Assembly of Human Stratum Corneum Lipids In Vitro: Fluidity Matters

Fluid lipid membranes are vital for living systems. In contrast, the skin barrier lipids are primarily rigid and tightly packed. While this unusual lipid rigidity makes sense for restricting water loss and preventing the penetration of harmful substances, it is less conceivable how such lipids attain their complex architecture.
Our in vitro experiments on isolated human stratum corneum lipids suggest that the essential skin barrier structure, the long periodicity phase, LPP, is a robust assembly highly favored by the lipids without the need for fluidization or a template. However, to reduce nanoscopic packing defects and improve the barrier properties, the lipids need to undergo temporary fluidization. This finding may be relevant to the function of the corneocyte lipid envelope in vivo, as these covalent lipids may help orient the free lipids in a controlled manner to seal their lateral packing defects.

流体脂质膜对于生物体系至关重要。相较之下，皮肤屏障脂质则主要表现为刚性且紧密排列。尽管这种不寻常的脂质刚性对于限制水分流失和防止有害物质渗透具有合理性，但其如何形成复杂的结构则显得较为难以想象。我们的体外实验针对分离的人体角质层脂质进行了研究，指出构成皮肤屏障的关键结构——长周期相，即LPP，是一种脂质高度青睐的稳固组装，无需经历液化和模板化过程。然而，为了减少纳米级排列缺陷并提升屏障性能，脂质需要经历暂时的液态化过程。这一发现可能与活体中角质细胞脂质囊的功能相关，因为这些共价脂质可能有助于以可控的方式定向排列游离脂质，以密封其侧向排列缺陷。