Health & Medicine︱ Grimshaw, Xu and Murphy The partnership between scalp skin and its microbiome – a balancing act

Healthy microbiome Cosmetic interventions e.g. anti-dandruff shampoo Dandruff microbiome M. restricta M. restricta S. epidermidis Host factors, nutrient disruption, environment S. epidermidis Scalp microbiome S. capitis S. capitis gets to the root Beneficial compounds for skin Skin irritation and inflammation of dandruff Beneficial Beneficial host STOP host defence nutrients factors Dandruff is an extremely andruff can be irritating, have all been linked to disturbances common cosmetic condition, uncomfortable and unsightly. It in the microbiome. It would probably but one that remains often Dis also extremely common. The be safe to add dandruff to that list. difficult to treat. Research condition, which typically causes a dry, Although no single definitive cause scientists Sally Grimshaw, itchy and flaky scalp, affects up to half for dandruff has been identified, Elaine Xu and Dr Barry the world’s population. Surprisingly, for researchers generally agree that certain Josan/Shutterstock.comVictor Murphy, of Unilever R&D, have such a prevalent condition, for some changes or conditions are significant. carried out a detailed genetic people dandruff remains very tricky These include over-colonisation of the investigation of the scalp to treat. scalp by yeasts belonging to the genus microbiome: the community Malassezia (yeasts are a type of fungus). of bacteria, fungi and other One explanation for the difficulties in Individuals may also be predisposed to A healthy scalp is the foundation microorganisms that live on treating dandruff is that the causes are dandruff due to changes in the activity of a balanced microbiome the scalp skin. Their findings often elusive. While some traits – such of the sebaceous (oil) glands in the suggest that both bacteria and as age, gender and underlying health skin, and genetic factors that can result SEEKING THE CAUSES invaluable tool in many areas of then used to identify which species of fungi play an important role in conditions – are linked to a greater in a less robust skin barrier. Even the OF DANDRUFF research. The team at Unilever used bacteria and fungi resided on the scalps the development of dandruff. likelihood of dandruff, the precise weather might play a role: many people Recently, research interest has turned NGS to assess the genetic composition of the study participants. A technique This knowledge is being used reasons why some people develop find that their dandruff is worse in the towards a possible role of bacteria in of the scalp microbiome, allowing called quantitative polymerase chain to develop better treatments the condition and others do not are winter months. dandruff. This has been encouraged by them to define precisely which types of reaction (qPCR) was also used, to for the condition. unclear. Much of the previous research one particular study which found that bacteria and fungi were present. determine how many micro-organisms has focused on a possible fungal Fungi like Malassezia are normal the link between bacteria and dandruff of each species were present. cause for dandruff, with the result that residents of the skin’s surface. Micro- might actually be stronger than the More than 100 people took part in the cases are often treated with antifungal organisms like this are commensal, relationship between fungi and dandruff. team’s study of the scalp microbiome. BACTERIA AND FUNGI: ARE THEY shampoos. However, there is another which means they benefit from or First, the overall scalp health of the BOTH RESPONSIBLE? potential group of culprits: bacteria. depend on their host, while causing Sally Grimshaw, Elaine Xu and Dr participants was assessed and they were The team discovered that, as they Until recently, there has been relatively no harm. However, sometimes the Barry Murphy, of Unilever R&D, are divided into two groups, “Healthy” and had predicted, the microbiome of a little consideration of the possible role balance of the microbiome is disturbed, investigating the scalp microbiome at “Dandruff”. Scalp skin washes were scalp with dandruff differs from that of bacteria in dandruff. causing normally harmless micro- the genetic level, of a healthy scalp. organisms to become problematic. with a particular Interestingly, it seems THE SCALP MICROBIOME Multiple studies have found a link interest in bacteria. Neither bacteria nor fungi are solely that neither bacteria Like every other part of the human between the abundance of Malassezia Recently, the nor fungi are solely body, the scalp has its own unique and scalp health. When people with team used a responsible for dandruff; in fact, both responsible for microbiome. A microbiome is the dandruff used an antifungal shampoo, method called are involved. dandruff; in fact, both sum of all the micro-organisms, the number of Malassezia on the next generation are involved. including bacteria, viruses and fungi, scalp was reduced, and a decrease in sequencing (NGS) to analyse the DNA taken from two sites on the scalp of that inhabit a particular place. Time skin flaking was seen – suggesting a of the complete scalp microbiome. each person, one from the healthiest On both healthy and dandruff scalps, by after time, research has shown that relationship between the abundance Simply put, NGS is a quick, relatively part of the scalp, and one from the least far the most abundant fungal resident the microbiome plays a complex and of Malassezia and dandruff. However, cheap DNA sequencing technique healthy. This allowed the microbiome is the yeast Malassezia restricta. For vital role in human health; a healthy Malassezia is sometimes also present that can sequence “barcoding” marker to not only be compared between people without dandruff, M. restricta microbiome means a healthy body. in high numbers on healthy scalps. This genes present in bacteria and fungi, individuals, but also on the same is found in similar quantities on both suggests that both a large Malassezia the sequencing of which facilitates person. DNA was extracted from the the most and least healthy parts of the Common conditions such as acne, population and a predisposition to their identification. Thanks to these samples, processed and sequenced. scalp. However, on dandruff scalps, the dermatitis and irritable bowel disease dandruff are involved. advantages, NGS has become an The microbial DNA sequences were picture is different, with a much greater

www.researchoutreach.org www.researchoutreach.org species of Staphylococcus, S. epidermidis declines in number, while another species, S. capitis, greatly increases. The Behind the Research team suspect that the increases in both M. restricta and S. capitis seen in this study could be explained by both species having the ability to exploit changes in Sally G Dr Barry Elaine scalp biology. What these changes are – damage to the skin surface, or changes in Grimshaw Murphy Xu skin oil production, for example – could T: +44(0)151 641 3661 T: +44(0)151 641 1201 T: +86 021 22125889 A healthy scalp (left) versus a dandruff scalp (right) may be determined by the scalp microbiome (centre). be revealed by further research. E: [email protected] E: [email protected] E: [email protected]

The microbiome is a complex and The number of bacteria differed sometimes delicate community of micro- Research Objectives organisms. Successfully identifying the both between healthy and dandruff bacteria and fungi in the microbiomes The team at Unilever investigate the scalp microbiome to better understand the causes of dandruff. scalps, and between different of both healthy and dandruff scalps, as the team at Unilever have done, is the areas on the same scalp. first step towards discovering why the Detail microbiome can become unbalanced, difference in abundance of M. restricta NGS and other techniques, including leading to scalp problems such as Sally G. Grimshaw Bio More information between the healthiest and least healthy qPCR, allowed the bacteria and fungi dandruff, itch and dryness. With this Barry Murphy Unilever has an established www.clearhaircare.com sites. This finding could indicate that present on the scalp to be examined in knowledge it is possible to develop Unilever R&D Port Sunlight R&D global capability in Human www.livingproof.com Quarry Road East Microbiomics. In partnership with not only are some individuals more intricate detail. products such as the Clear Advanced Bebington leading experts in the field of Next susceptible to dandruff than others, but Protection anti-dandruff shampoo, Funding Wirral Generation Sequencing (NGS) and The study was funded by that, for the same person, some parts The next step will be to determine just Clear Scalp Clinic range and Living CH63 3JW Bioinformatics we have undertaken Unilever R&D of the scalp might be more prone to how these changes in the microbiome Proof Restore Dry Scalp Treatment that numerous clinical studies to obtain a dandruff than others. might be linked to the development of target the root cause of these conditions deeper understanding of the role of Collaborators dandruff. In a further result, the team and restore the equilibrium of the Elaine Xu the microbiome in consumer relevant The University of Liverpool’s Centre for The team’s work identified a further four found that, on a dandruff scalp, one scalp microbiome. Unilever R&D Shanghai conditions across our Beauty and Genomic Research (CGR), known species of Malassezia in the scalp 66, Linxin Rd. Personal Care division, examining the Liverpool, UK; Beijing Genomics samples. They also uncovered another, Shanghai 200335 microbiome associated with cosmetic Institute, Shenzhen, Guangdong, undefined species ofMalassezia . China skin conditions, axillary malodour and China; Eagle Genomics, Importantly, although this new yeast oral health. Cambridge UK species was found in both groups of participants, it was far more abundant on the scalps of people with dandruff. Alone, this result is not enough to say References Personal Response that the mysterious Malassezia causes dandruff – but it does warrant more Grimshaw, SG, et al. 2019. The diversity and abundance How might S. capitis interact with other aspects of attention through future research. of fungi and bacteria on the healthy and dandruff the microbiome to cause dandruff? affected human scalp. PLOS ONE http://doi.org/10.1371/ Interactions between different species of bacteria So what about the bacteria? journal.pone.0225796 and fungi are complex and require further investigation Staphylococcus and Cutibacterium to be fully understood. Micro-organisms consume proved to be the most abundant substances present on the scalp in order to flourish, types of bacteria on both healthy and provide the scalp with essential nutrients and also dandruff scalps. As with Malassezia, the produce substances that can inhibit the growth of other number of staphylococci differed both microbes. However, the over or underproduction of between healthy and dandruff scalps, these metabolites can have a detrimental impact on the and between different areas on the same skin of susceptible individuals. This “balancing act” is key to the maintenance of a healthy scalp. The increase scalp. Significantly, this suggests that in the levels of S. capitis and M. restricta is an important something local is happening to disrupt indication of microbiome imbalance necessitating an the microbiome, rather than a condition intervention with anti-dandruff technology. that affects the individual as a whole.

A NEW APPROACH Grimshaw, Xu and Murphy’s work is the first time that these combined approaches have been used to study The Unilever team’s work allows the development of targeted anti- dandruff products such as those pictured here. the scalp microbiome. The use of

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