Back to balance

Specific and little differences of the skin microbiome can have an important impact on this ecological system and finally on the host. Even if there is no standard composition for skin microbiota, common genera (Staphylococcus, Propionibacterium, and Corynebacterium) with variations on ratios, species and strain level specifics can be identified. 

Unbalanced skin microbiota clearly plays a role in the pathobiology of many types of skin diseases and cosmetic disorders. In fact, when the diversity is lost, some microbial populations take the lead instead of others and participate actively to increase disorders such as inflammatory processes. To control and define the diversity, indexes such as the Shannon index are used to evaluate the diversity from one individual to another or to test the efficacy of a product.

Modern skincare maintains the homeostasis of the skin and its microbiota. The cosmetic industry must take not only the health of the skin and the naturality of the product into account but also the compatibility with this micro-ecosystem to solve problems such as too dry or too oily skin, blemishes, redness, and other skin disorders.

Beauty claims can also target the health and wellbeing status of the skin. These claims can be attributed to the balance of the skin microbiota, induction of commensal diversity as well as the protection against the exposom.

The links between skin microbiota and skin pathologies have been studied in recent years and today we know which bacteria or imbalance of certain strains are responsible for which skin disorder.

Plant Power for the skin

With interdisciplinary research projects it is possible to demonstrate what a positive influence certain bacteria or special plants and fruits can have on the skin. In the following, it will be demonstrated how four well-known skin disorders can be tackled by balancing the microbiome.

Dry skin

This term describes a skin type that produces less sebum than normal skin. Due to a lack of sebum, it does not have enough lipids to retain moisture and protect the skin against external aggression. A reduced radiance in complexion can be the result. But the desire for a radiant, glowing skin is always on demand. 

Using 16S rRNA sequencing, the researchers identified the most prominent bacteria involved in skin dryness and TEWL (transepidermal water loss), Staphylococcus epidermidis and developed an ingredient to balance the microbiome. Obtained by an optimised fermentation process of Lactobacillus pentosus,  patented active ingredient presents many health benefits, such as balancing the immune system, and boosting levels of Staphylococcus epidermidis. It stimulates the expression of antimicrobial peptides like beta-defensins and inhibits the expression of the Toll-like receptor TLR-2 involved in inflammatory response.

Results were obtained in a doubleblind test at 2% versus placebo and twice daily application during seven days on the forehead, with a wash out during two weeks prior to the evaluation. The active ingredient improved short-term and long-term skin moisturisation and fortified the skin barrier function. When skin is damaged, skin barrier recovery was accelerated and restored within six hours. The radiance was restored, and the skin’s texture appeared rested and plumped (figure 1).

The active, derived from lactobacillus pentosus restores a resilient skin barrier and shows a very good capacity to fight dry skin conditions for a new level of skin wellbeing and resilient skin.

Acne

Acne vulgaris is an inflammatory and multifactorial skin disease affecting more than 85% of adolescents and often continuing into adulthood. Its pathogenesis includes hyperseborrhea, hyperkeratosis, proliferation of Cutibacterium acnes (C. acnes) and inflammation. Sebum overproduction is a major concurrent event in the development of acne lesions because sebum serves as a nutrient source for C. acnes, activating toll-like receptors TLR2 and TLR4, leading to the release of proinflammatory cytokines/chemokines3.

The berries of Rhodomyrtus tomentosa are rich in acylphloroglucinols, polyphenols, and organic acids, which suggest a successful path towards developing a novel anti-acne agent. An active based on that addresses the main cause of oily skin by reducing sebum levels through down-regulation of a common type of bacteria in the skin microbiome and by inhibiting the key enzyme 5-α-reductase.

In a double-blind study on volunteers with oily skin and at least five inflammatory lesions, the active, derived from Rhodomyrtus tomentosa, was tested with 2% vs placebo for 28 days with a twice daily application. (Evaluation by 16S RNA sequencing, qPCR, SingleLocus Sequence Typing). It could be shown that regarding the C.acnes phylotypes modulation, cutibacterium acnes ia1 were reduced whilst the overall strains diversity was increased. On the other hand, acne lesion-related strains were reduced, especially corynebacterium granulosum, being more virulent than cutibacterium acnes.

The active controlled oiliness on prominent areas with a visible and mattifying effect on acne prone skin as sebum is reduced by 47%. It also limited oxidised squalene-induced inflammation, preserving sebum quality, and thus preventing dyseborrhea3(figure 2).

The active, derived from Rhodomyrtus tomentosa reduces the proliferation of cutibacterium acnes and therefore reduces hyperseborrhea and improvs oily skin appearance. 

Scalp and its microbiome 

The characteristics of the scalp, such as a high concentration in hair follicles (100,000 on average) as well as an important number of sweat and sebaceous glands, whose secretions contribute to form a protective and lubricating hydrolipidic film on hair and scalp, along with an acidic pH ranging from 4,5 to 5,5, create a specific surface micro-environment, colonised by a unique microbiota. Recent studies suggested links between scalp microbiota and some scalp disorders and functions, such as alopecia or dandruff5.

Hair loss

Androgenetic alopecia (AGA) is a common form of hair loss in males. It is a multifactorial condition invol-ving genetic predisposition as well as hormonal changes. 

The link between alopecia and imbalance of the scalp microbiota has been studied resulting in the development of an active ingredient titrated in sesquiterpenes and polyphenols extracted from the roots of Lindera strychnifolia.

It can reduce the c. acnes/ s. epidermidis ratio, which is, in the case of alopecia strongly increased, causing micro-inflammation and at the same time can rebalance the ratio of Malassezia globosa and Malassezia restricta.

In vitro studies have shown that the active has a significant impact on the inhibitors of the Wnt pathway, the key of hair growth. These results are reflected in a very positive user satisfaction: 77% of users observed a slowing down of hair loss while 81% noted an acceleration of hair growth.

It can rebalance scalp bacteriobiota and mycobiota for a healthy scalpmicrobiota crosstalk and can modulate key biological pathways involved in the hair cycle5 (figure 3).

The active, derived from the roots of Lindera strychnifolia can promote a harmonious interaction between scalp skin and its microbiome resulting in 7% more hairs.

Dandruff

Greasy or adherent dandruff is caused by excess sebum production. Dry dandruff however occurs when dry, white, and loose flakes or scales form on the scalp and fall from head and hair. In addition, symptoms such as itching, redness, and a greasy or dry scalp are also common.

Ziziphus joazeiro barks have traditionally been used for plant-based cleanser/shampoo in South America. It could be shown that the balance between Cutibacterium and Staphylococcus is an important factor to the severity of dandruff. Dandruff scalp is characterised by a decrease in the ratio of c.acnes / s.epidermis. Sebum quantity was found to be in relation with this ratio.

To study the bacterial and fungal scalp microflora of healthy and dandruff prone scalps, a doubleblind study with 1% versus placebo was conducted with male volunteers with a problematic scalp. At the same time, scoring of the total dandruff and the intensity of the scalp irritation were evaluated on the treated group, using 16S rRNA sequencing for bacteria and ITS1 (Internal Transcribed Spacer 1) ribosomal DNA for fungi. Within only two weeks, the ratio between c.acnes to s. epidermidis could be improved by 1/3 towards a healthier scalp. Clinically, at 1% it was proven to be a safe and natural alternative to Zinc Pyrithione (ZPT 1%), offering a similar long-lasting anti-dandruff and sebum control efficacy. So even if contained in a rinse-off shampoo formulation, the active was able to reduce the release of histamine, to prevent scalp inflammation, redness, and unpleasant itching (figure 4).

The active, derived from the bark of Ziziphus joazeiro, can offer a solution against dandruff, modulating both scalp microbiota and biological pathways for a healthy and purified scalp and 37% (D6) less dandruff even in rinse-off formulations.

Gentle cleansing

With the growing demand of products with microbiome-related claims in the cosmetic industry, formulators have been challenged with the target of creating products that keep the natural skin flora intact and healthy while at the same time guaranteeing foam volume and stability as well as efficient cleansing properties.

From six different vegetable oils (almond, apricot, argan, inca inchi, olive, sunflower) have been developed water soluble oils6. Beyond the anti-ageing property of lysine and the properties of natural fatty acids, these oils form a micellar solution with both functional and biological benefits for formulas for skin, hair, and scalp. 

The antimicrobial properties were studied on two major strains of skin microbiota: Staphylococcus aureus (S. aureus), which is a bacterium responsible for several infections and Staphylococcus epidermidis (S. epidermidis), which is known to be beneficial for skin. By using an initial bacterial concentration of 105 CFU.mL-1 the effect of the oils (tested at 5%) on S.epidermidis and S.aureus growth, on the microbiome was studied in vitro at T0 and after 24 hours of incubation at 37°C (figure 5).

The results show that the pre-study beneficial bacteria (S.epidermidis) have not been disturbed by the application, whereas S.aureus could be reduced. It is interesting to note that whilst all of these oils maintain s.epidermidis, the ability to reduce s.aureus varies greatly between the six different oils. The best efficacy was observed by Inca Inchi, a very Omega-3 rich oil.

References

1 Skin microbiota: maintain the dialogue. Mathieu Bey, Biovitis-Greentech Group. H&PC Today – Household and Personal Care Today – vol. 13(4) July/August 2018

2 Biotilys

3 What is new acne? Carine Boutot, Marion Napoli, Edwige Ranouille, Sandie Gervason, Jean-Yves Berthon – Greentech, France Edith Filaire – Greentech & Université Clermont Auvergne, France 4/2019

4 Acnilys

5 Dandrilys

6 Aquasiloils

7 Characteristics of healthy and androgenetic alopecia scalp microbiome: Effect of Lindera strychnifolia roots extract as a natural solution for its modulation E. Filaire*,†, A. Dreux*, C. Boutot*, E. Ranouille* and J. Y. Berthon*,

8 Interview with Professor Edith Filaire, Scientific Director Greentech Group Beauty and sustainability