Effect of TNF-α on Airway Smooth Muscle Cells Proliferation and the Activity of ERK1/2 in Asthmatic Rats

Objective To investigate the effect of TNF-α on airway smooth muscle cells(ASMCs) proliferation and expression of ERK1/2 mRNA and P-ERK1/2 in asthmatic rats.Methods The rat asthma model was made through ovalbumin(OVA) sensitization and excitation.Primary cultures of ASMCs were established for experiments.ASMCs were treated with 0.2 μg/L,1.0 μg/L,20 μg/L TNF-α.Proliferation of ASMCs was detected by flow cytometry and MTT colorimetric assay,observation of different concentrations of TNF-α on the proliferation of ASMCs.The expressions of ERK1/2 mRNA were detected by RT-PCR,the location and protein expressions of phosphorylated forms of ERK1/2(p-ERK1/2) were examined by immunocytochemical staining.Results The percentage of cells at S phase,A value,The expression quantities of ERK mRNA and p-ERK1/2 protein from asthmatic group were(34.45 ±2.08)%,(0.550 ±0.010),(0.995 ±0.118),(130.77 ±4.16)respectively,significantly increased compared with the control group((11.17 ±0.96)%,(0.292 ±0.008),(0.576 ±0.098),(163.82 ±1.38)respectively,(P0.01));ASMCs in asthmatic group were intervened by the different concentrations of TNF-α,the percentage of cells at S phase,A value,the expression quantities of ERK mRNA and p-ERK1/2 protein were significantly lower than those in the asthmatic group(P0.01).However, the expression quantities of p-ERK1/2 protein in ASMCs from 0.2 μg/L and 1.0 μg/L TNF-α group were higher than that from control group(P0.01),the expression quantities of p-ERK1/2 protein from 20 μg/L TNF-α group were not different from those from control group(P0.05).Conclusion Compared with normal rats,the proliferation of ASMCs in chronic asthmatic rats was obvious,the percentage of cells at S phase was increasing.However, ASMCs in chronic asthmatic rats was intervened by TNF-α,the percentage of cells at S phase was decreased and the proliferation of ASMCs was reduced,TNF-α may inhibit the proliferation of ASMCs in chronic asthmatic rats.TNF-α down-regulated Expression of ERK1/2 mRNA and P-ERK1/2 in asthmatic rats,TNF-α may regulate the proliferation of ASMCs in chronic asthmatic rats by inhibiting the activity of ERK signaling pathway.