INTRODUCTION

Respiratory viral infection in childhood is closely associated with asthmatic attacks. Of all predisposing factors, viral infection is the primary contributor to acute childhood asthma exacerbations. However, the mechanisms involved in viral asthma are unclear. This study attempted to provide insights into molecular mechanisms in respiratory virus-induced acute asthma exacerbations.

METHODS

House dust mite (HDM) was given by intranasal administration to induce asthma in mice. Poly(I:C) was used to mimic the viral infection. A selective YAP inhibitor, verteporfin (VP), was used to investigate the role of the YAP/FOXM1 pathway. The expression of YAP, FOXM1, cytokines, and inflammatory cells in lung tissue, and bronchoalveolar lavage fluid (BALF) was determined using RT-PCR, immunohistochemical, ELISA, and flow cytometry studies. The methacholine challenge assesses airway hyperresponsiveness. In 16HBE cell experiments, we selectively inhibited YAP and FOXM1 by VP and RCM1, respectively, and detected the expression of YAP and FOXM1.

RESULTS

The experimental studies have confirmed the YAP/FOXM1 pathway plays a vital role in the differentiation and proliferation of airway club cells into goblet cells and lung inflammation. Poly(I:C) upregulated the expression of FOXM1 by activating transcription factor YAP in mice airway epithelial cells and then promoted the expression of downstream transcription factors SPDEF/MUC5AC, resulting in airway mucus hypersecretion and hyperresponsiveness. In addition, Poly(I:C) facilitates the expression of inflammatory factors in lung tissue. All of these events induce asthma exacerbations. The in vitro studies have confirmed that YAP positively regulates FOXM1 in airway epithelial cells.

CONCLUSION

Poly(I:C) promotes airway epithelial goblet cell hyperplasia, mucus hypersecretion, and airway hyperresponsiveness. It also upregulates the expression of inflammatory factors in lung tissue and BALF in asthmatic mice by the YAP/FOXM1 pathway, resulting in asthma attacks.