Inflammatory cells as well as epithelial cells in nasal polyps express vascular endothelial growth factor

In nasal polyps (NPs), locally secreted growth factors are involved in the remodelling of the epithelium and extracellular matrix but little is known concerning vessel remodelling. The in situ expression of vascular endotheli al growth factor (VEGF) in NPs and control nasal mucosa (CM) were evaluated and in vitro secretion of VEGF from primary human cultures of nasal epithe lial cells (HNECs) was quantified. VEGF expression was evaluated in NP (n=14) and CM (n=6) after immunolabelli ng. In supernatants from HNECs cultured at air/liquid interface, VEGF was q uantified by immunoassay, under baseline conditions and after transforming growth factor-beta 1 (TGF-beta 1) stimulation. In HNEC lysates, VEGF and VE GF messenger ribonucleic acid (mRNA) were detected using Western blot analy sis and reverse transcriptase polymerase chain reaction respectively. VEGF positivity was more frequent in inflammatory cells in NPs (14 of 14) t han in CM (three of sis) (P<0.05) and in the epithelium in NPs (six of 14) than in Chi (two of sis) (nonsignificant), Under baseline conditions, the V EGF concentration in HNEC culture medium increased from day 2 to 4, then de creased and became undetectable. VEGF concentrations increased significantl y after TGF-beta 1 stimulation. In HNEC lysates, VEGF and VEGF mRNA were de tected on days 4 and 14 of culture. It was concluded that vascular endothelial growth factor is intensely expre ssed in situ in nasal polyps, mainly in inflammatory cells but also in epit helial cells. Human nasal epithelial cells are able to secrete in vitro vas cular endothelial growth factor, Transforming growth factor-beta 1 upregula tes this secretion. This suggests that vascular endothelial growth factor, inducing oedema and angiogenesis, could be involved in the pathogenesis of nasal polyps.