title: Tolerogenic Plasmacytoid Dendritic Cells Control Paracoccidioides brasiliensis Infection by Inducting Regulatory T Cells in an IDO-Dependent Manner.
abstract: Plasmacytoid dendritic cells (pDCs), considered critical for immunity against viruses, were recently associated with defense mechanisms against fungal infections. However, the immunomodulatory function of pDCs in pulmonary paracoccidiodomycosis (PCM), an endemic fungal infection of Latin America, has been poorly defined. Here, we investigated the role of pDCs in the pathogenesis of PCM caused by the infection of 129Sv mice with 1 x 106 P. brasiliensis-yeasts. In vitro experiments showed that P. brasiliensis infection induces the maturation of pDCs and elevated synthesis of TNF-α and IFN-β. The in vivo infection caused a significant influx of pDCs to the lungs and increased levels of pulmonary type I IFN. Depletion of pDCs by a specific monoclonal antibody resulted in a less severe infection, reduced tissue pathology and increased survival time of infected mice. An increased influx of macrophages and neutrophils and elevated presence of CD4+ and CD8+ T lymphocytes expressing IFN-γ and IL-17 in the lungs of pDC-depleted mice were also observed. These findings were concomitant with decreased frequency of Treg cells and reduced levels of immunoregulatory cytokines such as IL-10, TGF-β, IL-27 and IL-35. Importantly, P. brasilienis infection increased the numbers of pulmonary pDCs expressing indoleamine 2,3-dioxygenase-1 (IDO), an enzyme with immunoregulatory properties, that were reduced following pDC depletion. In agreement, an increased immunogenic activity of infected pDCs was observed when IDO-deficient or IDO-inhibited pDCs were employed in co-cultures with lymphocytes Altogether, our results suggest that in pulmonary PCM pDCs exert a tolerogenic function by an IDO-mediated mechanism that increases Treg activity.
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Eliseu Frank de
authors.initials: EF
authors.lastname: Araújo
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Daniella Helena
authors.initials: DH
authors.lastname: Medeiros
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Nayane Alves de Lima
authors.identifier: http://orcid.org/0000-0003-4723-5969
authors.initials: NA
authors.lastname: Galdino
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Antônio
authors.initials: A
authors.lastname: Condino-Neto
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Vera Lúcia Garcia
authors.initials: VL
authors.lastname: Calich
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Flávio Vieira
authors.initials: FV
authors.lastname: Loures
mesh_terms: D000818:Animals; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology*; D004195:Disease Models, Animal; D005434:Flow Cytometry; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000276:immunology*; D008172:Lung Diseases, Fungal / Q000276:immunology; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010228:Paracoccidioides / Q000276:immunology; D010229:Paracoccidioidomycosis / Q000276:immunology*; D060888:Real-Time Polymerase Chain Reaction; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase