Long and very long lamellar phases in model stratum corneum lipid membranes

Petra Pullmannová,Elena Ermakova,Andrej Kováčik,Lukáš Opálka,Jaroslav Maixner,Jarmila Zbytovská,Norbert Kučerka,Kateřina Vávrová

doi:10.1194/jlr.m090977

Abstract

Membrane models of the stratum corneum (SC) lipid barrier, either healthy or affected by recessive X-linked ichthyosis, constructed from ceramide [Cer; nonhydroxyacyl sphingosine N-tetracosanoyl-d-erythro-sphingosine (CerNS24) alone or with omega-O-acylceramide N-(32-linoleyloxy)dotriacontanoyl-d-erythro-sphingosine (CerEOS)], FFAs(C16-24), cholesterol (Chol), and sodium cholesteryl sulfate (CholS) were investigated. X-ray diffraction (XRD) revealed a previously unreported polymorphism of the membranes. In the absence of CerEOS, the membranes formed a short lamellar phase (SLP; the repeat distance d = 5.3 nm), a medium lamellar phase (MLP; d = 10.6 nm), or very long lamellar phases (VLLP; d = 15.9 and 21.2 nm). An increased CholS-to-Chol ratio modulated the membrane polymorphism, although the CholS phase separated at ≥ 7 weight% (of total lipids). The presence of CerEOS led to the stable long lamellar phase (LLP) with d = 12.2 nm and prevented VLLP formation. Our XRD results agree well with recently published cryo-electron microscopy data for vitreous skin sections, while also revealing new structures. Thus, lamellar phases with long repeat distances (MLP and VLLP) may be formed in the absence of omega-O-acylceramide, whereas these ultralong Cer species likely stabilize the final SC lipid architecture of LLP by riveting the adjacent lipid layers.

Highlights

Membrane models of the stratum corneum (SC) lipid barrier, either healthy or affected by recessive X-linked ichthyosis, constructed from ceramide [Cer; nonhydroxyacyl sphingosine N-tetracosanoyl-d-erythro-sphingosine (CerNS24) alone or with omega-O-acylceramide N-(32-linoleyloxy)dotriacontanoyl-d-erythro-sphingosine (CerEOS)], FFAs(C16–24), cholesterol (Chol), and sodium cholesteryl sulfate (CholS) were investigated
The X-ray diffraction (XRD) and electron-microscopy results have provided essential information about the SC lipid barrier structure, i.e., that the dominant repeating unit is 13 nm long [14, 15, 42] and contains repeating patterns of broad/narrow/ broad electron-lucent bands bordered by electron-dense segments [25]
We report, for the first time, that CerNS24-based model membranes in the absence of -O-acylCer form the short lamellar phase (SLP) and medium lamellar phase (MLP) and very long lamellar phases (VLLP) and that their lamellae can be arranged with even longer repeat distances than in membranes with -O-acylCer

Summary

Introduction

Membrane models of the stratum corneum (SC) lipid barrier, either healthy or affected by recessive X-linked ichthyosis, constructed from ceramide [Cer; nonhydroxyacyl sphingosine N-tetracosanoyl-d-erythro-sphingosine (CerNS24) alone or with omega-O-acylceramide N-(32-linoleyloxy)dotriacontanoyl-d-erythro-sphingosine (CerEOS)], FFAs(C16–24), cholesterol (Chol), and sodium cholesteryl sulfate (CholS) were investigated. Lamellar phases with long repeat distances (MLP and VLLP) may be formed in the absence of omega-O-acylceramide, whereas these ultralong Cer species likely stabilize the final SC lipid architecture of LLP by riveting the adjacent lipid layers.—Pullmannová, P., E. The SC extracellular lipid matrix consists mainly of ceramides (Cers), FFAs, and cholesterol (Chol) at an 1:1:1 molar ratio (supplemental Fig. S1). The lipid matrix of isolated SC has a lamellar characteristic and a long repeat distance (d) of 13 nm, as was revealed by electron microscopy [11,12,13] and/or by X-ray diffraction (XRD) [12, 14, 15].

Methods

Results

Conclusion