Supplementary Material for: Is There a Relation between Vitamin D and Interleukin-17 in Vitiligo? A Cross-Sectional Study

<p><b><i>Background:</i></b> High interleukin (IL)-17 contributes to vitiligo pathogenesis. Vitamin D has been assessed in vitiligo, with no reports targeting its relation to IL-17. <b><i>Objective:</i></b> To evaluate a possible regulatory effect of vitamin D on IL-17 and their relation to disease activity in vitiligo. <b><i>Methods:</i></b> This study included 30 vitiligo patients and 40 controls evaluated for IL-17 and vitamin D serum levels by ELISA technique. <b><i>Results:</i></b> IL-17 was significantly higher (<i>p</i> = 0.001) whereas vitamin D was found to be lower among the patients (<i>p</i> < 0.001). Multivariable regression was performed to evaluate the relationship between IL-17 and vitamin D levels with the demographic data on the patients, revealing a nonsignificant relationship (<i>p</i> > 0.05). A significant positive correlation was noted between vitamin D levels and disease duration. <b><i>Conclusion:</i></b> Vitamin D represents a potential player in the pathogenesis of vitiligo. Its possible regulatory relation to IL-17, together with its weight as a screening tool in vitiligo, needs further evaluation.</p>