Objective: Corticosteroids can destroy the cartilage. To investigate the effect of dexamethasone (Dexa) on the apoptosis and expression of Fas/FasL of human articular chondrocytes (HACs) in vitro so as to explore the mechanism of pro-apoptotic role of Dexa on HACs.
Methods: Following full agreement of patients, the cartilage specimens were collected from the patients with osteoarthritis undergoing knee replacement. The second passage HACs were incubated in cell culture media containing 0.125, 1.25, 12.5, 25, and 50 microg/mL Dexa for 48 hours respectively to determine the optimal concentration of Dexa by MTT. The apoptosis was assessed by TMRE/Hoechst/Annexin V-FITC/7-AAD quadruple staining after culture for 0, 24, and 48 hours. The mRNA expressions of Fas and FasL were determined by real-time quantitative PCR after culture for 48 hours. The protein expressions of Fas and FasL were determined by immunohistochemistry staining analysis after culture for 24 hours and 48 hours.
Results: The cell inhibitory rate of 25 microg/mL Dexa was significantly higher than that of 50 microg/mL Dexa (P < 0.05), and there were significant differences when compared with that at other concentrations of Dexa (P < 0.05), so 25 microg/mL Dexa was appropriately selected as an optimal concentration of Dexa. The apoptotic rates of HACs were 5.8% +/- 0.3%, 27.0% +/- 2.6%, and 36.0% +/- 3.1% at 0, 24, and 48 hours, respectively, in a time dependent manner (P < 0.05). The expressions of Fas mRNA were (8.93 +/- 1.12) x 10(-3) in the experimental group and (3.31 +/- 0.37) x 10(-3) in the control group, showing significant difference (P < 0.05). The expressions of FasL mRNA were (5.92 +/- 0.66) x 10(-3) in the experimental group and (2.31 +/- 0.35) x 10(-3) in the control group, showing significant difference (P < 0.05). The expressions of Fas and FasL proteins showed an increasing tendency with time in the experimental group and the expressions were significantly higher than those in the control group after culture for 24 hours and 48 hours (P < 0.05).
Conclusion: Dexa can induce the apoptosis and significantly upregulate the apoptotic gene expression of Fas/FasL, which can provide the experimental evidence to further investigate the role of Fas/FasL signaling pathway in Dexa-induced HACs apoptosis.