Bacillus anthracis genomic DNA enhances lethal toxin-induced cytotoxicity through TNF-αproduction

Jun Ho Jeon, Yeon Hee Kim, Min Kyung Choi, Kyung Ae Kim, Hae Ri Lee, Jeyoun Jang, Yu Ri Kim, Jeong Hoon Chun, Seong Kug Eo, Tae Sung Kim, Gi Eun Rhie

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Background: Bacillus anthracis is the etiological agent of anthrax. Lethal toxin (LT) produced by B. anthracis is a well-known key virulence factor for anthrax because of its strong cytotoxic activity. However, little is known about the role of B. anthracis genomic DNA (BAG) in anthrax pathogenesis. Results: We examined the effect of BAG on TNF-α production and LT-mediated cytotoxicity during B. anthracis spore infection in mouse macrophage cell lines (RAW264.7 cells and J774A.1) and BALB/c mice. Infection of RAW264.7 cells with B. anthracis spores induced TNF-α expression in a multiplicity of infection (MOI)-dependent manner, and this enhancement was attenuated by the toll-like receptor (TLR) 9 inhibitor oligodeoxynucleotide (ODN)2088. BAG led to TNF-α expression in a dose- and time-dependent manner when applied to RAW264.7 cells. TNF-α expression induced by BAG was reduced by either pretreatment with TLR9 inhibitors (ODN2088 and chloroquine (CQ)) or transfection with TLR9 siRNA. Furthermore, BAG-induced TNF-α production in TLR9+/+ macrophages was completely abrogated in TLR9-/- macrophages. BAG enhanced the phosphorylation of mitogen-activated protein kinases (MAPK), and BAG-induced TNF-α expression was attenuated by pretreatment with MAPK inhibitors. A reporter gene assay and confocal microscopy demonstrated that BAG increased NF-κB activation, which is responsible for TNF-αexpression. Treatment with BAG alone showed no cytotoxic activity on the macrophage cell line J774A.1, whereas LT-mediated cytotoxicity was enhanced by treatment with BAG or TNF-α. Enhanced LT-induced lethality was also confirmed by BAG administration in mice. Furthermore, LT plus BAG-mediated lethality was significantly recovered by administration of Infliximab, an anti-TNF-α monoclonal antibody. Conclusions: Our results suggest that B. anthracis DNA may contribute to anthrax pathogenesis by enhancing LT activity via TLR9-mediated TNF-α production.

Original languageEnglish
Article number300
JournalBMC Microbiology
Volume14
Issue number1
DOIs
Publication statusPublished - 2014

Fingerprint

Bacillus anthracis
DNA
Anthrax
Macrophages
Mitogen-Activated Protein Kinases
Spores
Infection
Toll-Like Receptor 9
Cell Line
Proto-Oncogene Proteins c-akt
Oligodeoxyribonucleotides
Chloroquine
Virulence Factors
Protein Kinase Inhibitors
Reporter Genes
Confocal Microscopy
Small Interfering RNA

Keywords

  • Bacillus anthracis
  • Genomic DNA
  • Lethal toxin
  • TLR9
  • TNF-α

ASJC Scopus subject areas

  • Microbiology
  • Microbiology (medical)

Cite this

Jeon, J. H., Kim, Y. H., Choi, M. K., Kim, K. A., Lee, H. R., Jang, J., ... Rhie, G. E. (2014). Bacillus anthracis genomic DNA enhances lethal toxin-induced cytotoxicity through TNF-αproduction. BMC Microbiology, 14(1), [300]. https://doi.org/10.1186/s12866-014-0300-9

Bacillus anthracis genomic DNA enhances lethal toxin-induced cytotoxicity through TNF-αproduction. / Jeon, Jun Ho; Kim, Yeon Hee; Choi, Min Kyung; Kim, Kyung Ae; Lee, Hae Ri; Jang, Jeyoun; Kim, Yu Ri; Chun, Jeong Hoon; Eo, Seong Kug; Kim, Tae Sung; Rhie, Gi Eun.

In: BMC Microbiology, Vol. 14, No. 1, 300, 2014.

Research output: Contribution to journalArticle

Jeon, JH, Kim, YH, Choi, MK, Kim, KA, Lee, HR, Jang, J, Kim, YR, Chun, JH, Eo, SK, Kim, TS & Rhie, GE 2014, 'Bacillus anthracis genomic DNA enhances lethal toxin-induced cytotoxicity through TNF-αproduction', BMC Microbiology, vol. 14, no. 1, 300. https://doi.org/10.1186/s12866-014-0300-9
Jeon, Jun Ho ; Kim, Yeon Hee ; Choi, Min Kyung ; Kim, Kyung Ae ; Lee, Hae Ri ; Jang, Jeyoun ; Kim, Yu Ri ; Chun, Jeong Hoon ; Eo, Seong Kug ; Kim, Tae Sung ; Rhie, Gi Eun. / Bacillus anthracis genomic DNA enhances lethal toxin-induced cytotoxicity through TNF-αproduction. In: BMC Microbiology. 2014 ; Vol. 14, No. 1.
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abstract = "Background: Bacillus anthracis is the etiological agent of anthrax. Lethal toxin (LT) produced by B. anthracis is a well-known key virulence factor for anthrax because of its strong cytotoxic activity. However, little is known about the role of B. anthracis genomic DNA (BAG) in anthrax pathogenesis. Results: We examined the effect of BAG on TNF-α production and LT-mediated cytotoxicity during B. anthracis spore infection in mouse macrophage cell lines (RAW264.7 cells and J774A.1) and BALB/c mice. Infection of RAW264.7 cells with B. anthracis spores induced TNF-α expression in a multiplicity of infection (MOI)-dependent manner, and this enhancement was attenuated by the toll-like receptor (TLR) 9 inhibitor oligodeoxynucleotide (ODN)2088. BAG led to TNF-α expression in a dose- and time-dependent manner when applied to RAW264.7 cells. TNF-α expression induced by BAG was reduced by either pretreatment with TLR9 inhibitors (ODN2088 and chloroquine (CQ)) or transfection with TLR9 siRNA. Furthermore, BAG-induced TNF-α production in TLR9+/+ macrophages was completely abrogated in TLR9-/- macrophages. BAG enhanced the phosphorylation of mitogen-activated protein kinases (MAPK), and BAG-induced TNF-α expression was attenuated by pretreatment with MAPK inhibitors. A reporter gene assay and confocal microscopy demonstrated that BAG increased NF-κB activation, which is responsible for TNF-αexpression. Treatment with BAG alone showed no cytotoxic activity on the macrophage cell line J774A.1, whereas LT-mediated cytotoxicity was enhanced by treatment with BAG or TNF-α. Enhanced LT-induced lethality was also confirmed by BAG administration in mice. Furthermore, LT plus BAG-mediated lethality was significantly recovered by administration of Infliximab, an anti-TNF-α monoclonal antibody. Conclusions: Our results suggest that B. anthracis DNA may contribute to anthrax pathogenesis by enhancing LT activity via TLR9-mediated TNF-α production.",
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AU - Kim, Yeon Hee

AU - Choi, Min Kyung

AU - Kim, Kyung Ae

AU - Lee, Hae Ri

AU - Jang, Jeyoun

AU - Kim, Yu Ri

AU - Chun, Jeong Hoon

AU - Eo, Seong Kug

AU - Kim, Tae Sung

AU - Rhie, Gi Eun

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N2 - Background: Bacillus anthracis is the etiological agent of anthrax. Lethal toxin (LT) produced by B. anthracis is a well-known key virulence factor for anthrax because of its strong cytotoxic activity. However, little is known about the role of B. anthracis genomic DNA (BAG) in anthrax pathogenesis. Results: We examined the effect of BAG on TNF-α production and LT-mediated cytotoxicity during B. anthracis spore infection in mouse macrophage cell lines (RAW264.7 cells and J774A.1) and BALB/c mice. Infection of RAW264.7 cells with B. anthracis spores induced TNF-α expression in a multiplicity of infection (MOI)-dependent manner, and this enhancement was attenuated by the toll-like receptor (TLR) 9 inhibitor oligodeoxynucleotide (ODN)2088. BAG led to TNF-α expression in a dose- and time-dependent manner when applied to RAW264.7 cells. TNF-α expression induced by BAG was reduced by either pretreatment with TLR9 inhibitors (ODN2088 and chloroquine (CQ)) or transfection with TLR9 siRNA. Furthermore, BAG-induced TNF-α production in TLR9+/+ macrophages was completely abrogated in TLR9-/- macrophages. BAG enhanced the phosphorylation of mitogen-activated protein kinases (MAPK), and BAG-induced TNF-α expression was attenuated by pretreatment with MAPK inhibitors. A reporter gene assay and confocal microscopy demonstrated that BAG increased NF-κB activation, which is responsible for TNF-αexpression. Treatment with BAG alone showed no cytotoxic activity on the macrophage cell line J774A.1, whereas LT-mediated cytotoxicity was enhanced by treatment with BAG or TNF-α. Enhanced LT-induced lethality was also confirmed by BAG administration in mice. Furthermore, LT plus BAG-mediated lethality was significantly recovered by administration of Infliximab, an anti-TNF-α monoclonal antibody. Conclusions: Our results suggest that B. anthracis DNA may contribute to anthrax pathogenesis by enhancing LT activity via TLR9-mediated TNF-α production.

AB - Background: Bacillus anthracis is the etiological agent of anthrax. Lethal toxin (LT) produced by B. anthracis is a well-known key virulence factor for anthrax because of its strong cytotoxic activity. However, little is known about the role of B. anthracis genomic DNA (BAG) in anthrax pathogenesis. Results: We examined the effect of BAG on TNF-α production and LT-mediated cytotoxicity during B. anthracis spore infection in mouse macrophage cell lines (RAW264.7 cells and J774A.1) and BALB/c mice. Infection of RAW264.7 cells with B. anthracis spores induced TNF-α expression in a multiplicity of infection (MOI)-dependent manner, and this enhancement was attenuated by the toll-like receptor (TLR) 9 inhibitor oligodeoxynucleotide (ODN)2088. BAG led to TNF-α expression in a dose- and time-dependent manner when applied to RAW264.7 cells. TNF-α expression induced by BAG was reduced by either pretreatment with TLR9 inhibitors (ODN2088 and chloroquine (CQ)) or transfection with TLR9 siRNA. Furthermore, BAG-induced TNF-α production in TLR9+/+ macrophages was completely abrogated in TLR9-/- macrophages. BAG enhanced the phosphorylation of mitogen-activated protein kinases (MAPK), and BAG-induced TNF-α expression was attenuated by pretreatment with MAPK inhibitors. A reporter gene assay and confocal microscopy demonstrated that BAG increased NF-κB activation, which is responsible for TNF-αexpression. Treatment with BAG alone showed no cytotoxic activity on the macrophage cell line J774A.1, whereas LT-mediated cytotoxicity was enhanced by treatment with BAG or TNF-α. Enhanced LT-induced lethality was also confirmed by BAG administration in mice. Furthermore, LT plus BAG-mediated lethality was significantly recovered by administration of Infliximab, an anti-TNF-α monoclonal antibody. Conclusions: Our results suggest that B. anthracis DNA may contribute to anthrax pathogenesis by enhancing LT activity via TLR9-mediated TNF-α production.

KW - Bacillus anthracis

KW - Genomic DNA

KW - Lethal toxin

KW - TLR9

KW - TNF-α

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