Methods: Human nasal epithelial cells (hNEC), RPMI2650 and A549 cell lines were used. Immunoblotting, immunofluorescence and immunohistochemistry were done to evaluate EMT markers and signaling molecules in vitro and in sinonasal tissues from CRS patients with or without NP. Boyden transwell system was utilized to measure the capacity of migration.
Results: Four different cytokines, IL-5, IL-17, TNF-α and IFN-γ, were treated to both hNEC and RPMI2650 cells respectively, and EMT markers were traced. Among them, IFN-γ could most induce EMT, which was confirmed by the spindle-shape of cell morphology, modest cytoskeleton rearrangement, increased migration potential and EMT marker changes. Mechanistically, IFN-γ-induced EMT via ERK and p38 pathway, which were known as non-smad pathway of EMT. Next, we investigated whether p38 and ERK inhibitors could prevent EMT phenomenon. Actually, both p38 inhibitor (SB203580) and ERK inhibitor (PD98059) suppressed IFN-γ-driven EMT. Finally, we checked IFN-γ and EMT marker levels in human nasal mucosa tissues. IFN-γ expression was upregulated in NP mucosa compared with tissues of control and CRS only patients. In addition, this IFN-γ expression was found to correlate with E-cadherin (an epithelial marker) loss and α-smooth muscle actin (a mesenchymal marker) expression.
Conclusion: IFN-γ induce EMT in hNEC and this process is critically mediated by ERK and p38 pathway. This study shows that IFN-γ-induced EMT is likely to contribute to nasal polyposis in CRS, and suggests that p38 and ERK inhibitors be viewed as a therapeutic target for nasal polyposis.
Ref. 1. Shin HW et al., Hypoxia-inducible Factor 1 Mediates Nasal Polypogenesis by Inducing epithelial-to-Mesenchymal Transition. Amer J Resp Crit Care Med, 2012, p944-954.