title: Human cutaneous leishmaniasis: interferon-dependent expression of double-stranded RNA-dependent protein kinase (PKR) via TLR2.
abstract: We investigated the type I interferon (IFN-1)/PKR axis in the outcome of the Leishmania (Leishmania) amazonensis infection, along with the underlying mechanisms that trigger and sustain this signaling pathway. Reporter assays of cell extracts from RAW-264.7 macrophages infected with L. (L.) amazonensis or HEK-293T cells cotransfected with TLR2 and PKR promoter constructions were employed. Primary macrophages of TLR2-knockout (KO) or IFNR-KO mice were infected, and the levels of PKR, IFN-1, and superoxide dismutase 1 (SOD1) transcript levels were investigated and compared. Immunohistochemical analysis of human biopsy lesions was evaluated for IFN-1 and PKR-positive cells. Leishmania infection increased the expression of PKR and IFN-β on induction of PKR-promoter activity. The observed effects required the engagement of TLR2. TLR2-KO macrophages expressed low IFN-β and PKR levels postinfection with a reduced parasite load. We also revealed the requirement of PKR signaling for Leishmania-induced IFN-1 expression, responsible for sustaining PKR expression and enhancing infection. Moreover, during infection, SOD1 transcripts increased and were also enhanced when IFN-1 was added to the cultures. Remarkably, SOD1 expression was abrogated in infected, dominant-negative PKR-expressing cells. Finally, lesions of patients with anergic diffuse cutaneous leishmaniasis exhibited higher levels of PKR/IFN-1-expressing cells compared to those with single cutaneous leishmaniasis. In summary, we demonstrated the mechanisms and relevance of the IFN-1/PKR axis in the Leishmania infection.
authors.affiliation: Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, RJ, Brazil.
authors.forename: Aislan de Carvalho
authors.initials: Ade C
authors.lastname: Vivarini
authors.forename: Renata de Meirelles Santos
authors.initials: Rde M
authors.lastname: Pereira
authors.forename: Karina Luiza Dias
authors.initials: KL
authors.lastname: Teixeira
authors.forename: Teresa Cristina
authors.initials: TC
authors.lastname: Calegari-Silva
authors.forename: Maria
authors.initials: M
authors.lastname: Bellio
authors.forename: Marcia Dalastra
authors.initials: MD
authors.lastname: Laurenti
authors.forename: Carlos Eduardo Pereira
authors.initials: CE
authors.lastname: Corbett
authors.forename: Cláudia Maria de Castro
authors.initials: CM
authors.lastname: Gomes
authors.forename: Rodrigo Pedro
authors.initials: RP
authors.lastname: Soares
authors.forename: Aristóbolo Mendes
authors.initials: AM
authors.lastname: Silva
authors.forename: Fernando Tobias
authors.initials: FT
authors.lastname: Silveira
authors.forename: Ulisses Gazos
authors.initials: UG
authors.lastname: Lopes
mesh_terms: D000818:Animals; D006028:Glycosphingolipids / Q000276:immunology; D006790:Host-Parasite Interactions; D006801:Humans; D007370:Interferon Type I / Q000378:metabolism*; D007894:Leishmania mexicana / Q000276:immunology / Q000472:pathogenicity; D016773:Leishmaniasis, Cutaneous / Q000201:enzymology* / Q000235:genetics / Q000276:immunology*; D016774:Leishmaniasis, Diffuse Cutaneous / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D017737:Macrophages, Peritoneal / Q000201:enzymology / Q000276:immunology / Q000469:parasitology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008954:Models, Biological; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics; D000072105:Superoxide Dismutase-1; D051195:Toll-Like Receptor 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism*
chemical_list: D006028:Glycosphingolipids; D007370:Interferon Type I; C000606290:SOD1 protein, human; C495342:TLR2 protein, human; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; C008290:lipophosphonoglycan; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D019892:eIF-2 Kinase