Fixing age with lipids:
Improvement of the epidermal barrier function in mature skin
Epidermal lipids, among other components, constitute the seal for the outermost skin layers and the glue for the corneocytes. Epidermal lipids, however, are reduced in mature skin and may represent the underlying cause of increased susceptibility, diminished capacity to recover, and chronic dryness of mature skin. Hence, reactivating epidermal lipid synthesis represents a promising anti-ageing strategy for mature skin.
Earlier in-vitro experiments implied that a cosmetic active ingredient, based on a Gynostemma pentaphyllum extract, reactivates lipid synthesis via the Liver X receptor (LXR). Here we show that the reactivation of lipid synthesis may indeed translate into improved barrier integrity and repair.
The skin barrier was disturbed by tape stripping. Subsequent placebo application for 28 days only minimally regenerated the barrier whereas the cosmetic active imparted full regeneration. Barrier strengthening was also supported by reduced corneocyte detachment.
Taken together, our data suggest that cosmetic actives increasing the amount of skin lipids may indeed help to replenish the skin from within. This will eventually improve typical signs of mature skin such as barrier deficiencies, but also chronic dryness and wrinkles.
The barrier integrity of mature skin is disturbed
Mature skin, as a consequence of intrinsic and extrinsic ageing (1), is associated with weaknesses of the skin barrier: The corneocytes of the stratum corneum are morphologically changed and the synthesis of epidermal lipids only functions to a limited extent. The spaces between the cells are no longer properly sealed by the intercellular lipid lamellae (2). This eventually leads to an increased permeability of the skin barrier; the skin becomes more susceptible to external aggressors, and water can evaporate from the skin more quickly. However, functional abnormalities often become evident only when the tissue is either stressed or required to carry out repair processes. To this end, the aged epidermis is perturbed much faster and recovers much more slowly in comparison to young skin (3). For example, resistance to sequential tape stripping was markedly reduced in aged epidermis: 18 versus 31 strippings were required to disturb the epidermis in old versus young skin (3).
In essence, this dysfunction can, at least in part, be attributed to a global deficiency in all ...