Identification of a Lipopolysaccharide Binding Domain in CD14 between Amino Acids 57 and 64

Juan, Todd; Hailman, Eric; Kelley, Michael J.; Busse, Leigh; Davy, Elyse; Empig, Cyril; Narhi, Linda O.; Wright, Samuel D.; Lichenstein, Henri S.

doi:10.1074/jbc.270.10.5219

Cited by 117 publications

(108 citation statements)

References 21 publications

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“…However, neither an epitope for 4C1 nor an LPS binding site has been identified in murine CD14 (26). In contrast, it has been demonstrated that LPS can bind to the negatively charged domain in human CD14 spanning aa 57-64 (D 57 ADPRQYA 64 ), which can be recognized by a neutralizing anti-human CD14 mAb MEM-18 (27). Moreover, it has been reported that the region at position 9 -13 (D 9 DEDF 13 ) comprising anionic amino acids is also involved in the binding of LPS to human CD14 (45).…”

Section: Discussionmentioning

confidence: 99%

“…4C1 can block the binding of LPS to CD14 ϩ cells, whereas rmC5-3 has little effect on LPS binding (26). Ascites of anti-human CD14 mAb MEM-18, which can recognize an epitope in the region spanning aa 57-64 of human CD14 and block the binding of LPS to CD14 (27), was obtained from HyCult Biotechnology. Rabbit control IgG was prepared from nonimmunized rabbit serum by affinity chromatography using a Hitrap protein A column (Amersham Pharmacia Biotech, Little Chalfont, U.K.).…”

Section: Antibodiesmentioning

confidence: 99%

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Cathelicidin Family of Antibacterial Peptides CAP18 and CAP11 Inhibit the Expression of TNF-α by Blocking the Binding of LPS to CD14+ Cells

Nagaoka

Hirota

Niyonsaba

et al. 2001

The Journal of Immunology

250

248

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Mammalian myeloid and epithelial cells express several kinds of antibacterial peptides (α-/β-defensins and cathelicidins) that contribute to the innate host defense by killing invading micro-organisms. In this study we evaluated the LPS-neutralizing activities of cathelicidin peptides human CAP18 (cationic antibacterial proteins of 18 kDa) and guinea pig CAP11 using the CD14+ murine macrophage cell line RAW264.7 and the murine endotoxin shock model. Flow cytometric analysis revealed that CAP18 and CAP11 inhibited the binding of FITC-conjugated LPS to RAW264.7 cells. Likewise, Northern and Western blot analyses indicated that CAP18 and CAP11 suppressed LPS-induced TNF-α mRNA and protein expression by RAW264.7 cells. Interestingly, CAP18 and CAP11 possessed LPS-binding activities, and they strongly suppressed the interaction of LPS with LPS binding protein that mediates the transport of LPS to CD14 to facilitate the activation of CD14+ cells by LPS. Moreover, when CAP18 and CAP11 were preincubated with RAW264.7 cells, they bound to the cell surface CD14 and inhibited the binding of FITC-LPS to the cells. Furthermore, in the murine endotoxin shock model, CAP18 or CAP11 administration inhibited the binding of LPS to CD14+ cells (peritoneal macrophages) and suppressed LPS-induced TNF-α expression by these cells. Together these observations indicate that cathelicidin peptides CAP18 and CAP11 probably exert protective actions against endotoxin shock by blocking the binding of LPS to CD14+ cells, thereby suppressing the production of cytokines by these cells via their potent binding activities for LPS and CD14.

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Section: Discussionmentioning

confidence: 99%

Section: Antibodiesmentioning

confidence: 99%

Cathelicidin Family of Antibacterial Peptides CAP18 and CAP11 Inhibit the Expression of TNF-α by Blocking the Binding of LPS to CD14+ Cells

Nagaoka

Hirota

Niyonsaba

et al. 2001

The Journal of Immunology

250

248

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“…The LPS-CD14 complex then initiates intracellular signalling by binding to Toll-like receptor 4 (TLR4) (Aderem and Ulevitch, 2000). At least one other protein, MD-2, is associated with CD14 and TLR4 on the cell surface; together, these make up the LPS receptor (da Silva Correia and Ulevitch, 2002;Juan et al, 1995;Stelter et al, 1997;Stelter et al, 1999;Viriyakosol and Kirkland, 1995;Viriyakosol et al, 2000). The binding of C1 inhibitor to LPS (or lipid A) was inhibited by fetal bovine serum, which contains LBP, and by an LBP peptide that includes the binding site for LBP (Liu et al, 2003).…”

Section: The Interaction Of C1 Inhibitor With Gram Negative Bacterialmentioning

confidence: 99%

C1 inhibitor: Biologic activities that are independent of protease inhibition

Davis

Cai

2007

Immunobiology

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C1 inhibitor therapy improves outcome in several animal models of inflammatory disease. These include sepsis and gram negative endotoxin shock, vascular leak syndromes, hyperacute transplant rejection, and ischemia-reperfusion injury. Furthermore, some data suggest a beneficial effect in human inflammatory disease. In many inflammatory conditions, complement system activation plays a role in pathogenesis. The contact system also very likely is involved in mediation of damage in inflammatory disease. Therefore, the beneficial effect of C1 inhibitor has been assumed to result from inhibition of one or both of these systems. Over the past several years, several other potential anti-inflammatory effects of C1 inhibitor have been described. These effects do not appear to require protease inhibition and depend on non-covalent interactions with other proteins, cell surfaces or lipids. In the first, C1 inhibitor binds to a variety of extracellular matrix components including type IV collagen, laminin, entactin and fibrinogen. The biologic role of these reactions is unclear, but they may serve to concentrate C1 inhibitor at extravascular inflammatory sites. The second is a noncovalent interaction with C3b that results in inhibition of formation of the alternative pathway C3 convertase, a function analogous to that of factor H. The third is an interaction with E and P selectins on endothelial cells that is mediated by the Lewis x tetrasaccharides that are expressed on C1 inhibitor. These interactions result in suppression of leukocyte rolling and transmigration. The fourth interaction is the binding of C1 inhibitor to gram negative bacterial endotoxin that results in suppression of endotoxin shock by interference with the interaction of endotoxin with its receptor complex on macrophages. Lastly, C1 inhibitor binds directly to gram negative bacteria, which leads to suppression of the development of sepsis, as demonstrated in the cecal ligation and puncture model. These observations suggest that C1 inhibitor is a multi-faceted anti-inflammatory protein that exerts its effects through a variety of mechanisms including both protease inhibition and several different non-covalent interactions that are unrelated to protease inhibition.

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“…However, the mode of recognition of these structurally distinct patterns by CD14 is not clear, since structural details for CD14 in complex with any of its ligands is not available. Deletion mutagenesis experiments and epitope mapping studies with blocking antibodies and proteases have previously identified broad regions on CD14 that are crucial for binding of various microbial ligands (residues 39-44, 57-64, 81-100) and which possess overlapping sites of interaction for these ligands [11][12][13][14][15]. More recently, a highresolution X-ray crystal structure for mouse sCD14 by itself has been determined [16], in which a potential endotoxin binding pocket can be seen at the N-terminus, with the binding regions identified previously from the mutagenesis experiments clustered around this pocket.…”

mentioning

confidence: 99%

Solution NMR studies provide structural basis for endotoxin pattern recognition by the innate immune receptor CD14

Albright¹,

Chen²,

Holbrook³

et al. 2008

Biochemical and Biophysical Research Communications

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CD14 functions as a key pattern recognition receptor for a diverse array of gram-negative and grampositive cell-wall components in the host innate immune response by binding to pathogen-associated molecular patterns (PAMPs) at partially overlapping binding site(s). To determine the potential contribution of CD14 residues in this pattern recognition, we have examined using solution NMR spectroscopy the binding of three different endotoxin ligands, Lipopolysaccharide, lipoteichoic acid and a PGN-derived compound, muramyl dipeptide to a 15 N isotopically labeled 152-residue Nterminal fragment of sCD14 expressed in Pichia pastoris. Mapping of NMR spectral changes upon addition of ligands revealed that the pattern of residues affected by binding of each ligand is partially similar and partially different. This first direct structural observation of the ability of specific residue combinations of CD14 to differentially affect endotoxin binding may help explain the broad specificity of CD14 in ligand recognition and provide a structural basis for pattern recognition. Another interesting finding from the observed spectral changes is that the mode of binding may be dynamically modulated and could provide a mechanism for binding endotoxins with structural diversity through a common binding site. KeywordsNMR; human CD14 structure; CD14-endotoxin complex; endotoxin; pattern recognition; pichia pastoris expression; isotopic labeling; cell-based assay; lipopolysaccharide; ReLPS; LTA; BODIPY Clinical manifestation of sepsis typically involves a complex interaction between the host immune system and major bacterial cell wall constituents known as endotoxins. The cluster differentiation antigen, CD14, has been shown to be a key high-affinity cellular receptor for these bacterial endotoxins and plays an important role in endotoxin-induced activation of innate immune cells [1]. In humans, CD14 is constitutively expressed on cell surfaces of monocytes/ macrophages as a 55 kDa membrane-bound protein and also exists in a soluble form (sCD14), in serum and bodily fluids in concentrations of 2-6 μg/ml [2,3]. Recognition and binding of different microbial endotoxins to both mCD14 and sCD14 initiates a signaling cascade mediated by Toll-like receptors (TLRs) that promotes the synthesis and secretion of multiple host-derived inflammatory mediators [4], overactivation of which is ultimately responsible for the deleterious effects of sepsis. Understanding mechanism of endotoxin recognition is

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Identification of a Lipopolysaccharide Binding Domain in CD14 between Amino Acids 57 and 64

Cited by 117 publications

References 21 publications

Cathelicidin Family of Antibacterial Peptides CAP18 and CAP11 Inhibit the Expression of TNF-α by Blocking the Binding of LPS to CD14+ Cells

Cathelicidin Family of Antibacterial Peptides CAP18 and CAP11 Inhibit the Expression of TNF-α by Blocking the Binding of LPS to CD14+ Cells

C1 inhibitor: Biologic activities that are independent of protease inhibition

Solution NMR studies provide structural basis for endotoxin pattern recognition by the innate immune receptor CD14

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