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Joseph L Witztum - One of the best experts on this subject based on the ideXlab platform.
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minimally modified ldl binds to cd14 induces macrophage spreading via tlr4 md 2 and inhibits phagocytosis of apoptotic cells
Journal of Biological Chemistry, 2003Co-Authors: Yury I Miller, Suganya Viriyakosol, Christoph J Binder, James R Feramisco, Theo N Kirkland, Joseph L WitztumAbstract:Abstract Minimally modified low density lipoprotein (mmLDL) is a pro-inflammatory and pro-atherogenic lipoprotein that, unlike profoundly oxidized LDL (OxLDL), is not recognized by scavenger Receptors and thus does not have enhanced uptake by macrophages. However, here we demonstrate that mmLDL (as well as OxLDL) induces actin polymerization and spreading of macrophages, which results in such pro-atherogenic consequences as inhibition of phagocytosis of apoptotic cells but enhancement of OxLDL uptake. We also demonstrate for the first time that the Lipopolysaccharide Receptor, CD14, and toll-like Receptor-4/MD-2 are involved in these mmLDL effects. Macrophages of the J774 cell line exhibited higher mmLDL binding and F-actin response than its CD14-deficient mutant, LR-9 cells. Similarly, Chinese hamster ovary cells transfected with human CD14 specifically bound mmLDL and responded with higher F-actin compared with control cells. Macrophages from C3H/HeJ mice, which have a point mutation in the Tlr4 gene, responded with lower F-actin to mmLDL and did not spread as well as macrophages from control animals. A significantly higher F-actin response was also observed in Chinese hamster ovary cells transfected with human toll-like Receptor-4/MD-2 but not with TLR4 alone or TLR2. Thus, in addition to inhibition of phagocytosis, the recognition of mmLDL by macrophage Lipopolysaccharide Receptors results in convergence of cellular immune responses to products of microorganisms and to oxidation-specific self-antigens, which could both influence macrophage function and atherogenesis.
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Minimally modified LDL binds to CD14, induces macrophage spreading via TLR4/MD-2, and inhibits phagocytosis of apoptotic cells.
The Journal of biological chemistry, 2002Co-Authors: Yury I Miller, Suganya Viriyakosol, Christoph J Binder, James R Feramisco, Theo N Kirkland, Joseph L WitztumAbstract:Minimally modified low density lipoprotein (mmLDL) is a pro-inflammatory and pro-atherogenic lipoprotein that, unlike profoundly oxidized LDL (OxLDL), is not recognized by scavenger Receptors and thus does not have enhanced uptake by macrophages. However, here we demonstrate that mmLDL (as well as OxLDL) induces actin polymerization and spreading of macrophages, which results in such pro-atherogenic consequences as inhibition of phagocytosis of apoptotic cells but enhancement of OxLDL uptake. We also demonstrate for the first time that the Lipopolysaccharide Receptor, CD14, and toll-like Receptor-4/MD-2 are involved in these mmLDL effects. Macrophages of the J774 cell line exhibited higher mmLDL binding and F-actin response than its CD14-deficient mutant, LR-9 cells. Similarly, Chinese hamster ovary cells transfected with human CD14 specifically bound mmLDL and responded with higher F-actin compared with control cells. Macrophages from C3H/HeJ mice, which have a point mutation in the Tlr4 gene, responded with lower F-actin to mmLDL and did not spread as well as macrophages from control animals. A significantly higher F-actin response was also observed in Chinese hamster ovary cells transfected with human toll-like Receptor-4/MD-2 but not with TLR4 alone or TLR2. Thus, in addition to inhibition of phagocytosis, the recognition of mmLDL by macrophage Lipopolysaccharide Receptors results in convergence of cellular immune responses to products of microorganisms and to oxidation-specific self-antigens, which could both influence macrophage function and atherogenesis.
Richard Chaby - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and in vitro activities of a spacer-containing glycophospholipid ligand of a Lipopolysaccharide Receptor involved in endotoxin tolerance.
Bioorganic & medicinal chemistry, 1998Co-Authors: Daniel Charon, Michelle Mondange, Jean-françois Pons, Karine Le Blay, Richard ChabyAbstract:A glycophospholipid consisting in a derivative of N,N′-acylated and bisphosphorylated 2,3-dideoxy-2,3-diamino-d-glucose, bearing a 6-aminocaproyl side chain as spacer arm at carbon 6 (PPDm2-B), has been synthesized and its effect on murine macrophages evaluated. The synthesis started from 2,3-diamino-d-glucose, which was best obtained from glucosamine essentially by known procedures, since attempts to use another known precursor (3-nitro-glycoside) led to unexpected results. Selective N-acylation was performed with the hydroxysuccinimide ester of (d)-3-benzyloxymyritic acid followed by esterification of the sole primary hydroxyl function by 6-azidocaproylchloride and phosphorylation of the resulting 1,4-diol by treatment with tetrabenzyl pyrophosphate. Hydrogenation on a Pd on carbon catalyst permitted the isolation of 6-(6-aminohexanoyl)-2,3-dideoxy-2,3-di-[(R)-3-hydroxy-tetradecanamido]-α-d-glucopyranose 1,4-diphosphate (PPDm2-B). In mouse macrophages, PPDm2-B enhanced the Lipopolysaccharide (LPS)-dependent secretion of tumor necrosis factor alpha (TNF-α), and inhibited the LPS-induced desensitization of these cells. The data suggest that PPDm2-B interacts in a serum-independent way with an LPS Receptor different from CD14, and involved in endotoxin tolerance. Binding studies of a fluorescent derivative of PPDm2-B indicated that the expression of this unknown Receptor is down-regulated during in vitro culture of the cells. Owing to its spacer arm, PPDm2-B could thus be a promising tool for future studies of this Receptor.
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Lipopolysaccharide and tumor necrosis factor-alpha induce Lipopolysaccharide Receptor expression on bone marrow cells by different mechanisms.
Journal of immunology (Baltimore Md. : 1950), 1993Co-Authors: Richard Chaby, Thierry Pedron, P L Stütz, R GirardAbstract:Two cell types, monocytes/macrophages and neutrophilic granulocytes, play a prominent role in the pathogenic effects of endotoxins during Gram-negative infections. We previously established that nanomolar concentrations of LPS induce the expression of new specific LPS-binding sites (LpsR) in bone marrow granulocytes of LPS-responsive mice. To examine this induction process further, we asked whether it, like other LPS activities, can be mediated by TNF-alpha. We report that exogenous rTNF-alpha can induce LpsR expression in bone marrow cells (BMC) from both LPS-responsive (C3H/HeOU) and LPS-hyporesponsive (C3H/HeJ) mice. In BMC, LPS elicited a down-regulation of the TNF-alpha Receptors (TNF-R) without direct binding to TNF-R. On the other hand, taxol, a microtubule stabilizer that has shown LPS mimetic activity in macrophages, was unable to elicit LpsR expression or induce TNF-R down-regulation in BMC. Thus, unlike the LPS-signaling Receptor of macrophages, that of BMC is apparently not functionally associated with microtubules. The LPS-induced expression of LpsR was inhibited only partially with an anti-TNF-alpha serum, and with dexamethasone, suggesting that an autocrine activity of endogenous TNF-alpha cannot alone account for the LPS effect. Comparative analyses also indicated that dexamethasone inhibited the LPS-induced increase of LpsR, but enhanced the number of TNF-induced LpsR+ BMC. Furthermore, the synthetic lipid PPDm2 (a 1,4-bisphosphorylated and N,N-diacylated derivative of 2,3-diamino-2,3-dideoxy-D-glucose) inhibited LPS-induced, but not TNF-induced, expression of LpsR. These data show that in BMC, LPS and TNF-alpha induce LpsR expression by different mechanisms.
Denis Wakefield - One of the best experts on this subject based on the ideXlab platform.
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Iris pigment epithelial cells express a functional Lipopolysaccharide Receptor complex.
Investigative ophthalmology & visual science, 2009Co-Authors: Jeanie J. Y. Chui, John H. Chang, Peter Mccluskey, Nick Di Girolamo, Denis WakefieldAbstract:PURPOSE Ocular pigment epithelial cells are hypothesized to play a role in the pathogenesis of acute anterior uveitis (AAU), where LPS activation of Toll-like Receptors (TLRs) may serve as a trigger. In this study, the expression of LPS Receptors in iris pigment epithelium (IPE) was determined. METHODS RT-PCR, flow cytometry, Western blot, and immunohistochemistry were used to investigate the expression of the LPS Receptor complex (TLR4, MD-2, and CD14) in primary human IPE. Cytokine secretion by LPS-treated IPE was measured by multiplex bead array and ELISA. The role of CD14 in modulating the LPS response was investigated by addition of soluble CD14 and by antibody neutralization studies. In vivo expression of CD14 was examined by immunohistochemistry and Western blot analysis. RESULTS IPE expressed TLR4, MD-2, and CD14 in vitro and secreted a panel of proinflammatory cytokines (IL-6, CXCL8, CXCL10, CCL2, CCL4, and CCL5) when stimulated with LPS. CXCL8 secretion by LPS-treated IPE was dependent on CD14 and TLR4. CD14 was detected in CD68+ cells in the iris by immunohistochemistry and in normal aqueous by Western blot analysis. CONCLUSIONS IPE cells express a functional LPS Receptor complex and are capable of promoting ocular inflammation through secretion of an array of proinflammatory mediators. CD14 was identified as a key molecule that modulated the LPS response in IPE.
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expression of toll like Receptor 4 and its associated Lipopolysaccharide Receptor complex by resident antigen presenting cells in the human uvea
Investigative Ophthalmology & Visual Science, 2004Co-Authors: John H. Chang, Peter Mccluskey, Denis WakefieldAbstract:PURPOSE. To investigate the in vivo expression of toll-like Receptor 4 (TLR4) and its associated Lipopolysaccharide (LPS) Receptor complex in the human eye. METHODS. Normal human ocular tissues were evaluated for in vivo TLR4, MD-2, and CD14 mRNA and protein expression by RT-PCR and immunohistochemistry, respectively. The distribution patterns and phenotypes of the cells expressing these proteins were further characterized by confocal microscopy and double-label immunofluorescence studies. RESULTS. Normal human uvea, retina, sclera, and conjunctiva constitutively expressed TLR4, MD-2, and CD14 mRNA. The protein expression of these molecules was restricted, however, to resident antigen-presenting cells (APCs) in the normal human uvea, consisting mainly of HLA-DR + dendritic cells (DCs). These APCs endowed with the complete LPS Receptor complex appeared to be strategically positioned in perivascular and subepithelial locations for surveying blood-borne or intraocular LPS. In contrast, other cell types of the normal human cornea, conjunctiva, retina, and sclera did not express TLR4/MD-2 protein in vivo as detectable by immunohistochemistry. CONCLUSIONS. The present study demonstrates for the first time that resident APCs in the normal human uvea express TLR4 and its associated LPS Receptor complex. This has significant implications for the understanding of normal ocular immunity as well as unraveling the potential role of Gram-negative bacteria in the pathogenesis of acute anterior uveitis (AAU).
Yury I Miller - One of the best experts on this subject based on the ideXlab platform.
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minimally modified ldl binds to cd14 induces macrophage spreading via tlr4 md 2 and inhibits phagocytosis of apoptotic cells
Journal of Biological Chemistry, 2003Co-Authors: Yury I Miller, Suganya Viriyakosol, Christoph J Binder, James R Feramisco, Theo N Kirkland, Joseph L WitztumAbstract:Abstract Minimally modified low density lipoprotein (mmLDL) is a pro-inflammatory and pro-atherogenic lipoprotein that, unlike profoundly oxidized LDL (OxLDL), is not recognized by scavenger Receptors and thus does not have enhanced uptake by macrophages. However, here we demonstrate that mmLDL (as well as OxLDL) induces actin polymerization and spreading of macrophages, which results in such pro-atherogenic consequences as inhibition of phagocytosis of apoptotic cells but enhancement of OxLDL uptake. We also demonstrate for the first time that the Lipopolysaccharide Receptor, CD14, and toll-like Receptor-4/MD-2 are involved in these mmLDL effects. Macrophages of the J774 cell line exhibited higher mmLDL binding and F-actin response than its CD14-deficient mutant, LR-9 cells. Similarly, Chinese hamster ovary cells transfected with human CD14 specifically bound mmLDL and responded with higher F-actin compared with control cells. Macrophages from C3H/HeJ mice, which have a point mutation in the Tlr4 gene, responded with lower F-actin to mmLDL and did not spread as well as macrophages from control animals. A significantly higher F-actin response was also observed in Chinese hamster ovary cells transfected with human toll-like Receptor-4/MD-2 but not with TLR4 alone or TLR2. Thus, in addition to inhibition of phagocytosis, the recognition of mmLDL by macrophage Lipopolysaccharide Receptors results in convergence of cellular immune responses to products of microorganisms and to oxidation-specific self-antigens, which could both influence macrophage function and atherogenesis.
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Minimally modified LDL binds to CD14, induces macrophage spreading via TLR4/MD-2, and inhibits phagocytosis of apoptotic cells.
The Journal of biological chemistry, 2002Co-Authors: Yury I Miller, Suganya Viriyakosol, Christoph J Binder, James R Feramisco, Theo N Kirkland, Joseph L WitztumAbstract:Minimally modified low density lipoprotein (mmLDL) is a pro-inflammatory and pro-atherogenic lipoprotein that, unlike profoundly oxidized LDL (OxLDL), is not recognized by scavenger Receptors and thus does not have enhanced uptake by macrophages. However, here we demonstrate that mmLDL (as well as OxLDL) induces actin polymerization and spreading of macrophages, which results in such pro-atherogenic consequences as inhibition of phagocytosis of apoptotic cells but enhancement of OxLDL uptake. We also demonstrate for the first time that the Lipopolysaccharide Receptor, CD14, and toll-like Receptor-4/MD-2 are involved in these mmLDL effects. Macrophages of the J774 cell line exhibited higher mmLDL binding and F-actin response than its CD14-deficient mutant, LR-9 cells. Similarly, Chinese hamster ovary cells transfected with human CD14 specifically bound mmLDL and responded with higher F-actin compared with control cells. Macrophages from C3H/HeJ mice, which have a point mutation in the Tlr4 gene, responded with lower F-actin to mmLDL and did not spread as well as macrophages from control animals. A significantly higher F-actin response was also observed in Chinese hamster ovary cells transfected with human toll-like Receptor-4/MD-2 but not with TLR4 alone or TLR2. Thus, in addition to inhibition of phagocytosis, the recognition of mmLDL by macrophage Lipopolysaccharide Receptors results in convergence of cellular immune responses to products of microorganisms and to oxidation-specific self-antigens, which could both influence macrophage function and atherogenesis.
Tooru Shimosegawa - One of the best experts on this subject based on the ideXlab platform.
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Ulcerative Colitis is Associated with a Promoter Polymorphism of Lipopolysaccharide Receptor Gene, CD14
Scandinavian journal of gastroenterology, 2002Co-Authors: Nobuya Obana, Seiichi Takahashi, Yoshitaka Kinouchi, Kenichi Negoro, Sho Takagi, Nobuo Hiwatashi, Tooru ShimosegawaAbstract:Background: Inflammatory bowel disease (IBD) is a multifactorial disease with a significant genetic background. Evidence is accumulating that molecules such as CD14, which interact with luminal bacterial constituents, are involved in the pathogenesis. It has recently been shown that the T allele of the 5'-flanking region of the CD14 gene at position-159 is related to high expression of CD14. In further exploring the genetic background of IBD, we investigated this novel polymorphism of CD14 gene in patients with ulcerative colitis or Crohn disease. Methods: DNA was obtained from 101 patients with ulcerative colitis, 82 with Crohn disease and 123 healthy controls. All were typed for the promoter polymorphism of the CD14 gene at position-159 by restriction fragment length polymorphism analysis. Serum samples were obtained from 105 healthy controls and serum sCD14 levels were measured. Results: T allele frequencies were 57.4%, 48.2% and 44.7% in ulcerative colitis, Crohn disease and healthy controls, respecti...