Altered lipid properties of the stratum corneum in Canine Atopic Dermatitis

Abstract

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.

An untargeted investigation into the skin surface lipidome in the West Highland white terrier dog, with and without atopic dermatitis

“…We detected 392 lipids, the majority of which could not be readily identi ed. The lipids found included ceramides, which were different to those that have been previously identi ed as being important in canine SC, and were in relatively low abundance [10,11,13,24]. This suggests that there are many more lipids which may have a functional role in health and/or disease than previously identi ed.…”

“…It is not known how these variables may have impacted the lipid pro les obtained but it is known from human studies that skin lipids vary with age and gender [26,27,28]. Lipid pro les also vary between body sites [13] and, in an untargeted human study, lipids varied depending on sebaceous gland density [29]. In order to limit this variable in our study the body sites sampled were kept as consistent as possible but there was variation in the affected sites sampled, and it is not known if this may have in uenced the results.…”

“…In previous studies of the cutaneous lipids, targeted approaches have focused on speci c lipid classes within the SC, such as ceramides, cholesterol and free fatty acids [9,10,11,12,13]. The skin surface lipids have been largely disregarded, because it has been suggested they do not play a major role in skin barrier function [14].…”

Characterization of Ceramides with Phytosphingosine Backbone by Hydrogen-deuterium Exchange Mass Spectrometry

“…[30] Investigation of the CER organization within the biological environment has important role in the study of the skin barrier function, and studies have reported alteration of the CERs composition in impaired human and canine skin barrier. [31,32] To address CERs complexity researchers are continuously seeking for methods convenient to reveal mechanisms of biomolecular interactions in the cells. To use advantage of sensitivity and specificity of MRM methods in some studies semi-quantification and profiling of the CERs performed with scheduled-MRM approach resulted with detection of more than 1000 CER species.…”

A pilot study on the effect of oclacitinib on epicutaneous sensitization and transepidermal water loss in a colony of atopic beagle dogs

“…Allergic sensitization to environmental allergens is common and exposure to allergens can increase the severity of AD . Impairment of the skin barrier has been described in atopic dogs and increases the risk for epicutaneous sensitization . It is currently unknown how systemic drug treatment for canine AD affects the rate and frequency of new allergen sensitization.…”