Comparison of biosynthetic zinc oxide nanoparticle and glucantime cytotoxic effects on Leishmania major (MRHO/IR/75/ER)

Currently, zinc oxide (ZnO) particles are used in nanotechnology to destroy a wide range of microorganisms. Although pentavalent antimony compounds are used as antileishmanial drugs, they are associated with several limitations and side effects. Therefore, it is always desirable to try to find new and effective treatments. The aim of this research is to determine the antileishmanial effect of ZnO particles in comparison to the Antimoan Meglumine compound on promastigotes and amastigotes of Leishmania major (MRHO/IR/75/ER). After the extraction and purification of macrophages from the peritoneal cavity of C57BL/6 mice, L. major parasites were cultured in Roswell Park Memorial Institute-1640 culture medium containing fetal bovine serum (FBS) 10% and antibiotic. In this experimental study, the effect of different concentrations of nanoparticles was investigated using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) colorimetric method, in comparison to the glucantime on promastigotes, amastigotes and healthy macrophages in the culture medium. The amount of light absorption of the obtained color from the regeneration of tetrazolium salt to the product color of formazan by the parasite was measured by an enzyme-linked immunosorbent assay (ELISA) reader, and the IC50 value was calculated. IC50 after 24 h of incubation was calculated as IC50 = 358.6 µg/mL. The results showed, that the efficacy of ZnO nanoparticles was favorable and dose-dependent. The concentration of 500 µg/mL of ZnO nanoparticles induced 84.67% apoptosis after 72. Also, the toxicity of nanoparticles was less than the drug. Nanoparticles exert their cytotoxic effects by inducing apoptosis. They can be suitable candidates in the pharmaceutical industry in the future.

Antileishmanial effect of podophyllotoxin and podophyllin on Leishmania major in vitro and in vivo

Therapeutic research is very important in the prevention and treatment of leishmaniasis due to problems such as drug resistance, scarring and disease recurrence. The aim of this study was to determine how Leishmania major responds to the anti-leishmaniasis properties of podophyllotoxin and podophyllin. Cultured Leishmania promastigotes were exposed to different concentrations of podophyllotoxin and podophyllin for 24 and 48 h. Then, during the animal phase, Balb/c mice were experimentally injected with Leishmania promastigotes. After wounding, the effects of 0.5% podophyllotoxin and 25% podophyllin on reducing wound diameter and the number of amastigotes in the wound were evaluated. Podophyllotoxin and podophyllin were 83% and 59% lethal to Leishmania major promastigotes at the highest concentrations (200 µg/ml) and time (48 h). In the in vivo study, the mean lesion diameter at the end of treatment in the negative control group was 15.10 mm compared to 14.21 mm and 11.55 mm in the 25% podophyllin and 0.5% podophyllotoxin groups, respectively. Although both agents reduced the size of mice wounds and the number of amastigotes in the wounds, podophyllotoxin was more effective in this regard. Based on the results, podophyllotoxin and podophyllin can be used as leishmaniasis drugs after further research.

Graphical abstract

Recognition of Immunoreactive Proteins in Leishmania infantum Amastigote-Like and Promastigote Using Sera of Visceral Leishmaniasis Patients: a Preliminary Study

PURPOSE

Visceral leishmaniasis (VL) is a systemic and parasitic disease that is usually fatal if left untreated. VL is endemic in different parts of Iran and is caused mainly by Leishmania infantum. This study aimed to recognition immunoreactive proteins in amastigote-like and promastigote stages of L. infantum (Iranian strain) by antibodies present in the sera of VL patients.

METHODS

Total protein extract from amastigote-like and promastigote cells was separated by two-dimensional electrophoresis (2DE). To detect the immunoreactive proteins, 2DE immunoblotting method was performed using different pools of VL patients' sera.

RESULTS

Approximately 390 and 430 protein spots could be separated in 2DE profiles of L. infantum amastigote-like and promastigote stages, respectively. In immunoblotting method, approximately 295 and 135 immunoreactive proteins of amastigotes-like reacted with high antibody titer serum pool and low antibody titer serum pool, respectively. Approximately 120 and 85 immunoreactive proteins of promastigote extract were recognized using the high antibody titer sera pool and low antibody titer sera, respectively.

CONCLUSION

The present study has recognized a number of antigenic diversity proteins based on the molecular weight and pH in amastigote-like and promastigote stages of L. infantum. These results provide us a new concept for further analysis development in the field of diagnosis biomarkers and vaccine targets.

Anti-Leishmania major activity of Calotropis procera extract by increasing ROS production and upregulating TNF-α, IFN-γ and iNOS mRNA expression under in vitro conditions

BACKGROUND

Leishmaniasis, caused by protozoan parasites of the genus Leishmania, is a neglected tropical disease with 700,000 to 1,000,000 global new cases annually. Adverse effects associated with expense, long-term treatment and drug resistance have made conventional therapies unfavorable, encouraging the search for alternative drugs based on plant products. In this study, the effect of Calotropis procera (Asclepiadaceae) extract against viability of promastigotes and amastigotes of Leishmania major was evaluated in vitro.

METHODS

The extract from the leaves of C. procera seedlings was prepared using a methanol maceration method. The colorimetric cell viability 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the growth-inhibitory effect of the extract on promastigotes. The level of reactive oxygen species (ROS) in promastigote cultures was determined after treatment with the extract using the 2',7'-dichlorofluorescein diacetate (DCFH-DA) method and compared with untreated cultures (control). After exposure to the extract the expression levels of tumor necrosis factor-α (TNF-α), interferon gamma (IFN-γ) and inducible nitric oxide synthase (iNOS) genes were determined and compared to control in peripheral blood mononuclear cells (PBMCs) infected with L. major.

RESULTS

Based on the MTT assay, the C. procera extract significantly reduced the proliferation of L. major promastigotes with IC50 values of 377.28 and 222.44 μg/mL for 24 and 72 h, respectively (p < 0.01). After treatment with 222.44 and 377.28 μg/mL of C. procera extract, ROS production in L. major promastigote cultures increased 1.2- to 1.65-fold and 2- to 4-fold compared to the control, respectively (p < 0.05). C. procera extract induced significant increases in gene expression of TNF-α (2.76-14.83 fold), IFN-γ (25.63-threefold) and iNOS (16.32-3.97 fold) in infected PBMCs compared to control (p < 0.01).

CONCLUSIONS

On the basis of its anti-leishmanial activity, C. procera can be considered as a promising new plant source for the potential treatment of leishmaniasis.

Phytochemical study of Seriphidium khorassanicum (syn. Artemisia khorassanica) aerial parts: sesquiterpene lactones with anti-protozoal activity

Two new eudesmane-type sesquiterpene lactones, 1β,3α,8α-trihydroxy-11β,13-dihydroeudesma-4(15)-en-12,6α-olide (1) and 1β,4α,8α-trihydroxy-11β,13-dihydroeudesma-12,6α-olide (2), and an unprecedented elemane-type sesquiterpene lactone, 1β,2β,8α-trihydroxy-11β,13-dihydroelema-12,6α-olide (3) along with a known eudesmanolide artapshin (4) were isolated from Seriphidium khorassanicum. Structures were elucidated by NMR, HR-ESI-MS, and ECD spectral data analysis. The anti-protozoal activity was evaluated against Leishmania major promastigotes and amastigote-infected macrophages. They showed dose- and time-dependent activity against L. major amastigotes with IC50 values in the range of 4.9 to 25.3 μM being favourably far below their toxicity against normal murine macrophages with CC50 values ranging from 432.5 to 620.7 μM after 48 h of treatment. Compound 3 exhibited the strongest activity and the highest selectivity index (SI) with IC50 of 4.9 ± 0.6 μM and SI of 88.2 comparable with the standard drug, meglumine antimoniate (Glucantime), with IC50 and SI values of 15.5 ± 2.1 μM and 40.0, respectively.

Detergent-free parasite transformation and replication assay for drug screening against intracellular Leishmania amastigotes

Leishmaniasis is an infectious disease caused by protozoan species in the genera Leishmania and Endotrypanum. Current antileishmanial drugs are limited due to adverse effects, variable efficacy, the development of resistant parasites, high cost, parenteral administration and lack of availability in endemic areas. Therefore, active searching for new antileishmanial drugs has been done for years, mainly by academia. Drug screening techniques have been a challenge since the intracellular localization of Leishmania amastigotes implies that the host cell may interfere with the quantification of the parasites and the final estimation of the effect. One of the procedures to avoid host cell interference is based on its detergent-mediated lysis and subsequent transformation of viable amastigotes into promastigotes, their proliferation and eventual quantification as an axenic culture of promastigotes. However, the use of detergent involves additional handling of cultures and variability. In the present work, cultures of intracellular amastigotes were incubated for 72 h at 26 °C after exposure to the test compounds and the transformation and proliferation of parasites took place without need of adding any detergent. The assay demonstrated clear differentiation of negative and positive controls (average Z´ = 0.75) and 50% inhibitory concentrations of compounds tested by this method and by the gold standard enumeration of Giemsa-stained cultures were similar (p = 0.5002) and highly correlated (r = 0.9707). This simplified procedure is less labor intensive, the probability of contamination and the experimental error are reduced, and it is appropriate for the automated high throughput screening of compounds.

Synthesis, biological assessment, and computational investigations of nifedipine and monastrol analogues as anti-leishmanial major and anti-microbial agents

Leishmaniasis includes a range of parasitic diseases caused by numerous types of the protozoan kinetoplastid parasite. Fungal and bacterial pathogens have led to infectious illnesses causing some main public health problem in current years. A series of dihydropyridine and tetrahydropyrimidine derivatives having fluoro, bromo, and nitro substituents at para-phenyl ring on C4 of dihydropyridine and tetrahydropyrimidine rings were synthesized. Then, anti-leishmanial and antimicrobial potencies of compounds were assessed. All compounds were synthesized via Hantzsch and Biginelli reactions. All derivatives were evaluated for their anti-leishmanial and antimicrobial activities. Moreover, docking and molecular dynamics simulation calculations of the compounds in PRT1 binding site were performed to report the results of anti-leishmanial and antimicrobial activities. Compounds 4a and 4b showed the highest anti-amastigote and anti-promastigote activities. Compound 4a revealed the highest antimicrobial activity against E. coli, P. aeruginosa, and C. albicans strains. In addition, compound 4c showed the highest activity against S. aureus. The fluoro, bromo, and nitro substituents in para-position of phenyl group at C4 of dihydropyridine and tetrahydropyrimidine moieties as well as the bulk and length of the chain linking to the ester moieties are essential for anti-leishmanial and anti-microbial activities of these derivatives. Low cytotoxicity was shown by most of derivatives against macrophages. The molecular docking studies were in agreement with in vitro assay. Moreover, hydrogen binds, RMSF, RMSD, and Rg, strongly showed the steady binding of 4a and 4b compounds in PRT1 active site.

In vitro and in vivo antileishmanial effects of Nectaroscordum koelzi extract against Leishmania major

Due to the increasing resistance to common medicinal compounds, the use of medicinal plants has received special attention. Therefore, the current survey was designed to study the antileishmanial effects of Nectaroscordum koelzi Trautv. methanolic extract against Leishmania major. In this study, after preparing the methanolic extract of N. koelzi, its effect on the amastigotes of L. major and triggering the nitric oxide (NO) were measured. Then, the in vivo effect of the methanol extract on cutaneous leishmaniasis in mice was evaluated. The best anti-amastigote effect was for the methanol extract of N. koelzi along with meglumine antimony with 50% inhibitory concentrations value of 17.4 μg/ml (p < 0.001). The 50% cytotoxic concentrations values of methanol extract, meglumine antimoniate, and methanol extract + meglumine antimoniate were 596.3, 784.6, and 296.4 µg/ml, respectively. Macrophages treated with the methanolic extract markedly (p < 0.001) induced the release of nitric oxide. After 28 days of treatment, lesions were completely (p < 0.001) healed in mice treated with the methanolic extract (100 mg/kg) + meglumine antimoniate (25 mg/kg). N. koelzi methanolic extract mainly in combination with meglumine antimoniate showed favorable antileishmanial effects on L. major, concluding that the methanolic extract of N. koelzi can be used for the production of new leishmanicidal agents agaist cutaneous leishmaniasis. Although we revealed that NO trigerring and inhibition of infection in host cells are the antileishmanial mechanism action of N. koelzi methanolic extract, more studies must be performed to clear the mechanisms and its safety.

Leishmanicidal and immunomodulatory activities of the formononetin (a natural isoflavone) against Leishmania tropica

OBJECTIVE

This work aimed to examine the leishmanicidal, cellular mechanisms and cytotoxicity effects of formononetin (FMN), a natural isoflavone, against Leishmania tropica. We used the MTT assay to determine the leishmanicidal effects of FMN against promastigotes and its cytotoxicity effects on J774-A1 macrophage cells. The Griess reaction assay and quantitative real-time PCR were used to determine the nitric oxide (NO) and the mRNA expression levels of IFN-γ and iNOS in infected J774-A1 macrophage cells.

RESULTS

FMN significantly (P < 0.001) decreased the viability and number of promastigotes and amastigotes forms. The 50% inhibitory concentrations value for FMN and glucantime was 9.3 and 14.3 µM for promastigote and amastigote, respectively. We found that the macrophages exposed with FMN especially at concentrations of 1/2 IC₅₀ and IC₅₀ significantly activated the NO release and the mRNA expression levels of IFN-γ, iNOS. The findings of the current research showed the favorable antileishmanial effects formononetin, a natural isoflavone, against various stages of L. tropica through inhibition of infectivity rate of macrophage cells and triggering the NO production and cellular immunity. However, supplementary works are essential to evaluate the ability and safety of FMN in animal model before use in the clinical phase.

Antileishmanial, cellular mechanisms, and cytotoxic effects of green synthesized zinc nanoparticles alone and in combined with glucantime against Leishmania major infection

BACKGROUND

We decided to investigate the antileishmanial, cellular mechanisms, and cytotoxic effects of green synthesized Zinc nanoparticles (ZnNPs) alone and combined with glucantime against Leishmania major infection.

METHODS

The effect of green synthesized ZnNP on L. major amastigote was studied through macrophage cells. The mRNA expression level of iNOS and IFN-γ followed by the exposure of J774-A1 macrophage cells to ZnNPs was assessed by Real-time PCR. The Caspase-3-like activity of promastigotes exposed to ZnNPs was studied. Effects of ZnNPs alone and combined with glucantime (MA) were studied on cutaneous leishmaniasis in BALB/c mice.

RESULTS

ZnNPs displayed the spherical shape with sizes ranging from 30 to 80 nm. The obtained IC₅₀ values for ZnNPs, MA, and ZnNPs + MA were 43.2, 26.3, and 12.6 µg/mL, respectively; indicating the synergistic effects of ZnNPs in combination with MA. CL lesions had completely improved in the mice received with ZnNPs in combination with MA. The mRNA expression level of iNOS, TNF-α, and IFN-γ was dose-dependently (p < 0.01) upregulated; whereas it was downregulated in IL-10. ZnNPs markedly stimulated the caspase-3 activation with no significant toxicity on normal cells.

CONCLUSION

Based on these in vitro and in vivo results, green synthesized ZnNPs, mainly along with MA, showed that has the potential to be introduced as a new drug for CL therapy. Triggering of NO production, and inhibition of infectivity rate are revealed as mechanisms of action ZnNPs on L. major. But, supplementary investigations are necessary to clear the efficacy and safety of these agents.

Synthesis and in vitro antileishmanial activity of alkylene-linked nitrofurantoin-triazole hybrids

Leishmaniasis is a vector-borne parasitic disease that mostly affects populations in tropical and sub-tropical countries. There is currently no protective anti-leishmanial vaccine and only a paucity of clinical drugs is available to treat this disease albeit their toxicity. Leishmaniasis is curable but its eradication and elimination have been hampered by the emergence of multidrug resistant strains of the causative pathogens. This heightens the necessity for new and effective antileishmanial drugs. In search for such agents, nitrofurantoin, a clinical antibiotic, was appended to triazole scaffold through alkylene linkers of various length, and the resulting hybrids were evaluated for in vitro antileishmanial efficacy against Leishmania (L.) parasite of two strains. The hybrid 13, harboring a n-pentylene linker was uncovered as a leishmanicidal hit with micromolar activity against antimonial-resistant L. donovani, the causative of deadly visceral Leishmaniasis.

Chemical composition, antileishmanial, and cytotoxic effects Ferula macrecolea essential oil against Leishmania tropica

Background

The current study was aimed to evaluate the chemical composition, as well as antileishmanial and cytotoxic effects of the essential oil of Ferula macrecolea and its main compound, terpinolene, against promastigotes and amastigotes of Leishmania tropica.

Methods

The chemical composition of the essential oil was analyzed by a gas chromatograph connected to a mass spectrometer (GC/MS). The MTT (3-(4.5-dimethylthiazol-2-yl) - 2.5-diphenyl tetrazolium bromide) assay was used to study the effects of the essential oil and terpinolene against promastigotes while the macrophage model was used for evaluating the effect of F. macrecolea essential oil against amastigotes of L. tropica as well as assessing cytotoxicity. The Griess reaction assay was employed to study the nitric oxide (NO) produced by treating macrophage cells with the essential oil and terpinolene. Furthermore, the effect of the essential oil and terpinolene on plasma membrane permeability and inhibition of infection in macrophages was evaluated.

Results

The main compounds were terpinolene (77.72%), n-nonanal (4.47%), and linalool (4.35%), respectively. The 50% inhibitory concentrations (IC₅₀) of the essential oil, terpinolene, and glucantime against promastigotes were 27.6, 11.6, and 32.8 μg/mL, respectively; however, their IC₅₀ values against amastigotes were 42.3, 19.6, and 56.9 μg/mL, respectively. The 50% cytotoxic concentrations of the essential oil, terpinolene, and glucantime were 471.3, 207.3, and 1165.3 μg/mL, respectively. The production of NO in macrophage cells after treatment with the essential oil and terpinolene was increased in a dose-dependent manner (p < 0.001). The results revealed that by increasing the concentration of the essential oil and terpinolene, the permeability of the parasites' plasma membrane was significantly changed (p < 0.001). The pre-incubation of Leishmania parasites with F. macrecolea essential oil and terpinolene significantly declined the rate of cell infection by 74.8% and 79.4%, respectively (p < 0.001).

Conclusion

The results of the present study indicated that F. macrecolea essential oil, especially its main compound, i.e., terpinolene, has a potent antiparasitic effect on the promastigote and amastigote stages of L. tropica. Considering the advantages of medicinal plant products over their chemical counterparts, it is suggested that in the continuation of this study, the effect of F. macrecolea essential oil, especially terpinolene, on laboratory animals, and in case of high efficiency, in humans be evaluated.

A recombinant Leishmania amastigote-specific protein, rLiHyG, with adjuvants, protects against infection with Leishmania infantum

Vaccination against visceral leishmaniasis (VL) should be considered as a control measure to protect against disease, and amastigote-specific proteins could help to develop such vaccines, since this parasite form is in contact with the host immune system during the active disease. In this study, a Leishmania amastigote-specific protein, LiHyG, was evaluated as recombinant protein (rLiHyG) as vaccine candidate against Leishmania infantum infection in BALB/c mice. The protein was associated with saponin (rLiHyG/Sap) or Poloxamer 407-based polymeric micelles (rLiHyG/Mic) as adjuvants, and animals receiving saline, saponin or micelle as controls. Immunological and parasitological analyses were performed before (n = 8 per group; as primary endpoint) and after (n = 8 per group; as secondary endpoint) infection. Results showed that, in both endpoints, rLiHyG/Sap and rLiHyG/Mic induced higher levels of IFN-γ, IL-12 and GM-CSF in spleen cell cultures from vaccinated animals, besides elevated presence of IgG2a isotype antibodies. Decreased hepatotoxicity and 'positive lymphoproliferative response were also found after challenge. Such findings reflected in significantly lower levels of parasite load found in their spleens, livers, bone marrows and draining lymph nodes. In conclusion, rLiHyG associated with Th1-type adjuvant could be considered for future studies as vaccine candidate to protect against VL.

Increased Leishmania infantum resistance to miltefosine and amphotericin B after treatment of a dog with miltefosine and allopurinol

Background

Leishmania infantum is the most important etiological agent of visceral leishmaniasis in the Americas and Mediterranean region, and the dog is the main host. Miltefosine was authorized to treat canine leishmaniasis (CanL) in Brazil in 2017, but there is a persistent fear of the emergence of parasites resistant not only to this drug but, through cross-resistance mechanisms, also to meglumine antimoniate and amphotericin B. Additionally, the literature shows that acquisition of resistance is followed by increased parasite fitness, with higher rates of proliferation, infectivity and metacyclogenesis, which are drivers of parasite virulence. In this context, the aim of this study was to analyze the impact of treating a dog with miltefosine and allopurinol on the generation of parasites resistant to miltefosine, amphotericin B and meglumine antimoniate.

Methods

In vitro susceptibility tests were conducted against miltefosine, amphotericin B and meglumine antimoniate with T0 (parasites isolated from a dog before treatment with miltefosine plus allopurinol), T1 (after 1 course of treatment) and T2 (after 2 courses of treatment) isolates. The rates of cell proliferation, infectivity and metacyclogenesis of the isolates were also evaluated.

Results

The results indicate a gradual increase in parasite resistance to miltefosine and amphotericin B with increasing the number of treatment courses. An increasing trend in the metacyclogenesis rate of the parasites was also observed as drug resistance increased.

Conclusion

The data indicates an increased L. infantum resistance to miltefosine and amphotericin B after the treatment of a dog with miltefosine plus allopurinol. Further studies with a larger number of L. infantum strains isolated from dogs with varied immune response profiles and undergoing different treatment regimes, are advocated.

Graphical Abstract

Fe3O4@piroctone olamine magnetic nanoparticles: Synthesize and therapeutic potential in cutaneous leishmaniasis

BACKGROUND

In recent years, magnetic nanoparticles (NMP) as novel materials have been widely used for biomedical, diagnostic and therapeutic purposes like microbial infection therapy. The purpose of this study is to synthesize PO coated iron oxide magnetic nanoparticles (Fe3O4@PO NPs) and their anti-leishmanial effects in vitro and in vivo against cutaneous leishmaniasis.

METHODS

Fe3O4 magnetic nanoparticles were synthesized by the coprecipitation of Fe2 + and Fe3 + ions and used as a nanocarrier for the production of Fe3O4@PO NPs. The in vitro antileishmanial effects of PO-coated Fe3O4 NPs and Fe3O4 NPs (10-200 µg/mL) was determined against the intracellular amastigotes of Leishmania major (MRHO/IR/75/ER) and, then, examined on cutaneous leishmaniasis induced in male BALB/c mice by L. major. The rate of infectivity, production of nitric oxide (NO), and cytotoxic activates of Fe3O4 NPs and Fe3O4@PO NPs on J774-A1 macrophage cells were determined.

RESULTS

The size scattering of the Fe3O4 NPs and Fe3O4@PO NPs were in the range among 1-40 and 5-55 nm, respectively. The obtained IC₅₀ values were 62.3 ± 2.15 μg/mL, 31.3 ± 2.26 μg/mL, and 52.6 ± 2.15 μg/mL for the Fe3O4 NPs and Fe3O4@PO NPs, and MA, respectively. The results revealed that the mean number of parasites and the mean diameter of the lesions was considerably (p < 0.05) decreased in the infected mice treated with Fe3O4 NPs and Fe3O4@PO NPs. The Fe3O4 NPs and Fe3O4@PO NPs significantly (p < 0.05) prompted the production of NO as a dose-dependent manner. The promastigotes pre-incubated in Fe3O4 NPs and Fe3O4@PO NPs at the concentration of 5 µg/mL had the ability to infect only 41.7% and 28.3% of the macrophages cells. The selectivity index of greater than 10 for Fe3O4 NPs and Fe3O4@PO NPs showed its safety to the J774-A1 macrophage cells and specificity to the parasite.

CONCLUSION

The results of this survey indicated the high potency of Fe3O4@PO NPs to inhibit the growth of amastigote forms of L. major as well as recovery and improvement CL induced by L. major in BALB/c mice without significant cytotoxicity. The results also indicated that, although the possible anti-leishmanial mechanisms of Fe3O4@PO NPs have not been clearly understood, however, the triggering of NO may be considered as one of the possible anti-leishmanial mechanisms of these nanoparticles. However, additional studies, in particular in clinical contexts, are mandatory.

New diarylsulfonamide inhibitors of Leishmania infantum amastigotes

New drugs against visceral leishmaniasis with mechanisms of action differing from existing treatments and with adequate cost, stability, and properties are urgently needed. No antitubulin drug is currently in the clinic against Leishmania infantum, the causative agent of visceral leishmaniasis in the Mediterranean area. We have designed and synthesized a focused library of 350 compounds against the Leishmania tubulin based on the structure-activity relationship (SAR) and sequence differences between host and parasite. The compounds synthesized are accessible, stable, and appropriately soluble in water. We assayed the library against Leishmania promastigotes, axenic, and intracellular amastigotes and found 0, 8, and 16 active compounds, respectively, with a high success rate against intracellular amastigotes of over 10%, not including the cytotoxic compounds. Five compounds have a similar or better potency than the clinically used miltefosine. 14 compounds showed a host-dependent mechanism of action that might be advantageous as it may render them less susceptible to the development of drug resistance. The active compounds cluster in five chemical classes that provide structure-activity relationships for further hit improvement and facilitate series development. Molecular docking is consistent with the proposed mechanism of action, supported by the observed structure-activity relationships, and suggests a potential extension to other Leishmania species due to sequence similarities. A new family of diarylsulfonamides designed against the parasite tubulins is active against Leishmania infantum and represents a new class of potential drugs with favorable cost, stability, and aqueous solubility for the treatment of visceral leishmaniasis (VL). These results could be extended to other clinically relevant species of Leishmania spp.

In Vitro Antileishmanial Effects of Saffron Compounds, Crocin and Stigmasterol, on Iranian Strain of Leishmania major (MHOM/IR/75/ER)

Background:

Due to numerous side effects of common drugs in treatment of leishmaniasis, new therapeutic approaches focus on herbal compounds. Therefore, we aimed to determine the effect of crocin and stigmasterol on in-vitro growth of promastigotes and amastigotes of Leishmania major in the Department of Parasitology, Pasteur Institute, Tehran, Iran in 2018.

Methods:

The effect of different concentrations of crocin and stigmasterol were evaluated by determining their in-vitro inhibitory effects on promastigotes and amastigotes of the L. major using MTT assay.

Results:

The fatality rate was 65.27% and 71.96% for crocin and stigmasterol respectively at 24 h post-culture in concentration of 50 μg/mL. The mean inhibitory effect of crocin and stigmasterol on L major amastigotes after 72 h were 52.22% and 38.96%.

Conclusion:

The crocin and stigmasterol had efficient adverse effects on promastigote and amastigotes of L. major, hence, further studies on the anti-leishmanial effects of these herbal compounds in human and animal models are recommended.

Design, synthesis, and evaluation of substrate - analogue inhibitors of Trypanosoma cruzi ribose 5-phosphate isomerase type B

Ribose 5-phosphate isomerase type B (RPI-B) is a key enzyme of the pentose phosphate pathway that catalyzes the isomerization of ribose 5-phosphate (R5P) and ribulose 5-phosphate (Ru5P). Trypanosoma cruzi RPI-B (TcRPI-B) appears to be a suitable drug-target mainly due to: (i) its essentiality (as previously shown in other trypanosomatids), (ii) it does not present a homologue in mammalian genomes sequenced thus far, and (iii) it participates in the production of NADPH and nucleotide/nucleic acid synthesis that are critical for parasite cell survival. In this survey, we report on the competitive inhibition of TcRPI-B by a substrate - analogue inhibitor, Compound B (K_i = 5.5 ± 0.1 μM), by the Dixon method. This compound has an iodoacetamide moiety that is susceptible to nucleophilic attack, particularly by the cysteine thiol group. Compound B was conceived to specifically target Cys-69, an important active site residue. By incubating TcRPI-B with Compound B, a trypsin digestion LC-MS/MS analysis revealed the identification of Compound B covalently bound to Cys-69. This inhibitor also exhibited notable in vitro trypanocidal activity against T. cruzi infective life-stages co-cultured in NIH-3T3 murine host cells (IC₅₀ = 17.40 ± 1.055 μM). The study of Compound B served as a proof-of-concept so that next generation inhibitors can potentially be developed with a focus on using a prodrug group in replacement of the iodoacetamide moiety, thus representing an attractive starting point for the future treatment of Chagas' disease.

In Vitro Image-Based Assay for Trypanosoma cruzi Intracellular Forms

The advances in development and popularization of automated fluorescence microscopes and pipetting robots allowed scientists to establish high-throughput compound screening using image-based assays for Trypanosoma cruzi intracellular forms, which are associated to chronic Chagas disease. An intracellular T. cruzi image-based assay is a valuable tool to early stage drug discovery for Chagas disease, because it allows scientists to assess a compound's efficacy and safety in the same experiment. During the last 10 years, several improvements have been incorporated into intracellular T. cruzi assay protocols to make them more predictable in what happens with parasites within an infected organism. In the present chapter, a protocol will be presented for an intracellular T. cruzi assay, but at a low-throughput scale, more compatible with facilities in many academic laboratories.

Genome-Wide Proteomics and Phosphoproteomics Analysis of Leishmania spp. During Differentiation

Determining variations in protein abundance and/or posttranslational modification as a function of time or upon induction by a signal in a particular cell type is central to quantitative proteomics. Isobaric labeling methodologies now allow for parallel quantification of proteins at various conditions concurrently or multiplexing in relatively quantitative proteomics workflows. Hence, mapping the protein expression profiles of various developmental stages of Leishmania parasites is possible with high-resolution mass spectrometry. To analyze global changes in protein expression and cellular signaling pathways during Leishmania differentiation and development is possible with a quantitative proteomics approach. The tandem mass tags (TMT) approach provides a chemical labeling method based on the principle of amine reactive tags; the maximum number of conditions that can be multiplexed is 10-plex. We describe herein a detailed method for sample preparation, TMT-labeling, mass spectrometry and data analysis of different developmental stages of Leishmania donovani parasites. This quantitative proteomic approach is useful to study dynamic changes in protein expression levels during L. donovani differentiation, and also allows in-depth analysis of signaling pathways via phosphoproteomics.

In Vitro Growth Inhibition Assays of Leishmania spp

In vitro growth (inhibition) assays have a dual application, either supporting the discovery of novel drugs or as a monitoring tool of drug resistance in patient isolates. From an experimental design point of view, both are quite different with regard to the infecting Leishmania species and strain, the wide variety of permissive host cells (primary cells versus cell lines), drug exposure times, detection methods and endpoint criteria. Recognizing the need for enhanced assay standardization to decrease interlaboratory variation and improve proper interpretation of results, a detailed description is given of the basic fundamental procedures and requirements for routine in vitro growth of Leishmania spp. with specific focus on the intracellular amastigote susceptibility assay. Although the described experimental procedures focus on visceral Leishmania species, the same assay principles may apply for the cutaneous species as well.

Study of the in vitro and in vivo antileishmanial activities of nimodipine in susceptible BALB/c mice

BACKGROUND & OBJECTIVES

Pentavalent antimonials are the standard treatment for cutaneous leishmaniasis (CL), however, treatment failures are frequent. Nimodipine, a calcium channel blocker is known to show promising antiprotozoal effects. Here, we investigated the antileishmanial effect of Nimodipine in both in vitro and in vivo BALB/c mice model of CL. We also compared the in vivo effect with amphotericin B and meglumine antimoniate in the experimental CL mice model.

METHODS

Colorimetric alamar blue assay and J774 A.1 mouse macrophage cells were used to determine the effect of nimodipine on promastigotes and amastigotes viability, respectively. Then, the in vivo activity of nimodipine was compared to that of conventional therapies in both the early and established courses of Leishmania major infection in susceptible non-healing BALB/c mice.

RESULTS

Nimodipine was highly active against promastigotes and amastigotes of L. major with IC₅₀ values of 49.40 and 15.03 μM, respectively. In the early model, the combination therapy with meglumine antimoniate and nimodipine showed no parasites in the spleen or footpad of animals. The footpad thickness was significantly lower in mice treated with either nimodipine (1 mg/kg or 2.5 mg/kg) or amphotericin B compared to the control group in the established lesions model. However, no complete remission was observed in the footpad lesion of any of the treatment groups (nimodipine, amphotericin B, meglumine antimoniate, and combination therapy).

INTERPRETATION & CONCLUSION

The effect of nimodipine was comparable to that of amphotericin B and meglumine antimoniate in early and established CL lesion models. Since nimodipine is more cost-effective than conventional therapies, our results merit further investigation in other animal models and voluntary human subjects.

Methods for the Investigation of Trypanosoma cruzi Amastigote Proliferation in Mammalian Host Cells

In its mammalian host, the kinetoplastid protozoan parasite, Trypanosoma cruzi, is obliged to establish intracellular residence in order to replicate. This parasite can infect and replicate within a diverse array of cell and tissue types across many mammalian host species. The establishment of quantitative assays to assess the replicative capacity of intracellular T. cruzi amastigotes under different conditions is a critical facet to understanding this host-pathogen interaction. Several complementary methods are outlined here. Their strengths and deficiencies in quantifying intracellular amastigote growth and death are discussed. We describe three assays to assess growth/replication. (1) A high throughput multiplexed plate-based assay that quantifies both host cell and parasite abundance. This method allows for the rapid and simultaneous screening of many conditions (e.g., small molecule inhibitors, the impact of host gene knockdown or of altered environmental parameters). (2) Simple fluorescence microscopy-based enumeration of amastigotes within host cells and (3) flow cytometry-based quantification of amastigote proliferation following isolation from host cells. Each approach has advantages but none of these can assess lethal outcomes in a quantitative manner. For this, we describe a clonal outgrowth assay that identifies the proportion of parasites that succumb to a defined exposure. Even using these assays, it can be challenging to differentiate between direct (targeting the parasite) and/or indirect (targeting the host) effects of a given treatment on amastigote growth. Therefore, we also outline a method of purification of intracellular amastigotes that allows for downstream biochemical and metabolic investigations specifically on the isolated amastigote.

In Vitro Culture for Differentiation Simulation of Leishmania spp

In the 1990s my laboratory discovered that Leishmania promastigotes can combine two environmental cues, typical to lysosomes, acidic pH (~5.5) and body temperature (37 °C) into a single signal that induced differentiation. Based on this concept, we modified EARLS-based medium 199 to become an amastigote-specific medium. Shifting promastigotes to this medium followed by incubation in a CO₂ incubator induced differentiation. Axenic amastigotes reach maturation within 5 days, resembling the time it takes in vivo. This chapter provides a complete protocol we developed for L. donovani promastigote-to-amastigote differentiation. This protocol should be useful for both old-world and new-world species of Leishmania.

Farnesyl pyrophosphate synthase is essential for the promastigote and amastigote stages in Leishmania major

Isoprenoid synthesis provides a diverse class of biomolecules including sterols, dolichols, ubiquinones and prenyl groups. The enzyme farnesyl pyrophosphate synthase (FPPS) catalyzes the formation of farnesyl pyrophosphate, a key intermediate for the biosynthesis of all isoprenoids. In Leishmania, FPPS is considered the main target of nitrogen containing bisphosphonates, yet the essentiality of this enzyme remains untested. Using a facilitated knockout approach, we carried out the genetic analysis of FPPS in Leishmania major. Our data indicated that chromosomal null mutants for FPPS could only be generated in presence of an episomally expressed FPPS. Long-term retention of the episome by the chromosomal FPPS-null mutants in culture and in infected BALB/c mice suggests that FPPS is indispensable. In addition, applying negative selection pressure failed to induce the loss of ectopic FPPS in the chromosomal FPPS-null mutants, although it led to significant growth delay in culture and in mice. Together, our findings have confirmed the essentiality of FPPS in both promastigotes and amastigotes in L. major and thus validate its potential as a drug target for the treatment of cutaneous leishmaniasis.

Host-Free Systems for Differentiation of Axenic Leishmania

This chapter describes, in detail, the method our laboratory developed to differentiate L. donovani promastigotes into amastigotes in a host-free culture. This method is based on previous observations that Leishmania promastigotes can combine two environmental signals, typical to lysosomes, acidic pH (~5.5) and body temperature (37 °C), into a signal that induces differentiation. Based on this concept, we have modified medium 199 to make it into an amastigote-specific medium. Shifting promastigotes to this medium, followed by incubation in a CO₂ incubator, induced differentiation. Axenic amastigotes reach maturation within 5 days, resembling the time it takes in vivo. This chapter provides a complete protocol that should be useful for both Old and New World species of Leishmania.

The therapeutic effect of ozonated olive oil plus glucantime on human cutaneous leishmaniasis

OBJECTIVES

Leishmaniasis is one of the main health problems in developing countries, caused by intracellular protozoan parasites of the Leishmania genus. Although research has been successful in discovering vaccines and anti-parasitic drugs like antimony compounds, their side effects like high toxicity, prolonged regeneration, etc., have raised the replacement importance of natural products with antioxidant and antibacterial properties. It can be said that an appropriate alternative to this is the ozonated olive oil. Ozone by introducing O2 in involved tissues and bloodstream could degrade parasite amastigotes and lead to cleared leishmaniasis infections. So, the present study aimed to evaluate the effect of ozonated olive oil in Iranian leishmaniasis patients compared to glucantime, a choice drug for the treatment of Leishmaniasis.

MATERIALS AND METHODS

Thirty patients with confirmed leishmaniasis lesions were included and divided into two groups, 15 cases as control and 15 cases as test with lesions of 30-50 mm2 in diameter. The control group received glucantime intralesionally and the test group ozonated olive oil plus glucantime, 2 times daily.

RESULTS

The mean of lesion size was (50.94±33.20) before and (15±14.34) after treatment in control (P<0.00) and (50.88±31.74) before and (9.93±14.18) after treatment in the test group (P<0.00). Moreover, the mean course of therapy was 10.4(±1.84) weeks and 8.93(±2.15) weeks in control and test groups, respectively (P=0.636). Significant differences were reported in lesion size after treatment between the two groups (P<0.00).

CONCLUSION

Data suggested ozonated olive oil can have synergistic effects with glucantime in the treatment of cutaneous leishmaniasis.

Antimicrobial activity of an antimicrobial peptide against amastigote forms of Leishmania major

Zoonotic cutaneous leishmaniasis caused by Leishmania major is a most common type of vector-borne disease in Iran. The pentavalent antimonial drugs have been used in the treatment of cutaneous leishmaniasis for a long time, but drug resistance and some of serious side effects have been reported. Thus, discovery and development of new therapeutic candidates are needed. The CM11 peptide is one of these peptides that its anti-bacterial activity has been proven. This peptide is a short cecropin–melittin hybrid peptide obtained through a sequence combination approach. The aim of this study was to evaluate in vitro anti-leishmanial activity of CM11 peptide against amastigote forms of Leishmania major. In this study, amastigote forms of Iranian strain of L. major (MRHO/IR/75/ER) were cultured in the presence of different concentrations of meglumine antimoniate (Glucantime^®) to find the most appropriate in vitro concentration of Glucantime^® against L. major amastigotes. Then, the anti-leishmanial activities of various concentrations of CM11 peptide (8, 16, 32 and 64 µM) were evaluated for 24, 48 and 72 hr by DAPI staining. In addition, MTT assay was used to determine the cytotoxic effects of CM11 peptide on murine fibroblast cell line. The results showed that CM11 peptide has antimicrobial activity against Iranian isolate of L. major in the laboratory conditions. It seems that the CM11 peptide has significant potential to be used as a new anti-leishmanial agent.

Promastigote parasites cultured from the lesions of patients with mucosal leishmaniasis are more resistant to oxidative stress than promastigotes from a cutaneous lesion

Human leishmaniasis caused by Leishmania (Viannia) braziliensis can be presented as localized cutaneous leishmaniasis (LCL) or mucosal leishmaniasis (ML). Macrophages kill parasites using nitric oxide (NO) and reactive oxygen species (ROS). The aim of this study was to evaluate the ability of parasites obtained from patients with LCL or ML to produce and resist NO or ROS. Promastigotes and amastigotes from LCL or ML isolates produced similar amounts of NO in culture. Promastigotes from ML isolates were more resistant to NO and H₂O₂ than LCL parasites in a stationary phase, whereas amastigotes from LCL isolates were more resistant to NO. In addition, in the stationary phase, promastigote isolates from patients with ML expressed more thiol-specific antioxidant protein (TSA) than LCL isolates. Therefore it is suggested that infective promastigotes from ML isolates are more resistant to microbicidal mechanisms in the initial phase of infection. Subsequently, amastigotes lose this resistance. This behavior of ML parasites can decrease the number of parasites capable of stimulating the host immune response shortly after the infection establishment.

Investigation of the antimicrobial activity of a short cationic peptide against promastigote and amastigote forms of Leishmania major (MHRO/IR/75/ER): An in vitro study

Cutaneous leishmaniasis is one of the most endemic global health problems in many countries all around the world. Pentavalent antimonial drugs constitute the first line of leishmaniasis treatment; however, resistance to these drugs is a serious problem. Therefore, new therapies with new modes of action are urgently needed. In the current study, we examined antimicrobial activity of CM11 hybrid peptide (WKLFKKILKVL-NH2) against promastigote and amastigote forms of L. major (MHRO/IR/75/ER). In vitro anti-leishmanial activity was identified against L. major by parasite viability and metabolic activity after exposure to different peptide concentration. In the presentt study, we demostrated that different concentrations of CM11 result in dose dependent growth inhibition of Leishmania promastigotes. Furthermore, we demostrated that CM11 peptide has significant anti-leishmanial activities on amastigotes. Our results demonstrated that CM11 antimicrobial peptide may provide an alternative therapeutic approach for L. major treatment.

Polyurethane sheet impregnated with Arabinogalactan can lead to increase of attachment of promastigotes and Amastigote of Leishmania major (MRHO/IR/75/ER) by GP63 and HSP70 genes

The aim of this study was to investigate the effect of polyurethane sheet (PUS) and polyurethane sheet impregnated with Arabinogalactan (PUSIAG) on the cell attachment and viability of Promastigotes and Amastigotes of Leishmania major (MRHO/IR/75/ER), and mouse macrophages, and its whole skin cells (WSCs). In a sterile condition, 10 mL of Arabinogalactan 5% w/v was poured into a falcon. Then, a piece of PUS was placed inside it, and incubated at 37 °C for 24 h. Next, it was washed, and cut. Then, one piece of PUS and PUSIAG was separately added to 1 mL of cell suspension (Promastigotes, Amastigote, and WSCs), and then incubated for 1, 2, 3, and 4 days at 37 °C. After incubation times, the quantity of adhered cells was counted, and cell viability was measured by MTT assay. Also, for WSCs and macrophages, the expression of integrin, fibronectin and GAPDH was investigated, and for Promastigotes and Amastigotes, the expression of GP63, Cpb, and 18s rRNA was measured. This study showed that with increase of exposure time, the percentage of attached cells was increased. There was a significant difference between attached cells to PUSIAG and PUS in case of Promastigotes and Amastigotes. It seems that Promastigotes and Amastigotes have higher interest to PUSIAG than WSCs and Macrophages. Also, this study showed with increase of exposure time, the percentage of viable cells was decreased. There were significant differences between cell viability of Promastigotes and Amastigotes when exposed to PUSIAG and PUS, especially in long time incubation. Also, when incubation time was increased the relative expression of integrin and fibronectin in WSCs and macrophages, and GP63 and HSP70 in Promastigotes and Amastigotes were increased.

Achievement amastigotes of Leishmania infantum and investigation of pathological changes in the tissues of infected golden hamsters

Leishmania infantum is an agent of visceral leishmaniasis (VL). Amastigote form is a more appropriate target for investigations on vaccines, treatment, and diagnosis. This study aimed to achieve the amastigotes of L. infantum in the golden hamster and J774 macrophages and report the pathological changes that occur in the liver and spleen of the hamsters with VL. 4 male golden hamsters were infected with L. infantum promastigotes. After 5 months, the hamsters were euthanized and touch and pathology smears were prepared from the livers and spleens. Then, these tissues were homogenized and centrifuged at 100×g. Supernatants were collected and centrifuged at 2000×g and the pellets were collected. In the next part of our study, J774 macrophages were infected with L. infantum promastigotes. Then, the infected macrophages were ruptured. Centrifuge stages were done same the previous part. The amastigotes were observed in touch and pathology smears. A load of amastigotes in the livers was more than the spleens in both types of smears. Although the livers' structure had undergone pathological changes, the spleens were unchanged. Also, the macrophage infectivity ratio was up to 95%. Our results present a simple and accessible way of achieving a lot of pure and real amastigotes for different fields in Leishmania. Also, it seems that the pathological changes occurring in the spleen and the liver of animals with VL are different and probably can be attributed to the genetic and immune process of the infected animals.

Comparison of p27 Gene Expression of Promastigote and Amastigote Forms of Leishmania major (MRHO/IR/75/ER) by Real-time RT-PCR

BACKGROUND

Cutaneous leishmaniasis (CL) is one of the world health problems. Leishmania major is the etiological agent of zoonotic cutaneous leishmaniasis (ZCL). Promastigote and amastigote are two morphological forms of Leishmania parasites that express different proteins and p27 is an important gene encoding cytochrome c oxidase (COX) component. P27 gene expresses a 27 kDa protein that essential in ATP synthesis. This study aimed to compare p27 gene expression in promastigote and amastigote forms in Iranian strain of L. major (MRHO/IR/75/ER).

METHODS

This study was conducted in 2015. Clinical isolates of CL patients from north, center, west and south parts of Iran were collected and identified by PCRRFLP. After RNA extraction of promastigotes and amastigotes and cDNA synthesis, the expression level of p27 gene was compared by real-time RT-PCR.

RESULTS

By comparison of expression level between amastigote and promastigote forms of Iranian strain of L. major, up-regulation of p27 gene (2.73 fold) was observed in amastigotes. Moreover, there was no significant difference in p27 gene expression between L. major isolates.

CONCLUSION

p27 gene and protein can be considered as a target in recombinant vaccine production and treatment process.

Drosophila Model of Leishmania amazonensis Infection

This protocol describes how to generate and harvest antibody-free L. amazonensis amastigotes, and how to infect adult Drosophila melanogaster with these parasites. This model recapitulates key aspects of the interactions between Leishmania amastigotes and animal phagocytes.

In vitro antileishmanial activity of novel azoles (3-imidazolylflavanones) against promastigote and amastigote stages of Leishmania major

Leishmaniasis is a protozoan infectious disease widely distributed all around the world. First line drugs including antimoniales are insufficient due to resistance in endemic areas and high toxicity. Azole antifungals like ketoconazole (KCZ) are also used as antileishmanial agents for several decades. In the present study, we evaluated in vitro antileishmanial effects of new azole antifungals namely 3-imidazolylflavanones (IFs) and their oximes (IFOs) against Leishmania major (L. major) parasites. The obtained results showed remarkable effect of our compounds on promastigote and amastigote stages of L. major. In particular, the 4-chloro analog of flavanone (IF-2) and 3-chloro substituted flavanone oxime (IFO-3) with IC₅₀ values ≤8.9μg/mL were 8-fold more potent than KCZ (IC₅₀=72μg/mL) against promastigote form of L. major. In amastigote stage, the compounds IF-2 and IFO-2 decreased the mean number of infected macrophages (MIR) more than KCZ (p<0.005). In addition, compounds IF-1, IF-2, IF-4, IFO-2, IFO-3 and IFO-5 decreased the mean number of amastigotes per macrophages (MNAPM) significantly more than KCZ (p<0.005). All compounds decreased both MIR and MNAPM significantly more than control (p<0.001). Compounds IF-2 and IFO-2 with parasite survival of 7.70% and 20% had the highest inhibition on intracellular amastigotes. Although most of compounds displayed acceptable selectivity index, compound IF-2 had the highest CC₅₀ value (115.4μg/mL) and SI (383.3). We concluded that our new synthetic azoles displaying potent activity against L. major could be considered as new hits for drug development in the field of antileishmanial therapy.

Synthesis and in-vitro anti-leishmanial activity of (4-arylpiperazin-1-yl)(1-(thiophen-2-yl)-9H-pyrido[3,4-b]indol-3-yl)methanone derivatives

In the present study, we have reported synthesis and biological evaluation of a series of fifteen 1-(thiophen-2-yl)-9H-pyrido[3,4-b]indole derivatives against both promastigotes and amastigotes of Leishmania parasites responsible for visceral (L. donovani) and cutaneous (L. amazonensis) leishmaniasis. Among these reported analogues, compounds 7b, 7c, 7f, 7g, 7i, 7j, 7m, 7o displayed potent activity (15.55, 7.70, 7.00, 3.80, 14.10, 9.25, 3.10, 4.85μM, respectively) against L. donovani promastigotes than standard drugs miltefosine (15.70μM) and pentamidine (32.70μM) with good selectivity index. In further, in-vitro evaluation against amastigote forms, two compounds 7g (8.80μM) and 7i (7.50μM) showed significant inhibition of L. donovani amastigotes. Standard drug amphotericin B is also used as control to compare inhibition potency of compounds against both promastigote (0.24μM) and amastigote (0.05μM) forms.

Visual assessment of parasitic burden in infected macrophage by plasmonic detection of leishmania specific marker RNA

Visceral leishmaniasis is a neglected tropical disease and may prove fatal if not diagnosed and treated early. The amastigotes of Leishmania donovani nest in the macrophage of human host and thus, determination of parasitic burden in the infected macrophages has been the most crucial step in diagnosis, dose determination and medical management of relapse cases of this fatal disease. Microscopic count following Giemsa staining and other morphological analysis are the classical ways vastly used in the resource stringent endemic areas. The current method introduced a high throughput, rapid, cheap, non-gel, non-PCR and nonculture based visual detection platform employing salt triggered aggregation of gold nanoparticle in presence of extracted total RNA from infected macrophages and leishmania specific oligo-nucleotide probe to determine the parasite burden in macrophages. Amastigote's small subunit ribosomal RNA (SSU rRNA, PMID 1565128) was used as the leishmania specific marker and its abundance in the total RNA extracts of infected macrophages were determined by this visual colorimetric assay.

Flagellar pocket restructuring through the Leishmania life cycle involves a discrete flagellum attachment zone

Leishmania promastigote parasites have a flagellum, which protrudes from the flagellar pocket at the cell anterior, yet, surprisingly, have homologs of many flagellum attachment zone (FAZ) proteins – proteins used in the related Trypanosoma species to laterally attach the flagellum to the cell body from the flagellar pocket to the cell posterior. Here, we use seven Leishmania mexicana cell lines that expressed eYFP fusions of FAZ protein homologs to show that the Leishmania flagellar pocket includes a FAZ structure. Electron tomography revealed a precisely defined 3D organisation for both the flagellar pocket and FAZ, with striking similarities to those of Trypanosoma brucei. Expression of two T. brucei FAZ proteins in L. mexicana showed that T. brucei FAZ proteins can assemble into the Leishmania FAZ structure. Leishmania therefore have a previously unrecognised FAZ structure, which we show undergoes major structural reorganisation in the transition from the promastigote (sandfly vector) to amastigote (in mammalian macrophages). Morphogenesis of the Leishmania flagellar pocket, a structure important for pathogenicity, is therefore intimately associated with a FAZ; a finding with implications for understanding shape changes involving component modules during evolution.

Summary:Leishmania parasites have a highly structured flagellar pocket, including a structure homologous to the Trypanosoma brucei flagellum attachment zone, which undergoes structural adaptations in different life cycle stages.

In vitro anti-leishmanial activity of methanolic extracts of Calendula officinalis flowers, Datura stramonium seeds, and Salvia officinalis leaves

AIM

The anti-leishmanial activity of methanolic extracts of Calendula officinalis flowers, Datura stramonium seeds, and Salvia officinalis leaves against extracellular (promastigote) and intracellular (amastigote) forms of Leishmania major were evaluated in this study.

METHOD

In the first stage, promastigote forms of L. major, were treated with different doses of the plant extracts in a 96-well tissue-culture microplate and IC50 values for each extract were measured with colorimetric MTT assay. In the second stage, macrophage cells were infected with L. major promastigotes. Infected macrophages were treated with plant extracts. Then the macrophages were stained with Gimsa and the number of infected macrophages and amastigotes were counted with a light microscope.

RESULTS

The results indicated that the plant extracts inhibited the growth of promastigotes and amastigotes of L. major. Inhibitory concentrations (IC50) for promastigote assay were 108.19, 155.15, and 184.32 μgmL(-1) for C. officinalis flowers, D. stramonium seeds and S. officinalis, respectively. The extracts also reduced the number of amastigotes in macrophage cells from 264 for control group to 88, 97, and 102 for test groups. Although the anti-leishmanial activity of the extracts were not comparable with the standard drug, miltefosine; but they showed significant efficiency in reducing the number of amastigotes in macrophages, in comparison with the control group (P < 0.001). These plant extracts had lower toxicity compared with miltefosine.

CONCLUSION

This study demonstrates the potential efficacy of the methanolic extracts of C. officinalis flowers, D. stramonium seeds, and S. officinalis leaves to control of cutaneous leishmaniasis.

Selective elimination of Leptomonas from the in vitro co-culture with Leishmania

Leishmania and Leptomonas are protozoan parasites of the family Trypanosomatidae. Leishmania donovani causes the fatal visceral leishmaniasis (VL; kala-azar) in mammals and is transmitted by sand fly vector. Certain VL-cured human populations in India and Sudan develop post kala-azar dermal leishmaniasis (PKDL) due to the same parasite. Although Leptomonas is parasitic mainly in insects, several recent reports on the clinical isolates of L. donovani from VL and PKDL patients in India confirm co-infection of Leptomonas seymouri, probably due to immune suppression in those individuals. Detection of L. seymouri in the in vitro cultures of L. donovani from clinical origin is difficult due to many similarities between L. seymouri and L. donovani. We describe here ways to detect L. seymouri and L. donovani in co-culture. In addition, based on our observation regarding the growth of L. seymouri in different culture conditions, we report here a novel procedure, which can selectively eliminate L. seymouri from the in vitro co-culture with L. donovani. This would be beneficial to researchers who prefer to deal with pure populations of Leishmania parasites for various downstream immunological and genetic studies.

In Vitro Study of Leishmanicidal Activity of Biogenic Selenium Nanoparticles against Iranian Isolate of Sensitive and Glucantime-Resistant Leishmania tropica

BACKGROUND

Sensitive and glucantime (MA) resistance Leishmania tropica are referred to those isolates, which are responsive, or non-responsive to one or two full courses of treatment by MA systematically and/or intra-lesionally, respectively. In this study, we evaluated the antileishmanial activity of biogenic selenium nanoparticles (Se NPs) alone and in combination with MA against sensitive and glucantime-resistant L. tropica on in vitro model.

METHODS

The Se NPs were synthesized by employing the Bacillus sp. MSh-1. The antileishmanial effects of Se NPs alone and in combination with MA on promastigote and amastigote stages of sensitive and glucantime-resistant L. tropica strains have been investigated using a colorimetric MTT assay and in a macrophage model. In addition hemolytic activity in type O+ human red blood cells and infectivity rate of the promastigotes before and after treatment with the Se NPs was evaluated.

RESULTS

In the promastigote stage, various concentrations of Se NPs significantly inhibited (P<0.05) the growth of promastigotes of both strains in a dose-dependent manner. Similarly, Se NPs especially in combination with MA significantly reduced the mean number of amastigotes of both strains in each macrophage. Se NPs showed no hemolytic effect on human RBCs at low concentrations. Moreover, infection rate of macrophages by promastigotes significantly (P<0.05) was reduced when promastigotes pre-treated with Se NPs.

CONCLUSION

The findings of this study suggest a first step in the search of Se NPs as a new antileishmanial agent. Further experiments are needed to investigate antileishmanial effects of biogenic Se NPs on L. tropica using a clinical setting.

Assessment of the infectivity potential of Leishmania infantum, using flow cytometry

The protozoan parasite Leishmania infantum causes leishmaniases, a sandfly-borne disease of humans and dogs, in all countries of the Mediterranean basin. The promastigote, infective stage of the parasite, once inoculated to the mammalian host by the vector, is ingested by macrophages. Leishmania lives within the lysosome of the phagocytic immune cells inactivating the enzymes contained. The ability of an isolate to survive within the macrophage and its rate of multiplication in this environment is an important factor determining the infectivity potential of the isolate and the manifestation of the disease. This capacity of the parasite is measured as the percentage of infected cells and the mean value of parasites per cell. The infectivity potential, of clinical isolates of L. infantum infecting THP-1 cells in vitro, was studied by flow cytometry and light microscopy. The percentages of cells in a sample containing a specific number of parasites, as recorded by light microscopy, were used in flow cytometry to manually gate the mean fluorescence intensity which corresponded to the percentage of cells with that number of parasites. The gating obtained, was then used as a "standard reference curve" to evaluate results by flow cytometry compared to those obtained by light microscopy. The results, of the overall percentage of infected cells and the number of parasites per cell in the culture, matched in the two methods. So, flow cytometry can be used as a rapid, cost effective, easy and reproducible method to study the infectivity potential of isolates, either in biological, epidemiological, or clinical tests, particularly for the assessment of drug efficiency trials.

Generation of growth arrested Leishmania amastigotes: a tool to develop live attenuated vaccine candidates against visceral leishmaniasis

Visceral leishmaniasis (VL) is fatal if not treated and is prevalent widely in the tropical and sub-tropical regions of world. VL is caused by the protozoan parasite Leishmania donovani or Leishmania infantum. Although several second generation vaccines have been licensed to protect dogs against VL, there are no effective vaccines against human VL [1]. Since people cured of leishmaniasis develop lifelong protection, development of live attenuated Leishmania parasites as vaccines, which can have controlled infection, may be a close surrogate to leishmanization. This can be achieved by deletion of genes involved in the regulation of growth and/or virulence of the parasite. Such mutant parasites generally do not revert to virulence in animal models even under conditions of induced immune suppression due to complete deletion of the essential gene(s). In the Leishmania life cycle, the intracellular amastigote form is the virulent form and causes disease in the mammalian hosts. We developed centrin gene deleted L. donovani parasites that displayed attenuated growth only in the amastigote stage and were found safe and efficacious against virulent challenge in the experimental animal models. Thus, targeting genes differentially expressed in the amastigote stage would potentially attenuate only the amastigote stage and hence controlled infectivity may be effective in developing immunity. This review lays out the strategies for attenuation of the growth of the amastigote form of Leishmania for use as live vaccine against leishmaniasis, with a focus on visceral leishmaniasis.

In Vitro Study on Cytotoxic Effects of ZnO Nanoparticles on Promastigote and Amastigote Forms of Leishmania major (MRHO/IR/75/ER)

BACKGROUND

Although pentavalent antimony compounds are used as antileishmanial drugs but they are associated with limitations and several adverse complications. Therefore, always effort to find a new and effective treatment is desired. In this study, the effect of ZnO nanoparticles with mean particle size of 20 nanometers (nm) on Leishmania major promastigotes and amastigotes was evaluated.

METHODS

Viability percentage of promastigotes after adding different concentrations of ZnO nanoparticles (30, 60, 90 and 120 μg/ml) to the parasite culture was evaluated by MTT assay. In the flow cytometry study, Annexin V-FITC Apoptosis detection Kit was used to study the induced apoptosis and necrotic effects.

RESULT

IC50 after 24 hours of incubation was 37.8 μg/ml. ZnO nanoparticles exert cytotoxic effects on promastigotes of L. major through the induction of apoptosis. A concentration of 120 μg/ml of ZnO nanoparticles induced 93.76% apoptosis in L. major after 72 hours.

CONCLUSION

ZnO NPs can induce apoptosis in L. major by dose and time-depended manner in vitro condition.