Unraveling the role of miR-223-3p in the regulation of airway inflammation in asthma

Abstract

We recently found higher miR-223-3p levels in sputum of asthma patients compared to controls. We hypothesized that miR-223-3p regulates pro-inflammatory responses to well-known risk factors for asthma, i.e. allergic sensitization and viral infection and could thus contribute to the regulation of airway inflammation in asthma. The aim was to validate miR-223-3p expression in bronchial biopsies from an independent asthma cohort and to study whether miR-223-3p increases pro-inflammatory activity of human bronchial epithelial cells (16HBE). MiR-223-3p expression was investigated in bronchial biopsies of asthma patients (n=46) and healthy controls (n=82) using RNA-sequencing. 16HBE cells were exposed to house dust mite (HDM) or viral mimic poly-(I:C) and miR-223-3p expression levels were measured by qPCR. 16HBE cells were transfected with miR-223-3p mimic, incubated with HDM or poly-(I:C) and secretion of pro-inflammatory cytokine CCL20 was measured using ELISA. Significantly higher levels of miR-223-3p were validated in bronchial biopsies from asthma patients compared to controls. In vitro, miR-223-3p was hardly detectable in 16HBE cells. Overexpression of miR-223-3p in 16HBE cells resulted in significantly higher basal and poly-(I:C)-induced CCL20 secretion, with a similar trend for HDM-induced CCL20 levels. In conclusion, we confirmed increased expression of miR-223-3p in airways of asthma patients compared to healthy controls. Overexpression of miR-223-3p in human bronchial epithelial cells resulted in higher CCL20 levels. This suggests that increased levels of miR-223-3p in asthma, e.g. when secreted in exosomes may contribute to the release of the pro-inflammatory CCL20 by airway epithelial cells.