1
|
Grandoni F, Fraboni D, Canonico B, Papa S, Buccisano F, Schuberth HJ, Hussen J. Flow Cytometric Identification and Enumeration of Monocyte Subsets in Bovine and Water Buffalo Peripheral Blood. Curr Protoc 2023; 3:e676. [PMID: 36799694 DOI: 10.1002/cpz1.676] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Monocytes are innate immune system key players with pivotal roles during infection and inflammation. They migrate into tissues and differentiate into myeloid effect cells (macrophages, dendritic cells) which orchestrate inflammatory processes and are interfaces between the innate and adaptive immune responses. Their clinical relevance to health and disease of cattle (Bos taurus) and water buffalo (Bubalus bubalis), two of the most important livestock species, has been highlighted in physiologic (pregnancy) and pathologic (mastitis, metritis, and viral infections) conditions. The existence of three different monocyte subsets in cattle was established by flow cytometry (FC), as follows: classical (cM; CD14++ CD16-/low ), intermediate (intM; CD14++/+ CD16+ ), and non-classical (ncM; CD14-/low CD16++ ) monocytes. FC applications for studying the immune system of cattle and water buffalo still have significant limitations. In this article, we describe some practical approaches to overcome these limitations and, in particular, allow the identification and enumeration of cM, intM, and ncM subpopulations in cattle and buffalo peripheral blood. Indeed, we propose the new procedure lyse/wash/no-centrifugation (L/W/NC) that can be combined with the FC absolute counting procedures and can overcome specific issues of the lyse/no-wash protocols (L/NW). Finally, for the first time, we demonstrated the existence of cM, intM, and ncM monocyte subsets also in the water buffalo, showing some interesting differences with cattle, such as the bubaline cM are mainly CD14+/++ /CD16+ . These subtle differences may influence inflammatory disease regulation in, for example, mastitis and metritis. The upregulation of CD16 expression on cM may reveal different monocyte priming, leading to different functional features of macrophages/dendritic cells in tissues after infection. © 2023 Wiley Periodicals LLC. Basic Protocol: Absolute count of cM, intM, and ncM without compensation Alternate Protocol: Absolute count of cM, intM, and ncM for single laser platform Support Protocol 1: In-house monoclonal antibody labeling using a Pacific Blue™ kit Support Protocol 2: In-house monoclonal antibody labeling using an Alexa Fluor® 647 kit Support Protocol 3: Titration of fluorochrome-conjugated antibodies.
Collapse
Affiliation(s)
- Francesco Grandoni
- CREA-Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Centro di ricerca Zootecnia e Acquacoltura (Research Center for Animal Production and Aquaculture), Monterotondo, Italy
| | | | - Barbara Canonico
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Urbino, Italy
| | - Stefano Papa
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo", Urbino, Italy
| | - Francesco Buccisano
- Department of Biomedicine and Prevention, Tor Vergata University, Rome, Italy
| | - Hans-Joachim Schuberth
- Institute for Immunology, University of Veterinary Medicine Foundation, Hanover, Germany
| | - Jamal Hussen
- Department of Microbiology, College of Veterinary Medicine, King Faisal University, Al-Ahsa, Saudi Arabia
| |
Collapse
|
2
|
Identification of macrophages in normal and injured mouse tissues using reporter lines and antibodies. Sci Rep 2022; 12:4542. [PMID: 35296717 PMCID: PMC8927419 DOI: 10.1038/s41598-022-08278-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 03/04/2022] [Indexed: 12/20/2022] Open
Abstract
Reliable tools for macrophage identification in mouse tissues are critical for studies investigating inflammatory and reparative responses. Transgenic reporter mice and anti-macrophage antibodies have been used as “specific pan-macrophage” markers in many studies; however, organ-specific patterns of expression and non-specific labeling of other cell types, such as fibroblasts, may limit their usefulness. Our study provides a systematic comparison of macrophage labeling patterns in normal and injured mouse tissues, using the CX3CR1 and CSF1R macrophage reporter lines and anti-macrophage antibodies. Moreover, we tested the specificity of macrophage antibodies using the fibroblast-specific PDGFR\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\mathrm{\alpha }$$\end{document}α reporter line. Mouse macrophages exhibit organ-specific differences in expression of macrophage markers. Hepatic macrophages are labeled for CSF1R, Mac2 and F4/80, but lack CX3CR1 expression, whereas in the lung, the CSF1R+/Mac2+/Mac3+ macrophage population is not labeled with F4/80. In the splenic red pulp, subpopulations of CSF1R+/F4/80+/Mac3+cells were labeled with Mac2, CX3CR1 and lysozyme M. In the kidney, Mac2, Mac3 and lysozyme M labeled a fraction of the CSF1R+ and CX3CR1+ macrophages, but also stained tubular epithelial cells. In normal hearts, the majority of CSF1R+ and CX3CR1+ cells were not detected with anti-macrophage antibodies. Myocardial infarction was associated with marked expansion of the CSF1R+ and CX3CR1+ populations that peaked during the proliferative phase of cardiac repair, and also expressed Mac2, Mac3 and lysozyme M. In normal mouse tissues, a small fraction of cells labeled with anti-macrophage antibodies were identified as PDGFR\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\mathrm{\alpha }$$\end{document}α+ fibroblasts, using a reporter system. The population of PDGFR\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\mathrm{\alpha }$$\end{document}α+ cells expressing macrophage markers expanded following injury, likely reflecting emergence of cellular phenotypes with both fibroblast and macrophage characteristics. In conclusion, mouse macrophages exhibit remarkable heterogeneity. Selection of the most appropriate markers for identification of macrophages in mouse tissues is dependent on the organ and the pathologic condition studied.
Collapse
|
3
|
Grandoni F, Scatà MC, Martucciello A, De Carlo E, De Matteis G, Hussen J. Comprehensive phenotyping of peripheral blood monocytes in healthy bovine. Cytometry A 2021; 101:122-130. [PMID: 34382742 DOI: 10.1002/cyto.a.24492] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 07/06/2021] [Accepted: 07/16/2021] [Indexed: 12/20/2022]
Abstract
Monocytes are bone marrow derived innate myeloid cells that circulate in the blood and play important roles in infection and inflammation. As part of the mononuclear phagocytic system, monocytes provide innate effector functions, support the adaptive immune response, and play a role in the maintenance of tissue homeostasis. In addition to their role in sensing pathogen-associated molecular patterns using several pattern recognition receptors, monocytes are characterized by their ability to ingest and kill microbes, to produce cytokines and chemokines, and to present antigens to T cells. For a long time, monocytes have been considered as a homogenous cell population, characterized by the expression of CD14, the receptor of lipopolysaccharide. Studies in several species have shown that the monocyte population consists of phenotypically and functionally different cell subsets. In this review, we report a comprehensive phenotyping of monocyte subsets in cattle. In addition, the most characterizing cell markers and gating strategies for detailed immunophenotyping of bovine monocyte subsets are discussed.
Collapse
Affiliation(s)
- Francesco Grandoni
- Centro di ricerca Zootecnia e Acquacoltura (Research Centre for Animal Production and Aquaculture), CREA-Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Monterotondo, Rome, Italy
| | - Maria Carmela Scatà
- Centro di ricerca Zootecnia e Acquacoltura (Research Centre for Animal Production and Aquaculture), CREA-Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Monterotondo, Rome, Italy
| | - Alessandra Martucciello
- National Reference Centre for Hygiene and Technologies of Water Buffalo Farming and Productions, Istituto Zooprofilattico Sperimentale del Mezzogiorno, Salerno, Italy
| | - Esterina De Carlo
- National Reference Centre for Hygiene and Technologies of Water Buffalo Farming and Productions, Istituto Zooprofilattico Sperimentale del Mezzogiorno, Salerno, Italy
| | - Giovanna De Matteis
- Centro di ricerca Zootecnia e Acquacoltura (Research Centre for Animal Production and Aquaculture), CREA-Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Monterotondo, Rome, Italy
| | - Jamal Hussen
- Department of Microbiology, King Faisal University College of Veterinary Medicine, Al-Ahsa, Saudi Arabia
| |
Collapse
|
4
|
Hume DA, Caruso M, Keshvari S, Patkar OL, Sehgal A, Bush SJ, Summers KM, Pridans C, Irvine KM. The Mononuclear Phagocyte System of the Rat. THE JOURNAL OF IMMUNOLOGY 2021; 206:2251-2263. [PMID: 33965905 DOI: 10.4049/jimmunol.2100136] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/01/2021] [Indexed: 12/14/2022]
Abstract
The laboratory rat continues to be the model of choice for many studies of physiology, behavior, and complex human diseases. Cells of the mononuclear phagocyte system (MPS; monocytes, macrophages, and dendritic cells) are abundant residents in every tissue in the body and regulate postnatal development, homeostasis, and innate and acquired immunity. Recruitment and proliferation of MPS cells is an essential component of both initiation and resolution of inflammation. The large majority of current knowledge of MPS biology is derived from studies of inbred mice, but advances in technology and resources have eliminated many of the advantages of the mouse as a model. In this article, we review the tools available and the current state of knowledge of development, homeostasis, regulation, and diversity within the MPS of the rat.
Collapse
Affiliation(s)
- David A Hume
- Mater Research Institute-University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Melanie Caruso
- Mater Research Institute-University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Sahar Keshvari
- Mater Research Institute-University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Omkar L Patkar
- Mater Research Institute-University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Anuj Sehgal
- Mater Research Institute-University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Stephen J Bush
- Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Kim M Summers
- Mater Research Institute-University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Clare Pridans
- Centre for Inflammation Research, University of Edinburgh, Edinburgh, United Kingdom.,Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Katharine M Irvine
- Mater Research Institute-University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| |
Collapse
|
5
|
Pridans C, Irvine KM, Davis GM, Lefevre L, Bush SJ, Hume DA. Transcriptomic Analysis of Rat Macrophages. Front Immunol 2021; 11:594594. [PMID: 33633725 PMCID: PMC7902030 DOI: 10.3389/fimmu.2020.594594] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 12/17/2020] [Indexed: 12/13/2022] Open
Abstract
The laboratory rat is widely used as a model for human diseases. Many of these diseases involve monocytes and tissue macrophages in different states of activation. Whilst methods for in vitro differentiation of mouse macrophages from embryonic stem cells (ESC) and bone marrow (BM) are well established, these are lacking for the rat. The gene expression profiles of rat macrophages have also not been characterised to the same extent as mouse. We have established the methodology for production of rat ESC-derived macrophages and compared their gene expression profiles to macrophages obtained from the lung and peritoneal cavity and those differentiated from BM and blood monocytes. We determined the gene signature of Kupffer cells in the liver using rats deficient in macrophage colony stimulating factor receptor (CSF1R). We also examined the response of BM-derived macrophages to lipopolysaccharide (LPS). The results indicate that many, but not all, tissue-specific adaptations observed in mice are conserved in the rat. Importantly, we show that unlike mice, rat macrophages express the CSF1R ligand, colony stimulating factor 1 (CSF1).
Collapse
Affiliation(s)
- Clare Pridans
- Centre for Inflammation Research, University of Edinburgh Centre for Inflammation Research, Edinburgh, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, United Kingdom
| | - Katharine M. Irvine
- Mater Research Institute Mater Research Institute – University of Queensland, Brisbane, QLD, Australia
| | - Gemma M. Davis
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Lucas Lefevre
- UK Dementia Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Stephen J. Bush
- Nuffield Department of Clinical Medicine, University of Oxford, Headington, United Kingdom
| | - David A. Hume
- Mater Research Institute Mater Research Institute – University of Queensland, Brisbane, QLD, Australia
| |
Collapse
|
6
|
Ahmed MH, Wilkens MR, Möller B, Ganter M, Breves G, Schuberth HJ. Blood leukocyte composition and function in periparturient ewes kept on different dietary magnesium supply. BMC Vet Res 2020; 16:484. [PMID: 33317521 PMCID: PMC7734835 DOI: 10.1186/s12917-020-02705-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 12/02/2020] [Indexed: 01/06/2023] Open
Abstract
Background Transition period (TP) is characterised by physiological and metabolic changes contributing to immunodysregulation. Since knowledge about this period in sheep is scarce, we analysed changes in selected immune variables during the TP in ewes and whether dietary magnesium (Mg) supplementation could modulate these immune variables. Pregnant ewes (2nd and 3rd lactation) were divided into a control group (CONT, n = 9) and a Mg group (MAG, n = 10) supplemented with Mg oxide resulting in a daily Mg intake of approximately 0.30 and 0.38% (MAG) of dry matter during ante- (a.p.) and post-partum (p.p.) periods, respectively. Blood samples were collected between days (d) 30 a.p. and d 30 p.p.. Whole blood neutrophil phagocytic activity, monocyte subset (classical cM, intermediate intM, non-classical ncM) composition and the proliferative capacity of lymphocytes were determined flow cytometrically. At d 14 a.p., all ewes were vaccinated against Mycobacterium avium subsp. paratuberculosis (MAP). Results Both groups showed a sharp increase in the total leukocyte counts (TLC) and neutrophil counts (P < 0.0001), at d 1 p.p., while, monocytes and their subpopulations displayed the highest values at d 30 p.p. (P ≤ 0.05). At d 1 p.p. the neutrophil phagocytic activity was higher (P < 0.05) in MAG ewes. Throughout the TP, the proliferative response of CD4+ cells was significantly higher in the MAG group (P < 0.05). Ewes in both groups responded with an increase in the TLC, neutrophil numbers (P ≤ 0.05) and ncM (P < 0.001) 24 h post vaccination, whereas monocytes and cM dropped in numbers (P ≤ 0.05). Numbers of intM only increased in MAG ewes (P < 0.05), whereas lymphocyte numbers decreased (P < 0.01). Mg supplementation did not affect the significant increase in MAP-specific antibodies at d 7 and 21 post vaccination. Total Mg and Ca serum levels did not show any differences between the two groups. Conclusion Whereas TP-associated fluctuations in blood leukocyte numbers are not influenced by Mg supplementation, neutrophil phagocytic activity, the proliferative capacity of CD4+ cells and the cellular response within 24 h after a vaccination are subject to modulation. Supplementary Information The online version contains supplementary material available at 10.1186/s12917-020-02705-9.
Collapse
Affiliation(s)
- Mona H Ahmed
- Institute of Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173, Hannover, Germany
| | - Mirja R Wilkens
- Institute of Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173, Hannover, Germany
| | - Bernd Möller
- Institute of Farm Animal Genetics, Friedrich-Loeffler-Institute (FLI), D-31535, Neustadt, Mecklenhorst, Germany
| | - Martin Ganter
- Clinic for Swine, Small Ruminants and Forensic Medicine, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173, Hannover, Germany
| | - Gerhard Breves
- Institute of Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, D-30173, Hannover, Germany
| | - Hans-Joachim Schuberth
- Institute of Immunology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 2, Building 261, D-30559, Hannover, Germany.
| |
Collapse
|
7
|
Grabert K, Sehgal A, Irvine KM, Wollscheid-Lengeling E, Ozdemir DD, Stables J, Luke GA, Ryan MD, Adamson A, Humphreys NE, Sandrock CJ, Rojo R, Verkasalo VA, Mueller W, Hohenstein P, Pettit AR, Pridans C, Hume DA. A Transgenic Line That Reports CSF1R Protein Expression Provides a Definitive Marker for the Mouse Mononuclear Phagocyte System. THE JOURNAL OF IMMUNOLOGY 2020; 205:3154-3166. [DOI: 10.4049/jimmunol.2000835] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/23/2020] [Indexed: 12/12/2022]
|
8
|
Obst J, Simon E, Martin-Estebane M, Pipi E, Barkwill LM, Gonzalez-Rivera I, Buchanan F, Prescott AR, Faust D, Fox S, Brownlees J, Taylor D, Perry VH, Nuthall H, Atkinson PJ, Karran E, Routledge C, Gomez-Nicola D. Inhibition of IL-34 Unveils Tissue-Selectivity and Is Sufficient to Reduce Microglial Proliferation in a Model of Chronic Neurodegeneration. Front Immunol 2020; 11:579000. [PMID: 33162994 PMCID: PMC7580706 DOI: 10.3389/fimmu.2020.579000] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/27/2020] [Indexed: 01/15/2023] Open
Abstract
The proliferation and activation of microglia, the resident macrophages in the brain, is a hallmark of many neurodegenerative diseases such as Alzheimer's disease (AD) and prion disease. Colony stimulating factor 1 receptor (CSF1R) is critically involved in regulating microglial proliferation, and CSF1R blocking strategies have been recently used to modulate microglia in neurodegenerative diseases. However, CSF1R is broadly expressed by many cell types and the impact of its inhibition on the innate immune system is still unclear. CSF1R can be activated by two independent ligands, CSF-1 and interleukin 34 (IL-34). Recently, it has been reported that microglia development and maintenance depend on IL-34 signaling. In this study, we evaluate the inhibition of IL-34 as a novel strategy to reduce microglial proliferation in the ME7 model of prion disease. Selective inhibition of IL-34 showed no effects on peripheral macrophage populations in healthy mice, avoiding the side effects observed after CSF1R inhibition on the systemic compartment. However, we observed a reduction in microglial proliferation after IL-34 inhibition in prion-diseased mice, indicating that microglia could be more specifically targeted by reducing IL-34. Overall, our results highlight the challenges of targeting the CSF1R/IL34 axis in the systemic and central compartments, important for framing any therapeutic effort to tackle microglia/macrophage numbers during brain disease.
Collapse
MESH Headings
- Animals
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal/toxicity
- Antibodies, Neutralizing/pharmacology
- Antibodies, Neutralizing/toxicity
- Brain/drug effects
- Brain/metabolism
- Brain/pathology
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Disease Models, Animal
- Genes, fms
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Interleukins/antagonists & inhibitors
- Interleukins/metabolism
- Mice, Inbred C57BL
- Mice, Transgenic
- Microglia/drug effects
- Microglia/metabolism
- Microglia/pathology
- Nerve Degeneration
- Prion Diseases/drug therapy
- Prion Diseases/metabolism
- Prion Diseases/pathology
- Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/antagonists & inhibitors
- Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/metabolism
- Signal Transduction
Collapse
Affiliation(s)
- Juliane Obst
- School of Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
| | - Emilie Simon
- School of Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
| | - Maria Martin-Estebane
- School of Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
| | - Elena Pipi
- School of Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
| | - Liana M. Barkwill
- School of Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
| | - Ivette Gonzalez-Rivera
- School of Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
| | - Fergus Buchanan
- Dundee Imaging Facility, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Alan R. Prescott
- Dundee Imaging Facility, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Dorte Faust
- Centre for Therapeutics Discovery, LifeArc, Accelerator Building, Stevenage, United Kingdom
| | - Simon Fox
- Centre for Therapeutics Discovery, LifeArc, Accelerator Building, Stevenage, United Kingdom
| | - Janet Brownlees
- Centre for Therapeutics Discovery, LifeArc, Accelerator Building, Stevenage, United Kingdom
| | - Debra Taylor
- Centre for Therapeutics Discovery, LifeArc, Accelerator Building, Stevenage, United Kingdom
| | - V. Hugh Perry
- School of Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
| | - Hugh Nuthall
- Eli Lilly Research Centre, Surrey, United Kingdom
| | - Peter J. Atkinson
- Eisai Limited, European Knowledge Centre, Hertfordshire, United Kingdom
| | - Eric Karran
- Abbvie, Foundational Neuroscience Centre, Cambridge, MA, United States
| | | | - Diego Gomez-Nicola
- School of Biological Sciences, Southampton General Hospital, University of Southampton, Southampton, United Kingdom
| |
Collapse
|
9
|
Irvine KM, Caruso M, Cestari MF, Davis GM, Keshvari S, Sehgal A, Pridans C, Hume DA. Analysis of the impact of CSF‐1 administration in adult rats using a novel
Csf1r
‐mApple reporter gene. J Leukoc Biol 2019; 107:221-235. [DOI: 10.1002/jlb.ma0519-149r] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 07/04/2019] [Accepted: 07/25/2019] [Indexed: 12/14/2022] Open
Affiliation(s)
| | - Melanie Caruso
- Mater Research The University of Queensland Brisbane Australia
| | | | - Gemma M. Davis
- Faculty of Life Sciences The University of Manchester Manchester United Kingdom
| | - Sahar Keshvari
- Mater Research The University of Queensland Brisbane Australia
| | - Anuj Sehgal
- Mater Research The University of Queensland Brisbane Australia
| | - Clare Pridans
- Centre for Inflammation Research The University of Edinburgh Edinburgh United Kingdom
| | - David A. Hume
- Mater Research The University of Queensland Brisbane Australia
- Centre for Inflammation Research The University of Edinburgh Edinburgh United Kingdom
| |
Collapse
|
10
|
Hume DA, Caruso M, Ferrari-Cestari M, Summers KM, Pridans C, Irvine KM. Phenotypic impacts of CSF1R deficiencies in humans and model organisms. J Leukoc Biol 2019; 107:205-219. [PMID: 31330095 DOI: 10.1002/jlb.mr0519-143r] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/20/2019] [Accepted: 07/01/2019] [Indexed: 12/12/2022] Open
Abstract
Mϕ proliferation, differentiation, and survival are controlled by signals from the Mϕ CSF receptor (CSF1R). Mono-allelic gain-of-function mutations in CSF1R in humans are associated with an autosomal-dominant leukodystrophy and bi-allelic loss-of-function mutations with recessive skeletal dysplasia, brain disorders, and developmental anomalies. Most of the phenotypes observed in these human disease states are also observed in mice and rats with loss-of-function mutations in Csf1r or in Csf1 encoding one of its two ligands. Studies in rodent models also highlight the importance of genetic background and likely epistatic interactions between Csf1r and other loci. The impacts of Csf1r mutations on the brain are usually attributed solely to direct impacts on microglial number and function. However, analysis of hypomorphic Csf1r mutants in mice and several other lines of evidence suggest that primary hydrocephalus and loss of the physiological functions of Mϕs in the periphery contribute to the development of brain pathology. In this review, we outline the evidence that CSF1R is expressed exclusively in mononuclear phagocytes and explore the mechanisms linking CSF1R mutations to pleiotropic impacts on postnatal growth and development.
Collapse
Affiliation(s)
- David A Hume
- Mater Research Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Melanie Caruso
- Mater Research Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | | | - Kim M Summers
- Mater Research Institute, University of Queensland, Woolloongabba, Queensland, Australia
| | - Clare Pridans
- Centre for Inflammation Research, The University of Edinburgh, Edinburgh, United Kingdom
| | - Katharine M Irvine
- Mater Research Institute, University of Queensland, Woolloongabba, Queensland, Australia
| |
Collapse
|
11
|
Hume DA, Irvine KM, Pridans C. The Mononuclear Phagocyte System: The Relationship between Monocytes and Macrophages. Trends Immunol 2019. [DOI: 10.1016/j.it.2018.11.007 order by 8029-- -] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
|
12
|
The Mononuclear Phagocyte System: The Relationship between Monocytes and Macrophages. Trends Immunol 2019. [DOI: 10.1016/j.it.2018.11.007 and 1880=1880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
|
13
|
Hume DA, Irvine KM, Pridans C. The Mononuclear Phagocyte System: The Relationship between Monocytes and Macrophages. Trends Immunol 2019. [DOI: 10.1016/j.it.2018.11.007 order by 1-- -] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
|
14
|
Hume DA, Irvine KM, Pridans C. The Mononuclear Phagocyte System: The Relationship between Monocytes and Macrophages. Trends Immunol 2019. [DOI: 10.1016/j.it.2018.11.007 order by 1-- #] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
|
15
|
Hume DA, Irvine KM, Pridans C. The Mononuclear Phagocyte System: The Relationship between Monocytes and Macrophages. Trends Immunol 2019. [DOI: 10.1016/j.it.2018.11.007 order by 8029-- awyx] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
|
16
|
The Mononuclear Phagocyte System: The Relationship between Monocytes and Macrophages. Trends Immunol 2019. [DOI: 10.1016/j.it.2018.11.007 order by 8029-- #] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
|
17
|
Hume DA, Irvine KM, Pridans C. The Mononuclear Phagocyte System: The Relationship between Monocytes and Macrophages. Trends Immunol 2019. [DOI: 10.1016/j.it.2018.11.007 order by 1-- gadu] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
|
18
|
Hume DA, Irvine KM, Pridans C. The Mononuclear Phagocyte System: The Relationship between Monocytes and Macrophages. Trends Immunol 2018; 40:98-112. [PMID: 30579704 DOI: 10.1016/j.it.2018.11.007] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2018] [Revised: 11/18/2018] [Accepted: 11/30/2018] [Indexed: 02/07/2023]
Abstract
The mononuclear phagocyte system (MPS) is defined as a cell lineage in which committed marrow progenitors give rise to blood monocytes and tissue macrophages. Here, we discuss the concept of self-proscribed macrophage territories and homeostatic regulation of tissue macrophage abundance through growth factor availability. Recent studies have questioned the validity of the MPS model and argued that tissue-resident macrophages are a separate lineage seeded during development and maintained by self-renewal. We address this issue; discuss the limitations of inbred mouse models of monocyte-macrophage homeostasis; and summarize the evidence suggesting that during postnatal life, monocytes can replace resident macrophages in all major organs and adopt their tissue-specific gene expression. We conclude that the MPS remains a valid and accurate framework for understanding macrophage development and homeostasis.
Collapse
Affiliation(s)
- David A Hume
- Mater Research Institute-University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, QLD 4102, Australia.
| | - Katharine M Irvine
- Mater Research Institute-University of Queensland, Translational Research Institute, 37 Kent Street, Woolloongabba, QLD 4102, Australia
| | - Clare Pridans
- University of Edinburgh Centre for Inflammation Research, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
| |
Collapse
|
19
|
Pridans C, Raper A, Davis GM, Alves J, Sauter KA, Lefevre L, Regan T, Meek S, Sutherland L, Thomson AJ, Clohisey S, Bush SJ, Rojo R, Lisowski ZM, Wallace R, Grabert K, Upton KR, Tsai YT, Brown D, Smith LB, Summers KM, Mabbott NA, Piccardo P, Cheeseman MT, Burdon T, Hume DA. Pleiotropic Impacts of Macrophage and Microglial Deficiency on Development in Rats with Targeted Mutation of the Csf1r Locus. THE JOURNAL OF IMMUNOLOGY 2018; 201:2683-2699. [PMID: 30249809 PMCID: PMC6196293 DOI: 10.4049/jimmunol.1701783] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 08/20/2018] [Indexed: 12/23/2022]
Abstract
We have produced Csf1r-deficient rats by homologous recombination in embryonic stem cells. Consistent with the role of Csf1r in macrophage differentiation, there was a loss of peripheral blood monocytes, microglia in the brain, epidermal Langerhans cells, splenic marginal zone macrophages, bone-associated macrophages and osteoclasts, and peritoneal macrophages. Macrophages of splenic red pulp, liver, lung, and gut were less affected. The pleiotropic impacts of the loss of macrophages on development of multiple organ systems in rats were distinct from those reported in mice. Csf1r-/- rats survived well into adulthood with postnatal growth retardation, distinct skeletal and bone marrow abnormalities, infertility, and loss of visceral adipose tissue. Gene expression analysis in spleen revealed selective loss of transcripts associated with the marginal zone and, in brain regions, the loss of known and candidate novel microglia-associated transcripts. Despite the complete absence of microglia, there was little overt phenotype in brain, aside from reduced myelination and increased expression of dopamine receptor-associated transcripts in striatum. The results highlight the redundant and nonredundant functions of CSF1R signaling and of macrophages in development, organogenesis, and homeostasis.
Collapse
Affiliation(s)
- Clare Pridans
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom; .,The University of Edinburgh Centre for Inflammation Research, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
| | - Anna Raper
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Gemma M Davis
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Joana Alves
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Kristin A Sauter
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Lucas Lefevre
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Tim Regan
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Stephen Meek
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Linda Sutherland
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Alison J Thomson
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom.,New World Laboratories, Laval, Quebec H7V 5B7, Canada
| | - Sara Clohisey
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Stephen J Bush
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom.,Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DU, United Kingdom
| | - Rocío Rojo
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Zofia M Lisowski
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Robert Wallace
- Department of Orthopaedic Surgery, The University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Kathleen Grabert
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Kyle R Upton
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom.,School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Yi Ting Tsai
- Medical Research Council Centre for Reproductive Health, The University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Deborah Brown
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Lee B Smith
- Medical Research Council Centre for Reproductive Health, The University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom.,Faculty of Science, University of Newcastle, Callaghan, New South Wales 2309, Australia; and
| | - Kim M Summers
- Mater Research-University of Queensland, Brisbane, Queensland 4101, Australia
| | - Neil A Mabbott
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Pedro Piccardo
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Michael T Cheeseman
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - Tom Burdon
- The Roslin Institute, The University of Edinburgh, Easter Bush EH25 9RG, United Kingdom
| | - David A Hume
- The University of Edinburgh Centre for Inflammation Research, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; .,Mater Research-University of Queensland, Brisbane, Queensland 4101, Australia
| |
Collapse
|
20
|
Dekker S, van Geemen D, van den Bogaerdt AJ, Driessen-Mol A, Aikawa E, Smits AIPM. Sheep-Specific Immunohistochemical Panel for the Evaluation of Regenerative and Inflammatory Processes in Tissue-Engineered Heart Valves. Front Cardiovasc Med 2018; 5:105. [PMID: 30159315 PMCID: PMC6104173 DOI: 10.3389/fcvm.2018.00105] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 07/13/2018] [Indexed: 12/27/2022] Open
Abstract
The creation of living heart valve replacements via tissue engineering is actively being pursued by many research groups. Numerous strategies have been described, aimed either at culturing autologous living valves in a bioreactor (in vitro) or inducing endogenous regeneration by the host via resorbable scaffolds (in situ). Whereas a lot of effort is being invested in the optimization of heart valve scaffold parameters and culturing conditions, the pathophysiological in vivo remodeling processes to which tissue-engineered heart valves are subjected upon implantation have been largely under-investigated. This is partly due to the unavailability of suitable immunohistochemical tools specific to sheep, which serves as the gold standard animal model in translational research on heart valve replacements. Therefore, the goal of this study was to comprise and validate a comprehensive sheep-specific panel of antibodies for the immunohistochemical analysis of tissue-engineered heart valve explants. For the selection of our panel we took inspiration from previous histopathological studies describing the morphology, extracellular matrix composition and cellular composition of native human heart valves throughout development and adult stages. Moreover, we included a range of immunological markers, which are particularly relevant to assess the host inflammatory response evoked by the implanted heart valve. The markers specifically identifying extracellular matrix components and cell phenotypes were tested on formalin-fixed paraffin-embedded sections of native sheep aortic valves. Markers for inflammation and apoptosis were tested on ovine spleen and kidney tissues. Taken together, this panel of antibodies could serve as a tool to study the spatiotemporal expression of proteins in remodeling tissue-engineered heart valves after implantation in a sheep model, thereby contributing to our understanding of the in vivo processes which ultimately determine long-term success or failure of tissue-engineered heart valves.
Collapse
Affiliation(s)
- Sylvia Dekker
- Soft Tissue Engineering & Mechanobiology Division, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
| | - Daphne van Geemen
- Soft Tissue Engineering & Mechanobiology Division, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
| | | | - Anita Driessen-Mol
- Soft Tissue Engineering & Mechanobiology Division, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Eindhoven, Netherlands
| | - Elena Aikawa
- Division of Cardiovascular Medicine, Department of Medicine, Center for Excellence in Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, United States
| | - Anthal I. P. M. Smits
- Soft Tissue Engineering & Mechanobiology Division, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Eindhoven, Netherlands
| |
Collapse
|
21
|
Hawley CA, Rojo R, Raper A, Sauter KA, Lisowski ZM, Grabert K, Bain CC, Davis GM, Louwe PA, Ostrowski MC, Hume DA, Pridans C, Jenkins SJ. Csf1r-mApple Transgene Expression and Ligand Binding In Vivo Reveal Dynamics of CSF1R Expression within the Mononuclear Phagocyte System. THE JOURNAL OF IMMUNOLOGY 2018; 200:2209-2223. [PMID: 29440354 PMCID: PMC5834790 DOI: 10.4049/jimmunol.1701488] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/17/2018] [Indexed: 01/18/2023]
Abstract
CSF1 is the primary growth factor controlling macrophage numbers, but whether expression of the CSF1 receptor differs between discrete populations of mononuclear phagocytes remains unclear. We have generated a Csf1r-mApple transgenic fluorescent reporter mouse that, in combination with lineage tracing, Alexa Fluor 647–labeled CSF1-Fc and CSF1, and a modified ΔCsf1–enhanced cyan fluorescent protein (ECFP) transgene that lacks a 150 bp segment of the distal promoter, we have used to dissect the differentiation and CSF1 responsiveness of mononuclear phagocyte populations in situ. Consistent with previous Csf1r-driven reporter lines, Csf1r-mApple was expressed in blood monocytes and at higher levels in tissue macrophages, and was readily detectable in whole mounts or with multiphoton microscopy. In the liver and peritoneal cavity, uptake of labeled CSF1 largely reflected transgene expression, with greater receptor activity in mature macrophages than monocytes and tissue-specific expression in conventional dendritic cells. However, CSF1 uptake also differed between subsets of monocytes and discrete populations of tissue macrophages, which in macrophages correlated with their level of dependence on CSF1 receptor signaling for survival rather than degree of transgene expression. A double ΔCsf1r-ECFP-Csf1r-mApple transgenic mouse distinguished subpopulations of microglia in the brain, and permitted imaging of interstitial macrophages distinct from alveolar macrophages, and pulmonary monocytes and conventional dendritic cells. The Csf1r-mApple mice and fluorescently labeled CSF1 will be valuable resources for the study of macrophage and CSF1 biology, which are compatible with existing EGFP-based reporter lines.
Collapse
Affiliation(s)
- Catherine A Hawley
- Medical Research Council Centre for Inflammation Research, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Rocio Rojo
- The Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, United Kingdom
| | - Anna Raper
- The Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, United Kingdom
| | - Kristin A Sauter
- The Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, United Kingdom
| | - Zofia M Lisowski
- The Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, United Kingdom
| | - Kathleen Grabert
- The Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, United Kingdom
| | - Calum C Bain
- Medical Research Council Centre for Inflammation Research, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Gemma M Davis
- The Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, United Kingdom.,Faculty of Life Sciences, The University of Manchester, Manchester M13 9PL, United Kingdom
| | - Pieter A Louwe
- Medical Research Council Centre for Inflammation Research, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom
| | - Michael C Ostrowski
- Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425; and
| | - David A Hume
- Medical Research Council Centre for Inflammation Research, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom.,The Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, United Kingdom.,Mater Research-University of Queensland, Translational Research Institute, Woolloongabba, Queensland 4104, Australia
| | - Clare Pridans
- Medical Research Council Centre for Inflammation Research, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom.,The Roslin Institute, University of Edinburgh, Midlothian EH25 9RG, United Kingdom
| | - Stephen J Jenkins
- Medical Research Council Centre for Inflammation Research, University of Edinburgh, Edinburgh EH16 4TJ, United Kingdom;
| |
Collapse
|
22
|
The evolution of the macrophage-specific enhancer (Fms intronic regulatory element) within the CSF1R locus of vertebrates. Sci Rep 2017; 7:17115. [PMID: 29215000 PMCID: PMC5719456 DOI: 10.1038/s41598-017-15999-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 11/03/2017] [Indexed: 01/07/2023] Open
Abstract
The Csf1r locus encodes the receptor for macrophage colony-stimulating factor, which controls the proliferation, differentiation and survival of macrophages. The 300 bp Fms intronic regulatory element (FIRE), within the second intron of Csf1r, is necessary and sufficient to direct macrophage-specific transcription. We have analysed the conservation and divergence of the FIRE DNA sequence in vertebrates. FIRE is present in the same location in the Csf1r locus in reptile, avian and mammalian genomes. Nearest neighbor analysis based upon this element alone largely recapitulates phylogenies inferred from much larger genomic sequence datasets. One core element, containing binding sites for AP1 family and the macrophage-specific transcription factor, PU.1, is conserved from lizards to humans. Around this element, the FIRE sequence is conserved within clades with the most conserved elements containing motifs for known myeloid-expressed transcription factors. Conversely, there is little alignment between clades outside the AP1/PU.1 element. The analysis favours a hybrid between “enhanceosome” and “smorgasbord” models of enhancer function, in which elements cooperate to bind components of the available transcription factor milieu.
Collapse
|