Association of Serum Vitamin D Levels, IL-17a Levels with Disease Severity among 3- to 18-year-old Children with Asthma in the Philippine General Hospital

Abstract

Background. Previous studies show that Vitamin D has an inverse relationship with asthma severity, symptoms, exacerbations, medication usage, and a direct relationship with lung function. IL-17A was found to be increased in asthmatics, which was inhibited by Vitamin D. Associations found between vitamin D, IL-17A, and asthma may support the future role of vitamin D in the treatment of asthma in children. Objective. To compare vitamin D and IL-17A levels between children with and without asthma and determine their association with asthma severity Study Design. Cross-sectional study Methods. There were 44 participants, aged 3 to 18 years: 22 with asthma (12 non-severe, 10 severe) and 22 without asthma. Participants with any disease-altering vitamin D metabolism, intake of vitamin D supplementation, and recent infection were excluded. Serum vitamin D and IL-17A levels were measured in all participants. Results. There was no significant difference in mean vitamin D levels between participants with asthma (29.6 ± 12.6 ng/mL) and without asthma (27.6 ± 9.5 ng/mL) (p = 0.55) as well as between participants with non-severe asthma (29.8 ± 14.0 ng/mL) and severe asthma (29.4 ± 11.5 ng/mL) (p = 0.95). The overall prevalence of hypovitaminosis D (< 30ng/mL) is 61.4%; 59.1% among those with asthma and 63.6% without asthma. The prevalence of vitamin D insufficiency and/or deficiency did not significantly differ between those with and without asthma (all p-value > 0.05); prevalence ratios were: 1.05 for vitamin D insufficiency, 0.58 for vitamin deficiency, and 0.92 for vitamin D insufficiency and deficiency combined. There was also no significant difference in the prevalence of vitamin D insufficiency and/or deficiency between severe and non-severe asthma (all p-values > 0.05), with prevalence ratios: 0.74 for vitamin D insufficiency, 0.50 for vitamin D deficiency, and 0.75 for vitamin D insufficiency and deficiency combined. Serum IL-17A levels were below the minimum detectable levels in 96% of the participants using the MILLIPLEX Map Human TH17 Magnetic Band Panel; hence, could not be analyzed. Conclusion. The mean serum vitamin D levels do not differ between children with asthma and healthy controls. There was no significant relationship between mean vitamin D levels and asthma severity. There was no association between the prevalence of vitamin D insufficiency and/or deficiency and asthma and its severity. The overall prevalence of hypovitaminosis D in this study is 61.4%. Serum IL-17A levels were undetectable in 96% of the study population.