A novel class of endotoxin receptor agonists with simplified structure, toll-like receptor 4-dependent immunostimulatory action, and adjuvant activity.
A series of novel, synthetic compounds containing lipids linked to a phosphate-containing acyclic backbone are shown to have similar biological properties to lipopolysaccharide (LPS). These compounds showed intrinsic agonistic properties when tested for their ability to stimulate tumor necrosis factor-alpha in human whole blood and interleukin-6 in U373 human glioblastoma cells without added LPS coreceptor CD14. The presence of the LPS antagonist E5564 completely blocked responses, suggesting that the novel compounds and LPS share a common mechanism of cell activation. Stereoselectivity of the molecules was observed in vitro; compounds with an R,R,R,R-configuration were strongly agonistic, whereas compounds with an R,S,S,R-configuration were much weaker in their activity on human whole blood and U373 cells. We also tested the effect of the compounds in cells transfected with the LPS receptor Toll-like receptor 4 (TLR4), with similar results, further supporting a shared mechanism with LPS. This was confirmed in vivo where the agonists failed to elicit cytokine responses in C3H/HeJ mice lacking TLR4 signaling. Because LPS-like molecules enhance immune responses, the compounds were mixed with tetanus toxoid and administered to mice in an immunization protocol to test for adjuvant activity. They enhanced the generation of specific antibodies against tetanus toxoid. Our results indicate that these unique compounds behave as agonists of TLR4, resulting in responses similar to those elicited by LPS. They display adjuvant activity in vivo and may be useful for the development of vaccine therapies.
Hawkins
Lynn D
LD
Department of Medicinal Chemistry, Signal Transduction Research, Eisai Research Institute, Andover, Massachusetts 01810, USA.
Ishizaka
Sally T
ST
McGuinness
Pamela
P
Zhang
Huiming
H
Gavin
Wendy
W
DeCosta
Bruce
B
Meng
Zhaoyang
Z
Yang
Hu
H
Mullarkey
Maureen
M
Young
Donna W
DW
Yang
Hua
H
Rossignol
Daniel P
DP
Nault
Anneliese
A
Rose
Jeffrey
J
Przetak
Melinda
M
Chow
Jesse C
JC
Gusovsky
Fabian
F
D000276:Adjuvants, Immunologic / Q000737:chemistry / Q000494:pharmacology*; D000293:Adolescent; D000328:Adult; D000818:Animals; D002460:Cell Line; D004187:Disaccharides / Q000494:pharmacology; D029721:Drosophila Proteins; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008050:Lipid A / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000737:chemistry; D008297:Male; D008562:Membrane Glycoproteins / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D018716:Molecular Mimicry; D016328:NF-kappa B / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects*; D011971:Receptors, Immunologic / Q000819:agonists*; D013329:Structure-Activity Relationship; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D000276:Adjuvants, Immunologic; D004187:Disaccharides; D029721:Drosophila Proteins; D015850:Interleukin-6; D008050:Lipid A; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; C048071:endotoxin receptor