Long-periodicity phase (LPP) lamellar structures in intercellular lipid matrixes of the stratum corneum (SC) are considered important for maintenance of skin permeability barriers. Acylceramides are essential components of LPP structures, and their absence influences skin barriers under physiological and pathological conditions, such as atopic dermatitis and dry skin. Although topical applications of acylceramide have been shown to facilitate maintenance of the skin barrier, it is unknown whether topically applied acylceramides are incorporated into intercellular lipids to form LPP structures. Thus, we assessed the effects of topical treatments with monomodal acylceramides on the formation of LPP structures in a surfactant-insulted reconstructed human epidermis model using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) analyses. In SAXS experiments, LPP structures give rise to a diffraction peak which indicates the presence of a structure with a 13 nm real space repeat distance. LPP patterns of intercellular lipid matrixes in the SC were disrupted’ by surfactant treatments and were recovered by topical acylceramide treatments. TEM images also showed specific repeating patterns of LPP structures, indicating that topical acylceramide treatments facilitate recovery of LPP structures in the SC. The present data show that the application of acylceramides might temporarily modify the lipid structure to resemble that of normal skin although the underlying cause of dry or diseased skin is not fully clarified.

角质层（SC）的细胞间脂质基质中的长周期相（LPP）层状结构被认为对于维持皮肤渗透性屏障很重要。酰基神经酰胺是LPP结构的重要组成部分，它们的缺乏会影响生理和病理条件下的皮肤屏障，例如特应性皮炎和皮肤干燥。尽管已显示局部应用酰基神经酰胺可促进皮肤屏障的维持，但尚不清楚是否将局部应用的酰基神经酰胺掺入细胞间脂质中以形成LPP结构。因此，我们使用小角度X射线散射（SAXS）和透射电子显微镜（TEM）分析评估了单峰酰基神经酰胺局部处理对LPP结构形成的影响。在SAXS实验中，LPP结构产生一个衍射峰，该衍射峰表明存在具有13 nm实际空间重复距离的结构。表面活性剂处理破坏了SC中细胞间脂质基质的LPP模式，并通过局部酰基神经酰胺处理恢复。TEM图像还显示了LPP结构的特定重复模式，表明局部酰基神经酰胺治疗促进了SC中LPP结构的恢复。