The Effect And Mechanism Of PLC-?1-regulated Autophagy In IL-1?-stimulated Osteoblasts And Experimental KOA Of Rat

Objective:It is well known that subchondral bone(SCB)does not play an innocent role in the development of osteoarthritis(OA).Especially,the increasing bone turnover(remolding)makes contributes to the progression of OA in early stage.The abnormal remolding may partly be attributed to suppressed differentiation and mineralization of OB.To maintain the normal phenotype and mineralization,however,a proper rate of autophagy flux should be sustained by OB.PLC-yl has been reported to be involved in the autophagy induction of cancer cells via blocking autophagy.In this study,it was investigated the role of PLC-?1 in regulating osteoarthritic OB metabolism,in an attempt to confirm whether or how PLC-yl modulte the differentiation and mineralization of osteoarthritic OBMethod:OA model rats were sacrificed at 2,4,10 weeks after ACLT operation,respectively.Morphologic changes were measured by histological staining and CT scanning.The phenotypes,function and autouphagy of OA OB and IL-1?-stimulated OB were detected by Western blot,qPCR,ARS staining,and transmission electron microscopy.OB was then treated with autophagy activators or inhibitors and PLC-yl inhibitor,followed by the detections as mentioned above,in an attempt to identify the relationships among abnormal phenotypes,autophagic level,and PLC-yl expression.Finally,the effect of PLC-yl inhibitor on SCB and articular cartilage was investigated with the injection of PLC-lyl inhibitor using standard bone canal technique in rat OA model with ACLT operation.Result:A significant decrease of bone mass in 2 weeks' OA rats after ACLT operation was observed.Abnormal phenotypes of OA OB were also detected,including higher expression at the protein level of Col-1,lower expression at the mRNA level of ALP and OCN,and the decrease of the mineralization.Meanwhile,the decrease of LC3BII/I protein expression and the increase of p62 protein expression were found in those OBs,as well as the increase of p-PLC-?l and p-mTOR.Furthermore,like autiophagy activators and PLC-?1 inhibitor U73122,had a positive effect on phenotypic changes of the OB through inducing autophagy,in which PLC-yl/mTOR signal axis was involved.The SCB injection of PLC-yl inhibitor U73122,using standard bone canal,attenuated the decrease of bone mass at the early stage of OA in rat OA model,with the alleviation of articular cartilage destruction.Conclusion:Our results demonstrated that autophagic abnormality of osteoarthrntic OB might contribute to the dysfunction of its differentiation and mineralization,resulting in the decrease of bone mass in SCB at the early stage of OA.PLC-yl inhibition promoted the differentiation and mineralization in osteoarthritic OB or IL-1?-stimulated OB through the induction of autophagy.The SCB inj ection of PLC-yl inhibitor could be a potential approach for OA therapy at the early stage of OA.