Chromatin Accessibility Dynamics Suggest Immune-Modulatory Effects of Vitamin D3 In Vivo

Vitamin D3 is a key micronutrient known to support innate immunity and modulate adaptive responses, with in vitro studies suggesting the involvement of epigenetic mechanisms. However, in vivo evidence remains limited. In this study, we investigated genome-wide epigenomic responses to vitamin D3 supplementation in a cohort of 38 individuals from a Polish population. Peripheral blood mononuclear cells (PBMCs) were collected at baseline (day 0) and 24 hours after supplementation (day 1). ATAC-seq analyses revealed widespread vitamin D3-induced changes in chromatin accessibility. Overall design: ATAC-seq libraries of PBMCs obtained from a Polish cohort of 38 individuals before supplementation (day 0) as well as 24 hours after (day 1).