Effects of psychological stress on the emission of volatile organic compounds from the skin

International audienceThirty-five women were included in a clinical study to characterize the volatile organic compounds (VOCs) emitted by the skin during exposure to psychological stress. An original silicon-based polymeric phase was used for VOC sampling on the forehead before and after stress induction. Cognitive stress was induced using specialized software that included a chronometer for semantic and arithmetic tasks. Assessment of stress was monitored using a State-trait anxiety inventory questionnaire, analysis of participants’ verbal expressions and clinical measurements. Identification and relative quantification of VOCs were performed by gas chromatography-mass spectrometry. Stress induction was validated by a significant increase in state-anxiety as indicated by the questionnaire, modifications in electrodermal activity measurements and the expression of stress verbatims. In parallel, a sebum production increase and a skin pH decrease were observed. A total of 198 VOCs with different potential sources were identified. They were categorized in 5 groups: probable cosmetic composition, VOCs produced by the body or its microbiota, environmental origin, and dietary intake. In our qualitative statistical approach, three VOCs were found to be correlated with stress induction and 14 compounds showed significance in the paired Wilcoxon test. Fatty-acyls derived from lipids were predominantly identified as well as ethylbenzenes

In elderly Caucasian women, younger facial perceived age correlates with better forearm skin microcirculation reactivity

International audienc

Influence of the environmental relative humidity on the inflammatory response of skin model after exposure to various environmental pollutants

International audienceThe skin is an essential barrier, protecting the body against the environment and its numerous pollutants. Several environmental pollutants are known to affect the skin, inducing premature aging through mechanisms including oxidative stress, inflammation, and impairment of skin functions. Even climate conditions can impact the skin. Therefore, using a Reconstructed Human Epidermis (RHE), we tested the effect of two samples of fine particulate matters (PM0.3-2.5 – one metals-rich sample and the other organic compounds-rich), two Volatile Organic Compounds mixtures (VOCs – from a solvent-based paint and a water-based paint) and Tobacco Smoke (TS). All pollutants affected cellular functionality, but to a lesser extent for the water-based paint VOC. This effect was enhanced when RHE were preconditioned for 2 h by a semi-dry airflow (45% relative humidity) before pollutants application, compared to preconditioning by a humid airflow (90% relative humidity). In the absence of preconditioning, IL-1α, IL-6, IL-8, and RANTES were almost systematically induced by pollutants. When RHE were preconditioned by a semi-dry or humid airflow before being subjected to pollutants, the increase of IL-1α, IL-8, and RANTES falls into two groups. Similarly to RHE not treated with pollutants, RHE treated with VOCs after preconditioning by a semi-dry airflow showed increased IL-1α, IL-8, and RANTES release. On the contrary, RHE treated with PM or TS after preconditioning by a semi-dry airflow show a lower increase in IL-1α, IL-8, and RANTES compared to preconditioning by a humid airflow. The effect of real environmental relative humidity conditions of the air, combined with acute exposure to various environmental pollutants, seemed to relate mainly to structural changes of the skin, determining the outcome of the inflammatory response depending on the physicochemical characteristics of pollutants

Road‐traffic‐related air pollution contributes to skin barrier alteration and growth defect of sensory neurons

International audienceAbstract The effects of air pollution on health are gaining increasing research interest with limited data on skin alterations available. It was suggested that air pollution is a trigger factor for sensitive skin (SS). However, this data was based on surveys with a lack of experimental data. SS is related to altered skin nerve endings and cutaneous neurogenic inflammation. TTe present study was to assess the in vitro effect of particulate matter (PM) on epidermis and nerve ending homeostasis. PM samples were collected according to a validated protocol. Reconstructed human epidermis (RHE, Episkin®) was exposed to PM and subsequently the supernatants were transferred to a culture of PC12 cells differentiated into sensory neurons (SN). Cell viability, axonal growth and neuropeptide‐release were measured. The modulation of the expression of different inflammatory, keratinocytes differentiation and neurites growth markers was assessed. PM samples contained a high proportion of particles with a size below 1 μm and a complex chemical composition. Transcriptomic and immunohistochemical analyses revealed that PM altered keratinocytes terminal differentiation and induced an inflammatory response. While viability and functionality of the SN were not modified, their outgrowth was significantly decreased after incubation with PM‐exposed Episkin® supernatants. This was closely related to the modification of nerve growth factor/semaphorin 3A balance. This study showed that air pollutants have negative effects on keratinocytes and sensory nerve endings including inflammatory responses. These effects are probably involved in the SS pathophysiology and might be involved in inflammatory skin disorders

Estrogens induce rapid cytoskeleton re-organization in human dermal fibroblasts via the non-classical receptor GPR30.

The post-menopausal decrease in estrogen circulating levels results in rapid skin deterioration pointing out to a protective effect exerted by these hormones. The identity of the skin cell type responding to estrogens is unclear as are the cellular and molecular processes they elicit. Here, we reported that lack of estrogens induces rapid re-organization of the human dermal fibroblast cytoskeleton resulting in striking cell shape change. This morphological change was accompanied by a spatial re-organization of focal adhesion and a substantial reduction of their number as evidenced by vinculin and actin co-staining. Cell morphology and cytoskeleton organization was fully restored upon 17β-estradiol (E2) addition. Treatment with specific ER antagonists and cycloheximide respectively showed that the E2 acts independently of the classical Estrogen Receptors and that cell shape change is mediated by non-genomic mechanisms. E2 treatment resulted in a rapid and transient activation of ERK1/2 but not Src or PI3K. We show that human fibroblasts express the non-classical E2 receptor GPR30 and that its agonist G-1 phenocopies the effect of E2. Inhibiting GPR30 through treatment with the G-15 antagonist or specific shRNA impaired E2 effects. Altogether, our data reveal a novel mechanism by which estrogens act on skin fibroblast by regulating cell shape through the non-classical G protein-coupled receptor GPR30 and ERK1/2 activation

Endothelial DLL4 Is an Adipose Depot–Specific Fasting Sensor Regulating Fatty Acid Fluxes

International audienceBackground: Adaptation of fat depots to change in fuel availability is critical for metabolic flexibility and cardiometabolic health. The mechanisms responsible for fat depot-specific lipid sensing and shuttling remain elusive. Adipose tissue microvascular endothelial cells (AT-EC) regulates bidirectional fatty acid fluxes depending on fed or fasted state. How AT-EC sense and adapt to metabolic changes according to AT location remains to be established. Methods: We combined transcriptional analysis of native human AT-EC together with in vitro approaches in primary human AT-EC and in vivo and ex vivo studies of mice under fed and fasted conditions. Results: Transcriptional large-scale analysis of human AT-EC isolated from gluteofemoral and abdominal subcutaneous AT revealed that the endothelium exhibits a fat depot–specific signature associated with lipid handling and Notch signaling enrichment. We uncovered a functional link between metabolic status and endothelial DLL4 (delta-like canonical notch ligand 4), which decreases with fasting. DLL4 regulates fatty acid uptake through nontranscriptional modulation of macropinocytosis-dependent long chain fatty acid uptake. Importantly, the changes in DLL4 expression, in response to energy transition state, is impaired under obesogenic conditions, an early alteration coinciding with a defect in systemic fatty acid fluxes adaptation and a resistance to weight loss. Conclusions: DLL4 is a major actor in the adaptive mechanisms of AT-EC to regulate lipid fluxes. It likely contributes to fat depot-dependent metabolism in response to energy transition states. AT-EC alteration with obesity may favor metabolic inflexibility and the development of cardiometabolic disorders

Coupling of melanocyte signaling and mechanics by caveolae is required for human skin pigmentation

International audienceTissue homeostasis requires regulation of cell-cell communication, which relies on signaling molecules and cell contacts. In skin epidermis, keratinocytes secrete factors transduced by melanocytes into signaling cues promoting their pigmentation and dendrite outgrowth, while melanocytes transfer melanin pigments to keratinocytes to convey skin photoprotection. How epidermal cells integrate these functions remains poorly characterized. Here, we show that caveolae are asymmetrically distributed in melanocytes and particularly abundant at the melanocyte-keratinocyte interface in epidermis. Caveolae in melanocytes are modulated by ultraviolet radiations and keratinocytes-released factors, like miRNAs. Preventing caveolae formation in melanocytes increases melanin pigment synthesis through upregulation of cAMP signaling and decreases cell protrusions, cell-cell contacts, pigment transfer and epidermis pigmentation. Altogether, we identify that caveolae serve as molecular hubs that couple signaling outputs from keratinocytes to mechanical plasticity of pigment cells. The coordination of intercellular communication and contacts by caveolae is thus crucial to skin pigmentation and tissue homeostasis

GPR30 mediates the effects of 17β-estradiol on hDF shape.

<p><b>a.</b> Efficiency of shRNA vectors. hDF were transfected with shGPR30 (#1 and #2) or control (shC). Expression of the indicated proteins was determined 48 h after transfection. <b>b.</b> ERK phosphorylation under the indicated conditions. Ratios of phosphorylated ERK (p-ERK) to total ERK (t-ERK) are indicated. Lower panel: quantification of the western blots performed on the four donors. Data are presented as mean +/- s.e.m. relative to vehicle-treated control. <b>c.</b> Cells shape monitored under the indicated conditions as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120672#pone.0120672.g001" target="_blank">Fig. 1b</a>. n = 400 cells. ns: not significant; ***<i>p</i><0.001.</p

17β-estradiol effect on cytoskeleton re-organization involves non-genomic mechanisms.

<p><b>a.</b> Cells were cultured in the presence of FCS, or DS supplemented or not with 10^-7 M E2 and cycloheximide (CHX; 20 μg/ml). Actin and nuclei were stained. Scale bar = 100 μm. Lower panel: expression of the ERRα protein upon treatment with CHX for the indicated time was analysed by western blot with actin used as a loading control. <b>b.</b> Cells were cultured in the presence of DS for 2 days, then treated with 10^-8 M E2 or its membrane-impermeable conjugate (E2-BSA). Cell shape was monitored as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120672#pone.0120672.g001" target="_blank">Fig. 1b</a>. n = 400 cells per condition. Values are mean +/- s.e.m; ns = not significant, ***<i>p</i><0.001.</p

Pharmacological modulation of GPR30 alters hDF response to 17β-estradiol.

<p><b>a.</b> Expression of the indicated proteins in hDF or MCF7. <b>b.</b> Expression of the indicated proteins upon E2 stimulation. Ratios of phosphorylated ERK (p-ERK) to total ERK (t-ERK) are indicated. <b>c.</b> ERK phosphorylation under the indicated conditions (G-1: GPR30 agonist). Right panel: quantification of the western blots performed on the four donors. Data are presented as mean +/- s.e.m. relative to vehicle-treated control. <b>d.</b> ERK phosphorylation under the indicated conditions (G-15: GPR30 antagonist; PD98059 [PD]: ERK inhibitor). Lower panel: quantification of the results as above. <b>e.</b> Cells shape monitored under the indicated conditions as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120672#pone.0120672.g001" target="_blank">Fig. 1b</a>. n = 400 cells. ns: not significant; *<i>p</i><0.05; **<i>p</i><0.01; ***<i>p</i><0.001.</p