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

Objective: 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.
Methods: 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.
Results: 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).
Conclusion: Moxifloxacin was shown to promote ASMC apoptosis by altering ΔΨm.