Immunohistochemical expression of VEGF and VEGF receptors in nasal polyps as compared to normal turbinate mucosa

The factors involved in the development of chronic inflammation and edema in nasal polyps remain to be clarified. The expression of vascular endothelial growth factor (VEGF) has been described in plasma cells, suggesting that plasma cells may play a major role in the development of edema in nasal polyps through the production of VEGF. We performed immunohistochemical analysis using specific antibodies to VEGF and to the known VEGF receptors, VEGFR-1 and VEGFR-2, on paraffin sections of human nasal polyps (n=11) and controls of human mucosa of the normal middle turbinates (n=6). In normal turbinate mucosa, sporadic immunostaining for VEGF was observed throughout the endothelial cells of the small veins and arteries. VEGFR-1 and VEGFR-2 expression was faint in the healthy turbinates. In nasal polyp tissues, strong immunostaining for VEGF was found in the endothelium of blood vessels and in the infiltrating perivascular inflammatory cells. Fibroblasts also stained for VEGF. Strong immunolabeling to VEGFR-1 was evident in the vascular endothelium, whereas weak to moderate VEGFR-1-staining was generally confined to scattered mononuclear round cells. Mononuclear round cells and the endothelium of capillaries revealed immunoreactivity to VEGFR-2. These findings support a role for VEGF and its receptors, VEGFR-1 and VEGFR-2, in the development and perpetuation of edema and angiogenesis in nasal polyps.