Expression profiles of fibrinolytic components in nasal mucosa

Components of the fibrinolytic pathway contribute to diverse pathways in many tissues, in addition to their well-recognized role in degradation of fibrin clots. In this study of nasal mucosa, we investigated the presence of mRNA of tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitor-1 (PAI-1), and plasminogen activator inhibitor-2 (PAI-2) using reverse transcription polymerase chain reaction (RT-PCR) and in situ hybridization, and compared these results with their localization in immunostained tissues. According to real-time RT-PCR results, t-PA, u-PA, PAI-1, and PAI-2 mRNA were noted in human nasal mucosa. Particularly, expression of u-PA and PAI-1 mRNA was significantly high in allergic nasal mucosa in comparison with normal mucosa. t-PA mRNA was detected in endothelial cells and epithelium in normal nasal mucosa. t-PA mRNA was detected in mucous cells of allergic submucosal glands, but not in normal glands. In allergic rhinitis, u-PA and PAI-2 mRNA were detected in mucinous cells and epithelium, and PAI-1 mRNA was detected in serous cells and epithelium. Expression of u-PA and PAI-1 mRNA in normal nasal tissues was decreased in contrast to that in allergic nasal tissues. u-PA staining was observed in mucous cells of allergic submucosal glands and the staining pattern of PAI-2 was similar to that of u-PA. PAI-1 was present in serous cells of submucosal glands from allergy samples, while epithelial cells were almost devoid of stain. In contrast, with allergy, immunohistochemical staining of t-PA was negative in submucosal glands, though positive in endothelial cells and epithelium. However, the expression of t-PA mRNA in allergic nasal mucosa was noted in mucous cells. In fibrin autography of nasal discharge, u-PA was markedly activated in the allergic patient. These results suggest that t-PA synthesized in mucous cells is promptly secreted and modifies watery nasal discharge in allergic rhinitis, and that u-PA activity may help the passage of large amounts of rhinorrhea by also reducing its viscosity. A lot of cellular infiltration (eosinophils in particular) was recognized in allergic nasal mucosa. It is most likely that the modifications in expression of PAs and PAIs are due to the local release of cytokines or growth factors from these inflammatory and immune cells.