Efficacy of a Multi-lamellar Emulsion Containing a Synthetic Sphingosine Kinase 1 Activator and Pseudoceramide in Patients with Atopic Dermatitis: A Randomized Controlled Trial

INTRODUCTION

Patients with atopic dermatitis (AD) have impaired barrier function, which decreases skin hydration, weakens their defense against microorganisms, and culminates in increased inflammatory responses. Here, we conducted a clinical trial to evaluate the efficacy of a multi-lamellar emulsion (MLE) containing the pseudoceramide PC-9S and a synthetic sphingosine kinase 1 (SPHK1) activator, Defensamide™, in improving mild-to-moderate atopic dermatitis.

METHODS

Forty patients aged ≥ 2 years were randomized into a combined-therapy group treated with the MLE containing PC-9S and Defensamide™ plus a topical corticosteroid and a topical-corticosteroid-only group. Assessments based on therapeutic methods included the Eczema Area and Severity Index (EASI), the Investigator Global Assessment (IGA), transepidermal water loss (TEWL), stratum corneum hydration (SCH), skin dryness, a visual analogue scale (VAS) of itchiness, a VAS of sleep disturbance, patient satisfaction, and the Dermatology Life Quality Index (DLQI).

RESULTS

Thirty-eight patients completed this study. In the combined-therapy group, significant improvements in clinical and instrumental measures such as EASI scores, skin hydration, and skin dryness were noted at 4 weeks compared to baseline, but such improvements were not noted in the topical corticosteroid-only group. Subjective assessments of itching and sleep disturbance and DLQI scores also showed significant improvements in the combined-therapy group.

CONCLUSION

Combined therapy with the MLE containing Defensamide™ and PC-9S and with topical corticosteroid demonstrated superior clinical outcomes compared with topical corticosteroid monotherapy. Our findings underscore the potential of MLE-containing formulations as effective adjunctive therapies for AD, offering both objective and subjective symptomatic relief and enhancing patients' quality of life.

Short-term effect of a moderate-potency topical corticosteroid on epidermal biophysical parameters in patients with mild-to-moderate atopic dermatitis: A randomised controlled study

Introduction

Skin barrier dysfunction is an important component of atopic dermatitis (AD) pathophysiology. Topical corticosteroids (TCSs) are the mainstay therapy, but steroid phobia is emerging due to potential side effects. We aimed to determine the short-term effect of clobetasone butyrate on patients with AD.

Methods

This investigator-blinded, randomised, moisturiser-controlled study evaluated patients with stable mild-to-moderate AD. Clobetasone butyrate ointment plus aqueous cream (Aq) or Aq alone was applied on randomised sites twice daily for 6 weeks. The itch score, modified Eczema Area and Severity Index (M-EASI) and epidermal biophysical parameters were assessed at baseline and 1 h, 3 h, 2 weeks and 6 weeks after application.

Results

Sixteen patients, among whom 14 (87.5%) were women and two (12.5%) were men, participated in the study. There were no significant differences in pH, transepidermal water loss (TEWL) and hydration between TCS + Aq and Aq from 1 h to 6 weeks. A non-significant trend of pH increment was observed with TCS + Aq from baseline to 6 weeks. TEWL and hydration improved at 6 weeks for both treatment arms. The difference in TEWL from baseline was significant with Aq (P=0.01). The M-EASI at 6 weeks was comparable between the two arms. TCS + Aq improved itch and erythema better than Aq (P=0.02). No cutaneous adverse effects were observed at both sites.

Conclusion

Short-term application of clobetasone butyrate with Aq is safe with no significant changes in epidermal biophysical parameters while controlling the symptoms and signs of eczema faster than Aq alone.

Evaluation of the efficacy and safety of artemether emulsion on localized senile pruritus: A randomized pilot study

BACKGROUND

Localized senile pruritus is a continued health problem for the elderly. This study aimed to evaluate the efficacy and safety of artemether emulsion on localized senile pruritus.

METHODS

Sixty patients diagnosed with senile pruritus were randomized into the artemether emulsion (1%) group or emulsion base group in a 1:1 ratio (the artemether group vs the control group). The patients used artemether emulsion or emulsion base for pruritus twice daily for 2 weeks. The pruritus visual analog scale (VAS) and the rate of adverse events were evaluated in week 0 and week 2.

RESULTS

The VAS scores in week 2 after treatment decreased significantly compared with those before treatment in both groups (P < .05). After treatment, patients receiving the artemether emulsion had significantly lower mean VAS scores compared to those who received the emulsion base (1.21 ± 1.64 vs 3.67 ± 2.97, P < .05). When the VAS scores were compared between the 2 groups before treatment, the effective rate of the artemether group was significantly higher than that of the control group (χ2 = 55, P < .05) in week 2 after treatment. Besides, no adverse events occurred in both groups.

CONCLUSIONS

Both artemether emulsion and emulsion base were effective in treating localized senile pruritus, and artemether emulsion was superior to emulsion base.

Type 2 Inflammation Contributes to Skin Barrier Dysfunction in Atopic Dermatitis

Skin barrier dysfunction, a defining feature of atopic dermatitis (AD), arises from multiple interacting systems. In AD, skin inflammation is caused by host-environment interactions involving keratinocytes as well as tissue-resident immune cells such as type 2 innate lymphoid cells, basophils, mast cells, and T helper type 2 cells, which produce type 2 cytokines, including IL-4, IL-5, IL-13, and IL-31. Type 2 inflammation broadly impacts the expression of genes relevant for barrier function, such as intracellular structural proteins, extracellular lipids, and junctional proteins, and enhances Staphylococcus aureus skin colonization. Systemic anti‒type 2 inflammation therapies may improve dysfunctional skin barrier in AD.

Comparison of Epidermal Barrier Integrity in Adults with Classic Atopic Dermatitis, Atopic Prurigo and Non-Atopic Prurigo Nodularis

A deficient epidermal barrier is a key feature of atopic dermatitis (AD) and comprises altered lipid and protein content and composition of the stratum corneum resulting in disturbed water balance. Clinically, eczematous lesions on dry skin and pruritus develop. Pruritic nodules occur in prurigo nodularis (PN), another chronic skin disease, which can be associated with atopy. We aimed at comparing the three clinical pictures, classic AD, atopic prurigo (AP), and non-atopic PN, to healthy controls regarding the epidermal barrier. We determined clinical parameters and performed biophysical measurements, histology/immunohistochemistry, electron microscopy, and molecular biological analysis. We found distinctively elevated clinical scores, reduced hydration and increased transepidermal water loss, epidermal hyperplasia and inflammation reduced filaggrin and increased loricrin and involucrin expression, as well as reduced intercellular lipid lamellae in all three disease groups. These findings show a severe disruption in epidermal barrier structure and function in all three disorders so that epidermal barrier impairment is now proven not only for AD but also for PN.

Topical Corticosteroids in the Treatment of Vulvar Lichen Sclerosus: A Review of Pharmacokinetics and Recommended Dosing Frequencies

Topical corticosteroids are often utilized as the first-line treatment for vulvar lichen sclerosus (VLS). However, there is wide variability in dosing regimens, as well as a lack of consensus on maintenance dosing. Available guidelines on dosing frequency and regimen continuation for VLS are based on clinical expert opinion and do not necessarily reflect the pharmacokinetics of topical corticosteroids. Over the past few decades, there have been many advances in the techniques used to measure the local and systemic absorption of topical corticosteroids. These techniques have led to a greater understanding of the pharmacokinetics and bioavailabilities of these medications. However, it is not clear how this new information has been applied in evaluating dosing regimens and commonly cited risks when considering short- and long-term use in different vulvar dermatoses. This purpose of this review is to evaluate the available evidence on pharmacokinetics, absorption rates, and concentration levels of topical corticosteroids in lesional and nonlesional skin. Additionally, the evidence regarding commonly cited risks of topical corticosteroid use, including dermal thinning, adrenal suppression, systemic immunosuppression, and tachyphylaxis are reviewed. Differences in the effects of topical corticosteroids on the varied tissues of the vulva are specifically explored. Finally, these considerations are applied to evaluate the current treatment guidelines for VLS to provide direction in determining an evidenced-based dosing regimen and to inform future research in this area. Mautz TT, Krapf JM, Goldstein AT. Topical Corticosteroids in the Treatment of Vulvar Lichen Sclerosus: A Review of Pharmacokinetics and Recommended Dosing Frequencies. Sex Med Rev 2021;XX:XXX-XXX.

Development of Ultradeformable Liposomes with Fatty Acids for Enhanced Dermal Rosmarinic Acid Delivery

This study aimed to develop ultradeformable liposomes (ULs) with fatty acids, namely, oleic, linoleic, and linolenic acid, to improve the skin penetration of rosmarinic acid. This study also investigated the vesicle-skin interaction and skin penetration pathway of ULs with fatty acids using the co-localization technique of multifluorescently labeled particles. The prepared ULs were characterized in terms of size, surface charge, size distribution, shape, % entrapment efficiency (% EE), and % loading efficiency (% LE). The prepared ULs with fatty acids had an average particle size between 50.37 ± 0.3 and 59.82 ± 17.3 nm with a size distribution within an acceptable range and exhibited a negative surface charge. The average % EE and % LE were 9 and 24.02, respectively. The in vitro skin penetration study found that ULs with oleic acid could significantly increase the skin penetration of rosmarinic acid compared to ULs. According to confocal laser scanning microscopy observations, this study suggested that UL vesicles attach to the skin before releasing the entrapped drug to penetrate the skin. These findings suggested that ULs with oleic acid penetrated the skin via the transfollicular pathway as a major penetration pathway.

Pharmacotherapy: Its impact on morphofunctional characteristics of the epidermal barrier

Various pharmaceuticals used for topical and systemic therapy are capable of exerting significant impact on morphological and physiological characteristics of human epidermis, as well as its barrier properties. This may affect the course of dermatologic diseases and the efficacy of their treatment. In this literature review, the author analyzes the impact of various pharmaceutical classes on the morphofunctional characteristics of the epidermal barrier and formulates recommendations for skin disease treatment.

A Randomized, Double-Blind, Placebo-Controlled Trial Assessing the Oral Administration of a Heat-Treated Lactobacillus paracasei Supplement in Infants with Atopic Dermatitis Receiving Topical Corticosteroid Therapy

BACKGROUND/AIMS

Atopic dermatitis (AD) is a common disease in infancy, for which topical steroids are the first-line therapy but have side effects. Innovative approaches are needed to reduce the burden of AD and corticosteroid usage in infants.

METHODS

The once-daily consumption of heat-treated probiotic Lactobacillus paracasei GM-080 or placebo for 16 weeks as supplementary approach to topical treatment with fluticasone propionate cream was compared in AD infants aged 4-30 months. Outcomes were SCORAD and its subscores, TEWL, Infants' Dermatitis Quality of Life Index (IDQOL), corticoid "sparing effect," CCL17/TARC, and IgE status.

RESULTS

SCORAD, objective SCORAD, itching, and IDQOL decreased significantly (p < 0.001) over the treatment period in both treatment groups. Slight decreases (ns) were noted in TEWL in lesional and unaffected skin and CCL17 levels. There were no differences between the treatment groups. Total IgE increased over the treatment period in both groups, with significantly higher increase in the heat-treated probiotic group (p = 0.038). There was no evidence of a corticoid "sparing effect" by the probiotic.

CONCLUSIONS

In this design, the probiotic L. paracasei was not beneficial as a complementary approach to topical corticosteroids in infants with AD. However, slight beneficial effects may have been masked by the moderate potency corticoid.

Impact of topical anti-inflammatory therapy on morpho-functional characteristics of epidermal barrier. Optimization of atopic dermatitis treatment schedules

In this literature review data regarding impact of topical therapy with topical corticosteroids (TCS) and tacrolimus ointment on morpho-functional characteristics of epidermal barrier is analyzed. Whereas TCS has profound negative impact on nearly all epidermal barrier parameters, including epidermal structure and thickness, integrity and cohesion of stratum corneum, protease activity, hydration, pH, differentiation, lipid lamellae structure etc., tacrolimus ointment (Protopic®) exerts positive effect on the majority of the aforementioned parameters, thus allowing to compensate deleterious effect of TCS. These data allow defining recommendations upon optimization of topical therapy of atopic dermatitis with stepwise switching from TCS to Protopic® ointment.

Atopic Dermatitis: Pathophysiology

The pathophysiology of atopic dermatitis is complex and multifactorial, involving elements of barrier dysfunction, alterations in cell mediated immune responses, IgE mediated hypersensitivity, and environmental factors. Loss of function mutations in filaggrin have been implicated in severe atopic dermatitis due to a potential increase in trans-epidermal water loss, pH alterations, and dehydration. Other genetic changes have also been identified which may alter the skin's barrier function, resulting in an atopic dermatitis phenotype. The imbalance of Th2 to Th1 cytokines observed in atopic dermatitis can create alterations in the cell mediated immune responses and can promote IgE mediated hypersensitivity, both of which appear to play a role in the development of atopic dermatitis. One must additionally take into consideration the role of the environment on the causation of atopic dermatitis and the impact of chemicals such as airborne formaldehyde, harsh detergents, fragrances, and preservatives. Use of harsh alkaline detergents in skin care products may also unfavorably alter the skin's pH causing downstream changes in enzyme activity and triggering inflammation. Environmental pollutants can trigger responses from both the innate and adaptive immune pathways. This chapter will discuss the multifaceted etiology of atopic dermatitis which will help us to elucidate potential therapeutic targets. We will also review existing treatment options and their interaction with the complex inflammatory and molecular triggers of atopic dermatitis.

In Vivo Assessment of Clobetasol Propionate-Loaded Lecithin-Chitosan Nanoparticles for Skin Delivery

The aim of this work was to assess in vivo the anti-inflammatory efficacy and tolerability of clobetasol propionate (CP) loaded lecithin/chitosan nanoparticles incorporated into chitosan gel for topical application (CP 0.005%). As a comparison, a commercial cream (CP 0.05% w/w), and a sodium deoxycholate gel (CP 0.05% w/w) were also evaluated. Lecithin/chitosan nanoparticles were prepared by self-assembling of the components obtained by direct injection of soybean lecithin alcoholic solution containing CP into chitosan aqueous solution. Nanoparticles obtained had a particle size around 250 nm, narrow distribution (polydispersity index below 0.2) and positive surface charge, provided by a superficial layer of the cationic polymer. The nanoparticle suspension was then loaded into a chitosan gel, to obtain a final CP concentration of 0.005%. The anti-inflammatory activity was evaluated using carrageenan-induced hind paw edema test on Wistar rats, the effect of formulations on the barrier property of the stratum corneum were determined using transepidermal water loss measurements (TEWL) and histological analysis was performed to evaluate the possible presence of morphological changes. The results obtained indicate that nanoparticle-in-gel formulation produced significantly higher edema inhibition compared to other formulations tested, although it contained ten times less CP. TEWL measurements also revealed that all formulations have no significant disturbance on the barrier function of skin. Furthermore, histological analysis of rat abdominal skin did not show morphological tissue changes nor cell infiltration signs after application of the formulations. Taken together, the present data show that the use of lecithin/chitosan nanoparticles in chitosan gel as a drug carrier significantly improves the risk-benefit ratio as compared with sodium-deoxycholate gel and commercial cream formulations of CP.

The prediction and monitoring of toxicity associated with long-term systemic glucocorticoid therapy

Glucocorticoids are often required for adequate control of inflammation in many serious inflammatory diseases; common indications for long-term treatment include polymyalgia rheumatica, giant cell arteritis, asthma and chronic obstructive pulmonary disease. Long-term glucocorticoid therapy is, however, associated with many adverse effects involving skin, gastro-intestinal, eye, skeletal muscle, bone, adrenal, cardio-metabolic and neuropsychiatric systems. This balance between benefits and risks of glucocorticoids is important for clinical practice and glucocorticoid-related adverse effects can significantly impair health-related quality of life. Understanding the nature and mechanisms of glucocorticoid-related adverse effects may inform how patients are monitored for toxicity and identify those groups, such as older people, that may need closer monitoring. For clinical trials in diseases commonly treated with glucocorticoids, standardised measurement of glucocorticoid-related adverse effects would facilitate future evidence synthesis and meta-analysis.

The effect of tacrolimus compared with betamethasone valerate on the skin barrier in volunteers with quiescent atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is an inflammatory skin disease arising as a result of immune system and skin barrier defects. Topical corticosteroids are safe and effective treatments for AD, when used in short courses. Prolonged use is associated with skin barrier damage. Topical calcineurin inhibitors are alternative immune-modulating treatments for AD purported to have no negative effects on the skin barrier.

OBJECTIVES

To compare the effects of betamethasone valerate 0·1% cream (BMVc) and tacrolimus 0·1% ointment (TACo) on the skin barrier.

METHODS

Twenty volunteers with quiescent AD (no active signs for 6 months) participated in a randomized observer-blind study, wherein BMVc was applied to one forearm and TACo to the other, twice daily for 4 weeks. The biophysical/biological properties of the stratum corneum were assessed before and after treatment. Nine volunteers with active disease and 10 with healthy skin were assessed at untreated sites.

RESULTS

BMVc significantly reduced skin barrier function, integrity and cohesion, and the levels of pyrrolidone carboxylic acid (PCA) and urocanic acid (UCA) towards the subclinical barrier defect observed in patients with AD (nonlesional sites). TACo preserved skin barrier function, integrity, cohesion and PCA and UCA levels, while significantly increasing skin hydration to levels comparable with healthy skin. Both treatments reduced skin surface pH and trypsin-like protease activity, with TACo doing so to a significantly greater degree.

CONCLUSION

In quiescent AD, 4 weeks of BMVc treatment adversely affected the biophysical properties of the skin and reduced the levels of natural moisturizing factor, whereas TACo improved the condition of the skin barrier.

Impaired nuclear translocation of glucocorticoid receptors: novel findings from psoriatic epidermal keratinocytes

Psoriasis is a chronic proliferative skin disease and is usually treated with topical glucocorticoids, which act through the glucocorticoid receptor (GR), a component of the physiological systems essential for immune responses, differentiation, and homeostasis. To investigate the possible role of GR in the pathogenesis of psoriasis, normal and psoriatic lesional skin were recruited. Firstly, the immunolocalization of GR in the skin and cultured epidermal keratinocytes were determined by immunofluorescence. In normal skin and cultured human epidermal keratinocytes, intracellular GR is localized in the nuclei, while in psoriatic skin and cultured keratinocytes, GR is in the cytoplasm. Next, we investigated possible factors associated with the cytoplasmic distribution. We found that VEGF and IFN-γ led to impaired nuclear translocation of GR through p53 and microtubule-inhibitor, vincristine, and inhibited nuclear uptake of GR in normal keratinocytes. In addition to dexamethasone, interleukin (IL)-13 was also able to transfer GR into nuclei of psoriatic keratinocytes. Furthermore, discontinuation of dexamethasone induced cytoplasmic retention of GR in normal keratinocytes. In contrast, energy depletion of normal epidermal keratinocytes did not change the nuclear distribution of GR. To confirm our findings in vivo, an imiquimod-induced psoriasis-like skin mouse model was included. IL-13 ameliorated (but vincristine exacerbated) the skin lesions on the mouse. Taken together, our findings define that impaired nuclear translocation of GR is associated with VEGF, IFN-γ, p53, and microtubule. Therapeutic strategies designed to accumulate GR in the nucleus, such as IL-13, may be beneficial for the therapy of psoriasis.

Lidocaine inhibits staphylococcal enterotoxin-stimulated activation of peripheral blood mononuclear cells from patients with atopic dermatitis

Atopic dermatitis (AD) is an inflammatory, chronically relapsing, pruritic skin disease and lesions associated with AD are frequently colonized with Staphylococcus aureus (S. aureus). Activation of T cells by staphylococcal enterotoxins (SE) plays a crucial role in the pathogenesis of AD. Previous studies have demonstrated that lidocaine could attenuate allergen-induced T cell proliferation and cytokine production in peripheral blood mononuclear cells (PBMCs) from asthma patients. The purpose of this study was to investigate the effects of lidocaine on SE-stimulated activation of PBMCs from AD patients. PBMCs were isolated from ten AD patients and stimulated by staphylococcal enterotoxin A (SEA) or staphylococcal enterotoxin B (SEB) in the presence or absence of lidocaine in various concentrations. Cellular proliferation and the release of representative TH1- and TH2-type cytokines were measured. The effect of lidocaine on filaggrin (FLG) expression in HaCaT cells co-cultured with SE-activated PBMCs was also examined. Our results demonstrated that lidocaine dose-dependently inhibited the proliferative response and the release of IL-4, IL-5, IL-13, TNF-α, and IFN-γ from SEA- and SEB-stimulated PBMCs and also blocked the down-regulation of FLG expression in HaCaT cells co-cultured with SEA- and SEB-activated PBMCs. These results indicate that lidocaine inhibited SEA- and SEB-stimulated activation of PBMCs from patients with AD. Our findings encourage the use of lidocaine in the treatment of AD.

Preventive effects of multi-lamellar emulsion on low potency topical steroid induced local adverse effect

Background

Topical steroid treatment induces diverse local Wand systemic adverse effects. Several approaches have been tried to reduce the steroid-induced adverse effects. Simultaneous application of physiological lipid mixture is also suggested.

Objective

Novel vehicles for topical glucocorticoids formulation were evaluated for the efficacy of reducing side-effects and the drug delivery properties of desonide, a low potency topical steroid.

Methods

Transcutaneous permeation and skin residual amount of desonide were measured using Franz diffusion cells. The in vivo anti-inflammatory activity was evaluated using murine model.

Results

Topical steroids formulation containing desonide, in either cream or lotion form, were prepared using multi-lamellar emulsion (MLE), and conventional desonide formulations were employed for comparison. MLE formulations did not affect the anti-inflammatory activity of the desonide in phobol ester-induced skin inflammation model, compared with conventional formulations. While the penetrated amounts of desonide were similar for all the tested formulations at 24 hours after application, the increased lag time was observed for the MLE formulations. Interestingly, residual amount of desonide in epidermis was significantly higher in lotion type MLE formulation. Steroid-induced adverse effects, including permeability barrier function impairment, were partially prevented by MLE formulation.

Conclusion

Topical desonide formulation using MLE as a vehicle showed a better drug delivery with increased epidermal retention. MLE also partially prevented the steroid-induced side effects, such as skin barrier impairment.

Epidermal barrier function and systemic diseases

The skin is a vital organ for life and, among its many functions, the role as a protective barrier is one of the most important. It is the main boundary between the body and the external environment. As defensive barrier, the epidermis protects internal organs from physical and chemical trauma, microorganism invasion, and ultraviolet radiation. It also acts in the regulation of transepidermal movement of water and electrolytes, and in preventing dehydration, all of which are essential for sustaining life. The main role is allotted to the stratum corneum and to the lipid matrix located in the intercellular space. The occurrence of dysfunction in the epidermal barrier is an important factor in the physiopathogenesis of skin diseases, particularly atopic dermatitis and psoriasis. There are few, but important, systemic changes that influence or are influenced by dysfunctions in the epidermal barrier. We review the effects of some systemic diseases on the maintenance of the skin's homeostasis.

Regulation of permeability barrier homeostasis

A major function of the skin is to provide a barrier to the movement of water and electrolytes, which is required for life in a terrestrial environment. This permeability barrier is localized to the stratum corneum and is mediated by extracellular lipid-enriched lamellar membranes, which are delivered to the extracellular spaces by the secretion of lamellar bodies by stratum granulosum cells. A large number of factors have been shown to regulate the formation of this permeability barrier. Specifically, lamellar body secretion and permeability barrier formation are accelerated by decreases in the calcium content in the stratum granulosum layer of the epidermis. In addition, increased expression of cytokines and growth factors and the activation of nuclear hormone receptors (peroxisome proliferator-activated receptors, liver X receptors, vitamin D receptor) accelerate permeability barrier formation. In contrast, nitric oxide, protease-activated receptor 2 activation, glucocorticoids, and testosterone inhibit permeability barrier formation. The ability of a variety of factors to regulate permeability barrier formation allows for a more precise and nuanced regulation.

Evaluation of the atrophogenic potential of hydrocortisone 1% cream and pimecrolimus 1% cream in uninvolved forehead skin of patients with atopic dermatitis using optical coherence tomography

Topical corticosteroids are widely used to treat atopic dermatitis (AD), but their anti-inflammatory mode of action can be accompanied by several unwanted side effects including skin atrophy and telangiectasia. In this 8-week, investigator-blinded, intraindividual right-left comparison study with patients with mild-to-moderate AD, hydrocortisone 1% cream (HCT) was applied twice daily for 4 weeks on one side of forehead skin without clinical signs of AD and pimecrolimus 1% cream (PIM) on the other. Epidermal and dermal thickness were assessed by optical coherence tomography (OCT) and high-frequency ultrasound, respectively. Skin atrophy and telangiectasia were assessed by contact dermatoscopic photography (Dermaphot(®)). Treatment with HCT leads to a significant decrease in epidermal thickness after only 2 weeks of treatment, while the decrease in PIM-treated sites was less pronounced and was not statistically significant. By 4 weeks after the end of treatment, epidermal thickness returned to baseline values. No dermal thinning or development of telangiectasia could be observed by means of ultrasound or Dermaphot(®), respectively. In summary, this study indicates that a 2-week single course of topical treatment with a mildly potent steroid can cause transient epidermal thinning, an effect not seen in the PIM group. The slight decrease with PIM - although not significant - could be due to normalization of the increased skin thickness caused by a subclinical inflammation in AD. This study suggests that PIM may be safer for treatment of AD in sensitive skin areas like the face, especially when repeated application is required.

Pseudoceramide-containing physiological lipid mixture reduces adverse effects of topical steroids

PURPOSE

Various therapeutic approaches have been suggested for preventing or reducing the adverse effects of topical glucocorticoids, including skin barrier impairment. Previously, we have shown that impairment of skin barrier function by the highest potency topical glucocorticoid, clobetasol 17-propinate (CP), can be partially prevented by co-application of a physiological lipid mixture containing pseudoceramide, free fatty acids, and cholesterol (multi-lamellar emulsion [MLE]). Skin atrophic effects of CP were also partially reduced by MLE. In this study, the preventive effects of MLE on the lowest potency topical glucocorticoid, hydrocortisone (HC), were investigated using animal models.

METHODS

Anti-inflammatory activity of topical HC was evaluated using a 12-O-tetradecanoylphobol-13-acetate-induced skin edema model. Topical steroid induced adverse effects were evaluated using hairless mouse.

RESULTS

The results showed that the anti-inflammatory activity was not altered by co-application of either MLE or hydrobase. However, co-application of MLE and 1.0% HC showed less impairment in the epidermal permeability barrier function, skin hydration, and skin surface pH compared with hydrobase. Stratum corneum integrity, evaluated by measuring trans-epidermal water loss after repeated tape stripping, showed less damage with MLE co-application. Long-term application of topical HC induced skin atrophy, measured by a reduction in skinfold and epidermal thickness and in the number of epidermal proliferating cell nucleus antigen (PCNA)-positive keratinocytes. Co-application of MLE did not affect the skinfold or epidermal thickness, but the number of PCNA-positive keratinocytes was less decreased with MLE use.

CONCLUSIONS

These results suggest that co-application of MLE is effective in reducing the local adverse effects of low-potency topical glucocorticoids and supports the therapeutic efficacy of physiological lipid mixtures on skin barrier function.

Topical calcineurin inhibitors compromise stratum corneum integrity, epidermal permeability and antimicrobial barrier function

BACKGROUND

Topical calcineurin inhibitors (TCIs) such as pimecrolimus and tacrolimus have recently been used for dermatologic diseases including atopic dermatitis instead of topical glucocorticoids, because they display comparable efficacy, but less-frequent side effects. Although even short-term topical glucocorticoid compromise epidermal permeability barrier homeostasis, the effects of TCI on barrier function have not yet been reported. However, viral infections such as eczema herpeticum and molluscum contagiosum, which could indicate an impaired skin barrier, continue to occur with TCI use in atopic dermatitis.

OBJECTIVES

We determined here whether TCIs disrupt epidermal permeability barrier and antimicrobial function, and whether these effects can be prevented.

METHODS AND RESULTS

In normal humans, topical pimecrolimus and tacrolimus applied twice-daily for 5 days, delay barrier recovery without an increase in basal transepidermal water loss was observed. Co-application of physiologic lipid mixture (PLM) containing an equimolar ratio of ceramides, cholesterol and free fatty acids normalized barrier homeostasis in the face of topical TCIs. In hairless mice, 4 days of TCI treatment also disrupted barrier function significantly. TCIs-treated epidermis showed the decrease of epidermal lipid content, lamellar body number and secretion, and lipid synthesis-related enzymes such as 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, serine-palmitoyl transferase and fatty acid synthase, implying decreased lipid synthesis. TCIs also suppressed expression of IL-1alpha and antimicrobial peptides, CRAMP and mouse beta-defensin 3. However, these TCI-induced abnormalities can be overridden by topical replacement with PLM.

CONCLUSIONS

Our results demonstrate that TCIs induce negative effects on the skin barrier including permeability and antimicrobial functions, which are mediated by decreasing epidermal lipid synthesis, lamellar body secretion and antimicrobial peptides expression through suppression of cytokine such as IL-1alpha, therefore co-treatment with PLM would be helpful to overcome these negative effects.

Epidermal barrier dysfunction in atopic dermatitis

Atopic dermatitis (AD) is a multifactorial, heterogenous disease that arises as a result of the interaction between both environmental and genetic factors. Changes in at least three groups of genes encoding structural proteins, epidermal proteases, and protease inhibitors predispose to a defective epidermal barrier and increase the risk of developing AD. Loss-of-function mutations found within the FLG gene encoding the structural protein, filaggrin, represent the most significant genetic factor predisposing to AD identified to date. Enhanced protease activity and decreased synthesis of the lipid lamellae lead to exacerbated breakdown of the epidermal barrier. Environmental factors, including the use of soap and detergents, exacerbate epidermal barrier breakdown, attributed to the elevation of stratum corneum pH. A sustained increase in pH enhances the activity of degradatory proteases and decreases the activity of the lipid synthesis enzymes. The strong association between both genetic barrier defects and environmental insults to the barrier with AD suggests that epidermal barrier dysfunction is a primary event in the development of this disease. Our understanding of gene-environment interactions should lead to a better use of some topical products, avoidance of others, and the increased use and development of products that can repair the skin barrier.

Activators of PPARs and LXR decrease the adverse effects of exogenous glucocorticoids on the epidermis

While glucocorticoids (GC) exert beneficial effects (anti-inflammatory), they also have adverse effects on the epidermis including decreased epidermal differentiation, decreased keratinocyte proliferation, and decreased cutaneous permeability barrier homeostasis. Thus, the purpose of this study was to develop strategies to prevent these GC toxicities using simultaneous topical treatments in clobetasol-treated mice. While a triple-lipid mixture of stratum corneum lipids (ceramide, free fatty acid and cholesterol) was previously shown to reverse the GC-induced abnormality in cutaneous barrier function [J Invest Dermatol, 120 (2003) 456], this lipid mixture did not prevent the GC-induced abnormalities in either keratinocyte proliferation or differentiation. As activators of PPARalpha, beta/delta, gamma and LXR, regulate keratinocyte proliferation and differentiation and improve permeability barrier homeostasis, we next assessed the effects of these activators during concurrent GC treatment. Co-application of either ciglitazone (PPARgamma activator), clofibrate (PPARalpha activator) or 22R (OH) cholesterol (LXR activator) with clobetasol prevented the decrease in involucrin, filaggrin and loricrin expression. By contrast, a PPARbeta/delta activator (GW501516) normalized only the expression of involucrin and filaggrin but not loricrin. Moreover, topical application of PPARalpha, beta/delta or LXR activators partially prevented the decrease in keratinocyte proliferation in GC-treated murine skin, as measured using PCNA, while no effect was seen after co-treatment with PPARgamma activators. Finally, PPARgamma and PPARbeta/delta activators but not PPARalpha and LXR activators improved permeability barrier homeostasis in GC-treated mice. Together, these studies demonstrate that PPAR and LXR activators can prevent several of the adverse effects of topical GC on the epidermis.

The epidermal barrier in atopic dermatitis

Epidermal barrier function is abnormal in individuals with atopic dermatitis (AD). It is controversial whether primary epidermal barrier abnormalities alone account for the physiological and clinical abnormalities found in those persons with AD or whether the observed barrier dysfunction is a consequence of primary immunologic abnormalities. Recent evidence is strengthening the argument for the former hypothesis. Attention to epidermal barrier care (ie, gentle skin care) has long been an important part of the therapy of AD. Advances in our understanding of the biology of the epidermal barrier and how this relates to the clinical manifestations of this disease has important consequences for new therapeutic approaches in the management of AD.

The treatment of facial atopic dermatitis in children who are intolerant of, or dependent on, topical corticosteroids: a randomized, controlled clinical trial

BACKGROUND

Atopic dermatitis (AD) is most prevalent in areas of reduced skin barrier reserve, like face and neck, especially in children. Treatment with topical corticosteroids (TCS) is limited due to heightened risk of treatment-associated side-effects, thus necessitating alternative AD therapies.

OBJECTIVES

The primary study objective was to determine the efficacy of pimecrolimus cream 1% in children with mild-moderate facial AD dependent on/intolerant of TCS. Secondary objectives included effects on overall Eczema Area and Severity Index (EASI), head/neck EASI, pruritus severity and time to clearance of facial AD.

METHODS

A multicentre, double-blind (DB) study of < or = 6 weeks, followed by a 6-week, open-label (OL) phase was conducted. Two hundred patients (aged 2-11 years) were randomized 1:1 to pimecrolimus cream 1% (n = 99) or vehicle (n = 101) twice daily until clearance of facial AD or for a maximum of 6 weeks (DB phase). Sixteen patients receiving vehicle were allowed to switch to the OL phase at day 22.

RESULTS

Significantly more pimecrolimus-treated vs. vehicle-treated patients were cleared/almost cleared of facial AD (Investigators' Global Assessment 0/1): 74.5% vs. 51.0%, P < 0.001 (day 43) [57.1% vs. 36.0%, P = 0.004 (day 22)]. Median time to clearance was 22.0 vs. 43.0 days (pimecrolimus vs. vehicle, respectively). Statistically significant differences for pimecrolimus vs. vehicle were also seen on head/neck EASI, overall EASI, and head/neck pruritus scores. Adverse events were mainly mild-moderate, occurring with similar frequency in both treatment groups.

CONCLUSIONS

In children with facial dermatitis intolerant of/dependent on TCS, pimecrolimus cream 1% effectively controls eczema and pruritus and is well tolerated.

Comparison of the effect of glycerol and triamcinolone acetonide on cumulative skin irritation in a randomized trial

BACKGROUND

So-called anti-irritants are added to cosmetic formulations because of their alleged beneficial effect on irritated skin. Documentation for these claims is often limited. However, glycerol has shown anti-irritant properties in experimentally induced irritation from sodium lauryl sulfate and nonanoic acid (NON). This study was designed to further substantiate that glycerol added to cosmetic formulations has an anti-irritant effect on experimentally induced skin irritation.

OBJECTIVE

We sought to compare glycerol with triamcinolone acetonide as treatments for cutaneous irritation in human volunteers.

METHODS

Irritation was induced by 3 daily arm washes for a week with 10% sodium lauryl sulfate on one arm and 30% NON on the other. To maintain irritation, for the next 12 days volunteers washed their arms twice daily with the irritants. Treatments were applied immediately after washing. The treatments (including vehicle and no treatment) were randomized to sites using a Latin square design. The reactions were evaluated clinically and instrumentally.

LIMITATIONS

Study was designed to only detect potent anti-irritants.

CONCLUSION

Glycerol reduced the irritant effect of both sodium lauryl sulfate and NON, whereas triamcinolone acetonide appeared to have beneficial effect only on the irritation induced by NON. The study provided experimental documentation for the claim that glycerol has anti-irritant effect in a cosmetic formulation.

Glucocorticoid blockade reverses psychological stress-induced abnormalities in epidermal structure and function

Many cutaneous disorders are adversely affected by psychological stress (PS), but the responsible mechanisms are poorly understood. Recent studies have demonstrated that PS decreases epidermal proliferation and differentiation, impairs permeability barrier homeostasis, and decreases stratum corneum integrity. PS also increases the production of endogenous glucocorticoids (GC), and both systemic and topical GC cause adverse effects on epidermal structure and function similar to those observed with PS. We therefore hypothesized that increased endogenous GC in PS mediates its adverse cutaneous effects. To test this hypothesis, we used two independent approaches, administering either RU-486, a GC receptor antagonist that inhibits GC action, or antalarmin, a corticotropin-releasing hormone (CRH) receptor antagonist that prevents increased GC production in the face of PS. Inhibition of either GC action or production prevents the PS-induced decline in epidermal cell proliferation and differentiation, impairment in permeability barrier homeostasis, and decrease in stratum corneum (SC) integrity. Moreover, the pathophysiological basis for the abnormality in permeability barrier homeostasis; i.e., decreased lamellar body production and secretion, is restored toward normal by inhibition of GC action. Similarly, the mechanistic basis for the decrease in SC integrity, i.e., a reduction in corneodesmosomes, is also normalized by inhibition of GC action. Thus many of the adverse effects of PS on epidermal structure and function can be attributed to increased endogenous GC and conversely, approaches that either reduce GC production or action might benefit cutaneous disorders that are provoked or exacerbated by PS.

Adverse effects of topical glucocorticosteroids

Topical corticosteroids were introduced into medicine about 50 years ago. They represent a significant milestone in dermatologic therapy. Despite encouragement to report observed adverse drug reactions, the clinical practice of reporting is poor and incomplete. Likewise, adverse effects and safety of topical corticosteroids are neglected in the medical literature. The authors provide an updated review of their adverse-effect profile. Children are more prone to the development of systemic reactions to topically applied medication because of their higher ratio of total body surface area to body weight. Cutaneous adverse effects occur regularly with prolonged treatment and are dependent on the chemical nature of the drug, the vehicle, and the location of its application. The most frequent adverse effects include atrophy, striae, rosacea, perioral dermatitis, acne, and purpura. Those that occur with lower frequency include hypertrichosis, pigmentation alterations, delayed wound healing, and exacerbation of skin infections. Of particular interest is the rate of contact sensitization against corticosteroids, which is considerably higher than generally believed. Systemic reactions such as hyperglycemia, glaucoma, and adrenal insufficiency have also been reported to follow topical application. The authors provide an updated review of local and systemic adverse effects upon administration of topical corticosteroids, including the latest FDA report on the safety of such steroids in children.

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be familiar with topical corticosteroids and their proper use.

Blockade of experimental atopic dermatitis via topical NF-kappaB decoy oligonucleotide

Atopic dermatitis (AD) is a common chronic skin inflammatory disease. Long-term use of topical corticosteroids in skin inflammation poses risks of systemic and local side effects. The NF-kappaB transcription factor family plays a central role in the progression and maintenance of AD. This study explores the possibility of using topical NF-kappaB Decoy as a novel therapeutic alternative for targeting Th1/Th2-driven skin inflammation in experimental AD. A high-affinity, topical NF-kappaB Decoy developed for human efficacy demonstrates: (i) efficient NF-kappaB Decoy penetration in pig skin, (ii) NF-kappaB Decoy nuclear localization in keratinocytes and key immune cells, and (iii) potent "steroid-like" efficacy in a chronic dust-mite antigen skin inflammation treatment model. NF-kappaB Decoy exerts its anti-inflammatory action through the effective inhibition of essential regulators of inflammation and by induction of apoptosis of key immune cells. Unlike betamethasone valerate (BMV), long-term NF-kappaB Decoy treatment does not induce skin atrophy. Moreover, topical NF-kappaB Decoy, in contrast to BMV, restores compromised stratum corneum integrity and barrier function. Steroid withdrawal causes rapid rebound of inflammation, while the NF-kappaB Decoy therapeutic benefit was maintained for weeks. Thus, topical NF-kappaB Decoy provides a novel mechanism of reducing chronic skin inflammation with improved skin homeostasis and minimal side effects.

Mechanisms by Which Psychologic Stress Alters Cutaneous Permeability Barrier Homeostasis and Stratum Corneum Integrity

Although many skin disorders, including psoriasis and atopic dermatitis, are adversely affected by psychologic stress (PS), the pathophysiologic link between PS and disease expression remains unclear. Recent studies demonstrated PS-induced alterations in permeability barrier homeostasis, mediated by increased endogenous glucocorticoids. Here, we assessed the mechanisms by which PS alters stratum corneum (SC) function. Insomniac psychologic stress (IPS) altered both barrier homeostasis and SC integrity. IPS decreased epidermal cell proliferation, impaired epidermal differentiation, and decreased the density and size of corneodesmosomes (CD), which was linked to degradation of CD proteins (e.g., desmoglein1). Barrier compromise was linked to decreased production and secretion of lamellar bodies (LB), which in turn could be attributed to a decrease in de novo synthesis of epidermal lipids. Topical physiologic lipids (equimolar cholesterol, ceramides, and free fatty acids) normalized both barrier homeostasis and SC integrity in IPS mice, further evidence that lipid deficiency accounted for these functional abnormalities. Thus, PS inhibition of epidermal lipid synthesis results in decreased LB formation and secretion, as well as decreased CD, compromising both permeability barrier homeostasis and SC integrity. These studies suggest that topical treatment with epidermal physiologic lipids could be beneficial in stress-induced, barrier-associated dermatoses, such as psoriasis and atopic dermatitis.

Lipid vesicles and other colloids as drug carriers on the skin

Colloids from an aqueous suspension can cross the skin barrier only through hydrophilic pathways. Various colloids have a different ability to do this by penetrating narrow pores of fixed size in the skin, or the relevant nano-pores in barriers modelling the skin. Such ability is governed by colloid adaptability, which must be high enough to allow penetrant deformation to the size of a pore in such barrier: for a 100 nm colloid trespassing the skin this means at least 5-fold deformation/elongation. (Lipid) Bilayer vesicles are normally more adaptable than the comparably large (lipid coated) fluid droplets. One of the reasons for this, and an essential condition for achieving a high bilayer adaptability and pore penetration, is a high bilayer membrane elasticity. The other reason is the relaxation of changing colloid's volume-to-surface constraint during pore penetration; it stands to reason that such relaxation requires a concurrent, but only transient and local, bilayer permeabilisation. Both these phenomena are reflected in bilayer composition sensitivity, which implies non-linear pressure dependency of the apparent barrier penetrability, for example. Amphipats that acceptably weaken a membrane (surfactants, (co)solvents, such as certain alcohols, etc.) consequently facilitate controlled, local bilayer destabilisation and increase lipid bilayer flexibility. When used in the right quantity, such additives thus lower the energetic expense for elastic bilayer deformation, associated with pore penetration. Another prerequisite for aggregate transport through the skin is the colloid-induced opening of the originally very narrow ( approximately 0.4 nm) gaps between cells in the barrier to pores with diameter above 30 nm. Colloids incapable of enforcing such widening-and simultaneously of self-adapting to the size of 20-30 nm without destruction-are confined to the skin surface. All relatively compact colloids seem to fall in this latter category. This includes mixed lipid micelles, solid (nano)particles, nano-droplets, biphasic vesicles, etc. Such colloids, therefore, merely enter the skin through the rare wide gaps between groups of skin cells near the organ surface. Transdermal drug delivery systems based on corresponding drug formulations, therefore, rely on simple drug diffusion through the skin; the colloid then, at best, can modulate drug transport through the barrier. In contrast, the adaptability-and stability-optimised mixed lipid vesicles (Transfersomes, a trademark of IDEA AG) can trespass much narrower pathways between most cells in the skin; such highly adaptable colloids thus mediate drug transport through the skin. Sufficiently stable ultra-adaptable carriers, therefore, can ensure targeted drug delivery deep below the application site. This has already been shown in numerous preclinical tests and several phase I and phase II clinical studies. Drug delivery by means of highly adaptable drug carriers, moreover, allows highly efficient and well-tolerated drug targeting into the skin proper. Sustained drug release through the skin into systemic blood circulation is another field of ultradeformable drug carrier application.

Short-term glucocorticoid treatment compromises both permeability barrier homeostasis and stratum corneum integrity: inhibition of epidermal lipid synthesis accounts for functional abnormalities

Prolonged exposure of human epidermis to excess endogenous or exogenous glucocorticoids can result in well-recognized cutaneous abnormalities. Here, we determined whether short-term glucocorticoid treatment would also display adverse effects, specifically on two key epidermal functions, permeability barrier homeostasis and stratum corneum integrity and cohesion, and the basis for such changes. In humans 3 d of treatment with a potent, commonly employed topical glucocorticoid (clobetasol), applied topically, produced a deterioration in barrier homeostasis, characterized by delayed barrier recovery and abnormal stratum corneum integrity (rate of barrier disruption with tape strippings) and stratum corneum cohesion (microg protein removed per stripping). Short-term systemic and topical glucocorticoid produced similar functional defects in mice, where the basis for these abnormalities was explored further. Both the production and secretion of lamellar bodies were profoundly decreased in topical glucocorticoid-treated mice resulting in decreased extracellular lamellar bilayers. These structural changes, in turn, were attributable to a profound global inhibition of lipid synthesis, demonstrated both in epidermis and in cultured human keratinocytes. The basis for the abnormality in stratum corneum integrity and cohesion was a diminution in the density of corneodesmosomes in the lower stratum corneum. We next performed topical replacement studies to determine whether lipid deficiency accounts for the glucocorticoid-induced functional abnormalities. The abnormalities in both permeability barrier homeostasis and stratum corneum integrity were corrected by topical applications of an equimolar distribution of free fatty acids, cholesterol, and ceramides, indicating that glucocorticoid-induced inhibition of epidermal lipid synthesis accounts for the derangements in both cutaneous barrier function and stratum corneum integrity/cohesion. These studies indicate that even short-term exposure to potent glucocorticosteroids can exert profound negative effects on cutaneous structure and function. Finally, topical replenishment with epidermal physiologic lipids could represent a potential method to reduce the adverse cutaneous effects of both topical glucocorticoid treatment and Cushing's syndrome.

Stress-induced changes in skin barrier function in healthy women

Despite clear exacerbation of several skin disorders by stress, the effect of psychologic or exertional stress on human skin has not been well studied. We investigated the effect of three different stressors, psychologic interview stress, sleep deprivation, and exercise, on several dermatologic measures: transepidermal water loss, recovery of skin barrier function after tape stripping, and stratum corneum water content (skin conductance). We simultaneously measured the effects of stress on plasma levels of several stress-response hormones and cytokines, natural killer cell activity, and absolute numbers of peripheral blood leukocytes. Twenty-five women participated in a laboratory psychologic interview stress, 11 women participated in one night of sleep deprivation, and 10 women participated in a 3 d exercise protocol. The interview stress caused a delay in the recovery of skin barrier function, as well as increases in plasma cortisol, norepinephrine, interleukin-1beta and interleukin-10, tumor necrosis factor-alpha, and an increase in circulating natural killer cell activity and natural killer cell number. Sleep deprivation also decreased skin barrier function recovery and increased plasma interleukin-1beta, tumor necrosis factor-alpha, and natural killer cell activity. The exercise stress did not affect skin barrier function recovery, but caused an increase in natural killer cell activity and circulating numbers of both cytolytic T lymphocytes and helper T cells. In addition, cytokine responses to the interview stress were inversely correlated with changes in barrier function recovery. These results suggest that acute psychosocial and sleep deprivation stress disrupts skin barrier function homeostasis in women, and that this disruption may be related to stress-induced changes in cytokine secretion.

Stress alters cutaneous permeability barrier homeostasis

Recent studies have shown that psychological stress can influence cutaneous barrier function, suggesting that this form of stress could trigger or aggravate skin disease. In the present study, we demonstrate that transfer of hairless mice to a different cage delays barrier recovery rates. Pretreatment with a phenothiazine sedative, chlorpromazine, before transfer of animals restored the kinetics of barrier recovery toward normal, suggesting that psychological stress is the basis for this alteration in barrier homeostasis. To determine the mechanism linking psychological stress to altered barrier recovery, we first demonstrated that plasma corticosterone levels increase markedly after transfer of animals to new cages and that pretreatment with chlorpromazine blocks this increase. Second, we demonstrated that the systemic administration of corticosterone delays barrier recovery. Finally, we demonstrated that pretreatment with the glucocorticoid receptor antagonist RU-486 blocks the delay in barrier recovery produced by systemic corticosterone, change of cage, or immobilization. These results suggest that psychological stress stimulates increased production of glucocorticoids, which, in turn, adversely affects permeability barrier homeostasis.

Human skin surface lipid film: an ultrastructural study and interaction with corneocytes and intercellular lipid lamellae of the stratum corneum

Sebum is a complex mixture of lipids, which is secreted by mammalian sebaceous glands, and forms a fluid film over the skin surface. After sebum is secreted, it becomes mixed with lipid from the keratinizing epithelium and forms the skin surface lipid film (SSLF). Until now, direct fine structural observation of the SSLF has been lacking. In the present work, we viewed the detailed structures of the human SSLF by ruthenium tetroxide staining. The results showed that the SSLF formed an amorphous sheet of variable thickness on the skin surface instead of forming lipid droplets, as had been the usual assumption. In general, its thickness was < 0.5 microm or even negligible in sebum-poor extremities. However, in the sebum-rich face, its thickness was > 4 microm in focal areas. Consistent with the thickness of SSLF, the sebum quantity showed great regional variation. It varied from 1 microg/cm2 (leg) to 189 +/- 42.7 microg/cm2 (mean +/- SD: face). The SSLF was composed of numerous fine granules of about 4-5 nm in a random orientation. Within the SSLF, variable amounts of deranged lipid lamellae derived from corneocytes were mixed with sebum. As well as on the skin surface, a similar amount of sebum was also found between the desquamating corneocytes in the uppermost several layers of the stratum corneum (SC). We also observed the presence of intercellular lipid lamellae in the outer layers of the SC: their lipid envelope remained intact even in desquamated corneocytes. Our results provide some new insights concerning the structure of the SSLF and its relationship with the SC.

Permeability barrier abnormality of hairless mouse epidermis after topical corticosteroid: characterization of stratum corneum lipids by ruthenium tetroxide staining and high-performance thin-layer chromatography

Topical corticosteroids (TCS) are among the most frequently used topical therapeutics. Recently, it has been shown that TCS not only has antiproliferative actions, but also inhibits the differentiation of the epidermis and finally perturbates stratum corneum (s.c.) barrier function. It is well established that epidermal barrier function resides within the intercellular lipids of the SC. However, to date, little is known about the effects of TCS on the structure and composition of s.c. lipids. We therefore used hairless mouse skin to study the sequential changes of the s.c. permeability barrier and their intercellular lipids by ruthenium tetroxide staining and high-performance thin-layer chromatography (HPTLC) during topical use of corticosteroids. The results demonstrated a progressive increase in transepidermal water loss accompanied by a diminution in the SC intercellular lipid lamellae, which showed a normal structure of individual lamella. Analysis of lipid composition by HPTLC after a 6-week application of TCS also showed an obvious decrease in all the main components of s.c. lipids, which are known to constitute the permeability barrier of the skin. In light of these results, our work provides direct morphological evidence that TCS deteriorates the permeability barrier of epidermis when applied to normal skin.