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Kopping EJ, Benziger PT, Thanassi DG. TolC and EmrA1 contribute to Francisella novicida multidrug resistance and modulation of host cell death. J Bacteriol 2024:e0024624. [PMID: 39194223 DOI: 10.1128/jb.00246-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Accepted: 07/29/2024] [Indexed: 08/29/2024] Open
Abstract
Francisella spp. are Gram-negative, facultative intracellular pathogens. Francisella tularensis causes the human disease tularemia and is considered a biological threat agent due to its high infectivity and virulence. A central aspect of Francisella virulence is its ability to dampen host immune responses. We previously identified the outer membrane channel (OMC) protein TolC as a critical F. tularensis virulence factor required for suppression of apoptotic and proinflammatory responses during macrophage infection. TolC functions as part of multidrug efflux systems and the type I secretion pathway that exports bacterial effector proteins. In these systems, TolC forms tripartite complexes together with an inner membrane transporter and periplasmic membrane fusion protein (MFP). To advance understanding of TolC function in Francisella, we analyzed OMC and MFP homologs in Francisella novicida, a widely used model species that causes a tularemia-like disease in mice. In agreement with the previous F. tularensis studies, all three OMCs present in F. novicida contributed to multidrug resistance, but only TolC was important for suppressing macrophage cell death. In addition, we identified the EmrA1 MFP as important for resisting antimicrobial compounds and dampening host cell death. In contrast to results obtained with F. tularensis, the cell death triggered during infection with the F. novicida tolC and emrA1 mutants was dominated by pyroptosis rather than apoptosis. These data expand our understanding of TolC function in Francisella and underscore both conserved and differential aspects of F. novicida and F. tularensis. IMPORTANCE Francisella tularensis is a Gram-negative intracellular bacterial pathogen and causative agent of tularemia. We previously identified the outer membrane channel protein TolC as contributing to antimicrobial resistance and subversion of host responses by F. tularensis. To advance understanding of TolC function in Francisella and to identify components that might work together with TolC, we took advantage of a transposon mutant library in F. novicida, a model species that causes a tularemia-like disease in mice. Our findings identify TolC and the membrane fusion protein EmrA1 as important for both antimicrobial resistance and suppression of macrophage cell death. This study also revealed differences in cell death pathways triggered by F. novicida versus F. tularensis infection that may relate to differences in virulence.
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Affiliation(s)
- Erik J Kopping
- Department of Microbiology and Immunology, School of Medicine, Stony Brook University, Stony Brook, New York, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA
| | - P Todd Benziger
- Department of Microbiology and Immunology, School of Medicine, Stony Brook University, Stony Brook, New York, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA
| | - David G Thanassi
- Department of Microbiology and Immunology, School of Medicine, Stony Brook University, Stony Brook, New York, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA
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2
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Jessop F, Schwarz B, Bohrnsen E, Bosio CM. Route of Francisella tularensis infection informs spatiotemporal metabolic reprogramming and inflammation in mice. PLoS One 2023; 18:e0293450. [PMID: 37883420 PMCID: PMC10602361 DOI: 10.1371/journal.pone.0293450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/12/2023] [Indexed: 10/28/2023] Open
Abstract
Route of exposure to pathogens can inform divergent disease pathogenesis and mortality rates. However, the features that contribute to these differences are not well established. Host metabolism has emerged as a critical element governing susceptibility and the metabolism of tissue exposure sites are unique. Therefore, specific metabolic niches may contribute to the course and outcome of infection depending on route of infection. In the current study, we utilized a combination of imaging and systems metabolomics to map the spatiotemporal dynamics of the host response to intranasal (i.n.) or intradermal (i.d.) infection of mice using the bacterium Francisella tularensis subsp tularensis (FTT). FTT causes lethal disease through these infection routes with similar inoculation doses and replication kinetics, which allowed for isolation of host outcomes independent of bacterial burden. We observed metabolic modifications that were both route dependent and independent. Specifically, i.d. infection resulted in early metabolic reprogramming at the site of infection and draining lymph nodes, whereas the lungs and associated draining lymph nodes were refractory to metabolic reprogramming following i.n. infection. Irrespective of exposure route, FTT promoted metabolic changes in systemic organs prior to colonization, and caused massive dysregulation of host metabolism in these tissues prior to onset of morbidity. Preconditioning infection sites towards a more glycolytic and pro-inflammatory state prior to infection exacerbated FTT replication within the lungs but not intradermal tissue. This enhancement of replication in the lungs was associated with the ability of FTT to limit redox imbalance and alter the pentose phosphate pathway. Together, these studies identify central metabolic features of the lung and dermal compartments that contribute to disease progression and identify potential tissue specific targets that may be exploited for novel therapeutic approaches.
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Affiliation(s)
- Forrest Jessop
- Rocky Mountain Laboratories, NIAID, Hamilton, MT, United States of America
| | - Benjamin Schwarz
- Rocky Mountain Laboratories, NIAID, Hamilton, MT, United States of America
| | - Eric Bohrnsen
- Rocky Mountain Laboratories, NIAID, Hamilton, MT, United States of America
| | - Catharine M. Bosio
- Rocky Mountain Laboratories, NIAID, Hamilton, MT, United States of America
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3
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Ojha D, Jessop F, Bosio CM, Peterson KE. Effective inhibition of HCoV-OC43 and SARS-CoV-2 by phytochemicals in vitro and in vivo. Int J Antimicrob Agents 2023; 62:106893. [PMID: 37339711 PMCID: PMC10277159 DOI: 10.1016/j.ijantimicag.2023.106893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 05/26/2023] [Accepted: 06/14/2023] [Indexed: 06/22/2023]
Abstract
OBJECTIVE Several coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and human coronavirus OC43 (HCoV-OC43), can cause respiratory infections in humans. To address the need for reliable anti-coronavirus therapeutics, we screened 16 active phytochemicals selected from medicinal plants used in traditional applications for respiratory-related illnesses. METHODS An initial screen was completed using HCoV-OC43 to identify compounds that inhibit virus-induced cytopathic effect (CPE) and cell death inhibition. Then the top hits were validated in vitro against both HCoV-OC43 and SARS-CoV-2 by determining virus titer in cell supernatant and virus-induced cell death. Finally, the most active phytochemical was validated in vivo in the SARS-CoV-2-infected B6.Cg-Tg(K18-ACE2)2Prlmn/J mouse model. RESULTS The phytochemicals lycorine (LYC), capsaicin, rottlerin (RTL), piperine and chebulinic acid (CHU) inhibited HCoV-OC43-induced cytopathic effect and reduced viral titres by up to 4 log. LYC, RTL and CHU also suppressed virus replication and cell death following SARS-CoV-2 infection. In vivo, RTL significantly reduced SARS-CoV-2-induced mortality by ∼40% in human angiotensin-converting enzyme 2 (ACE2)-expressing K18 mice. CONCLUSION Collectively, these studies indicate that RTL and other phytochemicals have therapeutic potential to reduce SARS-CoV-2 and HCoV-OC43 infections.
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Affiliation(s)
- Durbadal Ojha
- Neuroimmunology Section, Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 S. 4th St., Hamilton, MT, USA.
| | - Forrest Jessop
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 S. 4th St., Hamilton, MT, USA
| | - Catharine M Bosio
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 S. 4th St., Hamilton, MT, USA
| | - Karin E Peterson
- Neuroimmunology Section, Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 S. 4th St., Hamilton, MT, USA.
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Benziger PT, Kopping EJ, McLaughlin PA, Thanassi DG. Francisella tularensis disrupts TLR2-MYD88-p38 signaling early during infection to delay apoptosis of macrophages and promote virulence in the host. mBio 2023; 14:e0113623. [PMID: 37404047 PMCID: PMC10470500 DOI: 10.1128/mbio.01136-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 05/24/2023] [Indexed: 07/06/2023] Open
Abstract
Francisella tularensis is a zoonotic pathogen and the causative agent of tularemia. F. tularensis replicates to high levels within the cytosol of macrophages and other host cells while subverting the host response to infection. Critical to the success of F. tularensis is its ability to delay macrophage apoptosis to maintain its intracellular replicative niche. However, the host-signaling pathway(s) modulated by F. tularensis to delay apoptosis are poorly characterized. The outer membrane channel protein TolC is required for F. tularensis virulence and its ability to suppress apoptosis and cytokine expression during infection of macrophages. We took advantage of the F. tularensis ∆tolC mutant phenotype to identify host pathways that are important for activating macrophage apoptosis and that are disrupted by the bacteria. Comparison of macrophages infected with wild-type or ∆tolC F. tularensis revealed that the bacteria interfere with TLR2-MYD88-p38 signaling at early times post infection to delay apoptosis, dampen innate host responses, and preserve the intracellular replicative niche. Experiments using the mouse pneumonic tularemia model confirmed the in vivo relevance of these findings, revealing contributions of TLR2 and MYD88 signaling to the protective host response to F. tularensis, which is modulated by the bacteria to promote virulence. IMPORTANCE Francisella tularensis is a Gram-negative intracellular bacterial pathogen and the causative agent of the zoonotic disease tularemia. F. tularensis, like other intracellular pathogens, modulates host-programmed cell death pathways to ensure its replication and survival. We previously identified the outer membrane channel protein TolC as required for the ability of F. tularensis to delay host cell death. However, the mechanism by which F. tularensis delays cell death pathways during intracellular replication is unclear despite being critical to pathogenesis. In the present study, we address this gap in knowledge by taking advantage of ∆tolC mutants of F. tularensis to uncover signaling pathways governing host apoptotic responses to F. tularensis and which are modulated by the bacteria during infection to promote virulence. These findings reveal mechanisms by which intracellular pathogens subvert host responses and enhance our understanding of the pathogenesis of tularemia.
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Affiliation(s)
- P. Todd Benziger
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA
| | - Erik J. Kopping
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA
| | - Patrick A. McLaughlin
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA
| | - David G. Thanassi
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA
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Jessop F, Schwarz B, Bohrnsen E, Miltko M, Shaia C, Bosio CM. Targeting 2-Oxoglutarate-Dependent Dioxygenases Promotes Metabolic Reprogramming That Protects against Lethal SARS-CoV-2 Infection in the K18-hACE2 Transgenic Mouse Model. Immunohorizons 2023; 7:528-542. [PMID: 37417946 PMCID: PMC10587500 DOI: 10.4049/immunohorizons.2300048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/08/2023] Open
Abstract
Dysregulation of host metabolism is a feature of lethal SARS-CoV-2 infection. Perturbations in α-ketoglutarate levels can elicit metabolic reprogramming through 2-oxoglutarate-dependent dioxygenases (2-ODDGs), leading to stabilization of the transcription factor HIF-1α. HIF1-α activation has been reported to promote antiviral mechanisms against SARS-CoV-2 through direct regulation of ACE2 expression (a receptor required for viral entry). However, given the numerous pathways HIF-1α serves to regulate it is possible that there are other undefined metabolic mechanisms contributing to the pathogenesis of SARS-CoV-2 independent of ACE2 downregulation. In this study, we used in vitro and in vivo models in which HIF-1α modulation of ACE2 expression was negated, allowing for isolated characterization of the host metabolic response within SARS-CoV-2 disease pathogenesis. We demonstrated that SARS-CoV-2 infection limited stabilization of HIF-1α and associated mitochondrial metabolic reprogramming by maintaining activity of the 2-ODDG prolyl hydroxylases. Inhibition of 2-ODDGs with dimethyloxalylglycine promoted HIF-1α stabilization following SARS-CoV-2 infection, and significantly increased survival among SARS-CoV-2-infected mice compared with vehicle controls. However, unlike previous reports, the mechanism by which activation of HIF-1α responses contributed to survival was not through impairment of viral replication. Rather, dimethyloxalylglycine treatment facilitated direct effects on host metabolism including increased glycolysis and resolution of dysregulated pools of metabolites, which correlated with reduced morbidity. Taken together, these data identify (to our knowledge) a novel function of α-ketoglutarate-sensing platforms, including those responsible for HIF-1α stabilization, in the resolution of SARS-CoV-2 infection and support targeting these metabolic nodes as a viable therapeutic strategy to limit disease severity during infection.
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Affiliation(s)
- Forrest Jessop
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, Hamilton, MT
| | - Benjamin Schwarz
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, Hamilton, MT
| | - Eric Bohrnsen
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, Hamilton, MT
| | - Molly Miltko
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, Hamilton, MT
| | - Carl Shaia
- Rocky Mountain Veterinary Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, Hamilton, MT
| | - Catharine M. Bosio
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, Hamilton, MT
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Alqahtani M, Ma Z, Miller J, Yu J, Malik M, Bakshi CS. Comparative analysis of absent in melanoma 2-inflammasome activation in Francisella tularensis and Francisella novicida. Front Microbiol 2023; 14:1188112. [PMID: 37266012 PMCID: PMC10230036 DOI: 10.3389/fmicb.2023.1188112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 05/02/2023] [Indexed: 06/03/2023] Open
Abstract
Francisella tularensis is a highly virulent Gram-negative bacterium that causes the fatal zoonotic disease tularemia. The mechanisms and signaling pathways leading to the absent in melanoma 2 (Aim2) inflammasome activation have been elegantly elucidated using Francisella novicida as a model. Although not pathogenic for humans, F. novicida can cause tularemia in mice, and the inflammatory response it triggers is the polar opposite to that observed in mice infected with F. tularensis strains. This study aimed to understand the mechanisms of Aim2 inflammasome activation in F. tularensis-infected macrophages. The results reveal that macrophages infected with the F. tularensis live vaccine strain (LVS) induce lower levels of Aim2-dependent IL-1β than those infected with F. novicida. The suppression/weak activation of Aim2 in F. tularensis LVS-infected macrophages is due to the suppression of the cGAS-STING DNA-sensing pathway. Furthermore, the introduction of exogenous F. tularensis LVS DNA into the cytosol of the F. tularensis LVS-infected macrophages, alone or in conjunction with a priming signal, failed to restore IL-1β levels similar to those observed for F. novicida-infected macrophages. These results indicated that, in addition to the bacterial DNA, DNA from some other sources, specifically from the damaged mitochondria, might contribute to the robust Aim2-dependent IL-1β levels observed in F. novicida-infected macrophages. The results indicate that F. tularensis LVS induces mitophagy that may potentially prevent the leakage of mitochondrial DNA and the subsequent activation of the Aim2 inflammasome. Collectively, this study demonstrates that the mechanisms of Aim2 inflammasome activation established for F. novicida are not operative in F. tularensis.
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Affiliation(s)
- Maha Alqahtani
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY, United States
| | - Zhuo Ma
- Department of Basic and Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | - Jacob Miller
- Department of Basic and Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | - Jen Yu
- Electron Microscopy Laboratory, Department of Pathology, Westchester Medical Center, Valhalla, NY, United States
| | - Meenakshi Malik
- Department of Basic and Clinical Sciences, Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | - Chandra Shekhar Bakshi
- Department of Pathology, Microbiology and Immunology, New York Medical College, Valhalla, NY, United States
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7
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Schwarz B, Roberts LM, Bohrnsen E, Jessop F, Wehrly TD, Shaia C, Bosio CM. Contribution of Lipid Mediators in Divergent Outcomes following Acute Bacterial and Viral Lung Infections in the Obese Host. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 209:1323-1334. [PMID: 36002235 PMCID: PMC9529825 DOI: 10.4049/jimmunol.2200162] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 08/02/2022] [Indexed: 01/04/2023]
Abstract
Obesity is considered an important comorbidity for a range of noninfectious and infectious disease states including those that originate in the lung, yet the mechanisms that contribute to this susceptibility are not well defined. In this study, we used the diet-induced obesity (DIO) mouse model and two models of acute pulmonary infection, Francisella tularensis subspecies tularensis strain SchuS4 and SARS-CoV-2, to uncover the contribution of obesity in bacterial and viral disease. Whereas DIO mice were more resistant to infection with SchuS4, DIO animals were more susceptible to SARS-CoV-2 infection compared with regular weight mice. In both models, neither survival nor morbidity correlated with differences in pathogen load, overall cellularity, or influx of inflammatory cells in target organs of DIO and regular weight animals. Increased susceptibility was also not associated with exacerbated production of cytokines and chemokines in either model. Rather, we observed pathogen-specific dysregulation of the host lipidome that was associated with vulnerability to infection. Inhibition of specific pathways required for generation of lipid mediators reversed resistance to both bacterial and viral infection. Taken together, our data demonstrate disparity among obese individuals for control of lethal bacterial and viral infection and suggest that dysregulation of the host lipidome contributes to increased susceptibility to viral infection in the obese host.
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Affiliation(s)
- Benjamin Schwarz
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT; and
| | - Lydia M Roberts
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT; and
| | - Eric Bohrnsen
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT; and
| | - Forrest Jessop
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT; and
| | - Tara D Wehrly
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT; and
| | - Carl Shaia
- Rocky Mountain Veterinary Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT
| | - Catharine M Bosio
- Immunity to Pulmonary Pathogens Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT; and
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8
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Mohammadi N, Lindgren H, Yamamoto M, Martin A, Henry T, Sjöstedt A. Macrophages Demonstrate Guanylate-Binding Protein-Dependent and Bacterial Strain-Dependent Responses to Francisella tularensis. Front Cell Infect Microbiol 2022; 11:784101. [PMID: 35004352 PMCID: PMC8738097 DOI: 10.3389/fcimb.2021.784101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/09/2021] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis is a facultative intracellular bacterium and the etiological agent of tularemia, a zoonotic disease. Infection of monocytic cells by F. tularensis can be controlled after activation with IFN-γ; however, the molecular mechanisms whereby the control is executed are incompletely understood. Recently, a key role has been attributed to the Guanylate-binding proteins (GBPs), interferon-inducible proteins involved in the cell-specific immunity against various intracellular pathogens. Here, we assessed the responses of bone marrow-derived murine macrophages (BMDM) and GBP-deficient BMDM to F. tularensis strains of variable virulence; the highly virulent SCHU S4 strain, the human live vaccine strain (LVS), or the widely used surrogate for F. tularensis, the low virulent F. novicida. Each of the strains multiplied rapidly in BMDM, but after addition of IFN-γ, significant GBP-dependent control of infection was observed for the LVS and F. novicida strains, whereas there was no control of the SCHU S4 infection. However, no differences in GBP transcription or translation were observed in the infected cell cultures. During co-infection with F. novicida and SCHU S4, significant control of both strains was observed. Patterns of 18 cytokines were very distinct between infected cell cultures and high levels were observed for almost all cytokines in F. novicida-infected cultures and very low levels in SCHU S4-infected cultures, whereas levels in co-infected cultures for a majority of cytokines showed intermediate levels, or levels similar to those of F. novicida-infected cultures. We conclude that the control of BMDM infection with F. tularensis LVS or F. novicida is GBP-dependent, whereas SCHU S4 was only controlled during co-infection. Since expression of GBP was similar regardless of infecting agent, the findings imply that SCHU S4 has an inherent ability to evade the GBP-dependent anti-bacterial mechanisms.
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Affiliation(s)
- Nasibeh Mohammadi
- Department of Clinical Microbiology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Helena Lindgren
- Department of Clinical Microbiology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Masahiro Yamamoto
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka, Japan
| | - Amandine Martin
- Inserm, U1111, Centre International de Recherche en Infectiologie, Lyon, France
| | - Thomas Henry
- Inserm, U1111, Centre International de Recherche en Infectiologie, Lyon, France
| | - Anders Sjöstedt
- Department of Clinical Microbiology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
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9
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Using proteomics to identify host cell interaction partners for VgrG and IglJ. Sci Rep 2020; 10:14612. [PMID: 32884055 PMCID: PMC7471685 DOI: 10.1038/s41598-020-71641-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/23/2020] [Indexed: 11/17/2022] Open
Abstract
Francisella tularensis is a highly virulent intracellular bacterium and the causative agent of tularemia. The disease is characterized by the suboptimal innate immune response and consequently by the impaired adaptive immunity. The virulence of this pathogen depends on proteins encoded by a genomic island termed the Francisella Pathogenicity Island (FPI). However, the precise biological roles of most of the FPI-encoded proteins remain to be clarified. In this study, we employed stable isotope labeling by amino acids in cell culture (SILAC) in combination with affinity protein purification coupled with liquid chromatography–mass spectrometry to identify potential protein-effector binding pairs for two FPI virulence effectors IglJ and VgrG. Our results may indicate that while the IglJ protein interactions primarily affect mitochondria, the VgrG interactions affect phagosome and/or autophagosome biogenesis via targeting components of the host’s exocyst complex.
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10
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Allen PE, Martinez JJ. Modulation of Host Lipid Pathways by Pathogenic Intracellular Bacteria. Pathogens 2020; 9:pathogens9080614. [PMID: 32731350 PMCID: PMC7460438 DOI: 10.3390/pathogens9080614] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 07/17/2020] [Accepted: 07/25/2020] [Indexed: 12/22/2022] Open
Abstract
Lipids are a broad group of molecules required for cell maintenance and homeostasis. Various intracellular pathogens have developed mechanisms of modulating and sequestering host lipid processes for a large array of functions for both bacterial and host cell survival. Among the host cell lipid functions that intracellular bacteria exploit for infection are the modulation of host plasma membrane microdomains (lipid rafts) required for efficient bacterial entry; the recruitment of specific lipids for membrane integrity of intracellular vacuoles; and the utilization of host lipid droplets for the regulation of immune responses and for energy production through fatty acid β-oxidation and oxidative phosphorylation. The majority of published studies on the utilization of these host lipid pathways during infection have focused on intracellular bacterial pathogens that reside within a vacuole during infection and, thus, have vastly different requirements for host lipid metabolites when compared to those intracellular pathogens that are released into the host cytosol upon infection. Here we summarize the mechanisms by which intracellular bacteria sequester host lipid species and compare the modulation of host lipid pathways and metabolites during host cell infection by intracellular pathogens residing in either a vacuole or within the cytosol of infected mammalian cells. This review will also highlight common and unique host pathways necessary for intracellular bacterial growth that could potentially be targeted for therapeutic intervention.
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11
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Pierce SK, Schwartzberg PL, Shah NN, Taylor N. Women in immunology: 2020 and beyond. Nat Immunol 2020; 21:254-258. [PMID: 32094649 DOI: 10.1038/s41590-020-0618-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 01/24/2020] [Indexed: 12/27/2022]
Abstract
Women have been at the forefront of tremendous achievements in immunology in the past decade. However, disparities still exist, limiting upward potential and further advancements. As four NIH intramural women scientists who care deeply about scientific progress and the progress of women in our field, we review ongoing challenges and discuss potential approaches to help advance the promotion of women in the sciences.
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Affiliation(s)
- Susan K Pierce
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, USA.
| | - Pamela L Schwartzberg
- Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, USA.
| | - Nirali N Shah
- Pediatric Oncology Branch, National Cancer Institute, NIH, Bethesda, MD, USA.
| | - Naomi Taylor
- Pediatric Oncology Branch, National Cancer Institute, NIH, Bethesda, MD, USA. .,IGMM, Université de Montpellier, CNRS, Montpellier, France.
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12
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Interferon Gamma Reprograms Host Mitochondrial Metabolism through Inhibition of Complex II To Control Intracellular Bacterial Replication. Infect Immun 2020; 88:IAI.00744-19. [PMID: 31740527 DOI: 10.1128/iai.00744-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 11/12/2019] [Indexed: 12/21/2022] Open
Abstract
The mechanisms by which interferon gamma (IFN-γ) controls the replication of cytosolic pathogens independent of responses, such as the generation of reactive oxygen species/reactive nitrogen species (ROS/RNS), have not been fully elucidated. In the current study, we developed a model using Francisella tularensis, the causative agent of tularemia, in which pathways triggered by IFN-γ commonly associated with bacterial control were not required. Using this model, we demonstrated that IFN-γ-mediated production of itaconate and its ability to impair host mitochondrial function, independent of activity on the pathogen, were central for the restriction of bacterial replication in vitro and in vivo We then demonstrate that IFN-γ-driven itaconate production was dispensable, as directly targeting complex II using cell membrane-permeable metabolites also controlled infection. Together, these findings show that while reprogramming of mitochondrial metabolism is a key factor in IFN-γ control of intracellular bacteria, the development of antimicrobial strategies based on targeting host mitochondrial metabolism independent of this cytokine may be an effective therapeutic approach.
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Ramond E, Jamet A, Coureuil M, Charbit A. Pivotal Role of Mitochondria in Macrophage Response to Bacterial Pathogens. Front Immunol 2019; 10:2461. [PMID: 31708919 PMCID: PMC6819784 DOI: 10.3389/fimmu.2019.02461] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/02/2019] [Indexed: 12/23/2022] Open
Abstract
Mitochondria are essential organelles that act as metabolic hubs and signaling platforms within the cell. Numerous mitochondrial functions, including energy metabolism, lipid synthesis, and autophagy regulation, are intimately linked to mitochondrial dynamics, which is shaped by ongoing fusion and fission events. Recently, several intracellular bacterial pathogens have been shown to modulate mitochondrial functions to maintain their replicative niche. Through selected examples of human bacterial pathogens, we will discuss how infection induces mitochondrial changes in infected macrophages, triggering modifications of the host metabolism that lead to important immunological reprogramming.
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Affiliation(s)
- Elodie Ramond
- Université de Paris, Paris, France.,INSERM U1151, Institut Necker-Enfants Malades, Team 7, Pathogenesis of Systemic Infections, Paris, France.,CNRS UMR 8253, Paris, France
| | - Anne Jamet
- Université de Paris, Paris, France.,INSERM U1151, Institut Necker-Enfants Malades, Team 7, Pathogenesis of Systemic Infections, Paris, France.,CNRS UMR 8253, Paris, France
| | - Mathieu Coureuil
- Université de Paris, Paris, France.,INSERM U1151, Institut Necker-Enfants Malades, Team 7, Pathogenesis of Systemic Infections, Paris, France.,CNRS UMR 8253, Paris, France
| | - Alain Charbit
- Université de Paris, Paris, France.,INSERM U1151, Institut Necker-Enfants Malades, Team 7, Pathogenesis of Systemic Infections, Paris, France.,CNRS UMR 8253, Paris, France
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Kubelkova K, Macela A. Innate Immune Recognition: An Issue More Complex Than Expected. Front Cell Infect Microbiol 2019; 9:241. [PMID: 31334134 PMCID: PMC6616152 DOI: 10.3389/fcimb.2019.00241] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 06/18/2019] [Indexed: 12/11/2022] Open
Abstract
Primary interaction of an intracellular bacterium with its host cell is initiated by activation of multiple signaling pathways in response to bacterium recognition itself or as cellular responses to stress induced by the bacterium. The leading molecules in these processes are cell surface membrane receptors as well as cytosolic pattern recognition receptors recognizing pathogen-associated molecular patterns or damage-associated molecular patterns induced by the invading bacterium. In this review, we demonstrate possible sequences of events leading to recognition of Francisella tularensis, present findings on known mechanisms for manipulating cell responses to protect Francisella from being killed, and discuss newly published data from the perspective of early stages of host-pathogen interaction.
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Affiliation(s)
- Klara Kubelkova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
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