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PubMed1994

Structure of lipid A component of Rhizobium leguminosarum bv. phaseoli lipopolysaccharide. Unique nonphosphorylated lipid A containing 2-amino-2-deoxygluconate, galacturonate, and glucosamine.

The structure of lipid A from the lipopolysaccharide of Rhizobium leguminosarum bv. phaseoli (wild type strain CE3) was investigated by alkylation analysis, nuclear magnetic resonance spectroscopy, and electrospray and fast atom bombardment mass spectrometry of the de-O-acylated lipid A. The lipid A carbohydrate backbone was shown to be a trisaccharide containing galacturonic acid, glucosamine, and the unique sugar 2-amino-2-deoxygluconic acid, previously unreported in lipopolysaccharides. Nuclear magnetic resonance spectroscopy and ethylation analyses revealed that the galacturonic acid is alpha-1,4-linked to the glucosamine, while the amino aldonic acid residue, which may exist as the 1,5-lactone, is attached as an aglycone to the glucosamine and, thus, occupies the reducing end of the molecule. The resulting backbone is hydrophilic and analogous to the commonly observed bisphosphorylated glucosamine disaccharide from enteric bacterial lipopolysaccharides in that both the nonreducing and reducing ends carry negatively charged substituents. The fatty acids of the R. leguminosarum lipid A are attached both as O- and N-acyl substituents to glucosamine and 2-aminogluconate. All fatty acids are hydroxylated consisting of 3-hydroxymyristate (3-OH-C14.0), 3-hydroxypentadecanoate (3-OH-C15.0), 3-hydroxypalmitate (3-OH-C16.0), 3-hydroxystearate (3-OH-C18.0), and 27-hydroxyoctacosanoate (27-OH-C28.0) in the approximate mole ratio 3:0.2:1:0.6:1. Unlike lipid As from enteric bacteria, the R. leguminosarum lipid A lacks 3-acyloxyacyl substituents; however, the long chain 27-hydroxy fatty acid carries ester-linked beta-hydroxybutyrate at the 27-hydroxy position. Fast atom bombardment mass spectrometry of the de-O-acylated lipid A demonstrated the presence of 2 molecular species that differ by 28 mass units due to fatty acid heterogeneity at the two amide linkages. One species carries amide-linked 3-OH-C14.0 and 3-OH-C16.0; the second species carries 3-OH-C14.0 and 3-OH-C18.0. Each molecular species also exists as the aldonolactone, yielding molecular ions at ((M+H)+)-18. The heterogeneity in the amide-linked fatty acids further distinguishes the Rhizobium lipid A from enteric lipid As.

Carbohydrate Conformation↗

PubMed2001

Lipopolysaccharide and ceramide docking to CD14 provokes ligand-specific receptor clustering in rafts.

The glycosylphosphatidylinositol-anchored receptor CD14 plays a major role in the inflammatory response of monocytes to lipopolysaccharide. Here, we describe that ceramide, a constituent of atherogenic lipoproteins, binds to CD14 and induces clustering of CD14 to co-receptors in rafts. In resting cells, CD14 was associated with CD55, the Fcgamma-receptors CD32 and CD64 and the pentaspan CD47. Ceramide further recruited the complement receptor 3 (CD11b/CD18) and CD36 into proximity of CD14. Lipopolysaccharide, in addition, induced co-clustering with Toll-like receptor 4, Fcgamma-RIIIa (CD16a) and the tetraspanin CD81 while CD47 was dissociated. The different receptor complexes may be linked to ligand-specific cellular responses initiated by CD14.

Antigens, CD↗

PubMed2003

CD55/decay accelerating factor is part of the lipopolysaccharide-induced receptor complex.

Recently, we described an 80-kDa lipopolysaccharide (LPS)-binding membrane protein to be identical to CD55 [decay accelerating factor (DAF)]. Here, we demonstrate that CD55 is able to contribute to lipopolysaccharide (LPS) signaling. Transfection of Chinese hamster ovary (CHO) cells with human CD55 resulted in a translocation of NF-kappa B after stimulation with LPS as well as with free lipid A. In addition, interaction of lipid A and CD55 was shown by co-immuno-precipitation of these molecules from CHO-CD55 cells after incubation with lipid A and anti-lipid A monoclonal antibody, as well as by fluorescence resonance energy transfer (FRET) analysis in human monocytes. The comparison of LPS-induced signaling pathways in CHO-CD55 and CHO-CD14 cells revealed that p38, JNK and ERK MAP kinases are activated upon LPS stimulation in both cell lines, and that the activation by LPS can be blocked at the level of Toll-like receptor 4. Finally, through FRET analysis we could demonstrate LPS-induced clustering of CD55 and CD11/CD18 in human monocytes. Our results imply a new functional role of CD55 as a member of a multimeric LPS receptor complex.

Animals↗

PubMed1991

Effect of cytokines and lipopolysaccharide on CD14 antigen expression in human monocytes and macrophages.

The 52 kD myeloid membrane glycoprotein CD14 represents the receptor for complexes of lipopolysaccharide (LPS) and LPS binding protein (LBP); it is involved in LPS induced tumor necrosis factor-alpha production. Expression of CD14 increases in monocytes differentiating into macrophages, and it is reduced by rIFNg in monocytes in vitro. In the present study CD14 membrane antigen expression was investigated in cultures of human mononuclear leucocytes (PBL), in elutriated, purified monocytes, and in blood monocyte derived Teflon cultured macrophages. Cells were incubated for 15 or 45 h with rIL-1, rIL-2, rIL-3, rIL-5, rIL-6, rTNFa, rGM-CSF, rM-CSF, rTGFb1, rIFNa, lipopolysaccharide (LPS), and, as a control, rIFNg. The monoclonal antibodies Leu-M3 and MEM 18 were used for labelling of CD14 antigen by indirect immunofluorescence and FACS analysis of scatter gated monocytes or macrophages. IFNg concentrations were determined in PBL culture supernatants by ELISA. rIFNa and rIL-2 reduced CD14 in 15 and 45 h PBL cultures, an effect mediated by endogenous IFNg, since it was abolished by simultaneous addition of an anti-IFNg antibody. rIFNa and rIL-2 were ineffective in purified monocytes or macrophages. rIL-4 strongly reduced CD14 in PBL and purified monocytes after 45 h, whereas in macrophages the decrease was weak, although measurable after 15 h. The other cytokines investigated did not change CD14 antigen expression. Cycloheximide alone reduced CD14, but when added in combination with rIFNg the effect on CD14 downregulation was more pronounced. The effect of rIFNg on CD14 in PBL cultures was dose-dependently inhibited by rIL-4 and this inhibition is probably due to an IL-4 mediated blockade of IFNg secretion. LPS at a low dose increased CD14, at a high dose it produced a variable decrease of CD14 in PBL, which was probably due to LPS induced IFNg secretion. LPS strongly enhanced CD14 in 45 h cultures of purified monocytes. The results, showing that CD14 antigen expression is upregulated by LPS and downregulated by rIFNg and rIL-4, suggest that the LPS-LBP receptor is involved in the feedback response of IFNg and IL-4 to LPS stimulation.

Antibodies↗

PubMed1996

Purification of lipopolysaccharide-binding protein from bovine serum.

Lipopolysaccharide-binding protein (LBP) plays a central role in presentation of bacterial-derived lipopolysaccharide (LPS; endotoxin) to leukocytes such as macrophages and neutrophils. Interaction of LBP with LPS is significant because LBP-LPS complexes promote activation of leukocytes and the immune system, which results in enhanced secretion of a spectrum of proinflammatory cytokines. An improved, simplified method was used to purify bovine LBP from serum. Methodology consisted of ion-exchange chromatography using Bio-Rex 70 resin, followed by gel-filtration chromatography (Sephacryl S-200 resin) of a selected ion-exchange fraction (0.22-0.50 M NaCl). Densitometric scans on silver-stained polyacrylamide gels of chromatographically-derived proteins indicated up to 88.7% purity of the resultant 64kD protein (bovine LBP) in the cleanest fractions. The isoelectric point of bovine LBP was determined to be 6.8. Identity of the protein was substantiated by western-blot analysis, and by N-terminus amino acid sequence analysis with favorable comparison to published sequence data from rabbit, human, and murine LBP Identity was corroborated by use of purified bovine LBP in bioassays which demonstrated enhanced tissue factor expression of LPS (1 ng ml(-1)-stimulated bovine alveolar macrophages. Tissue factor expression was inhibitable in these assays using anti-CD14 monoclonal antibodies, which is also consistent with LBP-mediated activation of cells. When bovine LBP was heated at 56 degrees C for 30 min, the biological activity was reduced by 50% in the macrophage-based bioassays. Biological activity of bovine LBP was completely destroyed by heating at 62 degrees C for 30 min, which compared favorably with data resulting from use of fetal bovine serum.

Acute-Phase Proteins↗

PubMed2006

Purification of soluble CD14 fusion proteins and use in an electrochemiluminescent assay for lipopolysaccharide binding.

CD14, a 55kDa lipopolysaccharide binding glycoprotein, is a key element in both LPS-mediated activation of cells and endotoxin detoxification. A gene fragment containing residues 1-348 of the human LPS receptor CD14, representing the extracellular form of the molecule, was fused to the CH(2)-CH(3) portion of the human IgG heavy chain or to a 6x His tag and transfected into CHO cells. Stable cell lines of each were grown to produce recombinant protein in unsupplemented serum free media and CD14His was purified by ion-exchange chromatography. After passive immobilization onto a carbon surface both forms of the CD14 fusion proteins bound LPS-biotin in a dose-dependent manner in an electrochemiluminescent assay. Binding was inhibited by the anti-CD14 antibody S39 as well as by unlabeled LPS. This report describes an efficient method of purifying CD14 and a novel assay to detect bioactive lipopolysaccharide.

Animals↗

PubMed2002

Study of interleukin-10 and interleukin-12 productions in response to lipopolysaccharides extracted from two different Brucella strains.

The aim of the present study is to investigate the cytokines induction by smooth lipopolysaccharides (S-LPS) extracted from Brucella melitensis (Rev1 vaccine strain) and Brucella abortus (a field isolate). These lipopolysaccharides were used to induce inflammatory cytokines production in peripheral blood cell culture of healthy individuals. Secretion of IL-10 and IL-12 (p70) were measured by means of specific Elisa. In addition, intracellular expression of IL-12 was assessed in CD14+ cells by flow cytometry. It was shown that Brucella LPS is a potent inducer of IL-10. However interferon gamma (IFN-gamma) priming was able to significantly decrease the production of IL-10. Flow cytometry studies showed that LPS alone was not able to induce intracellular IL-12 expression in CD14+ cells. Nevertheless, IFN-gamma priming significantly increased the percentage of CD14+ IL-12+ cells. In conclusion, it was demonstrated that the Brucella LPS could be a potent inducer of IL-10 and induction of IL-12 production needs the most favorable conditions.

Brucella↗

PubMed1997

L-Selectin--a signalling receptor for lipopolysaccharide.

The activation of leukocytes by bacterial cell-wall lipopolysaccharide contributes to the pathogenesis of septic shock. We propose that in neutrophils, and possibly other leukocytes, L-selectin can act as a low-affinity lipopolysaccharide receptor. Inhibitors of L-selectin may therefore be of therapeutic value in treating this life-threatening condition.

Animals↗

PubMed2002

Structure and function of lipopolysaccharides.

The lipopolysaccharides of Gram-negative bacteria have a profound effect on the mammalian immune system and are of great significance in the pathophysiology of many disease processes. Consideration is given in this review to the relationship between structure and function of these lipopolysaccharides.

Carbohydrate Conformation↗

PubMed2002

Lipopolysaccharide recognition: CD14, TLRs and the LPS-activation cluster.

Recognition of bacterial lipopolysaccharide (LPS) by the innate immune system elicits strong pro-inflammatory responses that can eventually cause a fatal sepsis syndrome in humans. LPS-mediated activation of mammalian cells is believed to involve the interaction of LPS with lipopolysaccharide-binding protein (LBP) in the serum and, subsequently with CD14. Although there is no doubt that CD14 binds LPS, CD14 is not capable of initiating a transmembrane activation signal because it is a glycosylphosphatidylinositol (GPI)-anchored protein. Accumulating evidence has suggested that LPS must interact with a transmembrane receptor(s) that is responsible for signal transduction. Integrins CD11c and/or CD18, Toll-like receptors (TLRs), as well as CD55, have been suggested to serve this function. Recently, we have revealed that a signalling complex of receptors is formed following LPS stimulation, which comprises heat-shock proteins (Hsps) 70 and 90, chemokine receptor 4 (CXCR4) and growth differentiation factor 5 (GDF5). Taking into account the discovery of the TLRs and the LPS-activation cluster, we propose a new model of LPS recognition.

Animals↗

PubMed2004

Ehrlichia chaffeensis downregulates surface Toll-like receptors 2/4, CD14 and transcription factors PU.1 and inhibits lipopolysaccharide activation of NF-kappa B, ERK 1/2 and p38 MAPK in host monocytes.

Microbial ligands, such as lipopolysaccharide (LPS), activate Toll-like receptors (TLRs) of mononuclear phagocytes, thus activating transcription factors including NF-kappa B and inducing antimicrobial activity. Ehrlichia chaffeensis, an obligatory intramonocytic Gram-negative bacterium, causes human monocytic ehrlichiosis. In the present study, we found that E. chaffeensis-infected human monocytes became progressively less responsive to Escherichia coli lipopolysaccharide (LPS) in activating NF-kappa B and mobilizing ehrlichiacidal activities. E. chaffeensis infection caused downregulation of the expression of several pattern recognition receptors, such as CD14, TLR2 and TLR4, as revealed by flow cytometry and/or reverse transcription polymerase chain reaction analysis. Electrophoretic mobility shift assay revealed that the activity of a transcription factor PU.1 was also downregulated by E. chaffeensis infection. ERK 1/2 and p38 MAPK were slightly activated at the early stage of E. chaffeensis infection; however, the activations of ERK 1/2 and p38 MAPK by LPS treatment were subsequently reduced in E. chaffeensis-infected monocytes compared with those in uninfected monocytes. Like E. chaffeensis, the p38 MAPK-specific inhibitor SB 203580 downregulated PU.1 activity and the expression of TLR2, TLR4 and CD14 in human monocytes, suggesting that the inhibition of p38 MAPK by E. chaffeensis is involved in the suppression of several downstream signalling pathways. These data point to a novel mechanism by which E. chaffeensis can survive by inhibiting critical signalling in monocyte activation pathways linked to pattern recognition receptors.

Cells, Cultured↗

PubMed2000

Isolation, partial characterization, and concentration in experimental sepsis of baboon lipopolysaccharide-binding protein.

Lipopolysaccharide-binding protein (LBP) is important for mediating host responses to lipopolysaccharide (LPS). The structure and properties of human, rabbit, and murine LBP have been previously described. In this study we partially characterized baboon LBP and investigated its appearance in experimental sepsis. Recurrent bacteremia was induced in baboons by infusion of live Escherichia coli organisms over a 2-hour period at 0, 24, and 48 hours. To assay baboon plasma LBP levels, an enzyme-linked immunosorbent assay with cross-reactive antibodies to human LBP was developed. Control baboon plasma LBP concentrations were 2 to 5 microg/mL. During experimental sepsis, baboon plasma LBP levels increased to between 200 and 350 microg/mL and in parallel with the increase in C-reactive protein levels. Baboon LBP was isolated from acute phase serum by ion-exchange chromatography followed by immuno-affinity chromatography. Its NH2-terminal sequence (XNPGLVARTTNKGLEYSAQE) and its molecular weight (approximately 60 kd) were determined and were proved to be highly homologous to human LBP.

Acute-Phase Proteins↗

PubMed2001

Amniotic fluid lipopolysaccharide-binding protein and soluble CD14 as mediators of the inflammatory response in preterm labor.

OBJECTIVE: Our purpose was to determine the association of lipopolysaccharide-binding protein (LBP) and soluble CD14 (sCD14) with the proinflammatory response among women in preterm labor. The binding of lipopolysaccharide (LPS) with LBP and sCD14 activates macrophages at LPS concentrations up to 1000 times lower than required with LPS alone. LBP and sCD14 in amniotic fluid could explain the high concentrations of cytokines present in the amniotic fluid of culture-positive women and the presence of cytokines in the amniotic fluid of culture-negative women. STUDY DESIGN: A cohort of 169 afebrile women in preterm labor with intact membranes had amniotic fluid collected by transabdominal amniocentesis for culture and for LBP, sCD14, and interleukin 6 (IL-6) determinations by enzyme-linked immunosorbent assay. IL-6 levels of >2 ng/mL were considered elevated. Statistical analyses included analysis of variance, multiple comparisons with Bonferroni correction, and linear regression. RESULTS: All 169 amniotic fluid samples had measurable LBP and sCD14. Subjects were categorized by amniotic fluid culture results and IL-6 concentration into 3 groups: (1) positive amniotic fluid culture, (2) negative amniotic fluid culture, elevated IL-6 concentration, and (3) negative amniotic fluid culture, low IL-6 level. Geometric mean LBP and sCD14 levels differed significantly among groups such that levels were approximately twice as high among pregnancies with positive amniotic fluid culture or elevated IL-6 compared with those without evidence of inflammation (both P <.001). sCD14 was inversely associated with enrollment gestational age independent of amniotic fluid culture results and IL-6 concentrations. Among culture negative, low IL-6 pregnancies, sCD14 decreased 3.5% for each additional week of gestation (95% confidence interval [CI], 0.01%-6.4%; P =.02). LBP levels showed a similar trend in this group (P =.09). One hundred eleven subjects had detectable IL-6 levels. Among these subjects, IL-6 increased by 2.1-fold for every 10-fold increase in LBP (95% CI, 1.1-4.0; P =.02) and by 28.4-fold for every 10-fold increase in sCD14 (95% CI, 10.4-77.4; P <.001) with adjustment for gestational age by linear regression. CONCLUSIONS: LBP and sCD14 are present in amniotic fluid of preterm pregnancies and are linearly associated with amniotic fluid IL-6 concentrations. These molecules may amplify the cytokine response and thereby help explain the presence of cytokines in amniotic fluid when culturable quantities of microbes are absent.

Acute-Phase Proteins↗

PubMed1990

Suppression of T-cell proliferation by Mycobacterium leprae and its products: the role of lipopolysaccharide.

Addition of soluble molecules obtained from sonicated Mycobacterium leprae markedly suppressed the proliferative response to the mitogen anti-CD3 of peripheral blood mononuclear cells and isolated T cells. Suppression was nonspecific and occurred with cells from lepromatous and tuberculoid leprosy patients as well as control donors. The purified lipoarabinomannans from M. leprae and Mycobacterium tuberculosis had a similar spectrum of inhibition whereas their deacylated derivatives were without effect. All mycobacterial preparations of either a crude or purified state, which suppressed cellular responses, contained appreciable quantities of bacterial lipopolysaccharide by the Limulus amebocyte assay. Contamination with lipopolysaccharide could account for the extent and nonselectivity of the T-cell suppression. Suppression was also monocyte-dependent and in part due to the release of arachidonate metabolites of the cyclooxygenase pathway.

Antibodies, Monoclonal↗

PubMed1995

A region of human CD14 required for lipopolysaccharide binding.

CD14, a glycosylphosphatidylinositol-anchored protein on the surface of monocytes, macrophages, and polymorphonuclear leukocytes, is a receptor for lipopolysaccharide (LPS). CD14 binding of LPS is enhanced by serum proteins, especially lipopolysaccharide binding protein. The serum-dependent binding of LPS to CD14 stimulates macrophages to make cytokines, which can cause septic shock in humans and animals. Here, we identify a region in human CD14 which is important in serum-dependent LPS binding and LPS-induced cellular activation. Four small regions (4-5 amino acids long) within the N-terminal 65 amino acids of CD14 were deleted singly or in combination. The deletion mutants were stably expressed in Chinese hamster ovary (CHO) cells. The mutants were characterized in three assays: reactivity with anti-CD14 monoclonal antibody, serum-dependent LPS binding, and LPS-induced activation of NF-kappa B. Some of the mutants selectively lost reactivity with the anti-CD14 monoclonal antibody that inhibited serum-dependent LPS binding and cellular activation. All of the mutants bound much less LPS than wild type CD14 in the presence of serum. None of the mutants bound more LPS than control CD14-CHO cells in the absence of serum. CD14-CHO cells respond to LPS by activation of NF-kappa B. All of the deletion mutants were less active LPS receptors than wild type CD14-CHO cells. The delta AVEVE mutant, the delta DDED and delta PQPD double mutant, and the delta DDED, delta PQPD, delta AVEVE, and delta DPRQY quadruple deletion mutants were essentially inactive LPS receptors in CHO cells. These studies suggest that the 65 N-terminal amino acids of CD14 are critical for serum-dependent binding of LPS to CD14 and subsequent signal transduction in CHO cells.

Amino Acid Sequence↗

PubMed1996

Neutralization and transfer of lipopolysaccharide by phospholipid transfer protein.

Phospholipid transfer protein (PLTP) and lipopolysaccharide-binding protein (LPB) are lipid transfer proteins found in human plasma. PLTP shares 24% sequence similarity with LBP. PLTP mediates the transfer and exchange of phospholipids between lipoprotein particles, whereas LBP transfers bacterial lipopolysaccharide (LPS) either to lipoprotein particles or to CD14, a soluble and cell-surface receptor for LPS. We asked whether PLTP could interact with LPS and mediate the transfer of LPS to lipoproteins or to CD14. PLTP was able to bind and neutralize LPS: incubation of LPS with purified recombinant PLTP (rPLTP) resulted in the inhibition of the ability of LPS to stimulate adhesive responses of neutrophils, and addition of rPLTP to blood inhibited cytokine production in response to LPS. Transfer of LPS by rPLTP was examined using fluorescence dequenching experiments and native gel electrophoresis. The results suggested that rPLTP was able to mediate the exchange of LPS between micelles and the transfer of LPS to reconstituted HDL particles, but it did not transfer LPS to CD14. Consonant with these findings, rPLTP did not mediate CD14-dependent adhesive responses of neutrophils to LPS. These results suggest that while PLTP and LBP both bind and transfer LPS, PLTP is unable to transfer LPS to CD14 and thus does not mediate responses of cells to LPS.

Boron Compounds↗

PubMed1999

Membrane expression of soluble endotoxin-binding proteins permits lipopolysaccharide signaling in Chinese hamster ovary fibroblasts independently of CD14.

The activation of phagocytes by lipopolysaccharide (LPS) has been implicated in the pathogenesis of Gram-negative sepsis. Although the interaction between CD14 and LPS is a key event in the signaling cascade, the molecular mechanism by which cellular activation occurs remains obscure. We hypothesized that the main function of CD14 was to bind LPS and transfer it to a second receptor, which then initiates the subsequent signal for cellular activation. Thus, surface binding of LPS to the cell membrane would be the critical step that CD14 carries out. To test this hypothesis, we examined the activity of two other proteins known to bind LPS, lipopolysaccharide-binding protein and bactericidal/permeability-increasing protein. We found that when these normally soluble proteins were expressed in Chinese hamster ovary-K1 fibroblasts as glycosylphosphatidylinositol-anchored proteins, both could substitute for CD14 in initiating LPS signaling. Pharmacological studies with synthetic lipid A analogues demonstrated that these surface expressed LPS-binding proteins had characteristics that were qualitatively identical to membrane CD14. These data support the hypothesis that a receptor distinct from CD14 functions as the actual signal transducer and suggest that surface binding of LPS to the cell membrane is the crucial first step for initiating downstream signaling events.

Amino Acid Sequence↗

PubMed2005

Lipopolysaccharide binding protein/CD14/ TLR4-dependent recognition of salmonella LPS induces the functional activation of chicken heterophils and up-regulation of pro-inflammatory cytokine and chemokine gene expression in these cells.

Lipopolysaccharide (LPS) is the major pathogen-associated molecular pattern (PAMP) found in the cell wall of gram-negative bacteria and, in mammals, is recognized by the Toll-like receptor 4 (TLR4) in conjunction with the serum protein, lipopolysaccharide-binding protein (LBP), and the CD14 co-receptor. We have found that chicken heterophils constitutively express multiple TLRs including TLR4. Interestingly, ultrapure LPS from Salmonella minnesota directly induced the functional activation of heterophils without the presence of LBP. However, the role of LBP and CD14 in the recognition of LPS and the induction of innate immunity, including cellfunctional activation and the transcription of cytokine and chemokine genes in chicken heterophils, is not known. As previously seen, in the absence of chicken serum, heterophil exposure to ultrapure LPS from Salmonella minnesota stimulated an increased degranulation response. However, the presence of 5% chicken serum, presumed to be a source of LBP, increased heterophil degranulation by 84%. In addition, the presence of either soluble recombinant human LBP (rhLBP, 68%) or CD14 (39%) also induced the up-regulation of the heterophil degranulation response. Incubation of heterophils with either chicken serum or rhLBP also significantly induced the up-regulation of pro-inflammatory cytokine (IL-1beta, IL-6, and IL-18) and chemokine (CCLi4, CXCLi1, CXCLi2, and the CXC receptor 1) mRNA expression. Moreover, polyclonal antibodies directed against rat CD14 and human TLR4, but not antibodies against human TLR2, blocked LPS-mediated degranulation and up-regulation of the pro-inflammatory cytokine and chemokine mRNA expression. These data clearly demonstrate that LBP and CD14/TLR4 engagement is directly involved in LPS-mediated functional activation and innate immune gene expression in chicken heterophils.

Animals↗