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McNally A, Dalton T, Ragione RML, Stapleton K, Manning G, Newell DG. Yersinia enterocolitica isolates of differing biotypes from humans and animals are adherent, invasive and persist in macrophages, but differ in cytokine secretion profiles in vitro. J Med Microbiol 2006; 55:1725-1734. [PMID: 17108278 DOI: 10.1099/jmm.0.46726-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Previous epidemiological studies have demonstrated a potential link between the serotypes of Yersinia enterocolitica recovered from cattle, sheep and pigs and those isolated from human disease cases. Further studies utilizing amplified fragment length polymorphisms have shown a relationship at the genetic level between strains of biotypes 3 and 4 from humans and livestock, and also suggested that some biotype 1A isolates, classically defined as non-pathogenic, are closely related to biotype 3 and 4 isolates. This study sought to understand further the pathogenic potential of Y. enterocolitica isolates from livestock in Great Britain. A range of surrogate in vitro models, such as invasion of epithelial tissue cultures, survival in cultured macrophages and cytokine secretion response, was employed to assess the pathogenicity of 88 strains. The results suggested that all isolates examined were capable of adhering to and invading epithelial cells and of surviving within macrophages. However, the inflammatory response of the infected macrophages differed with the infecting Y. enterocolitica subtype, with the response to pathogenic biotype 3 and 4 isolates different to that observed with biotype 1A isolates, and with the biotype 3 O : 5,27 isolates recovered exclusively from animals. Infections of porcine tissue also suggested the possibility of host-tissue tropism within Y. enterocolitica subtypes.
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Affiliation(s)
- Alan McNally
- Veterinary Laboratories Agency, Woodham Lane, New Haw, Surrey KT15 3NB, UK
| | - Tracey Dalton
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E, UK
| | | | - Kenneth Stapleton
- Veterinary Laboratories Agency, Woodham Lane, New Haw, Surrey KT15 3NB, UK
| | - Georgina Manning
- Veterinary Laboratories Agency, Woodham Lane, New Haw, Surrey KT15 3NB, UK
| | - Diane G Newell
- Veterinary Laboratories Agency, Woodham Lane, New Haw, Surrey KT15 3NB, UK
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52
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Schroeder GN, Hilbi H. Cholesterol is required to trigger caspase-1 activation and macrophage apoptosis after phagosomal escape of Shigella. Cell Microbiol 2006; 9:265-78. [PMID: 16925787 DOI: 10.1111/j.1462-5822.2006.00787.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Pro-inflammatory macrophage apoptosis is pivotal in the aetiology of bacillary dysentery, an acute inflammatory diarrhoea caused by Shigella spp. S. flexneri triggers its uptake by macrophages, escapes the phagosome and kills the host cell by a cytotoxic pathway, which activates and requires caspase-1 [interleukin (IL)-1beta-converting enzyme] and releases mature IL-1beta. The bacterial type III-secreted translocator/effector protein IpaB triggers cell death and directly binds to caspase-1. Here, we demonstrate that in S. flexneri-infected macrophages, activated caspase-1 is present in the cytoplasm, the nucleus and on vesicular membranes. IpaB partitions with membrane and cytoplasmic fractions and colocalizes with activated caspase-1 on the surface of bacteria, in the macrophage cytoplasm and on vesicular membranes. Macrophages treated with the cholesterol-sequestering compound methyl-beta-cyclodextrin (MCD) were depleted from cholesterol within minutes and were impaired for phagocytosis of S. flexneri. Consequently, cytotoxicity as determined by lactate dehydrogenase release was blocked. Interestingly, if MCD was added 15-30 min post infection, cytotoxicity, activation of caspase-1, and apoptosis were inhibited, while phagocytosis of the bacteria, escape from the phagosome and type III secretion of IpaB was not affected. Inhibition of Shigella cytotoxicity by MCD coincided with a reduced association of IpaB to host cell membranes. Contrarily, the activation of caspase-1 and cytotoxicity triggered by the K+/H+ antiport ionophore nigericin or by ATP was not affected or even increased by MCD. These results indicate that cholesterol is specifically required for caspase-1 activation and apoptosis triggered by Shigella after the escape from phagosomes, and suggest that membrane association of IpaB contributes to the activation of caspase-1.
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Affiliation(s)
- Gunnar N Schroeder
- Institute of Microbiology, ETH Zürich, Wolfgang-Pauli Strasse 10, 8093 Zürich, Switzerland
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53
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Ingersoll MA, Zychlinsky A. ShiA abrogates the innate T-cell response to Shigella flexneri infection. Infect Immun 2006; 74:2317-27. [PMID: 16552062 PMCID: PMC1418937 DOI: 10.1128/iai.74.4.2317-2327.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Revised: 12/05/2005] [Accepted: 01/18/2006] [Indexed: 01/22/2023] Open
Abstract
Shigella spp. are the causative agent of bacillary dysentery. Infection results in acute colonic injury due to the host inflammatory response. The mediators of the damage, infiltrating polymorphonuclear leukocytes (PMN), also resolve the infection. Shigella flexneri's virulence effectors are encoded on its large virulence plasmid and on pathogenicity islands in the chromosome. The SHI-2 pathogenicity island encodes the virulence factor ShiA, which down-regulates Shigella-induced inflammation. In the rabbit ileal loop model, infection with a shiA null strain (DeltashiA) induces a more severe inflammation than wild-type infection. Conversely, a Shigella strain that overexpresses ShiA (ShiA+) is less inflammatory than the wild-type strain. To determine the host responses modulated by ShiA, we performed infection studies using the mouse lung model, which recapitulates the phenotypes observed in the rabbit ileal loop model. Significantly, ShiA+ strain-infected mice cleared the bacteria and survived infection, while wild-type- and DeltashiA strain-infected mice could not clear the bacteria and ultimately died. Surprisingly, microarray analysis of infected lungs revealed the regulation of genes involved in innate T-cell responses to infection. Immunohistochemistry showed that wild-type- and DeltashiA strain-infected animals have greater numbers of PMN and T cells in their lungs over the course of infection than ShiA+ strain-infected animals. These results suggest that the T-cell innate response is suppressed by ShiA in Shigella infections.
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MESH Headings
- Animals
- Bacterial Proteins/biosynthesis
- Bacterial Proteins/genetics
- Bacterial Proteins/toxicity
- Disease Models, Animal
- Dose-Response Relationship, Immunologic
- Down-Regulation/genetics
- Down-Regulation/immunology
- Dysentery, Bacillary/immunology
- Dysentery, Bacillary/microbiology
- Dysentery, Bacillary/pathology
- Gene Expression Profiling
- Immunity, Innate
- Inflammation Mediators/metabolism
- Inflammation Mediators/toxicity
- Lymphocyte Count
- Mice
- Mice, Inbred C57BL
- Neutrophil Activation/immunology
- Neutrophil Infiltration/immunology
- Oligonucleotide Array Sequence Analysis
- Pneumonia, Bacterial/immunology
- Pneumonia, Bacterial/microbiology
- Pneumonia, Bacterial/pathology
- Pneumonia, Bacterial/prevention & control
- Shigella flexneri/genetics
- Shigella flexneri/immunology
- Shigella flexneri/pathogenicity
- Survival Analysis
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- T-Lymphocytes/microbiology
- T-Lymphocytes/pathology
- Virulence Factors/biosynthesis
- Virulence Factors/genetics
- Virulence Factors/toxicity
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Affiliation(s)
- Molly A Ingersoll
- Max Planck Institute for Infection Biology, 21/22 Schumannstrasse, 10117 Berlin, Germany
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54
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Bastiani M, Vidotto MC, Horn F. An avian pathogenic Escherichia coli isolate induces caspase 3/7 activation in J774 macrophages. FEMS Microbiol Lett 2006; 253:133-40. [PMID: 16239084 DOI: 10.1016/j.femsle.2005.09.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 09/12/2005] [Accepted: 09/19/2005] [Indexed: 11/20/2022] Open
Abstract
Avian pathogenic Escherichia coli (APEC) strains, the etiological agent of colibacillosis in poultry, must resist the attack of incoming macrophages in order to cause disease. In this work, we show that an APEC strain (APEC17) remained viable inside J774 macrophages for at least 8 h and was cytotoxic to them 6-8 h after infection. APEC17 induced caspase 3/7 activation, the central caspases in apoptosis, in infected macrophages already at 2h after infection. Both cytotoxicity and caspase 3/7 activation were reduced when cells were infected with heat-killed APEC17, showing that bacteria must be viable to induce apoptosis. Our findings using APEC17 suggest that APEC may escape destruction by triggering macrophage apoptotic death.
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Affiliation(s)
- Michele Bastiani
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul, P.O. Box 15005, 91501-970 Porto Alegre, RS, Brazil
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55
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Luck SN, Bennett-Wood V, Poon R, Robins-Browne RM, Hartland EL. Invasion of epithelial cells by locus of enterocyte effacement-negative enterohemorrhagic Escherichia coli. Infect Immun 2005; 73:3063-71. [PMID: 15845514 PMCID: PMC1087320 DOI: 10.1128/iai.73.5.3063-3071.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The majority of enterohemorrhagic Escherichia coli (EHEC) strains associated with severe disease carry the locus of enterocyte effacement (LEE) pathogenicity island, which encodes the ability to induce attaching and effacing lesions on the host intestinal mucosa. While LEE is essential for colonization of the host in these pathogens, strains of EHEC that do not carry LEE are regularly isolated from patients with severe disease, although little is known about the way these organisms interact with the host epithelium. In this study, we compared the adherence properties of clinical isolates of LEE-negative EHEC with those of LEE-positive EHEC O157:H7. Transmission electron microscopy revealed that LEE-negative EHEC O113:H21 was internalized by Chinese hamster ovary (CHO-K1) epithelial cells and that intracellular bacteria were located within a membrane-bound vacuole. In contrast, EHEC O157:H7 remained extracellular and intimately attached to the epithelial cell surface. Quantitative gentamicin protection assays confirmed that EHEC O113:H21 was invasive and also showed that several other serogroups of LEE-negative EHEC were internalized by CHO-K1 cells. Invasion by EHEC O113:H21 was significantly reduced in the presence of the cytoskeletal inhibitors cytochalasin D and colchicine and the pan-Rho GTPase inhibitor compactin, whereas the tyrosine kinase inhibitor genistein had no significant impact on bacterial invasion. In addition, we found that EHEC O113:H21 was invasive for the human colonic cell lines HCT-8 and Caco-2. Overall these studies suggest that isolates of LEE-negative EHEC may employ a mechanism of host cell invasion to colonize the intestinal mucosa.
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Affiliation(s)
- Shelley N Luck
- Department of Microbiology, Monash University, Victoria 3800, Australia
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56
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Hertle R, Schwarz H. Serratia marcescens internalization and replication in human bladder epithelial cells. BMC Infect Dis 2004; 4:16. [PMID: 15189566 PMCID: PMC441377 DOI: 10.1186/1471-2334-4-16] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Accepted: 06/09/2004] [Indexed: 11/10/2022] Open
Abstract
Background Serratia marcescens, a frequent agent of catheterization-associated bacteriuria, strongly adheres to human bladder epithelial cells in culture. The epithelium normally provides a barrier between lumal organisms and the interstitium; the tight adhesion of bacteria to the epithelial cells can lead to internalization and subsequent lysis. However, internalisation was not shown yet for S. marcescens strains. Methods Elektronmicroscopy and the common gentamycin protection assay was used to assess intracellular bacteria. Via site directed mutagenesis, an hemolytic negative isogenic Serratia strain was generated to point out the importance of hemolysin production. Results We identified an important bacterial factor mediating the internalization of S. marcescens, and lysis of epithelial cells, as the secreted cytolysin ShlA. Microtubule filaments and actin filaments were shown to be involved in internalization. However, cytolysis of eukaryotic cells by ShlA was an interfering factor, and therefore hemolytic-negative mutants were used in subsequent experiments. Isogenic hemolysin-negative mutant strains were still adhesive, but were no longer cytotoxic, did not disrupt the cell culture monolayer, and were no longer internalized by HEp-2 and RT112 bladder epithelial cells under the conditions used for the wild-type strain. After wild-type S. marcescens became intracellular, the infected epithelial cells were lysed by extended vacuolation induced by ShlA. In late stages of vacuolation, highly motile S. marcescens cells were observed in the vacuoles. S. marcescens was also able to replicate in cultured HEp-2 cells, and replication was not dependent on hemolysin production. Conclusion The results reported here showed that the pore-forming toxin ShlA triggers microtubule-dependent invasion and is the main factor inducing lysis of the epithelial cells to release the bacteria, and therefore plays a major role in the development of S. marcescens infections.
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Affiliation(s)
- Ralf Hertle
- Microbiology/Membranphysiology, University of Tübingen, Germany
| | - Heinz Schwarz
- Max Planck Institute for Developmental Biology, Tübingen, Germany
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57
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Ingersoll MA, Moss JE, Weinrauch Y, Fisher PE, Groisman EA, Zychlinsky A. The ShiA protein encoded by theShigella flexneriSHI-2 pathogenicity island attenuates inflammation. Cell Microbiol 2003; 5:797-807. [PMID: 14531895 DOI: 10.1046/j.1462-5822.2003.00320.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Shigella spp. are the aetiologic agents of dysentery, a severe diarrhoeal syndrome characterized by acute inflammation in the colon. The inflammatory response, which includes recruitment of polymorphonuclear leukocytes (PMN), damages the colonic mucosa and exacerbates the infection. Shigella encodes a pathogenicity island (PAI), SHI-2, which is localized in a region of the chromosome linked to the induction of inflammation. Surprisingly, SHI-2 deletion mutants induce a stronger inflammatory response than wild-type Shigella as measured by increased villus blunting, increased PMN infiltration and induction of apoptosis in a rabbit ileal loop model of shigellosis. Mutational analysis mapped the hyper-inflammatory phenotype to a single gene, shiA. Similar to SHI-2 deletion mutants, infection with a shiA mutant strain induces dramatically elevated levels of inflammation when compared to the wild-type strain. Furthermore, infection with a wild-type strain containing multiple copies of shiA results in fewer infiltrating PMN and apoptotic cells, as well as preservation of a normal villus architecture at the site of infection, thus acting in a dominant fashion over the pro-inflammatory mechanisms of Shigella. The molecular mechanism of action of ShiA is independent of any in vitro phenotype associated with Shigella virulence. Our data suggest that ShiA allows Shigella to attenuate the host inflammatory response in a novel manner.
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Affiliation(s)
- Molly A Ingersoll
- Max Planck Institute for Infection Biology, 21/22 Schumannstrasse, 10117 Berlin, Germany
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58
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Fratamico PM. Tolerance to stress and ability of acid-adapted and non-acid-adapted Salmonella enterica serovar Typhimurium DT104 to invade and survive in mammalian cells in vitro. J Food Prot 2003; 66:1115-25. [PMID: 12870742 DOI: 10.4315/0362-028x-66.7.1115] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The ability of acid-adapted (AA) and non-acid-adapted (NA) Salmonella enterica serovar Typhimurium definitive type 104 (DT104) strains to invade and multiply in mammalian cells in vitro and to survive stress conditions was examined. DT104 and non-DT104 strains were grown in tryptic soy broth without glucose (NA) or in tryptic soy broth containing 1% glucose (AA) for 18 h at 37 degrees C. The invasiveness of DT104 strains in J774A.1 macrophage and Int407 intestinal cell lines was not more extensive than that of non-DT104 strains. In most cases, AA bacteria were less invasive than NA bacteria in both cell lines. Confocal microscopy showed that both DT104 and non-DT104 strains replicated in the two cell lines. In related studies, the survival levels of three strains of AA and NA DT104 and a non-DT104 (LT2) strain in 150 and 15 mM H2O2, 170 and 43 mM acetic acid, 2.6 M NaCl, 2.6 M NaCl containing 170 mM acetic acid, synthetic gastric fluid (SGF) at pH 2 and pH 3, and apple cider were compared. For all four strains, acid adaptation did not result in increased survival in apple cider. After 15 days of storage at 4 degrees C, reductions ranged from 1.96 to 4.1 log10 CFU/ml for AA bacteria and from 0.48 to 1.34 log10 CFU/ml for NA bacteria from a starting level of ca. 7.00 log10 CFU/ml of cider. Neither AA nor NA DT104 strains were more resistant to NaCl, acetic acid, H2O2, or SGF solutions than non-DT104 strain LT2. The level of AA bacteria was not appreciably reduced after exposure to SGF; however, the level of NA bacteria decreased to nondetectable levels in SGF at pH 2 within 3 h of exposure. These results indicate that the DT104 strains examined were not more invasive, nor did they display increased survival in mammalian cells or increased resistance to food environment stresses compared with non-DT104 strains. However, acid adaptation resulted in increased resistance to a low-pH gastric environment for all strains tested. These data indicate that DT104 strains are likely not more virulent or resistant to stresses relevant to foods than are non-DT104 Salmonella and that procedures used to inactivate or inhibit the growth of Salmonella in foods are likely adequate for DT104 strains.
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Affiliation(s)
- Pina M Fratamico
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
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59
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Petersen AM, Krogfelt KA. Helicobacter pylori: an invading microorganism? A review. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 2003; 36:117-26. [PMID: 12738380 DOI: 10.1016/s0928-8244(03)00020-8] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In this review we evaluate the pros and cons of Helicobacter pylori invasion of epithelial cells as part of the natural history of H. pylori infection. H. pylori is generally considered an extracellular microorganism. However, a growing body of evidence supports the controversial hypothesis that at least a subset of H. pylori microorganisms has an intracellular (intraepithelial) location. Most significant is the fact that H. pylori invades cultured epithelial cells with invasion frequencies similar to Yersinia enterocolitica and better than Shigella flexneri; furthermore, studies of invasion mechanisms suggest that H. pylori invasion of and survival within epithelial cells is not merely a passive event, but requires active participation of the microorganism. Although many studies of human gastric biopsy specimens have failed to demonstrate any intracellular H. pylori, some studies have revealed a minor fraction of H. pylori inside gastric epithelial cells, with possible linkage to peptic ulceration and epithelial cell damage. In conclusion, these data encourage further research to establish whether intracellular H. pylori does play a role in H. pylori colonization of the human stomach and in peptic ulcer pathogenesis.
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Affiliation(s)
- Andreas Munk Petersen
- Department of Gastrointestinal Infections, Statens Serum Institut, 5 Artillerivej, 2300 Copenhagen S, Denmark
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60
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Limongi CL, De Souza W, Rozental S. Protein kinase antagonists inhibit invasion of mammalian cells by Fonsecaea pedrosoi. J Med Microbiol 2003; 52:201-209. [PMID: 12621084 DOI: 10.1099/jmm.0.04945-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The phosphorylation process is an important mechanism of cell signalling and regulation. It has been implicated recently in defence strategies against a variety of pathogens that alter host signalling pathways in order to facilitate their invasion and survival within host cells. In this study, the involvement of protein kinases (PKs) has been investigated in attachment and invasion by the pathogenic fungus Fonsecaea pedrosoi within epithelial cells and macrophages. The use of the PK inhibitors staurosporine, genistein and calphostin C prior to infection provided significant information about the role played by PKs in the F. pedrosoi-host cell interaction. All three PK inhibitors could reduce cell invasion by F. pedrosoi significantly. Pre-treatment of macrophages, epithelial cells or conidia with PK inhibitors decreased fungus invasion, and this effect could be overcome by okadaic acid, a phosphatase inhibitor. Immunofluorescence assays showed that tyrosine residues were phosphorylated in the first step of the interaction, while serine residues were phosphorylated in the subsequent step of entry of the parasite into the host cell. These results suggest that both host-cell and conidium PK activities are important in the interaction process, playing a significant role in cell invasion.
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Affiliation(s)
- Cristiana L Limongi
- Laboratório de Biologia Celular de Fungos1 and Laboratório de Ultraestrutura Celular Hertha Meyer2, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Wanderley De Souza
- Laboratório de Biologia Celular de Fungos1 and Laboratório de Ultraestrutura Celular Hertha Meyer2, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Sonia Rozental
- Laboratório de Biologia Celular de Fungos1 and Laboratório de Ultraestrutura Celular Hertha Meyer2, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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61
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Scidmore MA, Fischer ER, Hackstadt T. Restricted fusion of Chlamydia trachomatis vesicles with endocytic compartments during the initial stages of infection. Infect Immun 2003; 71:973-84. [PMID: 12540580 PMCID: PMC145390 DOI: 10.1128/iai.71.2.973-984.2003] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The chlamydial inclusion occupies a unique niche within the eukaryotic cell that does not interact with endocytic compartments but instead is fusogenic with a subset of sphingomyelin-containing exocytic vesicles. The Chlamydia trachomatis inclusion acquires these distinctive properties by as early as 2 h postinfection as demonstrated by the ability to acquire sphingomyelin, endogenously synthesized from 6[N-[(7-nitrobenzo-2-oxa-1,3-diazol-4-yl)amino]caproylsphingosine] (C(6)-NBD-ceramide). The molecular mechanisms involved in transformation of the properties and cellular interactions of the inclusion are unknown except that they require early chlamydial transcription and translation. Although the properties of the inclusion are established by 2 h postinfection, the degree of interaction with endocytic pathways during the brief interval before fusogenicity with an exocytic pathway is established is unknown. Using a combination of confocal and electron microscopy to localize endocytic and lysosomal markers in C. trachomatis infected cells during the early stages of infection, we demonstrate a lack of these markers within the inclusion membrane or lumen of the inclusion to conclude that the nascent chlamydial inclusion is minimally interactive with endosomal compartments during this interval early in infection. Even when prevented from modifying the properties of the inclusion by incubation in the presence of protein synthesis inhibitors, vesicles containing elementary bodies are very slow to acquire lysosomal characteristics. These results imply a two-stage mechanism for chlamydial avoidance of lysosomal fusion: (i) an initial phase of delayed maturation to lysosomes due to an intrinsic property of elementary bodies and (ii) an active modification of the vesicular interactions of the inclusion requiring chlamydial protein synthesis.
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Affiliation(s)
- Marci A Scidmore
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana 59840, USA
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62
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Darfeuille-Michaud A. Adherent-invasive Escherichia coli: a putative new E. coli pathotype associated with Crohn's disease. Int J Med Microbiol 2002; 292:185-93. [PMID: 12398209 DOI: 10.1078/1438-4221-00201] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Crohn's disease (CD) is an inflammatory bowel disease (IBD) of unknown aetiology. Genetically engineered rodent models showed that IBDs are immunologically mediated and that luminal bacteria play an essential role in the development of the inflammation. Various bacterial pathogens have been incriminated but results have been conflicting. A new pathovar of E. coli, designated adherent-invasive Escherichia coli (AIEC) may be associated with CD. AIEC strains colonize the intestinal mucosa by adhering to intestinal epithelial cells. They are also true invasive pathogens, able to invade intestinal epithelial cells via a macropinocytosis-like process, and to survive and replicate intracellularly after lysis of the endocytic vacuole. Within macrophages, AIEC strains survive and replicate extensively without inducing host cell death and induce the release of high amounts of TNFalpha. All these virulence properties designate AIEC as a possible pathogen potentially able to induce persistent intestinal inflammation, by crossing and breaching the intestinal barrier, moving to deep tissues, and continuously activating macrophages.
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Affiliation(s)
- Arlette Darfeuille-Michaud
- Pathogénie Bactérienne Intestinale, Institut Universitaire de Technologie et Faculté de Pharmacie, Université d'Auvergne, Clermont-Ferrand, France.
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64
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Steele-Mortimer O, Brumell JH, Knodler LA, Méresse S, Lopez A, Finlay BB. The invasion-associated type III secretion system of Salmonella enterica serovar Typhimurium is necessary for intracellular proliferation and vacuole biogenesis in epithelial cells. Cell Microbiol 2002; 4:43-54. [PMID: 11856172 DOI: 10.1046/j.1462-5822.2002.00170.x] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Type III secretion systems (TTSS) are used by Gram-negative pathogens to translocate proteins into eukaryotic host cells. Salmonella enterica serovar Typhimurium (S. Typhimurium) has two of these specialized systems, which are encoded on separate Salmonella pathogenicity islands (SPI-1 and SPI-2) and translocate unique sets of effectors. The specific roles of these systems in Salmonella pathogenesis remain undefined, although SPI-1 is required for bacterial invasion of epithelial cells and SPI-2 for survival/replication in phagocytic cells. However, because SPI-1 TTSS mutants are invasion-incompetent, the role of this TTSS in post-invasion processes has not been investigated. In this study, we have used two distinct methods to internalize a non-invasive SPI-1 TTSS mutant (invA) into cultured epithelial cells: (i) co-internalization with wild-type S. Typhimurium (SPI-1-dependent) and (ii) complementation with the Yersinia pseudotuberculosis invasin (inv) gene (SPI-1-independent). In both cases, internalized invA mutants were unable to replicate intracellularly, indicating that SPI-1 effectors are essential for this process and cannot be complemented by wild-type bacteria in the same cell. Analysis of the biogenesis of SCVs showed that vacuoles containing mutant bacteria displayed abnormal maturation that was dependent on the mechanism of entry. Manipulation of Salmonella-containing vacuole (SCV) biogenesis by pharmacologically perturbing membrane trafficking in the host cell increased intracellular replication of wild-type but not mutant S. Typhimurium This demonstrates a previously unknown role for SPI-1 in vacuole biogenesis and intracellular survival in non-phagocytic cells.
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65
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Pathogenicity Islands of Shigella. Curr Top Microbiol Immunol 2002. [DOI: 10.1007/978-3-662-09217-0_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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66
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Guzmán-Verri C, Chaves-Olarte E, von Eichel-Streiber C, López-Goñi I, Thelestam M, Arvidson S, Gorvel JP, Moreno E. GTPases of the Rho subfamily are required for Brucella abortus internalization in nonprofessional phagocytes: direct activation of Cdc42. J Biol Chem 2001; 276:44435-43. [PMID: 11579087 DOI: 10.1074/jbc.m105606200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the genus Brucella are intracellular alpha-Proteobacteria responsible for brucellosis, a chronic disease of humans and animals. Little is known about Brucella virulence mechanisms, but the abilities of these bacteria to invade and to survive within cells are decisive factors for causing disease. Transmission electron and fluorescence microscopy of infected nonprofessional phagocytic HeLa cells revealed minor membrane changes accompanied by discrete recruitment of F-actin at the site of Brucella abortus entry. Cell uptake of B. abortus was negatively affected to various degrees by actin, actin-myosin, and microtubule chemical inhibitors. Modulators of MAPKs and protein-tyrosine kinases hampered Brucella cell internalization. Inactivation of Rho small GTPases using clostridial toxins TcdB-10463, TcdB-1470, TcsL-1522, and TcdA significantly reduced the uptake of B. abortus by HeLa cells. In contrast, cytotoxic necrotizing factor from Escherichia coli, known to activate Rho, Rac, and Cdc42 small GTPases, increased the internalization of both virulent and non-virulent B. abortus. Expression of dominant-positive Rho, Rac, and Cdc42 forms in HeLa cells promoted the uptake of B. abortus, whereas expression of dominant-negative forms of these GTPases in HeLa cells hampered Brucella uptake. Cdc42 was activated upon cell contact by virulent B. abortus, but not by a noninvasive isogenic strain, as proven by affinity precipitation of active Rho, Rac, and Cdc42. The polyphasic approach used to discern the molecular events leading to Brucella internalization provides new alternatives for exploring the complexity of the signals required by intracellular pathogens for cell invasion.
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Affiliation(s)
- C Guzmán-Verri
- Programa de Investigación en Enfermedades Tropicales, Escuela de Medicina Veterinaria, Universidad Nacional, P. O. Box 304, 3000 Heredia, Costa Rica
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67
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Velge-Roussel F, Dimier-Poisson I, Buzoni-Gatel D, Bout D. Anti-SAG1 peptide antibodies inhibit the penetration of Toxoplasma gondii tachyzoites into enterocyte cell lines. Parasitology 2001; 123:225-33. [PMID: 11578086 DOI: 10.1017/s0031182001008460] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The initial attachment of Toxoplasma tachyzoites to the target host cell is an important event in the life-cycle of the parasite and a critical stage in infection. Previous studies have shown that polyclonal antibodies directed against the major surface antigen of Toxoplasma gondii (SAG1) inhibit the infection of enterocyte cell lines. Here, we demonstrate that antibodies raised against a central peptide (V41T) of SAG1 and the SAGI protein itself are able to inhibit the infection of various cell lines by the tachyzoites. Antibodies directed against SAG1 peptides were used to define a site on the SAGI antigen that interacts with the host cell. The epitope carried by V41T was identified on the tachyzoite surface by immunofluorescence. The peptide sequence seems to be conserved in all the members of the SAGI Related Sequence family (SRS). Using undifferentiated and differentiated Caco-2 cells, we found that tachyzoites enter preferentially via the basolateral side of the cell. These findings highlight the role of the SRS family members in the mediation of host cell invasion.
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Affiliation(s)
- F Velge-Roussel
- UMR UNIVERSITE-INRA d'Immunologie Parasitaire, UFR des Sciences Pharmaceutiques, Tours, France.
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68
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Abstract
A previous study has shown that YopB of Yersinia spp. is essential for translocation of Yop effectors across the eucaryotic plasma membrane (M.-P. Sory and G. R. Cornelis, Mol. Microbiol. 14:583--594, 1994). However, this role was recently challenged (V. T. Lee and O. Schneewind, Mol. Microbiol. 31:1619--1629, 1999). Using protease protection and digitonin extraction, we reconfirm that YopB of Yersinia enterocolitica is essential for the translocation of YopE into HeLa cell monolayers.
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Affiliation(s)
- R Nordfelth
- Department of Cell and Molecular Biology, Umeå University, 901 87 Umeå, Sweden
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69
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Fuller JD, Bast DJ, Nizet V, Low DE, de Azavedo JC. Streptococcus iniae virulence is associated with a distinct genetic profile. Infect Immun 2001; 69:1994-2000. [PMID: 11254550 PMCID: PMC98122 DOI: 10.1128/iai.69.4.1994-2000.2001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus iniae causes meningoencephalitis and death in commercial fish species and has recently been identified as an emerging human pathogen producing fulminant soft tissue infection. As identified by pulsed-field gel electrophoresis (PFGE), strains causing disease in either fish or humans belong to a single clone, whereas isolates from nondiseased fish are genetically diverse. In this study, we used in vivo and in vitro models to examine the pathogenicity of disease-associated isolates. Strains with the clonal (disease-associated) PFGE profile were found to cause significant weight loss and bacteremia in a mouse model of subcutaneous infection. As little as 10(2) CFU of a disease-associated strain was sufficient to establish bacteremia, with higher inocula (10(7)) resulting in increased mortality. In contrast, non-disease-associated (commensal) strains failed to cause bacteremia and weight loss, even at inocula of 10(8) CFU. In addition, disease-associated strains were more resistant to phagocytic clearance in a human whole blood killing assay compared to commensal strains, which were almost entirely eradicated. Disease-associated strains were also cytotoxic to human endothelial cells as measured by lactate dehydrogenase release from host cells. However, both disease-associated and commensal strains adhered to and invaded cultured human epithelial and endothelial cells equally well. While cellular invasion may still contribute to the pathogenesis of invasive S. iniae disease, resistance to phagocytic clearance and direct cytotoxicity appear to be discriminating virulence attributes of the disease-associated clone.
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Affiliation(s)
- J D Fuller
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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70
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Guichon A, Hersh D, Smith MR, Zychlinsky A. Structure-function analysis of the Shigella virulence factor IpaB. J Bacteriol 2001; 183:1269-76. [PMID: 11157939 PMCID: PMC95000 DOI: 10.1128/jb.183.4.1269-1276.2001] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection by the gram-negative bacterium Shigella flexneri results in dysentery, an acute inflammatory disease of the colon. Essential events in the pathogenesis of Shigella infections include bacterial invasion of epithelial cells, escape from the phagosome, and induction of apoptosis in macrophages. The Shigella virulence factor invasion plasmid antigen B (IpaB) is required for all of these processes. Induction of apoptosis is dependent on IpaB binding to the cysteine protease caspase-1 (Casp-1). The activation of this enzyme triggers both apoptosis and release of the proinflammatory cytokine interleukin-1beta. Several IpaB mutants were generated to correlate function with protein subdomains. We determined that the N-terminal portion of IpaB is necessary for stable expression of IpaB. A putative amphipathic alpha-helical domain preserves the structure of IpaB. We found 10 consecutive residues within the amino terminus of the hydrophobic region that play a critical role in invasion, phagosomal escape, and cytotoxicity. An IpaB mutant carrying a mutation in this region binds to Casp-1 yet is not cytotoxic, even following direct delivery to the macrophage cytoplasm. These results indicate that the association between IpaB and Casp-1 is only a step in the activation of macrophage apoptosis.
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Affiliation(s)
- A Guichon
- The Skirball Institute and Department of Microbiology, New York University Medical Center, New York, New York 10016, USA
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71
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Moss JE, Fisher PE, Vick B, Groisman EA, Zychlinsky A. The regulatory protein PhoP controls susceptibility to the host inflammatory response in Shigella flexneri. Cell Microbiol 2000; 2:443-52. [PMID: 11207599 DOI: 10.1046/j.1462-5822.2000.00065.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The PhoP/PhoQ two-component regulatory system controls transcription of several key virulence genes essential for Salmonella survival in the host cell phagosome. Here, we determine that the PhoP/PhoQ system also regulates virulence in the aetiological agent of bacillary dysentery, Shigella flexneri, even though this pathogen escapes from the phagosome into the cytoplasm of the host cell. A phoP mutant of Shigella established infections and induced an acute inflammatory response in two different animal models. However, infections with phoP mutant bacteria were resolved more rapidly than infections with wild-type Shigella. Moreover, the Shigella phoP mutant was more sensitive than the wild-type strain to killing by polymorphonuclear leucocytes (PMNs), cationic polypeptides extracted from PMNs and other animal-derived antimicrobial peptides. The phoP mutant, however, invaded epithelial cells, spread intercellularly, induced apoptosis in macrophages and tolerated extreme acid pH as efficiently as the wild-type strain. PhoP appears to regulate Shigella susceptibility to PMNs and antimicrobial molecules that are important for the late stages of infection with this enteric bacterium.
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Affiliation(s)
- J E Moss
- Skirball Institute and Department of Microbiology, New York University Medical Center, NY 10016, USA
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72
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Czerucka D, Dahan S, Mograbi B, Rossi B, Rampal P. Saccharomyces boulardii preserves the barrier function and modulates the signal transduction pathway induced in enteropathogenic Escherichia coli-infected T84 cells. Infect Immun 2000; 68:5998-6004. [PMID: 10992512 PMCID: PMC101564 DOI: 10.1128/iai.68.10.5998-6004.2000] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Use of the nonpathogenic yeast Saccharomyces boulardii in the treatment of infectious diarrhea has attracted growing interest. The present study designed to investigate the effect of this yeast on enteropathogenic Escherichia coli (EPEC)-associated disease demonstrates that S. boulardii abrogated the alterations induced by an EPEC strain on transepithelial resistance, [(3)H]inulin flux, and ZO-1 distribution in T84 cells. Moreover, EPEC-mediated apoptosis of epithelial cells was delayed in the presence of S. boulardii. The yeast did not modify the number of adherent bacteria but lowered by 50% the number of intracellular bacteria. Infection by EPEC induced tyrosine phosphorylation of several proteins in T84 cells, including p46 and p52 SHC isoforms, that was attenuated in the presence of S. boulardii. Similarly, EPEC-induced activation of the ERK1/2 mitogen-activated protein (MAP) kinase pathway was diminished in the presence of the yeast. Interestingly, inhibition of the ERK1/2 pathway with the specific inhibitor PD 98059 decreased EPEC internalization, suggesting that modulation of the ERK1/2 MAP pathway might account for the lowering of the number of intracellular bacteria observed in the presence of S. boulardii. Altogether, this study demonstrated that S. boulardii exerts a protective effect on epithelial cells after EPEC adhesion by modulating the signaling pathway induced by bacterial infection.
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Affiliation(s)
- D Czerucka
- Laboratoire de Gastroentérologie et Nutrition, IFR50, Faculté de Médecine, Université de Nice-Sophia Antipolis, 06107 Nice Cedex 2, France.
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73
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Guy RL, Gonias LA, Stein MA. Aggregation of host endosomes by Salmonella requires SPI2 translocation of SseFG and involves SpvR and the fms-aroE intragenic region. Mol Microbiol 2000; 37:1417-35. [PMID: 10998173 DOI: 10.1046/j.1365-2958.2000.02092.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Salmonella-induced aggregation of host endosomal compartments into tubules, termed lgp-tubules, requires sifA and ompR. Lgp-tubules result from Salmonella-directed alteration of the endocytic system and typify the unique intracellular locale where Salmonella replicate. A high-throughput method devised to screen 11 520 MudJ mutants for loss of lgp-tubule formation identified one auxotrophic and nine prototrophic mutants. Molecular characterization identified four new loci required to alter epithelial endocytic structure. Salmonella pathogenicity island 2 (SPI2) is the locus central to the phenotype. A subset of SPI2 effectors is essential: SpiC and SseFG are required, but not SseE. A subset of apparatus proteins is also implicated: SsaJ, L, M, V and P are required. SPI2 was implicated further, as SifA shows similarity with known SPI2 translocation targets, and OmpR regulates SPI2. Another locus lies within the smf-aroE intragenic region. Lgp-tubule formation also involves a locus on the virulence plasmid pSLT. The pSLT-encoded SpvR negatively regulates an unknown repressor of the phenotype located on pSLT. Finally, disruption of carB leads to multiple auxotrophy that prevents lgp-tubule formation. This study demonstrates that lgp-tubule formation is a virulence mechanism that underlies the selective disruption of host endocytic trafficking and is associated with the formation of a replication-permissive locale.
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Affiliation(s)
- R L Guy
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405-0068, USA
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74
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Süssmuth SD, Muscholl-Silberhorn A, Wirth R, Susa M, Marre R, Rozdzinski E. Aggregation substance promotes adherence, phagocytosis, and intracellular survival of Enterococcus faecalis within human macrophages and suppresses respiratory burst. Infect Immun 2000; 68:4900-6. [PMID: 10948103 PMCID: PMC101694 DOI: 10.1128/iai.68.9.4900-4906.2000] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The aggregation substance (AS) of Enterococcus faecalis, encoded on sex pheromone plasmids, is a surface-bound glycoprotein that mediates aggregation between bacteria thereby facilitating plasmid transfer. Sequencing of the pAD1-encoded Asa1 revealed that this surface protein contains two RGD motifs which are known to ligate integrins. Therefore, we investigated the influence of AS on the interaction of E. faecalis with human monocyte-derived macrophages which constitutively express beta(2) integrins (e.g., CD18). AS was found to cause a greater-than-fivefold increase in enterococcal adherence to macrophages and a greater-than-sevenfold increase in phagocytosis. Adherence was mediated by an interaction between the RGD motif and the integrin CD11b/CD18 (complement receptor type 3) as demonstrated by inhibition studies with monoclonal antibodies and RGD peptide. AS-bearing enterococci were significantly more resistant to macrophage killing during the first 3 h postinfection, probably due to inhibition of the respiratory burst as indicated by reduced concentrations of superoxide anion.
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Affiliation(s)
- S D Süssmuth
- Department of Medical Microbiology and Hygiene, University of Ulm, D-89081 Ulm, Germany
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75
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Abstract
The ability of the widespread avian pathogen Mycoplasma gallisepticum to invade cultured human epithelial cells (HeLa-229) and chicken embryo fibroblasts (CEF) was investigated by using the gentamicin invasion assay and a double immunofluorescence microscopic technique for accurate localization of cell-associated mycoplasmas. The presence of intracellular mycoplasmas in both cell lines was clearly demonstrated, with organisms entering the eukaryotic cells within 20 min. Internalized mycoplasmas have the ability to leave the cell, but also to survive within the intracellular space over a 48-h period. Frequencies of invasion were shown to differ between the two cell lines, but were also considerably dependent on the mycoplasma input population. Of the prototype strain R, a low-passage population in artificial medium, R(low), was capable of active cell invasion, while a high-passage population, R(high), showed adherence to but nearly no uptake into HeLa-229 and CEF. By passaging R(low) and R(high) multiple times through HeLa-229 cells, the invasion frequency was significantly increased. Taken together, these findings demonstrate that M. gallisepticum has the capability of entering nonphagocytic host cells that may provide this pathogen with the opportunity for resisting host defenses and selective antibiotic therapy, establishing chronic infections, and passing through the respiratory mucosal barrier to cause systemic infections.
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Affiliation(s)
- F Winner
- Institute of Bacteriology, Mycology and Hygiene, University of Veterinary Medicine Vienna, A-1210 Vienna, Austria
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76
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Dersch P, Isberg RR. An immunoglobulin superfamily-like domain unique to the Yersinia pseudotuberculosis invasin protein is required for stimulation of bacterial uptake via integrin receptors. Infect Immun 2000; 68:2930-8. [PMID: 10768991 PMCID: PMC97506 DOI: 10.1128/iai.68.5.2930-2938.2000] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The binding of the Yersinia pseudotuberculosis and Yersinia enterocolitica invasin proteins to beta(1) integrin receptors allows internalization of these organisms by cultured cells. The C-terminal 192-residue superdomain of the Y. pseudotuberculosis invasin is necessary and sufficient for integrin recognition, while a region located outside, and N-terminal to, this superdomain strongly enhances the efficiency of bacterial uptake. Within the enhancer region is a domain called D2 that allows invasin-invasin interaction. To investigate the role of the enhancer region, bacterial cell binding and entry mediated by the Y. pseudotuberculosis invasin protein (invasin(pstb)) was compared to that of Y. enterocolitica invasin (invasin(ent)), which lacks the D2 self-association domain. Invasin(ent) was shown to be unable to promote self-interaction, using the DNA binding domain of lambda repressor as a reporter. Furthermore, two genetically engineered in-frame deletion mutations that removed D2 from invasin(pstb) were significantly less proficient than wild-type invasin(pstb) at promoting uptake, although the amount of surface-exposed invasin as well as the cell binding capacity of the recombinant Escherichia coli strains remained similar. Competitive uptake assays showed that E. coli cells expressing invasin(pstb) had a significant advantage in the internalization process versus either E. coli cells expressing invasin(ent) or the invasin(pstb) derivatives deleted for D2, further demonstrating the importance of invasin self-interaction for the efficiency of invasin-mediated uptake.
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Affiliation(s)
- P Dersch
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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77
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Ling SHM, Wang XH, Xie L, Lim TM, Leung KY. Use of green fluorescent protein (GFP) to study the invasion pathways of Edwardsiella tarda in in vivo and in vitro fish models. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 1):7-19. [PMID: 10658647 DOI: 10.1099/00221287-146-1-7] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Edwardsiella tarda is a fish pathogen that causes systemic infections in many food and ornamental fish. E. tarda PPD130/91 and PPD125/87 were selected as representatives of the virulent and avirulent groups, respectively, from eight fish isolates, and transformed with plasmids encoding either green fluorescent protein (pGFPuv) or blue fluorescent protein (pBFP2). Two host models were used to study the invasion pathway of E. tarda in vitro and in vivo. Epithelioma papillosum of carp (EPC) was used as the first model. Virulent and avirulent E. tarda strains were found to adhere to and invade EPC cells. Interactions between E. tarda and host cells examined under confocal microscopy and intracellular growth were followed at different time points. Bacterial internalization of PPD130/91 and PPD125/87 involved microfilaments and protein tyrosine kinase since cytochalasin D (an inhibitor of microfilament polymerization) and genistein (an inhibitor of protein tyrosine kinase) prevented internalization. Confocal studies revealed co-localization of polymerized actin with bacteria. Staurosporine, a protein kinase C inhibitor, accelerated internalization of PPD125/87, whereas PD098059, a mitogen-activated protein kinase (MAPK) kinase inhibitor prevented internalization of PPD130/91. In the second model, blue gourami were infected with E. tarda intramuscularly. Mortalities were observed in PPD130/91(pGFPuv)-infected fish with high bacterial numbers detectable in all organs. PPD125/87(pBFP2)-infected fish did not die and the bacterial population decreased over time. Mixed infections comprised of both PPD130/91(pGFPuv) and PPD125/87(pBFP2), where inoculum size was similar to the single infections, caused mortalities in fish. High bacterial populations were noted only in the fish body muscle. The PPD125/87(pBFP2) population in the fish decreased after 5 d. The number of PPD130/91(pGFPuv) also decreased in the fish organs, except for continued high growth in the body muscle. Histology revealed necrosis of the tissue (body muscle and liver) and fluorescent bacteria in fish that were infected with PPD130/91(pGFPuv) but not with PPD125/87(pBFP2). This study showed that fluorescent proteins are a useful tool for investigating bacterial host cell infection, and information elucidated here sheds new light on the interactions between E. tarda and its hosts.
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Affiliation(s)
- S H M Ling
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore 1192601
| | - X H Wang
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore 1192601
| | - L Xie
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore 1192601
| | - T M Lim
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore 1192601
| | - K Y Leung
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore 1192601
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78
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Cirillo JD, Cirillo SL, Yan L, Bermudez LE, Falkow S, Tompkins LS. Intracellular growth in Acanthamoeba castellanii affects monocyte entry mechanisms and enhances virulence of Legionella pneumophila. Infect Immun 1999; 67:4427-34. [PMID: 10456883 PMCID: PMC96761 DOI: 10.1128/iai.67.9.4427-4434.1999] [Citation(s) in RCA: 181] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Since Legionella pneumophila is an intracellular pathogen, entry into and replication within host cells are thought to be critical to its ability to cause disease. L. pneumophila grown in one of its environmental hosts, Acanthamoeba castellanii, is phenotypically different from L. pneumophila grown on standard laboratory medium (BCYE agar). Although amoeba-grown L. pneumophila displays enhanced entry into monocytes compared to BCYE-grown bacteria, the mechanisms of entry used and the effects on virulence have not been examined. To explore whether amoeba-grown L. pneumophila differs from BCYE-grown L. pneumophila in these characteristics, we examined entry into monocytes, replication in activated macrophages, and virulence in mice. Entry of amoeba-grown L. pneumophila into monocytes occurred more frequently by coiling phagocytosis, was less affected by complement opsonization, and was less sensitive to microtubule and microfilament inhibitors than was entry of BCYE-grown bacteria. In addition, amoeba-grown L. pneumophila displays increased replication in monocytes and is more virulent in A/J, C57BL/6 Beige, and C57BL/6 mice. These data demonstrate for the first time that the intra-amoebal growth environment affects the entry mechanisms and virulence of L. pneumophila.
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Affiliation(s)
- J D Cirillo
- Department of Veterinary and Biomedical Sciences, University of Nebraska, Lincoln, Lincoln, Nebraska 68583, USA.
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79
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Boudeau J, Glasser AL, Masseret E, Joly B, Darfeuille-Michaud A. Invasive ability of an Escherichia coli strain isolated from the ileal mucosa of a patient with Crohn's disease. Infect Immun 1999; 67:4499-509. [PMID: 10456892 PMCID: PMC96770 DOI: 10.1128/iai.67.9.4499-4509.1999] [Citation(s) in RCA: 342] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Crohn's disease (CD) is an inflammatory bowel disease in which Escherichia coli strains have been suspected of being involved. We demonstrated previously that ileal lesions of CD are colonized by E. coli strains able to adhere to intestinal Caco-2 cells but devoid of the virulence genes so far described in the pathogenic E. coli strains involved in gastrointestinal infections. In the present study we compared the invasive ability of one of these strains isolated from an ileal biopsy of a patient with CD, strain LF82, with that of reference enteroinvasive (EIEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enteraggregative (EAggEC), enterohemorrhagic (EHEC), and diffusely adhering (DAEC) E. coli strains. Gentamicin protection assays showed that E. coli LF82 was able to efficiently invade HEp-2 cells. Its invasive level was not significantly different from that of EIEC and EPEC strains (P > 0.5) but significantly higher than that of ETEC (P < 0.03), EHEC (P < 0. 005), EAggEC (P < 0.004) and DAEC (P < 0.02) strains. Strain LF82 also demonstrated efficient ability to invade intestinal epithelial cultured Caco-2, Intestine-407, and HCT-8 cells. Electron microscopy examination of infected HEp-2 cells revealed the presence of numerous intracellular bacteria located in vacuoles or free in the host cell cytoplasm. In addition, the interaction of strain LF82 with epithelial cells was associated with the elongation of microvillar extensions that extruded from the host cell membranes and engulfed the bacteria. This internalization mechanism strongly resembles Salmonella- or Shigella-induced macropinocytosis. The use of cytochalasin D and colchicine showed that the uptake of strain LF82 by HEp-2 cells was mediated by both an actin microfilament-dependent mechanism and microtubule involvement. In addition, strain LF82 survived for at least 24 h in HEp-2 and Intestine-407 cells and efficiently replicated intracellularly in HEp-2 cells. PCR and hybridization experiments did not reveal the presence of any of the genetic determinants encoding EIEC, EPEC, or ETEC proteins involved in bacterial invasion. Thus, these findings show that LF82, which colonized the ileal mucosa of a patient with CD, is a true invasive E. coli strain and suggest the existence of a new potentially pathogenic group of E. coli, which we propose be designated adherent-invasive E. coli.
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Affiliation(s)
- J Boudeau
- Pathogénie Bactérienne Intestinale, Laboratoire de Bactériologie, Faculté de Pharmacie, 63001 Clermont-Ferrand, France
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80
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Hu L, Kopecko DJ. Campylobacter jejuni 81-176 associates with microtubules and dynein during invasion of human intestinal cells. Infect Immun 1999; 67:4171-82. [PMID: 10417189 PMCID: PMC96722 DOI: 10.1128/iai.67.8.4171-4182.1999] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/1999] [Accepted: 05/04/1999] [Indexed: 11/20/2022] Open
Abstract
Campylobacter jejuni uptake into cultured INT407 cells was analyzed kinetically over a wide range of starting multiplicities of infection (MOI; from 0.02 to 20,000 bacteria/epithelial cell). The efficiency of internalization was the highest at MOI of 0.02 and decreased steadily at higher MOIs, presumably due to reported C. jejuni autoagglutination at higher densities. Total internalized Campylobacter CFU increased gradually from an MOI of 0.02 to a peak at an MOI of 200 (reaching an average of two bacteria internalized per epithelial cell) and decreased at higher MOIs. The invasion process was apparently saturated within 2 h at an MOI of 200, indicating stringent host cell limitations on this entry process. Furthermore, whereas control Salmonella typhi invaded all monolayer cells within 1 h, only two-thirds of monolayer cells were infected after 2 h with C. jejuni at MOIs of 200 to 2,000. The percentage of Campylobacter-infected host cells gradually increased to 85% after 7 h of infection, suggesting that C. jejuni entry may be host cell cycle dependent. Direct evidence of the involvement of microtubules in C. jejuni internalization, suggested previously by biochemical inhibitor studies, was obtained by time course immunofluorescence microscopic analyses. Bacteria initially bound to the tips of host cell membrane extensions containing microtubules, then aligned in parallel with microtubules during entry, colocalized specifically with microtubules and dynein but not with microfilaments, and moved over 4 h, presumably via microtubules to the perinuclear region of host cells. Orthovanadate, which inhibits dynein activity, specifically reduced C. jejuni 81-176 entry, suggesting that this molecular motor is involved in entry and endosome trafficking during this novel bacterial internalization process. Collectively, these data suggest that C. jejuni enters host cells in a targeted and tightly controlled process leading to uptake into an endosomal vacuole which apparently moves intracellularly along microtubules via the molecular motor, dynein, to the perinuclear region.
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Affiliation(s)
- L Hu
- Laboratory of Enteric and Sexually Transmitted Diseases, Center for Biologics Evaluation and Research, Food and Drug Administration. Bethesda, Maryland 20892, USA
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81
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Fives-Taylor PM, Meyer DH, Mintz KP, Brissette C. Virulence factors of Actinobacillus actinomycetemcomitans. Periodontol 2000 1999; 20:136-67. [PMID: 10522226 DOI: 10.1111/j.1600-0757.1999.tb00161.x] [Citation(s) in RCA: 214] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A. actinomycetemcomitans has clearly adapted well to its environs; its armamentarium of virulence factors (Table 2) ensures its survival in the oral cavity and enables it to promote disease. Factors that promote A. actinomycetemcomitans colonization and persistence in the oral cavity include adhesins, bacteriocins, invasins and antibiotic resistance. It can interact with and adhere to all components of the oral cavity (the tooth surface, other oral bacteria, epithelial cells or the extracellular matrix). The adherence is mediated by a number of distinct adhesins that are elements of the cell surface (outer membrane proteins, vesicles, fimbriae or amorphous material). A. actinomycetemcomitans enhances its chance of colonization by producing actinobacillin, an antibiotic that is active against both streptococci and Actinomyces, primary colonizers of the tooth surface. The fact that A. actinomycetemcomitans resistance to tetracyclines, a drug often used in the treatment of periodontal disease, is on the rise is an added weapon. Periodontal pathogens or their pathogenic products must be able to pass through the epithelial cell barrier in order to reach and cause destruction to underlying tissues (the gingiva, cementum, periodontal ligament and alveolar bone). A. actinomycetemcomitans is able to elicit its own uptake into epithelial cells and its spread to adjacent cells by usurping normal epithelial cell function. A. actinomycetemcomitans may utilize these remarkable mechanisms for host cell infection and migration to deeper tissues. A. actinomycetemcomitans also orchestrates its own survival by elaborating factors that interfere with the host's defense system (such as factors that kill phagocytes and impair lymphocyte activity, inhibit phagocytosis and phagocyte chemotaxis or interfere with antibody production). Once the organisms are firmly established in the gingiva, the host responds to the bacterial onslaught, especially to the bacterial lipopolysaccharide, by a marked and continual inflammatory response, which results in the destruction of the periodontal tissues. A. actinomycetemcomitans has at least three individual factors that cause bone resorption (lipopolysaccharide, proteolysis-sensitive factor and GroEL), as well as a number of activities (collagenase, fibroblast cytotoxin, etc.) that elicit detrimental effects on connective tissue and the extracellular matrix. It is of considerable interest to know that A. actinomycetemcomitans possesses so many virulence factors but unfortunate that only a few have been extensively studied. If we hope to understand and eradicate this pathogen, it is critical that in-depth investigations into the biochemistry, genetic expression, regulation and mechanisms of action of these factors be initiated.
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Affiliation(s)
- P M Fives-Taylor
- Department of Microbiology & Molecular Genetics, University of Vermont, Burlington, USA
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82
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Spiik AK, Meijer LK, Ridderstad A, Pettersson S. Interference of eukaryotic signalling pathways by the bacteria Yersinia outer protein YopJ. Immunol Lett 1999; 68:199-203. [PMID: 10424421 DOI: 10.1016/s0165-2478(99)00072-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Upon contact with bacteria, eukaryotic cells activates a slurry of defence mechanisms via distinct signalling transduction pathways. However, some bacteria have evolved strategies to escape or inhibit these host defence systems. We have recently shown that the bacteria Yersinia pseudotuberculosis, which encodes the Yersinia outer protein (YopJ) appears to inhibit the activation of NF-kappaB by preventing the phosphorylation of IkappaB. In a subsequent series of experiments it has also been shown that YopJ blocks the phosphorylation of the p38 MAP kinase. Here the regulatory function of YopJ on eukaryotic signal transduction is discussed.
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Affiliation(s)
- A K Spiik
- Center for Genomics Research, Karolinska Institute, Stockholm, Sweden.
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83
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Shaw MK. Theileria parva: sporozoite entry into bovine lymphocytes is not dependent on the parasite cytoskeleton. Exp Parasitol 1999; 92:24-31. [PMID: 10329362 DOI: 10.1006/expr.1998.4393] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The main conclusion from the present study is that T. parva sporozoite entry is dependent on a functional host cell actin cytoskeleton and is not driven by the parasite. Treating lymphocytes with cytochalasin D resulted in a dose-dependent reduction in the levels of host cell infection. However, the primary effect was to block sporozoite binding and only at the highest concentration (20 microM) was sporozoite internalization significantly reduced. In fact at lower concentrations (1-10 microM) cytochalasin treatment lead to a relative increase in sporozoite internalization. The results are consistent with sporozoite entry being primarily a passive process and with a functional host cell actin cytoskeleton that is required only to maintain the molecular integrity of the surface membrane. Thus T. parva sporozoite entry differs from the process in other apicomplexans, although the results are consistent with a number of features of sporozoite biology. Treatment of lymphocytes with either the microtubule-destabilizing agent, nocodazole, or taxol, which induces microtubule polymerization, had no significant effect on sporozoite binding or entry. As both reagents had the expected effects on the lymphocyte microtubule system, it is unlikely that host cell microtubules are essential for successful sporozoite invasion or establishment.
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84
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Denney CF, Eckmann L, Reed SL. Chemokine secretion of human cells in response to Toxoplasma gondii infection. Infect Immun 1999; 67:1547-52. [PMID: 10084985 PMCID: PMC96495 DOI: 10.1128/iai.67.4.1547-1552.1999] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The ubiquitous protozoan parasite Toxoplasma gondii is a major cause of morbidity and mortality in neonates and immunocompromised hosts. Both acute invasion and reactivation of latent infection result in an inflammatory reaction with lymphocytes, macrophages, and neutrophils. The mechanisms responsible for triggering the local host response to toxoplasmosis are not fully understood. Infection of monolayers of human HeLa epithelial cells and fibroblasts with T. gondii resulted in a marked increase in the expression of interleukin-8 (IL-8)-specific mRNA and secretion of the proinflammatory and chemoattractant cytokines interleukin-8 (IL-8), GROalpha, and MCP-1. Host cell invasion and lysis were required for this response, as tachyzoite lysates alone had no effect on IL-8 secretion. IL-8 release was dependent on the release of soluble host cell factors: IL-1alpha in HeLa cells and an additional mediator in fibroblasts. HT-29 epithelial cells, which lack IL-1alpha or another IL-8-inducing activity, did not release IL-8 after infection, although they were efficiently infected with T. gondii and increased IL-8 secretion in response to added IL-1alpha. These data suggest that proinflammatory chemokine secretion is an important host cell response to toxoplasmosis and that the release of IL-1alpha and other mediators from lysed host cells is critical for this chemokine response.
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Affiliation(s)
- C F Denney
- Departments of Medicine, University of California, San Diego, San Diego, California 92103-8416, USA
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85
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Abstract
Many pathogens actively exploit the actin cytoskeleton during infection. This exploitation may take place during entry into mammalian cells after engagement of a receptor and/or as series of signaling events culminating in the engulfment of the microorganism. Although actin rearrangements are a common feature of most internalization events (e.g. entry of Listeria, Salmonella, Shigella, Yersinia, Neisseria, and Bartonella), bacterial and other cellular factors involved in entry are specific to each bacterium. Another step during which pathogens harness the actin cytoskeleton takes place in the cytosol, within which some bacteria (Listeria, Shigella, Rickettsia) or viruses (vaccinia virus) are able to move. Movement is coupled to a polarized actin polymerization process, with the formation of characteristic actin tails. Increasing attention has focused on this phenomenon due to its striking similarity to cellular events occurring at the leading edge of locomoting cells. Thus pathogens are convenient systems in which to study actin cytoskeleton rearrangements in response to stimuli at the plasma membrane or inside cells.
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Affiliation(s)
- S Dramsi
- Unité des Interactions Bactéries-Cellules, Institut Pasteur, Paris, France
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86
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Wang XH, Oon HL, Ho GWP, Wong WSF, Lim TM, Leung KY. Internalization and cytotoxicity are important virulence mechanisms in Vibrio-fish epithelial cell interactions. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 11):2987-3002. [PMID: 9846734 DOI: 10.1099/00221287-144-11-2987] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Vibrio anguillarum and Vibrio damselae are Gram-negative bacteria that cause systemic infections called vibriosis in fish. They can enter fish cells and survive as intracellular parasites. The host-pathogen interactions between these Vibrio species and the fish epithelial cell lines epithelioma papillosum of carp (EPC) and grunt-fin tissue (GF) cells, were examined using phase-contrast, scanning electron and confocal microscopy. In addition, potential signal transduction pathways that precede bacterial internalization were studied by using signal transduction inhibitors. Some Vibrio species induced morphological changes in fish cells and this allowed classification into a cytopathic group and a noncytopathic group. The cytopathic group could be subdivided into two invasive groups (I and II) and a cytotoxic group. Of the invasive strains V. anguillarum 811218-5W (group I) and G/Virus/5(3) (group II), genistein, a tyrosine kinase inhibitor, only inhibited internalization of V. anguillarum G/Virus/5(3) into EPC cells, whereas staurosporine, a protein kinase C inhibitor, accelerated internalization of both strains. Cytochalasin D, an inhibitor of microfilament polymerization, prevented internalization of both strains, whilst vincristin, a microtubule inhibitor, only inhibited internalization of V. anguillarum G/Virus/5(3). For the cytotoxic strain V. damselae ATCC 33539, extracellular products (ECP) alone caused morphological changes in EPC and GF. Bacterial internalization may not be important in the pathogenesis of this group. The non-cytopathic strain V. anguillarum S2/5/93(2) did not enter cells or induce any changes in EPC and GF monolayers. This study has identified some major differences between Vibrio species in their interactions with fish cells in vitro and will thus facilitate future studies of the molecular basis of pathogenesis of vibriosis.
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Affiliation(s)
- X H Wang
- Department of Biological SciencesFaculty of Science University of Singapore,10 Kent Ridge Crescent Singapore 119260
| | - H L Oon
- Department of Biological SciencesFaculty of Science University of Singapore,10 Kent Ridge Crescent Singapore 119260
| | - G W P Ho
- Department of Biological SciencesFaculty of Science University of Singapore,10 Kent Ridge Crescent Singapore 119260
| | - W S F Wong
- Department of PharmacologyFaculty of MedicinezNational University of Singapore10 Kent Ridge Crescent Singapore 119260
| | - T M Lim
- Department of Biological SciencesFaculty of Science University of Singapore,10 Kent Ridge Crescent Singapore 119260
| | - K Y Leung
- Department of Biological SciencesFaculty of Science University of Singapore,10 Kent Ridge Crescent Singapore 119260
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87
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Lutwyche P, Cordeiro C, Wiseman DJ, St-Louis M, Uh M, Hope MJ, Webb MS, Finlay BB. Intracellular delivery and antibacterial activity of gentamicin encapsulated in pH-sensitive liposomes. Antimicrob Agents Chemother 1998; 42:2511-20. [PMID: 9756749 PMCID: PMC105873 DOI: 10.1128/aac.42.10.2511] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cell membranes are relatively impermeable to the antibiotic gentamicin, a factor that, along with the toxicity of gentamicin, precludes its use against many important intracellular bacterial infections. Liposomal encapsulation of this drug was used in order to achieve intracellular antibiotic delivery and therefore increase the drug's therapeutic activity against intracellular pathogens. Gentamicin encapsulation in several dipalmitoylphosphatidylcholine (DPPC) and pH-sensitive dioleoylphosphatidylethanolamine (DOPE)-based carrier systems was characterized. To systematically test the antibacterial efficacies of these formulations, a tissue culture assay system was developed wherein murine macrophage-like J774A.1 cells were infected with bacteria and were then treated with encapsulated drug. Of these formulations, DOPE-N-succinyl-DOPE and DOPE-N-glutaryl-DOPE (70:30;mol:mol) containing small amounts of polyethyleneglycol-ceramide showed appreciable antibacterial activities, killing greater than 75% of intracellular vacuole-resident wild-type Salmonella typhimurium compared to the level of killing of the control formulations. These formulations also efficiently eliminated intracellular infections caused by a recombinant hemolysin-expressing S. typhimurium strain and a Listeria monocytogenes strain, both of which escape the vacuole and reside in the cytoplasm. Control non-pH-sensitive liposomal formulations of gentamicin had poor antibacterial activities. A fluorescence resonance energy transfer assay indicated that the efficacious formulations undergo a pH-dependent lipid mixing and fusion event. Intracellular delivery of the fluorescent molecules encapsulated in these formulations was confirmed by confocal fluorescence microscopy and was shown to be dependent on endosomal acidification. This work shows that encapsulation of membrane-impermeative antibiotics in appropriately designed lipid-based delivery systems can enable their use in treating intracellular infections and details the development of a general assay for testing the intracellular delivery of encapsulated drug formulations.
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Affiliation(s)
- P Lutwyche
- Inex Pharmaceuticals Corporation, Burnaby, British Columbia, Canada V5J 5J8
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88
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Francis MS, Wolf-Watz H. YopD of Yersinia pseudotuberculosis is translocated into the cytosol of HeLa epithelial cells: evidence of a structural domain necessary for translocation. Mol Microbiol 1998; 29:799-813. [PMID: 9723919 DOI: 10.1046/j.1365-2958.1998.00973.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Yersinia pseudotuberculosis YopB and YopD proteins are essential for translocation of Yop effector proteins into the target cell cytosol. YopB is suggested to mediate pore formation in the target cell plasma membrane, allowing translocation of Yop effector proteins, although the function of YopD is unclear. To investigate the role in translocation for YopD, a mutant strain in Y. pseudotuberculosis was constructed containing an in frame deletion of essentially the entire yopD gene. As shown recently for the Y. pestis YopD protein, we found that the in vitro low calcium response controlling virulence gene expression was negatively regulated by YopD. This yopD null mutant (YPIII/pIB621) was also non-cytotoxic towards HeLa cell monolayers, supporting the role for YopD in the translocation process. Although other constituents of the Yersinia translocase apparatus (YopB, YopK and YopN) are not translocated into the host cell cytosol, fractionation of infected HeLa cells allowed us to identify the cytosolic localization of YopD by the wild-type strain (YPIII/pIB102), but not by strains defective in either YopD or YopB. YopD was also identified by immunofluorescence in the cytoplasm of HeLa cell monolayers infected with a multiple yop mutant strain (YPIII/pIB29MEKA). These results demonstrate a dual function for YopD in negative regulation of Yop production and Yop effector translocation, including the YopD protein itself. To investigate whether an amphipathic domain near the C-terminus of YopD is involved in the translocation process, a mutant strain (YPIII/pIB155deltaD278-292) was constructed that is devoid of this region. Phenotypically, this small in frame deltayopD278-292 deletion mutant was indistinguishable from the yopD null mutant. The truncated YopD protein and Yop effectors were not translocated into the cytosol of HeLa cell monolayers infected with this mutant. The comparable regulatory and translocation phenotypes displayed by the small in frame deltayopD278-292 deletion and deltayopD null mutants suggest that regulation of Yop synthesis and Yop translocation are intimately coupled. We present an intriguing scenario to the Yersinia infection process that highlights the need for polarized translocation of YopD to specifically establish translocation of Yop effectors. These observations are contrary to previous suggestions that members of the translocase apparatus were not translocated into the host cell cytosol.
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Affiliation(s)
- M S Francis
- Department of Cell and Molecular Biology, Umeå University, Sweden
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89
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Smith RL, Kaczmarek MT, Kucharski LM, Maguire ME. Magnesium transport in Salmonella typhimurium: regulation of mgtA and mgtCB during invasion of epithelial and macrophage cells. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 7):1835-1843. [PMID: 9695916 DOI: 10.1099/00221287-144-7-1835] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Salmonella typhimurium contains two inducible Mg2+ transport systems, MgtA and MgtB, the latter encoded by a two-gene operon, mgtCB. Mg2+ deprivation of S. typhimurium increases transcription of both mgtA and mgtCB over a thousandfold and a similar increase occurs upon S. typhimurium invasion of epithelial cells. These increases are mediated by the phoPQ two-component signal transduction system, an essential system for S. typhimurium virulence. It was therefore hypothesized that expression of MgtA and MgtCB is increased upon invasion of eukaryotic cells because of a lack of intravacuolar Mg2+. However, when S. typhimurium was grown at pH 5.2, the capacity of the constitutive CorA transporter in mediating Mg2+ was greater than that at pH 7.4. Furthermore, induction of mgtA and mgtCB transcription was greater in the presence of a wild-type corA allele than in its absence. This implies that intravacuolar S. typhimurium could obtain sufficient Mg2+ via the CorA system. The effect of acid pH on mgtA and mgtCB transcription was also measured. Compared to induction at pH 7.4, exposure to pH 5.2 almost completely abolished induction of mgtA at low Mg2+ concentrations but diminished induction of mgtCB only twofold. Adaptation of cells to acid pH by overnight growth resulted in normal levels of induction of mgtA and mgtCB at low Mg2+ concentrations. These results imply an additional level of regulation for mgtA that is not present for mgtCB. Conversely, repression of mgtA and mgtCB expression by increased extracellular Mg2+ was relatively insensitive to acid. Transcription of both loci was strongly induced upon invasion of the Hep-2 or CMT-93 epithelial-like or J774 macrophage-like cell lines. However, the presence or absence of functional alleles of either or both mgtA or mgtCB had no effect on invasion efficiency or short-term survival of S. typhimurium within the eukaryotic cells. It was concluded that the strong Mg(2+)-dependent induction of mgtA and mgtCB upon invasion of eukaryotic cells is not required because S. typhimurium lacks sufficient Mg2+ during eukaryotic cell invasion and initial intravacuolar growth.
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90
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Wells CL, van de Westerlo EM, Jechorek RP, Haines HM, Erlandsen SL. Cytochalasin-induced actin disruption of polarized enterocytes can augment internalization of bacteria. Infect Immun 1998; 66:2410-9. [PMID: 9596696 PMCID: PMC108218 DOI: 10.1128/iai.66.6.2410-2419.1998] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Cytochalasin-induced actin disruption has often been associated with decreased bacterial internalization by cultured epithelial cells, although polarized enterocytes have not been systematically studied. In assays using confluent polarized HT-29 enterocytes, cytochalasin D appeared to increase internalization of wild-type Salmonella typhimurium, Proteus mirabilis, and Escherichia coli. HeLa and HEp-2 epithelial cells, as well as HT-29 and Caco-2 enterocytes, were used to clarify this unexpected observation. Resulting data showed that cytochalasin D was associated with increased internalization of S. typhimurium and P. mirabilis by both HT-29 and Caco-2 enterocytes and with increased internalization of E. coli by HT-29 enterocytes; with either HeLa or HEp-2 cells, cytochalasin was associated with no change or a decrease in internalization of these same bacterial strains. Cytochalasin caused decreased internalization of Listeria monocytogenes by HT-29, Caco-2, HeLa, and HEp-2 cells, indicating that cytochalasin did not consistently augment bacterial internalization by polarized enterocytes. Fluorescein-labeled phalloidin confirmed marked disruption of filamentous actin in cytochalasin-treated HT-29, Caco-2, HeLa, and HEp-2 cells. Cytochalasin had no noticeable effect on epithelial viability but caused distorted apical microvilli, cell rounding, and separation of adjacent enterocytes in confluent cultures (with a corresponding decrease in transepithelial electrical resistance). Scanning electron microscopy showed that cytochalasin-induced enhanced bacterial internalization was associated with preferential bacterial adherence on the exposed enterocyte lateral surface. Colchicine, used to disrupt microtubules, had no noticeable effect on bacterial internalization by HT-29 or Caco-2 enterocytes. These data indicated that for HT-29 and Caco-2 enterocytes, cytochalasin-induced disruption of filamentous actin might augment internalization of some bacterial species by a mechanism that appeared to involve exposure of the enterocyte lateral surface.
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Affiliation(s)
- C L Wells
- Department of Laboratory Medicine, University of Minnesota, Minneapolis, Minnesota 55455-0385, USA.
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91
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Mecsas J, Raupach B, Falkow S. The Yersinia Yops inhibit invasion of Listeria, Shigella and Edwardsiella but not Salmonella into epithelial cells. Mol Microbiol 1998; 28:1269-81. [PMID: 9680215 DOI: 10.1046/j.1365-2958.1998.00891.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Yersinia virulence is dependent on the expression of plasmid-encoded secreted proteins called Yops. After bacterial adherence to receptors on the mammalian cell membrane, several Yops are transported by a type III secretion pathway into the host cell cytoplasm. Two Yops, YopH and YopE, prevent macrophages from phagocytosing Yersinia by disrupting the host cell cytoskeleton and signal transduction pathways. In contrast to this active inhibition of phagocytosis by Yersinia, other pathogens such as Salmonella, Shigella, Listeria and Edwardsiella actively promote their entry into mammalian cells by binding to specific host surface receptors and exploiting existing cell cytoskeletal and signalling pathways. We have tested whether Yersinia Yops can prevent the uptake of these diverse invasive pathogens. We first infected epithelial cells with Yersinia to permit delivery of Yops and subsequently with an invasive pathogen. We then measured the level of bacterial invasion. Preinfection with Yersinia inhibited invasion of Edwardsiella, Shigella and Listeria, but not Salmonella. Furthermore, we found that either YopE or YopH prevented Listeria invasion, whereas only YopE prevented Edwardsiella and Shigella invasion. We correlated the inhibitory effect of the Yops with the inhibitory action of the cell-signalling inhibitors Wortmannin, LY294002 and NDGA, and concluded that the four invasive pathogenic species enter epithelial cells using at least three distinct host cell pathways. We also speculate that YopE affects the rho pathway.
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Affiliation(s)
- J Mecsas
- Stanford University School of Medicine, CA 94305-5124, USA.
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92
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Schesser K, Spiik AK, Dukuzumuremyi JM, Neurath MF, Pettersson S, Wolf-Watz H. The yopJ locus is required for Yersinia-mediated inhibition of NF-kappaB activation and cytokine expression: YopJ contains a eukaryotic SH2-like domain that is essential for its repressive activity. Mol Microbiol 1998; 28:1067-79. [PMID: 9680199 DOI: 10.1046/j.1365-2958.1998.00851.x] [Citation(s) in RCA: 226] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Upon exposure to bacteria, eukaryotic cells activate signalling pathways that result in the increased expression of several defence-related genes. Here, we report that the yopJ locus of the enteropathogen Yersinia pseudotuberculosis encodes a protein that inhibits the activation of NF-kappaB transcription factors by a mechanism(s), which prevents the phosphorylation and subsequent degradation of the inhibitor protein IkappaB. Consequently, eukaryotic cells infected with YopJ-expressing Yersinia become impaired in NF-kappaB-dependent cytokine expression. In addition, the blockage of inducible cytokine production coincides with yopJ-dependent induction of apoptosis. Interestingly, the YopJ protein contains a region that resembles a src homology domain 2 (SH2), and we show that a wild-type version of this motif is required for YopJ activity in suppressing cytokine expression and inducing apoptosis. As SH2 domains are found in several eukaryotic signalling proteins, we propose that YopJ, which we show is delivered into the cytoplasm of infected cells, interacts directly with signalling proteins involved in inductive cytokine expression. The repressive activity of YopJ on the expression of inflammatory mediators may account for the lack of an inflammatory host response observed in experimental yersiniosis. YopJ-like activity may also be a common feature of commensal bacteria that, like Yersinia, do not provoke a host inflammatory response.
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Affiliation(s)
- K Schesser
- Department of Cell and Molecular Biology, Umeå University, Sweden.
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93
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Hueck CJ. Type III protein secretion systems in bacterial pathogens of animals and plants. Microbiol Mol Biol Rev 1998; 62:379-433. [PMID: 9618447 PMCID: PMC98920 DOI: 10.1128/mmbr.62.2.379-433.1998] [Citation(s) in RCA: 1723] [Impact Index Per Article: 66.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Various gram-negative animal and plant pathogens use a novel, sec-independent protein secretion system as a basic virulence mechanism. It is becoming increasingly clear that these so-called type III secretion systems inject (translocate) proteins into the cytosol of eukaryotic cells, where the translocated proteins facilitate bacterial pathogenesis by specifically interfering with host cell signal transduction and other cellular processes. Accordingly, some type III secretion systems are activated by bacterial contact with host cell surfaces. Individual type III secretion systems direct the secretion and translocation of a variety of unrelated proteins, which account for species-specific pathogenesis phenotypes. In contrast to the secreted virulence factors, most of the 15 to 20 membrane-associated proteins which constitute the type III secretion apparatus are conserved among different pathogens. Most of the inner membrane components of the type III secretion apparatus show additional homologies to flagellar biosynthetic proteins, while a conserved outer membrane factor is similar to secretins from type II and other secretion pathways. Structurally conserved chaperones which specifically bind to individual secreted proteins play an important role in type III protein secretion, apparently by preventing premature interactions of the secreted factors with other proteins. The genes encoding type III secretion systems are clustered, and various pieces of evidence suggest that these systems have been acquired by horizontal genetic transfer during evolution. Expression of type III secretion systems is coordinately regulated in response to host environmental stimuli by networks of transcription factors. This review comprises a comparison of the structure, function, regulation, and impact on host cells of the type III secretion systems in the animal pathogens Yersinia spp., Pseudomonas aeruginosa, Shigella flexneri, Salmonella typhimurium, enteropathogenic Escherichia coli, and Chlamydia spp. and the plant pathogens Pseudomonas syringae, Erwinia spp., Ralstonia solanacearum, Xanthomonas campestris, and Rhizobium spp.
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Affiliation(s)
- C J Hueck
- Lehrstuhl für Mikrobiologie, Biozentrum der Universität Würzburg, 97074 Würzburg, Germany.
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94
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Delvig AA, Robinson JH. Different endosomal proteolysis requirements for antigen processing of two T-cell epitopes of the M5 protein from viable Streptococcus pyogenes. J Biol Chem 1998; 273:3291-5. [PMID: 9452445 DOI: 10.1074/jbc.273.6.3291] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We studied endosomal proteolysis of the surface fibrillar M5 protein from viable Streptococcus pyogenes as an essential step involved in major histocompatibility complex class II-restricted antigen processing of two immunodominant CD4(+) T-cell epitopes (17-31/Ed and 308-319/Ad). Intracellular proteolysis of viable streptococci for presentation of 17-31, bound by serine proteinase cleavage sites, was mediated by serine proteinases, whereas processing of soluble recombinant M5 protein required in addition cysteine proteinases. Furthermore, processing of 17-31 was resistant to ammonium chloride and thus was not dependent on endosome acidification. Cysteine and serine proteinase cleavage sites were located adjacent to 308-319, and its processing was dependent on serine, cysteine, and aspartic proteinases, as well as on endosomal acidification. The data suggest that antigen processing of two major T-cell epitopes on streptococcal M5 protein occurred in different endosomal compartments by different classes of intracellular proteinases.
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Affiliation(s)
- A A Delvig
- Department of Immunology, School of Microbiological, Virological, and Immunological Sciences, The Medical School, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne, Tyne and Wear, NE2 4HH, United Kingdom
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95
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Low, Goh, Lim, Sin, Leung. Actin rearrangements accompanying Aeromonas hydrophila entry into cultured fish cells. JOURNAL OF FISH DISEASES 1998; 21:55-65. [PMID: 29739171 DOI: 10.1046/j.1365-2761.1998.00076.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Aeromonas hydrophila can enter fish cells and exist as intracellular parasites. Phase-contrast and confocal microscopy were used to examine morphological changes and various cytoskeletal components of infected fish cells. Four fish cell lines were included in this study: (1) AS, (2) BF2, (3) CHSE-214, and (4) EPC cells. Virulent but not avirulent strains of A. hydrophila PPD 134/91 invaded fish cells, causing morphological changes, and inducing microfilament (F-actin) rearrangement. Morphological changes were observed in all infected fish cell lines and could be classified into three different stages. In stage I, the cells became detached from each other and pointed ends were observed. In stage II, tubular cytoplasmic extensions formed at contact points connecting neighbouring cells. The monolayers formed a satellite-like organization and became less confluent. Finally (stage III), cells were heavily infected with bacteria, and bacteria containing vacuoles occupied most of the cells. They eventually detached and lysed. Rearrangement of F-actin was observed as local polymerization (actin clouds) in stage I and massive reorganization in stage III of infection. Actin clouds could have been induced by A. hydrophila for 'assisted' uptake into the cells. The massive reorganization of actin in stage III may be due to products released by the bacteria and the growth of vacuoles. Pretreatment of fish cells with the microfilament inhibitors such as cytochalasins induced a similar effect. There were little if any rearrangements in intermediate and microtubule filaments during bacterial entry (stages I and II). These results suggest that A. hydrophila may bind to the surface and trigger a signal to the microfilament which then generates the force necessary for bacterial uptake.
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Affiliation(s)
- Low
- School of Biological Sciences, Faculty of Science, National University of Singapore
| | - Goh
- School of Biological Sciences, Faculty of Science, National University of Singapore
| | - Lim
- School of Biological Sciences, Faculty of Science, National University of Singapore
| | - Sin
- School of Biological Sciences, Faculty of Science, National University of Singapore
| | - Leung
- School of Biological Sciences, Faculty of Science, National University of Singapore
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96
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Fällman M, Persson C, Schesser K, Wolf-Watz H. Bidirectional signaling between Yersinia and its target cell. Folia Microbiol (Praha) 1998; 43:263-73. [PMID: 9717253 DOI: 10.1007/bf02818611] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Preventing the early host immune defense allows pathogenic Yersinia to proliferate in lymphatic tissue. This ability depends on signaling that occurs between the bacteria and the host cells. Following intimate contact with the target cell a signal is generated within the bacterium that results in increased expression of virulence-associated proteins that are subsequently delivered into the infected cell. These proteins, designated Yops, interfere with the host-cell signaling pathways that are normally activated to eliminate infectious agents.
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Affiliation(s)
- M Fällman
- Department of Cell and Molecular Biology, Umeå University, Sweden
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97
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Wilson JA, Doyle TJ, Gulig PA. Exponential-phase expression of spvA of the Salmonella typhimurium virulence plasmid: induction in intracellular salts medium and intracellularly in mice and cultured mammalian cells. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 12):3827-3839. [PMID: 9421907 DOI: 10.1099/00221287-143-12-3827] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The spv genes of Salmonella typhimurium and other non-typhoidal Salmonella serovars are essential for efficient systemic infection beyond the intestines in orally inoculated mice as a model for enteric fever. These virulence genes are not significantly expressed by salmonellae during exponential growth in L broth but are induced when the bacteria enter the stationary phase of growth. Using RNase protection analysis to directly measure spvA mRNA from the virulence plasmid of S. typhimurium, we found that spvA was maximally induced in an SpvR- and RpoS-dependent manner during exponential growth in intracellular Salts Medium, which mimics the intracellular environment of mammalian cells. A cloned spvA-lacZ operon fusion in S. typhimurium was induced intracellularly in periotoneal cells of mice, correlating in vivo intracellular gene expression with intracellular function of the spv genes in infected mice. spvA was also induced intracellularly in vitro within both Henle-407 intestinal epithelial cells and J774.A1 macrophage-like cells when the bacteria were replicating with exponential kinetics. Prevention of invasion of salmonellae with cytochalasin D inhibited spvA induction within tissue culture cells, indicating that salmonellae must be internalized for spvA to be induced. The spvA-lacZ fusion was not induced by salmonellae in extracellular fluid of the peritoneal cavity or in serum. Since induction of the spv genes occurs intracellularly during exponential growth of salmonellae, cessation of growth may not be the most relevant inducing signal for spv gene expression.
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Affiliation(s)
| | - Thomas J Doyle
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, FL 32610-0266, USA
| | - Paul A Gulig
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, FL 32610-0266, USA
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98
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Nizet V, Kim KS, Stins M, Jonas M, Chi EY, Nguyen D, Rubens CE. Invasion of brain microvascular endothelial cells by group B streptococci. Infect Immun 1997; 65:5074-81. [PMID: 9393798 PMCID: PMC175731 DOI: 10.1128/iai.65.12.5074-5081.1997] [Citation(s) in RCA: 229] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Group B streptococci (GBS) are the leading cause of meningitis in newborns. Although meningitis develops following bacteremia, the precise mechanism or mechanisms whereby GBS leave the bloodstream and gain access to the central nervous system (CNS) are not known. We hypothesized that GBS produce meningitis because of a unique capacity to invade human brain microvascular endothelial cells (BMEC), the single-cell layer which constitutes the blood-brain barrier. In order to test this hypothesis, we developed an in vitro model with BMEC isolated from a human, immortalized by simian virus 40 transformation, and propagated in tissue culture monolayers. GBS invasion of BMEC monolayers was demonstrated by electron microscopy. Intracellular GBS were found within membrane-bound vacuoles, suggesting the organism induced its own endocytic uptake. GBS invasion of BMEC was quantified with a gentamicin protection assay. Serotype III strains, which account for the majority of CNS isolates, invaded BMEC more efficiently than strains from other common GBS serotypes. GBS survived within BMEC for up to 20 h without significant intracellular replication. GBS invasion of BMEC required active bacterial DNA, RNA, and protein synthesis, as well as microfilament and microtubule elements of the eukaryotic cytoskeleton. The polysaccharide capsule of GBS attenuated the invasive ability of the organism. At high bacterial densities, GBS invasion of BMEC was accompanied by evidence of cellular injury; this cytotoxicity was correlated to beta-hemolysin production by the bacterium. Finally, GBS demonstrated transcytosis across intact, polar BMEC monolayers grown on Transwell membranes. GBS invasion of BMEC may be a primary step in the pathogenesis of meningitis, allowing bacteria access to the CNS by transcytosis or by injury and disruption of the endothelial blood-brain barrier.
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Affiliation(s)
- V Nizet
- Division of Infectious Diseases, Children's Hospital and Medical Center, Seattle, Washington 98105, USA.
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99
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Fumagalli O, Tall BD, Schipper C, Oelschlaeger TA. N-glycosylated proteins are involved in efficient internalization of Klebsiella pneumoniae by cultured human epithelial cells. Infect Immun 1997; 65:4445-51. [PMID: 9353018 PMCID: PMC175639 DOI: 10.1128/iai.65.11.4445-4451.1997] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Klebsiella pneumoniae obtained from patients with urinary tract infections is able to invade cultured human epithelial cells. The internalization process is dependent upon both microfilaments and microtubules. To better understand the interaction of these invasive bacteria with the host cell receptor(s), bladder, lung, and ileocecal epithelial cells were infected with K. pneumoniae in the presence of various lectins possessing multiple glycan specificities. It was found that the N-acetylglucosamine (GlcNAc)-specific lectins concanavalin A, Datura stramonium agglutinin, and wheat germ agglutinin significantly inhibited the invasion of K. pneumoniae into these cells but did not interfere with the internalization of an invasive strain of Salmonella typhimurium. Conversely, internalization of K. pneumoniae but not S. typhimurium was also significantly inhibited when the bacteria were pretreated with GlcNAc or chitin hydrolysate, a GlcNAc polymer, prior to the gentamicin invasion assay. Other carbohydrates such as glucose, galactose, mannose, fucose, and N-acetylneuraminic acid had no inhibitory effects on K. pneumoniae uptake. Furthermore, internalization of K. pneumoniae but not S. typhimurium by HCT8 cells was also significantly inhibited when eukaryotic protein glycosylation was interrupted by tunicamycin or when host N-linked surface glycans were removed by pretreatment with N-glycosidase F. These studies suggest that a N-glycosylated protein receptor is involved in the internalization of K. pneumoniae by human epithelial cells in vitro. The results also indicate that internal GlcNAc residues might be a carbohydrate component of the receptor.
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Affiliation(s)
- O Fumagalli
- Institut für Molekulare Infektionsbiologie, Würzburg, Germany
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100
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Oelschlaeger TA, Tall BD. Invasion of cultured human epithelial cells by Klebsiella pneumoniae isolated from the urinary tract. Infect Immun 1997; 65:2950-8. [PMID: 9199471 PMCID: PMC175413 DOI: 10.1128/iai.65.7.2950-2958.1997] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The mechanisms which enable entry into cultured human epithelial cells by Klebsiella pneumoniae were compared with those of Salmonella typhi Ty2. K. pneumoniae 3091, isolated from a urine sample of a patient with a urinary tract infection, invaded human epithelial cells from the bladder and ileocecum and persisted for days in vitro. Electron microscopic studies demonstrated that K. pneumoniae was always contained in endosomes. The internalization mechanism(s) triggered by K. pneumoniae was studied by invasion assays conducted with different inhibitors that act on prokaryotic and eukaryotic cell structures and processes. Chloramphenicol inhibition of bacterial uptake revealed that bacterial de novo protein synthesis was essential for efficient invasion by K. pneumoniae and S. typhi. Interference with receptor-mediated endocytosis by g-strophanthin or monodansylcadaverine and inhibition of endosome acidification by monensin reduced the number of viable intracellular K. pneumoniae cells, but not S. typhi cells. The depolymerization of microfilaments by cytochalasin D inhibited the uptake of both bacteria. Microtubule depolymerization caused by colchicine, demecolcine, or nocodazole and the stabilization of microtubules with taxol reduced only the invasion ability of K. pneumoniae. S. typhi invasion was unaffected by microtubule depolymerization or stabilization. These data suggest that the internalization mechanism triggered by K. pneumoniae 3091 is strikingly different from the solely microfilament-dependent invasion mechanism exhibited by many of the well-studied enteric bacteria, such as enteroinvasive Escherichia coli, Salmonella, Shigella, and Yersinia strains.
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Affiliation(s)
- T A Oelschlaeger
- Department of Bacterial Immunology, Walter Reed Army Institute of Research, Washington, D.C. 20307, USA
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