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Seabaugh JA, Anderson DM. Pathogenicity and virulence of Yersinia. Virulence 2024; 15:2316439. [PMID: 38389313 PMCID: PMC10896167 DOI: 10.1080/21505594.2024.2316439] [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: 10/05/2023] [Accepted: 02/04/2024] [Indexed: 02/24/2024] Open
Abstract
The genus Yersinia includes human, animal, insect, and plant pathogens as well as many symbionts and harmless bacteria. Within this genus are Yersinia enterocolitica and the Yersinia pseudotuberculosis complex, with four human pathogenic species that are highly related at the genomic level including the causative agent of plague, Yersinia pestis. Extensive laboratory, field work, and clinical research have been conducted to understand the underlying pathogenesis and zoonotic transmission of these pathogens. There are presently more than 500 whole genome sequences from which an evolutionary footprint can be developed that details shared and unique virulence properties. Whereas the virulence of Y. pestis now seems in apparent homoeostasis within its flea transmission cycle, substantial evolutionary changes that affect transmission and disease severity continue to ndergo apparent selective pressure within the other Yersiniae that cause intestinal diseases. In this review, we will summarize the present understanding of the virulence and pathogenesis of Yersinia, highlighting shared mechanisms of virulence and the differences that determine the infection niche and disease severity.
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Affiliation(s)
- Jarett A. Seabaugh
- Department of Veterinary Pathobiology, University of Missouri, Columbia, USA
| | - Deborah M. Anderson
- Department of Veterinary Pathobiology, University of Missouri, Columbia, USA
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Li P, Wang H, Sun W, Ding J. Impact of MgtC on the Fitness of Yersinia pseudotuberculosis. Pathogens 2023; 12:1428. [PMID: 38133312 PMCID: PMC10747817 DOI: 10.3390/pathogens12121428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023] Open
Abstract
Yersinia pseudotuberculosis is an extracellular foodborne pathogen and usually causes self-limiting diarrhea in healthy humans. MgtC is known as a key subversion factor that contributes to intramacrophage adaptation and intracellular survival in certain important pathogens. Whether MgtC influences the fitness of Y. pseudotuberculosis is unclear. According to in silico analysis, MgtC in Y. pseudotuberculosis might share similar functions with other bacterial pathogens, such as Salmonella. Studies indicated that MgtC was clearly required for Y. pseudotuberculosis growth in vitro and bacterial survival in macrophages under Mg2+ starvation. Transcriptome analysis by RNA-seq indicated that 127 differentially expressed genes (DEGs) (fold change > 2 and p < 0.001) were discovered between wild-type PB1+ and mgtC mutant inside macrophages. However, a lack of MgtC only moderately, albeit significantly, reduced the virulence of Y. pseudotuberculosis in mice. Overall, this study provides additional insights for the role of MgtC in Y. pseudotuberculosis.
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Affiliation(s)
- Peng Li
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
| | - Hengtai Wang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
| | - Wei Sun
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, NY 12208, USA;
| | - Jiabo Ding
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China;
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3
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Taya T, Teruyama F, Gojo S. Host-directed therapy for bacterial infections -Modulation of the phagolysosome pathway. Front Immunol 2023; 14:1227467. [PMID: 37841276 PMCID: PMC10570837 DOI: 10.3389/fimmu.2023.1227467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023] Open
Abstract
Bacterial infections still impose a significant burden on humanity, even though antimicrobial agents have long since been developed. In addition to individual severe infections, the f fatality rate of sepsis remains high, and the threat of antimicrobial-resistant bacteria grows with time, putting us at inferiority. Although tremendous resources have been devoted to the development of antimicrobial agents, we have yet to recover from the lost ground we have been driven into. Looking back at the evolution of treatment for cancer, which, like infectious diseases, has the similarity that host immunity eliminates the lesion, the development of drugs to eliminate the tumor itself has shifted from a single-minded focus on drug development to the establishment of a treatment strategy in which the de-suppression of host immunity is another pillar of treatment. In infectious diseases, on the other hand, the development of therapies that strengthen and support the immune system has only just begun. Among innate immunity, the first line of defense that bacteria encounter after invading the host, the molecular mechanisms of the phagolysosome pathway, which begins with phagocytosis to fusion with lysosome, have been elucidated in detail. Bacteria have a large number of strategies to escape and survive the pathway. Although the full picture is still unfathomable, the molecular mechanisms have been elucidated for some of them, providing sufficient clues for intervention. In this article, we review the host defense mechanisms and bacterial evasion mechanisms and discuss the possibility of host-directed therapy for bacterial infection by intervening in the phagolysosome pathway.
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Affiliation(s)
- Toshihiko Taya
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Fumiya Teruyama
- Pharmacology Research Department, Tokyo New Drug Research Laboratories, Kowa Company, Ltd., Tokyo, Japan
- Department of Regenerative Medicine, Graduate School of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Satoshi Gojo
- Department of Regenerative Medicine, Graduate School of Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
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4
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Sontyana B, Shrivastava R, Battu S, Ghosh S, Mukhopadhyay S. Phagosome maturation and modulation of macrophage effector function by intracellular pathogens: target for therapeutics. Future Microbiol 2021; 17:59-76. [PMID: 34877879 DOI: 10.2217/fmb-2021-0101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Macrophages are important cells that regulate various innate functions. Macrophages after engulfment of pathogens proceed for phagosome maturation and finally fuse with lysosomes to kill pathogens. Although pathogen degradation is one of the important functions of phagosomes, various immune-effector functions of macrophages are also dependent on the phagosome maturation process. This review discusses signaling processes regulating phagosome maturation as well as various effector functions of macrophages such as apoptosis, antigen presentation, autophagy and inflammasome that are dependent on the phagosome maturation process. It also discusses strategies adopted by various intracellular pathogens to counteract these functions to evade intracellular destruction mechanisms. These studies may give direction for the development of new therapeutics to control various intracellular infections.
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Affiliation(s)
- Brahmaji Sontyana
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting & Diagnostics (CDFD), Inner Ring Road, Uppal, Hyderabad, 500039, Telangana, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Rohini Shrivastava
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting & Diagnostics (CDFD), Inner Ring Road, Uppal, Hyderabad, 500039, Telangana, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India
| | - Srikanth Battu
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting & Diagnostics (CDFD), Inner Ring Road, Uppal, Hyderabad, 500039, Telangana, India
| | - Sudip Ghosh
- Molecular Biology Unit, ICMR-National Institute of Nutrition, Jamai Osmania PO, Hyderabad, 500007, Telangana, India
| | - Sangita Mukhopadhyay
- Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting & Diagnostics (CDFD), Inner Ring Road, Uppal, Hyderabad, 500039, Telangana, India
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5
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Macrophages in Microbial Pathogenesis: Commonalities of Defense Evasion Mechanisms. Infect Immun 2021; 90:e0029121. [PMID: 34780281 DOI: 10.1128/iai.00291-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Macrophages are key arsenals of the immune system against invaders. After compartmental isolation of a pathogen in phagosomes, the host immune response attempts to neutralize the pathogen. However, pathogens possess the ability to subvert these assaults and can also convert macrophages into their replicative niche. The multiple host defense evasion mechanisms employed by these pathogens like phagosome maturation arrest, molecular mimicry through secretory antigens, interference with host signaling, active radical neutralization, inhibition of phagosome acidification, alteration of programmed cell death and many other mechanisms. Macrophage biology as a part of the host-pathogen interaction has expanded rapidly in the past decade. The present review aims to shed some light upon the macrophage defense evasion strategies employed by infecting pathogens. We have also incorporated recent knowledge in the field of macrophage dynamics during infection and evolutionary perspectives of macrophage dynamics.
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Autophagy-A Story of Bacteria Interfering with the Host Cell Degradation Machinery. Pathogens 2021; 10:pathogens10020110. [PMID: 33499114 PMCID: PMC7911818 DOI: 10.3390/pathogens10020110] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 02/07/2023] Open
Abstract
Autophagy is a highly conserved and fundamental cellular process to maintain cellular homeostasis through recycling of defective organelles or proteins. In a response to intracellular pathogens, autophagy further acts as an innate immune response mechanism to eliminate pathogens. This review will discuss recent findings on autophagy as a reaction to intracellular pathogens, such as Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Staphylococcus aureus, and pathogenic Escherichia coli. Interestingly, while some of these bacteria have developed methods to use autophagy for their own benefit within the cell, others have developed fascinating mechanisms to evade recognition, to subvert the autophagic pathway, or to escape from autophagy.
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Autophagy and Intracellular Membrane Trafficking Subversion by Pathogenic Yersinia Species. Biomolecules 2020; 10:biom10121637. [PMID: 33291818 PMCID: PMC7762052 DOI: 10.3390/biom10121637] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/30/2020] [Accepted: 12/03/2020] [Indexed: 02/07/2023] Open
Abstract
Yersinia pseudotuberculosis, Y. enterocolitica and Y. pestis are pathogenic bacteria capable of causing disease in humans by growing extracellularly in lymph nodes and during systemic infections. While the capacity of these bacteria to invade, replicate, and survive within host cells has been known for long, it is only in recent years that their intracellular stages have been explored in more detail. Current evidence suggests that pathogenic Yersinia are capable of activating autophagy in both phagocytic and epithelial cells, subverting autophagosome formation to create a niche supporting bacterial intracellular replication. In this review, we discuss recent results opening novel perspectives to the understanding of intimate host-pathogens interactions taking place during enteric yersiniosis and plague.
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Pessoa CC, Reis LC, Ramos-Sanchez EM, Orikaza CM, Cortez C, de Castro Levatti EV, Badaró ACB, Yamamoto JUDS, D’Almeida V, Goto H, Mortara RA, Real F. ATP6V0d2 controls Leishmania parasitophorous vacuole biogenesis via cholesterol homeostasis. PLoS Pathog 2019; 15:e1007834. [PMID: 31199856 PMCID: PMC6594656 DOI: 10.1371/journal.ppat.1007834] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 06/26/2019] [Accepted: 05/13/2019] [Indexed: 02/07/2023] Open
Abstract
V-ATPases are part of the membrane components of pathogen-containing vacuoles, although their function in intracellular infection remains elusive. In addition to organelle acidification, V-ATPases are alternatively implicated in membrane fusion and anti-inflammatory functions controlled by ATP6V0d2, the d subunit variant of the V-ATPase complex. Therefore, we evaluated the role of ATP6V0d2 in the biogenesis of pathogen-containing vacuoles using ATP6V0d2 knock-down macrophages infected with the protozoan parasite Leishmania amazonensis. These parasites survive within IFNγ/LPS-activated inflammatory macrophages, multiplying in large/fusogenic parasitophorous vacuoles (PVs) and inducing ATP6V0d2 upregulation. ATP6V0d2 knock-down decreased macrophage cholesterol levels and inhibited PV enlargement without interfering with parasite multiplication. However, parasites required ATP6V0d2 to resist the influx of oxidized low-density lipoprotein (ox-LDL)-derived cholesterol, which restored PV enlargement in ATP6V0d2 knock-down macrophages by replenishing macrophage cholesterol pools. Thus, we reveal parasite-mediated subversion of host V-ATPase function toward cholesterol retention, which is required for establishing an inflammation-resistant intracellular parasite niche.
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Affiliation(s)
- Carina Carraro Pessoa
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brasil
| | - Luiza Campos Reis
- Laboratório de Soroepidemiologia e Imunobiologia, Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, Brasil
| | - Eduardo Milton Ramos-Sanchez
- Laboratório de Soroepidemiologia e Imunobiologia, Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, Brasil
| | - Cristina Mary Orikaza
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brasil
| | - Cristian Cortez
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago de Chile, Chile
| | | | - Ana Carolina Benites Badaró
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brasil
| | | | - Vânia D’Almeida
- Departamento de Psicobiologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brasil
| | - Hiro Goto
- Laboratório de Soroepidemiologia e Imunobiologia, Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, Brasil
- Departamento de Medicina Preventiva, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brasil
| | - Renato Arruda Mortara
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brasil
| | - Fernando Real
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brasil
- * E-mail:
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Harrison MA, Muench SP. The Vacuolar ATPase - A Nano-scale Motor That Drives Cell Biology. Subcell Biochem 2018; 87:409-459. [PMID: 29464568 DOI: 10.1007/978-981-10-7757-9_14] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The vacuolar H+-ATPase (V-ATPase) is a ~1 MDa membrane protein complex that couples the hydrolysis of cytosolic ATP to the transmembrane movement of protons. In essentially all eukaryotic cells, this acid pumping function plays critical roles in the acidification of endosomal/lysosomal compartments and hence in transport, recycling and degradative pathways. It is also important in acid extrusion across the plasma membrane of some cells, contributing to homeostatic control of cytoplasmic pH and maintenance of appropriate extracellular acidity. The complex, assembled from up to 30 individual polypeptides, operates as a molecular motor with rotary mechanics. Historically, structural inferences about the eukaryotic V-ATPase and its subunits have been made by comparison to the structures of bacterial homologues. However, more recently, we have developed a much better understanding of the complete structure of the eukaryotic complex, in particular through advances in cryo-electron microscopy. This chapter explores these recent developments, and examines what they now reveal about the catalytic mechanism of this essential proton pump and how its activity might be regulated in response to cellular signals.
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Affiliation(s)
- Michael A Harrison
- School of Biomedical Sciences, Faculty of Biological Sciences, The University of Leeds, Leeds, UK.
| | - Steven P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, The University of Leeds, Leeds, UK
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Munang'andu HM. Intracellular Bacterial Infections: A Challenge for Developing Cellular Mediated Immunity Vaccines for Farmed Fish. Microorganisms 2018; 6:microorganisms6020033. [PMID: 29690563 PMCID: PMC6027125 DOI: 10.3390/microorganisms6020033] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 04/15/2018] [Accepted: 04/20/2018] [Indexed: 12/15/2022] Open
Abstract
Aquaculture is one of the most rapidly expanding farming systems in the world. Its rapid expansion has brought with it several pathogens infecting different fish species. As a result, there has been a corresponding expansion in vaccine development to cope with the increasing number of infectious diseases in aquaculture. The success of vaccine development for bacterial diseases in aquaculture is largely attributed to empirical vaccine designs based on inactivation of whole cell (WCI) bacteria vaccines. However, an upcoming challenge in vaccine design is the increase of intracellular bacterial pathogens that are not responsive to WCI vaccines. Intracellular bacterial vaccines evoke cellular mediated immune (CMI) responses that “kill” and eliminate infected cells, unlike WCI vaccines that induce humoral immune responses whose protective mechanism is neutralization of extracellular replicating pathogens by antibodies. In this synopsis, I provide an overview of the intracellular bacterial pathogens infecting different fish species in aquaculture, outlining their mechanisms of invasion, replication, and survival intracellularly based on existing data. I also bring into perspective the current state of CMI understanding in fish together with its potential application in vaccine development. Further, I highlight the immunological pitfalls that have derailed our ability to produce protective vaccines against intracellular pathogens for finfish. Overall, the synopsis put forth herein advocates for a shift in vaccine design to include CMI-based vaccines against intracellular pathogens currently adversely affecting the aquaculture industry.
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Affiliation(s)
- Hetron Mweemba Munang'andu
- Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Ullevålsveien 72, P.O. Box 8146, Dep NO-0033, 046 Oslo, Norway.
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Intracellular Growth of Bacterial Pathogens: The Role of Secreted Effector Proteins in the Control of Phagocytosed Microorganisms. Microbiol Spectr 2018; 3. [PMID: 27337278 DOI: 10.1128/microbiolspec.vmbf-0003-2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The ability of intracellular pathogens to subvert the host response, to facilitate invasion and subsequent infection, is the hallmark of microbial pathogenesis. Bacterial pathogens produce and secrete a variety of effector proteins, which are the primary means by which they exert control over the host cell. Secreted effectors work independently, yet in concert with each other, to facilitate microbial invasion, replication, and intracellular survival in host cells. In this review we focus on defined host cell processes targeted by bacterial pathogens. These include phagosome maturation and its subprocesses: phagosome-endosome and phagosome-lysosome fusion events, as well as phagosomal acidification, cytoskeleton remodeling, and lysis of the phagosomal membrane. We further describe the mode of action for selected effectors from six pathogens: the Gram-negative Legionella, Salmonella, Shigella, and Yersinia, the Gram-positive Listeria, and the acid-fast actinomycete Mycobacterium.
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12
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Induction of Type I Interferon through a Noncanonical Toll-Like Receptor 7 Pathway during Yersinia pestis Infection. Infect Immun 2017; 85:IAI.00570-17. [PMID: 28847850 PMCID: PMC5649010 DOI: 10.1128/iai.00570-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 08/21/2017] [Indexed: 12/12/2022] Open
Abstract
Yersinia pestis causes bubonic, pneumonic, and septicemic plague, diseases that are rapidly lethal to most mammals, including humans. Plague develops as a consequence of bacterial neutralization of the host's innate immune response, which permits uncontrolled growth and causes the systemic hyperactivation of the inflammatory response. We previously found that host type I interferon (IFN) signaling is induced during Y. pestis infection and contributes to neutrophil depletion and disease. In this work, we show that type I IFN expression is derived from the recognition of intracellular Y. pestis by host Toll-like receptor 7 (TLR7). Type I IFN expression proceeded independent of myeloid differentiation factor 88 (MyD88), which is the only known signaling adaptor for TLR7, suggesting that a noncanonical mechanism occurs in Y. pestis-infected macrophages. In the murine plague model, TLR7 was a significant contributor to the expression of serum IFN-β, whereas MyD88 was not. Furthermore, like the type I IFN response, TLR7 contributed to the lethality of septicemic plague and was associated with the suppression of neutrophilic inflammation. In contrast, TLR7 was important for defense against disease in the lungs. Together, these data demonstrate that an atypical TLR7 signaling pathway contributes to type I IFN expression during Y. pestis infection and suggest that the TLR7-driven type I IFN response plays an important role in determining the outcome of plague.
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Arsenault RJ, Maattanen P, Daigle J, Potter A, Griebel P, Napper S. From mouth to macrophage: mechanisms of innate immune subversion by Mycobacterium avium subsp. paratuberculosis. Vet Res 2014; 45:54. [PMID: 24885748 PMCID: PMC4046017 DOI: 10.1186/1297-9716-45-54] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 03/31/2014] [Indexed: 11/10/2022] Open
Abstract
Johne’s disease (JD) is a chronic enteric infection of cattle caused by Mycobacterium avium subsp. paratuberculosis (MAP). The high economic cost and potential zoonotic threat of JD have driven efforts to develop tools and approaches to effectively manage this disease within livestock herds. Efforts to control JD through traditional animal management practices are complicated by MAP’s ability to cause long-term environmental contamination as well as difficulties associated with diagnosis of JD in the pre-clinical stages. As such, there is particular emphasis on the development of an effective vaccine. This is a daunting challenge, in large part due to MAP’s ability to subvert protective host immune responses. Accordingly, there is a priority to understand MAP’s interaction with the bovine host: this may inform rational targets and approaches for therapeutic intervention. Here we review the early host defenses encountered by MAP and the strategies employed by the pathogen to avert or subvert these responses, during the critical period between ingestion and the establishment of persistent infection in macrophages.
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Affiliation(s)
| | | | | | | | | | - Scott Napper
- VIDO-InterVac, University of Saskatchewan, Saskatoon, SK S7N 5E3, Canada.
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Mycobacterium tuberculosis protein tyrosine phosphatase (PtpA) excludes host vacuolar-H+-ATPase to inhibit phagosome acidification. Proc Natl Acad Sci U S A 2011; 108:19371-6. [PMID: 22087003 DOI: 10.1073/pnas.1109201108] [Citation(s) in RCA: 274] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb) pathogenicity depends on its ability to inhibit phagosome acidification and maturation processes after engulfment by macrophages. Here, we show that the secreted Mtb protein tyrosine phosphatase (PtpA) binds to subunit H of the macrophage vacuolar-H(+)-ATPase (V-ATPase) machinery, a multisubunit protein complex in the phagosome membrane that drives luminal acidification. Furthermore, we show that the macrophage class C vacuolar protein sorting complex, a key regulator of endosomal membrane fusion, associates with V-ATPase in phagosome maturation, suggesting a unique role for V-ATPase in coordinating phagosome-lysosome fusion. PtpA interaction with host V-ATPase is required for the previously reported dephosphorylation of VPS33B and subsequent exclusion of V-ATPase from the phagosome during Mtb infection. These findings show that inhibition of phagosome acidification in the mycobacterial phagosome is directly attributed to PtpA, a key protein needed for Mtb survival and pathogenicity within host macrophages.
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Moreau K, Lacas-Gervais S, Fujita N, Sebbane F, Yoshimori T, Simonet M, Lafont F. Autophagosomes can support Yersinia pseudotuberculosis replication in macrophages. Cell Microbiol 2010; 12:1108-23. [PMID: 20180800 DOI: 10.1111/j.1462-5822.2010.01456.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Yersinia pseudotuberculosis is able to replicate inside macrophages. However, the intracellular trafficking of the pathogen after its entry into the macrophage remains poorly understood. Using in vitro infected bone marrow-derived macrophages, we show that Y. pseudotuberculosis activates the autophagy pathway. Host cell autophagosomes subverted by bacteria do not become acidified and sustain bacteria replication. Moreover, we report that autophagy inhibition correlated with bacterial trafficking inside an acidic compartment. This study indicates that Y. pseudotuberculosis hijacks the autophagy pathway for its replication and also opens up new opportunities for deciphering the molecular basis of the host cell signalling response to intracellular Yersinia infection.
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Affiliation(s)
- Kevin Moreau
- Cellular Microbiology of Infectious Pathogens, Center of Infection and Immunity of Lille, Institut Pasteur de Lille, Lille, France
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Pujol C, Klein KA, Romanov GA, Palmer LE, Cirota C, Zhao Z, Bliska JB. Yersinia pestis can reside in autophagosomes and avoid xenophagy in murine macrophages by preventing vacuole acidification. Infect Immun 2009; 77:2251-61. [PMID: 19289509 PMCID: PMC2687347 DOI: 10.1128/iai.00068-09] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 02/21/2009] [Accepted: 03/10/2009] [Indexed: 01/02/2023] Open
Abstract
Yersinia pestis survives and replicates in phagosomes of murine macrophages. Previous studies demonstrated that Y. pestis-containing vacuoles (YCVs) acquire markers of late endosomes or lysosomes in naïve macrophages and that this bacterium can survive in macrophages activated with the cytokine gamma interferon. An autophagic process known as xenophagy, which destroys pathogens in acidic autophagolysosomes, can occur in naïve macrophages and is upregulated in activated macrophages. Studies were undertaken here to investigate the mechanism of Y. pestis survival in phagosomes of naïve and activated macrophages and to determine if the pathogen avoids or co-opts autophagy. Colocalization of the YCV with markers of autophagosomes or acidic lysosomes and the pH of the YCV were determined by microscopic imaging of infected macrophages. Some YCVs contained double membranes characteristic of autophagosomes, as determined by electron microscopy. Fluorescence microscopy showed that approximately 40% of YCVs colocalized with green fluorescent protein (GFP)-LC3, a marker of autophagic membranes, and that YCVs failed to acidify below pH 7 in naïve macrophages. Replication of Y. pestis in naïve macrophages caused accumulation of LC3-II, as determined by immunoblotting. While activation of infected macrophages increased LC3-II accumulation, it decreased the percentage of GFP-LC3-positive YCVs (approximately 30%). A viable count assay showed that Y. pestis survived equally well in macrophages proficient for autophagy and macrophages rendered deficient for this process by Cre-mediated deletion of ATG5, revealing that this pathogen does not require autophagy for intracellular replication. We conclude that although YCVs can acquire an autophagic membrane and accumulate LC3-II, the pathogen avoids xenophagy by preventing vacuole acidification.
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Affiliation(s)
- Céline Pujol
- Center for Infectious Diseases, Stony Brook University, Stony Brook, NY 11794-5120, USA
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17
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Bliska JB, Casadevall A. Intracellular pathogenic bacteria and fungi--a case of convergent evolution? Nat Rev Microbiol 2008; 7:165-71. [PMID: 19098923 DOI: 10.1038/nrmicro2049] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The bacterium Yersinia pestis and the fungus Cryptococcus neoformans are the causative agents of human plague and cryptococcosis, respectively. Both microorganisms are facultatively intracellular pathogens. A comparison of their pathogenic strategies reveals similar tactics for intracellular survival in Y. pestis and C. neoformans despite their genetic unrelatedness. Both organisms can survive in environments where they are vulnerable to predation by amoeboid protozoal hosts. Here, we propose that the overall similarities in their pathogenic strategies are an example of convergent evolution that has solved the problem of intracellular survival.
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Affiliation(s)
- James B Bliska
- Department of Molecular Genetics and Microbiology and Center for Infectious Diseases, School of Medicine, Stony Brook University, Stony Brook, New York, New York 11794, USA
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Zhang Y, Murtha J, Roberts MA, Siegel RM, Bliska JB. Type III secretion decreases bacterial and host survival following phagocytosis of Yersinia pseudotuberculosis by macrophages. Infect Immun 2008; 76:4299-310. [PMID: 18591234 PMCID: PMC2519449 DOI: 10.1128/iai.00183-08] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Revised: 03/26/2008] [Accepted: 06/23/2008] [Indexed: 12/24/2022] Open
Abstract
Yersinia pseudotuberculosis uses a plasmid (pYV)-encoded type III secretion system (T3SS) to translocate a set of effectors called Yops into infected host cells. YopJ functions to induce apoptosis, and YopT, YopE, and YopH act to antagonize phagocytosis in macrophages. Because Yops do not completely block phagocytosis and Y. pseudotuberculosis can replicate in macrophages, it is important to determine if the T3SS modulates host responses to intracellular bacteria. Isogenic pYV-cured, pYV(+) wild-type, and yop mutant Y. pseudotuberculosis strains were allowed to infect bone marrow-derived murine macrophages at a low multiplicity of infection under conditions in which the survival of extracellular bacteria was prevented. Phagocytosis, the intracellular survival of the bacteria, and the apoptosis of the infected macrophages were analyzed. Forty percent of cell-associated wild-type bacteria were intracellular after a 20-min infection, allowing the study of the macrophage response to internalized pYV(+) Y. pseudotuberculosis. Interestingly, macrophages restricted survival of pYV(+) but not pYV-cured or DeltayopB Y. pseudotuberculosis within phagosomes: only a small fraction of the pYV(+) bacteria internalized replicated by 24 h. In addition, approximately 20% of macrophages infected with wild-type pYV(+) Y. pseudotuberculosis died of apoptosis after 20 h. Analysis of yop mutants expressing catalytically inactive effectors revealed that YopJ was important for apoptosis, while a role for YopE, YopH, and YopT in modulating macrophage responses to intracellular bacteria could not be identified. Apoptosis was reduced in Toll-like receptor 4-deficient macrophages, indicating that cell death required signaling through this receptor. Treatment of macrophages harboring intracellular pYV(+) Y. pseudotuberculosis with chloramphenicol reduced apoptosis, indicating that the de novo bacterial protein synthesis was necessary for cell death. Our finding that the presence of a functional T3SS impacts the survival of both bacterium and host following phagocytosis of Y. pseudotuberculosis suggests new roles for the T3SS in Yersinia pathogenesis.
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Affiliation(s)
- Yue Zhang
- Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, SUNY Stony Brook, Stony Brook, New York 11794-5222, USA.
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Adkins I, Köberle M, Gröbner S, Autenrieth SE, Bohn E, Borgmann S, Autenrieth IB. Y. enterocolitica inhibits antigen degradation in dendritic cells. Microbes Infect 2008; 10:798-806. [DOI: 10.1016/j.micinf.2008.04.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 04/03/2008] [Accepted: 04/16/2008] [Indexed: 10/22/2022]
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Tobback E, Decostere A, Hermans K, Haesebrouck F, Chiers K. Yersinia ruckeri infections in salmonid fish. JOURNAL OF FISH DISEASES 2007; 30:257-68. [PMID: 17501736 DOI: 10.1111/j.1365-2761.2007.00816.x] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Yersinia ruckeri is the causative agent of yersiniosis or enteric redmouth disease leading to significant economic losses in salmonid aquaculture worldwide. Infection may result in a septicaemic condition with haemorrhages on the body surface and in the internal organs. Despite the significance of the disease, very little information is available on the pathogenesis, hampering the development of preventive measures to efficiently combat this bacterial agent. This review discusses the agent and the disease it causes. The possibility of the presence of similar virulence markers and/or pathogenic mechanisms between the Yersinia species which elicit disease in humans and Y. ruckeri is also examined.
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Affiliation(s)
- E Tobback
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
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21
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Grabenstein JP, Fukuto HS, Palmer LE, Bliska JB. Characterization of phagosome trafficking and identification of PhoP-regulated genes important for survival of Yersinia pestis in macrophages. Infect Immun 2006; 74:3727-41. [PMID: 16790745 PMCID: PMC1489716 DOI: 10.1128/iai.00255-06] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The transcriptional activator PhoP is important for survival of Yersinia pestis in macrophage phagosomes. However, the phagosomes inhabited by Y. pestis have not been well characterized, and the mechanism by which PhoP promotes bacterial survival in these vacuoles is not fully understood. Lysosomal tracers, as well as antibodies to late endosomal or lysosomal proteins, were used in conjunction with confocal or electron microscopy to study the trafficking of phagosomes containing phoP(+) or phoP mutant Y. pestis strains or latex beads in J774A.1 macrophages. Phagosomes containing phoP(+) or phoP mutant Y. pestis acquired lysosomal markers to the same degree that phagosomes containing latex beads acquired these markers after 1.5 h of infection, showing that nascent phagosomes containing Y. pestis fuse with lysosomes irrespective of the phoP genotype. Similar results were obtained when phagosomes containing viable or dead phoP(+) Y. pestis cells or beads were analyzed at 8 h postinfection, indicating that the Y. pestis vacuole does not become secluded from the lysosomal compartment. However, only viable phoP(+) bacteria induced the formation of spacious phagosomes at 8 h postinfection, suggesting that Y. pestis can actively direct the expansion of its vacuole. PhoP-regulated genes that are important for survival of Y. pestis in phagosomes were identified by Tn5-lacZ mutagenesis and oligonucleotide microarray analysis. Three such genes were identified, and the products of these genes are predicted to promote resistance to antimicrobial peptides (ugd and pmrK) or low-Mg(2+) conditions (mgtC) found in phagosomes. Viable count assays carried out with Y. pestis ugd, mgtC, and ugd mgtC mutants revealed that the products of ugd and mgtC function independently to promote early survival of Y. pestis in macrophage phagosomes.
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Affiliation(s)
- Jens P Grabenstein
- Department of Molecular Genetics and Microbiology and Center for Infectious Diseases, SUNY at Stony Brook, Stony Brook, NY 11794-5222, USA
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22
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Pujol C, Bliska JB. Turning Yersinia pathogenesis outside in: subversion of macrophage function by intracellular yersiniae. Clin Immunol 2005; 114:216-26. [PMID: 15721832 DOI: 10.1016/j.clim.2004.07.013] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Accepted: 07/22/2004] [Indexed: 01/13/2023]
Abstract
Three bacterial species within the genus Yersinia are causative agents of human disease. Yersinia pestis is transmitted by fleas or in aerosols, infects regional lymph nodes or lungs, and causes the highly lethal disease known as plague. Yersinia enterocolitica and Yersinia pseudotuberculosis are enteric pathogens most commonly associated with self-limiting infections of the mesenteric lymph nodes. Although Y. pestis and the enteropathogenic Yersinia species utilize different modes of transmission and cause different diseases, they rely on a common set of "core" virulence determinants to successfully infect a mammalian host. These virulence factors are encoded on the bacterial chromosome and on an approximately 70-kb plasmid. Once established in lymphoid tissue, all three Yersinia species replicate as aggregates of extracellular bacteria within necrotic lesions or abscesses. At this stage of the infectious process, the bacteria resist phagocytosis by neutrophils, which are able to destroy the bacteria if they are internalized. A type III secretion system encoded on the 70-kb plasmid functions to export multiple proteins (the Yops and LcrV) that are delivered to the extracellular milieu, the plasma membrane, or the cytosol of a host target cell. The Yops and LcrV act in concert to inhibit phagocytosis and downregulate inflammation. Although it is clear that the bulk of bacterial multiplication occurs in an extracellular phase, there is also evidence that all three pathogenic Yersinia survive and multiply in macrophages. Survival and replication of Yersinia in macrophages may occur throughout the infection, but is likely to be of greatest importance at early stages of colonization. That macrophages can serve as permissive sites for bacterial replication in vivo is supported by in vitro experiments, which demonstrate that Y. pestis, Y. peudotuberculosis, and Y. enterocolitica share the ability to survive and multiply in macrophage phagosomes. There is also evidence that the bacteria can subvert the functions of macrophages from within, by inhibiting phagosome acidification (Y. pseudotuberculosis) and the production of nitric oxide (Y. pestis and Y. pseudotuberculosis). Although considerable attention has been focused on how Yersinia subverts the functions of phagocytes from the outside, the study of how these bacteria subvert macrophage functions from the inside will lead to a better overall understanding of Yersinia pathogenesis.
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Affiliation(s)
- Céline Pujol
- Department of Molecular Genetics and Microbiology, and Center for Infectious Diseases, SUNY at Stony Brook, Stony Brook, NY 11794-5222, USA
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Mitra BN, Yasuda T, Kobayashi S, Saito-Nakano Y, Nozaki T. Differences in morphology of phagosomes and kinetics of acidification and degradation in phagosomes between the pathogenicEntamoeba histolytica and the non-pathogenicEntamoeba dispar. ACTA ACUST UNITED AC 2005; 62:84-99. [PMID: 16106449 DOI: 10.1002/cm.20087] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Phagocytosis plays an important role in the pathogenicity of the intestinal protozoan parasite Entamoeba histolytica. We compared the morphology of phagosomes and the kinetics of phagosome maturation using conventional light and electron microscopy and live imaging with video microscopy between the virulent E. histolytica and the closely-related, but non-virulent E. dispar species. Electron micrographs showed that axenically cultivated trophozoites of the two Entamoeba species revealed morphological differences in the number of bacteria contained in a single phagosome and the size of phagosomes. Video microscopy using pH-sensitive fluorescein isothiocynate-conjugated yeasts showed that phagosome acidification occurs within 2 min and persists for >12 h in both species. The acidity of phagosomes significantly differed between two species (4.58 +/- 0.36 or 5.83 +/- 0.38 in E. histolytica or E. dispar, respectively), which correlated well with the differences in the kinetics of degradation of promastigotes of GFP-expressing Leishmania amazonensis. The acidification of phagosomes was significantly inhibited by a myosin inhibitor, whereas it was only marginally inhibited by microtubules or actin inhibitors. A specific inhibitor of vacuolar ATPase, concanamycin A, interrupted both the acidification and degradation in phagosomes in both species, suggesting the ubiquitous role of vacuolar ATPase in the acidification and degradation in Entamoeba. In contrast, inhibitors against microtubules or cysteine proteases (CP) showed distinct effects on degradation in phagosomes between these two species. Although depolymerization of microtubules severely inhibited degradation in phagosomes of E. histolytica, it did not affect degradation in E. dispar. Similarly, the inhibition of CP significantly reduced degradation in phagosomes of E. histolytica, but not in E. dispar. These data suggest the presence of biochemical or functional differences in the involvement of microtubules and proteases in phagosome maturation and degradation between the two species.
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Affiliation(s)
- Biswa Nath Mitra
- Department of Parasitology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-851, Japan
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Grabenstein JP, Marceau M, Pujol C, Simonet M, Bliska JB. The response regulator PhoP of Yersinia pseudotuberculosis is important for replication in macrophages and for virulence. Infect Immun 2004; 72:4973-84. [PMID: 15321989 PMCID: PMC517447 DOI: 10.1128/iai.72.9.4973-4984.2004] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Yersinia pestis and Yersinia pseudotuberculosis are closely related facultative intracellular pathogens. The response regulator PhoP was previously shown to be important for Y. pestis survival in macrophages and for virulence in a murine bubonic plague infection assay. Here the importance of PhoP for Y. pseudotuberculosis pathogenesis was investigated. Y. pseudotuberculosis phoP mutants were unable to replicate in low-Mg(2+) medium or in macrophages. phoP(+) Y. pseudotuberculosis strains initiated replication in macrophages after a lag period of approximately 5 h, as shown by fluorescence microscopy and viable count assays. Y. pseudotuberculosis phoP mutants died at a low rate in macrophages; there was no decrease in viability over the first 5 h of infection, and there was a 10-fold decrease in viability between 5 and 24 h of infection. Trafficking of phagosomes containing phoP(+) or phoP mutant Y. pseudotuberculosis was studied by using immunofluorescence microscopy and cathepsin D as a marker for lysosomes. Phagosomes containing phoP mutant Y. pseudotuberculosis acquired cathepsin D at a higher rate than phagosomes containing phoP(+) bacteria. However, the increased rate of marker acquisition for phagosomes containing mutant bacteria was only evident approximately 5 h after infection, suggesting that phoP mutants are able to retard phagosome maturation during the lag phase of intracellular growth. The results obtained with a Y. pestis phoP mutant were similar to those described above, except that the rates of intracellular killing and trafficking to cathepsin D-positive vacuoles were significantly higher. A Y. pseudotuberculosis phoP mutant was 100-fold less virulent than the wild-type strain in a murine intestinal infection model, suggesting that survival and replication in macrophages are important for Y. pseudotuberculosis pathogenesis.
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Affiliation(s)
- Jens P Grabenstein
- Department of Molecular Genetics and Microbiology and Center for Infectious Diseases, SUNY at Stony Brook, Stony Brook, NY 11794-5222, USA
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Pujol C, Bliska JB. The ability to replicate in macrophages is conserved between Yersinia pestis and Yersinia pseudotuberculosis. Infect Immun 2003; 71:5892-9. [PMID: 14500510 PMCID: PMC201058 DOI: 10.1128/iai.71.10.5892-5899.2003] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Yersinia pestis, the agent of plague, has arisen from a less virulent pathogen, Yersinia pseudotuberculosis, by a rapid evolutionary process. Although Y. pestis displays a large number of virulence phenotypes, it is not yet clear which of these phenotypes descended from Y. pseudotuberculosis and which were acquired independently. Y. pestis is known to replicate in macrophages, but there is no consensus in the literature on whether Y. pseudotuberculosis shares this property. We investigated whether the ability to replicate in macrophages is common to Y. pestis and Y. pseudotuberculosis or is a unique phenotype of Y. pestis. We also examined whether a chromosomal type III secretion system (TTSS) found in Y. pestis is present in Y. pseudotuberculosis and whether this system is important for replication of Yersinia in macrophages. A number of Y. pestis and Y. pseudotuberculosis strains of different biovars and serogroups, respectively, were tested for the ability to replicate in primary murine macrophages. Two Y. pestis strains (EV766 and KIM10(+)) and three Y. pseudotuberculosis strains (IP2790c, IP2515c, and IP2666c) were able to replicate in macrophages with similar efficiencies. Only one of six strains tested, the Y. pseudotuberculosis YPIII(p(-)) strain, was defective for intracellular replication. Thus, the ability to replicate in macrophages is conserved in Y. pestis and Y. pseudotuberculosis. Our results also indicate that a homologous TTSS is present on the chromosomes of Y. pestis and Y. pseudotuberculosis and that this secretion system is not required for replication of these bacteria in macrophages.
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Affiliation(s)
- Céline Pujol
- Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, State University of New York at Stony Brook, Stony Brook, NY 11794-5222, USA
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Ibrahim-Granet O, Philippe B, Boleti H, Boisvieux-Ulrich E, Grenet D, Stern M, Latgé JP. Phagocytosis and intracellular fate of Aspergillus fumigatus conidia in alveolar macrophages. Infect Immun 2003; 71:891-903. [PMID: 12540571 PMCID: PMC145364 DOI: 10.1128/iai.71.2.891-903.2003] [Citation(s) in RCA: 191] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Aspergillus fumigatus is the most prevalent airborne fungal pathogen responsible for fatal invasive aspergillosis in immunocompromised patients. Upon arrival in the lung alveolus, conidia of A. fumigatus are phagocytosed by alveolar macrophages, the major phagocytic cells of the lung. Engulfment and intracellular trafficking of A. fumigatus conidia in alveolar macrophages of two different origins, the murine cell line MH-S and human pulmonary alveolar macrophages, were analyzed by electron microscopy and immunofluorescence. Phagocytosis of A. fumigatus conidia required actin polymerization and phosphatidylinositol 3-kinase activity. Fusion of A. fumigatus phagosomes with early and late endosomes was shown by immunolabeling with specific markers for the transferrin receptor, early endosome antigen, and Rab7. Maturation of A. fumigatus phagolysosomes was monitored by using a fixable acidotropic probe, LysoTracker Red DND-99, and an anti-cathepsin D antibody. Bafilomycin A-induced inhibition of lysosomal acidification abolished the conidial killing by the macrophages. These data suggest that the maturation of A. fumigatus phagosomes results from fusion with the compartments of the endocytic pathway and that the killing of conidia depends on phagolysosome acidification. A model for the phagocytosis of A. fumigatus conidia by alveolar macrophages is proposed on the basis of these results.
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Affiliation(s)
- O Ibrahim-Granet
- Unité des Aspergillus, Institut Pasteur, 75724 Paris Cedex 15, France
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Korshunov SS, Imlay JA. A potential role for periplasmic superoxide dismutase in blocking the penetration of external superoxide into the cytosol of Gram-negative bacteria. Mol Microbiol 2002; 43:95-106. [PMID: 11849539 DOI: 10.1046/j.1365-2958.2002.02719.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Superoxide is a key component of the antibacterial weaponry of phagocytes. Presumably, for this reason, strains of Salmonella typhimurium express a periplasmic superoxide dismutase (SOD) that is essential for full virulence. Because most anions cannot easily penetrate lipid membranes, it is thought that the phagosomal superoxide either damages an unknown target on the bacterial surface or reacts with nitric oxide to form peroxynitrite (HOONO), a toxic oxidant that can freely enter bacteria. However, in this study, we tested whether superoxide itself could penetrate membranes. Superoxide that was generated at high pH (>7.5) very slowly reduced cytochrome c that was encapsulated inside lipid vesicles. It did so much more quickly at lower pH (<7). Under the latter conditions, more superoxide was protonated and uncharged (HO2*), and the penetrance of superoxide was proportional to the concentration of this species. The permeability coefficient of HO2* was determined to be 9 x 10(-4) cm sec(-1), just slightly lower than that of water and far higher than the value of the anionic form (O2-, <10(-7) cm sec(-1). When Escherichia coli mutants that lack periplasmic SOD were exposed to super-oxide at pH 6.5, cytosolic fumarase B was damaged. Damage was minimal at higher pH or in strains that contained periplasmic SOD. Thus, in the acidic phagolysosome, superoxide may be able to penetrate and attack cytosolic targets of captive bacteria. This process may contribute to the potency of the oxidative burst. One role of periplasmic SOD may be to avert this damage. In contrast, periplasmic SOD was ineffective at lowering the extracellular super-oxide concentration and, therefore, may have little impact upon HOONO formation.
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Affiliation(s)
- Sergei S Korshunov
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
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Maurin M, Raoult D. Use of aminoglycosides in treatment of infections due to intracellular bacteria. Antimicrob Agents Chemother 2001; 45:2977-86. [PMID: 11600345 PMCID: PMC90771 DOI: 10.1128/aac.45.11.2977-2986.2001] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- M Maurin
- Unité des Rickettsies, CNRS UPRES A 6020, Faculté de Médecine, Université de la Méditerranée, 13385 Marseille Cedex 05, France
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