Effect of eosinophils activated with Alternaria on the production of extracellular matrix from nasal fibroblasts

Abstract

Background: Eosinophils and fibroblasts are known to play major roles in the pathogenesis of nasal polyps. Fungi are commonly found in nasal secretion and are associated with airway inflammation.

Objective: To investigate whether activated eosinophils by airborne fungi can influence the production of extracellular matrix (ECM) from nasal fibroblasts.

Methods: Inferior turbinate and nasal polyp fibroblasts were stimulated with Alternaria or Aspergillus, respectively, for 24 hours and ECM messenger RNA (mRNA) and protein expressions were measured. Eosinophils isolated from healthy volunteers were stimulated with Alternaria or Aspergillus for 4 hours then superoxide, eosinophil peroxidase, and transforming growth factor β1 were measured. Then activated eosinophils were cocultured with nasal fibroblasts for 24 hours, and ECM mRNA expressions were measured.

Results: Alternaria strongly enhanced ECM mRNA expression and protein production from nasal fibroblasts. Alternaria also induced the production of superoxide, eosinophil peroxidase, and transforming growth factor β1 from eosinophils, and activated eosinophils enhanced ECM mRNA expression when they were cocultured without the Transwell insert system.

Conclusion: Eosinophils activated with Alternaria enhanced ECM mRNA expression from nasal polyp fibroblasts. Alternaria plays an important role in tissue fibrosis in the pathogenesis of nasal polyps by directly or indirectly influencing the production of ECM from nasal fibroblasts.