Intraarticular Injection Of Rapamycin Inhibits The Activity Of NLRP3 In Articular Cartilage Study On The Mechanism Of Delaying Osteoarthritis

Objective To investigate the effect of autophagy on the expression of type II collagen,light chain 3(LC-3)and NLRP3 in articular cartilage of osteoarthritis(OA).Methods Sixty C57 BL / 6 mice were used to study the osteoarthritis model of anterior medial meniscus(destabilising the medial meniscus operation,DMM).According to the time of rapamycin injection into the articular cavity,the model was divided into:(1)control group;(2)DMM2W group;(3)DMM8W group;(4)RAPA2W group;(5)RAPA8W group.The injury degree of articular cartilage was evaluated by Safranine O-fast green staining,hematoxylin red staining and Osteoarthritis Research Society Inretnatial(OARSI)score.The changes of organelle structure of articular cartilage were observed by transmission electron microscopy.The expression of Matrix metalloproteinase(MMP-13),type II collagen,LC-3and NLRP3 in chondrocytes was detected by immunohistochemistry and immunofluorescence.The expression of NLRP3,Caspase-1 and Interleukin-1?(IL-1 ?)mRNA in chondrocytes was detected by(Quantitative-Polymerase Chain Reaction)Q-PCR.Results Compared with the control group,the damage of articular cartilage in DMM2 W group and DMM8 W group was more serious,and the damage in RAPA2 W group and RAPA8 W group was less than that in DMM2 W and DMM8 W group(P < 0.05).Under the transmission electron microscope,the structure of chondrocytes in the control group was normal,the organelle of DMM2 W group was damaged seriously,the structure of mitochondria,endoplasmic reticulum and lysosome was damaged seriously,the structure of mitochondria,endoplasmic reticulum and lysosome was deformed,the nucleus was pyknosis,the damage of chondrocytes in RAPA2 W group and RAPA8 W group was less than that in DMM2 W and DMM8 W group.Immunohistochemistry and immunofluorescence showed that the expression of MMP-13 and NLRP3 was the lowest in the control group,increased in DMM2 W group,and the highest in DMM8 W group,RAPA2 W group and RAPA8 W group Compared with DMM2 W and DMM8 W,the protein expression of MMP-13 and NLRP3 in8 W group was significantly lower(P < 0.05);in the protein expression of type II collagen and LC-3,the expression of control group was the highest,DMM2 W group was lower,DMM8 W group was the lowest,RAPA2 W group and RAPA8 W group were significantly higher than DMM2 W and DMM8 W group(P < 0.05).Q-PCR showed that the expression of NLRP3,caspase-1,IL-1 ? mRNA in the control group was the lowest,the expression of DMM2 W group was increased,the expression of DMM8 W group was the highest,the expression of RAPA2 W group and RAPA8 W was significantly lower than that of DMM2 W and DMM8W(P < 0.05)Conclusion NLRP3 is closely related to osteoarthritis,and the protein expression level of NLRP3 is positively related to the severity of OA.Rapamycin can activate chondrocyte autophagy,inhibit the activity of NLRP3,and reduce the expression of NLRP3 related factors,so as to delay the progress of osteoarthritis.