Maria Dalko-Csiba

Improvement of the dermal epidermal junction in human reconstructed skin by a new c-xylopyranoside derivative

Skin aging entails drastic changes in the extracellular dermal matrix (ECM) and dermal-epidermal junction (DEJ). These biological alterations are reflected in the clinical signs of aged skin. A new C-xylopyranoside derivative, C-beta-D-xylopyranoside-2-hydroxy-propane (C-Xyloside) has been shown to induce neo-synthesis of matrix proteins such as glycosaminoglycans and heparan sulfate proteoglycans. The aim of this study was to assess the effects of C-Xyloside on markers of the dermal epidermal junction. Basement membrane components, collagen IV, collagen VII and laminin 5 as well as sub-epidermal dermal markers, pro-collagen I and fibrillin 1 were analysed using immunohistochemistry in a reconstructed skin model, including a dermal equivalent populated with living fibroblasts. Levels of mRNA of collagen VII alpha1 and collagen IV alpha1 were evaluated in dermal fibroblasts using RT-PCR. The results showed that C-Xyloside significantly induced a higher deposition of basement membrane and DEJ proteins in the reconstructed skin model and increased collagen VII gene expression. These findings indicate that, in addition to stimulating glycosaminoglycan and heparan sulfate proteoglycan expression, C-Xyloside improves the morphogenesis of the whole DEJ, and strongly suggests beneficial effects in aged skin from restoring DEJ integrity.

The anti-ageing potential of a new jasmonic acid derivative (LR2412): in vitro evaluation using reconstructed epidermis episkin™

Abstract:  Jasmonic acid is involved in plant wound repair and tissue regeneration, but no study has been reported in human skin. The effect of a jasmonic acid derivative, tetra‐hydro‐jasmonic acid (LR2412, 1 and 10 μm) was investigated on an in vitro reconstructed skin model, Episkin™. Using real time RTQPCR studies, results showed an increase in hyaluronan synthase 2 (HAS2) and hyaluronase synthase 3 (HAS3) expression. Furthermore, an increase in hyaluronic acid (HA) deposits in basal and suprabasal layers of the epidermis was observed. The percentage of positive Ki67 keratinocytes in the basal layer as well as the epidermis thickness were seen to increase. Immunohistochemistry studies showed that the synthesis of late differentiation proteins filaggrin and transglutaminase 1 was not modified. The human epidermis is known to thin with age while HA content has been reported to decrease. These results illustrate the potential of LR2412 in counteracting signs of skin ageing.

Interactions and encapsulation of vitamins C, B3, and B6 with dendrimers in water.

Titrations of commercial diaminobutane (DAB) and polyamidoamine (PAMAM) dendrimers by vitamins C (ascorbic acid, AA), B(3) (nicotinic acid), and B(6) (pyridoxine) were monitored by (1)H NMR spectroscopy using the chemical shifts of both dendrimer and vitamin protons and analyzed by comparison with the titration of propylamine. Quaternarizations of the terminal primary amino groups and intradendritic tertiary amino groups, which are nearly quantitative with vitamin C, were characterized by more or less sharp variations (Deltadelta) of the (1)H chemical shift (delta) at the equivalence points. The peripheral primary amino groups of the DAB dendrimers were quaternarized first, but not selectively, whereas a sharp chemical-shift variation was recorded for the inner methylene protons near the tertiary amines, thereby indicating encapsulation, when all the dendritic amines were quaternarized. With DAB-G5-64-NH(2), some excess acid is required to protonate the inner amino groups, presumably because of basicity decrease due to excess charge repulsion. On the other hand, this selectivity was not observed with PAMAM dendrimers. The special case of the titration of the dendrimers by vitamin B(6) indicates only dominant supramolecular hydrogen-bonding interactions and no quaternarization, with core amino groups being privileged, which indicates the strong tendency to encapsulate vitamins. With vitamin B(3), a carboxylic acid, titration of DAB-G3-16-NH(2) shows that only six peripheral amino groups are protonated on average, even with excess vitamin B(3), because protonation is all the more difficult due to increased charge repulsion, as positive charges accumulate around the dendrimer. Inner amino groups interact with this vitamin, however, thus indicating encapsulation presumably with supramolecular hydrogen bonding without much charge transfer.

Expression of NAD+ dependent 15-hydroxyprostaglandin dehydrogenase and protection of prostaglandins in human hair follicle

Abstract:  NAD+ dependent 15‐hydroxyprostaglandin dehydrogenate (15‐PGDH) catalyses oxidation of 15(S)‐hydroxyl group of prostaglandins and as a result inactivates their physiological potential. Positive effects of prostaglandins or prostaglandin analogues were reported on terminal hair, vellus hair or eyelash growth and a complex prostaglandin network was recently described in human hair follicle. In the present study, we showed that 15‐PGDH was expressed in human hair follicle mainly in melanocytes and keratinocytes, which brought us to consider this enzyme as a possible target to sustain local prostaglandin production. Using a recombinant enzymatic strategy, specific 15‐PGDH inhibitors were screened. We identified a thiazolidine dione derivative exhibiting efficacy on follicular outer root sheath keratinocytes, since it concomitantly decreased the production of deactivated 13,14 dihydro 15‐ketoprostaglandin F2α and sustained prostaglandin F2αin vitro production. In the context of recent interest in prostaglandins and prostaglandin analogues as hair regrowth agents, we postulated that the use of selected 15‐PGDH inhibitors could reinforce or prolong the effect of these physiological mediators on hair and skin.

Sweating the small stuff: Glycoproteins in human sweat and their unexplored potential for microbial adhesion.

There is increasing evidence that secretory fluids such as tears, saliva and milk play an important role in protecting the human body from infection via a washing mechanism involving glycan-mediated adhesion of potential pathogens to secretory glycoproteins. Interaction of sweat with bacteria is well established as the cause of sweat-associated malodor. However, the role of sweat glycoproteins in microbial attachment has received little, if any, research interest in the past. In this review, we demonstrate how recent published studies involving high-throughput proteomic analysis have inadvertently, and fortuitously, exposed an abundance of glycoproteins in sweat, many of which have also been identified in other secretory fluids. We bring together research demonstrating microbial adhesion to these secretory glycoproteins in tears, saliva and milk and suggest a similar role of the sweat glycoproteins in mediating microbial attachment to sweat and/or skin. The contribution of glycan-mediated microbial adhesion to sweat glycoproteins, and the associated impact on sweat derived malodor and pathogenic skin infections are unchartered new research areas that we are beginning to explore.

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.

Fragment pharmacophore-based in silico screening: a powerful approach for efficient lead discovery

Through a process of fragmentation, functionalization, and recombination of market approved molecules for cosmetic usage, we customized an in-house virtual library comprising molecules ideally suited for virtual screening. Computational pharmacophore-based screening of this virtual library followed by a 3 month optimization phase led to the identification of an optimized lead with all its expected properties in hand to be developed as a candidate molecule for skin care in cosmetic applications. The success of this pilot project paves the way for other cosmetic targets of interest.