Résumé
Objective To investigate the protective effects of carboxymethylated chitosan (CMCS) on nitric oxide (NO) induced apoptosis in rat chondrocytes, and the probable roles and mechanisms of PI3K/Akt signaling pathway in these process.Methods Rat knee articular cartilage was used as the source of chondrocytes, the cells were identified by immunohistochemical staining against collagen type Ⅱ, odium nitroprusside (SNP, 3 mmol/L) was used to establish the apoptotic models of chondrocytes.Cells were divided into four groups: the control group, the SNP-induced group, the SNP+CMCS treated group, the SNP+CMCS+PI3K inhibitor Wortmannin treated group.Cell proliferation were assessed by cell proliferation assay kit (CCK-8), the apoptotic rate of chondrocytes was determined by FCM with Annexin V-FITC/PI double staining, the expression levels of MMP-13 and TIMP-1 mRNA were detected by real-time polymerase chain reaction (PCR) analysis, the expression of Akt and p-Akt protein levels was detected by Western blotting analysis.One-way analysis of variance (ANOVA) statistical analysis was used to calculate the data.Results Three mmol/L SNP can inhibit proliferation (0.221±0.023), and the proliferation was reduced by 70％ compared with the control group (0.736±0.032, F=8.203, P=0.021);and the induced apoptosis in cultured chondrocytes could be observed.The apoptotic rate was (68.8±5.2)％.Increased MMP-3 and decreased TIMP-1 mRNA expression were observed in SNP-induced cells.After adding CMCS to SNP-induced chondrocytes, the proliferation was increased while apoptotic rate was decreased, the apoptotic rate decreased to (14.7±2.3)％.CMCS could promote the activation of p-Akt in SNP-induced chondrocytes and restore SNP-induced MMP-13 and TIMP-1 mRNA expression.Conclusion CMCS could protect apoptosis in SNP induced chon-drocvtes via activation of PI3K/Akt pathwav.
Résumé
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.
Résumé
Objective To investigate the effect of intra-articular carboxymethylated ehitosan(CM- CTS)injection on inducible nitric oxide synthase(iNOS)expression in cartilage at the early stage of os- teoarthfitis(OA).Methods Thirty-two white rabbits were underwent unilateral anterior cruciate ligament transection(ACLT)and were randomly divided into 4 groups 5 weeks after transection.Rabbits of group A re- ceived 0.3 ml of 2% high molecular weight CMCTS(H-CMCTS)once every two weeks.Rabbits in group B were treated using 2% low molecular weight(L-CMCTS)CMCTS at:the same intervals.Group C rabbits were injected intra-articularly with 0.3 ml of 1% sodium hyaluronate(Na-HA)once a week.Animals of group D were not injected.At sacrifice,11 weeks following surgery,the expression of iNOS in cartilages was analyzed by immunohistochemistry and reverse transcription-polymerase chain reaction(RT-PCR)methods.Results Both immunohistochemistry and RT-PCR showed that the level of iNOS expression of cartilage in CMCTS in- jection groups was lower than that in Na-HA injection group and the untreated group.There was no significant difference in iNOS expression between the two different molecular weight CMCTS injection groups. No signifi- cant difference of iNOS expression in cartilage was found between Na-HA injection group and the untreated group.Conclusion CMCTS suppresses iNOS expression in cartilage during the early stage of OA.Na-HA treatment has no effect on iNOS expression in cartilage.