Effects of Aspergillus fumigatus extract on expression of Muc5ac in human bronchial epithelial cells

AIM:To investigate the effects of Aspergillus fumigatus extract (AFE) on the expressions of Muc5ac in human bronchial epithelial cells and its possible mechanism. METHODS: Human bronchial epithelial cells (16HBE-14o) were cultured in vitro, which were exposed to different concentrations of AFE (0, 8, 16, 20 mg/L) for different times. In order to explore the mechanisms, heat-treated AFE, serine protease inhibitors (aprotinin) and protease-activated receptor-2 (PAR-2) antagonist (FSLLRY-NH2) were used. The production and release of Muc5ac in different intervals were tested by immunohistochemistry and ELISA. The expression of Muc5ac mRNA was measured by RT-PCR. RESULTS: In normal control group, only a few Muc5ac was detected. In the experimental groups with AFE exposure, cells produced more Muc5ac compared to normal control group (P0.01), which were positively related to the exposure time or the concentration of AFE. Aprotinin and PAR-2 antagonist (FSLLRY-NH2) inhibited the effect of AFE on Muc5ac production by 16HBE-14o. Heat-treated AFE, which lost protease activities, exerted no effect on Muc5ac production and mRNA expression. CONCLUSION: AFE, depending on its protease activity, activates PAR-2 and causes airway epithelial cells to produce and release more Muc5ac, which may contribute to deterioration of asthma.