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

doi:10.1186/s12866-014-0300-9

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

Department of Life Sciences

Research output: Contribution to journal › Article › peer-review

5 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 language	English
Article number	300
Journal	BMC Microbiology
Volume	14
Issue number	1
DOIs	https://doi.org/10.1186/s12866-014-0300-9
Publication status	Published - 2014 Dec

Keywords

Bacillus anthracis
Genomic DNA
Lethal toxin
TLR9
TNF-α

ASJC Scopus subject areas

Microbiology
Microbiology (medical)

Access to Document

10.1186/s12866-014-0300-9

Cite this

@article{b85130b63f4a4e0eaa4e76f2e6df74c7,

title = "Bacillus anthracis genomic DNA enhances lethal toxin-induced cytotoxicity through TNF-αproduction",

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.",

keywords = "Bacillus anthracis, Genomic DNA, Lethal toxin, TLR9, TNF-α",

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

note = "Funding Information: This work was supported by a grant (2009-N45001-00) from the Research of Korea Centers for Disease Control and Prevention. We thank Dr. H. Baek of Gachon University School of Medicine, Gil Hospital for providing Infliximab for this research. We also appreciate Dr. K. Cha and Dr. K. Hong for helpful discussions. Publisher Copyright: {\textcopyright} 2014 Jeon et al.; licensee BioMed Central Ltd.",

year = "2014",

month = dec,

doi = "10.1186/s12866-014-0300-9",

language = "English",

volume = "14",

journal = "BMC Microbiology",

issn = "1471-2180",

publisher = "BioMed Central",

number = "1",

}

TY - JOUR

T1 - Bacillus anthracis genomic DNA enhances lethal toxin-induced cytotoxicity through TNF-αproduction

AU - Jeon, Jun Ho

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

N1 - Funding Information: This work was supported by a grant (2009-N45001-00) from the Research of Korea Centers for Disease Control and Prevention. We thank Dr. H. Baek of Gachon University School of Medicine, Gil Hospital for providing Infliximab for this research. We also appreciate Dr. K. Cha and Dr. K. Hong for helpful discussions. Publisher Copyright: © 2014 Jeon et al.; licensee BioMed Central Ltd.

PY - 2014/12

Y1 - 2014/12

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

UR - http://www.scopus.com/inward/record.url?scp=84924192376&partnerID=8YFLogxK

U2 - 10.1186/s12866-014-0300-9

DO - 10.1186/s12866-014-0300-9

M3 - Article

C2 - 25472474

AN - SCOPUS:84924192376

SN - 1471-2180

VL - 14

JO - BMC Microbiology

JF - BMC Microbiology

IS - 1

M1 - 300

ER -

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

Abstract

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this