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McQueen CF, Groves JT. Toxicity of the iron siderophore mycobactin J in mouse macrophages: Evidence for a hypoxia response. J Inorg Biochem 2021; 227:111669. [PMID: 34864292 DOI: 10.1016/j.jinorgbio.2021.111669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/07/2021] [Accepted: 11/07/2021] [Indexed: 11/25/2022]
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis, is an obligate intracellular pathogen that lives within the phagosome of macrophages. Here we demonstrate that the siderophore mycobactin J, produced by the closely related intracellular pathogen Mycobacterium paratuberculosis, is toxic to murine macrophage cells. Its median lethal dose, 10 μM, is lower than that of the iron chelators desferrioxamine B and TrenCAM, an enterobactin analog. To determine the source of this toxicity, we conducted microarray, ELISA, and metabolite profiling experiments. The primary response is hypoxia-like, which implies iron starvation as the underlying cause of the toxicity. This observation is consistent with our recent finding that mycobactin J is a stronger iron chelator than had been inferred from previous studies. Mycobactin J is known to partition into cell membranes and hydrophobic organelles indicating that enhanced membrane penetration is also a likely factor. Thus, mycobactin J is shown to be toxic, eliciting a hypoxia-like response under physiological conditions.
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Affiliation(s)
| | - John T Groves
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
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Kiernan EA, Ewald AC, Ouellette JN, Wang T, Agbeh A, Knutson AO, Roopra AS, Watters JJ. Prior Hypoxia Exposure Enhances Murine Microglial Inflammatory Gene Expression in vitro Without Concomitant H3K4me3 Enrichment. Front Cell Neurosci 2020; 14:535549. [PMID: 33132843 PMCID: PMC7575929 DOI: 10.3389/fncel.2020.535549] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 09/09/2020] [Indexed: 12/19/2022] Open
Abstract
Hypoxia (Hx) is a component of multiple disorders, including stroke and sleep-disordered breathing, which often precede or are comorbid with neurodegenerative diseases. However, little is known about how hypoxia affects the ability of microglia, resident CNS macrophages, to respond to subsequent inflammatory challenges that are often present during neurodegenerative processes. We, therefore, tested the hypothesis that hypoxia would enhance or "prime" microglial pro-inflammatory gene expression in response to a later inflammatory challenge without programmatically increasing basal levels of pro-inflammatory cytokine expression. To test this, we pre-exposed immortalized N9 and primary microglia to hypoxia (1% O2) for 16 h and then challenged them with pro-inflammatory lipopolysaccharide (LPS) either immediately or 3-6 days following hypoxic exposure. We used RNA sequencing coupled with chromatin immunoprecipitation sequencing to analyze primed microglial inflammatory gene expression and modifications to histone H3 lysine 4 trimethylation (H3K4me3) at the promoters of primed genes. We found that microglia exhibited enhanced responses to LPS 3 days and 6 days post-hypoxia. Surprisingly, however, the majority of primed genes were not enriched for H3K4me3 acutely following hypoxia exposure. Using the bioinformatics tool MAGICTRICKS and reversible pharmacological inhibition, we found that primed genes required the transcriptional activities of NF-κB. These findings provide evidence that hypoxia pre-exposure could lead to persistent and aberrant inflammatory responses in the context of CNS disorders.
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Affiliation(s)
- Elizabeth A. Kiernan
- Department of Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, United States
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Andrea C. Ewald
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Jonathan N. Ouellette
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Tao Wang
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Abiye Agbeh
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, United States
| | - Andrew O. Knutson
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, United States
- Molecular and Environmental Toxicology Training Program, University of Wisconsin-Madison, Madison, WI, United States
| | - Avtar S. Roopra
- Department of Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, United States
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, United States
| | - Jyoti J. Watters
- Department of Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, United States
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, United States
- Molecular and Environmental Toxicology Training Program, University of Wisconsin-Madison, Madison, WI, United States
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Tanner R, Satti I, Harris SA, O'Shea MK, Cizmeci D, O'Connor D, Chomka A, Matsumiya M, Wittenberg R, Minassian AM, Meyer J, Fletcher HA, McShane H. Tools for Assessing the Protective Efficacy of TB Vaccines in Humans: in vitro Mycobacterial Growth Inhibition Predicts Outcome of in vivo Mycobacterial Infection. Front Immunol 2020; 10:2983. [PMID: 31998295 PMCID: PMC6968127 DOI: 10.3389/fimmu.2019.02983] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/05/2019] [Indexed: 12/16/2022] Open
Abstract
Tuberculosis (TB) remains a leading global cause of morbidity and mortality and an effective new vaccine is urgently needed. A major barrier to the rational development of novel TB vaccines is the lack of a validated immune correlate or biomarker of protection. Mycobacterial Growth Inhibition Assays (MGIAs) provide an unbiased measure of ability to control mycobacterial growth in vitro, and may represent a functional correlate of protection. However, the biological relevance of any potential correlate can only be assessed by determining the association with in vivo protection from either a controlled mycobacterial infection or natural development of TB disease. Our data demonstrate that the direct MGIA using peripheral blood mononuclear cells (PBMC) is measuring a biologically relevant response that correlates with protection from in vivo human BCG infection across two independent cohorts. This is the first report of an MGIA correlating with in vivo protection in the species-of-interest, humans, and furthermore on a per-individual as well as per-group basis. Control of mycobacterial growth in the MGIA is associated with a range of immune parameters measured post-BCG infection in vivo including the IFN-γ ELISpot response, frequency of PPD-specific IFN-γ or TNF-α producing CD4+ T cells and frequency of specific sub-populations of polyfunctional CD4+ T cells. Distinct transcriptomic profiles are associated with good vs. poor mycobacterial control in the MGIA, with good controllers showing enrichment for gene sets associated with antigen processing/presentation and the IL-23 pathway, and poor controllers showing enrichment for hypoxia-related pathways. This study represents an important step toward biologically validating the direct PBMC MGIA for use in TB vaccine development and furthermore demonstrates the utility of this assay in determining relevant immune mechanisms and pathways of protection.
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Affiliation(s)
- Rachel Tanner
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Iman Satti
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Stephanie A. Harris
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Matthew K. O'Shea
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, The University of Birmingham, Birmingham, United Kingdom
| | - Deniz Cizmeci
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Daniel O'Connor
- Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Agnieszka Chomka
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Magali Matsumiya
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Rachel Wittenberg
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Angela M. Minassian
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Joel Meyer
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Helen A. Fletcher
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Helen McShane
- The Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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