Impairment of leptin/leptin receptor pathway in nasal epithelium from allergic turbinates

Abstract

BACKGROUND: Allergic rhinitis (AR) is characterized by a remodeling of nasal epithelium. Leptin adipokine has been already identified as a marker of homeostasis in human bronchial epithelial of asthmatics. TGF-β is a multi-functional cytokine and conflicting findings exist regarding its role in the remodeling responses of the upper airways in allergic rhinitis. OBJECTIVE: We sought to investigate ex-vivo the expression of leptin/leptin receptor pathway and TGF-β in human nasal epithelium. METHODS: 41 biopsies of inferior turbinates obtained from allergic patients with AR (A, n = 20) and from healthy control subjects (C, n = 21) were analyzed for leptin/leptin receptor and for TGF-β 1, 2, 3 expression by immunohistochemistry and immunofluorescence staining and quantitative real-time PCR. RESULTS: In allergic turbinates the expression of leptin and its receptor significantly decreased in comparison to healthy controls (p= 0.01 and p= 0.0006 respectively), whereas TGF-β expression did not. Accordingly, leptin receptor mRNA was reduced in AR. Leptin mRNA was not detected in all recruited subjects. Immunofluorescence showed a prevalence of co-localization of leptin and its receptor in basal epithelial cells, whereas TGF-β was mainly localized in apical epithelial cells. CONCLUSION: Leptin/leptin receptor pathway may play a role in epithelium homeostasis also in allergic rhinitis and despite TGF-β is not representative of epithelial nasal remodeling, it is not co-localized with leptin/leptin receptor pathway.