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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  synthesis in infected wt (open  squares) and ko (solid circle) animals. Serum, PECs, and spleen  tissue were harvested from  ICSBP−/− and ICSBP+/+ mice  on days 0, 3, 5, and 7 after i.p.  infection with ME49. IFN-γ (A)  and IL-12 p40 (B) levels were  measured by ELISA in diluted  sera or in 72-h culture supernatants of single-cell suspensions as  described in Materials and Methods.  Data points are the mean ± SE  for four individual mice. An asterisk indicates a statistically significant difference (P <0.05 by  Student's t test) between the values observed in ICSBP−/− and  ICSBP+/+ samples. The experiment shown is representative of  three performed.
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Figure 2: Kinetics of cytokine synthesis in infected wt (open squares) and ko (solid circle) animals. Serum, PECs, and spleen tissue were harvested from ICSBP−/− and ICSBP+/+ mice on days 0, 3, 5, and 7 after i.p. infection with ME49. IFN-γ (A) and IL-12 p40 (B) levels were measured by ELISA in diluted sera or in 72-h culture supernatants of single-cell suspensions as described in Materials and Methods. Data points are the mean ± SE for four individual mice. An asterisk indicates a statistically significant difference (P <0.05 by Student's t test) between the values observed in ICSBP−/− and ICSBP+/+ samples. The experiment shown is representative of three performed.

Mentions: The rapid development of fulminant infection in ICSBP−/− mice and their subsequent mortality within the first 2 wk of parasite exposure suggested that induction of IFN-γ synthesis might be defective in these animals. To investigate this hypothesis, IFN-γ levels were compared in ICSBP−/− and ICSBP+/+ mice at different times during the first week of T. gondii infection. Wt mice displayed a characteristic elevation in IFN-γ protein as measured directly in the serum and in cultures of cells from the peritoneum and spleen (Fig. 2 A). In contrast, IFN-γ levels did not increase in ICSBP−/− mice at any of the time points analyzed (Fig. 2 A), and addition of STAg to the cultures failed to amplify the production of cytokine (data not shown).


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  synthesis in infected wt (open  squares) and ko (solid circle) animals. Serum, PECs, and spleen  tissue were harvested from  ICSBP−/− and ICSBP+/+ mice  on days 0, 3, 5, and 7 after i.p.  infection with ME49. IFN-γ (A)  and IL-12 p40 (B) levels were  measured by ELISA in diluted  sera or in 72-h culture supernatants of single-cell suspensions as  described in Materials and Methods.  Data points are the mean ± SE  for four individual mice. An asterisk indicates a statistically significant difference (P <0.05 by  Student's t test) between the values observed in ICSBP−/− and  ICSBP+/+ samples. The experiment shown is representative of  three performed.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199126&req=5

Figure 2: Kinetics of cytokine synthesis in infected wt (open squares) and ko (solid circle) animals. Serum, PECs, and spleen tissue were harvested from ICSBP−/− and ICSBP+/+ mice on days 0, 3, 5, and 7 after i.p. infection with ME49. IFN-γ (A) and IL-12 p40 (B) levels were measured by ELISA in diluted sera or in 72-h culture supernatants of single-cell suspensions as described in Materials and Methods. Data points are the mean ± SE for four individual mice. An asterisk indicates a statistically significant difference (P <0.05 by Student's t test) between the values observed in ICSBP−/− and ICSBP+/+ samples. The experiment shown is representative of three performed.
Mentions: The rapid development of fulminant infection in ICSBP−/− mice and their subsequent mortality within the first 2 wk of parasite exposure suggested that induction of IFN-γ synthesis might be defective in these animals. To investigate this hypothesis, IFN-γ levels were compared in ICSBP−/− and ICSBP+/+ mice at different times during the first week of T. gondii infection. Wt mice displayed a characteristic elevation in IFN-γ protein as measured directly in the serum and in cultures of cells from the peritoneum and spleen (Fig. 2 A). In contrast, IFN-γ levels did not increase in ICSBP−/− mice at any of the time points analyzed (Fig. 2 A), and addition of STAg to the cultures failed to amplify the production of cytokine (data not shown).

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