ResearchDermatologyGeneticsMetabolism Open Access | 10.1172/JCI198835 J Clin Invest. https://doi.org/10.1172/JCI198835. Copyright © 2026, Zhang et al. This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. View PDF Abstract Ceramides are essential skin lipids for maintaining the mammalian skin permeability barrier, which protects against external stimuli.