A taboo is being defeated: the one that states bacteria is our enemy, these invaders that occupy our body and our skin weakening them and causing much damage. Thus, thanks to gradual popularization, which started in the worlds of health, food supplements and functional foods, the cosmetics industry has logically found itself at the crossroads due to a cross-sector approach.
It is now a matter of an individualized, microbial balance, useful for our protection and our well-being.
Life is about balance, microbiota as well!
Thus the notion of cutaneous ecology takes on its full meaning by applying it to the world of the infinitely small, that of the microorganisms forming the Stratum microbium or cutaneous microbiota.
In the case of a "skin-microbiota" imbalance, much skin damage and even more severe disturbances may appear and the factors of aggression are unfortunately lacking in the hygienics society in which we live. It is now recognized that "too much hygiene kills hygiene" and from that we need to understand that it is not necessary to wash too frequently or to use harsh products because in close proximity to us, there are unwanted microorganisms, ready to take the place of the microbiota and destabilize it.
Microbiota, a complex system that has not finished revealing its secrets to us...
Cutaneous Microbiota cannot be defined in a specific way and generalized for all individuals. We have our own microbiotic identity card that has developed over time. Microbiota forms a true interactive ecological community, a balanced ecosystem that is essential to maintain or restore, but which is very complex. Indeed, since the launch of the National Institute of Health’s "Human Microbiome Project" (HMP) in 2007, the researchers were able to observe great topographic variations of human microbiota [1] as well as great differences according to each individual [2].
When you become aware that each cm2 of skin contains 1 million microorganisms with hundreds of specific species, you can measure the importance of this ecosystem better.
Bacteria can be commensal when living in contact with a host’s cutaneous-mucus membrane surface without causing damage. An equilibrium is then established between the individual and the various commensal flora of the skin and mucous membranes, depending on age, diet and living conditions, but this equilibrium is constantly threatened by the physical or chemical attacks they are subjected to (pollution, temperature, UV rays, intensive use of surfactants, antibiotics, stress, etc ). Commensal or resident bacteria are considered beneficial in the common discourse delivered to consumers. Facing them are transient, undesirable and/or pathogenic bacteria. These notions are much more sensitive insofar as the same bacteria may or may not be associated with undesirable effects. This will depend on the individual as well, in addition to the stability of his or her microbiota.
Opportunistic bacteria, another way of characterizing them, can become harmful or induce disorders when the host’s defenses are weakened. They await the opportunity to come and settle on the cutaneous area. The skin can also contain pathogenic bacteria, for example Staphylococcus aureus, which is part of their commensal flora without developing damage; it is worth noting that according to the Institut Pasteur, 30 to 50% of the population is healthy and that the breakdown of the skin barrier (in the case of an injury for example) can induce a pathogenic effect. Other examples: What is the status of Propionibacterium acnes and that of Corynebacterium xerosis, bacteria that are involved respectively in problems of oily skin or the development of bad odors? These microorganisms are not considered to be pathogenic per se, but their harmful action or the unpleasant problems they cause are related to the composition of the microbiota that surrounds them, but it also depends on skin function and its intrinsic imbalances. Last but not least, Staphylococcus epidermidis, which you often hear about in cosmetics: depending on the case, it can induce significant skin infections and is found in acne prone skin [3], while a study in 2015 by a Japanese team demonstrated its benefits on maintaining hydration [4].
We are only at the beginning of the investigations and many questions remain to be clarified before penetrating all the mysteries of microbiota and better understanding how it acts on the cutaneous ecosystem.
The skin’s defense mechanisms
In addition to the microbiota that blocks the development of opportunistic bacteria, the skin has other defense mechanisms, in particular its physical, chemical and biological barriers (Fig 1).
When this barrier is impaired or broken, leading to the entry of opportunistic microbial agents, the skin uses various biological defense mechanisms. Its innate immune system induces responses such as phagocytosis by neutrophils and macrophages or the induction, in particular by the keratinocytes, of the synthesis of antimicrobial peptides ( [5], [6]) or AMP (the β-defensins, in particular hBD2 & hBD3, cathelicidins LL37) in addition to constitutive AMP peptides (Rnase 7, psoriasin, lactoferrin, dermcidin).
Important points: pathogenic bacteria do not seem to be able to develop resistance to these AMPs. These peptides act, for example, by breaking the membrane of the targeted microorganisms or by penetrating the microbial cell to interfere with its intracellular functions.
The Solabia Group and its microbiotic approach
Convinced of the interactions between the body and microorganisms, Solabia became interested in skin flora and maintaining its balance on the surface of the skin almost 20 years ago. Specialized in enzymatic biocatalysis, Solabia thus developed an original method consisting first of all in producing a specific enzyme by fermentation (Glucosyl-transferase) and then in activating the latter on substrates of plant origin in order to obtain prebiotics.
– Maintaining the integrity of the microbiota or promoting its development. Prebiotics are oligosaccharides having bioselectivity with respect to the microbiota. In the present case, these are gluco-oligosaccharides (Fig. 2, Bioecolia®) acting as selective substrates to promote the development of the microbiota to the detriment of that of opportunistic or undesirable microorganisms associated with skin disorders (Propionibacterium acnes, Staphylooccus aureus, Corynebacterium xerosis, Malassezia furfur, Gardnarella vaginalis, Candida albicans, etc.). The selectivity of Bioecolia® is linked to the presence of specific bonds of types α-(1-6) and α-(1-2) between the constituent glucose units, metabolizable more quickly and efficiently by the commensal resident flora, which by competitive inhibition, is reinforced or develops better on the cutaneous surface than the opportunistic flora. A signature active ingredient of the Solabia Group, Bioecolia® is the guarantor of a sustainable ecology and is formulated in many skin care, hair care and personal and intimate hygiene products.
– Stimulating the synthesis of antimicrobial defense mechanisms. With consumer interest in probiotics, better known than prebiotics, Solabia has continued its research and developed a symbiotic active ingredient, combining two prebiotics and two probiotic bacteria (Lactobacillus acidophilus, Lactobacillus casei) but in an inactivated form to obtain Ecoskin®. In addition to the ability of the complex to interact on microbiota bioselectivity, the gluco-oligosaccharides and fructo-oligosaccharides (obtained after pressing the yacón tubers, Polymnia sonchifolia), have demonstrated stimulatory properties of the synthesis of antimicrobial peptides (Fig. 3) of type β-defensin 2 and β-defensin 3 (+71% vs. placebo). The presence of lactobacilli also enhances the immune protection of the skin. Evaluated against placebo, on a panel of volunteers with very dry skin, Ecoskin® enhances the skin’s radiance by reducing the average depth of the micro-furrows, restructuring the skin via its microdepression network, while nourishing it and reducing feelings of discomfort. Thus brighter, the skin can display an ecologically controlled "happy-look".
– Acting against microbial adhesion. The colonization of the cutaneous area but also of the mucous membranes uses adhesion factors associated with specialized structures present on the surface of the bacteria with the ability to bind to specific receptors of the skin cells. Fighting against the microbial adhesion of opportunistic bacteria is an additional means of defense to limit the proliferation of undesirable or even pathogenic bacteria, and to maintain the cutaneous microbiota. The adhesion factors are different according to the bacteria. Among them, the bacterial lectins, glycoproteins found on the surface of bacteria and capable of binding to receptors of epidermal cell membranes. Moreover, the adhesion process can also come from the lectins of the epidermal cells having a specific affinity for sugars, the latter then being on the surface of the bacteria and at the origin of the formation of biofilms [7]. It was from this observation that Solabia Research, specialized in Glycobiology, developed a polysaccharide, Teflose®, with a high concentration of rhamnose (Fig. 4), a sugar having specific affinity for epidermal cell receptors. This molecule then plays the role of a coating on the surface of the skin to limit the adhesion of opportunistic bacteria, like an anti-microbial shield, and reduce the resulting reaction of discomfort. Tested on reconstructed epidermis after topical application, Teflose® confirmed its affinity for the skin by decreasing the adhesion of Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis. Other studies, undergoing more in-depth study, have also emphasized its ability to reduce the biofilm formed by certain bacteria. But the rhamnose composition of Teflose® is not limited to anti-microbial adhesion; in fact, with 60% of this rare sugar, the polysaccharide also exhibits anti-inflammatory properties by regulating the release of specific mediators, in particular bacterial attacks (e.g.: Interleukin-8). Ubiquitous by its applications (soothing care, deodorants, care of sensitive skin / atopic dermatitis, care of oily skin, personal hygiene, etc.), Teflose® can also be combined with prebiotics, the latter promoting maintenance of the microbiota while this anti-adhesion shield prevents the establishment of opportunist bacteria on the skin, and even more so if the skin’s ecosystem is weakened.
Prospects
Since the start of the HMP project in 2007, many discoveries have been made regarding the role of the human microbiota. While only yesterday microorganisms were perceived negatively because they were considered as the cause of many diseases, today mentalities have changed and the evolution of knowledge has led us to consider the microbiota as one of our sentinels commanded by the skin’s defense system. Many promising avenues remain to be explored, and will undoubtedly change our approach to the skin and the ingredients we use to provide protection and well-being to it.
