The role of the skin barrier in modulating the effects of common skin microbial species on the inflammation, differentiation and proliferation status of epidermal keratinocytes.
BACKGROUND
Skin resident microbial species are often thought of either as pathogenic or commensal. However, little is known about the role of the skin barrier in modulating their potential for causing disease. To investigate this question we measured the effects of three microbial species commonly found on the skin (Staphylococcus epidermidis, Staphylococcus aureus, and Propionibacterium acnes) on a reconstructed human epidermal model by either applying the bacteria on the model surface (intact barrier) or adding them to the culture medium (simulating barrier breach).


RESULTS
When added to the medium, all of the tested species induced inflammatory responses and keratinocyte cell death with species-specific potency. P. acnes and S. epidermidis induced specific alterations in the expression of keratinocyte differentiation and proliferation markers, suggesting a barrier reparation response. S. aureus induced complete keratinocyte cell death. On the contrary, topically applied S. epidermidis and P. acnes caused no inflammatory response even when tested at high concentrations, while topical S. aureus induced a weak reaction. None of the tested species were able to alter the expression of keratinocyte differentiation or expression markers, when applied topically.


CONCLUSIONS
We show that the skin barrier prevents the effects of common skin bacteria on epidermal keratinocyte inflammation, differentiation and proliferation and highlight the importance of skin barrier in defending against the pathogenic effects of common skin bacteria.
Johnson & Johnson Santé Beauté France, 1 rue Camille Desmoulins, Issy-les-Moulineaux 92787, France. GStamata@its.jnj.com.
Patrick
P
Duckney
Heng Kuan
HK
Wong
José
J
Serrano
Diaraf
D
Yaradou
Thierry
T
Oddos
Georgios N
GN
Stamatas
D002454:Cell Differentiation; D049109:Cell Proliferation; D003470:Culture Media; D000078404:Epidermal Cells; D004817:Epidermis / Q000382:microbiology; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000382:microbiology
D003470:Culture Media