Sebum component lipids penetrate through the epidermis and accumulate in the dermis

Marianna Lovászi1, Attila Gácsi2, Lajos Kemény3, Erzsébet Csányi2, Dániel Törőcsik1
1Department of Dermatology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
2 Institute of Pharmaceutical Technology and Regulatory Affairs, Faculty of Pharmacy, University of Szeged, Szeged, Hungary
3Department of Dermatology and Allergology, University of Szeged, Szeged, Hungary



The primary function of the human sebaceous glands is to produce and secrete sebum to coat the surface of skin, aiding keratinocytes in the formation of the lipid barrier. As recent findings put forward that sebum component lipids might also have a significant contribution to the overall dermal lipid content where they could exert a (patho)physiological role, therefore our aim was to assess whether sebum lipids could penetrate into the dermis.
Applying major sebum component lipids such squalene, oleic-, palmitic- linoleic and stearic acid individually onto skin grafts from sebaceous gland poor regions we used Raman spectroscopy to determine the extent of penetration and accumulation for each of the lipids. 
Our results clearly showed that all of the tested lipids could penetrate through the epidermis without disrupting its structure. While palmitic acid could be detected in high concentrations in the full depth of the dermis, squalene and linoleic acid accumulated in the upper region. Interestingly stearic acid displayed a prominent enrichment in the intermediate dermal region, while oleic acid was only present in moderate amounts however it showed a scattered distribution throughout the skin.
Our finding, besides extending our knowledge in considering sebum lipids more than just topical lubricants, also opens several new pathways for researchers on how these lipids could be used in therapeutics both as carriers as well as agents with direct effects.