Resveratrol Reduces Cartilage Matrix Degradation and Affects Chondrocyte Apoptosis in Rats with Traumatic Arthritis

2020 ◽  
Vol 10 (2) ◽  
pp. 239-245
Author(s):  
Zhendong Liu ◽  
Kongbin Zhang ◽  
Yuesong Weng ◽  
Jianqiang Huang ◽  
Lu You
Keyword(s):  
Protein Expression ◽  
Protein Level ◽  
Cell Apoptosis ◽  
Cartilage Tissue ◽  
Chondrocyte Apoptosis ◽  
Therapeutic Effects ◽  
Matrix Degradation ◽  
Mankin Score ◽  
Joint Cavity ◽  
Traumatic Arthritis

Objective: Resveratrol (Resv) is a polyphenolic compound with anti-inflammatory, anti-oxidant, and other pharmacological effects in rheumatoid arthritis (RA). However, whether Resv has protective and therapeutic effects in post-traumatic arthritis (PTA) remains poorly understood. We explored the function of Resv in the treatment of PTA and reducing chondrocyte matrix degradation and chondrocyte apoptosis in PTA rats. Methods: The PTA rat model was established and divided into sham group and Resv gavage group. MMP-13 and Hyp contents in the joint cavity fluid were tested by ELISA. MMP-13 and COL2A1 protein expressions in the articular cartilage tissue were detected by Western blot. Mankin score was measured. The chondrocytes cultured in vitro and divided into control group, IL-1β group, and IL-1β + Resv group. Flow cytometry was adopted to detect cell apoptosis. Results: MMP-13 and Hyp contents were significantly increased, MMP-13 protein expression was significantly upregulated, COL2A1 protein expression was significantly reduced, while Mankin score was increased in PTA group in comparison to those in normal rats. Resv treatment significantly reduced MMP-13 protein expression and elevated COL2A1 protein level in cartilage tissue, decreased MMP-13 and Hyp contents in joint cavity fluid, and reduced Mankin score. After the treatment of IL-1β, the level of MMP-13 protein was significantly elevated, with decreased COL2A1 protein level in chondrocytes, and enhanced chondrocytes apoptosis. Resv intervention significantly inhibited MMP-13 protein and increased COL2A1 level in chondrocytes, and attenuated cell apoptosis. Conclusion: Resv inhibits MMP-13 expression, attenuates chondrocyte matrix degradation and apoptosis, indicating it plays a therapeutic value in treating PTA.

miR-211 Reduces the Degradation of Articular Cartilage Matrix by Targeting Matrix Metalloproteninase 9

2019 ◽  
Vol 9 (9) ◽  
pp. 1292-1297
Author(s):  
Yumei Tian ◽  
Jian Wang
Keyword(s):  
Cartilage Damage ◽  
Cartilage Matrix ◽  
Cartilage Tissue ◽  
Control Group ◽  
Matrix Degradation ◽  
Mankin Score ◽  
Joint Cavity ◽  
Mmp9 Expression ◽  
Col2a1 Expression ◽  
And Cartilage

Matrix metalloproteninase 9 (MMP9) promotes osteoarthritis (OA) cartilage matrix degradation. Abnormal miR-211 expression is associated with OA. Bioinformatics analysis showed a targeted relationship between miR-211 and MMP9 mRNA 3′-UTR. Our study intends to evaluate miR-211’s role in the destruction of chondrocyte matrix in OA model rats. The OA model rats were divided into OA group, OA group+agomir-NC group, OA group+agomir-211 group, followed by analysis of the arthritis Mankin score, Hyp and IL-1β content by ELISA, MMP-9 and COL2A1 expression by western blot and miR-211 level by qRT-PCR. The cartilage tissues were divided into control group, IL-1β+ agomir-NC group, IL-1β+ agomir-211 group, and the expression of MMP-9 and COL2A1 in chondrocytes were detected. Compared with Sham group, IL-1β and Hyp levels in the joint cavity fluid of the OA group were significantly increased and miR-211 expression was significantly decreased with increased MMP9 expression and decreased COL2A1 expression. Injection of agomir-211 into the joint cavity of OA rats significantly reduced MMP9 expression in cartilage tissue, decreased Hyp content in the joint cavity fluid, increased COL2A1 expression, and decreased Mankin score and cartilage damage. IL-1β treatment significantly up-regulated MMP9 expression and decreased COL2A1 expression; miR-211 overexpression attenuated IL-1β-induced cartilage matrix degradation and cartilage destruction. miR-211 plays a role in regulating MMP9 expression and promoting OA. miR-211 overexpression inhibits MMP9 expression, reduces the degradation of cartilage matrix and increases collagen synthesis, thus ameliorating OA development.

Celecoxib Attenuates Cartilage Matrix Damage in Arthritis Rats by Inhibiting NF-κ B

2020 ◽  
Vol 10 (4) ◽  
pp. 531-537
Author(s):  
Lukuan Du ◽  
Zhenghui Jiang ◽  
Zhaohui Wang ◽  
Liming Wang
Keyword(s):  
Caspase 3 ◽  
Sham Group ◽  
Culture Supernatant ◽  
Cartilage Tissue ◽  
Chondrocyte Apoptosis ◽  
Control Group ◽  
Therapeutic Effects ◽  
Protein Expressions ◽  
Col2a1 Expression ◽  
Matrix Damage

Objective: Celecoxib selectively inhibits the activity of COX-2 and the production of prostaglandin (PG), and plays a therapeutic role in treating osteoarthritis (OA). NF-κB signaling and IL-1α and TNFα are involved in OA pathogenesis. This study explored whether Celecoxib might exert therapeutic effects on OA through regulating NF-κB signaling and IL-1β and TNF release in OA rat model. Method : The contents of MMP-13, Hyp, IL-1β and TNFα in synovial fluid were detected by ELISA. The protein expressions of NF-κ B p-p65, COL2A1 and the activity of caspase-3 were detected. OA model rats were separated into OA group and OA+ Celecoxib group followed by analysis of MMP-13, Hyp, IL-1β and TNF level in articular fluid by ELISA and p-p65 and COL2A1 level and caspase-3 activity by western blot. Rat cartilage tissue was cultured and divided into control group, LPS group and LPS+ Celecoxib group followed by analysis of expressions of p-p65 and COL2A1 in cartilage tissue, IL-1 and TNF content in culture supernatant, and chondrocyte apoptosis. Results: Compared with Sham group, p-p65 expression and caspase-3 activity in cartilage tissue of OA rats was increased and COL2A1 level was reduced. Meanwhile the expression of MMP-13, Hyp, IL-1β and TNF in articular fluid of OA rats was increased. Compared to OA group, p-p65 expression and caspase-3 activity was decreased and COL2A1 expression was increased in OA+ Celecoxib treatment group along with decreased MMP-13, Hyp, IL-1β and TNF level in articular fluid. p-p65 expression and caspase-3 activity in LPS group was increased and COL2A1 expression was decreased with increased IL-beta; and TNF content. Compared to LPS group, p-p65 expression and caspase-3 activity was decreased and COL2A1 expression was increased in LPS+ Celecoxib group with decreased content of IL-1β and TNFα. Conclusion: Celecoxib can protect cartilage in OA by inhibiting NF-κB activation and IL-1β and TNF release, and decreasing cell apoptosis in inflammatory environment.

scholarly journals The Possible Mechanisms of HSV-TK/Hyperthermia Combined with 131I-antiAFPMcAb-GCV Nanospheres to Treat Hepatoma

2018 ◽  
Vol 2018 ◽  
pp. 1-15
Author(s):  
Mei Lin ◽  
Chenglin Zhou ◽  
Junxing Huang ◽  
Weizhong Tian ◽  
Hong Yu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Combination Therapy ◽  
Protein Expression ◽  
Tumor Cell ◽  
Clinical Application ◽  
Cell Apoptosis ◽  
Hepatoma Cell ◽  
Microvascular Density ◽  
Therapeutic Effects ◽  
Combination Regimen

Our previous findings showed a good therapeutic effect of the combination of suicide gene HSV-TK, nuclide 131I, and magnetic fluid hyperthermia (MFH) on hepatoma by using magnetic nanoparticles as linkers, far better than any monotherapy involved, with no adverse effects. This combination therapy might be an eligible strategy to treat hepatic cancer. However, it is not clear how the combination regimen took the therapeutic effects. In the current study, to explore the possible mechanisms of radionuclide-gene therapy combined with MFH to treat hepatoma at tissue, cellular, and molecular levels and to provide theoretical and experimental data for its clinical application, we examined the apoptosis induction of the combination therapy and investigated the expression of the proteins related to apoptosis such as survivin, livin, bcl-2, p53, and nucleus protein Ki67 involved in cell proliferation, detected VEGF, and MVD involved in angiogenesis of tumor tissues and analyzed the pathologic changes after treatment. The results showed that the combination therapy significantly induced the hepatoma cell apoptosis. The expression of survivin, VEGF, bcl-2, p53, livin, Ki67, and VEGF proteins and microvascular density (MVD) were all decreased after treatment. The therapeutic mechanisms may be involved in the downregulation of Ki67 expression leading to tumor cell proliferation repression and inhibition of survivin, bcl-2, p53, and livin protein expression inducing tumor cell apoptosis, negatively regulating VEGF protein expression, and reducing vascular endothelial cells, which results in tumor angiogenesis inhibition and microvascular density decrease and tumor cell necrosis. These findings offer another basic data support and theoretical foundation for the clinical application of the combination therapy.

scholarly journals Mesenchymal Stem Cell-Derived Exosomes Modulate Chondrocyte Glutamine Metabolism to Alleviate Osteoarthritis Progression

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Kai Jiang ◽  
Ting Jiang ◽  
Yang Chen ◽  
Xinzhan Mao
Keyword(s):  
Cell Proliferation ◽  
Therapeutic Effect ◽  
Cell Apoptosis ◽  
Glutamine Metabolism ◽  
Cartilage Tissue ◽  
Inflammatory Factors ◽  
Chondrocyte Apoptosis ◽  
Control Group ◽  
Collagen Ii

Osteoarthritis (OA) had a high incidence in people over 65 years old, and there is currently no drug that could completely cure it. This study is aimed at studying the role of exosomes in regulating glutamine metabolism in the treatment of OA. First, we identified the exosomes extracted from the mouse OA model’s bone marrow mesenchymal stem cells (MSC). In vitro, compared with the control group, the cell apoptosis in the OA group increased, while the cell proliferation of the OA group was suppressed. After exosomal treatment, cell apoptosis and cell proliferation were reversed. Inflammatory factors (TNFα, IL-6), glutamine metabolic activity-related proteins (c-MYC, GLS1), glutamine, and GSH/GSSG were increased in the OA group. The overexpression of c-MYC reduced the therapeutic effect of exosomes. At the same time, we found that chondrocyte functional factors (collagen II, Aggrecan) were improved under the treatment of exosomes. However, oe-c-MYC reversed the therapeutic effect of exosomes. In vivo, we found that the running capacity of the mice in the OA group was reduced, and the cartilage tissue was severely damaged. In addition, TNFα, IL-6, and chondrocyte apoptosis increased, while the metabolism of collagen II, Aggrecan, and glutamate decreased in the OA group. After exosomal treatment, the mice’s exercise capacity, tissue damage, inflammation, and chondrocyte function were improved, and glutamate metabolism was increased. This study showed that exosomes regulated the level of chondrocyte glutamine metabolism by regulating c-MYC, thereby alleviating OA.

Effect of miR-9 on Chondrocyte Apoptosis in Rats with Osteoarthritis by Regulating Notch1

2020 ◽  
Vol 10 (3) ◽  
pp. 371-378
Author(s):  
Xiao Zhong ◽  
Xiaodong Deng ◽  
Jian Luo ◽  
Ming Xiong ◽  
Wen Li ◽  
...  
Keyword(s):  
Western Blot ◽  
Caspase 3 ◽  
Notch Signaling Pathway ◽  
Cartilage Matrix ◽  
Cartilage Tissue ◽  
Chondrocyte Apoptosis ◽  
Control Group ◽  
Matrix Degradation ◽  
Qrt Pcr ◽  
Protein Expressions

Objective: Notch1 is an important receptor in Notch signaling pathway. Abnormal Notch1 expression or function is associated with the pathogenesis of OA. There is evidence that the abnormal expression of miR-9 is related to the pathogenesis of OA. Bioinformatics analysis showed that there was a targeting relationship between miR-9 and Notch1’s 3′-UTR, suggesting that there might be a mutual regulation between them. In this study, we established an OA rat model to investigate whether miR-9 plays a role in regulating Notch1 expression, affecting cartilage matrix degradation and chondrocyte apoptosis in OA. Methods: OA model rats were divided into three groups: OA group, OA + agomir group, OA + miR-9 agomir group. The content of Hyp in articular fluid was measured by ELISA, the activity of caspase-3 was detected by kit, the mRNA expressions of miR-9, COL2A1, Notch1 and Hes5 was detected by qRT-PCR, and the protein expressions of Notch1 and Hes5 in articular cartilage was detected by Western blot. Chondrocytes were separated into control group, IL-1β +miR-NC group, IL-1β +miR-9 mimic group followed by analysis of mRNA expressions of miR-9, COL2A1, Notch1 and Hes5 were detected by qRT-PCR, protein expressions of Notch1 and Hes5 by Western blot, and cell apoptosis by flow cytometry. Results: Compared with Sham group, the levels of IL-1β , Hyp, Notch1, Hes5 and Caspase-3 in the synovial fluid of rats in OA group were increased significantly, while the mRNA expressions of miR-9, COL2A1 and Notch1 and Hes5 level in cartilage tissue were decreased significantly. Intra-articular injection of miR-9 agomir could significantly reduce the content of Hyp, the mRNA expressions of Notch1 and Hes5 and the activity of caspase-3 in cartilage tissue of OA rats, increase the mRNA expressions of miR-9 and COL2A1, and decrease the protein expressions of Notch1 and Hes5. After treated with IL-1β , the expressions of Notch1 and Hes5 were increased, the mRNA expressions of miR-9 and COL2A1 were decreased, and apoptosis of chondrocyte was increased in chondrocyte. After miR-9 mimic transfection, miR-9 and COL2A1 mRNA expressions were increased, Notch1 and Hes5 expressions were decreased, and apoptosis of chondrocyte was decreased under IL-1β treatment. Conclusion: Reduced miR-9 expression upregulates Notch1 expression and promotes the pathogenesis of OA. Increased miR-9 expression can inhibit Notch1 expression, reduce cartilage matrix degradation and inhibit chondrocyte apoptosis.

scholarly journals miR-146a-5p Promotes Chondrocyte Apoptosis and Inhibits Autophagy of Osteoarthritis by Targeting NUMB

Cartilage ◽  
2021 ◽  
pp. 194760352110235
Author(s):  
Hongjun Zhang ◽  
Wendi Zheng ◽  
Du Li ◽  
Jia Zheng
Keyword(s):  
Caspase 3 ◽  
Cartilage Tissue ◽  
Luciferase Reporter ◽  
Chondrocyte Apoptosis ◽  
Knee Cartilage ◽  
Before And After ◽  
Related Proteins ◽  
Human And Mouse

Objective miR-146a-5p was found to be significantly upregulated in cartilage tissue of patients with osteoarthritis (OA). NUMB was shown to be involved in the autophagy regulation process of cells. We aimed to learn whether NUMB was involved in the apoptosis or autophagy process of chondrocytes in OA and related with miR-146a-5p. Methods QRT-PCR was used to detect miR-146a-5p level in 22 OA cartilage tissues and 22 controls. The targets of miR-146a-5p were analyzed using software and the luciferase reporter experiment. The apoptosis and autophagy, and related proteins were detected in chondrocytes treated with miR-146a-5p mimic/inhibitor or pcDNA3.1-NUMB/si-NUMB and IL-1β, respectively. In vivo experiment, intra-articular injection of miR-146a-5p antagomir/NC was administered at the knee of OA male mice before and after model construction. Chondrocyte apoptosis and the expression of apoptosis and autophagy-related proteins were also detected. Results miR-146a-5p was highly expressed in knee cartilage tissue of patients with OA, while NUMB was lowly expressed and negatively regulated by miR-146a-5p. Upregulation of miR-146a-5p can promote cell apoptosis and reduce autophagy of human and mouse chondrocytes by modulating the levels of cleaved caspase-3, cleaved PARP, Bax, Beclin 1, ATG5, p62, LC3-I, and LC3-II. Increasing the low level of NUMB reversed the effects of miR-146a-5p on chondrocyte apoptosis and autophagy. Intra-articular injection of miR-146a-5p antagomir can also reverse the effects of miR-146a-5p on the apoptosis and autophagy of knee joint chondrocytes in OA mice. Conclusion Downregulation of miR-146a-5p suppresses the apoptosis and promotes autophagy of chondrocytes by targeting NUMB in vivo and in vitro.

scholarly journals Cannabidiol Induces Cell Cycle Arrest and Cell Apoptosis in Human Gastric Cancer SGC-7901 Cells

Biomolecules ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 302 ◽  
Author(s):  
Xin Zhang ◽  
Yao Qin ◽  
Zhaohai Pan ◽  
Minjing Li ◽  
Xiaona Liu ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Cell Cycle ◽  
Protein Expression ◽  
Cell Cycle Arrest ◽  
Phase Cell ◽  
G1 Phase ◽  
Therapeutic Effects ◽  
Human Gastric Cancer ◽  
Expression Levels ◽  
Cycle Arrest

The main chemical component of cannabis, cannabidiol (CBD), has been shown to have antitumor properties. The present study examined the in vitro effects of CBD on human gastric cancer SGC-7901 cells. We found that CBD significantly inhibited the proliferation and colony formation of SGC-7901 cells. Further investigation showed that CBD significantly upregulated ataxia telangiectasia-mutated gene (ATM) and p53 protein expression and downregulated p21 protein expression in SGC-7901 cells, which subsequently inhibited the levels of CDK2 and cyclin E, thereby resulting in cell cycle arrest at the G0–G1 phase. In addition, CBD significantly increased Bax expression levels, decreased Bcl-2 expression levels and mitochondrial membrane potential, and then upregulated the levels of cleaved caspase-3 and cleaved caspase-9, thereby inducing apoptosis in SGC-7901 cells. Finally, we found that intracellular reactive oxygen species (ROS) increased after CBD treatment. These results indicated that CBD could induce G0–G1 phase cell cycle arrest and apoptosis by increasing ROS production, leading to the inhibition of SGC-7901 cell proliferation, thereby suggesting that CBD may have therapeutic effects on gastric cancer.

scholarly journals Propofol attenuates lung ischemia/reperfusion injury though the involvement of the MALAT1/microRNA-144/GSK3β axis

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Jian-Ping Zhang ◽  
Wei-Jing Zhang ◽  
Miao Yang ◽  
Hua Fang
Keyword(s):  
Cell Apoptosis ◽  
Ischemia Reperfusion Injury ◽  
Glycogen Synthase ◽  
Ischemia Reperfusion ◽  
Inflammatory Factors ◽  
Therapeutic Effects ◽  
Protective Effects ◽  
Loss Of Function

Abstract Background Propofol, an intravenous anesthetic, was proven to protect against lung ischemia/reperfusion (I/R) injury. However, the detailed mechanism of Propofol in lung I/R injury is still elusive. This study was designed to explore the therapeutic effects of Propofol, both in vivo and in vitro, on lung I/R injury and the underlying mechanisms related to metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/microRNA-144 (miR-144)/glycogen synthase kinase-3β (GSK3β). Methods C57BL/6 mice were used to establish a lung I/R injury model while pulmonary microvascular endothelial cells (PMVECs) were constructed as hypoxia/reperfusion (H/R) cellular model, both of which were performed with Propofol treatment. Gain- or loss-of-function approaches were subsequently employed, followed by observation of cell apoptosis in lung tissues and evaluation of proliferative and apoptotic capabilities in H/R cells. Meanwhile, the inflammatory factors, autophagosomes, and autophagy-related proteins were measured. Results Our experimental data revealed that Propofol treatment could decrease the elevated expression of MALAT1 following I/R injury or H/R induction, indicating its protection against lung I/R injury. Additionally, overexpressing MALAT1 or GSK3β promoted the activation of autophagosomes, proinflammatory factor release, and cell apoptosis, suggesting that overexpressing MALAT1 or GSK3β may reverse the protective effects of Propofol against lung I/R injury. MALAT1 was identified to negatively regulate miR-144 to upregulate the GSK3β expression. Conclusion Overall, our study demonstrated that Propofol played a protective role in lung I/R injury by suppressing autophagy and decreasing release of inflammatory factors, with the possible involvement of the MALAT1/miR-144/GSK3β axis.

scholarly journals Artemisinin attenuated oxidative stress and apoptosis by inhibiting autophagy in MPP+-treated SH-SY5Y cells

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Junqiang Yan ◽  
Hongxia Ma ◽  
Xiaoyi Lai ◽  
Jiannan Wu ◽  
Anran Liu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Membrane Potential ◽  
Protein Expression ◽  
Mitochondrial Membrane Potential ◽  
Western Blotting ◽  
Cell Apoptosis ◽  
Mitochondrial Membrane ◽  
Caspase 3 ◽  
Neuroprotective Effect ◽  
Neuroprotective Effects

Abstract Background Parkinson’s disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease. The oxidative stress is an important component of the pathogenesis of PD. Artemisinin (ART) has antioxidant and neuroprotective effects. The purpose of this study is to explore the neuroprotective effect of ART on 1-methyl-4-phenyliodine iodide (MPP +)-treated SH-SY5Y cells and underlying mechanism. Methods We used MPP+-treated SH-SY5Y cells to study the neuroprotective effect of ART. Cell viability was measured by MTT assay after incubating the cells with MPP+ and/or ART for 24 h. DCFH-DA was used to detect the level of intracellular reactive oxygen species (ROS), and WST-8 was used to detect the level of superoxide dismutase (SOD). The level of intracellular reduced glutathione (GSH) was detected with 5,5΄-dithiobis-(2-nitrobenzoic acid), and the level of malondialdehyde (MDA) was assessed based on the reaction of MDA and thiobarbituric acid. A mitochondrial membrane potential detection kit (JC-1) was used to detect changes in the mitochondrial membrane potential (MMP), and an Annexin V-FITC cell apoptosis kit was used to detect cell apoptosis. The expression levels of caspase-3, cleaved caspase-3 and the autophagy-related proteins LC3, beclin-1, and p62 were detected by Western blotting. In addition, to verify the change in autophagy, we used immunofluorescence to detect the expression of LC3 and p62. Results No significant cytotoxicity was observed at ART concentrations up to 40 μM. ART could significantly increase the viability of SH-SY5Y cells treated with MPP+ and reduce oxidative stress damage and apoptosis. In addition, the Western blotting and immunofluorescence results showed that MPP+ treatment could increase the protein expression of beclin1 and LC3II/LC3I and decrease the protein expression of p62, indicating that MPP+ treatment could induce autophagy. Simultaneous treatment with ART and MPP+ could decrease the protein expression of beclin1 and LC3II/LC3I and increase the protein expression of p62, indicating that ART could decrease the level of autophagy induced by MPP+. Conclusion Our results indicate that ART has a protective effect on MPP+-treated SH-SY5Y cells by the antioxidant, antiapoptotic activities and inhibition of autophagy. Our findings may provide new hope for the prevention and treatment of PD.

An Insight into the Role of Apoptosis and Autophagy in Nitric Oxide–Induced Articular Chondrocyte Cell Death

Cartilage ◽  
2020 ◽  
pp. 194760352097676
Author(s):  
Ekkapol Akaraphutiporn ◽  
Takafumi Sunaga ◽  
Eugene C. Bwalya ◽  
Wang Yanlin ◽  
Mwale Carol ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cell Death ◽  
Western Blot ◽  
Cell Apoptosis ◽  
Molecular Mechanisms ◽  
Interleukin 1 ◽  
Chondrocyte Apoptosis ◽  
Protective Mechanism ◽  
Autophagic Flux ◽  
Qpcr Analysis

Objective To investigate the role and characterize the molecular mechanisms regulating apoptosis and autophagy in nitric oxide (NO)–induced chondrocyte cell death. Design Cell apoptosis and autophagy were evaluated in chondrocytes treated with sodium nitroprusside (SNP) combined with the presence or absence of interleukin-1 beta (IL-1β) and nutrient-deprived conditions. The concentration of nitrite was determined by Griess reaction. Activation of apoptosis and autophagy were determined by immunocytochemistry, Western blot, and quantitative real-time polymerase chain reaction (qPCR) analysis. Flow cytometry and MTT assay were used to assess cell viability. Results Cotreatment of chondrocytes with SNP and IL-1β under nutrient-deprived condition potentially enhanced the effect of NO-induced cell death. Immunocytochemistry, Western blot, and qPCR analysis indicated that treatment of chondrocytes with SNP significantly reduced autophagic activity, autophagic flux, and multiple autophagy-related (Atg) genes expression. These findings were associated with an increase in ERK, Akt, and mTOR phosphorylation, whereas autophagy induction through mTOR/p70S6K inhibition by rapamycin significantly suppressed NO-induced cell apoptosis. Furthermore, the cleavage of poly(ADP-ribose) polymerase (PARP) and caspase-3 activation in response to apoptosis was weakly detected. These results corresponded with a significant increase in apoptosis-inducing factor (AIF) expression, suggesting the involvement of the caspase-independent pathway. Conclusions These results demonstrate that in chondrocyte cultures with cells induced into an osteoarthritis state, NO inhibits autophagy and induces chondrocyte apoptosis mainly, but not completely through the caspase-independent pathway. Our data suggest that autophagy is a protective mechanism in the pathogenesis of osteoarthritis and could be proposed as a therapeutic target for degenerative joint diseases.

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