Mycoplamal Macrophage-activating Lipopeptide-2 Induces The Secretion Of MUC5AC In Airway Epithelial Cells Via MMP-9/TGF-α/EGFR Pathway

Mucus is an elastic gel and is mainly composed of water and mucin, which are distributed in airway surface and secreted by epithelial goblet cell or sub mucosal gland cell. MUC5 AC is the major mucin of human airways. Mucins can form a protective coating that resist foreign particles and microbes. The aberrant mucin expression can be induced by pathological conditions, such as pathogen infection or smoking. The mycoplasma infection can promote airway epithelial cells secrete MUC5 AC, which participate in chronic obstructive pulmonary disease(COPD). However, the mechanisms remain unclear. The aim of this study was to investigate the molecular mechanism of the mycoplamal macrophage activating lipopeptide-2(MALP-2) stimulates airway epithelial cells to secrete MUC5 AC. The airway epithelial cell line NCI-H292 was cultured in vitro, then was stimulated with MALP-2 for indicative times, the mRNA and protein expressions of NUC5 AC were detected by real time PCR or western blot, respectively. MMP-9 and TGF-α were detected by ELISA. Western blot was used to analyze the phosphorylation of EGFR. Cells were pre-incubated with the inhibitor ofEGFR and MMP-9 or the antibody of TGF-α to observe the involvement of EGFR, MMP or TGF-α in secretion of MUC5 A. Our results showed NCI-H292 cells pretreated with 0.1, 1.0 and 5.0μg/mL MALP-2 for 24 h can secrete MUC5 AC in a dose and time dependent manner. The MUC5 AC was significantly induced by 5 μg/mL of MALP-2 for 8 h,reached the peak level at 36 h and lasted to 48 h. The same results were obtained from real-time PCR. MALP-2 could stimulate the secretion of MMP-9 and TGF-α in NCI-H292 cells. When the cells were pretreated with MMP-9 inhibitor, the expression of TGF-α and MUC5 AC were significantly decreased. The phosphorylation of EGFR in NCI-H292 could be induced by 5μg/mL of MALP-2 for 0~4h. Pretreatment with the neutralizing antibody against EGFR for 30 min or with the inhibitor of EGFR AG-1278 in cells could decrease the expression of MUC5 AC in NCI-H292. These results indicate that MALP-2 can induce MUC5 AC via MMP-9/TGF-a/EGFR pathway in NCI-H292 cell.