Exploring the mechanism of warm acupuncture intervention on cartilage degeneration in rabbit knee osteoarthritis based on TLRs/MyD88 signaling pathway
Objective To investigate the mechanism of warm acupuncture intervention on cartilage degenera-tion of rabbit knee osteoarthritis(KOA)based on toll-like receptors(TLRs)/myeloid differentiation factor 88(MyD88)signaling pathway.Methods 30 clean New Zealand male rabbits of six months old were divided into blank control group,model group,and warm acupuncture group by random number table method,with 10 rabbits in each group.Except for blank control group,the KOA model was established by intraarticular injection of papain in the other two groups.After experimental intervention,the rabbits in each group were sacrificed and knee synovial fluid and articular cartilage tissue were collected.The contents of tumor necrosis factor-α(TNF-α)and interleukin-1β(IL-1β)in synovial fluid of each group were detected by enzyme-linked immunosorbent assay(ELISA).The pathological changes of articular cartilage of each group were observed under microscope by HE staining,and the Mankin's score of articular cartilage tissue was compared between the groups.The apoptosis of articular cartilage cells was detected by TUNEL method,and the apoptosis rate of articular cartilage cells was compared between the groups.The expression level of type Ⅱ collagen in articular cartilage of each group was detected by immunohisto-chemistry,and the mRNA expression levels of TLR2,TLR4,MyD88,matrix metalloproteinase(MMP)-1 and MMP-13 mRNA in articular cartilage cells of each group were detected by real-time fluorescent quantitative polymerase chain reaction(qPCR).Results The results of HE staining showed that the structure of cartilage layer in the blank control group was normal,and the tidemark was clear and complete;the cartilage surface in the model group was not smooth,with fibrous tissue formation,cell disordered arrangement,hierarchical disorder,and blurred tidemark;the surface of cartilage in the warm acupuncture group was not smooth,part of the tidemark was blurred,and the surface chondrocytes were increased compared with the model group.Compared with the blank control group,the Mankin's score of articular cartilage tissue,the apoptosis rate of chondrocytes,the contents of TNF-α and IL-1β in synovial fluid,and the relative expression levels of TLR2,TLR4,MyD88,MMP-1 and MMP-13 mRNA in chondrocytes in the model group were significantly increased(P＜0.05);compared with the model group,the above indexes in the warm acupuncture group were significantly decreased(P＜0.05).Compared with the blank control group,the relative expression level of type Ⅱ collagen of articular cartilage in the model group was significantly decreased(P＜0.05);compared with the model group,the relative expression level of type Ⅱ collagen of articular cartilage in the warm acupuncture group was significantly increased(P＜0.05).Conclusion Warm acupuncture may inhibit the activation of TLRs/MyD88 signaling pathway,down-regulate the expression levels of inflammatory factors TNF-α,IL-1β,MMP-1,and MMP-13,and promote the synthesis of type Ⅱ collagen in chondrocytes,thereby inhibiting chondrocyte apoptosis and delaying cartilage degeneration,and achieving the therapeutic effect on KOA.
knee osteoarthritiswarming acupuncturetoll-like receptor/myeloid differentiation factor 88 signa-ling pathwayinflammatory factorstype Ⅱ collagenapoptosis rate of chondrocytesrabbitsexperimental study
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