title: MyD88 is dispensable for resistance to Paracoccidioides brasiliensis in a murine model of blood-borne disseminated infection.
abstract: We have studied the role of MyD88, an adaptor protein of Toll-like receptors (TLRs), in murine defenses against Paracoccidioides brasiliensis in a model of blood-borne disseminated infection. Wild-type (WT) and MyD88-deficient mice infected intravenously with P. brasiliensis yeast cells showed an equivalent fungal burden, as well as similar levels of proinflammatory IL-1beta, IL-6, IL-12p70, tumor necrosis factor (TNF)-alpha and MIP-2, T-helper type 1 (Th1) (IFN-gamma) and Th2 cytokines (IL-4) in tissue homogenates. In vitro production of TNF-alpha, IFN-gamma and IL-12p70, by antigen-stimulated splenocytes from infected animals, was also similar in both types of mice; this production of Th1 cytokines correlated with a similar frequency of IFN-gamma-producing CD4 T cells. Recruitment of neutrophils to the peritoneal cavity of intraperitoneally infected mice was not affected in TLR2-/-, TLR4-/- as compared with WT mice, but significantly decreased in MyD88-deficient mice. In vitro production of TNF-alpha by peritoneal macrophages from MyD88-, TLR2- and TLR4-deficient mice in response to P. brasiliensis yeasts was undiminished, as compared with macrophages from WT mice, and, in addition, laminarin failed to inhibit production of TNF-alpha by WT and MyD88-deficient macrophages. Overall, these data suggest that the response to P. brasiliensis yeasts occurs independently of the adaptor molecule MyD88, and indicate that TLR2, TLR4 and dectin-1 do not play a significant role in recognition of P. brasiliensis yeast cells.
authors.affiliation: Escuela de Microbiología, Universidad de Antioquia, Medellín, Colombia.
authors.forename: Angel
authors.initials: A
authors.lastname: González
authors.forename: Alberto
authors.initials: A
authors.lastname: Yáñez
authors.forename: Daniel
authors.initials: D
authors.lastname: Gozalbo
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Gil
mesh_terms: D000818:Animals; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D016469:Fungemia / Q000276:immunology* / Q000382:microbiology; D006801:Humans; D037181:Lectins, C-Type; D017737:Macrophages, Peritoneal / Q000276:immunology / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D010228:Paracoccidioides / Q000472:pathogenicity*; D010229:Paracoccidioidomycosis / Q000276:immunology* / Q000382:microbiology; D018417:Th1 Cells / Q000276:immunology; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism; D000099181:Dectin-1
chemical_list: D016207:Cytokines; D037181:Lectins, C-Type; D008565:Membrane Proteins; D053594:Myeloid Differentiation Factor 88; D009419:Nerve Tissue Proteins; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D000099181:Dectin-1