Nasal Levels of Antimicrobial Peptides in Allergic Asthma Patients and Healthy Controls: Differences and Effect of a Short 1,25(OH)₂ Vitamin D3 Treatment

<div><p>Background</p><p>Allergy is often accompanied by infections and lower levels of antimicrobial peptides (AMPs). Vitamin D has been shown to increase expression of selected AMPs. In this study we investigated whether antimicrobial peptide levels in nasal secretions of allergic asthma patients are lower than in healthy controls, and whether administration of the active form of vitamin D (1,25(OH)₂D3) affects these antimicrobial peptide levels.</p><p>Methods</p><p>The levels of antimicrobial peptides in nasal secretions were compared between 19 allergic asthma patients and 23 healthy controls. The effect of seven days daily oral treatment with 2 μg 1,25(OH)₂D3 on antimicrobial peptides in nasal secretions was assessed in a placebo-controlled cross-over clinical study.</p><p>Results</p><p>Levels of neutrophil α-defensins (human neutrophil peptides 1–3; HNP1-3) and lipocalin 2 (LCN2; also known as NGAL) were significantly lower in asthmatics, but no differences in LL-37 and SLPI were detected. Treatment with a short-term 1,25(OH)₂D3 caused a small increase in HNP1-3, but not when the asthma and control groups were analyzed separately. LL-37, LCN2 and SLPI did not change after treatment with 1,25(OH)₂D3.</p><p>Conclusion</p><p>Levels of the antimicrobial peptides HNP1-3 and LCN2 are lower in nasal secretions in asthmatics and are not substantially affected by a short-term treatment with active vitamin D.</p></div

Baseline AMPs, in nasal secretions.

<p>HNP1-3, LL-37, LCN2 and SLPI in nasal secretions from atopic asthma patients and healthy controls.</p

Effect of 1,25(OH)₂D3 treatment on levels of AMPs in nasal secretions.

<p>Change in levels of HNP1-3, LL-37, LCN2 and SLPI in nasal secretions from asthma patients and controls during placebo or 1,25(OH)₂D3 treatment. The horizontal bars represent the median AMP level before and after treatment.</p

Single-blind, placebo-controlled cross-over design of the present study.

<p>Single-blind, placebo-controlled cross-over design of the present study.</p

Clinical characteristics of the study population according to asthma status.

<p>BMI: Body mass index; IQR: Interquartile range; SD standard deviation, NA: not applicable; FEV₁: percent predicted of FEV₁, ppb parts per billion p-values for differences between groups</p><p>Clinical characteristics of the study population according to asthma status.</p