Combined forces work to restore skin firmness

At a facial level, skin expresses these changes with the appearance of wrinkles and flaccidity. This fact is aggravated by the action of gravity, which exerts a constant downward force, altering the shape of the facial oval. To counter these adverse effects, it is essential to recover and maintain the good condition of the skin structural elements: dermal-epidermal junction, epidermal cohesion and dermal extracellular matrix.

Union provides strength and firmness

The skin is structured in several tightly bound layers: epidermis, dermis and hypodermis. The epidermis maintains cell cohesion through structures such as desmosomes, which keep adjacent cells firmly together. Desmoplakin is a protein that helps stabilise these unions, strengthening the cohesion between epithelial cells and the integrity of the epidermis. The two outermost layers of the skin, epidermis and dermis, are connected by a complex anchoring structure called the dermal-epidermal junction (DEJ). The epidermis basal keratinocytes are attached to the DEJ basement membrane through hemidesmosomes. The basement membrane consists of the lamina densa and the lamina lucida. The latter is the area where the adhesion molecules (integrins, laminin 5, fibronectin) are found, which allow for the binding of epidermal cells. Collagen IV is the most important component of the DEJ lamina densa and acts as a basic support for the other components, such as laminins. It is a very important structural element and its presence is key to maintaining the mechanical stability of the union. Laminins represent the most important component of the basement membrane, after collagen IV. Specifically, the gamma 2, alpha 3 and beta 3 chains form the socalled laminin 5, which is a fundamental part of the anchoring filaments of epithelial cells to the basement membrane. On the side of the dermis, the DEJ has anchoring fibres of collagen VII and elastic microfibrils, arranged perpendicularly to the surface.1 All these components help keep the epidermis and dermis together and contribute to a smooth communication between them. The dermo-epidermal boundary is not straight, but the two layers interpenetrate forming dermal papillae and interpapillary ridges. As a consequence, the contact surface between both layers is bigger, increasing the flow of nutrients and the communication between them. Due to the strength of the dermalepidermal junction and the cohesion among keratinocytes, facial skin has a compact, firm and elastic appearance, which enables it to mitigate the effects of gravity and other destructive factors. The stronger the union between the epithelia, the higher their resistance will be against sagging.