Zekai Mao1, Pengcheng Wang2, Qiyong Pan1, Xiaojian Huang1, Rui Zhang1, Xiaobin Shang3, Xiaohu Ma1, Hongbo You4. 1. Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, China. 2. Department of Emergency, Zhongnan Hospital of Wuhan University, Wuhan 430030, Hubei, China. 3. Department of Orthopedics, Tongren Hospital of Wuhan University (Wuhan Third Hospital), Wuhan 430030, Hubei, China. 4. Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, China. Electronic address: hbyou@aliyun.com.
Abstract
BACKGROUND: Osteoarthritis (OA) is a chronic degenerative joint disease characterized by cartilage degradation driven by proinflammatory cytokines; meanwhile, statins display anti-inflammatory effects. Here we assessed the effects of pravastatin on inflammatory rat chondrocytes and explored the underlying mechanism. METHODS: Rat articular chondrocytes were pretreated with pravastatin and subsequently stimulated with IL-1β. Then, the expression levels of OA- and autophagy-related effectors, at the mRNA and protein levels, were examined by real-time polymerase chain reaction (RT-PCR) and Western blotting, respectively. Autophagic flux in chondrocytes in different treatment groups was monitored via GFP-mRFP-LC3 adenovirus transfection and confocal microscopy. Activation of MAPK, PI3K/Akt, and NF-κB pathways in chondrocytes with or without pravastatin treatment during IL-1β stimulation was examined by Western blotting. RESULTS: Our results showed that pravastatin downregulated the degradation related genes MMP3, MMP13 and ADAMTS5, as well as extracellular matrix degeneration induced by IL-1β. In addition, pravastatin upregulated the autophagy related genes atg7, atg12, Beclin1, and LC3 II in IL-1β stimulated chondrocytes. GFP-mRFP-LC3 adenovirus transfection also indicated that pravastatin restored impaired autophagy in OA chondrocytes. Furthermore, we demonstrated that regulation of the MAPK signaling pathway may be responsible for autophagy regulation in the articular cartilage. CONCLUSIONS: Taken together, these findings suggested that pravastatin restores impaired autophagic flux by inhibiting MAPK activation and protects the cartilage against inflammatory responses, suggesting a potential role for autophagic flux in pravastatin-mediated cartilage protection.
BACKGROUND:Osteoarthritis (OA) is a chronic degenerative joint disease characterized by cartilage degradation driven by proinflammatory cytokines; meanwhile, statins display anti-inflammatory effects. Here we assessed the effects of pravastatin on inflammatory rat chondrocytes and explored the underlying mechanism. METHODS:Rat articular chondrocytes were pretreated with pravastatin and subsequently stimulated with IL-1β. Then, the expression levels of OA- and autophagy-related effectors, at the mRNA and protein levels, were examined by real-time polymerase chain reaction (RT-PCR) and Western blotting, respectively. Autophagic flux in chondrocytes in different treatment groups was monitored via GFP-mRFP-LC3 adenovirus transfection and confocal microscopy. Activation of MAPK, PI3K/Akt, and NF-κB pathways in chondrocytes with or without pravastatin treatment during IL-1β stimulation was examined by Western blotting. RESULTS: Our results showed that pravastatin downregulated the degradation related genes MMP3, MMP13 and ADAMTS5, as well as extracellular matrix degeneration induced by IL-1β. In addition, pravastatin upregulated the autophagy related genes atg7, atg12, Beclin1, and LC3 II in IL-1β stimulated chondrocytes. GFP-mRFP-LC3 adenovirus transfection also indicated that pravastatin restored impaired autophagy in OA chondrocytes. Furthermore, we demonstrated that regulation of the MAPK signaling pathway may be responsible for autophagy regulation in the articular cartilage. CONCLUSIONS: Taken together, these findings suggested that pravastatin restores impaired autophagic flux by inhibiting MAPK activation and protects the cartilage against inflammatory responses, suggesting a potential role for autophagic flux in pravastatin-mediated cartilage protection.