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Zeczycki TN, Milton ME, Jung D, Thompson RJ, Jaimes FE, Hondros AD, Palethorpe S, Melander C, Cavanagh J. 2-Aminoimidazole Analogs Target PhoP Altering DNA Binding Activity and Affect Outer Membrane Stability in Gram-Negative Bacteria. Biochemistry 2022; 61:2948-2960. [DOI: 10.1021/acs.biochem.2c00560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Tonya N. Zeczycki
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Morgan E. Milton
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - David Jung
- Agile Sciences Inc., 617 Hutton Street, Raleigh, North Carolina27606, United States
| | - Richele J. Thompson
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Felicia E. Jaimes
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Alexander D. Hondros
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Samantha Palethorpe
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana46556, United States
| | - John Cavanagh
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
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Stårsta M, Hammarlöf DL, Wäneskog M, Schlegel S, Xu F, Heden Gynnå A, Borg M, Herschend S, Koskiniemi S. RHS-elements function as type II toxin-antitoxin modules that regulate intra-macrophage replication of Salmonella Typhimurium. PLoS Genet 2020; 16:e1008607. [PMID: 32053596 PMCID: PMC7043789 DOI: 10.1371/journal.pgen.1008607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 02/26/2020] [Accepted: 01/12/2020] [Indexed: 11/19/2022] Open
Abstract
RHS elements are components of conserved toxin-delivery systems, wide-spread within the bacterial kingdom and some of the most positively selected genes known. However, very little is known about how Rhs toxins affect bacterial biology. Salmonella Typhimurium contains a full-length rhs gene and an adjacent orphan rhs gene, which lacks the conserved delivery part of the Rhs protein. Here we show that, in addition to the conventional delivery, Rhs toxin-antitoxin pairs encode for functional type-II toxin-antitoxin (TA) loci that regulate S. Typhimurium proliferation within macrophages. Mutant S. Typhimurium cells lacking both Rhs toxins proliferate 2-times better within macrophages, mainly because of an increased growth rate. Thus, in addition to providing strong positive selection for the rhs loci under conditions when there is little or no toxin delivery, internal expression of the toxin-antitoxin system regulates growth in the stressful environment found inside macrophages. Bacteria that reside and multiply inside of phagocytic cells are hard to treat with common antibiotics, partly because subpopulations of bacteria are non-growing. Very little is known about how bacteria regulate their growth in the phagocytic vesicle. We show that RHS elements, previously known to function as mobilizable toxins that inhibit growth of neighboring bacteria, also function as internally expressed toxin-antitoxin systems that regulate Salmonella Typhimurium growth in macrophages. RHS elements were discovered more than 30 years ago, but their role in biology has long remained unclear even though they are some of the most positively selected genes known. Our results suggest an explanation to why rhs genes are under such strong positive selection in addition to suggesting a novel function for these toxins in regulating bacterial growth.
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Affiliation(s)
- Magnus Stårsta
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Disa L. Hammarlöf
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Marcus Wäneskog
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Susan Schlegel
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Feifei Xu
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Arvid Heden Gynnå
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Malin Borg
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Sten Herschend
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Sanna Koskiniemi
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- * E-mail:
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3
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Khan S, Fujii S, Matsunaga T, Nishimura A, Ono K, Ida T, Ahmed KA, Okamoto T, Tsutsuki H, Sawa T, Akaike T. Reactive Persulfides from Salmonella Typhimurium Downregulate Autophagy-Mediated Innate Immunity in Macrophages by Inhibiting Electrophilic Signaling. Cell Chem Biol 2018; 25:1403-1413.e4. [PMID: 30197193 DOI: 10.1016/j.chembiol.2018.08.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/29/2018] [Accepted: 08/07/2018] [Indexed: 12/17/2022]
Abstract
Reactive persulfides such as cysteine persulfide and glutathione persulfide are produced by bacteria including Salmonella during sulfur metabolism. The biological significance of bacterial reactive persulfides in host-pathogen interactions still warrants investigation. We found that reactive persulfides produced by Salmonella Typhimurium LT2 regulate macrophage autophagy via metabolizing 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP), an electrophilic product of reactive oxygen species and nitric oxide signaling. 8-Nitro-cGMP signaling was required for efficient autophagy-mediated clearance of Salmonella from infected macrophages. In the infected cells, 8-nitro-cGMP caused cGMP adduct formation (S-guanylation) of bacterial surface proteins, which triggered recruitment of autophagy-related proteins p62 and LC3-II to the intracellular bacteria. We also found that Salmonella-produced reactive persulfides downregulated this autophagy by decreasing cellular 8-nitro-cGMP content, thereby inhibiting electrophilic signaling. These data reveal a pathogenic role of bacteria-derived reactive persulfides via suppression of anti-bacterial autophagy.
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Affiliation(s)
- Shahzada Khan
- Gladstone Institute of Virology and Immunology, University of California, San Francisco, CA 94158, USA
| | - Shigemoto Fujii
- Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Tetsuro Matsunaga
- Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Akira Nishimura
- Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Katsuhiko Ono
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
| | - Tomoaki Ida
- Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Khandaker Ahtesham Ahmed
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
| | - Tatsuya Okamoto
- Intensive Care Unit, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan
| | - Hiroyasu Tsutsuki
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
| | - Tomohiro Sawa
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan
| | - Takaaki Akaike
- Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
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4
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The genes slyA, STM3120 and htrA are required for the anticancer ability of VNP20009. Oncotarget 2018; 7:81187-81196. [PMID: 27835896 PMCID: PMC5348385 DOI: 10.18632/oncotarget.13217] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 10/14/2016] [Indexed: 01/05/2023] Open
Abstract
VNP20009 is a very effective anti-cancer agent and can specifically target tumors and inhibit tumor growth. It was assumed that the tumor targeting ability of VNP20009 correlated to its anticancer capacity. However, our observation contradicted to this assumption. Three VNP20009 mutant strains (ΔslyA, ΔSTM3120 and ΔhtrA) with reduced fitness in normal tissues and unchanged fitness in tumors partially or completely lost their anti-cancer capacities. The genes slyA, STM3120 and htrA were required for survival within macrophages and were indispensable for tumor microenvironment remodeling by VNP20009. The infiltration of immune cells occurred less in the tumors of mice infected with the mutant strains. In addition, the mRNA levels of TNF-α and IL-1β were significantly decreased in the tumors of mice treated with the mutant strains. Our results indicate that the immune responses elicited by bacteria rather than the bacterial titer in tumors play a “decisive” role in VNP20009-mediated bacterial cancer therapy, which provides a novel perspective for the underlying mechanism of bacterial cancer therapy.
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5
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Kumawat M, Pesingi PK, Agarwal RK, Goswami TK, Mahawar M. Contribution of protein isoaspartate methyl transferase (PIMT) in the survival of Salmonella Typhimurium under oxidative stress and virulence. Int J Med Microbiol 2016; 306:222-30. [DOI: 10.1016/j.ijmm.2016.04.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 04/07/2016] [Accepted: 04/26/2016] [Indexed: 12/22/2022] Open
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6
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Liang S, Qin X. Critical role of type I interferon-induced macrophage necroptosis during infection with Salmonella enterica serovar Typhimurium. Cell Mol Immunol 2012; 10:99-100. [PMID: 23262973 DOI: 10.1038/cmi.2012.68] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Shujuan Liang
- Key Laboratory for Immunology in Universities of Shandong province, Weifang Medical University, Weifang 261053, China
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7
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Differential modulation of intracellular survival of cytosolic and vacuolar pathogens by curcumin. Antimicrob Agents Chemother 2012; 56:5555-67. [PMID: 22890770 DOI: 10.1128/aac.00496-12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Curcumin, a principal component of turmeric, acts as an immunomodulator regulating the host defenses in response to a diseased condition. The role of curcumin in controlling certain infectious diseases is highly controversial. It is known to alleviate symptoms of Helicobacter pylori infection and exacerbate that of Leishmania infection. We have evaluated the role of curcumin in modulating the fate of various intracellular bacterial pathogens. We show that pretreatment of macrophages with curcumin attenuates the infections caused by Shigella flexneri (clinical isolates) and Listeria monocytogenes and aggravates those caused by Salmonella enterica serovar Typhi CT18 (a clinical isolate), Salmonella enterica serovar Typhimurium, Staphylococcus aureus, and Yersinia enterocolitica. Thus, the antimicrobial nature of curcumin is not a general phenomenon. It modulated the intracellular survival of cytosolic (S. flexneri and L. monocytogenes) and vacuolar (Salmonella spp., Y. enterocolitica, and S. aureus) bacteria in distinct ways. Through colocalization experiments, we demonstrated that curcumin prevented the active phagosomal escape of cytosolic pathogens and enhanced the active inhibition of lysosomal fusion by vacuolar pathogens. A chloroquine resistance assay confirmed that curcumin retarded the escape of the cytosolic pathogens, thus reducing their inter- and intracellular spread. We have demonstrated that the membrane-stabilizing activity of curcumin is crucial for its differential effect on the virulence of the bacteria.
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Oxidative stress modulates the nitric oxide defense promoted by Escherichia coli flavorubredoxin. J Bacteriol 2012; 194:3611-7. [PMID: 22563051 DOI: 10.1128/jb.00140-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mammalian cells of innate immunity respond to pathogen invasion by activating proteins that generate a burst of oxidative and nitrosative stress. Pathogens defend themselves from the toxic compounds by triggering a variety of detoxifying enzymes. Escherichia coli flavorubredoxin is a nitric oxide reductase that is expressed under nitrosative stress conditions. We report that in contrast to nitrosative stress alone, exposure to both nitrosative and oxidative stresses abolishes the expression of flavorubredoxin. Electron paramagnetic resonance (EPR) experiments showed that under these conditions, the iron center of the flavorubredoxin transcription activator NorR loses the ability to bind nitric oxide. Accordingly, triggering of the NorR ATPase activity, a requisite for flavorubredoxin activation, was impaired by treatment of the protein with the double stress. Studies of macrophages revealed that the contribution of flavorubredoxin to the survival of E. coli depends on the stage of macrophage infection and that the lack of protection observed at the early phase is related to inhibition of NorR activity by the oxidative burst. We propose that the time-dependent activation of flavorubredoxin contributes to the adaptation of E. coli to the different fluxes of hydrogen peroxide and nitric oxide to which the bacterium is subjected during the course of macrophage infection.
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Fan YG, Hu CW, Chu C, Chiu KC, Weng BBC. Effect of barley β-glucan on murine RAW264.7 macrophages against virulent Salmonella enterica serovar Typhimurium. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.04.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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10
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The multi-copper-ion oxidase CueO of Salmonella enterica serovar Typhimurium is required for systemic virulence. Infect Immun 2010; 78:2312-9. [PMID: 20231415 DOI: 10.1128/iai.01208-09] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Salmonella enterica serovar Typhimurium possesses a multi-copper-ion oxidase (multicopper oxidase), CueO (also known as CuiD), a periplasmic enzyme known to be required for resistance to copper ions. CueO from S. Typhimurium was expressed as a recombinant protein in Escherichia coli, and the purified protein exhibited a high cuprous oxidase activity. We have characterized an S. Typhimurium cueO mutant and confirmed that it is more sensitive to copper ions. Using a murine model of infection, it was observed that the cueO mutant was significantly attenuated, as indicated by reduced recovery of bacteria from liver and spleen, although there was no significant difference in recovery from Peyer's patches and mesenteric lymph nodes. However, the intracellular survival of the cueO mutant in unprimed or gamma-interferon-primed murine macrophages was not statistically different from that of wild-type Salmonella, suggesting that additional host factors are involved in clearance of the cueO mutant. Unlike a cueO mutant from E. coli, the S. Typhimurium cueO mutant did not show greater sensitivity to hydrogen peroxide and its sensitivity to copper ions was not affected by siderophores. Similarly, the S. Typhimurium cueO mutant was not rescued from copper ion toxicity by addition of the branched-chain amino acids and leucine.
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11
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Valdez Y, Ferreira RBR, Finlay BB. Molecular mechanisms of Salmonella virulence and host resistance. Curr Top Microbiol Immunol 2010; 337:93-127. [PMID: 19812981 DOI: 10.1007/978-3-642-01846-6_4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Salmonella species can cause typhoid fever and gastroenteritis in humans and pose a global threat to human health. In order to establish a successful infection, Salmonella utilize a large number of genes encoding a variety of virulence factors. Different animal models of infection have been used to better understand the mechanisms underlying each disease including cattle, rodents, and nematodes. To date, a number of different bacterial virulence factors have been identified using such animal models, most of which are secreted by two type three secretion systems (T3SS) encoded within Salmonella pathogenicity islands (SPI) 1 and 2. These proteins alter various host cell pathways, facilitating the invasion of epithelial cells during infection, as well as the survival and replication of Salmonella inside phagocytic cells. On the other hand, host genetics and resistance also play a role in the susceptibility to Salmonella infection. The natural resistance-associated macrophage protein 1 (Nramp1), for example, is critical for host defense, since mice lacking Nramp1 fail to control bacterial replication and succumb to low doses of S. Typhimurium. In this chapter, we analyze the different pathogen and host factors that play a role in the dynamic interaction between Salmonella and its host and their impact on disease.
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Affiliation(s)
- Yanet Valdez
- Department of Microbiology and Immunology, Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
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12
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Abstract
The mammalian innate immune response provides a barrier against invading pathogens. Innate immune mechanisms are used by the host to respond to a range of bacterial pathogens in an acute and conserved fashion. Host cells express pattern recognition receptors that sense pathogen-associated molecular patterns. After detection, an arsenal of antimicrobial mechanisms is deployed to kill bacteria in infected cells. Innate immunity also stimulates antigen-specific responses mediated by the adaptive immune system. In response, pathogens manipulate host defence mechanisms to survive and eventually replicate. This Review focuses on the control of host innate immune responses by pathogenic intracellular bacteria.
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13
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Xu T, Maloy S, McGuire KL. Macrophages influence Salmonella host-specificity in vivo. Microb Pathog 2009; 47:212-22. [DOI: 10.1016/j.micpath.2009.07.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2008] [Revised: 07/23/2009] [Accepted: 07/27/2009] [Indexed: 01/21/2023]
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14
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Wu TT, Chen TL, Chen RM. Lipopolysaccharide triggers macrophage activation of inflammatory cytokine expression, chemotaxis, phagocytosis, and oxidative ability via a toll-like receptor 4-dependent pathway: validated by RNA interference. Toxicol Lett 2009; 191:195-202. [PMID: 19735705 DOI: 10.1016/j.toxlet.2009.08.025] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 08/29/2009] [Accepted: 08/31/2009] [Indexed: 11/28/2022]
Abstract
RNA interference has been extensively used to knock-down the translation of certain genes. Toll-like receptor 4 (TLR4) produced by macrophages can be activated in response to endotoxin stimulation. This study used the RNA interference technique to evaluate the roles of TLR4 in lipopolysaccharide (LPS)-stimulated activation of macrophages from the aspects of cytokine production, chemotaxis, phagocytosis, and oxidative ability. Exposure of macrophages to 1, 25, 50, 100 ng/mL LPS for 1, 6, and 24 h did not affect cell viability. Meanwhile, treatment with 100 ng/mL LPS induced interleukin (IL)-1beta protein and mRNA syntheses in a time-dependent manner. Application of TLR4 small interference (si)RNA into macrophages decreased the levels of this receptor, and simultaneously ameliorated LPS-induced IL-1beta and IL-6 mRNA production. Transwell analysis showed that LPS increased chemotactic activity of macrophages, but application of TLR4 siRNA reduced such an effect. Phagocytic activities of macrophages were significantly augmented following LPS treatment. However, knocking-down the translation of TLR4 mRNA using RNA interference lowered the LPS-enhanced phagocytic activity. Analysis of flow cytometry revealed that LPS increased oxidative ability of macrophages, but TLR4 siRNA inhibited such development. This study used RNA interference techniques to show that TLR4 can mediate LPS-induced macrophage activations of IL-1beta and IL-6 gene expression, chemotaxis, phagocytosis, and oxidative ability.
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Affiliation(s)
- Tsu-Tuan Wu
- Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei, Taiwan
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15
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Craig M, Slauch JM. Phagocytic superoxide specifically damages an extracytoplasmic target to inhibit or kill Salmonella. PLoS One 2009; 4:e4975. [PMID: 19305502 PMCID: PMC2654757 DOI: 10.1371/journal.pone.0004975] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 03/02/2009] [Indexed: 11/22/2022] Open
Abstract
Background The phagocytic oxidative burst is a primary effector of innate immunity that protects against bacterial infection. However, the mechanism by which reactive oxygen species (ROS) kill or inhibit bacteria is not known. It is often assumed that DNA is a primary target of oxidative damage, consistent with known effects of endogenously produced ROS in the bacterial cytoplasm. But most studies fail to distinguish between effects of host derived ROS versus damage caused by endogenous bacterial sources. We took advantage of both the ability of Salmonella enterica serovar Typhimurium to survive in macrophages and the genetic tractability of the system to test the hypothesis that phagocytic superoxide damages cytoplasmic targets including DNA. Methodology/Principal Findings SodCI is a periplasmic Cu-Zn superoxide dismutase (SOD) that contributes to the survival of Salmonella Typhimurium in macrophages. Through competitive virulence assays, we asked if sodCI has a genetic interaction with various cytoplasmic systems. We found that SodCI acts independently of cytoplasmic SODs, SodA and SodB. In addition, SodCI acts independently of the base excision repair system and RuvAB, involved in DNA repair. Although sodCI did show genetic interaction with recA, this was apparently independent of recombination and is presumably due to the pleiotropic effects of a recA mutation. Conclusions/Significance Taken together, these results suggest that bacterial inhibition by phagocytic superoxide is primarily the result of damage to an extracytoplasmic target.
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Affiliation(s)
- Maureen Craig
- Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America
| | - James M. Slauch
- Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America
- College of Medicine, University of Illinois, Urbana, Illinois, United States of America
- * E-mail:
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Effect of repeated in vivo passage (in mice) on Salmonella typhimurium dam mutant virulence and fitness. ACTA ACUST UNITED AC 2008; 56:121-4. [PMID: 18178022 DOI: 10.1016/j.patbio.2007.09.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Accepted: 09/28/2007] [Indexed: 12/26/2022]
Abstract
Numerous studies have shown that Salmonella typhimurium dam mutants are highly attenuated for virulence in mice. In vivo studies have also shown that, on oral and intraperitoneal administration, low number of these mutants is able to colonize and persist in target organs. So, they must sense and overcome a myriad of host killing mechanisms. Our goal was to evaluate the effect of in vivo passage, in mice, on S. typhimurium dam mutant virulence and fitness. Swiss albino mice were used for the determination of LD50 and enumeration of bacteria recovered from liver eight days postinfection. Our results indicate that LD50 values of re-isolated mutants were at least two to three-fold lower than those of control strains. Strains re-isolated from liver showed decreased in vitro sensitivity toward sodium deoxycholate and H(2)O(2) than control strains. In addition, the number of re-isolated mutants colonizing spleen and liver was relatively higher than control strains. According to these results, we suggest that persistence of S. typhimurium dam mutants within target organs can increase their in vivo virulence in mice.
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Simon R, Samuel CE. Innate interferon response in macrophage and epithelial cells infected with wild-type compared to DNA adenine methylase and flagellin mutant Salmonella enterica serovar Typhimurium. J Interferon Cytokine Res 2007; 27:317-27. [PMID: 17477819 DOI: 10.1089/jir.2006.0141] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Salmonella enterica serovar Typhimurium is highly virulent and mediates robust interferon (IFN)-stimulated gene (ISG) induction, whereas bacterial mutants that lack the DNA adenine methylase (Dam) are attenuated, elicit a reduced ISG activation profile, and establish immunity to murine typhoid fever. We show here that in contrast to observations in mice, infection of macrophage cell cultures with either wild-type (WT) or dam(-) mutant Salmonella resulted in surprisingly similar kinetics and amplitudes of induction of IFN-beta, the type I IFN-alpha,beta beacon gene Mx, and the type II IFN-gamma beacon inducible nitric oxide synthase (iNOS). Likewise, activation of NF-kappaB-dependent gene expression in epithelial cells was comparable with WT and dam(-) mutant Salmonella. In contrast, the flagellin-deficient flhC(-) mutant did not activate NF-kappaB in epithelial cells but activated ISG expression comparable to that of WT Salmonella in macrophage cells. WT and dam(-) strains displayed a similar Toll-like receptor 5 (TLR5)-dependent NF-kappaB activation, whereas the flhC(-) mutant lacked this activity. UV-inactivated Salmonella elicited similar ISG induction to that of viable Salmonella in macrophages and mediated the establishment of a functional antiviral state but displayed decreased cytocidal activity. These results establish that the inherent IFN system-inducing capacities of dam(-) and WT Salmonella strains in cultured macrophage and epithelial cells, unlike the mouse, are indistinguishable.
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Affiliation(s)
- Raphael Simon
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
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18
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Smallwood HS, Shi L, Squier TC. Increases in calmodulin abundance and stabilization of activated inducible nitric oxide synthase mediate bacterial killing in RAW 264.7 macrophages. Biochemistry 2006; 45:9717-26. [PMID: 16893173 DOI: 10.1021/bi060485p] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The rapid activation of macrophages in response to bacterial antigens is central to the innate immune system that permits the recognition and killing of pathogens to limit infection. To understand regulatory mechanisms underlying macrophage activation, we have investigated changes in the abundance of calmodulin (CaM) and iNOS in response to the bacterial cell wall component lipopolysaccharide (LPS) using RAW 264.7 macrophages. Critical to these measurements was the ability to differentiate free iNOS from the CaM-bound (active) form of iNOS associated with nitric oxide generation. We observe a rapid 2-fold increase in CaM abundance during the first 30 min that is blocked by inhibition of either NFkappaB nuclear translocation or protein synthesis. A similar 2-fold increase in the abundance of the complex between CaM and iNOS is observed with the same time dependence. In contrast, there are no detectable increases in the CaM-free (i.e., inactive) form of iNOS within the first 2 h; it remains at a very low abundance during the initial phase of macrophage activation. Increasing cellular CaM levels in stably transfected macrophages results in a corresponding increase in the abundance of the CaM/iNOS complex that promotes effective bacterial killing following infection by Salmonella typhimurium. Thus, LPS-dependent increases in CaM abundance function in the stabilization and activation of iNOS on the rapid time scale associated with macrophage activation and bacterial killing. These results explain how CaM and iNOS coordinately function to form a stable complex that is part of a rapid host response that functions within the first 30 min following bacterial infection to upregulate the innate immune system involving macrophage activation.
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Affiliation(s)
- Heather S Smallwood
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, USA
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Thaxton JP, Cutler SA, Griffith R, Scanes CG. Changes in Tissue Nitrite Concentration in the Crop of the Turkey Poult in Response to Salmonella Typhimurium Challenge. Poult Sci 2006; 85:1015-9. [PMID: 16776469 DOI: 10.1093/ps/85.6.1015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The present study examines whether Salmonella typhimurium colonization of the crop of young turkeys influences nitrite concentration in the component tissues of the crop. Nitric oxide (NO) is the principal compound in biological samples that is converted into nitrites and NO is known to be a component of the early host response to infection. Challenge with S. typhimurium increased the concentration of nitrite in the crop wall of 3-wk-old turkey poults. The magnitude of the response was reduced at 8 h and absent at 48 h after challenge. As would be expected, S. typhimurium concentrations in the crop were markedly increased following challenge, and were nondetectable in control poults.
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Affiliation(s)
- J P Thaxton
- Department of Poultry Science, Mississippi State University, 39762, USA.
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20
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Alam MS, Zaki MH, Yoshitake J, Akuta T, Ezaki T, Akaike T. Involvement of Salmonella enterica serovar Typhi RpoS in resistance to NO-mediated host defense against serovar Typhi infection. Microb Pathog 2006; 40:116-25. [PMID: 16448800 DOI: 10.1016/j.micpath.2005.11.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Revised: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 11/29/2022]
Abstract
The involvement of nitric oxide (NO) in host defense and cytoprotective functions in murine salmonellosis has been reported. Salmonella mutants with the altered sigma factor RpoS (sigmaS) are less virulent and are susceptible to various stresses. This study investigated the role of the rpoS gene of Salmonella enterica serovar Typhi in NO-dependent host defense in vitro and in vivo. Wild-type mice and mice deficient in inducible NO synthase (iNOS) were infected intraperitoneally or orally with serovar Typhi strains. iNOS-deficient mice were more susceptible to infection by both wild-type and rpoS mutant strains of serovar Typhi and showed extensive apoptotic liver damage compared with wild-type mice. Intracellular killing of Salmonella was analyzed with RAW 264 macrophage-like cells and primary peritoneal macrophages from wild-type and iNOS-deficient mice after cells were infected with the serovar Typhi parent or rpoS mutant strain. The rpoS mutant was more susceptible to killing by macrophages than was the wild-type strain. Also, the wild-type strain produced more extensive apoptotic changes in macrophages than did rpoS mutant. These effects were nullified in RAW 264 cells treated with an NOS inhibitor and in iNOS-deficient primary macrophages. Peroxynitrite susceptibility assays of these strains were also performed. The rpoS mutant Typhi strain was more sensitive to in vitro peroxynitrite treatment than was the parent strain. Together these data show that NO has a significant host defense function during serovar Typhi infection, and that Salmonella RpoS, because it reacts to the presence of NO or its reactive derivatives, is thought to have a role in the pathogenicity of serovar Typhi.
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Affiliation(s)
- Mohammad Samiul Alam
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
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21
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Thompson A, Rowley G, Alston M, Danino V, Hinton JCD. Salmonella transcriptomics: relating regulons, stimulons and regulatory networks to the process of infection. Curr Opin Microbiol 2006; 9:109-16. [PMID: 16413221 DOI: 10.1016/j.mib.2005.12.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Accepted: 12/22/2005] [Indexed: 11/29/2022]
Abstract
The advent of Salmonella transcriptomics has heralded a new era for gene expression analysis of this formidable intracellular pathogen. Increasing numbers of Salmonella transcriptomic datasets will contribute to the comprehensive definition of regulons, stimulons and regulatory networks. This task has highlighted the need for sophisticated computational techniques to describe regulatory interactions.
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Affiliation(s)
- Arthur Thompson
- Molecular Microbiology Group, Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UK.
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22
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Linehan SA, Rytkönen A, Yu XJ, Liu M, Holden DW. SlyA regulates function of Salmonella pathogenicity island 2 (SPI-2) and expression of SPI-2-associated genes. Infect Immun 2005; 73:4354-62. [PMID: 15972530 PMCID: PMC1168564 DOI: 10.1128/iai.73.7.4354-4362.2005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
During the systemic phase of murine infection with Salmonella enterica serovar Typhimurium, bacterial virulence is correlated with the ability to grow and survive within host macrophages. Salmonella pathogenicity island 2 (SPI-2), encoding a type three secretion system, has emerged as an important contributor to Salmonella intracellular growth. SPI-2 mutants have been proposed to be more accessible than wild-type Salmonella to oxyradicals generated by the NADPH phagocyte oxidase. We performed mixed infections of mice to investigate the relationship between SPI-2 and SlyA, a transcriptional regulator that confers resistance to oxyradicals. In mixed-infection experiments, the SPI-2 null mutant was severely attenuated in virulence, whereas slyA mutants were only mildly attenuated. Surprisingly, further experiments indicated that the function of SPI-2 was partially dependent on slyA. The intracellular behavior of a slyA mutant in infected cells was consistent with inefficient SPI-2 expression, as formation of Salmonella-induced filaments and the intracellular F-actin meshwork, features that depend on SPI-2, were present at abnormally low frequencies. Furthermore, the translocated levels of the SPI-2 effector SseJ were severely reduced in a strain carrying a mutation in slyA. We used flow cytometry to investigate the role of SlyA in expression of green fluorescent protein (GFP) from transcriptional fusions with promoters of either of two other SPI-2 effector genes, sifB and sifA. The slyA mutant exhibited reduced GFP expression from both promoters. Combining mutations in slyA and other regulators of SPI-2 indicated that SlyA acts through the SsrAB two-component regulatory system. SlyA exhibits partial functional redundancy with OmpR-EnvZ and contributes to the transcriptional response to low osmolarity and the absence of calcium, two environmental stimuli that promote SPI-2 gene expression.
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Affiliation(s)
- Sheena A Linehan
- Department of Infectious Diseases, Centre for Molecular Microbiology and Infection, Imperial College London, The Flowers Building, Armstrong Road, London SW7 2AZ, United Kingdom
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23
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Henry T, García-Del Portillo F, Gorvel JP. Identification of Salmonella functions critical for bacterial cell division within eukaryotic cells. Mol Microbiol 2005; 56:252-67. [PMID: 15773994 DOI: 10.1111/j.1365-2958.2005.04540.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Salmonella typhimurium multiplication inside eukaryotic host cells is critical for virulence. Salmonella typhimurium strain SL1344 appears as filaments upon growth in macrophages and MelJuSo cells, a human melanoma cell line, indicating a specific blockage in the bacterial cell division process. Several studies have investigated the host cell response impairing bacterial division. However, none looked at the bacterial factors involved in inhibition of Salmonella division inside eukaryotic cells. We show here that blockage in the bacterial division process is sulA-independent and takes place after FtsZ-ring assembly. Salmonella typhimurium genes in which mutations lead to filamentous growth within host cells were identified by a large scale mutagenesis approach on strain 12023, revealing bacterial functions crucial for cell division within eukaryotic cells. We finally demonstrate that SL1344 filamentation is a result of hisG mutation, requires the activity of an enzyme of the histidine biosynthetic pathway HisFH and is specific for the vacuolar environment.
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Affiliation(s)
- T Henry
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, Université de la Méditerranée, Case 906, 13288 Marseille Cedex 9, France
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Suvarnapunya AE, Stein MA. DNA base excision repair potentiates the protective effect of Salmonella Pathogenicity Island 2 within macrophages. Microbiology (Reading) 2005; 151:557-567. [PMID: 15699204 DOI: 10.1099/mic.0.27555-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Reactive oxidants are a primary weapon of the macrophage antibacterial arsenal. The ability of virulent Salmonella to repair oxidative DNA lesions via the base-excision repair system (BER) enables its survival and replication within the macrophage, but is not required for extracellular growth. Salmonella also inhibits the targeting of oxidant generators to the Salmonella-containing vacuole (SCV) via Salmonella Pathogenicity Island 2 (SPI2). Accordingly, the relative contributions of these two discrete systems to Salmonella resistance to both oxidative mutagenesis and lethality within RAW 264.7 macrophages were investigated. A mutant unable to initiate BER was constructed by deleting all three BER bifunctional glycosylases (Δfpg/nth/nei), and was significantly impaired for early intramacrophage survival. Mutations in various SPI2 effector (sifA and sseEFG) and structural (ssaV) genes were then analysed in the BER mutant background. Loss of SPI2 function alone appeared to increase macrophage-induced mutation. Statistical analyses of the reduced intramacrophage survival of SPI2 mutants and the corresponding SPI2/BER mutants indicated a synergistic interaction between BER and SPI2, suggesting that SPI2 promotes intramacrophage survival by protecting Salmonella DNA from exposure to macrophage oxidants. Furthermore, this protection may involve the SseF and SseG effectors. In contrast, the SifA effector did not seem to play a major role in oxidant protection. It is speculated that Salmonella initially stalls oxidative killing by preserving its genomic integrity through the function of BER, until it can upregulate SPI2 to limit its exposure to macrophage oxidants.
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Affiliation(s)
- Akamol E Suvarnapunya
- Department of Microbiology and Molecular Genetics and the Markey Center for Molecular Genetics and Department of Animal Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Murry A Stein
- Department of Microbiology and Molecular Genetics and the Markey Center for Molecular Genetics and Department of Animal Sciences, University of Vermont, Burlington, VT 05405, USA
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Valvano MA, Keith KE, Cardona ST. Survival and persistence of opportunistic Burkholderia species in host cells. Curr Opin Microbiol 2005; 8:99-105. [PMID: 15694863 DOI: 10.1016/j.mib.2004.12.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Burkholderia are microorganisms that have a unique ability to adapt and survive in many different environments. They can also serve as biopesticides and be used for the biodegradation of organic compounds. Usually harmless while living in the soil, these bacteria are opportunistic pathogens of plants and immunocompromised patients, and occasionally infect healthy individuals. Some of the species in this genus can also be utilised as biological weapons. They all possess very large genomes and have two or more circular chromosomes. Their survival and persistence, not only in the environment but also in host cells, offers a remarkable example of bacterial adaptation.
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Affiliation(s)
- Miguel A Valvano
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada.
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26
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Abstract
Ubiquitination is a protein modification generally used by cells to tag proteins that are destined for proteasomal degradation. In a recent article, Perrin et al. reported that the ubiquitination system has a role in the recognition of bacterial pathogens in the cytosol of mammalian cells. They showed that polyubiquitinated proteins accumulate on the surface of cytosolic Salmonella typhimurium. In macrophages, but not epithelial cells, proteasomes become associated with the surface of cytosolic bacteria. The authors proposed that the ubiquitin-proteasome machinery might be implicated indirectly in bacterial clearance.
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Affiliation(s)
- Esteban Veiga
- Unité des Interactions Bactéries-Cellules, Institut Pasteur, INSERM U 604, USC INRA, 28 rue du Dr Roux, Paris CEDEX 15, France
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27
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Nilsson AI, Kugelberg E, Berg OG, Andersson DI. Experimental adaptation of Salmonella typhimurium to mice. Genetics 2004; 168:1119-30. [PMID: 15579674 PMCID: PMC1448776 DOI: 10.1534/genetics.104.030304] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Accepted: 07/13/2004] [Indexed: 01/13/2023] Open
Abstract
Experimental evolution is a powerful approach to study the dynamics and mechanisms of bacterial niche specialization. By serial passage in mice, we evolved 18 independent lineages of Salmonella typhimurium LT2 and examined the rate and extent of adaptation to a mainly reticuloendothelial host environment. Bacterial mutation rates and population sizes were varied by using wild-type and DNA repair-defective mutator (mutS) strains with normal and high mutation rates, respectively, and by varying the number of bacteria intraperitoneally injected into mice. After <200 generations of adaptation all lineages showed an increased fitness as measured by a faster growth rate in mice (selection coefficients 0.11-0.58). Using a generally applicable mathematical model we calculated the adaptive mutation rate for the wild-type bacterium to be >10(-6)/cell/generation, suggesting that the majority of adaptive mutations are not simple point mutations. For the mutator lineages, adaptation to mice was associated with a loss of fitness in secondary environments as seen by a reduced metabolic capability. During adaptation there was no indication that a high mutation rate was counterselected. These data show that S. typhimurium can rapidly and extensively increase its fitness in mice but this niche specialization is, at least in mutators, associated with a cost.
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Affiliation(s)
- Annika I Nilsson
- Department of Bacteriology, Swedish Institute for Infectious Disease Control, S-171 82 Solna, Sweden
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28
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Jiang X, Rossanese OW, Brown NF, Kujat-Choy S, Galán JE, Finlay BB, Brumell JH. The related effector proteins SopD and SopD2 from Salmonella enterica serovar Typhimurium contribute to virulence during systemic infection of mice. Mol Microbiol 2004; 54:1186-98. [PMID: 15554961 DOI: 10.1111/j.1365-2958.2004.04344.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Salmonella resides within host cells in a vacuole that it modifies through the action of virulence proteins called effectors. Here we examined the role of two related effectors, SopD and SopD2, in Salmonella pathogenesis. Salmonella enterica serovar Typhimurium (S. Typhimurium) mutants lacking either sopD or sopD2 were attenuated for replication in the spleens of infected mice when competed against wild-type bacteria in mixed infection experiments. A double mutant lacking both effector genes did not display an additive attenuation of virulence in these experiments. The double mutant also competed equally with both of the single mutants. Deletion of either effector impaired bacterial replication in mouse macrophages but not human epithelial cells. Deletion of sopD2 impaired Salmonella's ability to form tubular membrane filaments [Salmonella-induced filaments (Sifs)] in infected cells; the number of Sifs decreased, whereas the number of pseudo-Sifs (thought to be a precursor of Sifs) was increased. Transfection of HeLa cells with the effector SifA induced the formation of Sif-like tubules and these were observed in greater size and number after co-transfection of SifA with SopD2. In infected cells, SifA and SopD2 were localized both to Sifs and to pseudo-Sifs. In contrast, deletion of sopD had no effect on Sif formation. Our results indicate that both SopD and SopD2 contribute to virulence in mice and suggest a functional relationship between these two proteins during systemic infection of the host.
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Affiliation(s)
- Xiuju Jiang
- Infection, Immunity, Injury and Repair Program, Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada
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29
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Wildschutte H, Wolfe DM, Tamewitz A, Lawrence JG. Protozoan predation, diversifying selection, and the evolution of antigenic diversity in Salmonella. Proc Natl Acad Sci U S A 2004; 101:10644-9. [PMID: 15247413 PMCID: PMC489988 DOI: 10.1073/pnas.0404028101] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Extensive population-level genetic variability at the Salmonella rfb locus, which encodes enzymes responsible for synthesis of the O-antigen polysaccharide, is thought to have arisen through frequency-dependent selection (FDS) by means of exposure of this pathogen to host immune systems. The FDS hypothesis works well for pathogens such as Haemophilus influenzae and Neisseria meningitis, which alter the composition of their O-antigens during the course of bloodborne infections. In contrast, Salmonella remains resident in epithelial cells or macrophages during infection and does not have phase variability in its O-antigen. More importantly, Salmonella shows host-serovar specificity, whereby strains bearing certain O-antigens cause disease primarily in specific hosts; this behavior is inconsistent with FDS providing selection for the origin or maintenance of extensive polymorphism at the rfb locus. Alternatively, selective pressure may originate from the host intestinal environment itself, wherein diversifying selection mediated by protozoan predation allows for the continued existence of Salmonella able to avoid consumption by host-specific protozoa. This selective pressure would result in high population-level diversity at the Salmonella rfb locus without phase variation. We show here that intestinal protozoa recognize antigenically diverse Salmonella with different efficiencies and demonstrate that differences solely in the O-antigen are sufficient to allow for prey discrimination. Combined with observations of the differential distributions of both serotypes of bacterial species and their protozoan predators among environments, our data provides a framework for the evolution of high genetic diversity at the rfb locus and host-specific pathogenicity in Salmonella.
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Affiliation(s)
- Hans Wildschutte
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15235, USA
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30
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Sukumaran SK, Shimada H, Prasadarao NV. Entry and intracellular replication of Escherichia coli K1 in macrophages require expression of outer membrane protein A. Infect Immun 2003; 71:5951-61. [PMID: 14500515 PMCID: PMC201085 DOI: 10.1128/iai.71.10.5951-5961.2003] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Interactions between Escherichia coli K1, which causes meningitis in neonates, and macrophages have not been explored well. In this study we found that E. coli K1 was able to enter, survive, and replicate intracellularly in both murine and human macrophage cell lines, as well as in monocytes and macrophages of newborn rats. In addition, we demonstrated that OmpA (+) E. coli also enters and replicates in human peripheral blood monocytes in vitro. Outer membrane protein A (OmpA) expression on E. coli contributes to binding to macrophages, phagocytosis, and survival within macrophages. Opsonization with either complement proteins or antibody is not required for uptake and survival of the bacteria within the macrophages. Transmission electron microscopy and immunocytochemistry studies with the infected macrophages indicated that OmpA(+) E. coli multiplies enormously in a single phagosome and bursts the cell. Internalization of OmpA(+) E. coli by RAW 264.7 cells occurred by both actin- and microtubule-dependent processes, which are independent of RGD-mediated integrin receptors. Internalization and intracellular survival within phagocytic cells thus may play an important role in the development of bacteremia, which is crucial for E. coli crossing of the blood-brain barrier.
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Affiliation(s)
- Sunil K Sukumaran
- Division of Infectious Diseases, Children's Hospital Los Angeles and Keck School of Medicine, University of Southern California, 4650 Sunset Boulevard, Los Angeles, CA 90027, USA
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