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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.

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Listeria replication and iNOS expression in the liver after infection with Listeria. ICSBP−/− (D–H), IRF1−/− (L, M), IRF2−/− (N, O), and  control mice (A–C, I, K) were infected with 5 × 103 CFU of Listeria. After 5 or 6 d liver and spleen were taken out. Conventional HE staining (A, D)  and immunohistology for Listeria (B, E, G, I, L, N) and iNOS (C, F, H, K, M, O) was performed using polyclonal primary antibodies. Magnifications:  (A, D), ×35, (B, C, E, F, I–O), ×60 (G, H), ×220.
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Figure 5: Listeria replication and iNOS expression in the liver after infection with Listeria. ICSBP−/− (D–H), IRF1−/− (L, M), IRF2−/− (N, O), and control mice (A–C, I, K) were infected with 5 × 103 CFU of Listeria. After 5 or 6 d liver and spleen were taken out. Conventional HE staining (A, D) and immunohistology for Listeria (B, E, G, I, L, N) and iNOS (C, F, H, K, M, O) was performed using polyclonal primary antibodies. Magnifications: (A, D), ×35, (B, C, E, F, I–O), ×60 (G, H), ×220.

Mentions: The effector mechansim responsible for listericidal properties of macrophages is widely studied and still not clearly defined. ROI (14–19) as well as RNI (20–23) have been proposed to be of major importance. Therefore NO production (measured as nitrite accumulation in culture medium) and respiratory burst upon PMA stimulation (H2O2 production measured by chemiluminescence) were tested in PEM cultures stimulated with LPS and/or IFN-γ as described in Materials and Methods. NO production (Fig. 4 A) was absent in IRF1−/− mice confirming earlier results that iNOS cannot be induced by IFN type I or II combined with LPS and/or TNF in the absence of IRF1 (48, 49). In contrast, iNOS activity was normal in ICSBP−/− and in IRF2−/− mice as well as in G129 mice (50). This finding in IRF2−/− mice differs from recently published results (51). The high susceptibility of the ICSBP−/− and G129 strains to Listeria infection in vivo and in vitro indicates that the NO effector mechanism does not play a limiting role in Listeria clearance. The phenotype of IRF1−/− mice found here is compatible to the published results of Listeria infection in iNOS-deficient mice (23). These mice showed also a slightly enhanced bacterial replication (10–100-fold) and a higher lethality to Listeria infection, but only after injection of 6 × 104 CFU i.v. The LD50 of iNOS-deficient mice was only a factor 10 lower compared to their normal littermates, whereas in the case of ICSBP−/− mice this difference is more than 10,000fold (Table 1; LD50 for C57BL/6 mice is ∼3 × 105 CFU [52]). The fact that iNOS induction in the susceptible strains (ICSBP−/−, IRF2−/−) was higher than in controls (Figs. 4 A, and 5) could even indicate that NO may have a toxic effect on infected cells during murine listeriosis.


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)

Listeria replication and iNOS expression in the liver after infection with Listeria. ICSBP−/− (D–H), IRF1−/− (L, M), IRF2−/− (N, O), and  control mice (A–C, I, K) were infected with 5 × 103 CFU of Listeria. After 5 or 6 d liver and spleen were taken out. Conventional HE staining (A, D)  and immunohistology for Listeria (B, E, G, I, L, N) and iNOS (C, F, H, K, M, O) was performed using polyclonal primary antibodies. Magnifications:  (A, D), ×35, (B, C, E, F, I–O), ×60 (G, H), ×220.
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Related In: Results  -  Collection

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Figure 5: Listeria replication and iNOS expression in the liver after infection with Listeria. ICSBP−/− (D–H), IRF1−/− (L, M), IRF2−/− (N, O), and control mice (A–C, I, K) were infected with 5 × 103 CFU of Listeria. After 5 or 6 d liver and spleen were taken out. Conventional HE staining (A, D) and immunohistology for Listeria (B, E, G, I, L, N) and iNOS (C, F, H, K, M, O) was performed using polyclonal primary antibodies. Magnifications: (A, D), ×35, (B, C, E, F, I–O), ×60 (G, H), ×220.
Mentions: The effector mechansim responsible for listericidal properties of macrophages is widely studied and still not clearly defined. ROI (14–19) as well as RNI (20–23) have been proposed to be of major importance. Therefore NO production (measured as nitrite accumulation in culture medium) and respiratory burst upon PMA stimulation (H2O2 production measured by chemiluminescence) were tested in PEM cultures stimulated with LPS and/or IFN-γ as described in Materials and Methods. NO production (Fig. 4 A) was absent in IRF1−/− mice confirming earlier results that iNOS cannot be induced by IFN type I or II combined with LPS and/or TNF in the absence of IRF1 (48, 49). In contrast, iNOS activity was normal in ICSBP−/− and in IRF2−/− mice as well as in G129 mice (50). This finding in IRF2−/− mice differs from recently published results (51). The high susceptibility of the ICSBP−/− and G129 strains to Listeria infection in vivo and in vitro indicates that the NO effector mechanism does not play a limiting role in Listeria clearance. The phenotype of IRF1−/− mice found here is compatible to the published results of Listeria infection in iNOS-deficient mice (23). These mice showed also a slightly enhanced bacterial replication (10–100-fold) and a higher lethality to Listeria infection, but only after injection of 6 × 104 CFU i.v. The LD50 of iNOS-deficient mice was only a factor 10 lower compared to their normal littermates, whereas in the case of ICSBP−/− mice this difference is more than 10,000fold (Table 1; LD50 for C57BL/6 mice is ∼3 × 105 CFU [52]). The fact that iNOS induction in the susceptible strains (ICSBP−/−, IRF2−/−) was higher than in controls (Figs. 4 A, and 5) could even indicate that NO may have a toxic effect on infected cells during murine listeriosis.

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