Does nitrogen dioxide affect inflammatory markers after nasal allergen challenge?

Area of Science:

• Environmental Health
• Allergy and Immunology
• Respiratory Medicine

Background:

• High ambient nitrogen dioxide (NO2) levels are known to worsen bronchial inflammation in response to allergens.
• Previous research focused on the lower airways; this study investigated NO2's impact on the upper airways.

Purpose of the Study:

• To determine if short-term exposure to nitrogen dioxide (NO2) primes the upper airways for an enhanced allergic inflammatory response.
• To assess the effect of NO2 on nasal allergic reactions.

Main Methods:

• Sixteen participants with allergic rhinitis and mild asthma were exposed to purified air or NO2 (500 microg/m3) for 30 minutes.
• A nasal allergen challenge was administered 4 hours post-exposure, followed by nasal lavage and symptom recording at multiple time points.

Main Results:

• No significant differences were observed in eosinophil and neutrophil percentages, eosinophil cationic protein, or myeloperoxidase levels between air and NO2 exposure groups.
• A slight, non-significant trend towards increased sneezing was noted the day after NO2 exposure combined with allergen challenge.

Conclusions:

• Short-term ambient exposure to nitrogen dioxide (NO2) did not appear to prime the upper airways for a heightened inflammatory response to allergens.
• The study did not find evidence of increased activation of inflammatory cells or mediators in the nasal passages following NO2 exposure and allergen challenge.