82 MICROBIOME
have conducted a clinical study to assess this. We have then used this data to investigate the modulatory effect a topically applied bioactive can have on key microorganisms. We have also illustrated all our findings using 3D facial colour mapping, a technology that visualises complex and detailed data in a way end consumers can relate to and understand.
A new methodology for assessing changes in microbiota composition Skin microbiome data are compositional, meaning that changes, or shifts, in one component affect all the others. To accurately determine which microbes are changing and to what extent, it is therefore essential to have information about the total microbial load or absolute number of microorganisms. However, collecting such data is
challenging and prone to bias, so current approaches to skin microbiome analysis tend to be based on comparing relative abundances across samples, even though these approaches are prone to high false discovery rates. To overcome this, our studies followed a new, state of the art methodology known as ‘reference frames’.6-7 This involved a comprehensive microbiome
analysis of different facial sites using 16S rRNA sequencing, the assessment of microbial changes in abundance in response to the product application, the identification and ranking of those bacteria changing most relative to each other (differential ranking) and the comparison of log-ratios of every bacterium with respect to a reference microorganism (the reference frame) to infer changes in abundance. Reference frames provide in-depth insights
into the compositional nature of microbiome data, alleviate false positives, and produce consistent results. They also help in the identification of consistent, differentially abundant microbes which are often undetected. By using reference frames to analyse
16S-rRNA sequencing data, we were able to identify shifts in microbial composition and associate specific microbiota with the presence of specific skin bioactives.7
We
applied our methodology to the first two studies described below.
Study 1: Shifts in skin microbiota after cleansing Our first study focused on the effect of cleansing skin with a body wash containing saccharide isomerate (commercial name Pentavitin®). This is our well-known cosmetic ingredient, with a unique binding mechanism that delivers instant and long-lasting moisturisation to skin. Cleansing involves the mechanical and
chemical removal of dirt, pollutants, and reduction of microbial load on the skin. While cleansing can help maintain good health and protect us from infection and illness, the process also strips skin of lipids and moisture. This can lead to irritation, impair the skin barrier, and disturb the delicate cutaneous microbiome.
PERSONAL CARE November 2021
Figure 2: Visualisation of log-ratio between S.epidermidi &
S.capitis via facial colour mapping Note: Colour maps showing a log-ratio increase in S. epidermidis over S. capitis after four weeks of treatment with the placebo (left) & the
product (right). The colour code (-2 to 2) is shown on the scale on the right-hand column. A, B, C, D & E were the facial sampling areas Our placebo-controlled clinical study
investigated how cleansing impacts the body skin’s microbial composition. In this, 30 Caucasian women applied a liquid body wash on their volar forearms twice daily for one week, to mimic frequent showering. As well as demonstrating the beneficial
effects of saccharide isomerate, the study revealed cleansing-associated microbial changes. Both short- and long-term perturbation were observed because of skin cleansing, but at the same time, the skin microbiome proved to be resilient and able to adapt its composition and re-establish itself. Additionally, the use of saccharide
isomerate in our studied body wash was associated with a reduction in coryneforms, such as B. casei and R. mucilaginosa (bacteria which are increasingly implicated in skin infections) and an increase in the beneficial bacterium, P. marcusii. These shifts were observed 24 hours after showering and after seven days of frequent showering.7
Study 2: Shifts in facial skin microbiota in response to a cosmetic bioactive Some 50% of consumers have concerns about oily skin. Over the past year, such concerns have been exacerbated by mask wearing because this practice traps oil and bacteria on the skin around the chin and creates humid conditions conducive to overproduction of sebum, resulting in clogged pores and spots. In a separate study, focusing on oily
skin, we assessed the composition of the skin microbiota in five facial areas. We then analysed shifts in microbiota composition after application of a leave on formulation containing Epilobium fleischeri plant extract (commercial name Alplafor® Alp-Sebum)
For this randomised, double-blind and
placebo-controlled study, we assessed to which extent the plant extract improved the overall skin phenotype and how it interacted with the facial microbiome. The 23 subjects applied either the formulation containing the plant extract or a placebo formulation to the full face, twice daily for 28 days. Microbiome samples were collected at the baseline and after 28 days by means of swabbing at five sites (forehead, nose, front cheek, lateral cheek and chin). By means of the reference frames method we identified differentially abundant species which led us to focus on three particularly relevant species of bacteria: ■ Staphylococcus epidermidis, a commensal known for its anti-microbial activity against some pathogens and for playing a role in acne prevention and inflammation resolution ■ M. yunnanensis, which plays a detoxification role and promotes skin defence; and ■ S. capitis, another skin commensal suggested to play a role in acne formation For each of these species, we mapped
median values of log ratios to a 3D image of an average face. More microbiome analysis is ongoing, but in this study, we found that the Epilobium fleischeri extract had a prebiotic effect on the skin microbiota, promoting an abundance of beneficial skin bacteria such as S. epidermidis and M. yunnanensis. Moreover, compared to the placebo
these bacteria were significantly modulated on the forehead, cheek, and chin. This is illustrated in the facial map in Figure 2, which provides a visual comparison of log ratios of S. epidermidis and S. capitis after 28 days of treatment with either the placebo or Epilobium fleischeri formulation.
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