“Although there is still a lot to discover, the skin microflora is fundamental in skin homeostasis. It participates in maintaining innate immunity and the barrier function. The bacterial ecosystem contributes to the clinical signs of some skin imbalances,” explained Audrey Guéniche, of L’Oréal, at the workshop organized by the French Society of Antioxidants (SFA) on the human microbiota, at the beginning of last November.
The epidermis generates antimicrobial lipids, peptides such as ß-defensins and cathelicidin, and receptors dedicated to the recognition of pathogens which, put together, form the skin’s innate immunity. The balance of the skin microbiota and the expression of the ecological conditions of the environment (temperature, pH, hormone concentrations in lipids or proteins, UV exposure, absence of light, type of mucous membrane, water concentration, etc.) are also essential to skin maintenance  .
Suppliers of cosmetic actives that are interested in this field will study the skin microbiota from different angles. The first way to do it is directly inspired from the benefits of probiotics on the intestinal microflora (figure 1). It consists in the topical administration of these probiotics on the skin microflora.
Greentech has developed Bioltilys®, an active derived from the optimized fermentation of Lactobacillus pentosus, which improves the barrier function to maintain the beauty of the skin and help it recover its performance functions more quickly after aggressions. Lonza proposes ProSynergen™ DF, which is obtained by the fermentation of two bacterial strains (lactobacillus and ulkenia amoeboidea) grown simultaneously in a competitive environment, so that their active principles are overexpressed. It targets skins that are weakened by environmental factors by reinforcing their barrier function.
Finally, Silab has developed Indufence®, which is rich in purified alisma peptides, and offers a probiotic-like effect thanks to a mechanism that is similar to that of an active probiotic, and optimizes the skin’s natural immune functions without causing any inflammation.
The second way to study the skin microbiota is related to antimicrobial peptides. Ashland Care Specialties has thus developed Lipigenine™ biofunctional, a flaxseed extract that increases the in vitro and ex vivo expressions of ß-defensin and cathelicidin LL-37 from 50 % to 150 %, when tested on keratinocytes, 24 hours after a 1 % active topical application.
Exsymol has focused on cells and nerve endings that are involved in the expression of antimicrobial peptides, and which are particularly sensitive to ageing. Glutrapeptide® acts on the production of catestatin and chromogranin A. In addition, this active can inhibit the growth of staphylococcus aureus in culture media of nerve cells.
BASF Beauty Creations proposes Betapur™, an extract from boldo leaves which regulates the skin microflora by activating the synthesis of ß-defensin. When tested in vivo, it showed a reduction in the size of pores, imperfections and specific lesions of acne prone skins.
Lastly, Solabia has been present on this market for several years with Bioecolia®, a prebiotic glycan which protects hair and skin ecology sustainability. The active is obtained by a patented process of enzymatic biocatalysis. It presents a double activity, as it has a microbiological action with the selective stimulation of the beneficial saprophytic flora, to the detriment of opportunist flora, and a biological action, with the release of antimicrobial peptides by keratinocytes. It thus protects the skin’s ecosystem.
As more discoveries will be made, the skin’s microbiota ecosystem should play an increasingly significant role in cosmetics.