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

The aim of this study was to investigate the expression of Aquaporin 1 (AQP1) and AQP4 in polyp tissue. 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. 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. 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.