Induction of toll-like receptors by Propionibacterium acnes.
BACKGROUND
The bacterium Propionibacterium acnes is involved in the induction and maintenance of the inflammatory phase of acne. Recent studies have found that keratinocytes express toll-like receptors (TLRs) implicated in immediate immunity. No studies have, to date, been carried out on the action of P. acnes upon TLR activation in keratinocytes.


OBJECTIVE
Focusing on the inflammatory phase of acne, to clarify the role of P. acnes in immediate immunity by inducing expression of TLR-2 and TLR-4 by keratinocytes. We also studied how the secretion and expression of matrix metalloproteinase (MMP)-9 is induced by P. acnes.


METHODS
The work was carried out on two levels: in vivo with the study of the expression of TLR-2 and TLR-4 proteins in biopsies of acne lesions and in vitro on cultured keratinocyte monolayers to study the modulating effects of P. acnes on the expression of TLR-2 and TLR-4 and also on the expression and secretion of MMP-9.


RESULTS
Our findings reveal that in vivo TLR-2 and TLR-4 expression is increased in the epidermis of acne lesions. In vitro, an increase in TLR-2 and TLR-4 expression by human keratinocytes occurred in the first hours of incubation with bacterial fractions as well as an increase of the expression and secretion by the keratinocytes of MMP-9, which plays a role in inflammation.


CONCLUSIONS
This work demonstrates that P. acnes induces TLR expression and that this mechanism could play an essential role in acne-linked inflammation. These receptors could be involved notably in acute acne.
Jugeau
S
S
INSERM U601, CHU, Pl. A. Ricordeau, 44095 Nantes, France.
Tenaud
I
I
Knol
A C
AC
Jarrousse
V
V
Quereux
G
G
Khammari
A
A
Dreno
B
B
D000152:Acne Vulgaris / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D002462:Cell Membrane / Q000276:immunology; D002470:Cell Survival; D002478:Cells, Cultured; D002648:Child; D005434:Flow Cytometry; D016908:Gram-Positive Bacterial Infections / Q000276:immunology*; D006801:Humans; D015603:Keratinocytes / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D019394:Ki-67 Antigen / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D011425:Propionibacterium acnes / Q000276:immunology*; D012867:Skin / Q000276:immunology; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism*
D019394:Ki-67 Antigen; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D020780:Matrix Metalloproteinase 9