The effect of moxifloxacin on apoptosis of airway smooth muscle cells and mitochondria membrane potential

Abstract

To observe the effects of moxifloxacin at various concentrations on the expression of Caspase-3, the alteration of mitochondria membrane potential (ΔΨm) and the apoptosis of airway smooth muscle cells (ASMCs), and to explore the possible mechanisms. ASMCs were derived from rat airway tissues and cultured in vitro. The cells were randomly divided into 5 groups including a control group and 4 groups to which moxifloxacin was added at different concentrations (40, 80, 120, 200 mg/L, groups M40, M80, M120 and M200 respectively). Then the cells of different groups were incubated for 48 h. An apoptosis detection kit was used for annexin V and PI staining, and JC-1 probe was employed to measure mitochondrial depolarization in ASMCs, and the protein of Caspase-3 was measured by Western blot. The apoptosis rates of ASMCs in groups M40, M80, M120 and M200 were (2.95 ± 0.21)%, (7.39 ± 0.63)%, (13.39 ± 0.40)% and (21.20 ± 1.42)%, respectively, all of which were higher than that in the control group (0.94 ± 0.05)%, F = 399.77, P < 0.01. Furthermore, the concentration of moxifloxacin was positively related to the apoptosis rate (r = 0.974, P < 0.01). Compared to the control group (the ratio of orange-red fluorescence to green fluorescence was 10.02 ± 0.20), there was a shift from mitochondrial orange-red fluorescence to green fluorescence among groups with the concentrations of moxifloxacin increasing (6.54 ± 0.15, 4.48 ± 0.14, 2.25 ± 0.10 and 1.99 ± 0.12); the difference was significant (F = 1565.12, P < 0.01), and there was a dose-dependent response (r = -0.946, P < 0.01). The results of Western blot indicated that the expression of Caspase-3 increased with the concentrations of moxifloxacin increasing (0.45 ± 0.05, 0.59 ± 0.04, 0.69 ± 0.06 and 0.84 ± 0.04, respectively), and there was a very low expression of Caspase-3 in the control group (0.31 ± 0.03). The expression of Caspase-3 showed a positive correlation with the concentration of moxifloxacin (r = 0.979, P < 0.01). The apoptosis rate of ASMCs in the different groups had a remarkable correlation with the ΔΨm and Caspase-3 (r = -0.887, P < 0.01; r = 0.955, P < 0.01). There was also a remarkable negative correlation between ΔΨm and Caspase-3 (r = -0.951, P < 0.01). Moxifloxacin was shown to promote ASMC apoptosis by altering ΔΨm.