Hydration of the skin and the integrity of the cutaneous barrier are intimately connected and much studied in the search for technological innovation with wider-ranging mechanisms of action which allow the maintenance of a more efficacious and longer-lasting hydration of the skin. The skin, thanks to the stratum corneum, is the body’s natural barrier, separating the internal homeostasis from each and every aggression we are exposed to daily. In addition to the proteins and lipids that make up the stratum corneum barrier, water plays a very important role in maintaining the integrity of this barrier. One of the main aspects of the vital role played by water is connected to its ability to mediate the activity of several hydrolytic enzymes in the skin, including those responsible for the formation of the natural moisturizing factor (NMF). This maintains hydration and consequently the functioning of the stratum corneum, something fundamental for the skin’s overall appearance.
Part of the complex equilibrium necessary for maintenance of the cutaneous barrier’s integrity is performed by the epidermal cornified cell envelope (ECCE), a lipid-protein layer that replaces the corneocytes’ plasma membrane and consists of a complex mixture of proteins bound to a lipid layer annexed to the extracellular surface of the protein layer. The adhesion between keratinocytes and basal layer, along with its interaction with the dermis, is another vital tool in the regulation of skin homeostasis and consequent maintenance of the skin’s hydro balance. Here, fibronectin, a multifunctional and versatile cellular adhesion glycoprotein, plays a crucial role in the process of tissue organization and re-epithelialization.
Another important factor which plays a critical part in the hydration of the skin and the maintenance of the integrity of the cell envelope is the presence of aquaglyceroporins (also known as aquaporins) in the skin. Thirteen aquaporins (AQP) have been described so far in humans, and of these, the most studied and spoken about in the skin to date is AQP-3, found in the epidermis. Epidermal AQP3 acts in the suppression of excessive water loss in the skin caused by hydric irrigation of the blood by the dermal cells via local capillaries.
As the skin contains polysaccharides, we can use the active ingredient Piptadenia Colubrina Peel Extract in the gene expression of the proteins in the AQP-3 molecular fibronectin adhesion envelope (filaggrin and involucrin), giving:
– Greater cohesion between the corneocytes and consequent maintenance of water and humenctants in the skin;
– Increased water canals in the epidermis, represented by aquaporin-3, making possible a better distribution and maintenance of water, glycerol and NMFs in the skin;
– Programmed cellular hydration;
– Greater epidermal cohesion;
– Repair and/or maintenance of the cutaneous barrier, through reduced transepidermal water loss (TEWL);
– Immediate hydrating effect, proved by the increased glycerol index in the first few hours after application;
– Improved overall skin appearance.
Evaluation of the gene expression of the proteins in the cornified cell envelope
In the stratum corneum, filaggrin behaves as a cationic protein that helps in the aggregation and subsequent disulfide bonds between keratin filaments. It is totally degraded in its amino acid constituents, such as PCA and uroncanic acid, making up approximately 50% of the NMFs retained inside the mature corneocytes of the cornified cell envelope. Equally so, the protein envelope is also formed of protein precursors such as involucrin, which promote a tight bond between corneocytes during the renewal of the stratum corneum. Both the genes that codify these envelope proteins are expressed significantly by the active ingredient, proving an excellent capacity to promote cohesion of the stratum corneum with subsequent maintenance of skin hydration.
Evaluation of the Gene Expression of Aquaporin-3
Aquaglyceroporins (aquaporins) are water and glycerol canals existing in several organic tissues. In the skin, AQP-3 is the most described and amply distributed. The active ingredient promotes an induction of approximately 3.5 times the expression of AQP-3, something that favors the homogeneous distribution of water in the skin’s most superficial layers and the increased hydration of the stratum corneum.