Journal Article
Infection and Immunity, vol. 83, iss. 8, pp. 3026-3034, 2015
Authors
Abdul G. Lone, Erhan Atci, Ryan Renslow, Haluk Beyenal, Susan Noh, Boel Fransson, Nehal Abu-Lail, Jeong-Jin Park, David R. Gang, Douglas R. Call, A. Camilli
Abstract
ABSTRACT
A partial-thickness epidermal explant model was colonized with green fluorescent protein (GFP)-expressing
Staphylococcus aureus
, and the pattern of
S. aureus
biofilm growth was characterized using electron and confocal laser scanning microscopy. The oxygen concentration in explants was quantified using microelectrodes. The relative effective diffusivity and porosity of the epidermis were determined using magnetic resonance imaging, while hydrogen peroxide (H
2
O
2
) concentration in explant media was measured by using microelectrodes. Secreted proteins were identified and quantified using elevated-energy mass spectrometry (MS
E
).
S. aureus
biofilm grows predominantly in lipid-rich areas around hair follicles and associated skin folds. Dissolved oxygen was selectively depleted (2- to 3-fold) in these locations, but the relative effective diffusivity and porosity did not change between colonized and control epidermis. Histological analysis revealed keratinocyte damage across all the layers of colonized epidermis after 4 days of culture. The colonized explants released significantly (
P
< 0.01) more antioxidant proteins of both epidermal and
S. aureus
origin, consistent with elevated H
2
O
2
concentrations found in the media from the colonized explants (
P
< 0.001). Caspase-14 was also elevated significantly in the media from the colonized explants. While H
2
O
2
induces primary keratinocyte differentiation, caspase-14 is required for terminal keratinocyte differentiation and desquamation. These results are consistent with a localized biological impact from
S. aureus
in response to colonization of the skin surface.
