D2.366 - The establishment of a Japanese cypress pollen environmental exposure chamber protocol

Environmental exposure chambers (EECs) provide a method for stable and reproducible inhalant allergen exposure under standardized environmental conditions. In Japan, most EEC studies have been performed using Japanese cedar pollen (JCeP) with fully validated protocols. However, EEC studies with Japanese cypress pollen (JCyP) are limited and protocols for JCyP exposure have not been completely established. The aim of this study was to establish an EEC protocol for JCyP exposure.

A total of 122 participants were enrolled in the study. Main inclusion criteria were male/female (20-64 years), specific IgE >=class 2 (JCeP and JCyP), and allergic rhinitis symptoms in the 2 JCeP and JCyP seasons prior to study enrollment. Participants were exposed to JCyP for 3 consecutive days. After a 4-week resting period, participants were exposed to JCeP for 2 consecutive days. Exposure conditions were 12,000 grains/m³ of JCyP or JCeP for 3h/day. Four nasal and 2 ocular symptoms (scores range 0-4) were recorded by participants every 0.5h during exposure. The primary endpoint was the total nasal symptom score calculated as the sum of the 4 individual nasal symptom scores recorded during the last 60 minutes of exposure (TNSS_120-180) analyzed using the paired t-test and shown as mean±SD.

TNSS_120-180 increased gradually during the 3 consecutive days of JCyP exposure (4.0±2.5, 5.7±2.7, 6.3±2.7, respectively). TNSS_120-180 on Day 3 was statistically significantly higher compared with baseline on Day1; 0.0±0.0 (p<0.0001) and TNSS_120-180 on Day 1 (p<0.0001) and Day 2 (p=0.0021). During the 2 days of JCeP exposure, TNSS_120-180 increased from JCeP-Day1 (5.7±3.1) to JCeP-Day2 (7.0±2.9). Comparing the JCyP EEC session with the JCeP EEC session, TNSS_120-180 on JCyP-Day 3 was statistically significantly lower compared with TNSS_120-180 on JCeP-Day 2 (p=0.0012). There was no significant difference between TNSS_120-180 on JCyP-Day 3 and JCeP-Day 1 (p=0.0641).The EEC challenge-related adverse events comprised 7 events in 4 participants. All were mild or moderate, and no events led to discontinuation of the study.

JCyP exposure conditions of 12,000 grains/m³ for 3 hours/day on 3 consecutive days were safe and well-tolerated. Also, the condition provoked clear symptoms of JCyP allergic rhinitis, although lower than the scores at JCeP EEC session. The protocol for a JCyP environmental exposure chamber was established in this EEC study.