595 Specificities of Microbiota From Sensitive Skin
Recent research indicates that the bacterial diversity and the relative abundance of different
microbes present on and in the skin may contribute to skin barrier dysfunction.22,23 In this
study, we have shown in the SS that the Staphylococcus genus level was decreased, but that
a 2.8-fold increase of S. aureus was observed with a correlated decrease of S. epidermidis,
S. capitis, S. equorum. S. hominis, or S. saprophyticus for the more abundant. Therefore, it seems
important to pay attention to S. aureus, S. epidermidis, S. hominis, S. capitis, or other coagulase
negative Staphylococci counterparts to help improve SS condition. Firstly, it was shown that a
S. epidermidis decrease correlates to high LAST score.14 Secondly, S. aureus secretes multiple
virulence factors known to contribute to skin barrier dysfunction (multiple metalloproteases
disrupting proteolytic balance in the skin).24 Finally, S. epidermidis and hominis produce
strain-specific, highly potent antimicrobial peptides (AMPs) that selectively kill S. aureus
and synergize with the human AMP LL-37,25 and some S. capitis also express strong
antibacterial activity against a range of Gram-positive species, most notably including
S. aureus strains with resistance to methicillin (MRSA) and strains with intermediate
resistance to vancomycin (VISA).26
After the analysis of the metagenome between the two cohorts, we used DBMT to isolate
bacterial species in culture from NS and SS and create a bacterial collection from these
clinical isolates. We previously observed that this technology was particularly suitable for
isolating bacteria that are known to be difficult to isolate and cultivate. Here we isolated
hundreds of species from each cohort and selected 31 strains as a representative for each.
On these 62 strains, we evaluated the effect of some preselected ingredients on the growth
profile of the selected species from both collections. Due to different bacterial growth
conditions and responsiveness to active ingredients, we monitored the growth over 72 hours,
with a dose range of the active ingredients. This strategy could be used for identifying
prebiotic ingredients for specific species of interest. For example, some species have been
shown to decrease with age and could therefore be used to restore a growth pattern closer
to a younger skin profile. For SS, the same methodology could be applied to compensate
the switch in abundance observed in SS at least for the common species highlighted and
including, if feasible, the less common microbe genera described. This system can also
be used to identify ingredients with minimal effects, those that can also be said to be
“microbiome friendly.”
Finally, when studying the potential damage induced on keratinocytes by C. acnes, more
abundant species found in the two cohorts of this study were evidenced. We determined
that C. acnes strains isolated from SS decreased the viability of keratinocytes (SS4 and SS8)
while two strongly induced IL-8 release by keratinocytes (SS4 and SS7) when compared to
the effect the species from NS. Consequently, in addition to showing an increase of C. acnes
in the SS, we also demonstrated that some specific strains present on the SS were more
detrimental to keratinocytes and could contribute to localized inflammation. This method
and its findings could be compared with those of Lu et al.,17 who examined the capacity
of standard S. epidermidis (ATCC12228) and S. aureus (USA 800) species to stimulate IL-8
secretion in keratinocytes, comparing them to S. epidermidis, S. aureus, S. capitis, and M.
luteus species isolated from a panelist with SS. They observed a higher IL-8 induction with
S. aureus when from SS, and also a very high induction with S. capitis and M. luteus from
SS. Altogether these results highlight the importance of isolating species specific to SS in
an effort to later search for ingredients that could not only help to compensate the shifts in
prevalence and/or abundance of these species between NS skin and SS, but also to regulate
their related virulence potential.
Recent research indicates that the bacterial diversity and the relative abundance of different
microbes present on and in the skin may contribute to skin barrier dysfunction.22,23 In this
study, we have shown in the SS that the Staphylococcus genus level was decreased, but that
a 2.8-fold increase of S. aureus was observed with a correlated decrease of S. epidermidis,
S. capitis, S. equorum. S. hominis, or S. saprophyticus for the more abundant. Therefore, it seems
important to pay attention to S. aureus, S. epidermidis, S. hominis, S. capitis, or other coagulase
negative Staphylococci counterparts to help improve SS condition. Firstly, it was shown that a
S. epidermidis decrease correlates to high LAST score.14 Secondly, S. aureus secretes multiple
virulence factors known to contribute to skin barrier dysfunction (multiple metalloproteases
disrupting proteolytic balance in the skin).24 Finally, S. epidermidis and hominis produce
strain-specific, highly potent antimicrobial peptides (AMPs) that selectively kill S. aureus
and synergize with the human AMP LL-37,25 and some S. capitis also express strong
antibacterial activity against a range of Gram-positive species, most notably including
S. aureus strains with resistance to methicillin (MRSA) and strains with intermediate
resistance to vancomycin (VISA).26
After the analysis of the metagenome between the two cohorts, we used DBMT to isolate
bacterial species in culture from NS and SS and create a bacterial collection from these
clinical isolates. We previously observed that this technology was particularly suitable for
isolating bacteria that are known to be difficult to isolate and cultivate. Here we isolated
hundreds of species from each cohort and selected 31 strains as a representative for each.
On these 62 strains, we evaluated the effect of some preselected ingredients on the growth
profile of the selected species from both collections. Due to different bacterial growth
conditions and responsiveness to active ingredients, we monitored the growth over 72 hours,
with a dose range of the active ingredients. This strategy could be used for identifying
prebiotic ingredients for specific species of interest. For example, some species have been
shown to decrease with age and could therefore be used to restore a growth pattern closer
to a younger skin profile. For SS, the same methodology could be applied to compensate
the switch in abundance observed in SS at least for the common species highlighted and
including, if feasible, the less common microbe genera described. This system can also
be used to identify ingredients with minimal effects, those that can also be said to be
“microbiome friendly.”
Finally, when studying the potential damage induced on keratinocytes by C. acnes, more
abundant species found in the two cohorts of this study were evidenced. We determined
that C. acnes strains isolated from SS decreased the viability of keratinocytes (SS4 and SS8)
while two strongly induced IL-8 release by keratinocytes (SS4 and SS7) when compared to
the effect the species from NS. Consequently, in addition to showing an increase of C. acnes
in the SS, we also demonstrated that some specific strains present on the SS were more
detrimental to keratinocytes and could contribute to localized inflammation. This method
and its findings could be compared with those of Lu et al.,17 who examined the capacity
of standard S. epidermidis (ATCC12228) and S. aureus (USA 800) species to stimulate IL-8
secretion in keratinocytes, comparing them to S. epidermidis, S. aureus, S. capitis, and M.
luteus species isolated from a panelist with SS. They observed a higher IL-8 induction with
S. aureus when from SS, and also a very high induction with S. capitis and M. luteus from
SS. Altogether these results highlight the importance of isolating species specific to SS in
an effort to later search for ingredients that could not only help to compensate the shifts in
prevalence and/or abundance of these species between NS skin and SS, but also to regulate
their related virulence potential.
