Aspergillus fumigatus extracts upregulated mucin 5AC expression in human 16HBE bronchial epithelial cells through activation of the EGFR-MEK-ERK1/2 pathway

Background: It has been demonstrated that Aspergillus fumigatus exposure leads to upregulation of MUC5AC expression in the airways epithelial cells. However, the signal pathway through which Aspergillus fumigatus induce MUC5AC expression is unknown. In this study the possible signal pathways of Aspergillus fumigatus extract (AFE) to regulate the expression of MUC5AC were investigated in human bronchial epithelial cells. Methods The 16HBE cells were divided into 4 groups: normal medium control group, AFE-treated group, AFE + selective inhibitor of protein tyrosine kinase of EGFR (AG1478) treated group, and AFE + inhibitor of MAPK kinase (MEK) (PD98059) treated group. The expression of EGFR, extracellular-signal regulated kinase 1/2 (ERK1/2), phospho-EGFR, phospho-ERK1/2 and MUC5AC were measured by immunofluorescence, immunohistochemistry, RT-PCR, and Western blot . Results Incubation with 16HBE cells for 24 h, AFE dose-dependently upregulated the expression of EGFR and ERK1/2; Incubation with 16HBE cells for 1 h, 16mg/L of AFE induced phosphorylation of EGFR and ERK1/2; Incubation with 16HBE cells, 10 M/L of AG1478 inhibited the phosphorylation of EGFR and ERK1/2, whereas 30 M/L of PD98059 only inhibited the phosphorylation of ERK1/2 and had no influence on the phosphorylation of EGFR. 16mg/L of AFE upregulated the expression of MUC5AC in 16HBE cells. The expression of MUC5AC induced by AFE in 16HBE cells could be inhibited after incubation with AG1478 or PD98059. Conclusion Activation of EGFR-MEK-ERK1/2 signal pathway is one of the mechanisms by which Aspergillus fumigatus upregulate the expression of MUC5AC in 16HBE cells.