BACKGROUND: Recent evidence about the various effects of vitamin D (vit D) on innate and adaptive immunity has led to a search for the role of vit D in asthma. It is postulated that a decrease in cathelicidin, a multifunctional host defense molecule, production due to low vit D status may predispose to infectious complications in children with asthma.
OBJECTIVE: The aim of this study was to determine the association of vit D, vit D-binding protein (VDBP) and cathelicidin with acute asthma attacks among children with allergic asthma.
METHODS: This prospective study included 35 patients with acute asthma attack and 32 children with controlled asthma, and all were matched by sampling season, sensitization to mites, and previous severity of asthma. A comprehensive questionnaire about risk factors, blood sampling for 25-hydroxyvitamin D vit D, VDBP, and cathelicidin levels; spirometric indices were used. Factors that influence serum vit D and cathelicidin levels and the development of asthma attacks were evaluated with multivariate analysis.
RESULTS: The mean serum vit D levels of the attack group was significantly lower than that of the controlled asthma group (p < 0.001). The mean cathelicidin level was significantly higher in the acute asthma group than with the controlled subjects with asthma (p = 0.002). There was no difference between the acute and controlled asthma groups in terms of markers of allergy and serum VDBP levels. Risk factors that may influence vit D levels revealed that body mass index (BMI) (p = 0.038), duration of sun exposure (p < 0.001), and amount of dietary vit D (p < 0.001) independently affected serum vit D levels. Risk factors that may result in acute asthma showed that low serum levels of vit D were significantly related to the risk of asthma attacks (p < 0.001, adjusted odds ratio 16.11). Cathelicidin levels showed a significant positive association with asthma attacks and BMI.
CONCLUSIONS: Vit D deficiency showed a significant relationship to the development of asthma attacks independent of cathelicidin deficiency and other factors associated with the severity of chronic asthma.