Guimarães-Pinto K, Nascimento DO, Corrêa-Ferreira A, Morrot A, Freire-de-Lima CG, Lopes MF, DosReis GA, Filardy AA. Trypanosoma cruzi Infection Induces Cellular Stress Response and Senescence-Like Phenotype in Murine Fibroblasts. Front Immunol. 2018 Jul 9;9:1569.
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Trypanosoma cruzi infects and replicates within a wide variety of immune and non-immune cells. Here, we investigated early cellular responses induced in NIH-3T3 fibroblasts upon infection with trypomastigote forms of T. cruzi. We show that fibroblasts were susceptible to T. cruzi infection and started to release trypomastigotes to the culture medium after 4 days of infection. Also, we found that T. cruzi infection reduced the number of fibroblasts in 3-day cell cultures, by altering fibroblast proliferation. Infected fibroblasts displayed distinctive phenotypic alterations, including enlarged and flattened morphology with a nuclei accumulation of senescence-associated heterochromatin foci. In addition, infection induced an overexpression of the enzyme senescence-associated β-galactosidase (SA-β-gal), an activation marker of the cellular senescence program, as well as the production of cytokines and chemokines involved with the senescence-associated secretory phenotype (SASP) such as IL-6, TNF-α, IL-1β, and MCP-1. Infected fibroblasts released increased amounts of stress-associated factors nitric oxide (NO) and reactive oxygen species (ROS), and the treatment with antioxidants deferoxamine (DFO) and N-acetylcysteine reduced ROS generation, secretion of SASP-related cytokine IL-6, SA-β-gal activity, and parasite load by infected fibroblasts. Taken together, our data suggest that T. cruzi infection triggers a rapid cellular stress response followed by induction of a senescent-like phenotype in NIH-3T3 fibroblasts, enabling them to act as reservoirs of parasites during the early stages of the Chagas disease.
Gomes-Neto JF, Sartorius R, Canto FB, Almeida TS, Dias AA, Barbosa CD, Melo GA, Oliveira AC, Aguiar PN, Machado CR, de Matos Guedes HL, Santiago MF, Nóbrega A, De Berardinis P, Bellio M. Vaccination With Recombinant Filamentous fd Phages Against Parasite Infection Requires TLR9 Expression. Front Immunol. 2018 May 29;9:1173.
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Recombinant filamentous fd bacteriophages (rfd) expressing antigenic peptides were shown to induce cell-mediated immune responses in the absence of added adjuvant, being a promising delivery system for vaccination. Here, we tested the capacity of rfd phages to protect against infection with the human protozoan Trypanosoma cruzi, the etiologic agent of Chagas Disease. For this, C57BL/6 (B6) and Tlr9−/− mice were vaccinated with rfd phages expressing the OVA257–264 peptide or the T. cruzi-immunodominant peptides PA8 and TSKB20 and challenged with either the T. cruzi Y-OVA or Y-strain, respectively. We found that vaccination with rfd phages induces anti-PA8 and anti-TSKB20 IgG production, expansion of Ag-specific IFN-γ, TNF-α, and Granzyme B-producing CD8+ T cells, as well as in vivo Ag-specific cytotoxic responses. Moreover, the fd-TSKB20 vaccine was able to protect against mortality induced by a high-dose inoculum of the parasite. Although vaccination with rfd phages successfully reduced both parasitemia and parasite load in the myocardium of WT B6 mice, Tlr9−/− animals were not protected against infection. Thus, our data extend previous studies, demonstrating that rfd phages induce Ag-specific IgG and CD8+ T cell-mediated responses and confer protection against an important human parasite infection, through a TLR9-dependent mechanism.
Pinheiro TM, Mota MTO, Watanabe ASA, Biselli-Périco JM, Drumond BP, Ribeiro MR, Vedovello D, Araújo JP Jr, Pimenta PFP, Chaves BA, Silva MMCD, Batista ICA, Papa MP, Meuren LM, Lucas CGO, Matassoli FL, Gil LHVG, Bozzi A, Calzavara-Silva CE, Arruda LB, Souza DDG, Teixeira MM, Vasilakis N, Nogueira ML. Viral immunogenicity determines epidemiological fitness in a cohort of DENV-1 infection in Brazil. PLoS Negl Trop Dis. 2018 May 29;12(5):e0006525.
DOI: 10.1371/journal.pntd.0006525
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The dynamics of dengue virus (DENV) circulation depends on serotype, genotype and lineage replacement and turnover. In São José do Rio Preto, Brazil, we observed that the L6 lineage of DENV-1 (genotype V) remained the dominant circulating lineage even after the introduction of the L1 lineage. We investigated viral fitness and immunogenicity of the L1 and L6 lineages and which factors interfered with the dynamics of DENV epidemics. The results showed a more efficient replicative fitness of L1 over L6 in mosquitoes and in human and non-human primate cell lines. Infections by the L6 lineage were associated with reduced antigenicity, weak B and T cell stimulation and weak host immune system interactions, which were associated with higher viremia. Our data, therefore, demonstrate that reduced viral immunogenicity and consequent greater viremia determined the increased epidemiological fitness of DENV-1 L6 lineage in São José do Rio Preto.
