Lysosome-dependent LXR and PPARdelta Activation upon Efferocytosis in Human Macrophages
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ABSTRACT:
PROVIDER: PRJNA715460 | ENA |
REPOSITORIES: ENA
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Project description:Efferocytosis is critical for tissue homeostasis, as its deregulation is associated with several autoimmune pathologies. While engulfing apoptotic cells, phagocytes activate transcription factors, such as peroxisome proliferator-activated receptors (PPAR) or liver X receptors (LXR) that orchestrate metabolic, phagocytic, and inflammatory responses towards the ingested material. Coordination of these transcription factors in efferocytotic human macrophages (MF) is not fully understood. In this study, we evaluated the transcriptional profile of MF following the uptake of apoptotic Jurkat T cells using RNA-seq analysis. Results indicated upregulation of PPAR and LXR pathways but downregulation of sterol regulatory element-binding proteins (SREBP) target genes. Pharmacological inhibition and RNA interference pointed to LXR and PPARdelta as relevant transcriptional regulators, while PPARdelta did not substantially contribute to gene regulation. Mechanistically, lysosomal digestion and lysosomal acid lipase (LIPA) were required for PPAR and LXR activation, while PPARdelta activation also demanded an active lysosomal phospholipase A2 (PLA2G15). Pharmacological interference with LXR signaling attenuated ABCA1-dependent cholesterol efflux from efferocytotic MF, but suppression of inflammatory responses following efferocytosis occurred independently of LXR and PPARdelta. These data provide mechanistic details on LXR and PPARdelta activation in efferocytotic human MF.
2021-05-26 | GSE169160 | GEO
Project description: Not available
| S-EPMC8137840 | biostudies-literature
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:Despite the importance of rapid adaptive responses for an efficient resolution of inflammation, which are commonly regulated on a post-transcriptional and specifically translational level, translational changes caused by efferocytosis remain largely elusive. To gain further insights into such gene regulatory principles, we analyzed translational changes in efferocytic and non-efferocytic bone marrow-derived macrophages (BMDM) in the course of inflammation. Using total RNA-sequencing, we confirmed that efferocytosis induced a pro-resolution signature in LPS-stimulated, inflammatory macropahges. Interestingly though, while LPS-induced transcriptional changes appeared rather small between efferocytic and non-efferocytic macrophages, we observed considerable differences on the level of de novo synthesized proteins. We further identified translationally regulated targets showing reduced translation upon inflammatory stimulation, which was buffered upon efferocytosis. Herein, pro-resolving matrix metallopeptidase 12 (Mmp12) emerged as a novel translationally regulated candidate, which was translationally repressed during early inflammation and increased during the resolution phase. Functionally, the translational repression of Mmp12 was linked to increased spontaneous two-dimensional migration. In summary, we identified the novel translationally regulated target Mmp12 in the context of the resolution of inflammation in primary murine macrophages, which is associated with a modulation of spontaneous migration.
2023-12-13 | GSE245834 | GEO
Project description:To investigate how LXR activation potentiates expression of Th2 cytokine-dependent genes in primary human macrophages, we pulsed macrophages with synthetic LXR ligand T0901317 then polarized cells to alternatively activated macrophages with IL-4 or IL-13.
2021-04-14 | GSE158022 | GEO
Project description:To identify novel LXR target genes, we conducted transcriptional profiling studies using RAW264.7 cells ectopically expressing LXRalpha
2009-08-01 | GSE17088 | 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: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
Project description:Liver X Receptor (LXR) activation in intestinal epithelial organoids promotes their growth in vitro. To investigate the downstream effect of LXR activation in intestinal epithelial cells and identify potential pathways driving regeneration, we carried out an unbiased transcriptomic analysis of intestinal epithelial organoids stimulated with the LXR agonist GW3965. In detail, wild type small intestinal crypts were seeded in vitro and stimulated with vehicle (DMSO) or GW3965. After six hours, closing crypts (organoids) were collected for RNA extraction and were analyzed by RNA sequencing.
2023-06-11 | GSE152283 | GEO
Project description:The efficient clearance of dead and dying cells, also known as efferocytosis, is critical to maintain tissue homeostasis. In the bone marrow microenvironment (BMME), this role is primarily fulfilled by professional bone marrow macrophages, but recent work has shown that mesenchymal stromal cells (MSCs) act as a non-professional phagocyte within the BMME. However, little is known about the mechanism and impact of efferocytosis on MSCs in the BMME and on their function. To investigate this, we performed flow cytometric analysis of neutrophil uptake by ST2 cells, a murine bone marrow-derived stromal cell line, and in murine primary bone marrow-derived stromal cells. Transcriptional analysis showed that MSCs possess the necessary receptors and internal processing machinery to conduct efferocytosis, with Axl and Tyro3 serving as the main receptors, while MerTK was not expressed. Moreover, the expression of these receptors was modulated by efferocytic behavior, regardless of apoptotic target. MSCs derived from human bone marrow also demonstrated efferocytic behavior, showing that MSC efferocytosis is conserved. In all MSCs, efferocytosis impaired osteoblastic differentiation. Transcriptional analysis and functional assays identified downregulation in MSC mitochondrial function upon efferocytosis. Experimentally, efferocytosis induced mitochondrial fission in MSCs. Pharmacologic inhibition of mitochondrial fission in MSCs not only decreased efferocytic activity but also rescued osteoblastic differentiation, demonstrating that efferocytosis-mediated mitochondrial remodeling plays a critical role in regulating MSC differentiation. This work describes a novel function of MSCs as non-professional phagocytes within the BMME and demonstrates that efferocytosis by MSCs plays a key role in directing mitochondrial remodeling and MSC differentiation. Efferocytosis by MSCs may therefore be a novel mechanism of dysfunction and senescence. Since our data in human MSCs show that MSC efferocytosis is conserved, the consequences of MSC efferocytosis may impact the behavior of these cells in the human skeleton, including osteoporosis in aging.
2023-07-14 | GSE223279 | GEO