Browsing by Author "Segatto, Marcela"

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    Leishmania major self-limited infection increases blood cholesterol and promotes atherosclerosis development.
    (2013) Fernandes, Luciana Rodrigues; Ribeiro, Ana Cecília de Castro; Segatto, Marcela; Santos, Luís Felipe F. F.; Amaral, Joana Ferreira do; Portugal, Luciane Rodrigues; Leite, Jacqueline Isaura Alvarez
    Leishmania major infection of resistant mice causes a self-limited lesion characterized by macrophage activation and a Th1 proinflammatory response. Atherosclerosis is an inflammatory disease involving hypercholesterolemia and macrophage activation. In this study, we evaluated the influence of L. major infection on the development of atherosclerosis using atherosclerosissusceptible apolipoprotein E-deficient (apoE KO) mice. After 6 weeks of infection, apoE KO mice exhibited reduced footpad swelling and parasitemia similar to C57BL/6 controls, confirming that both strains are resistant to infection with L.major. L.majorinfected mice had increased plasma cholesterol levels and reduced triacylglycerols. With regard to atherosclerosis, noninfected mice developed only fatty streak lesions, while the infected mice presented with advanced lesions containing a necrotic core and an abundant inflammatory infiltrate. CD36 expression was increased in the aortic valve of the infected mice, indicating increased macrophage activation. In conclusion, L. major infection, although localized and self-limited in resistant apoE KO mice, has a detrimental effect on the blood lipid profile, increases the inflammatory cell migration to atherosclerotic lesions, and promotes atherogenesis.These effects are consequences of the stimulation of the immune system by L. major, which promotes the inflammatory components of atherosclerosis, which are primarily the parasite-activated macrophages.
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    Unequivocal identification of subpopulations in putative multiclonal Trypanosoma cruzi strains by FACs single cell sorting and genotyping.
    (2012) Valadares, Helder Magno Silva; Pimenta, Juliana Ramos; Segatto, Marcela; Veloso, Vanja Maria; Gomes, Mônica Lúcia; Chiari, Egler; Gollob, Kenneth John; Bahia, Maria Terezinha; Lana, Marta de; Franco, Glória Regina; Machado, Carlos Renato; Pena, Sérgio Danilo Junho; Macedo, Andréa Mara
    Trypanosoma cruzi, the etiological agent of Chagas disease, is a polymorphic species. Evidence suggests that the majority of the T. cruzi populations isolated from afflicted humans, reservoir animals, or vectors are multiclonal. However, the extent and the complexity of multiclonality remain to be established, since aneuploidy cannot be excluded and current conventional cloning methods cannot identify all the representative clones in an infection. To answer this question, we adapted a methodology originally described for analyzing single spermatozoids, to isolate and study single T. cruzi parasites. Accordingly, the cloning apparatus of a Fluorescence-Activated Cell Sorter (FACS) was used to sort single T. cruzi cells directly into 96-wells microplates. Cells were then genotyped using two polymorphic genomic markers and four microsatellite loci. We validated this methodology by testing four T. cruzi populations: one control artificial mixture composed of two monoclonal populations – Silvio X10 cl1 (TcI) and Esmeraldo cl3 (TcII) – and three naturally occurring strains, one isolated from a vector (A316A R7) and two others derived from the first reported human case of Chagas disease. Using this innovative approach, we were able to successfully describe the whole complexity of these natural strains, revealing their multiclonal status. In addition, our results demonstrate that these T. cruzi populations are formed of more clones than originally expected. The method also permitted estimating of the proportion of each subpopulation of the tested strains. The single-cell genotyping approach allowed analysis of intrapopulation diversity at a level of detail not achieved previously, and may thus improve our comprehension of population structure and dynamics of T. cruzi. Finally, this methodology is capable to settle once and for all controversies on the issue of multiclonality.