Objectives: Urocortin (UCN) is a member of the corticotropin releasing factor (CRF) neuropeptide family. UCN act as locally expressed proinflammatory factor and induce mast cell degranulation, cytokine secretion, and trigger vascular permeability, which are mediated by CRF receptors in peripheral tissues. Considering its functional roles, UCN and its receptors may play a role in the pathogenesis of allergic nasal mucosa. Therefore, we investigated the expression profile and distribution of UCN and CRF receptors in normal and allergic nasal mucosa.
Methods: Reverse transcriptase-polymerase chain reaction, immunohistochemistry, and Western blotting were applied to the normal and allergic nasal mucosa.
Results: The expression levels of UCN and CRF receptors were increased in allergic nasal mucosa in comparison with normal nasal mucosa. In normal nasal mucosa, UCN and CRF receptors were restricted to the vascular endothelium of submucosal cavernous sinusoids where faint staining was found. However, in allergic nasal mucosa, UCN was expressed in small vessels distributed in lamina propria and the vascular endothelium of cavernous sinusoid located in submucosa. Many scattered positive cells were also found in allergic nasal mucosa, probably UCN-positive leukocytes. CRF receptors were also localized in the vascular endothelium of small vessels and cavernous sinusoid.
Conclusions: These results indicate that UCN may play a role in the regulation of vascular swelling in normal nasal mucosa. Moreover, in allergic nasal mucosa, increased expression levels of UCN and its receptors may contribute to increased mucosal swelling and vascular permeability, playing an important role in the pathogenesis of allergic rhinitis.