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Nicolaou A, Kendall AC. Bioactive lipids in the skin barrier mediate its functionality in health and disease. Pharmacol Ther 2024; 260:108681. [PMID: 38897295 DOI: 10.1016/j.pharmthera.2024.108681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 05/11/2024] [Accepted: 06/13/2024] [Indexed: 06/21/2024]
Abstract
Our skin protects us from external threats including ultraviolet radiation, pathogens and chemicals, and prevents excessive trans-epidermal water loss. These varied activities are reliant on a vast array of lipids, many of which are unique to skin, and that support physical, microbiological and immunological barriers. The cutaneous physical barrier is dependent on a specific lipid matrix that surrounds terminally-differentiated keratinocytes in the stratum corneum. Sebum- and keratinocyte-derived lipids cover the skin's surface and support and regulate the skin microbiota. Meanwhile, lipids signal between resident and infiltrating cutaneous immune cells, driving inflammation and its resolution in response to pathogens and other threats. Lipids of particular importance include ceramides, which are crucial for stratum corneum lipid matrix formation and therefore physical barrier functionality, fatty acids, which contribute to the acidic pH of the skin surface and regulate the microbiota, as well as the stratum corneum lipid matrix, and bioactive metabolites of these fatty acids, involved in cell signalling, inflammation, and numerous other cutaneous processes. These diverse and complex lipids maintain homeostasis in healthy skin, and are implicated in many cutaneous diseases, as well as unrelated systemic conditions with skin manifestations, and processes such as ageing. Lipids also contribute to the gut-skin axis, signalling between the two barrier sites. Therefore, skin lipids provide a valuable resource for exploration of healthy cutaneous processes, local and systemic disease development and progression, and accessible biomarker discovery for systemic disease, as well as an opportunity to fully understand the relationship between the host and the skin microbiota. Investigation of skin lipids could provide diagnostic and prognostic biomarkers, and help identify new targets for interventions. Development and improvement of existing in vitro and in silico approaches to explore the cutaneous lipidome, as well as advances in skin lipidomics technologies, will facilitate ongoing progress in skin lipid research.
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Affiliation(s)
- Anna Nicolaou
- Laboratory for Lipidomics and Lipid Biology, Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9NT, UK; Lydia Becker Institute of Immunology and Inflammation; Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9NT, UK.
| | - Alexandra C Kendall
- Laboratory for Lipidomics and Lipid Biology, Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9NT, UK
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2
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Yin X, Yan Y, Li J, Cao Z, Shen S, Chang Q, Zhao Y, Wang X, Wang P. Nuclear receptors for epidermal lipid barrier: Advances in mechanisms and applications. Exp Dermatol 2024; 33:e15107. [PMID: 38840418 DOI: 10.1111/exd.15107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 04/20/2024] [Accepted: 05/19/2024] [Indexed: 06/07/2024]
Abstract
The skin plays an essential role in preventing the entry of external environmental threats and the loss of internal substances, depending on the epidermal permeability barrier. Nuclear receptors (NRs), present in various tissues and organs including full-thickness skin, have been demonstrated to exert significant effects on the epidermal lipid barrier. Formation of the lipid lamellar membrane and the normal proliferation and differentiation of keratinocytes (KCs) are crucial for the development of the epidermal permeability barrier and is regulated by specific NRs such as PPAR, LXR, VDR, RAR/RXR, AHR, PXR and FXR. These receptors play a key role in regulating KC differentiation and the entire process of epidermal lipid synthesis, processing and secretion. Lipids derived from sebaceous glands are influenced by NRs as well and participate in regulation of the epidermal lipid barrier. Furthermore, intricate interplay exists between these receptors. Disturbance of barrier function leads to a range of diseases, including psoriasis, atopic dermatitis and acne. Targeting these NRs with agonists or antagonists modulate pathways involved in lipid synthesis and cell differentiation, suggesting potential therapeutic approaches for dermatosis associated with barrier damage. This review focuses on the regulatory role of NRs in the maintenance and processing of the epidermal lipid barrier through their effects on skin lipid synthesis and KC differentiation, providing novel insights for drug targets to facilitate precision medicine strategies.
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Affiliation(s)
- Xidie Yin
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Yu Yan
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Jiandan Li
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Zhi Cao
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Shuzhan Shen
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Qihang Chang
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Yiting Zhao
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Xiuli Wang
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Peiru Wang
- Institute of Photomedicine, Shanghai Skin Disease Hospital, School of Medicine, Tongji University, Shanghai, China
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3
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Schmuth M, Eckmann S, Moosbrugger-Martinz V, Ortner-Tobider D, Blunder S, Trafoier T, Gruber R, Elias PM. Skin Barrier in Atopic Dermatitis. J Invest Dermatol 2024; 144:989-1000.e1. [PMID: 38643989 DOI: 10.1016/j.jid.2024.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/27/2024] [Accepted: 03/07/2024] [Indexed: 04/23/2024]
Abstract
A compromised permeability barrier is a hallmark of atopic dermatitis (AD). Localized to the outermost skin layer, the stratum corneum (SC) is critically dependent on terminal differentiation of epidermal keratinocytes, which transform into protein-rich corneocytes surrounded by extracellular lamellae of unique epidermal lipids, conferring permeability barrier function. These structures are disrupted in AD. A leaky barrier is prone to environmental insult, which in AD elicits type 2-dominant inflammation, in turn resulting in a vicious cycle further impairing the SC structure. Therapies directed at enforcing SC structure and anti-inflammatory strategies administered by topical and systemic route as well as UV therapy have differential effects on the permeability barrier. The expanding armamentarium of therapeutic modalities for AD treatment warrants optimization of their effects on permeability barrier function.
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Affiliation(s)
- Matthias Schmuth
- Dermatology, Venerology and Allergy, Medical University Innsbruck, Innsbruck, Austria; Institute for Pediatric Dermatology and Rare Diseases, Karl Landsteiner Society, Innsbruck, Austria.
| | - Sonja Eckmann
- Dermatology, Venerology and Allergy, Medical University Innsbruck, Innsbruck, Austria
| | | | | | - Stefan Blunder
- Dermatology, Venerology and Allergy, Medical University Innsbruck, Innsbruck, Austria
| | - Thomas Trafoier
- Dermatology, Venerology and Allergy, Medical University Innsbruck, Innsbruck, Austria
| | - Robert Gruber
- Dermatology, Venerology and Allergy, Medical University Innsbruck, Innsbruck, Austria; Institute for Pediatric Dermatology and Rare Diseases, Karl Landsteiner Society, Innsbruck, Austria
| | - Peter M Elias
- Dermatology, Veteran Affairs Health Care System, San Francisco, California, USA; University of California San Francisco, San Francisco, California, USA
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4
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Fluhr JW, Moore DJ, Lane ME, Lachmann N, Rawlings AV. Epidermal barrier function in dry, flaky and sensitive skin: A narrative review. J Eur Acad Dermatol Venereol 2024; 38:812-820. [PMID: 38140732 DOI: 10.1111/jdv.19745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 11/17/2023] [Indexed: 12/24/2023]
Abstract
The stratum corneum (SC)-the outermost layer of the epidermis-is the principal permeability and protective barrier of the skin. Different components of the SC, including corneocytes, natural moisturizing factor, a variety of enzymes and their inhibitors, antimicrobial peptides and lipids, work interactively to maintain barrier function. The main barrier properties of the SC are the limitation of water loss and the prevention of infection and contact with potentially harmful exogenous factors. Although the SC functions consistently as a protective barrier throughout the body, variations in functions and morphology occur across body sites with age and skin type. Healthy SC function also depends on the interplay between the chemosensory barrier, the skin's microbiome and the innate immune system. Dysregulation of SC barrier function can lead to the development of skin disorders, such as dry, flaky or sensitive skin, but the complete underlying pathophysiology of these are not fully understood. This review provides insight into the current literature and emerging themes related to epidermal barrier changes that occur in the context of dry, flaky and sensitive skin. Additional studies are needed to further elucidate the underlying aetiology of dry, flaky and sensitive skin and to provide tailored treatment.
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Affiliation(s)
- Joachim W Fluhr
- Institute of Allergology IFA Charité Universitätsmedizin, Berlin, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Allergology and Immunology, Berlin, Germany
| | | | - Majella E Lane
- Department of Pharmaceutics, UCL School of Pharmacy, London, UK
| | | | - Anthony V Rawlings
- Department of Pharmaceutics, UCL School of Pharmacy, London, UK
- AVR Consulting Ltd., Northwich, UK
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5
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Guri-Lamce I, AlRokh Y, Kim Y, Maeshima R, Graham C, Hart SL, McGrath JA, Jacków-Malinowska J. Topical gene editing therapeutics using lipid nanoparticles: 'gene creams' for genetic skin diseases? Br J Dermatol 2024; 190:617-627. [PMID: 38149939 DOI: 10.1093/bjd/ljad528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/12/2023] [Accepted: 12/17/2023] [Indexed: 12/28/2023]
Abstract
Patients living with inherited skin diseases have benefited from recent advances in DNA sequencing technologies that provide new or improved diagnostics. However, developing and delivering new treatments for the 'genodermatoses' remains challenging. The goal of creating topical preparations that can recover the inherent gene pathology remains largely aspirational. However, recent progress in two fields - the chemistry of topical delivery formulations (lipid nanoparticles) and the molecular biology of gene repair (CRISPR-Cas9, base and prime editing) - presents new opportunities to address this unmet need. In this review, we discuss how lipid nanoparticle delivery vehicles could be used to deliver gene-editing tools to formulate topical 'gene creams' suitable for the treatment of genodermatoses. We summarize the historical landscape of topical therapeutics and advances in gene editing that may herald an era of new therapies for patients with inherited skin disorders.
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Affiliation(s)
- Ina Guri-Lamce
- St John's Institute of Dermatology, King's College London, London, UK
| | - Yara AlRokh
- St John's Institute of Dermatology, King's College London, London, UK
| | - Youngah Kim
- St John's Institute of Dermatology, King's College London, London, UK
| | - Ruhina Maeshima
- Genetics and Genomic Medicine Department, UCL Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Carina Graham
- Genetics and Genomic Medicine Department, UCL Great Ormond Street Institute of Child Health, UCL, London, UK
| | - Stephen L Hart
- Genetics and Genomic Medicine Department, UCL Great Ormond Street Institute of Child Health, UCL, London, UK
| | - John A McGrath
- St John's Institute of Dermatology, King's College London, London, UK
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6
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Bouwstra JA, Nădăban A, Bras W, McCabe C, Bunge A, Gooris GS. The skin barrier: An extraordinary interface with an exceptional lipid organization. Prog Lipid Res 2023; 92:101252. [PMID: 37666282 PMCID: PMC10841493 DOI: 10.1016/j.plipres.2023.101252] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/29/2023] [Accepted: 08/30/2023] [Indexed: 09/06/2023]
Abstract
The barrier function of the skin is primarily located in the stratum corneum (SC), the outermost layer of the skin. The SC is composed of dead cells with highly organized lipid lamellae in the intercellular space. As the lipid matrix forms the only continuous pathway, the lipids play an important role in the permeation of compounds through the SC. The main lipid classes are ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). Analysis of the SC lipid matrix is of crucial importance in understanding the skin barrier function, not only in healthy skin, but also in inflammatory skin diseases with an impaired skin barrier. In this review we provide i) a historical overview of the steps undertaken to obtain information on the lipid composition and organization in SC of healthy skin and inflammatory skin diseases, ii) information on the role CERs, CHOL and FFAs play in the lipid phase behavior of very complex lipid model systems and how this knowledge can be used to understand the deviation in lipid phase behavior in inflammatory skin diseases, iii) knowledge on the role of both, CER subclasses and chain length distribution, on lipid organization and lipid membrane permeability in complex and simple model systems with synthetic CERs, CHOL and FFAs, iv) similarity in lipid phase behavior in SC of different species and complex model systems, and vi) future directions in modulating lipid composition that is expected to improve the skin barrier in inflammatory skin diseases.
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Affiliation(s)
- Joke A Bouwstra
- Division of Biotherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands.
| | - Andreea Nădăban
- Division of Biotherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Wim Bras
- Chemical Sciences Division, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831, United States of America
| | - Clare McCabe
- School of Engineering & Physical Science, Heriot-Watt University, Edinburgh, Scotland, UK
| | - Annette Bunge
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, CO 80401, United States of America
| | - Gerrit S Gooris
- Division of Biotherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
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Brash AR, Noguchi S, Boeglin WE, Calcutt MW, Stec DF, Schneider C, Meyer JM. Two C18 hydroxy-cyclohexenone fatty acids from mammalian epidermis: Potential relation to 12R-lipoxygenase and covalent binding of ceramides. J Biol Chem 2023; 299:104739. [PMID: 37086788 PMCID: PMC10209020 DOI: 10.1016/j.jbc.2023.104739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 04/11/2023] [Accepted: 04/15/2023] [Indexed: 04/24/2023] Open
Abstract
A key requirement in forming the water permeability barrier in the mammalian epidermis is the oxidation of linoleate esterified in a skin-specific acylceramide by the sequential actions of 12R-lipoxygenase, epidermal lipoxygenase-3, and the epoxyalcohol dehydrogenase SDR9C7 (short-chain dehydrogenase-reductase family 7 member 9). By mechanisms that remain unclear, this oxidation pathway promotes the covalent binding of ceramides to protein, forming a critical structure of the epidermal barrier, the corneocyte lipid envelope. Here, we detected, in porcine, mouse, and human epidermis, two novel fatty acid derivatives formed by KOH treatment from precursors covalently bound to protein: a "polar" lipid chromatographing on normal-phase HPLC just before omega-hydroxy ceramide and a "less polar" lipid nearer the solvent front. Approximately 100 μg of the novel lipids were isolated from porcine epidermis, and the structures were established by UV-spectroscopy, LC-MS, GC-MS, and NMR. Each is a C18 fatty acid and hydroxy-cyclohexenone with the ring on carbons C9-C14 in the polar lipid and C8-C13 in the less polar lipid. Overnight culture of [14C]linoleic acid with whole mouse skin ex vivo led to recovery of the 14C-labeled hydroxy-cyclohexenones. We deduce they are formed from covalently bound precursors during the KOH treatment used to release esterified lipids. KOH-induced intramolecular aldol reactions from a common precursor can account for their formation. Discovery of these hydroxy-cyclohexenones presents an opportunity for a reverse pathway analysis, namely to work back from these structures to identify their covalently bound precursors and relationship to the linoleate oxidation pathway.
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Affiliation(s)
- Alan R Brash
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
| | - Saori Noguchi
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - William E Boeglin
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - M Wade Calcutt
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Donald F Stec
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Claus Schneider
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Jason M Meyer
- Department of Dermatology, Vanderbilt University Medical Center, and Dermatology Service, Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
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8
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Jonca N, Simon M. The Cornified Envelope: A Versatile Contributor to the Epidermal Barrier. J Invest Dermatol 2023:S0022-202X(23)00101-X. [PMID: 37149811 DOI: 10.1016/j.jid.2023.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 05/08/2023]
Affiliation(s)
- Nathalie Jonca
- Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), University of Toulouse, French National Center for Scientific Research (CNRS), French National Institute of Health and Medical Research (INSERM), University Paul Sabatier, Toulouse, France; Department of Cell Biology and Cytology, Federative Institute of Biology, Purpan University Hospital, Toulouse, France
| | - Michel Simon
- Toulouse Institute for Infectious and Inflammatory Diseases (Infinity), University of Toulouse, French National Center for Scientific Research (CNRS), French National Institute of Health and Medical Research (INSERM), University Paul Sabatier, Toulouse, France.
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9
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Role of Omega-Hydroxy Ceramides in Epidermis: Biosynthesis, Barrier Integrity and Analyzing Method. Int J Mol Sci 2023; 24:ijms24055035. [PMID: 36902463 PMCID: PMC10003399 DOI: 10.3390/ijms24055035] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/19/2023] [Accepted: 02/25/2023] [Indexed: 03/08/2023] Open
Abstract
Attached to the outer surface of the corneocyte lipid envelope (CLE), omega-hydroxy ceramides (ω-OH-Cer) link to involucrin and function as lipid components of the stratum corneum (SC). The integrity of the skin barrier is highly dependent on the lipid components of SC, especially on ω-OH-Cer. Synthetic ω-OH-Cer supplementation has been utilized in clinical practice for epidermal barrier injury and related surgeries. However, the mechanism discussion and analyzing methods are not keeping pace with its clinical application. Though mass spectrometry (MS) is the primary choice for biomolecular analysis, method modifications for ω-OH-Cer identification are lacking in progress. Therefore, finding conclusions on ω-OH-Cer biological function, as well as on its identification, means it is vital to remind further researchers of how the following work should be done. This review summarizes the important role of ω-OH-Cer in epidermal barrier functions and the forming mechanism of ω-OH-Cer. Recent identification methods for ω-OH-Cer are also discussed, which could provide new inspirations for study on both ω-OH-Cer and skin care development.
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10
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Nicolaou A, Kendall AC. Current insights into skin lipids and their roles in cutaneous health and disease. Curr Opin Clin Nutr Metab Care 2023; 26:83-90. [PMID: 36574279 DOI: 10.1097/mco.0000000000000902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
PURPOSE OF REVIEW The unique and complex array of cutaneous lipids include essential components of the skin structure and signalling molecules mediating homeostasis and inflammation. Understanding skin lipid biology and metabolism can support our comprehension of health and disease, including systemic conditions with cutaneous involvement. RECENT FINDINGS Lipids found on the skin surface, produced by both the host and resident microbes, maintain and regulate the skin microbiome and the epidermal barrier, whilst altered contributions from either source can be detrimental to skin health. The unique lipid composition of the epidermal barrier is essential for its function, and recent studies have expanded our understanding of epidermal ceramide production. This has been supported by improved models available for skin research, including organotypic skin models enabling in-vitro production of complex acylceramides for the first time, and model systems facilitating in-silico exploration of the lipid profile changes observed in clinical samples. Studies have revealed further involvement of lipid mediators such as eicosanoids in cutaneous inflammation, as well as immune regulation in both healthy and diseased skin. SUMMARY Skin lipids offer exciting opportunities as therapeutic targets for many conditions, whether through topical interventions or nutritional supplementation.
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Affiliation(s)
- Anna Nicolaou
- Laboratory for Lipidomics and Lipid Biology, Division of Pharmacy and Optometry, School of Health Sciences
- Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Alexandra C Kendall
- Laboratory for Lipidomics and Lipid Biology, Division of Pharmacy and Optometry, School of Health Sciences
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11
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de Szalay S, Wertz PW. Protective Barriers Provided by the Epidermis. Int J Mol Sci 2023; 24:ijms24043145. [PMID: 36834554 PMCID: PMC9961209 DOI: 10.3390/ijms24043145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023] Open
Abstract
The skin is the largest organ of the body and consists of an epidermis, dermis and subcutaneous adipose tissue. The skin surface area is often stated to be about 1.8 to 2 m2 and represents our interface with the environment; however, when one considers that microorganisms live in the hair follicles and can enter sweat ducts, the area that interacts with this aspect of the environment becomes about 25-30 m2. Although all layers of the skin, including the adipose tissue, participate in antimicrobial defense, this review will focus mainly on the role of the antimicrobial factors in the epidermis and at the skin surface. The outermost layer of the epidermis, the stratum corneum, is physically tough and chemically inert which protects against numerous environmental stresses. It provides a permeability barrier which is attributable to lipids in the intercellular spaces between the corneocytes. In addition to the permeability barrier, there is an innate antimicrobial barrier at the skin surface which involves antimicrobial lipids, peptides and proteins. The skin surface has a low surface pH and is poor in certain nutrients, which limits the range of microorganisms that can survive there. Melanin and trans-urocanic acid provide protection from UV radiation, and Langerhans cells in the epidermis are poised to monitor the local environment and to trigger an immune response as needed. Each of these protective barriers will be discussed.
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Affiliation(s)
- Sarah de Szalay
- Sarah de Szalay Consulting, LLC, Wesy Milford, NJ 07480, USA
| | - Philip W. Wertz
- Dows Institute for Dental Research, College of Dentistry, University of Iowa, Iowa City, IA 52240, USA
- Correspondence:
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12
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Lim SH, Kim EJ, Lee CH, Park GH, Yoo KM, Nam SJ, Shin KO, Park K, Choi EH. A Lipid Mixture Enriched by Ceramide NP with Fatty Acids of Diverse Chain Lengths Contributes to Restore the Skin Barrier Function Impaired by Topical Corticosteroid. Skin Pharmacol Physiol 2021; 35:112-123. [PMID: 34348350 DOI: 10.1159/000518517] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 07/10/2021] [Indexed: 11/19/2022]
Abstract
INTRODUCTION The stratum corneum (SC) is a skin barrier that consists of corneocytes, intercellular lipids, and corneodesmosomes. Ceramides are composed of sphingoid bases linked with various types of fatty acids (FAs), and they are an essential constituent of SC intercellular lipids. Among their subtypes, ceramide NP with a phytosphingosine base is especially important. Most of the previous studies on barrier recovery have focused on a specific ceramide with a single chain FA, not with diverse chain lengths. Skin barrier function is impaired by various factors, including topical corticosteroid. OBJECTIVE We evaluated whether a lipid mixture enriched by ceramide NP with FAs of diverse chain lengths (CER [NP]*) can restore the skin barrier function impaired by topical corticosteroid. METHODS Twenty-seven healthy adult male volunteers were recruited. Topical corticosteroid was applied on both volar forearms of volunteers. Then, the test cream containing a lipid mixture with CER (NP)* was applied on the left forearm, and a vehicle cream without a lipid mixture was applied on the right forearm of each subject. The functional parameters of the skin barrier were compared before and after the treatment. Epidermal differentiation markers, hyaluronic acid synthase 3 (HAS3), cytokine levels, and the lipid profiles in the SC were analyzed. RESULTS The functional parameters of the skin barrier, such as barrier recovery rate, SC integrity, and SC hydration were significantly improved in the test cream-applied site compared to the vehicle cream-applied sites. Filaggrin and HAS3 levels were significantly higher in the sites applied with the test cream. Interleukin (IL)-1α levels were also significantly increased in these sites. IL-2, IL-6, IL-10, and IL-13 levels were significantly decreased in the test cream-applied sites. Lipid analyses showed that C18, C20, and total ceramide NP levels significantly increased in the sites where the test cream was applied. Also, C16, C18, C20, C24, and total ceramide NP levels were significantly elevated in the test cream-applied sites after acute barrier disruption. CONCLUSION Our results demonstrate that a lipid mixture enriched by CER (NP)* could recover the barrier function impaired by topical corticosteroid.
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Affiliation(s)
- Sung Ha Lim
- Department of Dermatology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Eun Jung Kim
- Department of Dermatology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Chung Hyuk Lee
- Department of Dermatology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | | | | | | | - Kyong-Oh Shin
- The Korean Institute of Nutrition, Department of Food Science and Nutrition, Convergence Program of Material Science for Medicine and Pharmaceutics, Hallym University, Chuncheon, Republic of Korea
| | - Kyungho Park
- The Korean Institute of Nutrition, Department of Food Science and Nutrition, Convergence Program of Material Science for Medicine and Pharmaceutics, Hallym University, Chuncheon, Republic of Korea
| | - Eung Ho Choi
- Department of Dermatology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
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13
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Wertz PW. Roles of Lipids in the Permeability Barriers of Skin and Oral Mucosa. Int J Mol Sci 2021; 22:ijms22105229. [PMID: 34063352 PMCID: PMC8155912 DOI: 10.3390/ijms22105229] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/05/2021] [Accepted: 05/10/2021] [Indexed: 02/06/2023] Open
Abstract
PubMed searches reveal much literature regarding lipids in barrier function of skin and less literature on lipids in barrier function of the oral mucosa. In terrestrial mammals, birds, and reptiles, the skin’s permeability barrier is provided by ceramides, fatty acids, and cholesterol in the outermost layers of the epidermis, the stratum corneum. This layer consists of about 10–20 layers of cornified cells embedded in a lipid matrix. It effectively prevents loss of water and electrolytes from the underlying tissue, and it limits the penetration of potentially harmful substances from the environment. In the oral cavity, the regions of the gingiva and hard palate are covered by keratinized epithelia that much resemble the epidermis. The oral stratum corneum contains a lipid mixture similar to that in the epidermal stratum corneum but in lower amounts and is accordingly more permeable. The superficial regions of the nonkeratinized oral epithelia also provide a permeability barrier. These epithelial regions do contain ceramides, cholesterol, and free fatty acids, which may underlie barrier function. The oral epithelial permeability barriers primarily protect the underlying tissue by preventing the penetration of potentially toxic substances, including microbial products. Transdermal drug delivery, buccal absorption, and lipid-related disease are discussed.
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