Expression of IL-17 and syndecan-1 in nasal polyps and their correlation with nasal polyps

Nasal polyp (NP) is a common chronic inflammatory disease of the nasal cavity and sinuses. Although some authors have suggested that NP is related to inflammatory factors such as interleukin (IL)-1β, IL-5, IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor (TNF)-α, and IL-17, the mechanisms underlying the pathogenesis and progression of NP remain obscure. This study investigated the expression and distribution of IL-17 and syndecan-1 in NP, and explored the roles of these two molecules in the pathogenesis of eosinophilic chronic rhinosinusitis with nasal polyps (Eos CRSwNP) and non-Eos CRSwNP. Real-time PCR and immunohistochemistry were used to detect the expression of IL-17 and syndecan-1 in samples [NP, unciform process (UP) from patients with CRS, and middle turbinate (MT) from healthy controls undergoing pituitary tumor surgery]. The results showed that the expression levels of IL-17 and syndecan-1 were upregulated in both NP and UP tissues, but both factors were higher in NP tissues than in UP tissues. There was no significant difference in IL-17 levels between the Eos CRSwNP and non-Eos CRSwNP samples, and syndecan-1 levels were increased in the non-Eos CRSwNP tissues as compared with those in Eos CRSwNP tissues. In all of the groups, there was a close correlation between the expression of IL-17 and syndecan-1 in nasal mucosa epithelial cells, glandular epithelial cells, and inflammatory cells, suggesting that IL-17 and syndecan-1 may play a role, and interact with each other, in the pathogenesis of non-Eos CRSwNP.