[Effects of chronic Aspergillus fumigatus exposure on the expression of mucin 5AC in the airways of asthmatic rats].

OBJECTIVE:To explore the effects of chronic Aspergillus fumigatus (Af) exposure on the expression of mucin 5AC (MUC5AC) in the airways of asthmatic rats. METHODS:Fifty-six male Wistar rats were randomly divided into 8 groups: chronic asthma (group A), chronic asthma plus Af spores inhalation for 1 week (group B), 3 weeks (group C) and 5 weeks (group D), chronic asthma plus saline inhalation for 5 weeks (group E), OVA-sensitized and-saline-challenged group (group F) and OVA-sensitized and-saline-challenged plus Af spores inhalation for 5 weeks (group G) (each n = 8). The airway resistance (Raw) and the change rate of Raw after acetylcholine provocation were detected using a computerized system. The level of MUC5AC mRNA in the lung tissue was measured by RT-PCR, and the expression of MUC5AC in airway epithelial cells were demonstrated by immunohistochemistry. The concentration of IL-13 in BALF was measured by ELISA. The extent of goblet cell hyperplasia was evaluated on periodic acid-Schiff stain (PAS) lung sections. RESULTS:In group B, C, and D, the level of MUC5AC mRNA (MUC5AC mRNA/β-actin mRNA) (1.9 ± 0.4, 2.3 ± 0.6, 2.9 ± 0.8, respectively), the integrated optical density (value A) of MUC5AC positive stain in airway epithelial cells (278 ± 58, 566 ± 64, 891 ± 80, respectively), the concentration of IL-13 in BALF (µg/L) (96 ± 16, 136 ± 22, 197 ± 34, respectively), and the ratio of goblet cell area to epithelial cell area(%) (16 ± 5, 23 ± 7, 36 ± 9, respectively), were higher than those in group A, E, F and G (all P < 0.05). The change rate of Raw(%) in group C and D (61.91 ± 5.26 and 84.69 ± 6.38) were higher than that in group A, E, F and G (all P < 0.05). The level of MUC5AC mRNA and the value A of MUC5AC were positively correlated with the ratio of goblet cell area to epithelial cell area (r = 0.578, P < 0.05;r = 0.614, P < 0.05, respectively) and the change rate of Raw (r = 0.638, P < 0.05;r = 0.564, P < 0.05, respectively) in group B, C and D. CONCLUSION:Chronic Aspergillus fumigatus exposure upregulated the expression of MUC5AC in the airway epithelial cells and induced goblet cell hyperplasia, resulting in increased airway hypersensitivity in rats with chronic asthma.

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