Proteomic and transcriptomic investigation of acne vulgaris microcystic and papular lesions: Insights in the understanding of its pathophysiology.

BACKGROUND: The pathogenesis of acne vulgaris involves several phases including androgen-dependent hyper-seborrhea, colonization by Propionibacterium acnes, and inflammation. Recent investigations have shown that in fact P. acnes provokes the activation of the inflammasome present in macrophages and dendritic cells. This signaling pathway leads to excessive production of interleukin IL-1ß, a proinflammatory cytokine. Nevertheless, these well-studied phenomena in acne fail to elucidate the mechanisms responsible for the appearance of different lesions. METHODS: We investigate response pathways for specific acne lesions such as microcysts and papules using shot-gun proteomic followed by systemic biology and transcriptomic approaches. RESULTS: Results show that most of the proteins identified as differentially expressed between the normal and acne tissue biopsies associated with the immune system response were identified as highly or exclusively expressed in the papule biopsies. They were also expressed in microcysts, but in lower amounts compared to those in papules. These results are supported by the identification of CAMP factor protein produced by P. acnes in microcysts, indicating its enhanced proliferation in this type of lesion CONCLUSIONS: As CAMP factor protein was not detected in papule biopsies, we can see a clear delineation in the stages of progression of acne pathogenesis, which begins with a hyphenated inflammatory response in the papule stage, followed by imbalance of lipid production, which in turn triggers the enhanced proliferation of P. acnes. GENERAL SIGNIFICANCE: We demonstrate that expression inflammation varies across the two types of lesions, suggesting different pathways enhanced as a function of the progression of P. acnes.

Effects of a New Emollient-Based Treatment on Skin Microflora Balance and Barrier Function in Children with Mild Atopic Dermatitis.

BACKGROUND/OBJECTIVES: The use of emollients is widely recommended for the management of atopic dermatitis (AD), especially between flares. An imbalance of skin microflora is suspected of playing a key role in exacerbations of AD. Our aim was to evaluate the effect of a new emollient balm on clinical parameters (SCORing Atopic Dermatitis [SCORAD], xerosis, pruritus), skin barrier function (transepidermal water loss and loricrin, filaggrin, corneodesmosin, and involucrin expression], skin microflora biodiversity, and Staphylococcus aureus and Staphylococcus epidermidis balance in children with mild AD. METHODS: Fifty-four children (1-4 yrs old) were enrolled in this randomized, controlled study. Subjects applied a hygiene product and the emollient balm (emollient group, n = 28) or the hygiene product only (control group, n = 26) twice a day for 28 days. RESULTS: We found improvement in favor of the emollient group in SCORAD (p < 0.001), pruritus (p = 0.06), and xerosis (p = 0.06) after 28 days of application. Moreover, transepidermal water loss decreased in the emollient group by 34% (p = 0.06) and involucrin expression by 37% (p = 0.001) at day 28 from baseline in association with improvement in barrier function, whereas other barrier-specific proteins did not vary. S. aureus increased significantly in the control group only (6.5 times, p = 0.01), whereas S. epidermidis remained stable in both groups. The Shannon index (H' = 2.3) did not vary with treatment in either group. CONCLUSION: Twice-daily application of a new emollient balm in children with mild AD protected the skin from S. aureus proliferation and preserved microflora biodiversity.

Effects of the Staphylococcus aureus and Staphylococcus epidermidis Secretomes Isolated from the Skin Microbiota of Atopic Children on CD4+ T Cell Activation.

Interactions between the immune system and skin bacteria are of major importance in the pathophysiology of atopic dermatitis (AD), yet our understanding of them is limited. From a cohort of very young AD children (1 to 3 years old), sensitized to Dermatophagoides pteronyssinus allergens (Der p), we conducted culturomic analysis of skin microbiota, cutaneous transcript profiling and quantification of anti-Der p CD4+ T cells. This showed that the presence of S. aureus in inflamed skin of AD patients was associated with a high IgE response, increased expression of inflammatory and Th2/Th22 transcripts and the prevalence of a peripheral Th2 anti-Der p response. Monocyte-derived dendritic cells (moDC) exposed to the S. aureus and S. epidermidis secretomes were found to release pro-inflammatory IFN-γ and anti-inflammatory IL-10, respectively. Allogeneic moDC exposed to the S. aureus secretome also induced the proliferation of CD4+ T cells and this effect was counteracted by concurrent exposure to the S. epidermidis secretome. In addition, whereas the S. epidermidis secretome promoted the activity of regulatory T cells (Treg) in suppressing the proliferation of conventional CD4+ T cells, the Treg lost this ability in the presence of the S. aureus secretome. We therefore conclude that S. aureus may cause and promote inflammation in the skin of AD children through concomitant Th2 activation and the silencing of resident Treg cells. Commensals such as S. epidermidis may counteract these effects by inducing the release of IL-10 by skin dendritic cells.

Cathepsin S, a new pruritus biomarker in clinical dandruff/seborrhoeic dermatitis evaluation.

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.

Clinical and biochemical assessment of maintenance treatment in chronic recurrent seborrheic dermatitis: randomized controlled study.

INTRODUCTION: Few 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 METHODS: A new shampoo containing beta-glycyrrhetinic acid (18ßGA) 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). RESULTS: During 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. CONCLUSION: The 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.

Association between collagen production and mechanical stretching in dermal extracellular matrix: in vivo effect of cross-linked hyaluronic acid filler. A randomised, placebo-controlled study.

BACKGROUND: The effects of hyaluronic acid (HA) injection on tissue collagen anabolism are suggested to be related to the induction of mechanical stress, causing biochemical changes in skin physiology. OBJECTIVES: To ascertain the association between dermal mechanics modulated by a hyaluronic acid-based filler effect and metabolism. METHODS: Sixty females were randomised to receive a 0.5mL injection of HA gel or isotonic sodium chloride (control) in the arm. Skin biopsies were taken at baseline and after 1, 3 and 6 months. Protein and gene expression of procollagen, matrix metalloproteinases (MMP) and MMP tissue inhibitors (TIMP1) were measured blind by ELISA and qPCR, respectively. Injected volumes were measured by high-frequency ultrasound and radiofrequency analysis. Skin layer effects of injections were analysed by finite element digital modelling. RESULTS: One month after injection, the filler induced an increase in procollagen (p=0.0016) and TIMP-1 (p=0.0485) levels and relative gene expression of procollagen III and I isoforms compared with the controls. After 3 months, procollagen levels remained greater than in the controls (p=0.0005), whereas procollagen expression and TIMP-1 and MMP content were no longer different. Forty-three percent of the injected filler volume was found at 1 month, 26% after 3 months and 20% after 6 months. LIMITATIONS: The ultrasound imaging technique limited the scope of the investigation and precluded an evaluation of the action of the filler at the hypodermic level. CONCLUSIONS: Integrating both mechanical and biological aspects, our results suggest that mechanical stress generated by cross-linked HA plays a role in dermal cell biochemical response.

Quantification of Demodex folliculorum by PCR in rosacea and its relationship to skin innate immune activation.

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.

Exploration of the global antioxidant capacity of the stratum corneum by cyclic voltammetry.

Cyclic voltammetry is proposed as a new method for evaluating the antioxidant capacity of skin based on the reducing properties of low molecular weight antioxidants (LMWA). Experiments were performed simply by recording the anodic current at 0.9 V/SCE of a platinum microelectrode placed directly on the epidermis surface without any gel or water. This method ensured a direct, rapid (less than 1 min), reliable (accuracy 12%) and non-invasive measurement of the global antioxidant capacity of the stratum corneum with a high spatiotemporal resolution. At the same time, the pH of the skin surface was determined by recording the cathodic current at 0 V/SCE. Based on an exploratory study involving nine volunteer subjects, the evolution of the amperometric response of the microelectrode with time revealed a periodic modification of the redox properties.

Slow internal release of bioactive compounds under the effect of skin enzymes.

A new strategy for the skin delivery of bioactive compounds has been developed, using enzymes involved in the maintenance of the epidermal barrier function and the enzymatic transformation of corresponding precursors. This new strategy has been tested with regard to two enzymatic activities of the skin barrier: extracellular glucosidase and esterase/lipase. An analysis of the requirements for the glycosidic bond hydrolysis of any glycoconjugate by beta-glucocerebrosidase indicates that the release of the moiety linked to the glucose unit is obtained as long as the glycosidic bond being broken is not hindered, and as long as the leaving group property of the released moiety is good enough. This strategy was first applied to the release of the antioxidant delta-tocopherol. It was then extended to retinoic acid by introducing a spacer between the glucose unit and the bioactive moiety. This spacer was either a good leaving group such as hydroquinone, or a structure akin to a ceramide, namely glycerol. In these conditions, beta-glucocerebrosidase releases the complex spacer-active compound that is cleaved by an esterase. One of the advantages of this strategy lies in the slow release of the bioactive compound, extending in time its effect and most likely its tolerance, as is the case for retinoic acid.