Publications by authors named "Claudio P Figueira"

8 Publications

  • Page 1 of 1

Lipophosphoglycan-Deficient Mutants: A Tool to Study Host Cell-Parasite Interplay.

Front Microbiol 2018 5;9:626. Epub 2018 Apr 5.

Laboratory of Inflammation and Biomarkers, Gonçalo Moniz Institut, Oswaldo Cruz Foundation, Salvador, Brazil.

Lipophosphoglycan (LPG) is the major surface glycoconjugate of metacyclic promastigotes and is associated with virulence in various species of this parasite. Here, we generated a LPG-deficient mutant of , the foremost etiologic agent of visceral leishmaniasis in Brazil. The LPG-deficient mutant (Δ) was obtained by homologous recombination and complemented via episomal expression of (Δ + ). Deletion of had no observable effect on parasite morphology or on the presence of subcellular organelles, such as lipid droplets. While both wild-type and add-back parasites reached late phase in axenic cultures, the growth of Δ parasites was delayed. Additionally, the deletion of impaired the outcome of infection in murine bone marrow-derived macrophages. Although no significant differences were observed in parasite load after 4 h of infection, survival of Δ parasites was significantly reduced at 72 h post-infection. Interestingly, . LPG-deficient mutants induced a strong NF-κB-dependent activation of the inducible nitric oxide synthase (iNOS) promoter compared to wild type and Δ + parasites. In conclusion, the Δ mutant constitutes a powerful tool to investigate the role(s) played by LPG in host cell-parasite interactions.
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http://dx.doi.org/10.3389/fmicb.2018.00626DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5896263PMC
April 2018

Zika virus infection induces mitosis abnormalities and apoptotic cell death of human neural progenitor cells.

Sci Rep 2016 12 23;6:39775. Epub 2016 Dec 23.

Gonçalo Moniz Institute, FIOCRUZ, Salvador, Bahia, 40296-710, Brazil.

Zika virus (ZIKV) infection has been associated with severe complications both in the developing and adult nervous system. To investigate the deleterious effects of ZIKV infection, we used human neural progenitor cells (NPC), derived from induced pluripotent stem cells (iPSC). We found that NPC are highly susceptible to ZIKV and the infection results in cell death. ZIKV infection led to a marked reduction in cell proliferation, ultrastructural alterations and induction of autophagy. Induction of apoptosis of Sox2 cells was demonstrated by activation of caspases 3/7, 8 and 9, and by ultrastructural and flow cytometry analyses. ZIKV-induced death of Sox2 cells was prevented by incubation with the pan-caspase inhibitor, Z-VAD-FMK. By confocal microscopy analysis we found an increased number of cells with supernumerary centrosomes. Live imaging showed a significant increase in mitosis abnormalities, including multipolar spindle, chromosome laggards, micronuclei and death of progeny after cell division. FISH analysis for chromosomes 12 and 17 showed increased frequency of aneuploidy, such as monosomy, trisomy and polyploidy. Our study reinforces the link between ZIKV and abnormalities in the developing human brain, including microcephaly.
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http://dx.doi.org/10.1038/srep39775DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5180086PMC
December 2016

Real-Time PCR Reveals Rapid Dissemination of Leptospira interrogans after Intraperitoneal and Conjunctival Inoculation of Hamsters.

Infect Immun 2016 Jul 23;84(7):2105-2115. Epub 2016 Jun 23.

Epidemiology of Microbial Disease Division, Yale School of Public Health, New Haven, Connecticut, USA.

The pathogen Leptospira interrogans is a highly motile spirochete that causes acute and fulminant infections in humans and other accidental hosts. Hematogenous dissemination is important for infection by the pathogen but remains poorly understood because few animal model studies have used sensitive tools to quantify the bacteria. We evaluated the kinetics of leptospiral infection in Golden Syrian hamsters by a sensitive quantitative real-time PCR (TaqMan) with lipl32 as the target gene. The dissemination and bacterial burden were measured after intraperitoneal infection with a high dose (10(8)) or low dose (2.5 × 10(2)) of leptospires. We also examined the conjunctival challenge route to mimic the natural history of infection. Quantification of leptospires in perfused animals revealed that pathogens were detected in all organs of intraperitoneally infected hamsters, including the eye and brain, within 1 h after inoculation of 10(8) virulent L. interrogans bacteria. Peaks of 10(5) to 10(8) leptospires per gram or per milliliter were achieved in blood and all tissues between day 4 and day 8 after intraperitoneal inoculation of high- and low-dose challenges, respectively, coinciding with macroscopic and histological changes. The conjunctival route resulted in a delay in the time to peak organ burden in comparison to intraperitoneal infection, indicating that although infection could be established, penetration efficiency was low across this epithelial barrier. Surprisingly, infection with a large inoculum of high-passage-number attenuated L. interrogans strains resulted in dissemination to all organs in the first 4 days postinfection, albeit with a lower burden, followed by clearance from the blood and organs 7 days postinfection and survival of all animals. These results demonstrate that leptospiral dissemination and tissue invasion occur. In contrast, development of a critical level of tissue burden and pathology are dependent on the virulence of the infecting strain.
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http://dx.doi.org/10.1128/IAI.00094-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4936353PMC
July 2016

A novel flagellar sheath protein, FcpA, determines filament coiling, translational motility and virulence for the Leptospira spirochete.

Mol Microbiol 2016 08 24;101(3):457-70. Epub 2016 May 24.

Department of Epidemiology of Microbial Disease, Yale School of Public Health, New Haven, CT, 06520, USA.

Leptospira are unique among bacteria based on their helical cell morphology with hook-shaped ends and the presence of periplasmic flagella (PF) with pronounced spontaneous supercoiling. The factors that provoke such supercoiling, as well as the role that PF coiling plays in generating the characteristic hook-end cell morphology and motility, have not been elucidated. We have now identified an abundant protein from the pathogen L. interrogans, exposed on the PF surface, and named it Flagellar-coiling protein A (FcpA). The gene encoding FcpA is highly conserved among Leptospira and was not found in other bacteria. fcpA(-) mutants, obtained from clinical isolates or by allelic exchange, had relatively straight, smaller-diameter PF, and were not able to produce translational motility. These mutants lost their ability to cause disease in the standard hamster model of leptospirosis. Complementation of fcpA restored the wild-type morphology, motility and virulence phenotypes. In summary, we identified a novel Leptospira 36-kDa protein, the main component of the spirochete's PF sheath, and a key determinant of the flagella's coiled structure. FcpA is essential for bacterial translational motility and to enable the spirochete to penetrate the host, traverse tissue barriers, disseminate to cause systemic infection and reach target organs.
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http://dx.doi.org/10.1111/mmi.13403DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4979076PMC
August 2016

Acquisition of negative complement regulators by the saprophyte Leptospira biflexa expressing LigA or LigB confers enhanced survival in human serum.

Immunol Lett 2016 05 11;173:61-8. Epub 2016 Mar 11.

Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil. Electronic address:

Leptospiral immunoglobulin-like (Lig) proteins are surface exposed molecules present in pathogenic but not in saprophytic Leptospira species. We have previously shown that Lig proteins interact with the soluble complement regulators Factor H (FH), FH like-1 (FHL-1), FH related-1 (FHR-1) and C4b Binding Protein (C4BP). In this study, we used the saprophyte L. biflexa serovar Patoc as a surrogate host to address the specific role of LigA and LigB proteins in leptospiral complement evasion. L. biflexa expressing LigA or LigB was able to acquire FH and C4BP. Bound complement regulators retained their cofactor activities of FI in the proteolytic cleavage of C3b and C4b. Moreover, heterologous expression of ligA and ligB genes in the saprophyte L. biflexa enhanced bacterial survival in human serum. Complement deposition on lig-transformed L. biflexa was assessed by flow cytometry analysis. With regard to MAC deposition, L. biflexa expressing LigA or LigB presented an intermediate profile: MAC deposition levels were greater than those found in the pathogenic L. interrogans, but lower than those observed for L. biflexa wildtype. In conclusion, Lig proteins contribute to in vitro control of complement activation on the leptospiral surface, promoting an increased bacterial survival in human serum.
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http://dx.doi.org/10.1016/j.imlet.2016.03.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5437552PMC
May 2016

Extracellular vesicles from Leishmania-infected macrophages confer an anti-infection cytokine-production profile to naïve macrophages.

PLoS Negl Trop Dis 2014 Sep 18;8(9):e3161. Epub 2014 Sep 18.

Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Brazil.

Background: Extracellular vesicles (EVs) are structures with phospholipid bilayer membranes and 100-1000 nm diameters. These vesicles are released from cells upon activation of surface receptors and/or apoptosis. The production of EVs by dendritic cells, mast cells, macrophages, and B and T lymphocytes has been extensively reported in the literature. EVs may express MHC class II and other membrane surface molecules and carry antigens. The aim of this study was to investigate the role of EVs from Leishmania-infected macrophages as immune modulatory particles.

Methodology/principal Findings: In this work it was shown that BALB/c mouse bone marrow-derived macrophages, either infected in vitro with Leishmania amazonensis or left uninfected, release comparable amounts of 50-300 nm-diameter extracellular vesicles (EVs). The EVs were characterized by flow cytometry and electron microscopy. The incubation of naïve macrophages with these EVs for 48 hours led to a statistically significant increase in the production of the cytokines IL-12, IL-1β, and TNF-α.

Conclusions/significance: EVs derived from macrophages infected with L. amazonensis induce other macrophages, which in vivo could be bystander cells, to produce the proinflammatory cytokines IL-12, IL-1β and TNF-α. This could contribute both to modulate the immune system in favor of a Th1 immune response and to the elimination of the Leishmania, leading, therefore, to the control the infection.
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http://dx.doi.org/10.1371/journal.pntd.0003161DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169249PMC
September 2014

Anti-Trypanosoma cruzi activity of nicotinamide.

Acta Trop 2012 May 18;122(2):224-9. Epub 2012 Jan 18.

Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Rua Waldemar Falcão, Salvador, BA, Brazil.

Inhibition of Trypanosoma brucei and Leishmania spp. sirtuins has shown promising antiparasitic activity, indicating that these enzymes may be used as targets for drug discovery against trypanosomatid infections. In the present work we carried out a virtual screening focused on the C pocket of Sir2 from Trypanosoma cruzi. Using this approach, the best ligand found was nicotinamide. In vitro tests confirmed the anti-T. cruzi activity of nicotinamide on epimastigote and trypomastigote forms. Moreover, treatment of T. cruzi-infected macrophages with nicotinamide caused a significant reduction in the number of amastigotes. In addition, alterations in the mitochondria and an increase in the vacuolization in the cytoplasm were observed in epimastigotes treated with nicotinamide. Analysis of the complex of Sir2 and nicotinamide revealed the details of the possible ligand-target interaction. Our data reveal a potential use of TcSir2 as a target for anti-T. cruzi drug discovery.
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http://dx.doi.org/10.1016/j.actatropica.2012.01.001DOI Listing
May 2012

An imprint method for detecting leptospires in the hamster model of vaccine-mediated immunity for leptospirosis.

J Med Microbiol 2009 Dec 13;58(Pt 12):1632-1637. Epub 2009 Aug 13.

Department of Biointeraction, Health Sciences Institute, Federal University of Bahia, Salvador, BA, Brazil.

In determining the efficacy of new vaccine candidates for leptospirosis, the primary end point is death and an important secondary end point is sterilizing immunity. However, evaluation of this end point is often hampered by the time-consuming demands and complexity of methods such as culture isolation (CI). In this study, we evaluated the use of an imprint (or touch preparation) method (IM) in detecting the presence of leptospires in tissues of hamsters infected with Leptospira interrogans serovar Copenhageni. In a dissemination study, compared to CI, the IM led to equal or improved detection of leptospires in kidney, liver, lung and blood samples collected post-infection and overall concordance was good (kappa=0.61). Furthermore, in an evaluation of hamsters immunized with a recombinant leptospiral protein-based vaccine candidate and subsequently challenged, the agreement between the CI and IM was very good (kappa=0.84). These findings indicate that the IM is a rapid method for the direct observation of Leptospira spp. that can be readily applied to evaluating infection in experimental animals and determining sterilizing immunity when screening potential vaccine candidates.
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http://dx.doi.org/10.1099/jmm.0.014050-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2887544PMC
December 2009
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