A jasmonic acid derivative improves skin healing and induces changes in proteoglycan expression and glycosaminoglycan structure.

BACKGROUND: Jasmonates are plant hormones that exhibit anti-cancer and anti-inflammatory properties and have therefore raised interest for human health applications. The molecular basis of these activities remains poorly understood, although increasing evidence suggests that a variety of mechanisms may be involved. Recently, we have reported that a jasmonate derivative (JAD) displayed anti-aging effects on human skin by inducing extracellular matrix (ECM) remodeling. Based on this observation, we have investigated here the effects of JAD on proteoglycans and glycosaminoglycan (GAG) polysaccharides, which are major cell-surface/ECM components and are involved in a multitude of biological processes. In parallel, we have examined the ability of JAD to promote growth factor activities and improve skin wound healing. METHODS: Proteoglycan expression was analyzed on epidermal primary keratinocytes and reconstituted skin epidermis, using electron/immunofluorescence microscopy, western blotting and flow cytometry. GAG composition was determined by disaccharide analysis. Finally, biological activities of JAD were assessed in cellulo, in FGF-7 induced migration/proliferation assays, as well as in vivo, using a suction blister model performed on 24 healthy volunteers. RESULTS: JAD was found to induce expression of major skin proteoglycans and to induce subtle changes in GAG structure. In parallel, we showed that JAD promoted FGF-7 and improved skin healing by accelerating epithelial repair in vivo. CONCLUSION: This study highlights JAD as a promising compound for investigating GAG structure-function relationships and for applications in skin cosmetic /corrective strategies. GENERAL SIGNIFICANCE: We propose here a novel mechanism, by which jasmonate derivatives may elicit biological activities in mammals.

Cell surface glycans in the human stratum corneum: distribution and depth-related changes.

During the formation of the stratum corneum (SC) barrier, the extracellular spaces of viable epidermis, rich in glycans, are filled with a highly organized lipid matrix and the plasma membranes of keratinocytes are replaced by cornified lipid envelopes. These structures comprise cross-linked proteins, including transmembrane glycoproteins and proteoglycans, covalently bound to a monolayer of cell surface ceramides. Little is known about the presence and distribution of glycans on the SC corneocytes despite their possible involvement in SC hydration, cohesion and desquamation. In this work, we visualized ultrastructurally and quantified the distribution of glycans on the surface of native and delipidated corneocytes. The cells were harvested at different depths of the SC, allowing us to define the relationship between the distribution of various glycans, proteoglycans and glycoproteins, and other changes occurring in SC. At the cell periphery, we found a correlation between the depth-related alterations of corneodesmosome glycoproteins and α-d-mannosyl and N-acetyl-d-glucosamine-labelling patterns. Elimination of the terminal sugars, α-linked fucose and α-(2,3) linked sialic acid, was less abrupt, but also the initial extent of their peripheral distribution was overall lower than that of concanavalin A and wheat germ agglutinin lectin-detected glycans. Diffuse labelling of heparan sulphate glycosaminoglycans disappeared completely from the outermost corneocytes, whereas that of several simple carbohydrates could be detected at all SC levels. Our results suggest that specific glycan distribution may participate in the progressive changes of SC, as it evolves from the SC compactum to the SC disjunctum, towards desquamation.

Proteomic analysis identifies new biomarkers for postmenopausal and dry skin.

A proteomic analysis of stratum corneum (SC) samples of normal healthy skin revealed the presence of more than 70 proteins by 2D electrophoresis. The majority of these proteins to our knowledge have not yet been described in normal SC. We analysed by Western blot the levels of 25 proteins in the SC taken from postmenopausal and dry skin compared with young and normal skin, respectively. In postmenopausal skin, there was a significantly increased amount of heat shock protein 27, plakoglobin and desmoglein 1, whereas transglutaminase 3, apolipoprotein D and acid ceramidase levels were significantly reduced compared with the SC of young skin. We confirmed corneodesmosin as a marker of dry skin. In addition, we showed for the first time that the levels of both phosphatidylethanolamine-binding protein 1 and annexin A2 were significantly increased in the SC of dry skin compared with the SC of normal skin. These results suggest that a proteomic analysis of the SC obtained using a non-invasive varnish stripping method is an attractive alternative to invasive methods to better characterize changes in the physiology of ageing and dry skin.

Effect of C-xyloside on morphogenesis of the dermal epidermal junction in aged female skin. An ultrastuctural pilot study.

A placebo-controlled randomized pilot study was performed on five postmenopausal women aged from 60 to 75 years. The women applied 320 mg (2 mg/cm(2)) of either placebo or 10% C-ß-D-xylopyranoside-2-hydroxy-propane (C-xyloside) cream to each outer forearm twice daily for 3 months. At the end of the treatment, skin biopsies were collected from application areas on both forearms. Transmission electron microscope examinations revealed skin ultrastructural changes at the dermal epidermal junction (DEJ) after 10% C-xyloside application for 3 months. The morphological appearance of the DEJ showed strong improvements, with more homogeneous and regular lamina densa in the C-xyloside-treated compared to the placebo treated skin areas. The number of zones showing basement membrane re-duplication was indeed strikingly reduced on C-xyloside-treated skin. These ultrastructural results were further confirmed by a statistically significant increase in the expression levels of α6-integrin the and laminin-332, as estimated by immunohistochemistry. Altogether, these data suggest that topical C-xyloside application in vivo may be efficient in inducing a better dermal-epidermal cohesion when such a junction is deficient, as is the case in photo-aged or chronologically aged skin. Moreover, a statistically significant increase in CD44 expression was noted in the epidermis of C-xyloside-treated compared to the placebo treated skin areas.

In vitro assessment of eye irritancy using the Reconstructed Human Corneal Epithelial SkinEthic HCE model: application to 435 substances from consumer products industry.

The 7th amendment of the EU Cosmetics Directive led to the ban of eye irritation testing for cosmetic ingredients in animals, effective from March 11th 2009. Over the last 20years, many efforts have been made to find reliable and relevant alternative methods. The SkinEthic HCE model was used to evaluate the in vitro eye irritancy potential of substances from a cosmetic industry portfolio. An optimized protocol based on a specific 1-h treatment and a 16-h post-treatment incubation period was first assessed on a set of 102 substances. The prediction model (PM) based on a 50% viability cut-off, allowed to draw up two classes (Irritants and Non-Irritants), with good associated sensitivity (86.2%) and specificity (83.5%). To check the robustness of the method, the evaluated set was expanded up to 435 substances. Final performances maintained a high level and were characterized by an overall accuracy value > 82% when using EU or GHS classification rules. Results showed that the SkinEthic HCE test method is a promising in vitro tool for the prediction of eye irritancy. Optimization datasets were shared with the COLIPA Eye Irritation Project Team and ECVAM experts, and reviewed as part of an ongoing progression to enter an ECVAM prospective validation study for eye irritation.