Abstract:

Objective To investigate the effects of a disintegrin and metalloprotease 33 (ADAM33) on the proliferation and apoptosis of human airway smooth muscle cells (HASMCs) and the effects of interleukin-4 (IL-4) on the expression of ADAM33. Methods The HASMCs were stimulated by IL-4 in concentrations of 1, 10, 50, and 100 ng/mL. The unstimulated HASMCs were used as controls. The expressions of ADAM33 mRNA and ADAM33 protein were detected by the Real-Time PCR and Western blotting. ADAM33-siRNA was designed, synthesized, and transiently transfected to HASMCs. siRNA with the highest inhibition rate was screened by the Real-Time PCR and Western blotting and transiently transfected to HASMCs. The proliferation and apoptosis of cells were detected by the MTS and flow cytometry, respectively. Results The expressions of ADAM33 mRNA and ADAM33 protein were concentration-dependent for different concentrations of IL-4. Compared to the control group, the relative expressions of mRNA and protein of groups with IL-4 of 50 ng/mL and 100 ng/mL increased by 5.94 and 7.6 times, and 3.72 and 4.57 times, respectively. The differences were statistically significant (P<0.05). But the relative expressions of mRNA and ADAM33 protein of groups with IL-4 of 1 ng/mL and 10 ng/mL were not significant increased. The differences were not statistically significant (P>0.05). For three siRNA, the inhibition rate of ADAM33-siRNA-575 was the highest. The inhibition rate was 81.08% at the mRNA level. The cell proliferation of the intervention group was significantly lower than that of the negative control group at 24, 48, and 72 h (P<0.05). The inhibition rates were 15.38%, 32.83%, and 22.78%, respectively. The apoptotic rate of the intervention group was (25.88±3.37)%, which was significantly higher than that of the negative control group [(8.95±0.51)%](P<0.05). Conclusion ADAM33 can promote the proliferation of airway smooth muscle cells and cytokine IL-4 can promote its expression. Both of them may play important roles in airway remodeling.

Key words: a disintegrin and metalloprotease 33, asthma, airway remodeling, airway smooth muscle cells