title: Micron-scale assessment of molecular lipid organization in human stratum corneum using microprobe X-ray diffraction.
abstract: Lipid and protein components of the stratum corneum (SC) are organized in complex supramolecular arrangements. Exploring spatial relations between various possible substructures is important for understanding the barrier function of this uppermost layer of epidermis. Here, we report the first study where micro-focus X-ray scattering was used for assessing fine structural variations of the human skin barrier with micrometer resolution. We found that the scattering profiles were unchanged when scanning in the direction parallel to the SC surface. Furthermore, small-angle scattering profiles did not change as a function of depth in the SC, confirming that the lipid lamellar spacings remained the same throughout the SC. However, the wide-angle scattering data showed that the orthorhombic phase was more abundant in the middle layers of the SC, whereas the hexagonal phase dominated in the surface layers both at the external and the lowest part of the SC; i.e., the lipids were most tightly packed in the middle region of the SC. Taken together, our results demonstrate that microprobe X-ray diffraction provides abundant information about spatial variations of the SC lipid structure and thus may be a promising tool for assessing the effects of topical formulations on the barrier function of skin.
authors.affiliation: Laboratoire de Physique des Solides, Université Paris-Sud, Orsay, France Phi-Axis, Antony, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Doucet
authors.affiliation: Skin Biophysics Laboratory, L'Oréal Research & Innovation, Aulnay-sous-Bois, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Potter
authors.affiliation: Skin Biophysics Laboratory, L'Oréal Research & Innovation, Aulnay-sous-Bois, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Baltenneck
authors.affiliation: Skin Biophysics Laboratory, L'Oréal Research & Innovation, Aulnay-sous-Bois, France.
authors.forename: Yegor A
authors.initials: YA
authors.lastname: Domanov
mesh_terms: D004817:Epidermis / Q000737:chemistry*; D006801:Humans; D008055:Lipids / Q000737:chemistry* / Q000302:isolation & purification; D053838:Scattering, Small Angle; D012997:Solvents / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D008055:Lipids; D012997:Solvents
keywords: barrier function; ceramide; domains; heterogeneity; imaging; intercellular lipid lamellae; microdiffraction