Leptospiral lipopolysaccharide activates cells through a TLR2-dependent mechanism.
Leptospira interrogans are zoonotic pathogens that have been linked to a recent increased incidence of morbidity and mortality in highly populated tropical urban centers. They are unique among invasive spirochetes in that they contain outer membrane lipopolysaccharide (LPS) as well as lipoproteins. Here we show that both these leptospiral outer membrane constituents activate macrophages through CD14 and the Toll-like receptor 2 (TLR2). Conversely, it seems that TLR4, a central component for recognition of Gram-negative LPS, is not involved in cellular responses to L. interrogans. We also show that for intact L. interrogans, it is LPS, not lipoprotein, that constitutes the predominant signaling component for macrophages through a TLR2 pathway. These data provide a basis for understanding the innate immune response caused by leptospirosis and demonstrate a new ligand specificity for TLR2.
Werts
C
C
Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Tapping
R I
RI
Mathison
J C
JC
Chuang
T H
TH
Kravchenko
V
V
Saint Girons
I
I
Haake
D A
DA
Godowski
P J
PJ
Hayashi
F
F
Ozinsky
A
A
Underhill
D M
DM
Kirschning
C J
CJ
Wagner
H
H
Aderem
A
A
Tobias
P S
PS
Ulevitch
R J
RJ
D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D029721:Drosophila Proteins; D006801:Humans; D007921:Leptospira interrogans / Q000276:immunology* / Q000472:pathogenicity*; D007922:Leptospirosis / Q000276:immunology; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology / Q000633:toxicity*; D008074:Lipoproteins / Q000276:immunology; D008262:Macrophage Activation / Q000187:drug effects* / Q000276:immunology; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
D029721:Drosophila Proteins; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008074:Lipoproteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors