Beyond anti-microbial properties: The role of cathelicidin in allergic rhinitis.

Background: Cathelicidin, an anti-microbial peptide, is a component of the innate immune system. Cathelicidin has anti-microbial, anti-inflammatory and immunoregulatory functions. Knowledge about the role of the innate immune system in the pathogenesis of allergic diseases has expanded in recent years. We measured levels of the LL-37 peptide in the nasal fluids of children with allergic rhinitis (AR) and investigated the possible role of this peptide in the pathogenesis of AR. Methods: The study population included 46 children who were newly diagnosed with AR and not taking any medication. Thirty-three healthy control subjects were also enrolled. Nasal secretions were collected from the study and control groups using a polyurethane sponge nasal secretion collector, and nasal fluid LL-37 levels were determined using the ELISA method. Results: The levels of LL-37 in the nasal fluid of the AR patients were lower than those of the control group (median of 2.3 ng/ml [minimum-maximum, 2.1-3.2] vs. 2.6 ng/ml [2.1-5.4], respectively; p<0.001), and they were significantly reduced in patients with moderate/severe AR compared with those of patients with mild AR (2.2 ng/ml [2.1-2.4] vs. 2.5 ng/ml [2.1-3.1], respectively; p<0.001). Conclusion: Our results show that children with AR have reduced nasal fluid LL-37 levels compared with healthy controls. Additionally, children with moderate/severe AR have decreased nasal fluid LL-37 levels compared with children with mild AR. These findings highlight the role of cathelicidin in the pathogenesis of AR. (C) 2015 SEICAP. Published by Elsevier Espana, S.L.U. All rights reserved.