Toll-like receptor agonists regulate beta-defensin 2 release in hair follicle.
BACKGROUND
Skin is constantly in contact with different pathogens, which are present in the environment. The hair follicle is particularly susceptible to this microbial invasion as it offers an easy way of access for microorganisms; for this reason it is equipped with defence mechanisms to avoid frequent infections.


OBJECTIVE
To analyse the expression pattern of four different members of the toll-like receptor (TLR) family in murine hair follicles and to evaluate the effects of their activation by their specific microbiota-derived agonists, in terms of production of the antimicrobial peptide beta-defensin 2 (DEFB2).


METHODS
TLR and DEFB2 protein expression was investigated by immunohistochemistry on murine skin samples.


RESULTS
Murine hair follicle expresses TLR2, TLR4 and TLR5; agonists of TLR2, TLR4 and TLR5 but not of TLR9 induced DEFB2 production in this compartment. The strongest DEFB2 expression was observed following TLR4 activation by lipopolysaccharide.


CONCLUSIONS
Our data show that the hair follicle is equipped with TLR2, TLR4 and TLR5, and that these receptors are able to respond to microbial stimuli inducing the production of DEFB2 by epithelial cells. This immune response might be important in preserving the skin from microorganism infections.
Selleri
S
S
Department of Human Morphology, Università Degli Studi di Milano, via Mangiagalli 31, 20133 Milan, Italy.
Arnaboldi
F
F
Palazzo
M
M
Gariboldi
S
S
Zanobbio
L
L
Opizzi
E
E
Shirai
Y F
YF
Balsari
A
A
Rumio
C
C
D000818:Animals; D018859:Hair Follicle / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D051198:Toll-Like Receptor 5 / Q000378:metabolism; D051217:Toll-Like Receptor 9 / Q000378:metabolism; D051193:Toll-Like Receptors / Q000378:metabolism*; D023083:beta-Defensins / Q000276:immunology* / Q000378:metabolism
C106641:DEFB4A protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051198:Toll-Like Receptor 5; D051217:Toll-Like Receptor 9; D051193:Toll-Like Receptors; D023083:beta-Defensins