Electron Microscopic Observations of Stratum Corneum Intercellular Lipids in Normal and Atopic Dogs

Abstract

Abstract. The barrier function of mammalian skin is maintained by intercellular stratum corneum lipids. In human patients with atopic dermatitis, an abnormal lipid barrier results in dry skin and increased transepidermal water loss. At this time, it is not known if a defective lipid barrier is present in atopic dogs. Normal and atopic canine skin were postfixed in ruthenium tetroxide and studied using transmission electron microscopy to determine structural differences within stratum corneum lipids. Intercellular lipid lamellae were graded on a semiquantitative scale. The deposition of stratum corneum lipid lamellae in atopic canine skin appeared markedly heterogeneous compared with that seen in normal canine skin. When present, the lamellae often exhibited an abnormal structure. The continuity and thickness of the intercellular lipid lamellae were significantly less in nonlesional atopic than in normal canine skin. These preliminary observations suggest that the epidermal lipid barrier is defective in atopic canine skin. Additional studies are needed to further characterize the biochemical defect and to possibly correct it with nutritional and/or pharmacologic intervention.Key words: Barrier defect; canine atopic dermatitis; dogs; lipid lamellae; ruthenium tetroxide.The barrier function of mammalian skin is maintained by epidermal lipids, especially those interspersed between the layers of the stratum corneum. In mammalian stratum corneum, epidermal lipids consist of ceramides, cholesterol,

Analysis of epidermal lipids in normal and atopic dogs, before and after administration of an oral omega-6/omega-3 fatty acid feed supplement. A pilot study

“…However, SC lipid abnormalities have been reported. Indeed, both continuity and overall thickness of the SC intercellular lipid lamellae, which are prerequisite for the proper barrier function, were significantly decreased in the non-lesional skin of dogs with AD (Inman et al 2001;Piekutowska et al 2008). These morphological findings have been supported by biochemical analyses showing abnormal composition of the SC lipids, and more specifically ceramides, in AD dogs (Reiter et al 2009;Shimada et al 2009;Popa et al 2011, Popa et al, (in preparation)) and by functional assays testifying to an increased permeability of the skin barrier in this disease (Shimada et al 2009).…”

Recent developments in canine atopic dermatitis: A review

“…However, preliminary and empirical ultrastructural (i.e. electron microscopic) examination of the stratum corneum of atopic dogs revealed differences between normal skin and skin of AD patients (Inman et al, 2001). In the normal canine skin, the keratinocytes of the stratum corneum are arranged in regular, overlapping layers, and intervening lipid material fills the gaps between cells in a classical 'brick and mortar' arrangement.…”

Dermatite atopique canine : actualités et aspects de pathologie comparée

“…Chez le chien, il a été démontré que les lipides intercellulaires du stratum corneum sont altérés (INMAN et al 2001).…”

“…Un shampooing spécifiquement conçu pour le traitement de la DAC, à base d'acides linoléique et gamma linolénique (acides gras essentiels), de mono-oligosaccharides (immunomodulateurs), de vitamine E (anti-inflammatoire et immunostimulant) et de piroctone olamine (antiseptique) en micro-émulsion moussante a été récemment commercialisée (son efficacité devrait être évaluée dans des études contrôlées). Les acides gras essentiels pourraient renforcer le rôle de barrière lipidique de l'épiderme, qui est altérée chez le chien atopique (INMAN et al, 2001). De plus, la pénétration des aéroallergènes par voie transcutanée étant probable , un effet mécanique d'éviction allergénique est possible et serait dont bénéfique.…”