Reflectance confocal microscopy (RCM) may help to quantify variations of skin pigmentation induced by different stimuli such as UV radiation or therapeutic intervention. The objective of our work was to identify RCM parameters able to quantify in vivo dermis papilla density and epidermis pigmentation potentially applicable in clinical studies. The study included 111 healthy female volunteers with phototypes I-VI. Photo-exposed and photo-protected anatomical sites were imaged. The effect of age was also assessed. Four epidermis components were specifically investigated: stratum corneum, stratum spinosum, basal epidermal layer and dermo-epidermal junction. Laser power, diameter of corneocytes and upper spinous keratinocytes, brightness of upper spinous and interpapillary spinous keratinocytes, number of dermal papillae and papillary contrast were systematically assessed. Papillary contrast measured at the dermo-epidermal junction appeared to be a reliable marker of epidermis pigmentation and showed a strong correlation with skin pigmentation assessed clinically using the Fitzpatrick's classification. Brightness of upper spinous and interpapillary spinous keratinocytes was not influenced by the skin phototype. The number of dermal papillae was significantly lower in subjects with phototypes I-II as compared with darker skin subjects. A dramatic reduction in the number of dermal papillae was noticed with age, particularly in subjects with fair skin. The method presented here provides a new in vivo investigation tool for quantification of dermis papilla density and epidermal pigmentation. Papillary contrast measured at the dermo-epidermal junction may be selected as a marker of skin pigmentation for evaluation in clinical studies.

International audience(Pt-€“Pt-Ag/AgCl) and (Au-€“Pt-€“Ag/AgCl) electrochemical microcells (ElecCell) were developed for the detection of redox species by cyclic voltammetry. A special emphasis was placed on the SU-8 waferlevel passivation process in order to optimize the electrochemical properties of the different “thin film” metallic layers, i.e. gold or platinum for the working electrode, platinum for the counter electrode and silver/silver chloride for the reference electrode. (Au–Pt–Ag/AgCl) microcells were applied for the detection of antioxidant species such as ascorbic and uric acids in phosphate buffer solution, evidencing high sensitivity but low selectivity. Works were extended to skin analysis, demonstrating that a good electrical contact with the skin hydrolipidic film allowed the effective evaluation of the skin global antioxidant capacity

The cyclobutane pyrimidine dimer (CPD) is a potentially mutagenic DNA photolesion that is the basis of most skin cancers. There are no data on DNA protection by sunscreens under typical conditions of use. The study aim was to determine such protection, in phototypes I/II, with representative sunscreen-user application. A very high SPF formulation was applied at 0.75, 1.3 and 2.0 mg/cm2. Unprotected control skin was exposed to 4 standard erythema doses (SED) of solar simulated UVR, and sunscreen-treated sites to 30 SED. Holiday behaviour was also simulated by UVR exposure for 5 consecutive days. Control skin received 1 SED daily, and sunscreen-treated sites received 15 (all 3 application thicknesses) or 30 (2.0 mg/cm2) SED daily. CPD were assessed by quantitative HPLC-tandem mass spectrometry (HPLC-MS/MS) and semi-quantitative immunostaining. In comparison with unprotected control sites, sunscreen significantly (p ≤ 0.001-0.05) reduced DNA damage at 1.3 and 2.0 mg/cm2 in all cases. However, reduction with typical sunscreen use (0.75 mg/cm2) was non-significant, with the exception of HPLC-MS/MS data for the 5-day study (p <0.001). Overall, these results support sunscreen use as a strategy to reduce skin cancer, and demonstrate that public health messages must stress better sunscreen application to get maximal benefit.

BackgroundChronic hand eczema (CHE) is the most common skin disorder affecting the hands. It causes major physical and psychological burden for patients. Classification of CHE remains challenging because of its aetiological and clinical heterogeneity.ObjectivesUsing latent class analysis (LCA) on a large categorical data set, our aim was to identify distinct phenotypes in a cohort of unselected CHE patients based upon clinical, genetic, molecular and physical parameters of the affected skin.MethodsWe performed two independent LCA on a cohort of 71 well‐characterized patients that initially integrated clinical severity, total immunoglobulin E plasma level, transepidermal water loss, hydration index, interleukin(IL)‐8 lesional skin level, Staphylococcus (aureus and epidermidis) colonization, FLG genotype and the expression (mRNA) of genes involved either in the filaggrin degradation and the natural moisturizing factor synthesis, the cornified envelope formation, the tight junctions’ structure and the desquamation process, or encoding antimicrobial peptides and chemokines.ResultsThe first LCA categorized patients into a group displaying high severity of CHE, high skin barrier impairment, high Staphylococcus colonization, high IL‐8 skin level and high frequency of mutation in the FLG gene and a second group with opposite characteristics. The second LCA identified two independent groups of patients categorized by their low or high level of skin barrier impairment and corresponding changes in the expression of the related genes.ConclusionsOur study suggests that the degree of skin barrier dysfunction is the most important parameter to discriminate CHE patients and probably plays a pivotal role in the pathogenesis of the disease whatever the aetiological factors. As far as we know, this is the first study to address this topic using a statistical categorization method without preconception.

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