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1.
Parasitol Res ; 119(10): 3503-3515, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32772176

RESUMO

Malaria, babesiosis, trypanosomosis, and leishmaniasis are some of the most life-threatening parasites, but the range of drugs to treat them is limited. An effective, safe, and low-cost drug with a large activity spectrum is urgently needed. For this purpose, an aryl amino alcohol derivative called Alsinol was resynthesized, screened in silico, and tested against Plasmodium, Babesia, Trypanosoma, and Leishmania. In silico Alsinol follows the Lipinski and Ghose rules. In vitro it had schizontocidal activity against Plasmodium falciparum and was able to inhibit gametocytogenesis; it was particularly active against late gametocytes. In malaria-infected mice, it showed a dose-dependent activity similar to chloroquine. It demonstrated a similar level of activity to reference compounds against Babesia divergens, and against promastigotes, and amastigotes stages of Leishmania in vitro. It inhibited the in vitro growth of two African animal strains of Trypanosoma but was ineffective in vivo in our experimental conditions. It showed moderate toxicity in J774A1 and Vero cell models. The study demonstrated that Alsinol has a large spectrum of activity and is potentially affordable to produce. Nevertheless, challenges remain in the process of scaling up synthesis, creating a suitable clinical formulation, and determining the safety margin in preclinical models.


Assuntos
Amino Álcoois/farmacologia , Antiprotozoários/farmacologia , Amino Álcoois/síntese química , Amino Álcoois/química , Animais , Antiprotozoários/síntese química , Antiprotozoários/química , Babesia/efeitos dos fármacos , Babesia/crescimento & desenvolvimento , Sobrevivência Celular/efeitos dos fármacos , Chlorocebus aethiops , Modelos Animais de Doenças , Leishmania/efeitos dos fármacos , Leishmania/crescimento & desenvolvimento , Estágios do Ciclo de Vida/efeitos dos fármacos , Camundongos , Plasmodium/efeitos dos fármacos , Plasmodium/crescimento & desenvolvimento , Infecções por Protozoários/tratamento farmacológico , Infecções por Protozoários/parasitologia , Resultado do Tratamento , Trypanosoma/efeitos dos fármacos , Trypanosoma/crescimento & desenvolvimento , Células Vero
2.
Trends Parasitol ; 36(9): 785-795, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32713762

RESUMO

Leishmania parasites have the capacity to rapidly adapt to changing environments in their digenetic life cycle which alternates between a vertebrate and an invertebrate host. Emergence of resistance following drug exposure can evoke phenotypic alterations that affect several aspects of parasite fitness in both hosts. Current studies of the impact of resistance are mostly limited to interactions with the mammalian host and characterization of in vitro parasite growth and differentiation. Development in the vector and transmission capacity have been largely ignored. This review reflects on the impact of drug resistance on its spreading potential with specific focus on the use of the sand fly infection model to evaluate parasite development in the vector and the ensuing transmission potential of drug-resistant phenotypes.


Assuntos
Resistência a Medicamentos , Insetos Vetores/parasitologia , Leishmaniose/transmissão , Psychodidae/parasitologia , Animais , Antiparasitários/farmacologia , Humanos , Leishmania/efeitos dos fármacos , Leishmania/crescimento & desenvolvimento , Leishmaniose/parasitologia , Estágios do Ciclo de Vida/fisiologia
3.
Korean J Parasitol ; 58(2): 173-179, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32418386

RESUMO

Leishmaniasis is a prevalent cause of death and animal morbidity in underdeveloped countries of endemic area. However, there is few vaccine and effective drugs. Antimicrobial peptides are involved in the innate immune response in many organisms and are being developed as novel drugs against parasitic infections. In the present study, we synthesized a 5-amino acid peptide REDLK, which mutated the C-terminus of Pseudomonas exotoxin, to identify its effect on the Leishmania tarentolae. Promastigotes were incubated with different concentration of REDLK peptide, and the viability of parasite was assessed using MTT and Trypan blue dye. Morphologic damage of Leishmania was analyzed by light and electron microscopy. Cellular apoptosis was observed using the annexin V-FITC/PI apoptosis detection kit, mitochondrial membrane potential assay kit and flow cytometry. Our results showed that Leishmania tarentolae was susceptible to REDLK in a dose-dependent manner, disrupt the surface membrane integrity and caused parasite apoptosis. In our study, we demonstrated the leishmanicidal activity of an antimicrobial peptide REDLK from Pseudomonas aeruginosa against Leishmania tarentolae in vitro and present a foundation for further research of anti-leishmanial drugs.


Assuntos
Proteínas de Bactérias/farmacologia , Leishmania/efeitos dos fármacos , Leishmania/crescimento & desenvolvimento , Peptídeos/farmacologia , Pseudomonas/metabolismo , Técnicas In Vitro
4.
Nucleic Acids Res ; 48(8): 4405-4417, 2020 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-32232353

RESUMO

Translation of most cellular mRNAs in eukaryotes proceeds through a cap-dependent pathway, whereby the cap-binding complex, eIF4F, anchors the preinitiation complex at the 5' end of mRNAs and regulates translation initiation. The requirement of Leishmania to survive in changing environments can explain why they encode multiple eIF4E (LeishIF4Es) and eIF4G (LeishIF4Gs) paralogs, as each could be assigned a discrete role during their life cycle. Here we show that the expression and activity of different LeishIF4Es change during the growth of cultured promastigotes, urging a search for regulatory proteins. We describe a novel LeishIF4E-interacting protein, Leish4E-IP2, which contains a conserved Y(X)4LΦ IF4E-binding-motif. Despite its capacity to bind several LeishIF4Es, Leish4E-IP2 was not detected in m7GTP-eluted cap-binding complexes, suggesting that it could inhibit the cap-binding activity of LeishIF4Es. Using a functional assay, we show that a recombinant form of Leish4E-IP2 inhibits the cap-binding activity of LeishIF4E-1 and LeishIF4E-3. Furthermore, we show that transgenic parasites expressing a tagged version of Leish4E-IP2 also display reduced cap-binding activities of tested LeishIF4Es, and decreased global translation. Given its ability to bind more than a single LeishIF4E, we suggest that Leish4E-IP2 could serve as a broad-range repressor of Leishmania protein synthesis.


Assuntos
Fator de Iniciação 4F em Eucariotos/metabolismo , Leishmania/metabolismo , Proteínas de Protozoários/metabolismo , Capuzes de RNA/metabolismo , Leishmania/genética , Leishmania/crescimento & desenvolvimento , Biossíntese de Proteínas , Proteínas de Protozoários/isolamento & purificação
5.
Parasit Vectors ; 13(1): 181, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32268916

RESUMO

BACKGROUND: Leishmaniasis is a human and animal disease caused by parasites of the genus Leishmania, which is now divided into four subgenera, Leishmania, Viannia, Sauroleishmania and Mundinia. Subgenus Mundinia, established in 2016, is geographically widely dispersed, its distribution covers all continents, except Antarctica. It consists of 5 species; L. enriettii and L. macropodum are parasites of wild mammals while L. martiniquensis, L. orientalis and an unnamed Leishmania sp. from Ghana are infectious to humans. There is very little information on natural reservoir hosts and vectors for any Mundinia species. METHODS: Experimental infections of guinea pigs with all five Mundinia species were performed. Animals were injected intradermally with 107 culture-derived promastigotes into both ear pinnae. The courses of infections were monitored weekly; xenodiagnoses were performed at weeks 4 and 8 post-infection using Lutzomyia migonei. The distribution of parasites in different tissues was determined post-mortem by conventional PCR. RESULTS: No significant differences in weight were observed between infected animals and the control group. Animals infected with L. enriettii developed temporary lesions at the site of inoculation and were infectious to Lu. migonei in xenodiagnoses. Animals infected with L. martiniquensis and L. orientalis developed temporary erythema and dry lesions at the site of inoculation, respectively, but were not infectious to sand flies. Guinea pigs infected by L. macropodum and Leishmania sp. from Ghana showed no signs of infection during experiments, were not infectious to sand flies and leishmanial DNA was not detected in their tissue samples at the end of experiments at week 12 post-inoculation. CONCLUSIONS: According to our results, guinea pigs are not an appropriate model organism for studying Mundinia species other than L. enriettii. We suggest that for better understanding of L. (Mundinia) biology it is necessary to focus on other model organisms.


Assuntos
Modelos Animais de Doenças , Leishmania/crescimento & desenvolvimento , Leishmaniose/veterinária , Animais , Feminino , Cobaias , Leishmania/classificação , Leishmaniose/parasitologia
6.
Parasit Vectors ; 12(1): 601, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31870406

RESUMO

BACKGROUND: The in vitro activity against Leishmania spp. of a novel group of compounds, phenalenone derivatives, is described in this study. Previous studies have shown that some phenalenones present leishmanicidal activity, and induce a decrease in the mitochondrial membrane potential in L. amazonensis parasites, so in order to elucidate the evidence of programmed cell death occurring inside the promastigote stage, different assays were performed in two different species of Leishmania. METHODS: We focused on the determination of the programmed cell death evidence by detecting the characteristic features of the apoptosis-like process, such as phosphatidylserine exposure, mitochondrial membrane potential, and chromatin condensation among others. RESULTS: The results showed that four molecules activated the apoptosis-like process in the parasite. All the signals observed were indicative of the death process that the parasites were undergoing. CONCLUSIONS: The present results highlight the potential use of phenalenone derivatives against Leishmania species and further studies should be undertaken to establish them as novel leishmanicidal therapeutic agents.


Assuntos
Antiprotozoários/química , Antiprotozoários/farmacologia , Apoptose/efeitos dos fármacos , Leishmania/efeitos dos fármacos , Fenalenos/química , Fenalenos/farmacologia , Humanos , Leishmania/citologia , Leishmania/crescimento & desenvolvimento , Leishmaniose/parasitologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Estrutura Molecular
7.
Molecules ; 24(23)2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31757083

RESUMO

Leishmaniasis is a group of neglected tropical diseases caused by protozoan parasites of the Leishmania genus. The absence of effective vaccines and the limitations of current treatments make the search for effective therapies a real need. Different plant-derived essential oils (EOs) have shown antileishmanial effects, in particular from Bixa orellana L. (EO-Bo) and Dysphania ambrosioides (L.) Mosyakin & Clemants (EO-Da). In the present study, the EO-Bo and EO-Da, formulated in nanocochleates (EO-Bo-NC and EO-Da-NC, respectively), were evaluated in vitro and in vivo against L. amazonensis. The EO-Bo-NC and EO-Da-NC did not increase the in vitro inhibitory activity of the EOs, although the EO-Bo-NC showed reduced cytotoxic effects. In the animal model, both formulations (30 mg/kg/intralesional route/every 4 days/4 times) showed no deaths or weight loss greater than 10%. In the animal (mouse) model, EO-Bo-NC contributed to the control of infection (p < 0.05) in comparison with EO-Bo treatment, while the mice treated with EO-Da-NC exhibited larger lesions (p < 0.05) compared to those treated with EO-Da. The enhanced in vivo activity observed for EO-Bo-NC suggests that lipid-based nanoformulations like nanocochleates should be explored for their potential in the proper delivery of drugs, and in particular, the delivery of hydrophobic materials for effective cutaneous leishmaniasis treatment.


Assuntos
Amaranthaceae/química , Antiprotozoários , Caryophyllaceae/química , Leishmania/crescimento & desenvolvimento , Leishmaniose/tratamento farmacológico , Nanopartículas , Óleos Voláteis , Animais , Antiprotozoários/química , Antiprotozoários/farmacologia , Bixaceae , Feminino , Leishmaniose/metabolismo , Leishmaniose/patologia , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas/química , Nanopartículas/uso terapêutico , Óleos Voláteis/química , Óleos Voláteis/farmacologia
8.
mSphere ; 4(6)2019 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-31722993

RESUMO

Leishmania parasites cycle between sand-fly vectors and mammalian hosts, adapting to changing environmental conditions by driving a stage-specific program of gene expression, which is tightly regulated by translation processes. Leishmania encodes six eIF4E orthologs (LeishIF4Es) and five eIF4G candidates, forming different cap-binding complexes with potentially varying functions. Most LeishIF4E paralogs display temperature sensitivity in their cap-binding activity, except for LeishIF4E1, which maintains its cap-binding activity under all conditions. We used the CRISPR-Cas9 system to successfully generate a null mutant of LeishIF4E1 and examine how its elimination affected parasite physiology. Although the LeishIF4E1-/- null mutant was viable, its growth was impaired, in line with a reduction in global translation. As a result of the mutation, the null LeishIF4E1-/- mutant had a defective morphology, as the cells were round and unable to grow a normal flagellum. This was further emphasized when the LeishIF4E1-/- cells failed to develop the promastigote morphology once they shifted from conditions that generate axenic amastigotes (33°C, pH 5.5) back to neutral pH and 25°C, and they maintained their short flagellum and circular structure. Finally, the LeishIF4E1-/- null mutant displayed difficulty in infecting cultured macrophages. The morphological changes and reduced infectivity of the mutant may be related to differences in the proteomic profile of LeishIF4E1-/- cells from that of controls. All defects monitored in the LeishIF4E1-/- null mutant were reversed in the add-back strain, in which expression of LeishIF4E1 was reconstituted, establishing a strong link between the cellular defects and the absence of LeishIF4E1 expression.IMPORTANCE Leishmania parasites are the causative agents of a broad spectrum of diseases. The parasites migrate between sand-fly vectors and mammalian hosts, adapting to changing environments by driving a regulated program of gene expression, with translation regulation playing a key role. The leishmanias encode six different paralogs of eIF4E, the cap-binding translation initiation factor. Since these vary in function, expression profile, and assemblage, it is assumed that each is assigned a specific role throughout the life cycle. Using the CRISPR-Cas9 system for Leishmania, we generated a null mutant of LeishIF4E1, eliminating both alleles. Although the mutant cells were viable, their morphology was altered and their ability to synthesize the flagellum was impaired. Elimination of LeishIF4E1 affected their protein expression profile and decreased their ability to infect cultured macrophages. Restoring LeishIF4E1 expression restored the affected features. This study highlights the importance of LeishIF4E1 in diverse cellular events during the life cycle of Leishmania.


Assuntos
Fator de Iniciação 4E em Eucariotos/deficiência , Fator de Iniciação 4E em Eucariotos/metabolismo , Deleção de Genes , Leishmania/crescimento & desenvolvimento , Leishmania/patogenicidade , Proteoma/análise , Animais , Sobrevivência Celular , Técnicas de Inativação de Genes , Concentração de Íons de Hidrogênio , Leishmania/citologia , Leishmania/genética , Macrófagos/parasitologia , Camundongos , Células RAW 264.7 , Temperatura
9.
Biomolecules ; 9(11)2019 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-31652866

RESUMO

A series of seven chalcone-thiosemicarbazones (5a-5g) were synthesized and evaluated as potential new drugs (anti-leishmanial effect). Although four of the chalcone-thiosemicarbazones are already known, none of them or any compound in this class has been previously investigated for their effects on parasites of the Leishmania genus. The compounds were prepared in satisfactory yields (40-75%) and these compounds were evaluated against promastigotes, axenic amastigotes and intracellular amastigotes of L. amazonensis after 48 h of culture. The half maximal inhibitory concentration (IC50) values of the intracellular amastigotes were determined to be in the range of 3.40 to 5.95 µM for all compounds assayed. The selectivity index showed value of 15.05 for 5a, whereas pentamidine (reference drug) was more toxic in our model (SI = 2.32). Furthermore, to understand the preliminary relationship between the anti-leishmanial activity of the chalcone-thiosemicarbazones, their electronic (σ), steric (MR) and lipophilicity (π) properties were correlated, and the results indicated that moieties with electronic withdrawing effects increase the anti-leishmanial activity. The preliminary pharmacokinetic evaluation of one of the most active compound (5e) was studied via interaction to human serum albumin (HSA) using multiple spectroscopic techniques combined with molecular docking. The results of antiparasitic effects against L. amazonensis revealed the chalcone-thiosemicarbazone class to be novel prototypes for drug development against leishmaniasis.


Assuntos
Antiprotozoários/farmacologia , Chalconas/farmacologia , Leishmania/efeitos dos fármacos , Tiossemicarbazonas/farmacologia , Animais , Antiprotozoários/química , Chalconas/química , Leishmania/crescimento & desenvolvimento , Macrófagos/efeitos dos fármacos , Macrófagos/parasitologia , Camundongos Endogâmicos BALB C , Ligação Proteica , Albumina Sérica Humana/química , Tiossemicarbazonas/química
10.
Amino Acids ; 51(10-12): 1633-1648, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31654210

RESUMO

For medical use of proteins and peptide-based drugs, it is desirable to have small biologically active sequences because they improve stability, reduce side effects, and production costs. Several plant defensins have their biological activities imparted by a sequence named γ-core. Vu-Def, a Vigna unguiculata defensin, has activity against Leishmania amazonensis, which is one etiological agent of leishmaniasis and for which new drugs are needed. Our intention was to understand if the region comprising the Vu-Def γ-core is responsible for the biological activity against L. amazonensis and to unveil its mechanism of action. Different microbiological assays with L. amazonensis in the presence of the synthetic peptide A36,42,44γ32-46Vu-Def were done, as well as ultrastructural and fluorescent analyses. A36,42,44γ32-46Vu-Def showed biological activity similar to Vu-Def. A36,42,44γ32-46Vu-Def (74 µM) caused 97% inhibition of L. amazonensis culture and parasites were unable to regrow in fresh medium. The cells of the treated parasites showed morphological alterations by ultrastructural analysis and fluorescent labelings that corroborate with the data of the organelles alterations. The general significance of our work is based on the description of a small synthetic peptide, A36,42,44γ32-46Vu-Def, which has activity on L. amazonensis and that the interaction between A36,42,44γ32-46Vu-Def-L. amazonensis results in parasite inhibition by the activation of an apoptotic-like cell death pathway.


Assuntos
Apoptose/efeitos dos fármacos , Defensinas/química , Leishmania/efeitos dos fármacos , Fragmentos de Peptídeos/farmacologia , Vigna/química , Sequência de Aminoácidos , Defensinas/farmacologia , Leishmania/crescimento & desenvolvimento , Modelos Moleculares , Fragmentos de Peptídeos/síntese química , Fragmentos de Peptídeos/química , Estrutura Secundária de Proteína , Sementes/química
11.
Artigo em Inglês | MEDLINE | ID: mdl-31608245

RESUMO

For a long time Leishmaniasis had been considered as a neglected tropical disease. Recently, it has become a priority in public health all over the world for different aspects such as geographic spread, number of population living at risk of infection as well as the potential lethality and/or the development of disfiguring lesions in the, respectively, visceral and tegumentary forms of the disease. As a result, several groups have been bending over this issue and many valuable data have been published. Nevertheless, parasite-host interactions are still not fully known and, consequently, we do not entirely understand the infection dynamics and parasite persistence. This knowledge may point targets for modulation or blockage, being very useful in the development of measures to interfere in the course of infection/ disease and to minimize the risks and morbidity. In the present review we will discuss some aspects of the Leishmania spp-mammalian host interaction in the onset of infection and after the clinical cure of the lesions. We will also examine the information already available concerning the parasite strategy to evade immune response mainly at the beginning of the infection, as well as during the parasite persistence. This knowledge can improve the conditions of treatment, follow-up and cure control of patients, minimizing the potential damages this protozoosis can cause to infected individuals.


Assuntos
Interações Hospedeiro-Parasita , Leishmania/crescimento & desenvolvimento , Leishmaniose/patologia , Animais , Modelos Animais de Doenças , Humanos , Evasão da Resposta Imune , Leishmania/imunologia , Leishmania/patogenicidade
12.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(3): 294-298, 2019 Jun 12.
Artigo em Chinês | MEDLINE | ID: mdl-31544410

RESUMO

OBJECTIVE: To compare the growth and reproduction of the promastigotes of Leishmania isolates from various endemic areas of visceral leishmaniasis in China in various culture media, so as to provide experimental evidence for selecting an appropriate medium for the culture of Leishmania. METHODS: A total of 3 × 105 promastigotes of KS-2, Cy and JIASHI-5 Leishmania isolates were inoculated into 1 mL NNN medium, 1 mL M199 medium supplemented with 20% fetal bovine serum medium, 1 mL M199 medium supplemented with 20% horse serum medium, and 1 mL brain heart infusion medium containing heme, respectively. All media were placed at 22 ℃ under a sterile condition, and the number of promastigotes was counted continuously for 8 days under a microscope. The growth curve was plotted for the three Leishmania isolates. RESULTS: The promastigotes of KS-2, Cy and JIASHI-5 Leishmania isolates all grew and reproduced in the NNN medium, the M199 medium supplemented with 20% fetal bovine serum medium, and the M199 medium supplemented with 20% horse serum medium. The number of promastigotes of KS-2, Cy and JIASHI-5 Leishmania isolates was all significantly higher in the NNN medium than in the M199 medium supplemented with 20% fetal bovine serum medium, and the M199 medium supplemented with 20% horse serum medium at various time points of culture (all P values < 0.05), and the number of promastigotes of the KS-2 isolate was all significantly greater than that of the Cy and JIASHI-5 isolates in the NNN medium, the M199 medium supplemented with 20% fetal bovine serum medium, and the M199 medium supplemented with 20% horse serum medium at various time points of culture (all P values < 0.05). In ad dition, the promastigotes of KS-2, Cy and JIASHI-5 Leishmania isolates failed to grow and reproduce in the brain heart infusion medium. CONCLUSIONS: The growth and reproduction of the promastigotes of various Leishmania isolates from various endemic areas of visceral leishmaniasis in China vary in the same culture medium, and the growth and reproduction of a Leishmania isolate vary in different culture media. The NNN medium best fits for the culture of Leishmania isolates in the endemic areas of visceral leishmaniasis in China.


Assuntos
Meios de Cultura , Leishmania , China , Meios de Cultura/química , Humanos , Leishmania/crescimento & desenvolvimento , Leishmaniose Visceral/parasitologia , Reprodução
13.
Acta Trop ; 199: 105157, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31491400

RESUMO

Leishmania (Mundinia) orientalis is a newly described species causing human leishmaniasis in Thailand whose natural vector is unknown. L. orientalis infections in sand flies and/or biting midges under laboratory conditions have not been previously investigated. In this study, the development of L. orientalis in two experimental vectors, Lutzomyia longipalpis sand flies and Culicoides sonorensis biting midges was investigated for the first time using light microscopy, scanning electron microscopy, and histological examination. The results showed that L. orientalis was unable to establish infection in Lu. longipalpis. No parasites were found in the sand fly gut 4 days post-infected blood meal (PIBM). In contrast, the parasite successfully established infection in C. sonorensis. The parasites differentiated from amastigotes to procyclic promastigotes in the abdominal midgut (AMG) on day 1 PIBM. On day 2 PIBM, nectomonad promastigotes were observed in the AMG and migrated to the thoracic midgut (TMG). Leptomonad promastigotes appeared at the TMG on day 3 PIBM. Clusters of leptomonad promastigotes and metacyclic promastigotes colonized around the stomodeal valve with the accumulation of a promastigote secretory gel-like material from day 3 PIBM onwards. Haptomonad-like promastigotes were observed from day 5 PIBM, and the proportion of metacyclic promastigotes reached 23% on day 7 PIBM. The results suggest that biting midges or other sand fly genera or species might be vectors of L. orientalis.


Assuntos
Ceratopogonidae/parasitologia , Leishmania/crescimento & desenvolvimento , Psychodidae/parasitologia , Animais , Sistema Digestório/parasitologia , Humanos , Insetos Vetores , Leishmaniose/transmissão
14.
Parasitol Res ; 118(10): 2743-2752, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31473855

RESUMO

Leishmaniasis is a neglected parasitic disease for which the current antileishmania therapeutics are hampered by drug toxicity, high cost, need for parenteral administration, increasing treatment failure rates, and emergence of drug resistance. The R&D pipeline had run fairly dry for several years, but fortunately some new drug candidates are now under (pre)clinical development. Identification of novel drugs will nevertheless remain essential to adequately sustain and improve effective disease control in the future. In this review, a package of standard and accessible R&D approaches is discussed with expansion to some alternative strategies focusing on parasite-host and vector-host interactions.


Assuntos
Antiprotozoários/farmacologia , Descoberta de Drogas , Leishmania/efeitos dos fármacos , Animais , Resistência a Medicamentos , Humanos , Leishmania/crescimento & desenvolvimento , Leishmaniose/tratamento farmacológico , Leishmaniose/parasitologia
15.
Parasitol Res ; 118(10): 3067-3076, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31392413

RESUMO

This study is a report on the anti-Leishmania activity of Morita-Baylis-Hillman (MBH) homodimers adducts against the promastigote and axenic amastigote forms of Leishmania (Leishmania) infantum and Leishmania (Leishmania) amazonensis and on the cytotoxicity of these adducts to human blood cells. Both studied homodimers, MBH 1 and MBH 2, showed activity against the promastigote forms of L. infantum and L. amazonensis, which are responsible for visceral and cutaneous leishmaniasis, respectively. Additionally, the homodimers presented biological activity against the axenic amastigote forms of these two Leishmania species. The adducts exhibited no hemolytic activity to human peripheral blood mononuclear cells or erythrocytes at the tested concentrations and achieved higher selectivity indices than amphotericin B. Evaluation of cell death by apoptosis revealed that the homodimers had better apoptosis/necrosis profiles than amphotericin B in the promastigote forms of both L. infantum and L. amazonensis. In conclusion, these Morita-Baylis-Hillman adducts had anti-Leishmania activity in an in vitro model and may thus be promising molecules in the search for new drugs to treat leishmaniasis.


Assuntos
Antiprotozoários/síntese química , Antiprotozoários/farmacologia , Leishmania/efeitos dos fármacos , Anfotericina B/farmacologia , Animais , Antiprotozoários/química , Apoptose/efeitos dos fármacos , Dimerização , Avaliação Pré-Clínica de Medicamentos , Hemólise , Humanos , Leishmania/crescimento & desenvolvimento
16.
Nat Rev Microbiol ; 17(10): 607-620, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31444481

RESUMO

Antimicrobial treatment failure threatens our ability to control infections. In addition to antimicrobial resistance, treatment failures are increasingly understood to derive from cells that survive drug treatment without selection of genetically heritable mutations. Parasitic protozoa, such as Plasmodium species that cause malaria, Toxoplasma gondii and kinetoplastid protozoa, including Trypanosoma cruzi and Leishmania spp., cause millions of deaths globally. These organisms can evolve drug resistance and they also exhibit phenotypic diversity, including the formation of quiescent or dormant forms that contribute to the establishment of long-term infections that are refractory to drug treatment, which we refer to as 'persister-like cells'. In this Review, we discuss protozoan persister-like cells that have been linked to persistent infections and discuss their impact on therapeutic outcomes following drug treatment.


Assuntos
Antiprotozoários/farmacologia , Tolerância a Medicamentos , Leishmania/efeitos dos fármacos , Plasmodium/efeitos dos fármacos , Toxoplasma/efeitos dos fármacos , Trypanosoma cruzi/efeitos dos fármacos , Variação Biológica da População , Doença de Chagas/tratamento farmacológico , Doença de Chagas/parasitologia , Humanos , Leishmania/crescimento & desenvolvimento , Leishmaniose/tratamento farmacológico , Leishmaniose/parasitologia , Malária/tratamento farmacológico , Malária/parasitologia , Plasmodium/crescimento & desenvolvimento , Toxoplasma/crescimento & desenvolvimento , Toxoplasmose/tratamento farmacológico , Toxoplasmose/parasitologia , Falha de Tratamento , Trypanosoma cruzi/crescimento & desenvolvimento
17.
Chem Biol Drug Des ; 94(6): 2004-2012, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31444858

RESUMO

Isoxazole analogues derived from the neolignans veraguensin, grandisin, and machilin G were previously synthesized with different substitution patterns through the bioisosterism strategy. These compounds were tested on intracellular amastigotes of Leishmania (Leishmania) amazonensis; the derivatives proved to be active against intracellular amastigotes, with IC50 values ranging from 0.4 to 25 µM. The most active analogues were 4', 14', 15', and 18', with IC50 values of 0.9, 0.4, 0.7, and 1.4 µM, respectively, showing high selectivity indexes (SI = 277.0; 625.0; 178.5 and 357.1). Overall, the isoxazole analogues did not induce nitric oxide (NO) production by infected cells; there was no evidence that NO influences the antileishmanial mechanism of action, except for compound 4'. Trimethoxy groups as substituents seemed to be critical for antileishmanial activity. The SAR study demonstrated that the isoxazole compounds were more active than 1,2,3-triazole compounds with the same substitution pattterns, demonstrating the importance of the bioisosterism strategy in drug design.


Assuntos
Antiprotozoários/farmacologia , Furanos/química , Isoxazóis/química , Leishmania/efeitos dos fármacos , Lignanas/química , Triazóis/química , Animais , Antiprotozoários/química , Desenho de Fármacos , Feminino , Concentração Inibidora 50 , Isoxazóis/farmacologia , Leishmania/crescimento & desenvolvimento , Estágios do Ciclo de Vida/efeitos dos fármacos , Macrófagos Peritoneais/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico/metabolismo , Relação Estrutura-Atividade
18.
Free Radic Biol Med ; 143: 341-353, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31446054

RESUMO

Leishmania amazonensis is one of leishmaniasis' causative agents, a disease that has no cure and leads to the appearance of cutaneous lesions. Recently, our group showed that heme activates a Na+/K+ ATPase in these parasites through a signaling cascade involving hydrogen peroxide (H2O2) generation. Heme has a pro-oxidant activity and signaling capacity, but the mechanism by which this molecule increases H2O2 levels in L. amazonensis has not been elucidated. Here we investigated the source of H2O2 stimulated by heme, ruling out the participation of mitochondria and raising the possibility of a role for a NADPH oxidase (Nox) activity. Despite the absence of a classical Nox sequence in trypanosomatid genomes, L. amazonensis expresses a surface ferric iron reductase (LFR1). Interestingly, Nox enzymes are thought to have evolved from ferric iron reductases because they share same core domain and are very similar in structure. The main difference is that Nox catalyses electron flow from NADPH to oxygen, generating reactive oxygen species (ROS), while ferric iron reductase promotes electron flow to ferric iron, generating ferrous iron. Using L. amazonensis overexpressing or knockout for LFR1 and heterologous expression of LFR1 in mammalian embryonic kidney (HEK 293) cells, we show that this enzyme is bifunctional, being able to generate both ferrous iron and H2O2. It was previously described that protozoans knockout for LFR1 have their differentiation to virulent forms (amastigote and metacyclic promastigote) impaired. In this work, we observed that LFR1 overexpression stimulates protozoan differentiation to amastigote forms, reinforcing the importance of this enzyme in L. amazonensis life cycle regulation. Thus, we not only identified a new source of ROS production in Leishmania, but also described, for the first time, an enzyme with both ferric iron reductase and Nox activities.


Assuntos
FMN Redutase/metabolismo , Peróxido de Hidrogênio/metabolismo , Ferro/metabolismo , Leishmania/enzimologia , Leishmaniose/parasitologia , NADPH Oxidases/metabolismo , Proteínas de Protozoários/metabolismo , Células HEK293 , Heme/metabolismo , Humanos , Leishmania/crescimento & desenvolvimento , Leishmaniose/metabolismo , Mitocôndrias/metabolismo , Mitocôndrias/parasitologia , NADPH Oxidases/genética , Oxirredução , Proteínas de Protozoários/genética
19.
PLoS Pathog ; 15(7): e1007982, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31356625

RESUMO

To colonize phagocytes, Leishmania subverts microbicidal processes through components of its surface coat that include lipophosphoglycan and the GP63 metalloprotease. How these virulence glycoconjugates are shed, exit the parasitophorous vacuole (PV), and traffic within host cells is poorly understood. Here, we show that lipophosphoglycan and GP63 are released from the parasite surface following phagocytosis and redistribute to the endoplasmic reticulum (ER) of macrophages. Pharmacological disruption of the trafficking between the ER and the Golgi hindered the exit of these molecules from the PV and dampened the cleavage of host proteins by GP63. Silencing by RNA interference of the soluble N-ethylmaleimide-sensitive-factor attachment protein receptors Sec22b and syntaxin-5, which regulate ER-Golgi trafficking, identified these host proteins as components of the machinery that mediates the spreading of Leishmania effectors within host cells. Our findings unveil a mechanism whereby a vacuolar pathogen takes advantage of the host cell's secretory pathway to promote egress of virulence factors beyond the PV.


Assuntos
Interações Hospedeiro-Parasita/fisiologia , Leishmania/fisiologia , Leishmania/patogenicidade , Proteínas de Protozoários/fisiologia , Fatores de Virulência/fisiologia , Animais , Retículo Endoplasmático/parasitologia , Feminino , Glicoesfingolipídeos/fisiologia , Humanos , Leishmania/crescimento & desenvolvimento , Leishmaniose/parasitologia , Metaloendopeptidases/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Fagócitos/parasitologia , Fagocitose , Fagossomos/parasitologia , Proteínas Qa-SNARE/fisiologia , Proteínas R-SNARE/fisiologia , Via Secretória , Vacúolos/parasitologia , Virulência
20.
Curr Opin Microbiol ; 52: 70-76, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31229882

RESUMO

The inflammasomes are multi-molecular platforms that are activated in host cell cytoplasm when the innate immune cells are infected with pathogens or exposed to damage signals. Many independent groups reported that Leishmania infection trigger activation of the NLRP3 inflammasome in macrophages for restriction of intracellular parasite replication. Accordingly, Leishmania can dampen NLRP3 activation as an evasion strategy. In vivo, the NLRP3 inflammasome can promote parasite clearance, but the failure to eliminate parasites in the tissues together with sustained inflammasome activation can promote IL-1ß-mediated disease pathology. In this review, we discuss the recent data regarding activation of the NLRP3 inflammasome in response to Leishmania and the beneficial and detrimental effects of the inflammasome during development of Leishmaniasis.


Assuntos
Interações Hospedeiro-Patógeno , Evasão da Resposta Imune , Imunidade Inata , Inflamassomos/metabolismo , Leishmania/imunologia , Animais , Humanos , Leishmania/crescimento & desenvolvimento , Leishmaniose/parasitologia , Leishmaniose/patologia , Macrófagos/imunologia , Macrófagos/parasitologia
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