Lipids and skin barrier function--a clinical perspective

Ceramide as a Promising Tool for Diagnosis and Treatment of Clinical Diseases: A Review of Recent Advances

Background/Objectives: Ceramide, a sphingolipid metabolite, has emerged as a key player in various physiological and pathological processes. Changes in ceramide levels are associated with the occurrence and development of various diseases, highlighting its potential as a biomarker of various clinical diseases. Methods: The biosynthesis and metabolism of ceramide are discussed, along with its functions in cell signaling, apoptosis, and inflammation. This study further examines the potential of ceramide as a biomarker for disease diagnosis and treatment. Results: This article highlights the involvement of ceramide in several diseases, including cardiovascular diseases, dermatosis, cancer, neurodegenerative disorders and metabolic syndromes. For each disease, the potential of ceramide as a biomarker for disease diagnosis and prognosis is explored, and the feasibility of therapeutic strategies targeting ceramide metabolism are reviewed. Additionally, the challenges and future directions in the field of ceramide research are addressed. Conclusions: This review article provides an overview of the recent advances in understanding the role of ceramide in clinical diseases and its potential as a diagnostic and therapeutic tool.

C24 Ceramide Lipid Nanoparticles for Skin Wound Healing

Background/Objectives: C24 ceramide plays a crucial role in skin regeneration and wound healing; however, its hydrophobic nature limits its application in therapeutic formulations. This study aims to enhance the bioavailability and efficacy of C24 ceramide by developing ceramide-based lipid nanoparticles (C24-LNP) and evaluate their impact on skin regeneration and wound healing. Methods: C24-LNP was synthesized and characterized for aqueous stability and bioavailability. In vitro experiments were conducted to assess its effects on keratinocyte proliferation and migration. Molecular biological analysis examined key signaling pathways, including AKT and ERK1/2 phosphorylation. Additionally, an in vivo mouse wound model was utilized to evaluate wound healing efficacy, with histological analysis performed to assess epidermal and dermal regeneration. Results: C24-LNP exhibited improved aqueous stability and bioavailability compared to free C24 ceramide. In vitro studies demonstrated that C24-LNP significantly promoted keratinocyte proliferation and migration. Molecular analysis revealed activation of the AKT and ERK1/2 signaling pathways, which are critical for cell growth and skin regeneration. In vivo wound healing experiments showed that C24-LNP accelerated wound closure compared to the control group. Histological analysis confirmed enhanced epidermal and dermal regeneration, leading to improved structural and functional skin repair. Conclusion: The lipid nanoparticle formulation of C24 ceramide effectively increases its bioavailability and enhances its therapeutic efficacy in skin regeneration and wound healing. C24-LNP presents a scalable and cost-effective alternative to traditional growth factor-based therapies, offering significant potential for clinical applications in wound care and dermatological treatments.

Poly-γ-Glutamic Acid from a Novel Bacillus subtilis Strain: Strengthening the Skin Barrier and Improving Moisture Retention in Keratinocytes and a Reconstructed Skin Model

A novel Bacillus subtilis HB-31 strain was isolated from Gotjawal Wetland in Jeju Island, Republic of Korea. A mucus substance produced by this strain was identified as high-molecular-weight poly-γ-glutamic acid (γ-PGA) using NMR, Fourier transform infrared spectroscopy, and size-exclusion chromatography/multi-angle light scattering analyses. We evaluated whether γ-PGA strengthened the skin barrier using keratinocytes and a reconstructed skin model. In keratinocytes, γ-PGA treatment dose-dependently increased the mRNA expression of skin barrier markers, including filaggrin, involucrin, loricrin, serine palmitoyl transferase, fatty acid synthase, and 3-hydroxy-3-methylglutaryl coenzyme A reductase. γ-PGA also enhanced hyaluronic acid synthesis by upregulating hyaluronic acid synthase-1, -2, and -3 mRNA levels and promoted aquaporin 3 expression, which is involved in skin hydration. In the reconstructed skin model, topical application of 1% γ-PGA elevated filaggrin, involucrin, CD44, and aquaporin 3 expression, compared to the control. These results suggest that the newly isolated HB-31 can be used as a commercial production system of high-molecular-weight γ-PGA, which can serve as an effective ingredient for strengthening the skin barrier and improving moisture retention. Further research is needed to explore the long-term effects of γ-PGA on skin health and its application in treating skin conditions.

Causal relationship between circulating plasma lipids and atopic dermatitis risk: potential drug targets and therapeutic strategies

This study leverages the most up-to-date lipidomic data to provide fresh perspectives on the treatment and prevention of atopic dermatitis. The analysis utilized genome-wide association study (GWAS) data on 179 circulating plasma lipids and AD GWAS data. The primary analysis method employed was the inverse variance weighting (IVW) method, and several sensitivity analyses were conducted to ensure the reliability of the results. Additionally, summary-data-based MR (SMR) and colocalization analysis were utilized to investigate the underlying biological pathways of AD. After rigorous analyses, the IVW method utilized in TSMR analysis pinpointed six plasma lipids with potentially reduced AD risk when elevated. Subsequently, MVMR analysis revealed that there is no independent causal effect of different lipids within the same subtype on AD. Bidirectional MR analysis did not indicate reverse causality, and SMR analysis suggested FADS1 and FADS2 as potential drug targets for AD treatment. This MR study demonstrated a causal relationship between specific plasma lipid levels and AD risk at the genetic level, which can be used for clinical screening of AD plasma lipid biomarkers and provides a novel perspective on potential therapeutic strategies.

Topically Applied Therapies for the Treatment of Skin Disease: Past, Present, and Future

The purpose of this review is to summarize essential biological, pharmaceutical, and clinical aspects in the field of topically applied medicines that may help scientists when trying to develop new topical medicines. After a brief history of topical drug delivery, a review of the structure and function of the skin and routes of drug absorption and their limitations is provided. The most prevalent diseases and current topical treatment approaches are then detailed, the organization of which reflects the key disease categories of autoimmune and inflammatory diseases, microbial infections, skin cancers, and genetic skin diseases. The complexity of topical product development through to large-scale manufacturing along with recommended risk mitigation approaches are then highlighted. As such topical treatments are applied externally, patient preferences along with the challenges they invoke are then described, and finally the future of this field of drug delivery is discussed, with an emphasis on areas that are more likely to yield significant improvements over the topical medicines in current use or would expand the range of medicines and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of the skin and its associated diseases and current treatments along with the intricacies of topical formulation development should be helpful in making judicious decisions about the development of new or improved topical medicines. These aspects include the choices of the active ingredients, formulations, the target patient population's preferences, limitations, and the future with regard to new skin diseases and topical medicine approaches.

Cholesterol Nanofiber Patches with Sustainable Oil Delivery Eliminate Inflammation in Atopic Skin

Atopic skin is dry and itchy and lacks integrity. Impaired skin barrier results from altered lipid composition of the skin. A crucial skin lipid, cholesterol, provides flexibility and homeostasis of the cell membranes' lipid bilayer. Cholesterol-based creams and natural oils, especially blackcurrant seed oil, are beneficial for skin care as they hydrate the skin and improve its integrity. The major atopic symptom, skin dryness, can be overcome by the application of porous patches enhanced with cholesterol and natural oil. The base of the patches is constructed of polyimide (PI) nanofibers with cholesterol coatings and externally added blackcurrant seed oil. The presence of cholesterol in PI mats hinders the passage of oil through the patches to the skin, resulting in sustained and prolonged skin hydration. The theoretical and numerical investigations of oil dynamics in porous mats confirmed the experimental results, showing a prolonged skin hydration effect up to 6 h. Additionally, as demonstrated by in vivo tests on atopic mice, cholesterol patches lower serum immunoglobulin E levels and expression of proinflammatory cytokines in the skin, thereby accelerating skin healing. Our results hold great promise for the long-term application of the patches in atopic dermatitis treatment.

Piperlongumine regulates genes involved in the skin barrier in epidermal keratinocyte HaCaT cells

Given that the skin is the largest tissue in the human body, performing external barrier functions with innate and adaptive immunity and undergoing substantial changes during aging, it is under investigation as a major target of various bioactive molecules. In the present study, we examined the biological activity of the senolytic piperlongumine by analyzing alterations in mRNA expression of notable skin genes using transformed aneuploid immortal epidermal keratinocytes, HaCaT cells. We observed that piperlongumine increased the mRNA expression of genes playing critical roles in skin barrier function. In addition, piperlongumine increased expression enzymes involved in the synthesis of ceramide, a major component of intercellular lipids. Furthermore, we measured the protein levels of various cytokines secreted by epidermal keratinocytes and found changes in the release of GRO-αβγ, CCL5, and MCP1. Additionally, we observed that piperlongumine treatment modulated the expression of keratinocyte-specific aging markers and influenced telomerase activity. Based on these findings, piperlongumine could regulate the physiological activity of epidermal keratinocytes to induce beneficial effects in human skin by regulating important skin-related genes.

Sphingolipid-Induced Bone Regulation and Its Emerging Role in Dysfunction Due to Disease and Infection

The human skeleton is a metabolically active system that is constantly regenerating via the tightly regulated and highly coordinated processes of bone resorption and formation. Emerging evidence reveals fascinating new insights into the role of sphingolipids, including sphingomyelin, sphingosine, ceramide, and sphingosine-1-phosphate, in bone homeostasis. Sphingolipids are a major class of highly bioactive lipids able to activate distinct protein targets including, lipases, phosphatases, and kinases, thereby conferring distinct cellular functions beyond energy metabolism. Lipids are known to contribute to the progression of chronic inflammation, and notably, an increase in bone marrow adiposity parallel to elevated bone loss is observed in most pathological bone conditions, including aging, rheumatoid arthritis, osteoarthritis, and osteomyelitis. Of the numerous classes of lipids that form, sphingolipids are considered among the most deleterious. This review highlights the important primary role of sphingolipids in bone homeostasis and how dysregulation of these bioactive metabolites appears central to many chronic bone-related diseases. Further, their contribution to the invasion, virulence, and colonization of both viral and bacterial host cell infections is also discussed. Many unmet clinical needs remain, and data to date suggest the future use of sphingolipid-targeted therapy to regulate bone dysfunction due to a variety of diseases or infection are highly promising. However, deciphering the biochemical and molecular mechanisms of this diverse and extremely complex sphingolipidome, both in terms of bone health and disease, is considered the next frontier in the field.

The facial microbiome and metabolome across different geographic regions

IMPORTANCE

Characterization of the skin microbiome and metabolome across geography will help uncover the climate factors behind the prevalence of skin disorders and provide suggestions for skincare products for people living in different geographic regions.

The heterogeneity and complexity of skin surface lipids in human skin health and disease

The outermost epidermal layer of the skin, the stratum corneum, is not simply a barrier that safeguards skin integrity from external insults and invaders, it is also a delicately integrated interface composed of firm, essentially dead corneocytes and a distinctive lipid matrix. Together, the stratum corneum lipid matrix and sebum lipids derived from sebaceous glands give rise to a remarkably complex but quite unique blend of skin surface lipids that demonstrates tremendous heterogeneity and provides the skin with its indispensable protective coating. The stratum corneum lipid matrix is composed primarily of three major lipid classes: ceramides, non-esterified fatty acids and cholesterol, whereas sebum is a waxy mixture predominantly composed of acylglycerols, wax esters, non-esterified fatty acids, squalene, cholesterol and cholesterol esters. The balance of these skin surface lipids in terms of their relative abundance, composition, molecular organisation and dynamics, and their intricate interactions play a crucial role in the maintenance of healthy skin. For that reason, even minuscule alterations in skin surface lipid properties or overall lipid profile have been implicated in the aetiology of many common skin diseases including atopic dermatitis, psoriasis, xerosis, ichthyosis and acne. Novel lipid-based interventions aimed at correcting the skin surface lipid abnormalities have the potential to repair skin barrier integrity and the symptoms associated with such skin diseases, even though the exact mechanisms of lipid restoration remain elusive.

Development of a novel in vitro strategy to understand the impact of shaving on skin health: combining tape strip exfoliation and human skin equivalent technology

Introduction

The removal of unwanted hair is a widespread grooming practice adopted by both males and females. Although many depilatory techniques are now available, shaving remains the most common, despite its propensity to irritate skin. Current techniques to investigate the impact of shaving regimes on skin health rely on costly and lengthy clinical trials, which hinge on recruitment of human volunteers and can require invasive biopsies to elucidate cellular and molecular-level changes.

Methods

Well-characterised human skin equivalent technology was combined with a commonplace dermatological technique of tape stripping, to remove cellular material from the uppermost layer of the skin (stratum corneum). This method of exfoliation recapitulated aspects of razor-based shaving in vitro, offering a robust and standardised in vitro method to study inflammatory processes such as those invoked by grooming practices.

Results

Tape strip insult induced inflammatory changes in the skin equivalent such as: increased epidermal proliferation, epidermal thickening, increased cytokine production and impaired barrier function. These changes paralleled effects seen with a single dry razor pass, correlated with the number of tape strips removed, and were attenuated by pre-application of shaving foam, or post-application of moisturisation.

Discussion

Tape strip removal is a common dermatological technique, in this study we demonstrate a novel application of tape stripping, to mimic barrier damage and inflammation associated with a dry shave. We validate this method, comparing it to razor-based shaving in vitro and demonstrate the propensity of suitable shave- and skin-care formulations to mitigate damage. This provides a novel methodology to examine grooming associated damage and a platform for screening potential skin care formulations.

Review of available "extraction + purification" methods of natural ceramides and their feasibility for sewage sludge analysis

Natural ceramide, a biologically active compound present in plants, has been used widely in food, cosmetics, and pharmaceutical industries. Abundant ceramide has been detected in sewage sludge, which has inspired the idea to recycle ceramide from it. Therefore, the methods of extracting, purifying, and detecting ceramides from plants were reviewed, with the aim to establish methods to get condensed ceramide from sludge. Ceramide extraction methods include traditional methods (maceration, reflux, and Soxhlet extraction) and green technologies (ultrasound-assisted, microwave-assisted, and supercritical fluid extraction). In the past two decades, more than 70% of the articles have used traditional methods. However, green extraction methods are gradually improved and showed high extraction efficiency with lower solvent consumed. The preferred technique for ceramide purification is chromatography. Common solvent systems include chloroform-methanol, n-hexane-ethyl acetate, petroleum ether-ethyl acetate, and petroleum ether-acetone. For structural determination of ceramide, infrared spectroscopy, nuclear magnetic resonance spectroscopy, and mass spectrometry are used in combination. Among quantitative analysis methods for ceramide, liquid chromatography-mass spectrometry was the most accurate. This review concludes that with our prilemenary experiment results it is feasible to apply the plant "extraction + purification" process of ceramide to sludge, but more optimization need to be performed to get better results.

Skin Barrier Function and Its Relationship With IL-17, IL-33, and Filaggrin in Malar Melasma

BACKGROUND

The pathogenesis of melasma remains unclear. Interleukin (IL)-17, a proinflammatory mediator, disturbs barrier function. Filaggrin (FLG) is a protein involved in epidermal barrier homeostasis and may be affected by IL-17 and IL-33.

OBJECTIVE

To evaluate epidermal barrier function in malar melasma and its association with the expression of FLG, IL-17, and IL-33.

METHODS

Twenty patients with malar melasma were included in this study. Colorimetric and transepidermal water loss (TEWL) was measured in lesional and adjacent unaffected skin at baseline and 30 minutes after barrier disruption using the tape-stripping test. Biopsies from melasma and perilesional skin were performed to evaluate the presence of FLG by immunohistochemistry, and profilaggrin, IL-17, and IL-33 expression were analyzed by reverse transcription-qualitative polymerase chain reaction.

RESULTS

After the stripping test, the erythema and TEWL values were higher in the melasma than in the unaffected skin ( P = 0.01). Thirty minutes later, TEWL diminished, but it remained higher than in the perilesional skin. Profilaggrin increased as TEWL gradually decreased (R = -0.68, P = 0.04). FLG and IL-17 were higher in the melasma than in the perilesional skin ( P = 0.003). IL-17 and profilaggrin expression were positively associated (R = 0.60, P = 0.04). IL-33 expression was higher in the adjacent normal skin than in the melasma ( P = 0.01).

CONCLUSION

This study found subclinical inflammation in the skin adjacent to the melasma, dysfunction of the epidermal barrier in lesions associated with chronic inflammation, and an abnormal differentiation process promoting an increase in FLG. These findings highlight the need to preserve the integrity of the facial stratum corneum in these patients.

Elucidating collective translocation of nanoparticles across the skin lipid matrix: a molecular dynamics study

The top layer of skin, the stratum corneum, provides a formidable barrier to the skin. Nanoparticles are utilized and further explored for personal and health care applications related to the skin. In the past few years, several researchers have studied the translocation and permeation of nanoparticles of various shapes, sizes, and surface chemistry through cell membranes. Most of these studies focused on a single nanoparticle and a simple bilayer system, whereas skin has a highly complex lipid membrane architecture. Moreover, it is highly unlikely that a nanoparticle formulation applied on the skin will not have multiple nanoparticle-nanoparticle and skin-nanoparticle interactions. In this study, we have utilized coarse-grained MARTINI molecular dynamics simulations to assess the interactions of two types (bare and dodecane-thiol coated) of nanoparticles with two models (single bilayer and double bilayer) of skin lipid membranes. The nanoparticles were found to be partitioned from the water layer to the lipid membrane as an individual entity as well as in the cluster form. It was discovered that each nanoparticle reached the interior of both single bilayer and double bilayer membranes irrespective of the nanoparticle type and concentration, though coated particles were observed to efficiently traverse across the bilayer when compared with bare particles. The coated nanoparticles also created a single large cluster inside the membrane, whereas the bare nanoparticles were found in small clusters. Both the nanoparticles exhibited preferential interactions with cholesterol molecules present in the lipid membrane as compared to other lipid components of the membrane. We have also observed that the single membrane model exhibited unrealistic instability at moderate to higher concentrations of nanoparticles, and hence for translocation study, a minimum double bilayer model should be employed.

Pseudomonas Aeruginosa Theft Biofilm Require Host Lipids of Cutaneous Wound

OBJECTIVE

This work addressing complexities in wound infection, seeks to test the reliance of bacterial pathogen Pseudomonas aeruginosa (PA) on host skin lipids to form biofilm with pathological consequences.

BACKGROUND

PA biofilm causes wound chronicity. Both CDC as well as NIH recognizes biofilm infection as a threat leading to wound chronicity. Chronic wounds on lower extremities often lead to surgical limb amputation.

METHODS

An established preclinical porcine chronic wound biofilm model, infected with PA or Pseudomonas aeruginosa ceramidase mutant (PA ∆Cer ), was used.

RESULTS

We observed that bacteria drew resource from host lipids to induce PA ceramidase expression by three orders of magnitude. PA utilized product of host ceramide catabolism to augment transcription of PA ceramidase. Biofilm formation was more robust in PA compared to PA ∆Cer . Downstream products of such metabolism such as sphingosine and sphingosine-1-phosphate were both directly implicated in the induction of ceramidase and inhibition of peroxisome proliferator-activated receptor (PPAR)δ, respectively. PA biofilm, in a ceram-idastin-sensitive manner, also silenced PPARδ via induction of miR-106b. Low PPARδ limited ABCA12 expression resulting in disruption of skin lipid homeostasis. Barrier function of the wound-site was thus compromised.

CONCLUSIONS

This work demonstrates that microbial pathogens must co-opt host skin lipids to unleash biofilm pathogenicity. Anti-biofilm strategies must not necessarily always target the microbe and targeting host lipids at risk of infection could be productive. This work may be viewed as a first step, laying fundamental mechanistic groundwork, toward a paradigm change in biofilm management.

Treatment of Porokeratosis Ptychotropica With a Topical Combination of Cholesterol and Simvastatin

This case report describes 2 patients with Ptychotropic porokeratosis who were treated with a combination of cholesterol and simvastatin.

Skin-associated adipocytes in skin barrier immunity: A mini-review

The skin contributes critically to health via its role as a barrier tissue against a multitude of external pathogens. The barrier function of the skin largely depends on the uppermost epidermal layer which is reinforced by skin barrier immunity. The integrity and effectiveness of skin barrier immunity strongly depends on the close interplay and communication between immune cells and the skin environment. Skin-associated adipocytes have been recognized to play a significant role in modulating skin immune responses and infection by secreting cytokines, adipokines, and antimicrobial peptides. This review summarizes the recent understanding of the interactions between skin-associated adipocytes and other skin cells in maintaining the integrity and effectiveness of skin barrier immunity.

Development of a nanotechnological hydrogel containing desonide nanocapsules in association with acai oil: design and in vivo evaluation

Nanotechnological products have been used as strategies to optimize the therapy and minimize the side effects of topical corticoids. The objective of this study was to develop hydrogels by the addition of sclerotium gum to the suspensions of desonide-loaded açai oil-based nanocapsules and to study their biological effect using an animal model of acute skin inflammation. The hydrogels presented a pH compatible with topical application (4.4 to 5.0), nanometric mean diameter (131 to 165 nm), pseudoplastic behavior, and stability under room conditions during 30 days. The in vitro skin permeation/penetration study demonstrated that a higher amount of desonide (p < 0.05) was retained in the epidermis from the nanotechnological-hydrogels (0.33 to 0.36 µg.cm²) in comparison to the commercial gel cream (0.16 µg.cm²). In the dermis, the nanostructured hydrogels promoted a lower DES retention compared to the non-nanostructured formulations (p < 0.05). This result may indicate a smaller amount of drug reaching the bloodstream and, thus, fewer side effects can be expected. Concerning the anti-inflammatory effect, the developed hydrogels reduced both ear edema and inflammatory cell infiltration, showing an effect comparable to the commercially available formulation, which presents twice the drug concentration. The hydrogels developed may be considered a promising approach to treat dermatological disorders.

Delta-5® oil, containing the anti-inflammatory fatty acid sciadonic acid, improves skin barrier function in a skin irritation model in healthy female subjects

Background

Sciadonic acid (SA) is an anti-inflammatory fatty acid displacing arachidonic acid (ARA) from specific phospholipid pools, thus modulating downstream pro-inflammatory lipid mediators. Its novel anti-inflammatory actions have been studied in vitro, in pre-clinical models, and stemming from testimonials, after topical- and oral application. It has not been tested in a formal clinical study for topical benefits previously. Skin barrier layer was our focus as it has a critically important role in maintaining skin moisture balance.

Methods

Herein, forearm skin was left undamaged; or barrier layer was chemically-damaged with 2% sodium lauryl sulfate (SLS) for 24 h. SLS-damaged skin was left untreated or treated with Delta-5® oil containing 24% SA twice daily for 27 days. Barrier function was assessed by open chamber transepidermal water loss (TEWL) and skin surface impedance on days 0 (clear skin), -1 (1-day post-SLS), -2 (2-days post-SLS, 1-day post-Delta-5), -3, -7, and − 28.

Results

Relative to day 1, Delta-5 oil statistically significantly decreased TEWL vs. untreated damaged sites, on days 3 (125% more reduced), -7 (74% more reduced), and − 28 (69% more reduced). Decreases in TEWL following chemical damage indicates improved skin barrier repair and healing. Similar patterns were quantified for skin impedance. There was also reduced redness observed on days 3 and − 7 with Delta-5 oil vs. untreated SLS-damaged skin.

Conclusions

Delta-5 oil thus has anti-inflammatory potential in human skin, under controlled clinical conditions, to accelerate irritant-induced healing, and improve skin barrier function. Improvement in barrier function would benefit dermatitis, acne, eczema, and skin scarring. In normal skin, Delta-5 oil has potential to promote healthy, moisturized skin; and improve skin structure, elasticity, and firmness.

Commensal Staphylococcus epidermidis contributes to skin barrier homeostasis by generating protective ceramides

Previously either regarded as insignificant or feared as potential sources of infection, the bacteria living on our skin are increasingly recognized for their role in benefitting human health. Skin commensals modulate mucosal immune defenses and directly interfere with pathogens; however, their contribution to the skin's physical integrity is less understood. Here, we show that the abundant skin commensal Staphylococcus epidermidis contributes to skin barrier integrity. S. epidermidis secretes a sphingomyelinase that acquires essential nutrients for the bacteria and assists the host in producing ceramides, the main constituent of the epithelial barrier that averts skin dehydration and aging. In mouse models, S. epidermidis significantly increases skin ceramide levels and prevents water loss of damaged skin in a fashion entirely dependent on its sphingomyelinase. Our findings reveal a symbiotic mechanism that demonstrates an important role of the skin microbiota in the maintenance of the skin's protective barrier.

Revealing the Correlation between Altered Skin Lipids Composition and Skin Disorders

Human skin layers serve as a barrier between the body and the environment, by preventing water loss and blocking the entry of chemicals, allergens, and microbes. Recent data showed that skin lipids are vital ‘key players’ of several functions and mechanisms performing in the skin, such as, barrier function and microbiome composition. Abnormalities in lipid composition have been observed in inflammatory cutaneous diseases with a disrupted skin barrier. This review aims to demonstrate the fundamental role of keratinocytes, sebocytes, and microbiome-derived lipids in the maintenance of the skin barrier. Furthermore, it would reveal the correlation between altered skin lipids’ composition, microbiome, and the occurrence of certain dermatological disorders such as acne vulgaris, atopic dermatitis, psoriasis, and rosacea.

Deciphering the role of cartilage protein 1 in human dermal fibroblasts: a transcriptomic approach

Cartilage acidic protein 1A (hCRTAC1-A) is an extracellular matrix protein (ECM) of human hard and soft tissue that is associated with matrix disorders. The central role of fibroblasts in tissue integrity and ECM health made primary human dermal fibroblasts (NHDF) the model for the present study, which aimed to provide new insight into the molecular function of hCRTAC1-A. Specifically, we explored the differential expression patterns of specific genes associated with the presence of hCRTAC1-A by RNA-seq and RT-qPCR analysis. Functional enrichment analysis demonstrated, for the very first time, that hCRTAC1-A is involved in extracellular matrix organization and development, through its regulatory effect on asporin, decorin, and complement activity, in cell proliferation, regeneration, wound healing, and collagen degradation. This work provides a better understanding of putative hCRTAC1-A actions in human fibroblasts and a fundamental insight into its function in tissue biology.

Cutaneous Barriers and Skin Immunity

The skin barrier provides us with several lines of protection from outside hazards. Its most outward layers, the stratum corneum and the epidermis seal our body with an acidic, dry, and rather cool surface, hostile to microbes. Yet, there are also fine-tuned interactions between the mostly commensal microbiota on top of the skin surface, with underlying epidermal cells as well as the immune system, to preserve a healthy steady state and to initiate repair processes when necessary. We take a concise look at the recent insights on the inner workings of this complex barrier.

Increased 1-Deoxysphingolipids and Skin Barrier Dysfunction in the Skin of X-ray or Ultraviolet B Irradiation and Atopic Dermatitis Lesion Could Be Prevented by Moisturizer with Physiological Lipid Mixture

Background

Skin diseases characterized by epithelial barrier dysfunction show altered sphingolipid metabolism, which results in changes in the stratum corneum intercellular lipid components and structure. Under pathological conditions, 1-deoxysphingolipids form as atypical sphingolipids from de novo sphingolipid biosynthesis.

Objective

This study investigated the potential role of 1-deoxysphingolipids in skin barrier dysfunction secondary to X-ray and ultraviolet B (UVB) irradiation in vitro and in vivo. It was also evaluated changes in the expression of 1-deoxysphingolipids in lesional human skin of atopic dermatitis.

Methods

In this study, the changes in these 1-deoxysphingolipids levels of skin and serum samples were investigated in skin barrier dysfunction associated with X-ray and UVB irradiation in vitro and in vivo.

Results

Increased 1-deoxysphingolipids were observed in cultured normal human epidermal keratinocytes after X-ray irradiation. X-ray or UVB irradiation increased the production of 1-deoxysphingosine in a reconstituted 3-dimensional (3D) skin model. Interestingly, treatment with a physiological lipid mixture (multi-lamellar emulsion contained pseudoceramide), which can strengthen the epidermal permeability barrier function, resulted in decreased 1-deoxysphingosine formation in a reconstituted 3D skin model. Further investigation using a hairless mouse model showed similar preventive effects of physiological lipid mixture against 1-deoxysphingosine formation after X-ray irradiation. An increased level of 1-dexoysphingosine in the stratum corneum was also observed in lesional skin of atopic dermatitis.

Conclusion

1-deoxysphingosine might be a novel biomarker of skin barrier dysfunction and a physiological lipid mixture treatment could prevent 1-deoxysphingosine production and consequent skin barrier dysfunction.

Comprehensive characterization of the structure and properties of human stratum corneum relating to barrier function and skin hydration: modulation by a moisturizer formulation

The stratum corneum (SC) is key in the maintenance of the biomechanical barrier and hydration of skin. Our previous investigations showed beneficial effects of a combination of emollients on water capture and retention and protein and lipid organization, all of which are linked to dryness and dry skin damage. Here, we show how a formulation containing an emollient combination ("Trio") and its basal formulation (placebo) impacted the descriptors of SC hydration in SC layers. Only the Trio formulation-not its placebo formulation-modified SC biomechanical drying stress behaviour and imparted a high capacity to protect it from dehydration. This was in accordance with findings at the molecular level using Raman analyses and at the structural level using cryo-scanning electron microscopy (SEM). After topical application, only the Trio formulation profoundly increased lateral packing of lipids and their compactness. Cryo-SEM showed that, unlike the placebo formulation, the Trio formulation prevented the water loss when applied before the dehydration process. In conclusion, these studies demonstrate that stresses in the SC due to dehydration can be alleviated using a formulation containing emollients that interact with the SC lipid components.

Skin lipids in health and disease: A review

Our skin is the interface between us and our environment - a flexible barrier that has evolved for protection, immunity, regulation and sensation. Once regarded as inert, we now know that it is a dynamic environment. Skin lipids are crucial to the structure and function of skin. From deep in the hypodermis, through the ceramide-rich epidermis, to the lipids of the skin surface, there are a vast array of different lipids with important roles to play. This review firstly discusses the lipid composition of human skin and secondly, changes that have been found in skin lipid composition in different skin diseases. Further research into skin lipids facilitated by ever-improving methodologies will no doubt generate new knowledge, paving the way for diagnosis, prevention and treatment of skin disorders and diseases.

Assessment of non-invasive techniques and herbal-based products on dermatological physiology and intercellular lipid properties

Skin is the largest external organ of the human body. It acts as a barrier to protect the human body from environmental pollution, mechanical stress, and excessive water loss. The defensive function resides primarily on top of the epidermis layer commonly known as stratum corneum (SC). Human SC consists of three major lipids, namely ceramide, free fatty acid, and cholesterol that comprise approximately 50%, 25%, and 25% of the total lipid mass, respectively. The optimal composition of SC lipids is the vital epidermal barrier function of the skin. On the other hand, skin barrier serves to limit passive water loss from the body, reduces chemical absorption from the environment, and prevents microbial infection. In contrast, epidermal lipids are important to maintain the cell structure, growth and differentiation, cohesion and desquamation as well as formation of a permeability barrier. Multiple non-invasive in vivo approaches were implemented on a regular basis to monitor skin physiological and intercellular lipid properties. The measurement of different parameters such as transepidermal water loss (TEWL), hydration level, skin elasticity, collagen intensity, melanin content, sebum, pH, and tape stripping is essential to evaluate the epidermal barrier function. Novel non-invasive techniques such as tape stripping, ultrasound imaging, and laser confocal microscopy offer higher possibility of accurate and detailed characterisation of skin barrier. To date, these techniques have also been widely used to determine the effects of herbal plants in dermatology. Herbal plants have been traditionally used for ages to treat a variety of skin diseases, as reported by the World Health Organisation (WHO). Their availability, lower cost, and minimal or no side effects have created awareness among society, thus increase the demand for natural sources as the remedy to treat various skin diseases. This paper reviews several non-invasive techniques and evaluations of herbal-based product in dermatology.

Potential benefits of oral administration of AMORPHOPHALLUS KONJAC glycosylceramides on skin health - a randomized clinical study

Background

Ceramides play a fundamental role in maintaining the skin health as a function of improved barrier permeability. Reduced ceramide content results in skin dryness and wrinkledness. Intake of dietary ceramides potentially compensates the skin ceramide content. In the present study we have assessed the skin health benefits of oral supplementation of a hydroalcoholic extract from Amorphophallus konjac tubers standardized to 5% glycosylceramides, in a placebo-controlled clinical trial.

Methods

Fifty-one healthy human volunteers (aged 18–60 years) were supplemented with 100 mg/day of either a placebo or A. konjac extract capsules (5 mg glycosylceramides) for 6-weeks. The skin parameters were evaluated through dermatological diagnosis. Subject perceived efficacy of the product was further evaluated by a self-assessment questionnaire.

Results

Oral intake of A. konjac extract significantly decreased the skin dryness, hyperpigmentation, redness, itching and oilyness (p < 0.05). The improvement in skin health following intake of A. konjac extract was observed to be time-dependent from the start. Further, A. konjac extract was well-tolerated throughout the study, as no adverse events or toxic changes were recorded.

Conclusion

The study demonstrates the skincare properties of orally ingested glycosyl ceramides from konjac tubers.

Trial registration

CTRI/2018/12/016661 dated 13/12/2018 retrospectively registered, http://ctri.nic.in/Clinicaltrials/showallp.php?mid1=19851&EncHid=&userName=SkinCera

Photoprotective Activity of Topsentin, A Bis(Indole) Alkaloid from the Marine Sponge Spongosorites genitrix, by Regulation of COX-2 and Mir-4485 Expression in UVB-Irradiated Human Keratinocyte Cells

Skin is an important barrier to protect the body from environmental stress. However, exposure to ultraviolet radiation (UV) and various environmental oxidative stresses can cause skin inflammation. Cyclooxygenase-2 (COX-2) is an inducible enzyme that mediates the formation of prostaglandin E2 (PGE2) against internal and external inflammatory stimulations. Therefore, the inhibition of COX-2 is an important approach to maintain skin health and prevent skin inflammation and carcinogenesis. Topsentin, a bis(indolyl)imidazole alkaloid isolated from the marine sponge Spongosorites genitrix, has been reported to exhibit anti-tumor and anti-microbial activities. However, the effect of topsentin on skin inflammation and its underlying molecular mechanism has not been elucidated. In the present study, we identified the photoprotective effects of topsentin on UVB irradiated human epidermal keratinocyte HaCaT cells. Topsentin suppresses COX-2 expression and its upstream signaling pathways, AP-1 and MAPK. Furthermore, topsentin inhibits miR-4485, a new biomarker selected from a microarray, and its target gene tumor necrosis factor alpha induced protein 2 (TNF-α IP2). The photoprotective effect of topsentin was also confirmed in a reconstructed human skin model. These findings suggest that topsentin may serve as a potential candidate for cosmetic formulations with skin inflammatory-mediated disorder.

Wheat Extract Oil (WEO) Attenuates UVB-Induced Photoaging via Collagen Synthesis in Human Keratinocytes and Hairless Mice

The efficacy of wheat extract oil (WEO), standardized to glucosylceramides, for protecting against ultraviolet B (UVB)-induced damage of skin barrier function was assessed using the SHK-1 hairless mouse model and two human skin cell lines, namely, CCD-986sk and HeCaT. The ability of repeated oral administration of 30, 60, and 120 mg of WEO/kg/day for 12 weeks to prevent skin damage of SKH-1 hairless mice induced by UVB irradiation was evaluated. The results demonstrated that UVB-induced water evaporation (transepidermal water loss, TEWL) was significantly decreased by WEO. Similarly, UVB-induced losses in moisture and skin elasticity were improved by WEO supplementation. WEO attenuated the tissue procollagen type I, hyaluronic acid (HA), and ceramide reductions induced by UVB treatment as well. Collagen concentrations in skin tissue were increased in the WEO-treated mice, while UVB-induced epidermal thickening was reduced. In vitro studies using HeCaT human keratinocytes confirmed increased HA and collagen synthesis in response to WEO treatment. This may occur via WEO suppression of matrix metalloproteinase-1 (MMP-1), since its induction by UVB treatment was diminished in treated CCD-986sk cells. Oral administration of WEO improves skin barrier function in UVB-irradiated mice by attenuating damage typically observed in photoaging. This research further clarifies the clinical benefits previously observed by dietary WEO consumption.

Measuring the Antimicrobial Activity of Lauric Acid against Various Bacteria in Human Gut Microbiota Using a New Method

Lauric acid (LA) has a broad spectrum of anti-microbiological activities against enveloped viruses and various bacteria, and might be useful to protect against microbial infection and control the balance and distribution of bacteria in human gut microbiota. It is not necessarily more difficult to measure antimicrobial activity the traditional way, but it is, however, more laborious. In the present study, we developed a new method to measure the antimicrobial activity of LA in multiple samples with a microplate reader. A "test complex" (TC) was produced consisting of 100 μL of agar medium with LA in the bottom layer and 300 μL of broth in the top layer in 96-well deep-well microplates. Afterward, analysis of the broth in the top layer showed that the antimicrobial activity was the same as that of the "control complex," (CC) which consisted of 100 μL of agar medium in the bottom layer and 300 μL of broth with LA in the top layer. Furthermore, evaluation of the antimicrobial effect of the TC when using a microplate reader was the same as that with the use of the colony counting method. The colony counting method has confirmed that the antimicrobial activity of LA when bacteria are inoculated into the broth was equivalent between CC and TC, and we validated this by correlating the number of bacteria with absorbance. In addition, the broth itself in TC was transparent enough that the turbidity of broth can be used as an index of the number of bacteria, which enabled the use of a microplate reader for multiple samples. For human gut microbes, LA was shown to have low antimicrobial activity against commensal lactic acid bacteria, but high antimicrobial activity against pathogenic Bacteroides and Clostridium, suggesting that LA might modulate intestinal health, as confirmed by the proposed method.

Exome-Wide Rare Loss-of-Function Variant Enrichment Study of 21,347 Han Chinese Individuals Identifies Four Susceptibility Genes for Psoriasis

Most psoriasis-related genes or loci identified by GWAS represent common clusters and are located in noncoding regions of the human genome, providing only limited evidence for the roles of rare coding variants in psoriasis. Two exome-wide case-control genotyping data sets (11,245 cases and 11,177 controls) were obtained from our previous study. Quality controls were established for each data set, and the markers remaining in each set were annotated using ANNOVAR. Gene-based analysis was performed on the annotation results. A total of 250 and 35 genes in the Exome_Fine and Exome_Asian array cohorts, respectively, exceeded the threshold (P < 4.43 × 10^-6). Merged gene-based analysis was then conducted on the same set of SNPs from seven genes common to both arrays, and the chi-square test was used to confirm all gene-based results. Ultimately, four susceptibility genes were identified: BBS7 (P_combine = 1.38 × 10^-29), GSTCD (P_combine = 8.35 × 10^-47), LIPK (P_combine = 1.02 × 10^-19), and PPP4R3B (P_combine = 1.79 × 10^-33). This study identified four susceptibility genes for psoriasis via a gene-based method using rare variants, contributing to our understanding of the pathogenesis of psoriasis.

Azithromycin induces epidermal differentiation and multivesicular bodies in airway epithelia

Background

Azithromycin (Azm) is a macrolide recognized for its disease-modifying effects and reduction in exacerbation of chronic airway diseases. It is not clear whether the beneficial effects of Azm are due to its anti-microbial activity or other pharmacological actions. We have shown that Azm affects the integrity of the bronchial epithelial barrier measured by increased transepithelial electrical resistance. To better understand these effects of Azm on bronchial epithelia we have investigated global changes in gene expression.

Methods

VA10 bronchial epithelial cells were treated with Azm and cultivated in air-liquid interface conditions for up to 22 days. RNA was isolated at days 4, 10 and 22 and analyzed using high-throughput RNA sequencing. qPCR and immunostaining were used to confirm key findings from bioinformatic analyses. Detailed assessment of cellular changes was done using microscopy, followed by characterization of the lipidomic profiles of the multivesicular bodies present.

Results

Bioinformatic analysis revealed that after 10 days of treatment genes encoding effectors of sterol and cholesterol metabolism were prominent. Interestingly, expression of genes associated with epidermal barrier differentiation, KRT1, CRNN, SPINK5 and DSG1, increased significantly at day 22. Together with immunostaining, these results suggest an epidermal differentiation pattern. We also found that Azm induced the formation of multivesicular and lamellar bodies in two different airway epithelial cell lines. Lipidomic analysis revealed that Azm was entrapped in multivesicular bodies linked to different types of lipids, most notably palmitate and stearate. Furthermore, targeted analysis of lipid species showed accumulation of phosphatidylcholines, as well as ceramide derivatives.

Conclusions

Taken together, we demonstrate how Azm might confer its barrier enhancing effects, via activation of epidermal characteristics and changes to intracellular lipid dynamics. These effects of Azm could explain the unexpected clinical benefit observed during Azm-treatment of patients with various lung diseases affecting barrier function.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1101-3) contains supplementary material, which is available to authorized users.

Interactions Between Atopic Dermatitis and Staphylococcus aureus Infection: Clinical Implications

Staphylococcus aureus commonly colonizes the skin of atopic dermatitis (AD) patients and contributes to the development and exacerbation of AD. Multiple factors are associated with colonization of AD skin by S. aureus, including the strength of S. aureus-corneocyte adhesion, deficiency of antimicrobial peptides, decreased levels of filaggrin and filaggrin degradation products, overexpressed Th2/Th17 cytokines, microbial dysbiosis and altered lipid profiles. S. aureus colonization on AD skin causes skin barrier dysfunction through virulence factors such as superantigens (toxins), enzymes and other proteins. Furthermore, colonization of AD skin by S. aureus exacerbates AD and may contribute to microbial dysbiosis, allergen sensitization, Th2/Th17 polarization, development of atopic march and food allergy in AD patients. Skin colonization of S. aureus, particularly methicillin-resistant S. aureus (MRSA), is one of the major challenges commonly encountered in the management of AD. Bleach bath, and topical or systemic antibiotics could be used to control S. aureus infection on AD skin. However, careful use of antibiotics is required to control the occurence of MRSA. Recently, various strategies, including microbiome transplant, monoclonal antibodies against virulent toxins, vaccines and recombinant phage endolysin, have been studied to control S. aureus infection on AD skin. Further advances in our understanding of S. aureus could provide us with ways to manage S. aureus colonization more effectively in AD patients.

Kojyl cinnamate esters are peroxisome proliferator-activated receptor α/γ dual agonists

Adiponectin is an adipocytokine with insulin-sensitizing, anti-inflammatory, anti-atherosclerotic, and anti-aging properties. Compounds with the ability to promote adiponectin secretion are of interest for the development of anti-aging drugs to improve skin-aging phenotypes. In the phenotypic assay to measure adiponectin secretion during adipogenesis in human adipose tissue-derived mesenchymal stem cells (hAT-MSCs), kojyl cinnamate ester derivatives increased adiponectin secretion. A target identification study showed that the kojyl cinnamate ester derivatives competitively bound to peroxisome proliferator-activated receptor α/γ (PPARα/γ). The upregulation of adiponectin production induced by kojyl cinnamate ester derivatives was significantly correlated with PPARα and PPARγ binding activities. Kojyl cinnamate ester derivatives significantly increased the transcription of genes encoding cholesterol and fatty acid synthesizing enzymes in hAT-MSCs. Notably, the kojyl cinnamate esters upregulated the gene transcription of lipid metabolic enzymes in human epidermal keratinocytes, which are important in the integrity of skin permeability barrier. In addition, the kojyl cinnamate esters that function as PPARα/γ dual modulators inhibited ultraviolet B irradiation-induced inflammation in human epidermal keratinocytes. Therefore, kojyl cinnamate ester derivatives are a novel class of PPARα/γ dual agonists with the potential to improve skin-aging phenotypes.

Influence of the sebaceous gland density on the stratum corneum lipidome

The skin surface lipids (SSL) result from the blending of sebaceous and epidermal lipids, which derive from the sebaceous gland (SG) secretion and the permeability barrier of the stratum corneum (SC), respectively. In humans, the composition of the SSL is distinctive of the anatomical distribution of the SG. Thus, the abundance of sebum biomarkers is consistent with the density of the SG. Limited evidence on the influence that the SG exerts on the SC lipidome is available. We explored the differential amounts of sebaceous and epidermal lipids in areas at different SG density with lipidomics approaches. SC was sampled with adhesive patches from forearm, chest, and forehead of 10 healthy adults (8F, 2M) after mechanical removal of sebum with absorbing paper. Lipid extracts of SC were analysed by HPLC/(-)ESI-TOF-MS. In the untargeted approach, the naïve molecular features extraction algorithm was used to extract meaningful entities. Aligned and normalized data were evaluated by univariate and multivariate statistics. Quantitative analysis of free fatty acids (FFA) and cholesterol sulfate (CHS) was performed by targeted HPLC/(-)ESI-TOF-MS, whereas cholesterol and squalene were quantified by GC-MS. Untargeted approaches demonstrated that the relative abundance of numerous lipid species was distinctive of SC depending upon the different SG density. The discriminating species included FFA, CHS, and ceramides. Targeted analyses confirmed that sebaceous FFA and epidermal FFA were increased and decreased, respectively, in areas at high SG density. CHS and squalene, which are biomarkers of epidermal and sebaceous lipid matrices, respectively, were both significantly higher in areas at elevated SG density. Overall, results indicated that the SG secretion intervenes in shaping the lipid composition of the epidermal permeability barrier.

Solvent-Extracted Wool Wax: Thermotropic Properties and Skin Efficacy

BACKGROUND/AIMS

Wool wax is a soft, yellow, waxy substance that is secreted by the sebaceous glands of sheep. The purpose of wool wax is to waterproof and protect the wool. Chemically, wool wax is a complex mixture of esters, fatty acids, and alcohols. Wool waxes with different prop-erties can be obtained by following different extraction methodologies.

METHODS

Two differently extracted wool waxes are compared in this study. Their effectiveness in mimicking the properties of skin lipids is evaluated. In addition, the lipid compositions and thermotropic behaviours of the 2 differently extracted wool waxes were evaluated.

RESULTS

The solvent-extracted wool wax was found to have a significantly higher polar lipid content than that of the water-extracted wool wax. This increase in the polar character of the solvent-extracted wool wax was also demonstrated by increased values of transition and degradation temperatures in the differential scanning calorimetry and thermogravimetric analyses, respectively. In addition, solvent-extracted wool wax demonstrated the ability to reinforce stratum corneum lipids, which led to improved skin barrier function.

CONCLUSIONS

The suitability of the solvent-extracted wool wax for application in the preparation of cosmetics and dermatological products was demonstrated.

Determination of fatty acid and sphingoid base composition of eleven ceramide subclasses in stratum corneum by UHPLC/scheduled-MRM

INTRODUCTION

Ceramides play a key role in skin barrier function in homeostatic and pathological conditions and can be sampled non-invasively through stratum corneum collection.

OBJECTIVES

To develop a novel UHPLC/Scheduled MRM method for the identification and relative distribution of eleven classes of ceramides, which are separated by UHPLC and determined by their specific retention times. The precise composition of the fatty acid and sphingoid base parts of each individual ceramide is determined via mass fragmentation.

METHODS

More than 1000 human and pig ceramides were identified. Three human and minipig ceramide classes, CER[AS], CER[NS] and CER[EOS] have been investigated in depth.

RESULTS

Sphingoid bases were characterized by a prevalence of chain lengths with sizes from C16 to C22, whereas fatty acids were mainly observed in the range of C22-C26. Overall, the ceramide profiles between human and minipig stratum corneum were similar. Differences in the CER[AS] and CER[NS] classes included a more homogeneous distribution of fatty acids (16-30 carbon atoms) in minipig, whereas in human longer fatty acid chains (> 24 carbon atoms) predominated.

CONCLUSION

The method will be useful for the analysis of healthy and pathological skin in various specie, and the measurement of the relative distribution of ceramides as biomarkers for pharmacodynamic studies.

Effect of Torula Yeast (Candida utilis)-Derived Glucosylceramide on Skin Dryness and Other Skin Conditions in Winter

Glucosylceramide (GlcCer) is present in foods such as barley, corn, and wheat flour. GlcCer derived from different foods has differences in its physiological effects, depending on the sphingoid backbone and constituent fatty acids. In this study, we investigated the moisturizing and skin conditioning effects of GlcCer derived from torula yeast (Candida utilis) in healthy human subjects. The participants were randomly distributed in a crossover, double-blind comparative manner. Seventeen volunteers were orally administered both 1.8 mg/d of GlcCer derived from torula yeast and a placebo for 4 wk. Before and after oral administration, transepidermal water loss (TEWL) was measured and the objective skin condition observation and a questionnaire on skin condition were conducted. The primary endpoint was TEWL; secondary endpoints included the objective and subjective skin conditions. The change in TEWL over the study period on the forearm was -0.97±0.48 and -1.26±0.46 g/m2•h in the placebo and GlcCer groups, respectively, with significantly lower (p=0.01) TEWL observed in the GlcCer group. Brown spots increased in the placebo group but significantly decreased in the GlcCer group (p=0.04). Although chapped skin worsened in the placebo group, it significantly improved in the GlcCer group (p=0.04). The use of torula yeast-derived GlcCer as a functional cosmeceutical food is a viable option to ameliorate skin conditions, including improvement in skin barrier function, reduction of brown spots, and fixation of chapped skin.

Decrease of superficial serine and lactate in the stratum corneum due to repetitive frictional trauma

BACKGROUND

Repetitive frictional trauma can be induced in daily and occupational activities, such as daily ablutions with washcloths. The influence of frictional trauma on the skin barrier function, especially in the perspective of the components of stratum corneum (SC), has not yet been studied in detail. Raman spectroscopy is a noninvasive optical technique based on inelastic light scattering that is capable of measuring several components in the skin. In this study, we used Raman spectroscopy to investigate the change in natural moisturizing factor (NMF) components in the SC following repetitive physical friction.

METHODS

Six healthy volunteers, who were included in the study after obtaining an informed consent, performed repetitive washing with soap using nylon towels on the forearm twice a day for 2 weeks and used Raman spectroscopy to investigate the change in NMF components in the SC.

RESULTS

Compared with the control, which was washed with soap at the same frequency on the opposite forearm, a significant increase in the transepidermal water loss (TEWL) and a decrease in NMF, serine, and total lactate, responsible for maintenance the SC hydration and structuring and maintaining the epidermal barrier function, in the SC were found.

CONCLUSIONS

Increased TEWL and decreased NMF are considered as an etiology of atopic dermatitis (AD); therefore, our findings provide evidence that daily activities with repetitive frictional trauma may be related to the predisposition of AD.

Sphingosine-1-Phosphate Receptor 5 Modulates Early-Stage Processes during Fibrogenesis in a Mouse Model of Systemic Sclerosis: A Pilot Study

Systemic sclerosis (SSc) is a rare multi-organ autoimmune disease characterized by progressive skin fibrosis. Inflammation, type 2 immunity, and fibrogenic processes are involved in disease development and may be affected by sphingolipids. However, details about early-stage pathophysiological mechanisms and implicated mediators remain elusive. The sphingolipid sphingosine-1-phosphate (S1P) is elevated in the sera of SSc patients, and its receptor S1P5 is expressed in skin tissue. Nevertheless, almost nothing is known about the dermatological contribution of S1P5 to inflammatory and pro-fibrotic processes leading to the pathological changes seen in SSc. In this study, we observed a novel effect of S1P5 on the inflammatory processes during low-dose bleomycin (BLM)-induced fibrogenesis in murine skin. By comparing 2-week-treated skin areas of wild-type (WT) and S1P5-deficient mice, we found that S1P5 is important for the transcriptional upregulation of the Th2 characteristic transcription factor GATA-3 under treatment-induced inflammatory conditions, while T-bet (Th1) and FoxP3 (Treg) mRNA expression was regulated independently of S1P5. Additionally, treatment caused a regulation of S1P receptor 1 and S1P receptor 3 mRNA as well as a regulation of long-chain ceramide profiles, which both differ significantly between the genotypes. Despite S1P5-dependent differences regarding inflammatory processes, similar macroscopic evidence of fibrosis was detected in the skin histology of WT and S1P5-deficient mice after 4 weeks of subcutaneous BLM treatment. However, at the earlier 2-week point in time, the mRNA data of pro-collagen type 1 and SMAD7 indicate a pro-fibrotic S1P5 contribution in the applied SSc mouse model. In conclusion, we propose that S1P5 plays a role as a novel modulator during the early phase of BLM-caused fibrogenesis in murine skin. An immediate relationship between dermal S1P5 expression and fibrotic processes leading to skin alterations, such as formative for SSc pathogenesis, is indicated but should be studied more profound in further investigations. Therefore, this study is an initial step in understanding the role of S1P5-mediated effects during early stages of fibrogenesis, which may encourage the ongoing search for new therapeutic options for SSc patients.