Project description:Human genetic studies have pointed to a prominent role for innate immunity and lipid pathways in human immunological and neurodegenerative disorders. Our understanding of the composition and function of immunomodulatory lipid networks in innate immune cells, however, remains incomplete. Here, we show that phospholipase C gamma 2 (PLCγ2 or PLCG2) – mutations in which are associated with autoinflammatory disorders and Alzheimer’s disease – serves as a principal source of diacylglycerol (DAG) pools that are converted into a cascade of bioactive endocannabinoid (eCB) and eicosanoid lipids by DAG lipase (DAGL) and monoacylglycerol lipase (MGLL) enzymes in innate immune cells. We show that this lipid network is tonically stimulated by disease-relevant human mutations in PLCγ2, as well as Fc receptor activation in primary human and mouse macrophages. Genetic disruption of PLCγ2 in mouse microglia suppressed DAGL/MGLL-mediated eCB-eicosanoid crosstalk and also caused widespread transcriptional and proteomic changes, including the reorganization of immune-relevant lipid pathways reflected in reductions in DAGLB and elevations in PLA2G4A. Despite these changes, Plcg2-/- mice showed generally normal pro-inflammatory cytokine responses to lipopolysaccharide treatment, instead displaying a more restricted deficit in microglial activation that included impairments in prostaglandin production and CD68 expression. Our findings enhance the understanding of PLCγ2 function in innate immune cells, delineating a role in crosstalk with endocannabinoid/eicosanoid pathways and modulation of subsets of cellular responses to inflammatory stimuli.
Project description:Human genetic studies have pointed to a prominent role for innate immunity and lipid pathways in human immunological and neurodegenerative disorders. Our understanding of the composition and function of immunomodulatory lipid networks in innate immune cells, however, remains incomplete. Here, we show that phospholipase C gamma 2 (PLCγ2 or PLCG2) – mutations in which are associated with autoinflammatory disorders and Alzheimer’s disease – serves as a principal source of diacylglycerol (DAG) pools that are converted into a cascade of bioactive endocannabinoid (eCB) and eicosanoid lipids by DAG lipase (DAGL) and monoacylglycerol lipase (MGLL) enzymes in innate immune cells. We show that this lipid network is tonically stimulated by disease-relevant human mutations in PLCγ2, as well as Fc receptor activation in primary human and mouse macrophages. Genetic disruption of PLCγ2 in mouse microglia suppressed DAGL/MGLL-mediated eCB-eicosanoid crosstalk and also caused widespread transcriptional and proteomic changes, including the reorganization of immune-relevant lipid pathways reflected in reductions in DAGLB and elevations in PLA2G4A. Despite these changes, Plcg2-/- mice showed generally normal pro-inflammatory cytokine responses to lipopolysaccharide treatment, instead displaying a more restricted deficit in microglial activation that included impairments in prostaglandin production and CD68 expression. Our findings enhance the understanding of PLCγ2 function in innate immune cells, delineating a role in crosstalk with endocannabinoid/eicosanoid pathways and modulation of subsets of cellular responses to inflammatory stimuli.
Project description:We report a transcriptional response in human OECs that encompasses multiple innate immune networks not previously associated with these cells. Major pathways included immune cell trafficking, and differential cytokine production
Project description:We report a transcriptional response in the mouse bladder that encompasses multiple innate immune networks not previously associated with CD14. Major CD14-dependent pathways included immune cell trafficking, differential cytokine production in macrophages, and IL-17 signaling
Project description:Innate immune memory, also called "trained immunity," is a metabolically and epigenetically regulated functional state of myeloid cells. This phenomenon is important for host defense, but also plays a role in various immune-mediated conditions. We found that exogenously administered sphingolipids and inhibition of enzymes involved in sphingolipid metabolism modulate trained immunity. In particular, we found that acid ceramidase, an enzyme that converts ceramide to sphingosine, is a potent regulator of trained immunity. We discovered that acid ceramidase regulates the expression of genes encoding histone-modifying enzymes, resulting in profound changes in the epigenetic landscape. We confirmed our findings by identifying single-nucleotide polymorphisms in the region of ASAH1, the gene encoding acid ceramidase, that are associated with the trained immunity cytokine response. Our findings reveal a novel immunomodulatory effect of sphingolipids, provide new insight into the metabolic regulation of trained immunity, and identify acid ceramidase as a therapeutic target to modulate it.
Project description:The innate immune system provides the first response to pathogen infection and orchestrates the activation of the adaptive immune system. Though a large component of the innate immune response is common to all infections, pathogen-specific innate immune responses have been documented as well. The innate immune response is thought to be especially critical for fighting infection with Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis (TB). While TB can be a deadly disease, only 5-10% of individuals infected with MTB develop active disease, and this inter-individual variation is, at least partly, heritable. Studies of inter-individual variation in the innate immune response to MTB infection may therefore shed light on the genetic basis for variation in susceptibility to TB. Yet, to date, we still do not know which properties of the innate immune response are specific to MTB infection and which represent a general response to pathogen infection. To begin addressing this gap, we infected macrophages with eight different bacterial pathogens, including different MTB strains and related mycobacteria, and studied the transcriptional response to infection. We found that although the gene expression changes were largely consistent across the bacterial infection treatments, we were able to identify a novel subset of genes whose regulation was affected specifically by infection with mycobacteria. Genetic variants that are associated with regulatory differences in these genes should be considered candidate loci for explaining inter-individual susceptibility TB. RNA-seq of monocyte-derived macrophages isolated from 6 healthy European males at 4, 18, and 48 hours post-infection with the following 8 bacteria: Mycobacterium tuberculosis (MTB) H37Rv, Mycobacterium tuberculosis GC1237, MTB GC1237, bacillus Calmette-Guérin (BCG), Mycobacterium smegmatis, Yersinia pseudotuberculosis, Salmonella typhimurium, and Staphylococcus epidermidis. table-s1.txt is a tab-delimited text file that contains the batch-corrected log2 counts per million for each of the 156 samples, as well as the Ensembl gene ID and gene name. BCG = bacillus Calmette-Guérin GC = Mycobacterium tuberculosis GC1237 Rv = Mycobacterium tuberculosis (MTB) H37Rv Rv+ = heat-inactivated MTB H37Rv Salm = Salmonella typhimurium Smeg = Mycobacterium smegmatis Staph = Staphylococcus epidermidis Yers = Yersinia pseudotuberculosis
Project description:It is urgent and important to understand the relationship of the widespread severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2) with host immune response and study the underlying molecular mechanism. RNA modification landscape of SARS-CoV-2 and its functional relevance to host cell innate immune response remain unknown. N6-methylation of adenosine (m6A) in RNA regulates many physiological and disease processes. Here, we investigated m6A modification of SARS-CoV-2 gene in regulating host cell innate immune response. Our data showed that SARS-CoV-2 virus has m6A modification enriched in 3' region of the viral genome. We also found that host cell m6A methyltransferase METTL3 depletion reduced viral load in infected cells, decreased m6A levels in SARS-CoV-2 and host genes, and m6A reduction in viral RNA increased RIG-1 binding and subsequently enhanced downstream innate immune signaling pathway and inflammatory gene expression. METTL3 expression is reduced and inflammatory genes are induced in severe COVID-19 patients. These findings will aid to understand the COVID-19 pathogenesis and help in designing future studies of regulating innate immunity for COVID-19 treatment.
Project description:PAF1 knockout and ncgRNA control cells were treated with multiple innate immune stimuli for 3 hours to mimic various microbial stresses.