Novel metabolic adaptation promotes enhanced macrophage efferocytosis under a limited-oxygen environment
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE192969 | GEO | 2022/12/30
REPOSITORIES: GEO
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Project description:Phagocytes in different tissues recognize and remove apoptotic cells via the process of efferocytosis. Although it is well-established that efferocytosis elicits an anti-inflammatory response by phagocytes, the molecules and mechanisms that enforce this response in phagocytes are still being defined. In attempting to decipher gene programs induced after a phagocyte ingests a dying cell, we uncovered a chloride-sensing signaling pathway that controls both the ‘appetite’ of a phagocyte and how a phagocyte responds after corpse uptake. First, we noted that within phagocytes that have ingested a corpse, the solute carrier 12 (SLC12) family members SLC12A2 and SLC12A4 are actively modulated. Interfering with SLC12A2, either genetically or pharmacologically, led to significantly enhanced corpse uptake per phagocyte, while loss of SLC12A4 inhibited corpse uptake. Interestingly, when phagocytes with disrupted SLC12A2 engulfed apoptotic corpses, the typical homeostatic efferocytosis signature was perturbed, characterized by loss of the canonical anti-inflammatory program and replaced by pro-inflammatory and oxidative stress-associated gene programs. In further mechanistic studies, we observed efferocytosis was also regulated by the chloride-sensing pathway upstream of SLC12A2, including the kinases WNK1-OSR1-SPAK, and this involved chloride entry/exit across the plasma membrane of phagocytes during corpse engulfment. We also show that the ‘switch’ to pro-inflammatory sensing of apoptotic cells is specifically due to disruption of the chloride-sensing pathway and not due to corpse overload or poor degradation, and that the pro-inflammatory gene signature can be reversed using a chloride ionophore. Collectively, these data identify the WNK1-OSR1-SPAK-SLC12A2/SLC12A4 chloride-sensing pathway and chloride flux in phagocytes as key modifiers of how a phagocyte interprets an engulfed apoptotic corpse.
2020-03-24 | GSE131860 | GEO
Project description:Efferocytosis triggers cellular reprogramming, including the induction of mRNA transcripts which encode anti-inflammatory cytokines that promote inflammation resolution. Our current understanding of this transcriptional response is largely informed from analysis of bulk phagocyte populations; however, this precludes the resolution of heterogeneity between individual macrophages and macrophage subsets. Moreover, phagocytes may contain so called “passenger” transcripts that originate from engulfed apoptotic bodies, thus obscuring the true transcriptional reprogramming of the phagocyte. To define the transcriptional diversity during efferocytosis, we utilized single-cell mRNA sequencing after co-cultivating macrophages with apoptotic cells. Importantly, transcriptomic analyses were performed after validating the disappearance of apoptotic cell-derived RNA sequences. Our findings reveal new heterogeneity of the efferocytic response at a single-cell resolution, particularly evident between F4/80+ MHCIILO and F4/80- MHCIIHI macrophage sub-populations. After exposure to apoptotic cells, the F4/80+ MHCIILO subset significantly induced pathways associated with tissue and cellular homeostasis, while the F4/80- MHCIIHI subset downregulated these putative signaling axes. Ablation of a canonical efferocytosis receptor, MerTK, blunted efferocytic signatures and led to the escalation of cell death-associated transcriptional signatures in F4/80+ MHCIILO macrophages. Taken together, our results newly elucidate the heterogenous transcriptional response of single-cell peritoneal macrophages after exposure to apoptotic cells.
2020-08-22 | GSE156234 | GEO
Project description:Inflammation is a physiopathological process triggered by infection or tissue damage. Immune system initiates coordinated sequential steps in response to these danger signals. Once the threat has been contained inflammation has to be subsequently shut down. Inflammation resolution is initiated by the reprogramming of pro-inflammatory macrophages toward a pro-resolving profile. This reprogramming is induced in particular by the non-phlogistic engulfment of apoptotic cells, mostly apoptotic neutrophils, a process called efferocytosis. As a matter of fact, macrophages are an essential linchpin regulating both inflammation triggering and sustaining and inflammation resolution. This duality can be achieved through the tremendous plasticity of these innate immune cells. Indeed, depending on microenvironmental signals (cytokines, efferocytosis, growth factors…) macrophages can adopt numerous diverse and sometimes antagonistic phenotypes. The mechanisms governing these transitions remain relatively scattered especially in human. With this project we propose to explore the mechanisms involved in human macrophage reprogramming toward a pro-resolving profile after efferocytosis. The stakes are high due to the estimated prevalence of chronic inflammatory diseases in Western society is 5 to 7%. Chronic inflammation is a burden to patient due to life-long debilitating illness and increased mortality and is also a burden to society due to high costs for therapy and care. Finding new therapies to limit chronic inflammation establishment and persistence is thus a highly valuable goal.
2021-12-01 | E-MTAB-8885 | biostudies-arrayexpress
Project description:Poor wound healing due to dysregulated tissue repair responses can exacerbate and prolong disease. Successful tissue repair is critically dependent on the timely clearance of apoptotic cells by macrophages in a process termed efferocytosis. Mechanisms and factors that link these two fundamental processes are therefore of great interest. Herein, we observed that a subset of 12-lipoxygenase (ALOX12)-expressing macrophages upregulate the production of host protective autacoids termed maresin conjugates in tissue regeneration (MCTR) during efferocytosis. MCTRs in turn play autocrine and paracrine functions in enhancing the ability of both ALOX12-positive and surrounding ALOX12-negative macrophages to uptake apoptotic cells. These effects of ALOX12-positive macrophages and MCTRs in regulating apoptotic cells clearance was also observed at sites of high apoptotic cell burden in mouse and flatworm models, as the formation of these mediators was upregulated and abrogation of related ALOX activity in mice reduced the ability of macrophages to clear apoptotic cells. Furthermore, add-back of MCTRs rapidly enhanced the efferocytosis capability of macrophages in mice and planarian flatworms. Mechanistic studies in macrophages revealed that MCTRs modulated Rac1 signalling and glycolytic metabolism, two pathways crucial for effective efferocytosis, and enhanced efferocytosis-induced WNT ligand production. Inhibition of Rac1 abrogated the ability of MCTRs to enhance glucose uptake and efferocytosis in vitro, while inhibiting either Rac1, glycolysis, or WNT ligand production prevented MCTR-mediated enhancement of apoptotic cell clearance and tissue regeneration. Taken together, our findings identify a central role for ALOX12-expressing macrophages in the regulation of efferocytosis and tissue repair via the local formation of MCTRs.
2023-12-12 | PXD038390 | Pride
Project description:Tissue-resident macrophages (TRMs) are heterogeneous cell populations found throughout the body. Depending on their location, they perform diverse functions maintaining tissue homeostasis and providing immune surveillance. To survive and function within, TRMs adapt metabolically to the distinct microenvironments. However, little is known about the metabolic signatures of TRMs. The thymus provides a nurturing milieu for developing thymocytes yet efficiently removes those that failed the selection, relying on the TRMs – resident thymic macrophages (TMφs). This study harnesses multiomics analyses to characterize TMφs and unveils their unique metabolic features. We find that the pentose phosphate pathway (PPP) is preferentially activated in TMφs, responding to the reduction-oxidation demands associated with the efferocytosis of dying thymocytes. The blockade of PPP in Mφs leads to decreased efferocytosis, which can be rescued by ROS scavengers. Our study reveals the key role of PPP in TMφs and underscores the importance of metabolic adaptation in supporting Mφ efferocytosis.
2022-06-02 | GSE203543 | GEO
Project description:Clearance of apoptotic cancer cells by macrophages, known as efferocytosis, fuels the bone-metastatic growth of prostate cancer cells via pro-inflammatory and immunosuppressive mechanisms that are still unclear. In this study, single-cell transcriptomics of bone marrow macrophages undergoing efferocytosis of apoptotic prostate cancer cells revealed a significant enrichment of a cellular response to hypoxia. Here we show that efferocytic macrophages promote HIF-1α stabilization under normoxic conditions through interaction with phosphorylated STAT3. Inflammatory cytokine gene expression analysis of efferocytic HIF-1α-mutant macrophages revealed a reduced expression of the pro-tumorigenic Mif. Furthermore, stabilization of HIF-1α using the HIF-prolyl-hydroxylase inhibitor, Roxadustat, enhanced MIF expression in macrophages. Finally, macrophages treated with recombinant MIF protein activated NF-κB (p65) signaling increased the expression of pro-inflammatory cytokines. Altogether, these findings suggest that the clearance of apoptotic cancer cell by tumor-associated macrophages triggers p-STAT3/HIF-1α/MIF signaling to enhance tumor-promoting inflammation in bone, suggesting this axis as a target for metastatic prostate cancer.
2022-12-14 | GSE180638 | GEO
Project description:Macrophages can adjust their phenotype and function in response to environmental cues, such as encountering apoptotic cells or pathogens. After tissue injury or inflammation, macrophages must successively engulf and process multiple apoptotic corpses (via efferocytosis) to achieve tissue homeostasis. How macrophages may rapidly adapt their transcription to achieve continued corpse uptake is incompletely understood. Transcriptional pause/release is an evolutionarily conserved process wherein RNA polymerase II (Pol II), after initiating transcription for 20-60 nucleotides, gets ‘paused’ for seconds to hours; paused Pol II then gets ‘released’ to complete transcription to make full-length mRNA. Here we show that macrophages, within minutes of corpse encounter, use transcriptional pause/release as a mechanism to unleash a rapid transcriptional response. For human and murine macrophages, the Pol II pause/release was crucial for continued efferocytosis of corpses in vitro and in vivo. Interestingly, blocking Pol II pause/release did not impede FcR-mediated phagocytosis, yeast uptake, or bacterial phagocytosis. Integrating data from three complementary genomic approaches of PRO-seq, RNA-seq, and ATAC-seq on efferocytic macrophages at different time points, we found that Pol II pause/release controls expression of select transcription factors and downstream target genes. Further mechanistic studies on transcription factor Egr3, one of the genes prominently affected by pause/release, uncovered Egr3-related reprogramming of macrophage genes involved in cytoskeleton and corpse processing. Via lysosomal probes and a newly designed genetic fluorescent reporter, we identify a key role for pause/release in phagosome acidification during efferocytosis. Further, microglia from egr3-deficient zebrafish embryos displayed reduced phagocytosis of apoptotic neurons and fewer maturing endosomes, supporting a defect in corpse processing. Collectively, these data advance a novel concept that macrophages use Polymerase II pause/release as a mechanism to rapidly alter their transcriptional programs for efficient processing of the ingested apoptotic corpse and for successive efferocytosis.
2024-01-25 | GSE253577 | GEO
Project description:Macrophages can adjust their phenotype and function in response to environmental cues, such as encountering apoptotic cells or pathogens. After tissue injury or inflammation, macrophages must successively engulf and process multiple apoptotic corpses (via efferocytosis) to achieve tissue homeostasis. How macrophages may rapidly adapt their transcription to achieve continued corpse uptake is incompletely understood. Transcriptional pause/release is an evolutionarily conserved process wherein RNA polymerase II (Pol II), after initiating transcription for 20-60 nucleotides, gets ‘paused’ for seconds to hours; paused Pol II then gets ‘released’ to complete transcription to make full-length mRNA. Here we show that macrophages, within minutes of corpse encounter, use transcriptional pause/release as a mechanism to unleash a rapid transcriptional response. For human and murine macrophages, the Pol II pause/release was crucial for continued efferocytosis of corpses in vitro and in vivo. Interestingly, blocking Pol II pause/release did not impede FcR-mediated phagocytosis, yeast uptake, or bacterial phagocytosis. Integrating data from three complementary genomic approaches of PRO-seq, RNA-seq, and ATAC-seq on efferocytic macrophages at different time points, we found that Pol II pause/release controls expression of select transcription factors and downstream target genes. Further mechanistic studies on transcription factor Egr3, one of the genes prominently affected by pause/release, uncovered Egr3-related reprogramming of macrophage genes involved in cytoskeleton and corpse processing. Via lysosomal probes and a newly designed genetic fluorescent reporter, we identify a key role for pause/release in phagosome acidification during efferocytosis. Further, microglia from egr3-deficient zebrafish embryos displayed reduced phagocytosis of apoptotic neurons and fewer maturing endosomes, supporting a defect in corpse processing. Collectively, these data advance a novel concept that macrophages use Polymerase II pause/release as a mechanism to rapidly alter their transcriptional programs for efficient processing of the ingested apoptotic corpse and for successive efferocytosis.
2024-01-25 | GSE253576 | GEO
Project description:Macrophages can adjust their phenotype and function in response to environmental cues, such as encountering apoptotic cells or pathogens. After tissue injury or inflammation, macrophages must successively engulf and process multiple apoptotic corpses (via efferocytosis) to achieve tissue homeostasis. How macrophages may rapidly adapt their transcription to achieve continued corpse uptake is incompletely understood. Transcriptional pause/release is an evolutionarily conserved process wherein RNA polymerase II (Pol II), after initiating transcription for 20-60 nucleotides, gets ‘paused’ for seconds to hours; paused Pol II then gets ‘released’ to complete transcription to make full-length mRNA. Here we show that macrophages, within minutes of corpse encounter, use transcriptional pause/release as a mechanism to unleash a rapid transcriptional response. For human and murine macrophages, the Pol II pause/release was crucial for continued efferocytosis of corpses in vitro and in vivo. Interestingly, blocking Pol II pause/release did not impede FcR-mediated phagocytosis, yeast uptake, or bacterial phagocytosis. Integrating data from three complementary genomic approaches of PRO-seq, RNA-seq, and ATAC-seq on efferocytic macrophages at different time points, we found that Pol II pause/release controls expression of select transcription factors and downstream target genes. Further mechanistic studies on transcription factor Egr3, one of the genes prominently affected by pause/release, uncovered Egr3-related reprogramming of macrophage genes involved in cytoskeleton and corpse processing. Via lysosomal probes and a newly designed genetic fluorescent reporter, we identify a key role for pause/release in phagosome acidification during efferocytosis. Further, microglia from egr3-deficient zebrafish embryos displayed reduced phagocytosis of apoptotic neurons and fewer maturing endosomes, supporting a defect in corpse processing. Collectively, these data advance a novel concept that macrophages use Polymerase II pause/release as a mechanism to rapidly alter their transcriptional programs for efficient processing of the ingested apoptotic corpse and for successive efferocytosis.
2024-01-25 | GSE253574 | GEO
Project description:Efficient clearance and degradation of apoptotic cardiomyocytes by macrophages (termed efferocytosis) are critical for inflammation resolution and restoration of cardiac function after myocardial ischemia/reperfusion (I/R). Here, we define secreted and transmembrane protein 1a (Sectm1a), a cardiac macrophage-enriched gene, as a modulator of macrophage efferocytosis in I/R hearts. Upon myocardial I/R, Sectm1a-KO mice exhibit impaired macrophage efferocytosis, leading to massive accumulation of apoptotic cardiomyocytes, cardiac inflammation, fibrosis, and consequently, exaggerated cardiac dysfunction. By contrast, therapeutic administration of recombinant SECTM1A protein significantly enhances macrophage efferocytosis and improves cardiac function. Mechanistically, SECTM1A can elicit autocrine effects on the activation of glucocorticoid-induced TNF receptor (GITR) at the surface of macrophages, leading to the upregulation of liver X receptor alpha (LXRα) and its downstream efferocytosis-related genes and lysosomal enzyme genes. Our study suggests that Sectm1a-mediated activation of Gitr/LXRα axis could be a promising approach to enhance macrophage efferocytosis for the treatment of myocardial I/R injury.
2024-01-23 | GSE253579 | GEO