title: Cutting edge: MyD88 is required for resistance to Toxoplasma gondii infection and regulates parasite-induced IL-12 production by dendritic cells.
abstract: Host resistance to the intracellular protozoan Toxoplasma gondii is highly dependent on early IL-12 production by APC. We demonstrate here that both host resistance and T. gondii-induced IL-12 production are dramatically reduced in mice lacking the adaptor molecule MyD88, an important signaling element used by Toll-like receptor (TLR) family members. Infection of MyD88-deficient mice with T. gondii resulted in uncontrolled parasite replication and greatly reduced plasma IL-12 levels. Defective IL-12 responses to T. gondii Ags (soluble tachyzoite Ag (STAg)) were observed in MyD88(-/-) peritoneal macrophages, neutrophils, and splenic dendritic cells (DC). In contrast, DC from TLR2- or TLR4-deficient animals developed normal IL-12 responses to STAg. In vivo treatment with pertussis toxin abolished the residual IL-12 response displayed by STAg-stimulated DC from MyD88(-/-) mice. Taken together, these data suggest that the induction of IL-12 by T. gondii depends on a unique mechanism involving both MyD88 and G protein-coupled signaling pathways.
authors.affiliation: Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA. cscanga@niaid.nih.gov
authors.forename: Charles A
authors.initials: CA
authors.lastname: Scanga
authors.forename: Julio
authors.initials: J
authors.lastname: Aliberti
authors.forename: Dragana
authors.initials: D
authors.lastname: Jankovic
authors.forename: Florence
authors.initials: F
authors.lastname: Tilloy
authors.forename: Soumaya
authors.initials: S
authors.lastname: Bennouna
authors.forename: Eric Y
authors.initials: EY
authors.lastname: Denkers
authors.forename: Ruslan
authors.initials: R
authors.lastname: Medzhitov
authors.forename: Alan
authors.initials: A
authors.lastname: Sher
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000502:physiology*; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism* / Q000469:parasitology; D029721:Drosophila Proteins; D005260:Female; D007113:Immunity, Innate / Q000235:genetics; D007371:Interferon-gamma / Q000096:biosynthesis / Q000172:deficiency; D018664:Interleukin-12 / Q000096:biosynthesis* / Q000172:deficiency; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000378:metabolism / Q000469:parasitology; D008297:Male; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism / Q000469:parasitology; D019713:Receptors, CCR5 / Q000502:physiology; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000502:physiology; D011971:Receptors, Immunologic / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014122:Toxoplasma / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000235:genetics / Q000276:immunology* / Q000401:mortality / Q000469:parasitology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D029721:Drosophila Proteins; D008562:Membrane Glycoproteins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D019713:Receptors, CCR5; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D018664:Interleukin-12; D007371:Interferon-gamma