Role of SPDEF in rhinovirus-induced mucin production by differentiated airway epithelial cells
Cellular and molecular mechanisms (English)Background:
Acute exacerbations contribute to morbidity and mortality in COPD and asthma, and are associated with respiratory viral infections. Human rhinoviruses (HRV) are a major trigger of these acute exacerbations, which are characterized by increased inflammation and mucus production. Epithelial mucin production is regulated by various pathways, including those involving SAM-pointed domain-containing Ets-like factor (SPDEF), forkhead box protein 3 (FOXA3) and anterior gradient 2 (AGR2). The aim of the present study was to investigate the role of this SPDEF regulatory network in HRV-induced mucin production in well-differentiated human primary bronchial epithelial cells (PBEC).
PBEC were cultured at the air-liquid interface (ALI) for 21 days to achieve mucociliary differentiation. Next ALI-PBEC were infected with HRV-A16 or HRV-1B at different MOI (0.1, 1, 5). Cells, apical washes and basal conditioned medium were harvested at 24, 48 and 72 h after infection. Samples were analysed by RT-PCR, ELISA, Western blot, confocal and PAS staining.
Both HRV-A16 and HRV-1B increased mucin gene expression and protein levels (MUC5AC and MUC5B) dose dependently, and modulated the SPDEF network including SPDEF, FOXA3, FOXA2 and AGR2.Following HRV-A16 (MOI 5) infection, SPDEF gene expression was increased by 5.6-fold and FOXA3 gene expression was increased by 8.6-fold in ALI-PBEC at 48 h after infection. HRV-A16 also increased AGR2 gene expression and decreased FOXA2 gene expression. HRV-A16 affected epithelial cell differentiation, as shown by a decrease in FOXj1 (ciliated cell marker) and SCGB1A1 expression (club cell marker), and increased MUC5AC and MUC5B (goblet cell markers).
These data show that HRV increases mucin production in ALI-PBEC and that this associated with activation of the SPDEF regulatory network.
This study was supported in part by a grant from the China Scholarship Council and from Boehringer Ingelheim.