Treatment of Cutaneous Leishmaniasis and Insights into Species-Specific Responses: A Narrative Review

Multiple mechanisms of action of a triazole-derived salt against Leishmania amazonensis: Apoptosis-like death and autophagy

Current chemotherapy for leishmaniasis faces significant limitations due to high toxicity, prolonged treatment regimens, and increasing parasite resistance, highlighting the urgent need for innovative treatment strategies. This study aimed to evaluate the in vitro activity of 1,2,3-triazole derivatives against promastigotes and amastigotes of Leishmania amazonensis, as well as their cytotoxicity in murine macrophages. Additionally, we investigated the mechanism of parasite death through different biochemical and cellular indicators of cell death parameters. Our results underscored the importance of the salt form, as the neutral form showed no inhibition of parasite growth. In contrast, the triazole-derived salt demonstrated promising selective index (SI = 34.28) and antileishmanial activity (IC50 = 0.13 μM and IC50 = 2.06 μM against promastigote and amastigote forms, respectively), proving more active than miltefosine, the standard drug. Regarding the mode of action of the triazole-derived salt, this compound induced significant mitochondrial alterations in the parasite, characterized by an increase in mitochondrial membrane potential (ΔΨm), elevated levels of total and mitochondrial Reactive Oxygen Species (ROS), and lipid body accumulation in the cytoplasm. Treatment with triazole-derived salt also produced several ultrastructural, biochemical, and cellular changes in the promastigote forms, such as the occurrence of apoptosis-like death, including cell shrinkage and reduction in length, as well as exposure of phosphatidylserine in the outer leaflet of the plasma membrane and marked cell cycle interruption, in addition to DNA fragmentation. Despite MDC positive and the presence of membrane-bound vacuoles resembling autophagosomal structures observed by TEM analysis, autophagy is not a predominant process, with severe mitochondrial damage emerging as the primary event leading to parasite death. These findings demonstrate the promising antileishmanial potential of the triazole-derived salt, with its effect on multiple targets in parasite cells. Moreover, the association of the active compound with miltefosine showed an additive effect in treating L. amazonensis-infected macrophages. Altogether, these results highlight the therapeutic potential of the evaluated salt and support further studies to assess its in vivo efficacy in a murine model of cutaneous leishmaniasis.

Recombinase-based amplification coupled with lateral flow chromatography for the specific and sensitive detection and identification of Leishmania major in cutaneous leishmaniasis patients

Introduction

Cutaneous leishmaniases (CL), a wide range of cutaneous diseases caused by diverse species of Leishmania genus parasites, are among the most neglected infectious diseases. While they are non-fatal, CL are highly morbid with disfiguring lesions, which could be chronic, leaving lifelong unsightly scars; they are combined with psychological distress and social stigma. The efficiency of treatment highly depends on the infecting Leishmania species. Diagnosis is mainly based on microscopic direct examination (DE) of Giemsa-stained smears needing experienced microscopists. It can be laborious and time-consuming when the parasite load is low. DE is poorly sensitive and does not identify Leishmania species. So far, only DNA assays accurately identify the species. Despite their wide use for generic detection, PCR methods also require equipment and additional steps to identify causal Leishmania species. L. major is hyperendemic in many countries in Africa, the Middle East, and Asia, where other species co-occur with different endemicity levels according to the situations. This complicates disease management and treatment, particularly as distribution and epidemiology of leishmaniases remain poorly understood. Here, we aimed for a simple and rapid molecular diagnostic test to detect and identify L. major, a predominant CL causal species, which could be prone to become a control tool at the point of care, in endemic areas, using isothermal recombinase DNA amplification (recombinase polymerase amplification, RPA, or recombinase aided amplification, RAA) coupled to detection by the lateral flow (LF) chromatography on a PCRD cassette.

Methods

To develop an L. major species-specific RPA-LF assay, computational analysis of 70 Leishmania DNA targets, identified through bibliography and database searches, selected five targets. We designed and tested 7 primer pairs/probe sets to specifically amplify L. major DNAs. First, the primers were tested for species specificity and sensitivity using basic RPA chemistry. Then, to develop RPA-coupled LF detection, we shifted to the nfo chemistry.

Results

This way, we retained one set for further investigation, which confirmed it is L. major species-specific. Tested on 86 human cutaneous samples, this selected set was able to detect 100% of L. major infections in confirmed CL patients. We did not observe any cross-reactivity with lesions due to L. infantum or L. tropica.

Molecular Identification and Drug Susceptibility of Leishmania spp. Clinical Isolates Collected from Two Regions of Oaxaca, Mexico

Pentavalent antimonials are the first line for leishmaniasis treatment, although they induce many adverse side effects and treatment failure and parasite resistance have been detected. Cutaneous leishmaniasis is the main clinical manifestation of the disease in Oaxaca State, Mexico; however, its presence is under-registered, and information about the Leishmania species that circulate and cause the disease in the region is limited. In this study, the presence of Leishmania was analyzed in 24 skin smears and 2 biopsies from lesions suspicious for leishmaniasis in inhabitants of the Tehuantepec Isthmus and Papaloapan Basin regions, Oaxaca State. By ITS1-PCR, the species of clinical isolates were identified. Moreover, the susceptibility of clinical isolates to leishmanicidal drugs was assessed. Skin smears were negative for the presence of Leishmania spp.; meanwhile, parasite amastigotes were observed in tissue biopsies; however, by ITS1-PCR, 46% of the samples were determined to be positive for the parasite. Six clinical isolates were identified as L. mexicana and had lower susceptibility to Miltefosine and Amphotericin B than the L. mexicana reference strain. No leishmanicidal activity of Glucantime was detected. Further studies with increased patient sample sizes and genotypic studies will describe in detail parasite susceptibility to reference drugs in the region.

Spatial modelling to identify high-risk zones for the transmission of cutaneous leishmaniasis in hyperendemic urban environments: A case study of Mashhad, Iran

Spatial modelling was employed to identify high-risk zones for the transmission of cutaneous leishmaniasis in hyperendemic urban environments, focusing on Mashhad, Iran. Data analysis from 3033 CL patients (2016-2020) integrated socio-demographic, environmental, and geological factors using negative binomial regression and the technique for order of preference by similarity to ideal solution (TOPSIS) model. Findings indicate that 42.8% of the study area, affecting 20% of Mashhad's population, is at heightened risk due to factors such as high illiteracy rates, dense populations, poor built environment quality, and specific geological conditions. The model achieved an area under the curve (AUC) of 0.83, signifying strong discrimination, with Kappa statistics (KNO = 0.60, K standard = 0.56) showing substantial agreement. These insights can be used to inform targeted surveillance and effective disease control strategies.

Effectiveness of carbon dioxide cryotherapy for the treatment of cutaneous leishmaniasis: Systematic review and meta-analysis

BACKGROUND

Cutaneous leishmaniasis is one of the neglected tropical diseases which is hard to treat. Carbon dioxide-based cryotherapy is a novel therapeutic option for cutaneous leishmaniasis in both developed and developing nations. This study aims to summarize the pooled evidence on the effectiveness of carbon dioxide-based cryotherapy for the treatment of cutaneous leishmaniasis.

METHODS

Searches of grey literature using Google Scholar and databases including PubMed, Scopus, EMBASE, Web of Science, and Google Scholar were conducted to find studies that reported the cure rate of cryotherapy. The search, screening, data extraction, and critical evaluation were carried out by two authors, with a third acting as a tiebreaker. To locate papers, we used Medical Subject Headings (MeSH) phrases and keywords. Between May 10 and May 13, 2023, the review protocol was developed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist. For the meta-analysis, STATA 17 was the statistical software used. The random effects model was employed to compile the effect estimates. Lastly, we used the funnel plot and Egger's test to evaluate publication bias, heterogeneity, sensitivity, and subgroup analyses.

RESULT

Out of the 16 researches included in the review, seven papers with a total of 1,357 cases were chosen for the meta-analysis. For the treatment of cutaneous leishmaniasis, the pooled cure rate with carbon dioxide-based cryotherapy was 87.84% (95% CI: 65.92-109.77). Randomized controlled trials made up the majority of the studies that were used. The highest cure rate was seen when there were two lesions, 94.34% (95% CI:68.21-119.48), and when the size of the lesion was less than or equal to 4, 93.83% (95% CI:68.92-118.75). There was no indication of a significant publishing bias.

CONCLUSION

Carbon dioxide-based cryotherapy revealed a high pooled efficacy. The efficacy of the CL instances was mostly dependent on the extent of the lesion and the frequency of therapy administration. To determine if this therapy is beneficial in a routine care context, a large-scale study with a sound design is necessary.

Contribution of epidermal growth factor (EGF) in the treatment of cutaneous leishmaniasis caused by Leishmania major in BALB/c mice

Cutaneous leishmaniasis (CL) is a tropical disease that can cause chronic lesions and leave life-long scars, leading to social stigmatization and psychological disorders. Using growth factors and immunomodulatory agents that could accelerate wound healing and reduce the scar is highly demanded. Epidermal growth factor (EGF) plays an essential role in wound healing. It stimulates the proliferation of keratocytes and fibroblasts, and promotes re-epithelialization. Here, the effect of EGF in combination with Glucantime and nano-liposomal Amphotericin B (SinaAmpholeish) on the healing process of CL in BALB/c mice was investigated. Seventy-two mice were infected with Leishmania major parasites and randomly divided into eight treatment groups after the appearance of the lesion. The treatment was continued for five weeks, and lesion sizes were measured weekly. Parasite load was determined in the skin biopsies using qPCR. We found that subcutaneous injection of EGF at 4.5 μg/kg, combined with each of the two antileishmanial drugs, significantly reduced the wound size and parasite load; however, EGF at 1.5 μg/kg failed to be effective. Besides, the wound size and parasite loads were significantly lower in the SinaAmfoleish groups compared to the Glucantime groups. Among the treatment groups, EGF 4.5 μg/kg combined with SinaAmpholeish exhibited the most significant reduction in wound size and parasitic load. Our results suggest that EGF can potentiate the wound healing effect of antileishmanial drugs. Further studies are warranted to explore the beneficial effects of combining EGF with antileishmanial drugs in patients with cutaneous leishmaniasis in order to accelerate wound healing and reduce the scar.

In vitro Antileishmanial Activity and In silico Molecular Modeling Studies of Novel Analogs of Dermaseptins S4 and B2

BACKGROUND

Leishmaniasis is responsible for approximately 65,000 annual deaths. Various Leishmania species are the predominant cause of visceral, cutaneous, or mucocutaneous leishmaniasis, affecting millions worldwide. The lack of a vaccine, emergence of resistance, and undesirable side effects caused by antileishmanial medications have prompted researchers to look for novel therapeutic approaches to treat this disease. Antimicrobial peptides (AMPs) offer an alternative for promoting the discovery of new drugs.

METHODS

In this study, we detail the synthesis process and investigate the antileishmanial activity against Leishmania (Viannia) braziliensis for peptides belonging to the dermaseptin (DS) family and their synthetic analogs. The MTT assay was performed to investigate the cytotoxicity of these peptides on the murine macrophage cell line RAW 264.7. Subsequently, we performed molecular modeling analysis to explore the structure-function correlation of the derivatives interacting with the parasitic membrane.

RESULTS

All examined derivatives displayed concentration-dependent antileishmanial effect at low concentrations. Their effectiveness varied according to the peptide's proprieties. Notably, peptides with higher levels of charge demonstrated the most pronounced activities. Cytotoxicity assays showed that all the tested peptides were not cytotoxic compared to the tested conventional drug. The structure-function relationships demonstrated that the charged N-terminus could be responsible for the antileishmanial effect observed on promastigotes.

CONCLUSION

Collectively, these results propose that dermaseptins (DS) might offer potential as promising candidates for the development of effective antileishmanial therapies.

Anti-leishmanial activity of Hypericum Scabrum extract against Leishmania major

Leishmaniasis is a vector-borne disease and one of the most significant neglected tropical diseases. Current anti-leishmanial treatments are often ineffective over extended periods and are associated with toxic side effects, highlighting the urgent need for new, effective, and safe alternative treatments for this infectious disease. The objective of this study was to evaluate the anti-leishmanial effects of a hydroalcoholic extract of Hypericum scabrum (H. scabrum), comparing its efficacy to that of the control drug glucantime against the standard strain of Leishmania major. The H. scabrum plants were collected from the western regions of Iran. A hydroalcoholic extract was prepared from the flower and stem of the plant using a maceration method. High-performance liquid chromatography analysis was conducted to identify the chemical compounds present in the extract. Promastigotes of L. major were cultured, and the anti-leishmanial activity of the extracts was assessed at concentrations ranging from 12.5 to 800 µg/ml using the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] assay. The half-maximal inhibitory concentration (IC50) values for the H. scabrum plant extract at 24, 48, and 72 h were 245.47, 141.25 and 85.11 μg/ml, respectively. The IC50 values for glucantime (the control drug) at 24 h, 48 h, and 72 h were 30.19, 21.37, and 12.58 μg/ml, respectively. While the H. scabrum extract exhibited a lower effect compared to the control drug, it still demonstrated a significant inhibitory effect on the promastigote form of L. major. Given that the plant extract of H. scabrum has demonstrated promising anti-leishmanial effects against L. major promastigotes, further studies are warranted to evaluate the efficacy of these extracts in animal models of leishmaniasis.

Spatial and temporal modeling of the global burden of Cutaneous Leishmaniasis in Brazil: A 21-year ecological study

BACKGROUND

Cutaneous Leishmaniasis (CL) is a neglected tropical disease endemic in Brazil. Morbidity and disabilities caused by CL lesions require an analysis of a Global Burden of Disease (GBD), which would help discern the impact on the Brazilian population. Herein, we assess the burden of CL and its spatial and temporal patterns in Brazil between 2001 and 2021.

METHODOLOGY/PRINCIPAL FINDINGS

We estimated rates per 100,000 population for years lived with disabilities (YLD), years of life lost prematurely (YLL) and disability-adjusted life years (DALY) for each year of the study, sex assigned at birth, age group, and for each municipality in Brazil. In addition, the relative changes in these metrics over time for each region and sex were determined, as well as temporal trends using segmented joinpoint regression models. Using spatiotemporal analysis tools, we created choropleth maps representing DALY, YLD and YLL for three distinct periods (P1 = 2001 to 2007; P2 = 2008 to 2014; P3 = 2015 to 2021). These maps were constructed to visualize the inferences from Bayesian spatial statistics and Moran's autocorrelation using the Poisson model. The data were obtained from the DATASUS database. Although the global burden of CL has reduced over two decades, with the continual high impact among adults aged 20 to 39 years. In turn, YLL increased over time in 40-year-old populations, while among the elderly (>60 years old) this rate almost doubled from 2010 to 2021. Regarding the region of residence, we observed an average increase of 28% in YLL in Southeast, South and Central-West. Furthermore, the global burden of CL does not have a random spatial distribution, since there was a high-risk clustering of YLD in the north of the country. Interestingly, the YLL showed a vast geographic expansion through Brazilian territory.

CONCLUSIONS

This study provides a comprehensive analysis of the burden of CL in Brazil, pointing out areas of highest disease burden, where control and surveillance efforts should be undertaken.

Cutaneous leishmaniasis mimicking psoriasis: A case report

Scalp lesions associated with psoriasis and cutaneous leishmaniasis can be clinically indistinguishable, leading to misdiagnosis. Herein, we highlight a 70-year-old male initially misdiagnosed with psoriasis but subsequently confirmed to have cutaneous leishmaniasis. This emphasizes the importance of considering alternative diagnoses, especially in atypical presentations, to ensure accurate treatment.

Immunizing Mice with Influenza Virus-like Particles Expressing the Leishmania amazonensis Promastigote Surface Antigen Alleviates Inflammation in Footpad

Cutaneous leishmaniasis (CL) is a tropical disease endemic in many parts of the world. Characteristic clinical manifestations of CL include the formation of ulcerative skin lesions that can inflict life-long disability if left untreated. Although drugs are available, they are unaffordable and out of reach for individuals who need them the most. Developing a highly cost-efficient CL vaccine could address this problem but such a vaccine remains unavailable. Here, we developed a chimeric influenza virus-like particle expressing the Leishmania amazonensis promastigote surface antigen (LaPSA-VLP). LaPSA-VLPs were self-assembled in Spodoptera frugiperda insect cell lines using the baculovirus expression system. After characterizing the vaccines and confirming successful VLP assembly, BALB/c mice were immunized with these vaccines for efficacy assessment. Sera acquired from mice upon subcutaneous immunization with the LaPSA-VLP specifically interacted with the L. amazonensis soluble total antigens. LaPSA-VLP-immunized mice elicited significantly greater quantities of parasite-specific IgG from the spleens, popliteal lymph nodes, and footpads than unimmunized mice. LaPSA-VLP immunization also enhanced the proliferation of B cell populations in the spleens of mice and significantly lessened the CL symptoms, notably the footpad swelling and IFN-γ-mediated inflammatory response. Overall, immunizing mice with the LaPSA-VLPs prevented mice from developing severe CL symptoms, signifying their developmental potential.

Deciphering Molecular Mechanisms of Cutaneous Leishmaniasis, Pathogenesis and Drug Repurposing through Systems Biology

Background

Cutaneous leishmaniasis (CL) is a major health problem caused by an intracellular pathogen of the genus Leishmania. CL results in morphologically distinct skin injuries, ranging from nodules to plaques and ulcers, which persist as a recuperating incessant injury depending on the type of contaminating parasite. There is still no effective treatment to reduce the skin lesions in patients infected with CL. The aim of this study was to develop strategies to treat skin lesions in CL patients.

Methods

We retrieved the transcriptomic data of skin lesions from patients with CL and normal skin from the gene Expression Omnibus (GEO) database. The protein-protein interaction network (PPIN) was constructed using the STRING database and Cytoscape v3.10.1 software. Critical genes were identified by topological network analysis and cluster detection. Finally, gene ontology and repurposing drugs for critical genes were determined.

Results

CD8A, IFNG, IL-6, PTPRC, CCR7, TLR2, GSTA5, CYBB, IL-12RB2, ITGB2, FCGR3A, CTLA4, and IFNG were identified as the critical genes in PPIN and subnetworks. Enrichment analysis revealed that T-cell receptor signaling, toll-like receptor signaling, cytokine-cytokine receptor interaction, graft-versus-host disease, leishmaniasis, chemokine signaling, primary immunodeficiency, and Th17 cell differentiation were the major pathways associated with critical genes. The drug repurposing results identified cyclosporine, rituximab, infliximab, blinatumomab, and methylprednisolone as candidates for treatment of CL.

Conclusion

After validating our model with available experimental data, we found that critical molecules and drug candidates play a crucial role in the treatment of skin lesions caused by Leishmania in prospective studies.

Sterol 14-alpha demethylase (CYP51) activity in Leishmania donovani is likely dependent upon cytochrome P450 reductase 1

Liposomal amphotericin B is an important frontline drug for the treatment of visceral leishmaniasis, a neglected disease of poverty. The mechanism of action of amphotericin B (AmB) is thought to involve interaction with ergosterol and other ergostane sterols, resulting in disruption of the integrity and key functions of the plasma membrane. Emergence of clinically refractory isolates of Leishmania donovani and L. infantum is an ongoing issue and knowledge of potential resistance mechanisms can help to alleviate this problem. Here we report the characterisation of four independently selected L. donovani clones that are resistant to AmB. Whole genome sequencing revealed that in three of the moderately resistant clones, resistance was due solely to the deletion of a gene encoding C24-sterol methyltransferase (SMT1). The fourth, hyper-resistant resistant clone (>60-fold) was found to have a 24 bp deletion in both alleles of a gene encoding a putative cytochrome P450 reductase (P450R1). Metabolic profiling indicated these parasites were virtually devoid of ergosterol (0.2% versus 18% of total sterols in wild-type) and had a marked accumulation of 14-methylfecosterol (75% versus 0.1% of total sterols in wild-type) and other 14-alpha methylcholestanes. These are substrates for sterol 14-alpha demethylase (CYP51) suggesting that this enzyme may be a bona fide P450R specifically involved in electron transfer from NADPH to CYP51 during catalysis. Deletion of P450R1 in wild-type cells phenocopied the metabolic changes observed in our AmB hyper-resistant clone as well as in CYP51 nulls. Likewise, addition of a wild type P450R1 gene restored sterol profiles to wild type. Our studies indicate that P450R1 is essential for L. donovani amastigote viability, thus loss of this gene is unlikely to be a driver of clinical resistance. Nevertheless, investigating the mechanisms underpinning AmB resistance in these cells provided insights that refine our understanding of the L. donovani sterol biosynthetic pathway.

American Cutaneous Leishmaniasis: Imported cases in Berlin 2000-2023

BACKGROUND

American Cutaneous Leishmaniasis (ACL) shows variable response to therapy, but data on species-specific treatment efficacy is scarce. We describe the clinical characteristics and outcome of patients with ACL imported to a tertiary centre in Germany and determine whether species-specific therapy according to the 2014 "LeishMan" group recommendations is associated with cure.

METHODS

A retrospective chart review was conducted at the Charité Institute of International Health in Berlin. We analysed data on PCR-confirmed ACL cases collected between 2000 and 2023. Systemic therapy included liposomal amphotericin B, miltefosine, pentavalent antimony, ketoconazole or itraconazole. Localized therapy included perilesional pentavalent antimony or paromomycin ointment. Cure was defined as re-epithelialization of ulcers or disappearance of papular-nodular lesions after 3 months of treatment. Logistic regression models were used to quantify the effect of species-specific systemic therapy on the outcome.

RESULTS

75 cases were analysed. Most patients were male (62%), median age was 35 years, no patient had a history of immunosuppression. The most common reason for travel was tourism (60%), the most common destination was Costa Rica (28%), the median duration of illness was 8 weeks, and most patients presented with ulcers (87%). Lesions were complex in 43%. The most common Leishmania (L.) species was L. braziliensis (28%), followed by L. panamensis (21%). 51/73 (70%) patients were cured after initial therapy and 17/21 (81%) after secondary therapy. Cure after systemic therapy was more frequent when species-specific treatment recommendations were followed (33/45; 73%), compared to when not followed, (6/17; 35%, P = 0.008). This association was independent of age, sex, previous therapy, complex lesions, and Leishmania species (adjusted OR, 5.06; 95% CI, 1.22-24.16).

CONCLUSIONS

ACL is a rare, imported disease in Germany. Complex lesions were common, challenging successful therapy. This study highlights the importance of identifying the parasite species and suggests that a species-specific approach to treatment leads to better outcomes.

N6-methyltubercidin gives sterile cure in a cutaneous Leishmania amazonensis mouse model

Leishmania is a trypanosomatid parasite that causes skin lesions in its cutaneous form. Current therapies rely on old and expensive drugs, against which the parasites have acquired considerable resistance. Trypanosomatids are unable to synthesize purines relying on salvaging from the host, and nucleoside analogues have emerged as attractive antiparasitic drug candidates. 4-Methyl-7-β-D-ribofuranosyl-7H-pyrrolo[2,3-d]pyrimidine (CL5564), an analogue of tubercidin in which the amine has been replaced by a methyl group, demonstrates activity against Trypanosoma cruzi and Leishmania infantum. Herein, we investigated its in vitro and in vivo activity against L. amazonensis. CL5564 was 6.5-fold (P = 0.0002) more potent than milteforan™ (ML) against intracellular forms in peritoneal mouse macrophages, and highly selective, while combination with ML gave an additive effect. These results stimulated us to study the activity of CL5564 in mouse model of cutaneous Leishmania infection. BALB/c female and male mice infected by L. amazonensis treated with CL5564 (10 mg kg−1, intralesional route for five days) presented a >93% reduction of paw lesion size likely ML given orally at 40 mg kg−1, while the combination (10 + 40 mg kg−1 of CL5564 and ML, respectively) caused >96% reduction. The qPCR confirmed the suppression of parasite load, but only the combination approach reached 66% of parasitological cure. These results support additional studies with nucleoside derivatives.

Design and Synthesis of Novel 3-Nitro-1H-1,2,4-triazole-1,2,3-triazole-1,4-disubstituted Analogs as Promising Antitrypanosomatid Agents: Evaluation of In Vitro Activity against Chagas Disease and Leishmaniasis

A series of 28 compounds, 3-nitro-1H-1,2,4-triazole, were synthesized by click-chemistry with diverse substitution patterns using medicinal chemistry approaches, such as bioisosterism, Craig-plot, and the Topliss set with excellent yields. Overall, the analogs demonstrated relevant in vitro antitrypanosomatid activity. Analog 15g (R1 = 4-OCF3-Ph, IC50 = 0.09 μM, SI = >555.5) exhibited an outstanding antichagasic activity (Trypanosoma cruzi, Tulahuen LacZ strain) 68-fold more active than benznidazole (BZN, IC50 = 6.15 μM, SI = >8.13) with relevant selectivity index, and suitable LipE = 5.31. 15g was considered an appropriate substrate for the type I nitro reductases (TcNTR I), contributing to a likely potential mechanism of action for antichagasic activity. Finally, 15g showed nonmutagenic potential against Salmonella typhimurium strains (TA98, TA100, and TA102). Therefore, 3-nitro-1H-1,2,4-triazole 15g is a promising antitrypanosomatid candidate for in vivo studies.

Curcumin-loaded nanostructured systems for treatment of leishmaniasis: a review

Leishmaniasis is a neglected tropical disease that has affected more than 350 million people worldwide and can manifest itself in three different forms: cutaneous, mucocutaneous, or visceral. Furthermore, the current treatment options have drawbacks which compromise efficacy and patient compliance. To face this global health concern, new alternatives for the treatment of leishmaniasis have been explored. Curcumin, a polyphenol obtained from the rhizome of turmeric, exhibits leishmanicidal activity against different species of Leishmania spp. Although its mechanism of action has not yet been fully elucidated, its leishmanicidal potential may be associated with its antioxidant and anti-inflammatory properties. However, it has limitations that compromise its clinical use. Conversely, nanotechnology has been used as a tool for solving biopharmaceutical challenges associated with drugs, such as curcumin. From a drug delivery standpoint, nanocarriers (1-1000 nm) can improve stability, increase solubility, promote intracellular delivery, and increase biological activity. Thus, this review offers a deep look into curcumin-loaded nanocarriers intended for the treatment of leishmaniasis.

Antimony resistance and gene expression in Leishmania: spotlight on molecular and proteomic aspects

Leishmaniasis is a vector-borne parasitic disease caused by Leishmania parasites with a spectrum of clinical manifestations, ranging from skin lesions to severe visceral complications. Treatment of this infection has been extremely challenging with the concurrent emergence of drug resistance. The differential gene expression and the discrepancies in protein functions contribute to the appearance of 2 distinct phenotypes: resistant and sensitive, but the current diagnostic tools fail to differentiate between them. The identification of gene expression patterns and molecular mechanisms coupled with antimony (Sb) resistance can be leveraged to prompt diagnosis and select the most effective treatment methods. The present study attempts to use comparative expression of Sb resistance-associated genes in resistant and sensitive Leishmania, to disclose their relative abundance in clinical or in vitro selected isolates to gain an understanding of the molecular mechanisms of Sb response/resistance. Data suggest that the analysis of resistance gene expression would verify the Sb resistance or susceptibility only to a certain extent; however, none of the individual expression patterns of the studied genes was diagnostic as a biomarker of Sb response of Leishmania. The findings highlighted will be useful in bridging the knowledge gap and discovering innovative diagnostic tools and novel therapeutic targets.

Nanotechnology-Based Strategies in Parasitic Disease Management: From Prevention to Diagnosis and Treatment

Parasitic infections are a major global health issue causing significant mortality and morbidity. Despite substantial advances in the diagnostics and treatment of these diseases, the currently available options fall far short of expectations. From diagnosis and treatment to prevention and control, nanotechnology-based techniques show promise as an alternative approach. Nanoparticles can be designed with specific properties to target parasites and deliver antiparasitic medications and vaccines. Nanoparticles such as liposomes, nanosuspensions, polymer-based nanoparticles, and solid lipid nanoparticles have been shown to overcome limitations such as limited bioavailability, poor cellular permeability, nonspecific distribution, and rapid drug elimination from the body. These nanoparticles also serve as nanobiosensors for the early detection and treatment of these diseases. This review aims to summarize the potential applications of nanoparticles in the prevention, diagnosis, and treatment of parasitic diseases such as leishmaniasis, malaria, and trypanosomiasis. It also discusses the advantages and disadvantages of these applications and their market values and highlights the need for further research in this field.

Design, Synthesis, and Repurposing of Rosmarinic Acid-β-Amino-α-Ketoamide Hybrids as Antileishmanial Agents

A series of rosmarinic acid-β-amino-α-ketoamide hybrids were synthesized and rationally repurposed towards the identification of new antileishmanial hit compounds. Two hybrids, 2g and 2h, showed promising activity (IC50 values of 9.5 and 8.8 μM against Leishmania donovani promastigotes, respectively). Their activities were comparable to erufosine. In addition, cytotoxicity evaluation employing human THP-1 cells revealed that the two hybrids 2g and 2h possess no cytotoxic effects up to 100 µM, while erufosine possessed cytotoxicity with CC50 value of 19.4 µM. In silico docking provided insights into structure-activity relationship emphasizing the importance of the aliphatic chain at the α-carbon of the cinnamoyl carbonyl group establishing favorable binding interactions with LdCALP and LARG in both hybrids 2g and 2h. In light of these findings, hybrids 2g and 2h are suggested as potential safe antileishmanial hit compounds for further development of anti-leishmanial agents.

Amphotericin B-Loaded Extracellular Vesicles Derived from Leishmania major Enhancing Cutaneous Leishmaniasis Treatment through In Vitro and In Vivo Studies

Background

Recent studies have shown an increasing number of patients with cutaneous leishmaniasis (CL) who do not respond to pentavalent antimonials as the first line of treatment for CL. Nanocarriers such as extracellular vesicles (EVs) are efficient vehicles that might be used as drug delivery systems for the treatment of diseases. Therefore, we aimed to isolate and characterize the EVs of Leishmania major, load them with Amphotericin B (AmB), and investigate the toxicity and efficacy of the prepared drug form.

Methods

The EVs of L. major were isolated, characterized, and loaded with amphotericin B (AmB), and the EVs-Amphotericin B (EVs-AmB) form was synthesized. Relevant in vitro and in vivo methods were performed to evaluate the toxicity and efficacy of EVs-AmB compared to the control.

Results

The anti-leishmanial activity of the EVs-AmB showed a higher percentage inhibition (PI%) (P = 0.023) compared to the AmB at different concentrations and time points. Obtained data showed a significant increase in the lesion size and parasite load in the lesion, PBS, and EVs mice groups in comparison with EVs-AmB, AmB, and Glucantime groups (P < 0.05), EVs-AmB had a significant decrease in lesion sizes in comparison with AmB (P < 0.05). Results showed that EVs-AmB decreased its toxicity to the kidneys and liver (P < 0.05).

Conclusion

EVs-AmB improved the efficacy of AmB in mouse skin lesions and reduced hepatorenal toxicity. Furthermore, EVs could be a promising nanoplatform for the delivery of AmB in CL caused by L. major.

Exploring the leishmanicidal potential of terpenoids: a comprehensive review on mechanisms of cell death

Leishmaniasis is a neglected tropical disease with a wide spectrum of clinical manifestations, ranging from visceral to cutaneous, with millions of new cases and thousands of deaths reported each year. The species of Leishmania and the immune response of the host determine the severity of the disease. Leishmaniasis remains challenging to diagnose and treat, and there is no vaccine available. Several studies have been conducted on the use of herbal medicines for the treatment of leishmaniasis. Natural products can provide an inexhaustible source of chemical diversity with therapeutic potential. Terpenes are a class of natural products derived from a single isoprene unit, a five-carbon compound that forms the basic structure of isoprenoids. This review focuses on the most important and recent advances in the treatment of parasites of the genus Leishmania with different subclasses of terpenes. Several mechanisms have been proposed in the literature, including increased oxidative stress, immunomodulatory role, and induction of different types of parasite cell death. However, this information needs to be brought together to provide an overview of how these compounds can be used as therapeutic tools for drug development and as a successful adjuvant strategy against Leishmania sp.

Effect of Intralesional Sodium Stibogluconate Alone versus Combinations with Topical Trichloroacetic Acid 50% or Fractional Carbon Dioxide Laser on Cutaneous Leishmaniasis

Background

Cutaneous leishmaniasis (CL) is a vector-borne protozoal disease. Antimonial drugs remain the first-line treatment for CL despite the widespread drug resistance and high incidence of side effects. The present study aimed to compare the efficacy and safety of traditional intralesional sodium stibogluconate (SSG) alone and its combinations with trichloroacetic acid (TCA) 50% and fractional carbon dioxide (CO2) laser for the treatment of CL.

Materials and Methods

An interventional study was carried out on 25 CL patients. In each patient, three lesions were assigned to treatment either by SSG alone (GI), SSG plus TCA 50% (GII), or SSG plus fractional CO2 laser (GIII). The overall clinical improvement and changes in the sizes of lesions and scars were assessed and compared among the three groups.

Results

GIII patients had significantly lower treatment sessions as compared to GI patients (3.6 ± 1.29 versus 4.04 ± 2.11, P = 0.042). Moreover, GII and GIII patients had significantly shorter healing times when compared with GI (3.63 ± 1.35 and 3.46 ± 1.25, respectively, versus 4.0 ± 2.15 weeks, P = 0.019). Also, it was shown that GIII patients had significantly lower scar scores (1.40 ± 1.52) when compared with GI (3.00 ± 0.0) and GII (2.80 ± 1.10), P = 0.017.

Conclusions

Intralesional SSG with TCA 50% is more effective than SSG alone and is comparable to SSG and fractional CO2 combination in the treatment of CL with better safety profile and patient satisfaction.

Strengthening collaborations at the Biology-Physics interface: trends in antimicrobial photodynamic therapy

The unbridled use of antimicrobial drugs over the last decades contributed to the global dissemination of drug-resistant pathogens and increasing rates of life-threatening infections for which limited therapeutic options are available. Currently, the search for safe, fast, and effective therapeutic strategies to combat infectious diseases is a worldwide demand. Antimicrobial photodynamic therapy (APDT) rises as a promising therapeutic approach against a wide range of pathogenic microorganisms. APDT combines light, a photosensitizing drug (PS), and oxygen to kill microorganisms by oxidative stress. Since the APDT field involves branches of biology and physics, the strengthening of interdisciplinary collaborations under the aegis of biophysics is welcome. Given this scenario, Brazil is one of the global leaders in the production of APDT science. In this review, we provide detailed reports of APDT studies published by the Laboratory of Optical Therapy (IPEN-CNEN), Group of Biomedical Nanotechnology (UFPE), and collaborators over the last 10 years. We present an integrated perspective of APDT from basic research to clinical practice and highlight its promising use, encouraging its adoption as an effective and safe technology to tackle important pathogens. We cover the use of methylene blue (MB) or Zn(II) porphyrins as PSs to kill bacteria, fungi, parasites, and pathogenic algae in laboratory assays. We describe the impact of MB-APDT in Dentistry and Veterinary Medicine to treat different infectious diseases. We also point out future directions combining APDT and nanotechnology. We hope this review motivates further APDT studies providing intuitive, vivid, and insightful information for the readers.

Field-Deployable Treatments For Leishmaniasis: Intrinsic Challenges, Recent Developments and Next Steps

Leishmaniasis is a neglected tropical disease endemic primarily to low- and middle-income countries, for which there has been inadequate development of affordable, safe, and efficacious therapies. Clinical manifestations of leishmaniasis range from self-healing skin lesions to lethal visceral infection with chances of relapse. Although treatments are available, secondary effects limit their use outside the clinic and negatively impact the quality of life of patients in endemic areas. Other non-medicinal treatments, such as thermotherapies, are limited to use in patients with cutaneous leishmaniasis but not with visceral infection. Recent studies shed light to mechanisms through which Leishmania can persist by hiding in cellular safe havens, even after chemotherapies. This review focuses on exploring the cellular niches that Leishmania parasites may be leveraging to persist within the host. Also, the cellular, metabolic, and molecular implications of Leishmania infection and how those could be targeted for therapeutic purposes are discussed. Other therapies, such as those developed against cancer or for manipulation of the ferroptosis pathway, are proposed as possible treatments against leishmaniasis due to their mechanisms of action. In particular, treatments that target hematopoietic stem cells and monocytes, which have recently been found to be necessary components to sustain the infection and provide a safe niche for the parasites are discussed in this review as potential field-deployable treatments against leishmaniasis.

A review on new natural and synthetic anti-leishmanial chemotherapeutic agents and current perspective of treatment approaches

Leishmaniases are considered among the most neglected yet dangerous parasitic diseases worldwide. According to the recent WHO report (Weekly Epidemiological Record, Sep, 2021), 200 countries and territories reported leishmanises cases in 2020; of which 89 (45%) for CL, and 79 (40%) for VL were endemic. Indian subcontinent (India, Bangladesh and Nepal), one of the three eco-epidemiological hotspots of VL, currently reported 18% of the total cases of VL worldwide. Eastern Mediterranean region and the Region of the Americas together reported >90% of the new CL cases, of which >80% were from Afghanistan, Algeria, Brazil, Colombia, Iraq, Pakistan and the Syrian Arab Republic. While considering the current therapeutic options, conventional anti-leishmanial drugs have long been proved to be toxic and/or expensive and have resulted in extensive drug resistance in India. Recent searches for novel anti-leishmanial drugs have led to find out the prime cellular targets and metabolic pathways to bridge the gap between the known facts and unexplored data. Cutting edge knowledge based drug designing has simplified the search for novel molecules with leishmanicidal efficacy by identifying ligand-receptor interactions and has accelerated the cost effective primary discovery of molecules through computational validation against Leishmaniases. This review focuses on the limitations of conventional drugs, and discusses the chemotherapeutic potential of many novel natural and synthetic anti-leishmanial agents reported since the last decade. It is also interpreted that some of the reported molecules might be tested singly or as a part of combinatorial therapy on pre-clinical and clinical level.

In Vivo Safety and Efficacy of Chalcone-Loaded Microparticles with Modified Polymeric Matrix against Cutaneous Leishmaniasis

Current chemotherapy of cutaneous leishmaniasis (CL) is based on repeated systemic or intralesional administration of drugs that often cause severe toxicity. Previously, we demonstrated the therapeutic potential of biodegradable poly(lactic-co-glycolic acid) (PLGA) microparticles (MPs) loaded with 8% of the nitrochalcone CH8 (CH8/PLGA) prepared by a conventional bench method. Aiming at an industrially scalable process and increased drug loading, new MPs were prepared by spray drying: CH8/PDE with PLGA matrix and CH8/PVDE with PLGA + polyvinylpyrrolidone (PVP) matrix, both with narrower size distribution and higher drug loading (18%) than CH8/PLGA. Animal studies were conducted to evaluate their clinical feasibility. Both MP types induced transient local swelling and inflammation, peaking at 1−2 days, following a single intralesional injection. Different from CH8/PDE that released 90% of the drug in the ear tissue in 60 days, CH8/PVDE achieved that in 30 days. The therapeutic efficacy of a single intralesional injection was evaluated in BALB/c mice infected with Leishmania (Leishmania) amazonensis and golden hamsters infected with L. (Viannia) braziliensis. CH8/PVDE promoted greater reduction in parasite burden than CH8/PDE or CH8/PLGA, measured at one month and two months after the treatment. Thus, addition of PVP to PLGA MP matrix accelerates drug release in vivo and increases its therapeutic effect against CL.

Direct In Vitro Comparison of the Anti-Leishmanial Activity of Different Olive Oil Total Polyphenolic Fractions and Assessment of Their Combined Effects with Miltefosine

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.

Synthesis, Structure and Antileishmanial Evaluation of Endoperoxide–Pyrazole Hybrids

Leishmaniases are among the most impacting neglected tropical diseases. In attempts to repurpose antimalarial drugs or candidates, it was found that selected 1,2,4-trioxanes, 1,2,4,5-tetraoxanes, and pyrazole-containing chemotypes demonstrated activity against Leishmania parasites. This study reports the synthesis and structure of trioxolane–pyrazole (OZ1, OZ2) and tetraoxane–pyrazole (T1, T2) hybrids obtained from the reaction of 3(5)-aminopyrazole with endoperoxide-containing building blocks. Interestingly, only the endocyclic amine of 3(5)-aminopyrazole was found to act as nucleophile for amide coupling. However, the fate of the reaction was influenced by prototropic tautomerism of the pyrazole heterocycle, yielding 3- and 5-aminopyrazole containing hybrids which were characterized by different techniques, including X-ray crystallography. The compounds were evaluated for in vitro antileishmanial activity against promastigotes of L. tropica and L. infantum, and for cytotoxicity against THP-1 cells. Selected compounds were also evaluated against intramacrophage amastigote forms of L. infantum. Trioxolane–pyrazole hybrids OZ1 and OZ2 exhibited some activity against Leishmania promastigotes, while tetraoxane–pyrazole hybrids proved inactive, most likely due to solubility issues. Eight salt forms, specifically tosylate, mesylate, and hydrochloride salts, were then prepared to improve the solubility of the corresponding peroxide hybrids and were uniformly tested. Biological evaluations in promastigotes showed that the compound OZ1•HCl was the most active against both strains of Leishmania. Such finding was corroborated by the results obtained in assessments of the L. infantum amastigote susceptibility. It is noteworthy that the salt forms of the endoperoxide–pyrazole hybrids displayed a broader spectrum of action, showing activity in both strains of Leishmania. Our preliminary biological findings encourage further optimization of peroxide–pyrazole hybrids to identify a promising antileishmanial lead.

Establish an allele-specific real-time PCR for Leishmania species identification

Background

Leishmaniasis is a serious neglected tropical disease that may lead to life-threatening outcome, which species are closely related to clinical diagnosis and patient management. The current Leishmania species determination method is not appropriate for clinical application. New Leishmania species identification tool is needed using clinical samples directly without isolation and cultivation of parasites.

Methods

A probe-based allele-specific real-time PCR assay was established for Leishmania species identification between Leishmania donovani and L. infantum for visceral leishmaniasis (VL) and among L. major, L. tropica and L. donovani/L. infantum for cutaneous leishmaniasis (CL), targeting hypoxanthine-guanine phosphoribosyl transferase (HGPRT) and spermidine synthase (SPDSYN) gene with their species-specific single nucleotide polymorphisms (SNPs). The limit of detection of this assay was evaluated based on 8 repeated tests with intra-assay standard deviation < 0.5 and inter-assay coefficients of variability < 5%. The specificity of this assay was tested with DNA samples obtained from Plasmodium falciparum, Toxoplasma gondii, Brucella melitensis and Orientia tsutsugamushi. Total 42 clinical specimens were used to evaluate the ability of this assay for Leishmania species identification. The phylogenetic tree was constructed using HGPRT and SPDSYN gene fragments to validate the performance of this assay.

Results

This new method was able to detect 3 and 12 parasites/reaction for VL and CL respectively, and exhibited no cross-reaction with P. falciparum, T. gondii, B. melitensis, O. tsutsugamushi and non-target species of Leishmania. Twenty-two samples from VL patients were identified as L. donovani (n = 3) and L. infantum (n = 19), and 20 specimens from CL patients were identified as L. major (n = 20), providing an agreement of 100% compared with sequencing results. For further validation, 29 sequences of HGPRT fragment from nine Leishmania species and 22 sequences from VL patients were used for phylogenetic analysis, which agreed with the results of this new method. Similar results were obtained with 43 sequences of SPDSYN fragment from 18 Leishmania species and 20 sequences from CL patients.

Conclusions

Our assay provides a rapid and accurate tool for Leishmania species identification which is applicable for species-adapted therapeutic schedule and patient management.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-00992-y.