Objective: To investigate the effects of 1,25-(OH)(2)D(3) on the proliferation of passively sensitized human airway smooth muscle cells (HASMCs) and their expressions of MMP-9 and a disintegrin and metalloprotease 33(ADAM33).
Methods: HASMCs were passively sensitized with 10% serum from asthmatic patients. MTT colorimetry assay was used to examine the effect of 1,25-(OH)(2)D(3) on cell proliferation at different concentrations (10(-10) mol/L, 10(-9) mol/L, 10(-8) mol/L, 10(-7) mol/L).By this way, its optimal inhibitory concentration was determined. And then the effects of 1,25-(OH)(2)D(3) at the optimal concentration on cell proliferation was examined by the same MTT assay and cell cycle analysis by flow cytometry. The expressions of MMP-9 and ADAM33 in HASMCs were studied by real-time quantitative RT-PCR and Western blotting analysis.
Results: (1) Inhibition of cell proliferation by 1,25-(OH)(2)D(3) was barely detectable at 10(-10) mol/L. But with the increasing concentration ranging from 10(-9) mol/L to 10(-7) mol/L, 1,25-(OH)(2)D(3) markedly inhibited the cell proliferation concentration-dependently and reached the maximum effect at the concentration of 10(-7) mol/L. Accordingly, 10(-7) mol/L was chosen as the optimal concentration of 1,25-(OH)(2)D(3) for the following study. (2) At the concentration of 10(-7) mol/L, 1,25-(OH)(2)D(3) inhibited the cell proliferation of passively sensitized HASMCs in a time-dependent manner and hampered the G(1)/S transition. (3) 1,25-(OH)(2)D(3) pretreatment attenuated the MMP-9 and ADAM33 protein levels in passively sensitized HASMCs by (63.4 ± 3.6)% and (50.9 ± 2.9)%, respectively (P < 0.01). (4) 1,25-(OH)(2)D(3) significantly inhibited the MMP-9 and ADAM33 mRNA levels in passively sensitized HASMCs by (52.2 ± 2.5)% and (67.8 ± 3.2)%, respectively (P < 0.01).
Conclusion: 1,25-(OH)(2)D(3) has a direct inhibitory effect on passively sensitized HASMCs in vitro, including the inhibition of cell proliferation and the expressions of MMP-9 and ADAM33, which maybe associated with the beneficial role of 1,25-(OH)(2)D(3) in the prevention and therapy of asthmatic airway remodeling.