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CUTTING EDGE |

*
Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84132; and
Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814
| Abstract |
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| Introduction |
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B-dependent production of inflammatory cytokines
(2). Although CD14 has been recognized as a nonsignaling
coreceptor for LPS (1), members of the Toll-like receptor
(TLR)3 family have
recently emerged as candidate receptors capable of transmitting LPS
signaling across the cell membrane. Currently, there are at least six TLR family members (TLR16) (3, 4, 5, 6), and two of these, TLR2 and TLR4, have been associated with LPS signaling (7, 8, 9, 10, 11, 12). A point mutation within tlr4 underlies the LPS hyporesponsiveness of C3H/HeJ mice (7, 8, 9), while overexpression of either TLR2 or TLR4 has been reported to confer responsiveness to LPS in cell lines (10, 11, 12). More recent data examining LPS responses in TLR2-deficient mice and hamsters indicate that TLR2 is not required for LPS signaling when TLR4 is present (13, 14, 15). TLR2 also has numerous non-LPS ligands (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26), and a possible explanation for the discrepancy concerning whether TLR2 and/or TLR4 mediate(s) LPS signaling is that the commercial LPS preparations used in the transfection experiments were contaminated with one or more of these ligands. Historically, investigators have documented that established protocols for isolating LPS result in the copurification of varying amounts of endotoxin protein(s) (27, 28, 29, 30, 31, 32). These contaminants are known to possess extremely potent bioactivity (28, 29, 30, 31, 32, 33, 34). Thus, assigning cellular responses to the LPS component of a particular preparation may be confounded by the presence of these contaminants. Using a protocol shown previously to remove endotoxin proteins from commercial LPS preparations (28), we investigated whether TLR2 mediates LPS responses in the absence of protein in vitro. Our results demonstrate that overexpressed TLR2 is extremely sensitive to minor contaminants in commercial LPS preparations.
| Materials and Methods |
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The human astrocytoma cell line U87 was obtained from the American Type Culture Collection (Manassas, VA). Bone marrow-derived macrophages were prepared from C3H/HeN and C3H/HeJ mice (National Cancer Institute, Frederick, MD) as described (35). The subclone of the human embryonic kidney epithelial cell line 293 and the constructs for human TLR, endothelial cell-leukocyte adhesion molecule (ELAM-1) luciferase, and respiratory syncytial virus (RSV)-ß-galactosidase were provided by Tularik (South San Francisco, CA) (10). LPS from Echerichia coli O111:B4 (smooth), J5 (Rc), and K12, D31 m4 (Re) were obtained from List Biological Laboratories (Campbell, CA). Recombinant OspA was provided by John Dunn (Brookhaven National Laboratories) (36). Synthetic lipid A was obtained from ICN Pharmaceuticals (Costa Mesa, CA). All other reagents were obtained from Sigma (St. Louis, MO). The coding sequence of TLR2 from C3H/HeN mice was amplified from genomic DNA and cloned into the mammalian expression vector pFLAG-CMV-1 (Sigma).
Removal of endotoxin protein from LPS
At room temperature, 5 mg of smooth, Rc, and Re LPS were individually resuspended in 1 ml of endotoxin-free water containing 0.2% triethylamine (TEA). Each sample was split into two 500-µl aliquots, and one aliquot was stored at 4°C without further manipulation ("unextracted LPS"). Deoxycholate (DOC) was added to the remaining aliquot to a final concentration of 0.5%, followed by the addition of 500 µl of water-saturated phenol. The samples were vortexed intermittently for 5 min, and the phases were allowed to separate at room temperature for 5 min. Samples were placed on ice for 5 min, followed by centrifugation at 4°C for 2 min at 10,000 x g. The top aqueous layer was transferred to a new tube, and the phenol phase was subjected to re-extraction with 500 µl of 0.2% TEA/0.5% DOC. The aqueous phases were pooled and re-extracted with 1 ml of water-saturated phenol. The pooled aqueous phases were adjusted to 75% ethanol and 30 mM sodium acetate and were allowed to precipitate at -20°C for 1 h. The precipitates were centrifuged at 4°C for 10 min at 10,000 x g, washed in 1 ml of cold 100% ethanol, and air-dried. The precipitates were resuspended in the original volume (500 µl) of 0.2% TEA. One hundred percent recovery was assumed for the purified LPS samples (28), which will be referred to as "phenol re-extracted LPS." This method was previously reported by Manthey et al. to eliminate the stimulatory activity of various LPS preparations on C3H/HeJ macrophage gene expression by removal of protein contaminants (28, 31).
Transfections
U87 cells were transfected in 12-well plates using pFx-2 (Invitrogen, Carlsbad, CA) with 2 µg of either TLR2 or TLR4 expression construct. Cells were then grown for 24 h in DMEM with Nutridoma-HU (Boehringer Mannheim, Indianapolis, IN) followed by stimulation with agonist for an additional 24 h in DMEM containing 2% human serum. 293 cells were cotransfected in six-well plates using a calcium phosphate kit (Clontech, Palo Alto, CA) at a ratio of 2:0.5:0.5 µg for the TLR2 expression construct, the ELAM-1 luciferase reporter construct, and the RSV ß-galactosidase construct to normalize for transfection efficiency. Cells were grown for 36 h and stimulated with the indicated agonist for an additional 6 h.
Luciferase and cytokine assays
IL-6 (U87) and IL-8 (293) production were measured by ELISA (Endogen, Woburn, MA). Transfected 293 cells were lysed using reporter lysis buffer (Promega, Madison, WI), and 20 µl of lysate was assayed for luciferase and ß-galactosidase activity using a Dynex MLX luminometer after incubation in luciferase assay reagent (Promega) or Galacto-Light with light emission accelerator (Tropix, Bedford, MA), respectively.
| Results |
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B-dependent luciferase reporter plasmid that
contains the E-selectin (ELAM-1) promoter. This particular 293 subclone
was previously described as LPS-unresponsive unless transfected with
TLR2, and this acquired LPS responsiveness was augmented either by
cotransfection with the CD14 gene or the presence of soluble CD14 in
serum (10). In this and following experiments, soluble
CD14 was provided in serum. To normalize for transfection efficiency,
an RSV ß-galactosidase control plasmid was also cotransfected. Only
unextracted Rc LPS was able to elicit a potent response in
TLR2-transfected 293 cells and was reflected in both luciferase (Fig. 2
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B translocation (Fig. 2
The ability of TLR4 to mediate signaling by phenol re-extracted LPS was
tested in another LPS-unresponsive cell line, U87. When TLR4 was
transfected into U87 cells, both unextracted and phenol re-extracted Rc
LPS caused secretion of IL-6 (Fig. 3
A). This effect was not seen
with either untransfected (data not shown) or TLR2-transfected (Fig. 3
B) U87 cells, in which secretion of IL-6 was only increased
when stimulated with unextracted LPS. In fact, expression of TLR4
enabled U87 cells to respond to 100-fold lower doses of both
unextracted and phenol re-extracted LPS than transfection of TLR2. U87
cells are also naturally responsive to purified bacterial lipoproteins
(Fig. 3
, A and B), suggesting that the protein
contaminants in unextracted LPS may be signaling through a similar
pathway. These results again provide evidence that TLR4, not TLR2,
mediates signaling by LPS in the absence of endotoxin protein.
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B translocation in 293 cells or IL-6
production in U87 cells (Fig. 4
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| Discussion |
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Our results suggest that the overexpression of either human or murine TLR2 causes cell lines to become extremely sensitive to the potent "endotoxin protein" contaminants present in many commercial LPS preparations. Our data clearly point to non-LPS ligands as the active agent(s) in previous papers that describe LPS-mediated TLR2 signaling and resolve the discrepancy between results from transfection studies and TLR2-deficient mice. However, the biology of TLR signaling is likely to be more complex. It is certainly possible that interactions among different TLRs could confer unique specificities capable of mediating LPS signaling in some cell types (41). Additionally, other, less well-characterized LPS signaling pathways may exist and may depend on the cell line (42) or the genetic background of the mouse strain (43). It is also possible that certain nonenterobacterial lipid A structures bind and/or signal through TLRs apart from TLR4 (42). However, these pathways do not seem to be active to any significant extent in TLR4-deficient mice (9, 13) or in the naturally occurring mutant strains C3H/HeJ and C57BL/10ScCR (7, 8, 28, 31); nor do they appear to occur to any measurable extent in the 293 or U87 human cells used in our study.
Although we have not characterized the biochemical nature of the contaminants responsible for TLR2-mediated signaling, it seems likely that bacterial lipoproteins could be at least partially responsible, given past reports demonstrating lipoprotein signaling mediated by TLR2 (18, 20, 22, 23, 26). In addition, lipoproteins possess extremely potent bioactivity, with some variants exhibiting half-maximal stimulation at levels as low as 3 pM in vitro (44). Similar concentrations of lipoproteins should easily be attainable in commercial preparations of LPS, which may be contaminated with up to 10% endotoxin protein (32). Undoubtedly, both TLR2 and TLR4 are important in the inflammatory response to Gram-negative bacterial infection because both endotoxin proteins and LPS are present in the context of whole bacteria. Thus, investigators should be aware of the contribution of combinations of microbial components and their subsequent activation of various TLRs to the pathogenesis of inflammatory events.
| Acknowledgments |
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| Footnotes |
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2 Address correspondence and reprint requests to Dr. Janis J. Weis, Department of Pathology, University of Utah School of Medicine, 50 North Medical Drive, Salt Lake City, UT 84132. ![]()
3 Abbreviations used in this paper: TLR, Toll-like receptor; ELAM-1, endothelial cell-leukocyte adhesion molecule (E-selectin); TEA, triethylamine; DOC, deoxycholate; RSV, respiratory syncytial virus. ![]()
Received for publication March 23, 2000. Accepted for publication May 11, 2000.
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M. W. Moore, A. R. Cruz, C. J. LaVake, A. L. Marzo, C. H. Eggers, J. C. Salazar, and J. D. Radolf Phagocytosis of Borrelia burgdorferi and Treponema pallidum Potentiates Innate Immune Activation and Induces Gamma Interferon Production Infect. Immun., April 1, 2007; 75(4): 2046 - 2062. [Abstract] [Full Text] [PDF] |
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A. Tirsoaga, A. Novikov, M. Adib-Conquy, C. Werts, C. Fitting, J.-M. Cavaillon, and M. Caroff Simple Method for Repurification of Endotoxins for Biological Use Appl. Envir. Microbiol., March 15, 2007; 73(6): 1803 - 1808. [Abstract] [Full Text] [PDF] |
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G. Sireci, M. P. La Manna, C. Di Sano, D. Di Liberto, S. A. Porcelli, M. Kronenberg, F. Dieli, and A. Salerno Pivotal Advance: {alpha}-Galactosylceramide induces protection against lipopolysaccharide-induced shock J. Leukoc. Biol., March 1, 2007; 81(3): 607 - 622. [Abstract] [Full Text] [PDF] |
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L. K. Weaver, P. A. Pioli, K. Wardwell, S. N. Vogel, and P. M. Guyre Up-regulation of human monocyte CD163 upon activation of cell-surface Toll-like receptors J. Leukoc. Biol., March 1, 2007; 81(3): 663 - 671. [Abstract] [Full Text] [PDF] |
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P. Winkler, D. Ghadimi, J. Schrezenmeir, and J.-P. Kraehenbuhl Molecular and Cellular Basis of Microflora-Host Interactions J. Nutr., March 1, 2007; 137(3): 756S - 772S. [Abstract] [Full Text] [PDF] |
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G. Elson, I. Dunn-Siegrist, B. Daubeuf, and J. Pugin Contribution of Toll-like receptors to the innate immune response to Gram-negative and Gram-positive bacteria Blood, February 15, 2007; 109(4): 1574 - 1583. [Abstract] [Full Text] [PDF] |
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P. Parroche, F. N. Lauw, N. Goutagny, E. Latz, B. G. Monks, A. Visintin, K. A. Halmen, M. Lamphier, M. Olivier, D. C. Bartholomeu, et al. From the Cover: Malaria hemozoin is immunologically inert but radically enhances innate responses by presenting malaria DNA to Toll-like receptor 9 PNAS, February 6, 2007; 104(6): 1919 - 1924. [Abstract] [Full Text] [PDF] |
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C. Erridge, O. L. Moncayo-Nieto, R. Morgan, M. Young, and I. R. Poxton Acinetobacter baumannii lipopolysaccharides are potent stimulators of human monocyte activation via Toll-like receptor 4 signalling J. Med. Microbiol., February 1, 2007; 56(2): 165 - 171. [Abstract] [Full Text] [PDF] |
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M. Jayachandran, G. J. Brunn, K. Karnicki, R. S. Miller, W. G. Owen, and V. M. Miller In vivo effects of lipopolysaccharide and TLR4 on platelet production and activity: implications for thrombotic risk J Appl Physiol, January 1, 2007; 102(1): 429 - 433. [Abstract] [Full Text] [PDF] |
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C. Erridge, C. M. Spickett, and D. J. Webb Non-enterobacterial endotoxins stimulate human coronary artery but not venous endothelial cell activation via Toll-like receptor 2 Cardiovasc Res, January 1, 2007; 73(1): 181 - 189. [Abstract] [Full Text] [PDF] |
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A. M. Hajjar, M. D. Harvey, S. A. Shaffer, D. R. Goodlett, A. Sjostedt, H. Edebro, M. Forsman, M. Bystrom, M. Pelletier, C. B. Wilson, et al. Lack of In Vitro and In Vivo Recognition of Francisella tularensis Subspecies Lipopolysaccharide by Toll-Like Receptors Infect. Immun., December 1, 2006; 74(12): 6730 - 6738. [Abstract] [Full Text] [PDF] |
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D. D. Bolz, R. S. Sundsbak, Y. Ma, S. Akira, J. H. Weis, T. G. Schwan, and J. J. Weis Dual Role of MyD88 in Rapid Clearance of Relapsing Fever Borrelia spp. Infect. Immun., December 1, 2006; 74(12): 6750 - 6760. [Abstract] [Full Text] [PDF] |
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A. Visintin, K. A. Halmen, N. Khan, B. G. Monks, D. T. Golenbock, and E. Lien MD-2 expression is not required for cell surface targeting of Toll-like receptor 4 (TLR4) J. Leukoc. Biol., December 1, 2006; 80(6): 1584 - 1592. [Abstract] [Full Text] [PDF] |
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D. J. Davidson, A. J. Currie, D. M. E. Bowdish, K. L. Brown, C. M. Rosenberger, R. C. Ma, J. Bylund, P. A. Campsall, A. Puel, C. Picard, et al. IRAK-4 Mutation (Q293X): Rapid Detection and Characterization of Defective Post-Transcriptional TLR/IL-1R Responses in Human Myeloid and Non-Myeloid Cells J. Immunol., December 1, 2006; 177(11): 8202 - 8211. [Abstract] [Full Text] [PDF] |
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C. D. Coldren, J. A. Nick, K. R. Poch, M. D. Woolum, B. W. Fouty, J. M. O'Brien, M. P. Gruber, M. R. Zamora, D. Svetkauskaite, D. A. Richter, et al. Functional and genomic changes induced by alveolar transmigration in human neutrophils Am J Physiol Lung Cell Mol Physiol, December 1, 2006; 291(6): L1267 - L1276. [Abstract] [Full Text] [PDF] |
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K. W. Boehme, M. Guerrero, and T. Compton Human Cytomegalovirus Envelope Glycoproteins B and H Are Necessary for TLR2 Activation in Permissive Cells J. Immunol., November 15, 2006; 177(10): 7094 - 7102. [Abstract] [Full Text] [PDF] |
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X. Yang, V. Murthy, K. Schultz, J. B. Tatro, K. A. Fitzgerald, and D. Beasley Toll-like receptor 3 signaling evokes a proinflammatory and proliferative phenotype in human vascular smooth muscle cells Am J Physiol Heart Circ Physiol, November 1, 2006; 291(5): H2334 - H2343. [Abstract] [Full Text] [PDF] |
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S. Ohta, U. Bahrun, R. Shimazu, H. Matsushita, K. Fukudome, and M. Kimoto Induction of Long-Term Lipopolysaccharide Tolerance by an Agonistic Monoclonal Antibody to the Toll-Like Receptor 4/MD-2 Complex Clin. Vaccine Immunol., October 1, 2006; 13(10): 1131 - 1136. [Abstract] [Full Text] [PDF] |
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H. Li, S. Nookala, X. R. Bina, J. E. Bina, and F. Re Innate immune response to Francisella tularensis is mediated by TLR2 and caspase-1 activation J. Leukoc. Biol., October 1, 2006; 80(4): 766 - 773. [Abstract] [Full Text] [PDF] |
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J. Rodo, L. A. Goncalves, J. Demengeot, A. Coutinho, and C. Penha-Goncalves MHC Class II Molecules Control Murine B Cell Responsiveness to Lipopolysaccharide Stimulation J. Immunol., October 1, 2006; 177(7): 4620 - 4626. [Abstract] [Full Text] [PDF] |
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A. W. Lee, L. Hertel, R. K. Louie, T. Burster, V. Lacaille, A. Pashine, D. A. Abate, E. S. Mocarski, and E. D. Mellins Human Cytomegalovirus Alters Localization of MHC Class II and Dendrite Morphology in Mature Langerhans Cells J. Immunol., September 15, 2006; 177(6): 3960 - 3971. [Abstract] [Full Text] [PDF] |
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M. Severa, E. M. Coccia, and K. A. Fitzgerald Toll-like Receptor-dependent and -independent Viperin Gene Expression and Counter-regulation by PRDI-binding Factor-1/BLIMP1 J. Biol. Chem., September 8, 2006; 281(36): 26188 - 26195. [Abstract] [Full Text] [PDF] |
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J. M. Marques, R. J. Rodrigues, A. C. de Magalhaes-Sant'Ana, and T. Goncalves Saccharomyces cerevisiae Hog1 Protein Phosphorylation upon Exposure to Bacterial Endotoxin J. Biol. Chem., August 25, 2006; 281(34): 24687 - 24694. [Abstract] [Full Text] [PDF] |
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T. H. Harris, N. M. Cooney, J. M. Mansfield, and D. M. Paulnock Signal transduction, gene transcription, and cytokine production triggered in macrophages by exposure to trypanosome DNA. Infect. Immun., August 1, 2006; 74(8): 4530 - 4537. [Abstract] [Full Text] [PDF] |
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J. L. Shoenfelt and M. J. Fenton TLR2- and TLR4-dependent activation of STAT1 serine phosphorylation in murine macrophages is protein kinase C-{delta}-independent Innate Immunity, August 1, 2006; 12(4): 231 - 240. [Abstract] [PDF] |
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B. Gao, Y. Wang, and M.-F. Tsan The heat sensitivity of cytokine-inducing effect of lipopolysaccharide J. Leukoc. Biol., August 1, 2006; 80(2): 359 - 366. [Abstract] [Full Text] [PDF] |
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H. J. Brown, H. R. Lock, S. H. Sacks, and M. G. Robson TLR2 Stimulation of Intrinsic Renal Cells in the Induction of Immune-Mediated Glomerulonephritis J. Immunol., August 1, 2006; 177(3): 1925 - 1931. [Abstract] [Full Text] [PDF] |
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K. A. Scheibner, M. A. Lutz, S. Boodoo, M. J. Fenton, J. D. Powell, and M. R. Horton Hyaluronan Fragments Act as an Endogenous Danger Signal by Engaging TLR2 J. Immunol., July 15, 2006; 177(2): 1272 - 1281. [Abstract] [Full Text] [PDF] |
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L. K. Weaver, K. A. Hintz-Goldstein, P. A. Pioli, K. Wardwell, N. Qureshi, S. N. Vogel, and P. M. Guyre Pivotal Advance: Activation of cell surface Toll-like receptors causes shedding of the hemoglobin scavenger receptor CD163 J. Leukoc. Biol., July 1, 2006; 80(1): 26 - 35. [Abstract] [Full Text] [PDF] |
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C. N. Renn, D. J. Sanchez, M. T. Ochoa, A. J. Legaspi, C.-K. Oh, P. T. Liu, S. R. Krutzik, P. A. Sieling, G. Cheng, and R. L. Modlin TLR Activation of Langerhans Cell-Like Dendritic Cells Triggers an Antiviral Immune Response J. Immunol., July 1, 2006; 177(1): 298 - 305. [Abstract] [Full Text] [PDF] |
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H. J. Brown, S. H. Sacks, and M. G. Robson Toll-Like Receptor 2 Agonists Exacerbate Accelerated Nephrotoxic Nephritis J. Am. Soc. Nephrol., July 1, 2006; 17(7): 1931 - 1939. [Abstract] [Full Text] [PDF] |
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A. E. Medvedev, I. Sabroe, J. D. Hasday, and S. N. Vogel Invited review: Tolerance to microbial TLR ligands: molecular mechanisms and relevance to disease Innate Immunity, June 1, 2006; 12(3): 133 - 150. [Abstract] [PDF] |
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O. Dehus, T. Hartung, and C. Hermann Endotoxin evaluation of eleven lipopolysaccharides by whole blood assay does not always correlate with Limulus amebocyte lysate assay Innate Immunity, June 1, 2006; 12(3): 171 - 180. [Abstract] [PDF] |
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G. Gatti, V. Rivero, R. D. Motrich, and M. Maccioni Prostate epithelial cells can act as early sensors of infection by up-regulating TLR4 expression and proinflammatory mediators upon LPS stimulation J. Leukoc. Biol., May 1, 2006; 79(5): 989 - 998. [Abstract] [Full Text] [PDF] |
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D. C. Rowe, A. F. McGettrick, E. Latz, B. G. Monks, N. J. Gay, M. Yamamoto, S. Akira, L. A. O'Neill, K. A. Fitzgerald, and D. T. Golenbock The myristoylation of TRIF-related adaptor molecule is essential for Toll-like receptor 4 signal transduction PNAS, April 18, 2006; 103(16): 6299 - 6304. [Abstract] [Full Text] [PDF] |
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K. Zacharowski, P. A. Zacharowski, A. Koch, A. Baban, N. Tran, R. Berkels, C. Papewalis, K. Schulze-Osthoff, P. Knuefermann, U. Zahringer, et al. Toll-like receptor 4 plays a crucial role in the immune-adrenal response to systemic inflammatory response syndrome PNAS, April 18, 2006; 103(16): 6392 - 6397. [Abstract] [Full Text] [PDF] |
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H. S. Seo, J. H. Kim, and M. H. Nahm Platelet-Activating Factor-Acetylhydrolase Can Monodeacylate and Inactivate Lipoteichoic Acid Clin. Vaccine Immunol., April 1, 2006; 13(4): 452 - 458. [Abstract] [Full Text] [PDF] |
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L. R. Young, M. T. Borchers, H. L. Allen, R. S. Gibbons, and F. X. McCormack Lung-Restricted Macrophage Activation in the Pearl Mouse Model of Hermansky-Pudlak Syndrome J. Immunol., April 1, 2006; 176(7): 4361 - 4368. [Abstract] [Full Text] [PDF] |
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J. Fan, Y. Li, Y. Vodovotz, T. R. Billiar, and M. A. Wilson Hemorrhagic shock-activated neutrophils augment TLR4 signaling-induced TLR2 upregulation in alveolar macrophages: role in hemorrhage-primed lung inflammation Am J Physiol Lung Cell Mol Physiol, April 1, 2006; 290(4): L738 - L746. [Abstract] [Full Text] [PDF] |
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R. E. Rumbaut, R. V. Bellera, J. K. Randhawa, C. N. Shrimpton, S. K. Dasgupta, J.-F. Dong, and A. R. Burns Endotoxin enhances microvascular thrombosis in mouse cremaster venules via a TLR4-dependent, neutrophil-independent mechanism Am J Physiol Heart Circ Physiol, April 1, 2006; 290(4): H1671 - H1679. [Abstract] [Full Text] [PDF] |
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J. S. Park, F. Gamboni-Robertson, Q. He, D. Svetkauskaite, J.-Y. Kim, D. Strassheim, J.-W. Sohn, S. Yamada, I. Maruyama, A. Banerjee, et al. High mobility group box 1 protein interacts with multiple Toll-like receptors Am J Physiol Cell Physiol, March 1, 2006; 290(3): C917 - C924. [Abstract] [Full Text] [PDF] |
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J. Bylund, L.-A. Burgess, P. Cescutti, R. K. Ernst, and D. P. Speert Exopolysaccharides from Burkholderia cenocepacia Inhibit Neutrophil Chemotaxis and Scavenge Reactive Oxygen Species J. Biol. Chem., February 3, 2006; 281(5): 2526 - 2532. [Abstract] [Full Text] [PDF] |
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M. Hashimoto, K. Tawaratsumida, H. Kariya, K. Aoyama, T. Tamura, and Y. Suda Lipoprotein is a predominant Toll-like receptor 2 ligand in Staphylococcus aureus cell wall components Int. Immunol., February 1, 2006; 18(2): 355 - 362. [Abstract] [Full Text] [PDF] |
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T. B. Thornley, M. A. Brehm, T. G. Markees, L. D. Shultz, J. P. Mordes, R. M. Welsh, A. A. Rossini, and D. L. Greiner TLR Agonists Abrogate Costimulation Blockade-Induced Prolongation of Skin Allografts J. Immunol., February 1, 2006; 176(3): 1561 - 1570. [Abstract] [Full Text] [PDF] |
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C. M. O'Connell, I. A. Ionova, A. J. Quayle, A. Visintin, and R. R. Ingalls Localization of TLR2 and MyD88 to Chlamydia trachomatis Inclusions: EVIDENCE FOR SIGNALING BY INTRACELLULAR TLR2 DURING INFECTION WITH AN OBLIGATE INTRACELLULAR PATHOGEN J. Biol. Chem., January 20, 2006; 281(3): 1652 - 1659. [Abstract] [Full Text] [PDF] |
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S. H. Han, J. H. Kim, H. S. Seo, M. H. Martin, G.-H. Chung, S. M. Michalek, and M. H. Nahm Lipoteichoic Acid-Induced Nitric Oxide Production Depends on the Activation of Platelet-Activating Factor Receptor and Jak2 J. Immunol., January 1, 2006; 176(1): 573 - 579. [Abstract] [Full Text] [PDF] |
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K. L. Williams, J. D. Lich, J. A. Duncan, W. Reed, P. Rallabhandi, C. Moore, S. Kurtz, V. M. Coffield, M. A. Accavitti-Loper, L. Su, et al. The CATERPILLER Protein Monarch-1 Is an Antagonist of Toll-like Receptor-, Tumor Necrosis Factor {alpha}-, and Mycobacterium tuberculosis-induced Pro-inflammatory Signals J. Biol. Chem., December 2, 2005; 280(48): 39914 - 39924. [Abstract] [Full Text] [PDF] |
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S. Morath, S. von Aulock, and T. Hartung Structure/function relationships of lipoteichoic acids Innate Immunity, December 1, 2005; 11(6): 348 - 356. [Abstract] [PDF] |
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L. Romics Jr, A. Dolganiuc, A. Velayudham, K. Kodys, P. Mandrekar, D. Golenbock, E. Kurt-Jones, and G. Szabo Toll-like receptor 2 mediates inflammatory cytokine induction but not sensitization for liver injury by Propioni- bacterium acnes J. Leukoc. Biol., December 1, 2005; 78(6): 1255 - 1264. [Abstract] [Full Text] [PDF] |
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L. C. Parker, E. C. Jones, L. R. Prince, S. K. Dower, M. K. B. Whyte, and I. Sabroe Endotoxin tolerance induces selective alterations in neutrophil function J. Leukoc. Biol., December 1, 2005; 78(6): 1301 - 1305. [Abstract] [Full Text] [PDF] |
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