Modulation of cardiac macrophages by phosphatidylserine-presenting liposomes improves infarct repair
01 Feb 2011-Proceedings of the National Academy of Sciences of the United States of America (National Academy of Sciences)-Vol. 108, Iss: 5, pp 1827-1832
TL;DR: A new strategy for the modulation of cardiac macrophages to a reparative state, at a predetermined time after myocardial infarction (MI), in aim to promote resolution of inflammation and elicit infarct repair is investigated.
Abstract: Herein we investigated a new strategy for the modulation of cardiac macrophages to a reparative state, at a predetermined time after myocardial infarction (MI), in aim to promote resolution of inflammation and elicit infarct repair. The strategy employed intravenous injections of phosphatidylserine (PS)-presenting liposomes, mimicking the anti-inflammatory effects of apoptotic cells. Following PS-liposome uptake by macrophages in vitro and in vivo, the cells secreted high levels of anti-inflammatory cytokines [transforming growth factor β (TGFβ) and interleukin 10 (IL-10)] and upregulated the expression of the mannose receptor—CD206, concomitant with downregulation of proinflammatory markers, such as tumor necrosis factor α (TNFα) and the surface marker CD86. In a rat model of acute MI, targeting of PS-presenting liposomes to infarct macrophages after injection via the femoral vein was demonstrated by magnetic resonance imaging (MRI). The treatment promoted angiogenesis, the preservation of small scars, and prevented ventricular dilatation and remodeling. This strategy represents a unique and accessible approach for myocardial infarct repair.
Citations
More filters
TL;DR: This review discusses the mechanisms that instruct macrophages to adopt pro-inflammatory, pro-wound-healing,pro-fibrotic, anti- inflammatory, anti -fib rotic, Pro-resolving, and tissue-regenerating phenotypes after injury, and highlights how some of these mechanisms and macrophage activation states could be exploited therapeutically.
2,284 citations
Cites background from "Modulation of cardiac macrophages b..."
...Finally, by mimicking the anti-inflammatory effects of apoptotic cells, phosphatidlyserine-presenting liposomes have also been used to induce reparative IL-10and TGFb1-producing cardiac macrophages (Harel-Adar et al., 2011)....
[...]
TL;DR: The current understanding of the complex process of apoptotic cell clearance in physiology and pathology is reviewed, and how this knowledge could be harnessed for new therapeutic strategies are discussed.
Abstract: Prompt removal of apoptotic cells by phagocytes is important for maintaining tissue homeostasis. The molecular and cellular events that underpin apoptotic cell recognition and uptake, and the subsequent biological responses are increasingly better defined. The detection and disposal of apoptotic cells generally promote an anti-inflammatory response at the tissue level, as well as immunological tolerance. Consequently, defects in apoptotic cell clearance have been linked with a variety of inflammatory diseases and autoimmunity. Conversely, under certain conditions such as killing tumour cells by specific cell death inducers, the recognition of apoptotic tumour cells can promote an immunogenic response and anti-tumour immunity. Here, we review the current understanding of the complex process of apoptotic cell clearance in physiology and pathology, and discuss how this knowledge could be harnessed for new therapeutic strategies.
909 citations
TL;DR: The restorative macrophage phenotype was recapitulated in vitro by the phagocytosis of cellular debris with associated activation of the ERK signaling cascade, offering a therapeutic strategy to this orphan pathological process.
Abstract: Although macrophages are widely recognized to have a profibrotic role in inflammation, we have used a highly tractable CCl4-induced model of reversible hepatic fibrosis to identify and characterize the macrophage phenotype responsible for tissue remodeling: the hitherto elusive restorative macrophage. This CD11Bhi F4/80int Ly-6Clo macrophage subset was most abundant in livers during maximal fibrosis resolution and represented the principle matrix metalloproteinase (MMP) -expressing subset. Depletion of this population in CD11B promoter–diphtheria toxin receptor (CD11B-DTR) transgenic mice caused a failure of scar remodeling. Adoptive transfer and in situ labeling experiments showed that these restorative macrophages derive from recruited Ly-6Chi monocytes, a common origin with profibrotic Ly-6Chi macrophages, indicative of a phenotypic switch in vivo conferring proresolution properties. Microarray profiling of the Ly-6Clo subset, compared with Ly-6Chi macrophages, showed a phenotype outside the M1/M2 classification, with increased expression of MMPs, growth factors, and phagocytosis-related genes, including Mmp9, Mmp12, insulin-like growth factor 1 (Igf1), and Glycoprotein (transmembrane) nmb (Gpnmb). Confocal microscopy confirmed the postphagocytic nature of restorative macrophages. Furthermore, the restorative macrophage phenotype was recapitulated in vitro by the phagocytosis of cellular debris with associated activation of the ERK signaling cascade. Critically, induced phagocytic behavior in vivo, through administration of liposomes, increased restorative macrophage number and accelerated fibrosis resolution, offering a therapeutic strategy to this orphan pathological process.
744 citations
Cites background from "Modulation of cardiac macrophages b..."
...Furthermore, recent studies have shown that liposome administration can alter macrophage phenotype in vivo in part by induction of ERK signaling after ingestion (53, 54)....
[...]
TL;DR: This review integrates the key molecular and cellular mechanisms of resolution and describes how abrogation of chemokine signalling blocks continued neutrophil tissue infiltration and how apoptotic neutrophils attract monocytes and macrophages to induce their clearance.
Abstract: Resolution of inflammation is a coordinated and active process aimed at restoration of tissue integrity and function. This review integrates the key molecular and cellular mechanisms of resolution. We describe how abrogation of chemokine signalling blocks continued neutrophil tissue infiltration and how apoptotic neutrophils attract monocytes and macrophages to induce their clearance. Uptake of apoptotic neutrophils by macrophages reprograms macrophages towards a resolving phenotype, a key event to restore tissue homeostasis. Finally, we highlight the therapeutic potential that derives from understanding the mechanisms of resolution.
590 citations
Cites background from "Modulation of cardiac macrophages b..."
...…infarction in rats PS/PC liposomes Induction of angiogenesis, preservation of small scars, prevention of ventricular dilatation and remodelling Harel-Adar et al (2011) Retinal ischaemia in mice PS/PC liposomes Reduced expression of pro-inflammatory genes, reduced neuronal death in the retina…...
[...]
TL;DR: The data indicate that Treg cells beneficially influence wound healing after MI by modulating monocyte/macrophage differentiation, and therapeutic activation of TReg cells constitutes a novel approach to improve healing post-MI.
Abstract: Rationale:An exaggerated or persistent inflammatory activation after myocardial infarction (MI) leads to maladaptive healing and subsequent remodeling of the left ventricle. Foxp3+ CD4+ regulatory T cells (Treg cells) contribute to inflammation resolution. Therefore, Treg cells might influence cardiac healing post-MI. Objective:Our aim was to study the functional role of Treg cells in wound healing post-MI in a mouse model of permanent left coronary artery ligation. Methods and Results:Using a model of genetic Treg-cell ablation (Foxp3DTR mice), we depleted the Treg-cell compartment before MI induction, resulting in aggravated cardiac inflammation and deteriorated clinical outcome. Mechanistically, Treg-cell depletion was associated with M1-like macrophage polarization, characterized by decreased expression of inflammation-resolving and healing-promoting factors. The phenotype of exacerbated cardiac inflammation and outcome in Treg-cell–ablated mice could be confirmed in a mouse model of anti-CD25 monoclo...
492 citations
Cites background from "Modulation of cardiac macrophages b..."
...Consistently, experimental modulation of macrophage polarization toward an M2 state has been previously demonstrated to improve wound healing post-MI.(46) Figure 8....
[...]
References
More filters
TL;DR: The evidence in favour of alternative macrophage activation by the TH2-type cytokines interleukin-4 (IL-4) and IL-13 is assessed, and its limits and relevance to a range of immune and inflammatory conditions are defined.
Abstract: The classical pathway of interferon-gamma-dependent activation of macrophages by T helper 1 (T(H)1)-type responses is a well-established feature of cellular immunity to infection with intracellular pathogens, such as Mycobacterium tuberculosis and HIV. The concept of an alternative pathway of macrophage activation by the T(H)2-type cytokines interleukin-4 (IL-4) and IL-13 has gained credence in the past decade, to account for a distinctive macrophage phenotype that is consistent with a different role in humoral immunity and repair. In this review, I assess the evidence in favour of alternative macrophage activation in the light of macrophage heterogeneity, and define its limits and relevance to a range of immune and inflammatory conditions.
5,930 citations
"Modulation of cardiac macrophages b..." refers background in this paper
...The anti-inflammatory macrophage phenotype after uptake of PS-presenting liposomes mimicked that of activated macrophages after the uptake of apoptotic cells (14, 15)....
[...]
Journal Article•
TL;DR: The data suggest that macrophages specifically recognize phosphatidylserine that is exposed on the surface of lymphocytes during the development of apoptosis, and suggest that apoptotic lymphocytes lose membrane phospholipid asymmetry and expose phosphorus on the outer leaflet of the plasma membrane.
Abstract: During normal tissue remodeling, macrophages remove unwanted cells, including those that have undergone programmed cell death, or apoptosis. This widespread process extends to the deletion of thymocytes (negative selection), in which cells expressing inappropriate Ag receptors undergo apoptosis, and are phagocytosed by thymic macrophages. Although phagocytosis of effete leukocytes by macrophages has been known since the time of Metchnikoff, only recently has it been recognized that apoptosis leads to surface changes that allow recognition and removal of these cells before they are lysed. Our data suggest that macrophages specifically recognize phosphatidylserine that is exposed on the surface of lymphocytes during the development of apoptosis. Macrophage phagocytosis of apoptotic lymphocytes was inhibited, in a dose-dependent manner, by liposomes containing phosphatidyl-L-serine, but not by liposomes containing other anionic phospholipids, including phosphatidyl-D-serine. Phagocytosis of apoptotic lymphocytes was also inhibited by the L isoforms of compounds structurally related to phosphatidylserine, including glycerophosphorylserine and phosphoserine. The membranes of apoptotic lymphocytes bound increased amounts of merocyanine 540 dye relative to those of normal cells, indicating that their membrane lipids were more loosely packed, consistent with a loss of membrane phospholipid asymmetry. Apoptotic lymphocytes were shown to express phosphatidylserine (PS) externally, because PS on their surfaces was accessible to derivatization by fluorescamine, and because apoptotic cells expressed procoagulant activity. These observations suggest that apoptotic lymphocytes lose membrane phospholipid asymmetry and expose phosphatidylserine on the outer leaflet of the plasma membrane. Macrophages then phagocytose apoptotic lymphocytes after specific recognition of the exposed PS.
3,344 citations
TL;DR: This review summarizes the current understanding of the cellular and molecular mechanisms regulating the inflammatory response following myocardial ischemia and reperfusion and concludes that by promoting more effective tissue repair, it may be possible to reduce the deleterious remodeling.
Abstract: One of the major therapeutic goals of modern cardiology is to design strategies aimed at minimizing myocardial necrosis and optimizing cardiac repair following myocardial infarction. However, a sound understanding of the biology is necessary before a specific intervention is pursued on a therapeutic basis. This review summarizes our current understanding of the cellular and molecular mechanisms regulating the inflammatory response following myocardial ischemia and reperfusion. Myocardial necrosis induces complement activation and free radical generation, triggering a cytokine cascade initiated by Tumor Necrosis Factor (TNF)-α release. If reperfusion of the infarcted area is initiated, it is attended by an intense inflammatory reaction. Interleukin (IL)-8 synthesis and C5a activation have a crucial role in recruiting neutrophils in the ischemic and reperfused myocardium. Neutrophil infiltration is regulated through a complex sequence of molecular steps involving the selectins and the integrins, which mediate leukocyte rolling and adhesion to the endothelium. Marginated neutrophils exert potent cytotoxic effects through the release of proteolytic enzymes and the adhesion with Intercellular Adhesion Molecule (ICAM)-1 expressing cardiomyocytes. Despite this potential injury, substantial evidence suggests that reperfusion enhances cardiac repair improving patient survival; this effect may be in part related to the inflammatory response. Monocyte Chemoattractant Protein (MCP)-1 is also markedly upregulated in the infarcted myocardium inducing recruitment of mononuclear cells in the injured areas. Monocyte-derived macrophages and mast cells may produce cytokines and growth factors necessary for fibroblast proliferation and neovascularization, leading to effective repair and scar formation. At this stage expression of inhibitory cytokines such as IL-10 may have a role in suppressing the acute inflammatory response and in regulating extracellular matrix metabolism. Fibroblasts in the healing scar undergo phenotypic changes expressing smooth muscle cell markers. Our previous review in this journal focused almost exclusively on reduction of the inflammatory injury. The current update is prompted by the potential therapeutic opportunity that the open vessel offers. By promoting more effective tissue repair, it may be possible to reduce the deleterious remodeling, that is the leading cause of heart failure and death. Elucidating the complex interactions and regulatory mechanisms responsible for cardiac repair may allow us to design effective inflammation-related interventions for the treatment of myocardial infarction.
1,966 citations
"Modulation of cardiac macrophages b..." refers background in this paper
...Following MI, resident and recruited macrophages remove necrotic and apoptotic cells, secrete cytokines, and modulate angiogenesis at the infarct site (1)....
[...]
TL;DR: This work identifies two distinct phases of monocyte participation after MI and proposes a model that reconciles the divergent properties of these cells in healing and identifies new therapeutic targets that can influence healing and ventricular remodeling after MI.
Abstract: Healing of myocardial infarction (MI) requires monocytes/macrophages These mononuclear phagocytes likely degrade released macromolecules and aid in scavenging of dead cardiomyocytes, while mediating aspects of granulation tissue formation and remodeling The mechanisms that orchestrate such divergent functions remain unknown In view of the heightened appreciation of the heterogeneity of circulating monocytes, we investigated whether distinct monocyte subsets contribute in specific ways to myocardial ischemic injury in mouse MI We identify two distinct phases of monocyte participation after MI and propose a model that reconciles the divergent properties of these cells in healing Infarcted hearts modulate their chemokine expression profile over time, and they sequentially and actively recruit Ly-6Chi and -6Clo monocytes via CCR2 and CX3CR1, respectively Ly-6Chi monocytes dominate early (phase I) and exhibit phagocytic, proteolytic, and inflammatory functions Ly-6Clo monocytes dominate later (phase II), have attenuated inflammatory properties, and express vascular–endothelial growth factor Consequently, Ly-6Chi monocytes digest damaged tissue, whereas Ly-6Clo monocytes promote healing via myofibroblast accumulation, angiogenesis, and deposition of collagen MI in atherosclerotic mice with chronic Ly-6Chi monocytosis results in impaired healing, underscoring the need for a balanced and coordinated response These observations provide novel mechanistic insights into the cellular and molecular events that regulate the response to ischemic injury and identify new therapeutic targets that can influence healing and ventricular remodeling after MI
1,895 citations
"Modulation of cardiac macrophages b..." refers background in this paper
...According to recent studies, different subsets of macrophages are responsible for these different activities; during the early inflammatory phase (phase 1), proinflammatory macrophages dominate the injury site and phagocytose apoptotic/necrotic myocytes and other debris, whereas during inflammation resolution (phase 2), the dominant subsets are the reparative macrophages, which propagate infarct repair (3, 4)....
[...]
TL;DR: In vivo that direct instillation of apoptotic cells enhanced the resolution of acute inflammation, and apoptotic cell recognition and clearance, via exposure of PS and ligation of its receptor, induce TGF-beta1 secretion, resulting in accelerated resolution of inflammation.
Abstract: Ingestion of apoptotic cells in vitro by macrophages induces TGF-beta1 secretion, resulting in an anti-inflammatory effect and suppression of proinflammatory mediators. Here, we show in vivo that direct instillation of apoptotic cells enhanced the resolution of acute inflammation. This enhancement appeared to require phosphatidylserine (PS) on the apoptotic cells and local induction of TGF-beta1. Working with thioglycollate-stimulated peritonea or LPS-stimulated lungs, we examined the effect of apoptotic cell uptake on TGF-beta1 induction. Viable or opsonized apoptotic human Jurkat T cells, or apoptotic PLB-985 cells, human monomyelocytes that do not express PS during apoptosis, failed to induce TGF-beta1. PS liposomes, or PS directly transferred onto the PLB-985 surface membranes, restored the TGF-beta1 induction. Apoptotic cell instillation into LPS-stimulated lungs reduced proinflammatory chemokine levels in the bronchoalveolar lavage fluid (BALF). Additionally, total inflammatory cell counts in the BALF were markedly reduced 1-5 days after apoptotic cell instillation, an effect that could be reversed by opsonization or coinstillation of TGF-beta1 neutralizing antibody. This reduction resulted from early decrease in neutrophils and later decreases in lymphocytes and macrophages. In conclusion, apoptotic cell recognition and clearance, via exposure of PS and ligation of its receptor, induce TGF-beta1 secretion, resulting in accelerated resolution of inflammation.
1,189 citations