title: In vivo and in vitro Leishmania amazonensis infection induces autophagy in macrophages.
abstract: Autophagy is the primary mechanism of degradation of cellular proteins and at least two functions can be attributed to this biological phenomenon: increased nutrient supply via recycling of the products of autophagy under nutrient starvation; and antimicrobial response involved in the innate immune system. Many microorganisms induce host cell autophagy and it has been proposed as a pathway by which parasites compete with the host cell for limited resources. In this report we provide evidence that the intracellular parasite Leishmania amazonensis induces autophagy in macrophages. Using western blotting, the LC3II protein, a marker of autophagosomes, was detected in cell cultures with a high infection index. Macrophages infected with L. amazonensis were examined by transmission electronic microscopy, which revealed enlarged myelin-like structures typical late autophagosome and autolysosome. Other evidence indicating autophagy was Lysotracker red dye uptake by the macrophages. Autophagy also occurs in the leishmaniasis skin lesions of BALB/c mice, detected by immunohistochemistry with anti-LC3II antibody. In this study, autophagy inhibitor 3-methyladenine (3MA) reduced the infection index, while autophagy inductors, such as rapamycin or starvation, did not alter the infection index in cultivated macrophages, suggesting that one aspect of the role of autophagy could be the provision of nutritive support to the parasite.
authors.affiliation: Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Caixa Postal 6109, Cep 13.083-970, Campinas, São Paulo, Brazil.
authors.forename: Larissa Tavares
authors.initials: LT
authors.lastname: Cyrino
authors.forename: Alexandra Paiva
authors.initials: AP
authors.lastname: Araújo
authors.forename: Paulo Pinto
authors.initials: PP
authors.lastname: Joazeiro
authors.forename: Cristina Pontes
authors.initials: CP
authors.lastname: Vicente
authors.forename: Selma
authors.initials: S
authors.lastname: Giorgio
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000588:Amines / Q000378:metabolism; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000187:drug effects / Q000473:pathology; D002478:Cells, Cultured; D005260:Female; D007894:Leishmania mexicana / Q000187:drug effects / Q000502:physiology*; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology* / Q000473:pathology*; D008264:Macrophages / Q000187:drug effects / Q000469:parasitology* / Q000473:pathology* / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D013194:Staining and Labeling
chemical_list: D000588:Amines; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; C493330:Red DND-99; C025946:3-methyladenine; D000225:Adenine; D020123:Sirolimus