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Bastos PAD, Wheeler R, Boneca IG. Uptake, recognition and responses to peptidoglycan in the mammalian host. FEMS Microbiol Rev 2021; 45:5902851. [PMID: 32897324 PMCID: PMC7794044 DOI: 10.1093/femsre/fuaa044] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/03/2020] [Indexed: 12/13/2022] Open
Abstract
Microbiota, and the plethora of signalling molecules that they generate, are a major driving force that underlies a striking range of inter-individual physioanatomic and behavioural consequences for the host organism. Among the bacterial effectors, one finds peptidoglycan, the major constituent of the bacterial cell surface. In the steady-state, fragments of peptidoglycan are constitutively liberated from bacterial members of the gut microbiota, cross the gut epithelial barrier and enter the host system. The fate of these peptidoglycan fragments, and the outcome for the host, depends on the molecular nature of the peptidoglycan, as well the cellular profile of the recipient tissue, mechanism of cell entry, the expression of specific processing and recognition mechanisms by the cell, and the local immune context. At the target level, physiological processes modulated by peptidoglycan are extremely diverse, ranging from immune activation to small molecule metabolism, autophagy and apoptosis. In this review, we bring together a fragmented body of literature on the kinetics and dynamics of peptidoglycan interactions with the mammalian host, explaining how peptidoglycan functions as a signalling molecule in the host under physiological conditions, how it disseminates within the host, and the cellular responses to peptidoglycan.
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Affiliation(s)
- Paulo A D Bastos
- Institut Pasteur, Biology and genetics of the bacterial cell wall Unit, 25-28 rue du Docteur Roux, Paris 75724, France; CNRS, UMR 2001 "Microbiologie intégrative et moléculaire", Paris 75015, France.,Université de Paris, Sorbonne Paris Cité, 12 rue de l'Ecole de Médecine, 75006, Paris, France
| | - Richard Wheeler
- Institut Pasteur, Biology and genetics of the bacterial cell wall Unit, 25-28 rue du Docteur Roux, Paris 75724, France; CNRS, UMR 2001 "Microbiologie intégrative et moléculaire", Paris 75015, France.,Tumour Immunology and Immunotherapy, Institut Gustave Roussy, 114 rue Edouard-Vaillant, Villejuif 94800, France; INSERM UMR 1015, Villejuif 94800, France
| | - Ivo G Boneca
- Institut Pasteur, Biology and genetics of the bacterial cell wall Unit, 25-28 rue du Docteur Roux, Paris 75724, France; CNRS, UMR 2001 "Microbiologie intégrative et moléculaire", Paris 75015, France
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High Mobility Group Box 1 in Pig Amniotic Membrane Experimentally Infected with E. coli O55. Biomolecules 2021; 11:biom11081146. [PMID: 34439812 PMCID: PMC8393629 DOI: 10.3390/biom11081146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/27/2021] [Accepted: 07/29/2021] [Indexed: 12/15/2022] Open
Abstract
Intra-amniotic infections (IAI) are one of the reasons for preterm birth. High mobility group box 1 (HMGB1) is a nuclear protein with various physiological functions, including tissue healing. Its excessive extracellular release potentiates inflammatory reaction and can revert its action from beneficial to detrimental. We infected the amniotic fluid of a pig on the 80th day of gestation with 1 × 104 colony forming units (CFUs) of E. coli O55 for 10 h, and evaluated the appearance of HMGB1, receptor for glycation endproducts (RAGE), and Toll-like receptor (TLR) 4 in the amniotic membrane and fluid. Sham-infected amniotic fluid served as a control. The expression and release of HMGB1 were evaluated by Real-Time PCR, immunofluorescence, immunohistochemistry, and ELISA. The infection downregulated HMGB1 mRNA expression in the amniotic membrane, changed the distribution of HMGB1 protein in the amniotic membrane, and increased its level in amniotic fluid. All RAGE mRNA, protein expression in the amniotic membrane, and soluble RAGE level in the amniotic fluid were downregulated. TLR4 mRNA and protein expression and soluble TLR4 were all upregulated. HMGB1 is a potential target for therapy to suppress the exaggerated inflammatory response. This controlled expression and release can, in some cases, prevent the preterm birth of vulnerable infants. Studies on suitable animal models can contribute to the development of appropriate therapy.
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Armaroli G, Verweyen E, Pretzer C, Kessel K, Hirono K, Ichida F, Okabe M, Cabral DA, Foell D, Brown KL, Kessel C. Monocyte-Derived Interleukin-1β As the Driver of S100A12-Induced Sterile Inflammatory Activation of Human Coronary Artery Endothelial Cells: Implications for the Pathogenesis of Kawasaki Disease. Arthritis Rheumatol 2019; 71:792-804. [PMID: 30447136 DOI: 10.1002/art.40784] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 11/13/2018] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Kawasaki disease (KD) is an acute vasculitis of childhood, predominantly affecting the coronary arteries. S100A12, a granulocyte-derived agonist of both the receptor for advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR-4), is strongly up-regulated in KD. This study was undertaken to investigate the potential contributions of S100A12 to the pathogenesis of KD. METHODS Serum samples from patients with KD (n = 30) at different stages pre- and post-intravenous immunoglobulin (IVIG) treatment were analyzed for the expression of S100A12, cytokines, chemokines, and soluble markers of endothelial cell activation. Primary human coronary artery endothelial cells (HCAECs) were analyzed for responsiveness to direct stimulation with S100A12 or lipopolysaccharide (LPS), as assessed by real-time quantitative reverse transcription-polymerase chain reaction analysis of cytokine and endothelial cell adhesion molecule messenger RNA expression. Alternatively, HCAECs were cultured in conditioned medium obtained from primary human monocytes that were stimulated with LPS or S100A12 in the absence or presence of IVIG or cytokine antagonists. RESULTS In the serum of patients with KD, pretreatment S100A12 levels were associated with soluble vascular cell adhesion molecule 1 titers in the course of IVIG therapy (rs = -0.6, P = 0.0003). Yet, HCAECs were not responsive to direct S100A12 stimulation, despite the presence of appropriate receptors (RAGE, TLR-4). HCAECs did, however, respond to supernatants obtained from S100A12-stimulated primary human monocytes, as evidenced by the gene expression of inflammatory cytokines and adhesion molecules. This response was strictly dependent on interleukin-1β (IL-1β) signaling (P < 0.001). CONCLUSION In its role as a highly expressed mediator of sterile inflammation in KD, S100A12 appears to activate HCAECs in an IL-1β-dependent manner. These data provide new mechanistic insights into the contributions of S100A12 and IL-1β to disease pathogenesis, and may therefore support current IL-1-targeting studies in the treatment of patients with KD.
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Affiliation(s)
| | | | | | | | | | | | - Mako Okabe
- University of Toyama, Toyama City, Japan
| | - David A Cabral
- University of British Columbia, British Columbia Children's Hospital, Vancouver, British Columbia, Canada
| | - Dirk Foell
- University Children's Hospital, Munster, Germany
| | - Kelly L Brown
- University of British Columbia, British Columbia Children's Hospital, Vancouver, British Columbia, Canada
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Abstract
Many LPS binding proteins have been described, but the exact nature of the LPS receptors that signal cells remains unclear. MD-2 is a molecule that is found in association with Toll-like receptor 4, which has been shown to be a receptor for LPS. We have produced human MD-2 in baculovirus and tested it for LPS binding. MD-2 binds the lipid A region of LPS without the need for LPS binding protein. These data suggest that MD-2 may be binding LPS as part of the TLR4 receptor complex.
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Affiliation(s)
- S. Viriyakosol
- Department of Pathology and Medicine, Department of Veterans Affairs Medical Center, University of California San Diego, San Diego, California, USA
| | - T.N. Kirkland
- Department of Pathology and Medicine, Department of Veterans Affairs Medical Center, University of California San Diego, San Diego, California, USA
| | - K. Soldau
- Department of Immunology, The Scripps Research Institute, La Jolla, California, USA
| | - P.S. Tobias
- Department of Immunology, The Scripps Research Institute, La Jolla, California, USA
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5
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Zschemisch NH, Brüsch I, Hambusch AS, Bleich A. Transcription Factor SP2 Enhanced the Expression of Cd14 in Colitis-Susceptible C3H/HeJBir. PLoS One 2016; 11:e0155821. [PMID: 27191968 PMCID: PMC4871554 DOI: 10.1371/journal.pone.0155821] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 05/04/2016] [Indexed: 01/19/2023] Open
Abstract
Genetic analysis in the IL10-deficient mouse model revealed a modifier locus of experimental inflammatory bowel disease (IBD) on chromosome 18, with the allele of the strain C3H/HeJBir (C3Bir) conferring resistance and the allele of C57BL/6J (B6) conferring susceptibility. Differential Cd14 expression was associated with this background specific susceptibility to intestinal inflammation. Polymorphisms of the Cd14 promoter were found to be likely causative for strain specific expression, and Cd14-knockout mice revealed a protective role of this gene-product in experimental IBD. In this study, luciferase reporter assays confirmed an increased activity of the C3Bir derived Cd14 promoter compared to the one of B6. Promoter truncation experiments and site-directed mutagenesis in both strains resulted in reduced Cd14 promoter activity and confirmed that a central AP1 and the proximal SP1 transcription factor binding sites mediated the basal activity of the Cd14 promoter in the mouse. Moreover, a T to C exchange at position -259 replaced putative STAT1 and CDX1 sites in the Cd14 promoter from B6 by a SP2 site in C3Bir. Ablation of the Sp2 site through truncation was associated with a decreased promoter activity. Site-directed mutagenesis also demonstrated that the inactivation of SP2 led to a substantial loss of promoter activity in C3Bir. Performing electrophoretic mobility shift and supershift assays demonstrated interaction of SP2 with its potential binding site. In addition, retroviral—mediated overexpression of the SP2 transcription factor in primary bone marrow macrophages derived from C3Bir mice caused a significant increase in Cd14 transcription. These data characterized SP2 as important factor responsible for higher Cd14 expression and reduced IBD susceptibility mediated by the C3Bir allele.
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Affiliation(s)
- Nils-Holger Zschemisch
- Institute for Laboratory Animal Science and Central Animal Facility, Hannover Medical School, Hannover, Germany
| | - Inga Brüsch
- Institute for Laboratory Animal Science and Central Animal Facility, Hannover Medical School, Hannover, Germany
| | - Anne-Sophie Hambusch
- Institute for Laboratory Animal Science and Central Animal Facility, Hannover Medical School, Hannover, Germany
| | - André Bleich
- Institute for Laboratory Animal Science and Central Animal Facility, Hannover Medical School, Hannover, Germany
- * E-mail:
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Kim SM, Kim BY, Eo SK, Kim CD, Kim K. 27-Hydroxycholesterol up-regulates CD14 and predisposes monocytic cells to superproduction of CCL2 in response to lipopolysaccharide. Biochim Biophys Acta Mol Basis Dis 2015; 1852:442-50. [DOI: 10.1016/j.bbadis.2014.12.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 12/01/2014] [Accepted: 12/03/2014] [Indexed: 11/16/2022]
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7
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Ning BT, Tang YM. Establishment of the cell line, HeLa-CD14, transfected with the human CD14 gene. Oncol Lett 2012; 3:871-874. [PMID: 22741009 DOI: 10.3892/ol.2012.557] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/23/2011] [Indexed: 11/06/2022] Open
Abstract
CD14 is the pivotal molecule in the diagnosis and therapy of CD14-associated diseases, and is important in bacteremia. The HeLa cell line is regarded as immortal due to its prolific character. The HeLa cell line is derived from human cervical cancer cells and has been widely used in cancer research and gene transfection. In the present study, we established the expression plasmid pcDNA3.1(+)-CD14, and transfected it into the human cervical cancer cell line HeLa to establish a stable cell line (HeLa-CD14) expressing human CD14 antigen on the membrane. After the human CD14 gene was cloned and sequenced through RT-PCR and T-A cloning techniques, the eukaryotic expression vector pcDNA3.1(+)-CD14 was constructed by cleaving with double restriction endonucleases and ligating with T4 ligase. HeLa cells were transfected with the pcDNA3.1(+)-CD14 recombinant plasmid using Superfect transfection reagent. The cells were selected using G418 and the expression of human CD14 on the transfectant was confirmed by RT-PCR and immunohistochemistry. The expression of CD14 mRNA was significantly different between the blank pcDNA3.1(+)-transfected cell group and the pcDNA3.1(+)-CD14-transfected cell group (p<0.01). The fluorescence was significantly stronger on the established stable cell line than on the transiently transfected HeLa cells, and no visible fluorescence was observed in blank pcDNA3.1(+)-transfected cells. In this study, the human CD14 transfectant, stable cell line HeLa-CD14, was successfully established, which may be used to study CD14 and cervical cancer in vitro and in vivo.
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Affiliation(s)
- Bo-Tao Ning
- Division of Hematology-Oncology, The Children's Hospital of Zhejiang University School of Medicine,Hangzhou 310003, P.R. China
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Boltaña S, Reyes-Lopez F, Morera D, Goetz F, MacKenzie SA. Divergent responses to peptidoglycans derived from different E. coli serotypes influence inflammatory outcome in trout, Oncorhynchus mykiss, macrophages. BMC Genomics 2011; 12:34. [PMID: 21235753 PMCID: PMC3087353 DOI: 10.1186/1471-2164-12-34] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 01/14/2011] [Indexed: 12/24/2022] Open
Abstract
Background Pathogen-associated molecular patterns (PAMPs) are structural components of pathogens such as lipopolysaccharide (LPS) and peptidoglycan (PGN) from bacterial cell walls. PAMP-recognition by the host results in an induction of defence-related genes and often the generation of an inflammatory response. We evaluated both the transcriptomic and inflammatory response in trout (O. mykiss) macrophages in primary cell culture stimulated with DAP-PGN (DAP; meso-diaminopimelic acid, PGN; peptidoglycan) from two strains of Escherichia coli (PGN-K12 and PGN-O111:B4) over time. Results Transcript profiling was assessed using function-targeted cDNA microarray hybridisation (n = 36) and results show differential responses to both PGNs that are both time and treatment dependent. Wild type E. coli (K12) generated an increase in transcript number/diversity over time whereas PGN-O111:B4 stimulation resulted in a more specific and intense response. In line with this, Gene Ontology analysis (GO) highlights a specific transcriptomic remodelling for PGN-O111:B4 whereas results obtained for PGN-K12 show a high similarity to a generalised inflammatory priming response where multiple functional classes are related to ribosome biogenesis or cellular metabolism. Prostaglandin release was induced by both PGNs and macrophages were significantly more sensitive to PGN-O111:B4 as suggested from microarray data. Conclusion Responses at the level of the transcriptome and the inflammatory outcome (prostaglandin synthesis) highlight the different sensitivity of the macrophage to slight differences (serotype) in peptidoglycan structure. Such divergent responses are likely to involve differential receptor sensitivity to ligands or indeed different receptor types. Such changes in biological response will likely reflect upon pathogenicity of certain serotypes and the development of disease.
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Affiliation(s)
- Sebastian Boltaña
- Institute of Biotechnology and Biomedicine, Universitat Autónoma de Barcelona, 08193 Barcelona, Spain
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Kövér KE, Szilágyi L, Batta G, Uhrín D, Jiménez-Barbero J. Biomolecular Recognition by Oligosaccharides and Glycopeptides: The NMR Point of View. COMPREHENSIVE NATURAL PRODUCTS II 2010:197-246. [DOI: 10.1016/b978-008045382-8.00193-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
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Aalto H, Takala A, Kautiainen H, Siitonen S, Repo H. Monocyte CD14 and soluble CD14 in predicting mortality of patients with severe community acquired infection. ACTA ACUST UNITED AC 2009; 39:596-603. [PMID: 17577824 DOI: 10.1080/00365540701199808] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Monocyte membrane CD14 (mCD14) and soluble CD14 (sCD14) both associate with poor outcome in sepsis. Because the value of combined use of the markers is unknown we measured both in patients with severe community acquired infections. The study comprised 142 acutely ill patients with community acquired pneumonia and/or blood culture-positive sepsis. Expression of mCD14 was measured, on admission to hospital, by whole blood flow cytometry and sCD14 by ELISA. There was no significant correlation between mCD14 and sCD14. Patients in the lowest tertile of mCD14 were 9.79 times (95% CI 1.31- >50, p =0.006) more likely to die than patients in the middle/highest tertiles. Survival rates in the highest and middle/lowest tertiles of sCD14 levels were comparable. After stratification by sCD14, patients in the lowest tertile of mCD14 were 14.4 times (95% CI 1.90-39.44) more likely to die than patients in the middle/highest tertiles. A significant positive correlation was detected between C-reactive protein and sCD14 levels, providing evidence that sCD14 may serve as an acute phase reactant. In conclusion, low monocyte mCD14 level, unlike the concurrent sCD14 level, predicts 28-d mortality in patients with community acquired infections.
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Affiliation(s)
- Hannele Aalto
- Department of Bacteriology and Immunology, The Haartman Institute, University of Helsinki, Finland.
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11
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NMR spectral mapping of Lipid A molecular patterns affected by interaction with the innate immune receptor CD14. Biochem Biophys Res Commun 2009; 378:721-6. [DOI: 10.1016/j.bbrc.2008.11.113] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 11/19/2008] [Indexed: 11/20/2022]
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12
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McGreal EP. Structural basis of pattern recognition by innate immune molecules. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 653:139-61. [PMID: 19799117 DOI: 10.1007/978-1-4419-0901-5_10] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The importance of the innate immune system as a first line defence against pathogenic challenge has long been recognised. Over the last decade the identity of many of the key molecules mediating innate host defence have been clarified and a model of self/ nonself discrimination by families of pattern recognition receptors (PRRs) has emerged. Although a large amount of information is now available concerning the action of these innate immune molecules at the level of the cell and organism, little is known about the molecular interface between pathogens and innate immune recognition molecules. In this chapter the molecular basis for innate immune discrimination of a wide variety of pathogen derived molecules is discussed in the context of the emerging literature.
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Affiliation(s)
- Eamon P McGreal
- Department of Child Health, Cardiff University School of Medicine, Heath Park, Cardiff, UK.
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13
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Albright S, Chen B, Holbrook K, Jain NU. Solution NMR studies provide structural basis for endotoxin pattern recognition by the innate immune receptor CD14. Biochem Biophys Res Commun 2008; 368:231-7. [PMID: 18230335 DOI: 10.1016/j.bbrc.2008.01.085] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2008] [Accepted: 01/14/2008] [Indexed: 11/29/2022]
Abstract
CD14 functions as a key pattern recognition receptor for a diverse array of Gram-negative and Gram-positive 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 15N isotopically labeled 152-residue N-terminal 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.
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Affiliation(s)
- Seth Albright
- Biochemistry, Cellular and Molecular Biology Department, University of Tennessee, M407 Walters Life Sciences, 1410 Cumberland Avenue, Knoxville, TN 37996-0840, USA
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14
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Zhao Z, Fleming R, McCloud B, Klempner MS. CD14 mediates cross talk between mononuclear cells and fibroblasts for upregulation of matrix metalloproteinase 9 by Borrelia burgdorferi. Infect Immun 2007; 75:3062-9. [PMID: 17403874 PMCID: PMC1932873 DOI: 10.1128/iai.00202-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lyme disease is an infection caused by a tick-borne spirochete, Borrelia burgdorferi. Matrix metalloproteinase 9 (MMP-9) was selectively upregulated in the erythema migrans skin lesions of patients with acute Lyme disease. In this study, the mechanism of upregulation of MMP-9 was investigated in vitro and in vivo. The concentrations of MMP-9 and soluble CD14 were markedly elevated in serum from patients with acute Lyme disease and were also upregulated in U937 cells by B. burgdorferi in a time- and concentration-dependent manner. MMP-9 mRNA was expressed at baseline in fibroblasts in the presence or absence of B. burgdorferi. However, when fibroblasts were incubated with supernatants from U937 cells with B. burgdorferi or recombinant CD14, the expression of MMP-9 was significantly increased. This effect was completely abolished by the anti-CD14 antibody. These data suggest that the upregulation of MMP-9 by B. burgdorferi involves the CD14 pathway in infiltrating inflammatory cells. Fibroblasts could be recruited to amplify local production of MMP-9 by acquiring CD14 from macrophages.
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Affiliation(s)
- Zhihui Zhao
- Boston Medical Center, 650 Albany Street, Boston, MA 02118, USA.
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15
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Royet J, Dziarski R. Peptidoglycan recognition proteins: pleiotropic sensors and effectors of antimicrobial defences. Nat Rev Microbiol 2007; 5:264-77. [PMID: 17363965 DOI: 10.1038/nrmicro1620] [Citation(s) in RCA: 281] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Peptidoglycan recognition proteins (PGRPs) are innate immunity molecules that are present in most invertebrate and vertebrate animals. All PGRPs function in antimicrobial defence and are homologous to the prokaryotic peptidoglycan-lytic type 2 amidases. However, only some PGRPs have the catalytic activity that protects the host from excessive inflammation, and most PGRPs have diversified to carry out other host-defence functions. Insect and mammalian PGRPs defend host cells against infection through very different mechanisms. Insect PGRPs activate signal transduction pathways in host cells or trigger proteolytic cascades in the haemolymph, both of which generate antimicrobial effectors. By contrast, mammalian PGRPs are directly bactericidal. Here, we review these contrasting modes of action.
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Affiliation(s)
- Julien Royet
- Institut de Biologie du Développement de Marseille-Luminy, UMR 6216 CNRS, Université de la Méditérannée Aix-Marseille II, Marseille, France.
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16
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Wiertsema SP, Khoo SK, Baynam G, Veenhoven RH, Laing IA, Zielhuis GA, Rijkers GT, Goldblatt J, Lesouëf PN, Sanders EAM. Association of CD14 promoter polymorphism with otitis media and pneumococcal vaccine responses. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2006; 13:892-7. [PMID: 16893989 PMCID: PMC1539116 DOI: 10.1128/cvi.00100-06] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Innate immunity is of particular importance for protection against infection during early life, when adaptive immune responses are immature. CD14 plays key roles in innate immunity, including in defense against pathogens associated with otitis media, a major pediatric health care issue. The T allele of the CD14 C-159T polymorphism has been associated with increased serum CD14 levels. Our objective was to investigate the hypothesis that the CD14 C-159T allele is protective against recurrent acute otitis media in children. The association between the CD14 promoter genotype and the number of acute otitis media episodes was evaluated both retrospectively and prospectively in a cohort of 300 children. Serotype-specific immunoglobulin G (IgG) antibody responses after pneumococcal vaccinations were examined according to CD14 genotype to compare immune responsiveness across genotypes. An age-dependent association was found: compared with that for CC homozygotes aged between 12 to 24 months, TT homozygotes had fewer episodes of acute otitis media (79 versus 41%, respectively; P = 0.004); this relationship was absent in older children. Additionally, TT homozygotes showed higher serotype-specific anti-pneumococcal IgG antibody levels. Our data suggest that genetic variation in CD14, a molecule at the interface of innate and adaptive immune responses, plays a key role in the defense against middle ear disease in childhood and in pneumococcal vaccine responsiveness. These findings are likely to be important to these and other immune-mediated outcomes in early life.
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Affiliation(s)
- S P Wiertsema
- Department of Pediatric Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
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Abstract
Studies aimed at dissecting the complex pathophysiology of sepsis with multiple organ failure have traditionally focused on lipopolysaccharide of gram-negative bacteria, which is widely regarded as the classical endotoxin. However, gram-positive sepsis now accounts for up to 50% of all cases, calling for a shift of focus. Peptidoglycan (PepG) is the major cell wall component of gram-positive bacteria and has been increasingly recognized as an important proinflammatory molecule. During gram-positive infections, PepG reaches the circulation by bacterial breakdown or translocation from the intestine. Administration of PepG induces all the classical features of infectious illness and endotoxemia and may cause systemic inflammation with organ failure in animal models. Its potency, however, is crucially dependent on various features of its complex structure. PepG interacts with the innate immune system through receptors mainly expressed on monocytes/macrophages but may induce inflammatory changes in other cell types as well. Among the most extensively studied receptor systems are the nucleotide-binding oligomerization domains, the toll-like receptors, and the PepG recognition proteins. Based on the current available literature, we would like to propose that PepG must be regarded as an endotoxin in its own right and to encourage further work in the field of PepG signaling.
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Affiliation(s)
- Anders E Myhre
- University of Oslo, Faculty Division Rikshospitalet, Institute for Surgical Research, Oslo, Norway
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Esen N, Kielian T. Recognition of Staphylococcus aureus-derived peptidoglycan (PGN) but not intact bacteria is mediated by CD14 in microglia. J Neuroimmunol 2005; 170:93-104. [PMID: 16229899 PMCID: PMC2376817 DOI: 10.1016/j.jneuroim.2005.09.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Accepted: 09/08/2005] [Indexed: 11/29/2022]
Abstract
Recognition of Staphylococcus aureus and its cell-wall component peptidoglycan (PGN) by microglia is mediated, in part, by Toll-like receptor 2 (TLR2). However, the pattern recognition receptor (PRR) CD14 can also bind PGN and enhance TLR2-mediated signaling in macrophages, suggesting a similar phenomenon might occur in microglia. To assess the functional significance of CD14 on microglial activation, we evaluated the responses of primary microglia isolated from CD14 knockout (KO) and wild type (WT) mice. PGN-dependent microglial activation was partially CD14-dependent as demonstrated by the attenuated expression of TNF-alpha, macrophage inflammatory protein-2 (MIP-2/CXCL2), and the soluble PRR pentraxin-3 in CD14 KO microglia compared to WT cells. In contrast, microglial responses to intact S. aureus occurred primarily via a CD14-independent manner. Collectively, these findings reveal the complex nature of gram-positive bacterial recognition by microglia, which occurs, in part, via CD14.
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Affiliation(s)
| | - Tammy Kielian
- * Corresponding author. Tel.: +1 501 526 6348; fax: +1 501 526 6756.E-mail address: (T. Kielian)
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19
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Abstract
CD14 is a pattern recognition receptor; its important role in innate immunity is reviewed here. Since its discovery and subsequent classification at the first leucocyte typing workshop in 1982, CD14 has been thought of as a leucocyte differentiation antigen. However, it has become clear that CD14 is also expressed by many non-myeloid cells, and the evidence for this is presented. The possible role of the presence of low copy number CD14 on non-myeloid cells is discussed. It is time to acknowledge CD14 as an ubiquitous molecule and abandon the position that it is expressed by myeloid cells alone.
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Affiliation(s)
- Hubertus P A Jersmann
- Lung Research Laboratory, Hanson Institute, University of Adelaide, Adelaide, South Australia, Australia.
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Kim JI, Lee CJ, Jin MS, Lee CH, Paik SG, Lee H, Lee JO. Crystal structure of CD14 and its implications for lipopolysaccharide signaling. J Biol Chem 2005; 280:11347-51. [PMID: 15644310 DOI: 10.1074/jbc.m414607200] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipopolysaccharide, the endotoxin of Gram-negative bacteria, induces extensive immune responses that can lead to fatal septic shock syndrome. The core receptors recognizing lipopolysaccharide are CD14, TLR4, and MD-2. CD14 binds to lipopolysaccharide and presents it to the TLR4/MD-2 complex, which initiates intracellular signaling. In addition to lipopolysaccharide, CD14 is capable of recognizing a few other microbial and cellular products. Here, we present the first crystal structure of CD14 to 2.5 angstroms resolution. A large hydrophobic pocket was found on the NH2-terminal side of the horseshoe-like structure. Previously identified regions involved in lipopolysaccharide binding map to the rim and bottom of the pocket indicating that the pocket is the main component of the lipopolysaccharide-binding site. Mutations that interfere with lipopolysaccharide signaling but not with lipopolysaccharide binding are also clustered in a separate area near the pocket. Ligand diversity of CD14 could be explained by the generous size of the pocket, the considerable flexibility of the rim of the pocket, and the multiplicity of grooves available for ligand binding.
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Affiliation(s)
- Jung-In Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
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Rahman SH, Salter G, Holmfield JHM, Larvin M, McMahon MJ. Soluble CD14 receptor expression and monocyte heterogeneity but not the C-260T CD14 genotype are associated with severe acute pancreatitis. Crit Care Med 2004; 32:2457-63. [PMID: 15599151 DOI: 10.1097/01.ccm.0000148008.99716.9c] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE Soluble CD14 is derived from a membrane glycoprotein, and it enhances endothelial cytokine responses to lipopolysaccharide. We studied the role of soluble CD14 in the pathogenesis of the systemic inflammatory response associated with acute pancreatitis, to determine whether altered expression was due to a functional C-260T polymorphism in the CD14 promoter gene or altered monocyte heterogeneity. DESIGN Prospective case-matched study. SETTING Tertiary pancreatic treatment unit in the United Kingdom. SUBJECTS Patients with pancreatitis and controls. INTERVENTIONS DNA from 117 patients with pancreatitis (34 severe) and 263 controls underwent CD14 genotyping using restriction fragment length polymorphism-polymerase chain reaction. MEASUREMENTS AND MAIN RESULTS Peripheral venous blood samples at 24 and 72 hrs after the onset of abdominal pain were analyzed for sCD14 levels. Isolated peripheral blood mononuclear cells were phenotyped for CD14/CD16 receptor expression using immunofluorescence flow cytometry. Disease severity was assessed using Atlanta criteria, Acute Physiology Scores, and C-reactive protein.Soluble CD14 levels were higher in severe (24-hr median, 66.6 ng/mL; 72-hr median, 72.2 ng/mL) compared with mild attacks (24-hr median, 50.7 ng/mL; 72-hr median, 49.7 ng/mL, p < .001), although the latter was similar to controls (median, 51 ng/mL). Furthermore, soluble CD14 levels correlated with Acute Physiology Scores (p < .001) and C-reactive protein (p = .01).Peripheral blood mononuclear cells CD14++ (p = .008), CD14+/16+ (p = .003), and CD16++ (p = .015) receptor densities were all increased in severe attacks at 24 hrs. Early CD14+/16+ receptor density correlated with sCD14 (p < .001), Acute Physiology Scores (p < .001), and C-reactive protein (p = 0.006). The CD14 genotype prevalence in acute pancreatitis was similar to controls and failed to correlate with any variables studied. CONCLUSIONS Increased soluble CD14 expression is associated with the systemic inflammatory response to acute pancreatitis and an expansion of the proinflammatory CD14+/CD16+ monocyte subset. Its targeted disruption may afford some benefit in preventing the development of systemic complications.
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Affiliation(s)
- Sakhawat H Rahman
- Academic Unit of Surgery, University of Leeds, General Infirmary, Leeds, West Yorkshire, UK
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22
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Opal SM, Palardy JE, Parejo N, Jasman RL. Effect of anti-CD14 monoclonal antibody on clearance of Escherichia coli bacteremia and endotoxemia. Crit Care Med 2003; 31:929-32. [PMID: 12627007 DOI: 10.1097/01.ccm.0000054870.25767.ee] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To determine the effects of an anti-CD14 monoclonal antibody on the clearance of a bacteremic Escherichia coli challenge in the presence or absence of antimicrobial agents. DESIGN Prospective randomized animal study. SETTING University-affiliated research laboratory. SUBJECTS New Zealand White rabbits weighing 1.5-2.5 kg. INTERVENTIONS Animals were pretreated with either an anti-lapine CD14 monoclonal antibody (immunoglobulin G2a, 5 mg/kg intravenously) or an isotype control monoclonal antibody. The animals then were challenged with 1 x 10(6) E. coli 018:K1 in the presence or absence of ceftazidime (50 mg/kg intravenously). There were four groups of six animals randomized to receive either anti-CD14 monoclonal antibody without ceftazidime, isotype control monoclonal antibody without ceftazidime, anti-CD14 monoclonal antibody with ceftazidime, or isotype control antibody with ceftazidime. MEASUREMENTS AND MAIN RESULTS Serial measurement of quantitative bacteremia and endotoxemia was performed over 24 hrs after the administration of the bacterial challenge. Animals also underwent necropsy with quantitative bacterial cultures from multiple organ tissue samples. The anti-lapine CD14 monoclonal antibody significantly impaired the bloodstream clearance of E. coli (p <.01) and increased quantitative counts of E. coli in tissue culture samples when compared with isotype control antibody in the absence of simultaneous administration of ceftazidime. No differences in quantitative bacteremia, endotoxemia, or organ tissue counts were found after anti-CD14 antibody and control antibody-treated animals in the presence of ceftazidime treatment. CONCLUSIONS Anti-CD14 monoclonal antibody has the capacity to interfere with the innate immune response and systemic microbial clearance in experimental animals with E. coli bacteremia. The concomitant administration of effective antimicrobial therapy eliminated differences in the rate of microbial clearance between the control antibody and the CD14 monoclonal antibody. These results indicate that care should be taken in clinical trials with anti-CD14 monoclonal antibodies to ensure that adequate antimicrobial therapy is administered in the presence of systemic bacterial infection.
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Affiliation(s)
- Steven M Opal
- Brown University School of Medicine, Infectious Disease Division, Pawtucket, RI, USA.
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Wilhelm W, Grundmann U, Rensing H, Werth M, Langemeyer J, Stracke C, Dhingra D, Bauer M. Monocyte deactivation in severe human sepsis or following cardiopulmonary bypass. Shock 2002; 17:354-60. [PMID: 12022753 DOI: 10.1097/00024382-200205000-00002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We investigated the specificity for gram-negative stimuli as well as the contribution of signal transduction pathways for leukocyte hyporesponsiveness in sepsis or following cardiopulmonary bypass (CPB). Whole blood of nine patients undergoing CPB and 25 patients with severe sepsis was stimulated ex vivo with LPS (E. coli O111:B4) or with Staphylococcus aureus Cowan strain I (SAC-I) lysate in the absence or presence of inhibitors of protein kinase C (PKC), protein-tyrosine kinase (PTK), or protein-tyrosine phosphatase (PTP). Both toxins stimulated a TNF-alpha response through PTK signaling. Although suppression of the cytokine response was similar for LPS and SAC-I after CPB, it was significantly more pronounced for SAC-I in sepsis. Inhibition of PTP failed to increase TNF-alpha upon LPS, whereas a moderate increase was observed with SAC-I. Impaired TNF-alpha responses occur in sepsis and after CPB. Although this has primarily been reported for gram-negative stimuli, our data suggest that this is even more pronounced for gram-positive stimuli in severe sepsis. Although PTK was the predominant signaling pathway, inhibition of PTP only partially restored the TNF-alpha response to SAC-I. Our results suggest that cellular mechanisms underlying monocyte deactivation are different in sepsis or following CPB and are discriminate for gram-positive and gram-negative toxins.
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Affiliation(s)
- Wolfram Wilhelm
- Department of Anesthesiology and Intensive Care Medicine, University of Saarland, Homburg/Saar, Germany.
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Iovine N, Eastvold J, Elsbach P, Weiss JP, Gioannini TL. The carboxyl-terminal domain of closely related endotoxin-binding proteins determines the target of protein-lipopolysaccharide complexes. J Biol Chem 2002; 277:7970-8. [PMID: 11773072 DOI: 10.1074/jbc.m109622200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bactericidal/permeability increasing (BPI) and lipopolysaccharide (LPS)-binding (LBP) proteins are closely related two-domain proteins in which LPS binding is mediated by the NH(2)-terminal domain. To further define the role of the COOH-terminal domain of these proteins in delivery of LPS to specific host acceptors, we have compared interactions of LBP, BPI, LBP(N)-BPI(C) (NH(2)-terminal domain of LBP, COOH-terminal domain of BPI), and BPI(N)-LBP(C) with purified (3)H-LPS and, subsequently, with purified leukocytes and soluble (s)CD14. The COOH-terminal domain of LBP promotes delivery of LPS to CD14 on both polymorphonuclear leukocytes and monocytes resulting in cell activation. In the presence of Ca(2+) and Mg(2+), LBP and BPI each promote aggregation of LPS to protein-LPS aggregates of increased size (apparent M(r) > 20 x 10(6) Da), but only LPS associated with LBP and BPI(N)-LBP(C) is disaggregated in the presence of CD14. BPI and LBP(N)-BPI(C) promote apparently CD14-independent LPS association to monocytes without cell activation. These findings demonstrate that the carboxyl-terminal domain of these closely related endotoxin-binding proteins dictates the route and host responses to complexes they form with endotoxin.
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Affiliation(s)
- Nicole Iovine
- Department of Medicine, New York University School of Medicine, New York, New York 10016, USA
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Muhvić D, El-Samalouti V, Flad HD, Radosević-Stasić B, Rukavina D. The involvement of CD14 in the activation of human monocytes by peptidoglycan monomers. Mediators Inflamm 2001; 10:155-62. [PMID: 11545252 PMCID: PMC1781699 DOI: 10.1080/09629350123956] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Cell-wall components of Gram-positive and Gram-negative bacteria induce the production of cytokines in human peripheral blood mononuclear cells. These cytokines are the main mediators of local or systemic inflammatory reaction that can contribute to the development of innate immunity. AIMS This study was performed to analyze the involvement of CD14 molecule in the activation of human monocytes by peptidoglycan monomer (PGM) obtained by biosynthesis from culture fluid of penicillin-treated Brevibacterium divaricatum NRLL-2311. METHODS Cytokine release of interleukin (IL)-1, IL-6 and tumor necrosis factor-alpha from human monocytes via soluble CD14 (sCD14) or membrane-associated (mCD14) receptor using anti-CD14 monoclonal antibody (MEM-18) or lipid A structure (compound 406) was measured in bioassays. RESULTS The results demonstrated that PGM in the presence of human serum might induce the monokine release in a dose-dependent manner. The addition of sCD14 at physiologic concentrations enhanced the PGM-induced monokine release, while the monokine inducing capacity of PGM in the presence of sCD14 was inhibited by MEM-18. Effects of PGM were also blocked by glycolipid, compound 406, suggesting the involvement of binding structures similar to those for lipopolysaccharide. CONCLUSION Activation of human monocytes by PGM involves both forms of CD14 molecule, sCD14 and mCD14.
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Affiliation(s)
- D Muhvić
- Department of Physiology and Immunology, Medical Faculty, University of Rijeka, Croatia.
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