Aldo-keto Reductase 1C3 (AKR1C3) is Expressed in Differentiated Human Epidermis, Affects Keratinocyte Differentiation and is Upregulated in Atopic Dermatitis

Aldo-keto reductase 1C3 (AKR1C3) has been shown to mediate the metabolism of sex hormones and prostaglandin D(2) (PGD(2)), a lipid mediator that promotes skin inflammation in atopic dermatitis (AD). Since both play a role in skin function and pathology, we first sought to investigate the expression pattern of AKR1C3 in normal human epidermis. Immunofluorescence revealed a strong expression of AKR1C3 in the differentiated suprabasal layers compared with the basal layer. Western blot and quantitative PCR confirmed that AKR1C3 expression was also upregulated in differentiation-induced primary human keratinocytes (PHK). To investigate the functional role of AKR1C3 during PHK differentiation, its expression and activity (measured as PGD(2) reduction to 9α,11β-PGF(2) by ELISA) were impaired by siRNA or 2′-hydroxyflavanone, respectively. Cytokeratin 10 (K10) and loricrin expression were then examined by western blot revealing altered expression of these differentiation markers. Finally, following an observation that the AD-associated mediator, PGD(2) upregulated AKR1C3 expression in PHK, we used immunofluorescence to examine AKR1C3 expression in AD and psoriasis lesions. AKR1C3 was found to be upregulated in AD but not in psoriasis lesions compared with non-lesional skin. Our work demonstrates a function for AKR1C3 in differentiation-associated gene regulation and also suggests a role in supporting inflammation in AD.