Abstract
Background: The Wnt signalling pathway is tightly linked to lung development processes. Recent publications suggest an additional role for the Wnt signalling in several respiratory diseases and there is growing evidence for contribution of the Wnt signalling to asthma. Though the impact of IL-4, a key cytokine in asthma, on the Wnt signalling of bronchial epithelial cells is still unknown.
Aim: To investigate the influence of IL-4 on the Wnt signalling in bronchial epithelial cells.
Methods: Primary bronchial epithelial cells (NHBEs) were cultured in the presence of IL-4 and RNA was harvested after 6h, 24h, 48h and 72h of stimulation. The expression of regulated Wnt and FZD genes was analysed using SYBR Green based quantitative PCR. Regulation of selected Wnt signalling proteins was confirmed by Western blot.
Results: Significant gene expression changes of several Wnt ligands and FZD receptors were observed in IL-4 stimulated NHBEs. Wnt5a was 1.3 (95% CI, 1.2-2.0) fold upregulated after 6h, while FZD10 was 6-7 fold upregulated over 48h of IL-4 treatment. In contrast Wnt5b and Wnt7a were about 2 fold downregulated in the presence of IL-4. Wnt4 was time-dependent upregulated with a maximal induction of 3 (95% CI, 1.4-10.7) fold compared to control at 48h. The upregulation of Wnt5a could additional be shown by Western blot.
Conclusion: The results indicate that IL-4 influences the expression of several Wnt signalling proteins in the bronchial epithelium. Interestingly the non-canonical Wnt5a is upregulated in NHBEs in response to IL-4 on transcription and on protein level. However the impact of the regulated Wnt signalling proteins in the asthmatic bronchial epithelium has to be further investigated.
- Copyright ©ERS 2015