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Cetin E, Mazzarino M, González-Mateo GT, Kopytina V, Meran S, Fraser D, López-Cabrera M, Labéta MO, Raby AC. Calprotectin blockade inhibits long-term vascular pathology following peritoneal dialysis-associated bacterial infection. Front Cell Infect Microbiol 2023; 13:1285193. [PMID: 38094743 PMCID: PMC10716465 DOI: 10.3389/fcimb.2023.1285193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 11/02/2023] [Indexed: 12/18/2023] Open
Abstract
Bacterial infections and the concurrent inflammation have been associated with increased long-term cardiovascular (CV) risk. In patients receiving peritoneal dialysis (PD), bacterial peritonitis is a common occurrence, and each episode further increases late CV mortality risk. However, the underlying mechanism(s) remains to be elucidated before safe and efficient anti-inflammatory interventions can be developed. Damage-Associated Molecular Patterns (DAMPs) have been shown to contribute to the acute inflammatory response to infections, but a potential role for DAMPs in mediating long-term vascular inflammation and CV risk following infection resolution in PD, has not been investigated. We found that bacterial peritonitis in mice that resolved within 24h led to CV disease-promoting systemic and vascular immune-mediated inflammatory responses that were maintained up to 28 days. These included higher blood proportions of inflammatory leukocytes displaying increased adhesion molecule expression, higher plasma cytokines levels, and increased aortic inflammatory and atherosclerosis-associated gene expression. These effects were also observed in infected nephropathic mice and amplified in mice routinely exposed to PD fluids. A peritonitis episode resulted in elevated plasma levels of the DAMP Calprotectin, both in PD patients and mice, here the increase was maintained up to 28 days. In vitro, the ability of culture supernatants from infected cells to promote key inflammatory and atherosclerosis-associated cellular responses, such as monocyte chemotaxis, and foam cell formation, was Calprotectin-dependent. In vivo, Calprotectin blockade robustly inhibited the short and long-term peripheral and vascular consequences of peritonitis, thereby demonstrating that targeting of the DAMP Calprotectin is a promising therapeutic strategy to reduce the long-lasting vascular inflammatory aftermath of an infection, notably PD-associated peritonitis, ultimately lowering CV risk.
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Affiliation(s)
- Esra Cetin
- Wales Kidney Research Unit, Division of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Morgane Mazzarino
- Wales Kidney Research Unit, Division of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Guadalupe T. González-Mateo
- Tissue and Organ Homeostasis Program, Centro de Biología Molecular Severo Ochoa – Consejo Superior de Investigaciones Científicas – Universidad Autónoma de Madrid (CBMSO-CSIC-UAM), Madrid, Spain
- Premium Research, S.L., Guadalajara, Spain
| | - Valeria Kopytina
- Tissue and Organ Homeostasis Program, Centro de Biología Molecular Severo Ochoa – Consejo Superior de Investigaciones Científicas – Universidad Autónoma de Madrid (CBMSO-CSIC-UAM), Madrid, Spain
| | - Soma Meran
- Wales Kidney Research Unit, Division of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Donald Fraser
- Wales Kidney Research Unit, Division of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Manuel López-Cabrera
- Tissue and Organ Homeostasis Program, Centro de Biología Molecular Severo Ochoa – Consejo Superior de Investigaciones Científicas – Universidad Autónoma de Madrid (CBMSO-CSIC-UAM), Madrid, Spain
| | - Mario O. Labéta
- Wales Kidney Research Unit, Division of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Anne-Catherine Raby
- Wales Kidney Research Unit, Division of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
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Mazzarino M, Cetin E, Bartosova M, Marinovic I, Ipseiz N, Hughes TR, Schmitt CP, Ramji DP, Labéta MO, Raby AC. Therapeutic targeting of chronic kidney disease-associated DAMPs differentially contributing to vascular pathology. Front Immunol 2023; 14:1240679. [PMID: 37849759 PMCID: PMC10577224 DOI: 10.3389/fimmu.2023.1240679] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 09/08/2023] [Indexed: 10/19/2023] Open
Abstract
Chronic Kidney Disease (CKD) is associated with markedly increased cardiovascular (CV) morbidity and mortality. Chronic inflammation, a hallmark of both CKD and CV diseases (CVD), is believed to drive this association. Pro-inflammatory endogenous TLR agonists, Damage-Associated Molecular Patterns (DAMPs), have been found elevated in CKD patients' plasma and suggested to promote CVD, however, confirmation of their involvement, the underlying mechanism(s), the extent to which individual DAMPs contribute to vascular pathology in CKD and the evaluation of potential therapeutic strategies, have remained largely undescribed. A multi-TLR inhibitor, soluble TLR2, abrogated chronic vascular inflammatory responses and the increased aortic atherosclerosis-associated gene expression observed in nephropathic mice, without compromising infection clearance. Mechanistically, we confirmed elevation of 4 TLR DAMPs in CKD patients' plasma, namely Hsp70, Hyaluronic acid, HMGB-1 and Calprotectin, which displayed different abilities to promote key cellular responses associated with vascular inflammation and progression of atherosclerosis in a TLR-dependent manner. These included loss of trans-endothelial resistance, enhanced monocyte migration, increased cytokine production, and foam cell formation by macrophages, the latter via cholesterol efflux inhibition. Calprotectin and Hsp70 most consistently affected these functions. Calprotectin was further elevated in CVD-diagnosed CKD patients and strongly correlated with the predictor of CV events CRP. In nephropathic mice, Calprotectin blockade robustly reduced vascular chronic inflammatory responses and pro-atherosclerotic gene expression in the blood and aorta. Taken together, these findings demonstrated the critical extent to which the DAMP-TLR pathway contributes to vascular inflammatory and atherogenic responses in CKD, revealed the mechanistic contribution of specific DAMPs and described two alternatives therapeutic approaches to reduce chronic vascular inflammation and lower CV pathology in CKD.
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Affiliation(s)
- Morgane Mazzarino
- Division of Infection & Immunity, Cardiff University, Cardiff, United Kingdom
- Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Esra Cetin
- Division of Infection & Immunity, Cardiff University, Cardiff, United Kingdom
- Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Maria Bartosova
- Division of Pediatric Nephrology, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Iva Marinovic
- Division of Pediatric Nephrology, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Natacha Ipseiz
- Division of Infection & Immunity, Cardiff University, Cardiff, United Kingdom
| | - Timothy R. Hughes
- Division of Infection & Immunity, Cardiff University, Cardiff, United Kingdom
| | - Claus Peter Schmitt
- Division of Pediatric Nephrology, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Dipak P. Ramji
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Mario O. Labéta
- Division of Infection & Immunity, Cardiff University, Cardiff, United Kingdom
- Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Anne-Catherine Raby
- Division of Infection & Immunity, Cardiff University, Cardiff, United Kingdom
- Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
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Raby AC, Labéta MO. Preventing Peritoneal Dialysis-Associated Fibrosis by Therapeutic Blunting of Peritoneal Toll-Like Receptor Activity. Front Physiol 2018; 9:1692. [PMID: 30538643 PMCID: PMC6277495 DOI: 10.3389/fphys.2018.01692] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/09/2018] [Indexed: 12/30/2022] Open
Abstract
Peritoneal dialysis (PD) is an essential daily life-saving treatment for end-stage renal failure. PD therapy is limited by peritoneal inflammation, which leads to peritoneal membrane failure as a result of progressive fibrosis. Peritoneal infections, with the concomitant acute inflammatory response and membrane fibrosis development, worsen PD patient outcomes. Patients who remain infection-free, however, also show evidence of inflammation-induced membrane damage and fibrosis, leading to PD cessation. In this case, uraemia, prolonged exposure to bio-incompatible PD solutions and surgical catheter insertion have been reported to induce sterile peritoneal inflammation and fibrosis as a result of cellular stress or tissue injury. Attempts to reduce inflammation (either infection-induced or sterile) and, thus, minimize fibrosis development in PD have been hampered because the immunological mechanisms underlying this PD-associated pathology remain to be fully defined. Toll-like receptors (TLRs) are central to mediating inflammatory responses by recognizing a wide variety of microorganisms and endogenous components released following cellular stress or generated as a consequence of extracellular matrix degradation during tissue injury. Given the close link between inflammation and fibrosis, recent investigations have evaluated the role that TLRs play in infection-induced and sterile peritoneal fibrosis development during PD. Here, we review the findings and discuss the potential of reducing peritoneal TLR activity by using a TLR inhibitor, soluble TLR2, as a therapeutic strategy to prevent PD-associated peritoneal fibrosis.
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Affiliation(s)
- Anne-Catherine Raby
- The Wales Kidney Research Unit, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Mario O Labéta
- The Wales Kidney Research Unit, Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
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4
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Holst B, Szakmany T, Raby AC, Hamlyn V, Durno K, Hall JE, Labéta MO. Soluble Toll-like receptor 2 is a biomarker for sepsis in critically ill patients with multi-organ failure within 12 h of ICU admission. Intensive Care Med Exp 2017; 5:2. [PMID: 28092080 PMCID: PMC5236041 DOI: 10.1186/s40635-016-0116-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/29/2016] [Indexed: 12/27/2022] Open
Abstract
Soluble TLR2 levels are elevated in infective and inflammatory conditions, but its diagnostic value with sepsis-induced multi-organ failure has not been evaluated. 37 patients with a diagnosis of severe sepsis/septic shock (sepsis) and 27 patients with organ failure without infection (SIRS) were studied. Median (IQR) plasma sTLR2 levels were 2.7 ng/ml (1.4-6.1) in sepsis and 0.6 ng/ml (0.4-0.9) in SIRS p < 0.001. sTLR2 showed good diagnostic value for sepsis at cut-off of 1.0 ng/ml, AUC:0.959. We report the ability of sTLR2 levels to discriminate between sepsis and SIRS within 12 h of ICU admission in patients with multi-organ failure.
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Affiliation(s)
- Benjamin Holst
- Department of Anaesthesia, Intensive Care and Pain Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Tamas Szakmany
- Department of Anaesthesia, Intensive Care and Pain Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK. .,ACT Directorate, Cwm Taf University Health Board, Llantrisant, CF72 8XR, UK. .,Anaesthetic Directorate, Aneurin Bevan University Health Board, Newport, NP20 5UB, UK.
| | - Anne-Catherine Raby
- Division of Infection and Immunity, Cardiff University, School of Medicine, Heath Park, Cardiff, CF14 4XN, UK
| | - Vincent Hamlyn
- Department of Anaesthesia, Intensive Care and Pain Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK.,Anaesthetic Directorate, Aneurin Bevan University Health Board, Newport, NP20 5UB, UK
| | - Kimberley Durno
- Department of Anaesthesia, Intensive Care and Pain Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Judith E Hall
- Department of Anaesthesia, Intensive Care and Pain Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Mario O Labéta
- Division of Infection and Immunity, Cardiff University, School of Medicine, Heath Park, Cardiff, CF14 4XN, UK.
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Raby AC, Labéta MO. Therapeutic Boosting of the Immune Response: Turning to CD14 for Help. Curr Pharm Biotechnol 2016; 17:414-8. [PMID: 26778454 PMCID: PMC5421138 DOI: 10.2174/1389201017666160114095708] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/29/2015] [Accepted: 01/04/2016] [Indexed: 02/08/2023]
Abstract
The Toll-like family of immune receptors (TLRs) are critical for an efficient immune response to a variety of microorganisms and other antigens that may cause pathology. Modulating immune responses by targeting TLRs therefore has substantial therapeutic potential, and a number of TLR-based therapeutic strategies have been developed. Minimizing the adverse effects that may result from the therapeutic manipulation of these signalling receptors nevertheless remains a major challenge. Efficient responses via TLRs require the activity of the co-receptor CD14, which enhances TLR responses. In an attempt to boost the immune response for therapeutic purposes, we have sought to target CD14 to achieve TLR modulation. Here we discuss the design, activity and therapeutic development options of TLR-derived peptides that interact with CD14 and enhance its co-receptor activity, thus amplifying TLR-mediated responses. This strategy represents a promising alternative to current TLR-based therapies, as it has the potential to amplify responses to different pathogens mediated by different TLRs by targeting the common TLR co-receptor, CD14.
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Affiliation(s)
| | - Mario O Labéta
- Institute of Infection & Immunity, School of Medicine, Cardiff University, Tenovus Building, Heath Park, Cardiff, CF14 4XN, United Kingdom.
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6
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Raby AC, Colmont CS, Kift-Morgan A, Köhl J, Eberl M, Fraser D, Topley N, Labéta MO. Toll-Like Receptors 2 and 4 Are Potential Therapeutic Targets in Peritoneal Dialysis-Associated Fibrosis. J Am Soc Nephrol 2016; 28:461-478. [PMID: 27432741 DOI: 10.1681/asn.2015080923] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 06/02/2016] [Indexed: 01/07/2023] Open
Abstract
Peritoneal dialysis (PD) remains limited by dialysis failure due to peritoneal membrane fibrosis driven by inflammation caused by infections or sterile cellular stress. Given the fundamental role of Toll-like receptors (TLRs) and complement in inflammation, we assessed the potential of peritoneal TLR2, TLR4 and C5a receptors, C5aR and C5L2, as therapeutic targets in PD-associated fibrosis. We detected TLR2-, TLR4-, and C5aR-mediated proinflammatory and fibrotic responses to bacteria that were consistent with the expression of these receptors in peritoneal macrophages (TLR2/4, C5aR) and mesothelial cells (TLR2, C5aR). Experiments in knockout mice revealed a major role for TLR2, a lesser role for TLR4, a supplementary role for C5aR, and no apparent activity of C5L2 in infection-induced peritoneal fibrosis. Similarly, antibody blockade of TLR2, TLR4, or C5aR differentially inhibited bacteria-induced profibrotic and inflammatory mediator production by peritoneal leukocytes isolated from the peritoneal dialysis effluent (PDE) of noninfected uremic patients. Additionally, antibodies against TLR2, TLR4, or the coreceptor CD14 reduced the profibrotic responses of uremic leukocytes to endogenous components present in the PDE of noninfected patients. Enhancing TLR2-mediated inflammation increased fibrosis in vivo Furthermore, soluble TLR2 (sTLR2), a negative modulator of TLRs that we detected in PDE, inhibited PDE-induced, TLR2- or TLR4-mediated profibrotic responses. Notably, sTLR2 treatment markedly reduced Gram-positive and -negative bacteria-induced fibrosis in vivo, inhibiting proinflammatory and fibrotic genes without affecting infection clearance. These findings reveal the influence of peritoneal TLR2 and TLR4 on PD-associated fibrosis and describe a therapeutic strategy against fibrosis.
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Affiliation(s)
- Anne-Catherine Raby
- Division of Infection and Immunity and The Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom;
| | - Chantal S Colmont
- Division of Infection and Immunity and The Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Ann Kift-Morgan
- Division of Infection and Immunity and The Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Jörg Köhl
- Institute for Systemic Inflammation Research, University of Lübeck, Lubeck, Germany; and.,Division of Immunobiology, Cincinnati Children's Hospital, Cincinnati, Ohio
| | - Matthias Eberl
- Division of Infection and Immunity and The Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Donald Fraser
- Division of Infection and Immunity and The Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Nicholas Topley
- Division of Infection and Immunity and The Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Mario O Labéta
- Division of Infection and Immunity and The Wales Kidney Research Unit, School of Medicine, Cardiff University, Cardiff, United Kingdom;
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7
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Holst B, Raby AC, Hall JE, Labéta MO. Complement takes its Toll: an inflammatory crosstalk between Toll-like receptors and the receptors for the complement anaphylatoxin C5a. Anaesthesia 2012; 67:60-64. [PMID: 22150483 DOI: 10.1111/j.1365-2044.2011.07011.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The innate immune system is responsible for a rapid inflammatory response to pathogens that is essential for the clearance of infections. Although this response is vital, it is nonetheless potentially harmful, and dysregulated inflammation is a feature of many disease states. Thus, the mechanisms that regulate the release of soluble mediators of inflammation are an active focus of investigation. The activation by infections of two key components of the innate immune system, the Toll-like receptors (TLRs) and complement, leading to the release of soluble mediators of inflammation, is critical to microbial killing and clearance. Both TLRs and complement are independently capable of triggering pro-inflammatory responses, but their synergistic interaction resulting from a substantial crosstalk markedly amplifies those responses and may contribute to the pathophysiology of diseases such as sepsis.
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Affiliation(s)
| | | | - J E Hall
- Professor and Head, Department of Anaesthetics, Intensive Care and Pain Medicine, School of Medicine, Cardiff University, Cardiff, UK
| | - M O Labéta
- Senior Lecturer, Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, UK
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8
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Raby AC, Holst B, Davies J, Colmont C, Laumonnier Y, Coles B, Shah S, Hall J, Topley N, Köhl J, Morgan BP, Labéta MO. TLR activation enhances C5a-induced pro-inflammatory responses by negatively modulating the second C5a receptor, C5L2. Eur J Immunol 2011; 41:2741-52. [PMID: 21630250 PMCID: PMC3638321 DOI: 10.1002/eji.201041350] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 05/03/2011] [Accepted: 05/25/2011] [Indexed: 01/07/2023]
Abstract
TLR and complement activation ensures efficient clearance of infection. Previous studies documented synergism between TLRs and the receptor for the pro-inflammatory complement peptide C5a (C5aR/CD88), and regulation of TLR-induced pro-inflammatory responses by C5aR, suggesting crosstalk between TLRs and C5aR. However, it is unclear whether and how TLRs modulate C5a-induced pro-inflammatory responses. We demonstrate a marked positive modulatory effect of TLR activation on cell sensitivity to C5a in vitro and ex vivo and identify an underlying mechanistic target. Pre-exposure of PBMCs and whole blood to diverse TLR ligands or bacteria enhanced C5a-induced pro-inflammatory responses. This effect was not observed in TLR4 signalling-deficient mice. TLR-induced hypersensitivity to C5a did not result from C5aR upregulation or modulation of C5a-induced Ca2+ mobilization. Rather, TLRs targeted another C5a receptor, C5L2 (acting as a negative modulator of C5aR), by reducing C5L2 activity. TLR-induced hypersensitivity to C5a was mimicked by blocking C5L2 and was not observed in C5L2KO mice. Furthermore, TLR activation inhibited C5L2 expression upon C5a stimulation. These findings identify a novel pathway of crosstalk within the innate immune system that amplifies innate host defense at the TLR-complement interface. Unravelling the mutually regulated activities of TLRs and complement may reveal new therapeutic avenues to control inflammation.
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Affiliation(s)
- Anne-Catherine Raby
- Department of Infection, Immunity and Biochemistry, School of Medicine, Cardiff University, Cardiff, UK
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9
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Colmont CS, Raby AC, Dioszeghy V, Lebouder E, Foster TL, Jones SA, Labéta MO, Fielding CA, Topley N. Human peritoneal mesothelial cells respond to bacterial ligands through a specific subset of Toll-like receptors. Nephrol Dial Transplant 2011; 26:4079-90. [PMID: 21633096 PMCID: PMC3224115 DOI: 10.1093/ndt/gfr217] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Bacterial infection remains a major cause of morbidity and mortality in peritoneal dialysis (PD) patients worldwide. Previous studies have identified a key role for mesothelial cells, lining the peritoneal cavity, in coordinating inflammation and host defense. Toll-like receptor (TLR) involvement in early activation events within the mesothelium, however, remains poorly defined. To investigate the initiation of bacterial peritonitis, we characterized TLR activation by bacterial ligands in human peritoneal mesothelial cells (HPMC). METHODS Primary HPMC were isolated from omental biopsies and TLR expression detected by real-time polymerase chain reaction (PCR), reverse transcription (RT)-PCR and flow cytometry. The responsiveness of HPMC to specific bacterial TLR agonists was determined using chemokine production as a biological readout. The requirement for CD14 in HPMC responses to a clinically relevant Staphylococcus epidermidis cell-free supernatant (SES) was investigated using soluble CD14 or anti-CD14-blocking antibodies. RESULTS Real-time PCR detected TLR1-6 messenger RNA expression in HPMC and responses to TLR2/1 and TLR2/6 ligands and SES. No cell surface TLR4 expression or responses to lipopolysaccharide were detectable in HPMC, but they did respond to flagellin, a TLR5 ligand. SES-mediated responses were dependent on TLR2 but did not require CD14 in HPMC for optimal efficiency, unlike peripheral blood mononuclear cells. HPMC expression of TLR2 was also modulated by TLR2 ligands and inflammatory cytokines. CONCLUSIONS These data suggest that mesothelial cell activation by TLR2/1, TLR2/6 and TLR5 contributes to bacterial recognition influencing the course of the infective process and has implications for improving treatment of infection in PD patients.
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Affiliation(s)
- Chantal S Colmont
- Department of Infection, Immunity and Biochemistry, School of Medicine, Cardiff University, Cardiff, UK
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Raby AC, Le Bouder E, Colmont C, Davies J, Richards P, Coles B, George CH, Jones SA, Brennan P, Topley N, Labéta MO. Soluble TLR2 Reduces Inflammation without Compromising Bacterial Clearance by Disrupting TLR2 Triggering. J Immunol 2009; 183:506-17. [DOI: 10.4049/jimmunol.0802909] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Colmont CS, Labéta MO, Raby AC, Coles B, Jones SA, Topley N. 49 Regulation of TLR mediated responses in the peritoneal cavity. Cytokine 2008. [DOI: 10.1016/j.cyto.2008.07.090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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12
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LeBouder E, Rey-Nores JE, Raby AC, Affolter M, Vidal K, Thornton CA, Labéta MO. Modulation of Neonatal Microbial Recognition: TLR-Mediated Innate Immune Responses Are Specifically and Differentially Modulated by Human Milk. J Immunol 2006; 176:3742-52. [PMID: 16517743 DOI: 10.4049/jimmunol.176.6.3742] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The mechanisms controlling innate microbial recognition in the neonatal gut are still to be fully understood. We have sought specific regulatory mechanisms operating in human breast milk relating to TLR-mediated microbial recognition. In this study, we report a specific and differential modulatory effect of early samples (days 1-5) of breast milk on ligand-induced cell stimulation via TLRs. Although a negative modulation was exerted on TLR2 and TLR3-mediated responses, those via TLR4 and TLR5 were enhanced. This effect was observed in human adult and fetal intestinal epithelial cell lines, monocytes, dendritic cells, and PBMC as well as neonatal blood. In the latter case, milk compensated for the low capacity of neonatal plasma to support responses to LPS. Cell stimulation via the IL-1R or TNFR was not modulated by milk. This, together with the differential effect on TLR activation, suggested that the primary effect of milk is exerted upstream of signaling proximal to TLR ligand recognition. The analysis of TLR4-mediated gene expression, used as a model system, showed that milk modulated TLR-related genes differently, including those coding for signal intermediates and regulators. A proteinaceous milk component of > or =80 kDa was found to be responsible for the effect on TLR4. Notably, infant milk formulations did not reproduce the modulatory activity of breast milk. Together, these findings reveal an unrecognized function of human milk, namely, its capacity to influence neonatal microbial recognition by modulating TLR-mediated responses specifically and differentially. This in turn suggests the existence of novel mechanisms regulating TLR activation.
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Affiliation(s)
- Emmanuel LeBouder
- Infection and Immunity, Department of Medical Biochemistry and Immunology, Cardiff University College of Medicine, Heath Park, Cardiff CF14 4XX, Wales, UK
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13
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LeBouder E, Rey-Nores JE, Rushmere NK, Grigorov M, Lawn SD, Affolter M, Griffin GE, Ferrara P, Schiffrin EJ, Morgan BP, Labéta MO. Soluble forms of Toll-like receptor (TLR)2 capable of modulating TLR2 signaling are present in human plasma and breast milk. J Immunol 2004; 171:6680-9. [PMID: 14662871 DOI: 10.4049/jimmunol.171.12.6680] [Citation(s) in RCA: 244] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Dysregulation of the initial, innate immune response to bacterial infection may lead to septic shock and death. Toll-like receptors (TLRs) play a crucial role in this innate immune response, and yet the regulatory mechanisms controlling microbial-induced TLR triggering are still to be fully understood. We have therefore sought specific regulatory mechanisms that may modulate TLR signaling. In this study, we tested for the possible existence of a functionally active soluble form of TLR2. We demonstrated the existence of natural soluble forms of TLR2 (sTLR2), which we show to be capable of modulating cell activation. We found that blood monocytes released sTLR2 constitutively and that the kinetics of sTLR2 release increased upon cell activation. Analysis of cells expressing the human TLR2 cDNA or its c-myc-tagged version indicated that sTLR2 resulted from the posttranslational modification of the TLR2 protein in an intracellular compartment. Moreover, an intracellular pool of sTLR2 is maintained. sTLR2 was found naturally expressed in breast milk and plasma. Milk sTLR2 levels mirrored those of the TLR coreceptor soluble CD14. Depletion of sTLR2 from serum resulted in an increased cellular response to bacterial lipopeptide. Notably, serum sTLR2 was lower in tuberculosis patients. Coimmunoprecipitation experiments and computational molecular docking studies showed an interaction between sTLR2 and soluble CD14 in plasma and milk. These findings suggest the existence of a novel and specific innate immune mechanism regulating microbial-induced TLR triggering, and may lead to new therapeutics for the prevention and/or treatment of severe infectious diseases.
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MESH Headings
- Amino Acid Sequence
- Cell Line
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Cells, Cultured
- Cysteine/analogs & derivatives
- Cysteine/antagonists & inhibitors
- Cysteine/pharmacology
- DNA, Complementary/biosynthesis
- Down-Regulation/drug effects
- Down-Regulation/immunology
- Female
- Humans
- Immunoglobulin Fc Fragments/genetics
- Intracellular Fluid/drug effects
- Intracellular Fluid/immunology
- Intracellular Fluid/metabolism
- Lactation
- Lipopolysaccharide Receptors/blood
- Lipopolysaccharide Receptors/metabolism
- Lipoproteins/antagonists & inhibitors
- Lipoproteins/pharmacology
- Macrophage Activation/drug effects
- Macrophage Activation/immunology
- Membrane Glycoproteins/blood
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Membrane Glycoproteins/physiology
- Milk, Human/chemistry
- Milk, Human/immunology
- Milk, Human/metabolism
- Molecular Sequence Data
- Monensin/pharmacology
- Monocytes/immunology
- Monocytes/metabolism
- Peptides/blood
- Peptides/isolation & purification
- Peptides/metabolism
- Peptides/physiology
- Precipitin Tests
- Protein Isoforms/blood
- Protein Isoforms/genetics
- Protein Isoforms/isolation & purification
- Protein Isoforms/metabolism
- Protein Processing, Post-Translational/drug effects
- Protein Processing, Post-Translational/immunology
- Protein Transport/immunology
- Receptors, Cell Surface/blood
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Recombinant Fusion Proteins/physiology
- Signal Transduction/drug effects
- Signal Transduction/immunology
- Solubility
- Toll-Like Receptor 2
- Toll-Like Receptors
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Affiliation(s)
- Emmanuel LeBouder
- Section of Infection and Immunity, University of Wales, College of Medicine, Cardiff, United Kingdom
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14
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Abstract
Immune factors secreted in milk are important for health in the neonatal gut. We have detected the bacterial pattern recognition receptor, soluble CD14 (sCD14) in human breast milk at different times during lactation. The molecule occurs in a single form in milk, in contrast to human serum, in which there are two isoforms. Produced by mammary epithelial cells, milk sCD14 mediates secretion of innate immune response molecules such as interleukin-8, tumor necrosis factor-alpha, and epithelial neutrophil activator-78 by CD14-negative intestinal epithelial cells exposed to lipopolysaccharide (LPS) or bacteria. Although present at low concentrations in milk, LPS-binding protein may be implicated in the biological effects observed. Our findings support the premise that milk sCD14 acts as a 'sentinel' molecule and immune modulator in homeostasis and in the defense of the neonatal intestine. In so doing, it may prevent the immune and inflammatory conditions of the gut to which non-breastfed infants are predisposed.
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Affiliation(s)
- K Vidal
- Nestlé Research Center, Vers-Chez-Les-Blanc, Lausanne, Switzerland
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15
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Labéta MO, Vidal K, Nores JE, Arias M, Vita N, Morgan BP, Guillemot JC, Loyaux D, Ferrara P, Schmid D, Affolter M, Borysiewicz LK, Donnet-Hughes A, Schiffrin EJ. Innate recognition of bacteria in human milk is mediated by a milk-derived highly expressed pattern recognition receptor, soluble CD14. J Exp Med 2000; 191:1807-12. [PMID: 10811873 PMCID: PMC2193148 DOI: 10.1084/jem.191.10.1807] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Little is known about innate immunity to bacteria after birth in the hitherto sterile fetal intestine. Breast-feeding has long been associated with a lower incidence of gastrointestinal infections and inflammatory and allergic diseases. We found in human breast milk a 48-kD polypeptide, which we confirmed by mass spectrometry and sequencing to be a soluble form of the bacterial pattern recognition receptor CD14 (sCD14). Milk sCD14 (m-sCD14) concentrations were up to 20-fold higher than serum sCD14 from nonpregnant, pregnant, or lactating women. In contrast, lipopolysaccharide (LPS)-binding protein was at very low levels. Mammary epithelial cells produced 48-kD sCD14. m-sCD14 mediated activation by LPS and whole bacteria of CD14 negative cells, including intestinal epithelial cells, resulting in release of innate immune response molecules. m-sCD14 was undetectable in the infant formulas and commercial (cows') milk tested, although it was present in bovine colostrum. These findings indicate a sentinel role for sCD14 in human milk during bacterial colonization of the gut, and suggest that m-sCD14 may be involved in modulating local innate and adaptive immune responses, thus controlling homeostasis in the neonatal intestine.
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Affiliation(s)
- M O Labéta
- Department of Medicine, University of Wales, College of Medicine, Heath Park, Cardiff CF4 4XX, United Kingdom
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16
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Arias MA, Rey Nores JE, Vita N, Stelter F, Borysiewicz LK, Ferrara P, Labéta MO. Cutting edge: human B cell function is regulated by interaction with soluble CD14: opposite effects on IgG1 and IgE production. J Immunol 2000; 164:3480-6. [PMID: 10725700 DOI: 10.4049/jimmunol.164.7.3480] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The mechanism(s) controlling activation of naive B cells, their proliferation, Ag receptor affinity maturation, isotype switching, and their fate as memory or plasma cells is not fully elucidated. Here we show that between 24 and 60% of CD19+ cells in PBMC bind soluble CD14 (sCD14). Tonsillar B cells also bind sCD14, but preferentially the CD38-ve/low cells. Interaction of sCD14 with B cells resulted in higher levels of IgG1 and marked inhibition of IgE production by activated tonsillar B cells and Ag-stimulated PBMC. We found that sCD14 interfered with CD40 signaling in B cells, inhibited IL-6 production by activated B cells, and increased the kinetics and magnitude of CD40 ligand expression on T cells. Together with the previously reported effects on T cells, these findings define sCD14 as a novel soluble regulatory factor capable of modulating cellular and humoral immune responses by interacting directly with T and B cells.
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Affiliation(s)
- M A Arias
- Department of Medicine, University of Wales, College of Medicine, Cardiff, United Kingdom
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17
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Rey Nores JE, Bensussan A, Vita N, Stelter F, Arias MA, Jones M, Lefort S, Borysiewicz LK, Ferrara P, Labéta MO. Soluble CD14 acts as a negative regulator of human T cell activation and function. Eur J Immunol 1999. [PMID: 9933108 DOI: 10.1002/(sici)1521-4141(199901)29:01<265::aid-immu265>3.0.co;2-g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
T cell activation is controlled by the coordination of stimulatory and negative regulatory signals which are not completely defined. In this study we tested for a possible direct effect of CD14 on the regulation of T cell activation and function. We show that soluble CD14 (sCD14) induces inhibition of antigen-mediated peripheral blood mononuclear cells (PBMC) proliferation and anti-CD3-mediated proliferation of CD4+CD8+, CD4+CD8+ and CD4+CD8+ Tcell clones. This effect is not due to cell death, but results from a marked inhibition of IL-2 production. Proliferation of T cell clones due to exogenous IL-2 is not affected by sCD14. We also found that sCD14 inhibits production of another Th1-like cytokine, IFN-gamma and a Th2-like cytokine, IL-4. Importantly, sCD14 induces a progressive accumulation of the inhibitory protein IkappaB-alpha. We show that sCD14 binds to activated T cells. Following cell activation, biotinylated sCD14 stains CD3+ PBMC, as well as human T cell clones with varying intensity. The binding is saturable, can be inhibited by excess of unlabeled sCD14 and, following binding, sCD14 is internalized. Collectively, these findings reveal a previously unrecognized function of sCD14, namely its capacity to negatively regulate T lymphocyte activation and function by interacting directly with activated T cells.
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Affiliation(s)
- J E Rey Nores
- Department of Medicine, University of Wales, College of Medicine, Cardiff, GB
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18
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Rey Nores JE, Bensussan A, Vita N, Stelter F, Arias MA, Jones M, Lefort S, Borysiewicz LK, Ferrara P, Labéta MO. Soluble CD14 acts as a negative regulator of human T cell activation and function. Eur J Immunol 1999; 29:265-76. [PMID: 9933108 DOI: 10.1002/(sici)1521-4141(199901)29:01<265::aid-immu265>3.0.co;2-g] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
T cell activation is controlled by the coordination of stimulatory and negative regulatory signals which are not completely defined. In this study we tested for a possible direct effect of CD14 on the regulation of T cell activation and function. We show that soluble CD14 (sCD14) induces inhibition of antigen-mediated peripheral blood mononuclear cells (PBMC) proliferation and anti-CD3-mediated proliferation of CD4+CD8+, CD4+CD8+ and CD4+CD8+ Tcell clones. This effect is not due to cell death, but results from a marked inhibition of IL-2 production. Proliferation of T cell clones due to exogenous IL-2 is not affected by sCD14. We also found that sCD14 inhibits production of another Th1-like cytokine, IFN-gamma and a Th2-like cytokine, IL-4. Importantly, sCD14 induces a progressive accumulation of the inhibitory protein IkappaB-alpha. We show that sCD14 binds to activated T cells. Following cell activation, biotinylated sCD14 stains CD3+ PBMC, as well as human T cell clones with varying intensity. The binding is saturable, can be inhibited by excess of unlabeled sCD14 and, following binding, sCD14 is internalized. Collectively, these findings reveal a previously unrecognized function of sCD14, namely its capacity to negatively regulate T lymphocyte activation and function by interacting directly with activated T cells.
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Affiliation(s)
- J E Rey Nores
- Department of Medicine, University of Wales, College of Medicine, Cardiff, GB
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19
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Vita N, Lefort S, Sozzani P, Reeb R, Richards S, Borysiewicz LK, Ferrara P, Labéta MO. Detection and biochemical characteristics of the receptor for complexes of soluble CD14 and bacterial lipopolysaccharide. J Immunol 1997; 158:3457-62. [PMID: 9120307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Soluble CD14 (sCD14) has been found to bind LPS and mediate LPS activation of several cell types. It has been postulated that sCD14-LPS complexes induce cell responses by interacting with a cell surface structure, which, in turn, triggers cell activation. There has been no biochemical evidence, however, for a direct interaction of sCD14 with a cell surface structure, and the putative receptor has not been identified. To rigorously test this hypothesis, we studied the interaction of human rsCD14 with cells in the absence of serum and in the presence and the absence of LPS. We found 1) there was specific and saturable binding of 125I-sCD14, indicative of a typical receptor-ligand interaction, to several cell types, including endothelial cells, epithelial cells, astrocytes, and human monocytes; 2) specific binding to all the cell types and IL-6 induction in membrane-bound CD14 (mCD14)-negative cells occurred only when both sCD14 and LPS were present; 3) competitive displacement experiments of 125I-sCD14 binding to astrocytes and Scatchard plots revealed a binding of high affinity (Kd = 3.3 +/- 0.4 nM) and approximately 25,000 single class binding sites/cell; 4) the steady state for the association of 125I-sCD14 was obtained after 180-200 min; 5) chemical cross-linking experiments revealed the association of sCD14 with a binding structure of approximately 216 kDa; 6) binding of 125I-sCD14 to CD14-expressing cell transfectants was about 50% lower than that to nontransfected cells. Maximal binding, however, was recovered after removing mCD14, suggesting that the sCD14-LPS receptor may also interact with mCD14. These results provide direct biochemical evidence for the existence of a cell surface signal-mediating binding structure for LPS-bearing sCD14 and suggest that this structure may represent the signaling unit of the postulated multimeric LPS receptor in mCD14-bearing cells.
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Affiliation(s)
- N Vita
- SANOFI Research, Labège Center, France
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20
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Vita N, Lefort S, Sozzani P, Reeb R, Richards S, Borysiewicz LK, Ferrara P, Labéta MO. Detection and biochemical characteristics of the receptor for complexes of soluble CD14 and bacterial lipopolysaccharide. The Journal of Immunology 1997. [DOI: 10.4049/jimmunol.158.7.3457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Soluble CD14 (sCD14) has been found to bind LPS and mediate LPS activation of several cell types. It has been postulated that sCD14-LPS complexes induce cell responses by interacting with a cell surface structure, which, in turn, triggers cell activation. There has been no biochemical evidence, however, for a direct interaction of sCD14 with a cell surface structure, and the putative receptor has not been identified. To rigorously test this hypothesis, we studied the interaction of human rsCD14 with cells in the absence of serum and in the presence and the absence of LPS. We found 1) there was specific and saturable binding of 125I-sCD14, indicative of a typical receptor-ligand interaction, to several cell types, including endothelial cells, epithelial cells, astrocytes, and human monocytes; 2) specific binding to all the cell types and IL-6 induction in membrane-bound CD14 (mCD14)-negative cells occurred only when both sCD14 and LPS were present; 3) competitive displacement experiments of 125I-sCD14 binding to astrocytes and Scatchard plots revealed a binding of high affinity (Kd = 3.3 +/- 0.4 nM) and approximately 25,000 single class binding sites/cell; 4) the steady state for the association of 125I-sCD14 was obtained after 180-200 min; 5) chemical cross-linking experiments revealed the association of sCD14 with a binding structure of approximately 216 kDa; 6) binding of 125I-sCD14 to CD14-expressing cell transfectants was about 50% lower than that to nontransfected cells. Maximal binding, however, was recovered after removing mCD14, suggesting that the sCD14-LPS receptor may also interact with mCD14. These results provide direct biochemical evidence for the existence of a cell surface signal-mediating binding structure for LPS-bearing sCD14 and suggest that this structure may represent the signaling unit of the postulated multimeric LPS receptor in mCD14-bearing cells.
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Affiliation(s)
- N Vita
- SANOFI Research, Labège Center, France
| | - S Lefort
- SANOFI Research, Labège Center, France
| | - P Sozzani
- SANOFI Research, Labège Center, France
| | - R Reeb
- SANOFI Research, Labège Center, France
| | | | | | - P Ferrara
- SANOFI Research, Labège Center, France
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