Burkholderia pseudomallei RpoS regulates multinucleated giant cell formation and inducible nitric oxide synthase expression in mouse macrophage cell line (RAW 264.7)

Utaisincharoen, Pongsak; Arjcharoen, S.; Limposuwan, K.; Tungpradabkul, Sumalee; Sirisinha, Stitaya

doi:10.1016/j.micpath.2006.01.002

Cited by 37 publications

(32 citation statements)

References 25 publications

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“…Despite a series of in vitro studies that have shown that nitric oxide is important for the bactericidal effects of IFN-␥ against both B. pseudomallei and B. mallei, in our studies we failed to find a role for nitric oxide in CLDC-mediated protective activity (3,15,23,35,36). Our findings thus are in agreement with a previous in vivo study wherein mice lacking the iNOS gene (NOS2 Ϫ/Ϫ ) did not exhibit increased susceptibility to B. pseudomallei infection (8).…”

Section: Discussionmentioning

confidence: 57%

“…IFN-␥ also is known to be a potent inducer of NOS2 (iNOS) activity, with the subsequent production of nitric oxide (24) tion, which in turn mediates bacterial killing. Other in vitro studies have shown that Burkholderia species may downmodulate nitric oxide production in order to enhance its survival (3,15,23,35,36). In contrast to the results obtained in these in vitro studies, in vivo B. pseudomallei challenge studies using NOS2 Ϫ/Ϫ mice have failed to demonstrate a role for nitric oxide in controlling infection (8).…”

Section: Ifn-␥ Is Necessary For Cldc-mediated Protection In Vivomentioning

confidence: 88%

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Protection from Pneumonic Infection withBurkholderiaSpecies by Inhalational Immunotherapy

Goodyear¹,

Kellihan²,

Bielefeldt‐Ohmann³

et al. 2009

Infect Immun

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Burkholderia mallei and B. pseudomallei are important human pathogens and cause the diseases glanders and melioidosis, respectively. Both organisms are highly infectious when inhaled and are inherently resistant to many antimicrobials, thus making it difficult to treat pneumonic Burkholderia infections. We investigated whether it was possible to achieve rapid protection against inhaled Burkholderia infection by using inhaled immunotherapy. For this purpose, cationic liposome DNA complexes (CLDC), which are potent activators of innate immunity, were used to elicit the activation of pulmonary innate immune responses. We found that mucosal CLDC administration before or shortly after bacterial challenge could generate complete or nearly complete protection from inhalational challenge with 100% lethal doses of B. mallei and B. pseudomallei. Protection was found to be dependent on the CLDC-mediated induction of gamma interferon responses in lung tissues and was partially dependent on the activation of NK cells. However, CLDC-mediated protection was not dependent on the induction of inducible nitric oxide synthase, as assessed by depletion studies. We concluded that the potent local activation of innate immune responses in the lung could be used to elicit rapid and nonspecific protection from aerosol exposure to both B. mallei and B. pseudomallei.

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Section: Discussionmentioning

confidence: 57%

Section: Ifn-␥ Is Necessary For Cldc-mediated Protection In Vivomentioning

confidence: 88%

Protection from Pneumonic Infection withBurkholderiaSpecies by Inhalational Immunotherapy

Goodyear¹,

Kellihan²,

Bielefeldt‐Ohmann³

et al. 2009

Infect Immun

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“…To date, both BipB and RpoS have been implicated in B. pseudomallei-induced MNGC formation in murine macrophage cell lines (54,58). One of the most striking observations from this study was the inability of B. mallei tssE mutants to induce MNGCs following infection of RAW 264.7 cell monolayers.…”

Section: Vol 78 2010 Interactions Of B Mallei T6s Mutants With Macmentioning

confidence: 61%

Burkholderia mallei Cluster 1 Type VI Secretion Mutants Exhibit Growth and Actin Polymerization Defects in RAW 264.7 Murine Macrophages

Burtnick

DeShazer

Nair³

et al. 2010

Infect Immun

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Burkholderia mallei is a facultative intracellular pathogen that causes severe disease in animals and humans. Recent studies have shown that the cluster 1 type VI secretion system (T6SS-1) expressed by this organism is essential for survival in a hamster model of glanders. To better understand the role of T6SS-1 in the pathogenesis of disease, studies were initiated to examine the interactions of B. mallei tssE mutants with RAW 264.7 murine macrophages. Results obtained by utilizing modified gentamicin protection assays indicated that although the tssE mutants were able to survive within RAW 264.7 cells, significant growth defects were observed in comparison to controls. In addition, analysis of infected monolayers by differential interference contrast and fluorescence microscopy demonstrated that the tssE mutants lacked the ability to induce multinucleated giant cell formation. Via the use of fluorescence microscopy, tssE mutants were shown to undergo escape from lysosome-associated membrane protein 1-positive vacuoles. Curiously, however, following entry into the cytosol, the mutants exhibited actin polymerization defects resulting in inefficient intra-and intercellular spread characteristics. Importantly, all mutant phenotypes observed in this study could be restored by complementation. Based upon these findings, it appears that T6SS-1 plays a critical role in growth and actin-based motility following uptake of B. mallei by RAW 264.7 cells.

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“…MNGC are predicted to be important for evasion of host immune responses and persistence of B. pseudomallei within the host (11). The formation of MNGC does not occur if bacterial protein synthesis is inhibited after B. pseudomallei is internalized in RAW 264.7 cells (35), suggesting that a bacterial factor needs to be actively synthesized intracellularly for MNGC to form. We propose that a T6SS-1 effector mediates MNGC formation by activating molecular machinery involved in macrophage fusion (16).…”

Section: Discussionmentioning

confidence: 99%

The Cluster 1 Type VI Secretion System Is a Major Virulence Determinant in Burkholderia pseudomallei

et al. 2011

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The Burkholderia pseudomallei K96243 genome encodes six type VI secretion systems (T6SSs), but little is known about the role of these systems in the biology of B. pseudomallei. In this study, we purified recombinant Hcp proteins from each T6SS and tested them as vaccine candidates in the BALB/c mouse model of melioidosis. Recombinant Hcp2 protected 80% of mice against a lethal challenge with K96243, while recombinant Hcp1, Hcp3, and Hcp6 protected 50% of mice against challenge. Hcp6 was the only Hcp constitutively produced by B. pseudomallei in vitro; however, it was not exported to the extracellular milieu. Hcp1, on the other hand, was produced and exported in vitro when the VirAG two-component regulatory system was overexpressed in trans. We also constructed six hcp deletion mutants (⌬hcp1 through ⌬hcp6) and tested them for virulence in the Syrian hamster model of infection. The 50% lethal doses (LD 50 s) for the ⌬hcp2 through ⌬hcp6 mutants were indistinguishable from K96243 (<10 bacteria), but the LD 50 for the ⌬hcp1 mutant was >10 3 bacteria. The hcp1 deletion mutant also exhibited a growth defect in RAW 264.7 macrophages and was unable to form multinucleated giant cells in this cell line. Unlike K96243, the ⌬hcp1 mutant was only weakly cytotoxic to RAW 264.7 macrophages 18 h after infection. The results suggest that the cluster 1 T6SS is essential for virulence and plays an important role in the intracellular lifestyle of B. pseudomallei.

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Burkholderia pseudomallei RpoS regulates multinucleated giant cell formation and inducible nitric oxide synthase expression in mouse macrophage cell line (RAW 264.7)

Cited by 37 publications

References 25 publications

Protection from Pneumonic Infection withBurkholderiaSpecies by Inhalational Immunotherapy

Protection from Pneumonic Infection withBurkholderiaSpecies by Inhalational Immunotherapy

Burkholderia mallei Cluster 1 Type VI Secretion Mutants Exhibit Growth and Actin Polymerization Defects in RAW 264.7 Murine Macrophages

The Cluster 1 Type VI Secretion System Is a Major Virulence Determinant in Burkholderia pseudomallei

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