title: In situ TLR2 and TLR4 expression in a murine model of mycetoma caused by Nocardia brasiliensis.
abstract: Actinomycetoma caused by Nocardia brasiliensis is a common disease in tropical regions. This ailment is characterized by a localized chronic inflammation that mainly affects the lower limbs. Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns, inducing the production of proinflammatory mediators. The role of TLRs in the immune response against N. brasiliensis is unknown. The aim of this work was to locate and quantify in a murine model the expression of TLR2 and TLR4 in the infection site using reverse transcription-PCR and immunohistochemistry. The results showed that TLR2 expression increased in the infected tissue, whereas TLR4 expression decreased. The presence of TLR2 and TLR4 was demonstrated in different cell populations throughout the chronic infectious process. In the early stages of this process, TLR2 was expressed in neutrophils and macrophages in direct contact with the inoculum, whereas TLR4 was observed in mast cells. In the advanced stages of the infection, TLR2 was expressed in foam cells and fibroblasts and was likely associated with bacterial containment, while TLR4 was downregulated, probably resulting in an imbalance between the host immune response and the bacterial load that favoured chronic disease.
authors.affiliation: Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, México DF, Mexico.
authors.forename: Blanca Edith
authors.initials: BE
authors.lastname: Millán-Chiu
authors.forename: Francisca
authors.initials: F
authors.lastname: Hernández-Hernández
authors.forename: Armando
authors.initials: A
authors.lastname: Pérez-Torres
authors.forename: Luis Javier
authors.initials: LJ
authors.lastname: Méndez-Tovar
authors.forename: Rubén
authors.initials: R
authors.lastname: López-Martínez
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005347:Fibroblasts / Q000276:immunology; D005487:Foam Cells / Q000276:immunology; D020869:Gene Expression Profiling; D008264:Macrophages / Q000276:immunology; D008297:Male; D008407:Mast Cells / Q000276:immunology; D051379:Mice; D008271:Mycetoma / Q000276:immunology* / Q000382:microbiology* / Q000473:pathology; D009504:Neutrophils / Q000276:immunology; D009615:Nocardia / Q000276:immunology* / Q000472:pathogenicity*; D051195:Toll-Like Receptor 2 / Q000096:biosynthesis*; D051197:Toll-Like Receptor 4 / Q000096:biosynthesis*
chemical_list: C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4