Supplementary Material for: The Effect of Glycation on Epidermal Lipid Content, Its Metabolism and Change in Barrier Function

<i>Background/Aims:</i> Advanced glycation end products, which are linked to both aging and hyperglycemia, cause marked functional and structural alterations in human skin. Though it is well known that the metabolism of glucose is closely associated with that of fatty acid (FA), sharing the same energy-yielding reaction pathways as glucose, its effect on the epidermis has been unclear so far. <i>Methods:</i> Content of ceramides, cholesterol and FA in a reconstructed epidermal model glycated by glyoxal was analyzed by high-performance thin-layer chromatography. FA species extracted from HaCaT keratinocytes was determined by gas chromatography/mass spectrometry. Regulation of FA synthesis was analyzed by real-time PCR. For physiological analysis, excised mouse skin was glycated using a vertical diffusion cell and used for the evaluation of barrier function by transepidermal water loss measurement and observation of penetration of sodium fluorescein. <i>Results:</i> Saturated FA content was significantly increased in glycated epidermis, and glycation upregulated mRNA expression of FA elongases 2 and 3 and FA synthase in HaCaT cells. Further, both inside-out and outside-in barriers were disrupted in glycated excised skin. <i>Conclusion:</i>Biological and physical change in the epidermis, especially upregulation of FA synthesis by glycation, contributed to barrier disruption, and inhibiting glycation may offer an effective treatment option for aged or glycated skin