Histological analysis of glucocorticoid receptor and eosinophilic cytokines in the adenoid mucosal epithelium

Objective: In recent years, the clinical efficacy of medications for adenoid hypertrophy has been demonstrated. Topical nasal steroids have effects to shrink hypertrophic adenoids and improve symptoms of associated diseases. However, the mechanism which topical steroid administrations cause adenoid shrinkage remains unclear, herein, sensitivity for topical steroids in the mucosal epithelium of adenoids was evaluated histologically by comparing with tonsils.

Methods: Histological analysis was performed on adenoids and tonsils removed from 32 pediatric patients with adenoid hypertrophy. In hematoxylin-eosin-stained specimens, the morphology of the mucosal epithelium and eosinophil infiltration were evaluated. The expression of the glucocorticoid receptor (GR), interleukin (IL)-4, and IL-25 in the mucosal epithelium was evaluated, and the staining intensity was scored as 0 (none), 1 (weak), and 2 (strong). The number of eosinophils and expression scores of GR, IL-4, and IL-25 were statistically compared between adenoids and tonsils and analyzed correlations with adenoids sizes.

Results: Adenoids were covered with ciliated epithelium, and eosinophils in the mucosal epithelium and submucosal area was higher than tonsils (p < 0.05). GR expression in the most superficial layer of the mucosal epithelium was observed in adenoids, and the expression intensity score was higher than that in tonsils (p < 0.05). IL-4 and IL-25 were more widely expressed in the mucosal epithelium of adenoids than in tonsils, and their expression intensity scores were also higher than in tonsils (p < 0.05). A correlation was found between adenoid size and the intensity of IL-25 expression in the adenoid epithelium (p < 0.05).

Conclusion: Eosinophilic inflammations in adenoids mucosal epithelium could be one of etiology of adenoid hypertrophy, and the GR and eosinophilic inflammation in the adenoids mucosal epithelium might be target of topical nasal steroids to shrink hypertrophic adenoids.