title: Interferon consensus sequence binding protein-deficient mice display impaired resistance to intracellular infection due to a primary defect in interleukin 12 p40 induction.
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.
authors.affiliation: Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-2753, USA.
authors.forename: T
authors.initials: T
authors.lastname: Scharton-Kersten
authors.forename: C
authors.initials: C
authors.lastname: Contursi
authors.forename: A
authors.initials: A
authors.lastname: Masumi
authors.forename: A
authors.initials: A
authors.lastname: Sher
authors.forename: K
authors.initials: K
authors.lastname: Ozato
mesh_terms: D000208:Acute Disease; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000276:immunology; D016384:Consensus Sequence / Q000276:immunology; D005260:Female; D007113:Immunity, Innate / Q000235:genetics; D050835:Interferon Regulatory Factors; D007371:Interferon-gamma / Q000096:biosynthesis / Q000494:pharmacology; D018664:Interleukin-12 / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics / Q000494:pharmacology; D017737:Macrophages, Peritoneal / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins; D013154:Spleen / Q000276:immunology / Q000378:metabolism / Q000469:parasitology; D014122:Toxoplasma / Q000254:growth & development / Q000276:immunology; D014124:Toxoplasmosis, Animal / Q000235:genetics* / Q000276:immunology* / Q000469:parasitology; D014157:Transcription Factors / Q000172:deficiency* / Q000235:genetics; D014158:Transcription, Genetic; D000099185:Interferon Regulatory Factor-8
chemical_list: D002352:Carrier Proteins; D050835:Interferon Regulatory Factors; D007371:Interferon-gamma; D018664:Interleukin-12; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; D000099185:Interferon Regulatory Factor-8