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Zhong T, Zhang W, Guo H, Pan X, Chen X, He Q, Yang B, Ding L. The regulatory and modulatory roles of TRP family channels in malignant tumors and relevant therapeutic strategies. Acta Pharm Sin B 2022; 12:1761-1780. [PMID: 35847486 PMCID: PMC9279634 DOI: 10.1016/j.apsb.2021.11.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 09/11/2021] [Accepted: 10/19/2021] [Indexed: 02/08/2023] Open
Abstract
Transient receptor potential (TRP) channels are one primary type of calcium (Ca2+) permeable channels, and those relevant transmembrane and intracellular TRP channels were previously thought to be mainly associated with the regulation of cardiovascular and neuronal systems. Nowadays, however, accumulating evidence shows that those TRP channels are also responsible for tumorigenesis and progression, inducing tumor invasion and metastasis. However, the overall underlying mechanisms and possible signaling transduction pathways that TRP channels in malignant tumors might still remain elusive. Therefore, in this review, we focus on the linkage between TRP channels and the significant characteristics of tumors such as multi-drug resistance (MDR), metastasis, apoptosis, proliferation, immune surveillance evasion, and the alterations of relevant tumor micro-environment. Moreover, we also have discussed the expression of relevant TRP channels in various forms of cancer and the relevant inhibitors' efficacy. The chemo-sensitivity of the anti-cancer drugs of various acting mechanisms and the potential clinical applications are also presented. Furthermore, it would be enlightening to provide possible novel therapeutic approaches to counteract malignant tumors regarding the intervention of calcium channels of this type.
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Key Words
- 4α-PDD, 4α-phorbol-12,13-didecanoate
- ABCB, ATP-binding cassette B1
- AKT, protein kinase B
- ALA, alpha lipoic acid
- AMPK, AMP-activated protein kinase
- APB, aminoethoxydiphenyl borate
- ATP, adenosine triphosphate
- CBD, cannabidiol
- CRAC, Ca2+ release-activated Ca2+ channel
- CaR, calcium-sensing receptor
- CaSR, calcium sensing receptor
- Cancer progression
- DAG, diacylglycerol
- DBTRG, Denver Brain Tumor Research Group
- ECFC, endothelial colony-forming cells
- ECM, enhanced extracellular matrix
- EGF, epidermal growth factor
- EMT, epithelial–mesenchymal transition
- ER, endoplasmic reticulum
- ERK, extracellular signal-regulated kinase
- ETS, erythroblastosis virus E26 oncogene homolog
- FAK, focal adhesion kinase
- GADD, growth arrest and DNA damage-inducible gene
- GC, gastric cancer
- GPCR, G-protein coupled receptor
- GSC, glioma stem-like cells
- GSK, glycogen synthase kinase
- HCC, hepatocellular carcinoma
- HIF, hypoxia-induced factor
- HSC, hematopoietic stem cells
- IP3R, inositol triphosphate receptor
- Intracellular mechanism
- KO, knockout
- LOX, lipoxygenase
- LPS, lipopolysaccharide
- LRP, lipoprotein receptor-related protein
- MAPK, mitogen-activated protein kinase
- MLKL, mixed lineage kinase domain-like protein
- MMP, matrix metalloproteinases
- NEDD4, neural precursor cell expressed, developmentally down-regulated 4
- NFAT, nuclear factor of activated T-cells
- NLRP3, NLR family pyrin domain containing 3
- NO, nitro oxide
- NSCLC, non-small cell lung cancer
- Nrf2, nuclear factor erythroid 2-related factor 2
- P-gp, P-glycoprotein
- PCa, prostate cancer
- PDAC, pancreatic ductal adenocarcinoma
- PHD, prolyl hydroxylases
- PI3K, phosphoinositide 3-kinase
- PKC, protein kinase C
- PKD, polycystic kidney disease
- PLC, phospholipase C
- Programmed cancer cell death
- RNS/ROS, reactive nitrogen species/reactive oxygen species
- RTX, resiniferatoxin
- SMAD, Caenorhabditis elegans protein (Sma) and mothers against decapentaplegic (Mad)
- SOCE, store operated calcium entry
- SOR, soricimed
- STIM1, stromal interaction molecules 1
- TEC, tumor endothelial cells
- TGF, transforming growth factor-β
- TNF-α, tumor necrosis factor-α
- TRP channels
- TRPA/C/M/ML/N/P/V, transient receptor potential ankyrin/canonical/melastatin/mucolipon/NOMPC/polycystin/vanilloid
- Targeted tumor therapy
- Tumor microenvironment
- Tumor-associated immunocytes
- UPR, unfolded protein response
- VEGF, vascular endothelial growth factor
- VIP, vasoactive intestinal peptide
- VPAC, vasoactive intestinal peptide receptor subtype
- mTOR, mammalian target of rapamycin
- pFRG/RTN, parafacial respiratory group/retrotrapezoid nucleus
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Spartalis M, Spartalis E, Athanasiou A, Paschou SA, Kontogiannis C, Georgiopoulos G, Iliopoulos DC, Voudris V. The Role of the Endothelium in Premature Atherosclerosis: Molecular Mechanisms. Curr Med Chem 2020; 27:1041-1051. [PMID: 31544711 DOI: 10.2174/0929867326666190911141951] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 03/29/2019] [Accepted: 04/28/2019] [Indexed: 12/22/2022]
Abstract
Atherosclerotic disease is still one of the leading causes of mortality. Atherosclerosis is a complex progressive and systematic artery disease that involves the intima of the large and middle artery vessels. The inflammation has a key role in the pathophysiological process of the disease and the infiltration of the intima from monocytes, macrophages and T-lymphocytes combined with endothelial dysfunction and accumulated oxidized low-density lipoprotein (LDL) are the main findings of atherogenesis. The development of atherosclerosis involves multiple genetic and environmental factors. Although a large number of genes, genetic polymorphisms, and susceptible loci have been identified in chromosomal regions associated with atherosclerosis, it is the epigenetic process that regulates the chromosomal organization and genetic expression that plays a critical role in the pathogenesis of atherosclerosis. Despite the positive progress made in understanding the pathogenesis of atherosclerosis, the knowledge about the disease remains scarce.
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Affiliation(s)
- Michael Spartalis
- Division of Cardiology, Onassis Cardiac Surgery Center, 17674 Athens, Greece
| | - Eleftherios Spartalis
- Laboratory of Experimental Surgery and Surgical Research, University of Athens, Medical School, Athens, Greece
| | - Antonios Athanasiou
- Laboratory of Experimental Surgery and Surgical Research, University of Athens, Medical School, Athens, Greece
| | - Stavroula A Paschou
- Division of Endocrinology and Diabetes, "Aghia Sophia" Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Christos Kontogiannis
- Department of Clinical Therapeutics, "Alexandra" Hospital, University of Athens, 11528 Athens, Greece
| | - Georgios Georgiopoulos
- Department of Clinical Therapeutics, "Alexandra" Hospital, University of Athens, 11528 Athens, Greece
| | - Dimitrios C Iliopoulos
- Laboratory of Experimental Surgery and Surgical Research, University of Athens, Medical School, Athens, Greece
| | - Vassilis Voudris
- Division of Cardiology, Onassis Cardiac Surgery Center, 17674 Athens, Greece
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Tang Y, Li H, Li J, Liu Y, Li Y, Zhou J, Zhou J, Lu X, Zhao W, Hou J, Wang XY, Chen Z, Zuo D. Macrophage scavenger receptor 1 contributes to pathogenesis of fulminant hepatitis via neutrophil-mediated complement activation. J Hepatol 2018; 68:733-743. [PMID: 29154963 PMCID: PMC5951742 DOI: 10.1016/j.jhep.2017.11.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 10/30/2017] [Accepted: 11/05/2017] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS The macrophage scavenger receptor 1 (Msr1, also called SRA) is a pattern recognition receptor primarily expressed on myeloid cells, which plays an important role in the maintenance of immune homeostasis. Since MSR1 expression was upregulated in the livers of patients with fulminant hepatitis (FH), we investigated the functional mechanism of Msr1 in FH pathogenesis. METHODS Msr1-deficient (Msr1-/-) mice and their wild-type (WT) littermates were infected with mouse hepatitis virus strain-A59 (MHV-A59) to induce FH, and the levels of tissue damage, serum alanine aminotransferase, inflammatory cytokines and complement component 5a (C5a) were measured and compared. Liver injury was studied after MHV infection with or without neutrophil depletion. RESULTS Our results showed that Msr1-/- mice were resistant to MHV-induced hepatitis. Treatment with the C5a receptor antagonist (C5aRa) diminished the differences in inflammatory responses and liver injury between MHV-infected wild-type and Msr1-/- mice, suggesting that C5a-induced pro-inflammatory response plays a critical role in the Msr1-mediated regulation of FH pathogenesis. We demonstrated that Msr1 efficiently enhanced transforming growth factor-activated kinase-1 phosphorylation in neutrophils upon MHV-A59 stimulation, thereby promoting the activation of the extracellular signal-regulated kinase pathway and subsequent NETosis formation. Moreover, we provided evidence that blockage of Msr1 attenuated the liver damage caused by MHV-A59 infection. CONCLUSIONS Msr1 promotes the pathogenesis of virus-induced FH by enhancing induction of neutrophil NETosis and subsequent complement activation. Targeting Msr1 may be employed as a new immunotherapeutic strategy for FH. LAY SUMMARY Virus-induced fulminant hepatitis (FH) is a disease with a high mortality worldwide. Enhanced levels of macrophage scavenger receptor 1 (Msr1) in the liver of patients with FH and of murine experimental FH indicated Msr1 plays a role in the pathogenesis of FH. Herein, we demonstrate that mice deficient in Msr1 are resistant to FH induced by MHV-A59, and the Msr1 inhibitor fucoidan suppresses the progression of FH in mice. Our study suggests that use of drugs inhibiting MSR1 function could be beneficial to patients with FH.
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Affiliation(s)
- Yuan Tang
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Huifang Li
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Junru Li
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Yunzhi Liu
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Yanli Li
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Jing Zhou
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Jia Zhou
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Xiao Lu
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Wei Zhao
- Biosafety Level-3 Laboratory, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Jinlin Hou
- State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Xiang-Yang Wang
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Zhengliang Chen
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, Guangdong 510515, China.
| | - Daming Zuo
- Department of Immunology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong 510515, China; Guangdong Provincial Key Laboratory of Proteomics, Southern Medical University, Guangzhou, Guangdong 510515, China.
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Harvey BP, Raycroft MT, Quan TE, Rudenga BJ, Roman RM, Craft J, Mamula MJ. Transfer of antigen from human B cells to dendritic cells. Mol Immunol 2014; 58:56-65. [PMID: 24309484 PMCID: PMC4234097 DOI: 10.1016/j.molimm.2013.10.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 10/03/2013] [Accepted: 10/15/2013] [Indexed: 12/13/2022]
Abstract
The cooperation of B lymphocytes with other antigen presenting cells (APCs) is often necessary in the efficient processing and presentation of antigen. Herein, we describe a mechanism by which B cells physically interact with dendritic cells (DCs) resulting in the transfer of B cell receptor (BCR)-enriched antigen to these APCs. Antigen transfer involves direct contact between the two cells followed by the capture of B cell derived membrane and intracellular components. Strikingly, DCs acquire greater amounts of antigen by transfer from B cells than by endocytosis of free antigen. Blocking scavenger receptor A, a DC surface receptor involved in membrane acquisition, abrogates these events. We propose that antigen transfer from B cells to DCs results in a more focused immunologic response due to the selective editing of Ag by the BCR.
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Affiliation(s)
- Bohdan P Harvey
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Maurice T Raycroft
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Timothy E Quan
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Benjamin J Rudenga
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Robert M Roman
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Joe Craft
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Mark J Mamula
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA.
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Sang A, Zheng YY, Morel L. Contributions of B cells to lupus pathogenesis. Mol Immunol 2013; 62:329-38. [PMID: 24332482 DOI: 10.1016/j.molimm.2013.11.013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 10/14/2013] [Accepted: 11/14/2013] [Indexed: 01/09/2023]
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies. This review summarizes first the results obtained in the mouse that have revealed how B cell tolerance is breached in SLE. We then review the B cell subsets, in addition to the autoAb producing cells, which contribute to SLE pathogenesis, focusing on marginal zone B cells, B-1 cells and regulatory B cells. Finally, we review the interactions between B cells and other immune cells that have been implicated in SLE, such as dendritic cells, macrophages, neutrophils and T cells.
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Affiliation(s)
- Allison Sang
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Ying-Yi Zheng
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Laurence Morel
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, FL 32610, USA.
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6
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Garraud O, Borhis G, Badr G, Degrelle S, Pozzetto B, Cognasse F, Richard Y. Revisiting the B-cell compartment in mouse and humans: more than one B-cell subset exists in the marginal zone and beyond. BMC Immunol 2012. [PMID: 23194300 PMCID: PMC3526508 DOI: 10.1186/1471-2172-13-63] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The immunological roles of B-cells are being revealed as increasingly complex by functions that are largely beyond their commitment to differentiate into plasma cells and produce antibodies, the key molecular protagonists of innate immunity, and also by their compartmentalisation, a more recently acknowledged property of this immune cell category. For decades, B-cells have been recognised by their expression of an immunoglobulin that serves the function of an antigen receptor, which mediates intracellular signalling assisted by companion molecules. As such, B-cells were considered simple in their functioning compared to the other major type of immune cell, the T-lymphocytes, which comprise conventional T-lymphocyte subsets with seminal roles in homeostasis and pathology, and non-conventional T-lymphocyte subsets for which increasing knowledge is accumulating. Since the discovery that the B-cell family included two distinct categories — the non-conventional, or extrafollicular, B1 cells, that have mainly been characterised in the mouse; and the conventional, or lymph node type, B2 cells — plus the detailed description of the main B-cell regulator, FcγRIIb, and the function of CD40+ antigen presenting cells as committed/memory B-cells, progress in B-cell physiology has been slower than in other areas of immunology. Cellular and molecular tools have enabled the revival of innate immunity by allowing almost all aspects of cellular immunology to be re-visited. As such, B-cells were found to express “Pathogen Recognition Receptors” such as TLRs, and use them in concert with B-cell signalling during innate and adaptive immunity. An era of B-cell phenotypic and functional analysis thus began that encompassed the study of B-cell microanatomy principally in the lymph nodes, spleen and mucosae. The novel discovery of the differential localisation of B-cells with distinct phenotypes and functions revealed the compartmentalisation of B-cells. This review thus aims to describe novel findings regarding the B-cell compartments found in the mouse as a model organism, and in human physiology and pathology. It must be emphasised that some differences are noticeable between the mouse and human systems, thus increasing the complexity of B-cell compartmentalisation. Special attention will be given to the (lymph node and spleen) marginal zones, which represent major crossroads for B-cell types and functions and a challenge for understanding better the role of B-cell specificities in innate and adaptive immunology.
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7
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Raycroft MT, Harvey BP, Bruck MJ, Mamula MJ. Inhibition of antigen trafficking through scavenger receptor A. J Biol Chem 2012; 287:5310-6. [PMID: 22215667 DOI: 10.1074/jbc.m111.316356] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
B cell acquisition and presentation of specific autoantigens (auto-Ags) are thought to play an important and complex role in autoimmunity development. We previously identified scavenger receptor A (SR-A) as an early target in altering B cell-mediated autoimmunity. SR-A is highly expressed on professional antigen-presenting cells such as macrophages (MΦs) and dendritic cells (DCs). In this study, we demonstrate that SR-A is responsible for controlling B cell interactions with DCs/MΦs to promote Ag transfer from B cells to DCs/MΦs. We established a high-throughput ELISA-based screen to identify novel SR-A inhibitors, the specificity of which was determined by dose dependence and Biacore surface plasmon resonance testing. We identified small molecule inhibitors (SMIs) able to reduce SR-A-mediated Ag transfer in human cells. In particular, the SMIs prevented SR-A-positive cells from accumulating/loading Ag over time. Furthermore, we determined that one SMI, sennoside B, can reduce SR-A-mediated capture of B cells. Finally, SMI-mediated decreases in Ag transfer or accumulation reduced T cell proliferation in vitro and in vivo. These observations demonstrate that B cell-DC/MΦ interactions are conducive to promoting Ag trafficking between these cell types via SR-A. Inhibitors of SR-A may provide a novel therapeutic strategy in ameliorating autoimmune disease development.
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Affiliation(s)
- Maurice T Raycroft
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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8
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Scavenger receptors as regulators of natural antibody responses and B cell activation in autoimmunity. Mol Immunol 2011; 48:1307-18. [DOI: 10.1016/j.molimm.2011.01.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2010] [Revised: 01/05/2011] [Accepted: 01/17/2011] [Indexed: 12/12/2022]
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9
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Birjandi SZ, Ippolito JA, Ramadorai AK, Witte PL. Alterations in marginal zone macrophages and marginal zone B cells in old mice. THE JOURNAL OF IMMUNOLOGY 2011; 186:3441-51. [PMID: 21307289 DOI: 10.4049/jimmunol.1001271] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Marginal zones (MZs) are architecturally organized for clearance of and rapid response against blood-borne Ags entering the spleen. MZ macrophages (MZMs) and MZ B cells are particularly important in host defense against T-independent pathogens and may be crucial for the prevention of diseases, such as streptococcal pneumonia, that are devastating in older patients. Our objective was to determine whether there are changes in the cellular components of the MZ between old and young mice. Using immunocytochemistry and a blinded scoring system, we observed gross architectural changes in the MZs of old mice, including reduction in the abundance of MZMs surrounding the MZ sinus as well as disruptions in positioning of mucosal addressin cell adhesion molecule 1 (MAdCAM-1)(+) sinus lining cells and metallophilic macrophages. Loss of frequency of MZMs was corroborated by flow cytometry. A majority of old mice also showed reduced frequency of MZ B cells, which correlated with decreased abundance of MZM in individual old mice. The spleens of old mice showed less deposition of intravenously injected dextran particles within the MZ, likely because of the decreased frequency in MZMs, because SIGN-R1 expression was not reduced on MZM from old mice. The phagocytic ability of individual MZMs was examined using Staphylococcus aureus bioparticles, and no differences in phagocytosis were found between macrophages from young or old spleens. In summary, an anatomical breakdown of the MZ occurs in advanced age, and a reduction in frequency of MZM may affect the ability of the MZM compartment to clear blood-borne Ags and mount proper T-independent immune responses.
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Affiliation(s)
- Shirin Z Birjandi
- Program for Immunology and Aging, Graduate Program in Cell Biology, Neurobiology and Anatomy, Loyola University Chicago Medical Center, Maywood, IL 60153, USA
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Kishore U, Plüddemann A, Gordon S. Macrophage pattern recognition receptors in immunity, homeostasis and self tolerance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 653:1-14. [PMID: 19799108 PMCID: PMC7123833 DOI: 10.1007/978-1-4419-0901-5_1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Macrophages, a major component of innate immune defence, express a large repertoire of different classes of pattern recognition receptors and other surface antigens which determine the immunologic and homeostatic potential of these versatile cells. In the light of present knowledge ofmacrophage surface antigens, we discuss self versus nonself recognition, microbicidal effector functions and self tolerance in the innate immune system.
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Affiliation(s)
- Uday Kishore
- Laboratory of Human Immunology and Infection Biology, Biosciences Division, School of Health Sciences and Social Care, Brunei University, Uxbridge, London, UK
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11
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van Lent PLEM, Hofkens W, Blom AB, Grevers L, Sloetjes A, Takahashi N, van Tits LJ, Vogl T, Roth J, de Winther MP, van den Berg WB. Scavenger receptor class A type I/II determines matrix metalloproteinase-mediated cartilage destruction and chondrocyte death in antigen-induced arthritis. ACTA ACUST UNITED AC 2009; 60:2954-65. [DOI: 10.1002/art.24908] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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12
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Harvey BP, Quan TE, Rudenga BJ, Roman RM, Craft J, Mamula MJ. Editing antigen presentation: antigen transfer between human B lymphocytes and macrophages mediated by class A scavenger receptors. THE JOURNAL OF IMMUNOLOGY 2008; 181:4043-51. [PMID: 18768860 DOI: 10.4049/jimmunol.181.6.4043] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
B lymphocytes can function independently as efficient APCs. However, our previous studies demonstrate that both dendritic cells and macrophages are necessary to propagate immune responses initiated by B cell APCs. This finding led us to identify a process in mice whereby Ag-specific B cells transfer Ag to other APCs. In this study, we report the ability and mechanism by which human B lymphocytes can transfer BCR-captured Ag to macrophages. The transfer of Ag involves direct contact between the two cells followed by the capture of B cell-derived membrane and/or intracellular components by the macrophage. These events are abrogated by blocking scavenger receptor A, a receptor involved in the exchange of membrane between APCs. Macrophages acquire greater amounts of Ag in the presence of specific B cells than in their absence. This mechanism allows B cells to amplify or edit the immune response to specific Ag by transferring BCR-captured Ag to other professional APCs, thereby increasing the frequency of its presentation. Ag transfer may perpetuate chronic autoimmune responses to specific self-proteins and help explain the efficacy of B cell-directed therapies in human disease.
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Affiliation(s)
- Bohdan P Harvey
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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13
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Macrophage scavenger receptors and host-derived ligands. Methods 2008; 43:207-17. [PMID: 17920517 DOI: 10.1016/j.ymeth.2007.06.004] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Accepted: 06/25/2007] [Indexed: 02/07/2023] Open
Abstract
The scavenger receptors are a large family of molecules that are structurally diverse and have been implicated in a range of functions. They are expressed by myeloid cells, selected endothelial cells and some epithelial cells and recognise many different ligands, including microbial pathogens as well as endogenous and modified host-derived molecules. This review will focus on the eight classes of scavenger receptors (class A-H) in terms of their structure, expression and recognition of host-derived ligands. Scavenger receptors have been implicated in a range of physiological and pathological processes, such as atherosclerosis and Alzheimer's disease, and function in adhesion and tissue maintenance. More recently, some of the scavenger receptors have been shown to mediate binding and endocytosis of chaperone proteins, such as the heat shock proteins, thereby playing an important role in antigen cross-presentation.
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14
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Getchell ML, Li H, Vaishnav RA, Borders AS, Witta J, Subhedar N, de Villiers W, Stromberg AJ, Getchell TV. Temporal gene expression profiles of target-ablated olfactory epithelium in mice with disrupted expression of scavenger receptor A: impact on macrophages. Physiol Genomics 2006; 27:245-63. [PMID: 16882882 DOI: 10.1152/physiolgenomics.00261.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Target ablation [removal of the olfactory bulb (OBX)] induces apoptotic death of olfactory sensory neurons (OSNs) and an immune response in which activation and recruitment of macrophages (ms) into the olfactory epithelium (OE) occupy a central role. Ms phagocytose apoptotic neurons and secrete cytokines/growth factors that regulate subsequent progenitor cell proliferation and neurogenesis. Scavenger receptor A (SR-A) is a pattern recognition receptor that mediates binding of ms to apoptotic cells and other relevant immune response functions. The aim of this study was to determine the impact of the absence of SR-A on the immune response to OBX. The immune response to OBX was evaluated in mice in which functional expression of the m scavenger receptor (MSR) was eliminated by gene disruption (MSR-/-) and wild-type (wt) mice of the same genetic background. OBX induced significant apoptotic death of mature OSNs in the two strains. However, subsequent m infiltration and activation and progenitor cell proliferation were significantly reduced in MSR-/- vs. wt mice. Gene expression profiling at short intervals after OBX demonstrated significant differences in temporal patterns of expression of several gene categories, including immune response genes. Many immune response genes that showed different temporal patterns of expression are related to m function, including cytokine and chemokine secretion, phagocytosis, and m maturation and activation. These studies suggest that impairment of the immune response to OBX in the OE of MSR-/- mice most likely resulted from decreased m adhesion and subsequent reduced infiltration and activation, with a resultant decrease in neurogenesis.
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Affiliation(s)
- M L Getchell
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, Kentucky, USA.
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15
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Kvell K, Czömpöly T, Pikkarainen T, Balogh P. Species-specific restriction of cell surface expression of mouse MARCO glycoprotein in murine cell lines. Biochem Biophys Res Commun 2006; 341:1193-202. [PMID: 16460688 DOI: 10.1016/j.bbrc.2006.01.083] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Accepted: 01/17/2006] [Indexed: 12/19/2022]
Abstract
The MARCO (macrophage receptor with collagenous structure) glycoprotein belongs to the scavenger receptor type family of pattern-recognition molecules produced by a subset of marginal zone macrophages in the spleen. Stimulation with LPS leads to its appearance on macrophages located at other tissue compartments. In the present work, we report its in vitro expression by various cell lines using transient and stable (lentiviral) gene delivery aimed at investigating the signaling properties of this receptor and its analysis using a novel rat monoclonal antibody against the SRCR-domain of mouse MARCO. When trying to establish stable mouse MARCO-transfectants using lentiviral transduction and other methods, we consistently found that MARCO accumulated intracellularly in various murine host cells. In contrast, such a phenomenon was not observed in non-murine cell lines. Our observations indicate the presence of an unexpected limitation of the in vitro expression of mouse MARCO glycoprotein in murine cell lines. We believe that the failure to express MARCO on the cell surface of the many murine cell lines is likely due to the absence of endoplasmic reticulum molecular chaperones needed for the correct folding and assembly of the trimeric MARCO molecule.
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Affiliation(s)
- Krisztián Kvell
- Department of Immunology and Biotechnology, Faculty of Medicine, University of Pécs, Szigeti út 12, H-7634 Pécs, Hungary
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16
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Beamer CA, Holian A. Scavenger receptor class A type I/II (CD204) null mice fail to develop fibrosis following silica exposure. Am J Physiol Lung Cell Mol Physiol 2005; 289:L186-95. [PMID: 15849212 DOI: 10.1152/ajplung.00474.2004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Alveolar macrophages express the class A scavenger receptor (CD204) (Babaev VR, Gleaves LA, Carter KJ, Suzuki H, Kodama T, Fazio S, and Linton MF. Arterioscler Thromb Vasc Biol 20: 2593-2599, 2000); yet its role in vivo in lung defense against environmental particles has not been clearly defined. In the current study, CD204 null mice (129Sv background) were used to investigate the link between CD204 and downstream events of inflammation and fibrosis following silica exposure in vivo. CD204-/- macrophages were shown to recognize and uptake silica in vitro, although this response was attenuated compared with 129Sv wild-type mice. The production of tumor necrosis factor-alpha in lavage fluid was significantly enhanced in CD204 null mice compared with wild-type mice following silica exposure. Moreover, after exposure to environmental particles, CD204-/- macrophages exhibited improved cell viability in a dose-dependent manner compared with wild-type macrophages. Finally, histopathology from a murine model of chronic silicosis in 129Sv wild-type mice displayed typical focal lesions, interstitial thickening with increased connective tissue matrix, and cellular infiltrate into air space. In contrast, CD204-/- mice exhibited little to no deposition of collagen, yet they demonstrated enhanced accumulation of inflammatory cells largely composed of neutrophils. Our findings point to an important role of CD204 in mounting an efficient and appropriately regulated immune response against inhaled particles. Furthermore, these results indicate that the functions of CD204 are critical to the development of fibrosis and the resolution of inflammation.
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Affiliation(s)
- Celine A Beamer
- Univ. of Montana, Center for Environmental Health Sciences, Dept. of Biomedical and Pharmaceutical Sciences, School of Pharmacy and Allied Health Sciences, Skaggs Bldg., Rm. 155, Missoula, MT 59812-1552, USA.
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17
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Prevo R, Banerji S, Ni J, Jackson DG. Rapid plasma membrane-endosomal trafficking of the lymph node sinus and high endothelial venule scavenger receptor/homing receptor stabilin-1 (FEEL-1/CLEVER-1). J Biol Chem 2004; 279:52580-92. [PMID: 15345716 DOI: 10.1074/jbc.m406897200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The sinusoidal endothelia of liver, spleen, and lymph node are major sites for uptake and recycling of waste macromolecules through promiscuous binding to a disparate family of scavenger receptors. Among the most complex is stabilin-1, a large multidomain protein containing tandem fasciclin domains, epidermal growth factor-like repeats, and a C-type lectin-like hyaluronan-binding Link module, which functions as an endocytic receptor for acetylated low density lipoprotein and advanced glycation end products. Intriguingly, stabilin-1 has also been reported to mediate both homing of leukocytes across lymph node high endothelial venules and adhesion of metastatic tumor cells to peritumoral lymphatic vessels. Currently, however, it is not clear how stabilin-1 mediates these distinct functions. To address the issue, we have investigated the tissue and subcellular localization of stabilin-1 in detail and assessed the functional status of its Link module. We show that stabilin-1 is almost entirely intracellular in lymph node high endothelial venules, lymphatic sinus endothelium, and cultured endothelial cells but that a finite population, detectable only by fluorescent antibody or fluorescein-labeled (Fl)-acetylated low density lipoprotein uptake, cycles rapidly between the plasma membrane and EEA-1+ve (early endosome antigen 1) early endosomes. In addition, we show using full-length stabilin-1 cDNA and a stabilin-1/CD44 chimera in HeLa cells that intracellular targeting is influenced by the transmembrane domain/cytoplasmic tail, which contains a putative dileucine (DXXLL) Golgi to endosomal sorting signal. Finally, we provide evidence that the stabilin-1 Link domain binds neither hyaluronan nor other glycosaminoglycans. These properties support a role for stabilin-1 as a rapidly recycling scavenger receptor and argue against a role in cell adhesion or lymphocyte homing.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Biological Transport, Active
- Cell Adhesion Molecules, Neuronal/chemistry
- Cell Adhesion Molecules, Neuronal/genetics
- Cell Adhesion Molecules, Neuronal/metabolism
- Cell Membrane/metabolism
- Cells, Cultured
- DNA, Complementary/genetics
- Endosomes/metabolism
- Endothelium, Lymphatic/metabolism
- HeLa Cells
- Humans
- Kinetics
- Models, Molecular
- Molecular Sequence Data
- Protein Conformation
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Receptors, Lymphocyte Homing/chemistry
- Receptors, Lymphocyte Homing/genetics
- Receptors, Lymphocyte Homing/metabolism
- Receptors, Scavenger
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Sequence Homology, Amino Acid
- Transfection
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Affiliation(s)
- Remko Prevo
- Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, United Kingdom
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18
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Józefowski S, Kobzik L. Scavenger receptor A mediates H2O2 production and suppression of IL-12 release in murine macrophages. J Leukoc Biol 2004; 76:1066-74. [PMID: 15316030 DOI: 10.1189/jlb.0504270] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Although class A type I/II scavenger receptor (SR-A) is involved in numerous macrophage functions, its signaling ability remains uncertain. We used monoclonal antibodies (mAb) to specifically stimulate receptors on mouse alveolar (AMs) and peritoneal macrophages (PMs). Immobilized anti-SR-A (2F8) and anti-FcgammaR II/III (2.4G2) mAb stimulated hydrogen peroxide (H2O2) production in normal C3H/HeJ AMs (by 55% and 98%, respectively) and resident PMs (66% and 128%). The 2F8 mAb-stimulated H2O2 production resulted from specific stimulation of SR-A, since this response was absent in AMs from SR-A-deficient or C57BL/6 mice--the latter strain expressing an allelic form of SR-A, unrecognizable by 2F8 mAb. H2O2 production stimulated by anti-SR-A but not by anti-FcgammaRII/III mAb was preserved in FcgammaRI/III-deficient mice, ruling out involvement of FcgammaRs in the 2F8 mAb effect. In comparison with the FcgammaR-stimulated respiratory burst, the response to anti-SR-A mAb was delayed and, unlike the former, inhibited by pertussis toxin. Ligation of SR-A also inhibited lipopolysaccharide plus interferon-gamma-stimulated interleukin-12 (IL-12) release, by 25% in AMs and by 68% in thioglycollate-elicited PMs, consistent with different levels of SR-A expression. Neither nitrite nor IL-6 accumulation was affected by anti-SR-A mAb. SR-A-stimulated H2O2 does not seem to mediate the inhibition of IL-12 release, since the inhibition was neither reversed by scavenging of H2O2 nor mimicked by exogenous H2O2. Our results indicate that SR-A not only mediates endocytosis but can also generate signals such as H2O2, which may affect microbicidal or proinflammatory functions.
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Affiliation(s)
- Szczepan Józefowski
- Physiology Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA.
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Mukhopadhyay S, Gordon S. The role of scavenger receptors in pathogen recognition and innate immunity. Immunobiology 2004; 209:39-49. [PMID: 15481139 DOI: 10.1016/j.imbio.2004.02.004] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Scavenger receptors represent a large family of structurally unrelated distinct gene products, expressed by myeloid and selected endothelial cells and able to recognise modified low-density lipoproteins. They also bind and internalise a variety of microbial pathogens, as well as modified or endogenous molecules derived from the host, and contribute to a range of physiological or pathological processes.
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Affiliation(s)
- Subhankar Mukhopadhyay
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK.
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20
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Willis MS, Thiele GM, Tuma DJ, Klassen LW. T cell proliferative responses to malondialdehyde-acetaldehyde haptenated protein are scavenger receptor mediated. Int Immunopharmacol 2003; 3:1381-99. [PMID: 12946435 DOI: 10.1016/s1567-5769(03)00136-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Malondialdehyde-acetaldehyde (MAA) haptenated proteins have been described in disease processes related to prolonged oxidative stress (via malondialdehyde production), such as alcohol liver disease (ALD), non-alcoholic non-steatohepatitis (NASH) and atherosclerosis. Experimentally, high titer IgG1 antibody responses are seen after immunization without adjuvant; however, T cell proliferative responses and the role of scavenger receptors in this immunogenicity has not previously been described. In this study, T cell proliferative responses to the carrier protein, but not the MAA hapten itself, were identified in vitro. Moreover, these T proliferative responses were inhibited when MAA-hen egg lysozyme (HEL) was co-immunized with excess scavenger receptor ligand polyG (poly-guanylic acid), implicating the role of (a) scavenger receptor(s) in initiating the T helper cell response. Activated B cells were unable to process and present MAA-HEL preferentially to T cells, while thioglycollate-elicited (but not Con A-elicited) macrophages and dendritic cells (DC) did so with approximately 32-fold less MAA-HEL than native antigen necessary to initiate equal proliferative responses. While this preferential processing and presentation may be related to several factors, preferential binding of MAA haptenated proteins mediated by scavenger receptors may be one mechanism. IL-4 was absent from the supernatants of T proliferative assays despite a strong IgG1 response in vivo, although the TH2 cytokines IL-6 and IL-10 were expressed. Since the modification of proteins by the MAA have previously been shown to occur after ethanol consumption in vivo, the ability of MAA haptens to experimentally enhance immune responses, specifically humoral and T cell responses, may represent mechanisms by which autoimmune phenomena found in ALD occur.
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Affiliation(s)
- Monte S Willis
- Veterans Affairs Alcohol Research Center, Omaha Veterans Affairs Medical Center, 4101 Woolworth Ave., Omaha, NE 68105.
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21
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Karlsson MC, Guinamard R, Bolland S, Sankala M, Steinman RM, Ravetch JV. Macrophages control the retention and trafficking of B lymphocytes in the splenic marginal zone. J Exp Med 2003; 198:333-40. [PMID: 12874264 PMCID: PMC2194070 DOI: 10.1084/jem.20030684] [Citation(s) in RCA: 181] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The marginal zone of the spleen is a precisely ordered region that contains specialized subsets of B lymphocytes and macrophages. Disruption of the negative signaling inositol phosphatase, SH2-containing inositol-5-phosphatase 1 (SHIP), results in the loss of marginal zone B cells (MZBs) with reorganization of marginal zone macrophages (MZMOs) to the red pulp of the spleen. This primary macrophage defect, as revealed by selectively depleting SHIP in myeloid cells shows that MZMOs are specifically required for the retention of MZBs. The MZMO phenotype was reverted in SHIP/Bruton's tyrosine kinase (Btk) double knockout mice, thus identifying the Btk activating pathway as an essential component being regulated by SHIP. Furthermore, we identified a direct interaction between the MARCO scavenger receptor on MZMOs and MZBs. Activation or disruption of this interaction results in MZB migration to the follicle. The migration of the MZMOs was further studied after the response to Staphylococcus aureus, which induced MZMOs to move into the red pulp while MZBs migrated into the follicular zone. The marginal zone is therefore a dynamic structure in which retention and trafficking of B cells requires specific macrophage-B cell interactions.
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Affiliation(s)
- Mikael C.I. Karlsson
- Laboratory of Molecular Genetics and Immunology, The Rockefeller University, New York, NY 10021
| | - Rodolphe Guinamard
- Laboratory of Molecular Genetics and Immunology, The Rockefeller University, New York, NY 10021
- Centre d'Immunologie de Marseille Luminy, CNRS-INSERM-Universite de la Mediterranee, 13288 Marseille, France
| | - Silvia Bolland
- Laboratory of Molecular Genetics and Immunology, The Rockefeller University, New York, NY 10021
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases/National Institutes of Health, Rockville, MD 20852
| | - Marko Sankala
- Department of Medical Biochemistry and Biophysics, Division of Matrix Biology, The Karolinska Institute, 17177 Stockholm, Sweden
| | - Ralph M. Steinman
- Cellular Physiology and Immunology, The Rockefeller University, New York, NY 10021
| | - Jeffrey V. Ravetch
- Laboratory of Molecular Genetics and Immunology, The Rockefeller University, New York, NY 10021
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22
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Santiago-García J, Kodama T, Pitas RE. The class A scavenger receptor binds to proteoglycans and mediates adhesion of macrophages to the extracellular matrix. J Biol Chem 2003; 278:6942-6. [PMID: 12488451 DOI: 10.1074/jbc.m208358200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The class A scavenger receptor (SR-A) binds modified lipoproteins and has been implicated in cholesterol ester deposition in macrophages. The SR-A also contributes to cellular adhesion. Using SR-A(+/+) and SR-A(-)/- murine macrophages, we found SR-A expression important for both divalent cation-dependent and -independent adhesion of macrophages to the human smooth muscle cell extracellular matrix. The SR-A mediated 65 and 85% of macrophage adhesion to the extracellular matrix in the presence and absence of serum, respectively. When EDTA was added to chelate divalent cations, the SR-A mediated 90 and 95% of the macrophage adhesion without and with serum, respectively. SR-A-mediated adhesion to the extracellular matrix was prevented by fucoidin, an SR-A antagonist. Biglycan and decorin, proteoglycans of the extracellular matrix, were identified as SR-A ligands. Compared with control cells, Chinese hamster ovary cells expressing the SR-A showed 5- and 6-fold greater cell association (binding and internalization) of (125)I-decorin and -biglycan, respectively. In competition studies, unlabeled proteoglycan or fucoidin competed for binding of (125)I-labeled decorin and -biglycan, and biglycan and decorin competed for the SR-A-mediated cell association and degradation of (125)I-labeled acetylated LDL, a well characterized ligand for the SR-A. These results suggest that the SR-A could contribute to the adhesion of macrophages to the extracellular matrix of atherosclerotic plaques.
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Affiliation(s)
- Juan Santiago-García
- Gladstone Institutes of Cardiovascular Disease and Neurological Disease, Cardiovascular Research Institute, Department of Pathology, University of California, San Francisco, California 94143, USA
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23
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24
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Hansen B, Arteta B, Smedsrød B. The physiological scavenger receptor function of hepatic sinusoidal endothelial and Kupffer cells is independent of scavenger receptor class A type I and II. Mol Cell Biochem 2002; 240:1-8. [PMID: 12487366 DOI: 10.1023/a:1020660303855] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This study was undertaken to determine the role of scavenger receptor class A type I and II (SR-Al/II) in the physiological scavenger function of hepatic sinusoidal endothelial cells (SEC) and Kupffer cells (KC). Following intravenous administration of radiolabelled SR-ligands, [advanced glycation end (AGE)-products, N-terminal propeptide of type III procollagen (PIIINP) and formaldehyde treated serum albumin (FSA)] in SR-AI/II-deficient and wild-type mice, radioactivity was removed equally rapidly from the circulation of both types of mice. The major site of uptake was the liver. Separation of liver cells showed that the population of SEC and KC were responsible for approximately 55 and approximately 25% of the uptake. There was no difference in plasma clearance, organ distribution or cell distribution in SR-Al/Il-deficient and wild-type mice. Experiments performed to determine the specificity of endocytosis in cultured SEC showed that uptake of radiolabelled SR-ligands (AGE-protein, PIIINP or FSA) was inhibited equally well by unlabelled FSA and AGE-protein in SEC from receptor deficient and wild-type mice. We conclude from these findings that SR-Al/lI is of minor importance in the plasma clearance of physiological as well as foreign SR-ligands.
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Affiliation(s)
- Berit Hansen
- Department of Experimental Pathology, Institute of Medical Biology, University of Tromsø, Tromsø, Norway.
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25
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Ishii J, Adachi H, Aoki J, Koizumi H, Tomita S, Suzuki T, Tsujimoto M, Inoue K, Arai H. SREC-II, a new member of the scavenger receptor type F family, trans-interacts with SREC-I through its extracellular domain. J Biol Chem 2002; 277:39696-702. [PMID: 12154095 DOI: 10.1074/jbc.m206140200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The scavenger receptor expressed by endothelial cells (SREC) with an extremely large cytoplasmic domain, was originally identified in a human endothelial cell line. In this study, we have cloned a second isoform named SREC-II and shown that there is a heterophilic interaction between SREC-I and -II at their extracellular domains. The cDNA for murine SREC-II encodes an 834-amino acid protein with 35% homology to SREC-I. Similar to SREC-I, SREC-II contains multiple epidermal growth factor-like repeats in its extracellular domain. However, in contrast to SREC-I, SREC-II had little activity to internalize modified low density lipoproteins (LDL). A Northern blot analysis revealed a tissue expression pattern of SREC-II similar to that of SREC-I with predominant expression in human heart, lung, ovary, and placenta. Mouse fibroblast L cells with no tendency to associate showed noticeable aggregation when SREC-I was overexpressed in these cells, whereas overexpression of SREC-II caused only slight aggregation. Remarkably, intense aggregation was observed when SREC-I-expressing cells were mixed with those expressing SREC-II. Deletion of almost all of the cytoplasmic receptor domain had no effect on the receptor expression and cell aggregation, indicating that solely the extracellular domain is involved in cell aggregation. The association of SREC-I and -II was effectively suppressed by the presence of scavenger receptor ligands such as acetylated LDL and oxidized LDL. These findings suggest that SREC-I and -II show weak cell-cell interaction by their extracellular domains (termed homophilic trans-interaction) but display strong heterophilic trans-interaction through the extracellular epidermal growth factor-like repeat domains.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Northern
- CHO Cells
- Cell Adhesion Molecules
- Cell Division
- Cloning, Molecular
- Cricetinae
- DNA, Complementary/metabolism
- Databases as Topic
- Expressed Sequence Tags
- Gene Deletion
- Humans
- Leukocytes/metabolism
- Lipoproteins/metabolism
- Mice
- Molecular Sequence Data
- Oxygen/metabolism
- Phosphorylation
- Protein Binding
- Protein Structure, Tertiary
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/metabolism
- Receptors, LDL/chemistry
- Receptors, LDL/metabolism
- Receptors, Scavenger
- Scavenger Receptors, Class F
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tissue Distribution
- Transfection
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Affiliation(s)
- Junko Ishii
- Laboratory of Cellular Biochemistry, RIKEN (the Institute of Physical and Chemical Research), 2-1 Wako-shi, Saitama 351-0198, Japan
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26
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Whitman SC, Rateri DL, Szilvassy SJ, Cornicelli JA, Daugherty A. Macrophage-specific expression of class A scavenger receptors in LDL receptor−/− mice decreases atherosclerosis and changes spleen morphology. J Lipid Res 2002. [DOI: 10.1194/jlr.m200116-jlr200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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27
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Platt N, Haworth R, Darley L, Gordon S. The many roles of the class A macrophage scavenger receptor. INTERNATIONAL REVIEW OF CYTOLOGY 2002; 212:1-40. [PMID: 11804035 DOI: 10.1016/s0074-7696(01)12002-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The class A macrophage scavenger receptor (SR-A) is the prototypic example of a group of plasma membrane receptors collectively known as scavenger receptors. SR-A displays the ability to bind and endocytose large quantities of modified lipoprotein. Hence, it is thought to be one of the main receptors involved in mediating lipid influx into macrophages (Mphi), which promotes their conversion into foam cells that are abundant in the atherosclerotic lesion. However, as a result of increased interest and research effort and through the development of specific reagents and animal models, it is now appreciated to be multifunctional. These roles include Mphi growth and maintenance, adhesion to the substratum, cell-cell interactions, phagocytosis, and host defense. In this review, we attempt to summarize the evidence and argue that these kinds of activities underlie the biological versatility of Mphi.
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Affiliation(s)
- Nick Platt
- Sir William Dunn School of Pathology, University of Oxford, United Kingdom
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28
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Carvalho MDT, Harada LM, Gidlund M, Ketelhuth DFJ, Boschcov P, Quintão ECR. Macrophages take up triacylglycerol-rich emulsions at a faster rate upon co-incubation with native and modified LDL: An investigation on the role of natural chylomicrons in atherosclerosis. J Cell Biochem 2002; 84:309-23. [PMID: 11787060 DOI: 10.1002/jcb.10020] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Chylomicrons play a role in atherosclerosis, however, because the mechanisms involved in the cell uptake of these particles are not fully understood, investigations were carried out using a radioactively labeled protein-free triacylglycerol-rich emulsion incubated with peritoneal macrophages obtained from normal and apoE-knockout mice. Experiments were done in the presence of substances that inhibit several endocytic processes: EDTA for low density lipoprotein receptor, fucoidan for scavenger receptor, cytochalasin B for phagocytosis, and a lipopolysaccharide for lipoprotein lipase. In addition, triacylglycerol-rich emulsions were also prepared in the presence of native or modified radioactively labeled low density lipoprotein particles that are known to accumulate in the arterial intima. Probucol was also used to prevent the possible role played by an antioxidant in triacylglycerol-rich emulsion uptake. We have shown that triacylglycerol-rich emulsion alone is taken up by a coated-pit-dependent mechanism, mediated by macrophage secretion of apolipoprotein E. Furthermore, native, aggregated, acetylated, and moderately macrophage-oxidized low density lipoprotein stimulate the uptake of a triacylglycerol-rich emulsion through several mechanisms such as an actin-dependent pathway, scavenger receptors, and lipolysis mediated by lipoprotein lipase. On the other hand, in spite of the interaction of low density lipoprotein forms with a triacylglycerol-rich emulsion, the cellular triacylglycerol-rich emulsion uptake is impaired by copper-oxidized low density lipoprotein, possibly due to its diminished affinity towards lipoprotein lipase. We have also shown that macrophages take up aggregated low density lipoprotein better than the acetylated or oxidized forms of low density lipoprotein.
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Affiliation(s)
- Márcia D T Carvalho
- Lipids Laboratory (LIM/10), University of São Paulo Medical School, São Paulo, Brazil
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29
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Hansen B, Melkko J, Smedsrød B. Serum is a rich source of ligands for the scavenger receptor of hepatic sinusoidal endothelial cells. Mol Cell Biochem 2002; 229:63-72. [PMID: 11936848 DOI: 10.1023/a:1017919800347] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The present study was prompted by findings in our laboratory showing that serum effectively inhibits scavenger receptor (SR)-mediated endocytosis in hepatic sinusoidal endothelial cells (SEC). Experiments with SEC in vitro showed that the presence of 20% human serum inhibited endocytosis of SR ligands, 125I-formaldehyde treated bovine serum albumin (FSA) and 125I-nidogen, by 30 and 50%, respectively, whereas pre-heated foetal bovine serum (10%) inhibited endocytosis of 125I-FSA by as much as 56%. Human, bovine and rat serum had similar inhibitory effect on endocytosis in SEC. Fractionation of foetal bovine and human serum on anion exchange chromatography demonstrated that the inhibitory principle co-purified with macromolecules of high negative charge. The serum fraction that most effectively inhibited SR-mediated endocytosis of 125I-FSA did not affect mannose receptor-mediated endocytosis of 125I-mannan to the same extent. Trap-labelled negatively charged serum fraction administered intravenously to rats was eliminated almost exclusively by liver, with a blood decay of 50% over the first 3 min after injection. Isolation of liver cells showed that the populations of Kupffer cells and SEC contained 39 and 61% of liver radioactivity 30 min after injection of trap-labelled negatively charged fractions prepared from pre-heated ('complement inactivated') foetal bovine sera. These findings suggest that the process of serum formation from native blood generates appreciable amounts of macromolecules that compete specifically with the SR for endocytosis in SEC. The inhibitory power of pre-heated serum is particularly great. For this reason pre-heated serum should be used with caution in studies of SR in SEC.
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Affiliation(s)
- Berit Hansen
- Department of Experimental Pathology, Institute of Medical Biology, University of Tromsø, Norway.
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30
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Daugherty A, Kosswig N, Cornicelli JA, Whitman SC, Wolle S, Rateri DL. Macrophage-specific expression of class A scavenger receptors enhances granuloma formation in the absence of increased lipid deposition. J Lipid Res 2001. [DOI: 10.1016/s0022-2275(20)31593-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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31
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Gowen BB, Borg TK, Ghaffar A, Mayer EP. The collagenous domain of class A scavenger receptors is involved in macrophage adhesion to collagens. J Leukoc Biol 2001. [DOI: 10.1189/jlb.69.4.575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Brian B. Gowen
- Departments of Microbiology and Immunology, University of South Carolina, School of Medicine, Columbia, South Carolina
| | - Thomas K. Borg
- Departments of Developmental Biology and Anatomy, University of South Carolina, School of Medicine, Columbia, South Carolina
| | - Abdul Ghaffar
- Departments of Microbiology and Immunology, University of South Carolina, School of Medicine, Columbia, South Carolina
| | - Eugene P. Mayer
- Departments of Microbiology and Immunology, University of South Carolina, School of Medicine, Columbia, South Carolina
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Miles EA, Wallace FA, Calder PC. Dietary fish oil reduces intercellular adhesion molecule 1 and scavenger receptor expression on murine macrophages. Atherosclerosis 2000; 152:43-50. [PMID: 10996338 DOI: 10.1016/s0021-9150(99)00446-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
During atherogenesis, a pathological accumulation of lipids occurs within aortic intimal macrophages through uptake of oxidised low-density lipoprotein (LDL) via scavenger receptors. Here we investigate whether some of the anti-atherosclerotic effects ascribed to dietary fish oil are mediated through effects on macrophage intercellular adhesion molecule 1 (ICAM-1) and scavenger receptor expression. Mice were fed on a low fat diet (containing 25 g/kg corn oil) or on high fat diets containing 200 g/kg coconut oil, safflower oil or fish oil. Thioglycollate-elicited peritoneal macrophages were analysed for fatty acid composition by gas chromatography. Macrophage scavenger receptor A (MSR-A) type I+type II and ICAM-1 expression were measured by flow cytometry and the levels of mRNA coding for MSR-A type I, MSR-A type II and ICAM-1 were measured by reverse-transcription polymerase chain reaction. Feeding mice diets enriched with different fats resulted in significant changes in the fatty acid profile of macrophages, which reflected the fatty acid compositions of the diets. Macrophages from the fish oil fed mice had the lowest expression of ICAM-1 and MSR-A at the level of both mRNA and cell surface expression. The reduced expression of ICAM-1 and MSR-A on macrophages from mice fed on a fish oil-rich diet supports our hypothesis that part of the protective effect of fish oil against atherosclerosis might be due to an altered macrophage phenotype and function ameliorating macrophage-induced plaque formation.
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MESH Headings
- Analysis of Variance
- Animals
- Base Sequence
- Cells, Cultured
- Chromatography, Gas
- Coconut Oil
- Corn Oil/pharmacology
- Diet, Fat-Restricted
- Fish Oils/pharmacology
- Flow Cytometry
- Intercellular Adhesion Molecule-1/analysis
- Intercellular Adhesion Molecule-1/drug effects
- Macrophages, Peritoneal/drug effects
- Macrophages, Peritoneal/metabolism
- Male
- Membrane Proteins
- Mice
- Mice, Inbred C57BL
- Models, Animal
- Molecular Sequence Data
- Plant Oils/pharmacology
- Polymerase Chain Reaction
- Probability
- RNA, Messenger/analysis
- Receptors, Immunologic/analysis
- Receptors, Immunologic/drug effects
- Receptors, Lipoprotein
- Receptors, Scavenger
- Reference Values
- Safflower Oil/pharmacology
- Scavenger Receptors, Class B
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Affiliation(s)
- E A Miles
- Institute of Human Nutrition, University of Southampton, Bassett Crescent East, SO16 7PX, Southampton, UK.
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Terpstra V, van Amersfoort ES, van Velzen AG, Kuiper J, van Berkel TJ. Hepatic and extrahepatic scavenger receptors: function in relation to disease. Arterioscler Thromb Vasc Biol 2000; 20:1860-72. [PMID: 10938005 DOI: 10.1161/01.atv.20.8.1860] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- V Terpstra
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, University of Leiden, Sylvius Laboratories, Leiden, the Netherlands
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Fitzpatrick SL, Kassam G, Manro A, Braat CE, Louie P, Waisman DM. Fucoidan-dependent conformational changes in annexin II tetramer. Biochemistry 2000; 39:2140-8. [PMID: 10694379 DOI: 10.1021/bi992180z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fucoidan, a sulfated fucopolysaccharide, mimics the fucosylated glycans of glycoproteins and has therefore been used as a probe for investigating the role of membrane polysaccharides in cell-cell adhesion. In the present report we have characterized the interaction of fucoidan with the Ca(2+)- and phospholipid-binding protein annexin II tetramer (AIIt). AIIt bound to fucoidan with an apparent K(d) of 1.24 +/- 0.69 nM (mean +/- SD, n = 3) with a stoichiometry of 0.010 +/- 0.001 mol of fucoidan/mol of AIIt (mean +/- SD, n = 3). The binding of fucoidan to AIIt was Ca(2+)-independent. Furthermore, in the presence but not the absence of Ca(2+), the binding of fucoidan to AIIt caused a decrease in the alpha-helical content from 32% to 7%. A peptide corresponding to a region of the p36 subunit of AIIt, F(306)-S(313), which contains a Cardin-Weintraub consensus sequence for heparin binding, was shown to undergo a conformational change upon fucoidan binding. This suggests that heparin and fucoidan bound to this region of AIIt. The binding of fucoidan but not heparin by AIIt also inhibited the ability of AIIt to bind to and aggregate phospholipid liposomes. These results suggest that the binding of AIIt to the carbohydrate conjugates of certain membrane glycoproteins may have profound effects on the structure and biological activity of AIIt.
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Affiliation(s)
- S L Fitzpatrick
- Cancer Biology Research Group, Department of Medical Biochemistry, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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de Winther MP, van Dijk KW, Havekes LM, Hofker MH. Macrophage scavenger receptor class A: A multifunctional receptor in atherosclerosis. Arterioscler Thromb Vasc Biol 2000; 20:290-7. [PMID: 10669623 DOI: 10.1161/01.atv.20.2.290] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In atherogenesis, elevated plasma levels of low density lipoprotein (LDL) lead to the chronic presence of LDL in the arterial wall. There, LDL is modified (eg, oxidized), and these modified lipoproteins activate endothelial cells, which attract circulating monocytes. These monocytes enter the vessel wall, differentiate into macrophages, and subject the modified lipoproteins to endocytosis through scavenger receptor pathways. This unrestricted uptake, which is not limited by intracellular cholesterol levels, eventually leads to the formation of lipid-filled foam cells, the initial step in atherosclerosis. Macrophage scavenger receptor class A (SRA) is thought to be one of the main receptors involved in foam cell formation, mediating the influx of lipids into the macrophages. In addition to this role in modified lipoprotein uptake by macrophages, the SRA has been shown to be important in the inflammatory response in host defense, cellular activation, adhesion, and cell-cell interaction. Given the importance of these processes in atherogenesis, these latter functions may prove to make the SRA a multifunctional player in the atherosclerotic process.
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Affiliation(s)
- M P de Winther
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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Gowen BB, Borg TK, Ghaffar A, Mayer EP. Selective adhesion of macrophages to denatured forms of type I collagen is mediated by scavenger receptors. Matrix Biol 2000; 19:61-71. [PMID: 10686426 DOI: 10.1016/s0945-053x(99)00052-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Macrophages (Mφs) are multifunctional immune cells which are involved in the regulation of immune and inflammatory responses, as well as in tissue repair and remodeling. In tissues, Mφs reside in areas which are rich in extracellular matrix (ECM), the structural component which also plays an essential role in regulating a variety of cellular functions. A major ECM protein encountered by Mφs is type I collagen, the most abundant of the fibril-forming collagens. In this study, the adhesion of RAW 264.7 murine Mphis to native fibrillar, monomeric, and denatured type I collagen was investigated. Using atomic force microscopy, structural differences between fibrillar and monomeric type I collagen were clearly resolved. When cultured on fibrillar type I collagen, Mphis adhered poorly. In contrast, they adhered significantly to monomeric, heat-denatured, or collagenase-modified type I collagen. Studies utilizing anti-beta1 and -beta2 integrin adhesion-blocking antibodies, RGD-containing peptides, or divalent cation-free conditions did not inhibit Mphi; adhesion to monomeric or denatured type I collagen. However, macrophage scavenger receptor (MSR) ligands and anti-MSR antibodies significantly blocked Mphi; adhesion to denatured and monomeric type I collagen strongly suggesting the involvement of the MSR as an adhesion molecule for denatured type I collagen. Further analysis by Western blot identified the MSR as the primary receptor for denatured type I collagen among Mphi; proteins purified from a heat-denatured type I collagen affinity column. These findings indicate that Mphis adhere selectively to denatured forms of type I collagen, but not the native fibrillar conformation, via their scavenger receptors.
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Affiliation(s)
- B B Gowen
- Department of Microbiology and Immunology, University of South Carolina, School of Medicine, Columbia 29208, USA
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Kangas M, Brännström A, Elomaa O, Matsuda Y, Eddy R, Shows TB, Tryggvason K. Structure and chromosomal localization of the human and murine genes for the macrophage MARCO receptor. Genomics 1999; 58:82-9. [PMID: 10331948 DOI: 10.1006/geno.1999.5811] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The structures of the human and mouse genes for the macrophage receptor with collagenous structure were determined. Both genes have 17 exons, of which exons 4-15 encode the collagenous domain. The transcription initiation sites in the mouse gene were identified using primer extension, SI nuclease mapping, and 5' capturing rapid amplification of cDNA ends assays. All three methods revealed two major initiation sites, one starting 27 bp downstream of a TATA box and another at positions -63 and -66 downstream of an AT-rich region. Several potential binding sites for transcription factors were identified in the promoter region, neither gene has a CAAT box or GC boxes. The human and mouse genes were localized to syntenic regions on chromosomes 2 and 1, respectively, using fluorescence in situ hybridization.
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Affiliation(s)
- M Kangas
- Biocenter Oulu and Department of Biochemistry, University of Oulu, Oulu, FIN-90570, Finland
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Nicoletti A, Caligiuri G, Törnberg I, Kodama T, Stemme S, Hansson GK. The macrophage scavenger receptor type A directs modified proteins to antigen presentation. Eur J Immunol 1999; 29:512-21. [PMID: 10064066 DOI: 10.1002/(sici)1521-4141(199902)29:02<512::aid-immu512>3.0.co;2-y] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Scavenger receptors constitute a family of cell surface receptors that internalize endotoxins, oxidized low-density lipoproteins (oxLDL) and other proteins with clustered negative charges for degradation in macrophages. They were recently proposed to play a role in antigen presentation but the type of scavenger receptor involved in this process has not been known. In this report, we have examined the cellular immune responses to modified proteins in mice lacking the SR-A scavenger receptor (SRAKO) and their wild-type (ICR) controls. While spleen cells of ICR mice immunized with maleylated murine serum albumin (Mal-MSA) exhibit strong proliferative responses to the antigen, no such responses were found in SRAKO mice. However, addition of SR-A+ antigen-presenting cells from ICR mice unmasked proliferative responses to Mal-MSA in spleen cultures of immunized SRAKO mice. Similarly, addition of SR-A+ antigen-presenting cells was necessary to detect T cell responses in spleen cultures of oxLDL-immunized SRAKO mice. This indicates that SR-A can mediate uptake of modified antigens for presentation to antigen-specific T cells. The fact that cellular immunity developed in SRAKO mice implies that other scavenger receptor(s) also internalize modified antigens for presentation in vivo. These observations show that scavenger receptors participate in immune recognition of oxidized protein antigens; this system may be important for recognition of damaged macromolecules but could also play a role in autoimmunity.
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Affiliation(s)
- A Nicoletti
- Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
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