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Wang Z, Nie K, Liang Y, Niu J, Yu X, Zhang O, Liu L, Shi X, Wang Y, Feng X, Zhu Y, Wang P, Cheng G. A mosquito salivary protein-driven influx of myeloid cells facilitates flavivirus transmission. EMBO J 2024; 43:1690-1721. [PMID: 38378891 PMCID: PMC11066113 DOI: 10.1038/s44318-024-00056-x] [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: 07/11/2023] [Revised: 01/29/2024] [Accepted: 02/02/2024] [Indexed: 02/22/2024] Open
Abstract
Mosquitoes transmit many disease-relevant flaviviruses. Efficient viral transmission to mammalian hosts requires mosquito salivary factors. However, the specific salivary components facilitating viral transmission and their mechanisms of action remain largely unknown. Here, we show that a female mosquito salivary gland-specific protein, here named A. aegypti Neutrophil Recruitment Protein (AaNRP), facilitates the transmission of Zika and dengue viruses. AaNRP promotes a rapid influx of neutrophils, followed by virus-susceptible myeloid cells toward mosquito bite sites, which facilitates establishment of local infection and systemic dissemination. Mechanistically, AaNRP engages TLR1 and TLR4 of skin-resident macrophages and activates MyD88-dependent NF-κB signaling to induce the expression of neutrophil chemoattractants. Inhibition of MyD88-NF-κB signaling with the dietary phytochemical resveratrol reduces AaNRP-mediated enhancement of flavivirus transmission by mosquitoes. These findings exemplify how salivary components can aid viral transmission, and suggest a potential prophylactic target.
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Affiliation(s)
- Zhaoyang Wang
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China
- Institute of Infectious Diseases, Shenzhen Bay Laboratory, Shenzhen, 518000, China
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Kaixiao Nie
- Department of Pathogen Biology, School of Basic Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, 250000, China
| | - Yan Liang
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jichen Niu
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China
| | - Xi Yu
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Oujia Zhang
- Department of Pathogen Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100086, China
| | - Long Liu
- Institute of Virology, Hubei University of Medicine, Shiyan, 442000, China
- Department of Infectious Diseases, Renmin Hospital, School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, 442000, China
| | - Xiaolu Shi
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Yibaina Wang
- China National Center for Food Safety Risk Assessment, Beijing, 100022, China
| | - Xuechun Feng
- Institute of Infectious Diseases, Shenzhen Bay Laboratory, Shenzhen, 518000, China
| | - Yibin Zhu
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China
| | - Penghua Wang
- Department of Immunology, School of Medicine, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Gong Cheng
- New Cornerstone Science Laboratory, Tsinghua University-Peking University Joint Center for Life Sciences, School of Basic Medical Sciences, Tsinghua University, Beijing, 100084, China.
- Institute of Infectious Diseases, Shenzhen Bay Laboratory, Shenzhen, 518000, China.
- Institute of Pathogenic Organisms, Shenzhen Center for Disease Control and Prevention, Shenzhen, 518055, China.
- Southwest United Graduate School, Kunming, 650092, China.
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2
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Yang JL, Li D, Zhan XY. Concept about the Virulence Factor of Legionella. Microorganisms 2022; 11:microorganisms11010074. [PMID: 36677366 PMCID: PMC9867486 DOI: 10.3390/microorganisms11010074] [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] [Received: 11/30/2022] [Revised: 12/23/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
Pathogenic species of Legionella can infect human alveolar macrophages through Legionella-containing aerosols to cause a disease called Legionellosis, which has two forms: a flu-like Pontiac fever and severe pneumonia named Legionnaires' disease (LD). Legionella is an opportunistic pathogen that frequently presents in aquatic environments as a biofilm or protozoa parasite. Long-term interaction and extensive co-evolution with various genera of amoebae render Legionellae pathogenic to infect humans and also generate virulence differentiation and heterogeneity. Conventionally, the proteins involved in initiating replication processes and human macrophage infections have been regarded as virulence factors and linked to pathogenicity. However, because some of the virulence factors are associated with the infection of protozoa and macrophages, it would be more accurate to classify them as survival factors rather than virulence factors. Given that the molecular basis of virulence variations among non-pathogenic, pathogenic, and highly pathogenic Legionella has not yet been elaborated from the perspective of virulence factors, a comprehensive explanation of how Legionella infects its natural hosts, protozoans, and accidental hosts, humans is essential to show a novel concept regarding the virulence factor of Legionella. In this review, we overviewed the pathogenic development of Legionella from protozoa, the function of conventional virulence factors in the infections of protozoa and macrophages, the host's innate immune system, and factors involved in regulating the host immune response, before discussing a probably new definition for the virulence factors of Legionella.
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3
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Horváth E, Rossi L, Mercier C, Lehmann C, Sienkiewicz A, Forró L. Photocatalytic Nanowires-Based Air Filter: Towards Reusable Protective Masks. ADVANCED FUNCTIONAL MATERIALS 2020; 30:2004615. [PMID: 32837497 PMCID: PMC7435547 DOI: 10.1002/adfm.202004615] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/02/2020] [Indexed: 05/19/2023]
Abstract
In the last couple decades, several viral outbreaks resulting in epidemics and pandemics with thousands of human causalities have been witnessed. The current Covid-19 outbreak represents an unprecedented crisis. In stopping the virus' spread, it is fundamental to have personal protective equipment and disinfected surfaces. Here, the development of a TiO2 nanowires (TiO2NWs) based filter is reported, which it is believed will work extremely well for personal protective equipment (PPE), as well as for a new generation of air conditioners and air purifiers. Its efficiency relies on the photocatalytic generation of high levels of reactive oxygen species (ROS) upon UV illumination, and on a particularly high dielectric constant of TiO2, which is of paramount importance for enhanced wettability by the water droplets carrying the germs. The filter pore sizes can be tuned by processing TiO2NWs into filter paper. The kilogram-scale production capability of TiO2NWs gives credibility to its massive application potentials.
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Affiliation(s)
- Endre Horváth
- Laboratory of Physics of Complex MatterEcole Polytechnique Fédérale de LausanneLausanne1015Switzerland
| | - Lídia Rossi
- Laboratory of Physics of Complex MatterEcole Polytechnique Fédérale de LausanneLausanne1015Switzerland
| | - Cyprien Mercier
- Laboratory of Physics of Complex MatterEcole Polytechnique Fédérale de LausanneLausanne1015Switzerland
| | - Caroline Lehmann
- Laboratory of Physics of Living MatterEcole Polytechnique Fédérale de LausanneLausanne1015Switzerland
| | - Andrzej Sienkiewicz
- Laboratory of Physics of Complex MatterEcole Polytechnique Fédérale de LausanneLausanne1015Switzerland
- ADSresonancesPréverenges1028Switzerland
| | - László Forró
- Laboratory of Physics of Complex MatterEcole Polytechnique Fédérale de LausanneLausanne1015Switzerland
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4
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He TT, Zhou Y, Liu YL, Li DY, Nie P, Li AH, Xie HX. Edwardsiella piscicida
type III protein EseJ suppresses apoptosis through down regulating type 1 fimbriae, which stimulate the cleavage of caspase‐8. Cell Microbiol 2020; 22:e13193. [DOI: 10.1111/cmi.13193] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 01/24/2020] [Accepted: 02/10/2020] [Indexed: 01/13/2023]
Affiliation(s)
- Tian Tian He
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of HydrobiologyChinese Academy of Sciences Wuhan China
- University of Chinese Academy of Sciences Beijing China
| | - Ying Zhou
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of HydrobiologyChinese Academy of Sciences Wuhan China
- University of Chinese Academy of Sciences Beijing China
| | - Ying Li Liu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of HydrobiologyChinese Academy of Sciences Wuhan China
- University of Chinese Academy of Sciences Beijing China
| | - Duan You Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of HydrobiologyChinese Academy of Sciences Wuhan China
- University of Chinese Academy of Sciences Beijing China
| | - Pin Nie
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of HydrobiologyChinese Academy of Sciences Wuhan China
- Laboratory for Marine Biology and BiotechnologyPilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao China
- School of Marine Science and EngineeringQingdao Agricultural University Qingdao China
| | - Ai Hua Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of HydrobiologyChinese Academy of Sciences Wuhan China
| | - Hai Xia Xie
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of HydrobiologyChinese Academy of Sciences Wuhan China
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5
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Yang C, McDermot DS, Pasricha S, Brown AS, Bedoui S, Lenz LL, van Driel IR, Hartland EL. IFNγ receptor down-regulation facilitates Legionella survival in alveolar macrophages. J Leukoc Biol 2020; 107:273-284. [PMID: 31793076 PMCID: PMC8015206 DOI: 10.1002/jlb.4ma1019-152r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 10/10/2019] [Accepted: 10/30/2019] [Indexed: 12/17/2022] Open
Abstract
Legionella pneumophila is an opportunistic human pathogen and causative agent of the acute pneumonia known as Legionnaire's disease. Upon inhalation, the bacteria replicate in alveolar macrophages (AM), within an intracellular vacuole termed the Legionella-containing vacuole. We recently found that, in vivo, IFNγ was required for optimal clearance of intracellular L. pneumophila by monocyte-derived cells (MC), but the cytokine did not appear to influence clearance by AM. Here, we report that during L. pneumophila lung infection, expression of the IFNγ receptor subunit 1 (IFNGR1) is down-regulated in AM and neutrophils, but not MC, offering a possible explanation for why AM are unable to effectively restrict L. pneumophila replication in vivo. To test this, we used mice that constitutively express IFNGR1 in AM and found that prevention of IFNGR1 down-regulation enhanced the ability of AM to restrict L. pneumophila intracellular replication. IFNGR1 down-regulation was independent of the type IV Dot/Icm secretion system of L. pneumophila indicating that bacterial effector proteins were not involved. In contrast to previous work, we found that signaling via type I IFN receptors was not required for IFNGR1 down-regulation in macrophages but rather that MyD88- or Trif- mediated NF-κB activation was required. This work has uncovered an alternative signaling pathway responsible for IFNGR1 down-regulation in macrophages during bacterial infection.
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Affiliation(s)
- Chao Yang
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Daniel S McDermot
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Denver, Colorado, USA
| | - Shivani Pasricha
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Australia
| | - Andrew S Brown
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Sammy Bedoui
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Laurel L Lenz
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Denver, Colorado, USA
| | - Ian R van Driel
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Elizabeth L Hartland
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Australia
- Department of Molecular and Translational Science, Monash University, Melbourne, Victoria, Australia
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6
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Viewing Legionella pneumophila Pathogenesis through an Immunological Lens. J Mol Biol 2019; 431:4321-4344. [PMID: 31351897 DOI: 10.1016/j.jmb.2019.07.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 06/25/2019] [Accepted: 07/13/2019] [Indexed: 12/14/2022]
Abstract
Legionella pneumophila is the causative agent of the severe pneumonia Legionnaires' disease. L. pneumophila is ubiquitously found in freshwater environments, where it replicates within free-living protozoa. Aerosolization of contaminated water supplies allows the bacteria to be inhaled into the human lung, where L. pneumophila can be phagocytosed by alveolar macrophages and replicate intracellularly. The Dot/Icm type IV secretion system (T4SS) is one of the key virulence factors required for intracellular bacterial replication and subsequent disease. The Dot/Icm apparatus translocates more than 300 effector proteins into the host cell cytosol. These effectors interfere with a variety of cellular processes, thus enabling the bacterium to evade phagosome-lysosome fusion and establish an endoplasmic reticulum-derived Legionella-containing vacuole, which facilitates bacterial replication. In turn, the immune system has evolved numerous strategies to recognize intracellular bacteria such as L. pneumophila, leading to potent inflammatory responses that aid in eliminating infection. This review aims to provide an overview of L. pneumophila pathogenesis in the context of the host immune response.
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7
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Hayek I, Fischer F, Schulze-Luehrmann J, Dettmer K, Sobotta K, Schatz V, Kohl L, Boden K, Lang R, Oefner PJ, Wirtz S, Jantsch J, Lührmann A. Limitation of TCA Cycle Intermediates Represents an Oxygen-Independent Nutritional Antibacterial Effector Mechanism of Macrophages. Cell Rep 2019; 26:3502-3510.e6. [DOI: 10.1016/j.celrep.2019.02.103] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 12/16/2018] [Accepted: 02/25/2019] [Indexed: 10/27/2022] Open
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8
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Nelson RH, Nelson DE. Signal Distortion: How Intracellular Pathogens Alter Host Cell Fate by Modulating NF-κB Dynamics. Front Immunol 2018; 9:2962. [PMID: 30619320 PMCID: PMC6302744 DOI: 10.3389/fimmu.2018.02962] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Accepted: 12/03/2018] [Indexed: 01/17/2023] Open
Abstract
By uncovering complex dynamics in the expression or localization of transcriptional regulators in single cells that were otherwise hidden at the population level, live cell imaging has transformed our understanding of how cells sense and orchestrate appropriate responses to changes in their internal state or extracellular environment. This has proved particularly true for the nuclear factor-kappaB (NF-κB) family of transcription factors, key regulators of the inflammatory response and innate immune function, which are capable of encoding information about the mode and intensity of stimuli in the dynamics of NF-κB nuclear accumulation and loss. While live cell imaging continues to serve as a useful tool in ongoing efforts to characterize the feedbacks that shape these dynamics and to connect dynamics to downstream gene expression, it is also proving invaluable for recent studies that seek to determine how intracellular pathogens subvert NF-κB signaling to survive and replicate within host cells by providing quantitative information about the pathogen and changes in NF-κB activity during different stages of an infection. Here, we provide a brief overview of NF-κB signaling in innate immune cells and review recent literature that uses live imaging to investigate the mechanisms by which bacterial and yeast pathogens modulate NF-κB in a variety of different host cell types to evade destruction or maintain the viability of an intracellular growth niche.
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Affiliation(s)
- Rachel H Nelson
- Cellular Generation and Phenotyping Core Facility, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - David E Nelson
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, United States
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9
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Best AM, Abu Kwaik Y. Evasion of phagotrophic predation by protist hosts and innate immunity of metazoan hosts by Legionella pneumophila. Cell Microbiol 2018; 21:e12971. [PMID: 30370624 DOI: 10.1111/cmi.12971] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/08/2018] [Accepted: 10/24/2018] [Indexed: 12/18/2022]
Abstract
Legionella pneumophila is a ubiquitous environmental bacterium that has evolved to infect and proliferate within amoebae and other protists. It is thought that accidental inhalation of contaminated water particles by humans is what has enabled this pathogen to proliferate within alveolar macrophages and cause pneumonia. However, the highly evolved macrophages are equipped with more sophisticated innate defence mechanisms than are protists, such as the evolution of phagotrophic feeding into phagocytosis with more evolved innate defence processes. Not surprisingly, the majority of proteins involved in phagosome biogenesis (~80%) have origins in the phagotrophy stage of evolution. There are a plethora of highly evolved cellular and innate metazoan processes, not represented in protist biology, that are modulated by L. pneumophila, including TLR2 signalling, NF-κB, apoptotic and inflammatory processes, histone modification, caspases, and the NLRC-Naip5 inflammasomes. Importantly, L. pneumophila infects haemocytes of the invertebrate Galleria mellonella, kill G. mellonella larvae, and proliferate in and kill Drosophila adult flies and Caenorhabditis elegans. Although coevolution with protist hosts has provided a substantial blueprint for L. pneumophila to infect macrophages, we discuss the further evolutionary aspects of coevolution of L. pneumophila and its adaptation to modulate various highly evolved innate metazoan processes prior to becoming a human pathogen.
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Affiliation(s)
- Ashley M Best
- Department of Microbiology and Immunology, College of Medicine, University of Louisville, Louisville, Kentucky
| | - Yousef Abu Kwaik
- Department of Microbiology and Immunology, College of Medicine, University of Louisville, Louisville, Kentucky.,Center for Predictive Medicine, College of Medicine, University of Louisville, Louisville, Kentucky
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10
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Legionella pneumophila inhibits immune signalling via MavC-mediated transglutaminase-induced ubiquitination of UBE2N. Nat Microbiol 2018; 4:134-143. [PMID: 30420781 PMCID: PMC6294664 DOI: 10.1038/s41564-018-0282-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 10/03/2018] [Indexed: 01/16/2023]
Abstract
The bacterial pathogen Legionella pneumophila modulates host immunity using effectors translocated by its Dot/Icm transporter to facilitate its intracellular replication. A number of these effectors employ diverse mechanisms to interfere with protein ubiquitination, a posttranslational modification essential for immunity. Here we found that L. pneumophila induces monoubiquitination of the E2 enzyme UBE2N by its Dot/Icm substrate MavC(Lpg2147). We demonstrate that MavC is a transglutaminase that catalyzes covalent linkage of ubiquitin to Lys92 and Lys94 of UBE2N via Gln40. Similar to canonical transglutaminases, MavC possess deamidase activity that targets ubiquitin at Gln40. We identified Cys74 as the catalytic residue for both ubiquitination and deamidation activities. Furthermore, ubiquitination of UBE2N by MavC abolishes its activity in the formation of K63-type polyubiquitin chains, which dampens NFκB signaling in the initial phase of bacterial infection. Our results reveal an unprecedented mechanism of modulating host immunity by modifying a key ubiquitination enzyme by ubiquitin transglutamination.
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11
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Abstract
Within the human host, Legionella pneumophila replicates within alveolar macrophages, leading to pneumonia. However, L. pneumophila is an aquatic generalist pathogen that replicates within a wide variety of protist hosts, including amoebozoa, percolozoa, and ciliophora. The intracellular lifestyles of L. pneumophila within the two evolutionarily distant hosts macrophages and protists are remarkably similar. Coevolution with numerous protist hosts has shaped plasticity of the genome of L. pneumophila, which harbors numerous proteins encoded by genes acquired from primitive eukaryotic hosts through interkingdom horizontal gene transfer. The Dot/Icm type IVb translocation system translocates ∼6,000 effectors among Legionella species and >320 effector proteins in L. pneumophila into host cells to modulate a plethora of cellular processes to create proliferative niches. Since many of the effectors have likely evolved to modulate cellular processes of primitive eukaryotic hosts, it is not surprising that most of the effectors do not contribute to intracellular growth within human macrophages. Some of the effectors may modulate highly conserved eukaryotic processes, while others may target protist-specific processes that are absent in mammals. The lack of studies to determine the role of the effectors in adaptation of L. pneumophila to various protists has hampered the progress to determine the function of most of these effectors, which are routinely studied in mouse or human macrophages. Since many protists restrict L. pneumophila, utilization of such hosts can also be instrumental in deciphering the mechanisms of failure of L. pneumophila to overcome restriction of certain protist hosts. Here, we review the interaction of L. pneumophila with its permissive and restrictive protist environmental hosts and outline the accomplishments as well as gaps in our knowledge of L. pneumophila-protist host interaction and L. pneumophila's evolution to become a human pathogen.
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Affiliation(s)
- Ashley Best
- Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, USA
| | - Yousef Abu Kwaik
- Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, USA
- Center for Predictive Medicine, University of Louisville, Louisville, Kentucky, USA
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12
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Wang H, Lu J, Li K, Ren H, Shi Y, Qin T, Duan X, Fang M. The virulence of Legionella pneumophila is positively correlated with its ability to stimulate NF-κB activation. Future Microbiol 2018; 13:1247-1259. [PMID: 30238775 DOI: 10.2217/fmb-2018-0051] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
AIM Our work is to study the correlation between the virulence of different Legionella pneumophila in mouse model and its ability to activate NF-κB signaling pathway in vitro. MATERIALS & METHODS We measured the abilities of different strains of L. pneumophila to induce the activation of NF-κB signaling pathway in vitro. By using A/J mice, we also detected the virulence of different strains in vivo. RESULTS & CONCLUSION We demonstrated that different strains of L. pneumophila induce different levels of activation to NF-κB signaling pathway in vitro. We also found that L. pneumophila strain induced higher NF-κB activation in vitro showed more severe weight losses, higher mortality, more severe lung inflammation and higher levels of serum cytokines production in mice.
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Affiliation(s)
- Haoyu Wang
- CAS Key Laboratory of Pathogenic Microbiology & Immunology, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing 100101, PR China.,Institute of Physical Science & Information Technology, Anhui University, Hefei 230601, PR China
| | - Jiao Lu
- CAS Key Laboratory of Pathogenic Microbiology & Immunology, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing 100101, PR China.,University of Chinese Academy of Sciences, Beijing 100101, PR China
| | - Kaili Li
- CAS Key Laboratory of Pathogenic Microbiology & Immunology, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing 100101, PR China.,Institute of Physical Science & Information Technology, Anhui University, Hefei 230601, PR China
| | - Hongyu Ren
- State Key Laboratory for Infectious Disease Prevention & Control, National Institute for Communicable Disease Control & Prevention, Chinese Centre for Disease Control & Prevention, Beijing 102206, PR China
| | - Yi Shi
- CAS Key Laboratory of Pathogenic Microbiology & Immunology, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing 100101, PR China
| | - Tian Qin
- State Key Laboratory for Infectious Disease Prevention & Control, National Institute for Communicable Disease Control & Prevention, Chinese Centre for Disease Control & Prevention, Beijing 102206, PR China
| | - Xuefeng Duan
- CAS Key Laboratory of Pathogenic Microbiology & Immunology, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing 100101, PR China
| | - Min Fang
- CAS Key Laboratory of Pathogenic Microbiology & Immunology, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing 100101, PR China.,International College, University of Chinese Academy of Sciences, Beijing 100101, PR China
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13
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The Type II Secretion System of Legionella pneumophila Dampens the MyD88 and Toll-Like Receptor 2 Signaling Pathway in Infected Human Macrophages. Infect Immun 2017; 85:IAI.00897-16. [PMID: 28138020 DOI: 10.1128/iai.00897-16] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/24/2017] [Indexed: 12/25/2022] Open
Abstract
Previously, we reported that mutants of Legionella pneumophila lacking a type II secretion (T2S) system elicit higher levels of cytokines (e.g., interleukin-6 [IL-6]) following infection of U937 cells, a human macrophage-like cell line. We now show that this effect of T2S is also manifest upon infection of human THP-1 macrophages and peripheral blood monocytes but does not occur during infection of murine macrophages. Supporting the hypothesis that T2S acts to dampen the triggering of an innate immune response, we observed that the mitogen-activated protein kinase (MAPK) and nuclear transcription factor kappa B (NF-κB) pathways are more highly stimulated upon infection with the T2S mutant than upon infection with the wild type. By using short hairpin RNA to deplete proteins involved in specific pathogen-associated molecular pattern (PAMP) recognition pathways, we determined that the dampening effect of the T2S system was not dependent on nucleotide binding oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible protein I (RIG-I)-like receptors (RLRs), double-stranded RNA (dsRNA)-dependent protein kinase receptor (PKR), or TIR domain-containing adaptor inducing interferon beta (TRIF) signaling or an apoptosis-associated speck-like protein containing a CARD (ASC)- or caspase-4-dependent inflammasome. However, the dampening effect of T2S on IL-6 production was significantly reduced upon gene knockdown of myeloid differentiation primary response 88 (MyD88), TANK binding kinase 1 (TBK1), or Toll-like receptor 2 (TLR2). These data indicate that the L. pneumophila T2S system dampens the signaling of the TLR2 pathway in infected human macrophages. We also document the importance of PKR, TRIF, and TBK1 in cytokine secretion during L. pneumophila infection of macrophages.
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14
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Mahapatra S, Gallaher B, Smith SC, Graham JG, Voth DE, Shaw EI. Coxiella burnetii Employs the Dot/Icm Type IV Secretion System to Modulate Host NF-κB/RelA Activation. Front Cell Infect Microbiol 2016; 6:188. [PMID: 28066723 PMCID: PMC5165255 DOI: 10.3389/fcimb.2016.00188] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 12/02/2016] [Indexed: 12/17/2022] Open
Abstract
Coxiella burnetii is the causative agent of Q fever and an obligate intracellular pathogen in nature that survives and grows in a parasitophorous vacuole (PV) within eukaryotic host cells. C. burnetii promotes intracellular survival by subverting apoptotic and pro-inflammatory signaling pathways that are typically regulated by nuclear transcription factor-κB (NF-κB). We and others have demonstrated that C. burnetii NMII proteins inhibit expression of pro-inflammatory cytokines and induce expression of anti-apoptotic genes during infection. Here, we demonstrate that C. burnetii promotes intracellular survival by modulating NF-κB subunit p65 (RelA) phosphorylation, and thus activation, in a Type Four B Secretion System (T4BSS)-dependent manner. Immunoblot analysis of RelA phosphorylated at serine-536 demonstrated that C. burnetii increases NF-κB activation via the canonical pathway. However, RelA phosphorylation levels were even higher in infected cells where bacterial protein or mRNA synthesis was inhibited. Importantly, we demonstrate that inhibition of RelA phosphorylation impairs PV formation and C. burnetii growth. We found that a T4BSS-defective mutant (CbΔdotA) elicited phosphorylated RelA levels similar to those of wild type C. burnetii infection treated with Chloramphenicol. Moreover, cells infected with CbΔdotA or wild type C. burnetii treated with Chloramphenicol showed similar levels of GFP-RelA nuclear localization, and significantly increased localization compared to wild type C. burnetii infection. These data indicate that without de novo protein synthesis and a functional T4BSS, C. burnetii is unable to modulate NF-κB activation, which is crucial for optimal intracellular growth.
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Affiliation(s)
- Saugata Mahapatra
- Department of Microbiology and Molecular genetics, Oklahoma State UniversityStillwater, OK, USA
| | - Brandi Gallaher
- Department of Microbiology and Molecular genetics, Oklahoma State UniversityStillwater, OK, USA
| | - Sydni Caet Smith
- Department of Microbiology and Molecular genetics, Oklahoma State UniversityStillwater, OK, USA
| | - Joseph G. Graham
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences (UAMS)Little Rock, AR, USA
| | - Daniel E. Voth
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences (UAMS)Little Rock, AR, USA
| | - Edward I. Shaw
- Department of Microbiology and Molecular genetics, Oklahoma State UniversityStillwater, OK, USA
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Ramos-Marquès E, Zambrano S, Tiérrez A, Bianchi ME, Agresti A, García-Del Portillo F. Single-cell analyses reveal an attenuated NF-κB response in the Salmonella-infected fibroblast. Virulence 2016; 8:719-740. [PMID: 27575017 DOI: 10.1080/21505594.2016.1229727] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The eukaryotic transcriptional regulator Nuclear Factor kappa B (NF-κB) plays a central role in the defense to pathogens. Despite this, few studies have analyzed NF-κB activity in single cells during infection. Here, we investigated at the single cell level how NF-κB nuclear localization - a proxy for NF-κB activity - oscillates in infected and uninfected fibroblasts co-existing in cultures exposed to Salmonella enterica serovar Typhimurium. Fibroblasts were used due to the capacity of S. Typhimurium to persist in this cell type. Real-time dynamics of NF-κB was examined in microfluidics, which prevents cytokine accumulation. In this condition, infected (ST+) cells translocate NF-κB to the nucleus at higher rate than the uninfected (ST-) cells. Surprisingly, in non-flow (static) culture conditions, ST- fibroblasts exhibited higher NF-κB nuclear translocation than the ST+ population, with these latter cells turning refractory to external stimuli such as TNF-α or a second infection. Sorting of ST+ and ST- cell populations confirmed enhanced expression of NF-κB target genes such as IL1B, NFKBIA, TNFAIP3, and TRAF1 in uninfected (ST-) fibroblasts. These observations proved that S. Typhimurium dampens the NF-κB response in the infected fibroblast. Higher expression of SOCS3, encoding a "suppressor of cytokine signaling," was also observed in the ST+ population. Intracellular S. Typhimurium subverts NF-κB activity using protein effectors translocated by the secretion systems encoded by pathogenicity islands 1 (T1) and 2 (T2). T1 is required for regulating expression of SOCS3 and all NF-κB target genes analyzed whereas T2 displayed no role in the control of SOCS3 and IL1B expression. Collectively, these data demonstrate that S. Typhimurium attenuates NF-κB signaling in fibroblasts, an effect only perceptible when ST+ and ST- populations are analyzed separately. This tune-down in a central host defense might be instrumental for S. Typhimurium to establish intracellular persistent infections.
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Affiliation(s)
- Estel Ramos-Marquès
- a Laboratory of Intracellular Bacterial Pathogens , Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC) , Madrid , Spain
| | | | - Alberto Tiérrez
- a Laboratory of Intracellular Bacterial Pathogens , Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC) , Madrid , Spain
| | - Marco E Bianchi
- c Genetics and Cell Biology Division , San Raffaele Scientific Institute , Milan , Italy
| | - Alessandra Agresti
- c Genetics and Cell Biology Division , San Raffaele Scientific Institute , Milan , Italy
| | - Francisco García-Del Portillo
- a Laboratory of Intracellular Bacterial Pathogens , Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC) , Madrid , Spain
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Shin S. Innate Immunity to Intracellular Pathogens: Lessons Learned from Legionella pneumophila. ADVANCES IN APPLIED MICROBIOLOGY 2016; 79:43-71. [PMID: 22569517 DOI: 10.1016/b978-0-12-394318-7.00003-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Intracellular bacterial pathogens have the remarkable ability to manipulate host cell processes in order to establish a replicative niche within the host cell. In response, the host can initiate immune defenses that lead to the eventual restriction and clearance of intracellular infection. The bacterial pathogen Legionella pneumophila has evolved elaborate virulence mechanisms that allow for its survival inside protozoa within a specialized membrane-bound organelle. These strategies also enable L. pneumophila to survive and replicate within alveolar macrophages, and can result in the severe pneumonia Legionnaires' disease. Essential to L. pneumophila's intracellular lifestyle is a specialized type IV secretion system, termed Dot/Icm, that translocates bacterial effector proteins into host cells. The ease with which L. pneumophila can be genetically manipulated has facilitated the comparison of host responses to virulent and isogenic avirulent mutants lacking a functional Dot/Icm system. This has made L. pneumophila an excellent model for understanding how the host discriminates between pathogenic and nonpathogenic bacteria and for systematically dissecting host defense mechanisms against intracellular pathogens. In this chapter, I discuss a few examples demonstrating how the study of immune responses triggered specifically by the L. pneumophila type IV secretion system has provided unique insight into our understanding of host immunity against intracellular bacterial pathogens.
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Affiliation(s)
- Sunny Shin
- Department of Microbiology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, USA.
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Jung AL, Stoiber C, Herkt CE, Schulz C, Bertrams W, Schmeck B. Legionella pneumophila-Derived Outer Membrane Vesicles Promote Bacterial Replication in Macrophages. PLoS Pathog 2016; 12:e1005592. [PMID: 27105429 PMCID: PMC4841580 DOI: 10.1371/journal.ppat.1005592] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 04/01/2016] [Indexed: 02/07/2023] Open
Abstract
The formation and release of outer membrane vesicles (OMVs) is a phenomenon of Gram-negative bacteria. This includes Legionella pneumophila (L. pneumophila), a causative agent of severe pneumonia. Upon its transmission into the lung, L. pneumophila primarily infects and replicates within macrophages. Here, we analyzed the influence of L. pneumophila OMVs on macrophages. To this end, differentiated THP-1 cells were incubated with increasing doses of Legionella OMVs, leading to a TLR2-dependent classical activation of macrophages with the release of pro-inflammatory cytokines. Inhibition of TLR2 and NF-κB signaling reduced the induction of pro-inflammatory cytokines. Furthermore, treatment of THP-1 cells with OMVs prior to infection reduced replication of L. pneumophila in THP-1 cells. Blocking of TLR2 activation or heat denaturation of OMVs restored bacterial replication in the first 24 h of infection. With prolonged infection-time, OMV pre-treated macrophages became more permissive for bacterial replication than untreated cells and showed increased numbers of Legionella-containing vacuoles and reduced pro-inflammatory cytokine induction. Additionally, miRNA-146a was found to be transcriptionally induced by OMVs and to facilitate bacterial replication. Accordingly, IRAK-1, one of miRNA-146a's targets, showed prolonged activation-dependent degradation, which rendered THP-1 cells more permissive for Legionella replication. In conclusion, L. pneumophila OMVs are initially potent pro-inflammatory stimulators of macrophages, acting via TLR2, IRAK-1, and NF-κB, while at later time points, OMVs facilitate L. pneumophila replication by miR-146a-dependent IRAK-1 suppression. OMVs might thereby promote spreading of L. pneumophila in the host.
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Affiliation(s)
- Anna Lena Jung
- Institute for Lung Research, Universities of Giessen and Marburg Lung Center, Philipps-University Marburg, Member of the German Center for Lung Research (DZL), Marburg, Germany
| | - Cornelia Stoiber
- Institute for Virology, Philipps-University Marburg, Marburg, Germany
| | - Christina E. Herkt
- Institute for Lung Research, Universities of Giessen and Marburg Lung Center, Philipps-University Marburg, Member of the German Center for Lung Research (DZL), Marburg, Germany
| | - Christine Schulz
- Institute for Lung Research, Universities of Giessen and Marburg Lung Center, Philipps-University Marburg, Member of the German Center for Lung Research (DZL), Marburg, Germany
| | - Wilhelm Bertrams
- Institute for Lung Research, Universities of Giessen and Marburg Lung Center, Philipps-University Marburg, Member of the German Center for Lung Research (DZL), Marburg, Germany
| | - Bernd Schmeck
- Institute for Lung Research, Universities of Giessen and Marburg Lung Center, Philipps-University Marburg, Member of the German Center for Lung Research (DZL), Marburg, Germany
- Department of Medicine, Pulmonary and Critical Care Medicine, University Medical Center Giessen and Marburg, Philipps-University, Member of the German Center for Lung Research (DZL), Marburg, Germany
- * E-mail:
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18
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Abu Khweek A, Kanneganti A, C. Guttridge D D, Amer AO. The Sphingosine-1-Phosphate Lyase (LegS2) Contributes to the Restriction of Legionella pneumophila in Murine Macrophages. PLoS One 2016; 11:e0146410. [PMID: 26741365 PMCID: PMC4704736 DOI: 10.1371/journal.pone.0146410] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 12/16/2015] [Indexed: 12/16/2022] Open
Abstract
L. pneumophila is the causative agent of Legionnaires’ disease, a human illness characterized by severe pneumonia. In contrast to those derived from humans, macrophages derived from most mouse strains restrict L. pneumophila replication. The restriction of L. pneumophila replication has been shown to require bacterial flagellin, a component of the type IV secretion system as well as the cytosolic NOD-like receptor (NLR) Nlrc4/ Ipaf. These events lead to caspase-1 activation which, in turn, activates caspase-7. Following caspase-7 activation, the phagosome-containing L. pneumophila fuses with the lysosome, resulting in the restriction of L. pneumophila growth. The LegS2 effector is injected by the type IV secretion system and functions as a sphingosine 1-phosphate lyase. It is homologous to the eukaryotic sphingosine lyase (SPL), an enzyme required in the terminal steps of sphingolipid metabolism. Herein, we show that mice Bone Marrow-Derived Macrophages (BMDMs) and human Monocyte-Derived Macrophages (hMDMs) are more permissive to L. pneumophila legS2 mutants than wild-type (WT) strains. This permissiveness to L. pneumophila legS2 is neither attributed to abolished caspase-1, caspase-7 or caspase-3 activation, nor due to the impairment of phagosome-lysosome fusion. Instead, an infection with the legS2 mutant resulted in the reduction of some inflammatory cytokines and their corresponding mRNA; this effect is mediated by the inhibition of the nuclear transcription factor kappa-B (NF-κB). Moreover, BMDMs infected with L. pneumophila legS2 mutant showed elongated mitochondria that resembles mitochondrial fusion. Therefore, the absence of LegS2 effector is associated with reduced NF-κB activation and atypical morphology of mitochondria.
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Affiliation(s)
- Arwa Abu Khweek
- Birzeit University, Department of Biology and Biochemistry, West Bank, Palestine
- * E-mail:
| | - Apurva Kanneganti
- The Ohio State University, Department of Microbial Infection and Immunity, College of Medicine, Center for Microbial Interface Biology, Columbus, Ohio, United States of America
| | - Denis C. Guttridge D
- Human Cancer Genetics Program, Ohio State University, Columbus, Ohio, United States of America
| | - Amal O. Amer
- The Ohio State University, Department of Microbial Infection and Immunity, College of Medicine, Center for Microbial Interface Biology, Columbus, Ohio, United States of America
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Schell U, Simon S, Hilbi H. Inflammasome Recognition and Regulation of the Legionella Flagellum. Curr Top Microbiol Immunol 2016; 397:161-81. [PMID: 27460809 DOI: 10.1007/978-3-319-41171-2_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The Gram-negative bacterium Legionella pneumophila colonizes extracellular environmental niches and infects free-living protozoa. Upon inhalation into the human lung, the opportunistic pathogen grows in macrophages and causes a fulminant pneumonia termed Legionnaires' disease. L. pneumophila employs a biphasic life cycle, comprising a replicative, non-virulent, and a stationary, virulent form. In the latter phase, the pathogen produces a plethora of so-called effector proteins, which are injected into host cells, where they subvert pivotal processes and promote the formation of a distinct membrane-bound compartment, the Legionella-containing vacuole. In the stationary phase, the bacteria also produce a single monopolar flagellum and become motile. L. pneumophila flagellin is recognized by and triggers the host's NAIP5 (Birc1e)/NLRC4 (Ipaf) inflammasome, which leads to caspase-1 activation, pore formation, and pyroptosis. The production of L. pneumophila flagellin and pathogen-host interactions are controlled by a complex stationary phase regulatory network, detecting nutrient availability as well as the Legionella quorum sensing (Lqs) signaling compound LAI-1 (3-hydroxypentadecane-4-one). Thus, the small molecule LAI-1 coordinates L. pneumophila flagellin production and motility, inflammasome activation, and virulence.
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Affiliation(s)
- Ursula Schell
- Max von Pettenkofer Institute, Ludwig-Maximilians University, Pettenkoferstraße 9a, 80336, Munich, Germany
| | - Sylvia Simon
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30/32, 8006, Zürich, Switzerland
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Gloriastrasse 30/32, 8006, Zürich, Switzerland.
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20
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Simon S, Hilbi H. Subversion of Cell-Autonomous Immunity and Cell Migration by Legionella pneumophila Effectors. Front Immunol 2015; 6:447. [PMID: 26441958 PMCID: PMC4568765 DOI: 10.3389/fimmu.2015.00447] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 08/17/2015] [Indexed: 12/14/2022] Open
Abstract
Bacteria trigger host defense and inflammatory processes, such as cytokine production, pyroptosis, and the chemotactic migration of immune cells toward the source of infection. However, a number of pathogens interfere with these immune functions by producing specific so-called “effector” proteins, which are delivered to host cells via dedicated secretion systems. Air-borne Legionella pneumophila bacteria trigger an acute and potential fatal inflammation in the lung termed Legionnaires’ disease. The opportunistic pathogen L. pneumophila is a natural parasite of free-living amoebae, but also replicates in alveolar macrophages and accidentally infects humans. The bacteria employ the intracellular multiplication/defective for organelle trafficking (Icm/Dot) type IV secretion system and as many as 300 different effector proteins to govern host–cell interactions and establish in phagocytes an intracellular replication niche, the Legionella-containing vacuole. Some Icm/Dot-translocated effector proteins target cell-autonomous immunity or cell migration, i.e., they interfere with (i) endocytic, secretory, or retrograde vesicle trafficking pathways, (ii) organelle or cell motility, (iii) the inflammasome and programed cell death, or (iv) the transcription factor NF-κB. Here, we review recent mechanistic insights into the subversion of cellular immune functions by L. pneumophila.
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Affiliation(s)
- Sylvia Simon
- Institute of Medical Microbiology, University of Zürich , Zürich , Switzerland
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich , Zürich , Switzerland ; Max von Pettenkofer Institute, Ludwig-Maximilians University , Munich , Germany
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21
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So EC, Mattheis C, Tate EW, Frankel G, Schroeder GN. Creating a customized intracellular niche: subversion of host cell signaling by Legionella type IV secretion system effectors. Can J Microbiol 2015; 61:617-35. [PMID: 26059316 DOI: 10.1139/cjm-2015-0166] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The Gram-negative facultative intracellular pathogen Legionella pneumophila infects a wide range of different protozoa in the environment and also human alveolar macrophages upon inhalation of contaminated aerosols. Inside its hosts, it creates a defined and unique compartment, termed the Legionella-containing vacuole (LCV), for survival and replication. To establish the LCV, L. pneumophila uses its Dot/Icm type IV secretion system (T4SS) to translocate more than 300 effector proteins into the host cell. Although it has become apparent in the past years that these effectors subvert a multitude of cellular processes and allow Legionella to take control of host cell vesicle trafficking, transcription, and translation, the exact function of the vast majority of effectors still remains unknown. This is partly due to high functional redundancy among the effectors, which renders conventional genetic approaches to elucidate their role ineffective. Here, we review the current knowledge about Legionella T4SS effectors, highlight open questions, and discuss new methods that promise to facilitate the characterization of T4SS effector functions in the future.
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Affiliation(s)
- Ernest C So
- a MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK.,b Department of Chemistry, South Kensington Campus, Imperial College, London, SW7 2AZ, UK
| | - Corinna Mattheis
- a MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Edward W Tate
- b Department of Chemistry, South Kensington Campus, Imperial College, London, SW7 2AZ, UK
| | - Gad Frankel
- a MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Gunnar N Schroeder
- a MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
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22
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Price CTD, Abu Kwaik Y. The transcriptome of Legionella pneumophila-infected human monocyte-derived macrophages. PLoS One 2014; 9:e114914. [PMID: 25485627 PMCID: PMC4259488 DOI: 10.1371/journal.pone.0114914] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 11/15/2014] [Indexed: 11/19/2022] Open
Abstract
Background Legionella pneumophila is an intracellular bacterial pathogen that invades and replicates within alveolar macrophages through injection of ∼300 effector proteins by its Dot/Icm type IV translocation apparatus. The bona fide F-box protein, AnkB, is a nutritional virulence effector that triggers macrophages to generate a surplus of amino acids, which is essential for intravacuolar proliferation. Therefore, the ankB mutant represents a novel genetic tool to determine the transcriptional response of human monocyte-derived macrophages (hMDMs) to actively replicating L. pneumophila. Methodology/Principal Findings Here, we utilized total human gene microarrays to determine the global transcriptional response of hMDMs to infection by wild type or the ankB mutant of L. pneumophila. The transcriptomes of hMDMs infected with either actively proliferating wild type or non-replicative ankB mutant bacteria were remarkably similar. The transcriptome of infected hMDMs was predominated by up-regulation of inflammatory pathways (IL-10 anti-inflammatory, interferon signaling and amphoterin signaling), anti-apoptosis, and down-regulation of protein synthesis pathways. In addition, L. pneumophila modulated diverse metabolic pathways, particularly those associated with bio-active lipid metabolism, and SLC amino acid transporters expression. Conclusion/Significance Taken together, the hMDM transcriptional response to L. pneumophila is independent of intra-vacuolar replication of the bacteria and primarily involves modulation of the immune response and metabolic as well as nutritional pathways.
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Affiliation(s)
- Christopher T. D. Price
- Department of Microbiology and Immunology, University of Louisville, KY, 40202, United States of America
- * E-mail: (YAK); (CP)
| | - Yousef Abu Kwaik
- Department of Microbiology and Immunology, University of Louisville, KY, 40202, United States of America
- Center for Predictive Medicine, University of Louisville, KY, 40202, United States of America
- * E-mail: (YAK); (CP)
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Legionella pneumophila type IV effectors hijack the transcription and translation machinery of the host cell. Trends Cell Biol 2014; 24:771-8. [PMID: 25012125 DOI: 10.1016/j.tcb.2014.06.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 06/09/2014] [Accepted: 06/10/2014] [Indexed: 01/26/2023]
Abstract
Intracellular bacterial pathogens modulate the host response to persist and replicate inside a eukaryotic cell and cause disease. Legionella pneumophila, the causative agent of Legionnaires' disease, is present in freshwater environments and represents one of these pathogens. During coevolution with protozoan cells, L. pneumophila has acquired highly sophisticated and diverse strategies to hijack host cell processes. It secretes hundreds of effectors into the host cell, and these manipulate host signaling pathways and key cellular processes. Recently it has been shown that L. pneumophila is also able to alter the transcription and translation machinery of the host and to exploit epigenetic mechanisms in the cells it resides in to counteract host responses.
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24
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Teh BE, French CT, Chen Y, Chen IGJ, Wu TH, Sagullo E, Chiou PY, Teitell MA, Miller JF, Gan YH. Type three secretion system-mediated escape of Burkholderia pseudomallei into the host cytosol is critical for the activation of NFκB. BMC Microbiol 2014; 14:115. [PMID: 24884837 PMCID: PMC4026835 DOI: 10.1186/1471-2180-14-115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 04/25/2014] [Indexed: 11/24/2022] Open
Abstract
Background Burkholderia pseudomallei is the causative agent of melioidosis, a potentially fatal disease endemic in Southeast Asia and Northern Australia. This Gram-negative pathogen possesses numerous virulence factors including three “injection type” type three secretion systems (T3SSs). B. pseudomallei has been shown to activate NFκB in HEK293T cells in a Toll-like receptor and MyD88 independent manner that requires T3SS gene cluster 3 (T3SS3 or T3SSBsa). However, the mechanism of how T3SS3 contributes to NFκB activation is unknown. Results Known T3SS3 effectors are not responsible for NFκB activation. Furthermore, T3SS3-null mutants are able to activate NFκB almost to the same extent as wildtype bacteria at late time points of infection, corresponding to delayed escape into the cytosol. NFκB activation also occurs when bacteria are delivered directly into the cytosol by photothermal nanoblade injection. Conclusions T3SS3 does not directly activate NFκB but facilitates bacterial escape into the cytosol where the host is able to sense the presence of the pathogen through cytosolic sensors leading to NFκB activation.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
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25
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Human lung tissue explants reveal novel interactions during Legionella pneumophila infections. Infect Immun 2013; 82:275-85. [PMID: 24166955 DOI: 10.1128/iai.00703-13] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Histological and clinical investigations describe late stages of Legionnaires' disease but cannot characterize early events of human infection. Cellular or rodent infection models lack the complexity of tissue or have nonhuman backgrounds. Therefore, we developed and applied a novel model for Legionella pneumophila infection comprising living human lung tissue. We stimulated lung explants with L. pneumophila strains and outer membrane vesicles (OMVs) to analyze tissue damage, bacterial replication, and localization as well as the transcriptional response of infected tissue. Interestingly, we found that extracellular adhesion of L. pneumophila to the entire alveolar lining precedes bacterial invasion and replication in recruited macrophages. In contrast, OMVs predominantly bound to alveolar macrophages. Specific damage to septa and epithelia increased over 48 h and was stronger in wild-type-infected and OMV-treated samples than in samples infected with the replication-deficient, type IVB secretion-deficient DotA(-) strain. Transcriptome analysis of lung tissue explants revealed a differential regulation of 2,499 genes after infection. The transcriptional response included the upregulation of uteroglobin and the downregulation of the macrophage receptor with collagenous structure (MARCO). Immunohistochemistry confirmed the downregulation of MARCO at sites of pathogen-induced tissue destruction. Neither host factor has ever been described in the context of L. pneumophila infections. This work demonstrates that the tissue explant model reproduces realistic features of Legionnaires' disease and reveals new functions for bacterial OMVs during infection. Our model allows us to characterize early steps of human infection which otherwise are not feasible for investigations.
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Belogolova E, Bauer B, Pompaiah M, Asakura H, Brinkman V, Ertl C, Bartfeld S, Nechitaylo TY, Haas R, Machuy N, Salama N, Churin Y, Meyer TF. Helicobacter pylori outer membrane protein HopQ identified as a novel T4SS-associated virulence factor. Cell Microbiol 2013; 15:1896-912. [PMID: 23782461 DOI: 10.1111/cmi.12158] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 06/11/2013] [Accepted: 06/11/2013] [Indexed: 12/13/2022]
Abstract
Helicobacter pylori is a bacterial pathogen that colonizes the gastric niche of ∼ 50% of the human population worldwide and is known to cause peptic ulceration and gastric cancer. Pathology of infection strongly depends on a cag pathogenicity island (cagPAI)-encoded type IV secretion system (T4SS). Here, we aimed to identify as yet unknown bacterial factors involved in cagPAI effector function and performed a large-scale screen of an H. pylori transposon mutant library using activation of the pro-inflammatory transcription factor NF-κB in human gastric epithelial cells as a measure of T4SS function. Analysis of ∼ 3000 H. pylori mutants revealed three non-cagPAI genes that affected NF-κB nuclear translocation. Of these, the outer membrane protein HopQ from H. pylori strain P12 was essential for CagA translocation and for CagA-mediated host cell responses such as formation of the hummingbird phenotype and cell scattering. Besides that, deletion of hopQ reduced T4SS-dependent activation of NF-κB, induction of MAPK signalling and secretion of interleukin 8 (IL-8) in the host cells, but did not affect motility or the quantity of bacteria attached to host cells. Hence, we identified HopQ as a non-cagPAI-encoded cofactor of T4SS function.
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Affiliation(s)
- Elena Belogolova
- Department of Molecular Biology, Max Planck Institute for Infection Biology, D-10117, Berlin, Germany
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27
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The Dot/Icm effector SdhA is necessary for virulence of Legionella pneumophila in Galleria mellonella and A/J mice. Infect Immun 2013; 81:2598-605. [PMID: 23649096 DOI: 10.1128/iai.00296-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Legionella pneumophila is an intracellular bacterium that resides within amoebae and macrophages in a specialized compartment termed the Legionella-containing vacuole (LCV). As well as providing an intracellular niche for replication, the LCV helps to prevent the release of bacterial components into the cytoplasm. Recognition of these components as danger signals by the host activates immune responses leading to clearance of the bacterium. Here, we examined the role of two important virulence factors of L. pneumophila, the potent danger signal flagellin and the translocated Dot/Icm type IVB secretion system effector SdhA, which is crucial to maintain LCV integrity, in the Galleria mellonella infection model. We demonstrate that flagellin expression does not contribute to virulence, replication, or induction of clearance mechanisms. Conversely, SdhA expression is important for virulence. We found that in the absence of SdhA, the LCV in hemocytes showed signs of instability and leakage. Furthermore, in contrast to wild-type L. pneumophila, a ΔsdhA mutant caused a transient depletion of hemocytes and reduced mortality. Analysis of the ΔsdhA mutant in the A/J mouse model also showed a significant replication defect. Together, our data underline the crucial importance of SdhA in infection across different model organisms.
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Effector-triggered versus pattern-triggered immunity: how animals sense pathogens. Nat Rev Immunol 2013; 13:199-206. [PMID: 23411798 DOI: 10.1038/nri3398] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A fundamental question regarding any immune system is how it can discriminate between pathogens and non-pathogens. Here, we discuss how this discrimination can be mediated by a surveillance system distinct from pattern-recognition receptors that recognize conserved microbial patterns. It can be based instead on the ability of the host to sense perturbations in host cells induced by bacterial toxins or 'effectors' that are encoded by pathogenic microorganisms. Such 'effector-triggered immunity' was previously demonstrated mainly in plants, but recent data confirm that animals can also use this strategy.
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Liu M, Haenssler E, Uehara T, Losick VP, Park JT, Isberg RR. The Legionella pneumophila EnhC protein interferes with immunostimulatory muramyl peptide production to evade innate immunity. Cell Host Microbe 2013; 12:166-76. [PMID: 22901537 PMCID: PMC3678716 DOI: 10.1016/j.chom.2012.06.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 04/27/2012] [Accepted: 06/04/2012] [Indexed: 12/22/2022]
Abstract
Successful pathogens have evolved to evade innate immune recognition of microbial molecules by pattern recognition receptors (PRR), which control microbial growth in host tissues. Upon Legionella pneumophila infection of macrophages, the cytosolic PRR Nod1 recognizes anhydro-disaccharide-tetrapeptide (anhDSTP) generated by soluble lytic transglycosylase (SltL), the predominant bacterial peptidoglycan degrading enzyme, to activate NF-κB-dependent innate immune responses. We show that L. pneumophila periplasmic protein EnhC, which is uniquely required for bacterial replication within macrophages, interferes with SltL to lower anhDSTP production. L. pneumophila mutant strains lacking EnhC (ΔenhC) increase Nod1-dependent NF-κB activation in host cells, while reducing SltL activity in a ΔenhC strain restores intracellular bacterial growth. Further, L. pneumophila ΔenhC is specifically rescued in Nod1- but not Nod2-deficient macrophages, arguing that EnhC facilitates evasion from Nod1 recognition. These results indicate that a bacterial pathogen regulates peptidoglycan degradation to control the production of PRR ligands and evade innate immune recognition.
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Affiliation(s)
- Mingyu Liu
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02115, USA
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Escoll P, Rolando M, Gomez-Valero L, Buchrieser C. From amoeba to macrophages: exploring the molecular mechanisms of Legionella pneumophila infection in both hosts. Curr Top Microbiol Immunol 2013; 376:1-34. [PMID: 23949285 DOI: 10.1007/82_2013_351] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Legionella pneumophila is a Gram-negative bacterium and the causative agent of Legionnaires' disease. It replicates within amoeba and infects accidentally human macrophages. Several similarities are seen in the L. pneumophila-infection cycle in both hosts, suggesting that the tools necessary for macrophage infection may have evolved during co-evolution of L. pneumophila and amoeba. The establishment of the Legionella-containing vacuole (LCV) within the host cytoplasm requires the remodeling of the LCV surface and the hijacking of vesicles and organelles. Then L. pneumophila replicates in a safe intracellular niche in amoeba and macrophages. In this review we will summarize the existing knowledge of the L. pneumophila infection cycle in both hosts at the molecular level and compare the factors involved within amoeba and macrophages. This knowledge will be discussed in the light of recent findings from the Acanthamoeba castellanii genome analyses suggesting the existence of a primitive immune-like system in amoeba.
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Affiliation(s)
- Pedro Escoll
- Institut Pasteur, Biologie des Bactéries Intracellulaires and CNRS UMR, 3525, Paris, France
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31
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Host signal transduction and protein kinases implicated in Legionella infection. Curr Top Microbiol Immunol 2013; 376:249-69. [PMID: 23918173 DOI: 10.1007/82_2013_342] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Modulation of the phosphorylation status of proteins by both kinases and phosphatases plays an important role in cellular signal transduction. Challenge of host cells by Legionella pneumophila manipulates the phosphorylation state of multiple host factors. These changes play roles in bacterial uptake, vacuole modification, cellular survival, and the immune response. In addition to modification by host cell kinases in response to the bacterium, L. pneumophila translocates bacterial kinases into the host cell that may contribute to further signaling modifications. Proper regulation of host cell signaling by L. pneumophila is necessary for its ability to replicate intracellulary, while avoiding host defenses.
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Abstract
Legionella is a gram-negative bacterium and the causative pathogen of legionellosis-a severe pneumonia in humans. A large number of Legionella effectors interfere with numerous host cell functions, including intracellular vacuole trafficking and maturation, phospholipid metabolism, protein ubiquitination, pro-/anti-apoptotic balances or inflammatory responses. Moreover, eukaryotic protein synthesis is affected by L. pneumophila glucosyltransferases Lgt1, Lgt2, and Lgt3. Structurally, these enzymes are similar to large clostridial cytotoxins, use UDP-glucose as a co-substrate and modify a conserved serine residue (Ser-53) in elongation factor 1A (eEF1A). The ternary complex consisting of eEF1A, GTP, and aminoacylated-tRNA seems to be the substrate for Lgts. Studies with Saccharomyces cerevisiae corroborated that eEF1A is the major target responsible for Lgt-induced cytotoxic activity. In addition to Lgt proteins, Legionella produces other effector glycosyltransferase, including the modularly composed protein SetA, which displays tropism for early endosomal compartments, subverts host cell vesicle trafficking and demonstrates toxic activities toward yeast and mammalian cells. Here, our current knowledge about both groups of L. pneumophila glycosylating effectors is reviewed.
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Xu L, Luo ZQ. Cell biology of infection by Legionella pneumophila. Microbes Infect 2012; 15:157-67. [PMID: 23159466 DOI: 10.1016/j.micinf.2012.11.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 11/02/2012] [Accepted: 11/05/2012] [Indexed: 01/09/2023]
Abstract
Professional phagocytes digest internalized microorganisms by actively delivering them into the phagolysosomal compartment. Intravacuolar bacterial pathogens have evolved a variety of effective strategies to bypass the default pathway of phagosomal maturation to create a niche permissive for their survival and propagation. Here we discuss recent progress in our understanding of the sophisticated mechanisms used by Legionella pneumophila to survive in phagocytes.
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Affiliation(s)
- Li Xu
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, United States
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Voth DE, Broederdorf LJ, Graham JG. Bacterial Type IV secretion systems: versatile virulence machines. Future Microbiol 2012; 7:241-57. [PMID: 22324993 DOI: 10.2217/fmb.11.150] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Many bacterial pathogens employ multicomponent protein complexes to deliver macromolecules directly into their eukaryotic host cell to promote infection. Some Gram-negative pathogens use a versatile Type IV secretion system (T4SS) that can translocate DNA or proteins into host cells. T4SSs represent major bacterial virulence determinants and have recently been the focus of intense research efforts designed to better understand and combat infectious diseases. Interestingly, although the two major classes of T4SSs function in a similar manner to secrete proteins, the translocated 'effectors' vary substantially from one organism to another. In fact, differing effector repertoires likely contribute to organism-specific host cell interactions and disease outcomes. In this review, we discuss the current state of T4SS research, with an emphasis on intracellular bacterial pathogens of humans and the diverse array of translocated effectors used to manipulate host cells.
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Affiliation(s)
- Daniel E Voth
- Department of Microbiology & Immunology, University of Arkansas for Medical Sciences, 4301 W. Markham, Little Rock, AR 72205, USA.
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Rolando M, Buchrieser C. Post-translational modifications of host proteins by Legionella pneumophila: a sophisticated survival strategy. Future Microbiol 2012; 7:369-81. [DOI: 10.2217/fmb.12.9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Eukaryotic proteins are tightly regulated by post-translational modifications, leading to a very subtle degree of regulation in time and space. Pathogen-mediated post-translational modifications are key strategies to modulate host factors by targeting central signaling pathways in the host cell. Legionella pneumophila, an intracellular pathogen that coevolved with protozoan hosts, encodes a large arsenal of secreted effectors conferring the ability to evade host cellular defenses and to manipulate them to promote invasion and intracellular replication. Conservation of many signaling pathways of protozoa in human macrophages confers the ability of L. pneumophila to infect humans, causing a severe pneumonia called legionnaires’ disease. Most of the secreted proteins are delivered by the Dot/Icm type IV secretion system and several of these have been shown to act on different cellular pathways critical for infection. Moreover, multiple effectors target a single host function to orchestrate bacterial survival. In this review, we focus on those effectors in the repertoire of L. pneumophila proteins that target key cellular pathways by specific post-translational modifications.
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Affiliation(s)
- Monica Rolando
- Institut Pasteur, Biologie des Bactéries Intracellulaires, 75724 Paris, France
- CNRS UMR 3525, 75724 Paris, France
| | - Carmen Buchrieser
- CNRS UMR 3525, 75724 Paris, France
- Institut Pasteur, Biologie des Bactéries Intracellulaires, 75724 Paris, France
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Ashida H, Mimuro H, Ogawa M, Kobayashi T, Sanada T, Kim M, Sasakawa C. Cell death and infection: a double-edged sword for host and pathogen survival. ACTA ACUST UNITED AC 2011; 195:931-42. [PMID: 22123830 PMCID: PMC3241725 DOI: 10.1083/jcb.201108081] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Host cell death is an intrinsic immune defense mechanism in response to microbial infection. However, bacterial pathogens use many strategies to manipulate the host cell death and survival pathways to enhance their replication and survival. This manipulation is quite intricate, with pathogens often suppressing cell death to allow replication and then promoting it for dissemination. Frequently, these effects are exerted through modulation of the mitochondrial pro-death, NF-κB-dependent pro-survival, and inflammasome-dependent host cell death pathways during infection. Understanding the molecular details by which bacterial pathogens manipulate cell death pathways will provide insight into new therapeutic approaches to control infection.
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Affiliation(s)
- Hiroshi Ashida
- Department of Microbiology and Immunology, International Research Center for Infectious Disease, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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Ge J, Shao F. Manipulation of host vesicular trafficking and innate immune defence by Legionella Dot/Icm effectors. Cell Microbiol 2011; 13:1870-80. [PMID: 21981078 DOI: 10.1111/j.1462-5822.2011.01710.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Legionella pneumophila, the causative agent of Legionnaires' disease, infects and replicates in macrophages and amoebas. Following internalization, L. pneumophila resides in a vacuole structure called Legionella-containing vacuole (LCV). The LCV escapes from the endocytic maturation process and avoids fusion with the lysosome, a hallmark of Legionella pathogenesis. Interference with the secretory vesicle transport and avoiding lysosomal targeting render the LCV permissive for L. pneumophila intracellular replication. Central to L. pneumophila pathogenesis is a defect in the organelle trafficking/intracellular multiplication (Dot/Icm) type IV secretion system that translocates a large number of effector proteins into host cells. Many of the Dot/Icm effectors employ diverse and sophisticated biochemical strategies to manipulate the host vesicular transport system, playing an important role in LCV biogenesis and trafficking. Similar to other bacterial pathogens, L. pneumophila also delivers effector proteins to modulate or counteract host innate immune defence pathways such as the NF-κB and apoptotic signalling. This review summarizes the known functions and mechanisms of Dot/Icm effectors that target host membrane trafficking and innate immune defence pathways.
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Affiliation(s)
- Jianning Ge
- National Institute of Biological Sciences, Zhongguancun Life Science Park, Beijing 102206, China
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38
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Abstract
Legionella pneumophila is a facultative intracellular pathogen capable of replicating in a wide spectrum of cells. Successful infection by Legionella requires the Dot/Icm type IV secretion system, which translocates a large number of effector proteins into infected cells. By co-opting numerous host cellular processes, these proteins function to establish a specialized organelle that allows bacterial survival and proliferation. Even within the vacuole, L. pneumophila triggers robust immune responses. Recent studies reveal that a subset of Legionella effectors directly target some basic components of the host innate immunity systems such as phagosome maturation. Others play essential roles in engaging the host innate immune surveillance system. This review will highlight recent progress in our understanding of these interactions and discuss implications for the study of the immune detection mechanisms.
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Affiliation(s)
- Zhao-Qing Luo
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
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Schuelein R, Ang DKY, van Driel IR, Hartland EL. Immune Control of Legionella Infection: An in vivo Perspective. Front Microbiol 2011; 2:126. [PMID: 21687433 PMCID: PMC3109619 DOI: 10.3389/fmicb.2011.00126] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 05/23/2011] [Indexed: 11/13/2022] Open
Abstract
Legionella pneumophila is an intracellular pathogen that replicates within alveolar macrophages. Through its ability to activate multiple host innate immune components, L. pneumophila has emerged as a useful tool to dissect inflammatory signaling pathways in macrophages. However the resolution of L. pneumophila infection in the lung requires multiple cell types and abundant cross talk between immune cells. Few studies have examined the coordination of events that lead to effective immune control of the pathogen. Here we discuss L. pneumophila interactions with macrophages and dendritic cell subsets and highlight the paucity of knowledge around how these interactions recruit and activate other immune effector cells in the lung.
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Affiliation(s)
- Ralf Schuelein
- Department of Microbiology and Immunology, University of Melbourne Parkville, Victoria, Australia
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Dietrich M, Bartfeld S, Munke R, Lange C, Ogilvie LA, Friedrich A, Meyer TF. Activation of NF-κB by Neisseria gonorrhoeae is associated with microcolony formation and type IV pilus retraction. Cell Microbiol 2011; 13:1168-82. [PMID: 21615661 DOI: 10.1111/j.1462-5822.2011.01607.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The early stage of infection with Neisseria gonorrhoeae (Ngo), the causative agent of gonorrhoea, is marked by type IV pilus (Tfp)-mediated attachment and the formation of bacterial microcolonies on epithelial cells. Retraction of the Ngo Tfp generates substantial force on its substrate which can elicit host cell signalling. Here, we observed that this retraction force could also activate nuclear factor (NF)-κB, the central signalling cascade of innate immunity. Using a p65-GFP-expressing epithelial cell line, we show that piliated Ngo induce asynchronous NF-κB activation in infected cells, which is temporally associated with the formation of gonococcal microcolonies. A mutant lacking PilT, an ATPase necessary for Tfp retraction, induced markedly reduced NF-κB activation. This was accompanied by decreased NF-κB target gene transcription and cytokine release. The impaired ability of the pilT mutant to activate NF-κB was compensated by applying mechanical shear stress to the infected host cells, indicating that the mechanical forces generated by retractile pili are involved in the retraction-dependent activation of NF-κB elicited by gonococcal microcolonies. Thus, our work provides evidence for an intriguing relationship between microcolony growth, pilus retraction and host cell signalling, with likely implications with regard to the course of symptomatic versus asymptomatic gonococcal infections.
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Affiliation(s)
- Manuela Dietrich
- Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany
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Newman RH, Fosbrink MD, Zhang J. Genetically encodable fluorescent biosensors for tracking signaling dynamics in living cells. Chem Rev 2011; 111:3614-66. [PMID: 21456512 PMCID: PMC3092831 DOI: 10.1021/cr100002u] [Citation(s) in RCA: 260] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Robert H. Newman
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Matthew D. Fosbrink
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Jin Zhang
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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Haenssler E, Isberg RR. Control of host cell phosphorylation by legionella pneumophila. Front Microbiol 2011; 2:64. [PMID: 21747787 PMCID: PMC3128975 DOI: 10.3389/fmicb.2011.00064] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 03/24/2011] [Indexed: 11/13/2022] Open
Abstract
Phosphorylation is one of the most frequent modifications in intracellular signaling and is implicated in many processes ranging from transcriptional control to signal transduction in innate immunity. Many pathogens modulate host cell phosphorylation pathways to promote growth and establish an infectious disease. The intracellular pathogen Legionella pneumophila targets and exploits the host phosphorylation system throughout the infection cycle as part of its strategy to establish an environment beneficial for replication. Key to this manipulation is the L. pneumophila Icm/Dot type IV secretion system, which translocates bacterial proteins into the host cytosol that can act directly on phosphorylation cascades. This review will focus on the different stages of L. pneumophila infection, in which host kinases and phosphatases contribute to infection of the host cell and promote intracellular survival of the pathogen. This includes the involvement of phosphatidylinositol 3-kinases during phagocytosis as well as the role of phosphoinositide metabolism during the establishment of the replication vacuole. Furthermore, L. pneumophila infection modulates the NF-κB and mitogen-activated protein kinase pathways, two signaling pathways that are central to the host innate immune response and involved in regulation of host cell survival. Therefore, L. pneumophila infection manipulates host cell signal transduction by phosphorylation at multiple levels.
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Affiliation(s)
- Eva Haenssler
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine Boston, MA, USA
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Legionella pneumophila type II secretion dampens the cytokine response of infected macrophages and epithelia. Infect Immun 2011; 79:1984-97. [PMID: 21383054 DOI: 10.1128/iai.01077-10] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The type II secretion (T2S) system of Legionella pneumophila is required for the ability of the bacterium to grow within the lungs of A/J mice. By utilizing mutants lacking T2S (lsp), we now document that T2S promotes the intracellular infection of both multiple types of macrophages and lung epithelia. Following infection of macrophages, lsp mutants (but not a complemented mutant) elicited significantly higher levels of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), IL-10, IL-8, IL-1β, and MCP-1 within tissue culture supernatants. A similar result was obtained with infected lung epithelial cell lines and the lungs of infected A/J mice. Infection with a mutant specifically lacking the T2S-dependent ProA protease (but not a complemented proA mutant) resulted in partial elevation of cytokine levels. These data demonstrate that the T2S system of L. pneumophila dampens the cytokine/chemokine output of infected host cells. Upon quantitative reverse transcription (RT)-PCR analysis of infected host cells, an lspF mutant, but not the proA mutant, produced significantly higher levels of cytokine transcripts, implying that some T2S-dependent effectors dampen signal transduction and transcription but that others, such as ProA, act at a posttranscriptional step in cytokine expression. In summary, the impact of T2S on lung infection is a combination of at least three factors: the promotion of growth in macrophages, the facilitation of growth in epithelia, and the dampening of the chemokine and cytokine output from infected host cells. To our knowledge, these data are the first to identify a link between a T2S system and the modulation of immune factors following intracellular infection.
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Abdelaziz DHA, Gavrilin MA, Akhter A, Caution K, Kotrange S, Khweek AA, Abdulrahman BA, Hassan ZA, El-Sharkawi FZ, Bedi SS, Ladner K, Gonzalez-Mejia ME, Doseff AI, Mostafa M, Kanneganti TD, Guttridge D, Marsh CB, Wewers MD, Amer AO. Asc-dependent and independent mechanisms contribute to restriction of legionella pneumophila infection in murine macrophages. Front Microbiol 2011; 2:18. [PMID: 21713115 PMCID: PMC3112328 DOI: 10.3389/fmicb.2011.00018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 01/25/2011] [Indexed: 11/13/2022] Open
Abstract
The apoptosis-associated speck-like protein containing a caspase recruitment domain (Asc) is an adaptor molecule that mediates inflammatory and apoptotic signals. Legionella pneumophila is an intracellular bacterium and the causative agent of Legionnaire's pneumonia. L. pneumophila is able to cause pneumonia in immuno-compromised humans but not in most inbred mice. Murine macrophages that lack the ability to activate caspase-1, such as caspase(-1-/-) and Nlrc4(-/-) allow L. pneumophila infection. This permissiveness is attributed mainly to the lack of active caspase-1 and the absence of its down stream substrates such as caspase-7. However, the role of Asc in control of L. pneumophila infection in mice is unclear. Here we show that caspase-1 is moderately activated in Asc(-/-) macrophages and that this limited activation is required and sufficient to restrict L. pneumophila growth. Moreover, Asc-independent activation of caspase-1 requires bacterial flagellin and is mainly detected in cellular extracts but not in culture supernatants. We also demonstrate that the depletion of Asc from permissive macrophages enhances bacterial growth by promoting L. pneumophila-mediated activation of the NF-κB pathway and decreasing caspase-3 activation. Taken together, our data demonstrate that L. pneumophila infection in murine macrophages is controlled by several mechanisms: Asc-independent activation of caspase-1 and Asc-dependent regulation of NF-κB and caspase-3 activation.
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Affiliation(s)
- Dalia H A Abdelaziz
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Center for Microbial Interface Biology and the Department of Internal Medicine, Ohio State University Columbus, OH, USA
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Khweek AA, Amer A. Replication of Legionella Pneumophila in Human Cells: Why are We Susceptible? Front Microbiol 2010; 1:133. [PMID: 21687775 PMCID: PMC3109522 DOI: 10.3389/fmicb.2010.00133] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 11/16/2010] [Indexed: 11/13/2022] Open
Abstract
Legionella pneumophila is the causative agent of Legionnaires’ disease, a serious and often fatal form of pneumonia. The susceptibility to L. pneumophila arises from the ability of this intracellular pathogen to multiply in human alveolar macrophages and monocytes. L. pneumophila also replicates in several professional and non-professional phagocytic human-derived cell lines. With the exception of the A/J mouse strain, most mice strains are restrictive, thus they do not support L. pneumophila replication. Mice lacking the NOD-like receptor Nlrc4 or caspase-1 are also susceptible to L. pneumophila. On the other hand, in the susceptible human hosts, L. pneumophila utilizes several strategies to ensure intracellular replication and protect itself against the host immune system. Most of these strategies converge to prevent the fusion of the L. pneumophila phagosome with the lysosome, inhibiting host cell apoptosis, activating survival pathways, and sequestering essential nutrients for replication and pathogenesis. In this review, we summarize survival mechanisms employed by L. pneumophila to maintain its replication in human cells. In addition, we highlight different human-derived cell lines that support the multiplication of this intracellular bacterium. Therefore, these in vitro models can be applicable and are reproducible when investigating L. pneumophila/phagocyte interactions at the molecular and cellular levels in the human host.
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Affiliation(s)
- Arwa Abu Khweek
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Center for Microbial Interface Biology and the Department of Internal Medicine, Ohio State University Columbus, OH, USA
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Abdelaziz DH, Gavrilin MA, Akhter A, Caution K, Kotrange S, Khweek AA, Abdulrahman BA, Grandhi J, Hassan ZA, Marsh C, Wewers MD, Amer AO. Apoptosis-associated speck-like protein (ASC) controls Legionella pneumophila infection in human monocytes. J Biol Chem 2010; 286:3203-8. [PMID: 21097506 PMCID: PMC3030324 DOI: 10.1074/jbc.m110.197681] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The ability of Legionella pneumophila to cause pneumonia is determined by its capability to evade the immune system and grow within human monocytes and their derived macrophages. Human monocytes efficiently activate caspase-1 in response to Salmonella but not to L. pneumophila. The molecular mechanism for the lack of inflammasome activation during L. pneumophila infection is unknown. Evaluation of the expression of several inflammasome components in human monocytes during L. pneumophila infection revealed that the expression of the apoptosis-associated speck-like protein (ASC) and the NOD-like receptor NLRC4 are significantly down-regulated in human monocytes. Exogenous expression of ASC maintained the protein level constant during L. pneumophila infection and conveyed caspase-1 activation and restricted the growth of the pathogen. Further depletion of ASC with siRNA was accompanied with improved NF-κB activation and enhanced L. pneumophila growth. Therefore, our data demonstrate that L. pneumophila manipulates ASC levels to evade inflammasome activation and grow in human monocytes. By targeting ASC, L. pneumophila modulates the inflammasome, the apoptosome, and NF-κB pathway simultaneously.
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Affiliation(s)
- Dalia H Abdelaziz
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Center for Microbial Interface Biology and the Department of Internal Medicine, Ohio State University, Columbus, Ohio 43210, USA
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Lee TK, Covert MW. High-throughput, single-cell NF-κB dynamics. Curr Opin Genet Dev 2010; 20:677-83. [PMID: 20846851 DOI: 10.1016/j.gde.2010.08.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/23/2010] [Accepted: 08/19/2010] [Indexed: 01/08/2023]
Abstract
Single cells in a population often respond differently to perturbations in the environment. Live-cell microscopy has enabled scientists to observe these differences at the single-cell level. Some advantages of live-cell imaging over population-based methods include better time resolution, higher sensitivity, automation, and richer datasets. One specific area where live-cell microscopy has made a significant impact is the field of NF-κB signaling dynamics, and recent efforts have focused on making live-cell imaging of these dynamics more high-throughput. We highlight the major aspects of increasing throughput and describe a current system that can monitor, image and analyze the NF-κB activation of thousands of single cells in parallel.
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Affiliation(s)
- Timothy K Lee
- Department of Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, United States
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Lomma M, Dervins-Ravault D, Rolando M, Nora T, Newton HJ, Sansom FM, Sahr T, Gomez-Valero L, Jules M, Hartland EL, Buchrieser C. The Legionella pneumophila F-box protein Lpp2082 (AnkB) modulates ubiquitination of the host protein parvin B and promotes intracellular replication. Cell Microbiol 2010; 12:1272-91. [DOI: 10.1111/j.1462-5822.2010.01467.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Abstract
The genus Legionella contains more than 50 species, of which at least 24 have been associated with human infection. The best-characterized member of the genus, Legionella pneumophila, is the major causative agent of Legionnaires' disease, a severe form of acute pneumonia. L. pneumophila is an intracellular pathogen, and as part of its pathogenesis, the bacteria avoid phagolysosome fusion and replicate within alveolar macrophages and epithelial cells in a vacuole that exhibits many characteristics of the endoplasmic reticulum (ER). The formation of the unusual L. pneumophila vacuole is a feature of its interaction with the host, yet the mechanisms by which the bacteria avoid classical endosome fusion and recruit markers of the ER are incompletely understood. Here we review the factors that contribute to the ability of L. pneumophila to infect and replicate in human cells and amoebae with an emphasis on proteins that are secreted by the bacteria into the Legionella vacuole and/or the host cell. Many of these factors undermine eukaryotic trafficking and signaling pathways by acting as functional and, in some cases, structural mimics of eukaryotic proteins. We discuss the consequences of this mimicry for the biology of the infected cell and also for immune responses to L. pneumophila infection.
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Böhme L, Albrecht M, Riede O, Rudel T. Chlamydia trachomatis-infected host cells resist dsRNA-induced apoptosis. Cell Microbiol 2010; 12:1340-51. [PMID: 20482554 DOI: 10.1111/j.1462-5822.2010.01473.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Human pathogenic Chlamydia trachomatis have evolved sophisticated mechanisms to manipulate host cell signalling pathways in order to prevent apoptosis. We show here that host cells infected with C. trachomatis resist apoptosis induced by polyI:C, a synthetic double-stranded RNA that mimics viral infections. Infected cells displayed significantly reduced levels of PARP cleavage, caspase-3 activation and a decrease in the TUNEL positive population in the presence of polyI:C. Interestingly, the chlamydial block of apoptosis was upstream of the initiator caspase-8. Processing of caspase-8 was reduced in infected cells and coincided with a decrease in Bid truncation and downstream caspase-9 cleavage. Moreover, the enzymatic activity of caspase-8, measured by a luminescent substrate, was significantly reduced in infected cells. Caspase-8 inhibition by Chlamydia was dependent on cFlip as knock-down of cFlip decreased the chlamydial block of caspase-8 activation and consequently reduced apoptosis inhibition. Our data implicate that chlamydial infection interferes with the host cell's response to viral infections and thereby influences the fate of the cell.
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Affiliation(s)
- Linda Böhme
- Biocenter, University of Würzburg, 97074 Würzburg, Germany
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