Immunohistological Study of Wound Healing after Submucosal Radiofrequency Tissue Ablation of Inferior Nasal Turbinate in a Sheep Model

Abstract

Background Data on the molecular processes involved in nasal mucosa wound healing after radiofrequency tissue ablation (RTA) of the inferior nasal turbinate (INT) are missing. This study was designed to examine tissue expression of fibronectin, collagen III, CD68, and matrix metalloproteinase (MMP) 9 in the INT (ventral) after RTA in sheep. Methods An experimental randomized controlled study was performed. Seventeen INTs (ventral) of nine sheep were used. RTA was applied in 12 INTs. Turbinate samples were studied 1, 3, and 8 weeks postoperatively (4 samples/time point) and in five control INTs (without surgery). Besides hematoxylin and eosin staining, immunostaining was done for MMP-9, collagen III, fibronectin, and CD68. A quantitative grading ranging between 0 (no immunoreactivity at all) and 100% (profuse immunoreactivity) was performed by a blinded senior pathologist. Comparisons between groups were performed using Mann-Whitney U test and Kruskal-Wallis one-way ANOVA. Spearman's rho correlation coefficients were calculated between histological and/or immunohistological variables. Results At week 8, fibronectin (p = 0.025), collagen III (p = 0.004), and MMP-9 (p < 0.001) immunoreactivity was significantly higher than controls, while immunoreactivity for CD68 was higher, although not significantly (p = 0.114) compared with controls. Strong correlations have been found between mucosal vascularization and interstitial space volume (r = 0.776), interstitial space volume and epithelial cell necrosis (r = 0.730), and CD68 immunostaining and epithelial cell necrosis (r = 0.784). Conclusion Given their high tissue concentrations after RTA application, fibronectin, collagen III, CD68, and MMP-9 deserve further study as candidate modulators of the INT wound-healing process.