Effects of Corticocosteroids and ß2-Agonists on Laryngeal Mucosa in a Rat Model

Can laryngeal allergic reactions be mitigated with inhaled corticosteroids and ß2-agonists?

Background: Respiratory mucosa is consistent throughout the nasal cavity, larynx, trachea and bronchi and can trigger a type I IgE-mediated laryngeal hypersensitivity reaction. The acute allergic response of the larynx is associated with edema. Though the specific mechanisms are unknown, mast cells are thought to play a key role by releasing inflammatory mediators, such as histamine, chemotactic factors, proteases, cytokines and arachidonic acid metabolites. Inhaled corticosteroids are the most efficacious anti-inflammatory agents in the treatment of allergic disease, though they may cause irritation and histological inflammation at the primary sites of contact. ß2-agonists have been to shown to also have anti-inflammatory effects and enhance the effects of corticosteroids through glucocorticosteroid receptor activation.

Study design: Prospective randomized animal study.

Setting: Istanbul Training and Research Hospital, Turkey.

Synopsis: Wistar albino rats (n=32) were sensitized to ovalbumin. Unsensitized rats (n=8) served as controls. The animals were subsequently exposed to aerosolized phosphate buffered saline (n=8), fluticasone propionate (n=8), salbutamol (n=8) or combined salbutamol and fluticasone proprionate (n=8). Laryngeal mucosa was then harvested and examined for inflammatory cell infiltration, mast cell count and degranulation. A localized allergic reaction in the supraglottis was identified, where a similar glottic response was not present. Inhaled corticosteroids reduced the allergic response but were associated with an increased inflammatory response. Combined inhaled cortiosteroids and ß2-agonists minimized both the allergic and inflammatory responses.

Bottom line: This study provides an animal model to characterize the mechanisms of allergy-induced laryngeal edema. It also provides evidence for the combined efficacy of corticosteroids and ß2-agonists in the treatment of laryngeal edema secondary to allergies.

Citation: Akpinar ME, Tekke NS, Yigit O, Ercan F, Durna Y, Kiran D. Histological effects of inhaled corticosteroids and ß2-agonists on laryngeal mucosa in an allergic rat model. Otolaryngol Head Neck Surg. 2013;149:457-465.

—Reviewed by Ravindhra Elluru MD, PhD