We sat down with Cécile Clavaud, Research Engineer, Open Research, for L’Oréal Research & Innovation, to hear about her team’s recent research into microbiota imbalance in the scalp.
Clavaud is presenting at the in-cosmetics Formulation Summit, which takes place in London on 25-26 October 2017.
Her presentation ‘Keeping scalp microbiota in check’ will highlight how to manage scalp microecology, and more info on the summit can be found here.
Can you explain a little about how microbiota imbalance in the scalp can cause skin issues?
Dandruff is one of the most common skin conditions, affecting approximately half of the adult population worldwide.
This flaky scalp disorder is related to skin barrier disruption, epidermal cellular proliferation and differentiation, as well as shifts in sebum composition.
It has been frequently associated with yeasts from Malassezia genus, which are also members of the healthy cutaneous microbiome.
Malassezia sp. especially M. restricta is able to induce cytotoxicity to skin cells in vitro suggesting an active role in the accelerated formation of scales.
In our recent studies on dandruff scalp microbiome, we observed 10 times more M. restricta cells per cm2 on dandruff scalp areas than on dandruff-free areas. In addition to this increased amount of M. restricta, we have shown a microbial shift in bacterial and fungal communities compared to normal scalps.
More particularly, the ratios P. acnes / M. restricta and P. acnes / S. epidermidis, the three major microbes in the scalp microbiota, were significantly decreased in dandruff scalps. These results observed in France, China and Brazil suggest that P. acnes is associated to a “healthy” state and S. epidermidis to dandruff condition.
Our recent studies on dandruff scalp microbiota provide new perspectives for the understanding of this scalp disorder, establishing steps toward a more comprehensive view of dandruff etiology.
Although a causal role has not been clearly demonstrated in the context of dandruff, it is known that scalp microbiota is one of the contributing factor.
We think that understanding the contribution of each community (bacteria, fungi, viruses) at the functional level is now possible thanks to metagenomics tools and will be essential to decipher their contribution in dandruff formation and to propose new antidandruff approaches.
Are there currently any products that can address these issues on the market? How effective are they?
Currently, effective treatments for dandruff/seborrheic dermatitis require (i) a potent antifungal active and (ii) efficient topical delivery while maintaining bioavailability.
The most widely used antidandruff strategy is to limit the proliferation of Malassezia genus using antifungal product.
The most common agents, zinc pyrithione (ZPT), piroctone olamine, selenium sulfide (SeS2) and ketoconazole, are usually used at approximately 1% concentration in a shampoo base for OTC. The active compounds are deposited onto the scalp surface and will later inhibit the growth of Malassezia spp.
ZPT and SeS2 have additional keratolytic effect that contributes to their anti-dandruff efficiency. Some keratolytic agents such as salicylic acid can also be added.
Significant improvement in dandruff condition appears after two to three shampoos, sensory manifestations (itching) being the earliest to decline.
Although current products are efficient, once the treatment is stopped, there is a reoccurrence of scaling along with re-colonization of scalp by the yeast within four to six weeks, depending on the active.
What’s the future for research in this area? What kind of innovation are we likely to see for scalp microbiome-related products?
Our findings from these past years suggest that relying solely on antifungal agents for treating dandruff could be not optimum.
Indeed, reducing the individual susceptibility to develop dandruff by controlling microbial species equilibrium and / or reinforcing skin barrier function could be the pillars of a new holistic treatment to get better long-lasting effects.
Is this a major area of focus for L’Oreal? Are you also looking at the skin other than scalp skin?
Since around 10 years ago and the first publication on the effect of Vitreoscilla filiformis biomass on seborrheic dermatitis, L’Oréal has been involved in both scalp and skin microbiome research.
The advances in sequencing technologies allowed us to investigate deeper the skin and scalp microbiome in various contexts: dandruff, atopic dermatitis, normal skin of different populations and more recently in skin aging, as presented in our recent publication.
After describing the skin microbiomes in these different conditions, our goal will be to better understand the role played by the different microbial actors in skin homeostasis to propose more efficient skin/scalp care products.
 Jourdain R, et al. (2016). Exploration of scalp surface lipids reveals squalene peroxide as a potential actor in dandruff condition. Arch Dermatol Res.;308:153–163
 Donnarumma G, et al. (2014) Analysis of the response of human keratinocytes to Malassezia globosa and restricta strains. Arch Dermatol Res. ;306(8):763-8.
 -Clavaud C, et al. (2013) Dandruff is associated with disequilibrium in the proportion of the major bacterial and fungal populations colonizing the scalp. PLoS One;8(3):e58203.
- Wang L, et al. (2015) Characterization of the major bacterial-fungal populations colonizing dandruff scalps in Shanghai, China, shows microbial disequilibrium. Exp Dermatol.;24(5):398-400.
- Soares RC, et al. (2016) Dysbiotic Bacterial and Fungal Communities Not Restricted to Clinically Affected Skin Sites in Dandruff. Front Cell Infect Microbiol.;6:157.
 Guéniche A, et al. (2008). Vitreoscilla filiformis biomass improves seborrheic dermatitis. J Eur Acad Dermatol Venereol. ;22(8):1014-5