Harnessing the Pre-metastatic Niche Macrophages through the Induction of Trained Immunity to control Metastasis.
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ABSTRACT: We demonstrate that a natural compund B-Glucan (WGP) can induce training of macrophages by upregulating the Sphingolipid biosynthesis pathway and more specifically, the accumulation of S1P, resulting in mitochondrial fission in macrophages. These trained macrophages upon re-stimulation with tumor cells or tumor-derived factors showed increased responsiveness by increased pro-inflammatory cytokine production, increased phagocytosis and cytotoxicity. In vivo training of mice with WGP resulted in the training of Lung Interstitial macrophages and controlled the metastasis to the lungs.
Project description:Venous thromboembolism is common in individuals with chronic inflammatory diseases, but the pathogenic basis for this increased thrombotic risk remains poorly understood. Myeloid cell ‘trained immunity’ describes persistent innate immune cell memory arising from prior exposure to an inflammatory stimulus, leading to an enhanced immune response to subsequent unrelated stimuli. We identify enhanced myeloid cell prothrombotic activity as a novel maladaptive consequence of trained immunity. LPS stimulation of murine bone marrow-derived macrophages trained previously with either β-glucan or free haem exhibited significantly enhanced procoagulant and antifibrinolytic gene expression and activity compared to macrophages stimulated with LPS alone. The β-glucan training-mediated increase in activated myeloid cell procoagulant activity was mediated by enhanced acid sphingomyelinase-mediated tissue factor (TF) functional decryption. Furthermore, pre-treatment with methyltransferase and acetyltransferase inhibitors to erase epigenetic marks associated with innate immune memory diminished trained macrophage TF gene expression in β-glucan-trained macrophages. Functional analysis of splenic monocytes isolated from β-glucan-trained mice revealed enhanced procoagulant activity up to 4 weeks after β-glucan administration compared to monocytes from control mice over the same time period. Remarkably, monocyte procoagulant activity increased proportionately with time since β-glucan administration, before plateauing at 4 weeks. Furthermore, haematopoietic progenitor cells and bone marrow interstitial fluid isolated from β-glucan-trained mice possessed enhanced procoagulant activity compared to control mice. Trained immunity and associated metabolic perturbations may therefore represent novel therapeutic vulnerabilities in immunothrombotic disease development, opening new avenues for targeted intervention.
Project description:Bone-marrow macrophages polarized to M2 phenotype are immunosuppressive. Interestingly, treatment with whole-glucan particles converts M2 macrophages to M1 phenotype with an anti-tumor phenotype. In this study, the effect of WGP treatment for 6 hours on the gene expression of M2 macrophages was assessed.
Project description:Fungal beta-glucans are major drivers of trained immunity which increases long-term protection against secondary infections. Heterogeneity in beta-glucan source, structure and solubility alters interaction with the phagocytic receptor Dectin-1 and could impact strategies to improve trained immunity in humans. Using a panel of diverse beta-glucans we describe the ability of a specific yeast-derived whole-glucan particle (WGP) to reprogramme metabolism and thereby drive trained immunity in human monocyte-derived macrophages in-vitro and mice bone-marrow in-vivo. Presentation of pure, non-soluble, non-aggregated WGPs led to the formation of the Dectin-1 phagocytic synapse with subsequent lysosomal mTOR activation, metabolic reprogramming and epigenetic rewiring. Intraperitoneal or oral administration of WGP drove bone-marrow myelopoiesis and improved mature macrophage responses, pointing to therapeutic and food-based strategies to drive immune training. Thus, the investment of a cell in a trained response relies on specific recognition of beta-glucans presented on intact microbial particles through stimulation of the Dectin-1 phagocytic response.
Project description:In animals, maternal diet and environment can influence the health of offspring. Whether and how maternal dietary choice impacts the nervous system across multiple generations is not well understood. Here, we show that feeding Caenorhabditis elegans with ursolic acid (UA), a natural plant product, reduces adult-onset neurodegeneration intergenerationally. UA provides neuroprotection by enhancing maternal provisioning of sphingosine-1-phosphate (S1P) - a bioactive sphingolipid. Intestine-to-oocyte S1P transfer is required for intergenerational neuroprotection and is dependent on the RME-2 lipoprotein yolk receptor. S1P acts intergenerationally by upregulating transcription of the acid ceramidase-1 (asah-1) gene in the intestine. Spatially regulating sphingolipid metabolism is critical as inappropriate asah-1 expression in neurons causes developmental axon outgrowth defects. Our results show that sphingolipid homeostasis impacts the development and intergenerational health of the nervous system. The ability of specific lipid metabolites to act as messengers between generations may have broad implications for dietary choice during reproduction.
Project description:The cleavage of sphingoid base phosphates by sphingosine-1-phosphate (S1P) lyase to produce phosphoethanolamine and a fatty aldehyde is the final degradative step in the sphingolipid metabolic pathway. We have studied mice with an inactive S1P lyase gene and have found that, in addition to the expected increase of sphingoid base phosphates, other sphingolipids (including sphingosine, ceramide, and sphingomyelin) were substantially elevated in the serum and /or liver of these mice. This latter increase is consistent with a reutilization of the sphingosine backbone for sphingolipid synthesis due to its inability to exit the sphingolipid metabolic pathway. Furthermore, the S1P lyase deficiency resulted in changes in the levels of serum and liver lipids not directly within the sphingolipid pathway, including phospholipids, triacyglycerol, diacylglycerol, and cholesterol. Even though lipids in serum and lipid storage were elevated in liver, adiposity was reduced in the S1P lyase-deficient mice. Microarray analysis of lipid metabolism genes in liver showed that the S1P lyase deficiency caused widespread changes in their expression pattern. These results demonstrate that S1P lyase is a key regulator of the levels of multiple sphingolipid substrates and reveal functional links between the sphingolipid metabolic pathway and other lipid metabolic pathways that may be mediated by shared lipid substrates and changes in gene expression programs. The disturbance of lipid homeostasis by altered sphingolipid levels may be relevant to metabolic diseases. Experiment Overall Design: RNA samples from liver for three sphingosine-1-phosphate lyase knock-out and three WT mice.
Project description:Sphingosine-1-phosphate (S1P) is a sphingolipid metabolite that regulates basic cell functions through metabolic and signaling pathways. Intracellular metabolism of S1P is controlled, in part, by two homologous S1P phosphatases, 1 and 2, which are encoded by Sgpp1 and Sgpp2, respectively. S1P phosphatase activity is needed for efficient recycling of sphingosine into the sphingolipid synthesis pathway. S1P phosphatase 1 is important for skin homeostasis, but little is known about the functional role of S1P phosphatase 2. To identify the functions of S1P phosphatase 2 in vivo, we studied mice with the Sgpp2 gene deleted. In contrast to Sgpp1-/- mice, Sgpp2-/- mice had normal skin and were viable into adulthood. Unexpectedly, WT mice expressed Sgpp2 mRNA at high levels in pancreatic islets when compared with other tissues. Sgpp2-/- mice had normal blood insulin levels and pancreatic islet size; however, Sgpp2-/- mice treated with a high-fat diet (HFD) had significantly lower blood insulin levels and smaller pancreatic islets compared with WT mice. The smaller islets in the HFD-treated Sgpp2-/- mice had a significantly lower adaptive B-cell proliferation rate in response to the diet compared with HFD-treated WT mice. Importantly, B-cells from Sgpp2-/- mice fed a normal diet showed significantly increased expression of proteins characteristic of the endoplasmic reticulum (ER) stress response compared with B-cells from WT mice. Our results suggest that Sgpp2 deletion causes B-cell ER stress, which is a known cause of B-cell dysfunction, and reveal a novel juncture in the sphingolipid recycling pathway that could impact the development of diabetes. Three replications of Mouse (WT vs KO) that were treated with with Normal and HFD foods.
Project description:Following treatment with WGP, we have observed an influx of immune cell populations into the pancreas over time. These cells have increased anti-tumor activities, which results in protection against pancreatic cancer growth. The study objective is to better understand the cell types involved in this process and the temporal nature of this influx. It is known that the immune influx peaks at day 7, so we are interested in the changes in the immune populations of the pancreas 3 days and 7 days following WGP treatment. To gain a more in depth analysis of the cell populations present in the pancreas after WGP treatment, a single cell RNA sequencing (scRNA-Seq) was performed on sorted CD45+ cells from PBS treated mice and mice treated with WGP 3 and 7 days prior.
Project description:The cleavage of sphingoid base phosphates by sphingosine-1-phosphate (S1P) lyase to produce phosphoethanolamine and a fatty aldehyde is the final degradative step in the sphingolipid metabolic pathway. We have studied mice with an inactive S1P lyase gene and have found that, in addition to the expected increase of sphingoid base phosphates, other sphingolipids (including sphingosine, ceramide, and sphingomyelin) were substantially elevated in the serum and /or liver of these mice. This latter increase is consistent with a reutilization of the sphingosine backbone for sphingolipid synthesis due to its inability to exit the sphingolipid metabolic pathway. Furthermore, the S1P lyase deficiency resulted in changes in the levels of serum and liver lipids not directly within the sphingolipid pathway, including phospholipids, triacyglycerol, diacylglycerol, and cholesterol. Even though lipids in serum and lipid storage were elevated in liver, adiposity was reduced in the S1P lyase-deficient mice. Microarray analysis of lipid metabolism genes in liver showed that the S1P lyase deficiency caused widespread changes in their expression pattern. These results demonstrate that S1P lyase is a key regulator of the levels of multiple sphingolipid substrates and reveal functional links between the sphingolipid metabolic pathway and other lipid metabolic pathways that may be mediated by shared lipid substrates and changes in gene expression programs. The disturbance of lipid homeostasis by altered sphingolipid levels may be relevant to metabolic diseases.
Project description:To investigate the effect of the sphingolipid S1P secreted by melanoma cells on epidermal keratinocytes, we treated human primary keratinocytes with exogenous S1P.
Project description:Trained immunity is a form of innate immune memory characterized by epigenetic and metabolic reprogramming in response to specific stimuli. This rewiring can result in increased cytokine and effector responses to pathogenic challenge, providing non-specific protection against disease. It may also improve immune responses to established immunotherapeutics and vaccines. Despite the promise of training for next-generation therapeutic design, most current understanding and experimentation is conducted with complex and heterogeneous biologically derived molecules, such as β-glucan or the BCG vaccine. This limited collection of training compounds also limits study of the genes most involved in training responses as each molecule has both training and non-training effects. Small molecules with tunable pharmacokinetics and delivery modalities would both assist in the study of trained immunity and its future application for therapeutics. To identify novel small molecule inducers of trained immunity, we screened a library of 2000 drugs and drug-like compounds. Identification of well-defined compounds can improve our understanding of innate immune memory and broaden the scope of its clinical applications. We identified over 2 dozen small molecules in several chemical classes, including the traditionally immunosuppressive glucocorticoids, that induce a training phenotype in the absence of initial immune activation – a current limitation of reported inducers of training. We chose 7 of these top candidates to characterize and establish training activity in vivo. In this work, we expand the number of compounds known to induce trained immunity, creating new avenues for the study and application of innate immune training.