Apolipoproteins have a potential role in nasal mucus of allergic rhinitis patients: a proteomic study.

Abstract

Nasal mucus is a defense barrier against aeroallergens. We recently found apolipoproteins to be elevated in the nasal mucus of allergic rhinitis patients. Apolipoproteins are involved in lipid metabolism, have immunomodulatory properties, and may represent interesting novel biomarkers. This study aims to validate our findings and analyze whether the increased abundance of apolipoproteins in nasal mucus is a local or systemic phenomenon in allergic rhinitis. Prospective controlled trial. Nasal mucus of allergic rhinitis patients (n = 10) and healthy controls (n = 12) was collected, tryptically digested, and analyzed by LC-MS/MS. Areas under the curve (AUCs) of the total peptides identified and matched to apolipoproteins were used to compare relative protein abundances of the same protein between groups. In a total of 389 identified proteins in nasal mucus, apolipoproteins A-I, A-II, A-IV, and B 100 were detected. Apolipoprotein A-I (mean normalized AUC 1.49% [SEM = 0.5] vs. 0.42% [SEM = 0.2]) and A-II (mean normalized AUC 0.47% [SEM = 0.2] vs. 0.05% [SEM = 0.02]) were significantly more abundant in allergic rhinitis patients than controls (3.6-fold and 9.4-fold, respectively). Apolipoprotein A-IV (mean normalized AUC = 0.01%) and B-100 (mean normalized AUC = 0.02%) were each detected in only one allergic rhinitis patient out of 10. Myeloperoxidase was detected with a mean normalized AUC of 0.06% (SEM = 0.03) in allergic rhinitis patients and 0.18% (SEM = 0.08) in healthy controls without reaching significance. This study confirms the significantly higher abundance of apolipoproteins A-I and AII in allergic rhinitis mucus. Their release seems to be triggered by local mechanisms as an antiinflammatory response to allergens.