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Production by Macrophages In Vitro and In Vivo and Prevent Endotoxin-Mediated Toxic Shock


*
Institute of Medical Microbiology, Immunology and Hygiene, Technical University of Munich, Munich, Germany;
MorphoSys, Martinsried/Munich, Germany; and
Institute of Medical Immunology, Humboldt University of Berlin, Berlin, Germany
Lipid A, the conserved portion of endotoxin, is the major mediator
of septic shock; therefore, endotoxin-neutralizing molecules could have
important clinical applications. Here we show that peptides derived
from Limulus anti-LPS factor (LALF),
bactericidal/permeability increasing protein (BPI) and
endotoxin-binding protein, bind to lipid A and block the recombinant
LALF/lipid A interaction in vitro. Because their neutralizing capacity
in vitro as well as in vivo has been limited, we created hybrid
peptides comprising two endotoxin-binding domains. The hybrid molecule
LL-10-H-14, containing endotoxin-binding domains from LALF and
endotoxin-binding protein, turned out to be the most active peptide
within the series of peptides tested here to inhibit the CD14/lipid A
interaction and is able in vitro to block the endotoxin-induced TNF-
release of murine macrophages up to 90%. Furthermore, LL-10-H-14 not
only reduced peak serum levels of TNF-
of mice when preinjected but
also reduced TNF-
levels when given 15 min after the endotoxin
challenge. As compared with other peptides, only LL-10-H-14 is able to
strongly decrease endotoxin-stimulated TNF-
release by human
macrophage cell lines as well as by PBMC. Furthermore, the hybrid
peptide is protective against endotoxin-provoked lethal shock. As such,
LL-10-H-14 could have prophylactic and/or therapeutic properties in
humans for the management of septic shock.
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