Soothing Effect of Pogostemon cablin Extract (Patchouli), via Cannabinoid Receptor 2 Modulation in Human Skin.

Skin functions as a neuro-immuno-endocrine tissue with well-defined neuronal networks and functions. The endocannabinoid system has been proven to be an important, homeostatic regulator for homeostatic and inflammatory events. The system comprises endogenous or exogenous ligands and receptors (CB1 and CB2). In the present study, we evaluated the soothing properties of a Pogostemon cablin (patchouli) extract. Agonist AM1241 and antagonist AM630 were used for CB2 receptor activation/inhibition. Expression of CB2 receptor and ß-endorphin was monitored by immunohistochemistry. Skin inflammation was induced with ultraviolet B (UVB) or lipopolysaccharide (LPS), and the following markers were used to highlight the anti-inflammatory properties of the extract: transient receptor potential vanilloid 1 (TRPV1), interleukin receptors 1 (IL1R1), and the interleukin 6 signal transducer (IL6ST). Our results demonstrated the implication of the CB2 receptor in the skin inflammation process. The expression of CB2 receptor and ß-endorphin was increased 48 hours after application of the extract. Furthermore, patchouli extract application helped to reduce IL1R1, IL6ST, and TRPV1 expression, in skin exposed to UVB or LPS. In conclusion, the application of the patchouli extract helps maintain skin integrity and reduce skin discomfort via modulation of CB2 receptor stimulation and the subsequent ß-endorphin release.

Plant Small RNAs: A New Technology for Skin Care.

This study was performed on an aqueous extract of baobab seedcake enriched in small ribonucleic acids (RNAs) for cosmetic use. The seedcake is a by-product, obtained from Baobab seeds belonging to the Adansonia digitata species. A particular patented extraction process, named plant small RNA (PSR) technology, has been developed to retain some specific nutrient compounds, including small RNAs. Small RNAs, such as microRNAs (miRNAs), play an essential role in gene regulation. The biological potential of this new patented PSR extract was studied in skin fibroblasts and in ex vivo skin. To demonstrate the effect relative to the presence of small RNAs, the same extract in which small RNAs were removed was also tested. After observing the efficacy of PSR extract on collagen expression in ex vivo skin, different markers of senescence were investigated on fibroblasts aged by replicative senescence. The study of the expression of Drosha, an enzyme responsible for miRNA maturation, the expression of miRNA-19b, a biomarker of cellular aging, and the activity of senescence-associated ß-galactosidase showed more efficient activity of PSR extract, compared with small RNAs-free extract. Taken together, these studies demonstrate the potential of PSR extract for use in cosmetic end use applications.

Skin presenting a higher level of caspase-14 is better protected from UVB irradiation according to in vitro and in vivo studies.

Caspase-14, a cysteine endoproteinase belonging to the conserved family of aspartate-specific proteinases, was shown to play an important role in the terminal differentiation of keratinocytes and barrier function of the skin. In the present study, we developed a biofunctional compound that we described as a modulator of caspase-14 expression. Using normal human keratinocytes (NHK) in culture and human skin biopsies, this compound was shown to increase caspase-14 expression and partially reverse the effect of caspase-14-specific siRNA on NHK. Moreover, the increase in filaggrin expression visualized on skin biopsies and the recovery of the barrier structure after tape-stripping indicated that this compound could exhibit a beneficial effect on the skin barrier function. Considering the possible link between caspase-14 and the barrier function, a UVB irradiation on NHK and skin biopsies previously treated with the caspase-14 inducer, was performed. Results indicated that pretreated skin biopsies exhibited less signs of UV damage such as active caspase-3 and cyclobutane pyrimidine dimers (CPDs). Likewise, pretreated NHK were protected from UV-induced genomic DNA damage, as revealed by the Comet Assay. Finally, a clinical test showed a reduction of transepidermal water loss (TEWL) on the treated skin compared with placebo, under UV stress condition, confirming a protecting effect. Taken together, these results strongly suggest that, by increasing caspase-14 expression, the biofunctional compound could exhibit a protective effect on the skin barrier function, especially in case of barrier damage and UV irradiation.

Functional expression of AQP3 in human skin epidermis and reconstructed epidermis.

The purpose of this study was to examine the presence of aquaporin water channels in human skin and to assess their functional role. On western blots of human epidermis obtained from plastic surgery, a strong signal was obtained with polyclonal anti-aquaporin-3 antibodies. By indirect immunofluorescence on 5 microm cryosections, anti-aquaporin-3 antibodies strongly stained keratinocyte plasma membranes in human epidermis, whereas no staining was observed in the dermis or the stratum corneum or when anti-aquaporin-3 antibodies were preabsorbed with the peptide used for immunization. Similarly, a strong signal with anti-aquaporin-3 antibodies was observed in keratinocyte plasma membranes of reconstructed human epidermis in culture at the air-liquid interface for up to 3 wk. The keratinocyte plasma membrane localization of aquaporin-3 was confirmed at the electron microscope level in prickle cells. In addition an intracellular localization of aquaporin-3 was also detected in epidermis basal cells. Osmotically induced transepidermal water permeability was measured on stripped human skin and on reconstructed epidermis. Water transport across both stripped human skin and 2-3 wk reconstructed epidermis was comparable, inhibited by > 50% by 1 mM HgCl2 and fully inhibited by acid pH. By stopped-flow light scattering, keratinocyte plasma membranes, where aquaporin-3 is localized, exhibited a high, pH-sensitive, water permeability. Although human skin is highly impermeable to water, this is primarily accounted for by the stratum corneum, where a steep water content gradient was demonstrated. In contrast, the water content of viable strata of the epidermis is remarkably constant. Our results suggest that the human epidermis, below the stratum corneum, exhibits a high, aquaporin-3-mediated, water permeability. We propose that the role of aquaporin-3 is to water-clamp viable layers of the epidermis in order to improve the hydration of the epidermis below the stratum corneum.