Poly(I:C) Exacerbates Airway Goblet Cell Hyperplasia and Lung Inflammation in HDM-Exposed Balb/C Mice by YAP/FOXM1 Pathway

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.

Callosal projections in the visual cortex and the vertical meridian of the visual field in the albino rat

Studies using electrophysiological and HRP-labeling techniques showed that the lateral border of physiologically determined primary visual cortex coincides with the cytoarchiectonically defined area 17/18a border. The dense callosal projections are distributed in a zone, about 1.5 mm wide, along this border, which lies in the callosal zone, about 1/4-1/3 of the zone width from its lateral limit. There are two representations of the vertical meridian of the visual field, one in the proper of area 17, about 1/3 of the zone width from its medial limit, the other in area 18a, at about the lateral zone limit.

Binocular responses in the superior colliculus of the albino rat

The retinotopic map for the contralateral eye is similar to that found in the pigmented rats and in other rodents. Cells which had ipsilateral responses were recorded in a fairly large area in the rostral portion of the tectum. Their receptive fields lay from about 40 degrees in the contralateral hemifield to about 40 degrees in the ipsilateral hemifield. The ipsilateral response of a binocular cell is similar in almost every respect to its counterpart in the opposite eye except being very weak and that the receptive field is usually smaller. Most binocular cells are distributed in the Stratum griseum superficiale (SGS) and the Stratum opticum (SO). Less binocular cells recorded in the Stratum griseum intermediale (SGI) have more scattered distribution both in the size and in the position of the receptive field.