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Trypanosoma cruzi is the etiologic agent of Chagas’ disease, a debilitating and mortal zoonotic illness that threatens the lives of several millions of people in the American continent. The acute phase is underdiagnosed and there is no curative treatment for the chronic stage. This unicellular pathogen colonizes cells from different tissues wherein it replicates and remains hidden from immune recognition. There is an urgent need to develop new chemotherapy, which requires robust screening bioassays against the amastigote, a proliferative and drug-resilient intracellular stage of the parasite. With this aim, here we present the generation and characterization of a bioluminescent reporter cell line of the highly infective strain Dm28c from T. cruzi. Constitutive and stable expression of the reporter gene (a red-shifted luciferase from Photinus pyralis) was achieved in the different developmental stages of the pathogen. The transgene did not affect parasite growth and differentiation. The bioluminescence signal displayed a linear correlation with the parasite number. A 96-well screening assay against the amastigote stage has been established and validated with a small compound library. The bioassay proved sensitive, robust, and amenable for high throughput applications. The reporter cell line may prove highly valuable to address different goals in the early phase of the drug discovery process against American trypanosomiasis.

Key Clinical Message We report a case of 45‐year‐old farmer who presented with solitary crateriform non healing ulcer with crust over left dorsal hand. FNAC of lesion showed intracellular round to oval amastigotes within macrophage on giemsa stain. This simple diagnostic method could be utilized as a diagnostic tool in resource poor setting.

The bioactive compounds present in the edible products of the olive tree have been extensively studied and their favorable effects on various disease risk factors have been demonstrated. The aim of this study was to perform a comparative analysis of the anti-leishmanial effects of total phenolic fractions (TPFs) derived from extra virgin olive oil with different phenolic contents and diverse quantitative patterns. Moreover, the present study investigated their association with miltefosine, a standard anti-leishmanial drug, against both extracellular promastigotes and intracellular amastigotes of a viscerotropic and a dermotropic Leishmania strain. The chemical compositions of TPFs were determined by high performance liquid chromatography with diode array detection (HPLC-DAD). Analysis of parasite growth kinetics, reactive oxygen species production and apoptotic events were determined by microscopy and flow cytometry. Our results revealed that the presence of oleacein (OLEA) and oleocanthal (OLEO) secoiridoids enhances the anti-leishmanial effect of TPF. The association between TPFs and miltefosine was suggested as being additive in Leishmania infantum and Leishmania major promastigotes, and as antagonistic in intracellular amastigotes, as was evaluated with the modified isobologram method. The obtained data verified that TPFs are bioactive dietary extracts with a strong anti-leishmanial activity and highlighted that fractions that are richer in OLEA and OLEO phenolic compounds possess stronger inhibitory effects against parasites. This study may contribute to improving the therapeutic approaches against leishmaniasis. [ABSTRACT FROM AUTHOR]

Leishmaniasis is considered to be one of the most neglected tropical diseases affecting humans and animals around the world. Due to the absence of an effective vaccine, current treatment is based on chemotherapy. However, the continuous appearance of drug resistance and therapeutic failure (TF) lead to an early obsolescence of treatments. Identification of the factors that contribute to TF and drug resistance in leishmaniasis will constitute a useful tool for establishing future strategies to control this disease. In this manuscript, we evaluated the transcriptomic changes in the intracellular amastigotes of the Leishmania infantum parasites isolated from patients with leishmaniasis and TF at 96 h post-infection of THP-1 cells. The adaptation of the parasites to their new environment leads to expression alterations in the genes involved mainly in the transport through cell membranes, energy and redox metabolism, and detoxification. Specifically, the gene that codes for the prostaglandin f2α synthase seems to be relevant in the pathogenicity and TF since it appears substantially upregulated in all the L. infantum lines. Overall, our results show that at the late infection timepoint, the transcriptome of the parasites undergoes significant changes that probably improve the survival of the Leishmania lines in the host cells, contributing to the TF phenotype as well as drug therapy evasion. [ABSTRACT FROM AUTHOR]

Leishmaniasis is considered to be one of the most neglected tropical diseases affecting humans and animals around the world. Due to the absence of an effective vaccine, current treatment is based on chemotherapy. However, the continuous appearance of drug resistance and therapeutic failure (TF) lead to an early obsolescence of treatments. Identification of the factors that contribute to TF and drug resistance in leishmaniasis will constitute a useful tool for establishing future strategies to control this disease. In this manuscript, we evaluated the transcriptomic changes in the intracellular amastigotes of the Leishmania infantum parasites isolated from patients with leishmaniasis and TF at 96 h post-infection of THP-1 cells. The adaptation of the parasites to their new environment leads to expression alterations in the genes involved mainly in the transport through cell membranes, energy and redox metabolism, and detoxification. Specifically, the gene that codes for the prostaglandin f2α synthase seems to be relevant in the pathogenicity and TF since it appears substantially upregulated in all the L. infantum lines. Overall, our results show that at the late infection timepoint, the transcriptome of the parasites undergoes significant changes that probably improve the survival of the Leishmania lines in the host cells, contributing to the TF phenotype as well as drug therapy evasion.

Leishmaniasis is an infectious parasitic disease that is caused by protozoa of the genus Leishmania, a member of the Trypanosomatidae family. Leishmaniasis is classified by the World Health Organization as a neglected tropical disease that is responsible for millions of deaths worldwide. Although there are many possible treatments for leishmaniasis, these treatments remain mostly ineffective, expensive, and long treatment, as well as causing side effects and leading to the development of resistance. For novel and effective treatments to combat leishmaniasis, many research groups have sought to utilize natural products. In addition to exhibiting potential as therapeutic compounds, natural products may also contribute to the development of new drugs based on their chemical structures. This review presents the most promising natural products, including crude extracts and isolated compounds, employed against Leishmania spp.

A 5-y-old male Poodle mix was presented with intermittent vomiting, anorexia, and weight loss. Physical examination revealed emaciation, lethargy, dehydration, hypothermia, respiratory distress, and splenomegaly. Based on clinicopathologic, serologic, and parasitologic findings, diagnoses of severe leishmaniosis and dirofilariasis were made. Extracellular, intraneutrophilic, and intramonocytic Leishmania amastigotes were observed on blood smear and buffy coat smear examination. In blood smears, 0.2% of neutrophils were observed to be infected; in buffy coat smears, 0.5% of neutrophils and 0.1% of monocytes were found to be infected. Leishmania amastigotes were also found engulfed by eosinophils and neutrophil precursors in bone marrow aspiration cytology. The detection of Leishmania amastigotes in blood smears is rare, and the clinical significance is uncertain. In circulating blood, Leishmania amastigotes are primarily found phagocytized by neutrophils. Although debatable, there is growing evidence that neutrophils are used as carriers enabling the "silent entry" of the protozoa into macrophages ("Trojan horse" theory). To date, cytologic screening of blood smears for the diagnosis of canine leishmaniosis is not a routine practice. Clinical pathologists and practitioners should be aware that Leishmania amastigotes may be present in neutrophils and less frequently monocytes during blood smear evaluation; neutrophil precursors and eosinophils may also be parasitized in bone marrow specimens. [ABSTRACT FROM AUTHOR]

Key Clinical Message: We report a case of 45‐year‐old farmer who presented with solitary crateriform non healing ulcer with crust over left dorsal hand. FNAC of lesion showed intracellular round to oval amastigotes within macrophage on giemsa stain. This simple diagnostic method could be utilized as a diagnostic tool in resource poor setting. [ABSTRACT FROM AUTHOR]

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.

Since the discovery of the28 first drugs used in leishmaniasis treatment up to now, the search for compounds with anti- Leishmania activity without toxic effects and able to overcome the emergency of resistant strains remains a major goal to combat this neglected disease. With this in mind, in the present work, we evaluated the effects of the calpain inhibitor MDL28170 on the interaction process of Leishmania amazonensis promastigote forms with murine peritoneal macrophages and on the intracellular amastigotes. Our results showed that the calpain inhibitor MDL28170 at 15 and 30 μM significantly reduced the interaction process of promastigotes with macrophages by 16% and 41%, respectively. The inhibitor was also able to drastically reduce the number of infected macrophages in a time- and dose-dependent manner: after only 24 h, MDL28170 was able to significantly diminish the infection rate, presenting an IC 50 value of 18.2 μM for amastigotes. The treatment with MDL28170 did not alter the nitric oxide production, but the production of TNF-α was significantly raised. Altogether, the results presented here contribute to the search of new proteolytic inhibitors able to act in a selective and effective manner against the diseases caused by trypanosomatids. [ABSTRACT FROM AUTHOR]

Actualmente la quimioterapia de la leishmaniasis es promisoria, sin embargo aun no se dispone de un medicamento adecuado. Varias quinolinas sustituidas han presentado actividad in vitro contra agentes causales de leishmaniasis cutánea, leishmaniasis visceral, tripanosomiasis africana y enfermedad de Chagas. En este trabajo se sintetizan seis 2-arilquinolinas derivadas de la galipeina mediante condensación de Perkin a partir de quinaldina y aldehídos aromáticos. La actividad leishmanicida se evalúa en amastigotes axénicos y la actividad citotóxica en células U-937. Todos los compuestos muestran ser activos contra leishmania panamensis pero también contra células mamíferas. Los compuestos estirilquinolinas 2-[(E)-2-(2,5-dimetoxifenil)etenil]quinolina (1), 2-[(E)-2-(2,3-dimetoxifenil)etenil]quinolina (2) y N-{4-[(E)-2-quinolin-2-iletenil]fenil}acetamida (3) son mas activos sobre amastigotes axénicos (CE50 = 3,7; 4,5 y 19,1μg/mL) e intracelulares (CE50 = 1,4; 1,8 y 1,7μg/mL), en comparación con los derivados hidrogenados 2-[2-(2,5-dimetoxifenil)etil]quinolina (1a), 2-[2-(2,3-dimetoxifenil)etil]quinolina (2a) y N-[4-(2-quinolin-2-iletil)fenil]acetamida (3a) (CE50= 31,1; 23,6 y 59,3μg/mL). Todos los compuestos muestran también actividad contra células U-937 con CE50 de 3,7; 6,2 y 4,5μg/mL para las estirilquinolinas 1, 2 y 3, respectivamente y CE50 de 16,0; 12,9 y 20,2μg/mL para los derivados hidrogenados 1a, 2a y 3a, respectivamente. Aunque el proceso de hidrogenación produjo una disminución tanto de la actividad leishmanicida como de la actividad citotóxica, la actividad leishmanicida mostrada por los compuestos de tipo 2-estirilquinolinas les confiere un potencial como moléculas candidatas para el desarrollo de compuestos anti-leishmania.The search of new treatments for leishmaniasis is an active task nowadays, since there is a lack of non-toxic, cheap and non-resistant medication. In the literature several quinolines have shown in vitro activity against agents of cutaneous leishmaniasis, visceral leishmaniasis, African trypanosomiasis and Chagas diseases. Six 2-styrylquinolines derived from galipeine were synthesized by Perkin condensation of quinaldine with aromatic aldehydes. Leishmanicidal activity was estimated for leishmania panamensis at the amastigote form and cytotoxic activity against U-937 cells. All compounds showed activity against both L. panamensis and U-937 cells. (E)-2-(2,5-dimethoxyphenyl)ethenyl)quinoline (1), (E)-2-(2,3-dimethoxyphenyl)ethenyl)quinoline (2) and (E)-N-[4-(2-quinolin-2-yl-ethenyl)phenyl]acetamide (3) were more active against axenic (EC50= 3.7, 4.5 and 19.1μg/mL) and intracellular amastigotes (EC50= 1.4, 1.8 and 1.7μg/ml, respectively), in comparison with hydrogenated derivatives 2-[2-(2,5-dimethoxyphenyl)ethyl]quinoline (1a), 2-[2-(2,3-dimethoxyphenyl)ethyl]quinoline (2a) and N-[4-(2-quinolin-2-ylethyl)phenyl]acetamide (3a) (CE50= 31.1, 23.6 and 59.3μg/mL, respectively). All compounds were also active against the U-937 cells. Styrylquinolines 1, 2 and 3 showed a LC50 of 3.7, 6.2 and 4.5μg/mL, respectively and the hydrogenated derivatives 1a, 2a and 3a showed a LC50 of 16.0. 12.9 and 20.2μg/mL, respectively. Although hydrogenation reduced the leishmanicidal and cytotoxic activities, the activity showed against leishmania parasites suggests this compound series has potential as drug candidates for the treatment of leishmaniasis.

Extracts of Serjania lethalis A. St.-Hil leaves and stems were tested in order to identify potential agents against Leishmania amazonensis . The hexane fraction (HF) and dichloromethane subfractions (DDF and MDF) showed leishmanicidal effect. The anti-promastigote IC 50 values were 10.29 (HF), 11.41 (DDF) and 28.33 μg ⁄ mL (MDF); whereas those against amastigote were 7.2 (HF), 8.1 (DDF) and 6.5 μg ⁄ mL (MDF). Among the fractions and subfractions assayed, only HF altered the cell cycle of the parasite, increasing 3-fold the number of cells in the sub-G0/G1 phase. HF also changed the parasite mitochondrial membrane potential (ΔΨm) and the percentage of annexin-V-propidium iodide positive promastigotes. Our evaluations of the IC 50 values showed that HF, DDF and MDF decreased NO production in infected macrophages stimulated with IFN-γ and LPS. Moreover, HF increased the production of TNF-α in Leishmania infected macrophages. This paper reports for the first time the leishmanicidal activity of extracts and fractions of Serjania lethalis leaves and also characterizes its leishmanicidal and immunomodulatory properties. [ABSTRACT FROM AUTHOR]

The anti-Trypanosoma cruzi activity of natural products isolated from Azorella compacta was evaluated, with particular emphasis on their effect against intracellular amastigotes. Five diterpenoids from A. compacta derived from mulinane and azorellane were isolated and identified. Only two products, named azorellanol (Y-2) and mulin-11,3-dien-20-oic acid (Y-5), showed trypanocidal activity against all stages of T. cruzi including intracellular amastigotes. At 10 µM, these compounds displayed a strong lytic activity. It ranged from 88.4 ± 0.6 to 99.0 ± 1 % for all strains and stages evaluate, with an IC50 /18 h values of 20-84 µM and 41-87 µM, respectively. The development of intracellular amastigotes was also inhibited by nearly 60% at 25 µM. The trypanocidal molecules Y-2 and Y-5 did show different degrees of cytotoxicity depending on the cell line tested, with an IC50 /24 h ranging from 33.2 to 161.2 µM. We evaluated the effect of diterpenoids against intracellular T. cruzi forms by immunofluorescent identification of a specific membrane molecular marker (Ssp-4 antigen) of the T. cruzi amastigote forms. The accuracy and reproducibility of the measurements were found to be outstanding when examined by confocal microscopy.

Abstract: Protozoan parasites of the genus Leishmania are important human pathogens that cycle between an extracellular promastigote stage residing in the sandflies and an intracellular amastigote stage colonizing the phagolysosomal compartment of the mammalian macrophages. Here, we used the isobaric tagging method to quantify the global proteomic differences between the promastigotes and the intracellular amastigotes of three different Leishmania donovani clones derived from the THP-1 human macrophage cell line. We identified a substantial number of differentially modulated proteins involved in nutrient acquisition and energy metabolism, cell motility and cytoskeleton, transport, cell signaling and stress response. Proteins involved in vesicular trafficking and endocytosis like the rab7 GTP binding protein, GTP-binding proteins of the Ras superfamily and developmentally regulated GTP-binding protein 1 revealed enhanced expression and also a putative dynein heavy chain protein was found to be up-regulated in the amastigotes and it probably has a role in cargo transport inside the vesicles. Significantly, in the amastigotes the expression of a protein involved in glucose transport was increased eight to fifteen-fold, whereas concentrations of several proteins associated with cell motility and cytoskeleton were reduced. Thus, the quantitative proteomic analysis of L. donovani isolates sheds light on some novel proteins that may have a role in Leishmania differentiation and intracellular survival. [Copyright &y& Elsevier]

Abstract: In this work a simple and novel method to evaluate the efficacy of compounds on intracellular Leishmania amastigotes by using a fluorometric assay has been developed. The new method is sensitive, easy to perform and scalable for high throughput and therefore it could be validated for screening of new anti-leishmanial agents. [Copyright &y& Elsevier]

Abstract: Leishmania parasites cycle between the alimentary tract of a sandfly vector as free-living promastigotes and the acidified phagolysosomes of the vertebrate host macrophage as aflagellated amastigotes. The differentiation process can be mimicked in host-free culture by switching promastigotes (e.g. 25°C, neutral pH) to a phagolysosomal-like environment (e.g. 37°C, acidic pH and 5% CO2) for certain, but not all Leishmania species. Axenically grown amastigotes have been shown to share several morphological and biochemical characteristics with macrophage-derived intracellular amastigotes. In this study, we used a DNA oligonucleotide full-genome array to compare global RNA expression profiling of Leishmania infantum axenic amastigotes to intracellular amastigotes derived from infected macrophages. In general, 40% more genes (518 genes vs. 309 genes) were found upregulated in axenic amastigotes compared to intracellular amastigotes. Comparisons in expression profiling between axenic amastigotes and intracellular amastigotes revealed substantial differences in regulated mRNA abundance. Remarkably, among the differentially upregulated transcripts only 12% were common to both amastigote preparations. The major differences between axenic and intracellular amastigotes were observed in metabolic process, especially in fatty acid metabolism, in intracellular transport and membrane vesicular fusion, in proteolysis, in the number and type of protein kinases and RNA binding proteins and in the response to oxidative stress. These findings highlight the importance of the host macrophage in driving the parasite to specific adaptations, which consequently result in highly regulated changes in gene expression. [Copyright &y& Elsevier]

Background: Cutaneous leishmaniasis is caused by Leishmania spp., and its treatment is limited. The β-carbolines have shown activity against kinetoplastids. Aim: To evaluate the activity and effects of the β-carbolines, N-{2-[(4,6-bis(isopropylamino)-1,3,5-triazin-2-yl)amino]ethyl}-1-(4-methoxyphenyl)-β-carboline-3-carboxamide ( RCC) and N-benzyl-1-(4-methoxy)phenyl-9H-beta-carboline-3-carboxamide (C5) , against L. amazonensis intracellular amastigotes and to suggest their mechanism of action. Methods: We analyzed the activity and cytotoxicity of β-carbolines and the morphological alterations by electron microscopy. Mitochondrial membrane potential, production nitric oxide, reactive oxygen species, lipidic bodies, autophagic vacuoles and ATP were also evaluated. Results & conclusion: The results showed that RCC and C5 are active against intracellular amastigotes and were able to induce oxidative stress and ultrastructural alterations such as accumulation of lipid bodies and autophagic vacuoles, leading to parasite death.

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. [ABSTRACT FROM AUTHOR]

High content analysis enables automated, robust, and unbiased evaluation of in vitro Leishmania infection. Here, we describe a protocol based on the infection of THP-1 macrophages with Leishmania promastigotes and the quantification of parasite load by high content analysis. The technique is capable of detecting and quantifying intracellular amastigotes, providing a multiparametric readout of the total number of cells, ratio of infected cells, total number of parasites, and number of parasites per infected cells. The technique can be used to quantitate infection of any Leishmania species in virtually all types of permissive host cells and can be applied to quantification of drug activity and studies of the Leishmania intracellular life cycle stage.