The skin is at the interface with the environment and is constantly exposed to a range of physical, chemical, and microbial aggressions such as mechanical frictions, pollution, bacteria, or viruses. Its main function is to provide effective protection against these stresses. This is done by the coordinated action of three barriers that create the first line of skin defense: the mechanical, immune, and microbial barriers.

In normal conditions, the skin is impermeable to external agents. This role of mechanical barrier is guaranteed by the particular structure of the stratum corneum. Lipid cement binds cells together and intercellular junctions strengthen cohesion of the upper layers of the epidermis.

The immune barrier is ensured by keratinocytes and immune cells. Keratinocytes are equipped with danger receptors (Nod-like, Toll-like receptors, etc.) that rapidly detect foreign agents. This intelligent and selective recognition system enables cell defense mechanisms to be installed.
Thus, keratinocytes act directly by secreting antimicrobial peptides (β-defensins, cathelicidins, ribonucleases, etc.). They operate as natural antibiotics that can kill or inactivate aggressors. Indirectly, the local inflammatory response triggered by keratinocytes via the production of cytokines and chemokines promotes the recruitment of immune cells. Just like garbage collectors, immune cells remove exogenous elements.

In addition to skin cells, the microbiota also has an important role. It is qualified as a veritable functional unit of the skin. “Good bacteria” stimulate the production of antimicrobial peptides by keratinocytes, amplifying the host’s immune defenses. In addition, they counteract against the implantation of “bad bacteria”, thereby reinforcing the immune barrier.

The correct operation and equilibrium of these three barriers guarantee skin in good health.

The skin’s defenses are weakened with age or under the influence of stress. The pandemic has added strict hygiene routines to this, leaving the natural barriers in a more fragile state and threatening the equilibrium of the microbiota (hand sanitizers, frequent washing).

Thus, when the pillars of immunity are undermined, several skin disorders appear. This results in skin dryness, the appearance of redness and sensations of discomfort. Quality of the skin is deteriorated; the complexion is no longer uniform and it loses its radiance.

The markets of dietary supplements and health products ensuring immune equilibrium are growing rapidly. At the present time, aware of the importance of preserving cutaneous immunity, more than 50% of consumers are interested in skin care products that can strengthen it. We are witnessing the emergence of a new branch of cosmetics: immunocosmetics whose underlying principle is the intimate collaboration between the mechanical, immune, and microbial barriers for skin in good health.

SILAB has been working on the skin’s immunity for more than 15 years and this is the subject of an ongoing research program. On the one hand, it supports the development of cosmetic active ingredients that address the reduction of immunity in different contexts (hyperseborrhea, aging, in response of bacterial aggression). On the other hand, it has driven the conception of dermocosmetic active ingredients that regulate the immunity of compromised skin (atopic dermatitis, acne).
SILAB’s active ingredients target cutaneous immunity for unquestionable cosmetic and health benefits.