Pyrrolidone carboxylic acid levels or caspase-14 expression in the corneocytes of lesional skin correlates with clinical severity, skin barrier function and lesional inflammation in atopic dermatitis

•Quantities of PCA, caspase-14 and some cytokines were evaluated in the corneocytes of lesional and non-lesional skin of atopic dermatitis.•The amounts of PCA and caspase-14 decreased in atopic dermatitis patients, especially significant in lesional skin.•In the lesional skin, quantity of PCA correlated with caspase-14. PCA level or caspase-14 expression correlated with clinical severity (EASI score) and skin barrier function (TEWL, SC hydration and skin surface pH). Quantities of TNF-α and IL-13 inversely correlated with PCA.