Cutting edge: cell surface expression and lipopolysaccharide signaling via the toll-like receptor 4-MD-2 complex on mouse peritoneal macrophages.
The human MD-2 molecule is associated with the extracellular domain of human Toll-like receptor 4 (TLR4) and greatly enhances its LPS signaling. The human TLR4-MD-2 complex thus signals the presence of LPS. Little is known, however, about cell surface expression and LPS signaling of the TLR4-MD-2 complex in vivo. We cloned mouse MD-2 molecularly and established a unique mAb MTS510, which reacted selectively with mouse TLR4-MD-2 but not with TLR4 alone in flow cytometry. Mouse MD-2 expression in TLR4-expressing cells enhanced LPS-induced NF-kappaB activation, which was clearly inhibited by MTS510. Thioglycolate-elicited peritoneal macrophages expressed TLR4-MD-2, which was rapidly down-regulated in the presence of LPS. Moreover, LPS-induced TNF-alpha production by peritoneal macrophages was inhibited by MTS510. Collectively, the TLR4-MD-2 complex is expressed on macrophages in vivo and senses and signals the presence of LPS.
Akashi
S
S
Department of Immunology, Saga Medical School, Nabeshima, Japan.
Shimazu
R
R
Ogata
H
H
Nagai
Y
Y
Takeda
K
K
Kimoto
M
M
Miyake
K
K
D000276:Adjuvants, Immunologic / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D029721:Drosophila Proteins; D008070:Lipopolysaccharides / Q000276:immunology*; D051218:Lymphocyte Antigen 96; D008262:Macrophage Activation; D017737:Macrophages, Peritoneal / Q000276:immunology* / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology*; D013864:Thioglycolates / Q000494:pharmacology; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014162:Transfection
D000276:Adjuvants, Immunologic; D000954:Antigens, Surface; D029721:Drosophila Proteins; D008070:Lipopolysaccharides; D051218:Lymphocyte Antigen 96; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D013864:Thioglycolates; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors