1
|
Khromov T, Dressel R, Siamishi I, Nolte J, Opitz L, Engel W, Pantakani DVK. Apoptosis-related gene expression profiles of mouse ESCs and maGSCs: role of Fgf4 and Mnda in pluripotent cell responses to genotoxicity. PLoS One 2012; 7:e48869. [PMID: 23145002 PMCID: PMC3492253 DOI: 10.1371/journal.pone.0048869] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 10/02/2012] [Indexed: 01/27/2023] Open
Abstract
Stem cells in the developing embryo proliferate and differentiate while maintaining genomic integrity, failure of which may lead to accumulation of mutations and subsequent damage to the embryo. Embryonic stem cells (ESCs), the in vitro counterpart of embryo stem cells are highly sensitive to genotoxic stress. Defective ESCs undergo either efficient DNA damage repair or apoptosis, thus maintaining genomic integrity. However, the genotoxicity- and apoptosis-related processes in germ-line derived pluripotent cells, multipotent adult germ-line stem cells (maGSCs), are currently unknown. Here, we analyzed the expression of apoptosis-related genes using OligoGEArray in undifferentiated maGSCs and ESCs and identified a similar set of genes expressed in both cell types. We detected the expression of intrinsic, but not extrinsic, apoptotic pathway genes in both cell types. Further, we found that apoptosis-related gene expression patterns of differentiated ESCs and maGSCs are identical to each other. Comparative analysis revealed that several pro- and anti-apoptotic genes are expressed specifically in pluripotent cells, but markedly downregulated in the differentiated counterparts of these cells. Activation of the intrinsic apoptotic pathway cause approximately ∼35% of both ESCs and maGSCs to adopt an early-apoptotic phenotype. Moreover, we performed transcriptome studies using early-apoptotic cells to identify novel pluripotency- and apoptosis-related genes. From these transcriptome studies, we selected Fgf4 (Fibroblast growth factor 4) and Mnda (Myeloid cell nuclear differentiating antigen), which are highly downregulated in early-apoptotic cells, as novel candidates and analyzed their roles in apoptosis and genotoxicity responses in ESCs. Collectively, our results show the existence of common molecular mechanisms for maintaining the pristine stem cell pool of both ESCs and maGSCs.
Collapse
Affiliation(s)
- Tatjana Khromov
- Institute of Human Genetics, University of Goettingen, Goettingen, Germany
| | - Ralf Dressel
- Department of Cellular and Molecular Immunology, University of Goettingen, Goettingen, Germany
| | - Iliana Siamishi
- Institute of Human Genetics, University of Goettingen, Goettingen, Germany
| | - Jessica Nolte
- Institute of Human Genetics, University of Goettingen, Goettingen, Germany
| | - Lennart Opitz
- DNA Microarray Facility, University of Goettingen, Goettingen, Germany
| | - Wolfgang Engel
- Institute of Human Genetics, University of Goettingen, Goettingen, Germany
| | | |
Collapse
|
2
|
Kiwamoto T, Kawasaki N, Paulson JC, Bochner BS. Siglec-8 as a drugable target to treat eosinophil and mast cell-associated conditions. Pharmacol Ther 2012; 135:327-36. [PMID: 22749793 PMCID: PMC3587973 DOI: 10.1016/j.pharmthera.2012.06.005] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 06/07/2012] [Indexed: 12/19/2022]
Abstract
Siglecs (sialic acid immunoglobulin-like lectins) are members of the immunoglobulin gene family that contain sialoside binding N-terminal domains. They are cell surface proteins found predominantly on cells of the immune system. Among them, Siglec-8 is uniquely expressed by human eosinophils and mast cells, as well as basophils. Engaging this structure with antibodies or glycan ligands results in apoptosis in human eosinophils and inhibition of release of preformed and newly generated mediators from human mast cells without affecting their survival. Pro-apoptotic effects are also seen when its closest functional paralog, Siglec-F, on mouse eosinophils is similarly engaged in vitro, and beneficial effects are observed after administration of Siglec-F antibody using models of eosinophilic pulmonary and gastrointestinal inflammation in vivo. Siglec-8 targeting may thus provide a means to specifically inhibit or deplete these cell types. Cell-directed therapies are increasingly sought after by the pharmaceutical industry for their potential to reduce side effects and increase safety. The challenge is to identify suitable targets on the cell type of interest, and selectively deliver a therapeutic agent. By targeting Siglec-8, monoclonal antibodies and glycan ligand-conjugated nanoparticles may be ideally suited for treatment of eosinophil and mast cell-related diseases, such as asthma, chronic rhinosinusitis, chronic urticaria, hypereosinophilic syndromes, mast cell and eosinophil malignancies and eosinophilic gastrointestinal disorders.
Collapse
Affiliation(s)
- Takumi Kiwamoto
- Department of Medicine, Division of Allergy and Clinical Immunology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA
| | - Norihito Kawasaki
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037 USA
| | - James C. Paulson
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037 USA
| | - Bruce S. Bochner
- Department of Medicine, Division of Allergy and Clinical Immunology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA
| |
Collapse
|
3
|
Thenappan T, Goel A, Marsboom G, Fang YH, Toth PT, Zhang HJ, Kajimoto H, Hong Z, Paul J, Wietholt C, Pogoriler J, Piao L, Rehman J, Archer SL. A central role for CD68(+) macrophages in hepatopulmonary syndrome. Reversal by macrophage depletion. Am J Respir Crit Care Med 2011; 183:1080-91. [PMID: 21148721 PMCID: PMC3086745 DOI: 10.1164/rccm.201008-1303oc] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 11/21/2010] [Indexed: 12/16/2022] Open
Abstract
RATIONALE The etiology of hepatopulmonary syndrome (HPS), a common complication of cirrhosis, is unknown. Inflammation and macrophage accumulation occur in HPS; however, their importance is unclear. Common bile duct ligation (CBDL) creates an accepted model of HPS, allowing us to investigate the cause of HPS. OBJECTIVES We hypothesized that macrophages are central to HPS and investigated the therapeutic potential of macrophage depletion. METHODS Hemodynamics, alveolar-arterial gradient, vascular reactivity, and histology were assessed in CBDL versus sham rats (n = 21 per group). The effects of plasma on smooth muscle cell proliferation and endothelial tube formation were measured. Macrophage depletion was used to prevent (gadolinium) or regress (clodronate) HPS. CD68(+) macrophages and capillary density were measured in the lungs of patients with cirrhosis versus control patients (n = 10 per group). MEASUREMENTS AND MAIN RESULTS CBDL increased cardiac output and alveolar-arterial gradient by causing capillary dilatation and arteriovenous malformations. Activated CD68(+)macrophages (nuclear factor-κB+) accumulated in HPS pulmonary arteries, drawn by elevated levels of plasma endotoxin and lung monocyte chemoattractant protein-1. These macrophages expressed inducible nitric oxide synthase, vascular endothelial growth factor, and platelet-derived growth factor. HPS plasma increased endothelial tube formation and pulmonary artery smooth muscle cell proliferation. Macrophage depletion prevented and reversed the histological and hemodynamic features of HPS. CBDL lungs demonstrated increased medial thickness and obstruction of small pulmonary arteries. Nitric oxide synthase inhibition unmasked exaggerated pulmonary vasoconstrictor responses in HPS. Patients with cirrhosis had increased pulmonary intravascular macrophage accumulation and capillary density. CONCLUSIONS HPS results from intravascular accumulation of CD68(+)macrophages. An occult proliferative vasculopathy may explain the occasional transition to portopulmonary hypertension. Macrophage depletion may have therapeutic potential in HPS.
Collapse
MESH Headings
- Animals
- Antigens, CD/immunology
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/immunology
- Antigens, Differentiation, Myelomonocytic/physiology
- Arteriovenous Malformations/etiology
- Arteriovenous Malformations/physiopathology
- Disease Models, Animal
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Hepatopulmonary Syndrome/etiology
- Hepatopulmonary Syndrome/immunology
- Humans
- Lung/blood supply
- Lung/cytology
- Lung/immunology
- Macrophages/immunology
- Macrophages/physiology
- Male
- Muscle, Smooth, Vascular/physiopathology
- Nitric Oxide Synthase Type II/antagonists & inhibitors
- Nitric Oxide Synthase Type II/physiology
- Platelet-Derived Growth Factor/antagonists & inhibitors
- Platelet-Derived Growth Factor/physiology
- Rats
- Rats, Sprague-Dawley
- Signal Transduction/physiology
- Vascular Endothelial Growth Factor A/antagonists & inhibitors
- Vascular Endothelial Growth Factor A/physiology
Collapse
Affiliation(s)
- Thenappan Thenappan
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Ankush Goel
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Glenn Marsboom
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Yong-Hu Fang
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Peter T. Toth
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Hannah J. Zhang
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Hidemi Kajimoto
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Zhigang Hong
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Jonathan Paul
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Christian Wietholt
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Jennifer Pogoriler
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Lin Piao
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Jalees Rehman
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| | - Stephen L. Archer
- Section of Cardiology, Department of Medicine, The University of Chicago, Chicago, Illinois; and The Cardiovascular Research Institute, Kurume University, Kurume, Fukuoka, Japan
| |
Collapse
|
4
|
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) infects fully differentiated cells of the monocyte/macrophage lineage. Recently, CD163 was shown to be a cellular receptor capable of mediating infection of otherwise PRRSV non-permissive cell lines. CD163 is a macrophage differentiation antigen belonging to the scavenger receptor cysteine-rich (SRCR) family of membrane proteins. We provide a brief review of current knowledge regarding CD163 in relation to PRRSV infection, and propose a structure-based prediction of amino acid sequences involved in PRRSV interaction.
Collapse
MESH Headings
- Animals
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/physiology
- Cell Line
- Macrophages/virology
- Porcine respiratory and reproductive syndrome virus/physiology
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Receptors, Virus/chemistry
- Receptors, Virus/genetics
- Receptors, Virus/physiology
- Virus Internalization
Collapse
Affiliation(s)
- Siao-Kun W Welch
- Global Biologics Research, Pfizer Animal Health, 333 Portage Street, Kalamazoo, MI 49007, USA.
| | | |
Collapse
|
5
|
Onofre G, Kolácková M, Jankovicová K, Krejsek J. Scavenger receptor CD163 and its biological functions. Acta Medica (Hradec Kralove) 2009; 52:57-61. [PMID: 19777868] [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] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
CD163 is a member of scavenger receptor super family class B of the first subgroup. It is mapped to the region p13 on chromosome 12. Five different isoforms of CD163 have been described, which differ in the structure of their cytoplasmic domains and putative phosporylation sites. This scavenger receptor is selectively expressed on cells of monocytes and macrophages lineage exclusively. CD163 immunological function is essentially homeostatic. It also has other functions because participates in adhesion to endothelial cells, in tolerance induction and tissues regeneration. Other very important function of CD163 is the clearance of hemoglobin in its cell-free form and participation in anti-inflammation in its soluble form, exhibiting cytokine-like functions. We review the biological functions of CD163 which have been discovered until now. It seems apparent from this review that CD163 scavenger receptor can be used as biomarker in different diseases and as a valuable diagnostic parameter for prognosis of many diseases especially inflammatory disorders and sepsis.
Collapse
Affiliation(s)
- Gabriela Onofre
- Department of Clinical Immunology and Allergology, Charles University in Prague, Faculty of Medicine and University Hospital Hradec Králové, Czech Republic
| | | | | | | |
Collapse
|
6
|
Abstract
Efficient extracellular hemoglobin (Hb) clearance is essential to prevent oxidative- and nitrosative-mediated toxicity. CD163 belongs to group B of the scavenger receptor cysteine-rich (SRCR) protein family found on the surface of monocytes and macrophages and is responsible for Hb-haptoglobin (Hp) complex uptake. Hb uptake by CD163 was thought to proceed exclusively through an Hp-dependent pathway. However, Hb can interact directly with CD163 via a low affinity binding when Hp is absent. As a result, a two-phase hypothesis of Hb clearance by monocytes/macrophages suggests that Hp-Hb binding to CD163 is the primary mechanism of plasma Hb clearance, while clearance of Hb by direct binding to CD163 is secondary to Hp depletion. The authors have considered the ligand specificity of CD163 in human macrophages and in a heterologous gene expression model to demonstrate that Hb is effectively endocytosed by CD163 in the absence of Hp. Additionally, the authors have considered Hb-based oxygen carriers (HBOCs) administration as a unique situation during which direct CD163 uptake may be relevant as a mechanism of clearance. However, the nature of chemical modifications introduced onto the Hb molecule and/or oxidative changes induced in the protein appear to influence the extent of CD163 interaction and cellular uptake. Here, an overview and novel insights into the role of CD163 in Hb redox inactivation and clearance are provided.
Collapse
MESH Headings
- Animals
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/immunology
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Hemoglobins/chemistry
- Hemoglobins/metabolism
- Humans
- Macrophages/immunology
- Macrophages/metabolism
- Oxidation-Reduction
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/metabolism
- Receptors, Cell Surface/physiology
- Receptors, Scavenger/immunology
- Receptors, Scavenger/metabolism
- Receptors, Scavenger/physiology
- Signal Transduction
Collapse
Affiliation(s)
- Dominik J Schaer
- Medical Clinic B Research Unit, University of Zurich, Switzerland
| | | | | |
Collapse
|
7
|
O'Reilly D, Greaves DR. Cell-type-specific expression of the human CD68 gene is associated with changes in Pol II phosphorylation and short-range intrachromosomal gene looping. Genomics 2007; 90:407-15. [PMID: 17583472 DOI: 10.1016/j.ygeno.2007.04.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 04/26/2007] [Accepted: 04/28/2007] [Indexed: 01/05/2023]
Abstract
Transcriptional regulation in higher eukaryotes frequently involves long-range interactions, up to tens of hundreds of kilobases away, of a number of cis-acting regulatory DNA elements. Using the chromosome conformation capture technique we have analyzed the expression of a small 2.5-kb gene, CD68, in different human cell types and show for the first time that short-range interactions may also be critical. In human monocytes, which produce high levels of CD68 mRNA, the gene is characterized by intramolecular ligations between the promoter and the 3' intervening region. In cells that poorly express the gene a change in architecture is apparent whereby the promoter preferentially associates with the terminator region only. Furthermore, alterations in CD68 gene structure are associated with failings in mRNA splicing and changes with the phosphorylation status of RNA Pol II across the gene. We propose that short-range intrachromosomal interactions may form the basis of coordinated control of monocyte-specific gene regulation.
Collapse
MESH Headings
- Antigens, CD/biosynthesis
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/biosynthesis
- Antigens, Differentiation, Myelomonocytic/physiology
- Cell Line
- Cell Line, Tumor
- Chromatin/metabolism
- Chromatin Immunoprecipitation
- DNA Polymerase II/metabolism
- Gene Expression Regulation
- HL-60 Cells
- Humans
- Jurkat Cells
- Models, Genetic
- Myeloid Cells/metabolism
- Phosphorylation
- RNA, Messenger/metabolism
- Transcription, Genetic
Collapse
Affiliation(s)
- Dawn O'Reilly
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | | |
Collapse
|
8
|
Brinkman-Van der Linden ECM, Hurtado-Ziola N, Hayakawa T, Wiggleton L, Benirschke K, Varki A, Varki N. Human-specific expression of Siglec-6 in the placenta. Glycobiology 2007; 17:922-31. [PMID: 17580316 DOI: 10.1093/glycob/cwm065] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [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: 11/14/2022] Open
Abstract
CD33-related-Siglecs are lectins on immune cells that recognize sialic acids via extracellular domains, and deliver negative signals via cytosolic tyrosine-based regulatory motifs. We report that while Siglec-6/OB-BP1 (which can also bind leptin) is expressed on immune cells of both humans and the closely related great apes, placental trophoblast expression is human-specific, with little or no expression in ape placentae. Human-specific transcription factor recognition site changes in the Siglec-6 promoter region can help explain the human-specific expression. Human placenta also expresses natural ligands for Siglec-6 (a mixture of glycoproteins carrying cognate sialylated targets), in areas adjacent to Siglec-6 expression. Ligands were also found in uterine endometrium and on cell lines of trophoblastic or endometrial origin. Thus, Siglec-6 was recruited to placental expression during human evolution, presumably to interact with sialylated ligands for specific negative signaling functions and/or to regulate leptin availability. The control of human labor is poorly understood, but involves multiple cues, including placental signaling. Human birthing is also prolonged in comparison to that in our closest evolutionary relatives, the great apes. We found that Siglec-6 levels are generally low in placentae from elective surgical deliveries without known labor and the highest following completion of labor. We therefore speculate that the negative signaling potential of Siglec-6 was recruited to human-specific placental expression, to slow the tempo of the human birth process. The leptin-binding ability of Siglec-6 is also consistent with this hypothesis, as leptin-deficient mice have increased parturition times.
Collapse
MESH Headings
- 5' Untranslated Regions
- Animals
- Antibodies, Monoclonal/chemistry
- Antigens, CD/biosynthesis
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/biosynthesis
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Base Sequence
- Cytosol/metabolism
- Gene Expression Regulation, Developmental
- Humans
- Lectins/metabolism
- Lectins/physiology
- Mice
- Molecular Sequence Data
- N-Acetylneuraminic Acid/metabolism
- Pan troglodytes
- Placenta/metabolism
- Sialic Acid Binding Ig-like Lectin 3
- Species Specificity
- Transcription, Genetic
Collapse
Affiliation(s)
- Els C M Brinkman-Van der Linden
- Glycobiology Research and Training Center, Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0687, USA
| | | | | | | | | | | | | |
Collapse
|
9
|
Schaer CA, Vallelian F, Imhof A, Schoedon G, Schaer DJ. CD163-expressing monocytes constitute an endotoxin-sensitive Hb clearance compartment within the vascular system. J Leukoc Biol 2007; 82:106-10. [PMID: 17460152 DOI: 10.1189/jlb.0706453] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [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: 11/24/2022] Open
Abstract
Hemoglobin (Hb) is released into the circulation during intravascular hemolysis and exerts toxic effects through oxidative damage and NO scavenging. According to the traditional concept of Hb clearance, free Hb is bound to the plasma protein haptoglobin (Hp), and the Hb-Hp complexes are cleared by liver and spleen macrophages via the Hb scavenger receptor CD163. Using a novel whole blood assay, we demonstrate that clearance of Hb-Hp is also mediated by CD14(high)/CD64(high) peripheral blood monocytes, which express CD163. Hb-Hp uptake by these cells is Ca(2+)-dependent and is abrogated by the addition of CD163-blocking antibodies. Accordingly, LPS treatment reduces monocyte surface CD163 and impairs Hb-Hp uptake. Monocytes likely mediate Hp-Hb uptake in vivo, as a high expression of the heme breakdown enzyme heme oxygenase-1 was observed in CD163(+) monocytes but not in other leukocyte populations obtained from healthy blood donors. We propose that CD163-mediated Hb-Hp uptake by peripheral blood monocytes constitutes an Hb-Hp clearance pathway, which acts at the site of intravascular hemolysis to reduce Hb-Hp circulation time and toxicity. Disruption of monocyte Hb-Hp clearance may increase Hb-Hp toxicity and contribute to the pathogenesis of systemic inflammatory diseases associated with reduced monocyte CD163 expression.
Collapse
Affiliation(s)
- Christian A Schaer
- Department of Medicine, University Hospital, CH-8091 Zurich, Switzerland
| | | | | | | | | |
Collapse
|
10
|
Fabriek BO, Polfliet MMJ, Vloet RPM, van der Schors RC, Ligtenberg AJM, Weaver LK, Geest C, Matsuno K, Moestrup SK, Dijkstra CD, van den Berg TK. The macrophage CD163 surface glycoprotein is an erythroblast adhesion receptor. Blood 2007; 109:5223-9. [PMID: 17353345 DOI: 10.1182/blood-2006-08-036467] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [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: 12/15/2022] Open
Abstract
Erythropoiesis occurs in erythroblastic islands, where developing erythroblasts closely interact with macrophages. The adhesion molecules that govern macrophage-erythroblast contact have only been partially defined. Our previous work has implicated the rat ED2 antigen, which is highly expressed on the surface of macrophages in erythroblastic islands, in erythroblast binding. In particular, the monoclonal antibody ED2 was found to inhibit erythroblast binding to bone marrow macrophages. Here, we identify the ED2 antigen as the rat CD163 surface glycoprotein, a member of the group B scavenger receptor cysteine-rich (SRCR) family that has previously been shown to function as a receptor for hemoglobin-haptoglobin (Hb-Hp) complexes and is believed to contribute to the clearance of free hemoglobin. CD163 transfectants and recombinant protein containing the extracellular domain of CD163 supported the adhesion of erythroblastic cells. Furthermore, we identified a 13-amino acid motif (CD163p2) corresponding to a putative interaction site within the second scavenger receptor domain of CD163 that could mediate erythroblast binding. Finally, CD163p2 promoted erythroid expansion in vitro, suggesting that it enhanced erythroid proliferation and/or survival, but did not affect differentiation. These findings identify CD163 on macrophages as an adhesion receptor for erythroblasts in erythroblastic islands, and suggest a regulatory role for CD163 during erythropoiesis.
Collapse
Affiliation(s)
- Babs O Fabriek
- Department of Molecular Cell Biology, Vrije Universiteit Medical Center, Amsterdam, the Netherlands
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Zhang M, Angata T, Cho JY, Miller M, Broide DH, Varki A. Defining the in vivo function of Siglec-F, a CD33-related Siglec expressed on mouse eosinophils. Blood 2007; 109:4280-7. [PMID: 17272508 PMCID: PMC1885492 DOI: 10.1182/blood-2006-08-039255] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD33-related Siglecs (CD33rSiglecs) are a family of sialic acid-recognizing lectins on immune cells whose biologic functions are unknown. We studied in vivo functions of Siglec-F, the CD33rSiglec expressed on mouse eosinophils, which are prominent in allergic processes. Induction of allergic lung inflammation in mice caused up-regulation of Siglec-F on blood and bone marrow eosinophils, accompanied by newly induced expression on some CD4(+) cells, as well as quantitative up-regulation of endogenous Siglec-F ligands in the lung tissue and airways. Taken together with the tyrosine-based inhibitory motif in the cytosolic tail of Siglec-F, the data suggested a negative feedback loop, controlling allergic responses of eosinophils and helper T cells, via Siglec-F and Siglec-F ligands. To pursue this hypothesis, we created Siglec-F-null mice. Allergen-challenged null mice showed increased lung eosinophil infiltration, enhanced bone marrow and blood eosinophilia, delayed resolution of lung eosinophilia, and reduced peribronchial-cell apoptosis. Anti-Siglec-F antibody cross-linking also enhanced eosinophil apoptosis in vitro. These data support the proposed negative feedback role for Siglec-F, represent the first in vivo demonstration of biologic functions for any CD33rSiglec, and predict a role for human Siglec-8 (the isofunctional paralog of mouse Siglec-F) in regulating the pathogenesis of human eosinophil-mediated disorders.
Collapse
MESH Headings
- Animals
- Antigens, CD/chemistry
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/immunology
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Apoptosis/drug effects
- Bronchial Provocation Tests
- Disease Models, Animal
- Eosinophils/metabolism
- Gene Expression Regulation
- Hypersensitivity/genetics
- Hypersensitivity/metabolism
- Lung Diseases/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- N-Acetylneuraminic Acid/pharmacology
- Respiratory Mucosa/drug effects
- Respiratory Mucosa/metabolism
- Sequence Homology
- Sialic Acid Binding Ig-like Lectin 3
- Sialic Acid Binding Immunoglobulin-like Lectins
- T-Lymphocytes/metabolism
Collapse
Affiliation(s)
- Mai Zhang
- Glycobiology Research and Training Center, Departments of Medicine and Cellular & Molecular Medicine, and Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093-0687, USA
| | | | | | | | | | | |
Collapse
|
12
|
Schaer CA, Schoedon G, Imhof A, Kurrer MO, Schaer DJ. Constitutive endocytosis of CD163 mediates hemoglobin-heme uptake and determines the noninflammatory and protective transcriptional response of macrophages to hemoglobin. Circ Res 2006; 99:943-50. [PMID: 17008602 DOI: 10.1161/01.res.0000247067.34173.1b] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Heme toxicity contributes to the pathogenesis of chronic inflammatory diseases, atherosclerosis, and hemolysis associated vasculopathy. Macrophage clearance of cell free hemoglobin (Hb) is thus an essential homeostatic function of these cells. We examined the transcriptional response of human PBMC derived macrophages to Hb by gene array analysis. The observed noninflammatory macrophage response was characterized by induction of an antioxidative and antiinflammatory gene expression pattern with most prominent induction of the inducible heme oxygenase (HO-1). The metabolically active Hb-CD163-HO-1 pathway resulted in synthesis of ferritin-1 of the antioxidative and antiinflammatory end products linked to heme breakdown by HO-1. This response was mediated by the Hb scavenger receptor CD163 and heme and was not related to Hb mediated depletion of reduced glutathione. In contrast to other cellular responses induced by CD163, there was no role of protein phosphorylation dependent CD163 signaling in the protective macrophage response to Hb. Instead, CD163 acted as an Hb transporter, which undergoes constitutive and ligand independent internalization and recycling between the cell surface and early endosomes. The expression of CD163 and HO-1 in macrophages of neovascularized atherosclerotic lesions suggests that the pathway described herein is active in vivo. Noninflammatory Hb clearance and intimately linked HO-1 expression may provide the long sought-after explanation for the antiinflammatory activity associated with CD163-positive macrophages.
Collapse
MESH Headings
- Antigens, CD/analysis
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/analysis
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Atherosclerosis/metabolism
- Atherosclerosis/pathology
- Cells, Cultured
- Cytoprotection
- Endocytosis
- Endosomes/metabolism
- Gene Expression Profiling
- Gene Expression Regulation, Enzymologic
- Glutathione/metabolism
- Heme/metabolism
- Heme/physiology
- Heme Oxygenase-1/biosynthesis
- Heme Oxygenase-1/genetics
- Hemoglobins/metabolism
- Hemoglobins/pharmacology
- Humans
- Inflammation/metabolism
- Macrophages/drug effects
- Macrophages/enzymology
- Macrophages/metabolism
- Neovascularization, Pathologic/metabolism
- RNA, Messenger/metabolism
- Receptors, Cell Surface/analysis
- Receptors, Cell Surface/metabolism
- Receptors, Cell Surface/physiology
- Receptors, Scavenger/metabolism
- Transcription, Genetic
Collapse
|
13
|
Vanheusden K, Van Coppernolle S, De Smedt M, Plum J, Vandekerckhove B. In vitro expanded cells contributing to rapid severe combined immunodeficient repopulation activity are CD34+38-33+90+45RA-. Stem Cells 2006; 25:107-14. [PMID: 16973833 DOI: 10.1634/stemcells.2006-0256] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [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: 11/17/2022]
Abstract
Expansion of hematopoietic stem cells could be used clinically to shorten the prolonged aplastic phase after umbilical cord blood (UCB) transplantation. In this report, we investigated rapid severe combined immunodeficient (SCID) repopulating activity (rSRA) 2 weeks after transplantation of CD34(+) UCB cells cultured with serum on MS5 stromal cells and in serum- and stroma-free cultures. Various subpopulations obtained after culture were studied for rSRA. CD34(+) expansion cultures resulted in vast expansion of CD45(+) and CD34(+) cells. Independent of the culture method, only the CD34(+)33(+)38(-) fraction of the cultured cells contained rSRA. Subsequently, we subfractionated the CD34(+)38(-) fraction using stem cell markers CD45RA and CD90. In vitro differentiation cultures showed CD34(+) expansion in both CD45RA(-) and CD90(+) cultures, whereas little increase in CD34(+) cells was observed in both CD45RA(+) and CD90(-) cultures. By four-color flow cytometry, we could demonstrate that CD34(+)38(-)45RA(-) and CD34(+)38(-)90(+) cell populations were largely overlapping. Both populations were able to reconstitute SCID/nonobese diabetic mice at 2 weeks, indicating that these cells contained rSRA activity. In contrast, CD34(+)38(-)45RA(+) or CD34(+)38(-)90(-) cells contributed only marginally to rSRA. Similar results were obtained when cells were injected intrafemorally, suggesting that the lack of reconstitution was not due to homing defects. In conclusion, we show that after in vitro expansion, rSRA is mediated by CD34(+)38(-)90(+)45RA(-) cells. All other cell fractions have limited reconstitutive potential, mainly because the cells have lost stem cell activity rather than because of homing defects. These findings can be used clinically to assess the rSRA of cultured stem cells.
Collapse
Affiliation(s)
- Katrien Vanheusden
- Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent University Hospital, Ghent, Belgium
| | | | | | | | | |
Collapse
|
14
|
Avril T, Wagner ER, Willison HJ, Crocker PR. Sialic acid-binding immunoglobulin-like lectin 7 mediates selective recognition of sialylated glycans expressed on Campylobacter jejuni lipooligosaccharides. Infect Immun 2006; 74:4133-41. [PMID: 16790787 PMCID: PMC1489752 DOI: 10.1128/iai.02094-05] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [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: 02/06/2023] Open
Abstract
siglecs are a family of sialic-acid binding immunoglobulin-like lectins mostly expressed by cells of the immune system that have the potential to interact with sialylated glycans expressed not only on host cells but also on certain pathogens. Campylobacter jejuni is a common pathogen of humans that expresses surface lipooligosaccharides (LOS) that can be modified with ganglioside-like terminal structures in the core oligosaccharides. In this study, we examined the interaction of 10 siglecs with LOS purified from four different C. jejuni isolates expressing GM1-like, GD1a-like, GD3-like, and GT1a-like oligosaccharides. Of all siglecs examined, only Siglec-7 exhibited specific, sialic acid-dependent interactions with C. jejuni LOS in solid-phase binding assays. Binding was especially prominent with LOS from the HS:19(GM1(+) GT1a(+)) isolate, with weaker binding with LOS from the HS:19(GD3(+)) isolate. Binding of Siglec-7 was also observed with intact bacteria expressing these LOS structures. Specific binding of HS:19(GM1(+) GT1a(+)) bacteria was demonstrated with Siglec-7 expressed on transfected Chinese hamster ovary cells and with peripheral blood leukocytes, among which HS:19(GM1(+) GT1a(+)) bacteria bound selectively to both natural killer cells and monocytes which naturally express Siglec-7. These results raise the possibility that, in addition to their role in generating autoimmune antibody responses, C. jejuni LOS could interact with Siglec-7 expressed by leukocytes, modulate the host-pathogen interaction, and contribute to the clinical outcome and the development of secondary complications such as Guillain-Barré syndrome.
Collapse
Affiliation(s)
- Tony Avril
- Wellcome Trust Biocentre, University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
| | | | | | | |
Collapse
|
15
|
Attrill H, Takazawa H, Witt S, Kelm S, Isecke R, Brossmer R, Ando T, Ishida H, Kiso M, Crocker P, van Aalten D. The structure of siglec-7 in complex with sialosides: leads for rational structure-based inhibitor design. Biochem J 2006; 397:271-8. [PMID: 16623661 PMCID: PMC1513286 DOI: 10.1042/bj20060103] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [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: 11/17/2022]
Abstract
Siglecs (sialic acid binding Ig-like lectins) are transmembrane receptors for sialylated glycoconjugates that modulate cellular interactions and signalling events in the haematopoietic, immune and nervous systems. Siglec-7 is a structural prototype for the recently described family of immune inhibitory CD33-related siglecs and is predominantly expressed on natural killer cells and monocytes, as well as subsets of CD8 T-cells. Siglec-specific inhibitors are desired for the detection of masked and unmasked forms of siglecs, to aid in dissection of signalling pathways and as tools to investigate siglecs as potential therapeutic targets. As a first step towards this end, we present the crystal structure of siglec-7 in complex with a sialylated ligand, the ganglioside analogue DSLc4 [alpha(2,3)/alpha(2,6) disialyl lactotetraosyl 2-(trimethylsilyl)ethyl], which allows for a detailed description of the binding site, required for structure-guided inhibitor design. Mutagenesis and binding assays were used to demonstrate a key structural role for Lys131, a residue that changes conformation upon sialic acid binding. Differences between the binding sites of siglec family members were then exploited using alpha-methyl Neu5Ac (N-acetylneuraminic acid) as a basic scaffold. A co-crystal of siglec-7 in complex with the sialoside inhibitor, oxamido-Neu5Ac [methyl alpha-9-(amino-oxalyl-amino)-9-deoxy-Neu5Ac] and inhibition data for the sialosides gives clear leads for future inhibitor design.
Collapse
Affiliation(s)
- Helen Attrill
- *Divisions of Biological Chemistry and Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
- †Department of Cell Biology and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
| | - Hirokazu Takazawa
- †Department of Cell Biology and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
| | - Simone Witt
- ‡Centre for Biomolecular Interactions Bremen, Department of Biology and Chemistry, University Bremen, 28334 Bremen, Germany
| | - Soerge Kelm
- ‡Centre for Biomolecular Interactions Bremen, Department of Biology and Chemistry, University Bremen, 28334 Bremen, Germany
| | - Rainer Isecke
- §Biochemistry Center Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany
| | - Reinhard Brossmer
- §Biochemistry Center Heidelberg, University of Heidelberg, 69120, Heidelberg, Germany
| | - Takayuki Ando
- ¶Department of Applied Bioorganic Chemistry, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan
| | - Hideharu Ishida
- ¶Department of Applied Bioorganic Chemistry, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan
| | - Makoto Kiso
- ¶Department of Applied Bioorganic Chemistry, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan
| | - Paul R. Crocker
- †Department of Cell Biology and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
| | - Daan M. F. van Aalten
- *Divisions of Biological Chemistry and Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K
- To whom correspondence should be addressed (email )
| |
Collapse
|
16
|
Briggs RC, Shults KE, Flye LA, McClintock-Treep SA, Jagasia MH, Goodman SA, Boulos FI, Jacobberger JW, Stelzer GT, Head DR. Dysregulated human myeloid nuclear differentiation antigen expression in myelodysplastic syndromes: evidence for a role in apoptosis. Cancer Res 2006; 66:4645-51. [PMID: 16651415 DOI: 10.1158/0008-5472.can-06-0229] [Citation(s) in RCA: 32] [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: 11/16/2022]
Abstract
Reduced levels of human myeloid nuclear differentiation antigen (MNDA) gene transcripts have been detected in both familial and sporadic cases of myelodysplastic syndromes (MDS). Numerous reports implicate elevated apoptosis/programmed cell death and death ligands and their receptors in the pathogenesis of MDS. MNDA and related proteins contain the pyrin domain that functions in signaling associated with programmed cell death and inflammation. We tested the hypothesis that MNDA is involved in the regulation of programmed cell death in human myeloid hematopoietic cells. Clones of K562 cells (MNDA-null) that expressed ectopic MNDA protein were established using retroviral transduction. MNDA-expressing K562 clones were resistant to tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-induced apoptosis, but were not protected from programmed cell death induced with genotoxic agents or H(2)O(2). MNDA protein expression assessed in control and intermediate and high-grade MDS marrows showed several patterns of aberrant reduced MNDA. These variable patterns of dysregulated MNDA expression may relate to the variable pathophysiology of MDS. We propose that MNDA has a role regulating programmed cell death in myeloid progenitor cells, and that its down-regulation in MDS is related to granulocyte-macrophage progenitor cell sensitivity to TRAIL-induced programmed cell death.
Collapse
Affiliation(s)
- Robert C Briggs
- Departments of Pathology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Taylor MD, Harris A, Nair MG, Maizels RM, Allen JE. F4/80+Alternatively Activated Macrophages Control CD4+T Cell Hyporesponsiveness at Sites Peripheral to Filarial Infection. J Immunol 2006; 176:6918-27. [PMID: 16709852 DOI: 10.4049/jimmunol.176.11.6918] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Both T cells and APC have been strongly implicated in the immune suppression observed during filarial nematode infections, but their relative roles are poorly understood, particularly in regard to timing and locality of action. Using Litomosoides sigmodontis infection of susceptible BALB/c mice, we have studied the progression of filarial immunosuppression leading to patent infection with blood microfilaremia. Patent infection is associated with decreased immune responsiveness in the draining thoracic lymph nodes (tLN) and intrinsically hyporesponsive CD4+ T cells at the infection site. We now show that we are able to separate, both in time and space, different suppressive mechanisms and cell populations that contribute to filarial hyporesponsiveness. L. sigmodontis infection recruited a F4/80+ population of alternatively activated macrophages that potently inhibited Ag-specific CD4+ T cell proliferative responses even in the presence of competent naive APC. T cell responsiveness was partially restored by neutralizing TGF-beta, but not by blocking IL-10 or CTLA-4 signaling. During prepatent infection, the macrophage population was restricted to the infection site. However, once infection became patent with systemic release of microfilariae, the suppressive macrophage activity extended peripherally into the tLN. In contrast, the hyporesponsive CD4+ T cell phenotype remained localized at the infection site, and the tLN CD4+ T cell population recovered full Ag responsiveness in the absence of suppressive macrophages. Filarial immunosuppression, therefore, evolves over time at sites increasingly distal to infection, and the mechanisms of filarial down-regulation are dependent on proximity to the infection site.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Antigen-Presenting Cells/immunology
- Antigen-Presenting Cells/parasitology
- Antigen-Presenting Cells/pathology
- Antigens, Differentiation/biosynthesis
- Antigens, Differentiation/physiology
- Antigens, Differentiation, Myelomonocytic/physiology
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/parasitology
- Cell Movement/immunology
- Cells, Cultured
- Female
- Filariasis/immunology
- Filariasis/parasitology
- Filariasis/pathology
- Filarioidea/growth & development
- Filarioidea/immunology
- Immune Tolerance
- Immunophenotyping
- Lymph Nodes/immunology
- Lymph Nodes/parasitology
- Lymph Nodes/pathology
- Macrophage Activation/immunology
- Mice
- Mice, Inbred BALB C
- Mice, Transgenic
- Molecular Sequence Data
- Pleural Cavity/immunology
- Pleural Cavity/parasitology
- Pleural Cavity/pathology
- T-Lymphocytes, Regulatory/cytology
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/parasitology
Collapse
Affiliation(s)
- Matthew D Taylor
- Institute of Immunology and Infection Research, Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
| | | | | | | | | |
Collapse
|
18
|
Schaer DJ, Schaer CA, Buehler PW, Boykins RA, Schoedon G, Alayash AI, Schaffner A. CD163 is the macrophage scavenger receptor for native and chemically modified hemoglobins in the absence of haptoglobin. Blood 2005; 107:373-80. [PMID: 16189277 DOI: 10.1182/blood-2005-03-1014] [Citation(s) in RCA: 217] [Impact Index Per Article: 11.4] [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: 02/04/2023] Open
Abstract
CD163 mediates the internalization of hemoglobin-haptoglobin (Hb-Hp) complexes by macrophages. Because Hp binding capacity is exhausted during severe hemolysis, an Hp-independent Hb-clearance pathway is presumed to exist. We demonstrate that Hb interacts efficiently with CD163 in the absence of Hp. Not only is Hb internalized into an endosomal compartment by CD163 as a result of active receptor-dependent endocytosis; it also inhibits the uptake of Hb-Hp complexes, suggesting a common receptor-binding site. Free Hb further induces heme oxygenase mRNA expression in CD163+ HEK293 cells, but not in CD163- cells. Additional evidence for Hp-independent Hb-CD163 interaction is provided by the demonstration that CD163 mediates the uptake of alpha alpha-DBBF crosslinked Hb, a chemically modified Hb that forms minimal Hp complexes. Moreover, certain modifications to Hb, such as polymerization or the attachment of specific functional groups (3 lysyl residues) to the beta-Cys93 can reduce or enhance this pathway of uptake. In human macrophages, Hp-complex formation critically enhances Hb uptake at low (1 microg/mL), but not at high (greater than 100 microg/mL), ligand concentrations, lending support for a concentration-dependent biphasic model of macrophage Hb-clearance. These results identify CD163 as a scavenger receptor for native Hb and small-molecular-weight Hb-based blood substitutes after Hp depletion.
Collapse
Affiliation(s)
- Dominik J Schaer
- Medical Clinic B Research Unit, University Hospital, CH-8091 Zurich, Switzerland.
| | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
Blood levels of inflammatory markers associated with endothelial dysfunction and atherosclerosis are increased in diabetic patients; the highest levels occur in poorly controlled diabetes. We investigated the activation state of peripheral blood monocytes in diabetes with respect to scavenger receptor (CD36) expression and monocyte chemoattractant protein-1, intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and peroxisome proliferator-activated receptors mRNA expression. CD14(+) monocytes were isolated from peripheral blood of type 1 and type 2 diabetic patients with good (HbA(1c) <7.0%) or poor (>9.4%) glycemic control and a group of nondiabetic subjects. Monocytes from diabetic subjects displayed increased CD36 cell surface expression (P < 0.0005) and increased uptake of oxidized LDL (P < 0.05). Monocyte chemoattractant protein-1 gene expression was increased in monocytes from both groups of diabetic subjects (P < 0.05). Both CD68 and peroxisome proliferator-activated receptor-gamma gene expression were increased in the poorly controlled diabetic group (P < 0.05 for each), whose monocytes also displayed increased attachment to endothelial monolayers (P < 0.0005 vs. nondiabetic control subjects). In poorly controlled diabetes, CD14(+) monocytes are functionally activated and show some of the differentiation markers associated with macrophages. These monocytes also demonstrate an increased ability for attachment to normal endothelial cells, one of the early stages in atherogenesis.
Collapse
Affiliation(s)
- Christine Cipolletta
- Department of Clinical Biochemistry and Metabolic Medicine, Queen's University Belfast, Institute of Clinical Science A, Grosvenor Road, Belfast BT12 6BJ, UK.
| | | | | | | |
Collapse
|
20
|
Tateno H, Crocker PR, Paulson JC. Mouse Siglec-F and human Siglec-8 are functionally convergent paralogs that are selectively expressed on eosinophils and recognize 6′-sulfo-sialyl Lewis X as a preferred glycan ligand. Glycobiology 2005; 15:1125-35. [PMID: 15972893 DOI: 10.1093/glycob/cwi097] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [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: 11/14/2022] Open
Abstract
Mouse sialic acid-binding immunoglobulin-like lectin F (Siglec-F) is an eosinophil surface receptor, which contains an immunoreceptor tyrosine-based inhibitory motif (ITIM) in its cytoplasmic domain, implicating it as a regulator of cell signaling as documented for other siglecs. Here, we show that the sialoside sequence 6'-sulfo-sLe(X) (Neu5Acalpha2-3[6-SO4] Galbeta1-4[Fucalpha1-3]GlcNAc) is a preferred ligand for Siglec-F. In glycan array analysis of 172 glycans, recombinant Siglec-F-Fc chimeras bound with the highest avidity to 6'-sulfo-sLe X. Secondary analysis showed that related structures, sialyl-Lewis X (sLe X) and 6-sulfo-sLe X containing 6-GlcNAc-SO4 showed much lower binding avidity, indicating significant contribution of 6-Gal-SO4 on Siglec-F binding to 6'-sulfo-sLe x. The lectin activity of Siglec-F on mouse eosinophils was "masked" by endogenous cis ligands and could be unmasked by treatment with sialidase. Unmasked Siglec-F mediated mouse eosinophil binding and adhesion to multivalent 6'-sulfo-sLe X structure, and these interactions were inhibited by anti-Siglec-F monoclonal antibody (mAb). Although there is no clear-cut human ortholog of Siglec-F, Siglec-8 is encoded by a paralogous gene that is expressed selectively by human eosinophils and has recently been found to recognize 6'-sulfo-sLe X. These observations suggest that mouse Siglec-F and human Siglec-8 have undergone functional convergence during evolution and implicate a role for the interaction of these siglecs with their preferred 6'-sulfo-sLe X ligand in eosinophil biology.
Collapse
MESH Headings
- Animals
- Antibodies, Monoclonal/pharmacology
- Antigens, CD/drug effects
- Antigens, CD/genetics
- Antigens, CD/physiology
- Antigens, Differentiation, B-Lymphocyte/drug effects
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/physiology
- Antigens, Differentiation, Myelomonocytic/drug effects
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/physiology
- CHO Cells
- Cricetinae
- Eosinophils/metabolism
- Humans
- Lectins/drug effects
- Lectins/genetics
- Lectins/physiology
- Lewis X Antigen/analogs & derivatives
- Ligands
- Mice
- Mice, Transgenic
- Microscopy, Fluorescence
- Neuraminidase/metabolism
- Oligosaccharides/metabolism
- Polysaccharides/chemistry
- Polysaccharides/metabolism
- Sialic Acid Binding Immunoglobulin-like Lectins
- Sialyl Lewis X Antigen/analogs & derivatives
Collapse
Affiliation(s)
- Hiroaki Tateno
- Department of Molecular Biology, The Scripps Research Institute, San Diego, CA 92037, USA
| | | | | |
Collapse
|
21
|
Sarrias MR, Grønlund J, Padilla O, Madsen J, Holmskov U, Lozano F. The Scavenger Receptor Cysteine-Rich (SRCR) domain: an ancient and highly conserved protein module of the innate immune system. Crit Rev Immunol 2005; 24:1-37. [PMID: 14995912 DOI: 10.1615/critrevimmunol.v24.i1.10] [Citation(s) in RCA: 201] [Impact Index Per Article: 10.6] [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: 11/13/2022]
Abstract
The Scavenger Receptor Cysteine-Rich (SRCR) domain is an ancient and highly conserved protein module of ~100-110 amino acids, which defines a superfamily (SRCR-SF) of either soluble or membrane-bound receptors expressed by hematopoietic and nonhematopoietic cells, at either embryonic or adult stages. The existence of two types of SRCR domains allows the division of the SRCR-SF into two groups. Members of group A contain SRCR domains with 6 cysteine residues and are encoded by two exons, whereas those of group B usually contain 8 cysteines and are encoded by a single exon. Group A members usually present as multidomain mosaic proteins containing single SRCR domains associated to other functional domains, such as enzymatic (protease) domains or collagenous regions. On the contrary, group B members generally present as proteins exclusively composed of tandem repeats of SRCR domains, with or without the presence of CUB and ZP domains thought to be involved in oligomerization but never associated to protease domains. Representatives of either group are found in different animal species, from low invertebrates (sponges) to high vertebrates (mammals). Although no unifying function has been defined for SRCR-SF members, accumulated data, together with the high degree of structural and phylogenetic conservation of SRCR domains indicates that they might subserve basic homeostatic functions, including innate immune defense.
Collapse
MESH Headings
- Agglutinins/chemistry
- Agglutinins/immunology
- Agglutinins/physiology
- Amino Acid Oxidoreductases/physiology
- Amino Acid Sequence
- Animals
- Antigens, CD/immunology
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/immunology
- Antigens, Differentiation, Myelomonocytic/physiology
- Antigens, Differentiation, T-Lymphocyte/immunology
- Antigens, Differentiation, T-Lymphocyte/physiology
- CD36 Antigens/immunology
- CD36 Antigens/physiology
- CD5 Antigens/immunology
- CD5 Antigens/physiology
- Calcium-Binding Proteins
- DNA-Binding Proteins
- Fibronectins/physiology
- Gene Expression Regulation
- Glycoproteins/chemistry
- Glycoproteins/immunology
- Glycoproteins/physiology
- Humans
- Immunity, Innate/immunology
- Immunity, Innate/physiology
- Ligands
- Membrane Proteins/immunology
- Membrane Proteins/physiology
- Models, Molecular
- Molecular Sequence Data
- Mucins/chemistry
- Mucins/immunology
- Mucins/physiology
- Protein Structure, Tertiary/genetics
- Protozoan Proteins/immunology
- Protozoan Proteins/physiology
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/physiology
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/genetics
- Receptors, Immunologic/immunology
- Receptors, Immunologic/physiology
- Receptors, Scavenger
- Scavenger Receptors, Class A
- Sequence Homology
- Structural Homology, Protein
- Tumor Suppressor Proteins
Collapse
Affiliation(s)
- Maria Rosa Sarrias
- Sevei d'Immunologia, Institut Clinic d'Infeccions i Immunologia (ICII), Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Hospital Clinic, Barcelona, Spain
| | | | | | | | | | | |
Collapse
|
22
|
Avril T, Floyd H, Lopez F, Vivier E, Crocker PR. The membrane-proximal immunoreceptor tyrosine-based inhibitory motif is critical for the inhibitory signaling mediated by Siglecs-7 and -9, CD33-related Siglecs expressed on human monocytes and NK cells. J Immunol 2005; 173:6841-9. [PMID: 15557178 DOI: 10.4049/jimmunol.173.11.6841] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [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
Siglec-7 and Siglec-9 are two members of the recently characterized CD33-related Siglec family of sialic acid binding proteins and are both expressed on human monocytes and NK cells. In addition to their ability to recognize sialic acid residues, these Siglecs display two conserved tyrosine-based motifs in their cytoplasmic region similar to those found in inhibitory receptors of the immune system. In the present study, we use the rat basophilic leukemia (RBL) model to examine the potential of Siglecs-7 and -9 to function as inhibitory receptors and investigate the molecular basis for this. We first demonstrate that Siglecs-7 and -9 are able to inhibit the FcepsilonRI-mediated serotonin release from RBL cells following co-crosslinking. In addition, we show that under these conditions or after pervanadate treatment, Siglecs-7 and -9 associate with the Src homology region 2 domain-containing phosphatases (SHP), SHP-1 and SHP-2, both in immunoprecipitation and in fluorescence microscopy experiments using GFP fusion proteins. We then show by site-directed mutagenesis that the membrane-proximal tyrosine motif is essential for the inhibitory function of both Siglec-7 and -9, and is also required for tyrosine phosphorylation and recruitment of SHP-1 and SHP-2 phosphatases. Finally, mutation of the membrane-proximal motif increased the sialic acid binding activity of Siglecs-7 and -9, raising the possibility that "inside-out" signaling may occur to regulate ligand binding.
Collapse
MESH Headings
- Amino Acid Motifs/genetics
- Amino Acid Motifs/immunology
- Amino Acid Sequence
- Animals
- Antigens, CD/biosynthesis
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/biosynthesis
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Cell Line, Tumor
- Cell Membrane/genetics
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Cross-Linking Reagents/metabolism
- Down-Regulation/genetics
- Down-Regulation/immunology
- Humans
- Intracellular Signaling Peptides and Proteins
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Lectins/biosynthesis
- Lectins/genetics
- Lectins/metabolism
- Lectins/physiology
- Molecular Sequence Data
- Monocytes/immunology
- Monocytes/metabolism
- Mutagenesis, Site-Directed
- Protein Transport
- Protein Tyrosine Phosphatase, Non-Receptor Type 11
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/metabolism
- Rats
- Receptors, IgE/antagonists & inhibitors
- Receptors, IgE/physiology
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Serotonin/metabolism
- Serotonin Antagonists/pharmacology
- Sialic Acid Binding Ig-like Lectin 3
- Sialic Acid Binding Immunoglobulin-like Lectins
- Sialic Acids/metabolism
- Signal Transduction/genetics
- Signal Transduction/immunology
- Tyrosine/metabolism
Collapse
Affiliation(s)
- Tony Avril
- Division of Cell Biology and Immunology, The Wellcome Trust Biocentre, University of Dundee, Dundee, United Kingdom
| | | | | | | | | |
Collapse
|
23
|
Abstract
Siglec-7 (p70/AIRM) and Siglec-9 are "CD33"-related siglecs expressed on natural killer (NK) cells and subsets of peripheral T cells. Like other inhibitory NK cell receptors, they contain immunoglobulin receptor family tyrosine-based inhibitory motifs in their cytoplasmic domains, and Siglec-7 has been demonstrated to negatively regulate NK cell activation. Based on reports of the presence of these siglecs on T cells, we sought to determine if they are capable of modulating T cell receptor (TCR) signaling using Jurkat T cells stably and transiently transfected with Siglec-7 or Siglec-9. Following either pervanadate stimulation or TCR engagement, both Siglecs exhibited increased tyrosine phosphorylation and recruitment of SHP-1. Effects of Siglec-7 and -9 were also evident in downstream events in the signaling pathway. Both siglecs reduced phosphorylation of Tyr319 on ZAP-70, known to play a pivotal role in up-regulation of gene transcription following TCR stimulation. There was also a corresponding decreased transcriptional activity of nuclear factor of activated T cells (NFAT) as determined using a luciferase reporter gene. Like all siglecs, Siglec-7 and -9 recognize sialic acid-containing glycans of glycoproteins and glycolipids as ligands. Mutation of the conserved Arg in the ligand binding site of Siglec-7 (Arg124) or Siglec-9 (Arg120) resulted in reduced inhibitory function in the NFAT/luciferase transcription assay, suggesting that ligand binding is required for optimal inhibition of TCR signaling. The combined results demonstrate that both Siglec-7 and Siglec-9 are capable of negative regulation of TCR signaling and that ligand binding is required for optimal activity.
Collapse
MESH Headings
- Amino Acid Motifs
- Antigens, CD/chemistry
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Blotting, Western
- Cell Separation
- Cytoplasm/metabolism
- Dose-Response Relationship, Drug
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- Flow Cytometry
- Genes, Reporter
- Humans
- Immunoprecipitation
- Jurkat Cells
- Lectins/metabolism
- Lectins/physiology
- Ligands
- Luciferases/metabolism
- Microscopy, Fluorescence
- Models, Biological
- Phosphorylation
- Protein Binding
- Protein Structure, Tertiary
- Protein-Tyrosine Kinases/chemistry
- Sialic Acid Binding Ig-like Lectin 3
- Sialic Acid Binding Immunoglobulin-like Lectins
- Signal Transduction
- T-Lymphocytes/metabolism
- Time Factors
- Transcription, Genetic
- Transcriptional Activation
- Transfection
- Tyrosine/chemistry
- Vanadates/chemistry
- ZAP-70 Protein-Tyrosine Kinase
Collapse
Affiliation(s)
- Yuzuru Ikehara
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | | | | |
Collapse
|
24
|
Chamorro S, Revilla C, Gómez N, Alvarez B, Alonso F, Ezquerra A, Domínguez J. In vitro differentiation of porcine blood CD163− and CD163+ monocytes into functional dendritic cells. Immunobiology 2004; 209:57-65. [PMID: 15481141 DOI: 10.1016/j.imbio.2004.02.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [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: 12/21/2022]
Abstract
Swine monocytes constitute a heterogeneous cell population containing subsets with distinct functional capacities or representing different maturational stages. Based on the expression of CD163, we have recently identified two monocyte subpopulations. In this study, we investigate the ability of both CD163- and CD163+ monocytes to differentiate into dendritic cells (DCs) in the presence of GM-CSF and IL-4. Monocyte differentiation into DC is accompanied by an up-regulation of the expression of swine leukocyte antigen (SLA) I, SLA II and CD80/86 molecules, and a decrease in the expression of CD14, CD16 and CD163. These DC express the pan-myeloid marker SWC3 and display typical dendritic cytoplasmic projections. When monocytes are split into CD163+ and CD163- cells, both subsets give rise to DC. However, compared to CD163- monocyte-derived DC (MoDC), CD163+ MoDC appear to have reached a more advanced stage of maturation, expressing higher levels of SLA II and CD80/86 and inducing more efficiently proliferation of T cells to recall antigens and alloantigens.
Collapse
Affiliation(s)
- Sonia Chamorro
- Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Ctra de la Coruña, Km 7.5, 28040 Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
25
|
Jedema I, Barge RMY, van der Velden VHJ, Nijmeijer BA, van Dongen JJM, Willemze R, Falkenburg JHF. Internalization and cell cycle-dependent killing of leukemic cells by Gemtuzumab Ozogamicin: rationale for efficacy in CD33-negative malignancies with endocytic capacity. Leukemia 2004; 18:316-25. [PMID: 14614514 DOI: 10.1038/sj.leu.2403205] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [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: 11/09/2022]
Abstract
Multicenter phase II trials with Gemtuzumab Ozogamicin (GO/Mylotarg), consisting of a CD33 antibody linked to the cytotoxic drug calicheamicin, have shown a 30% overall response rate in relapsed acute myeloid leukemia patients. However, no clear correlation was observed between CD33 expression on leukemic blasts and response to GO therapy. We analyzed the CD33 specificity of GO-induced cell death and the effect of GO on CD33-negative malignancies. We demonstrate that lysis induced by clinically relevant GO concentrations is partially CD33 mediated, and that efficient non-CD33-mediated GO uptake can occur via endocytosis. In agreement with these results, we observed GO-mediated death of human CD33-negative acute lymphoblastic leukemia cells both in vitro and in vivo in an NOD/SCID mouse model. Finally, sensitivity to GO-induced cell death was at least partially determined by the activation status of leukemic cells, with cells in activated phases of the cell cycle being most effective in both CD33-specific GO internalization, renewed expression of CD33 molecules, and non-CD33-mediated GO uptake via endocytosis. In conclusion, these data provide mechanistic insight into the efficacy of GO in CD33-positive as well as in CD33-negative malignancies with endocytic capacity, and provide a rationale for the use of GO in the treatment of malignancies with endocytic capacity.
Collapse
MESH Headings
- Adult
- Aged
- Aminoglycosides/administration & dosage
- Aminoglycosides/pharmacokinetics
- Aminoglycosides/pharmacology
- Aminoglycosides/therapeutic use
- Antibodies, Monoclonal/administration & dosage
- Antibodies, Monoclonal/pharmacokinetics
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Humanized
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/physiology
- Cell Cycle
- Cell Death/drug effects
- Cell Line, Tumor
- Dose-Response Relationship, Drug
- Endocytosis
- Female
- Gemtuzumab
- HL-60 Cells
- Humans
- Leukemia/immunology
- Leukemia/pathology
- Leukemia, Myeloid/immunology
- Leukemia, Myeloid/pathology
- Lymphocyte Activation/drug effects
- Male
- Middle Aged
- Mutagens/pharmacology
- Precursor Cell Lymphoblastic Leukemia-Lymphoma/immunology
- Precursor Cell Lymphoblastic Leukemia-Lymphoma/pathology
- Retrospective Studies
- Sialic Acid Binding Ig-like Lectin 3
Collapse
Affiliation(s)
- I Jedema
- Laboratory of Experimental Hematology, Department of Hematology, Leiden University Medical Center, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
The recently described hemoglobin scavenger receptor CD163 mediates the endocytosis of hemoglobin:haptoglobin (Hb:Hp) complexes and thereby counters Hb-induced oxidative tissue damage after hemolysis. Although CD163 has been indirectly associated with antiinflammatory and atheroprotective activity, no ligand-receptor-effector pathway has yet been described for this receptor. To understand the significance of CD163 and more clearly define downstream pathways linked to inflammatory resolution, we studied the expression and function of CD163 in human monocytes/macrophages using both in vitro and in vivo models. Differentiation of human blood monocytes into macrophages either by in vitro culture or in resolving cantharidin-induced skin blisters led to an equivalent increase (>15x) in CD163 expression. Elevated CD163 levels were also noted on circulating monocytes in cardiac surgical patients during the resolution phase of the systemic inflammatory response to cardiopulmonary bypass surgery. In each case, binding of Hb:Hp to CD163-bearing cells elicited potent interleukin-10 secretion, and this was inhibited by the anti-CD163 antibody RM3/1. Release of interleukin-10, in turn, induced heme oxygenase-1 stress protein synthesis via an autocrine mechanism. Such induction of heme oxygenase-1 was observed in vivo 24 to 48 hours after the onset of cardiopulmonary bypass surgery. These results identify novel antiinflammatory and cytoprotective effector pathways in human monocytes/macrophages related to Hb scavenging and metabolism, which may have relevance in atheroprotection, wound healing, and patient recovery postoperatively.
Collapse
Affiliation(s)
- P Philippidis
- British Heart Foundation Cardiovascular Medicine Unit, National Heart and Lung Institute, Faculty of Medicine, Imperial College, Hammersmith Hospital, Du Cane Rd, London W12 0NN, UK
| | | | | | | | | | | | | |
Collapse
|
27
|
Abstract
CD163 is a hemoglobin scavenger receptor exclusively expressed in the monocyte-macrophage system. A particularly high expression is seen in macrophages of the 'alternative activation' phenotype playing a major role in dampening the inflammatory response and in scavenging components of damaged cells. CD163-mediated endocytosis of haptoglobin-hemoglobin complexes formed upon red blood cell hemolysis leads to lysosomal degradation of the ligand protein and metabolism of heme by cytosolic heme oxygenase. In accordance with a stimulated expression of haptoglobin, CD163 and heme oxygenase-1 during the acute phase response, there is evidence that this metabolic pathway regulates inflammation by at least two ways. First, CD163 is reported to directly induce intracellular signaling leading to secretion of anti-inflammatory cytokines. Second and perhaps even more important, the CD163-mediated delivery of hemoglobin to the macrophage may fuel an anti-inflammatory response because heme metabolites have potent anti-inflammatory effects. In addition to being present on the macrophage surface, continuous shedding of the extracellular domain of CD163 leads to substantial amounts of soluble receptor in plasma. An increased shedding is due to inflammatory stimuli, and a role for soluble CD163 in immune suppression has been proposed. Furthermore, recent data indicate that soluble CD163 may be a valuable diagnostic parameter for monitoring macrophage activation in inflammatory conditions.
Collapse
MESH Headings
- Antigens, CD/blood
- Antigens, CD/immunology
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/blood
- Antigens, Differentiation, Myelomonocytic/immunology
- Antigens, Differentiation, Myelomonocytic/physiology
- Cytokines/immunology
- Cytokines/metabolism
- Cytokines/physiology
- Hemoglobins/metabolism
- Humans
- Macrophages/immunology
- Macrophages/metabolism
- Macrophages/physiology
- Monocytes/immunology
- Monocytes/metabolism
- Monocytes/physiology
- Receptors, Cell Surface/blood
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/physiology
- Signal Transduction
Collapse
Affiliation(s)
- Søren K Moestrup
- Department of Medical Biochemistry, University of Aarhus, Denmark.
| | | |
Collapse
|
28
|
Matsuzaki J, Tsuji T, Chamoto K, Takeshima T, Sendo F, Nishimura T. Successful elimination of memory-type CD8+ T cell subsets by the administration of anti-Gr-1 monoclonal antibody in vivo. Cell Immunol 2003; 224:98-105. [PMID: 14609575 DOI: 10.1016/j.cellimm.2003.08.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [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: 11/29/2022]
Abstract
During investigating the expression of Gr-1 antigen on various subsets of mouse spleen cells, we found that Gr-1 was expressed on memory-type CD8(+)CD44(high)CD62L(high) T cells in addition to granulocytes. Intraperitoneal administration of anti-Gr-1 mAb caused almost complete elimination of Ly-6C(+) memory-type CD8(+) T cells as well as Ly-6G(+) granulocytes. Anti-Gr-1 mAb-treated mouse spleen cells exhibited greatly reduced IFN-gamma production in response to anti-CD3 mAb both in vitro and in vivo. This reduced cytokine production appeared to be derived from elimination of IFN-gamma-producing Gr-1(+)CD8(+) T cells. Indeed, CD8(+) T cells with IFN-gamma-producing activity and cytotoxicity were generated from isolated Gr-1(+)CD8(+) cells but not from Gr-1(-)CD8(+) T cells. We also demonstrated that therapeutic effect of MBL-2 tumor-immunized spleen cells was greatly reduced by anti-Gr-1 mAb-treatment. Thus, we initially demonstrated that anti-Gr-1 mAb might become a good tool to investigate a precise role for memory-type CD8(+) T cells in vivo.
Collapse
Affiliation(s)
- Junko Matsuzaki
- Division of Immunoregulation, Section of Disease Control, Institute for Genetic Medicine, Hokkaido University, 060-0815, Hokkaido, Sapporo, Japan
| | | | | | | | | | | |
Collapse
|
29
|
Biassoni R, Cantoni C, Marras D, Giron-Michel J, Falco M, Moretta L, Dimasi N. Human natural killer cell receptors: insights into their molecular function and structure. J Cell Mol Med 2003; 7:376-87. [PMID: 14754506 PMCID: PMC6740120 DOI: 10.1111/j.1582-4934.2003.tb00240.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
NK cells express receptors characterized by opposite functions that finely regulate their activities. Among inhibitory receptors, some are specific for different groups of MHC class I alleles, while others are still orphan receptors. On the contrary, various activating receptors are involved in the triggering of NK-mediated natural cytotoxicity. In general, their engagement induces human NK cells to kill target cells that are either HLA class I-negative or -deficient. Thus, the process of NK cell triggering mediated by Natural Cytotoxicity Receptors can be mainly considered as a non MHC-restricted mechanism. Here, a brief description of the molecular nature of these receptors, as well as, of their 3D-structures and of the implications for ligand recognition, is given.
Collapse
MESH Headings
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/physiology
- Chromosomes, Human, Pair 17/genetics
- Cytotoxicity, Immunologic
- Humans
- Killer Cells, Natural/immunology
- Lectins/chemistry
- Lectins/genetics
- Lectins/physiology
- Models, Immunological
- Models, Molecular
- Multigene Family
- Natural Cytotoxicity Triggering Receptor 1
- Natural Cytotoxicity Triggering Receptor 2
- Psoriasis/genetics
- Psoriasis/immunology
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Receptors, KIR
- Receptors, Natural Killer Cell
Collapse
Affiliation(s)
- R Biassoni
- Instituto Giannina Gaslini, Genova, Italy.
| | | | | | | | | | | | | |
Collapse
|
30
|
Sánchez-Torres C, Gómez-Puertas P, Gómez-del-Moral M, Alonso F, Escribano JM, Ezquerra A, Domínguez J. Expression of porcine CD163 on monocytes/macrophages correlates with permissiveness to African swine fever infection. Arch Virol 2003; 148:2307-23. [PMID: 14648288 DOI: 10.1007/s00705-003-0188-4] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2003] [Revised: 01/01/2003] [Accepted: 06/03/2003] [Indexed: 11/29/2022]
Abstract
Monocytes-macrophages, the target cells of African swine fever virus (ASFV) are highly heterogeneous in phenotype and function. In this study, we have investigated the correlation between the phenotype of specific populations of porcine macrophages and their permissiveness to ASFV infection. Bone marrow cells and fresh blood monocytes were less susceptible to in vitro infection by ASFV than more mature cells, such as alveolar macrophages. FACS analyses of monocytes using a panel of mAbs specific for porcine monocyte/macrophages showed that infected cells had a more mature phenotype, expressing higher levels of several macrophage specific markers and SLA II antigens. Maturation of monocytes led to an increase in the percentage of infected cells, which correlated with an enhanced expression of CD163. Separation of CD163+ and CD163- monocytes demonstrated the specific sensitivity of the CD163+ subset to ASFV infection. In vivo experiments also showed a close correlation between CD163 expression and virus infection. Finally, mAb 2A10 and, in a lower extent, mAb 4E9 were able to inhibit, in a dose-dependent manner, both ASFV infection and viral particle binding to alveolar macrophages. Altogether, these results strongly suggest a role of CD163 in the process of infection of porcine monocytes/macrophages by ASFV.
Collapse
Affiliation(s)
- C Sánchez-Torres
- Dpto. Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Ctra de la Coruña km. 7.5, 28040 Madrid, Spain
| | | | | | | | | | | | | |
Collapse
|
31
|
Yamaji T, Hashimoto Y. [Functions of sialic acids-binding lectins, Siglecs]. Tanpakushitsu Kakusan Koso 2003; 48:1098-105. [PMID: 12807015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
MESH Headings
- Animals
- Antigens, CD/chemistry
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Humans
- Immune System
- Lectins/chemistry
- Lectins/metabolism
- Lectins/physiology
- N-Acetylneuraminic Acid/metabolism
- N-Acetylneuraminic Acid/physiology
- Protein Binding
- Receptors, Immunologic
- Sialic Acid Binding Ig-like Lectin 3
- Sialic Acid Binding Immunoglobulin-like Lectins
Collapse
|
32
|
Nicoll G, Avril T, Lock K, Furukawa K, Bovin N, Crocker PR. Ganglioside GD3 expression on target cells can modulate NK cell cytotoxicity via siglec-7-dependent and -independent mechanisms. Eur J Immunol 2003; 33:1642-8. [PMID: 12778482 DOI: 10.1002/eji.200323693] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.5] [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: 11/08/2022]
Abstract
Siglec-7 is a sialic acid binding receptor with inhibitory potential, expressed on human NK cells and monocytes. It has an unusual binding preference for alpha2,8-linked disialic acids, such as those displayed by ganglioside GD3. Here we have investigated whether siglec-7-GD3 interactions are able to modulate NK cell cytotoxicity. Using synthetic polyacrylamide glycoprobes, siglec-7 was found to be masked at the NK cell surface but it could be unmasked by sialidase treatment of NK cells. GD3 synthase-transfected P815 target cells expressed high levels of GD3 and bound strongly to recombinant siglec-7-Fc protein. Surprisingly, GD3 synthase-transfected P815 cells were killed more effectively by untreated cells in a siglec-7-independent manner. However, following sialidase treatment of NK cells, a siglec-7-dependent inhibition of killing was observed. These findings have important implications for NK cell cytotoxicity against tumor cells like melanoma that express high levels of GD3 ganglioside.
Collapse
MESH Headings
- Animals
- Antigens, CD/chemistry
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/physiology
- Binding Sites
- Cytotoxicity, Immunologic/physiology
- Disaccharides/metabolism
- Gangliosides/physiology
- Humans
- Immune Tolerance/physiology
- Killer Cells, Natural/drug effects
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Lectins/chemistry
- Lectins/physiology
- Mastocytoma/pathology
- Mice
- Neuraminidase/metabolism
- Neuraminidase/pharmacology
- Protein Binding
- Recombinant Fusion Proteins/metabolism
- Sialic Acids/metabolism
- Sialyltransferases/genetics
- Sialyltransferases/metabolism
- Transfection
- Tumor Cells, Cultured/chemistry
- Tumor Cells, Cultured/immunology
- Tumor Escape
Collapse
Affiliation(s)
- Gavin Nicoll
- The School of Life Sciences, Wellcome Trust Biocentre, University of Dundee, GB
| | | | | | | | | | | |
Collapse
|
33
|
Brinkman-Van der Linden ECM, Angata T, Reynolds SA, Powell LD, Hedrick SM, Varki A. CD33/Siglec-3 binding specificity, expression pattern, and consequences of gene deletion in mice. Mol Cell Biol 2003; 23:4199-206. [PMID: 12773563 PMCID: PMC156146 DOI: 10.1128/mcb.23.12.4199-4206.2003] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [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: 11/20/2022] Open
Abstract
Mouse CD33/Siglec-3 (mCD33) is the apparent ortholog of human CD33/Siglec-3 (hCD33), a member of the Siglec (sialic acid-binding Ig superfamily lectin) family of sialic acid-recognizing cell-surface lectins. We examined the binding specificity and expression pattern of mCD33 and explored its functions by generating mice deficient in this molecule. Like hCD33, mCD33 is expressed on myeloid precursors in the bone marrow, albeit mostly in the more mature stages of the granulocytic lineage. Moreover, unlike hCD33, mCD33 in peripheral blood is primarily expressed on granulocytes. Also, unlike hCD33, mCD33 did not bind to alpha2-3- or alpha2-6-linked sialic acids on lactosamine units. Instead, it showed distinctive sialic acid-dependent binding only to the short O-linked glycans of certain mucins and weak binding to the sialyl-Tn epitope. Binding was enhanced by removal of 9-O-acetyl groups and attenuated by truncation of the glycerol-like side chain of sialic acids. Mice deficient in CD33 were viable and fertile in a controlled-access specific-pathogen-free vivarium, showed no major morphological or histological abnormalities, had no changes in bone marrow or peripheral leukocyte subpopulations, and had very minor differences in biochemical and erythrocyte parameters. Cellular responses to intraperitoneally injected proinflammatory stimulants, as well as subsequent interleukin-6 secretion, were also apparently unaffected. These results indicate substantial species differences in CD33 expression patterns and ligand recognition and suggest functional degeneracy between mCD33 and the other CD33-related Siglec proteins expressed on cells of the myeloid lineage.
Collapse
MESH Headings
- Animals
- Antigens, CD/biosynthesis
- Antigens, CD/metabolism
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/biosynthesis
- Antigens, Differentiation, Myelomonocytic/metabolism
- Antigens, Differentiation, Myelomonocytic/physiology
- Biotinylation
- COS Cells
- Caseins/metabolism
- Cell Lineage
- Enzyme-Linked Immunosorbent Assay
- Epitopes
- Exons
- Gene Deletion
- Granulocytes/metabolism
- Hematopoietic Stem Cells/metabolism
- Humans
- Inflammation
- Lipopolysaccharides/metabolism
- Mice
- Mice, Inbred C57BL
- Models, Genetic
- N-Acetylneuraminic Acid/metabolism
- Protein Binding
- Recombinant Fusion Proteins/metabolism
- Sialic Acid Binding Ig-like Lectin 3
Collapse
|
34
|
Abstract
OBJECTIVES Acute myeloid leukemia (AML) cells express the cell surface antigen CD33 that can function as a downregulator of cell growth, mediating growth arrest and apoptosis. The protein kinase Syk is an essential element in several cascades coupling certain antigen receptors to cell responses. Recently we reported that CD33 recruits Syk for its signaling in AML cell lines. In this study, we further investigated the mechanism(s) of Syk engagement in CD33 signaling in primary AML samples. METHODS We investigated 25 primary AML samples for their proliferative response (3H-thymidine incorporation) and biochemical changes (Western blot analysis) to anti-CD33 mAb treatment. RESULTS Proliferation studies demonstrated that 14 (56%) of AML samples were responsive (R) while 11 (44%) were nonresponsive (n-R) to inhibitory antibody activity. Seven of 25 AML samples (28%) expressed undetectable levels of Syk. However, cells from two of these patients expressed the ZAP-70 protein kinase. In Syk/ZAP-70(+) samples, CD33 ligation inhibited proliferation in 70% of cases, while none of the Syk/ZAP-70(-) samples was responsive. There were significant biochemical differences between responder and nonresponder AML populations. In responder samples, CD33 ligation induced phosphorylation of CD33 andSyk and formation of the CD33/Syk complex. In nonresponder samples, CD33 was not phosphorylated, and Syk was in complex with the SHP-1 protein phosphatase constitutively. CONCLUSIONS Syk is an important component in the regulation of proliferation in AML cells. The differential response of AML cells to CD33 ligation is associated with the level of the Syk expression.
Collapse
Affiliation(s)
- Larisa Balaian
- Department of Medicine and Cancer Center, University of California, San Diego School of Medicine, La Jolla, Calif., USA
| | | | | |
Collapse
|
35
|
Erickson-Miller CL, Freeman SD, Hopson CB, D'Alessio KJ, Fischer EI, Kikly KK, Abrahamson JA, Holmes SD, King AG. Characterization of Siglec-5 (CD170) expression and functional activity of anti-Siglec-5 antibodies on human phagocytes. Exp Hematol 2003; 31:382-8. [PMID: 12763136 DOI: 10.1016/s0301-472x(03)00046-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [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: 11/20/2022]
Abstract
OBJECTIVE The Siglec family of proteins consists of at least 10 members with immunoglobulin and lectin domains and with similar sialic acid-binding properties. Many Siglec family members are expressed on hematopoietic cells and are involved in cell/cell interactions. Some family members are suspected of regulating cellular processes through specific signaling pathways. Monoclonal antibodies were generated against specific epitopes of Siglec-5 (CD170) and were used to determine expression of Siglec-5 on normal blood and marrow cells and cell lines. The antibodies also were used to elucidate functional activity for Siglec-5 on blood neutrophils. METHODS Flow cytometry and ELISA were used to determine the specificity of the monoclonal antibodies for Siglec-5 and to determine expression patterns. Chemiluminescence assays were employed to measure the oxidative burst activity of whole blood or purified neutrophils following treatment with the anti-Siglec-5 antibodies. RESULTS Cell surface expression analysis demonstrated that the protein was expressed on gated human neutrophil and monocyte populations, both in the blood and bone marrow. Expression on neutrophils was enhanced by one-hour treatment with fMLP or TNF-alpha. Epitope-specific anti-Siglec-5 monoclonal antibodies did not directly activate human neutrophils; however, antibody binding augmented neutrophil oxidative burst activity as determined by fMLP-induced luminol-dependent chemiluminescence. CONCLUSION Data demonstrating expression of Siglec-5 on cells of the myelomonocytic lineage and alteration of its expression by inflammatory stimuli suggest a role for this protein in cell/cell interactions following microbial exposure.
Collapse
Affiliation(s)
- Connie L Erickson-Miller
- Department of Molecular Virology and Host Defense, SmithKline Beecham Pharmaceuticals, Collegeville, PA, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Abstract
Murine macrosialin (MS), a scavenger receptor family member, is a heavily glycosylated transmembrane protein expressed predominantly in macrophage late endosomes. MS is also found on the cell surface where it is suggested, on the basis of ligand blotting, to bind oxidized LDL (oxLDL). Here we report on the regulation of MS by an atherogenic high-fat diet and oxLDL, and on the inability of MS in transfected cells to bind oxLDL. MS expression was markedly increased in the livers of atherosclerosis-susceptible C57BL/6 and atherosclerosis-resistant C3H/HeJ mice fed an atherogenic high-fat diet. In resident-mouse peritoneal macrophages, treatment with oxLDL upregulated MS mRNA and protein expression 1.5- to 3-fold. MS, overexpressed in COS-7 cells through adenovirus mediated gene transfer, bound oxLDL by ligand blotting. However, no binding of oxLDL to MS was observed in intact transfected COS-7 and Chinese hamster ovary cells, despite significant cell surface expression of MS. Furthermore, inhibition of MS through gene silencing did not affect the binding of oxLDL to macrophages. We conclude that although MS expression in macrophages and Kupffer cells is responsive to a proatherogenic inflammatory diet and to oxLDL, MS does not function as an oxLDL receptor on the cell surface.
Collapse
MESH Headings
- Animals
- Antigens, CD/genetics
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/physiology
- Cell Line
- Diet, Atherogenic
- Gene Silencing
- Humans
- Lipoproteins, LDL/metabolism
- Liver/chemistry
- Mice
- Mice, Inbred Strains
- Oxidation-Reduction
- Protein Binding
- Receptors, LDL
- Receptors, Oxidized LDL
- Scavenger Receptors, Class E
- Transfection
Collapse
Affiliation(s)
- Maria C de Beer
- Department of Internal Medicine, University of Kentucky Medical Center, Lexington 40536, USA
| | | | | | | | | |
Collapse
|
37
|
Frings W, Dreier J, Sorg C. Only the soluble form of the scavenger receptor CD163 acts inhibitory on phorbol ester-activated T-lymphocytes, whereas membrane-bound protein has no effect. FEBS Lett 2002; 526:93-6. [PMID: 12208511 DOI: 10.1016/s0014-5793(02)03142-3] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [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: 11/21/2022]
Abstract
The extracellular moiety of the hemoglobin/haptoglobin scavenger receptor CD163 (RM3/1 antigen) can be shed from monocytes and is a normal plasma component. We found that in a dose-dependent manner soluble CD163 induces a decrease in CD69 expression, a reduced [(3)H]thymidine uptake and a down-regulated matrix metalloproteinase-9 RNA expression in phorbol myristate acetate-stimulated T-cells. Co-culturing T-cells on transgenic fibroblasts, expressing membrane-bound CD163, yielded no differences compared to culture on non-transfected cells. We conclude that CD163 has at least two distinct functions: the clearance of hemoglobin in its cell-bound form and participation in anti-inflammation as a soluble factor, exhibiting cytokine-like functions.
Collapse
MESH Headings
- Antigens, CD/genetics
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/isolation & purification
- Antigens, Differentiation, Myelomonocytic/physiology
- Antigens, Differentiation, T-Lymphocyte/genetics
- Apoptosis
- Chromatography, Affinity
- Gene Expression Regulation
- Humans
- Lectins, C-Type
- Lymphocyte Activation/drug effects
- Lymphocyte Activation/physiology
- Matrix Metalloproteinase 3/genetics
- Matrix Metalloproteinase 9/genetics
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/isolation & purification
- Receptors, Cell Surface/physiology
- Recombinant Proteins/isolation & purification
- Recombinant Proteins/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- T-Lymphocytes/drug effects
- T-Lymphocytes/immunology
- Tetradecanoylphorbol Acetate
Collapse
Affiliation(s)
- Werner Frings
- Institute of Experimental Dermatology, Westfälische Wilhelms-Universität, Münster, Germany.
| | | | | |
Collapse
|
38
|
Abstract
The plasma protein haptoglobin and the endocytic hemoglobin receptor HbSR/CD163 are key molecules in the process of removing hemoglobin released from ruptured erythrocytes. Hemoglobin in plasma is instantly bound with high affinity to haptoglobin--an interaction leading to the recognition of the complex by HbSR/CD163 and endocytosis in macrophages. The haptoglobin-dependent HbSR/CD163 scavenging system for hemoglobin clearance prevents toxic effects of hemoglobin in plasma and kidney and explains the decrease in the haptoglobin plasma concentration in patients with accelerated hemolysis. The HbSR/CD163 activity may be of quantitative importance for iron uptake in macrophages in general and for some iron-associated pathological processes, e.g. the atherogenesis-promoting oxidation of LDL leading to foam cell formation and apoptosis in the vessel wall.
Collapse
Affiliation(s)
- M Madsen
- Department of Medical Biochemistry, University of Aarhus, Denmark
| | | | | |
Collapse
|
39
|
Kowalski ML, Grzegorczyk J, Pawliczak R, Kornatowski T, Wagrowska-Danilewicz M, Danilewicz M. Decreased apoptosis and distinct profile of infiltrating cells in the nasal polyps of patients with aspirin hypersensitivity. Allergy 2002; 57:493-500. [PMID: 12028114 DOI: 10.1034/j.1398-9995.2002.13508.x] [Citation(s) in RCA: 51] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Patients with aspirin-hypersensitive rhinosinusitis/asthma suffer from a severe form of hyperplastic rhinosinusitis with recurrent polyposis. We aimed to assess the presence of apoptotic cells in nasal polyps from aspirin-hypersensitive (AH) and aspirin-tolerant (AT) patients with rhinosinusitis as related to the characteristics of local inflammation. METHODS Nasal polyps obtained from 16 AH patients and 36 AT patients (17 atopic and 19 nonatopic) were stained for eosinophils and metachromatic cells, and in parallel immunocytochemistry was performed to detect CD45RO+, HLA-DR+, CD8+ and CD68+ positive cells. Apoptotic cells were detected by a nick-end labelling technique, TUNEL. RESULTS The density of apoptotic cells in AH polyps (5.5 + 1.5 cells/mm2) was significantly lower as compared to both atopic (18.7 + 3.8 cells/mm2; P < 0.02;) and nonatopic (21.3 + 5.2 cells/mm2; P < 0.01) AT polyps. The number of eosinophils, mast cells, and CD45RO+ cells were significantly increased in AH compared to AT polyps (P < 0.001), and the density of HLA-DR+ cells in AH patients was higher than in nonatopic (P < 0.02), but not in atopic AT patients. While in AH patients the duration of rhinosinusitis correlated inversely with the number of apoptotic cells (r = - 0.67; P < 0.04), in contrast, in AT atopic patients the duration of rhinosinusitis showed positive correlation with apoptosis (r = 0.89; P < 0.003). CONCLUSIONS We conclude, that decreased apoptosis of inflammatory cells in nasal polyps from ASA-hypersensitive patients, reflects a distinct mechanisms of local inflammation and may be related to persistence and severity of the disease in these patients.
Collapse
Affiliation(s)
- M L Kowalski
- Department of Clinical Immunology and Allergy, Faculty of Medicine, Medical University, Lódz, Poland
| | | | | | | | | | | |
Collapse
|
40
|
Lang R, Rutschman RL, Greaves DR, Murray PJ. Autocrine deactivation of macrophages in transgenic mice constitutively overexpressing IL-10 under control of the human CD68 promoter. J Immunol 2002; 168:3402-11. [PMID: 11907098 DOI: 10.4049/jimmunol.168.7.3402] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IL-10 plays an essential role in blocking cytokine production by activated macrophages. To analyze the consequences of enforced expression of IL-10 by macrophages on innate and adaptive immune responses, we generated transgenic mice (macIL-10tg mice) expressing an epitope-tagged IL-10 (Flag-IL-10) under control of the human CD68 promoter. Expression of Flag-IL-10 was constitutive and restricted to macrophages, as shown by sorting splenocyte cell populations and intracellular staining for IL-10. Transgenic macrophages displayed suppressed production of TNF-alpha and IL-12 upon stimulation with LPS. When macIL-10tg mice were challenged with LPS, serum levels of proinflammatory cytokines were attenuated compared with controls. Infection with Mycobacterium bovis bacille Calmette-Guérin resulted in approximately 10-fold-higher bacterial loads than in wild-type mice. Normal T and B cell responses were observed in macIL-10tg mice, suggesting that macrophage-specific overexpression of IL-10 predominantly acts in an autocrine/paracrine manner, resulting in chronically deactivated macrophages that manifest an impaired ability to control pathogens.
Collapse
MESH Headings
- Animals
- Antigens, CD/genetics
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/physiology
- Autocrine Communication/immunology
- Cell Count
- Cells, Cultured
- Colony Count, Microbial
- Epitopes, B-Lymphocyte/immunology
- Epitopes, T-Lymphocyte/immunology
- Female
- Gene Dosage
- Humans
- Infertility, Male/genetics
- Infertility, Male/mortality
- Injections, Intraperitoneal
- Interferon-gamma/antagonists & inhibitors
- Interferon-gamma/biosynthesis
- Interleukin-10/biosynthesis
- Interleukin-10/genetics
- Interleukin-12/biosynthesis
- Lipopolysaccharides/administration & dosage
- Lymphoid Tissue/cytology
- Macrophage Activation/genetics
- Macrophages/immunology
- Macrophages/metabolism
- Male
- Mice
- Mice, Transgenic
- Mycobacterium bovis/immunology
- Myeloid Cells/cytology
- Oligopeptides
- Peptides/genetics
- Promoter Regions, Genetic/immunology
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/genetics
- Signal Transduction/genetics
- Signal Transduction/immunology
- Tuberculosis/genetics
- Tuberculosis/immunology
- Tuberculosis/microbiology
- Tumor Necrosis Factor-alpha/antagonists & inhibitors
- Tumor Necrosis Factor-alpha/biosynthesis
Collapse
Affiliation(s)
- Roland Lang
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | | | | | | |
Collapse
|
41
|
Wellhausen SR, Peiper SC. CD33: biochemical and biological characterization and evaluation of clinical relevance. J BIOL REG HOMEOS AG 2002; 16:139-43. [PMID: 12144127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
MESH Headings
- Amino Acid Sequence
- Antigens, CD/analysis
- Antigens, CD/chemistry
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/analysis
- Antigens, Differentiation, Myelomonocytic/chemistry
- Antigens, Differentiation, Myelomonocytic/physiology
- Biochemistry/methods
- Biomarkers, Tumor/analysis
- Biomarkers, Tumor/metabolism
- Blood Cells/immunology
- Chemistry, Clinical/methods
- Humans
- Leukemia, Lymphoid/immunology
- Leukemia, Myeloid/drug therapy
- Leukemia, Myeloid/immunology
- Molecular Sequence Data
- Sequence Homology, Amino Acid
- Sialic Acid Binding Ig-like Lectin 3
- Stem Cells/immunology
Collapse
|
42
|
Abstract
Studies on monocyte adhesion are frequently limited by spontaneous changes of CD11b and CD62L during cell purification. Most isolation protocols for flow cytometric analysis that overcome this problem cannot be used when large numbers of living cells are needed for functional adhesion assays. This study investigated whether magnetic cell separation of monocytes with a paramagnetic bead against CD33 is a feasible method combining high yield with a low degree of spontaneous activation. As determined by flow cytometry, isolation of magnetically tagged monocytes at 4 degrees C did not alter the expression of CD11b and CD62L when compared to whole blood controls. Warming the cells slowly to room temperature immediately before starting the adhesion assay in a parallel plate flow chamber at 37 degrees C prevented further upregulation of adhesion molecules due to rewarming. When adhesion of magnetically tagged monocytes was compared with untouched monocytes that had been isolated via depletion of contaminating leukocytes, videomicroscopy showed that labelling CD33 neither affected rolling nor firm adhesion to human umbilical venous endothelial cells under flow. Finally, the subsequent upregulation of tissue factor expression on adherent monocytes indicates that magnetically separated monocytes responded properly to activating stimuli during cell adhesion. We conclude that magnetic cell separation via CD33 represents a feasible method for cell separation whenever large numbers of non-activated monocytes are needed for adhesion assays under flow.
Collapse
Affiliation(s)
- Boris Nohé
- Laboratory for Vascular Biology, Department of Anaesthesiology and Critical Care, University Hospital Tübingen, Germany.
| | | | | | | | | |
Collapse
|
43
|
Mahon NG, Madden BP, Caforio ALP, Elliott PM, Haven AJ, Keogh BE, Davies MJ, McKenna WJ. Immunohistologic evidence of myocardial disease in apparently healthy relatives of patients with dilated cardiomyopathy. J Am Coll Cardiol 2002; 39:455-62. [PMID: 11823084 DOI: 10.1016/s0735-1097(01)01762-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES This study investigated whether apparently healthy relatives of patients with idiopathic dilated cardiomyopathy (DCM) who have left ventricular enlargement (LVE) have biopsy evidence of underlying myocardial disease. BACKGROUND Left ventricular enlargement with normal systolic function is common among asymptomatic relatives of patients with DCM. Although there is circumstantial evidence to suggest that LVE may be a marker of early DCM, its pathophysiologic significance remains uncertain. METHODS Over six years, 767 asymptomatic relatives of 183 consecutive patients with DCM were evaluated: 37 (5%) had DCM and 104 (14%) had LVE (left ventricular end-diastolic dimension >112% predicted) with normal systolic function. Right ventricular biopsy was performed in 32 relatives with LVE, 14 patients with symptomatic DCM and 6 control subjects with normal ventricular function undergoing elective coronary artery bypass graft surgery. Histologic and immunohistochemical analyses, including quantitative double immunofluorescence, were performed for leukocyte markers (CD3 and CD68), intercellular adhesion molecule-1 (ICAM-1) and human leukocyte antigen class II antigens (DR and DQ). RESULTS Histologic findings consistent with DCM were present in 50% of the patients with DCM, 25% of the relatives with LVE and 0% of the control subjects. The median CD3 count was 2.4/mm(2) in patients with DCM, 4/mm(2) in relatives with LVE and 0 in control subjects (p = 0.04). Using a threshold of >7 cells/mm(2), 21% of patients with DCM and 25% of relatives with LVE were CD3-positive (p = 0.01). Quantitative analysis demonstrated DR expression on 55.8+/-22.8%, 63.5+/-18.8% and 30.9+/-15.7% of the endothelial surface in patients with DCM, relatives and control subjects, respectively (p = 0.003). Corresponding values for ICAM expression were 35.6+/-15.1%, 36.7+/-14.5% and 17.3+/-7.9% (p = 0.013). When combining inflammatory and histologic changes, 28 (86%) of LVE, 14 (100%) of DCM and no control biopsies were abnormal (p < 0.001). CONCLUSIONS Most asymptomatic relatives of patients with DCM with LVE have histopathologic and immunopathologic findings similar to those of patients with established disease. Clinical identification and follow-up of such individuals are warranted to prevent presentation with advanced DCM and to enable assessment of interventions aimed at attenuating disease progression.
Collapse
MESH Headings
- Adult
- Age Factors
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/physiology
- Biopsy
- CD3 Complex/physiology
- Cardiomyopathies/diagnosis
- Cardiomyopathies/metabolism
- Cardiomyopathies/pathology
- Cardiomyopathy, Dilated/diagnosis
- Cardiomyopathy, Dilated/metabolism
- Cardiomyopathy, Dilated/pathology
- Endothelium, Vascular/metabolism
- Female
- Fibrosis
- Follow-Up Studies
- HLA-DQ Antigens/physiology
- HLA-DR Antigens/physiology
- Humans
- Hypertrophy, Left Ventricular/etiology
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Immunohistochemistry
- Inflammation/etiology
- Inflammation/metabolism
- Intercellular Adhesion Molecule-1/physiology
- Interpersonal Relations
- London/epidemiology
- Male
- Middle Aged
- Reference Values
Collapse
Affiliation(s)
- Niall G Mahon
- Department of Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom.
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Holmes RK, Harutyunyan K, Shah M, Joenje H, Youssoufian H. Correction of cross-linker sensitivity of Fanconi anemia group F cells by CD33-mediated protein transfer. Blood 2001; 98:3817-22. [PMID: 11739191 DOI: 10.1182/blood.v98.13.3817] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Studies have previously described the feasibility of receptor-mediated protein transfer in a cell culture model of Fanconi anemia (FA) group C. This study explores the versatility of this approach by using an antibody single-chain fusion protein to correct the phenotypic defect in FA group F cells. A 68.5-kd chimeric protein (His-M195FANCF) was expressed, consisting of a His tag, a single-chain antibody to the myeloid antigen CD33, and the FANCF protein, as well as a 43-kd His-FANCF fusion protein lacking the antibody motif, in Escherichia coli. The nickel-agarose-purified His-M195FANCF protein bound specifically to the surface of HeLa cells transfected with CD33 and internalized through vesicular structures. The fusion protein, but not CD33, sorted to the nucleus, consistent with the known nuclear localization of FANCF. No similar binding or internalization was observed with His-FANCF. Pretreatment of the transfected cells with chloroquine abolished nuclear accumulation, but there was little change with brefeldin A, indicating a minimal if any role for the Golgi apparatus in mediating transport from endosomes to the cytosol and the nucleus. The intracellular half-life of His-M195FANCF was approximately 160 minutes. Treatment of CD33-transfected FA group F lymphoblastoid cells with 0.1 mg/mL His-M195FANCF conferred resistance to mitomycin C. No similar protection was noted in CD33(-) parental cells or CD33(+) FA cells belonging to groups A and C. These results demonstrate that antibody-directed, receptor-mediated protein transfer is a versatile method for the delivery of biologically active proteins into hematopoietic cells.
Collapse
Affiliation(s)
- R K Holmes
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | | | | | | | | |
Collapse
|
45
|
Zocchi MR, Pellegatta F, Pierri I, Gobbi M, Poggi A. Leukocyte-associated Ig-like receptor-1 prevents granulocyte-monocyte colony stimulating factor-dependent proliferation and Akt1/PKB alpha activation in primary acute myeloid leukemia cells. Eur J Immunol 2001; 31:3667-75. [PMID: 11745387 DOI: 10.1002/1521-4141(200112)31:12<3667::aid-immu3667>3.0.co;2-g] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [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: 11/07/2022]
Abstract
The leukocyte-associated Ig-like receptor-1 (LAIR-1), a surface leukocyte receptor containing two immune receptor tyrosine-based inhibitory motif (ITIM) is expressed on acute myeloid leukemia (AML) blasts isolated from peripheral blood or bone marrow of 17 patients (2 M0, 3 M1, 5 M2, 2 M4 and 5 M5 according to French, American and British classification). Further, we provide evidence thatLAIR-1 engagement inhibits granulocyte-monocyte colony-stimulating factor (GM-CSF)-induced proliferation of AML blasts. Indeed, leukemia cells stimulated with GM-CSF were blocked in the G0/G1 phase of the cell cycle and underwent apoptosis within 4 days after the engagement of LAIR-1. Remarkably, LAIR-1 was functional also in AML blasts which do not express CD33, mainly M4 and M5. Importantly, the LAIR-1 ligation led to a strong inhibition of both GM-CSF receptor-mediated intracellular calcium increases, phosphorylation and activation of Akt1/protein kinase B alpha, a substrate of the phosphatidylinositol-3 kinase. This last inhibitory effect was prevented by a synthetic peptide spanning the ITIM portion of LAIR-1, suggesting the involvement of SHP-1 phosphatase in LAIR-1-mediated inhibitory signal. Altogether, these findings indicate that the engagement of LAIR-1 can down-regulate GM-CSF-mediated survival and proliferation of AML blasts, suggesting an additional therapeutic approach to the treatment of AML patients.
Collapse
MESH Headings
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/physiology
- Cell Division/drug effects
- Enzyme Activation
- Granulocyte-Macrophage Colony-Stimulating Factor/pharmacology
- Humans
- Leukemia, Myeloid, Acute/enzymology
- Leukemia, Myeloid, Acute/pathology
- Protein Serine-Threonine Kinases/metabolism
- Proto-Oncogene Proteins
- Proto-Oncogene Proteins c-akt
- Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/physiology
- Receptors, Immunologic/analysis
- Receptors, Immunologic/physiology
- Sialic Acid Binding Ig-like Lectin 3
Collapse
Affiliation(s)
- M R Zocchi
- Laboratory of Tumor Immunology, Department of Internal Medicine, Scientific Institute San Raffaele, Milan, Italy
| | | | | | | | | |
Collapse
|
46
|
Abstract
Bispecific anti-CD33 x anti-CD64 antibody (BsAb) directly inhibited proliferation and colony formation of human acute myeloid leukemia cell lines, without affecting the function of normal monocytes. Addition of BsAb to normal monocytes induced tyrosine phosphorylation of Cbl and Vav, association of these molecules with CD33, and downstream signaling. In leukemia cells that were insensitive to BsAb treatment, Vav and Cbl were constitutively phosphorylated and, therefore, constitutively associated with CD33. Direct growth inhibition is an additional mechanism by which BsAb may be useful in the therapy of AML.
Collapse
MESH Headings
- Antibodies, Bispecific/pharmacology
- Antigens, CD/immunology
- Antigens, CD/physiology
- Antigens, Differentiation, Myelomonocytic/immunology
- Antigens, Differentiation, Myelomonocytic/physiology
- Cell Division
- Humans
- Interferon-gamma/pharmacology
- Leukemia, Myeloid, Acute/pathology
- Monocytes/immunology
- Phagocytosis
- Phosphorylation
- Receptors, IgG/immunology
- Receptors, IgG/physiology
- Sialic Acid Binding Ig-like Lectin 3
- Tumor Cells, Cultured
- Tyrosine/metabolism
- Vanadates/pharmacology
Collapse
Affiliation(s)
- L Balaian
- Department of Medicine and Cancer Center, University of California, San Diego School of Medicine, La Jolla, CA 92093-0960, USA
| | | |
Collapse
|
47
|
Abstract
Siglecs are members of the Ig superfamily that bind to sialic acid (Sia) and are mainly expressed by cells of the hematopoietic system. Until three years ago, only four Siglecs were known, namely sialoadhesin, CD22, myelin-associated glycoprotein and CD33. Since then, a further six human CD33-related Siglecs with features of inhibitory receptors have been identified and shown to be expressed by discrete subsets of leukocytes. Recognition of Sia by these Siglecs could play a role in the regulation of the innate immune system.
Collapse
Affiliation(s)
- P R Crocker
- The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, DD1 5EH, Dundee, UK.
| | | |
Collapse
|
48
|
Mingari MC, Vitale C, Romagnani C, Falco M, Moretta L. p75/AIRM1 and CD33, two sialoadhesin receptors that regulate the proliferation or the survival of normal and leukemic myeloid cells. Immunol Rev 2001; 181:260-8. [PMID: 11513147 DOI: 10.1034/j.1600-065x.2001.1810122.x] [Citation(s) in RCA: 42] [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: 11/23/2022]
Abstract
Inhibitory receptors originally identified in natural killer (NK) cells have also been detected in other leukocyte types, thus suggesting that they may play a more general role in the control of leukocyte function. Here we report data on p75/adhesion receptor molecule 1 (AIRM1), a surface inhibitory receptor of the sialoadhesin family originally identified in NK cells that is also expressed by normal and leukemic myeloid cells. Given the homology between p75/AIRM1 and CD33, we also reanalyzed CD33, a major myeloid marker of still unknown function. We discuss recent data indicating that engagement of p75/AIRM1 or CD33 sharply inhibits the in vitro proliferation/differentiation of CD34+ myeloid precursors induced by stem cell factor and granulocyte-macrophage colony-stimulating factor. Importantly, a similar in vitro inhibitory effect occurs in monocyte/macrophages as well as in chronic or acute myeloid leukemias. While CD33 appears to act via the induction of apoptosis, p75/AIRM1 blocks cell proliferation but does not appear to induce apoptosis. A synergistic effect in the induction of apoptosis has also been documented between antibodies specific for CD33 and the chemotherapic agent etoposide. Taken together, the use of appropriate ligands against CD33 or p75/AIRM1 may represent a new therapeutic tool for treatment of myeloid leukemias or diseases characterized by overwhelming macrophage activation.
Collapse
Affiliation(s)
- M C Mingari
- Istituto Nazionale per la Ricerca sul Cancro, Centro Biotecnologie Avanzate, Genova, Italy
| | | | | | | | | |
Collapse
|
49
|
Minami M, Kume N. [Role of CD68 and macrosialin in atherosclerosis]. Nihon Rinsho 2001; 59 Suppl 2:355-9. [PMID: 11351605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Affiliation(s)
- M Minami
- Department of Geriatric Medicine, Graduate School of Medicine, Kyoto University
| | | |
Collapse
|
50
|
Hiki N, Mimura Y, Ogawa T, Kojima J, Hatao F, Kaminishi M. Pathophysiological relevance of the CD14 receptor in surgical patients: biological activity of endotoxin is regulated by the CD14 receptor. J Endotoxin Res 2001; 7:461-6. [PMID: 11753218] [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] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
Endotoxins (lipopolysaccharides, LPSs) are potent bacterial poisons, and they are always present in the intestine in considerable numbers. Stress, such that as a resulting from multiple injuries, burns, hypovolemia, hypoxia, intestinal ischemia, and surgery can lead to a breakdown of the gut barrier, allowing endotoxins to enter the systemic circulation via translocation. However, estimating the biological activity of translocated circulating endotoxins and identification of the mechanisms regulating their biological activities remain complex problems. CD14 has been found to exist as a soluble protein in the serum and as a glycosylphosphatidylinositol (GPI)-anchored protein of myeloid lineage cells. It plays key roles in both LPS-induced activation and in LPS internalization by cells. In this article, we outline: (i) the biological activity of circulating endotoxin; and (ii) the role of membrane and/or soluble CD14 regulating the bioactivity of circulating endotoxin in a human model of postoperative endotoxemia.
Collapse
Affiliation(s)
- N Hiki
- Department of Surgery, University of Tokyo, Tokyo, Japan.
| | | | | | | | | | | |
Collapse
|