Exposure To Consistent And Controlled Levels Of Aerosolized Dust Mite Allergen Evokes Ocular Symptoms In Dust Mite Allergic Patients

Abstract

RATIONALE: Dust mite allergen (DMA) is one of the most common aeroallergens causing allergic sensitization and asthma worldwide. Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) are the two major DMA in North America. Induction of ocular symptoms by Der p was assessed in an Environmental Exposure Chamber (EEC). METHODS: Patients with positive SPT to Der p and/or Der f were exposed for 3 hours to aerosolized Der p allergen (10-120ng/m3) on 4 consecutive days (V2-V5). Symptoms were collected and assessed [nasal congestion, rhinorrhea, sneezing, itchy nose, itchy eyes, watery eyes, red eyes and itchy ear/palate; 0-3 scale] at pre-EEC, 10, 20, 30, 45, 60, 90, 120, 150, and 180 minutes (Mean±SEM). RESULTS: Significant total ocular symptom scores (itchy, watery, red eyes: TOSS) were reported by patients who qualified based on nasal and total symptoms scores (≥6/12 total nasal symptom score,≥10/24 total symptom score). During the first EEC visit (V2), pre-EEC TOSS was 0.2±0.08. By 150 and 180 minutes, mean TOSS was approximately 4.6 (max=9). There was some “priming” effect as patients returned for V3 with pre-EEC TOSS of 0.7±0.20 units. However, TOSS increased to levels similar to V2 with a maximum mean TOSS of 4.7±0.40 units. Similarly, pre-EEC TOSS was reported at 0.6±0.22 (V4) and 1.1±0.32 units (V5) with maximum TOSS of approximately 4.9 (V4) and 4.6 (V5) units. CONCLUSIONS: Dust Mite Allergen clinical model in an EEC is a safe, well-controlled environment whereby patients can be exposed to consistent levels of aerosolized DMA to evoke significant levels of allergic conjunctivitis symptoms.