Effect of lactic acid isomers on keratinocyte ceramide synthesis, stratum corneum lipid levels and stratum corneum barrier function

Lactic Acid Chemical Peeling in Skin Disorders

Lactic acid is the most widely occurring natural organic acid in nature. It not only exhibits mild and safe properties but also possesses multiple physiological activities, such as antibacterial effects, immune regulation, and promotion of wound healing, making it one of the most popular chemical peeling agents. Chemical peels are commonly used in the field of aesthetic dermatology as a non-invasive therapeutic approach. This research aims to provide valuable references for clinical dermatologists by summarizing the characteristics of lactic acid, elucidating its mechanism of action in peeling, and investigating the clinical applications of this compound. Furthermore, it anticipates the potential for lactic acid to be the most suitable chemical peeling agent for Chinese skin.

The Skin Barrier and Moisturization: Function, Disruption, and Mechanisms of Repair

BACKGROUND

The anatomic layers of the skin are well-defined, and a functional model of the skin barrier has recently been described. Barrier disruption plays a key role in several skin conditions, and moisturization is recommended as an initial treatment in conditions such as atopic dermatitis. This review aimed to analyze the skin barrier in the context of the function model, with a focus on the mechanisms by which moisturizers support each of the functional layers of the skin barrier to promote homeostasis and repair.

SUMMARY

The skin barrier is comprised of four interdependent layers - physical, chemical, microbiologic, and immunologic - which maintain barrier structure and function. Moisturizers target disruption affecting each of these four layers through several mechanisms and were shown to improve transepidermal water loss in several studies. Occlusives, humectants, and emollients occlude the surface of the stratum corneum (SC), draw water from the dermis into the epidermis, and assimilate into the SC, respectively, in order to strengthen the physical skin barrier. Acidic moisturizers bolster the chemical skin barrier by supporting optimal enzymatic function, increasing ceramide production, and facilitating ideal conditions for commensal microorganisms. Regular moisturization may strengthen the immunologic skin barrier by reducing permeability and subsequent allergen penetration and sensitization.

KEY MESSAGES

The physical, chemical, microbiologic, and immunologic layers of the skin barrier are each uniquely impacted in states of skin barrier disruption. Moisturizers target each of the layers of the skin barrier to maintain homeostasis and facilitate repair.

Topical dexpanthenol effects on physiological parameters of the stratum corneum by Confocal Raman Microspectroscopy

BACKGROUND

Topical use of dexpanthenol presents well-established moisturizing properties and maintenance and repair of the skin barrier function, however, its exact action mechanisms are not completely elucidated. In this context, Confocal Raman Microspectroscopy is an optical method that enables non-invasive and non-destructive in vivo analysis with the sensitive acquisition of molecular changes in different skin layers. Herein, the aim was to evaluate the effects of topical dexpanthenol on the components and physiological parameters of the stratum corneum (SC).

MATERIALS AND METHODS

Ten healthy female subjects underwent skin evaluation by means of a Confocal Raman Spectrometer Skin Analyzer 3510. Spectral data were obtained from the skin of the anterior forearm region, before and 2 h after applying a cosmetic formulation containing or not containing 5% dexpanthenol.

RESULTS

Semiquantitative analysis of the natural moisturizing factor showed a significant decrease in content after 2 h of topical dexpanthenol application, while the analysis of the lamellar organization of intercellular lipids and the secondary structure of keratin showed a significant increase in hexagonal organization of lipids at the first half of the SC and a significant increase in β-pleated sheet conformation of keratin.

CONCLUSION

Effects of topical dexpanthenol on SC suggest a contribution in increasing fluidity of both lipidic and protein components of the SC and are compatible with dexpanthenol activity in maintaining adequate physiological conditions and preventing transepidermal water loss. This study also contributes to the elucidation of action mechanisms and other concurrent biochemical processes.

Clay-Catalyzed Ozonation of Hydrotalcite-Extracted Lactic Acid Potential Application for Preventing Milk Fermentation Inhibition

An unprecedented route for mitigating the inhibitory effect of lactic acid (LA) on milk fermentation was achieved through lactate adsorption on hydrotalcite (Ht) from simulated lactate extracts. During its regeneration by ozonation, Ht displayed catalytic activity that appeared to increase by addition of montmorillonite (Mt). Changes in the pH, Zeta potential and catalyst particle size during LA ozonation were found to strongly influence LA–LA, LA–catalyst and catalyst–catalyst interactions. The latter determine lactate protonation–deprotonation and clay dispersion in aqueous media. The activity of Mt appears to involve hydrophobic adsorption of non-dissociated LA molecules on silica-rich areas at low pH, and Lewis acid–base and electrostatic interactions at higher pH than the pKa. Hydrotalcite promotes both hydrophobic interaction and anion exchange. Hydrotalcite–smectite mixture was found to enhance clay dispersion and catalytic activity. This research allowed demonstrating that natural clay minerals can act both as adsorbents for LA extract from fermentation broths and as catalysts for adsorbent regeneration. The results obtained herein provide valuable and useful findings for envisaging seed-free milk clotting in dairy technologies.

Glycerol fermentation by skin bacteria generates lactic acid and upregulates the expression levels of genes associated with the skin barrier function

Commensal bacteria play a major role in multiple skin functions by providing the first layer of defense against pathogens and maintaining the skin barrier. Staphylococcus epidermidis is one of the most common skin commensals. In this study, we showed that S. epidermidis ferments glycerol and uses it as a nutrient, while producing short-chain and organic fatty acids, with the most notable being lactic acid. Lactic acid is an alpha-hydroxy acid that inhibits the growth of pathogenic bacteria, without any negative effect on the commensal bacteria itself. Using in vivo experiments, we validated our in vitro results, showing that the skin microbiome is also capable of doing this. Finally, using 2D and 3D skin culture models, we showed that the fermentation of glycerol, mainly lactic acid, as determined by analytical methods, upregulates the expression levels of several key genes that are associated with the barrier properties of the skin. While the hydration effect of glycerol on the skin is well known, our study shows the overall benefits of glycerol on the skin microbiome, while revealing an alternate mode of action of glycerol for multiple skin benefits.

Molecular characterization of xerosis cutis: A systematic review

Background

Xerosis cutis or dry skin is a highly prevalent dermatological disorder especially in the elderly and in patients with underlying health conditions. In the past decades, numerous molecular markers have been investigated for their association with the occurrence or severity of skin dryness. The aim of this review was to summarize the molecular markers used in xerosis cutis research and to describe possible associations with different dry skin etiologies.

Methods

We conducted a systematic review of molecular markers of xerosis cutis caused by internal or systemic changes. References published between 1990 and September 2020 were searched using ‘MEDLINE’, ‘EMBASE’ and ‘Biological abstracts’ databases. Study results were summarized and analyzed descriptively. The review protocol was registered in PROSPERO database (CRD42020214173).

Results

A total of 21 study reports describing 72 molecules were identified including lipids, natural moisturizing factors (NMFs), proteins including cytokines and metabolites or metabolic products. Most frequently reported markers were ceramides, total free fatty acids, triglycerides and selected components of NMFs. Thirty-one markers were reported only once. Although, associations of these molecular markers with skin dryness were described, reports of unclear and/or no association were also frequent for nearly every marker.

Conclusion

An unexpectedly high number of various molecules to quantify xerosis cutis was found. There is substantial heterogeneity regarding molecular marker selection, tissue sampling and laboratory analyses. Empirical evidence is also heterogeneous regarding possible associations with dry skin. Total free fatty acids, total ceramide, ceramide (NP), ceramide (NS), triglyceride, total free amino acids and serine seem to be relevant, but the association with dry skin is inconsistent. Although the quantification of molecular markers plays an important role in characterizing biological processes, pathogenic processes or pharmacologic responses, it is currently unclear which molecules work best in xerosis cutis.

The Selective Antibacterial Activity of the Mixed Systems Containing Myristic Acid against Staphylococci

Fatty acids and their derivatives are interesting cosmetic ingredients because they show the selective antibacterial activity against Staphylococcus aureus (S. aureus). However, the antibacterial activity in mixed systems containing several active ingredients is unclear because previous studies focused antibacterial systems containing one kind of fatty acid. In the present study, the minimal inhibitory concentration (MIC) and the fractional inhibitory concentration (FIC) were evaluated for myristic acid/lauric acid, myristic acid/palmitoleic acid, and myristic acid/lactic acid mixed systems to show the effect of the coexisting components on the selective antibacterial activity of myristic acid. In the myristic acid/palmitoleic acid mixed system, the antibacterial activity against S. aureus was enhanced by additive effect, whereas the antibacterial activity was not observed against S. epidermidis. On the other hand, the myristic acid/lauric acid mixed system showed antibacterial activity against S. epidermidis: Lauric acid impaired the selectivity of antibacterial activity of myristic acid. These results suggest that the selective activity of myristic acid varies with the additives. The present findings are useful for designing formulations of cosmetics and body cleansers containing myristic acid.

Effectiveness of a cosmetic device containing a combination of alpha- and beta-hydroxy acids, urea, and thuja for the treatment of seborrheic keratoses

BACKGROUND

Seborrheic keratosis is a benign epidermal tumor of cosmetic concern-as it progressively increases in size, thickness, and pigmentation-on which topical treatments are poorly effective. Considering its keratotic component, effective products may include active principles with keratolytic action.

AIMS

Evaluate the efficacy and tolerability of a topical cosmetic product with urea and hydroxy acids, in the treatment of seborrheic keratoses.

PATIENTS AND METHODS

Twenty patients were enrolled in an observational, prospective, open-label study. The topical device was applied on seborrheic keratoses twice daily for 30 days. We evaluated the progression of the treatment by clinical examination-using Daily Life Quality Index-and epiluminescence microscopy at baseline and day 30.

RESULTS

After 30 days of treatment, we documented a significant reduction in seborrheic keratosis thickness and number, which was confirmed also by epiluminescence microscopy. On day 30, global Daily Life Quality Index improved by 99.95%. The tolerability of the cosmetic device was considered excellent, according to 19/20 subjects (95%).

CONCLUSIONS

The results of our study showed the efficacy and tolerability of this cosmetic device. Its active compounds favor gradual removal of seborrheic keratoses, even in case of pigmented variants. This non-invasive treatment represents an alternative to surgical procedures, mainly for fragile patients and delicate skin areas. It is possible to speculate its usefulness in the topical treatment of circumscribed hyperkeratosis, palmoplantar keratoderma, and thick psoriatic plaques.

A daily regimen of a ceramide-dominant moisturizing cream and cleanser restores the skin permeability barrier in adults with moderate eczema: A randomized trial

The dysfunctional skin barrier in eczema patients may be attributed to decreased levels of ceramides in the stratum corneum. The aim of this study was to determine whether a two-part system consisting of a ceramide-dominant physiological lipid-based moisturizing cream and cleanser could ameliorate the signs and symptoms of moderate eczema in adults over 28 days compared to placebo. Assessments were conducted at baseline and every 7 days thereafter. Eczema area severity index score decreased significantly across all time points in both groups compared to baseline (P < .0001), however, this decrease was not significant between groups at day 28 (P = .7804). In contrast, transepidermal water loss and skin hydration significantly improved over time in the active group, while it either stayed the same or worsened in the placebo group (P = .0342 and P < .0001, respectively). There was no difference in the use of mometasone furoate as rescue medication over time between groups (P = .1579). Dermatology life quality index scores improved significantly in both groups (P < .0001), with no difference between groups (P = .5256). However, patient satisfaction was greater in the active compared to the placebo group for several parameters including relief of itch, dry skin, skin softness and smoothness (all P < .05). No patients withdrew from the study due to adverse events (AEs) and there were no serious AEs. The ceramide-dominant moisturizing cream and cleanser safely restores skin permeability and improves the signs and symptoms of eczema in adults.

Multi parametric biophysical assessment of treatment effects on xerotic skin

Background

Topical moisturizing products are widely used to alleviate the problems associated with xerotic skin. Their use affects many properties of the stratum corneum (SC) in a complex and interrelated manner. The range of measurement techniques available to the researcher has increased in recent years. However, few studies have looked for correlations between the different techniques for assessing how aspects of xerotic skin change over time as a result of topical moisturizer usage.

Objectives

A 3‐week in vivo study using an oil‐in‐water based moisturizing product and an untreated site was conducted to determine the clinical significance of and any correlations between a range of different approaches for the measurement of skin lipid content and also skin hydration and visual grading of dry skin.

Methods

A range of traditional and more recently developed skin measurement techniques have been used to examine a variety of SC properties in normal and xerotic skin during topical moisturizer usage.

Results

In vivo confocal Raman spectroscopy and analysis of SC lipids from tape strips both showed an increase in SC lipid level and organization after 3 weeks of moisturizer usage on xerotic skin. Hydration, measured both optically and electrically, also increased and skin barrier function improved, with strong correlations between the different measures of dryness being observed.

Conclusions

Strong correlations were observed between the skin measurements for lipid assessment and skin hydration with regard to the assessment of xerotic skin, providing valuable new information for future in vivo clinical research into dry and atopic skin.

Keywords

biophysical assessment, skin barrier, skin hydration, topical moisturizers, Xerosis

UV-Irradiation- and Inflammation-Induced Skin Barrier Dysfunction Is Associated with the Expression of Olfactory Receptor Genes in Human Keratinocytes

Olfactory receptors (ORs) have diverse physiological roles in various cell types, beyond their function as odorant sensors in the olfactory epithelium. These previous findings have suggested that ORs could be diagnostic markers and promising therapeutic targets in several pathological conditions. In the current study, we sought to characterize the changes in the expression of ORs in the HaCaT human keratinocytes cell line exposed to ultraviolet (UV) light or inflammation, well-recognized stimulus for skin barrier disruption. We confirmed that major olfactory signaling components, including ORs, GNAL, Ric8b, and adenylate cyclase type 3, are highly expressed in HaCaT cells. We have also demonstrated that the 12 ectopic ORs detectable in HaCaT cells are more highly expressed in UV-irradiated or inflamed conditions than in normal conditions. We further assessed the specific OR-mediated biological responses of HaCaT cells in the presence of known odorant ligands of ORs and observed that specific ligand-activated ORs downregulate skin barrier genes in HaCaT cells. This study shows the potential of OR as a marker for skin barrier abnormalities. Further research is needed to explore how OR is implicated in the development and progression of barrier dysfunction.

Efficacy of Nonprescription Moisturizers for Atopic Dermatitis: An Updated Review of Clinical Evidence

Twice-daily moisturization is recommended by international guidelines as the bedrock of the management of atopic dermatitis (AD). Moisturizers should be selected based on proven clinical effectiveness in improving the skin barrier and improving the symptoms of AD. We searched the PubMed database for clinical trials assessing daily moisturization for the treatment of AD published between 2006 and 2019. Studies had to assess the efficacy of commercially available moisturizers using objective measures of corneometry, transepidermal water loss, or incidence of flare as endpoints, and treatments had to be currently available to patients. Clinical studies showed that moisturization (typically twice daily) significantly improved the skin barrier in adults and children with AD. Longer-term flare studies showed that daily moisturization reduced the incidence of flares and extended the time between flares. Proactive moisturization of infants at high risk of developing AD may reduce its manifestation. Therapeutic moisturizers for AD are specifically formulated with ingredients that target symptoms of AD, such as itch, inflammation, or compromised skin barrier. The US FDA requires that any moisturizer available in the USA and claiming to treat AD must contain colloidal oatmeal. Healthcare providers can maximize compliance and outcomes by educating patients on the benefits of liberally applying a therapeutic moisturizer twice daily to support the skin barrier and help reduce the incidence of flares. Specific recommendations should be for clinically tested moisturizers evaluated using objective, validated skin assessments.

Vehicles for atopic dermatitis therapies: more than just a placebo

A topical vehicle is a 'carrier system' for an active pharmaceutical (or cosmetic) substance, referred to hereafter as the drug, but a vehicle may also be used on its own as an emollient to ameliorate dry skin. It is well established that the vehicle plays an important role in determining the bioavailability of a given drug at its ultimate target within the skin. Yet in the treatment of atopic eczema/dermatitis (AD), wherein the structure and function of the skin's outer barrier play a pivotal role in the development and course of the condition, the interaction of the vehicle with this barrier carries a particular importance. It is now clear that the often-considered inert excipients of a vehicle bring about changes within the skin at the molecular level that promote barrier restoration and enhance innate immune defenses with therapeutic value to AD patients. Moreover, the vehicle control in randomized controlled trials (RCTs) increasingly displays significant efficacy. In light of this, we consider the implications of vehicle design in relation to AD pathophysiology and the role vehicles play as controls in RCTs of new drug treatments for this condition.

Diagnosis and treatment of xerosis cutis - a position paper

BACKGROUND AND RATIONALE

Xerosis cutis (also referred to as xeroderma, dry skin, asteatosis) affects more than 10 million individuals in Germany. It is among the most common dermatological diagnoses and a cardinal symptom of many dermatological, internal and neurological diseases. Even though it has been established that basic skin care plays a significant role in the management of patients with xerosis cutis, there are as yet no evidence-based algorithms for diagnosis and treatment.

OBJECTIVE

The present position paper provides physicians across all specialties with a practical, symptom-based approach to the prevention, diagnosis and treatment of xerosis cutis.

METHODS

Within a structured decision-making process, a panel of experienced dermatologists first defined questions relevant to everyday clinical practice, which were then addressed by a systematic review of the literature. Based on the evidence available as well as expert consensus, diagnostic and treatment algorithms were subsequently developed and agreed upon.

RESULTS

Xerosis cutis is generally diagnosed on clinical grounds. Possible trigger factors must be avoided, and comorbidities should be adequately and specifically treated. Suitable skin care products should be chosen with a view to improving skin hydration and restoring its barrier function. They should therefore contain both rehydrating and lipid-replenishing components. The "drier" the skin appears, the greater the lipid content should be (preferably using water-in-oil formulations). The choice of ingredients is based on a patient's individual symptoms, such as scaling (e.g., urea), fissures/rhagades (e.g., urea or dexpanthenol), erythema (e.g., licochalcone A) and pruritus (e.g., polidocanol). Other factors to be considered include the site affected and patient age. Ingredients or rather combinations thereof for which there is good clinical evidence should be preferentially used. The best evidence by far is available for urea, whose efficacy in the treatment of xerosis is further enhanced by combining it with other natural moisturizing components and ceramides. The "xerosimeter" is a tool developed in an effort to facilitate patient management and for training purposes. It not only includes practical tools for diagnosis and follow-up but also a classification of ingredients and a structured treatment algorithm.

CONCLUSION

The structured symptom- and evidence-based approach proposed herein contains a road map for diagnosis and treatment of xerosis cutis. It aims to raise awareness in terms of prevention and early treatment of this condition and may thus improve quality of life and prevent potential sequelae.

The Enigma of Bioactivity and Toxicity of Botanical Oils for Skin Care

Botanical oils have a long history of traditional use and are routinely applied to skin care. The focus of this review is to contrast the functionality of skin oils versus the differential biological and toxicological effects of major plant oils, and to correlate them to their compositional changes. In total, over 70 vegetable oils were clustered according to their lipid composition to promote awareness of health practitioners and botanical product manufacturers for the safety and efficacy of oil-based interventions based on their fatty acid profiles. Since multiple skin disorders result in depletion or disturbance of skin lipids, a tailored mixture of multiple botanical oils to simultaneously maintain natural skin-barrier function, promote repair and regeneration of wounded tissues, and achieve corrective modulation of immune disorders may be required. As bioactive constituents of botanical oils enter the human body by oral or topical application and often accumulate in measurable blood concentrations, there is also a critical need for monitoring their hazardous effects to reduce the possible over-added toxicity and promote maximal normal tissue sparing. The review also provides a useful tool to improve efficacy and functionality of fatty acid profiles in cosmetic applications.

Skin hydration is significantly increased by a cream formulated to mimic the skin's own natural moisturizing systems

Background

Moisturizers are topical products designed to improve and maintain the skin barrier function and to help prevent dry skin.

Materials and methods

A new moisturizer (Ceramide cream) was formulated containing ingredients which mimic the skin's own natural moisturizing systems. Corneometry was performed at baseline, 2, 4, 6 and 24 hours following a single application of Ceramide cream to healthy skin, and compared to three reference moisturizers available over-the-counter, and placebo. Transepidermal water loss (TEWL) was also measured following a single application of Ceramide cream compared to baseline, and its safety was assessed by repeat insult patch test, ophthalmologist and pediatric testing.

Results

A single topical application of either the Ceramide cream or the three reference moisturizers resulted in a significant increase in skin hydration over time (P<0.001). The placebo cream did not significantly increase skin hydration at any time point. At 24 hours post-application, skin hydration measured for Ceramide cream was significantly greater (P<0.05) than that measured for all three of the reference moisturizers tested. Ceramide cream was also found to significantly decrease TEWL (P<0.001) over 24 hours, and was shown to be non-sensitizing to the skin of both adults and children and non-irritating to the skin, eyes and related eye area.

Conclusion

Ceramide cream increases skin hydration and improves barrier function which may make it suitable for use on dry skin.

The Role of Moisturizers in Addressing Various Kinds of Dermatitis: A Review

Moisturizer is a major component of basic daily skin care, particularly in presence of epidermal barrier alteration and reduced epidermal water content. It is an important part of a dermatologist's strategy to maintain skin health as well as treating various dermatoses which co-exist with skin dryness and are linked to impaired skin barrier function, such as in atopic disorders as well as other types of dermatitis. Mastering the knowledge regarding mechanism of action, application, dosage, adverse effects as well as specific clinical usage of moisturizers is a must for a dermatologist in order to support their use, particularly for evidence-based, therapeutic purposes. This review discusses the use of moisturizer both for skin health maintenance as well as a definitive or adjuvant therapy for many kinds of dermatitis.

Efficacy and tolerability of a double-conjugated retinoid cream vs 1.0% retinol cream or 0.025% tretinoin cream in subjects with mild to severe photoaging

BACKGROUND

Topical retinoids are used to treat the visible signs of photoaging. While efficacious, they are irritating.

OBJECTIVE

Evaluate the effectiveness and tolerability of a double-conjugate retinoid cream (AlphaRet Overnight Cream; AHA-Ret) in improving visible signs of photoaging vs 1.0% retinol or 0.025% tretinoin.

METHODS

A 12-week, split-face, randomized trial was conducted in 48 female subjects, aged 30-65 years with mild to severe photodamage. AHA-Ret was applied to one side of the face and either retinol (n=24) or tretinoin (n=24) to the other side (PM). Expert blinded evaluation of images and Nova measurements occurred at 4, 8, and 12 weeks. Tolerability was assessed throughout the study.

RESULTS

Forty-seven subjects completed the study. AHA-Ret demonstrated significant reductions in average severity from baseline: Fine Lines/Wrinkles (P<.001; all time points); Erythema (P=.004, P<.0001; 8 and 12 weeks, respectively); Dyschromia (P<.0001; all time points); Skin Tone (P<.0001; all time points), and Pore Size (P=.035, P<.0001; 8 and 12 weeks, respectively). AHA-Ret induced less Erythema vs retinol at 8 (P=.008) and 12 (P<.02) weeks. AHA-Ret was noninferior to prescription tretinoin in all categories at 4 and 8 weeks, and for Fine Lines/Wrinkles, Erythema, Dyschromia, and Skin Tone at 12 weeks. Improvements in Hydration occurred at every time point with AHA-Ret only (P<.04, P<.03, P<.01). Less irritation was reported with AHA-Ret vs retinol or tretinoin.

CONCLUSIONS

Treatment with a double-conjugate retinoid cream demonstrated early reductions in photodamage and improvements in Hydration. AHA-Ret induced less Erythema vs retinol and was more tolerable vs retinol and tretinoin.

Beneficial and Healthy Properties of Eucalyptus Plants: A Great Potential Use

Eucalyptus (Eucapyptusspp.), an evergreen tall tree native to Australia and Tasmania, has been used since ancient times by the aboriginal population for several purposes. In particular, the speciesE. globulusis widely used in the pulp industry, as well as for the production of eucalyptus oil extracted on a commercial scale in many countries as raw materials in perfumery, cosmetics, food, beverages, aromatherapy and phytotherapy. The 1,8-cineole (eucalyptol), the principal and the most important constituent extracted from eucalyptus leaves, demonstrated an antimicrobial and anti-inflammatory activities. Despite the fact that the healthy effects of eucalyptus have been well established by research, further studies are necessary to investigate other prime effects of the plant and its possible implication in the treatment of a greater number of pathological conditions.

Glycolic Acid Silences Inflammasome Complex Genes, NLRC4 and ASC, by Inducing DNA Methylation in HaCaT Cells

AHAs (α-hydroxy acids), including glycolic acid (GA), have been widely used in cosmetic products and superficial chemical peels. Inflammasome complex has been shown to play critical roles in inflammatory pathways in human keratinocytes. However, the anti-inflammatory mechanism of GA is still unknown. The aim of this study is to investigate the relationship between the expression of the inflammasome complex and epigenetic modification to elucidate the molecular mechanism of the anti-inflammatory effect of GA in HaCaT cells. We evaluated NLRP3, NLRC4, AIM2, and ASC inflammasome complex gene expression on real-time polymerase chain reaction (PCR). Methylation changes were detected in these genes following treatment with DNA methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine (5-Aza) with or without the addition of GA using methylation-specific PCR (MSP). GA inhibited the expressions of these inflammasome complex genes, and the decreases in the expressions of mRNA were reversed by 5-Aza treatment. Methylation was detected in NLRC4 and ASC on MSP, but not in NLRP3 or AIM2. GA decreased NLRC4 and ASC gene expression by increasing not only DNA methyltransferase 3B (DNMT-3B) protein level, but also total DNMT activity. Furthermore, silencing of DNMT-3B (shDNMT-3B) increased the expressions of NLRC4 and ASC. Our data demonstrated that GA treatment induces hypermethylation of promoters of NLRC4 and ASC genes, which may subsequently lead to the hindering of the assembly of the inflammasome complex in HaCaT cells. These results highlight the anti-inflammatory potential of GA-containing cosmetic agents in human skin cells and demonstrate for the first time the role of aberrant hypermethylation in this process.

Molecular basis for stratum corneum maturation and moisturization

This themed edition of BJD is dedicated to the work of Professor Ronald Marks for his untiring work on the understanding of stratum corneum (SC) structure and function. He and his coworkers, in my opinion, had the right focus for cosmetic dermatology issues. Namely, consumers experience the wonderful properties of the SC through sight, touch and the somatosensory system. They do not experience, for example, transepidermal water loss and skin conductance or capacitance! Marks understood this and set about developing the methodologies to examine the changes in SC architecture and function when desquamation goes haywire. More importantly, he understood that moisturizers do far more than simply hydrate the SC, as exemplified in the paper by Tree and Marks, 'An explanation for the placebo effect of bland ointment bases.' Moisturizing ingredients influence the properties of the SC in many ways with the sole purpose of overcoming the signs and symptoms of dry skin. Marks demonstrated the decrease in SC cohesion following use of hydrating agents, which led to the mechanistic work on the effects of a simple molecule like glycerol on the desquamatory process. In further exploiting forced desquamation and use of abrasion, he showed that improvements in exfoliation contribute to the mitigation of the signs of photodamaged skin, which can explain part of the antiageing effect of simple moisturizers. It is here that I should point out that at least this particular author in 1988 was 'standing on the shoulders of' a great corneologist whose work influenced his research directions. So this paper will provide an update on the latest developments for the molecular basis of SC maturation and moisturization, while highlighting the contributions of Professor Marks in the different areas.

Incidence and risk of xerosis with targeted anticancer therapies

BACKGROUND

Many targeted therapies used in the treatment of cancer can lead to the development of xerosis, but the incidence and relative risk of xerosis have not been ascertained.

OBJECTIVE

We conducted a systematic review and metaanalysis of clinical trials, to ascertain the incidence and risk of developing xerosis after taking anticancer drugs.

METHODS

The PubMed (1966-October 2013), Web of Science (January 1998-October 2013), and American Society of Clinical Oncology abstracts (2004-2013) databases were searched for clinical trials of 58 targeted agents. Results were calculated using random or fixed effects models.

RESULTS

The incidences of all- and high-grade xerosis were 17.9% (95% confidence interval [CI]: 15.6-20.4%) and 1.0% (95% CI: 0.9-1.5%), respectively. The risk of developing all-grade xerosis was 2.99 (95% CI: 2.0-4.3), and it varied across different drugs (P < .001).

LIMITATIONS

The reporting of xerosis may vary among clinicians and institutions, and the incidence may be affected by age, concomitant medications, comorbidities, and underlying malignancies or skin conditions.

CONCLUSION

Patients receiving targeted therapies have a significant risk of developing xerosis. Patients should be counseled and treated early for this symptom to prevent suboptimal dosing and quality of life impairment.

Children with dry skin and atopic predisposition: daily use of emollients in a participant-blinded, randomized, prospective trial

BACKGROUND

Dry skin reflects a skin barrier defect which can lead to atopic dermatitis. Little is known about the distinct effects of emollient use in children with dry skin and atopic predisposition.

OBJECTIVES

We investigated the effects of daily application of pressed ice plant juice (PIPJ)-based emollients and petrolatum-based emollients.

METHODS

Children aged 2-6 years with dry skin and atopic predisposition were randomized into 2 groups: group 1 received emollients containing PIPJ and natural lipids, while group 2 received petrolatum-based emollients. Skin condition and biophysical properties of the skin barrier were assessed at inclusion and weeks 4, 12 and 16.

RESULTS

Skin condition improved significantly in all children. Comparing the groups, children treated with emollients containing PIPJ showed significantly higher stratum corneum hydration values and significantly lower transepidermal water loss values at week 16 on the forearm and forehead. A significant decrease in skin pH was noted in group 2 on the forearm and forehead; group 1 showed a stable course.

CONCLUSION

Early intervention with emollients in children with dry skin condition and atopic predisposition may improve their skin condition during daily emollient application. PIPJ-based formulations may be helpful to maintain skin barrier integrity.

Bioactives from probiotics for dermal health: functions and benefits

Probiotics have been extensively reviewed for decades, emphasizing on improving general gut health. Recently, more studies showed that probiotics may exert other health-promoting effects beyond gut well-being, attributed to the rise of the gut-brain axis correlations. Some of these new benefits include skin health such as improving atopic eczema, atopic dermatitis, healing of burn and scars, skin-rejuvenating properties and improving skin innate immunity. Increasing evidence has also showed that bacterial compounds such as cell wall fragments, their metabolites and dead bacteria can elicit certain immune responses on the skin and improve skin barrier functions. This review aimed to underline the mechanisms or the exact compounds underlying the benefits of bacterial extract on the skin based on evidences from in vivo and in vitro studies. This review could be of help in screening of probiotic strains with potential dermal enhancing properties for topical applications.

Effect of moisturizers on epidermal barrier function

A daily moisturizing routine is a vital part of the management of patients with atopic dermatitis and other dry skin conditions. The composition of the moisturizer determines whether the treatment strengthens or deteriorates the skin barrier function, which may have consequences for the outcome of the dermatitis. One might expect that a patient's impaired skin barrier function should improve in association with a reduction in the clinical signs of dryness. Despite visible relief of the dryness symptoms, however, the abnormal transepidermal water loss has been reported to remain high, or even to increase under certain regimens, whereas other moisturizers improve skin barrier function. Differing outcomes have also been reported in healthy skin: some moisturizers produce deterioration in skin barrier function and others improve the skin. Possible targets for barrier-influencing moisturizing creams include the intercellular lipid bilayers, where the fraction of lipids forming a fluid phase might be changed due to compositional or organizational changes. Other targets are the projected size of the corneocytes or the thickness of the stratum corneum. Moisturizers with barrier-improving properties may delay relapse of dermatitis in patients with atopic dermatitis. In a worst-case scenario, treatment with moisturizing creams could increase the risks of dermatitis and asthma.

Improvement by sodium dl-α-tocopheryl-6-O-phosphate treatment of moisture-retaining ability in stratum corneum through increased ceramide levels

Sodium dl-α-tocopheryl-6-O-phosphate (1), a water-soluble derivative of vitamin E (dl-α-tocopherol, 2), exhibits protective effects against various type of skin damage. As reported herein, we found that topical application of 1 improves hygroscopicity and water holding capacity in the stratum corneum of hairless mice in vivo by increasing the ceramide content. In normal human epidermal keratinocytes, treatment with 1 increases ceramide levels and enhances gene expression of serine palmitoyltransferase, which catalyzes the first step of ceramide synthesis in vitro. In addition, 1 increases gene expressions of differentiation markers (transglutaminase 1, cytokeratin 10, involucrin and loricrin), and intracellular Ca(2+) concentrations. These results suggest that 1 could be an excellent agent for improving skin moisture-retention by enhancing ceramide synthesis through the induction of differentiation.

Healing fats of the skin: the structural and immunologic roles of the omega-6 and omega-3 fatty acids

Linoleic acid (18:2omega6) and alpha-linolenic acid (18:3omega3) represent the parent fats of the two main classes of polyunsaturated fatty acids: the omega-6 (n-6) and the omega-3 (n-3) fatty acids, respectively. Linoleic acid and alpha-linolenic acid both give rise to other long-chain fatty acid derivatives, including gamma-linolenic acid and arachidonic acid (omega-6 fatty acids) and docosahexaenoic acid and eicosapentaenoic acid (omega-3 fatty acids). These fatty acids are showing promise as safe adjunctive treatments for many skin disorders, including atopic dermatitis, psoriasis, acne vulgaris, systemic lupus erythematosus, nonmelanoma skin cancer, and melanoma. Their roles are diverse and include maintenance of the stratum corneum permeability barrier, maturation and differentiation of the stratum corneum, formation and secretion of lamellar bodies, inhibition of proinflammatory eicosanoids, elevation of the sunburn threshold, inhibition of proinflammatory cytokines (tumor necrosis factor-alpha, interferon-gamma, and interleukin-12), inhibition of lipoxygenase, promotion of wound healing, and promotion of apoptosis in malignant cells, including melanoma. They fulfill these functions independently and through the modulation of peroxisome proliferator-activated receptors and Toll-like receptors.

Synergistic effect of ultrasound and thiazone-PEG 400 on human skin optical clearing in vivo

In this paper, we propose a new physical method in combination with mixed solution of thiazone and polyethylene glycol 400 (thiazone PEG 400 solution) penetration into tissue to assess the skin optical clearing. Four treatments were performed: (1) control group (C); (2) polyethylene glycol 400 (PEG400); (3) 0.25% thiazone (0.25%T); (4) 0.25% thiazone and 5-min ultrasound (0.25%T/SP). The diffuse reflectance spectra and imaging depth of human skin in vivo at different times were measured by spectroscopy and optical coherence tomography (OCT). The optical clearing efficacy of skin was qualitatively and quantitatively analyzed. The results showed that the diffuse reflectance at 540 nm of samples at 10 min after being treated by 0.25%T/SP decreased by approximately 15.51%, whereas, 0.46%, 4.73% and 5.75% were received in C, PEG400 and 0.25%T, respectively. And at 60 min, the decrease in diffuse reflectance of samples in 0.25%T/SP is about 2.22-fold, 1.20-fold compared with that of the samples in PEG 400 and 0.25%T, at 540 nm, respectively. Simultaneously, 0.25%T/SP results in 41.33% increase in OCT 1/e light penetration depth after 60 min. There was a significant difference in the optical clearing effect on skin between ultrasound-mixed solution of thiazone in combination with PEG 400 and the mixed solution (P < 0.05).

Acute acidification of stratum corneum membrane domains using polyhydroxyl acids improves lipid processing and inhibits degradation of corneodesmosomes

Neutralization of the normally acidic stratum corneum (SC) has deleterious consequences for permeability barrier homeostasis and SC integrity/cohesion attributable to serine proteases (SPs) activation leading to deactivation/degradation of lipid-processing enzymes and corneodesmosomes (CD). As an elevated pH compromises SC structure and function, we asked here whether SC hyperacidification would improve the structure and function. We lowered the pH of mouse SC using two polyhydroxyl acids (PHA), lactobionic acid (LBA), or gluconolactone (GL). Applications of the PHA reduced the pH at all levels of SC of hairless mouse, with further selective acidification of SC membrane domains, as shown by fluorescence lifetime imaging. Hyperacidification improved permeability barrier homeostasis, attributable to increased activities of two key membrane-localized, ceramide-generating hydrolytic enzymes (beta-glucocerebrosidase and acidic sphingomyelinase), which correlated with accelerated extracellular maturation of SC lamellar membranes. Hyperacidification generated "supernormal" SC integrity/cohesion, attributable to an SP-dependent decreased degradation of desmoglein-1 (DSG1) and the induction of DSG3 expression in lower SC. As SC hyperacidification improves the structure and function, even of normal epidermis, these studies lay the groundwork for an assessment of the potential utility of SC acidification as a therapeutic strategy for inflammatory dermatoses, characterized by abnormalities in barrier function, cohesion, and surface pH.

pH-regulated mechanisms account for pigment-type differences in epidermal barrier function

To determine whether pigment type determines differences in epidermal function, we studied stratum corneum (SC) pH, permeability barrier homeostasis, and SC integrity in three geographically disparate populations with pigment type I-II versus IV-V skin (Fitzpatrick I-VI scale). Type IV-V subjects showed: (i) lower surface pH (approximately 0.5 U); (ii) enhanced SC integrity (transepidermal water loss change with sequential tape strippings); and (iii) more rapid barrier recovery than type I-II subjects. Enhanced barrier function could be ascribed to increased epidermal lipid content, increased lamellar body production, and reduced acidity, leading to enhanced lipid processing. Compromised SC integrity in type I-II subjects could be ascribed to increased serine protease activity, resulting in accelerated desmoglein-1 (DSG-1)/corneodesmosome degradation. In contrast, DSG-1-positive CDs persisted in type IV-V subjects, but due to enhanced cathepsin-D activity, SC thickness did not increase. Adjustment of pH of type I-II SC to type IV-V levels improved epidermal function. Finally, dendrites from type IV-V melanocytes were more acidic than those from type I-II subjects, and they transfer more melanosomes to the SC, suggesting that melanosome secretion could contribute to the more acidic pH of type IV-V skin. These studies show marked pigment-type differences in epidermal structure and function that are pH driven.

Measuring the effects of topical moisturizers on changes in stratum corneum thickness, water gradients and hydration in vivo

BACKGROUND

Moisturizers are the most commonly used topically applied product for the treatment of dry skin conditions. They affect many properties and functions of the stratum corneum but some moisturizers have been reported to be detrimental to barrier function. Stratum corneum barrier function is a composite of its total structure and thickness but few studies have taken this into account. As a biosensor, the stratum corneum (SC) will change its structure in response to treatment and a swelling effect has been clearly demonstrated by skin hydration. Recently several moisturizing agents have been shown to have an effect on SC swelling behaviour with conflicting results. However, there is a paucity of data reported for measuring the effects of long-term usage of moisturizers on SC thickness in vivo as, until recently, traditional techniques did not have the resolution to measure the effects of moisturizers on nonpalmoplantar body sites. The development of confocal Raman spectroscopy for use in human subjects provides noninvasive, real-time, in vivo measurement of SC water concentration profiles and we have also used this state of the art equipment to measure the effect of the long-term use of moisturizers on SC thickness for the first time.

OBJECTIVES

To validate the use of confocal Raman spectroscopy (CRS) to measure SC thickness and then use it to investigate the short- and long-term effects of moisturizers (one of which is known to improve SC barrier function) on SC thickness, water gradients and hydration.

METHODS

Two studies were conducted: (i) to validate the use of CRS for measuring SC thickness through comparison with optical coherence tomography (OCT); and (ii) once validated to use CRS to measure the long-term effects of three commercially available moisturizers (A, B, C) on SC thickness and water gradients, together with total hydration, over a 3-week period (2 weeks of treatment and 1 week regression) and compare the spectroscopy-derived hydration value with instrumentally derived capacitance hydration values.

RESULTS

(i) A strong, positive correlation in SC thickness was obtained between CRS and OCT (OCT-derived thickness = 0.96 x CRS-derived thickness, r(2) = 0.93; P <0.0001). OCT was shown, however, to have a lower resolution than CRS in distinguishing SC thickness on thinner nonpalmoplantar body sites. Using the CRS method, differences in SC thickness were readily apparent on different body sites (cheek 12.8 +/- 0.9 microm, volar forearm 18.0 +/- 3.9 microm, leg 22.0 +/- 6.9 microm). (ii) Examining the effects of moisturizers in a blinded, randomized 3-week study in human volunteers (n = 14) demonstrated that only one commercially available formulation (A) changed SC water gradients, thickness and hydration as measured by CRS. These hydration data did not directly correlate with capacitance hydration values.

CONCLUSIONS

(i) In vivo CRS was validated as a technique to measure SC thickness on both palmoplantar and, particularly, on nonpalmoplantar skin sites. (ii) Moisturizers improve skin moisturization but in this study only formulation A improved SC thickness, water gradients and hydration as measured by CRS. We hypothesize that this was due to compositional differences between the products. We believe that niacinamide (nicotinamide, vitamin B(3)) is probably contributing significantly to this effect, as it has been proven to increase epidermal lipogenesis and SC barrier function in other studies. These results show that by using CRS, we were able for the first time to determine the effect of moisturizer on multiple SC barrier endpoints including SC thickness, and water content as a function of depth and total SC water content.

Steroids versus other immune modulators in the management of allergic dermatoses

PURPOSE OF REVIEW

The classic role of topical and systemic corticosteroids for allergic dermatoses is discussed, with special attention to the impact on the current clinical treatment paradigm by newer systemic and topical therapies. These products are reviewed and recommendations presented on how to effectively assimilate them into clinical practice.

RECENT FINDINGS

Current knowledge about the etiopathogenesis of atopic dermatitis has resulted in drug development focused on agents with less toxicity than current topical and systemic corticosteroids. Some agents with ceramide/cholesterol/acid combinations demonstrate efficacy in restoring the dysfunctional skin barrier of atopic patients. Concerns resulting from the recent Federal Drug Administration announcement regarding a theoretical risk of cancer associated with topical calcineurin inhibitors are also addressed. Novel therapeutic entities are presented.

SUMMARY

Patients seeking relief from atopic dermatitis have historically had few really effective and safe therapeutic options. Topical calcineurin inhibitors represent an exciting new therapy for atopic dermatitis without the side-effect profile associated with topical corticosteroids. Nonsteroidal formulations incorporating glycyrrhetinic acid/telmesteine/Vitis vinifera extract and palmitoylethanolamide as 'active' ingredients recently entered the market, stressing antipruritic, antiinflammatory, and skin barrier repair. This confabulates against previously designed topical therapy paradigms. These new products may be used as monotherapy or alternatives to steroid agents.

Changing paradigms in dermatology: topical immunomodulators within a permutational paradigm for the treatment of atopic and eczematous dermatitis

The first formulation of a class of products called topical immuno modulators (TIMS) was approved for clinical use in December 2000 and released in February 2001. This product is tacrolimus in an ointment base, prescribed under the Protopic. The next TIM, pimecrolimus cream, was FDA approved in December 2001 and launched February 2002 in a cream vehicle under the Elidel. TIMs are becoming a significant component in the topical treatment paradigm for atopic dermatitis, introducing a useful alternative to, or complement for, high- and low-potency topical steroid therapy.