When developing new cosmetics, it is extremely important to consider the safety of consumers. Absence of potential irritancy is generally assessed using an OECD TG439 compliant Reconstructed Human ...Epidermis (RHE) systems and MTT assays, resulting in an irritant/not irritant classification. To gain insight into the irritancy of molecules/finished cosmetic products and to predict the outcome of irritation tests performed on subjects whatever their nature, we developed a test that uses skin explants and histological analysis. Results showed that this irritation test is sensitive enough to accurately and repeatably detect known irritants. If the diverse origin of the skin explants used led to variability in the histological alterations scored, the overall grading of irritancy is highly reproducible. Finally, when testing 120 non-alcoholic cosmetics of various galenic forms, comparison of data between the ex vivo irritation tests and of a 24-/48-h human patch test revealed a single false negative, very close to the limit, and a 10% false positive rate. It was not possible to calculate the sensitivity of the ex vivo irritation test; however, its specificity was 89.9% and its accuracy was 89.1%. Similar results, with a slightly higher false positive rate, were found when testing 49 alcoholic cosmetics. These values exceed the minimum requirements of OECD TG439.
•We developed an irritation test using skin explants and histological analysis.•The test is sensitive enough to accurately and repeatably detect known irritants.•Despite diverse origin of explants, grading of irritancy is highly reproducible.•Comparison to human patch test, shows high specificity and accuracy.
Skin is being increasingly exposed to artificial blue light due to the extensive use of electronic devices, which can induce cell oxidative stress, causing signs of early photo aging. The Melissa ...officinalis phytocomplex is a new standardized cosmetic ingredient obtained by an in vitro plant cell culture with a high content of rosmarinic acid. In this study, we examine the activity of the Melissa officinalis phytocomplex to protect skin against blue light and infrared damages, evaluating the ROS (Radical Oxygen Species) level in keratinocyte cell line from human skin (HaCaT) and Nrf2 (Nuclear factor erythroid 2-related factor 2), elastin, and MMP1 (Matrix Metalloproteinase 1) immunostaining in living human skin explants ex vivo. This phytocomplex demonstrates antioxidant activity by reducing ROS production and thus the oxidant damage of the skin caused by UV and blue light exposure. In addition, it inhibits blue light-induced Nrf2 transcriptional activity, IR-induced elastin alteration, and IR-induced MMP-1 release. This Melissa officinalis phytocomplex is a new innovative active ingredient for cosmetic products that is able to protect skin against light and screen exposure damages and oxidative stress.
Air pollution is a growing threat to human health. Airborne pollution effects on respiratory, cardiovascular and skin health are well-established. The main mechanisms of air-pollution-induced health ...effects involve oxidative stress and inflammation. The present study evaluates the potential of a polyphenol-enriched food supplement ingredient comprising
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,
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extracts in mitigating the adverse effects of environmental pollution on skin and cardiopulmonary systems. Both in vitro and ex vivo studies were used to assess the blend's effects against pollution-induced damage. In these studies, the botanical blend was found to reduce lipid peroxidation, inflammation (by reducing IL-1α), and metabolic alterations (by regulating MT-1H, AhR, and Nrf2 expression) in human skin explants exposed to a mixture of pollutants. Similar results were also observed in keratinocytes exposed to urban dust. Moreover, the ingredient significantly reduced pollutant-induced ROS production in human endothelial cells and lung fibroblasts, while downregulating the expression of apoptotic genes (bcl-2 and bax) in lung fibroblasts. Additionally, the blend counteracted the effect of urban dust on the heart rate in zebrafish embryos. These results support the potential use of this supplement as an adjuvant method to reduce the impact of environmental pollution on the skin, lungs, and cardiovascular tissues.
Photobiomodulation (PBM) is rapidly gaining traction as a valuable tool in dermatology for treating many inflammatory skin conditions using low levels of visible light or near-infrared radiation. ...However, the physiological regulatory pathways responsible for the anti-inflammatory effect of PBM have not been well defined. Since previous studies showed that nuclear factor-erythroid 2 like 2 (Nrf2) is a master regulator of the skin inflammatory response, we have addressed its role in controlling inflammation by PBM. Primary human keratinocytes (KCs) stimulated with 2,4-dinitrochlorobenzene (DNCB) to mimic pro-inflammatory stress were illuminated with two wavelengths: 660 nm or 520 nm. Both lights significantly reduced the mRNA expression of the DNCB-triggered
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cytokines in KCs, while they enhanced Nrf2 pathway activation. PBM-induced Nrf2 is a key regulator of the inflammatory response in KCs since its absence abolished the regulatory effect of light on cytokines production. Further investigations of the mechanisms contributing to the immunoregulatory effect of PBM in inflamed human skin explants showed that 660 nm light prevented Langerhans cells migration into the dermis, preserving their dendricity, and decreased pro-inflammatory cytokine production compared to the DNCB-treated group. This study is the first to report that the PBM-mediated anti-inflammatory response in KCs is Nrf2-dependent and further support the role of PBM in skin immunomodulation. Therefore, PBM should be considered a promising alternative or complementary therapeutic approach for treating skin-related inflammatory diseases.
•Exposure of human skin explants to urban pollutant mixture via the Pollubox® chamber.•Skin alterations were recorded down to the stratum basale.•Pollutant exposure induces relevant xenobiotic and ...anti-oxidant responses.•The model developed herein is able to test anti-pollutant cosmetic products.
The skin epidermis is continuously exposed to external aggressions, including environmental pollution. The cosmetic industry must be able to offer dedicated products to fight the effects of pollutants on the skin. We set up an experimental model that exposed skin explants maintained in culture to a pollutant mixture. This mixture P representing urban pollution was designed on the basis of the French organization ‘Air Parif’ database. A chamber, called Pollubox®, was built to allow a controlled nebulization of P on the cultured human skin explants. We investigated ultrastructural morphology by transmission electron microscopy of high pressure frozen skin explants. A global transcriptomic analysis indicated that the pollutant mixture was able to induce relevant xenobiotic and antioxidant responses. Modulated detoxifying genes were further investigated by laser micro-dissection coupled to qPCR, and immunochemistry. Both approaches showed that P exposure correlated with overexpression of detoxifying genes and provoked skin physiological alterations down to the stratum basale. The model developed herein might be an efficient tool to study the effects of pollutants on skin as well as a powerful testing method to evaluate the efficacy of cosmetic products against pollution.
Background: Accumulation of advanced glycation end-products (AGEs) in skin has been associated with skin aging. Inhibition of glycation of proteins of extracellular matrix may help skin texture and ...appearance. The objective of the study was to demonstrate the antiglycation activity of topically applied carnosine and novel facial cream (FC) containing carnosine in human skin explants ex vivo. Methods: Glycation was induced in human skin explants by methylglyoxal (MG) in culture media. FC containing carnosine (FC-CARN) or carnosine in aqueous solution (AQ-CARN) was applied topically on skin explants. Levels of AGEs carboxymethyl-lysine (CML) and pentosidine were determined in the epidermis and dermis of skin sections and were used to calculate antiglycation activity. Results: Exposure to MG led to increases in CML and pentosidine in skin explants. Antiglycation effect for AQ-CARN was CML: –64 and –41%, pentosidine: –48 and 42% in epidermis and reticular dermis respectively. Antiglycation effect for FC-CARN was CML: –150 and –122%, pentosidine: –108 and –136%, in epidermis and reticular dermis respectively. Conclusion: Topically applied carnosine protects against the glycation induced by MG. Novel FC-CARN significantly reduced levels of AGEs in both epidermis and reticular dermis in human skin explants.
Hyaluronic acid (HA) is a popular ingredient in topical formulations for cosmetic improvement of the skin. Most formulations contain linear, non-crosslinked HA oligomers, low molecular weight (LMW) ...HA, and/or high molecular weight (HMW) HA. Crosslinking of HA enhances its clinical longevity and mechanical characteristics. The objective of this study was to characterize the topical effects of a new, crosslinked resilient HA (RHA) that is also available as a cohesive, tissue-integrating injectable filler, compared with non-crosslinked HMW HA and LMW HA. Living human skin explants that preserve the 3-dimensional structure of in vivo skin were used to maximize clinical relevance.
Standardized doses of each HA product were applied daily for 9 days to human skin explant surfaces. Untreated explants served as controls. Water content of the stratum corneum and entire epidermis was analyzed by Raman spectroscopy. Transepidermal water loss (TEWL) was measured to assess skin barrier function. Explant morphology and microrelief were evaluated by optical and scanning electron microscopy.
Crosslinked RHA achieved a significant increase in epidermal water content (7.6%) over the control. Spectral cartography confirmed a higher epidermal water content with RHA than with HMW HA or LMW HA. TEWL was reduced by 27.8% with RHA, and by 15.6% with HMW HA, but increased by 55.5% with LMW HA. Cutaneous microrelief improved with RHA. Corneocyte cohesion improved with RHA and HMW HA.
This comparative, multimodal study demonstrated greater benefits of topical crosslinked RHA over linear HMW HA or LMW HA in reducing TEWL, retaining and redistributing water within the epidermis, maintaining skin integrity, and improving skin barrier structure and function. RHA was a more efficacious humectant than LMW HA, and a more efficacious occlusive moisturizer than HMW HA. These integrative epidermal repair activities are of significant value for addressing primary deficits of aging skin, improving tolerance to retinoids and other topical agents, and optimizing procedural outcomes. A combination of topical and injectable HA provides an elegant model of synergistic, multi-level skin restoration.
Synopsis
Glycation is an ageing reaction of naturally occurring sugars with dermal proteins, whose clinical signs may appear in vivo around age 30, and increases steadily/regularly with age. The ...suppleness of the dermis is affected by the formation of bridges between proteins and sugars (Maillard’s reaction). The residues formed (Amadori products, Advanced Glycation End products) as well as the proteins they alter, can be visualized by specific immunostainings.
Induced in a few days on living skin explants by methylglyoxal, glycation can be prevented by the application of aminoguanidine HCl, the reference anti‐glycation molecule. This model enabled to highlight the anti‐glycation activity of substances of vegetal origin such as puerarin and chlorogenic acid.
Résumé
La glycation est une réaction des sucres avec les protéines dermiques se produisant naturellement au cours du vieillissement dont les signes cliniques peuvent apparaître in vivo vers 30 ans et augmenter régulièrement avec l’âge. La souplesse du derme est affectée par la formation de ponts entre les protéines et les sucres (réaction de Maillard). Les résidus formés (Produits Amadori, Advanced Glycation End Produits) ainsi que les protéines altérées peuvent être visualisés par un immuno marquage spécifique. Induite par du methyl glyoxal pendant plusieurs jours sur des explants de peau humaine, la glycation peut être empêchée par application d’aminoguanidine HCl, la molécule anti‐glycation de référence. Ce modèle a permis de mettre en évidence l’activité anti‐glycation de substances d’origine végétale Comme la puérarine et l’acide chlorogénique.
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