Iontophoresis and Sonophoresis Stimulate Epidermal Cytokine Expression at Energies That Do Not Provoke a Barrier Abnormality: Lamellar Body Secretion and Cytokine Expression Are Linked to Altered Epidermal Calcium Levels

We performed this study to identify whether the expression of epidermal cytokines is altered by changes in epidermal calcium content, independent of skin barrier disruption. Iontophoresis and sonophoresis with the energies that do not disrupt the skin barrier, but induce changes in the epidermal calcium gradient, were applied to the skin of hairless mice. Immediately after iontophoresis and sonophoresis, immersion in a solution containing calcium was carried out, and iontophoresis in either high- or low-calcium solutions was performed. The biopsy specimens were taken for real-time quantitative RT-PCR to detect changes in mRNA level of interleukin-1α (IL-1α), tumor necrosis factor-α (TNF-α), and transforming growth factor-β in the epidermis and for immunohistochemical stain with primary antibodies to IL-1α and TNF-α. The expression of each cytokine mRNA increased in the epidermis treated with iontophoresis and sonophoresis compared to a nontreated control as well as in tape-stripped skin used as a positive control and was lower after immersion in a high-calcium solution than in low-calcium solution. IL-1α and TNF-α immunohistochemical protein staining increased with iontophoresis at low calcium. These studies suggest that changes in epidermal calcium can directly signal expression of epidermal cytokines in vivo, independent of changes in barrier function.