ABSTRACT: Immune-Responsive Gene 1 expression in myeloid cells prevents neutrophil mediated immunopathology during Mycobacterium tuberculosis infection, in vitro neutrophils data
Project description:Immune-Responsive Gene 1 expression in myeloid cells prevents neutrophil mediated immunopathology during Mycobacterium tuberculosis infection, in vivo neutrophil data
Project description:Immune-Responsive Gene 1 (Irg1) is a mitochondrial enzyme that produces itaconate under inflammatory conditions principally in cells of myeloid lineage. Cell culture studies suggest that itaconate regulates inflammation through inhibitory effects on cytokine and reactive oxygen species production. To evaluate the functions of Irg1 in vivo, we challenged wild-type (WT) and Irg1 KO mice with Mycobacterium tuberculosis (Mtb) and monitored disease progression. Irg1 KO but not WT mice succumbed rapidly to Mtb, and mortality was associated with increased infection, inflammation, and pathology. Infection of LysM-Cre Irg1 flox, MPR8-Cre Irg1 flox, and CD11c-Cre Irg1 flox conditional knockout mice along with neutrophil depletion experiments revealed a role for Irg1 in alveolar macrophages and LysM+ myeloid cells in preventing neutrophil-mediated immunopathology and disease. RNA-seq analyses suggest that Irg1 and its production of itaconate temper Mtb-induced inflammatory responses in myeloid cells at the transcriptional level. Thus, Irg1 modulates inflammation to curtail Mtb-induced lung disease.
Project description:Immune-Responsive Gene 1 (Irg1) is a mitochondrial enzyme that produces itaconate under inflammatory conditions principally in cells of myeloid lineage. Cell culture studies suggest that itaconate regulates inflammation through inhibitory effects on cytokine and reactive oxygen species production. To evaluate the functions of Irg1 in vivo, we challenged wild-type (WT) and Irg1 KO mice with Mycobacterium tuberculosis (Mtb) and monitored disease progression. Irg1 KO but not WT mice succumbed rapidly to Mtb, and mortality was associated with increased infection, inflammation, and pathology. Infection of LysM-Cre Irg1 flox, MPR8-Cre Irg1 flox, and CD11c-Cre Irg1 flox conditional knockout mice along with neutrophil depletion experiments revealed a role for Irg1 in alveolar macrophages and LysM+ myeloid cells in preventing neutrophil-mediated immunopathology and disease. RNA-seq analyses suggest that Irg1 and its production of itaconate temper Mtb-induced inflammatory responses in myeloid cells at the transcriptional level. Thus, Irg1 modulates inflammation to curtail Mtb-induced lung disease.
Project description:Immune-Responsive Gene 1 (Irg1) is a mitochondrial enzyme that produces itaconate under inflammatory conditions principally in cells of myeloid lineage. Cell culture studies suggest that itaconate regulates inflammation through inhibitory effects on cytokine and reactive oxygen species production. To evaluate the functions of Irg1 in vivo, we challenged wild-type (WT) and Irg1-/- mice with Mycobacterium tuberculosis (Mtb) and monitored disease progression. Irg1-/- but not WT mice succumbed rapidly to Mtb, and mortality was associated with increased infection, inflammation, and pathology. Infection of LysM-Cre Irg1fl/fl, MPR8-Cre Irg1fl/fl, and CD11c-Cre Irg1fl/fl conditional knockout mice along with neutrophil depletion experiments revealed a role for Irg1 in alveolar macrophages and LysM+ myeloid cells in preventing neutrophil-mediated immunopathology and disease. RNA-seq analyses suggest that Irg1 and its production of itaconate temper Mtb-induced inflammatory responses in myeloid cells at the transcriptional level. Thus, Irg1 modulates inflammation to curtail Mtb-induced lung disease.
Project description:Mycobacterium tuberculosis infection of mice elicits a robust neutrophil influx that associates with poor outcome from tuberculosis (TB). However, the mechanism by which neutrophils contribute to TB disease pathogenesis is not understood. To gain insights into the pathological functions of neutrophils, the current study performs bulk mRNA sequencing from the neutrophils isolated from lung, spleen and bone marrow of resistant (C57BL/6) and susceptible (IL-1R1 KO) mice at 28 days post M.tuberculosis HN878 infection.
Project description:The immune response to a chronic viral infection is uniquely tailored to balance viral control and immunopathology. The role of myeloid cells in shaping the response to chronic viral infection, however, is poorly understood. Single-cell RNA sequencing of myeloid cells during acute and chronic LCMV infection was performed to address this question. We discovered a cluster of suppressive neutrophils that is enriched in chronic versus acute infection. Furthermore, suppressive neutrophils highly expressed the gene encoding PIM1, a kinase known to promote mitochondrial fitness and cell survival. Pharmacological inhibition of PIM1 selectively diminished suppressive neutrophil-mediated immunosuppression without affecting the function of monocytic myeloid derived suppressor cells (M-MDSCs). Decreased accumulation of suppressive neutrophils led to increased CD8 T cell function and viral control. Mechanistically, PIM kinase activity was required for maintaining fused mitochondrial networks in suppressive neutrophils, but not in M-MDSCs, and loss of PIM kinase function caused increased apoptosis of suppressive neutrophils.
Project description:The mechanisms that govern the neutrophil response to Mycobacterium tuberculosis remain poorly understood. In this study we utilize an innovative binary approach in zebrafish to perform in depth profiling of the initial response of neutrophils to Mycobacterium marinum, by in vivo biotinylation of neutrophil nuclei and subsequent rapid isolation directly from the in vivo context. RNA-seq and differential expression analysis of the neutrophil nuclear transcriptome reveals a significant upregulation in both damage-sensing and effector components of the inflammasome, including caspase b, wu:fb15h11 (NLRC3 ortholog) and il1β. Crispr/Cas9-mediated knockdown of caspase b, which mediates its effects by the proteolytic processing of il1β, results in increased bacterial burden and less infiltration of macrophages to sites of mycobacterium infection, thus impairing granuloma development. We also show that a number of immediate early response genes (IEGs) are responsible for orchestrating the initial response to mycobacterial infection in neutrophils. Further perturbation of the IEGs revealed egr3 as a key transcription factor regulating il1β transcription.
Project description:BACKGROUND: Neutrophils are phagocytic innate immune cells that play essential roles in host defence, but are also implicated in inflammatory diseases such as rheumatoid arthritis (RA) where they contribute to systemic inflammation and joint damage. Transcriptomic analysis of neutrophils has revealed significant changes in gene expression in neutrophils activated in vitro by cytokines and in vivo during inflammation in RA. However, there are no reports on the global metabolomic changes that occur during neutrophil activation. The aim of this study was to establish protocols for the study changes in the metabolome of human neutrophils using 1H NMR spectroscopy.
