Supplementary Material for: Impaired Skin Barrier Function and Downregulated Expression of Caspase-14 in Moderate to Severe Chronic Hand Eczema

Aim: To investigate whether the skin barrier function is impaired with regard to the pH value, water content, transepidermal water loss (TEWL), and the integrity of the stratum corneum, and whether the expression of caspase-14 is altered in moderate to severe chronic hand eczema (CHE). Methods: Thirty patients with moderate to severe CHE treated at our institute and 30 healthy volunteers were included in this study. The pH value, water content, TEWL, and the integrity of the stratum corneum were measured in all subjects. Results: Significantly increased pH value, decreased water content, elevated TEWL, and impaired integrity of the stratum corneum were observed in the lesional skin of CHE patients compared with the nonlesional skin of CHE patients and the normal skin of healthy volunteers. The expression of caspase-14 decreased in the lesional and nonlesional skin of CHE patients compared with the normal skin of healthy volunteers, especially prominent in the nonlesional skin. The mean optical density (OD) value of immunohistochemical staining for caspase-14 was significantly lower in the nonlesional skin than in the lesional skin and normal skin (p < 0.01 for both). Although the mean OD value was lower in the lesional skin than in the normal skin, the difference was not statistically significant (p > 0.05). Conclusion: Skin barrier dysfunction indeed occurs in CHE patients, which may be related to mechanisms associated with a downregulated expression of caspase-14.