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Ackermann J, Arndt L, Fröba J, Lindhorst A, Glaß M, Kirstein M, Hobusch C, Wunderlich FT, Braune J, Gericke M. IL-6 signaling drives self-renewal and alternative activation of adipose tissue macrophages. Front Immunol 2024; 15:1201439. [PMID: 38482013 PMCID: PMC10933059 DOI: 10.3389/fimmu.2024.1201439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 02/13/2024] [Indexed: 03/20/2024] Open
Abstract
Introduction Obesity is associated with chronic low-grade inflammation of adipose tissue (AT) and an increase of AT macrophages (ATMs) that is linked to the onset of type 2 diabetes. We have recently shown that neutralization of interleukin (IL)-6 in obese AT organ cultures inhibits proliferation of ATMs, which occurs preferentially in alternatively activated macrophage phenotype. Methods In this study, we investigated AT biology and the metabolic phenotype of mice with myeloid cell-specific IL-6Rα deficiency (Il6ra Δmyel) after normal chow and 20 weeks of high-fat diet focusing on AT inflammation, ATM polarization and proliferation. Using organotypical AT culture and bone marrow derived macrophages (BMDMs) of IL-4Rα knockout mice (Il4ra -/-) we studied IL-6 signaling. Results Obese Il6ra Δmyel mice exhibited no differences in insulin sensitivity or histological markers of AT inflammation. Notably, we found a reduction of ATMs expressing the mannose receptor 1 (CD206), as well as a decrease of the proliferation marker Ki67 in ATMs of Il6ra Δmyel mice. Importantly, organotypical AT culture and BMDM data of Il4ra -/- mice revealed that IL-6 mediates a shift towards the M2 phenotype independent from the IL-6/IL-4Rα axis. Discussion Our results demonstrate IL-4Rα-independent anti-inflammatory effects of IL-6 on macrophages and the ability of IL-6 to maintain proliferation rates in obese AT.
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Affiliation(s)
- Jan Ackermann
- Institute of Anatomy, Leipzig University, Leipzig, Germany
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Lilli Arndt
- Institute of Anatomy, Leipzig University, Leipzig, Germany
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Janine Fröba
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | | | - Markus Glaß
- Institute of Molecular Medicine, Martin Luther University Halle-Wittenberg, Charles Tanford Protein Center, Halle (Saale), Germany
| | - Michaela Kirstein
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | | | - F Thomas Wunderlich
- Max-Planck-Institute for Metabolism Research, Research Group for Obesity and Cancer, Cologne, Germany
| | - Julia Braune
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Martin Gericke
- Institute of Anatomy, Leipzig University, Leipzig, Germany
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
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2
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Ackermann J, Arndt L, Kirstein M, Hobusch C, Brinker G, Klöting N, Braune J, Gericke M. Myeloid Cell-Specific IL-4 Receptor Knockout Partially Protects from Adipose Tissue Inflammation. J Immunol 2021; 207:3081-3089. [PMID: 34789558 DOI: 10.4049/jimmunol.2100699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/18/2021] [Indexed: 11/19/2022]
Abstract
IL-4 receptor signaling is supposed to play a major role in anti-inflammatory polarization and proliferation of adipose tissue macrophages. In this study, we examined the metabolic and inflammatory phenotype of C57BL/6J mice (IIl4ra) with LysM-dependent knockout (IIl4ra Δmyel) of the IL-4 receptor α-chain (IL-4Rα), the mandatory signaling component of IL-4 and IL-13, on chow and high-fat diet. Lean IIl4ra Δmyel mice showed decreased insulin sensitivity, no divergent adipose tissue macrophage polarization, but an increased percentage of CD8+ T cells in visceral adipose tissue. After 20 wk of a high-fat diet, IIl4ra Δmyel mice exhibited higher glucose tolerance, no changes in the lymphocyte compartment and fewer M1 macrophages in visceral adipose tissue. In vivo adipose tissue macrophage proliferation measured by BrdU incorporation was unaffected by Il4ra knockout. Interestingly, we show that IL-4Rα signaling directly augmented Itgax (Cd11c) gene expression in bone marrow-derived macrophages and increased the amount of CD11c+ macrophages in adipose tissue explants. Myeloid cell-specific knockout of Il4ra deteriorated insulin sensitivity in lean mice but improved parameters of glucose homeostasis and partially protected from adipose tissue inflammation in obese mice. Hence, IL-4Rα signaling probably plays a minor role in maintaining the macrophage M2 population and proliferation rates in vivo. Moreover, our data indicate that IL-4 signaling plays a proinflammatory role in adipose tissue inflammation by directly upregulating CD11c on adipose tissue macrophages.
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Affiliation(s)
- Jan Ackermann
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany.,Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Lilli Arndt
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Michaela Kirstein
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | | | - Georg Brinker
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany.,Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Nora Klöting
- Helmholtz Institute for Metabolic, Obesity and Vascular Research of the Helmholtz Zentrum München at the University of Leipzig; and.,Medical Department III, Leipzig University, Leipzig, Germany
| | - Julia Braune
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany.,Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Martin Gericke
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany; .,Institute of Anatomy, Leipzig University, Leipzig, Germany
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3
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Brinker G, Froeba J, Arndt L, Braune J, Hobusch C, Lindhorst A, Bechmann I, Gericke M. CD4 + T cells regulate glucose homeostasis independent of adipose tissue dysfunction in mice. Eur J Immunol 2021; 51:1399-1411. [PMID: 33784418 DOI: 10.1002/eji.202048870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 02/10/2021] [Accepted: 03/16/2021] [Indexed: 11/11/2022]
Abstract
Obesity is frequently associated with a chronic low-grade inflammation in the adipose tissue (AT) and impaired glucose homeostasis. Adipose tissue macrophages (ATMs) have been shown to accumulate in the inflamed AT either by means of recruitment from the blood or local proliferation. ATM proliferation and activation can be stimulated by TH2 cytokines, such as IL-4 and IL-13, suggesting involvement of CD4-positive T cells in ATM proliferation and activation. Furthermore, several studies have associated T cells to alterations in glucose metabolism. Therefore, we sought to examine a direct impact of CD4-positive T cells on ATM activation, ATM proliferation and glucose homeostasis using an in vivo depletion model. Surprisingly, CD4 depletion did not affect ATM activation, ATM proliferation, or insulin sensitivity. However, CD4 depletion led to a significant improvement of glucose tolerance. In line with this, we found moderate disturbances in pancreatic endocrine function following CD4 depletion. Hence, our data suggest that the effect on glucose metabolism observed after CD4 depletion might be mediated by organs other than AT and independent of AT inflammation.
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Affiliation(s)
- Georg Brinker
- Institute of Anatomy, Leipzig University, Leipzig, D-04103, Germany
| | - Janine Froeba
- Institute of Anatomy, Leipzig University, Leipzig, D-04103, Germany.,Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), D-06108, Germany
| | - Lilli Arndt
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), D-06108, Germany
| | - Julia Braune
- Institute of Anatomy, Leipzig University, Leipzig, D-04103, Germany.,Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), D-06108, Germany
| | | | - Andreas Lindhorst
- Institute of Anatomy, Leipzig University, Leipzig, D-04103, Germany.,Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), D-06108, Germany
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Leipzig, D-04103, Germany
| | - Martin Gericke
- Institute of Anatomy, Leipzig University, Leipzig, D-04103, Germany.,Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), D-06108, Germany
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4
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Braune J, Lindhorst A, Fröba J, Hobusch C, Kovacs P, Blüher M, Eilers J, Bechmann I, Gericke M. Multinucleated Giant Cells in Adipose Tissue Are Specialized in Adipocyte Degradation. Diabetes 2021; 70:538-548. [PMID: 33158932 DOI: 10.2337/db20-0293] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 10/30/2020] [Indexed: 11/13/2022]
Abstract
Obesity is associated with chronic low-grade inflammation of visceral adipose tissue (AT) characterized by an increasing number of AT macrophages (ATMs) and linked to type 2 diabetes. AT inflammation is histologically indicated by the formation of so-called crown-like structures, as ATMs accumulate around dying adipocytes, and the occurrence of multinucleated giant cells (MGCs). However, to date, the function of MGCs in obesity is unknown. Therefore, the aim of this study was to characterize MGCs in AT and unravel the function of these cells. We demonstrated that MGCs occurred in obese patients and after 24 weeks of a high-fat diet in mice, accompanying signs of AT inflammation and then representing ∼3% of ATMs in mice. Mechanistically, we found evidence that adipocyte death triggered MGC formation. Most importantly, MGCs in obese AT had a higher capacity to phagocytize oversized particles, such as adipocytes, as shown by live imaging of AT, 45-µm bead uptake ex vivo, and higher lipid content in vivo. Finally, we showed that interleukin-4 treatment was sufficient to increase the number of MGCs in AT, whereas other factors may be more important for endogenous MGC formation in vivo. Most importantly, our data suggest that MGCs are specialized for clearance of dead adipocytes in obesity.
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Affiliation(s)
- Julia Braune
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Andreas Lindhorst
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Janine Fröba
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | | | - Peter Kovacs
- Medical Department III, Leipzig University, Leipzig, Germany
| | - Matthias Blüher
- Medical Department III, Leipzig University, Leipzig, Germany
| | - Jens Eilers
- Carl-Ludwig Institute of Physiology, Leipzig University, Leipzig, Germany
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Leipzig, Germany
| | - Martin Gericke
- Institute of Anatomy and Cell Biology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
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5
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Graf-Riesen K, Kimura K, Unger A, Lother A, Hein L, Daerr J, Braune J, Ooms A, Li G, Wu SM, Höhfeld J, Linke WA, Fürst D, Fleischmann BK, Hesse M. Abstract 466: Myopathy Causing Bag3
P209L
Protein Leads to Restrictive Cardiomyopathy Caused by Aggregate Formation and Sarcomere Disruption in Cardiomyocytes. Circ Res 2019. [DOI: 10.1161/res.125.suppl_1.466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The co-chaperone BAG3 (Bcl-2 associated athanogene 3) is strongly expressed in cross-striated muscles and plays a key role in the turnover of muscle-proteins as a member of the CASA (chaperone-assisted selected autophagy) complex. An amino acid exchange (P209L) in the human BAG3 gene, caused by a single base mutation, gives rise to a severe dominant childhood muscular dystrophy, restrictive cardiomyopathy, and respiratory insufficiency. To get deeper insights into the pathophysiological mechanisms of the disease, we generated a transgenic mouse model of the human mutation BAG3
P209L
, in which a fusion protein consisting of the human BAG3
P209L
and the green fluorescent protein eGFP can be conditionally overexpressed. Ubiquitous overexpression of BAG3
P209L
-eGFP leads to a severe phenotype between the second and fourth week of life, including decreased body weight, skeletal muscle weakness, and heart failure. Echocardiography revealed that the BAG3
P209L
-mice suffer from restrictive cardiomyopathy and Sirius-red-staining of heart tissue showed extensive fibrosis. In cardiomyocytes, isolated from hearts of transgenic mice overexpressing BAG3
wt
-eGFP or BAG3
P209L
-eGFP, BAG3
wt
-eGFP stringently localizes to sarcomeres and intercalated discs, whereas cardiomyocytes from BAG3
P209L
-eGFP mice displayed formation of BAG3 containing aggregates and disruption of sarcomeres in
vivo
. While BAG3
P209L
-eGFP binding to á-Hsp70, Filamin C and á-HspB8 was unchanged it was less soluble than BAG3 and had a tendency to aggregate, thereby sequestering BAG3 and its clients. Depletion of the BAG3 pool leads to an impairment of CASA and accumulation of damaged proteins, causing sarcomere disintegration leading to restrictive cardiomyopathy.
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Affiliation(s)
| | | | | | - Achim Lother
- Institute of Experimental and Clinical Pharmacology and Toxicology, Freiburg, Germany
| | - Lutz Hein
- Institute of Experimental and Clinical Pharmacology and Toxicology, Freiburg, Germany
| | - Jan Daerr
- Institute of Cell Biology, Bonn, Germany
| | | | | | - Guang Li
- Stanford Cardiovascular Institute, Stanford, Germany
| | - Sean M. Wu
- Stanford Cardiovascular Institute, Stanford, Germany
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6
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Dierck F, Kuhn C, Rohr C, Hille S, Braune J, Sossalla S, Molt S, van der Ven PFM, Fürst DO, Frey N. The novel cardiac z-disc protein CEFIP regulates cardiomyocyte hypertrophy by modulating calcineurin signaling. J Biol Chem 2017; 292:15180-15191. [PMID: 28717008 DOI: 10.1074/jbc.m117.786764] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 07/04/2017] [Indexed: 11/06/2022] Open
Abstract
The z-disc is a structural component at the lateral borders of the sarcomere and is important for mechanical stability and contractility of both cardiac and skeletal muscles. Of note, the sarcomeric z-disc also represents a nodal point in cardiomyocyte function and signaling. Mutations of numerous z-disc proteins are associated with cardiomyopathies and muscle diseases. To identify additional z-disc proteins that might contribute to cardiac disease, we employed an in silico screen for cardiac-enriched cDNAs. This screen yielded a previously uncharacterized protein named cardiac-enriched FHL2-interacting protein (CEFIP), which exhibited a heart- and skeletal muscle-specific expression profile. Importantly, CEFIP was located at the z-disc and was up-regulated in several models of cardiomyopathy. We also found that CEFIP overexpression induced the fetal gene program and cardiomyocyte hypertrophy. Yeast two-hybrid screens revealed that CEFIP interacts with the calcineurin-binding protein four and a half LIM domains 2 (FHL2). Because FHL2 binds calcineurin, a phosphatase controlling hypertrophic signaling, we examined the effects of CEFIP on the calcineurin/nuclear factor of activated T-cell (NFAT) pathway. These experiments revealed that CEFIP overexpression further enhances calcineurin-dependent hypertrophic signal transduction, and its knockdown repressed hypertrophy and calcineurin/NFAT activity. In summary, we report on a previously uncharacterized protein CEFIP that modulates calcineurin/NFAT signaling in cardiomyocytes, a finding with possible implications for the pathogenesis of cardiomyopathy.
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Affiliation(s)
- Franziska Dierck
- From the Department of Internal Medicine III, University Medical Center of Schleswig-Holstein, 24105 Kiel.,the DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 24105 Kiel
| | - Christian Kuhn
- From the Department of Internal Medicine III, University Medical Center of Schleswig-Holstein, 24105 Kiel.,the DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 24105 Kiel
| | - Claudia Rohr
- the Department of Internal Medicine III, University of Heidelberg, 69120 Heidelberg, and
| | - Susanne Hille
- From the Department of Internal Medicine III, University Medical Center of Schleswig-Holstein, 24105 Kiel.,the DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 24105 Kiel
| | - Julia Braune
- the Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Samuel Sossalla
- From the Department of Internal Medicine III, University Medical Center of Schleswig-Holstein, 24105 Kiel.,the DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 24105 Kiel
| | - Sibylle Molt
- the Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Peter F M van der Ven
- the Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Dieter O Fürst
- the Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Norbert Frey
- From the Department of Internal Medicine III, University Medical Center of Schleswig-Holstein, 24105 Kiel, .,the DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, 24105 Kiel
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7
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Braune J, Weyer U, Matz-Soja M, Hobusch C, Kern M, Kunath A, Klöting N, Kralisch S, Blüher M, Gebhardt R, Zavros Y, Bechmann I, Gericke M. Hedgehog signalling in myeloid cells impacts on body weight, adipose tissue inflammation and glucose metabolism. Diabetologia 2017; 60:889-899. [PMID: 28233033 DOI: 10.1007/s00125-017-4223-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 01/23/2017] [Indexed: 12/21/2022]
Abstract
AIMS/HYPOTHESIS Recently, hedgehog (Hh) was identified as a crucial player in adipose tissue development and energy expenditure. Therefore, we tested whether Hh ligands are regulated in obesity. Further, we aimed at identifying potential target cells of Hh signalling and studied the functional impact of Hh signalling on adipose tissue inflammation and glucose metabolism. METHODS Hh ligands and receptors were analysed in adipose tissue or serum from lean and obese mice as well as in humans. To study the impact on adipose tissue inflammation and glucose metabolism, Hh signalling was specifically blocked in myeloid cells using a conditional knockout approach (Lys-Smo -/-). RESULTS Desert Hh (DHH) and Indian Hh (IHH) are local Hh ligands, whereas Sonic Hh is not expressed in adipose tissue from mice or humans. In mice, obesity leads to a preferential upregulation of Hh ligands (Dhh) and signalling components (Ptch1, Smo and Gli1) in subcutaneous adipose tissue. Further, adipose tissue macrophages are Hh target cells owing to the expression of Hh receptors, such as Patched1 and 2. Conditional knockout of Smo (which encodes Smoothened, a mandatory Hh signalling component) in myeloid cells increases body weight and adipose tissue inflammation and attenuates glucose tolerance, suggesting an anti-inflammatory effect of Hh signalling. In humans, adipose tissue expression of DHH and serum IHH decrease with obesity and type 2 diabetes, which might be explained by the intake of metformin. Interestingly, metformin reduced Dhh and Ihh expression in mouse adipose tissue explants. CONCLUSIONS/INTERPRETATION Hh signalling in myeloid cells affects adipose tissue inflammation and glucose metabolism and may be a potential target to treat type 2 diabetes.
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Affiliation(s)
- Julia Braune
- Institute of Anatomy, Leipzig University, Oststrasse 25, D-04317, Leipzig, Germany
| | - Ulrike Weyer
- Institute of Anatomy, Leipzig University, Oststrasse 25, D-04317, Leipzig, Germany
| | - Madlen Matz-Soja
- Institute of Biochemistry, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Constance Hobusch
- Institute of Anatomy, Leipzig University, Oststrasse 25, D-04317, Leipzig, Germany
| | - Matthias Kern
- German Center of Diabetes Research (DZD), Leipzig, Germany
| | - Anne Kunath
- IFB Adiposity Disease, Core Unit, Leipzig University, Leipzig, Germany
| | - Nora Klöting
- IFB Adiposity Disease, Core Unit, Leipzig University, Leipzig, Germany
| | - Susann Kralisch
- Department of Medicine, Leipzig University, Leipzig, Germany
| | - Matthias Blüher
- Department of Medicine, Leipzig University, Leipzig, Germany
| | - Rolf Gebhardt
- Institute of Biochemistry, Faculty of Medicine, Leipzig University, Leipzig, Germany
| | - Yana Zavros
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, USA
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Oststrasse 25, D-04317, Leipzig, Germany
| | - Martin Gericke
- Institute of Anatomy, Leipzig University, Oststrasse 25, D-04317, Leipzig, Germany.
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8
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Braune J, Weyer U, Hobusch C, Mauer J, Brüning JC, Bechmann I, Gericke M. IL-6 Regulates M2 Polarization and Local Proliferation of Adipose Tissue Macrophages in Obesity. J Immunol 2017; 198:2927-2934. [PMID: 28193830 DOI: 10.4049/jimmunol.1600476] [Citation(s) in RCA: 160] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 01/20/2017] [Indexed: 12/12/2022]
Abstract
Obesity is associated with chronic low-grade inflammation of adipose tissue (AT) and an increase of AT macrophages (ATMs) that is linked to the onset of type 2 diabetes. We have recently shown that focal sites of inflammation around dying adipocytes, so-called crown-like structures, exhibit a unique microenvironment for macrophage proliferation. Interestingly, locally proliferating macrophages were not classically activated (M1), but they exhibited a rather alternatively activated (M2) immune phenotype. In this study, we established organotypic cell cultures of AT explants to study the impact of cytokine treatment on local ATM proliferation, without the bias of early monocyte recruitment. We show that exposure of AT to Th2 cytokines, such as IL-4, IL-13, and GM-CSF, stimulates ATM proliferation, whereas Th1 cytokines, such as TNF-α, inhibit local ATM proliferation. Furthermore, AT from obese mice exhibits an increased sensitivity to IL-4 stimulation, indicated by an increased phosphorylation of STAT6. In line with this, gene expression of the IL-4 receptor (Il4ra) and its ligand IL-13 are elevated in AT of obese C57BL/6 mice. Most importantly, Il4ra expression and susceptibility to IL-4 or IL-13 treatment depend on IL-6 signaling, which seems to be the underlying mechanism of local ATM proliferation in obesity. We conclude that IL-6 acts as a Th2 cytokine in obesity by stimulating M2 polarization and local ATM proliferation, presumably due to upregulation of the IL-4 receptor α.
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Affiliation(s)
- Julia Braune
- Institute of Anatomy, Leipzig University, 04317 Leipzig, Germany
| | - Ulrike Weyer
- Institute of Anatomy, Leipzig University, 04317 Leipzig, Germany
| | | | - Jan Mauer
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY 10065; and
| | - Jens C Brüning
- Max Planck Institute for Metabolism Research, 50931 Cologne, Germany
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, 04317 Leipzig, Germany
| | - Martin Gericke
- Institute of Anatomy, Leipzig University, 04317 Leipzig, Germany;
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9
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Gericke M, Weyer U, Braune J, Bechmann I, Eilers J. A method for long-term live imaging of tissue macrophages in adipose tissue explants. Am J Physiol Endocrinol Metab 2015; 308:E1023-33. [PMID: 25874903 DOI: 10.1152/ajpendo.00075.2015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 04/14/2015] [Indexed: 11/22/2022]
Abstract
Obesity is frequently associated with a chronic low-grade inflammation within adipose tissue (AT). Although classical signs of inflammation are missing in AT inflammation, there is a significant increase in macrophages and, to a lesser extent, other immune cells, such as T cells, B cells, mast cells, and neutrophils. The spatial and temporal activation of these cells as well as their accumulation in the AT seem to be tightly linked to so-called crown-like structures (CLS). CLS are accumulations of adipose tissue macrophages (ATMs) around dead adipocytes and are thought to reflect a scavenger response. At present, data on the life cycle of CLS are missing. To better understand the cellular events underlying AT inflammation, we developed an approach that allows long-term imaging of ATMs, adipocytes, and CLS within live AT explants. We tested three putative reporter mouse lines for myeloid cells in regard to their suitability for live imaging. Thereby, we identified ATMs from CSF1R-eGFP mice to exhibit the most robust expression of eGFP. AT explants from these mice allowed stable live imaging for more than 7 days without significant phototoxicity. Long-term imaging thus revealed the accumulation of ATMs around dying adipocytes, migration of ATMs within AT, and also the degradation of the lipid remnants of perishing adipocytes. The observed behavior of ATMs in the context of AT inflammation is in line with previous studies but for the first time provides data on the specific behavior of individual ATMs and on the life cycle of CLS with unprecedented spatiotemporal resolution.
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Affiliation(s)
- Martin Gericke
- Institute of Anatomy, Leipzig University, Leipzig, Germany; and
| | - Ulrike Weyer
- Institute of Anatomy, Leipzig University, Leipzig, Germany; and
| | - Julia Braune
- Institute of Anatomy, Leipzig University, Leipzig, Germany; and
| | - Ingo Bechmann
- Institute of Anatomy, Leipzig University, Leipzig, Germany; and
| | - Jens Eilers
- Carl-Ludwig Institute of Physiology, Leipzig University, Leipzig, Germany
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10
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Abstract
In addition to the direct impact of a farm safety day camp on its participants' knowledge and safety awareness, there are extended and indirect effects that occur through the wider dispersion of information and the involvement and cooperation of community members. Reports completed by 228 coordinators of farm safety day camps, report forms completed by 5,037 volunteers at farm safety day camps, and telephone interviews with 924 parents of farm safety day camp participants were analyzed for evidence of the impact of the camps beyond the immediate knowledge gained by the children who participated. These data indicate that the indirect benefits to a community include enhanced safety awareness within the wider community as children and adult volunteers disseminate the information they learned, as well as enhanced community strength and cohesiveness resulting from the cooperation of many individuals and organizations in achieving a common goal.
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Affiliation(s)
- D M McCallum
- Institute for Social Science Research, 391-A Nott Hall, The University of Alabama, Tuscaloosa, AL 35487, USA.
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11
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McCallum DM, Conaway MB, Drury S, Braune J, Reynolds SJ. Safety-Related Knowledge and Behavior Changes in Participants of Farm Safety Day Camps. J Agric Saf Health 2005; 11:35-50. [PMID: 15782887 DOI: 10.13031/2013.17895] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Significant resources are devoted to conducting farm safety day camps throughout North America, but the impact and effectiveness of these programs has not been systematically demonstrated. This project assessed changes in safety-related knowledge and behaviors among participants in the Progressive Farmer Farm Safety Day Camp program. A written pre-test and a three-month telephone post-test were administered to three samples of participants, ages 8 to 13, in camps held in 1999, 2000, and 2001. A sample of 20 to 30 camps was included in each year of the study, with a total sample of 1,780 participants for all three years. The pre-test and post-test contained questions related to first aid and to safety around animals, ATVs, farm equipment, flowing grains, and tractors. Three scores were computed from responses to 20 knowledge and behavior items. A knowledge score indicated the number of 8 knowledge items answered correctly, a behavior risk score indicated the amount of risk exposure for the child based on 8 behavior items, and an ATV safety gear risk score indicated, for those who rode ATVs, the level of risk due to lack of proper safety gear (4 items). From pre-test to post-test, there was an increase in knowledge scores and a decrease in behavior risk scores and ATV safety gear risk scores. These changes were consistent both for males and females, for farm residents and non-farm residents, and across all ages in the sample. These results support claims for the effectiveness of farm safety day camps for increasing knowledge and improving safe practices among camp participants.
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Affiliation(s)
- D M McCallum
- Institute for Social Science Research, University of Alabama, Tuscaloosa, Alabama 35487-0216, USA.
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Diederich T, Döppner T, Braune J, Tiggesbäumker J, Meiwes-Broer KH. Electron delocalization in magnesium clusters grown in supercold helium droplets. Phys Rev Lett 2001; 86:4807-4810. [PMID: 11384353 DOI: 10.1103/physrevlett.86.4807] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2000] [Indexed: 05/23/2023]
Abstract
The formation of bare clusters from highly reactive metals can be achieved very effectively by the pickup of atoms into superfluid helium droplets. We report on the experimental observation of electronic shells in small magnesium clusters produced by this method. Mass spectra taken under various ionization conditions show steps and outstanding peaks, as well as pronounced minima. The abundance distribution suggests a transition to full electron delocalization which is complete at about 20 atoms. A so-far-not-reported electron reorganization is observed, leading to a novel shell structure.
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Affiliation(s)
- T Diederich
- Fachbereich Physik, Universität Rostock, 18051 Rostock, Germany
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Abstract
OBJECTIVE To compare the venodilator potencies of the phosphodiesterase (PDE) III inhibitors amrinone and enoximone with the unspecific PDE inhibitors theophylline and pentoxifylline in human hand veins in vivo. METHODS Eighteen healthy nonsmokers (16 men and two women) were studied using the dorsal hand vein technique. After preconstriction with the selective alpha1-adrenergic-receptor agonist phenylephrine dose-response curves were constructed for amrinone (1-270 microg x min(-1)), enoximone (1-270 microg x min(-1)), theophylline (5-1500 microg x min(-1)) and pentoxifylline (2-877 microg x min(-1)) in a random order on separate occasions. Due to limitation in the maximum dose infused in order to avoid systemic effects, full dose-response curves could not be constructed for pentoxifylline. In this case, the individual dose of pentoxifylline and theophylline producing 50% venodilation were compared. RESULTS All PDE inhibitors induced dose-dependent venodilation. The value of maximum venodilation was the same for amrinone, enoximone and theophylline. The infusion rate needed to induce 50% of maximum venodilation (ED50) was not significantly different for amrinone (geometric mean, 8.8 microg x min(-1)) and enoximone (14.2 microg x min(-1)), whereas the ED50 of theophylline (84.0 microg x min(-1)) was significantly higher than either amrinone or enoximone. The dose necessary to dilate the vein to 50% the maximum dilation (as determined during sodium chloride infusion) was significantly higher for pentoxifylline than for theophylline (409 vs 71 microg x min(-1)). CONCLUSIONS These findings demonstrate that enoximone and amrinone have similar venodilatory potency which is six times higher than that of theophylline. The least potent vasodilator in this study was pentoxifylline.
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Affiliation(s)
- M Grossmann
- Institute of Clinical Pharmacology, Faculty of Medicine, Technical University, Dresden, Germany.
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