SKIN CARE 59 Restoration of abundance of resident commensal Micrococcus
4 3 2 1 0
Baseline (D-2) (*)/D0 (**)/D-2 +66%
-48% /D-2
SLS effect (D0)
+66% /D0
2% Rapeseed phytosterols (D7)
4 3 2 1 0
Baseline (D-2) Corynebacterium (*)/D0 +88% (**)/D-2
-47% /D-2
SLS effect (D0)
+88% /D0
2% Rapeseed phytosterols (D7)
6 5 4 3 2 1 0
Baseline (D-2) Paracoccus
(*) p<0.05 (**) p<0.01
(*)/D0 (*)/D-2 +88%
-40% /D-2
SLS effect (D0)
+47% /D0
2% Rapeseed phytosterols (D7)
Figure 3: Evaluation of resident commensal relative abundance after SLS exposure compared with 7 day treatment of 2% Rapeseed phytosterols using 16S DNA sequencing. The following symbols denote significance values of p=0.1, p<0.05, p<0.01, and p<0.001 denoted as (°), (*), (**), (***), respectively.
phytosterol formulation was applied only once a day. The treatment with formulations started 24 hours after patch removal (D0). The study was conducted during a period of nine days with check points at day-2 (before patch application), day 0 (1 day after patch removal, before first application of the treatment) and day 7 (after 7 days of formula application). The study was done on the backs of 29 healthy Caucasian female volunteers (Fitzpatricks skin type II or III), ages 18 to 45, with body mass index (BMI) between 18.5 to 29.9 kg/m2 with self- reported thin, dry, and sensitive skin. The application was made once a day by volunteers with the help of someone else. After application, the volunteer massaged the area until complete absorption of the formulation. The last application was done the evening before the final visit.
Skin microbiome analysis The skin microbiome was collected by swabbing a 20 cm2
area of skin on the backs
of the volunteers, after a rest period of five to ten minutes in a climatized room, under a controlled temperature of 21+1°C and a humidity of 45+5%. Swabs underwent a DNA extraction using both mechanical and chemical lysis protocol. DNA was subsequently quantified by fluorimetry and Illumina Next Generation sequencing was performed on a MiSeq for DNA fragment sequence for 16S rRNA. Taxonomic classifications were assigned to OTU (operational taxonomic units) using MOTHUR software (Software version: 1.33.3; database version used for sequence alignment: Greengenes v13.5.99; database version used for taxonomy: Greengenes v 13.5.99; threshold to construct OTUs: 0.03). Results were only considered if all quality
control parameters were met. Relative abundances of taxa (phylum, family, genus), were expressed at baseline (D-2) after SLS Patch (D0) and after product application (D7) by LSmean + standard deviation (adjusted mean and SEM). Statistical analysis was conducted using the following
October 2020
analysis of variance (One-way ANOVA) model for repeated measurements (SAS®
PROC MIXED).
Results Skin barrier damage by a 1% SLS occlusion patch Prior to skin exposure to the 1% SLS occlusion patch, there was an average TEWL value of 11 g/m2h and an average hydration value of 24 AU using the Tewameter and Corneometer, respectively. After 24 hours of exposure and 7 subsequent days with no interventions, there was an increased average TEWL of 17.9 g/m2h (p<0.001) and a lower average corneometry value of 12.0 A.U. (p<0.001). These results indicate that even after
seven days after SLS exposure, there is a significant increase in transepidermal water loss and a significant decrease in skin hydration. Conversely, both the TEWL and corneometry measurements were significantly improved (p<0.05 and p<0.001, respectively) after seven days of application of 2% Rapeseed phytosterols when compared to a control vehicle (Fig 1). Application of 2% Rapeseed phytosterols decreased TEWL by 9% and increased hydration by 25% compared to a control vehicle (p<0.05 and p<0.001, respectively).
Changes in skin microbiome populations We observe a skin microbiome shift in the relative abundance on both the phylum, family, and genus level after 0.5% SLS exposure. On the phylum level, there is a 37% increase in Firmicutes and a 14% decrease in Actinobacteria (Figure 2A). These broader taxonomic changes appear to be driven by relative abundance changes in the genera of Micrococcus, Corynebacterium, and Paracoccus, known skin commensal bacteria. Reductions of Micrococcus, Corynebacterium, and Paracoccus were 39%, 42%, and 36%, respectively. These values were significantly (p<0.05) lower than they were before SLS exposure (Figure 2C). After application of 2% Rapeseed phytosterols
there is a significant (p<0.05) recovery of 66% and 88%, in Micrococcus and Corynebacterium populations, respectively (Fig 3). We also observe a trending increase of Paracoccus populations (p=0.10). Not only were the populations of skin
commensal bacteria reduced after 24 hours of SLS exposure, but we also observed the increase of opportunitistic pathogens. There was a 451 fold increase of Pantoea genus as well as a 210% increase of the Pseudomonas genus. After treatment with 2% Rapeseed phytosterols, there was an 89% (p<0.05) and 62% (p=0.1) reduction of Pantoea and Pseudomonas, respectively (Fig 4).
Discussion and conclusion As expected, SLS exposure increases transepidermal water loss and decreases skin hydration, thus contributing to skin dryness and irritation. Besides disrupting the physical barrier of the skin, SLS also alters the microbiotic barrier by changing the populations of the skin microbiome. This 16S rRNA sequencing-based study confirms previous culture-based studies highlighting the deleterious effects of excessive hygiene on the composition of the skin microbiome.8
Some residential
commensal microorganisms belonging to the phylum Actinobacteria (genera Micrococcus and Corynebacterium) and Proteobacteria (genus Paracoccus) decreased, while some opportunistic pathogenic microorganisms had a population increase (Pseudomonas and Pantoea). These SLS-induced changes can broadly impact benefits from these bacteria. One of the clearest benefits is maintaining the balance of the skin microbiome. Both Micrococcus and Corynebacterium prevent the colonization of pathogens though competition for nutrients on the skin.5
Additionally,
Corynebacterium produces antimicrobial peptides and has been known to reduce the virulence of other pathogens, such as S. aureus.21
Other benefits from the presence of Paracoccus and Micrococcus PERSONAL CARE NORTH AMERICA
Relative abundance of the genus
Relative abundance of the genus
Relative abundance of the genus
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