Search

Skin barrier disruption plays a role in the pathogenesis of atopic dermatitis (AD) in humans. However, little is known about skin barrier (dys-) function in Canine Atopic Dermatitis. The properties of lipids located in the outermost layer of the skin, the stratum corneum (SC) are considered to be important for the barrier. In the present study the lipid composition and lipid organization of the SC of AD dogs and control dogs were examined. The lipid composition of lesional AD skin as compared to control skin, showed a reduced free fatty acid level and a decreased ratio of ceramide[NS] C44/C34, in which C44 and C34 are the total numbers of carbon atoms of the sphingosine (S) and non-hydroxy (N) acyl chains. As a consequence of the observed changes in lipid composition in AD lesional skin the lamellar organization of lipids altered and a shift from orthorhombic to hexagonal lipid packing was monitored. Simultaneously an increased conformational disordering occurred. These changes are expected to compromise the integrity of the skin barrier. The C44/C34 chain length ratio of ceramide[NS] also showed a decreasing nonlinear relationship with the AD severity score (CADESI). Taken together, canine atopic skin showed alterations in SC lipid properties, similar to the changes observed in atopic dermatitis in humans, that correlated with a disruption of the skin barrier. Hence lipids play an important role in the pathogenesis of Canine Atopic Dermatitis., (Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.)

UVB irradiation (290-320 nm) is used to treat skin diseases like psoriasis and atopic dermatitis, and is known to suppress contact hypersensitivity (CHS) reactions in mouse models. Regulatory T cells (Treg cells) have been shown to be responsible for this UVB-induced suppression of CHS. The epidermal growth factor (EGF)-like growth factor amphiregulin (AREG) engages EGFR on Treg cells and, in different disease models, it was shown that mast cell-derived AREG is essential for optimal Treg cell function in vivo. Here we determined whether AREG has a role in UVB-induced, Treg cell-mediated suppression of CHS reactions in the skin. Our data show that AREG is essential for UVB-induced CHS suppression. In contrast to the general assumption, however, mast cells were dispensable for UVB-induced immune suppression, whereas basophil-derived AREG was essential. These data reveal, to our knowledge, a previously unreported function for basophils in the homeostasis of immune responses in the skin. Basophils thus fulfill a dual function: they contribute to the initiation of effective type 2 immune responses and, by enhancing the suppressive capacity of local Treg cell populations, also to local immune regulation in the skin.