Expression of leptin receptor in nasal polyps: leptin as a mucosecretagogue

Leptin is a pleiotropic hormone that regulates food intake and metabolic and endocrine functions. Serum leptin levels have been reported to be increased in patients with allergic rhinitis and nasal polyposis; however, the explanation for this is unclear. We aimed to demonstrate the differential expression of leptin receptors in normal human nasal mucosa and nasal polyps, and to elucidate the effects of leptin on mucin gene expression in human nasal polyp epithelial cells.

Case-control and in vitro study.

Normal ethmoid sinus mucosa was obtained from 10 subjects and used as a control; nasal polyps were obtained from 10 patients. Leptin receptor expression was analyzed using reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis. Leptin-induced expression of major respiratory mucins (MUC5AC and MUC5B) in the human nasal polyp epithelial cells was determined using RT-PCR and enzyme-linked immunosorbent assay.

The leptin receptor expression was stronger in the nasal polyps than in the normal nasal mucosa. In human nasal polyp epithelial cells, leptin increased the expression of MUC5AC and MUC5B, in a dose- and time-dependent manner, at the gene and protein levels. Leptin-induced mucin expression was inhibited by the leptin receptor antagonist.

The increased expression of leptin receptors in nasal polyps implies leptin has a certain role in nasal polyposis. In addition, leptin appears to induce the expression of MUC5AC and MUC5B through leptin receptors in the human nasal polyp epithelial cells.