The effect of double-stranded RNA on extracellular matrix deposition in an in vitro model of the airway mucosa

Bronchial epithelial cells (BECs) and fibroblasts form an epithelial-mesenchymal trophic unit (EMTU) that maintains tissue homeostasis and activates repair responses following injury. In asthma, activation of the EMTU by viral infection is proposed to be linked to disease exacerbation. We hypothesised that viral infection activates BECs to induce repair processes within the EMTU.An EMTU model incorporating polarised BECs (16HBE14o-) and fibroblasts (MRC-5) grown on the apical and basolateral surface of a nanoporous membrane respectively was established and apically challenged with dsRNA (a molecular pattern that mimics viral replication). Ionic permeability was determined by transepithelial electrical resistance and IL-6 release by ELISA. Fibroblast responses were assessed by extracellular matrix (ECM) protein and α-smooth muscle actin (α-SMA) expression by immunofluorescence microscopy or by Western blotting.In the EMTU model, dsRNA increased ionic permeability and IL-6 release relative to BEC monocultures. Supplementation with ascorbic acid, an important co-factor in ECM formation, enhanced ECM deposition in control co-cultures, but had no effect on dsRNA-dependent IL-6 release or ionic permeability. Apical dsRNA challenge increased fibronectin, collagen and α-SMA expression in fibroblasts and increased release of ECM proteins in cell-free supernatants.These data demonstrate that dsRNA elicits an inflammatory response from BECs and induces fibroblasts to d...
Source: European Respiratory Journal - Category: Respiratory Medicine Authors: Tags: Airway Cell Biology and Immunopathology Source Type: research