The Role Of ICAM-1 And Activation Of Eosinophils To Tissue Remodeling In Nasal Polyps

Background: Remodeling is defined as "model again or differently, reconstruct". It is well studied in the airways of the asthmatic patients. When airway chronic inflammation is not adequately treated, it can result in permanent structural changes and tissue remoldeling in the airways. The airway remodeling involved in epithelial shedding, thickening of the basement membrane (lamina reticularis), an increase in blood vessel cross-sectional area, airway smooth-muscle hyperplasia and hypertrophy, mucous gland and goblet cell hyperplasia, and increased collagen deposition in asthma. Nasal airway remodeling is proved in allergic rhinitis in recent years. However, the pathologic extent of nasal remodeling in patients with rhinitis seems to be far less extensive than that in the bronchi of asthmatic patients. Nasal polyps is characterized with infiltration and activation of eosinophils, which is confirmed to play an important role in the two diseases mentioned above. The three diseases share many other similarities, such as anatomic structure, pathophysiological process, and there are also present differences like the embryologic differentiation. Based on the above similarities and differences, we believe that tissue remodeling also could play a major role in the pathogenesis of nasal polyps. A better understanding of tissue remodeling might help to identify new pathways and new therapeutic strategies to reduce the increasing prevalence. Until now, almost no systemic researches have investigated tissue remodeling in nasal polyps, more studies are urgently required to demonstrate and to better characterize nasal remodeling in patients with nasal polyps.Objectives: To demonstrate the hypothesis that histopathologic features of tissue remodeling of nasal mucosa in nasal polyps, also to analyse the correlation between tissue remodeling and infiltration of ECP+ eosinophils or expression of ICAM-1 (intercellular adhesion molecule-1).Methods: To examine histologic specimens from 28 randomly selected patients with nasal polyps undergoing endoscopic sinus surgery and 8 healthy control subjects. All the patients were proved no suffering from any other allergic diseases such as allergic rhinitis and asthma. Paraffin sections 3μm thick from samples were stained by hematoxylin-and-eosin (H&E) staining for determining eosinophilial infiltration and the shedding of the epithelium, alcian blue(pH, 2.6)-periodic acid-Schiff (AB-PAS) staining for evaluating goblet cell and subepithelial gland, Masson'sTrichrome(MT) staining for observing subepithelial collagen fiber deposition. To test with Immunohistochemistry for ICAM-1 and actived eosinophils (ECP+). The staining results were assessed under optical microscope.The number of ECP+ eosinophils, ICAM-1 positive cells and subepithelial gland in nasal mucosa, AB-PAS-positive cells in the surface epithelium were counted. The area percentage of MT stained extracellular matrix in basemembrane and nasal mucosa and damage of epithelium were measured. Results were given as"mean±standard deviation".The Kolmogorov-Smirnov test was used to determine the data distribution was normal. The"T test"were used to compare the differences between the two groups. The correlation of infiltration and activation of eosinophils (ECP+) or expression of ICAM-1 separately with tissue remodeling were analysed by Pearson analysis. All statistical analysis were performed by computer software SPSS 13.0.Results: Infiltrated eosinophil numbers, ECP+ eosinophils with 86.10% (33.58/39.00) and expression of ICAM-1 are significantly higher in NP tissue compared to control group. ICAM-1 were expressed in part of the activated eosinophils. All histologic specimens from nasal polyps group revealed damage of epithelium, decrease of goblet cell, increase of subepithelial gland, deposition of subepithelial collagen. The infiltration and activation of eosinophils and the expression of ICAM-1 demonstrate positive correlation, and both of them respectively and significantly correlate with the processes of extracellular collagen fiber deposition.Conclusions: Tissue remodeling is confirmed in nasal polyps from our findings. The positive correlation between the infiltration and activation of eosinophils (ECP+) and the expression of ICAM-1, as well as the expression of ICAM-1 in activated eosinophils strongly suggest the ICAM-1 act directly in eosinophil activation, finally caused the injure of nasal mocus and tissue remodeling. Besides, the correlation analysis also proved that the infiltration and activation of eosinophils and the expression of ICAM-1 separately correlate with extracellular collagen fiber deposition, which propose that both of them play an important role in tissue remodeling.