The role of p38 MAPK signal pathway in carboxymethylated chitosan protecting NO-induced chondrocytes apoptosis and the mechanisms / 中华风湿病学杂志

ABSTRACT

Objective To study the effects of carboxymethylated chitosan (CMCS) to nitric oxide (NO)-induced apoptosis on rat chondrocytes,and explore p38MAPK signal transduction pathway in the process and its mechanism.Methods The rat articular cartilage cells were cultured in vitro,collagen type-2 (collagen-2) immunohistochemical staining was used to identify the cartilage cells.The model of chondrocyte apoptosis was built by different concentrations of sodium nitroprusside (SNP) induction.The cells were divided into the control group,the SNP treated group SNP+CMCS treated group,and the SNP+p38 MAPK inhibitor SB203580 treated group.The apoptotic rate of chondrocytes was calculated by FCM,apoptotic nuclei was identified by Hoechst33342 stain,the mitochondrial membrane potential changes was detected by Rhodamine123 (Rho123) stain,the expression of p38 and p-p38 were detected by Western blotting analysis.Results 1-3 mmol/L SNP could induce chondrocyte apoptosis,the apoptotic rate was increased with the SNP increasing,the most obvious apoptosis was occurred in 3 mmol/L SNP treated chondrocytes,which was 69.8％ (P＜0.05).SNP could increase the nuclear fragmentation of chondrocytes,the cells with nuclear fragmentation was significantly higher than that in the control group.SNP could reduce mitochondrial membrane potential in chondrocytes,which decreased significantly compared with the control group.SNP could increase the p-p38 expression in chondrocytes,which was 4.3 times compared to the control group.CMCS of different concentrations could reduce the apoptotic rate of SNP-induced chondrocytes,which was 51.0％,29.9％ and 15.2％,which was decreased significantly (P＜0.05) when compared with 3 mmol/L SNP induced group,CMCS decreased the cells number of SNP-induced nuclear fragmentation.CMCS increased the mitochondrial membrane potential in SNP-induced chondrocytes.CMCS reduced the expression levels of p-p38 in SNP-induced chondrocytes.Conclusion CMCS has protective effect on SNP-induced apoptosis of chondrocytes.This process is completed by inhibiting the activity of p38 MAPK signal pathway.