Specificity and reproducibility of nasal biomarkers in patients with allergic rhinitis after allergen challenge chamber exposure

Background Allergic rhinitis is an inflammatory disease that causes cellular influx and mediator release in the nose. These inflammatory changes might be used as nasal biomarkers to assess the efficacy of novel anti-allergic treatments. Objective To assess the specificity and reproducibility of nasal biomarkers in patients with allergic rhinitis after grass pollen exposure in an allergen challenge chamber.MethodsIn a monocenter pilot study, 15 patients with allergic rhinitis and 19 healthy individuals underwent two 4-hour Dactylis glomerate pollen challenges in the challenge chamber with an interval of 21 days. Before challenge, on exit, and after 2 and 22 hours, a nasal lavage was performed and nasal secretions were collected on filter paper to determine a wide panel of cells and mediators. Furthermore, total nasal symptom score, nasal flow, and nasal nitric oxide were measured. Results Pollen exposure significantly increased eosinophil, interleukin (IL) 5, IL-6, IL-13, and macrophage inflammatory protein 1v levels in allergic patients but not in healthy individuals. The effect could be reproduced for eosinophils, IL-5, IL-6, and macrophage inflammatory protein 1v after the second allergen challenge. By contrast, the IL-13 levels were higher and eotaxin levels first increased after repetitive allergen challenge. There was no correlation between total nasal symptom score and elevated cell or cytokine levels. Nasal nitric oxide levels were nonspecifically elevated in both patients with allergy and healthy controls. Conclusion A subset of cellular and soluble biomarkers in nasal lavage and secretion reveals specificity and reproducibility in patients with allergic rhinitis. These can be used to measure the immunologic efficacy of antiallergic treatments in an allergen challenge chamber. Carryover effects attributable to priming must be considered when designing cross-over studies.