LUIZ FELIPE DOMINGUES PASSERO
Projetos de Pesquisa
Unidades Organizacionais
LIM/50 - Laboratório de Patologia das Moléstias Infecciosas, Hospital das Clínicas, Faculdade de Medicina
5 resultados
Resultados de Busca
Agora exibindo 1 - 5 de 5
- Analysis of the protective potential of antigens released by Leishmania (Viannia) shawi promastigotes(2012) PASSERO, Luiz Felipe Domingues; MARQUES, Claudia; VALE-GATO, Ines; CORBETT, Carlos Eduardo Pereira; LAURENTI, Marcia Dalastra; SANTOS-GOMES, GabrielaLeishmania (Viannia) shawi causes cutaneous lesions in humans. Parasite antigens conferring significant protection against American tegumentar leishmaniosis (ATL) might be important for the development of effective vaccine. Therefore, this work evaluates the protective effect of antigenic fractions released by L. shawi. Antigens released by promastigotes to culture medium were concentrated and isolated by SDS-PAGE. The three main fractions LsPass1 (>75 kDa), LsPass2 (75-50 kDa) and LsPass3 (<50 kDa) were electro-eluted according with their molecular mass. Immunized BALB/c mice were challenged with L. shawi promastigotes and the course of infection monitored during 5 weeks. LsPass1-challenged mice showed no protection, however, a strong degree of protection associated to smaller lesions and high expression of IFN-gamma and TNF-alpha by CD4(+) T, CD8(+) T and double negative CD4CD8 cells was achieved in LsPass3-challenged mice. Furthermore, LsPass2-challenged mice showed an intermediated degree of protection associated to high levels of IFN-gamma, IL-4 and IL-10 mRNA. In spite of increased expression of IFN-gamma and TNF-alpha, high amounts of IL-4 and IL-10 mRNA were also detected in LsPass3-challenged mice indicating a possible contribution of these cytokines for the persistence of a residual number of parasites that may be important in inducing long-lasting immunity. Therefore, LsPass3 seems to be an interesting alternative that should be considered in the development of an effective vaccine against ATL.
- The Effect of Ursolic Acid on Leishmania (Leishmania) amazonensis Is Related to Programed Cell Death and Presents Therapeutic Potential in Experimental Cutaneous Leishmaniasis(2015) YAMAMOTO, Eduardo S.; CAMPOS, Bruno L. S.; JESUS, Jessica A.; LAURENTI, Marcia D.; RIBEIRO, Susan P.; KALLAS, Esper G.; RAFAEL-FERNANDES, Mariana; SANTOS-GOMES, Gabriela; SILVA, Marcelo S.; SESSA, Deborah P.; LAGO, Joao H. G.; LEVY, Debora; PASSERO, Luiz F. D.Among neglected tropical diseases, leishmaniasis is one of the most important ones, affecting more than 12 million people worldwide. The available treatments are not well tolerated, and present diverse side effects, justifying the search for new therapeutic compounds. In the present study, the activity of ursolic acid (UA) and oleanolic acid (OA) were assayed in experimental cutaneous leishmaniasis (in vitro and in vivo). Promastigote forms of L. amazonensis were incubated with OA and UA for 24h, and effective concentration 50% (EC50) was estimated. Ultraestructural alterations in Leishmania amazonensis promastigotes after UA treatment were evaluated by transmission electron microscopy, and the possible mode of action was assayed through Annexin V and propidium iodide staining, caspase 3/7 activity, DNA fragmentation and transmembrane mitochondrial potential. The UA potential was evaluated in intracellular amastigotes, and its therapeutic potential was evaluated in L. amazonensis infected BALB/c mice. UA eliminated L. amazonensis promastigotes with an EC50 of 6.4 mu g/mL, comparable with miltefosine, while OA presented only a marginal effect on promastigote forms at 100 mu g/mL. The possible mechanism by which promastigotes were eliminated by UA was programmed cell death, independent of caspase 3/7, but it was highly dependent on mitochondria activity. UA was not toxic for peritoneal macrophages from BALB/c mice, and it was able to eliminate intracellular amastigotes, associated with nitric oxide (NO) production. OA did not eliminate amastigotes nor trigger NO. L. amazonensis infected BALB/c mice submitted to UA treatment presented lesser lesion size and parasitism compared to control. This study showed, for the first time, that UA eliminate promastigote forms through a mechanism associated with programed cell death, and importantly, was effective in vivo. Therefore, UA can be considered an interesting candidate for future tests as a prototype drug for the treatment of cutaneous leishmaniasis.
- New insights into neutrophil and Leishmania infantum in vitro immune interactions(2015) MARQUES, Claudia S.; PASSERO, Luiz Felipe D.; VALE-GATO, Ines; RODRIGUES, Armanda; RODRIGUES, Olivia Roos; MARTINS, Catarina; CORREIA, Ivone; TOMAS, Ana M.; ALEXANDRE-PIRES, Graca; FERRONHA, M. Helena; SANTOS-GOMES, Gabriela M.The interaction between polymorphonuclear leukocytes (PMN) or neutrophils and Leishmania became an interesting focus of research, since PMN turn out to be essential cells in transiently hosting the parasites. This study aims to evaluate whether L. infantum, the etiological agent of zoonotic visceral leishmaniasis, influences the in vitro functional activity of murine neutrophils. Phagocytosis, chemotaxis, oxidative burst, degranulation and apoptosis assays were performed. Cytokines, chemokines and toll-like receptors gene expression were evaluated by Real-time PCR. Results indicate that some of the innate features of PMN immunity were activated when in contact with L. infantum. However, parasites might negatively interfere with PMN defense mechanisms compromising the link between innate and acquired immunity. This work provides additional insights on the inflammatory immune interactions between neutrophils and L. infantum highlighting the role of PMN in Leishmania infection.
- In Vivo Antileishmanial Activity of Plant-Based Secondary Metabolites(2013) PASSERO, Luiz Felipe Domingues; LAURENTI, Marcia D.; SANTOS-GOMES, Gabriela; CAMPOS, Bruno Luiz Soares; SARTORELLI, Patricia; LAGO, Joao Henrique G.
- Mechanistic Insights into the Leishmanicidal and Bactericidal Activities of Batroxicidin, a Cathelicidin-Related Peptide from a South American Viper (Bothrops atrox)(2021) DEMATEI, Anderson; NUNES, Joao B.; MOREIRA, Daniel C.; JESUS, Jessica A.; LAURENTI, Marcia D.; MENGARDA, Ana C. A.; VIEIRA, Maria Silva; AMARAL, Constanca Pais do; DOMINGUES, Marco M.; MORAES, Josue de; PASSERO, Luiz F. D.; BRAND, Guilherme; BESSA, Lucinda J.; WIMMER, Reinhard; KUCKELHAUS, Selma A. S.; TOMAS, Ana M.; SANTOS, Nuno C.; PLACIDO, Alexandra; EATON, Peter; LEITE, Jose Roberto S. A.Snake venoms are important sources of bioactive molecules, including those with antiparasitic activity. Cathelicidins form a class of such molecules, which are produced by a variety of organisms. Batroxicidin (BatxC) is a cathelicidin found in the venom of the common lancehead (Bothrops atrox). In the present work, BatxC and two synthetic analogues, Bab(C(C-2.15Phe) and BabcC(C-2.14Phe)des-Phe1, were assessed for their microbicidal activity. All three peptides showed a broad-spectrum activity on Gram-positive and -negative bacteria, as well as promastigote and amastigote forms of Leishmania (Leishmania) amazonensis. Circular dichroism (CD) and nuclear magnetic resonance (NMR) data indicated that the three peptides changed their structure upon interaction with membranes. Biomimetic membrane model studies demonstrated that the peptides exert a permeabilization effect in prokaryotic membranes, leading to cell morphology distortion, which was confirmed by atomic force microscopy (AFM). The molecules considered in this work exhibited bactericidal and leishmanicidal activity at low concentrations, with the AFM data suggesting membrane pore formation as their mechanism of action. These peptides stand as valuable prototype drugs to be further investigated and eventually used to treat bacterial and protozoal infections.