IL-5 synthesis is upregulated in human nasal polyp tissue

TLDR: Investigating a possibly distinct cytokine and chemokine pattern that could explain the characteristic tissue eosinophilia in nasal polyps indicates that IL-5 plays a key role in the pathophysiology of eOSinophilic nasalpolyps and may be produced by eos inophils.

Abstract: Background: In most nasal polyps, tissue eosinophilia is a striking finding, the pathologic mechanism of which is not understood Objective: This study was performed to investigate a possibly distinct cytokine and chemokine pattern that could explain the characteristic tissue eosinophilia in nasal polyps Methods: Polyps from 23 patients and turbinate tissue from 18 control subjects were investigated The cytokine protein content (IL-1β, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, tumor necrosis factor-α, granulocyte-macrophage colony-stimulating factor, IL-1RA, RANTES, GRO-α) of tissue homogenates was measured by ELISA Immunohistochemistry was performed in selected samples to detect IL-5 + , major basic protein-positive, and EG2 + cells Results: IL-5 was detectable in only one sample of tissue from 18 control subjects but was found in 18 of 23 nasal polyps Immunohistochemistry revealed an abundant number of IL-5 + cells, of which 695% could be identified as eosinophils by morphology IL-6, IL-8, IL-10, tumor necrosis factor-α, GRO-α, and RANTES were detected in all specimens, without significant differences between groups ( p ≥005), whereas significantly higher concentrations of IL-1β and IL-1RA were found in turbinate mucosa ( p ≤005) IL-3 was not detectable; granulocyte-macrophage colony-stimulating factor could only occasionally be found Conclusion: This study indicates that IL-5 plays a key role in the pathophysiology of cosinophilic nasal polyps and may be produced by eosinophils