Navegando por Assunto "Leishmania amazonensis"

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Ação do alcaloide (+)-filantidina sobre o protozoário Leishmania (Leishmania) amazonensis e a célula hospedeira
(Universidade Federal do Pará, 2014-08-14) MORAES, Lienne Silveira de; SILVA, Edilene Oliveira da; http://lattes.cnpq.br/7410116802190343
Leishmaniasis is an antropozoonotic disease caused by parasites of the genus Leishmania. These parasites proliferate primarily within macrophages of mammals and are responsible for promoting a variety of clinical manifestations, such as cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (MCL). The treatment available is chemotherapy, but is limited by toxicity and requires a long term treatment. The study of natural products from plants such as antileishmanial agent currently plays an important role in the search for new drugs for the treatment of leishmaniasis. (+)-phylantidine, is an alkaloid extracted from stem of Margaritaria nobilis of the family Phyllanthaceae. The aim of this study is evaluated the effects of (+)-phylantidine on promastigotes forms of Leishmania (Leishmania) amazonensis and host cell. Antiproliferative activity of promastigotes forms was observed when parasites were treated with 50, 100 e 200 μg/mL of alkaloid for 96 hours, with reduction of 73.75%, 82.50% and 88.75%, respectively when compared with non-treated parasites. In the period of 96 hours it was observed an IC50 of 56.34 μg/mL. Amphotericin B was used as reference drug and reduction of 100% in parasites treated with 0.1 μg/mL was observed after 96 hours. Treatment with the alkaloid promoted important changes in promastigotes that were observed by scanning and transmission electron microscopy. Alterations in cell body, flagellum, kinetoplast, mitochondria, rosette formation, presence of electrodense vesicles suggestive of lipid body and increase in structures like acidocalcisssomes were observed. In the host cell no cytotoxic effect was observed in the macrophages treated with the alkaloid and analysis by scanning electron microscopy showed that the alkaloid promoted an increase in the number of cytoplasmic projections, increased cell volume and spreading. Thus, these results demonstrate that (+)-phylantidine was effective in reducing the growth of the protozoa, without citotoxy effect which may represent a promising natural alternative source for the treatment of leishmaniasis.
Acesso aberto (Open Access)
Atividade leishmanicida do extrato da raiz de Physalis angulata e sua ação na célula hospedeira
(Universidade Federal do Pará, 2013-05-23) SILVA, Raquel Raick Pereira da; SILVA, Edilene Oliveira da; http://lattes.cnpq.br/7410116802190343
Leishmaniasis is an infectious disease caused by various species of the protozoan parasites of the Leishmania genus. The chemotherapy is the only effective treatment for the disease, but these drugs are, in general, toxics and requires a longer treatment period. Natural products have been used as traditional medicine and offer new perspectives and represent an important source of new antileishmanial agents. Thus, it is of great importance to assess the effects of the aqueous extract of the root of Physalis angulata, a plant widely used in popular medicine, in promastigotes and amastigotes of Leishmania (Leishmania) amazonensis and its effect on the host cell. Physalins D, E, F and G were found present, for the first time, in the P. angulata roots using liquid chromatography/mass spectrometry analysis. Antiproliferative activity and a dose-dependent inhibition of promastigote growth 74.1% and 99.8 % (IC50 35.5 μg/mL), and intracellular amastigotes 70.6% and 70.8% (IC50 32.2 μg/mL) was observed when parasites were treated with 50 and 100 μg/ mL of extract, respectively. The analysis of the microbicidal activity of host cell infected, with L. amazonensis demonstrated that extract is able to reverse the effect caused by the parasite to inhibit the production of reactive oxygen species. This growth inhibition was associated with several morphological alterations assessed by optical microscopy, transmission electron microscopy and scanning such as alteration on cell division, especially in the phase of cytokinesis, alteration in flagellar membrane, in flagellar pocket and duplication of kinetoplast DNA. Already by flow cytometry was possible to confirm that the treatment induced a phosphatidylserine exposure and decreased cell volume of promastigotes treated. In the host cell were observed cytoskeleton alterations, high number of cytoplasmatic projections, increase of cytoplasm, vacuoles and spreading ability. No cytotoxicity towards macrophages was observed. We have demonstrated that aqueous extract effectively promotes antileishmanial activity and clearly demonstrate the induction of apoptosis and ultrastructural alterations in Leishmania parasites. Thus, aqueous extract may represent a promising natural alternative source for a new antileishmanial agent.
Acesso aberto (Open Access)
Detecção da atividade e imunolocalização da enzima óxido nítrico sintase em Leishmania (Leishmania) amazonensis e Leishmania (Viannia) braziliensis
(Universidade Federal do Pará, 2014-10-30) FURTADO, Rodrigo Ribeiro; SILVA, Edilene Oliveira da; http://lattes.cnpq.br/7410116802190343
The Leishmaniasis is an infectious disease caused by parasites of the Leishmania genus and are distributed in different parts of the world. This pathology manifests in several clinical forms: Visceral leishmaniasis (VL), cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (MCL). The Leishmania parasite presents two evolutionary forms: promastigote form, free life parasite, and amastigotes, intracellular binding, present mainly in the mononuclear phagocytic cells. The growth inhibition or destruction of parasites within the host cell is an essential to break the infection mechanism. Inhibition of macrophage leishmanicidal effect appears to be related to the ability of some species to inhibit the nitric oxide (NO) production. Recent studies have shown that some species of Leishmania have the ability to produce NO by the constitutive form of nitric oxide synthase (cNOS). This work aims to detect and locate the cNOS enzyme present in Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis promastigotes. For this reason, this study used flow cytometry, which allowed to quantify NO production in parasites, indicating the increased activity of the cNOS enzyme in Leishmania (Leishmania) amazonensis compared with Leishmania (Viannia) braziliensis species. We performed immunostaining of promastigotes with anti-cNOS antibody to watch the ultrastructural localization of the enzyme by transmission electron microscopy (TEM), then co-labeling with anti-cNOS and anti-GAPDH antibody to confirm the probable compartmentalization this enzyme in glycossomal organelles. The results suggest that NO production by different strains of Leishmania is a process located in the glycossomal organelles capturing L-arginine from the host cell, the substrate depletion deprives the host to synthesize the harmful exogenous NO to the parasite. This modulation suggests another escape mechanism that trypanosomatid protozoa present in the complex host-parasite interaction.
Acesso aberto (Open Access)
Efeito in vitro e in vivo do 5-hidroxi-2-hidroximetil-gama-pirona durante a infecção por Leishmania (Leishmania) amazonensis
(Universidade Federal do Pará, 2013-05-27) RODRIGUES, Ana Paula Drummond; SILVA, Edilene Oliveira da; http://lattes.cnpq.br/7410116802190343
Leishmaniasis includes a group of infectious diseases with worldwide distribution. Chemotherapy is one of the most effective treatments for this disease; although a number of anti-leishmanial drugs are available, these drugs are in general toxic, expensive and require long-term treatment. Kojic acid, or 5-hydroxy-2-hydroxymethyl-γ-pyrone (HMP), is well known for effectively inhibiting the tyrosinase enzyme in the process of melanin biosynthesis and is extensively used in cosmetics and as a topical treatment for melasm with no cytotoxicity observed in humans; however its potential as anti-leishmanial agent are unknown. The present study was designed to determine the effect of this bioproduct on L. amazonensis, following in vitro and in vivo infections. HMP (50μg/mL) was found to decrease the growth by 62% (IC50 34 μg/mL) and 79% (IC50 27.84 μg/mL) of promastigotes and amastigotes in vitro, respectively. Ultrastructural analysis of both evolutive forms showed that HMP increasing the presence of vesicles bodies into the flagellar pocket, and inducing an intense intracellular vacuolization and swelling of the mitochondrion. In vitro study also demonstrated that HMP is able to reverse ROS inhibitory mechanism promoted by L. amazonensis observed by nitroblue tetrazolium reaction. Histopathologycal analysis of in vivo topical treatment with HMP ointment showed healing process and suppressed ulcer dissemination in animal model. In addition, collagen fibers stained by picrosirus red, were found at the infection site of HMP-treated animals and an absence or low-level cellular infiltrate was observed, as well as a decrease in parasite burden. In view of the in vitro selective action of HMP on leishmania parasites, the activation of host cells and in vivo decrease in parasite burden, observed using HMP ointment, as well as the fact that HMP is widely and safely applied as an antimelasm agent in humans, this compound could be useful for the selective treatment of cutaneous leishmaniasis and may hold great potential as an anti-leishmanial agent.
Acesso aberto (Open Access)
Estudo da ação da crotoxina sobre o perfil de ativação de macrófagos peritoneais infectados com Leishmania (Leishmania) amazonensis
(Universidade Federal do Pará, 2016-04-12) FARIAS, Luis Henrique Seabra de; SILVA, Edilene Oliveira da; http://lattes.cnpq.br/7410116802190343
American Tegumentary Leishmaniasis (ATL) is a parasitic disease widely spread in most countries of Latin America, and caused by different species of the genus Leishmania. This protozoan is an obligate intracellular parasite that developed mechanisms to subvert the microbicidal activity of macrophages, such as inhibition of reactive oxygen species (ROS) and nitric oxide (NO) production. The chemotherapy is one of the most effective treatments for this disease, although the antileishmanial drugs available are in general toxic, expensive and require long-term treatment. Thus, the development of new natural products to treat leishmaniasis has become a priority. Ophidian toxins are natural sources of bioactive products with therapeutic properties already described. Therefore, we considered analyze the activity of crotoxin (CTX), a dimeric protein and the main neurotoxic component of Crotalus durissus terrificus snake venom, against promastigotes of Leishmania (L.) amazonensis and macrophages. The toxin significantly decreasing of 32,5% on the growth of promastigotes at 1,2μg/mL and 24,9% at 4,8μg/mL after 96 hours of treatment (IC50= 22,86μg/mL). The colorimetric assay (MTT) showed that this compound presented no cytotoxic effects against macrophages. Interestingly, CTX treated macrophages presented a significant higher capacity to metabolize the MTT substrate (mean= 59,78% ±3,31, higher) when compared with untreated control. It was observed that treated macrophages presented intense production of ROS (mean= 35,95% ±2,76, higher) when compared with untreated cells. Treated macrophages presented increased phagocytic activity and were capable to eliminate intracellular parasites. Besides that, these cells had it NO and pro-inflammatory cytokines production increased and morphological alteration that characterizes the M1 cellular activation profile. That activation culminates with the parasite elimination throughout host response, reverting the anergic action promoted by L. amazonensis, thereby leading to a good disease prognostic, evidencing that this compound could be a promising antileishmanial agent.
Acesso aberto (Open Access)
Further observations on clinical, histopathological, and immunological features of borderline disseminated cutaneous leishmaniasis caused by Leishmania (Leishmania) amazonensis
(2005-08) SILVEIRA, Fernando Tobias; LAINSON, Ralph; CORBETT, Carlos Eduardo Pereira
Leishmania (Leishmania) amazonensis has for some time been considered as the causative agent of two distinct forms of American cutaneous leishmaniasis (ACL): localized cutaneous leishmaniasis (LCL), and anergic diffuse cutaneous leishmaniasis (ADCL). Recently, a new intermediate form of disease, borderline disseminated cutaneous leishmaniasis (BDCL), was introduced into the clinical spectrum of ACL caused by this parasite, and in this paper we record the clinical, histopathological, and immunological features of eight more BDCL patients from Brazilian Amazonia, who acquired the disease in the Pará state, North Brazil. Seven of them had infections of one to two years' evolution and presented with primary skin lesions and the occurrence of metastases at periods varying from six to 12 months following appearance of the first lesion. Primary skin lesions ranged from 1-3 in number, and all had the aspect of an erythematous, infiltrated plaque, variously located on the head, arms or legs. There was lymphatic dissemination of infection, with lymph node enlargement in seven of the cases, and the delayed hypersensitivity skin-test (DTH) was negative in all eight patients prior to their treatment. After that, there was a conversion of DTH to positive in five cases re-examined. The major histopathological feature was a dermal mononuclear infiltration, with a predominance of heavily parasitized and vacuolated macrophages, together with lymphocytes and plasma cells. In one case, with similar histopathology, the patient had acquired his infection seven years previously and he presented with the largest number of disseminated cutaneous lesions. BDCL shows clinical and histopathological features which are different from those of both LCL and ADCL, and there is a good prognosis of cure which is generally not so in the case of frank ADCL.
Acesso aberto (Open Access)
Leishmania (L.) amazonensis inibe a maturação e a função ativadora das células de Langerhans da pele tratadas com TNF-α e anti-CD40 in vitro
(Universidade Federal do Pará, 2014-06-27) CAMPELO, Simone Rodrigues; SALGADO, Claudio Guedes; http://lattes.cnpq.br/2310734509396125
Leishmania amazonensis is one of the agents in a wide spectrum of clinical forms of cutaneous leishmaniasis. In general, the resistance against leishmaniasis depends on the development of an efficient immune response, however many studies have demonstrated that specific cytokines or combinations of cytokines may be factors of resistance or susceptibility to infection by L. amazonensis. Recent studies suggest the involvement of Langerhans cells (LCs) in the anti-Leishmania response, but the mechanisms involved in this interaction are still poorly understood. In this study, we investigated the role of TNF-α and anti-CD40 in L. amazonensis interaction with LCs in vitro, showing de profile of cytokines produced and the expression of surface molecules, besides verifing their abilities to activate the production of IFN-γ e IL-4 by lymph node cells. Methods: Fresh immature LCs, highly purified from BALB/c mouse skin, were incubated with L. amazonensis promastigotes, TNF-α and/or anti- CD40 mAb. After 24 h, LCs were co-cultured with lymph nodes cells of BALB/c mice for additional 72h. Culture supernatants were tested for IL-6, IL-12p70, IFN-γ and IL-4 by ELISA, while surface molecules were analyzed by FACS. Results: The levels of IL-6 and IL- 12p70 produced by LCs were significantly reduced after interaction with L. amazonensis, even after treatment of LCs with TNF-α or anti-CD40. Regarding surface molecules, there was no difference in the expression of CD207 in both groups, but the presence of L. amazonensis promoted a significant reduction in the expression of CD40 on LCs treated with TNF-α or anti-CD40, and increased expression CD86 in all groups. Lymph node cells showed a decreased production of IFN-γ in the presence of L. amazonensis and no change in IL-4. When co-cultured with LCs previously stimulated with L. amazonensis, the production of IFN-γ was also reduced, even in the presence of TNF-α and/or anti-CD40. No significant changes were observed in IL-4 by lymph cells co-cultured under the same experimental conditions. Conclusion: L. (L.) amazonensis exert an immunomodulatory effect on the immune response mediated by LCs by: 1) inhibiting the production of IL-6 and IL-12p70; 2) decreasing CD40 expression and; 3) preventing the activation of IFN-γ production by lymph node cells co-cultured with LCs, even after treatment with TNF-α and anti-CD40 antibody.
Acesso aberto (Open Access)
Planejamento e avaliação in sílica de análogos de lapachol em enzima alvo de Leishmania (Leishmania) amazonensis
(Universidade Federal do Pará, 2017-11-09) FERREIRA, Érica Patrícia dos Reis; DOLABELA, Maria Fani; http://lattes.cnpq.br/0458080121943649; SANTOS, Lourivaldo da Silva; http://lattes.cnpq.br/3232898465948962
The study aims to design and evaluate antiamastigote activity of Leishmania amazonensis and cytotoxicity Lapachol analogues. The studies predictive pharmacokinetic characteristics were performed, toxicological, biological activity and molecular docking or molecular docking. For pharmacokinetic and toxicological characteristics used the online program PreADMET while biological activities were assessed by online program Prediction Spectra of Activity is Substances (PASS). For the molecular docking analysis, the therapeutic target was selected Triponationa reductase, and the evaluation of interaction between the molecules and target this protein was performed by the virtual Molegro program docker (MVD). The extraction and isolation of Lapachol was performed and its identification was performed by nuclear magnetic resonance spectroscopy (NMR). All analogs Lapachol and are well absorbed from the intestine with the absorption ranging from 79.745% to 99.056%, furthermore inhibit the cytochrome P450 (CYP). Almost half of the molecules tested (42.1%) had moderate distribution into the central nervous system (CNS), including Lapachol, while the remainder have high distribution. The results of the toxicity of the molecules studied suggest that 63.16% are mutagenic and carcinogenic, which includes Lapachol and 10.5% and 5.26% are carcinogenic and mutagenic, respectively, but showed 21.05% not exhibit cytotoxicity. In molecular docking the substances studied showed less energy than the standard substance, although they have good interaction with energies between 94.343 to 115.635 kJ / mol. The Lapachol was isolated and identified. According with to the analogo results show that with the best characteristics was the 3,4-dihydroxy-2- (2-hydroxy-3-methylbutil) nafthalen-1 (4H) -one.