title: IRF4 and IRF8 Act in CD11c+ Cells To Regulate Terminal Differentiation of Lung Tissue Dendritic Cells.
abstract: Dendritic cells (DCs) initiate immune responses in barrier tissues including lung and skin. Conventional DC (cDC) subsets, CD11b(-) (cDC1s) or CD11b(+) (cDC2s), arise via distinct networks of transcription factors involving IFN regulatory factor 4 (IRF4) and IRF8, and are specialized for unique functional responses. Using mice in which a conditional Irf4 or Irf8 allele is deleted in CD11c(+) cells, we determined whether IRF4 or IRF8 deficiency beginning in CD11c(+) cDC precursors (pre-cDCs) changed the homeostasis of mature DCs or pre-DCs in the lung, dermis, and spleen. CD11c-cre-Irf4(-/-) mice selectively lacked a lung-resident CD11c(hi)CD11b(+)SIRPα(+)CD24(+) DC subset, but not other lung CD11b(+) DCs or alveolar macrophages. Numbers of CD11b(+)CD4(+) splenic DCs, but not CD11b(+) dermal DCs, were reduced, indicating cDC2s in the lung and dermis develop via different pathways. Irf4 deficiency did not alter numbers of cDC1s. CD11c-cre-Irf8(-/-) mice lacked lung-resident CD103(+) DCs and splenic CD8α(+) DCs, yet harbored increased IRF4-dependent DCs. This correlated with a reduced number of Irf8(-/-) pre-cDCs, which contained elevated IRF4, suggesting that Irf8 deficiency diverts pre-cDC fate. Analyses of Irf4 and Irf8 haploinsufficient mice showed that, although one Irf4 allele was sufficient for lung cDC2 development, two functional Irf8 alleles were required for differentiation of lung cDC1s. Thus, IRF8 and IRF4 act in pre-cDCs to direct the terminal differentiation of cDC1 and cDC2 subsets in the lung and spleen. These data suggest that variation in IRF4 or IRF8 levels resulting from genetic polymorphisms or environmental cues will govern tissue DC numbers and, therefore, regulate the magnitude of DC functional responses.
authors.affiliation: Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104.
authors.forename: Sandra
authors.initials: S
authors.lastname: Bajaña
authors.affiliation: Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104.
authors.forename: Sean
authors.identifier: http://orcid.org/0000-0001-9879-0183
authors.initials: S
authors.lastname: Turner
authors.affiliation: Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104.
authors.forename: Jinny
authors.identifier: http://orcid.org/0000-0002-6863-6406
authors.initials: J
authors.lastname: Paul
authors.affiliation: Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104.
authors.forename: Erola
authors.initials: E
authors.lastname: Ainsua-Enrich
authors.affiliation: Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104 Susan-Kovats@omrf.org.
authors.forename: Susan
authors.identifier: http://orcid.org/0000-0001-5479-9952
authors.initials: S
authors.lastname: Kovats
mesh_terms: D000818:Animals; D039521:CD11c Antigen / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology*; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology*; D005434:Flow Cytometry; D007113:Immunity, Innate / Q000276:immunology*; D050835:Interferon Regulatory Factors / Q000276:immunology*; D008168:Lung / Q000166:cytology / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000099185:Interferon Regulatory Factor-8; D000099218:Interferon Regulatory Factor-4
chemical_list: D039521:CD11c Antigen; D050835:Interferon Regulatory Factors; D000099185:Interferon Regulatory Factor-8; D000099218:Interferon Regulatory Factor-4