The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
George M. Bahr - One of the best experts on this subject based on the ideXlab platform.
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identification of a synthetic Muramyl Peptide derivative with enhanced nod2 stimulatory capacity
Innate Immunity, 2013Co-Authors: Stephen Rubino, George M. Bahr, Didier Blanot, Dana J. Philpott, Joao G Magalhaes, Stephen E. GirardinAbstract:Muramyl Peptides (MPs) represent the building blocks of bacterial peptidoglycan, a critical component of bacterial cell walls. MPs are well characterized for their immunomodulatory properties, and numerous studies have delineated the role of MPs or synthetic MP analogs in host defense, adjuvanticity and inflammation. More recently, Nod1 and Nod2 have been identified as the host sensors for specific MPs, and, in particular, Nod2 was shown to detect Muramyl diPeptide (MDP), a MP found in both Gram-positive and Gram-negative bacterial cell walls. Because mutations in Nod2 are associated with the etiology of Crohn’s disease, there is a need to identify synthetic MP analogs that could potentiate Nod2-dependent immunity. Here, we analyzed the Nod2-activating property of 36 MP analogs that had been tested previously for their adjuvanticity and anti-infectious activity. Using a luciferase-based screen, we demonstrate that addition of a methyl group to the second amino acid of MDP generates a MDP derivative with e...
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Identification of a synthetic Muramyl Peptide derivative with enhanced Nod2 stimulatory capacity.
Innate immunity, 2013Co-Authors: Stephen Rubino, George M. Bahr, Didier Blanot, Dana J. Philpott, Joao G Magalhaes, Stephen E. GirardinAbstract:Muramyl Peptides (MPs) represent the building blocks of bacterial peptidoglycan, a critical component of bacterial cell walls. MPs are well characterized for their immunomodulatory properties, and numerous studies have delineated the role of MPs or synthetic MP analogs in host defense, adjuvanticity and inflammation. More recently, Nod1 and Nod2 have been identified as the host sensors for specific MPs, and, in particular, Nod2 was shown to detect Muramyl diPeptide (MDP), a MP found in both Gram-positive and Gram-negative bacterial cell walls. Because mutations in Nod2 are associated with the etiology of Crohn's disease, there is a need to identify synthetic MP analogs that could potentiate Nod2-dependent immunity. Here, we analyzed the Nod2-activating property of 36 MP analogs that had been tested previously for their adjuvanticity and anti-infectious activity. Using a luciferase-based screen, we demonstrate that addition of a methyl group to the second amino acid of MDP generates a MDP derivative with enhanced Nod2-activating capacity. We further validated these results in murine macrophages, human dendritic cells and in vivo. These results offer a basis for the rational development of synthetic MPs that could be used in the treatment of inflammatory disorders that have been associated with Nod2 dysfunction, such as Crohn's disease.
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Selection of a Muramyl Peptide based on its lack of activation of nuclear factor-κB as a potential adjuvant for AIDS vaccines
Clinical and experimental immunology, 2008Co-Authors: R. Schreck, D. Bevec, P. Dukor, Patrick A. Baeuerle, L. Chedid, George M. BahrAbstract:Activation of the cellular transcription factor nuclear factor-kappa B (NF-kappa B) by cytokines and other immunostimulants has been tightly linked with enhanced replication of human immunodeficiency virus-type 1 (HIV-1) in infected cells. Various immunomodulators are currently being examined in animal and human trials for their suitability as adjuvants in potential vaccines against acquired immunodeficiency syndrome (AIDS). It may prove to be beneficial to select adjuvants that do not induce NF-kappa B activation and particularly if the vaccines are to be aimed at seropositive individuals. We have examined a battery of synthetic immunostimulants of the Muramyl Peptide family for their ability to activate NF-kappa B in human and mouse cell lines. In this report, we demonstrate selective activation of NF-kappa B in different cell lines and by different Muramyl Peptides possessing immunostimulatory activities. The mechanism of such activation is apparently via production of reactive oxygen intermediates (ROI) since pretreatment of cells with antioxidants blocked subsequent activation of NF-kappa B. However, among all the molecules tested only one lipophilic, non-pyrogenic adjuvant active Muramyl Peptide showed a complete lack of NF-kappa B activation in all cell lines tested. This molecule could well become the adjuvant of choice in future AIDS vaccines.
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macrophage stimulation with murabutide an hiv suppressive Muramyl Peptide derivative selectively activates extracellular signal regulated kinases 1 and 2 c ebpβ and stat1 role of cd14 and toll like receptors 2 and 4
European Journal of Immunology, 2001Co-Authors: Vincent Vidal, Carrie J Riendeau, Edith Darcissac, Nathalie Casteran, André Capron, Hardy Kornfeld, George M. BahrAbstract:The smallest unit of bacterial peptidoglycans known to be endowed with biological activities is Muramyl diPeptide (MDP). A clinically acceptable synthetic derivative of MDP, namely murabutide (MB), has been found to present interesting pharmacological properties and to suppress HIV-1 replication in monocyte-derived macrophages (MDM). We have addressed the signaling events activated in MDM following stimulation with either MB or the potent immunostimulant LPS. We also examined whether signaling by Muramyl Peptides involves the use of cell surface receptors, including CD14 and Toll-like receptor 2 (TLR2) or TLR4 that are known to be signal-transducing receptors for other bacterial cell wall components. We demonstrate that, unlike LPS, the safe immunomodulator MB selectively activates extracellular signal-regulated kinases (Erk) 1 / 2, in the absence of detectable Jun N-terminal kinase (JNK) or p38 mitogen-activated kinase activation. Furthermore, STAT1 activation but weakor no activation of STAT3 or STAT5 respectively, could be detected in MB-stimulated MDM. Using MonoMac6 cells, we observed high C / EBPβ and AP-1 but weaker and transient NF-κB activation by MB.Moreover, the truncated form of C / EBPβ, known to repress HIV-1 transcription, was detected in extracts from MB-treated THP-1 cells. Surprisingly, neither MB nor MDP were able to transduce signals via CD14 and TLR2 or 4. These findings present major differences in the early cell activation process between LPS and Muramyl Peptides, and strongly argue for the implication of co-receptors other than TLR2 and TLR4 in mediating the signaling events induced by defined subunits of bacterial peptidoglycans.
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Macrophage stimulation with Murabutide, an HIV-suppressive Muramyl Peptide derivative, selectively activates extracellular signal-regulated kinases 1 and 2, C / EBPβ and STAT1: role of CD14 and Toll-like receptors 2 and 4
European journal of immunology, 2001Co-Authors: Vincent Vidal, Carrie J Riendeau, Edith Darcissac, Nathalie Casteran, André Capron, Hardy Kornfeld, George M. BahrAbstract:The smallest unit of bacterial peptidoglycans known to be endowed with biological activities is Muramyl diPeptide (MDP). A clinically acceptable synthetic derivative of MDP, namely murabutide (MB), has been found to present interesting pharmacological properties and to suppress HIV-1 replication in monocyte-derived macrophages (MDM). We have addressed the signaling events activated in MDM following stimulation with either MB or the potent immunostimulant LPS. We also examined whether signaling by Muramyl Peptides involves the use of cell surface receptors, including CD14 and Toll-like receptor 2 (TLR2) or TLR4 that are known to be signal-transducing receptors for other bacterial cell wall components. We demonstrate that, unlike LPS, the safe immunomodulator MB selectively activates extracellular signal-regulated kinases (Erk) 1/2, in the absence of detectable Jun N-terminal kinase (JNK) or p38 mitogen-activated kinase activation. Furthermore, STAT1 activation but weak or no activation of STAT3 or STAT5 respectively, could be detected in MB-stimulated MDM. Using MonoMac6 cells, we observed high C/EBPbeta and AP-1 but weaker and transient NF-kappaB activation by MB.Moreover, the truncated form of C/EBPbeta, known to repress HIV-1 transcription, was detected in extracts from MB-treated THP-1 cells. Surprisingly, neither MB nor MDP were able to transduce signals via CD14 and TLR2 or 4. These findings present major differences in the early cell activation process between LPS and Muramyl Peptides, and strongly argue for the implication of co-receptors other than TLR2 and TLR4 in mediating the signaling events induced by defined subunits of bacterial peptidoglycans.
Stephen E. Girardin - One of the best experts on this subject based on the ideXlab platform.
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identification of a synthetic Muramyl Peptide derivative with enhanced nod2 stimulatory capacity
Innate Immunity, 2013Co-Authors: Stephen Rubino, George M. Bahr, Didier Blanot, Dana J. Philpott, Joao G Magalhaes, Stephen E. GirardinAbstract:Muramyl Peptides (MPs) represent the building blocks of bacterial peptidoglycan, a critical component of bacterial cell walls. MPs are well characterized for their immunomodulatory properties, and numerous studies have delineated the role of MPs or synthetic MP analogs in host defense, adjuvanticity and inflammation. More recently, Nod1 and Nod2 have been identified as the host sensors for specific MPs, and, in particular, Nod2 was shown to detect Muramyl diPeptide (MDP), a MP found in both Gram-positive and Gram-negative bacterial cell walls. Because mutations in Nod2 are associated with the etiology of Crohn’s disease, there is a need to identify synthetic MP analogs that could potentiate Nod2-dependent immunity. Here, we analyzed the Nod2-activating property of 36 MP analogs that had been tested previously for their adjuvanticity and anti-infectious activity. Using a luciferase-based screen, we demonstrate that addition of a methyl group to the second amino acid of MDP generates a MDP derivative with e...
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Identification of a synthetic Muramyl Peptide derivative with enhanced Nod2 stimulatory capacity.
Innate immunity, 2013Co-Authors: Stephen Rubino, George M. Bahr, Didier Blanot, Dana J. Philpott, Joao G Magalhaes, Stephen E. GirardinAbstract:Muramyl Peptides (MPs) represent the building blocks of bacterial peptidoglycan, a critical component of bacterial cell walls. MPs are well characterized for their immunomodulatory properties, and numerous studies have delineated the role of MPs or synthetic MP analogs in host defense, adjuvanticity and inflammation. More recently, Nod1 and Nod2 have been identified as the host sensors for specific MPs, and, in particular, Nod2 was shown to detect Muramyl diPeptide (MDP), a MP found in both Gram-positive and Gram-negative bacterial cell walls. Because mutations in Nod2 are associated with the etiology of Crohn's disease, there is a need to identify synthetic MP analogs that could potentiate Nod2-dependent immunity. Here, we analyzed the Nod2-activating property of 36 MP analogs that had been tested previously for their adjuvanticity and anti-infectious activity. Using a luciferase-based screen, we demonstrate that addition of a methyl group to the second amino acid of MDP generates a MDP derivative with enhanced Nod2-activating capacity. We further validated these results in murine macrophages, human dendritic cells and in vivo. These results offer a basis for the rational development of synthetic MPs that could be used in the treatment of inflammatory disorders that have been associated with Nod2 dysfunction, such as Crohn's disease.
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Synthesis and Biological Evaluation of Biotinyl Hydrazone Derivatives of Muramyl Peptides
Chemical biology & drug design, 2011Co-Authors: Didier Blanot, Jooeun Lee, Stephen E. GirardinAbstract:Muramyl Peptides derived from bacterial peptidoglycan have long been known for their ability to trigger host innate immune responses, including inflammation and antimicrobial defense. Muramyl Peptides have also been widely studied for their role as immune adjuvants. In mammals, the nucleotide-binding oligomerization domain (Nod) proteins Nod1 and Nod2 detect distinct Muramyl Peptide structures and mediate their biological activity. Because of the poor immunogenicity of these small peptidoglycan derivatives, research in this field is currently limited by the lack of reagents to track or immobilize specific Muramyl Peptides. We present here the generation and initial biological characterization of synthetic Muramyl Peptides covalently coupled to dansyl or biotinyl derivatives and demonstrate that biotinyl coupling on the Muramyl moiety results in derivatives that can be tracked by immunofluorescence and maintain full biological activity, as observed by their capacity to trigger Nod signaling. Moreover, using digitonin-mediated permeabilization techniques on live cells, we also demonstrate that biotinylated Muramyl Peptides efficiently reach the host cytosol, where they activate Nod signaling. Therefore, these derivatives represent useful probes to study the cell biology and the biochemistry of host responses to Muramyl Peptides.
William E. Goldman - One of the best experts on this subject based on the ideXlab platform.
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Synergistic epithelial responses to endotoxin and a naturally occurring Muramyl Peptide.
Infection and immunity, 2000Co-Authors: Tod A. Flak, L N Heiss, Jacquelyn T. Engle, William E. GoldmanAbstract:We have investigated the synergistic interactions of a naturally occurring peptidoglycan fragment (Muramyl Peptide) and bacterial endotoxin in the induction of inflammatory processes within respiratory epithelial cells, at the levels of both signal transduction events and ultimate cellular metabolic effects. The source of the Muramyl Peptide is Bordetella pertussis, the causative agent of the respiratory disease pertussis. During log-phase growth, B. pertussis releases the Muramyl Peptide tracheal cytotoxin (TCT), which has the structure N - acetylglucosaminyl - 1,6 - anhydro - N - acetylMuramyl - (l) - alanyl - γ - (d) - glutamyl - meso - diaminopimelyl - (d) - alanine, equivalent to a monomeric subunit of gram-negative bacterial peptidoglycan. When applied to hamster trachea epithelial (HTE) cells, TCT and endotoxin were found to be highly synergistic in the induction of interleukin-1α (IL-1α), type II (inducible) nitric oxide synthase (iNOS), nitric oxide production, and inhibition of DNA synthesis. Neither molecule alone significantly triggered these responses. The serine/threonine protein kinase inhibitor H7 blocked induction of both IL-1α and iNOS. More selective inhibitors of protein kinase C, cyclic AMP-dependent protein kinase, and cyclic GMP-dependent protein kinase were not capable of blocking the effects of TCT and endotoxin, suggesting that the H7-inhibited component in this pathway is not among the commonly described kinase targets of H7. Treatment of HTE cells with exogenous IL-1 reproduced the induction of iNOS and DNA synthesis inhibition caused by TCT and endotoxin. H7 was not capable of interfering with effects caused by exogenous IL-1, implying that the H7-sensitive step in the pathway is upstream of IL-1 protein production. Similar assays with the phorbol ester phorbol myristate acetate indicate that it could effectively synergize with endotoxin but not with TCT, suggesting that TCT and endotoxin induce different signal transduction events that combine synergistically. The synergy observed with TCT and endotoxin in epithelial cells is significantly different from their interaction with other cell types, revealing a unique inflammatory response by epithelial cells to these natural bacterial products.
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Muramyl Peptide probes derived from tracheal cytotoxin of Bordetella pertussis.
Analytical biochemistry, 1998Co-Authors: Tod A. Flak, William E. GoldmanAbstract:Abstract A novel semisynthetic scheme was developed to couple amine-reactive labeling reagents to the Muramyl Peptide tracheal cytotoxin (TCT) without affecting a critical amine group. Tracheal cytotoxin,N-acetylglucosaminyl-1,6-anhydro-N-acetylMuramyl-Ala-γ-Glu-A2pmAla (A2pm, diaminopimelic acid), is released byBordetella pertussis,the etiologic agent of whooping cough. This glycoPeptide reproduces the specific ciliated cell damage observed in the respiratory tract duringB. pertussisinfection. To examine binding of TCT to target respiratory cells, we have produced labeled TCT analogs. Structure–function studies have shown that the primary amine of the A2pm side chain is essential for TCT toxicity in respiratory tissue. The methodology described here allows coupling of amine-reactive reagents to TCT without affecting this essential amine. The terminalN-acetylglucosamine ring is opened by oxidation with periodic acid, a dihydrazide linker is coupled to the oxidized ring, and pH control is used to selectively derivatize the free hydrazide with anN-hydroxysuccinimide ester, while the A2pm side-chain amine remains free. Using this method, we have coupled the Bolton–Hunter reagent to TCT, producing a biologically active125I-labeled TCT analog.
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Tracheal cytotoxin structural requirements for respiratory epithelial damage in pertussis
Molecular microbiology, 1995Co-Authors: Kathryn E. Luker, Andrew N. Tyler, Garland R. Marshall, William E. GoldmanAbstract:Summary The respiratory epithelial pathology of pertussis (whooping cough) can be reproduced by tracheal cyto-toxin (TCT), a disaccharide-tetraPeptide released by Bordetella pertussis. TCT is a Muramyl Peptide, a class of peptidoglycan-derived compounds which have many biological activities including adjuvanticity, somnogenicity, pyrogenicity, and cytotoxicity. The structural requirements for Muramyl Peptides to produce some of these biological effects have been partially characterized. Using in vitro assays with respiratory epithelial cells and tissue, we have previously determined that the disaccharide moiety of TCT is not involved in toxicity and that the side-chain functional groups of diaminopimelic acid (A2pm) are crucial for toxicity. In this study, we determine the importance of every amino acid, functional group and chiral centre in the Peptide portion of TCT. Although lactyl tetraPeptides are the most toxic of the TCT fragments, producing dose-response curves identical to TCT, the smallest analogues of TCT which are active in our assay are of the form X-γ-(d)-Glu-meso-A2pm, where X may be an amino acid or a blocking group. Within this active substructure, main-chain chirality and all functional groups are essential for toxicity. This definition of the core region of TCT indicates that the TCT interaction site is unlike almost all other Muramyl Peptide interaction sites for which structure-activity data are available.
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Interleukin-1 is linked to the respiratory epithelial cytopathology of pertussis.
Infection and immunity, 1993Co-Authors: L N Heiss, Stephen A. Moser, Emil R. Unanue, William E. GoldmanAbstract:Bordetella pertussis, the causative agent of whooping cough, releases a Muramyl Peptide known as tracheal cytotoxin (TCT) that is responsible for destruction of ciliated epithelial cells lining the large airways. In vitro, TCT has been shown to cause this specific pathology in human or hamster respiratory epithelium and to inhibit the proliferation of cultured hamster trachea epithelial cells. The diverse biological actions of Muramyl Peptides, including adjuvanticity, somnogenicity, and pyrogenicity, have been correlated with the production and release of the inflammatory mediator interleukin-1 (IL-1). Consistent with its ability to reproduce other Muramyl Peptide actions, recombinant IL-1 caused TCT-like damage to the respiratory epithelium. In the nanogram-per-milliliter range, exogenous IL-1 inhibited DNA synthesis in hamster trachea epithelial cells and reproduced the pathology of TCT in hamster tracheal organ culture. Tumor necrosis factor alpha and IL-6, cytokines also associated with inflammation, were unable to reproduce TCT cytopathology. Furthermore, exposure of respiratory epithelial cells to TCT stimulated production of cell-associated IL-1 alpha, which could be detected within 2 h of TCT treatment. In contrast, there was no evidence of TCT-triggered release of IL-1. Previous studies have suggested that intracellular IL-1 alpha, as well as exogenous IL-1 alpha and IL-1 beta, can inhibit cell proliferation. Our results therefore implicate IL-1 alpha, produced by epithelial cells in response to TCT, as a potential intracellular mediator of the primary respiratory cytopathology of pertussis.
Didier Blanot - One of the best experts on this subject based on the ideXlab platform.
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identification of a synthetic Muramyl Peptide derivative with enhanced nod2 stimulatory capacity
Innate Immunity, 2013Co-Authors: Stephen Rubino, George M. Bahr, Didier Blanot, Dana J. Philpott, Joao G Magalhaes, Stephen E. GirardinAbstract:Muramyl Peptides (MPs) represent the building blocks of bacterial peptidoglycan, a critical component of bacterial cell walls. MPs are well characterized for their immunomodulatory properties, and numerous studies have delineated the role of MPs or synthetic MP analogs in host defense, adjuvanticity and inflammation. More recently, Nod1 and Nod2 have been identified as the host sensors for specific MPs, and, in particular, Nod2 was shown to detect Muramyl diPeptide (MDP), a MP found in both Gram-positive and Gram-negative bacterial cell walls. Because mutations in Nod2 are associated with the etiology of Crohn’s disease, there is a need to identify synthetic MP analogs that could potentiate Nod2-dependent immunity. Here, we analyzed the Nod2-activating property of 36 MP analogs that had been tested previously for their adjuvanticity and anti-infectious activity. Using a luciferase-based screen, we demonstrate that addition of a methyl group to the second amino acid of MDP generates a MDP derivative with e...
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Identification of a synthetic Muramyl Peptide derivative with enhanced Nod2 stimulatory capacity.
Innate immunity, 2013Co-Authors: Stephen Rubino, George M. Bahr, Didier Blanot, Dana J. Philpott, Joao G Magalhaes, Stephen E. GirardinAbstract:Muramyl Peptides (MPs) represent the building blocks of bacterial peptidoglycan, a critical component of bacterial cell walls. MPs are well characterized for their immunomodulatory properties, and numerous studies have delineated the role of MPs or synthetic MP analogs in host defense, adjuvanticity and inflammation. More recently, Nod1 and Nod2 have been identified as the host sensors for specific MPs, and, in particular, Nod2 was shown to detect Muramyl diPeptide (MDP), a MP found in both Gram-positive and Gram-negative bacterial cell walls. Because mutations in Nod2 are associated with the etiology of Crohn's disease, there is a need to identify synthetic MP analogs that could potentiate Nod2-dependent immunity. Here, we analyzed the Nod2-activating property of 36 MP analogs that had been tested previously for their adjuvanticity and anti-infectious activity. Using a luciferase-based screen, we demonstrate that addition of a methyl group to the second amino acid of MDP generates a MDP derivative with enhanced Nod2-activating capacity. We further validated these results in murine macrophages, human dendritic cells and in vivo. These results offer a basis for the rational development of synthetic MPs that could be used in the treatment of inflammatory disorders that have been associated with Nod2 dysfunction, such as Crohn's disease.
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Synthesis and Biological Evaluation of Biotinyl Hydrazone Derivatives of Muramyl Peptides
Chemical biology & drug design, 2011Co-Authors: Didier Blanot, Jooeun Lee, Stephen E. GirardinAbstract:Muramyl Peptides derived from bacterial peptidoglycan have long been known for their ability to trigger host innate immune responses, including inflammation and antimicrobial defense. Muramyl Peptides have also been widely studied for their role as immune adjuvants. In mammals, the nucleotide-binding oligomerization domain (Nod) proteins Nod1 and Nod2 detect distinct Muramyl Peptide structures and mediate their biological activity. Because of the poor immunogenicity of these small peptidoglycan derivatives, research in this field is currently limited by the lack of reagents to track or immobilize specific Muramyl Peptides. We present here the generation and initial biological characterization of synthetic Muramyl Peptides covalently coupled to dansyl or biotinyl derivatives and demonstrate that biotinyl coupling on the Muramyl moiety results in derivatives that can be tracked by immunofluorescence and maintain full biological activity, as observed by their capacity to trigger Nod signaling. Moreover, using digitonin-mediated permeabilization techniques on live cells, we also demonstrate that biotinylated Muramyl Peptides efficiently reach the host cytosol, where they activate Nod signaling. Therefore, these derivatives represent useful probes to study the cell biology and the biochemistry of host responses to Muramyl Peptides.
Edith Darcissac - One of the best experts on this subject based on the ideXlab platform.
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macrophage stimulation with murabutide an hiv suppressive Muramyl Peptide derivative selectively activates extracellular signal regulated kinases 1 and 2 c ebpβ and stat1 role of cd14 and toll like receptors 2 and 4
European Journal of Immunology, 2001Co-Authors: Vincent Vidal, Carrie J Riendeau, Edith Darcissac, Nathalie Casteran, André Capron, Hardy Kornfeld, George M. BahrAbstract:The smallest unit of bacterial peptidoglycans known to be endowed with biological activities is Muramyl diPeptide (MDP). A clinically acceptable synthetic derivative of MDP, namely murabutide (MB), has been found to present interesting pharmacological properties and to suppress HIV-1 replication in monocyte-derived macrophages (MDM). We have addressed the signaling events activated in MDM following stimulation with either MB or the potent immunostimulant LPS. We also examined whether signaling by Muramyl Peptides involves the use of cell surface receptors, including CD14 and Toll-like receptor 2 (TLR2) or TLR4 that are known to be signal-transducing receptors for other bacterial cell wall components. We demonstrate that, unlike LPS, the safe immunomodulator MB selectively activates extracellular signal-regulated kinases (Erk) 1 / 2, in the absence of detectable Jun N-terminal kinase (JNK) or p38 mitogen-activated kinase activation. Furthermore, STAT1 activation but weakor no activation of STAT3 or STAT5 respectively, could be detected in MB-stimulated MDM. Using MonoMac6 cells, we observed high C / EBPβ and AP-1 but weaker and transient NF-κB activation by MB.Moreover, the truncated form of C / EBPβ, known to repress HIV-1 transcription, was detected in extracts from MB-treated THP-1 cells. Surprisingly, neither MB nor MDP were able to transduce signals via CD14 and TLR2 or 4. These findings present major differences in the early cell activation process between LPS and Muramyl Peptides, and strongly argue for the implication of co-receptors other than TLR2 and TLR4 in mediating the signaling events induced by defined subunits of bacterial peptidoglycans.
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Macrophage stimulation with Murabutide, an HIV-suppressive Muramyl Peptide derivative, selectively activates extracellular signal-regulated kinases 1 and 2, C / EBPβ and STAT1: role of CD14 and Toll-like receptors 2 and 4
European journal of immunology, 2001Co-Authors: Vincent Vidal, Carrie J Riendeau, Edith Darcissac, Nathalie Casteran, André Capron, Hardy Kornfeld, George M. BahrAbstract:The smallest unit of bacterial peptidoglycans known to be endowed with biological activities is Muramyl diPeptide (MDP). A clinically acceptable synthetic derivative of MDP, namely murabutide (MB), has been found to present interesting pharmacological properties and to suppress HIV-1 replication in monocyte-derived macrophages (MDM). We have addressed the signaling events activated in MDM following stimulation with either MB or the potent immunostimulant LPS. We also examined whether signaling by Muramyl Peptides involves the use of cell surface receptors, including CD14 and Toll-like receptor 2 (TLR2) or TLR4 that are known to be signal-transducing receptors for other bacterial cell wall components. We demonstrate that, unlike LPS, the safe immunomodulator MB selectively activates extracellular signal-regulated kinases (Erk) 1/2, in the absence of detectable Jun N-terminal kinase (JNK) or p38 mitogen-activated kinase activation. Furthermore, STAT1 activation but weak or no activation of STAT3 or STAT5 respectively, could be detected in MB-stimulated MDM. Using MonoMac6 cells, we observed high C/EBPbeta and AP-1 but weaker and transient NF-kappaB activation by MB.Moreover, the truncated form of C/EBPbeta, known to repress HIV-1 transcription, was detected in extracts from MB-treated THP-1 cells. Surprisingly, neither MB nor MDP were able to transduce signals via CD14 and TLR2 or 4. These findings present major differences in the early cell activation process between LPS and Muramyl Peptides, and strongly argue for the implication of co-receptors other than TLR2 and TLR4 in mediating the signaling events induced by defined subunits of bacterial peptidoglycans.
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selective potentiation of cytokine expression in human whole blood by murabutide a Muramyl diPeptide analogue
Cytokine, 1996Co-Authors: Edith Darcissac, George M. Bahr, Gilles Riveau, P Pouillart, Monique ParantAbstract:Abstract Murabutide is a synthetic Muramyl Peptide which is in clinical stage of development. Its effect on cytokine production was analysed in human whole blood to reproduce the natural environment. Induced gene transcription within 2 h was associated with the release of cytokines such as tumour necrosis factor (TNF), interleukin-1 beta (IL–1β), IL–6, IL–8, and also the anti-inflammatory mediator IL–1ra. This synthesis was not associated with the release of IL–4, IL–12, interferon gamma (IFN–γ), the three colony-stimulating factors (CSFs) or the soluble TNF receptors. The same series of cytokines were assayed to determine the effect of some recombinant cytokines in association with murabutide. Thus, in the presence of IL–2, IL–6, IL–3 or granulocyte-macrophage colony-stimulating factor (GM–CSF), the level of cytokines induced by murabutide was enhanced with no change in the other cytokines profile. IL–3 and GM–CSF were more potent in increasing the murabutide-induced response, eliciting synergistic effects on IL–8 and IL–1Ra production, at both the mRNA accumulation and the protein release. Although neither IL–12 nor IFN–γ were produced in cells stimulated with murabutide alone, some mRNA expression was found with combined treatments. The results indicate that association of murabutide with a cytokine could exert synergistic effects, thus reducing effective doses of the recombinant protein, increasing the release of anti-inflammatory mediators, and triggering efficient cellular immunity.
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Immunopharmacological activities and clinical development of Muramyl Peptides with particular emphasis on murabutide.
International journal of immunopharmacology, 1995Co-Authors: George M. Bahr, Edith Darcissac, P. Dukor, Dorian Bevec, Louis ChedidAbstract:Certain immunopharmacological activities of Muramyl Peptides have been associated with inflammatory and undesirable side-effects typically observed following the administration of the prototype molecule Muramyl diPeptide. This activity is now demonstrated not to be linked to a direct activation of inflammatory processes in endothelial cells. Neither MDP nor other structural derivatives were able to induce inflammatory cytokines release or E-selectin gene expression in cultured human umbilical vein endothelial cells. However, oral administration of Muramyl Peptides has been reported to induce certain biological effects, including the downregulation of anamnestic, antigen-specific IgE responses, which are not observed following parenteral administration. We elaborate on these findings and extend them to show the efficacy of a new Muramyl Peptide in suppressing polyclonally induced serum IgE levels in anti-IgD-treated mice. The comparative effects of Muramyl Peptides, selected for clinical development, on the induction of cytokines in human whole blood are then presented at the level of mRNA accumulation and protein secretion. Moreover, the cytokine profile induced in vitro and in vivo by the combination of the safe immunostimulant, Murabutide, with interferon-α is examined. This combination reveals a selective and beneficial synergistic activity and induces anti-inflammatory cytokines in the absence of synergistic toxicity. The potential and the implications for the use of a therapeutic combination of an immunostimulant with a cytokine are discussed.
