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Frontiers in Immunology 2022Macrophages are essential innate immune cells that contribute to host defense during infection. An important feature of macrophages is their ability to respond to... (Review)
Review
Macrophages are essential innate immune cells that contribute to host defense during infection. An important feature of macrophages is their ability to respond to extracellular cues and to adopt different phenotypes and functions in response to these stimuli. The evidence accumulated in the last decade has highlighted the crucial role of metabolic reprogramming during macrophage activation in infectious context. Thus, understanding and manipulation of macrophage immunometabolism during infection could be of interest to develop therapeutic strategies. In this review, we focus on 5 major metabolic pathways including glycolysis, pentose phosphate pathway, fatty acid oxidation and synthesis, tricarboxylic acid cycle and amino acid metabolism and discuss how they sustain and regulate macrophage immune function in response to parasitic, bacterial and viral infections as well as trained immunity. At the end, we assess whether some drugs including those used in clinic and in development can target macrophage immunometabolism for potential therapy during infection with an emphasis on SARS-CoV2 infection.
Topics: Animals; COVID-19; Humans; Immunity, Innate; Infections; Macrophage Activation; Macrophages; SARS-CoV-2
PubMed: 35154105
DOI: 10.3389/fimmu.2022.780839 -
Frontiers in Immunology 2019Macrophage activation is intimately linked to metabolic reprogramming. Inflammatory (M1) macrophages are able to sustain inflammatory responses and to kill pathogens,... (Review)
Review
Macrophage activation is intimately linked to metabolic reprogramming. Inflammatory (M1) macrophages are able to sustain inflammatory responses and to kill pathogens, mostly by relying on aerobic glycolysis and fatty acid biosynthesis. Glycolysis is a fast way of producing ATP, and fatty acids serve as precursors for the synthesis of inflammatory mediators. On the opposite side, anti-inflammatory (M2) macrophages mediate the resolution of inflammation and tissue repair, switching their metabolism to fatty acid oxidation and oxidative phosphorylation. Over the years, this classical view has been challenged by recent discoveries pointing to a more complex metabolic network during macrophage activation. Lipid metabolism plays a critical role in the activation of both M1 and M2 macrophages. Recent evidence shows that fatty acid oxidation is also essential for inflammasome activation in M1 macrophages, and glycolysis is now known to fuel fatty acid oxidation in M2 macrophages. Ultimately, targeting lipid metabolism in macrophages can improve the outcome of metabolic diseases. Here, we review the main aspects of macrophage immunometabolism from the perspective of the metabolism of lipids. Building a reliable metabolic network during macrophage activation will bring us closer to targeting macrophages for improving human health.
Topics: Animals; Humans; Inflammation; Lipid Metabolism; Macrophage Activation; Macrophages; Metabolic Diseases
PubMed: 31998297
DOI: 10.3389/fimmu.2019.02993 -
Gut Dec 2021As a canonical membrane tethering factor, the function of synbindin has been expanding and indicated in immune response. Here, we investigated the role of synbindin in...
OBJECTIVE
As a canonical membrane tethering factor, the function of synbindin has been expanding and indicated in immune response. Here, we investigated the role of synbindin in the regulation of toll-like receptor 4 (TLR4) signalling and macrophage response to microbiota during colitis.
DESIGN
Three distinct mouse models allowing global, myeloid-specific or intestinal epithelial cell-specific synbindin heterozygous deletion were constructed and applied to reveal the function of synbindin during dextran sodium sulfate (DSS) colitis. Effects of synbindin on TLR4 signalling and macrophage activation in response to bacterial lipopolysaccharide (LPS) or were evaluated. The colocalisation and interaction between synbindin and Rab7b were determined by immunofluorescence and coimmunoprecipitation. Synbindin expression in circulating monocytes and intestinal mucosal macrophages of patients with active IBD was detected.
RESULTS
Global synbindin haploinsufficiency greatly exacerbated DSS-induced intestinal inflammation. The increased susceptibility to DSS was abolished by gut microbiota depletion, while phenocopied by specific synbindin heterozygous deletion in myeloid cells rather than intestinal epithelial cells. Profoundly aberrant proinflammatory gene signatures and excessive TLR4 signalling were observed in macrophages with synbindin interference in response to bacterial LPS or . Synbindin was significantly increased in intestinal mucosal macrophages and circulating monocytes from both mice with DSS colitis and patients with active IBD. Interleukin 23 and granulocyte-macrophage colony-stimulating factor were identified to induce synbindin expression. Mechanistic characterisation indicated that synbindin colocalised and directly interacted with Rab7b, which coordinated the endosomal degradation pathway of TLR4 for signalling termination.
CONCLUSION
Synbindin was a key regulator of TLR4 signalling and restrained the proinflammatory macrophage activation against microbiota during colitis.
Topics: Animals; Colitis; Disease Models, Animal; Gastrointestinal Microbiome; Humans; Intestinal Mucosa; Macrophage Activation; Mice; Nerve Tissue Proteins; Signal Transduction; Toll-Like Receptor 4; Vesicular Transport Proteins; rab7 GTP-Binding Proteins
PubMed: 33441378
DOI: 10.1136/gutjnl-2020-321094 -
Nature Reviews. Cardiology Apr 2020Monocytes and macrophages provide defence against pathogens and danger signals. These cells respond to stimulation in a fast and stimulus-specific manner by utilizing... (Review)
Review
Monocytes and macrophages provide defence against pathogens and danger signals. These cells respond to stimulation in a fast and stimulus-specific manner by utilizing complex cascaded activation by lineage-determining and signal-dependent transcription factors. The complexity of the functional response is determined by interactions between triggered transcription factors and depends on the microenvironment and interdependent signalling cascades. Dysregulation of macrophage phenotypes is a major driver of various diseases such as atherosclerosis, rheumatoid arthritis and type 2 diabetes mellitus. Furthermore, exposure of monocytes, which are macrophage precursor cells, to certain stimuli can lead to a hypo-inflammatory tolerized phenotype or a hyper-inflammatory trained phenotype in a macrophage. In atherosclerosis, macrophages and monocytes are exposed to inflammatory cytokines, oxidized lipids, cholesterol crystals and other factors. All these stimuli induce not only a specific transcriptional response but also interact extensively, leading to transcriptional and epigenetic heterogeneity of macrophages in atherosclerotic plaques. Targeting the epigenetic landscape of plaque macrophages can be a powerful therapeutic tool to modulate pro-atherogenic phenotypes and reduce the rate of plaque formation. In this Review, we discuss the emerging role of transcription factors and epigenetic remodelling in macrophages in the context of atherosclerosis and inflammation, and provide a comprehensive overview of epigenetic enzymes and transcription factors that are involved in macrophage activation.
Topics: Atherosclerosis; Epigenesis, Genetic; Macrophage Activation; Macrophages; Transcription, Genetic
PubMed: 31578516
DOI: 10.1038/s41569-019-0265-3 -
Immunity Nov 2021Alternatively activated macrophages (AAMs) contribute to the resolution of inflammation and tissue repair. However, molecular pathways that govern their differentiation...
Alternatively activated macrophages (AAMs) contribute to the resolution of inflammation and tissue repair. However, molecular pathways that govern their differentiation have remained incompletely understood. Here, we show that uncoupling protein-2-mediated mitochondrial reprogramming and the transcription factor GATA3 specifically controlled the differentiation of pro-resolving AAMs in response to the alarmin IL-33. In macrophages, IL-33 sequentially triggered early expression of pro-inflammatory genes and subsequent differentiation into AAMs. Global analysis of underlying signaling events revealed that IL-33 induced a rapid metabolic rewiring of macrophages that involved uncoupling of the respiratory chain and increased production of the metabolite itaconate, which subsequently triggered a GATA3-mediated AAM polarization. Conditional deletion of GATA3 in mononuclear phagocytes accordingly abrogated IL-33-induced differentiation of AAMs and tissue repair upon muscle injury. Our data thus identify an IL-4-independent and GATA3-dependent pathway in mononuclear phagocytes that results from mitochondrial rewiring and controls macrophage plasticity and the resolution of inflammation.
Topics: Biomarkers; Cell Differentiation; Energy Metabolism; Inflammation; Interleukin-33; Macrophage Activation; Macrophages; Mitochondria; Phagocytes; Signal Transduction
PubMed: 34644537
DOI: 10.1016/j.immuni.2021.09.010 -
Frontiers in Immunology 2022Cardiovascular diseases, the notorious killer, are mainly caused by atherosclerosis (AS) characterized by lipids, cholesterol, and iron overload in plaques. Macrophages...
Cardiovascular diseases, the notorious killer, are mainly caused by atherosclerosis (AS) characterized by lipids, cholesterol, and iron overload in plaques. Macrophages are effector cells and accumulate to the damaged and inflamed sites of arteries to internalize native and chemically modified lipoproteins to transform them into cholesterol-loaded foam cells. Foam cell formation is determined by the capacity of phagocytosis, migration, scavenging, and the features of phenotypes. Macrophages are diverse, and the subsets and functions are controlled by their surrounding microenvironment. Generally, macrophages are divided into classically activated (M1) and alternatively activated (M2). Recently, intraplaque macrophage phenotypes are recognized by the stimulation of CXCL4 (M4), oxidized phospholipids (Mox), hemoglobin/haptoglobin complexes [HA-mac/M(Hb)], and heme (Mhem). The pro-atherogenic or anti-atherosclerotic phenotypes of macrophages decide the progression of AS. Besides, apoptosis, necrosis, ferroptosis, autophagy and pyrotopsis determine plaque formation and cardiovascular vulnerability, which may be associated with macrophage polarization phenotypes. In this review, we first summarize the three most popular hypotheses for AS and find the common key factors for further discussion. Secondly, we discuss the factors affecting macrophage polarization and five types of macrophage death in AS progression, especially ferroptosis. A comprehensive understanding of the cellular and molecular mechanisms of plaque formation is conducive to disentangling the candidate targets of macrophage-targeting therapies for clinical intervention at various stages of AS.
Topics: Atherosclerosis; Foam Cells; Humans; Macrophage Activation; Macrophages; Plaque, Atherosclerotic
PubMed: 35432323
DOI: 10.3389/fimmu.2022.843712 -
The Journal of Allergy and Clinical... Apr 2019
Topics: Humans; Macrophage Activation; Macrophages
PubMed: 30639344
DOI: 10.1016/j.jaci.2018.12.995 -
Molecular Cancer Feb 2021Noncoding RNA (ncRNA) transcripts that did not code proteins but regulate their functions were extensively studied for the last two decades and the plethora of... (Review)
Review
Noncoding RNA (ncRNA) transcripts that did not code proteins but regulate their functions were extensively studied for the last two decades and the plethora of discoveries have instigated scientists to investigate their dynamic roles in several diseases especially in cancer. However, there is much more to learn about the role of ncRNAs as drivers of malignant cell evolution in relation to macrophage polarization in the tumor microenvironment. At the initial stage of tumor development, macrophages have an important role in directing Go/No-go decisions to the promotion of tumor growth, immunosuppression, and angiogenesis. Tumor-associated macrophages behave differently as they are predominantly induced to be polarized into M2, a pro-tumorigenic type when recruited with the tumor tissue and thereby favoring the tumorigenesis. Polarization of macrophages into M1 or M2 subtypes plays a vital role in regulating tumor progression, metastasis, and clinical outcome, highlighting the importance of studying the factors driving this process. A substantial number of studies have demonstrated that ncRNAs are involved in the macrophage polarization based on their ability to drive M1 or M2 polarization and in this review we have described their functions and categorized them into oncogenes, tumor suppressors, Juggling tumor suppressors, and Juggling oncogenes.
Topics: Animals; Biomarkers, Tumor; Cell Plasticity; Disease Susceptibility; Gene Expression Regulation, Neoplastic; Humans; Macrophage Activation; Macrophages; MicroRNAs; Molecular Targeted Therapy; Neoplasms; RNA, Long Noncoding; RNA, Untranslated; Tumor Microenvironment
PubMed: 33522932
DOI: 10.1186/s12943-021-01313-x -
Nature Reviews. Immunology May 2019Itaconate is one of the best examples of the consequences of metabolic reprogramming during immunity. It is made by diverting aconitate away from the tricarboxylic acid... (Review)
Review
Itaconate is one of the best examples of the consequences of metabolic reprogramming during immunity. It is made by diverting aconitate away from the tricarboxylic acid cycle during inflammatory macrophage activation. The main reason macrophages exhibit this response currently appears to be for an anti-inflammatory effect, with itaconate connecting cell metabolism, oxidative and electrophilic stress responses and immune responses. A role for itaconate in the regulation of type I interferons during viral infection has also been described, as well as in M2 macrophage function under defined circumstances. Finally, macrophage-specific itaconate production has also been shown to have a pro-tumour effect. All of these studies point towards itaconate being a critical immunometabolite that could have far-reaching consequences for immunity, host defence and tumorigenesis.
Topics: Animals; Child; Humans; Inflammation; Interferon Type I; Macrophage Activation; Macrophages; Oxidation-Reduction; Succinates
PubMed: 30705422
DOI: 10.1038/s41577-019-0128-5 -
Biomaterials Jun 2020Macrophages are among the first cells to interact with biomaterials and ultimately determine their integrative fate. Biomaterial surface characteristics like roughness...
Macrophages are among the first cells to interact with biomaterials and ultimately determine their integrative fate. Biomaterial surface characteristics like roughness and hydrophilicity can activate macrophages to an anti-inflammatory phenotype. Wnt signaling, a key cell proliferation and differentiation pathway, has been associated with dysregulated macrophage activity in disease. However, the role Wnt signaling plays in macrophage activation and response to biomaterials is unknown. The aim of this study was to characterize the regulation of Wnt signaling in macrophages during classical pro- and anti-inflammatory polarization and in their response to smooth, rough, and rough-hydrophilic titanium (Ti) surfaces. Peri-implant Wnt signaling in macrophage-ablated (MaFIA) mice instrumented with intramedullary Ti rods was significantly attenuated compared to untreated controls. Wnt ligand mRNA were upregulated in a surface modification-dependent manner in macrophages isolated from the surface of Ti implanted in C57Bl/6 mice. In vitro, Wnt mRNAs were regulated in primary murine bone-marrow-derived macrophages cultured on Ti in a surface modification-dependent manner. When macrophageal Wnt secretion was inhibited, macrophage sensitivity to both physical and biological stimuli was abrogated. Loss of macrophage-derived Wnts also impaired recruitment of mesenchymal stem cells and T-cells to Ti implants in vivo. Finally, inhibition of integrin signaling decreased surface-dependent upregulation of Wnt genes. These results suggest that Wnt signaling regulates macrophage response to biomaterials and that macrophages are an important source of Wnt ligands during inflammation and healing.
Topics: Animals; Biocompatible Materials; Macrophage Activation; Macrophages; Mice; Surface Properties; Titanium; Wnt Signaling Pathway
PubMed: 32179303
DOI: 10.1016/j.biomaterials.2020.119920