Exhaustion-associated cholesterol deficiency dampens the cytotoxic arm of antitumor immunity
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ABSTRACT:
ORGANISM(S): Mus musculus Homo sapiens
PROVIDER: GSE229611 | GEO | 2023/04/13
REPOSITORIES: GEO
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Project description:Mycobacterium tuberculosis (Mtb) is a life-threatening pathogen in humans. Bacterial infection of macrophages usually triggers strong innate immune mechanisms, including IL-1 cytokine secretion. The newer member of the IL-1 family, IL-36, was recently shown to be involved in cellular defense against Mtb. To unveil the underlying mechanism of IL-36 induced antibacterial activity, we analyzed its role in the regulation of cholesterol metabolism, together with the involvement of Liver X Receptor (LXR) in this process. Here we report that, in Mtb-infected macrophages, IL-36 signaling modulates cholesterol biosynthesis and efflux via LXR. Moreover, IL-36 induces the expression of cholesterol-converting enzymes and the accumulation of LXR ligands, such as oxysterols. Ultimately, both IL-36 and LXR signaling play a role in the regulation of antimicrobial peptides expression and in Mtb growth restriction. These data provide novel evidence for the importance of IL‑36 and cholesterol metabolism mediated by LXR in cellular host defense against Mtb.
2018-02-14 | GSE103092 | GEO
Project description:Circulating levels of the gut microbe-derived metabolite trimethylamine-N-oxide(TMAO) have recently been linked to cardiovascular disease (CVD) risk. Here we performed transcriptional profiling in mouse models of altered reverse cholesterol transport (RCT), and serendipitously identified the TMAO-generating enzyme flavin monooxygenase 3 (FMO3) as a powerful modifier of cholesterol metabolism and RCT. Knockdown of FMO3 in cholesterol-fed mice alters biliary lipid secretion, blunts intestinal cholesterol absorption, and limits the production of hepatic oxysterols and cholesteryl esters. Furthermore, FMO3 knockdown stimulates basal and liver X receptor (LXR)-stimulated macrophage RCT, thereby improving cholesterol balance. Conversely, FMO3 knockdown exacerbates hepatic ER stress and inflammation in part by decreasing hepatic oxysterol levels and subsequent LXR activation. FMO3 is thus identified as a central integrator of hepatic cholesterol and triacylglycerol metabolism, inflammation, and ER stress. These studies suggest that the gut microbiota-driven TMA/FMO3/TMAO pathway is a key regulator of lipid metabolism and inflammation. To identify potential regulators of macrophage reverse cholesterol transport (RCT), liver was isolated from two independent mouse models where the non-biliary RCT pathway known as transintestinal cholesterol excretion (TICE) was either chronically (NPC1L1-liver-transgenic mice) or acutely (ACAT2 antisense oligonucleotide treatment) stimulated. Total RNA was isolated and gene expression levels were profiled on the Affymetrix GeneAtlas MG-430 PM Array Strip (Affymetrix; Santa Clara, CA, USA)
2014-12-19 | E-GEOD-64326 | biostudies-arrayexpress
Project description:Circulating levels of the gut microbe-derived metabolite trimethylamine-N-oxide(TMAO) have recently been linked to cardiovascular disease (CVD) risk. Here we performed transcriptional profiling in mouse models of altered reverse cholesterol transport (RCT), and serendipitously identified the TMAO-generating enzyme flavin monooxygenase 3 (FMO3) as a powerful modifier of cholesterol metabolism and RCT. Knockdown of FMO3 in cholesterol-fed mice alters biliary lipid secretion, blunts intestinal cholesterol absorption, and limits the production of hepatic oxysterols and cholesteryl esters. Furthermore, FMO3 knockdown stimulates basal and liver X receptor (LXR)-stimulated macrophage RCT, thereby improving cholesterol balance. Conversely, FMO3 knockdown exacerbates hepatic ER stress and inflammation in part by decreasing hepatic oxysterol levels and subsequent LXR activation. FMO3 is thus identified as a central integrator of hepatic cholesterol and triacylglycerol metabolism, inflammation, and ER stress. These studies suggest that the gut microbiota-driven TMA/FMO3/TMAO pathway is a key regulator of lipid metabolism and inflammation.
2014-12-19 | GSE64326 | GEO
Project description:Dysregulation of cholesterol metabolism and homeostasis is associated with the pathology of many diseases such as cardiovascular disease and cancer. Two major upstream regulators of cholesterol homeostasis are the SREBP2 pathway and the actions of the liver X receptors (LXRs), with the liver thought to handle the majority of cholesterol homeostasis at the organismal level. Endogenous cholesterol metabolites such as 27-hydroxycholesterol (27HC), which serve to activate the nuclear receptor LXR, result in increased expression of genes associated with cholesterol catabolism and efflux. LXR and various LXR ligands such as 27HC have been described to influence several extra-hepatic biological systems. However, disparate reports of LXR function have emerged, especially with respect to immunology and cancer biology. This would suggest that similar to steroid nuclear receptors, the LXR may be selectively modulated by ligands. Here, we use bulk RNA-sequencing of bone marrow-derived macrophages and single-cell RNA-sequencing of immune cells from murine lungs bearing metastatic mammary cancer, to prove that LXR satisfies the two principles of selective nuclear receptor modulation: (1) different LXR ligands result in overlapping but distinct gene expression profiles within the same cell type, and (2) the same LXR ligands differentially regulate gene expression in a highly context-specific manner, depending on cell or tissue type. The concept that the LXR can be selectively modulated provides the foundation for the development of ligands that are tailored to promote those activities that are desirable (pro-immune), but at the same time minimizing harmful side effects (such as elevated triglyceride levels).
2022-06-01 | GSE186910 | GEO
Project description:Dysregulation of cholesterol metabolism and homeostasis is associated with the pathology of many diseases such as cardiovascular disease and cancer. Two major upstream regulators of cholesterol homeostasis are the SREBP2 pathway and the actions of the liver X receptors (LXRs), with the liver thought to handle the majority of cholesterol homeostasis at the organismal level. Endogenous cholesterol metabolites such as 27-hydroxycholesterol (27HC), which serve to activate the nuclear receptor LXR, result in increased expression of genes associated with cholesterol catabolism and efflux. LXR and various LXR ligands such as 27HC have been described to influence several extra-hepatic biological systems. However, disparate reports of LXR function have emerged, especially with respect to immunology and cancer biology. This would suggest that similar to steroid nuclear receptors, the LXR may be selectively modulated by ligands. Here, we use bulk RNA-sequencing of bone marrow-derived macrophages and single-cell RNA-sequencing of immune cells from murine lungs bearing metastatic mammary cancer, to prove that LXR satisfies the two principles of selective nuclear receptor modulation: (1) different LXR ligands result in overlapping but distinct gene expression profiles within the same cell type, and (2) the same LXR ligands differentially regulate gene expression in a highly context-specific manner, depending on cell or tissue type. The concept that the LXR can be selectively modulated provides the foundation for the development of ligands that are tailored to promote those activities that are desirable (pro-immune), but at the same time minimizing harmful side effects (such as elevated triglyceride levels).
2022-06-01 | GSE186909 | GEO
Project description:Immunometabolism is a growing field that centers on a core paradigm: perturbations in metabolism alter a cell’s biological response in immunity and, likewise, inflammatory signals, such as cytokines and pathogens, can directly influence cellular metabolism. Although the carbons within cholesterol cannot be used for catabolic energy production, there is a growing appreciation that a similar relationship exists between cholesterol homeostasis and immunity. The majority of this literature is focused on cholesterol dynamics in the context of leukocyte immunobiology. However, the endothelium also plays an important role during the acute inflammatory response. Endothelial cells (ECs) rapidly respond to extrinsic signals, such as tissue damage or microbial infection, by upregulating factors to activate and recruit circulating leukocytes to the site of injury. Dysregulation or aberrant activation of ECs leads to disease, such as atherosclerosis. I studied the role of cholesterol and its master regulator, SREBP2, in the EC response to acute inflammatory stress. ECs treated with cytokines upregulated SREBP2 cleavage and classical cholesterol biosynthesis gene expression within the late phase of the acute inflammatory response. Furthermore, SREBP2 activation was dependent on NF-kB DNA binding and classical SCAP-SREBP2 processing. We used bacterial cytolysin probes to show that inflammatory stress significantly decreased accessible cholesterol, leading to dysfunctional sterol sensing and downstream SREBP2 cleavage. We also explored what role SREBP2 plays in the EC inflammatory response. Loss of SREBP2 in ECs treated with inflammatory cytokine altered EC phenotype, which was defined by decreased chemokine expression and increased type I inflammatory signaling. Interestingly, this effect on the EC inflammatory transcriptome could not be accounted by changes in cholesterol, but rather through SREBP2 binding to promoters of pro-inflammatory transcription factors. Preliminary results revealed that BHLHE40 and KLF6 are direct targets of SREBP2 and that loss of one of KLF6 could mimic the effect of SREBP2 knockdown on chemokine expression. This study is the first to provide an in-depth characterization of the relationship between SREBP2 and the endothelial acute inflammatory response.
2022-07-14 | GSE207919 | GEO
Project description:Cholesterol homeostasis plays a central role in disease pathogenesis in chronic disorders such as cardiovascular and kidney diseases. The transcription factor SREBP2 is the main regulator of cholesterol metabolism and is central to the mechanism of action of lipid lowering drugs, such as statins, that are responsible for the largest overall reduction in cardiovascular risk and mortality in humans with atherosclerotic cardiovascular disease. Recently, SREBP2 has been implicated in both the innate and adaptive immune responses by upregulation of cholesterol flux or via direct transcriptional activation of pro-inflammatory genes in leukocytes. Here, we investigate the role of SREBP2 in endothelial cells (ECs), since ECs are at the interface of circulating lipids with tissues and are activated in response to damage and inflammation. The loss of SREBP2 in cultured human ECs results in significant alterations of the transcriptional response to inflammatory cytokines whereas SREBF2 knockdown inhibits the transcription and secretion of pro-inflammatory chemokines but amplifies type I interferon response genes. Furthermore, we show that SREBP2 regulates chemokine expression not through enhancement of endogenous cholesterol synthesis or lipoprotein uptake, but partially through direct transcriptional activation. Chromatin immunoprecipitation sequencing (ChIP-seq) of endogenous SREBP2 reveals the SREBP2 bound to the promoter regions of classical response genes as well as two non-classical sterol responsive genes involved in immune modulation, BHLHE40 and KLF6. Overexpression of SREBP2 upregulated both BHLHE40 and KLF6 transcripts independent of inflammatory stress and the transcription of these genes were found to be sensitive to cellular cholesterol levels. Of these two targets, we found that KLF6 was responsible for the amplification of chemokine expression highlighting a tight relationship between cholesterol homeostasis and inflammatory phenotypes in ECs.
2023-08-21 | GSE223094 | GEO
Project description:Dysregulated cholesterol homeostasis promotes tumorigenesis and progression. Therefore, metabolic reprogramming constitutes a new hallmark of cancer. However, until today, only few therapeutic approaches exist to target this pathway due to the often-observed negative feedback induced by agents like statins leading to controversially increased cholesterol synthesis upon inhibition. Sterol regulatory element-binding proteins (SREBPs) are key transcription factors regulating the synthesis of cholesterol and fatty acids. Since SREBP2 is difficult to target, we performed pharmacological inhibition of retinoic acid receptor (RAR)-related orphan receptor gamma (RORγ), which acts upstream of SREBP2 and serves as master regulator of the cholesterol metabolism. This resulted in an inactivated cholesterol-related gene program with significant downregulation of cholesterol biosynthesis. Strikingly, these effects were more pronounced than the effects of fatostatin, a direct SREBP2 inhibitor. Upon RORγ inhibition, RNA sequencing showed strongly increased cholesterol efflux genes leading to leukemic cell death and cell cycle changes in a dose- and time-dependent manner. Combinatorial treatment of t(4;11) cells with the RORγ inhibitor showed additive effects with cytarabine and even strong anti-leukemia synergism with atorvastatin by circumventing the statin-induced feedback. Our results suggest a novel therapeutic strategy to inhibit tumor-specific cholesterol metabolism for the treatment of t(4;11) leukemia.
2024-01-01 | GSE242401 | GEO
Project description:Abstract: The LXR and SREBP transcription factors are key regulators of cellular and systemic cholesterol homeostasis. The molecular mechanisms that integrate these pathways are incompletely understood. Here we show that ligand activation of LXRs in liver not only promotes cholesterol efflux, but also simultaneously inhibits cholesterol biosynthesis. We further identify the long non-coding RNA LeXis as an unexpected mediator of this effect. LeXis is robustly induced in mouse liver in response to western diet feeding or pharmacologic LXR activation. Expression of LeXis in liver inhibits cholesterol biosynthesis and lowers plasma cholesterol levels. Reciprocally, knockdown of LeXis increases hepatic cholesterol content and raises plasma cholesterol levels. LeXis interacts with the heterogeneous nuclear ribonucleoprotein Raly and regulates its binding to cholesterol biosynthetic gene promoters. These studies outline a regulatory role for a non-coding RNA in lipid metabolism and advance our understanding of the mechanisms orchestrating systemic sterol homeostasis. Global RNA expression from primary hepatocytes treated with or without GW3965 were compared by RNA-Seq.
2016-02-10 | E-GEOD-77793 | biostudies-arrayexpress
Project description:The LXR proteins, LXRα and LXRβ, are transcription factors that belong to the nuclear receptor superfamily. LXRs are activated by oxysterols and control the transcription of genes involved in the regulation of cholesterol and fatty acid metabolism. They also mediate several aspects of macrophage biology, including inflammatory responses, cell survival in response to infection and phagocytosis of apoptotic cells. LXRs share a high degree of sequence homology and most of their functions are believed to be performed similarly by LXRα and LXRβ. However, the individual, transcriptional roles of each LXR isoform have not been characterized in detail, in part due to the lack of specific experimental tools that can discriminate between LXRα and LXRβ actions. To identify common and differential transcriptional functions of LXR nuclear receptors in macrophages, we developed a cellular model of stable expression of FLAG-tagged LXRα or LXRβ in LXR-null immortalized murine bone marrow-derived macrophages (parental line published Elife. 2015 Jul 14;4:e08009. doi: 10.7554/eLife.08009). To take a deeper insight into the epigenomic features of LXR nuclear receptors, we performed chromatin immunoprecipitation coupled to next-generation sequencing (ChIP-seq) to identify genome-wide binding locations of LXRα and LXRβ in the presence of a synthetic agonist (GW3965, 1uM). Additionally, we identified genome-wide DNA locations of acetylation mark on lysine 27 of histone H3 (H3K27ac), upon LXR agonist (GW3965, 1uM) and antagonist (GW2033, 1uM) treatment. Collectively, these studies will increase our understanding of common and differential genomic actions of LXRα and LXRβ in cultured murine macrophages.
2017-10-19 | GSE104027 | GEO