PI3K signaling promotes formation of lipid-laden foamy macrophages at the spinal cord injury site
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE237511 | GEO | 2023/12/05
REPOSITORIES: GEO
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2018-08-30 | GSE116239 | GEO
Project description:Formation of foam cell macrophages (FCMs), which sequester extracellular modified lipids, is a key event in atherosclerosis. How lipid loading affects macrophage phenotype is controversial, with evidence suggesting either pro- or anti-inflammatory consequences. To investigate this further, we compared the transcriptomes of foamy and non-foamy macrophages (NFMs) that accumulate in the subcutaneous granulomas of fed-fat ApoE null mice and normal chow fed wild-type mice in vivo. Consistent with previous studies, LXR/RXR pathway genes were significantly over-represented among the genes up-regulated in foam cell macrophages. Unexpectedly, the hepatic fibrosis pathway, associated with platelet derived growth factor and transforming growth factor-? action, was also over-represented. Several collagen polypeptides and proteoglycan core proteins as well as connective tissue growth factor and fibrosis-related FOS and JUN transcription factors were up-regulated in foam cell macrophages. Increased expression of several of these genes was confirmed at the protein level in foam cell macrophages from subcutaneous granulomas and in atherosclerotic plaques. Moreover, phosphorylation and nuclear translocation of SMAD2, which is downstream of several transforming growth factor-? family members, was also detected in foam cell macrophages. We conclude that foam cell formation in vivo leads to a pro-fibrotic macrophage phenotype, which could contribute to plaque stability, especially in early lesions that have few vascular smooth muscle cells. Samples (n=4/group): Foam cell macrophages (FCM) isolated from inflammatory sponges placed in ApoE null mice fed a high-fat diet (n=4), non-foamy macrophages (NFM) isolated from inflammatory sponges placed in control mice fed a normal diet (n=4).
2015-07-23 | E-GEOD-70126 | biostudies-arrayexpress
Project description:The class 3 phosphoinositide 3-kinase (PI3K) is required for the lysosomal degradation by autophagy and vesicular trafficking, assuring adaptation to energy shortages. Mitochondrial lipid catabolism is another important energy source. Autophagy and mitochondrial metabolism are transcriptionally controlled by nutrient sensing nuclear receptors. However, it is not known whether the class 3 PI3K contributes to this regulation. Here we show that hepatocyte-specific inactivation of Vps15, the essential regulatory subunit of the class 3 PI3K, results in mitochondrial depletion and a failure to oxidize fatty acids. Mechanistically, the transcriptional activity of Peroxisome Proliferator Activated Receptor alpha (PPARα), a nuclear receptor that orchestrates fatty acid catabolism, is blunted in Vps15-deficient livers. We find PPARα transcriptional repressors Histone Deacetylase 3 (Hdac3) and Nuclear receptor co-repressor 1 (NCoR1) accumulated in Vps15-deficient livers due to defective autophagic flux. Pharmacologic activation of PPARα with a synthetic ligand, re-expression of its co-activator Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha (PGC-1α) or inhibition of Hdac3 restored mitochondrial biogenesis and lipid oxidation in Vps15-deficient hepatocytes. These findings reveal a role for the class 3 PI3K and autophagy in transcriptional coordination of mitochondrial metabolism.
2020-02-06 | E-MTAB-7685 | biostudies-arrayexpress
Project description:NLRX1 is a mitochondrial-associated NOD-like receptor that modulates antiviral immunity, cellular stress, autophagy, and reactive oxygen species (ROS) production. The role of NLRX1 in inflammatory bowel disease (IBD) remains largely unknown. This study aimed to characterize NLRX1-mediated mechanisms of protection from IBD. We investigated the ability of NLRX1 to modulate global colonic gene expression, gut pathology, inflammation and immunity by using loss-of-function approaches in dextran sodiu sulfate (DSS) and CD4+CD45RBhigh transfer colitis models. Colons, spleens, and mesenteric lymph nodes (MLN) were excised for characterizing immune cell subsets, histological analyses, cytokine, RNA sequencing analyses, and autophagy expression, NF-κB activity, and ROS production. The loss of NLRX1 increased severity of disease and colonic histopathology in both models of IBD. Colons of NLRX1-/- mice had significantly increased epithelial ulceration and leukocyte infiltration mostly in the form of neutrophils, lymphocytes, and macrophages in the DSS model, while recipients of NLRX1-/- CD4+ T cells had increased leukocytic infiltration, proliferation, fibrosis, and crypt abscessation in both colon and ileum. The loss of NLRX1 increased numbers of effector T helper (Th1), Th17, and regulatory T cells (Treg) cells in the colonic mucosa and spleen, increased colonic NF-κB activity, upregulation of IL-17, IFNγ and TNF-α production, and increased ROS production. Global transcriptomic analyses demonstrates that NLRX1 regulates immunity and lipid metabolism pathways. NLRX1 ameliorates intestinal pathology during IBD by acting as an internal thermostat that modulates the balance of effector versus regulatory CD4+ T cell responses, and suppressing colonic NF-κB activity, inflammatory cytokine expression, lipid metabolism gene expression, ROS production and autophagy.
2018-03-07 | GSE68419 | GEO
Project description:Obesity leads to a state of chronic low-grade inflammation that features accumulation of lipid-laden macrophages in adipose tissue. Here, we determined the role of macrophage lipid droplet accumulation in the development of obesity-induced adipose tissue inflammation, using mice with myeloid-specific deficiency of the lipid-inducible HILPDA protein. HILPDA deficiency markedly reduced intracellular lipid levels and accumulation of fluorescently-labeled fatty acids. Decreased lipid storage in HILPDA-deficient macrophages could be rescued by inhibition of adipose triglyceride lipase (ATGL) and was associated with increased oxidative metabolism. In diet-induced obese mice, HILPDA deficiency did not alter inflammatory and metabolic parameters, despite markedly reducing lipid accumulation in macrophages. Overall, we find that HILPDA is a lipid-induced physiological inhibitor of ATGL-mediated lipolysis in macrophages that uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation. Our data question the contribution of lipid droplet accumulation in adipose tissue macrophages in obesity-induced inflammation and metabolic dysregulation.
2019-12-19 | GSE142294 | GEO
Project description:Obesity leads to a state of chronic low-grade inflammation that features accumulation of lipid-laden macrophages in adipose tissue. Here, we determined the role of macrophage lipid droplet accumulation in the development of obesity-induced adipose tissue inflammation, using mice with myeloid-specific deficiency of the lipid-inducible HILPDA protein. HILPDA deficiency markedly reduced intracellular lipid levels and accumulation of fluorescently-labeled fatty acids. Decreased lipid storage in HILPDA-deficient macrophages could be rescued by inhibition of adipose triglyceride lipase (ATGL) and was associated with increased oxidative metabolism. In diet-induced obese mice, HILPDA deficiency did not alter inflammatory and metabolic parameters, despite markedly reducing lipid accumulation in macrophages. Overall, we find that HILPDA is a lipid-induced physiological inhibitor of ATGL-mediated lipolysis in macrophages that uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation. Our data question the contribution of lipid droplet accumulation in adipose tissue macrophages in obesity-induced inflammation and metabolic dysregulation.
2019-12-19 | GSE142295 | GEO
Project description:Purpose: The phosphoinositide 3-kinase (PI3K) pathway is fundamental for cell proliferation and survival and is frequently altered and activated in neoplasia, including carcinomas of the lung. In this study we investigated the potential of targeting the catalytic class IA PI3K isoforms in small cell lung cancer (SCLC), which is the most aggressive of all lung cancer types. Experimental Design: The expression of PI3K isoforms in patient specimens was analyzed. The effects on SCLC cell survival and downstream signaling were determined following PI3K isoform inhibition by selective inhibitors or down-regulation by small interfering RNA. Results: Over-expression of the PI3K isoforms p110 -alpha and p110-alpha was shown by immunohistochemistry in primary SCLC tissue samples. Targeting the PI3K p110 -alpha with RNA interference (RNAi) or selective pharmacological inhibitors resulted in strongly affected cell proliferation of SCLC cells in vitro and in vivo, while targeting p110-alph was less effective. Inhibition of p110 -alpha also resulted in increased apoptosis and autophagy, which was accompanied by decreased phosphorylation of Akt and components of the mammalian target of rapamycin (mTOR) pathway, such as the ribosomal S6 protein, and the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). A DNA microarray analysis revealed that p110-alpha inhibition profoundly affected the balance of pro- and anti-apoptotic Bcl-2 family proteins. Finally, p110 -alpha inhibition led to impaired SCLC tumor formation and vascularization in vivo. Conclusion: Together our data demonstrate the key involvement of the PI3K isoform p110 -alpha in multiple tumor-promoting processes in SCLC. 3 control samples, 3 samples for two treaments
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2022-02-01 | GSE163471 | GEO
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism. conditional activation of pkb and pi3k were followed in a timeseries. Each timepoint consists of 4 independent replicates, labeled with either cy3 or cy5 and put on array against time0.
2012-07-21 | E-GEOD-35701 | biostudies-arrayexpress
Project description:The inflammatory response after spinal cord injury (SCI) is an important contributor to secondary damage. Infiltrating macrophages can acquire a spectrum of activation states, however, the microenvironment at the SCI site favors macrophage polarization into a pro-inflammatory phenotype, which is one of the reasons why macrophage transplantation has failed. In this study, we investigated the therapeutic potential of the macrophage secretome for SCI recovery. We investigated the effect of the secretome in vitro using peripheral and CNS-derived neurons and human neural stem cells. Moreover, we perform a pre-clinical trial using a SCI compression mice model and analyzed the recovery of motor, sensory and autonomic functions. Instead of transplanting the cells, we injected the paracrine factors and extracellular vesicles that they secrete, avoiding the loss of the phenotype of the transplanted cells due to local environmental cues. We demonstrated that different macrophage phenotypes have a distinct effect on neuronal growth and survival, namely, the alternative activation with IL-10 and TGF-β1 (M(IL-10+TGF-β1)) promotes significant axonal regeneration. We also observed that systemic injection of soluble factors and extracellular vesicles derived from M(IL-10+TGF-β1) macrophages promotes significant functional recovery after compressive SCI and leads to higher survival of spinal cord neurons. Additionally, the M(IL-10+TGF-β1) secretome supported the recovery of bladder function and decreased microglial activation, astrogliosis and fibrotic scar in the spinal cord. Proteomic analysis of the M(IL-10+TGF-β1)-derived secretome identified clusters of proteins involved in axon extension, dendritic spine maintenance, cell polarity establishment, and regulation of astrocytic activation. Overall, our results demonstrated that macrophages-derived soluble factors and extracellular vesicles might be a promising therapy for SCI with possible clinical applications.
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