title: Novel role for the double-stranded RNA-activated protein kinase PKR: modulation of macrophage infection by the protozoan parasite Leishmania.
abstract: The evolution of Leishmania infection depends on the balance between microbicidal and suppressor macrophage functions. Double-stranded RNA (dsRNA)-activated protein kinase R (PKR), a classic antiviral protein, is able to regulate a number of signaling pathways and macrophage functions. We investigated the possible role of PKR in the modulation of Leishmania infection. Our data demonstrated that Leishmania amazonensis infection led to PKR activation and increased PKR levels. Consistently, in macrophages from PKR knockout 129Sv/Ev mice and RAW-264.7 cells stably expressing a dominant-negative (DN) construct of PKR (DN-PKR), L. amazonensis infection was strongly reduced. The treatment of infected macrophages with the synthetic double-stranded RNA poly(I:C), a potent PKR inductor, increased L. amazonensis intracellular proliferation. This effect was reversed by 2-aminopurine (2-AP), a pharmacological inhibitor of PKR, as well as by the expression of DN-PKR. NO release induced by dsRNA treatment was inhibited by L. amazonensis through NF-kappaB modulation. PKR activation induced by dsRNA also resulted in IL-10 production, whose neutralization with specific antibody completely abrogated L. amazonensis proliferation. Our data demonstrated a new role of PKR in protozoan parasitic infection through IL-10 modulation.
authors.affiliation: Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Renata M S
authors.initials: RM
authors.lastname: Pereira
authors.forename: Karina Luiza Dias
authors.initials: KL
authors.lastname: Teixeira
authors.forename: Victor
authors.initials: V
authors.lastname: Barreto-de-Souza
authors.forename: Teresa Cristina
authors.initials: TC
authors.lastname: Calegari-Silva
authors.forename: Luiz D B
authors.initials: LD
authors.lastname: De-Melo
authors.forename: Deivid C
authors.initials: DC
authors.lastname: Soares
authors.forename: Dumith C
authors.initials: DC
authors.lastname: Bou-Habib
authors.forename: Aristóbolo M
authors.initials: AM
authors.lastname: Silva
authors.forename: Elvira M
authors.initials: EM
authors.lastname: Saraiva
authors.forename: Ulisses G
authors.initials: UG
authors.lastname: Lopes
mesh_terms: D015075:2-Aminopurine / Q000494:pharmacology; D000818:Animals; D004789:Enzyme Activation; D006801:Humans; D016753:Interleukin-10 / Q000378:metabolism; D007891:Leishmania / Q000235:genetics / Q000472:pathogenicity*; D008264:Macrophages / Q000469:parasitology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology; D011070:Poly I-C / Q000494:pharmacology; D012330:RNA, Double-Stranded / Q000235:genetics; D019892:eIF-2 Kinase / Q000378:metabolism*
chemical_list: D016328:NF-kappa B; D012330:RNA, Double-Stranded; D016753:Interleukin-10; D009569:Nitric Oxide; D015075:2-Aminopurine; D019892:eIF-2 Kinase; D011070:Poly I-C