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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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Kinetics of cytokine mRNA expression in splenic tissue from T. gondii-infected ICSBP+/+ and ICSBP−/− mice. (A) Splenic tissue was harvested from 4 individual mice at days 0, 3, 5, and 7 after parasite exposure from the same animals studied in Fig. 2. Extracted RNAs were subjected to  quantitative RT-PCR analysis using primers specific for IL-12 p40, IL-12 p35, IFN-γ, IL-10, IL-4, and HPRT genes. (B) RNA from four individual mice  were pooled and levels of TNFα expression were determined by RT-PCR as performed in (A). Similar results were attained in a second experiment.
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Figure 4: Kinetics of cytokine mRNA expression in splenic tissue from T. gondii-infected ICSBP+/+ and ICSBP−/− mice. (A) Splenic tissue was harvested from 4 individual mice at days 0, 3, 5, and 7 after parasite exposure from the same animals studied in Fig. 2. Extracted RNAs were subjected to quantitative RT-PCR analysis using primers specific for IL-12 p40, IL-12 p35, IFN-γ, IL-10, IL-4, and HPRT genes. (B) RNA from four individual mice were pooled and levels of TNFα expression were determined by RT-PCR as performed in (A). Similar results were attained in a second experiment.

Mentions: To evaluate whether the lack of IL-12 p40 production in infected ICSBP−/− mice is attributable to a deficiency in the mRNA expression, semiquantitative RT-PCR was performed to measure levels of transcripts for IL-12 p40 and p35 during parasite infection (Fig. 4). After parasite inoculation, IL-12 p40 mRNA levels remained low in ICSBP−/− mice throughout the 7 d of the experiment, with only minor variation among animals. In contrast, IL-12 p40 mRNA levels were markedly increased in wt mice after infection, reaching maximum levels on days 3 and 5 and declining by day 7. Of note, the levels of mRNA encoding the constitutively expressed IL-12 p35 subunit were comparable between ICSBP−/− and ICSBP+/+ mice before parasite exposure and did not significantly change for 7 d after infection. Consistent with the reduced production of IFN-γ protein (Fig. 2), the IFN-γ transcript levels remained low in the ICSBP−/− spleens, while clearly increasing in tissues from +/+ animals.


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)

Kinetics of cytokine mRNA expression in splenic tissue from T. gondii-infected ICSBP+/+ and ICSBP−/− mice. (A) Splenic tissue was harvested from 4 individual mice at days 0, 3, 5, and 7 after parasite exposure from the same animals studied in Fig. 2. Extracted RNAs were subjected to  quantitative RT-PCR analysis using primers specific for IL-12 p40, IL-12 p35, IFN-γ, IL-10, IL-4, and HPRT genes. (B) RNA from four individual mice  were pooled and levels of TNFα expression were determined by RT-PCR as performed in (A). Similar results were attained in a second experiment.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199126&req=5

Figure 4: Kinetics of cytokine mRNA expression in splenic tissue from T. gondii-infected ICSBP+/+ and ICSBP−/− mice. (A) Splenic tissue was harvested from 4 individual mice at days 0, 3, 5, and 7 after parasite exposure from the same animals studied in Fig. 2. Extracted RNAs were subjected to quantitative RT-PCR analysis using primers specific for IL-12 p40, IL-12 p35, IFN-γ, IL-10, IL-4, and HPRT genes. (B) RNA from four individual mice were pooled and levels of TNFα expression were determined by RT-PCR as performed in (A). Similar results were attained in a second experiment.
Mentions: To evaluate whether the lack of IL-12 p40 production in infected ICSBP−/− mice is attributable to a deficiency in the mRNA expression, semiquantitative RT-PCR was performed to measure levels of transcripts for IL-12 p40 and p35 during parasite infection (Fig. 4). After parasite inoculation, IL-12 p40 mRNA levels remained low in ICSBP−/− mice throughout the 7 d of the experiment, with only minor variation among animals. In contrast, IL-12 p40 mRNA levels were markedly increased in wt mice after infection, reaching maximum levels on days 3 and 5 and declining by day 7. Of note, the levels of mRNA encoding the constitutively expressed IL-12 p35 subunit were comparable between ICSBP−/− and ICSBP+/+ mice before parasite exposure and did not significantly change for 7 d after infection. Consistent with the reduced production of IFN-γ protein (Fig. 2), the IFN-γ transcript levels remained low in the ICSBP−/− spleens, while clearly increasing in tissues from +/+ animals.

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