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Interferon consensus sequence binding protein-deficient mice display impaired resistance to intracellular infection due to a primary defect in interleukin 12 p40 induction.

Scharton-Kersten T, Contursi C, Masumi A, Sher A, Ozato K - J. Exp. Med. (1997)

Bottom Line: Analysis of cytokine synthesis in vitro and in vivo revealed a major deficiency in the expression of both interferon (IFN)-gamma and interleukin (IL)-12 p40 in the T. gondii exposed ICSBP-/- animals.This selective defect in IL-12 p40 production was observed regardless of whether the macrophages had been primed with IFN-gamma.Together these findings implicate ICSBP as a major transcription factor which directly or indirectly regulates IL-12 p40 gene activation and, as a consequence, IFN-gamma-dependent host resistance.

View Article: PubMed Central - PubMed

Affiliation: Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-2753, USA.

ABSTRACT
Mice lacking the transcription factor interferon consensus sequence binding protein (ICSBP), a member of the interferon regulatory factor family of transcription proteins, were infected with the intracellular protozoan, Toxoplasma gondii. ICSBP-deficient mice exhibited unchecked parasite replication in vivo and rapidly succumbed within 14 d after inoculation with an avirulent Toxoplasma strain. In contrast, few intracellular parasites were observed in wild-type littermates and these animals survived for at least 60 d after infection. Analysis of cytokine synthesis in vitro and in vivo revealed a major deficiency in the expression of both interferon (IFN)-gamma and interleukin (IL)-12 p40 in the T. gondii exposed ICSBP-/- animals. In related experiments, macrophages from uninfected ICSBP-/- mice were shown to display a selective impairment in the mRNA expression of IL-12 p40 but not IL-1alpha, IL-1beta, IL-1Ra, IL-6, IL-10, or TNF-alpha in response to live parasites, parasite antigen, lipopolysaccharide, or Staphylococcus aureus. This selective defect in IL-12 p40 production was observed regardless of whether the macrophages had been primed with IFN-gamma. We hypothesize that the impaired synthesis of IL-12 p40 in ICSBP-/- animals is the primary lesion responsible for the loss in resistance to T. gondii because IFN-gamma-induced parasite killing was unimpaired in vitro and, more importantly, administration of exogenous IL-12 in vivo significantly prolonged survival of the infected mice. Together these findings implicate ICSBP as a major transcription factor which directly or indirectly regulates IL-12 p40 gene activation and, as a consequence, IFN-gamma-dependent host resistance.

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ICSBP−/− mice can be stimulated exogenously to control T.  gondii infection in vitro (A) and in vivo (B). (A) PECs were collected from  naive mice (resident) or from animals injected i.p. with thioglycollate 5 d  prior (thioglycollate elicited). Cells were pretreated with murine IFN-γ  for 2 h. Cultures were infected with 0.2 RH tachyzoites per cell, pulsed  24 h later with [3H]uracil, and cultured overnight. Incorporated radioactivity was determined and expressed as mean CPM for triplicate cultures.  Percentage killing is indicated above the bar for IFN-γ–treated cultures  and was calculated using the formula indicated in Materials and Methods.  Comparable results were observed in two additional experiments. (B)  Survival was compared in ICSBP−/− mice that were treated with PBS (10  mice per group) or rIL-12 (0.5 μg, 13 mice per group) over the first 5 d  of infection. The results shown are pooled from two experiments.
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Figure 7: ICSBP−/− mice can be stimulated exogenously to control T. gondii infection in vitro (A) and in vivo (B). (A) PECs were collected from naive mice (resident) or from animals injected i.p. with thioglycollate 5 d prior (thioglycollate elicited). Cells were pretreated with murine IFN-γ for 2 h. Cultures were infected with 0.2 RH tachyzoites per cell, pulsed 24 h later with [3H]uracil, and cultured overnight. Incorporated radioactivity was determined and expressed as mean CPM for triplicate cultures. Percentage killing is indicated above the bar for IFN-γ–treated cultures and was calculated using the formula indicated in Materials and Methods. Comparable results were observed in two additional experiments. (B) Survival was compared in ICSBP−/− mice that were treated with PBS (10 mice per group) or rIL-12 (0.5 μg, 13 mice per group) over the first 5 d of infection. The results shown are pooled from two experiments.

Mentions: To determine whether the ICSBP−/− lesion also influences effector functions downstream from the defect in IL-12 p40 induction, we assessed the ability of IFN-γ–activated macrophage populations from ICSBP mutant animals to restrict the growth of T. gondii in vitro as measured by incorporation of [3H]uracil, a nucleotide preferentially used by the parasite. Unactivated cells from either wt or ICSBP−/− mice exhibited a 50–80-fold increase in nucleotide incorporation after infection with tachyzoites (0.2/cell) and addition of IFN-γ dramatically reduced tachyzoite proliferation in cultures from both mouse strains. Similar results were obtained using thioglycollate-elicited or resident macrophage-enriched populations (Fig. 7 A).


Interferon consensus sequence binding protein-deficient mice display impaired resistance to intracellular infection due to a primary defect in interleukin 12 p40 induction.

Scharton-Kersten T, Contursi C, Masumi A, Sher A, Ozato K - J. Exp. Med. (1997)

ICSBP−/− mice can be stimulated exogenously to control T.  gondii infection in vitro (A) and in vivo (B). (A) PECs were collected from  naive mice (resident) or from animals injected i.p. with thioglycollate 5 d  prior (thioglycollate elicited). Cells were pretreated with murine IFN-γ  for 2 h. Cultures were infected with 0.2 RH tachyzoites per cell, pulsed  24 h later with [3H]uracil, and cultured overnight. Incorporated radioactivity was determined and expressed as mean CPM for triplicate cultures.  Percentage killing is indicated above the bar for IFN-γ–treated cultures  and was calculated using the formula indicated in Materials and Methods.  Comparable results were observed in two additional experiments. (B)  Survival was compared in ICSBP−/− mice that were treated with PBS (10  mice per group) or rIL-12 (0.5 μg, 13 mice per group) over the first 5 d  of infection. The results shown are pooled from two experiments.
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Figure 7: ICSBP−/− mice can be stimulated exogenously to control T. gondii infection in vitro (A) and in vivo (B). (A) PECs were collected from naive mice (resident) or from animals injected i.p. with thioglycollate 5 d prior (thioglycollate elicited). Cells were pretreated with murine IFN-γ for 2 h. Cultures were infected with 0.2 RH tachyzoites per cell, pulsed 24 h later with [3H]uracil, and cultured overnight. Incorporated radioactivity was determined and expressed as mean CPM for triplicate cultures. Percentage killing is indicated above the bar for IFN-γ–treated cultures and was calculated using the formula indicated in Materials and Methods. Comparable results were observed in two additional experiments. (B) Survival was compared in ICSBP−/− mice that were treated with PBS (10 mice per group) or rIL-12 (0.5 μg, 13 mice per group) over the first 5 d of infection. The results shown are pooled from two experiments.
Mentions: To determine whether the ICSBP−/− lesion also influences effector functions downstream from the defect in IL-12 p40 induction, we assessed the ability of IFN-γ–activated macrophage populations from ICSBP mutant animals to restrict the growth of T. gondii in vitro as measured by incorporation of [3H]uracil, a nucleotide preferentially used by the parasite. Unactivated cells from either wt or ICSBP−/− mice exhibited a 50–80-fold increase in nucleotide incorporation after infection with tachyzoites (0.2/cell) and addition of IFN-γ dramatically reduced tachyzoite proliferation in cultures from both mouse strains. Similar results were obtained using thioglycollate-elicited or resident macrophage-enriched populations (Fig. 7 A).

Bottom Line: Analysis of cytokine synthesis in vitro and in vivo revealed a major deficiency in the expression of both interferon (IFN)-gamma and interleukin (IL)-12 p40 in the T. gondii exposed ICSBP-/- animals.This selective defect in IL-12 p40 production was observed regardless of whether the macrophages had been primed with IFN-gamma.Together these findings implicate ICSBP as a major transcription factor which directly or indirectly regulates IL-12 p40 gene activation and, as a consequence, IFN-gamma-dependent host resistance.

View Article: PubMed Central - PubMed

Affiliation: Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-2753, USA.

ABSTRACT
Mice lacking the transcription factor interferon consensus sequence binding protein (ICSBP), a member of the interferon regulatory factor family of transcription proteins, were infected with the intracellular protozoan, Toxoplasma gondii. ICSBP-deficient mice exhibited unchecked parasite replication in vivo and rapidly succumbed within 14 d after inoculation with an avirulent Toxoplasma strain. In contrast, few intracellular parasites were observed in wild-type littermates and these animals survived for at least 60 d after infection. Analysis of cytokine synthesis in vitro and in vivo revealed a major deficiency in the expression of both interferon (IFN)-gamma and interleukin (IL)-12 p40 in the T. gondii exposed ICSBP-/- animals. In related experiments, macrophages from uninfected ICSBP-/- mice were shown to display a selective impairment in the mRNA expression of IL-12 p40 but not IL-1alpha, IL-1beta, IL-1Ra, IL-6, IL-10, or TNF-alpha in response to live parasites, parasite antigen, lipopolysaccharide, or Staphylococcus aureus. This selective defect in IL-12 p40 production was observed regardless of whether the macrophages had been primed with IFN-gamma. We hypothesize that the impaired synthesis of IL-12 p40 in ICSBP-/- animals is the primary lesion responsible for the loss in resistance to T. gondii because IFN-gamma-induced parasite killing was unimpaired in vitro and, more importantly, administration of exogenous IL-12 in vivo significantly prolonged survival of the infected mice. Together these findings implicate ICSBP as a major transcription factor which directly or indirectly regulates IL-12 p40 gene activation and, as a consequence, IFN-gamma-dependent host resistance.

Show MeSH
Related in: MedlinePlus