title: New insights into the immunopathology of early Toxocara canis infection in mice.
abstract: BACKGROUND
  Nematodes of the genus Toxocara are cosmopolitan roundworms frequently found in dogs and cats. Toxocara spp. can accidentally infect humans and cause a zoonosis called human toxocariasis, which is characterized by visceral, ocular or cerebral migration of larval stages of the parasite, without completing its life cycle. In general, chronic nematode infections induce a polarized TH2 immune response. However, during the initial phase of infection, a strong pro-inflammatory response is part of the immunological profile and might determine the outcome and/or pathology of the infection.
  
  
  METHODS
  Parasitological aspects and histopathology during larval migration were evaluated after early T. canis experimental infection of BALB/c mice, which were inoculated via the intra-gastric route with a single dose of 1000 fully embryonated eggs. Innate immune responses and systemic cytokine patterns (TH1, TH2, TH17 and regulatory cytokines) were determined at different times after experimental challenge by sandwich ELISA.
  
  
  RESULTS
  We found that experimental infection with T. canis induced a mix of innate inflammatory/TH17/TH2 responses during early infection, with a predominance of the latter. The TH2 response was evidenced by significant increases in cytokines such as IL-4, IL-5, IL-13 and IL-33, in addition to increasing levels of IL-6 and IL-17. No significant increases were observed for IL-10, TNF-α or IFN-γ levels. In parallel, parasitological analysis clearly revealed the pattern of larval migration through the mouse organs, starting from the liver in the first 24 h of infection, reaching the peak in the lungs on the 3rd day of infection and finally being found numerously in the brain after 5 days of infection. Peripheral leukocytosis, characterized by early neutrophilia and subsequent eosinophilia, was remarkable during early infection. The tissue damage induced by larvae was evidenced by histopathological analysis of the organs at different time points of infection. In all of the affected organs, larval migration induced intense inflammatory infiltrate and hemorrhage.
  
  
  CONCLUSIONS
  In conclusion, these new insights into early T. canis infection in mice presented here enabled a better understanding of the immunopathological events that might also occur during human toxocariasis, thus contributing to future strategies of diagnosis and control.
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. nathy_resende@yahoo.com.br.|Laboratório de Fisiologia de Sistemas e Toxicologia Reprodutiva, Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso, Barra do Garças, Brazil. nathy_resende@yahoo.com.br.
authors.forename: Nathália M
authors.initials: NM
authors.lastname: Resende
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. pedrogazzinelli@yahoo.com.br.
authors.forename: Pedro Henrique
authors.initials: PH
authors.lastname: Gazzinelli-Guimarães
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. fernandosergioba@gmail.com.
authors.forename: Fernando S
authors.initials: FS
authors.lastname: Barbosa
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. luliz_maria@yahoo.com.br.
authors.forename: Luciana M
authors.initials: LM
authors.lastname: Oliveira
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. denisesnogueira@gmail.com.
authors.forename: Denise S
authors.initials: DS
authors.lastname: Nogueira
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. aninhaguimaraes2@hotmail.com.
authors.forename: Ana Clara
authors.initials: AC
authors.lastname: Gazzinelli-Guimarães
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. marcotpg8@hotmail.com.
authors.forename: Marco Túlio P
authors.initials: MT
authors.lastname: Gonçalves
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. chiaramorim@hotmail.com.
authors.forename: Chiara C O
authors.initials: CC
authors.lastname: Amorim
authors.affiliation: Departamento de Patologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. fabriciom19@yahoo.com.br.
authors.forename: Fabrício M S
authors.initials: FM
authors.lastname: Oliveira
authors.affiliation: Departamento de Patologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. caliari@icb.ufmg.br.
authors.forename: Marcelo V
authors.initials: MV
authors.lastname: Caliari
authors.affiliation: Departamento de Patologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. milenerachid@icb.ufmg.br.
authors.forename: Milene A
authors.initials: MA
authors.lastname: Rachid
authors.affiliation: Laboratório de Fisiologia de Sistemas e Toxicologia Reprodutiva, Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Mato Grosso, Barra do Garças, Brazil. gtvolpato@yahoo.com.
authors.forename: Gustavo T
authors.initials: GT
authors.lastname: Volpato
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. lilianlacerdabueno@hotmail.com.
authors.forename: Lilian L
authors.initials: LL
authors.lastname: Bueno
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. stefan.geiger76@gmail.com.
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Geiger
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. fujiwara@icb.ufmg.br.
authors.forename: Ricardo T
authors.initials: RT
authors.lastname: Fujiwara
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D020381:Interleukin-17 / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D015848:Interleukin-5 / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D058504:Th17 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology; D017166:Toxocara canis / Q000502:physiology*; D014120:Toxocariasis / Q000276:immunology* / Q000469:parasitology* / Q000473:pathology
chemical_list: D020381:Interleukin-17; D015848:Interleukin-5; D015847:Interleukin-4