Lipids in the Skin and pH.

The pH value is identified as an essential determinant for the lipid synthesis in the stratum corneum (SC). The activity of the enzymes that catalyse the transformation of lipid precursors into ceramides, free fatty acids or cholesterol highly depends on pH value. Additionally, there are substantial indications for pH conditions to have a direct effect on the molecular structure of the membranes and their properties. Knowledge about the sigmoidal pH gradient within the corneal layer also provides understanding of the pathological processes in a dysfunctional barrier. Shifting the pH environment from acidic into alkaline does not only inhibit the regenerating metabolic pathways but also activates enzymes that accelerate desquamation of the SC.