Details

Autor(en) / Beteiligte

• Gioannini, Theresa L.
• Teghanemt, Athmane
• Zhang, DeSheng
• Coussens, Nathan P.
• Dockstader, Wendie
• Ramaswamy, S.
• Weiss, Jerrold P.
• Gotschlich, Emil C.

Titel

Isolation of an Endotoxin-MD-2 Complex That Produces Toll-Like Receptor 4-Dependent Cell Activation at Picomolar Concentrations

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2004-03, Vol.101 (12), p.4186-4191

Ort / Verlag

United States: National Academy of Sciences

Erscheinungsjahr

2004

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Host proinflammatory responses to minute amounts of endotoxins derived from many Gram-negative bacteria require the interaction of lipopolysaccharide-binding protein (LBP), CD14, Toll-like receptor 4 (TLR4) and MD-2. Optimal sensitivity to endotoxin requires an ordered series of endotoxin-protein and protein-protein interactions. At substoichiometric concentrations, LBP facilitates delivery of endotoxin aggregates to soluble CD14 (sCD14) to form monomeric endotoxin-sCD14 complexes. Subsequent interactions of endotoxin-sCD14 with TLR4 and/or MD-2 have not been specifically defined. This study reports the purification of a stable, monomeric, bioactive endotoxin-MD-2 complex generated by treatment of endotoxin-sCD14 with recombinant MD-2. Efficient generation of this complex occurred at picomolar concentrations of endotoxin and nanogram per milliliter doses of MD-2 and required presentation of endotoxin to MD-2 as a monomeric endotoxin-CD14 complex. TLR4-dependent delivery of endotoxin to human embryonic kidney (HEK) cells and cell activation at picomolar concentrations of endotoxin occurred with the purified endotoxin-MD-2 complex, but not with purified endotoxin aggregates with or without LBP and/or sCD14. The presence of excess MD-2 inhibited delivery of endotoxin-MD-2 to HEK/TLR4 cells and cell activation. These findings demonstrate that TLR4-dependent activation of host cells by picomolar concentrations of endotoxin occurs by sequential interaction and transfer of endotoxin to LBP, CD14, and MD-2 and simultaneous engagement of endotoxin and TLR4 by MD-2.