Expression of inducible nitric oxide synthase (iNOS) is increased in the bronchial epithelium of allergic asthmatics following allergen provocation.

<p>Bronchial biopsies were collected during fiberoptic bronchoscopy of allergic asthmatics (n = 9), before (light grey) and 24 hours after allergen provocation (dark grey). Representative image of the epithelial (Ep) expression of iNOS (brown color) was assessed by immunohistochemistry in bronchial biopsies from allergic asthmatics A) before and B) after allergen provocation. Cell nuclei were counterstained with Mayer's haematoxylin (blue stain). Morphometric analysis was performed. Samples where intact bronchial epithelium could not be identified were omitted from the analysis. Epithelial cells detached from the basal membrane were excluded (indicated by arrow). C) Percentage of bronchial epithelium positive for iNOS immunoreactivity and D) correlation analysis of the percentage of positive epithelium and fractional exhaled nitric oxide (FENO) using Pearson correlation test of linear regression. Significant differences were detected using paired t-test. Scale bars indicate 200 µm. *** indicates p<0.001.