Limits...
Crucial role of interferon consensus sequence binding protein, but neither of interferon regulatory factor 1 nor of nitric oxide synthesis for protection against murine listeriosis.

Fehr T, Schoedon G, Odermatt B, Holtschke T, Schneemann M, Bachmann MF, Mak TW, Horak I, Zinkernagel RM - J. Exp. Med. (1997)

Bottom Line: However, the involved signaling pathways and effector mechanisms are still poorly understood.This correlated with impaired elimination of Listeria from infected peritoneal macrophage (PEM) cultures stimulated with IFN-gamma in vitro; in addition these cultures showed reduced and delayed oxidative burst upon IFN-gamma stimulation, whereas nitric oxide production was normal.These results indicate that (a) the ICSBP/IRF2 complex is essential for IFN-gamma-mediated protection against Listeria and that (b) ROI together with additional still unknown effector mechanisms may be responsible for the anti-Listeria activity of macrophages, whereas IRF1-induced RNI are not limiting.

View Article: PubMed Central - PubMed

Affiliation: Institute of Experimental Immunology, University Hospital, Zürich, Switzerland.

ABSTRACT
Listeria monocytogenes is widely used as a model to study immune responses against intracellular bacteria. It has been shown that neutrophils and macrophages play an important role to restrict bacterial replication in the early phase of primary infection in mice, and that the cytokines interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) are essential for protection. However, the involved signaling pathways and effector mechanisms are still poorly understood. This study investigated mouse strains deficient for the IFN-dependent transcription factors interferon consensus sequence binding protein (ICSBP), interferon regulatory factor (IRF) 1 or 2 for their capacity to eliminate Listeria in vivo and in vitro and for production of inducible reactive nitrogen intermediates (RNI) or reactive oxygen intermediates (ROI) in macrophages. ICSBP-/- and to a lesser degree also IRF2-/- mice were highly susceptible to Listeria infection. This correlated with impaired elimination of Listeria from infected peritoneal macrophage (PEM) cultures stimulated with IFN-gamma in vitro; in addition these cultures showed reduced and delayed oxidative burst upon IFN-gamma stimulation, whereas nitric oxide production was normal. In contrast, mice deficient for IRF1 were not able to produce nitric oxide, but they efficiently controlled Listeria in vivo and in vitro. These results indicate that (a) the ICSBP/IRF2 complex is essential for IFN-gamma-mediated protection against Listeria and that (b) ROI together with additional still unknown effector mechanisms may be responsible for the anti-Listeria activity of macrophages, whereas IRF1-induced RNI are not limiting.

Show MeSH

Related in: MedlinePlus

Elimination of Listeria from a PEM culture stimulated with  LPS, IFN-γ or both. PEM of mice deficient for different IFN-related  transcription factors were elicited with starch solution, harvested after 5 d  and put into culture on cover slips under presence of the indicated stimulators. After 42 h (at time point t0) they were infected with Listeria and allowed to digest the bacteria during 7 h. Then, cover slips were taken out,  dried and May-Grünwald-Giemsa stained. The number of infected macrophages was counted under the microscope, compared to the infection  rate at t0 and expressed as difference in percentage of infected cells. Error  bars represent standard deviation. Examples for absolute numbers: the  number of infected macrophages at t0 was between 80 and 106/200 for all  strains; the number of infected cells in IFN-γ-stimulated cultures after 7 h  of digestion was 19/200 for wild-type and 168/200 for ICSBP−/− mice.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2196174&req=5

Figure 3: Elimination of Listeria from a PEM culture stimulated with LPS, IFN-γ or both. PEM of mice deficient for different IFN-related transcription factors were elicited with starch solution, harvested after 5 d and put into culture on cover slips under presence of the indicated stimulators. After 42 h (at time point t0) they were infected with Listeria and allowed to digest the bacteria during 7 h. Then, cover slips were taken out, dried and May-Grünwald-Giemsa stained. The number of infected macrophages was counted under the microscope, compared to the infection rate at t0 and expressed as difference in percentage of infected cells. Error bars represent standard deviation. Examples for absolute numbers: the number of infected macrophages at t0 was between 80 and 106/200 for all strains; the number of infected cells in IFN-γ-stimulated cultures after 7 h of digestion was 19/200 for wild-type and 168/200 for ICSBP−/− mice.

Mentions: To evaluate listericidal activity of macrophages of the different mutant mouse strains, we tested PEM in an in vitro killing assay. ICSBP−/−, IRF1−/−, and IRF2−/− PEM were elicited by starch injection intraperitoneally, plated onto cover slips and cultured as described in Materials and Methods. After 42 h the cultures were infected with Listeria in vitro, and the number of infected cells determined at time point t0 and after 7 h of infection. The results (Fig. 3) show that PEM of ICSBP−/− and, to a lesser degree, IRF2−/− mice allowed enhanced replication of Listeria, whereas PEM of IRF1−/− and normal mice were able to reduce the bacterial load in these macrophage cultures. Also the number of bacteria per macrophage was higher in ICSBP−/− mice (mostly more than 10 bacteria/cell) compared to their controls (0–4 bacteria/cell), revealing some macrophages with plenty of Listeria and typical comet tails (18). This finding confirms the defect in macrophage effector function, which correlates with the in vivo susceptibility of these mouse strains to Listeria (ICSBP−/− >IRF2−/− >IRF1−/−).


Crucial role of interferon consensus sequence binding protein, but neither of interferon regulatory factor 1 nor of nitric oxide synthesis for protection against murine listeriosis.

Fehr T, Schoedon G, Odermatt B, Holtschke T, Schneemann M, Bachmann MF, Mak TW, Horak I, Zinkernagel RM - J. Exp. Med. (1997)

Elimination of Listeria from a PEM culture stimulated with  LPS, IFN-γ or both. PEM of mice deficient for different IFN-related  transcription factors were elicited with starch solution, harvested after 5 d  and put into culture on cover slips under presence of the indicated stimulators. After 42 h (at time point t0) they were infected with Listeria and allowed to digest the bacteria during 7 h. Then, cover slips were taken out,  dried and May-Grünwald-Giemsa stained. The number of infected macrophages was counted under the microscope, compared to the infection  rate at t0 and expressed as difference in percentage of infected cells. Error  bars represent standard deviation. Examples for absolute numbers: the  number of infected macrophages at t0 was between 80 and 106/200 for all  strains; the number of infected cells in IFN-γ-stimulated cultures after 7 h  of digestion was 19/200 for wild-type and 168/200 for ICSBP−/− mice.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196174&req=5

Figure 3: Elimination of Listeria from a PEM culture stimulated with LPS, IFN-γ or both. PEM of mice deficient for different IFN-related transcription factors were elicited with starch solution, harvested after 5 d and put into culture on cover slips under presence of the indicated stimulators. After 42 h (at time point t0) they were infected with Listeria and allowed to digest the bacteria during 7 h. Then, cover slips were taken out, dried and May-Grünwald-Giemsa stained. The number of infected macrophages was counted under the microscope, compared to the infection rate at t0 and expressed as difference in percentage of infected cells. Error bars represent standard deviation. Examples for absolute numbers: the number of infected macrophages at t0 was between 80 and 106/200 for all strains; the number of infected cells in IFN-γ-stimulated cultures after 7 h of digestion was 19/200 for wild-type and 168/200 for ICSBP−/− mice.
Mentions: To evaluate listericidal activity of macrophages of the different mutant mouse strains, we tested PEM in an in vitro killing assay. ICSBP−/−, IRF1−/−, and IRF2−/− PEM were elicited by starch injection intraperitoneally, plated onto cover slips and cultured as described in Materials and Methods. After 42 h the cultures were infected with Listeria in vitro, and the number of infected cells determined at time point t0 and after 7 h of infection. The results (Fig. 3) show that PEM of ICSBP−/− and, to a lesser degree, IRF2−/− mice allowed enhanced replication of Listeria, whereas PEM of IRF1−/− and normal mice were able to reduce the bacterial load in these macrophage cultures. Also the number of bacteria per macrophage was higher in ICSBP−/− mice (mostly more than 10 bacteria/cell) compared to their controls (0–4 bacteria/cell), revealing some macrophages with plenty of Listeria and typical comet tails (18). This finding confirms the defect in macrophage effector function, which correlates with the in vivo susceptibility of these mouse strains to Listeria (ICSBP−/− >IRF2−/− >IRF1−/−).

Bottom Line: However, the involved signaling pathways and effector mechanisms are still poorly understood.This correlated with impaired elimination of Listeria from infected peritoneal macrophage (PEM) cultures stimulated with IFN-gamma in vitro; in addition these cultures showed reduced and delayed oxidative burst upon IFN-gamma stimulation, whereas nitric oxide production was normal.These results indicate that (a) the ICSBP/IRF2 complex is essential for IFN-gamma-mediated protection against Listeria and that (b) ROI together with additional still unknown effector mechanisms may be responsible for the anti-Listeria activity of macrophages, whereas IRF1-induced RNI are not limiting.

View Article: PubMed Central - PubMed

Affiliation: Institute of Experimental Immunology, University Hospital, Zürich, Switzerland.

ABSTRACT
Listeria monocytogenes is widely used as a model to study immune responses against intracellular bacteria. It has been shown that neutrophils and macrophages play an important role to restrict bacterial replication in the early phase of primary infection in mice, and that the cytokines interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) are essential for protection. However, the involved signaling pathways and effector mechanisms are still poorly understood. This study investigated mouse strains deficient for the IFN-dependent transcription factors interferon consensus sequence binding protein (ICSBP), interferon regulatory factor (IRF) 1 or 2 for their capacity to eliminate Listeria in vivo and in vitro and for production of inducible reactive nitrogen intermediates (RNI) or reactive oxygen intermediates (ROI) in macrophages. ICSBP-/- and to a lesser degree also IRF2-/- mice were highly susceptible to Listeria infection. This correlated with impaired elimination of Listeria from infected peritoneal macrophage (PEM) cultures stimulated with IFN-gamma in vitro; in addition these cultures showed reduced and delayed oxidative burst upon IFN-gamma stimulation, whereas nitric oxide production was normal. In contrast, mice deficient for IRF1 were not able to produce nitric oxide, but they efficiently controlled Listeria in vivo and in vitro. These results indicate that (a) the ICSBP/IRF2 complex is essential for IFN-gamma-mediated protection against Listeria and that (b) ROI together with additional still unknown effector mechanisms may be responsible for the anti-Listeria activity of macrophages, whereas IRF1-induced RNI are not limiting.

Show MeSH
Related in: MedlinePlus