Shikimic Acid Relieves IL-1β-Induced Cartilage Degradation By Enhancing Damaged Autophagy

Objective:To observe interleukin1β-induced MMP3、MMP13 expression and impaired autophagy in SW1353 cells and to inverstigate the role and regulatory mechanisms of Shikimic acid in this progression.Methods:Shikimic acid cytotoxicity was assessed by CCK-8 assay.The SW1353 cells were stimulated with IL-1βfor 24 h after Shikimic acid(0.1m M,1m M or 10 m M)pretreatment.Total protein and RNA was extracted and the MMP3,MMP13,ATG7,Beclin-1,LC3 Ⅰ/Ⅱ expression was examined by western bloting or RT-PCR.RT-PCR or western bloting were performed to investigate the MMPs,ATG7,Beclin-1,LC3 Ⅰ/Ⅱ expression of cells treated with activator or inhibitor of autophagy.Besides,MAPK-related pathway signaling molecules were detected after IL-1β treatment for different time,and the optimal time point was selected for further experiments..And PI3K/AKT signals,NF-κB signals were evaluated by westen bloting after 24 hours of IL-1β stimulation after SA pretreatment.Results:The MMPs expression of SW1353 cells treated with IL-1β were increased and casused damage to autophagy,while shikimic acid could inhibit this effect.CCK8 result shows that different concentration of shikimic acid used in this expression has no inhibitory effect on viability of SW1353 cells.When the cells pretreated with SA were stimulated by IL-1β,the expression levels of MMP3 and MMP13 were decreased,and the phosphorylation levels of ERK,JNK,P38 and P65 were differently reduced.In addition,the phosphorylation of ERK,JNK and P38 can be observed clearly at 30 min after treated by IL-1βwhile the phosphorylation of AKT and P65 increases clearly after treated for 24 h,and shikimic acid can block these effects except AKT.Autophagy inhibitor 3-MA upregulate the MMPs expression in cells,and the activator rapamycin blocks the IL1β-induced MMPs expression.Conclusion:IL-1β upregulate MMPs and cause damage to autophagy,in turn MMPs were secreted to breakdown extracellular matrix by switch the phosphorylation of ERK,JNK,AKT and P65,SA can inhibit Activation of MAPK,but not the PI3K/AKT signaling pathway,promotes autophagy levels in chondrocytes to slow this process.In addition,SA can also inhibit cartilage matrix degradation by inhibiting IL-1β-induced activation of the NF-κB signaling pathway.The results of this study suggested the protective effect of autophagy on osteoarthritis and shikimic acid could be novel therapeutic drug to treat osteoarthritis.