{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T10:56:53Z","timestamp":1788346613502,"version":"build-2803163510"},"reference-count":21,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2025,12,16]],"date-time":"2025-12-16T00:00:00Z","timestamp":1765843200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002951","name":"Dokkyo Medical University","doi-asserted-by":"crossref","award":["2364"],"award-info":[{"award-number":["2364"]}],"id":[{"id":"10.13039\/501100002951","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100002951","name":"Dokkyo Medical University","doi-asserted-by":"crossref","award":["2465"],"award-info":[{"award-number":["2465"]}],"id":[{"id":"10.13039\/501100002951","id-type":"DOI","asserted-by":"crossref"}]},{"name":"JSPS KAKENHI","award":["22K08410"],"award-info":[{"award-number":["22K08410"]}]},{"name":"JSPS KAKENHI","award":["24K01519"],"award-info":[{"award-number":["24K01519"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Lipids are essential for the skin, playing a crucial role in forming plasma membranes and maintaining the skin\u2019s permeability barrier and hydration. Intercellular lipids fill the spaces between corneocytes and contribute to the barrier function. Lipid abnormalities in the skin have been observed in many skin diseases, including atopic dermatitis and psoriasis. However, the specific localization and roles of skin lipids at particular sites remain incompletely elucidated due to the limited methods available for comprehensive lipid analysis. This study aims to precisely determine the localization of skin lipids, especially intercellular lipids, and investigate their roles and metabolism using mass spectrometry imaging (MSI). We conducted high-resolution (spatial resolution: 5 \u00b5m) matrix-assisted laser desorption\/ionization (MALDI)-MSI on the lower back and buttocks and created overlay images of skin lipids to clarify their precise localizations. Ceramide was localized in the outermost layer among intercellular lipids. Cholesterol and free fatty acids were present in the stratum corneum but were at trace levels in the outermost layer. Cholesterol sulfate was abundant in the granular layer and gradually decreased in the stratum corneum, promoting desquamation. Phospholipids were confined to the viable epidermis (stratum corneum-\/epidermis+), which forms the plasma membrane. A significant increase in mass intensity in the stratum corneum was observed for ceramide, sphingoid base, cholesterol, and free fatty acids, along with a decrease in phospholipids compared with those in the viable epidermis, based on region of interest analysis (Mann\u2013Whitney test, p &lt; 0.0005). We clarified the precise localization of skin lipids, particularly intercellular lipids. Our findings supported the reported functions of skin lipids at specific sites. Skin lipids are metabolized to form intercellular lipids in the stratum corneum, which are essential for the skin barrier. Our current lipid localization data serve as a baseline, or healthy control dataset, for future MSI-based lipid biomarker research in disease groups.<\/jats:p>","DOI":"10.3390\/ijms262412114","type":"journal-article","created":{"date-parts":[[2025,12,16]],"date-time":"2025-12-16T15:41:12Z","timestamp":1765899672000},"page":"12114","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Mass Spectrometry Imaging Elucidates the Precise Localization and Site-Specific Functions of Skin Lipids"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5308-8462","authenticated-orcid":false,"given":"Shown","family":"Tokoro","sequence":"first","affiliation":[{"name":"Department of Dermatology, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Shimotsuga, Tochigi 3210293, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4627-0693","authenticated-orcid":false,"given":"Tadayuki","family":"Ogawa","sequence":"additional","affiliation":[{"name":"Laboratory for Molecular Pathobiology, Research Center for Advanced Medical Sciences, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Shimotsuga, Tochigi 3210293, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6558-4818","authenticated-orcid":false,"given":"Shujiro","family":"Hayashi","sequence":"additional","affiliation":[{"name":"Department of Dermatology, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Shimotsuga, Tochigi 3210293, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ken","family":"Igawa","sequence":"additional","affiliation":[{"name":"Department of Dermatology, Dokkyo Medical University, 880 Kitakobayashi, Mibu, Shimotsuga, Tochigi 3210293, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"280","DOI":"10.1016\/j.bbalip.2013.11.007","article-title":"Role of Lipids in the Formation and Maintenance of the Cutaneous Permeability Barrier","volume":"1841","author":"Feingold","year":"2013","journal-title":"Biochim. Biophys. Acta\u2014Mol. Cell Biol. Lipids"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"105055","DOI":"10.1016\/j.chemphyslip.2021.105055","article-title":"Skin Lipids in Health and Disease: A Review","volume":"236","author":"Knox","year":"2021","journal-title":"Chem. Phys. Lipids"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1463","DOI":"10.1172\/JCI124608","article-title":"Epithelial Barrier Repair and Prevention of Allergy","volume":"129","author":"Goleva","year":"2019","journal-title":"J. Clin. Investig."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1016\/j.bbalip.2013.10.001","article-title":"Lipid Abnormalities and Lipid-Based Repair Strategies in Atopic Dermatitis","volume":"1841","author":"Elias","year":"2015","journal-title":"Biochim. Biophys. Acta\u2014Mol. Cell Biol. Lipids"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Mahanty, S., and Setty, S.R.G. (2021). Epidermal Lamellar Body Biogenesis: Insight into the Roles of Golgi and Lysosomes. Front. Cell Dev. Biol., 9.","DOI":"10.3389\/fcell.2021.701950"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/j.alit.2017.10.002","article-title":"Barrier Dysfunction in the Skin Allergy","volume":"67","author":"Egawa","year":"2017","journal-title":"Allergol. Int."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"100235","DOI":"10.1016\/j.jlr.2022.100235","article-title":"Whole Picture of Human Stratum Corneum Ceramides, Including the Chain-Length Diversity of Long-Chain Bases","volume":"63","author":"Suzuki","year":"2022","journal-title":"J. Lipid Res."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2215","DOI":"10.1038\/jid.2012.43","article-title":"The Human Skin Barrier is Organized as Stacked Bilayers of Fully Extended Ceramides with Cholesterol Molecules Associated with the Ceramide Sphingoid Moiety","volume":"132","author":"Iwai","year":"2012","journal-title":"J. Investig. Dermatol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"3818","DOI":"10.1021\/bi301519p","article-title":"Matrix-Assisted Laser Desorption Ionization Imaging Mass Spectrometry: In Situ Molecular Mapping","volume":"52","author":"Angel","year":"2014","journal-title":"Biochemistry"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e456","DOI":"10.1111\/jdv.19621","article-title":"High-resolution Mass Spectrometry Imaging Reveals Skin Lipid Changes and the Cholesterol Sulphate Cycle during Keratinization","volume":"38","author":"Tokoro","year":"2024","journal-title":"Acad. Dermatol. Venereol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"866","DOI":"10.1016\/S0190-9622(84)80144-9","article-title":"The epidermal cholesterol sulfate cycle","volume":"10","author":"Epstein","year":"1984","journal-title":"J. Am. Acad. Dermatol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"2105","DOI":"10.1007\/s13361-015-1226-7","article-title":"Differentiating Fragmentation Pathways of Cholesterol by Two-Dimensional Fourier Transform Ion Cyclotron Resonance Mass Spectrometry","volume":"26","author":"Barrow","year":"2015","journal-title":"J. Am. Soc. Mass Spectrom."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"999","DOI":"10.1111\/exd.13329","article-title":"The how, Why and Clinical Importance of Stratum Corneum Acidification","volume":"26","author":"Elias","year":"2017","journal-title":"Exp. Dermatol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"261","DOI":"10.2340\/00015555-1531","article-title":"Skin pH: From Basic SciencE to Basic Skin Care","volume":"93","author":"Ali","year":"2013","journal-title":"Acta Derm. Venerol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"261","DOI":"10.2165\/00128071-200203040-00004","article-title":"The Acidic Milieu of the Horny Layer","volume":"3","author":"Rippke","year":"2002","journal-title":"Am. J. Clin. Dermatol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"4062","DOI":"10.1038\/s41467-024-48226-z","article-title":"Three Stepwise pH Progressions in Stratum Corneum for Homeostatic Maintenance of the Skin","volume":"15","author":"Fukuda","year":"2024","journal-title":"Nat. Commun."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1016\/S0022-2275(20)38006-8","article-title":"Human epidermal lipids: Characterization and modulations during differentiation","volume":"24","author":"Lamp","year":"1983","journal-title":"J. Lipid Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"353","DOI":"10.1016\/j.bbalip.2013.11.009","article-title":"Role of Cholesterol Sulfate in Epidermal Structure and Function: Lessons from X-Linked Ichthyosis","volume":"1841","author":"Elias","year":"2015","journal-title":"Biochim. Biophys. Acta\u2014Mol. Cell Biol. Lipids"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1516","DOI":"10.1021\/acs.analchem.6b03353","article-title":"Structural Characterization of Phosphatidylcholines using 193 Nm Ultraviolet Photodissociation Mass Spectrometry","volume":"89","author":"Klein","year":"2017","journal-title":"Anal. Chem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"e2020722118","DOI":"10.1073\/pnas.2020722118","article-title":"A Unique Mode of Keratinocyte Death Requires Intracellular Acidification","volume":"118","author":"Matsui","year":"2021","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Alibardi, L., Conway, S.J., and Matsui, T. (2023). Epidermal Barrier Development Via Corneoptosis: A Unique Form of Cell Death in Stratum Granulosum Cells. J. Dev. 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