Expression and distribution of aquaporin-1 in nasal polyps: Does it have any significance in edema formation?

Background: The aim of this study was to investigate the expression of Aquaporin 1 (AQP1) and AQP4 in polyp tissue. Methods: Nasal polyps were obtained from 34 patients with nasal polyposis during endoscopic sinus surgery. Bullous middle turbinates with normal-appearing mucosa of 10 patients were used as controls. Expression of AQP1 and AQP4 water channels were determined by Immunohistochemical methods. Results: AQP1 has been found to be expressed in fibroblasts located in polyp tissue, especially in the subepithelial area, periphery of seromucous glands, and endothelial cells of venules. Conclusion: We have established a high expression of AQP1 water channels in nasal polyp tissue and have suggested two mechanisms to explain this finding. Increased AQP1 expression may be a cause or a consequence of edema formation. Thus, additional studies are needed to elucidate the true mechanism underlying this relationship.