)and high-dose catalpol group(0.1%bovine serum albumin+1 μmol/L adriamycin+80 μmol/L catalpol from Rehmannia glutinosa).Adriamycin-induced ATDC5 chondrocyte senescence model was constructed,and the corresponding treatments were given according to the above groups.Cell counting kit-8 assay was used to detect the effects of catalpol from Rehmannia glutinosa on ATDC5 chondrocyte viability,and to screen the optimal concentration of catalpol from Rehmannia glutinosa.The senescence of ATDC5 chondrocytes in each group was detected by β-galactosidase staining after the corresponding treatments.Real-time fluorescence quantitative PCR and western blot were used to detect the mRNA and protein expression of P21,P53,type II collagen,matrix metalloproteinase 13,and interleukin-6.Immunofluorescence method was used to detect the expression of P21,P53 and type II collagen.Flow cytometry was used to detect apoptosis in each group. RESULTS AND CONCLUSION:ATDC5 chondrocytes were identified to be successfully induced and senescence model was induced.Catalpol from Rehmannia glutinosa at the concentrations of 0,20,40,and 80 μmol/L showed no significant effects on the cell viability,suggesting that catalpol from Rehmannia glutinosa is non-cytotoxic and can be used safely(P>0.05);when the concentration was≥100 μmol/L,the cell viability was reduced,suggesting that there may be cytotoxic.Therefore,80 μmol/L was chosen as the high dose for subsequent experiments in this study.The percentage of positive cells in the model group was(86.93±2.18)%,which was significantly higher than that in the blank group[(17.32±0.72)%;P<0.05].Compared with the model group,the percentage of positive cells was significantly lower in the low-and high-dose catalpol groups[(57.28±1.73)%and(27.18±0.97)%,respectively;both P<0.05].Compared with the model group,the relative expression of P21,P53,matrix metalloproteinase 13,and interleukin-6 at mRNA and protein levels was significantly downregulated in the low-and high-dose catalpol groups,while the relative expression of type II collagen at mRNA and protein levels was significantly upregulated in both groups(P<0.05),especially in the high-dose catalpol group(P<0.05).Compared with the model group,the fluorescence intensities of P21 and P53 were significantly weakened in the low-and high-dose catalpol groups,while the fluorescence intensity of type II collagen was significantly enhanced in the low-and high-dose catalpol groups(P<0.05),especially in the high-dose catalpol group(P<0.05).The cell apoptosis detected by Annexin V/PI method showed that there was no significant difference between the model group and the blank group(P>0.05);compared with the model group,the apoptotic index was significantly elevated in the low-and high-dose catalpol groups,especially in the high-dose catalpol group(P<0.05).To conclude,catalpol from Rehmannia glutinosa can slow the progression of osteoarthritis by promoting apoptosis of senescent ATDC5 chondrocytes,further removing senescent ATDC5 chondrocytes,and decreasing the senescence-associated phenotypes.