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Xia W, Zhu Z, Xiang S, Yang Y. Ginsenoside Rg5 promotes wound healing in diabetes by reducing the negative regulation of SLC7A11 on the efferocytosis of dendritic cells. J Ginseng Res 2023; 47:784-794. [PMID: 38107390 PMCID: PMC10721477 DOI: 10.1016/j.jgr.2023.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/31/2023] [Accepted: 06/19/2023] [Indexed: 12/19/2023] Open
Abstract
Background: ginsenoside Rg5 is a rare ginsenoside with known hypoglycemic effects in diabetic mice. This study aimed to explore the effects of ginsenoside Rg5 on skin wound-healing in the Leprdb/db mutant (db/db) mice (C57BL/KsJ background) model and the underlying mechanisms. Methods Seven-week-old male C57BL/6J, SLC7A11-knockout (KO), the littermate wild-type (WT), and db/db mice were used for in vivo and ex vivo studies. Results Ginsenoside Rg5 provided through oral gavage in db/db mice significantly alleviated the abundance of apoptotic cells in the wound areas and facilitated skin wound healing. 50 μM ginsenoside Rg5 treatment nearly doubled the efferocytotic capability of bone marrow-derived dendritic cells (BMDCs) from db/db mice. It also reduced NF-κB p65 and SLC7A11 expression in the wounded areas of db/db mice dose-dependently. Ginsenoside Rg5 physically interacted with SLC7A11 and suppressed the cystine uptake and glutamate secretion of BMDCs from db/db and SLC7A11-WT mice but not in BMDCs from SLC7A11-KO mice. In BMDCs and conventional type 1 dendritic cells (cDC1s), ginsenoside Rg5 reduced their glycose storage and enhanced anaerobic glycolysis. Glycogen phosphorylase inhibitor CP-91149 almost abolished the effect of ginsenoside Rg5 on promoting efferocytosis. Conclusion: ginsenoside Rg5 can suppress the expression of SLC7A11 and inhibit its activity via physical binding. These effects collectively alleviate the negative regulations of SLC7A11 on anaerobic glycolysis, which fuels the efferocytosis of dendritic cells. Therefore, ginsenoside Rg5 has a potential adjuvant therapeutic reagent to support patients with wound-healing problems, such as diabetic foot ulcers.
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Affiliation(s)
- Wei Xia
- Department of Endocrinology, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Zongdong Zhu
- Department of Orthopedics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Song Xiang
- Department of Endocrinology, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Yi Yang
- Department of Endocrinology, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
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2
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Pinos I, Yu J, Pilli N, Kane MA, Amengual J. Functional characterization of interleukin 4 and retinoic acid signaling crosstalk during alternative macrophage activation. Biochim Biophys Acta Mol Cell Biol Lipids 2023; 1868:159291. [PMID: 36754230 PMCID: PMC9974901 DOI: 10.1016/j.bbalip.2023.159291] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/25/2023] [Accepted: 01/28/2023] [Indexed: 02/09/2023]
Abstract
Retinoic acid possesses potent immunomodulatory properties in various cell types, including macrophages. In this study, we first investigated the effects at the transcriptional and functional levels of exogenous retinoic acid in murine bone marrow-derived macrophages (BMDMs) in the presence or absence of interleukin 4 (IL4), a cytokine with potent anti-inflammatory properties. We examined the effect of IL4 on vitamin A homeostasis in macrophages by quantifying retinoid synthesis and secretion. Our RNAseq data show that exogenous retinoic acid synergizes with IL4 to regulate anti-inflammatory pathways such as oxidative phosphorylation and phagocytosis. Efferocytosis and lysosomal degradation assays validated gene expression changes at the functional level. IL4 treatment altered the expression of several genes involved in vitamin A transport and conversion to retinoic acid. Radiolabeling experiments and mass spectrometry assays revealed that IL4 stimulates retinoic acid production and secretion in a signal transducer and activator of transcription 6 (STAT6)-dependent manner. In summary, our studies highlight the key role of exogenous and endogenous retinoic acid in shaping the anti-inflammatory response of macrophages.
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Affiliation(s)
- Ivan Pinos
- Division of Nutritional Sciences, University of Illinois Urbana Champaign, Urbana, IL, United States
| | - Jianshi Yu
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
| | - Nageswara Pilli
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
| | - Maureen A Kane
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
| | - Jaume Amengual
- Division of Nutritional Sciences, University of Illinois Urbana Champaign, Urbana, IL, United States; Department of Food Science and Human Nutrition, University of Illinois Urbana Champaign, Urbana, IL, United States.
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3
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Taefehshokr N, Heit B. Methods for Quantitative Efferocytosis Assays. Methods Mol Biol 2023; 2692:41-59. [PMID: 37365460 DOI: 10.1007/978-1-0716-3338-0_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Efferocytosis, the phagocytic removal of apoptotic cells, is a dynamic process requiring recruitment of numerous regulatory proteins to mediate the uptake, engulfment, and degradation of apoptotic cells. Herein, we describe microscopy-based methods for the enumeration of efferocytic events and characterization of the spatiotemporal dynamics of signaling molecule recruitment during efferocytosis using genetically encoded probes and immunofluorescent labeling. While these methods are illustrated using macrophages, they are applicable to any efferocytic cell type.
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Affiliation(s)
- Nima Taefehshokr
- Department of Microbiology and Immunology, and The Western Infection, Immunity and Inflammation Centre, The University of Western Ontario, London, ON, Canada
| | - Bryan Heit
- Department of Microbiology and Immunology, and The Western Infection, Immunity and Inflammation Centre, The University of Western Ontario, London, ON, Canada.
- Robarts Research Institute, London, ON, Canada.
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4
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Mogilenko DA, Danko K, Larionova EE, Shavva VS, Kudriavtsev IV, Nekrasova EV, Burnusuz AV, Gorbunov NP, Trofimov AV, Zhakhov AV, Ivanov IA, Orlov SV. Differentiation of human macrophages with anaphylatoxin C3a impairs alternative M2 polarization and decreases lipopolysaccharide‐induced cytokine secretion. Immunol Cell Biol 2022; 100:186-204. [DOI: 10.1111/imcb.12534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 01/06/2022] [Accepted: 02/07/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Denis A Mogilenko
- Department of Biochemistry Institute of Experimental Medicine St. Petersburg Russia
- Department of Embryology St. Petersburg State University St. Petersburg Russia
| | - Katerina Danko
- Department of Biochemistry Institute of Experimental Medicine St. Petersburg Russia
- Department of Cytology and Histology St. Petersburg State University St. Petersburg Russia
| | | | - Vladimir S Shavva
- Department of Biochemistry Institute of Experimental Medicine St. Petersburg Russia
| | - Igor V Kudriavtsev
- Department of Cytology and Histology St. Petersburg State University St. Petersburg Russia
- Department of Immunology Institute of Experimental Medicine St. Petersburg Russia
| | | | - Alexandra V Burnusuz
- Department of Biochemistry Institute of Experimental Medicine St. Petersburg Russia
- Department of Cytology and Histology St. Petersburg State University St. Petersburg Russia
- Department of Immunology Institute of Experimental Medicine St. Petersburg Russia
| | - Nikolay P Gorbunov
- The Research Institute of Highly Pure Biopreparations St. Petersburg Russia
| | | | | | | | - Sergey V Orlov
- Department of Biochemistry Institute of Experimental Medicine St. Petersburg Russia
- Department of Embryology St. Petersburg State University St. Petersburg Russia
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5
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Meriwether D, Jones AE, Ashby JW, Solorzano-Vargas RS, Dorreh N, Noori S, Grijalva V, Ball AB, Semis M, Divakaruni AS, Mack JJ, Herschman HR, Martin MG, Fogelman AM, Reddy ST. Macrophage COX2 Mediates Efferocytosis, Resolution Reprogramming, and Intestinal Epithelial Repair. Cell Mol Gastroenterol Hepatol 2022; 13:1095-1120. [PMID: 35017061 PMCID: PMC8873959 DOI: 10.1016/j.jcmgh.2022.01.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 12/30/2021] [Accepted: 01/03/2022] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIMS Phagocytosis (efferocytosis) of apoptotic neutrophils by macrophages anchors the resolution of intestinal inflammation. Efferocytosis prevents secondary necrosis and inhibits further inflammation, and also reprograms macrophages to facilitate tissue repair and promote resolution function. Macrophage efferocytosis and efferocytosis-dependent reprogramming are implicated in the pathogenesis of inflammatory bowel disease. We previously reported that absence of macrophage cyclooxygenase 2 (COX2) exacerbates inflammatory bowel disease-like intestinal inflammation. To elucidate the underlying pathogenic mechanism, we investigated here whether COX2 mediates macrophage efferocytosis and efferocytosis-dependent reprogramming, including intestinal epithelial repair capacity. METHODS Using apoptotic neutrophils and synthetic apoptotic targets, we determined the effects of macrophage specific Cox2 knockout and pharmacological COX2 inhibition on the efferocytosis capacity of mouse primary macrophages. COX2-mediated efferocytosis-dependent eicosanoid lipidomics was determined by liquid chromatography tandem mass spectrometry. Small intestinal epithelial organoids were employed to assay the effects of COX2 on efferocytosis-dependent intestinal epithelial repair. RESULTS Loss of COX2 impaired efferocytosis in mouse primary macrophages, in part, by affecting the binding capacity of macrophages for apoptotic cells. This effect was comparable to that of high-dose lipopolysaccharide and was accompanied by both dysregulation of macrophage polarization and the inhibited expression of genes involved in apoptotic cell binding. COX2 modulated the production of efferocytosis-dependent lipid inflammatory mediators that include the eicosanoids prostaglandin I2, prostaglandin E2, lipoxin A4, and 15d-PGJ2; and further affected secondary efferocytosis. Finally, macrophage efferocytosis induced, in a macrophage COX2-dependent manner, a tissue restitution and repair phenotype in intestinal epithelial organoids. CONCLUSIONS Macrophage COX2 potentiates efferocytosis capacity and efferocytosis-dependent reprogramming, facilitating macrophage intestinal epithelial repair capacity.
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Affiliation(s)
- David Meriwether
- Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California,Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California,Correspondence Address correspondence to: David Meriwether, PhD, Department of Medicine, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, University of California Los Angeles, 10833 Le Conte Avenue, Los Angeles, CA 90095-5347. fax: 310-206-3605.
| | - Anthony E. Jones
- Department of Medical and Molecular Pharmacology, University of California, Los Angeles, Los Angeles, California
| | - Julianne W. Ashby
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - R. Sergio Solorzano-Vargas
- Division of Gastroenterology, Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Nasrin Dorreh
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Shoreh Noori
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Victor Grijalva
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Andréa B. Ball
- Department of Medical and Molecular Pharmacology, University of California, Los Angeles, Los Angeles, California
| | - Margarita Semis
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Ajit S. Divakaruni
- Department of Medical and Molecular Pharmacology, University of California, Los Angeles, Los Angeles, California
| | - Julia J. Mack
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Harvey R. Herschman
- Department of Medical and Molecular Pharmacology, University of California, Los Angeles, Los Angeles, California
| | - Martin G. Martin
- Division of Gastroenterology, Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Alan M. Fogelman
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Srinivasa T. Reddy
- Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California,Department of Medical and Molecular Pharmacology, University of California, Los Angeles, Los Angeles, California,Srinivasa T. Reddy, PhD, Department of Medicine, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Room 43-144 CHS, Los Angeles, CA 90095-1679. fax: 310-206-3605.
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6
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Rajamohan A, Heit B, Cairns E, Barra L. Citrullinated and homocitrullinated low- density lipoprotein in rheumatoid arthritis. Scand J Rheumatol 2021; 50:343-350. [PMID: 33678128 DOI: 10.1080/03009742.2020.1867237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Objective: Antibodies to citrullinated and homocitrullinated (also known as carbamylated) proteins, specific for rheumatoid arthritis (RA), are associated with cardiovascular disease (CVD). Immune complexes containing these proteins have been identified in the atherosclerotic plaque of CVD patients. In mice, homocitrullinated low-density lipoprotein (HomoCitLDL) promotes foam cell formation, which is critical in the pathogenesis of atherosclerosis. We aimed to investigate the atherogenic potential of HomoCitLDL and citrullinated low-density lipoprotein (CitLDL) in RA.Method: Human LDL was homocitrullinated in potassium cyanate and citrullinated by rabbit skeletal muscle peptidyl arginine deiminase-2. The modifications were confirmed by mass spectrometry. Primary human monoctyes from healthy subjects (N = 8) were differentiated to macrophages using macrophage colony-stimulating factor and incubated with modified LDL. Foam cells were visualized using Oil Red O staining. Serum from RA patients (N = 101) and controls (N = 32) was tested for immunoglobulin G antibodies to modified LDL using enzyme-linked immunosorbent assay.Results: HomoCitLDL and CitLDL strongly induced foam cell production (> 90%) versus unmodified LDL (11%) (p < 0.0001). The characteristics of the RA subjects were: 73% females, median age 60 [interquartile range (IQR) 17] years and disease duration 7.5 (IQR 13) years; 11% had a prior major cardiovascular event, 66% were ever smokers, 32% had hypertension, 33% dyslipidaemia, and 14% diabetes. Antibodies to HomoCitLDL were detected in 18% of RA patients; they were significantly associated with dyslipidaemia [odds ratio (OR) 3.86; 95% confidence interval (CI) 1.22, 12.17] and antibodies to other homocitrullinated antigens (OR 10.61; 95% CI 1.31, 86.11).Conclusions: HomoCitLDL and CitLDL have atherogenic properties in vitro. Antibody responses to HomoCitLDL, but not CitLDL, were detected in RA patients.
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Affiliation(s)
- A Rajamohan
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON, Canada
| | - B Heit
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON, Canada.,Robarts Research Institute, London, ON, Canada
| | - E Cairns
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON, Canada.,Division of Rheumatology, Department of Medicine, The University of Western Ontario, London, ON, Canada
| | - L Barra
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON, Canada.,Division of Rheumatology, Department of Medicine, The University of Western Ontario, London, ON, Canada
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7
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Yin C, Vrieze AM, Rosoga M, Akingbasote J, Pawlak EN, Jacob RA, Hu J, Sharma N, Dikeakos JD, Barra L, Nagpal AD, Heit B. Efferocytic Defects in Early Atherosclerosis Are Driven by GATA2 Overexpression in Macrophages. Front Immunol 2020; 11:594136. [PMID: 33193444 PMCID: PMC7644460 DOI: 10.3389/fimmu.2020.594136] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 10/01/2020] [Indexed: 01/01/2023] Open
Abstract
The loss of efferocytosis-the phagocytic clearance of apoptotic cells-is an initiating event in atherosclerotic plaque formation. While the loss of macrophage efferocytosis is a prerequisite for advanced plaque formation, the transcriptional and cellular events in the pre-lesion site that drive these defects are poorly defined. Transcriptomic analysis of macrophages recovered from early-stage human atherosclerotic lesions identified a 50-fold increase in the expression of GATA2, a transcription factor whose expression is normally restricted to the hematopoietic compartment. GATA2 overexpression in vitro recapitulated many of the functional defects reported in patient macrophages, including deficits at multiple stages in the efferocytic process. These findings included defects in the uptake of apoptotic cells, efferosome maturation, and in phagolysosome function. These efferocytic defects were a product of GATA2-driven alterations in the expression of key regulatory proteins, including Src-family kinases, Rab7 and components of both the vacuolar ATPase and NADPH oxidase complexes. In summary, these data identify a mechanism by which efferocytic capacity is lost in the early stages of plaque formation, thus setting the stage for the accumulation of uncleared apoptotic cells that comprise the bulk of atherosclerotic plaques.
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Affiliation(s)
- Charles Yin
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - Angela M Vrieze
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - Mara Rosoga
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - James Akingbasote
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - Emily N Pawlak
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - Rajesh Abraham Jacob
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - Jonathan Hu
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - Neha Sharma
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada
| | - Lillian Barra
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada.,Division of Rheumatology, Department of Medicine, The University of Western Ontario, London, ON, Canada
| | - A Dave Nagpal
- Division of Cardiac Surgery, Department of Surgery, The University of Western Ontario, London, ON, Canada.,Division of Critical Care Medicine, Department of Medicine, The University of Western Ontario, London, ON, Canada
| | - Bryan Heit
- Department of Microbiology and Immunology, and The Center for Human Immunology, The University of Western Ontario, London, ON, Canada.,Robarts Research Institute, London, ON, Canada
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8
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Blackburn JWD, Lau DHC, Liu EY, Ellins J, Vrieze AM, Pawlak EN, Dikeakos JD, Heit B. Soluble CD93 is an apoptotic cell opsonin recognized by α x β 2. Eur J Immunol 2019; 49:600-610. [PMID: 30656676 DOI: 10.1002/eji.201847801] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 12/13/2018] [Accepted: 01/16/2019] [Indexed: 11/11/2022]
Abstract
Efferocytosis is essential for homeostasis and prevention of the inflammatory and autoimmune diseases resulting from apoptotic cell lysis. CD93 is a transmembrane glycoprotein previously implicated in efferocytosis, with mutations in CD93 predisposing patients to efferocytosis-associated diseases. CD93 is a cell surface protein, which is proteolytically shed under inflammatory conditions, but it is unknown how CD93 mediates efferocytosis or whether its efferocytic activity is mediated by the soluble or membrane-bound form. Herein, using cell lines and human monocytes and macrophages, we demonstrate that soluble CD93 (sCD93) potently opsonizes apoptotic cells but not a broad range of microorganisms, whereas membrane-bound CD93 has no phagocytic, efferocytic, or tethering activity. Using mass spectrometry, we identified αx β2 as the receptor that recognizes sCD93, and via deletion mutagenesis determined that sCD93 binds to apoptotic cells via its C-type lectin-like domain and to αx β2 by its EGF-like repeats. The bridging of apoptotic cells to αx β2 markedly enhanced efferocytosis by macrophages and was abrogated by αx β2 knockdown. Combined, these data elucidate the mechanism by which CD93 regulates efferocytosis and identifies a previously unreported opsonin-receptor system utilized by phagocytes for the efferocytic clearance of apoptotic cells.
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Affiliation(s)
- Jack W D Blackburn
- Department of Microbiology and Immunology, Center for Human Immunology, The University of Western Ontario, London, Ontario, Canada
| | - Darius H C Lau
- Department of Microbiology and Immunology, Center for Human Immunology, The University of Western Ontario, London, Ontario, Canada
| | - Elaine Y Liu
- Department of Microbiology and Immunology, Center for Human Immunology, The University of Western Ontario, London, Ontario, Canada
| | - Jessica Ellins
- Department of Microbiology and Immunology, Center for Human Immunology, The University of Western Ontario, London, Ontario, Canada
| | - Angela M Vrieze
- Department of Microbiology and Immunology, Center for Human Immunology, The University of Western Ontario, London, Ontario, Canada
| | - Emily N Pawlak
- Department of Microbiology and Immunology, Center for Human Immunology, The University of Western Ontario, London, Ontario, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology, Center for Human Immunology, The University of Western Ontario, London, Ontario, Canada
| | - Bryan Heit
- Department of Microbiology and Immunology, Center for Human Immunology, The University of Western Ontario, London, Ontario, Canada
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9
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Taruc K, Yin C, Wootton DG, Heit B. Quantification of Efferocytosis by Single-cell Fluorescence Microscopy. J Vis Exp 2018. [PMID: 30176011 DOI: 10.3791/58149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Studying the regulation of efferocytosis requires methods that are able to accurately quantify the uptake of apoptotic cells and to probe the signaling and cellular processes that control efferocytosis. This quantification can be difficult to perform as apoptotic cells are often efferocytosed piecemeal, thus necessitating methods which can accurately delineate between the efferocytosed portion of an apoptotic target versus residual unengulfed cellular fragments. The approach outlined herein utilizes dual-labeling approaches to accurately quantify the dynamics of efferocytosis and efferocytic capacity of efferocytes such as macrophages. The cytosol of the apoptotic cell is labeled with a cell-tracking dye to enable monitoring of all apoptotic cell-derived materials, while surface biotinylation of the apoptotic cell allows for differentiation between internalized and non-internalized apoptotic cell fractions. The efferocytic capacity of efferocytes is determined by taking fluorescent images of live or fixed cells and quantifying the amount of bound versus internalized targets, as differentiated by streptavidin staining. This approach offers several advantages over methods such as flow cytometry, namely the accurate delineation of non-efferocytosed versus efferocytosed apoptotic cell fractions, the ability to measure efferocytic dynamics by live-cell microscopy, and the capacity to perform studies of cellular signaling in cells expressing fluorescently-labeled transgenes. Combined, the methods outlined in this protocol serve as the basis for a flexible experimental approach that can be used to accurately quantify efferocytic activity and interrogate cellular signaling pathways active during efferocytosis.
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Affiliation(s)
- Kyle Taruc
- Department of Microbiology and Immunology and the Center for Human Immunology, University of Western Ontario
| | - Charles Yin
- Department of Microbiology and Immunology and the Center for Human Immunology, University of Western Ontario
| | - Daniel G Wootton
- Institute of Infection and Global Health, University of Liverpool; Department of Respiratory Research, Aintree University Hospital NHS Foundation Trust
| | - Bryan Heit
- Department of Microbiology and Immunology and the Center for Human Immunology, University of Western Ontario;
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10
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Evans AL, Blackburn JWD, Taruc K, Kipp A, Dirk BS, Hunt NR, Barr SD, Dikeakos JD, Heit B. Antagonistic Coevolution of MER Tyrosine Kinase Expression and Function. Mol Biol Evol 2017; 34:1613-1628. [PMID: 28369510 DOI: 10.1093/molbev/msx102] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
TYRO3, AXL, and MERTK (TAM) receptors are a family of receptor tyrosine kinases that maintain homeostasis through the clearance of apoptotic cells, and when defective, contribute to chronic inflammatory and autoimmune diseases such as atherosclerosis, multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and Crohn's disease. In addition, certain enveloped viruses utilize TAM receptors for immune evasion and entry into host cells, with several viruses preferentially hijacking MERTK for these purposes. Despite the biological importance of TAM receptors, little is understood of their recent evolution and its impact on their function. Using evolutionary analysis of primate TAM receptor sequences, we identified strong, recent positive selection in MERTK's signal peptide and transmembrane domain that was absent from TYRO3 and AXL. Reconstruction of hominid and primate ancestral MERTK sequences revealed three nonsynonymous single nucleotide polymorphisms in the human MERTK signal peptide, with a G14C mutation resulting in a predicted non-B DNA cruciform motif, producing a significant decrease in MERTK expression with no significant effect on MERTK trafficking or half-life. Reconstruction of MERTK's transmembrane domain identified three amino acid substitutions and four amino acid insertions in humans, which led to significantly higher levels of self-clustering through the creation of a new interaction motif. This clustering counteracted the effect of the signal peptide mutations through enhancing MERTK avidity, whereas the lower MERTK expression led to reduced binding of Ebola virus-like particles. The decreased MERTK expression counterbalanced by increased avidity is consistent with antagonistic coevolution to evade viral hijacking of MERTK.
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Affiliation(s)
- Amanda L Evans
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Jack W D Blackburn
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Kyle Taruc
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Angela Kipp
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Brennan S Dirk
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Nina R Hunt
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Stephen D Barr
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
| | - Bryan Heit
- Department of Microbiology and Immunology and the Centre for Human Immunology, The University of Western Ontario, London, Canada
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11
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Yin C, Argintaru D, Heit B. Rab17 mediates intermixing of phagocytosed apoptotic cells with recycling endosomes. Small GTPases 2017; 10:218-226. [PMID: 28471261 DOI: 10.1080/21541248.2017.1308852] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Efferocytosis-the phagocytic removal of apoptotic cells-is required for preventing the presentation of apoptotic cell-derived antigens. This process is regulated by Rab17-dependent sorting of efferocytosed cargos from the phagolysosome to recycling endosomes. In this study we demonstrate that Rab17 is rapidly recruited to efferosomes, followed by migration of the efferosome to the cell center where it intermixes with lysosomes and undergoes Rab17-dependent vesiculation. These efferosome-derived vesicles then traffic in a Rab17-dependent manner to the cell periphery, where they transfer cargo to recycling endosomes. Combined, our observations support a model wherein efferosomes migrate to the cell center to acquire degradative enzymes, followed by peripheral migration to prevent further phagolysosome maturation and to enable cargo transfer to recycling endosomes.
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Affiliation(s)
- Charles Yin
- a Department of Microbiology and Immunology and the Centre for Human Immunology , The University of Western Ontario , London , Ontario , Canada
| | - Dean Argintaru
- a Department of Microbiology and Immunology and the Centre for Human Immunology , The University of Western Ontario , London , Ontario , Canada
| | - Bryan Heit
- a Department of Microbiology and Immunology and the Centre for Human Immunology , The University of Western Ontario , London , Ontario , Canada
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