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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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Progression of T. gondii infection in ICSBP−/− versus control  animals. Mice were infected by the i.p. route of infection with 20 ME49  cysts and cumulative mortality monitored. The data shown in (A and B)  are pooled from three independent experiments and involve a total of 14  ICSBP−/−, 15 ICSBP+/+, 14 IL-12 p40 ko and 19 IFN-γ ko animals. (C)  Qualitative analysis of the PEC present in wt (dark grey bars), ICSBP−/−  (black bars), IFN-γ ko (pale grey bars) and IL-12 p40 ko (hatched bars) animals at 5 d after infection with ME49. Cytospin smears of PEC were prepared and stained with Diff-Quik reagent, as described in Materials and  Methods. The percentage of infected cells, large mononuclear cells (LMc;  macrophages, monocytes, and blasting lymphocytes), small mononuclear  cells (SMc; resting lymphocytes), polymorphonuclear cells (PMN) and  eosinophils (Eos) were calculated. Uninfected mice of each of the four  strains did not differ significantly in the composition of their PECs. Values shown are the mean ± SE of 6–12 infected animals per group. Statistically significant differences between the values observed in ICSBP−/−  and wt (*) or ICSBP−/− and both IFN-γ ko−/− and IL-12 p40 ko (**)  samples are indicated (P ⩽0.05).
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Figure 1: Progression of T. gondii infection in ICSBP−/− versus control animals. Mice were infected by the i.p. route of infection with 20 ME49 cysts and cumulative mortality monitored. The data shown in (A and B) are pooled from three independent experiments and involve a total of 14 ICSBP−/−, 15 ICSBP+/+, 14 IL-12 p40 ko and 19 IFN-γ ko animals. (C) Qualitative analysis of the PEC present in wt (dark grey bars), ICSBP−/− (black bars), IFN-γ ko (pale grey bars) and IL-12 p40 ko (hatched bars) animals at 5 d after infection with ME49. Cytospin smears of PEC were prepared and stained with Diff-Quik reagent, as described in Materials and Methods. The percentage of infected cells, large mononuclear cells (LMc; macrophages, monocytes, and blasting lymphocytes), small mononuclear cells (SMc; resting lymphocytes), polymorphonuclear cells (PMN) and eosinophils (Eos) were calculated. Uninfected mice of each of the four strains did not differ significantly in the composition of their PECs. Values shown are the mean ± SE of 6–12 infected animals per group. Statistically significant differences between the values observed in ICSBP−/− and wt (*) or ICSBP−/− and both IFN-γ ko−/− and IL-12 p40 ko (**) samples are indicated (P ⩽0.05).

Mentions: The observation of decreased constitutive levels of IL-12 p40 and IFN-γ mRNA in spleen cells from ICSBP−/− mice (13) suggested that these mice might display increased susceptibility to T. gondii infection. However, we and others have described an association between neutrophil responses and control of infection (40, 41). Since ICSBP−/− animals display a predilection toward neutrophilia (13), the mutation could potentially result in increased rather than decreased resistance to parasite exposure. To assess their susceptibility to T. gondii, ICSBP−/− mice were infected with 20 cysts of the ME49 strain and their survival compared with IFN-γ−/−, IL-12 p40−/−, and ICSBP wt littermates. In agreement with previous reported findings (27, 40), the IFN-γ−/− and IL-12 p40−/− strains succumbed to the infection within 14 d of parasite exposure, while the wt animals survived throughout the 30-d duration of the experiment (Fig. 1, A and B). In contrast to the wt controls, ICSBP−/− mice exhibited an acute mortality pattern comparable to that of IFN-γ−/− and IL-12 p40−/− mice. Enumeration of infected cells in cytospin smears of PECs taken 5 d after parasite exposure revealed numerous cells containing parasites in ICSBP−/− but not wt animals (> 35 versus < 1%, Fig. 1 C). PEC populations from wt controls, IFN-γ−/−, IL-12p40−/−, and ICSBP−/− mice were all similar in composition before infection consisting of 70– 80% large mononuclear cells (LMc), 20-30% small mononuclear cells (SMc), 1–3% PMN, 2–4% eosinophils (Eos), and 1–3% mast cells. At 5 d after infection the number of cells recovered increased from two- to fivefold and the composition of the exudate was significantly different amongst the groups of mice (Fig. 1 C). As compared with the wt animals, exudates from infected ICSBP−/− mice contained a lower percentage of LMc and SMc and the difference was largely attributable to a corresponding increase in PMNs. However, cells from infected IL-12 p40−/− and IFN-γ−/− mice were comparable and contained a greater percentage of SMc and Eos than the exudates from ICSBP−/− 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)

Progression of T. gondii infection in ICSBP−/− versus control  animals. Mice were infected by the i.p. route of infection with 20 ME49  cysts and cumulative mortality monitored. The data shown in (A and B)  are pooled from three independent experiments and involve a total of 14  ICSBP−/−, 15 ICSBP+/+, 14 IL-12 p40 ko and 19 IFN-γ ko animals. (C)  Qualitative analysis of the PEC present in wt (dark grey bars), ICSBP−/−  (black bars), IFN-γ ko (pale grey bars) and IL-12 p40 ko (hatched bars) animals at 5 d after infection with ME49. Cytospin smears of PEC were prepared and stained with Diff-Quik reagent, as described in Materials and  Methods. The percentage of infected cells, large mononuclear cells (LMc;  macrophages, monocytes, and blasting lymphocytes), small mononuclear  cells (SMc; resting lymphocytes), polymorphonuclear cells (PMN) and  eosinophils (Eos) were calculated. Uninfected mice of each of the four  strains did not differ significantly in the composition of their PECs. Values shown are the mean ± SE of 6–12 infected animals per group. Statistically significant differences between the values observed in ICSBP−/−  and wt (*) or ICSBP−/− and both IFN-γ ko−/− and IL-12 p40 ko (**)  samples are indicated (P ⩽0.05).
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Related In: Results  -  Collection

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Figure 1: Progression of T. gondii infection in ICSBP−/− versus control animals. Mice were infected by the i.p. route of infection with 20 ME49 cysts and cumulative mortality monitored. The data shown in (A and B) are pooled from three independent experiments and involve a total of 14 ICSBP−/−, 15 ICSBP+/+, 14 IL-12 p40 ko and 19 IFN-γ ko animals. (C) Qualitative analysis of the PEC present in wt (dark grey bars), ICSBP−/− (black bars), IFN-γ ko (pale grey bars) and IL-12 p40 ko (hatched bars) animals at 5 d after infection with ME49. Cytospin smears of PEC were prepared and stained with Diff-Quik reagent, as described in Materials and Methods. The percentage of infected cells, large mononuclear cells (LMc; macrophages, monocytes, and blasting lymphocytes), small mononuclear cells (SMc; resting lymphocytes), polymorphonuclear cells (PMN) and eosinophils (Eos) were calculated. Uninfected mice of each of the four strains did not differ significantly in the composition of their PECs. Values shown are the mean ± SE of 6–12 infected animals per group. Statistically significant differences between the values observed in ICSBP−/− and wt (*) or ICSBP−/− and both IFN-γ ko−/− and IL-12 p40 ko (**) samples are indicated (P ⩽0.05).
Mentions: The observation of decreased constitutive levels of IL-12 p40 and IFN-γ mRNA in spleen cells from ICSBP−/− mice (13) suggested that these mice might display increased susceptibility to T. gondii infection. However, we and others have described an association between neutrophil responses and control of infection (40, 41). Since ICSBP−/− animals display a predilection toward neutrophilia (13), the mutation could potentially result in increased rather than decreased resistance to parasite exposure. To assess their susceptibility to T. gondii, ICSBP−/− mice were infected with 20 cysts of the ME49 strain and their survival compared with IFN-γ−/−, IL-12 p40−/−, and ICSBP wt littermates. In agreement with previous reported findings (27, 40), the IFN-γ−/− and IL-12 p40−/− strains succumbed to the infection within 14 d of parasite exposure, while the wt animals survived throughout the 30-d duration of the experiment (Fig. 1, A and B). In contrast to the wt controls, ICSBP−/− mice exhibited an acute mortality pattern comparable to that of IFN-γ−/− and IL-12 p40−/− mice. Enumeration of infected cells in cytospin smears of PECs taken 5 d after parasite exposure revealed numerous cells containing parasites in ICSBP−/− but not wt animals (> 35 versus < 1%, Fig. 1 C). PEC populations from wt controls, IFN-γ−/−, IL-12p40−/−, and ICSBP−/− mice were all similar in composition before infection consisting of 70– 80% large mononuclear cells (LMc), 20-30% small mononuclear cells (SMc), 1–3% PMN, 2–4% eosinophils (Eos), and 1–3% mast cells. At 5 d after infection the number of cells recovered increased from two- to fivefold and the composition of the exudate was significantly different amongst the groups of mice (Fig. 1 C). As compared with the wt animals, exudates from infected ICSBP−/− mice contained a lower percentage of LMc and SMc and the difference was largely attributable to a corresponding increase in PMNs. However, cells from infected IL-12 p40−/− and IFN-γ−/− mice were comparable and contained a greater percentage of SMc and Eos than the exudates from ICSBP−/− 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