Influence of Vitamin D and Cotinine on T-Regulatory Cells and Asthma Severity in Children.

Asthma is a common chronic respiratory diseases in children. Understanding the immune mechanisms of epigenetic factors may contribute to a better control of asthma. This study seeks to determine the effects of serum vitamin D and urine cotinine on asthma severity and on T regulatory cells (Tregs) and other immune-related factors such as CD3, CD4, CD8, CD19, CD16/56, and anti-CD3 HLA-DR3. The study involved 34 children with asthma. Disease severity was assessed with the Asthma Control Test, spirometry, and the fractional exhaled nitric oxide (FeNO). The control group consisted of 18 healthy children. We found a significantly lower proportion of Tregs in the serum of asthmatic children compared with the control group (p < 0.002). There were no significant differences in the other immunological factors investigated. Nor was there any appreciable association between vitamin D or cotinine and the course of asthma, FeNO, Tregs, and the other immune factors. However, the percentage of Tregs was positively associated with the level of FeNO (p < 0.02). In conclusion, the study shows a role of T regulatory cells in the pathogenesis of asthma in children, but fails to show any influence of serum vitamin D or urine cotinine on disease course.