Consequences of Interaction of a Lipophilic Endotoxin Antagonist with Plasma Lipoproteins

Rose, Jeffrey; Mullarkey, Maureen; Christ, William J.; Hawkins, Lynn D.; Lynn, Melvyn; Kishi, Yoshito; Peteherych, Kathy D.; Rossignol, Daniel P.

doi:10.1128/aac.44.3.504-510.2000

Cited by 35 publications

(37 citation statements)

References 36 publications

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“…In their studies they observed that E5531 was slowly inactivated when it was bound to HDL, while little or no loss of activity occurred when it was associated with LDL, as determined by in vitro assays (16). Preliminary studies with E5564 have yielded similar results (data not shown).…”

Section: Discussionsupporting

confidence: 66%

“…Furthermore, it appears that increases in triglyceride (TG)-rich lipoprotein (TRL; which contains very low density lipoproteins and chylomicrons) and low-density lipoprotein (LDL) cholesterol, TG, and protein levels in plasma significantly increase the levels of TRL and LDL binding of E5531, while decreases in the levels of these fractions in plasma significantly increase the level of HDL binding of E5531. In addition, we have observed a rapid loss of the endotoxin antagonistic activity of E5531 upon binding to HDL but no such loss upon binding to LDL or TRL (16).…”

mentioning

confidence: 82%

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Association of the Endotoxin Antagonist E5564 with High-Density Lipoproteins In Vitro: Dependence on Low-Density and Triglyceride-Rich Lipoprotein Concentrations

Sivak

Cote

MacInnes

et al. 2003

Antimicrob Agents Chemother

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The objective of this study was to determine the distribution profile of the novel endotoxin antagonist E5564 in plasma obtained from fasted human subjects with various lipid concentrations. Radiolabeled E5564 at 1 M was incubated in fasted plasma from seven human subjects with various total cholesterol (TC) and triglyceride (TG) concentrations for 0.5 to 6 h at 37°C. Following these incubations, plasma samples were separated into their lipoprotein and lipoprotein-deficient fractions by ultracentrifugation and were assayed for E5564 radioactivity. TC, TG, and protein concentrations in each fraction were determined by enzymatic assays. Lipoprotein surface charge within control and phosphatidylinositol-treated plasma and E5564's influence on cholesteryl ester transfer protein (CETP) transfer activity were also determined. We observed that the majority of E5564 was recovered in the high-density lipoprotein (HDL) fraction. We further observed that incubation in plasma with increased levels of TG-rich lipoprotein (TRL) lipid (TC and TG) concentrations resulted in a significant increase in the percentage of E5564 recovered in the TRL fraction. In further experiments, E5564 was preincubated in human TRL. Then, these mixtures were incubated in hypolipidemic human plasma for 0.5 and 6 h at 37°C. Preincubation of E5564 in purified TRL prior to incubation in human plasma resulted in a significant decrease in the percentage of drug recovered in the HDL fraction and an increase in the percentage of drug recovered in the TRL and low-density lipoprotein fractions. These findings suggest that the majority of the drug binds to HDLs. Preincubation of E5564 in TRL prior to incubation in normolipidemic plasma significantly decreased the percentage of drug recovered in the HDL fraction. Modifications to the lipoprotein negative charge did not alter the E5564 concentration in the HDL fraction. In addition, E5564 does not influence CETP-mediated transfer activity. Information from these studies could be used to help identify the possible components of lipoproteins which influence the interaction of E5564 with specific lipoprotein particles.Inflammatory shock as a consequence of lipopolysaccharide (LPS) or endotoxin release from gram-negative bacteria remains a serious clinical concern (3). In humans, inflammatory responses to LPS result in the release of cytokines and other cell mediators from monocytes and macrophages, which can cause fever, shock, organ failure, and death (3). A number of different approaches have been investigated to try to treat and/or prevent the septic shock associated with infections caused by gram-negative bacteria, including blocking of one or more of the cytokines induced by LPS (14). Recently, novel amphipathic compounds E5531 and E5564 have been developed as direct antagonists of LPS at the LPS receptor, TLR4 (5).Our laboratory has previously reported that the majority of E5531 (an analogue of E5564 which has chemical properties and pharmacological activity similar to those of E5531) associates with high-d...

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Section: Discussionsupporting

confidence: 66%

mentioning

confidence: 82%

Association of the Endotoxin Antagonist E5564 with High-Density Lipoproteins In Vitro: Dependence on Low-Density and Triglyceride-Rich Lipoprotein Concentrations

Sivak

Cote

MacInnes

et al. 2003

Antimicrob Agents Chemother

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“…In rabbits, the uptake of LPS by the adrenal glands was increased after LPS binding to HDL, which indicates that binding of LPS to HDL results in a decreased recognition by LPS receptors (347,372). Since then, in vivo and in vitro experiments have shown that LPS and LTA bind to and are neutralized by lipid emulsions (177,445), chylomicrons (194,195,447), VLDL (102,194,459,464,576), LDL (102,177,366,459,464,554,576), Lp(a) (385), HDL (102,144,177,374,459,464,535,576), ApoA-I (112, 135, 539), ApoB (112,464), and ApoE (449,555).…”

Section: Anti-inflammatory Rolementioning

confidence: 99%

“…Using a solidphase binding assay, they also observed that in the absence of LBP, LPS preferentially bound to LDL and VLDL. (375,464,535), to LDL and/or VLDL (102,554), or to all lipoproteins (102,459,554,562,576) depending on the lipid and/or protein distribution in the distinct lipoprotein fractions. A correlation between the cholesterol contents of the lipoprotein fractions and LPS association was proposed by Van Lenten et al (554), but with rHDL the neutralizing potency correlates with the phospholipid contents of the particle (72).…”

Section: Anti-inflammatory Rolementioning

confidence: 99%

Receptors, Mediators, and Mechanisms Involved in Bacterial Sepsis and Septic Shock

2003

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Bacterial sepsis and septic shock result from the overproduction of inflammatory mediators as a consequence of the interaction of the immune system with bacteria and bacterial wall constituents in the body. Bacterial cell wall constituents such as lipopolysaccharide, peptidoglycans, and lipoteichoic acid are particularly responsible for the deleterious effects of bacteria. These constituents interact in the body with a large number of proteins and receptors, and this interaction determines the eventual inflammatory effect of the compounds. Within the circulation bacterial constituents interact with proteins such as plasma lipoproteins and lipopolysaccharide binding protein. The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents. The role of individual receptors such as the toll-like receptors and CD14 in the induction of proinflammatory cytokines and adhesion molecules is discussed in detail. In addition, the roles of a number of other receptors that bind bacterial compounds such as scavenger receptors and their modulating role in inflammation are described. Finally, the therapies for the treatment of bacterial sepsis and septic shock are discussed in relation to the action of the aforementioned receptors and proteins

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“…We have previously shown that loss in antagonistic activity can be observed in vitro in human whole blood (Mullarkey et al, 2003) and is likely due to its interaction with plasma lipoproteins (Rose et al, 2000;Wasan et al, 2003). However, higher concentrations of E5564 (Ն1 M) are not quantitatively inactivated in vitro by whole blood, even after overnight incubation (data not shown), indicating that inactivation of E5564 is either time-dependent or is a "saturable" process.…”

Section: Discussionmentioning

confidence: 86%

Extended in Vivo Pharmacodynamic Activity of E5564 in Normal Volunteers with Experimental Endotoxemia

Lynn¹,

Wong²,

Wheeler³

et al. 2003

J Pharmacol Exp Ther

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E5564 is a synthetic antagonist of bacterial endotoxin that has been shown to completely block human endotoxin response. Low doses of E5564 (0.35-3.5 mg) have a long pharmacokinetic half-life, but a surprisingly short ex vivo and in vivo pharmacodynamic half-life (generally less than several hours). To determine whether extended antagonistic activity can be achieved in vivo, this study assesses the pharmacodynamic activity of 4-and 72-h infusions of E5564 into normal volunteers. Administration of 3.5 mg of E5564/h ϫ 72 h completely blocked effects of endotoxin challenge at the end of dosing (72 h), and at 48 and 72 h postdosing. Similarly, a 4-h infusion of E5564, 3 mg/h completely blocked endotoxin administered 8 h postdosing. A lower dose of E5564, 0.5 mg/h ϫ 4 h, ameliorated but did not block most effects of endotoxin 8 h postdosing (p Ͻ 0.05). Finally, the effect of varying plasma lipoprotein content on E5564 activity was studied in subjects having high or low cholesterol levels (Ͼ180 or Ͻ140 mg/dl) after 72-h infusion of 252 mg of E5564. No differences were observed. These results demonstrate that E5564 blocks the effects of endotoxin in a human model of clinical sepsis and indicate its potential in the treatment and/or prevention of clinical sepsis.

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Consequences of Interaction of a Lipophilic Endotoxin Antagonist with Plasma Lipoproteins

Cited by 35 publications

References 36 publications

Association of the Endotoxin Antagonist E5564 with High-Density Lipoproteins In Vitro: Dependence on Low-Density and Triglyceride-Rich Lipoprotein Concentrations

Association of the Endotoxin Antagonist E5564 with High-Density Lipoproteins In Vitro: Dependence on Low-Density and Triglyceride-Rich Lipoprotein Concentrations

Receptors, Mediators, and Mechanisms Involved in Bacterial Sepsis and Septic Shock

Extended in Vivo Pharmacodynamic Activity of E5564 in Normal Volunteers with Experimental Endotoxemia

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