Dataset Information

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.

SUBMITTER: Doucet J

PROVIDER: S-EPMC4617139 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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Micron-scale assessment of molecular lipid organization in human stratum corneum using microprobe X-ray diffraction.

Doucet Jean J Potter Anne A Baltenneck Carine C Domanov Yegor A YA

Journal of lipid research 20140901 11

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 sca ...[more]

PMID: 25180243

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Project description:Molecular dynamics simulations of mixtures of the ceramide nonhydroxy-sphingosine (NS), cholesterol, and a free fatty acid are performed to gain molecular-level understanding of the structure of the lipids found in the stratum corneum layer of skin. A new coarse-grained force field for cholesterol was developed using the multistate iterative Boltzmann inversion (MS-IBI) method. The coarse-grained cholesterol force field is compatible with previously developed coarse-grained force fields for ceramide NS, free fatty acids, and water and validated against atomistic simulations of these lipids using the CHARMM force field. Self-assembly simulations of multilayer structures using these coarse-grained force fields are performed, revealing that a large fraction of the ceramides adopt extended conformations, which cannot occur in the single bilayer in water structures typically studied using molecular simulation. Cholesterol fluidizes the membrane by promoting packing defects, and an increase in cholesterol content is found to reduce the bilayer thickness due to an increase in interdigitation of the C24 lipid tails, consistent with experimental observations. Using a reverse-mapping procedure, a self-assembled coarse-grained multilayer system is used to construct an equivalent structure with atomistic resolution. Simulations of this atomistic structure are found to closely agree with experimentally derived neutron scattering length density profiles. Significant interlayer hydrogen bonding is observed in the inner layers of the atomistic multilayer structure that are not found in the outer layers in contact with water or in equivalent bilayer structures. This work highlights the importance of simulating multilayer structures, as compared to the more commonly studied bilayer systems, to enable more appropriate comparisons with multilayer experimental membranes. These results also provide validation of the efficacy of the MS-IBI derived coarse-grained force fields and the framework for multiscale simulation.

Dataset Information

Micron-scale assessment of molecular lipid organization in human stratum corneum using microprobe X-ray diffraction.

Publications

Micron-scale assessment of molecular lipid organization in human stratum corneum using microprobe X-ray diffraction.

Similar Datasets

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