Effect of Sublingual Immunotherapy on Airway Inflammation and Airway Wall Thickness in Allergic Asthma

Abstract

Background: The efficacy of the standardized quality (SQ) house dust mite (HDM) sublingual immunotherapy (SLIT) has been demonstrated for respiratory allergic disease. However, the effects of SLIT on inflammation and structural changes of the airways are still unknown.

Objective: The aim of this study was to assess the effects of the 6 SQ-HDM SLIT on airway inflammation and airway geometry in allergic asthma and rhinitis.

Methods: One hundred two asthmatic patients with rhinitis sensitized to HDM were randomized to receive either SLIT plus pharmacotherapy or standard pharmacotherapy alone, for 48 weeks. Fractional exhaled nitric oxide (FeNO), pulmonary function, quantitative computed tomography, and clinical symptoms were performed at baseline and end of the study.

Results: Compared with pharmacotherapy, SLIT demonstrated a significant reduction of FeNO (P < .01), airway wall area/body surface area (WA/BSA, P < .001), wall thickness (T/√BSA, P < .001), percentage wall area (WA/Ao, P < .01), increase in luminal area (Ai/BSA, P < .05), improvement of airflow limitation (P < .001), and clinical symptom scores (P < .05). The change in forced expiratory volume in 1 second (FEV₁) was correlated with both changes in FeNO and airway dimensions. Multiple regression analysis showed that the change in FeNO was independently associated with an increase in FEV₁ in the SLIT group (r² = 0.623, P = .037).

Conclusions: Adding 6 SQ-HDM SLIT to standard asthma therapy provides a significant improvement in symptoms and pulmonary function compared with pharmacotherapy. Improvement of airflow limitation with SLIT was associated with the decrease in eosinophilic airway inflammation.

Keywords: Airway inflammation; Airway wall thickness; Asthma; House dust mite; Remodeling; Rhinitis; Sublingual immunotherapy.