title: Interferon alpha/beta and interleukin 12 responses to viral infections: pathways regulating dendritic cell cytokine expression in vivo.
abstract: Interferon (IFN)-alpha/beta and interleukin (IL)-12 are cytokines critical in defense against viruses, but their cellular sources and mechanisms of regulation for in vivo expression remain poorly characterized. The studies presented here identified a novel subset of dendritic cells (DCs) as major producers of the cytokines during murine cytomegalovirus (MCMV) but not lymphocytic choriomeningitis virus (LCMV) infections. These DCs differed from those activated by Toxoplasma antigen but were related to plasmacytoid cells, as assessed by their CD8alpha(+)Ly6G/C(+)CD11b(-) phenotype. Another DC subset (CD8alpha(2)Ly6G/C(-)CD11b(+)) also contributed to IL-12 production in MCMV-infected immunocompetent mice, modestly. However, it dramatically increased IL-12 expression in the absence of IFN-alpha/beta functions. Conversely, IFN-alpha/beta production was greatly reduced under these conditions. Thus, a cross-regulation of DC subset cytokine responses was defined, whereby secretion of type I IFNs by CD8alpha(+) DCs resulted in responses limiting IL-12 expression by CD11b(+) DCs but enhancing overall IFN-alpha/beta production. Taken together, these data indicate that CD8alpha(+)Ly6G/C(+)CD11b(-) DCs play important roles in limiting viral replication and regulating immune responses, through cytokine production, in some but not all viral infections. They also illustrate the plasticity of cellular sources for innate cytokines in vivo and provide new insights into the roles of IFNs in shaping immune responses to viruses.
authors.affiliation: Department of Molecular Microbiology and Immunology, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Dalod
authors.forename: Thais P
authors.initials: TP
authors.lastname: Salazar-Mather
authors.forename: Lene
authors.initials: L
authors.lastname: Malmgaard
authors.forename: Casey
authors.initials: C
authors.lastname: Lewis
authors.forename: Carine
authors.initials: C
authors.lastname: Asselin-Paturel
authors.forename: Francine
authors.initials: F
authors.lastname: Brière
authors.forename: Giorgio
authors.initials: G
authors.lastname: Trinchieri
authors.forename: Christine A
authors.initials: CA
authors.lastname: Biron
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000276:immunology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D016898:Interferon-alpha / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D016899:Interferon-beta / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D018664:Interleukin-12 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D018146:Muromegalovirus / Q000276:immunology*; D017471:Receptors, Interferon / Q000378:metabolism; D050794:STAT1 Transcription Factor; D015398:Signal Transduction; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
chemical_list: D000956:Antigens, Viral; D004268:DNA-Binding Proteins; D016898:Interferon-alpha; D017471:Receptors, Interferon; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse; D015534:Trans-Activators; D018664:Interleukin-12; D016899:Interferon-beta