Abstract:

Objective To investigate the effects of hyaluronan (HA) and CD44 on airway mucous hypersecretion, and explore the molecular mechanism of activation of epidermal growth factor (EGF)/epidermal growth factor receptor (EGFR) signal transduction pathway by signal factors. Methods BEAS-2B airway epithelial cells were cultured in vitro, and were stimulated by neutrophil elastase (NE). Reactive oxygen species (ROS) scavenger (DMTU), hyaluronidase (Hase), CD44 antibody and tissue kallikrein (TK) inhibitor (PI) were served as interventional factors, and control group (serum free culture), NE stimulation group (50 nmol/L NE), DMTU+NE group (20 μmol/L DMTU+50 nmol/L NE), DMTU+Hase+NE group (20 μmol/L DMTU+10 μg/mL Hase+50 nmol/L NE), CD44Ab+NE group (5 μg/mL CD44Ab+50 nmol/L NE) and PI+NE group (100 μg/mL PI+50 nmol/L NE) were established. The expression of mucin (MUC) 5AC mRNA was detected by RT-PCR, the expression of MUC5AC and EGF protein was determined by ELISA, and the expression of phosphorylated epidermal growth factor receptor (p-EGFR) protein was analysed by Western blotting. Results The expression of MUC5AC, EGF and p-EGFR protein and MUC5AC mRNA in NE stimulation group was significantly higher than that in control group (P<0.01), the expression in DMTU+NE group was significantly lower than that in NE stimulation group (P<0.01), the expression in MTU+Hase+NE group was significantly higher than that in DMTU+NE group (P<0.05 for MUC5AC and p-EGFR protein and MUC5AC mRNA, and P<0.01 for EGF protein), the expression in CD44Ab+NE group and PI+NE group was significantly higher than that in NE stimulation group (P<0.05 for MUC5AC and p-EGFR protein and MUC5AC mRNA, and P<0.01 for EGF protein). Conclusion NE upregulates the expression of MUC5AC gene via OS/HA/CD44/TK/EGF/EGFR signal transduction pathway in airway epithelial cells.

Key words: hyaluronan, CD44, reactive oxygen species, mucin