How Does the Skin Barrier Work?

How Does the Skin Barrier Work?

The skin barrier is a complex, multi-layered system that protects the body from environmental insults, regulates water loss, and maintains immune homeostasis. Its primary component is the stratum corneum, composed of corneocytes embedded in a lipid matrix rich in ceramides, cholesterol, and free fatty acids. This structure, often described as a 'brick and mortar' model, is supported by tight junctions, desmosomes, and the skin microbiome. Disruption of this barrier is implicated in conditions such as atopic dermatitis (AD) and psoriasis, where impaired barrier function and immune dysregulation are hallmarks [1][3].

Research into skin barrier function spans multiple pathways, including sphingolipid metabolism, NAD+ biology, and collagen-derived peptide signaling. The following sections summarize studies that have investigated specific compounds or interventions in various models, from in vitro systems to animal models and human clinical trials.

Research Studies

Vernix Caseosa and Primary Prevention of Atopic Dermatitis in Newborns

Vernix caseosa is a naturally occurring, white, creamy substance that covers the skin of newborns at birth, forming during the last trimester of gestation. A clinical trial is investigating whether retention of vernix caseosa on newborn skin can prevent the development of atopic dermatitis (AD), also known as eczema. AD is a chronic inflammatory skin disease that usually begins in infancy and affects up to one in five children worldwide. The study focuses on primary prevention, targeting skin-barrier integrity and the skin microbiome during early life [1].

Peristomal Skin Barrier Characteristics in People With a Stoma

An exploratory study is characterizing the skin barrier at peristomal and non-peristomal sites in individuals living with a stoma. The research aims to determine whether differences exist in barrier function between these sites and among different stoma types (colostomy, ileostomy, urostomy). Participants undergo non-invasive skin procedures during a one-hour appointment. This work may inform our understanding of how stoma function influences skin barrier properties [2].

Niacinamide Riboside and Facial Skin Aging

Niacinamide riboside (NR), also known as nicotinamide riboside, is an endogenous compound and a precursor to nicotinamide adenine dinucleotide (NAD+). Research by Maussudi et al. (2012) demonstrated that skin NAD+ levels were negatively correlated with age in both males and females, and aged skin was correlated with increased DNA damage. A clinical trial is evaluating the efficacy of topical NR on signs of facial skin aging, proposing that supporting skin NAD+ may combat DNA damage and support skin cell resilience [4].

AP Collagen Peptides and Skin Hydration in a Mouse Model of Atopic Dermatitis

Atopic dermatitis is characterized by impaired skin barrier function and Th2-mediated immune responses. A study evaluated AP collagen peptide (APCP), which contains collagen tripeptide (CTP), in an oxazolone-induced AD-like model using hairless mice. The researchers assessed skin hydration and transepidermal water loss to determine the potential effects of APCP on barrier function and inflammatory responses [5].

Curcumin Delivery via Mussel Adhesive Protein Ethosomes for Psoriasis

Curcumin has shown therapeutic potential for psoriasis, but its poor skin permeability and retention limit efficacy. Researchers fabricated mussel adhesion protein (MAP)-modified curcumin-loaded ethosomes (Cur-MAP-Es) to enhance permeation and retention. The average particle size was 197.17 nm, and encapsulation efficiency was 90.84%. The Cur-MAP-Es exhibited a spherical morphology and were tested for improved topical treatment of psoriasis [6].

Metabolic Engineering of Saccharomyces cerevisiae for Phytoceramide Production

Phytoceramides are essential sphingolipids that support skin barrier integrity and hydration. Due to their intricate structures and low natural abundance, scalable production is challenging. A study used metabolic engineering in Saccharomyces cerevisiae, implementing three strategies: overexpression of SUR2 (sphinganine C4-hydroxylase) to boost phytosphingolipid formation; deletion of SCS7 (ceramide α-hydroxylase) to redirect flux toward non-hydroxylated phytoceramides; and overexpression of ISC1 (inositol phospho...). This integrated approach aimed to enhance phytoceramide production [7].

Oral Collagen Peptides and Skin Barrier Function in Women

A clinical study is investigating whether oral intake of two different doses of collagen-derived peptides for three months improves facial skin barrier integrity in women with dry, sensitive skin, compared with a placebo. The trial aims to determine the effects of collagen peptides on barrier function in this population [8].

Comparison of Skin Barrier Assessment Methods

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Sources

• [1] Retention of Vernix Caseosa in Newborns for Primary Prevention of Atopic Dermatitis
• [2] Exploratory Study of Peristomal and Non-Peristomal Skin Barrier Characteristics in People With a Stoma
• [3] Integrated InPETM drug analysis and transcriptomics to explore potential mechanisms and key active components of multiple traditional Chinese medicine prescriptions for psoriasis.
• [4] Efficacy of Topical Niacinamide Riboside on the Signs of Facial Skin Aging
• [5] Potential Supportive Effects of AP Collagen Peptides on Skin Hydration in a Mouse Model of Oxazolone-Induced Atopic Dermatitis.
• [6] Improved topical delivery of curcumin by mussel adhesive protein functionalized ethosomes for effective psoriasis treatment.
• [7] Metabolic engineering of Saccharomyces cerevisiae sphingolipid pathways for enhanced phytoceramide production.
• [8] Evaluation of Oral Collagen Peptides on Skin Barrier Function in Women