title: Physicochemical analysis of liposome membranes consisting of model lipids in the stratum corneum.
abstract: Lamellar lipid layers in the stratum corneum (SC), the outermost layer of the skin, act as a primary permeability barrier to protect the body. The roles of SC lipid composition and membrane structure in skin barrier function have been extensively investigated using ex-vivo SC samples and reconstructed SC lipids in the form of multi-lamellar lipids or liposomes. The primary lipids, especially ceramide, have been found to be highly important. Atopic dermatitis (AD) is a well-known chronic inflammatory skin disease with immunologic and epidermal abnormalities of the permeability barrier; therefore, a comparison of SC lipids in AD skin with those in normal skin is a promising method to explore the mechanisms of skin barrier function. Here, we focused on the effect of sphingoids (ceramide metabolites and a minor component of the SC lipids) and their content/species on skin barrier function. A significant difference in the leakage ratio was observed between model SC lipid liposomes with a different sphingolipid ratio (sphingosine/sphinganine), with a value of 5.43 for normal skin vs. 14.3 for AD skin. This result shows a good concordance with AD mouse experiments. Therefore, an alteration in the composition of minor SC lipids resulting from a ceramide metabolic abnormality can affect the membrane integrity (i.e., skin barrier function). Small angle X-ray scattering (SAXS) measurements revealed no distinct differences in the SAXS pattern between the 3 models, with all models forming a rigid membrane (i.e., a nearly hydrated solid). According to increasing the temperature, the peaks indicated that the lamellar structures decreased in all models and that the lateral packing of lipids decreased, which suggested annealing or melting of the gel to a liquid crystal, although no distinct phase transition was observed through fluorescence anisotropy measurements. Hence, we assume that the altered sphingoid composition triggers local membrane structural changes (i.e., formation of domains or clusters).
authors.affiliation: Department of Pure and Applied Chemistry, Tokyo University of Science, 2641 Yamazaki, Chiba, Japan. j7208702@ed.noda.tus.ac.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Aburai
authors.forename: Saeko
authors.initials: S
authors.lastname: Yoshino
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sakai
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abe
authors.forename: Nicolas
authors.initials: N
authors.lastname: Loiseau
authors.forename: Walter
authors.initials: W
authors.lastname: Holleran
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Uchida
authors.forename: Kazutami
authors.initials: K
authors.lastname: Sakamoto
mesh_terms: D000818:Animals; D003876:Dermatitis, Atopic / Q000378:metabolism*; D004817:Epidermis / Q000737:chemistry* / Q000378:metabolism; D005454:Fluorescence Polarization; D008081:Liposomes / Q000737:chemistry*; D051379:Mice; D010539:Permeability; D013107:Sphingolipids / Q000032:analysis*; D013696:Temperature
chemical_list: D008081:Liposomes; D013107:Sphingolipids