Formulation of a new broad-spectrum UVB + UVA and blue light SPF50+ sunscreen containing Phenylene Bis-Diphenyltriazine (TriAsorB), an innovative sun filter with unique optical properties

Accumulating evidence from numerous comprehensive studies has demonstrated that blue light, in particular high-energy visible light, can exert a range of harmful effects on skin cells. These forms of radiation are now known to be able to trigger oxidation reactions, DNA damage, erythema and pigmentary changes, and may also be associated with photoaging. Sunscreens protecting the skin from only ultraviolet (UV)-B and UVA rays can therefore no longer be regarded as sufficient to help prevent skin damage from sunlight, and products containing filters that can provide broad-spectrum photoprotection are required. To meet this need, a new sunscreen formulation that provides photoprotection against solar radiation with wavelengths ranging from UV to visible light has been developed, using an innovative organic sun filter with unique optical properties: phenylene bis diphenyltriazine (TriAsorB™). This article outlines the development and characteristics of this innovative filter and describes new key results from studies performed to assess the effectiveness and safety of the filter and the new sunscreen product. The studies conducted so far demonstrate that the filter has a good human and environmental safety profile. In addition, the sunscreen, which contains TriAsorB in combination with three other UV filters to offer broad-spectrum sun protection with a high sun protection factor (SPF50⁺ ), appears to effectively prevent multiple forms of cellular photodamage, in particular blue light-induced oxidatively generated DNA lesions. Overall, the available data indicate that regular use of the TriAsorB-containing sunscreen could help prevent solar radiation-induced skin damage and the development of signs of premature skin aging, as well as photodermatoses caused or exacerbated by visible light.

MS imaging and absorption methods visualizing sun filter skin spatial distribution and penetration

Sunscreens must now be effective in protecting skin from ultraviolet, as well as visible/infrared radiation. Here, TriAsorB, a new broad-spectrum sun filter, was formulated with three other sunscreens and their distribution on human skin was studied using a standard penetration protocol and two novel mass spectrometry imaging techniques: atmospheric pressure matrix assisted laser desorption ionization (AP-MALDI) coupled to high resolution mass spectrometry and time of flight - secondary ion mass spectrometry (ToF-SIMS). The standard penetration protocol showed that sun filters absorption was very low, with most of the dose recovered at the surface (none entered the receptor fluid). Absorption was not increased in damaged skin. The results were confirmed by AP-MALDI and ToF-SIMS imaging of the spatial distribution of molecular species in cross-section samples of human skin. Each sun filter was detected on or in the stratum corneum, with a good homogenous coverage over the valleys and peaks of the skin, and correlated well with the distribution of endogenous biomarkers. In conclusion, conventional and novel imaging analysis methods showed that the sun filters remained mainly on the skin surface after topical application. Mass spectrometry imaging is a promising complementary approach to traditional skin penetration studies to visualize penetration of compounds.

In vitro characterization and clinical evaluation of skin hydration by two formulations mimicking the skin's natural components

BACKGROUND

We have developed innovative base formulations that were designed to mimic the skin with respect to its components and galenic structure. Components include water, proteins, lipids, sugars and minerals.

OBJECTIVES

We characterized formulations and their skin penetration using in vitro methods and evaluated their impact on skin hydration in a clinical trial.

METHODS

Scanning electron microscopy (SEM) imaging and X-ray diffraction were used to analyse formulations as well as formulation impact on the stratum corneum (SC) structure. Mass spectrometry imaging (MSI) was used to compare formulation ingredients with SC components and to detect their distribution in the skin. Clinical studies were performed to confirm effects on skin hydration and investigate potential adverse skin effects (irritation and sensitization).

RESULTS

SEM and X-ray diffraction of the formulations showed that lipids were organized in sheets similar to SC lipids. MSI demonstrated similarities between formulation components and skin constituents, as well as a good penetration into the skin. The formulations did not modify the lamellar organization of the SC lipids, but they increased the relative proportion of the crystallized lipids and some of the amorphous lipids. In in vivo studies, a high level of hydration was maintained over 24 h after application with an intense and 'very good hydration'. Both formulations were shown to be non-(photo)sensitizers with excellent tolerance. Sensorial evaluation indicated the formulations were not oily or sticky and maintained the skin's suppleness over time. Formulations had a 'nude skin' touch and created a natural protective film.

CONCLUSIONS

The two formulations were well-tolerated and increased skin hydration in clinical subjects, an effect that could contribute to the alleviation of sensitive skin. The formulations were shown to resemble the lipid organization of the stratum corneum, as well as penetrate the skin without disrupting the lipid lamella organization.

Clinical evaluation of anaesthetic-like effect of two dermocosmetic formulations containing Aquaphilus dolomiae extract-G3 in subjects with sensitive facial skin

BACKGROUND

Sensitive skin is a common condition of hyper-reactivity to external stimuli, e.g. heat or abrasion. The symptoms are subjective but can be measured using validated emotional and technical methods. Avène water has several beneficial effects on the skin. In vitro studies indicated that the active component of this natural spring water, Aquaphilus dolomiae extract-G3 (ADE-G3), modulates cutaneous sensitivity via an anaesthetic-like mechanism.

OBJECTIVES

To assess facial skin reactivity after repeated application of two formulations containing ADE-G3.

METHODS

In open-label studies, healthy subjects with sensitive facial skin applied cream or balm twice daily for 84 days. The severity of skin sensitivity was measured using the Sensitive Scale (based on quantifying visible or subjective signs). Subjective responses associated with pain or uncomfortable feeling were assessed by measuring electrodermal response (EDR). This involves measuring variations in skin electrical resistance due to non-conscious physiological changes in activity of the sympathetic nervous system. Subjects were also evaluated for beneficial effects according to a quantitative approach using semantic assessment of a question regarding their skin quality. Evaluations were performed before and after the first application, and after 29/30, 56 and 84 days of twice daily use.

RESULTS

There was a significant decrease in the EDR after stimuli immediately after the application of both ADE-G3 formulations, which continued to decrease over 84 days (40-50% decrease by D85). Likewise, all physical and functional signs of the Sensitive Scale were significantly decreased immediately after the first application and at all time points tested after treatment. Verbatim analysis revealed a semantic shift, from mainly negative terms on D1 to mainly positive terms at D85 for both tested products.

CONCLUSIONS

These results demonstrated that two formulations containing ADE-G3 reduced skin sensitivity, indicating a decreased activation of the sympathetic nervous system associated with this condition.

Specific protection of sensitive skin against environmental stress by maintenance and improvement of barrier function

BACKGROUND

Sensitive skin is a common condition that can severely impact quality of life. Several mechanisms are thought to be involved, including those affecting the skin barrier function, hydration and skin innervation.

OBJECTIVES

To investigate the benefit of cream and balm formulations dedicated to sensitive skin and containing Aquaphilus dolomiae extract-G3 (ADE-G3) on skin barrier functions (lipid composition, pH, TEWL), as well as protective responses to dry and pollution stresses.

METHODS

In vitro sensitized (using histamine) reconstructed human epidermis (RHE) were subjected to dehydration and pollution stress in the absence and presence of the formulations. Endpoint measurements included transepithelial electric resistance (TEER), stratum corneum protein expression and lipid contents. Clinical measurements included transepithelial water loss (TEWL), skin pH and the lipid index.

RESULTS

When applied in cream and balm formulations, ADE-G3, increased the TEER in sensitized RHEs. In non-sensitized dehydrated RHEs, both formulations increased recovery of skin barrier integrity after dehydration, evident as a return of the ratios of filaggrin/profilaggrin and caspase-14/procaspase-14 to values measured in control non-stressed RHEs, as well as reducing the 'natural moisturizing factor' to control levels. In clinical studies performed on dry human skin, the formulations helped to maintain and improve the skin barrier function. This was evident as an intense and sustained moisturization (total lipids and lipid esters were increased), an increase in pH and a decrease in the TEWL by both formulations. When exposed to pollution stress by treating the models with benzo[a]pyrene and airborne particulate matter (PM10), application of both formulations prior to exposure attenuated the induction of CYP1A1, CYP1B1 and UGT1A7 expression, indicating a protective effect.

CONCLUSIONS

ADE-G3 cream and balm formulations increased the hydration of the skin but also protected and improved the skin barrier integrity of sensitive skin exposed to dry and cold and airborne pollutant-induced stress environments.

Protective properties of Avène Thermal Spring Water on biomechanical, ultrastructural and clinical parameters of human skin

BACKGROUND

Thermal Spring Water (TSW) has been recognized to have beneficial effects on skin; however, the mechanisms underlying these are not completely elucidated.

AIMS

We compared the effects of Avène TSW with mineral-rich (MR) TSW on the biomechanical properties of the skin using mechanistic ex vivo assays and clinical studies.

METHODS

Ex vivo studies included the effect of both TSWs on the structure of the surface of human skin explants using scanning electron microscopy (SEM); mineral elemental content on the skin surface using SEM coupled to energy dispersing X-ray spectroscopy; and the stress properties of the stratum corneum (SC) when exposed to dehydration. Human clinical studies were conducted to compare the soothing effect of TSWs after a dermatological chemical peeling of face skin and to evaluate the overall sensitive scale of consumers using Avène TSW for 7 days.

RESULTS

Both TSWs preserved surface skin ultrastructure; however, crystals formed from MR-TSW were needle-like and formed small grains, present in clusters heterogeneously spread over the surface. Needle crystals were mainly composed of calcium, while small clusters were mainly composed of sulphur. By contrast, Avène TSW-formed crystals composed of sodium and chlorine only were regular in shape and homogeneously distributed across the skin surface. Peak stress of SC layers was increased by MR-TSW, whereas Avène TSW showed a comparatively reduced effect on dehydration and stress. The difference in the two TSW types was reflected in clinical findings comparing postpeeling redness after TSW application. Avène TSW significantly decreased postpeeling redness, while MR-TSW increased it. The overall sensitive scale of consumers was decreased by 47% using Avène TSW for 7 days.

CONCLUSIONS

Avène TSW decreases postpeeling redness and soothes sensitive skin in human volunteers. Mechanistic studies suggested that differences in biomechanical effects could be linked to differences in calcium content of the TSW.

Broad spectrum repairing properties of an extract of Aquaphilus dolomiae on in vitro and ex vivo models of injured skin

BACKGROUND

A biological concentrate was produced from cultures of an Avène aquatic microflora isolate, namely Aquaphilus dolomiae. Some of the beneficial effects on diseased and damaged skin are thought to be due to the presence of this microorganism.

AIMS

An extract of A. dolomiae (A. dolomiae extract-G2, ADE-G2) was evaluated for its wound-healing effects using in vitro and ex vivo models of injured skin.

METHODS

The effect of ADE-G2 on the proliferation of fibroblasts, migration of keratinocytes and re-epithelialization of ex vivo wounded skin explants was measured. Antimicrobial protection by ADE-G2 was measured by analysing the gene expression of a panel of antimicrobial proteins (AMPs) in keratinocytes (RNASE7, S100A7, DEFB4A/B and DEFb103B), as well as the protein encoded by DEFB4A-B (hBD2) in the medium.

RESULTS

ADE-G2 increased fibroblast proliferation and keratinocyte migration, as well as re-epithelialization of wounded ex vivo skin. ADE-G2 induced the expression of all AMP genes analysed in keratinocytes, as well as stimulated the release in to the medium of hBD2 peptide, encoded by DEFB4A/B.

CONCLUSIONS

We have shown the broad spectrum of the repairing properties of the A. dolomiae extract, ADE-G2. These results support the use of ADE-G2 as a promising component for use in formulations aimed at repairing skin, limiting wound superinfection and preventing complicated wounds.

Protective effect of Aquaphilus dolomiae extract-G1, ADE-G1, on tight junction barrier function in a Staphylococcus aureus-infected atopic dermatitis model

BACKGROUND

Atopic dermatitis (AD) is a common skin disease characterized by recurrent pruritic inflammatory skin lesions and defects of the skin barrier. Bacterial infection with Staphylococcus aureus contributes to increased severity of AD by compromising the barrier further. A microorganism component of Avène Thermal Spring Water, Aquaphilus dolomiae, is thought to contribute to some of its beneficial effects to skin, eg AD alleviation.

AIMS

Here, we have investigated the effects of an extract of A. dolomiae, A. dolomiae extract-G1 (ADE-G1), on the structural barrier function of keratinocytes, tight junction (TJ) protein expression and the expression of several genes altered in AD patients.

METHODS

An epidermal cell culture model mimicking the AD environment and phenotype was used, in which S. aureus-infected cell cultures of normal human epidermal keratinocytes were exposed to a proinflammatory environment. Endpoints measured included the transepithelial electrical resistance (TER) and immunohistological staining of the epidermal TJ proteins, claudin and occludin. Additional analysis was made of several genes known to be differentially regulated in skin from AD patients (C-C motif chemokine ligand 20 (CCL20), interleukin-8 (IL-8), S100 calcium binding protein A7 (S100A7), defensin beta 4 (DEFB4) and filaggrin).

RESULTS

Aquaphilus dolomiae extract-G1 strongly increased TER in non-infected cells and provided protection against infection by overcoming the decrease in TER induced by the infection with S. aureus. In infected cells exposed to a pro-inflammatory environment - depicting AD-like conditions - TER protection by ADE-G1 was still observed. Gene expression analysis of infected and pro-inflammatory stimulated cells indicated that ADE-G1 modulated the inflammatory response (induced IL-8 and attenuated CCL20 expression), increased antimicrobial activities (induced DEFB4 and A100A7) and strengthened barrier function (restored filaggrin expression).

CONCLUSIONS

ADE-G1 reinforces barrier function and strongly protects TJ barrier disruption induced by bacterial infection and inflammation.

Cutaneous sensitivity modulation by Aquaphilus dolomiae extract-G3 on in vitro models of neuro-inflammation

BACKGROUND

Inflammatory skin disorders, including atopic dermatitis (AD), associated pruritus and sensitive skin, have a complex multifactorial pathogenesis including neurogenic inflammation involving the release in blood and skin of neurotransmitters such as substance P (SP).

AIMS AND METHODS

In vitro models evaluated the effect of the original biological extract of Aquaphilus dolomiae extract-G3 (ADE-G3) on cutaneous neurogenic inflammation.

RESULTS

ADE-G3 significantly inhibited SP-stimulated release of IL-1β and TNF-α from normal human epidermal keratinocytes; significantly and dose-dependently inhibited SP-stimulated activation of human mast cells; significantly inhibited veratridine-stimulated release of SP from human sensory neurons; modulated expression of genes involved in lipid synthesis, innate immunity, corneocyte scaffolding and epidermal differentiation in a histamine-sensitized reconstructed human epidermis model; and, when applied topically to ex vivo human explants, inhibited IL-8 and histamine release.

CONCLUSIONS

Topically applied ADE-G3, once formulated, may improve neuro-inflammation in patients with inflammatory skin disorders.

Comparison of the metabolism of 10 chemicals in human and pig skin explants

Skin metabolism is important to consider when assessing local toxicity and/or penetration of chemicals and their metabolites. If human skin supply is limited, pig skin can be used as an alternative. To identify any species differences, we have investigated the metabolism of 10 chemicals in a pig and human skin explant model. Phase I metabolic pathways in skin from both species included those known to occur via cytochrome P450s, esterases, alcohol dehydrogenases and aldehyde dehydrogenases. Common Phase II pathways were glucuronidation and sulfation but other conjugation pathways were also identified. Chemicals not metabolized by pig skin (caffeine, IQ and 4‐chloroaniline) were also not metabolized by human skin. Six chemicals metabolized by pig skin were metabolized to a similar extent (percentage parent remaining) by human skin. Human skin metabolites were also detected in pig skin incubations, except for one unidentified minor vanillin metabolite. Three cinnamyl alcohol metabolites were unique to pig skin but represented minor metabolites. There were notable species differences in the relative amounts of common metabolites. The difference in the abundance of the sulfate conjugates of resorcinol and 4‐amino‐3‐nitrophenol was in accordance with the known lack of aryl sulfotransferase activity in pigs. In conclusion, while qualitative comparisons of metabolic profiles were consistent between pig and human skin, there were some quantitative differences in the percentage of metabolites formed. This preliminary assessment suggests that pig skin is metabolically competent and could be a useful tool for evaluating potential first‐pass metabolism before testing in human‐derived tissues.

We have investigated the metabolism of 10 chemicals in viable pig and human skin. Phase I and II metabolic pathways were present in skin from both species. Chemicals not metabolized by pig skin were also not metabolized by human skin. Six chemicals metabolized by pig skin were also metabolized to a similar extent by human skin. Pig and human skin produced common metabolites, although some species differences were observed and as their relative amounts differed.

Comparison of protocols measuring diffusion and partition coefficients in the stratum corneum

Partition (K) and diffusion (D) coefficients are important to measure for the modelling of skin penetration of chemicals through the stratum corneum (SC). We compared the feasibility of three protocols for the testing of 50 chemicals in our main studies, using three cosmetics-relevant model chemicals with a wide range of logP values. Protocol 1: SC concentration-depth profile using tape-stripping (measures KSC/v and DSC /HSC2 , where HSC is the SC thickness); Protocol 2A: incubation of isolated SC with chemical (direct measurement of KSC/v only) and Protocol 2B: diffusion through isolated SC mounted on a Franz cell (measures KSC/v and DSC /HSC2 , and is based on Fick's laws). KSC/v values for caffeine and resorcinol using Protocol 1 and 2B were within 30% of each other, values using Protocol 2A were ~two-fold higher, and all values were within 10-fold of each other. Only indirect determination of KSC/v by Protocol 2B was different from the direct measurement of KSC/v by Protocol 2A and Protocol 1 for 7-EC. The variability of KSC/v for all three chemicals using Protocol 2B was higher compared to Protocol 1 and 2A. DSC /HSC2 values for the three chemicals were of the same order of magnitude using all three protocols. Additionally, using Protocol 1, there was very little difference between parameters measured in pig and human SC. In conclusion, KSC/v, and DSC values were comparable using different methods. Pig skin might be a good surrogate for human skin for the three chemicals tested. Copyright © 2017 The Authors Journal of Applied Toxicology published by John Wiley & Sons Ltd.

Fragility of epidermis in newborns, children and adolescents

Within their first days of life, newborns' skin undergoes various adaptation processes needed to accommodate the transition from the wet uterine environment to the dry atmosphere. The skin of newborns and infants is considered as a physiological fragile skin, a skin with lower resistance to aggressions. Fragile skin is divided into four categories up to its origin: physiological fragile skin (age, location), pathological fragile skin (acute and chronic), circumstantial fragile skin (due to environmental extrinsic factors or intrinsic factors such as stress) and iatrogenic fragile skin. Extensive research of the past 10 years have proven evidence that at birth albeit showing a nearly perfect appearance, newborn skin is structurally and functionally immature compared to adult skin undergoing a physiological maturation process after birth at least throughout the first year of life. This article is an overview of all known data about fragility of epidermis in 'fragile populations': newborns, children and adolescents. It includes the recent pathological, pathophysiological and clinical data about fragility of epidermis in various dermatological diseases, such as atopic dermatitis, acne, rosacea, contact dermatitis, irritative dermatitis and focus on UV protection.