Comparative analysis of epidermal gene expression in mice exposed to deionized water and groundwater

In our daily life, our skin is frequently exposed to water, which can affect human health. Previous studies have demonstrated that water bathing improves skin conditions in individuals with dermatoses. However, whether groundwater bathing influences epidermal gene expression in normal skin is largely unknown. Therefore, we compared epidermal gene expression in mice exposed in groundwater and deionized water. Flank of mouse skin was exposed to either groundwater or deionized water for 30 min twice daily for three consecutive days. Expression levels of epidermal mRNA were compared between the skin exposed to deionized and groundwaters. In comparison to deionized water, spring water A (Yichun) upregulated 257 genes and downregulated 380 genes, while spring water B (AVENE) upregulated 242 genes and downregulated 668 genes. Moreover, spring water A upregulated 469 genes and downregulated 277 genes compared to spring water B. Spring water A downregulated genes were mainly enriched in the pathways associated with keratinization, keratinocyte differentiation and development, while upregulated genes were enriched in the pathways associated with muscle contraction, sarcomere organization and skeletal muscle fiber development. Whereas genes upregulated by spring water B were associated with pathways related to ion transport and activation of endothelial cells, while downregulated genes were related to keratinization, response to bacteria and keratinocyte differentiation. Collectively, groundwater can affect epidermal gene expression. The influences of water bathing on epidermal gene expression vary with water, likely due to the differences in active constitutes in the water. However, the clinical significance of altered epidermal gene expression remains to be explored.