25-Hydroxyvitamin D, biomarkers of eosinophilic inflammation, and airway remodeling in children with newly diagnosed untreated asthma.

BACKGROUND

Low 25-hydroxyvitamin D (25[OH]D) and asthma development may be related to airway remodeling and eosinophilia. Periostin is proposed as a key molecule that links remodeling and eosinophilic inflammation.

OBJECTIVE

We evaluated the association of 25(OH)D concentration with periostin, peripheral blood eosinophil counts, and immunoglobulin E (IgE) in children with newly diagnosed asthma.

METHODS

The study included 150 children: 110 with atopic asthma and 40 constituted a reference group. Fasting blood was collected for cell counts and serum for measurements of 25(OH)D, periostin, IgE, and C-reactive protein (CRP) concentrations.

RESULTS

Significantly lower 25(OH)D, elevated IgE concentrations, and eosinophil counts were found in children with asthma compared with the reference group (p = 0.0001). A lower forced expiratory volume in the first second of expiration percentage predicted value was associated with a lower 25(OH)D value in children with asthma. The bronchodilator reversibility was inversely related to serum 25(OH)D concentrations (R = -0.45, p = 0.029). The children with asthma and with a 25(OH)D deficient concentration (≤20 ng/mL) had higher concentrations of periostin (p = 0.035) and CRP (p = 0.01) than those with a sufficient 25(OH)D concentration (≥30 ng/L). Additional analysis revealed statistically significant differences (p = 0.013) when comparing periostin concentrations between subjects with a 25(OH)D deficient concentration (≤20 ng/mL) and subjects who did not have a deficient concentration (>20 ng/mL). In individuals with asthma, a 25(OH)D concentration of <30 ng/mL had no impact on eosinophilia, whereas IgE concentrations were associated with increased eosinophils, and the effect of periostin on eosinophilia was small although significant. Multivariate regression, including 25(OH)D concentration, CRP level, eosinophil counts, and sex, accounted for 7% of periostin variation in subjects with asthma.

CONCLUSION

In newly diagnosed pediatric asthma, 25(OH)D concentrations revealed a small although significant association with periostin levels but no effect on eosinophilia. A low vitamin D concentration may increase airway remodeling induced by inflammatory mediators, but further clinical studies aimed to explain the causal link between vitamin D insufficiency and asthma are needed.