Effect of Th2 cytokines on ceramide subclasses based on a model of reconstructed human epidermis.

Atopic dermatitis (AD) is associated with chronic inflammation and an altered skin barrier. Lipids of the stratum corneum of AD patients are known to differ substantially in composition from those of healthy subjects. A reconstructed human epidermis (RHE) model has been developed in vitro in order to mimic the characteristics of AD.

Effects of solar radiations on stratum corneum hydration: Part II, protective action of solar filters.

The skin surface lipids (SSLs) film, composed of sebum and keratinocyte membrane lipids, is crucial to the barrier function of the stratum corneum (SC). The first part of this study investigated the impact of solar radiation on the SC based on a novel hydration and dehydration approach using Raman spectroscopy. The SSLs were found to absorb solar light, and thus participate to the protection of the skin surface.

Effects of solar radiations on stratum corneum hydration: Part I, protective role of skin surface lipids.

This study used Raman spectroscopy to develop a new approach to evaluate the effects of solar radiation on the stratum corneum (SC). The method measures the SC's hydration and dehydration kinetics by calculating the vOH/vCH ratio to monitor the relative water content during the drying process. The study also investigated the role of skin surface lipids (SSLs) in protecting the SC from solar radiation.

Characterization of triglycerides photooxidation under solar radiations: A stepwise Raman study.

Triglycerides (TGs) are one of the main components of the glycerolipid family. Their main task in cells is to store excess fatty acids. TG energy storage is mainly concentrated in adipocytes.

Studying the effects of suberythemal UV doses on the human stratum corneum by in vivo confocal Raman spectroscopy.

Background: The stratum corneum (SC) plays an important role in skin barrier function. It acts as a protective barrier against water loss, eliminates foreign substances and micro-organisms and acts against harmful effects of UVR.

Objectives: Our aim was to study the impact of suberythemal doses of UVA and UVB exposure on the molecular structure, organization and barrier function of the SC by following different Raman descriptors.

Stratum corneum ceramide profiles in vitro, ex vivo, and in vivo: characterization of the α-hydroxy double esterified ceramides.

The presence of a new ceramide subclass, the 1-O-acyl omega-linoleoyloxy ceramides [1-O-E (EO) Cer], has been previously highlighted in reconstructed human epidermis (RHE). These ceramides are double esterified on two positions. The first is the 1-O position of the sphingoid base moiety with a long to very long chain of acyl residues (1-O-E), and the second is the position of the ω-hydroxyl group of the fatty acid moiety with linoleic acid (EO).

EBT3 Gafchromic film as a new substrate for in vitro evaluation of sun protection factor.

There exist different methods for the determination of sun protection factor (SPF) values for sunscreens. We aimed to develop a new in vitro method using EBT3 Gafchromic film as a substrate. The colour of EBT3 Gafchromic film changes when exposed to UV light.

Assessment of the skin barrier function in the reconstructed human epidermis using a multimodal approach at molecular, tissue and functional levels.

Reconstructed human epidermis models are used as epidermis alternatives in skin research studies. It is necessary to provide molecular and functional characterization in order to assess these models. Our aim is to establish a link between the barrier function and the structure and composition of the stratum corneum using several complementary techniques.

Biomolecular modifications during keratinocyte differentiation: Raman spectroscopy and chromatographic techniques.

From the basal layer until the stratum corneum, lipid and protein biomarkers associated with morphological changes denote keratinocyte differentiation and characterize each epidermis layer. Herein, we followed keratinocyte differentiation in the early stages using HaCaT cells over a period of two weeks by two complementary analytical techniques: Raman microspectroscopy and high-performance liquid chromatography coupled with high resolution mass spectrometry. A high concentration of calcium in the medium induced HaCaT cell differentiation in vitro.

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

The stratum corneum (SC) is key in the maintenance of the biomechanical barrier and hydration of skin. Our previous investigations showed beneficial effects of a combination of emollients on water capture and retention and protein and lipid organization, all of which are linked to dryness and dry skin damage. Here, we show how a formulation containing an emollient combination ("Trio") and its basal formulation (placebo) impacted the descriptors of SC hydration in SC layers.

The stratum corneum water content and natural moisturization factor composition evolve with age and depend on body site.

Background: The study objective was to examine if age and chronic environmental exposure affect the water content and the composition of the natural moisturizing factors (NMFs) of the stratum corneum (SC).

Methods: Forty healthy Caucasian women 18-70 years of age were recruited. Measurements were done on the cheek and on two skin sites on the arm (one relatively protected and one exposed to environmental factors).

Skin surface lipid composition in women: increased 2,3-oxidosqualene correlates with older age.

The importance of the hydrolipidic film of skin has been well documented, however, few data are available in cases of very old age. Our aim was to characterize the difference in skin surface lipid (SSL) composition between individuals of different age groups. Data were collected from the forehead of 22 young volunteers (18-24 years old) and 18 senior volunteers (70-75 years old).

Nanoscale investigation of human skin and study of skin penetration of Janus nanoparticles.

Janus nanoparticles (JNP) are innovative nanocarriers with an interesting pharmaceutical and cosmetic potential. They are characterized by the presence of a lipid compartment associated with an aqueous compartment delimited by a phospholipid bilayer containing phospholipids and non-ionic surfactants. The hydrodynamic diameter of JNP varies between 150 and 300 nm.

Origanum essential oils reduce the level of melanin in B16-F1 melanocytes.

Background: Hyperpigmentation disorders are considered signs of skin aging and are aesthetically unpleasant. Most active ingredients used against hyperpigmentation disorders predominantly target tyrosinase activity.

Objectives: To study the effect of two Origanum essential oils on the melanogenic activity of B16-F1 murine melanocytes.

Comprehensive characterization and simultaneous analysis of overall lipids in reconstructed human epidermis using NPLC/HR-MS: 1-O-E (EO) Cer, a new ceramide subclass.

Stratum corneum lipids are responsible for the skin's barrier function. They are the final product of epidermis lipid biosynthesis. During this process, lipids evolve from simple to complex structures in three main levels respectively (stratum basal level, stratum granulosum level, and stratum corneum level).

Skin lightening effect of natural extracts coming from Senegal botanical biodiversity.

Background: Skin depigmentation is increasingly oriented toward plant extracts because of harmfulness of depigmenting active ingredients used in cosmetics and dermatology. Reconstructed human pigmented epidermis (RHPE) is the closest in vitro model to human skin and offers the possibility to test the global depigmenting effect of a plant extract. These co-cultures of keratinocytes and melanocytes are the most advanced and newest models for testing depigmentation, and until now very few studies have been done with these cultures.

ATR-FTIR Characterization of Janus Nanoparticles-Part II: Follow-Up Skin Application.

Attenuated total reflection by Fourier transform infrared (ATR-FTIR) was used to implement reliable infrared descriptors over time of Janus nanoparticles (JNP), to follow their behavior before and after cutaneous application. In the last study, ATR-FTIR spectroscopic analysis allowed us to identify the evolution of intensity ratio of ν(C=O) at 1739 cm and δ(H-O-H) at 1639 cm as a spectroscopic descriptor, for JNP before cutaneous application (on the CaF window). This descriptor can be used to follow the physical stability (presence) of nanoparticles over time.

Phytochemical screening and antityrosinase activity of carvacrol, thymoquinone, and four essential oils of Lebanese plants.

Objective: In our study, we aim to explore the ability of four essential oils (EO) of Lebanese plants to inhibit the tyrosinase activity and to correlate their efficiency level to their phytochemical compositions.

Methods: The EO have been extracted by hydrodistillation using a Clevenger apparatus and have been studied by GC-MS analysis. Active compounds of Origanum species were identified and antityrosinase activities of EO and active molecules (carvacrol and thymoquinone) have been tested in tubo.

Clustering-based preprocessing method for lipidomic data analysis: application for the evolution of newborn skin surface lipids from birth until 6 months.

After life in utero and birth, the skin is submitted to an important process of adaptation to a relatively dry gaseous environment. Skin surface lipids (SSLs) contribute actively to the protection of the skin barrier. Within this context, our objective was to study the evolution of each lipid compound during the postnatal period.

Retinoblastoma membrane models and their interactions with porphyrin photosensitisers: An infrared microspectroscopy study.

Fourier Transform Infrared (FTIR) microspectroscopy was used to highlight the interactions between two photosensitisers (PS) of different geometries, TPPmOH4 and a glycoconjugated analogous, TPPDegMan, and lipid bilayers modelling retinoblastoma cell membranes. Retinoblastoma is a rare disease occurring in young infants, for whom conservative treatments may present harmful side-effects. Photodynamic therapy (PDT) is expected to induce less side-effects, as the photosensitiser is only activated when the tumour is illuminated.

Measurement of the biomechanical function and structure of ex vivo drying skin using raman spectral analysis and its modulation with emollient mixtures.

An important aspect of the biomechanical behaviour of the stratum corneum (SC) is the drying stresses that develop with water loss. These stresses act as a driving force for damage in the form of chapping and cracking. Betasitosterol is a plant sterol with a structure similar to cholesterol, a key component in the intercellular lipids of the outermost layer of human skin, the SC.

ATR-FTIR Characterization of Janus Nanoparticles. Part I: Implementation of Spectroscopic Descriptors.

The present work deals with original bicompartmental lipid Janus nanoparticles (JNPs), which are characterized by the presence of an oily compartment associated with an aqueous compartment delimited by a phospholipid-based bilayer. The size of JNP varies between 150 and 300 nm. As JNP are promising candidates for cutaneous application, the purpose of this study was to implement reliable infrared descriptors over time of JNP, to follow the physical stability of JNP in open air and over time.

Optimization of classification and regression analysis of four monoclonal antibodies from Raman spectra using collaborative machine learning approach.

The use of monoclonal antibodies (mAbs) constitutes one of the most important strategies to treat patients suffering from cancers such as hematological malignancies and solid tumors. These antibodies are prescribed by the physician and prepared by hospital pharmacists. An analytical control enables the quality of the preparations to be ensured.

Labeling of Hyaluronic Acids with a Rhenium-tricarbonyl Tag and Percutaneous Penetration Studied by Multimodal Imaging.

Hyaluronic acids were labeled with a rhenium-tricarbonyl used as single core multimodal probe for imaging and their penetration into human skin biopsies was studied using IR microscopy and fluorescence imaging (labeled SCoMPI). The penetration was shown to be dependent on the molecular weight of the molecule and limited to the upper layer of the skin.