The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Melvyn Lynn - One of the best experts on this subject based on the ideXlab platform.
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intravenous infusions of Eritoran in healthy Japanese and Caucasian men
2016Co-Authors: Naoki Aikawa, Melvyn Lynn, Daniel P Rossignol, Olena Sivak, Y Okubo, Edgar Schuck, Yasumi Kitahara, T Nakano, Nancy Y Wong, Kishor M WasanAbstract:Eritoran, a synthetic analogue of lipid A, has been shown to bind to TLR4/MD-2 complex and thereby block the interaction of endotoxins with TLR4. We report here the results of a study conducted to assess the single-dose safety and tolerability, as well as the pharmacokinetics and pharmacodynamics, of Eritoran infusion in Japanese and Caucasian healthy adult men. Sixty-four men (aged 20–45 years; body mass index 18–30 kg/m2) were randomized into four groups: 4-mg total dose (six Japanese and six Caucasian men); 12-mg total dose (12 Japanese and 12 Caucasian men); 28-mg total dose (six Japanese and six Caucasian men); and placebo (eight Japanese and eight Caucasian men). Eritoran in single doses up to 28 mg over 4 h was well tolerated, with no apparent ethnic differences noted. Plasma concentrations were slightly higher in Japanese versus Caucasian men; these differences were not significant after adjustment for differences in body mass (clearance: approximately 1.2 ml/h/kg; volume of distribution at steady state: approximately 0.07 l/kg). The ex vivo endotoxin inhibitory activity of Eritoran was similar in Japanese and Caucasian men. The data do not indicate any need for clinical dose adjustment for possible ethnic-based differences in drug distribution or metabolism
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safety pharmacokinetics and pharmacodynamics of four hour intravenous infusions of Eritoran in healthy japanese and caucasian men
Innate Immunity, 2012Co-Authors: Naoki Aikawa, Melvyn Lynn, Daniel P Rossignol, Olena Sivak, Y Okubo, Edgar Schuck, Yasumi Kitahara, T Nakano, Nancy Y Wong, Kishor M WasanAbstract:Eritoran, a synthetic analogue of lipid A, has been shown to bind to TLR4/MD-2 complex and thereby block the interaction of endotoxins with TLR4. We report here the results of a study conducted to ...
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deactivation of the lipopolysaccharide antagonist Eritoran e5564 by high density lipoprotein associated apolipoproteins
Innate Immunity, 2012Co-Authors: Jacklyn G Fleischer, Melvyn Lynn, Dan Rossignol, Gordon A Francis, Teddy Chan, Kishor M WasanAbstract:Lipid A, the active moiety of LPS, exerts its effects through interaction with TLR4, triggering a signalling cascade that results in the release of pro-inflammatory cytokines. Eritoran is a lipid A analogue that competes with LPS for binding to TLR4; however, after intravenous administration, it undergoes a time-dependent deactivation as a consequence of binding to high-density lipoproteins (HDLs). The site of Eritoran association with HDL remains unknown. Therefore the aim of this study was to determine if HDL-associated apolipoproteins A1, A2, serum amyloid A (SAA) and C1, inhibit the ability of Eritoran to block LPS-induced TNF-α release from whole blood. Eritoran activity after LPS stimulation in human whole blood was assessed in the presence of reconstituted HDL (rHDL) containing different apos. In rHDL, the major apolipoproteins in both the healthy and septic state, A1 and SAA, caused a significant reduction in Eritoran antagonistic activity and had a greater effect than minor apolipoproteins A2 and C1. Apolipoproteins associated with HDL are likely to facilitate Eritoran deactivation. Apolipoproteins A1 and SAA should be of particular focus as they are the major apos found on HDL in both the healthy and septic state. Further evaluation of the physical association between apolipoproteins and Eritoran should be explored.
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influence of severity of illness on the effects of Eritoran tetrasodium e5564 and on other therapies for severe sepsis
Shock, 2011Co-Authors: Andre C Kalil, Steven P. Larosa, Melvyn Lynn, Jagadish Gogate, Steven M OpalAbstract:Disease severity varies widely in patients with severe sepsis. Eritoran tetrasodium (E5564), a TLR4 antagonist, blocks the binding of endotoxin and is being evaluated as a novel therapy for severe sepsis. This analysis aimed to assess the efficacy of Eritoran based on severity of illness and similar effects in other recent sepsis trials. Prospective covariates from a randomized, double-blind, placebo-controlled, phase 2 trial were analyzed for treatment interaction measured by 28-day mortality. Five statistical interaction methodologies were used. The modified intent-to-treat population (n = 292), all-cause 28-day mortality was as follows: placebo, 33.3% (32/96); Eritoran 45 mg/105 mg, 29.6% (58/196). Logistic regression analysis identified Acute Physiology and Chronic Health Evaluation II scores, predicted-risk-of-mortality scores, IL-6, age, sex, race, and Eritoran use as associated with survival. Significant treatment interactions were observed (Eritoran vs. placebo) for baseline covariates: Acute Physiology and Chronic Health Evaluation II (P = 0.035), predicted-risk-of-mortality scores (P = 0.008), number of organ failures (P = 0.079), international normalized ratio (P = 0.05), and acute physiology score (P = 0.039). I analysis showed that 38% of the total Eritoran treatment variance was explained by the severity-of-illness heterogeneity rather than by chance. No interactions observed with other variables. Consistent with the finding in this Eritoran trial, other sepsis trials (IL-1 receptor antagonist, TNFsr-p55, antithrombin, drotrecogin alfa-activated) also demonstrated significant treatment by severity interaction. Potential survival benefits of Eritoran in severe sepsis patients were associated with high severity of illness. These findings were used to design a phase 3 trial. Similar treatment by severity-of-illness interaction was found in most recent sepsis trials.
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safety pharmacokinetics and pharmacodynamics of 4 hour intravenous infusion of Eritoran tetrasodium in healthy japanese and caucasian males
Critical Care, 2011Co-Authors: Y Okubo, Melvyn Lynn, Daniel P Rossignol, Olena Sivak, Naoki Aikawa, Yn Wong, Edgar Schuck, Yasumi Kitahara, T Nakano, Kishor M WasanAbstract:Activation of TLR4 signaling by endotoxin is believed to be a primary mediator of sepsis and septic shock, via excessive production of cytokines and proinflammatory mediators [1]. Eritoran tetrasodium (hereafter Eritoran), a synthetic analog of the endotoxin constituent lipid A, binds to the TLR4/MD-2 complex and thereby blocks the interaction of endotoxin with TLR4 [2]. Eritoran is being investigated for the treatment of severe sepsis [3]. We report results of a study conducted to assess the single-dose safety and tolerability, as well as pharmacokinetics and pharmacodynamics, of Eritoran infusion in Japanese and Caucasian healthy adult males.
Kari Ann Shirey - One of the best experts on this subject based on the ideXlab platform.
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Influenza “Trains” the Host for Enhanced Susceptibility to Secondary Bacterial Infection
'American Society for Microbiology', 2019Co-Authors: Kari Ann Shirey, Fabian Gusovsky, Jorge C G Blanco, Darren J. Perkins, Wendy Lai, Wei Zhang, Lurds R. Fernando, Stefanie N VogelAbstract:Enhanced susceptibility to 2° bacterial infections following infection with influenza virus is a global health concern that accounts for many hospitalizations and deaths, particularly during pandemics. The complexity of the impaired host immune response during 2° bacterial infection has been widely studied. Both type I IFN and neutrophil dysfunction through decreased chemokine production have been implicated as mechanisms underlying enhanced susceptibility to 2° bacterial infections. Our findings support the conclusion that selective suppression of CXCL1/CXCL2 represents an IFN-β-mediated “training” of the macrophage transcriptional response to TLR2 agonists and that blocking of TLR4 therapeutically with Eritoran after influenza virus infection reverses this suppression by blunting influenza-induced IFN-β.We previously reported that the Toll-like receptor 4 (TLR4) antagonist Eritoran blocks acute lung injury (ALI) therapeutically in mouse and cotton rat models of influenza. However, secondary (2°) bacterial infection following influenza virus infection is associated with excess morbidity and mortality. Wild-type (WT) mice infected with mouse-adapted influenza A/Puerto Rico/8/34 virus (PR8) and, 7 days later, with Streptococcus pneumoniae serotype 3 (Sp3) exhibited significantly enhanced lung pathology and lethality that was reversed by Eritoran therapy after PR8 infection but before Sp3 infection. Cotton rats infected with nonadapted pH1N1 influenza virus and then superinfected with methicillin-resistant Staphylococcus aureus also exhibited increased lung pathology and serum high-mobility-group box 1 (HMGB1) levels, both of which were blunted by Eritoran therapy. In mice, PR8 infection suppressed Sp3-induced CXCL1 and CXCL2 mRNA, reducing neutrophil infiltration and increasing the bacterial burden, all of which were reversed by Eritoran treatment. While beta interferon (IFN-β)-deficient (IFN-β−/−) mice are highly susceptible to PR8, they exhibited delayed death upon Sp3 superinfection, indicating that while IFN-β was protective against influenza, it negatively impacted the host response to Sp3. IFN-β-treated WT macrophages selectively suppressed Sp3-induced CXCL1/CXCL2 transcriptionally, as evidenced by reduced recruitment of RNA polymerase II to the CXCL1 promoter. Thus, influenza establishes a “trained” state of immunosuppression toward 2° bacterial infection, in part through the potent induction of IFN-β and its downstream transcriptional regulation of chemokines, an effect reversed by Eritoran
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serum high mobility group box 1 as a biomarker and a therapeutic target during respiratory virus infections
Mbio, 2018Co-Authors: Mira C Patel, Kari Ann Shirey, Marina S Boukhvalova, Stefanie N Vogel, Jorge C G BlancoAbstract:Host-derived "danger-associated molecular patterns" (DAMPs) contribute to innate immune responses and serve as markers of disease progression and severity for inflammatory and infectious diseases. There is accumulating evidence that generation of DAMPs such as oxidized phospholipids and high-mobility-group box 1 (HMGB1) during influenza virus infection leads to acute lung injury (ALI). Treatment of influenza virus-infected mice and cotton rats with the Toll-like receptor 4 (TLR4) antagonist Eritoran blocked DAMP accumulation and ameliorated influenza virus-induced ALI. However, changes in systemic HMGB1 kinetics during the course of influenza virus infection in animal models and humans have yet to establish an association of HMGB1 release with influenza virus infection. To this end, we used the cotton rat model that is permissive to nonadapted strains of influenza A and B viruses, respiratory syncytial virus (RSV), and human rhinoviruses (HRVs). Serum HMGB1 levels were measured by an enzyme-linked immunosorbent assay (ELISA) prior to infection until day 14 or 18 post-infection. Infection with either influenza A or B virus resulted in a robust increase in serum HMGB1 levels that decreased by days 14 to 18. Inoculation with the live attenuated vaccine FluMist resulted in HMGB1 levels that were significantly lower than those with infection with live influenza viruses. RSV and HRVs showed profiles of serum HMGB1 induction that were consistent with their replication and degree of lung pathology in cotton rats. We further showed that therapeutic treatment with Eritoran of cotton rats infected with influenza B virus significantly blunted serum HMGB1 levels and improved lung pathology, without inhibiting virus replication. These findings support the use of drugs that block HMGB1 to combat influenza virus-induced ALI.IMPORTANCE Influenza virus is a common infectious agent causing serious seasonal epidemics, and there is urgent need to develop an alternative treatment modality for influenza virus infection. Recently, host-derived DAMPs, such as oxidized phospholipids and HMGB1, were shown to be generated during influenza virus infection and cause ALI. To establish a clear link between influenza virus infection and HMGB1 as a biomarker, we have systematically analyzed temporal patterns of serum HMGB1 release in cotton rats infected with nonadapted strains of influenza A and B viruses and compared these patterns with a live attenuated influenza vaccine and infection by other respiratory viruses. Towards development of a new therapeutic modality, we show herein that blocking serum HMGB1 levels by Eritoran improves lung pathology in influenza B virus-infected cotton rats. Our study is the first report of systemic HMGB1 as a potential biomarker of severity in respiratory virus infections and confirms that drugs that block virus-induced HMGB1 ameliorate ALI.
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Serum High-Mobility-Group Box 1 as a Biomarker and a Therapeutic Target during Respiratory Virus Infections
American Society for Microbiology, 2018Co-Authors: Mira C Patel, Kari Ann Shirey, Marina S Boukhvalova, Stefanie N Vogel, Jorge C G Blanco, Alan SherAbstract:Host-derived “danger-associated molecular patterns” (DAMPs) contribute to innate immune responses and serve as markers of disease progression and severity for inflammatory and infectious diseases. There is accumulating evidence that generation of DAMPs such as oxidized phospholipids and high-mobility-group box 1 (HMGB1) during influenza virus infection leads to acute lung injury (ALI). Treatment of influenza virus-infected mice and cotton rats with the Toll-like receptor 4 (TLR4) antagonist Eritoran blocked DAMP accumulation and ameliorated influenza virus-induced ALI. However, changes in systemic HMGB1 kinetics during the course of influenza virus infection in animal models and humans have yet to establish an association of HMGB1 release with influenza virus infection. To this end, we used the cotton rat model that is permissive to nonadapted strains of influenza A and B viruses, respiratory syncytial virus (RSV), and human rhinoviruses (HRVs). Serum HMGB1 levels were measured by an enzyme-linked immunosorbent assay (ELISA) prior to infection until day 14 or 18 post-infection. Infection with either influenza A or B virus resulted in a robust increase in serum HMGB1 levels that decreased by days 14 to 18. Inoculation with the live attenuated vaccine FluMist resulted in HMGB1 levels that were significantly lower than those with infection with live influenza viruses. RSV and HRVs showed profiles of serum HMGB1 induction that were consistent with their replication and degree of lung pathology in cotton rats. We further showed that therapeutic treatment with Eritoran of cotton rats infected with influenza B virus significantly blunted serum HMGB1 levels and improved lung pathology, without inhibiting virus replication. These findings support the use of drugs that block HMGB1 to combat influenza virus-induced ALI
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the tlr4 antagonist Eritoran protects mice from lethal influenza infection
Nature, 2013Co-Authors: Kari Ann Shirey, W Y C Lai, Alison J Scott, Michael M Lipsky, Pragnesh Mistry, Lioubov M Pletneva, Christopher L Karp, Jaclyn W Mcalees, Theresa L GioanniniAbstract:There is a pressing need to develop alternatives to annual influenza vaccines and antiviral agents licensed for mitigating influenza infection. Previous studies reported that acute lung injury caused by chemical or microbial insults is secondary to the generation of host-derived, oxidized phospholipid that potently stimulates Toll-like receptor 4 (TLR4)-dependent inflammation. Subsequently, we reported that Tlr4(-/-) mice are highly refractory to influenza-induced lethality, and proposed that therapeutic antagonism of TLR4 signalling would protect against influenza-induced acute lung injury. Here we report that therapeutic administration of Eritoran (also known as E5564)-a potent, well-tolerated, synthetic TLR4 antagonist-blocks influenza-induced lethality in mice, as well as lung pathology, clinical symptoms, cytokine and oxidized phospholipid expression, and decreases viral titres. CD14 and TLR2 are also required for Eritoran-mediated protection, and CD14 directly binds Eritoran and inhibits ligand binding to MD2. Thus, Eritoran blockade of TLR signalling represents a novel therapeutic approach for inflammation associated with influenza, and possibly other infections.
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the tlr4 antagonist Eritoran protects mice from lethal influenza infection
Nature, 2013Co-Authors: Kari Ann Shirey, Alison J Scott, Michael M Lipsky, Pragnesh Mistry, Lioubov M Pletneva, Christopher L Karp, Jaclyn W Mcalees, Theresa L Gioannini, Jerrold WeissAbstract:TLR4 stimulation is known to contribute to acute lung injury after administration of inactivated influenza virus; here, the synthetic TLR4 antagonist Eritoran is shown to protect mice from death after infection with a lethal dose of the virus. With the influenza virus continually evolving, and resistance to existing antiviral therapies spreading, there is a pressing need for new anti-influenza therapies. Previous work has shown that TLR4 signalling mediates influenza-induced acute lung injury, cytokine production and systemic effects in mice. Stefanie Vogel and colleagues now report that Eritoran, a synthetic TLR4 antagonist, can protect mice from death when administered up to six days after infection with the influenza virus. Existing antivirals must be administered within three days of infection to be effective. This work suggests that TLR4 antagonists may be effective against influenza and could usefully extend the period during which the infection can be effectively treated. There is a pressing need to develop alternatives to annual influenza vaccines and antiviral agents licensed for mitigating influenza infection. Previous studies reported that acute lung injury caused by chemical or microbial insults is secondary to the generation of host-derived, oxidized phospholipid that potently stimulates Toll-like receptor 4 (TLR4)-dependent inflammation1. Subsequently, we reported that Tlr4−/− mice are highly refractory to influenza-induced lethality2, and proposed that therapeutic antagonism of TLR4 signalling would protect against influenza-induced acute lung injury. Here we report that therapeutic administration of Eritoran (also known as E5564)—a potent, well-tolerated, synthetic TLR4 antagonist3,4—blocks influenza-induced lethality in mice, as well as lung pathology, clinical symptoms, cytokine and oxidized phospholipid expression, and decreases viral titres. CD14 and TLR2 are also required for Eritoran-mediated protection, and CD14 directly binds Eritoran and inhibits ligand binding to MD2. Thus, Eritoran blockade of TLR signalling represents a novel therapeutic approach for inflammation associated with influenza, and possibly other infections.
Christian Alexander - One of the best experts on this subject based on the ideXlab platform.
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three dimensional mapping of differential amino acids of human murine canine and equine tlr4 md 2 receptor complexes conferring endotoxic activation by lipid a antagonism by Eritoran and species dependent activities of lipid iva in the mammalian lps sensor system
Computational and structural biotechnology journal, 2013Co-Authors: Thomas Scior, Jorge Lozanoaponte, Vianihuini Figueroavazquez, Julian A Yunesrojas, Ulrich Zahringer, Christian AlexanderAbstract:A literature review concerning the unexpected species differences of the vertebrate innate immune response to lipid IVA was published in CSBJ prior to the present computational study to address the unpaired activity-sequence correlation of prototypic E. coli -type lipid A and its precursor lipid IVA regarding human, murine, equine and canine species. To this end, their sequences and structures of hitherto known Toll-like receptor 4 (TLR4) and myeloid differentiation factor 2 (MD-2) complexes were aligned and their differential side chain patterns studied. If required due to the lack of the corresponding X-ray crystallographic data, three-dimensional models of TLR4/MD-2/ligand complexes were generated using mono and dimeric crystal structures as templates and in silico docking of the prototypic ligands lipid A, lipid IVA and Eritoran. All differential amino acids were mapped to pinpoint species dependency on an atomic scale, i.e. the possible concert of mechanistically relevant side chains. In its most abstract and general form the three-dimensional (3D-) models devise a triangular interface or "wedge" where molecular interactions between TLR4, MD-2 and ligand itself take place. This study identifies two areas in the wedge related to either agonism or antagonism reflecting why ligands like lipid IVA can possess a species dependent dual activity. Lipid IVA represents an imperfect (underacylated and backbone-flipped), low affinity ligand of mammalian TLR4/MD-2 complexes. Its specific but weak antagonistic activity in the human system is in particular due to the loss of phosphate attraction in the wedge-shaped region conferred by nonhomologous residue changes when compared to crystal and modeled structures of the corresponding murine and equine TLR4/MD-2 complexes. The counter-TLR4/MD-2 unit was also taken into account since agonist-mediated dimerization in a defined m-shaped complex composed of two TLR4/MD-2/agonist subunits triggers intracellular signaling during the innate immune response to bacterial endotoxin exposure.
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reviewing and identifying amino acids of human murine canine and equine tlr4 md 2 receptor complexes conferring endotoxic innate immunity activation by lps lipid a or antagonistic effects by Eritoran in contrast to species dependent modulation by lipid iva
Computational and structural biotechnology journal, 2013Co-Authors: Thomas Scior, Christian Alexander, Ulrich ZaehringerAbstract:There is literature evidence gathered throughout the last two decades reflecting unexpected species differences concerning the immune response to lipid IVa which provides the opportunity to gain more detailed insight by the molecular modeling approach described in this study. Lipid IVa is a tetra-acylated precursor of lipid A in the biosynthesis of lipopolysaccharide (LPS) in Gram-negative bacteria. Lipid A of the prototypic E. coli-type is a hexa-acylated structure that acts as an agonist in all tested mammalian species by innate immunorecognition via the Toll-like receptor 4 (TLR4)/myeloid differentiation factor 2 (MD-2) receptor complex. In contrast, lipid IVa is proinflammatory in mouse cells (agonism) but it remains inactive to human macrophages and even antagonizes the action of potent agonists like E. coli-type lipid A. This particular ambivalent activity profile of lipid IVa has been confirmed in other mammalian species: in equine cells Lipid IVa also acts in a weak agonistic manner, whereas being inactive and antagonizing the lipid A-induced activation of canine TLR4/MD-2. Intriguingly, the respective TLR4 amino acid sequences of the latter species are more identical to the human (67%, 68%) than to the murine (62%, 58%) ortholog. In order to address the unpaired activity-sequence dualism for human, murine, canine and equine species regarding the activity of lipid IVa as compared to LPS and lipid A and, we review the literature and computationally pinpoint the differential biological effects of lipid IVa versus LPS and lipid A to specific amino acid residues. In contrast to lipid IVa the structurally related synthetic compound Eritoran (E5564) acts consistently in an antagonistic manner in these mammalian species and serves as a reference ligand for molecular modeling in this study. The combined evaluation of data sets provided by prior studies and in silico homology mapping of differential residues of TLR4/MD-2 complexes lends detailed insight into the driving forces of the characteristic binding modes of the lipid A domain in LPS and the precursor structure lipid IVa to the receptor complex in individual mammalian species.
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THREE-DIMENSIONAL MAPPING OF DIFFERENTIAL AMINO ACIDS OF HUMAN, MURINE, CANINE AND EQUINE TLR4/MD-2 RECEPTOR COMPLEXES CONFERRING ENDOTOXIC ACTIVATION BY LIPID A, ANTAGONISM BY Eritoran AND SPECIES-DEPENDENT ACTIVITIES OF LIPID IVA IN THE MAMMALIAN LPS SENSOR SYSTEM
Elsevier, 2013Co-Authors: Thomas Scior, Ulrich Zahringer, Jorge Lozano-aponte, Vianihuini Figueroa-vazquez, Julian A. Yunes-rojas, Christian AlexanderAbstract:A literature review concerning the unexpected species differences of the vertebrate innate immune response to lipid IVA was published in CSBJ prior to the present computational study to address the unpaired activity-sequence correlation of prototypic E. coli -type lipid A and its precursor lipid IVA regarding human, murine, equine and canine species. To this end, their sequences and structures of hitherto known Toll-like receptor 4 (TLR4) and myeloid differentiation factor 2 (MD-2) complexes were aligned and their differential side chain patterns studied. If required due to the lack of the corresponding X-ray crystallographic data, three-dimensional models of TLR4/MD-2/ligand complexes were generated using mono and dimeric crystal structures as templates and in silico docking of the prototypic ligands lipid A, lipid IVA and Eritoran. All differential amino acids were mapped to pinpoint species dependency on an atomic scale, i.e. the possible concert of mechanistically relevant side chains. In its most abstract and general form the three-dimensional (3D-) models devise a triangular interface or “wedge” where molecular interactions between TLR4, MD-2 and ligand itself take place. This study identifies two areas in the wedge related to either agonism or antagonism reflecting why ligands like lipid IVA can possess a species dependent dual activity. Lipid IVA represents an imperfect (underacylated and backbone-flipped), low affinity ligand of mammalian TLR4/MD-2 complexes. Its specific but weak antagonistic activity in the human system is in particular due to the loss of phosphate attraction in the wedge-shaped region conferred by nonhomologous residue changes when compared to crystal and modeled structures of the corresponding murine and equine TLR4/MD-2 complexes. The counter-TLR4/MD-2 unit was also taken into account since agonist-mediated dimerization in a defined m-shaped complex composed of two TLR4/MD-2/agonist subunits triggers intracellular signaling during the innate immune response to bacterial endotoxin exposure
Thomas Scior - One of the best experts on this subject based on the ideXlab platform.
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three dimensional mapping of differential amino acids of human murine canine and equine tlr4 md 2 receptor complexes conferring endotoxic activation by lipid a antagonism by Eritoran and species dependent activities of lipid iva in the mammalian lps sensor system
Computational and structural biotechnology journal, 2013Co-Authors: Thomas Scior, Jorge Lozanoaponte, Vianihuini Figueroavazquez, Julian A Yunesrojas, Ulrich Zahringer, Christian AlexanderAbstract:A literature review concerning the unexpected species differences of the vertebrate innate immune response to lipid IVA was published in CSBJ prior to the present computational study to address the unpaired activity-sequence correlation of prototypic E. coli -type lipid A and its precursor lipid IVA regarding human, murine, equine and canine species. To this end, their sequences and structures of hitherto known Toll-like receptor 4 (TLR4) and myeloid differentiation factor 2 (MD-2) complexes were aligned and their differential side chain patterns studied. If required due to the lack of the corresponding X-ray crystallographic data, three-dimensional models of TLR4/MD-2/ligand complexes were generated using mono and dimeric crystal structures as templates and in silico docking of the prototypic ligands lipid A, lipid IVA and Eritoran. All differential amino acids were mapped to pinpoint species dependency on an atomic scale, i.e. the possible concert of mechanistically relevant side chains. In its most abstract and general form the three-dimensional (3D-) models devise a triangular interface or "wedge" where molecular interactions between TLR4, MD-2 and ligand itself take place. This study identifies two areas in the wedge related to either agonism or antagonism reflecting why ligands like lipid IVA can possess a species dependent dual activity. Lipid IVA represents an imperfect (underacylated and backbone-flipped), low affinity ligand of mammalian TLR4/MD-2 complexes. Its specific but weak antagonistic activity in the human system is in particular due to the loss of phosphate attraction in the wedge-shaped region conferred by nonhomologous residue changes when compared to crystal and modeled structures of the corresponding murine and equine TLR4/MD-2 complexes. The counter-TLR4/MD-2 unit was also taken into account since agonist-mediated dimerization in a defined m-shaped complex composed of two TLR4/MD-2/agonist subunits triggers intracellular signaling during the innate immune response to bacterial endotoxin exposure.
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reviewing and identifying amino acids of human murine canine and equine tlr4 md 2 receptor complexes conferring endotoxic innate immunity activation by lps lipid a or antagonistic effects by Eritoran in contrast to species dependent modulation by lipid iva
Computational and structural biotechnology journal, 2013Co-Authors: Thomas Scior, Christian Alexander, Ulrich ZaehringerAbstract:There is literature evidence gathered throughout the last two decades reflecting unexpected species differences concerning the immune response to lipid IVa which provides the opportunity to gain more detailed insight by the molecular modeling approach described in this study. Lipid IVa is a tetra-acylated precursor of lipid A in the biosynthesis of lipopolysaccharide (LPS) in Gram-negative bacteria. Lipid A of the prototypic E. coli-type is a hexa-acylated structure that acts as an agonist in all tested mammalian species by innate immunorecognition via the Toll-like receptor 4 (TLR4)/myeloid differentiation factor 2 (MD-2) receptor complex. In contrast, lipid IVa is proinflammatory in mouse cells (agonism) but it remains inactive to human macrophages and even antagonizes the action of potent agonists like E. coli-type lipid A. This particular ambivalent activity profile of lipid IVa has been confirmed in other mammalian species: in equine cells Lipid IVa also acts in a weak agonistic manner, whereas being inactive and antagonizing the lipid A-induced activation of canine TLR4/MD-2. Intriguingly, the respective TLR4 amino acid sequences of the latter species are more identical to the human (67%, 68%) than to the murine (62%, 58%) ortholog. In order to address the unpaired activity-sequence dualism for human, murine, canine and equine species regarding the activity of lipid IVa as compared to LPS and lipid A and, we review the literature and computationally pinpoint the differential biological effects of lipid IVa versus LPS and lipid A to specific amino acid residues. In contrast to lipid IVa the structurally related synthetic compound Eritoran (E5564) acts consistently in an antagonistic manner in these mammalian species and serves as a reference ligand for molecular modeling in this study. The combined evaluation of data sets provided by prior studies and in silico homology mapping of differential residues of TLR4/MD-2 complexes lends detailed insight into the driving forces of the characteristic binding modes of the lipid A domain in LPS and the precursor structure lipid IVa to the receptor complex in individual mammalian species.
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THREE-DIMENSIONAL MAPPING OF DIFFERENTIAL AMINO ACIDS OF HUMAN, MURINE, CANINE AND EQUINE TLR4/MD-2 RECEPTOR COMPLEXES CONFERRING ENDOTOXIC ACTIVATION BY LIPID A, ANTAGONISM BY Eritoran AND SPECIES-DEPENDENT ACTIVITIES OF LIPID IVA IN THE MAMMALIAN LPS SENSOR SYSTEM
Elsevier, 2013Co-Authors: Thomas Scior, Ulrich Zahringer, Jorge Lozano-aponte, Vianihuini Figueroa-vazquez, Julian A. Yunes-rojas, Christian AlexanderAbstract:A literature review concerning the unexpected species differences of the vertebrate innate immune response to lipid IVA was published in CSBJ prior to the present computational study to address the unpaired activity-sequence correlation of prototypic E. coli -type lipid A and its precursor lipid IVA regarding human, murine, equine and canine species. To this end, their sequences and structures of hitherto known Toll-like receptor 4 (TLR4) and myeloid differentiation factor 2 (MD-2) complexes were aligned and their differential side chain patterns studied. If required due to the lack of the corresponding X-ray crystallographic data, three-dimensional models of TLR4/MD-2/ligand complexes were generated using mono and dimeric crystal structures as templates and in silico docking of the prototypic ligands lipid A, lipid IVA and Eritoran. All differential amino acids were mapped to pinpoint species dependency on an atomic scale, i.e. the possible concert of mechanistically relevant side chains. In its most abstract and general form the three-dimensional (3D-) models devise a triangular interface or “wedge” where molecular interactions between TLR4, MD-2 and ligand itself take place. This study identifies two areas in the wedge related to either agonism or antagonism reflecting why ligands like lipid IVA can possess a species dependent dual activity. Lipid IVA represents an imperfect (underacylated and backbone-flipped), low affinity ligand of mammalian TLR4/MD-2 complexes. Its specific but weak antagonistic activity in the human system is in particular due to the loss of phosphate attraction in the wedge-shaped region conferred by nonhomologous residue changes when compared to crystal and modeled structures of the corresponding murine and equine TLR4/MD-2 complexes. The counter-TLR4/MD-2 unit was also taken into account since agonist-mediated dimerization in a defined m-shaped complex composed of two TLR4/MD-2/agonist subunits triggers intracellular signaling during the innate immune response to bacterial endotoxin exposure
Kishor M Wasan - One of the best experts on this subject based on the ideXlab platform.
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intravenous infusions of Eritoran in healthy Japanese and Caucasian men
2016Co-Authors: Naoki Aikawa, Melvyn Lynn, Daniel P Rossignol, Olena Sivak, Y Okubo, Edgar Schuck, Yasumi Kitahara, T Nakano, Nancy Y Wong, Kishor M WasanAbstract:Eritoran, a synthetic analogue of lipid A, has been shown to bind to TLR4/MD-2 complex and thereby block the interaction of endotoxins with TLR4. We report here the results of a study conducted to assess the single-dose safety and tolerability, as well as the pharmacokinetics and pharmacodynamics, of Eritoran infusion in Japanese and Caucasian healthy adult men. Sixty-four men (aged 20–45 years; body mass index 18–30 kg/m2) were randomized into four groups: 4-mg total dose (six Japanese and six Caucasian men); 12-mg total dose (12 Japanese and 12 Caucasian men); 28-mg total dose (six Japanese and six Caucasian men); and placebo (eight Japanese and eight Caucasian men). Eritoran in single doses up to 28 mg over 4 h was well tolerated, with no apparent ethnic differences noted. Plasma concentrations were slightly higher in Japanese versus Caucasian men; these differences were not significant after adjustment for differences in body mass (clearance: approximately 1.2 ml/h/kg; volume of distribution at steady state: approximately 0.07 l/kg). The ex vivo endotoxin inhibitory activity of Eritoran was similar in Japanese and Caucasian men. The data do not indicate any need for clinical dose adjustment for possible ethnic-based differences in drug distribution or metabolism
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safety pharmacokinetics and pharmacodynamics of four hour intravenous infusions of Eritoran in healthy japanese and caucasian men
Innate Immunity, 2012Co-Authors: Naoki Aikawa, Melvyn Lynn, Daniel P Rossignol, Olena Sivak, Y Okubo, Edgar Schuck, Yasumi Kitahara, T Nakano, Nancy Y Wong, Kishor M WasanAbstract:Eritoran, a synthetic analogue of lipid A, has been shown to bind to TLR4/MD-2 complex and thereby block the interaction of endotoxins with TLR4. We report here the results of a study conducted to ...
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deactivation of the lipopolysaccharide antagonist Eritoran e5564 by high density lipoprotein associated apolipoproteins
Innate Immunity, 2012Co-Authors: Jacklyn G Fleischer, Melvyn Lynn, Dan Rossignol, Gordon A Francis, Teddy Chan, Kishor M WasanAbstract:Lipid A, the active moiety of LPS, exerts its effects through interaction with TLR4, triggering a signalling cascade that results in the release of pro-inflammatory cytokines. Eritoran is a lipid A analogue that competes with LPS for binding to TLR4; however, after intravenous administration, it undergoes a time-dependent deactivation as a consequence of binding to high-density lipoproteins (HDLs). The site of Eritoran association with HDL remains unknown. Therefore the aim of this study was to determine if HDL-associated apolipoproteins A1, A2, serum amyloid A (SAA) and C1, inhibit the ability of Eritoran to block LPS-induced TNF-α release from whole blood. Eritoran activity after LPS stimulation in human whole blood was assessed in the presence of reconstituted HDL (rHDL) containing different apos. In rHDL, the major apolipoproteins in both the healthy and septic state, A1 and SAA, caused a significant reduction in Eritoran antagonistic activity and had a greater effect than minor apolipoproteins A2 and C1. Apolipoproteins associated with HDL are likely to facilitate Eritoran deactivation. Apolipoproteins A1 and SAA should be of particular focus as they are the major apos found on HDL in both the healthy and septic state. Further evaluation of the physical association between apolipoproteins and Eritoran should be explored.
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safety pharmacokinetics and pharmacodynamics of 4 hour intravenous infusion of Eritoran tetrasodium in healthy japanese and caucasian males
Critical Care, 2011Co-Authors: Y Okubo, Melvyn Lynn, Daniel P Rossignol, Olena Sivak, Naoki Aikawa, Yn Wong, Edgar Schuck, Yasumi Kitahara, T Nakano, Kishor M WasanAbstract:Activation of TLR4 signaling by endotoxin is believed to be a primary mediator of sepsis and septic shock, via excessive production of cytokines and proinflammatory mediators [1]. Eritoran tetrasodium (hereafter Eritoran), a synthetic analog of the endotoxin constituent lipid A, binds to the TLR4/MD-2 complex and thereby blocks the interaction of endotoxin with TLR4 [2]. Eritoran is being investigated for the treatment of severe sepsis [3]. We report results of a study conducted to assess the single-dose safety and tolerability, as well as pharmacokinetics and pharmacodynamics, of Eritoran infusion in Japanese and Caucasian healthy adult males.
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influence of plasma cholesterol and triglyceride concentrations and Eritoran e5564 micelle size on its plasma pharmacokinetics and ex vivo activity following single intravenous bolus dose into healthy female rabbits
Pharmaceutical Research, 2008Co-Authors: Kishor M Wasan, Melvyn Lynn, Nancy Wong, Verica Risovic, Olena Sivak, Stephen Lee, Douglas X Mason, Gregory R Chiklis, Jim Mcshane, Daniel P RossignolAbstract:Eritoran (E5564) is a glycophospholipid that acts as a toll-like receptor 4 (TLR4) antagonist that is being tested as a treatment for severe sepsis and septic shock. In the blood, Eritoran binds to plasma lipoproteins altering its pharmacokinetic and pharmacodynamic (PD) effects in vivo. The purpose of this study was to determine the influence of changes in plasma cholesterol and triglyceride concentrations on the plasma pharmacokinetics and ex vivo activity of Eritoran following single intravenous bolus dosing of Eritoran to healthy female rabbits fed either a regular chow diet or a cholesterol-enriched diet. This was done with Eritoran administered as stable micelle formulations of mean hydrodynamic diameters of 8 or 27 nm). Female New Zealand White rabbits were fed a standard diet for 7 days and then randomly assigned either a regular chow diet [regular-diet (n = 9)] or a cholesterol-enriched diet [cholesterol-diet (n = 12)] for an additional 7 days. Following feeding of these diets a single intravenous bolus dose of Eritoran (0.5 mg/kg) formulated into either “small micelles” (8 nm in diameter) or “large micelles” (27 nm in diameter) was administered to regular-fed and cholesterol-fed rabbits. Serial blood samples were obtained prior to Eritoran administration and at the following times post injection: 0.083 (5 min), 1, 2, 4, 8, 10, 24, 48 and 72 h. Plasma was analyzed for Eritoran concentrations using LC/MS/MS. Total plasma cholesterol (TC) and triglyceride (TG) levels were quantified using enzymatic kits. Plasma Eritoran pharmacokinetic (PK) parameters were estimated by non-compartmental analysis using the WinNonlin nonlinear estimation program. To analyze PD activity, whole blood obtained at 0.083 (5 min), 2, 24, 48 and 72 h following Eritoran administration was assessed for ex vivo activity by measuring the ability of 1 and 10 ng/ml LPS to elicit TNF-α release. Total plasma cholesterol and triglyceride levels were significantly higher in cholesterol-fed rabbits compared to the rabbits fed a regular chow diet. Diet had no effect on the estimated plasma PK parameters. However, PD activity of both small and large micelle Eritoran as measured by an ex vivo challenge dose of 1 ng/ml LPS was reduced in blood of cholesterol-fed rabbits compared to normal-fed rabbits. Comparison of PK parameters for small and large micelles indicated that small micelles had increased AUC0–72 h, decreased plasma clearance and increased initial concentration (measured at 5 min post administration) compared to the large micelle formulation. Consistent with this observation, Eritoran formulated into small micelles had significantly greater ex vivo activity than large micelles and was independent of TC and TG concentrations. These findings suggest that plasma pharmacokinetics and activity of Eritoran maybe influenced by Eritoran micelle size and plasma TC and TG concentrations.