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Sheet S, Sathishkumar Y, Acharya S, Lee YS. Exposure of Legionella pneumophila to low-shear modeled microgravity: impact on stress response, membrane lipid composition, pathogenicity to macrophages and interrelated genes expression. Arch Microbiol 2024; 206:87. [PMID: 38305908 DOI: 10.1007/s00203-023-03753-z] [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: 04/27/2023] [Revised: 10/31/2023] [Accepted: 11/16/2023] [Indexed: 02/03/2024]
Abstract
Here, we studied the effect of low-shear modeled microgravity (LSMMG) on cross stress resistance (heat, acid, and oxidative), fatty acid content, and pathogenicity along with alteration in expression of stress-/virulence-associated genes in Legionella pneumophila. The stress resistance analysis result indicated that bacteria cultivated under LSMMG environments showed higher resistance with elevated D-values at 55 °C and in 1 mM of hydrogen peroxide (H2O2) conditions compared to normal gravity (NG)-grown bacteria. On the other hand, there was no significant difference in tolerance (p < 0.05) toward simulated gastric fluid (pH-2.5) acid conditions. In fatty acid analysis, our result showed that a total amount of saturated and cyclic fatty acids was increased in LSMMG-grown cells; as a consequence, they might possess low membrane fluidity. An upregulated expression level was noticed for stress-related genes (hslV, htrA, grpE, groL, htpG, clpB, clpX, dnaJ, dnaK, rpoH, rpoE, rpoS, kaiB, kaiC, lpp1114, ahpC1, ahpC2, ahpD, grlA, and gst) under LSMMG conditions. The reduced virulence (less intracellular bacteria and less % of induce apoptosis in RAW 264.7 macrophages) of L. pneumophila under LSMMG conditions may be because of downregulation related genes (dotA, dotB, dotC, dotD, dotG, dotH, dotL, dotM, dotN, icmK, icmB, icmS, icmT, icmW, ladC, rtxA, letA, rpoN, fleQ, fleR, and fliA). In the LSMMG group, the expression of inflammation-related factors, such as IL-1α, TNF-α, IL-6, and IL-8, was observed to be reduced in infected macrophages. Also, scanning electron microscopy (SEM) analysis showed less number of LSMMG-cultivated bacteria attached to the host macrophages compared to NG. Thus, our study provides understandings about the changes in lipid composition and different genes expression due to LSMMG conditions, which apparently influence the alterations of L. pneumophila' stress/virulence response.
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Affiliation(s)
- Sunirmal Sheet
- Department of Wood Science and Technology, College of Agriculture and Life Sciences, Jeonbuk National University, 567, Jeonju-si, Jeollabuk-do, Republic of Korea
| | | | - Satabdi Acharya
- Department of Biomedical Sciences and Institute for Medical Science, Jeonbuk National University Medical School, 567, Jeonju-si, Jeollabuk-do, Republic of Korea
| | - Yang Soo Lee
- Department of Wood Science and Technology, College of Agriculture and Life Sciences, Jeonbuk National University, 567, Jeonju-si, Jeollabuk-do, Republic of Korea.
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2
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Ngwaga T, Chauhan D, Salberg AG, Shames SR. Effector-mediated subversion of proteasome activator (PA)28αβ enhances host defense against Legionella pneumophila under inflammatory and oxidative stress conditions. PLoS Pathog 2023; 19:e1011473. [PMID: 37347796 PMCID: PMC10321654 DOI: 10.1371/journal.ppat.1011473] [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: 05/03/2022] [Revised: 07/05/2023] [Accepted: 06/09/2023] [Indexed: 06/24/2023] Open
Abstract
Legionella pneumophila is a natural pathogen of amoebae that causes Legionnaires' Disease in immunocompromised individuals via replication within macrophages. L. pneumophila virulence and intracellular replication hinges on hundreds of Dot/Icm-translocated effector proteins, which are essential for biogenesis of the replication-permissive Legionella-containing vacuole (LCV). However, effector activity can also enhance mammalian host defense via effector-triggered immunity. The L. pneumophila effector LegC4 is important for virulence in amoebae but enhances host defense against L. pneumophila in the mouse lung and, uniquely, within macrophages activated with either tumor necrosis factor (TNF) or interferon (IFN)-γ. The mechanism by which LegC4 potentiates cytokine-mediated host defense in macrophages is unknown. Here, we found that LegC4 enhances cytokine-mediated phagolysosomal fusion with Legionella-containing vacuole (LCV) and binds host proteasome activator (PA)28α, which forms a heterooligomer with PA28β to facilitate ubiquitin-independent proteasomal degradation of oxidant-damaged (carbonylated) proteins. We found that oxidative stress was sustained in the presence of LegC4 and that the LegC4 restriction phenotype was relieved in PA28αβ-deficient macrophages and in the lungs of mice in vivo. Our data also show that oxidative stress is sufficient for LegC4-mediated restriction in macrophages producing PA28αβ. PA28αβ has been traditionally associated with antigen presentation; however, our data support a novel mechanism whereby effector-mediated subversion of PA28αβ enhances cell-autonomous host defense against L. pneumophila under inflammatory and oxidative stress conditions. This work provides a solid foundation to evaluate induced proteasome regulators as mediators of innate immunity.
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Affiliation(s)
- Tshegofatso Ngwaga
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Deepika Chauhan
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Abigail G. Salberg
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Stephanie R. Shames
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
- Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
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3
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Intrabacterial Regulation of a Cytotoxic Effector by Its Cognate Metaeffector Promotes Legionella pneumophila Virulence. mSphere 2023; 8:e0055222. [PMID: 36598225 PMCID: PMC9942577 DOI: 10.1128/msphere.00552-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Legionella pneumophila is a natural pathogen of unicellular protozoa that can opportunistically infect macrophages and cause Legionnaires' Disease. Intracellular replication is driven by hundreds of bacterial effector proteins that are translocated into infected host cells by a Dot/Icm type IV secretion system. L. pneumophila effectors are temporally regulated in part by a unique family of translocated regulatory effectors, termed metaeffectors, which bind and modulate the function of a cognate effector in host cells. Regulation of the cytotoxic effector SidI by its cognate metaeffector, MesI, is critical for L. pneumophila virulence in natural and opportunistic hosts. MesI binds and negatively regulates SidI activity in vitro, but how impaired regulation of SidI impairs L. pneumophila intracellular replication is unclear. Using a chromosomally encoded inducible expression system, we found that SidI was toxic to L. pneumophila when uncoupled from MesI. SidI enzymatic activity was required for intrabacterial toxicity since L. pneumophila growth was unaffected by induced expression of a catalytically inactive sidI allele. We also found that MesI translocation into host cells was dispensable for intracellular replication and that MesI-deficient bacteria were rapidly degraded within host cells. These data suggest that MesI promotes L. pneumophila intracellular replication by regulating SidI within the bacterium and reveal a unique role for intrabacterial effector regulation by a translocated metaeffector in L. pneumophila virulence. IMPORTANCE Legionella pneumophila replicates within phagocytic host cells using hundreds of effector protein virulence factors, which canonically subvert the function of host proteins and pathways. L. pneumophila encodes a unique family of translocated effectors called metaeffectors, which bind and regulate the function of a cognate effector in host cells. The metaeffector MesI promotes L. pneumophila virulence by regulating the cytotoxic effector SidI; however, the MesI regulatory mechanism is poorly understood. We discovered a unique intrabacterial role for MesI in L. pneumophila virulence. When uncoupled from MesI, SidI was toxic to L. pneumophila in vitro and triggered robust bacterial degradation in host cells. Furthermore, translocation of MesI was dispensable for intracellular replication, demonstrating that intrabacterial regulation of SidI contributes to L. pneumophila virulence. These data show a novel and important role for translocated effector activity within the bacterium, which challenges the dogma that L. pneumophila effectors function exclusively within host cells.
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4
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Lockwood DC, Amin H, Costa TRD, Schroeder GN. The Legionella pneumophila Dot/Icm type IV secretion system and its effectors. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35639581 DOI: 10.1099/mic.0.001187] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
To prevail in the interaction with eukaryotic hosts, many bacterial pathogens use protein secretion systems to release virulence factors at the host–pathogen interface and/or deliver them directly into host cells. An outstanding example of the complexity and sophistication of secretion systems and the diversity of their protein substrates, effectors, is the Defective in organelle trafficking/Intracellular multiplication (Dot/Icm) Type IVB secretion system (T4BSS) of
Legionella pneumophila
and related species.
Legionella
species are facultative intracellular pathogens of environmental protozoa and opportunistic human respiratory pathogens. The Dot/Icm T4BSS translocates an exceptionally large number of effectors, more than 300 per
L. pneumophila
strain, and is essential for evasion of phagolysosomal degradation and exploitation of protozoa and human macrophages as replicative niches. Recent technological advancements in the imaging of large protein complexes have provided new insight into the architecture of the T4BSS and allowed us to propose models for the transport mechanism. At the same time, significant progress has been made in assigning functions to about a third of
L. pneumophila
effectors, discovering unprecedented new enzymatic activities and concepts of host subversion. In this review, we describe the current knowledge of the workings of the Dot/Icm T4BSS machinery and provide an overview of the activities and functions of the to-date characterized effectors in the interaction of
L. pneumophila
with host cells.
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Affiliation(s)
- Daniel C Lockwood
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, BT9 7BL, Northern Ireland, UK
| | - Himani Amin
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Tiago R D Costa
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Gunnar N Schroeder
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, BT9 7BL, Northern Ireland, UK
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5
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Martyn JE, Gomez-Valero L, Buchrieser C. The evolution and role of eukaryotic-like domains in environmental intracellular bacteria: the battle with a eukaryotic cell. FEMS Microbiol Rev 2022; 46:6529235. [DOI: 10.1093/femsre/fuac012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 02/09/2022] [Accepted: 02/14/2022] [Indexed: 11/14/2022] Open
Abstract
Abstract
Intracellular pathogens that are able to thrive in different environments, such as Legionella spp. which preferentially live in protozoa in aquatic environments or environmental Chlamydiae which replicate either within protozoa or a range of animals, possess a plethora of cellular biology tools to influence their eukaryotic host. The host manipulation tools that evolved in the interaction with protozoa, confer these bacteria the capacity to also infect phylogenetically distinct eukaryotic cells, such as macrophages and thus they can also be human pathogens. To manipulate the host cell, bacteria use protein secretion systems and molecular effectors. Although these molecular effectors are encoded in bacteria, they are expressed and function in a eukaryotic context often mimicking or inhibiting eukaryotic proteins. Indeed, many of these effectors have eukaryotic-like domains. In this review we propose that the main pathways environmental intracellular bacteria need to subvert in order to establish the host eukaryotic cell as a replication niche are chromatin remodelling, ubiquitination signalling, and modulation of protein-protein interactions via tandem repeat domains. We then provide mechanistic insight into how these proteins might have evolved as molecular weapons. Finally, we highlight that in environmental intracellular bacteria the number of eukaryotic-like domains and proteins is considerably higher than in intracellular bacteria specialised to an isolated niche, such as obligate intracellular human pathogens. As mimics of eukaryotic proteins are critical components of host pathogen interactions, this distribution of eukaryotic-like domains suggests that the environment has selected them.
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Affiliation(s)
- Jessica E Martyn
- Institut Pasteur, Biologie des Bactéries Intracellulaires and CNRS UMR 3525, Paris, France
| | - Laura Gomez-Valero
- Institut Pasteur, Biologie des Bactéries Intracellulaires and CNRS UMR 3525, Paris, France
| | - Carmen Buchrieser
- Institut Pasteur, Biologie des Bactéries Intracellulaires and CNRS UMR 3525, Paris, France
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6
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Guillemot J, Ginevra C, Allam C, Kay E, Gilbert C, Doublet P, Jarraud S, Chapalain A. TNF-α response in macrophages depends on clinical Legionella pneumophila isolates genotypes. Virulence 2022; 13:160-173. [PMID: 35030980 PMCID: PMC8765069 DOI: 10.1080/21505594.2021.2022861] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Legionnaires' Disease (LD) is a severe pneumonia mainly caused in Europe by Legionella pneumophila serogroup 1 (Lp1). Sequence-based typing methods reveal that some sequence types (ST) are overrepresented in clinical samples such as ST1 and ST47, suggesting that some strains are more fit for infection than others. In the present study, a collection of 108 Lp1 clinical isolates were used to evaluate the strain-dependent immune responses from human macrophages. Clinical Lp1 isolates induced differential TNFα secretion from macrophages. ST1 isolates induced a significantly higher TNF-α secretion than non-ST1, whereas ST47 isolates induced a significantly lower TNF-α secretion than non-ST47 isolates. ST1 isolates induced a significantly higher cell death than ST47 isolates evaluated by lactate dehydrogenase activity (cytotoxicity) and caspase-3 activity (apoptosis). Treatment of macrophages with anti-TNF-α antibodies significantly reduced the cell death in macrophages infected with ST1 or ST47 strains. The TNF-α secretion was neither explained by a differential bacterial replication nor by the number or type (bystander or infected) of TNF-α producing cells following infection but by a differential response from macrophages. The Paris ST1 reference strain elicited a significantly higher TNF-α gene transcription and a higher induction of NF-κB signaling pathway than the Lorraine ST47 reference strain.Clinical Lp1 isolates induce a diverse immune response and cell death, which could be related to the genotype. The two predominant sequence-types ST1 and ST47 trigger opposite inflammatory response that could be related to the host susceptibility.
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Affiliation(s)
- Johann Guillemot
- Ciri, Centre International de Recherche En Infectiologie, Équipe Pathogenèse Des Légionelles, Université Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, Lyon, France
| | - Christophe Ginevra
- Ciri, Centre International de Recherche En Infectiologie, Équipe Pathogenèse Des Légionelles, Université Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, Lyon, France.,Hospices Civils de Lyon, Institut Des Agents Infectieux, Centre National de Référence Des Légionelles, Lyon, France
| | - Camille Allam
- Ciri, Centre International de Recherche En Infectiologie, Équipe Pathogenèse Des Légionelles, Université Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, Lyon, France.,Hospices Civils de Lyon, Institut Des Agents Infectieux, Centre National de Référence Des Légionelles, Lyon, France
| | - Elisabeth Kay
- Ciri, Centre International de Recherche En Infectiologie, Équipe Pathogenèse Des Légionelles, Université Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, Lyon, France
| | - Christophe Gilbert
- Ciri, Centre International de Recherche En Infectiologie, Équipe Pathogenèse Des Légionelles, Université Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, Lyon, France
| | - Patricia Doublet
- Ciri, Centre International de Recherche En Infectiologie, Équipe Pathogenèse Des Légionelles, Université Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, Lyon, France
| | - Sophie Jarraud
- Ciri, Centre International de Recherche En Infectiologie, Équipe Pathogenèse Des Légionelles, Université Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, Lyon, France.,Hospices Civils de Lyon, Institut Des Agents Infectieux, Centre National de Référence Des Légionelles, Lyon, France
| | - Annelise Chapalain
- Ciri, Centre International de Recherche En Infectiologie, Équipe Pathogenèse Des Légionelles, Université Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, Lyon, France
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7
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Wibawa RR, Li P, McCaffrey K, Hartland EL. Using Genomic Deletion Mutants to Investigate Effector-Triggered Immunity During Legionella pneumophila Infection. Methods Mol Biol 2022; 2523:23-41. [PMID: 35759189 DOI: 10.1007/978-1-0716-2449-4_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Legionella pneumophila is an intracellular bacterial pathogen that uses a type IV secretion system (T4SS), termed Dot/Icm, to secrete more than 330 virulence effector proteins into the infected host cell. Many Dot/Icm effectors are involved in biogenesis of the Legionella-containing vacuole (LCV), which allows intracellular bacterial replication in environmental amoebae and alveolar macrophages. Through their activity, some effectors trigger the mammalian host immune response in a phenomenon termed effector-triggered immunity (ETI). Here, we describe a protocol to create and use L. pneumophila genome deletion mutants to identify effector(s) that alter pro-inflammatory cytokine production and bacterial clearance in the lungs of mice.
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Affiliation(s)
- Rachelia R Wibawa
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia
- Department of Molecular and Translational Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Pengfei Li
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia
- Department of Molecular and Translational Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
- National Clinical Research Center for Hematologic Diseases, Soochow University, Suzhou, China
| | - Kathleen McCaffrey
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia
- Department of Molecular and Translational Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Elizabeth L Hartland
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia.
- Department of Molecular and Translational Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia.
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8
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Categorizing sequences of concern by function to better assess mechanisms of microbial pathogenesis. Infect Immun 2021; 90:e0033421. [PMID: 34780277 PMCID: PMC9119117 DOI: 10.1128/iai.00334-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To identify sequences with a role in microbial pathogenesis, we assessed the adequacy of their annotation by existing controlled vocabularies and sequence databases. Our goal was to regularize descriptions of microbial pathogenesis for improved integration with bioinformatic applications. Here, we review the challenges of annotating sequences for pathogenic activity. We relate the categorization of more than 2,750 sequences of pathogenic microbes through a controlled vocabulary called Functions of Sequences of Concern (FunSoCs). These allow for an ease of description by both humans and machines. We provide a subset of 220 fully annotated sequences in the supplemental material as examples. The use of this compact (∼30 terms), controlled vocabulary has potential benefits for research in microbial genomics, public health, biosecurity, biosurveillance, and the characterization of new and emerging pathogens.
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9
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Gilchrist AK, Smolensky D, Ngwaga T, Chauhan D, Cox S, Perumal R, Noronha LE, Shames SR. High-polyphenol extracts from Sorghum bicolor attenuate replication of Legionella pneumophila within RAW 264.7 macrophages. FEMS Microbiol Lett 2021; 367:5809964. [PMID: 32188994 DOI: 10.1093/femsle/fnaa053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 03/17/2020] [Indexed: 12/12/2022] Open
Abstract
Polyphenols derived from a variety of plants have demonstrated antimicrobial activity against diverse microbial pathogens. Legionella pneumophila is an intracellular bacterial pathogen that opportunistically causes a severe inflammatory pneumonia in humans, called Legionnaires' Disease, via replication within macrophages. Previous studies demonstrated that tea polyphenols attenuate L. pneumophila intracellular replication within mouse macrophages via increased tumor necrosis factor (TNF) production. Sorghum bicolor is a sustainable cereal crop that thrives in arid environments and is well-suited to continued production in warming climates. Sorghum polyphenols have anticancer and antioxidant properties, but their antimicrobial activity has not been evaluated. Here, we investigated the impact of sorghum polyphenols on L. pneumophila intracellular replication within RAW 264.7 mouse macrophages. Sorghum high-polyphenol extract (HPE) attenuated L. pneumophila intracellular replication in a dose-dependent manner but did not impair either bacterial replication in rich media or macrophage viability. Moreover, HPE treatment enhanced both TNF and IL-6 secretion from L. pneumophila infected macrophages. Thus, polyphenols derived from sorghum enhance macrophage restriction of L. pneumophila, likely via increased pro-inflammatory cytokine production. This work reveals commonalities between plant polyphenol-mediated antimicrobial activity and provides a foundation for future evaluation of sorghum as an antimicrobial agent.
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Affiliation(s)
- Aubrey K Gilchrist
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, Kansas, 66506 USA
| | - Dmitriy Smolensky
- Grain Quality and Structure Research Unit, Agricultural Research Service, U.S. Department of Agriculture, 1515 College Avenue, Manhattan, Kansas, 66506 USA
| | - Tshegofatso Ngwaga
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, Kansas, 66506 USA
| | - Deepika Chauhan
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, Kansas, 66506 USA
| | - Sarah Cox
- Grain Quality and Structure Research Unit, Agricultural Research Service, U.S. Department of Agriculture, 1515 College Avenue, Manhattan, Kansas, 66506 USA
| | - Ramasamy Perumal
- Kansas State University Agricultural Research Center, 1232 240th Avenue, Hays, Kansas, 67601 USA
| | - Leela E Noronha
- Arthropod-borne Animal Disease Research Unit, Agricultural Research Service, U. S. Department of Agriculture, 1515 College Avenue, Manhattan, Kansas, 66506 USA
| | - Stephanie R Shames
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, Kansas, 66506 USA
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10
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Chauhan D, Shames SR. Pathogenicity and Virulence of Legionella: Intracellular replication and host response. Virulence 2021; 12:1122-1144. [PMID: 33843434 PMCID: PMC8043192 DOI: 10.1080/21505594.2021.1903199] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Bacteria of the genus Legionella are natural pathogens of amoebae that can cause a severe pneumonia in humans called Legionnaires’ Disease. Human disease results from inhalation of Legionella-contaminated aerosols and subsequent bacterial replication within alveolar macrophages. Legionella pathogenicity in humans has resulted from extensive co-evolution with diverse genera of amoebae. To replicate intracellularly, Legionella generates a replication-permissive compartment called the Legionella-containing vacuole (LCV) through the concerted action of hundreds of Dot/Icm-translocated effector proteins. In this review, we present a collective overview of Legionella pathogenicity including infection mechanisms, secretion systems, and translocated effector function. We also discuss innate and adaptive immune responses to L. pneumophila, the implications of Legionella genome diversity and future avenues for the field.
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Affiliation(s)
- Deepika Chauhan
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
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11
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Ngwaga T, Chauhan D, Shames SR. Mechanisms of Effector-Mediated Immunity Revealed by the Accidental Human Pathogen Legionella pneumophila. Front Cell Infect Microbiol 2021; 10:593823. [PMID: 33614523 PMCID: PMC7886983 DOI: 10.3389/fcimb.2020.593823] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 12/22/2020] [Indexed: 12/25/2022] Open
Abstract
Many Gram-negative bacterial pathogens employ translocated virulence factors, termed effector proteins, to facilitate their parasitism of host cells and evade host anti-microbial defenses. However, eukaryotes have evolved to detect effector-mediated virulence strategies through a phenomenon termed effector-triggered immunity (ETI). Although ETI was discovered in plants, a growing body of literature demonstrates that metazoans also utilize effector-mediated immunity to detect and clear bacterial pathogens. This mini review is focused on mechanisms of effector-mediated immune responses by the accidental human pathogen Legionella pneumophila. We highlight recent advancements in the field and discuss the future prospects of harnessing effectors for the development of novel therapeutics, a critical need due to the prevalence and rapid spread of antibiotic resistance.
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Affiliation(s)
- Tshegofatso Ngwaga
- Division of Biology, Kansas State University, Manhattan, KS, United States
| | - Deepika Chauhan
- Division of Biology, Kansas State University, Manhattan, KS, United States
| | - Stephanie R Shames
- Division of Biology, Kansas State University, Manhattan, KS, United States
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12
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Yahr TL, Ellermeier CD. 25 th Annual Midwest Microbial Pathogenesis Conference. J Bacteriol 2019; 201:e00239-19. [PMID: 30988032 PMCID: PMC6597398 DOI: 10.1128/jb.00239-19] [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] [Indexed: 11/20/2022] Open
Abstract
The 25th annual Midwest Microbial Pathogenesis Conference (MMPC) was held at the University of Iowa from 28 to 30 September 2018. The conference has a long-standing tradition of providing scientists from the Midwest with a forum to present and discuss cutting-edge advances in microbial pathogenesis with particular focus on bacterial interactions with the environment, host, and other microbes. This review summarizes the genesis of the MMPC, topics presented at the conference, and articles found in the special MMPC sections of this issue of the Journal of Bacteriology.
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Affiliation(s)
- Timothy L. Yahr
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
| | - Craig D. Ellermeier
- Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA
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