RESUMO
<p><b>OBJECTIVE</b>Chronic rhinosinusitis was often exacerbated by viral infection. A disruption of the mechanisms that regulate the activity of matrix metalloproteinases (MMPs) during viral infection was one possible mechanism responsible for the exacerbation. The purpose of study was to achieve a better understanding of MMP expression in nasal epithelial cells after viral infection.</p><p><b>METHODS</b>Human nasal epithelial cells were isolated from nasal polyp specimens obtained during endoscopic endonasal surgery in chronic rhinosinusitis patients. The expression of MMP-2, MMP-9, and tissue inhibitor of metalloproteinase (TIMP)-1 mRNA in primary human nasal polyp epithelial cells after double stranded RNA (ds RNA) stimulation were investigated.</p><p><b>RESULTS</b>Among the genes whose expression was evaluated, only expression of MMP-9 mRNA increased significantly after dsRNA stimulation (22.61 +/- 5.47 fold increase, Z = -2.52, P = 0.012).</p><p><b>CONCLUSIONS</b>The significant up-regulation of MMP-9 mRNA, which was not modulated by TIMP-1, was an additional source of increased proteolytic activity in virus-infected upper airways that might contribute to the exacerbation of chronic rhinosinusitis with nasal polyps.</p>