The aim of this study is to quantify D. folliculorum colonisation in rosacea subtypes and age-matched controls and to determine the relationship between D. folliculorum load, rosacea subtype and skin innate immune system activation markers. We set up a multicentre, cross-sectional, prospective study in which 98 adults were included: 50 with facial rosacea, including 18 with erythematotelangiectatic rosacea (ETR), and 32 with papulopustular rosacea (PPR) and 48 age- and sex-matched healthy volunteers. Non-invasive facial samples were taken to quantify D. folliculorum infestation by quantitative PCR and evaluate inflammatory and immune markers. Analysis of the skin samples show that D. folliculorum was detected more frequently in rosacea patients than age-matched controls (96% vs 74%, P < 0.01). D. folliculorum density was 5.7 times higher in rosacea patients than in healthy volunteers. Skin sample analysis showed a higher expression of genes encoding pro-inflammatory cytokines (Il-8, Il-1b, TNF-a) and inflammasome-related genes (NALP-3 and CASP-1) in rosacea, especially PPR. Overexpression of LL-37 and VEGF, as well as CD45RO, MPO and CD163, was observed, indicating broad immune system activation in patients with rosacea. In conclusion, D. folliculorum density is highly increased in patients with rosacea, irrespective of rosacea subtype. There appears to be an inverse relationship between D. folliculorum density and inflammation markers in the skin of rosacea patients, with clear differences between rosacea subtypes.

Sunscreens, whose main function is to protect the skin against the harmful effects of solar irradiation, should remain at the skin surface or impregnate the first layers of the stratum corneum only and not penetrate into the underlying living tissue. The goal of this work was to assess the penetration of titanium dioxide (TiO₂) and methylene bis-benzotriazoyl tetramethylbutylphenol (MBBT), included in a broad-spectrum sunscreen formulation, into human skin in vivo, using the tape stripping method, and in vitro, using a compartmental approach. An additional objective was to propose an easy and minimally invasive approach to determining the percutaneous uptake of sunscreens following topical application. TiO₂ and MBBT were quantified using colorimetric assay and HPLC analysis, respectively. The transmission electron microscopy and particle-induced X-ray emission techniques were used to localize the TiO₂ in skin sections.More than 90% of both sunscreens was recovered in the first 15 tape strippings. In addition we have shown that the remaining 10% did not penetrate the viable tissue, but was localized in the furrows and in the opened infundibulum. Less than 0.1% of MBBT was detected in the receptor medium, and no TiO₂ was detected in the follicle, viable epidermis or dermis. Thus, this in vivo and in vitro penetration study showed an absence of TiO₂ penetration into the viable skin layers through either transcorneal or transfollicular pathways and negligible transcutaneous absorption of MBBT. However, differences in distribution within the stratum corneum reinforced the need for a complementary approach, using minimally invasive in vivo methodology and in vitro compartmental analysis.This combination represents a well-adapted method for testing the safety of topically applied sunscreen formulations in real-life conditions.

Atopic dermatitis (AD) is a multifactorial chronic inflammatory disease mainly stemming from a genetic predisposition that leads to hypersensitivity to environmental factors and a common involvement of Staphylococcus aureus (SA) colonization. The aim of this work was to propose a new non-invasive approach to enumerate the genes coding for the toxins of SA in atopic skin samples. In parallel, the study aimed to evaluate the change in AD through 3 markers of the inflammatory response: IL-8, IL-1RA/IL-1α and IL-18. These methods were tested on 31 patients with AD, and finally on a group of 19 subjects for whom clinical improvement had been reported after various treatments. The study revealed the presence of a large number of genes encoding toxins in atopic samples, indicating a high rate of SA colonization, and also an increase in the level of all cytokine markers in atopic skin compared to the skin of healthy subjects. Finally, we found a positive correlation between increases in the SCORAD (Scoring Atopic Dermatitis Index) value after treatment and the corresponding evolution of the SA density. These methods provide a means to clinically evaluate the course of AD, and may help in the development of potential treatments.

Dandruff/seborrhoeic dermatitis (D/SD) is characterized by Malassezia colonization, impaired barrier function with subsequent inflammation, resulting in dandruff and itching. Histamine is one of the biomarkers of pruritus now widely used in treatment efficacy trials. The exact mechanism leading to histamine release and pruritus is not yet clear. However, it could involve cathepsin S, an activator of proteinase-activated receptor 2 (PAR2). The purpose of this study was to evaluate the levels of cathepsin S, PAR2 and histamine in patients with D/SD compared with healthy subjects through non-invasive sampling of the scalp and to correlate those markers with D/SD clinical parameters. A significant increase in the three biological markers was observed in the D/SD group versus healthy subjects, and those markers were correlated with clinical parameters. In conclusion, cathepsin S could be a potential marker of pruritus in D/SD and could help assessing the effect of treatments.

IntroductionFew studies have investigated the long-term effects of a maintenance regimen in the prevention of relapses in scalp seborrheic dermatitis (SD), in particular following biomarker changes.Materials and methodsA new shampoo containing beta-glycyrrhetinic acid (18βGA) in addition to cyclopiroxolamine (CPO) and zinc pyrithione (ZP) was tested in 67 subjects suffering from SD with moderate to severe erythema and itching in a biphasic study. After a first common intensive treatment phase (investigational product thrice a week × 2 weeks), subjects randomly received the investigational product once a week × 8 weeks (maintenance) or a neutral shampoo (discontinuation) in a comparative, parallel group maintenance phase. Efficacy was assessed clinically (overall clinical dandruff score, erythema, overall efficacy, self-evaluation), biochemically and microbiologically by quantitative polymerase chain reaction (qPCR), high performance liquid chromatography (HPLC) or enzyme-linked immunoabsorbent assay (ELISA) analysis of scale samples (Malassezia species (restricta and globosa), cohesion proteins (plakoglobins), inflammation (Interleukin (IL)-8, IL-1RA/IL-1α) and pruritus (histamine, cathepsin S) markers).ResultsDuring the intensive treatment phase, SD improved significantly (p < 0.0001) with a decrease in clinical signs as well as Malassezia species, cohesion proteins, inflammation and pruritus markers. During the maintenance phase, the improvement persisted in the ‘maintenance’ group only, with a significant intergroup difference. A consistently positive relationship was found between dandruff, itching, erythema and Malassezia populations, histamine levels and IL-1RA/IL-1α ratio.ConclusionThe effectiveness of this maintenance regimen was objectively demonstrated at the clinical, biochemical and microbiological level. Correlations between clinical signs and biomarkers could provide clues to explain the resolution of SD and confirm the interest of biomarkers for SD treatment assessment.Electronic supplementary materialThe online version of this article (doi:10.1007/s13555-014-0047-0) contains supplementary material, which is available to authorized users.