Ex vivo and in vivo biological behavior of Leishmania (Viannia) shawi

São Paulo University Medical School Department of Pathology Av. Dr. Arnaldo, 455 01246-903 São Paulo SP Brazil
Parasitology Research (Impact Factor: 2.1). 11/2009; 105(6):1741-1747. DOI: 10.1007/s00436-009-1614-7
Source: PubMed

ABSTRACT Since the first description of Leishmania (Viannia) shawi, few studies were performed with this parasite. In the present work, the in vivo and ex vivo behavior of L. (Viannia) shawi infection was studied using murine model. Peritoneal macrophages from BALB/c and C57BL/6 mice were infected with promastigotes
in the stationary phase of growth; after 24h, the infection index and nitric oxide (NO) levels in the supernatant of the
cultures were analyzed. BALB/c and C57BL/6 mice were infected into the hind footpad, and at each 2weeks, mice were sacrificed,
and the histological changes of the skin inoculation site, parasitism, and humoral immune responses were evaluated during
8weeks. Ex vivo experiments showed that macrophages of BALB/c presented higher infection index and lesser NO levels than
macrophages of C57BL/6. In vivo experiments showed that BALB/c presented higher lesion size than C57BL/6 mice; similarly,
the histopathological changes and the parasitism in skin were more exacerbate in BALB/c mice. In draining lymph nodes, the
main change was increase of germinative centers, and parasites were detected from 6weeks pi onwards in both mice strain.
IgG was detected in BALB/c mice from 4weeks, while in C57BL/6, from 6weeks pi onwards. Taken together, these results indicate
that BALB/c showed a classical behavior of susceptibility when compared to C57BL/6 mice.

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Available from: Felipe Passero, Sep 29, 2015
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    • "These protozoa are able to cause cutaneous and visceral form of the disease. Several reports have examined the pathogenesis of leishmaniasis in murine models aiming to characterize the mechanisms by which Leishmania parasites induce disease [1] [2] [3] [4] [5]. However, other reports state that some aspects of leishmaniasis immunopathogenesis cannot be completely represented using murine models since they are not the natural hosts for the parasites. "
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    ABSTRACT: The purpose of this study was to characterize the immunopathological response in the skin of S. apella infected with Leishmania (L.) amazonensis and L. (V.) braziliensis parasites, the main causative agents of localized cutaneous leishmaniasis in South America. In infected animals, amastigote forms of L. (L.) amazonensis could be detected till 120 days postinfection (PI), while, in L. (V.) braziliensis infection, parasites could be detected until 180 days PI in the skin sections. CD20(+) cells were detected throughout the experimental time in both groups as well as in CD3(+) cells, which appeared to be activated because high densities of inducible nitric oxide synthase (iNOS(+)) cells were detected at 60 and 90 days PI in both studied groups. After 60 and 120 days PI, decrease in iNOS(+) cells was observed in L. (L.) amazonensis and L. (V.) braziliensis, respectively, which was associated with parasite clearance. Increase in lysozyme(+) cells was observed during the experimental infections, which also can be associated with parasite killing.
    BioMed Research International 08/2014; 2014:134236. DOI:10.1155/2014/134236 · 2.71 Impact Factor
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    • "A series of fractions and purified antigens have been characterized and used to achieve protection against L. (L.) amazonensis and L. (V.) braziliensis [18-20]. Despite their medical and epidemiological importance in the New World, other parasite species that affect humans are rarely studied, such as L. (V.) shawi and L. (V.) panamensis [21,22]. Some recent studies have demonstrated that antigens derived from both these species were immunogenic and beneficial to experimental hosts following challenge [23,24]. "
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    ABSTRACT: Leishmania (Viannia) shawi parasite was first characterized in 1989. Recently the protective effects of soluble leishmanial antigen (SLA) from L. (V.) shawi promastigotes were demonstrated using BALB/c mice, the susceptibility model for this parasite. In order to identify protective fractions, SLA was fractionated by reverse phase HPLC and five antigenic fractions were obtained. F1 fraction was purified from L. (V.) shawi parasite extract by reverse phase HPLC. BALB/c mice were immunized once a week for two consecutive weeks by subcutaneous routes in the rump, using 25 μg of F1. After 1 and 16 weeks of last immunization, groups were challenged in the footpad with L. (V.) shawi promastigotes. After 2 months, those same mice were sacrificed and parasite burden, cellular and humoral immune responses were evaluated. The F1 fraction induced a high degree of protection associated with an increase in IFN-γ, a decrease in IL-4, increased cell proliferation and activation of CD8+T lymphocytes. Long-term protection was acquired in F1-immunized mice, associated with increased CD4+ central memory T lymphocytes and activation of both CD4+ and CD8+ T cells. In addition, F1-immunized groups showed an increase in IgG2a levels. The inductor capability of antigens to generate memory lymphocytes that can proliferate and secrete beneficial cytokines upon infection could be an important factor in the development of vaccine candidates against American Tegumentary Leishmaniasis.
    Parasites & Vectors 03/2012; 5(1):64. DOI:10.1186/1756-3305-5-64 · 3.43 Impact Factor
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    • "After 24 h of infection, the plates were washed four times with PBS and the compounds were added at each well in a range of 16.31 to 500 ng/μL. After 48 h of treatment, the supernatants were collected to measure nitrate levels (Passero et al. 2009 "
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    ABSTRACT: Species of Baccharis exhibit antibiotic, antiseptic, wound-healing, and anti-protozoal properties, and have been used in the traditional medicine of South America for the treatment of several diseases. In the present work, the fractionation of EtOH extract from aerial parts of Baccharis uncinella indicated that the isolated compounds caffeic acid and pectolinaringenin showed inhibitory activity against Leishmania (L.) amazonensis and Leishmania (V.) braziliensis promastigotes, respectively. Moreover, amastigote forms of both species were highly sensible to the fraction composed by oleanolic + ursolic acids and pectolinaringenin. Caffeic acid also inhibited amastigote forms of L. (L.) amazonensis, but this effect was weak in L. (V.) braziliensis amastigotes. The treatment of infected macrophages with these compounds did not alter the levels of nitrates, indicating a direct effect of the compounds on amastigote stages. The results presented herein suggest that the active components from B. uncinella can be important to the design of new drugs against American tegumentar leishmaniases.
    Parasitology Research 10/2010; 108(3):529-36. DOI:10.1007/s00436-010-2091-8 · 2.10 Impact Factor
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