Reversal of Olfactory Disturbance in Allergic Rhinitis Related to OMP Suppression by Intranasal Budesonide Treatment

Abstract

Purpose: We evaluated the severity of olfactory disturbance (OD) in the murine model of allergic rhinitis (AR) and local allergic rhinitis (LAR) in mice. We also investigated the therapeutic effect of an intranasal steroid on OD.

Methods: Forty BALB/c mice were divided into 5 groups (n = 8 for each). The control group was sensitized intraperitoneally (i.p.) and challenged intranasally (i.n.) with saline. Mice in the AR group got i.p. and i.n. ovalbumin (OVA) administration for AR induction. The LAR group was challenged i.n. with 1% OVA for inducing local nasal allergic inflammation, without inducing the systemic allergy. The OD group got an i.p. methimazole administration (75 mg/kg) to induce total destruction of olfactory mucosa. Mice in the intranasal budesonide group received i.n. budesonide (12.8 μ per time, 30 minutes after the i.n. OVA challenge) while using OVA to cause systemic allergies. We conducted a buried-food pellet test to functionally assess the degree of OD in each group by measuring the time taken until finding hidden food. We evaluated the damage to olfactory epithelium using histopathologic evaluation and compared the degree of olfactory marker protein (OMP) expression in olfactory epithelium using immunofluorescent staining.

Results: Mice of the AR (81.3 ± 19.8 seconds) and LAR groups (66.2 ± 12.7 seconds) spent significantly more time to detect the pellets than the control group (35.6 ± 12.2 seconds, P < 0.01). After treatment, the intranasal budesonide group exhibited significantly better results (35.8 ± 11.9 seconds) compared with the AR and LAR groups (P < 0.01). The AR and LAR groups showed considerable olfactory epithelial damage and suppression of OMP expression compared with the control group. In the intranasal budesonide group, the olfactory lesions and OMP expression had improved substantially.

Conclusions: OD may be caused by olfactory epithelial damage and suppression of OMP expression in nasal allergic inflammation and could be reversed using an intranasal steroid.

Keywords: Olfactory mucosa; allergic rhinitis; odorants; olfaction disorders; olfactory marker protein; ovalbumin; quality of life; steroids.

Fig. 1. Detailed protocol for the treatment of the mice of the (A) control, AR, and intranasal budesonide groups, and the (B) LAR and OD groups.

AR, allergic rhinitis; LAR, local allergic rhinitis; OD, olfactory dysfunction; i.p., intraperitoneal; i.n., intranasal.; OVA, ovalbumin.

Fig. 2. Serum levels of (A) total IgE and (B) OVA-specific IgE.

IgE, immunoglobulin E; OVA, ovalbumin; AR, allergic rhinitis; LAR, local allergic rhinitis; OD, olfactory disturbance. ^*Statistically significant difference from the control group, P < 0.01; ^†Statistically significant difference from the AR group, P < 0.01; the Kruskal-Wallis and Mann-Whitney U tests.

Fig. 3. Number of inflammatory cells (eosinophils, neutrophils, and lymphocytes) in the BAL fluid.

BAL, broncho-alveolar lavage; AR, allergic rhinitis; LAR, local allergic rhinitis; OD, olfactory disturbance. ^*Statistically significant difference from the control group, P < 0.05; ^†Statistically significant difference from the control group, P < 0.01; ^‡Statistically significant difference from the AR group, P < 0.01; the Kruskal-Wallis and Mann-Whitney U tests.

Fig. 4. Time until the hidden-food pellet detection as measured by the “buried-food pellet test.”

NS, not significant; AR, allergic rhinitis; LAR, local allergic rhinitis; OD, olfactory disturbance.

Fig. 5. Histopathological examination of the lung parenchyma (A) and the number of eosinophils that infiltrated into 1 mm² of the lung parenchyma (B).

AR, allergic rhinitis; LAR, local allergic rhinitis; OD, olfactory disturbance; H&E, hematoxylin and eosin; PAS, periodic acid Schiff. ^*Statistically significant difference from the control group, P < 0.01; ^†Statistically significant difference from the control group, P < 0.001; ^‡Statistically significant difference from the AR group, P < 0.001; the Kruskal-Wallis and Mann-Whitney U tests (scale bar = 200 μm).

Fig. 6. Histopathological examination of the (A) nasal septa and (B) turbinate tissues (scale bar = 50 μm).

AR, allergic rhinitis; LAR, local allergic rhinitis; OD, olfactory disturbance; H&E, hematoxylin and eosin; PAS, periodic acid Schiff.

Fig. 7. Histopathological examination of the olfactory epithelia (A) and the number of eosinophils that infiltrated into 1 mm² of the olfactory epithelia (“mucosa” is better. In sirius staining, positive cells are in submucosa area.) (B).

AR, allergic rhinitis; LAR, local allergic rhinitis; OD, olfactory disturbance; H&E, hematoxylin and eosin; PAS, periodic acid Schiff. ^*Statistically significant difference from the control group, P < 0.001; ^†Statistically significant difference from the AR group, P < 0.001; the Kruskal-Wallis and Mann-Whitney U tests (scale bar = 50 μm).

Fig. 8. Expression of OMP by immunofluorescent staining. FITC was used for the conjugation with the secondary antibody against anti-OMP antibody (green color).

OMP, olfactory marker protein; FITC, fluorescein isothiocyanate; AR, allergic rhinitis; LAR, local allergic rhinitis; OD, olfactory disturbance.