BACKGROUND:Defective outgrowth of chondrocyte mitophagy causes degenerative chondrocyte pathological changes such as apoptosis and matrix loss.OBJECTIVE:To investigate the effects and possible mechanism of Juanbi Decoction-containing serum on interleukin-1β-induced inflammatory response and apoptosis of rat knee joint chondrocytes.METHODS:Fifty male Sprague-Dawley rats were randomly given saline,Juanbi Decoction in low,medium and high doses(1.24,2.48 and 4.96 g/kg),and celecoxib(positive drug)group.Drug-containing serum was obtained by continuous gavage for 2 weeks.(1)Chondrocytes were isolated and randomly divided into control group,interleukin-1β group,Juanbi Decoction low,medium and high dose containing serum groups and positive drug serum group.Cell counting kit-8 assay was used to detect cell viability;immunofluorescence double staining was used to detect mitophagy level;immunofluorescence was used to detect the phosphorylated AMP-activated protein kinase level;western blot was used to detect the expression of PTEN induced putative kinase 1/Parkin pathway-related protein and cleaved caspase-3;and ELISA was used to detect inflammatory factor level.(2)PTEN induced putative kinase 1 siRNA and Compound C were used for intervention to explore the role of AMP-activated protein kinase/PTEN induced putative kinase 1/Parkin pathway in the regulation of mitophagy by Juanbi Decoction-containing serum.RESULTS AND CONCLUSION:(1)Compared with the control group,chondrocyte survival,type II collagen,phosphorylated AMP-activated protein kinase,PTEN induced putative kinase 1,Parkin,and microtubule-associated proteins 1 light chain 3 protein levels,and mitophagy levels were significantly lower in the interleukin-1β group(P<0.05),while cleaved caspase-3 protein levels,interleukin-6,interleukin-8 and tumor necrosis factor-α levels were significantly higher(P<0.05).Compared with the interleukin-1β group,opposite changes in all the above indexes were observed in Juanbi Decoction low,medium and high dose containing serum groups and positive drug serum group(P<0.05).(2)PTEN induced putative kinase 1 siRNA significantly inhibited the effect of Juanbi Decoction-containing serum on mitophagy in interleukin-1β-treated chondrocytes and reduced the protective effect of Juanbi Decoction-containing serum on interleukin-1β-induced inflammation and apoptosis in chondrocytes;Compound C reversed the effect of Juanbi Decoction-containing serum on the PTEN induced putative kinase 1/Parkin signaling pathway in interleukin-1β-treated chondrocytes.To conclude,Juanbi Decoction-containing serum inhibits chondrocyte inflammation and apoptosis by affecting the level of mitochondrial autophagy,thereby attenuating interleukin-1β-induced chondrocyte degradation by a mechanism that may be related to the regulation of the AMP-activated protein kinase/PTEN induced putative kinase 1/Parkin pathway.
Juanbi Decoctionchondrocytemitophagyadenylate-activated protein kinaseAMPKPTEN induced putative kinase 1/Parkin