Amphotericin B for treatment of visceral leishmaniasis: systematic review and meta-analysis of prospective comparative clinical studies including dose-ranging studies

Anti-Leishmania amazonensis Activity of Morolic Acid, a Pentacyclic Triterpene with Effects on Innate Immune Response during Macrophage Infection

Leishmaniasis is a group of infectious diseases transmitted to humans during vector bites and caused by protozoans of the genus Leishmania. Conventional therapies face challenges due to their serious side effects, prompting research into new anti-leishmania agents. In this context, we investigated the effectiveness of morolic acid, a pentacyclic triterpene, on L. amazonensis promastigotes and amastigotes. The present study employed the MTT assay, cytokine analysis using optEIATM kits, an H2DCFDA test, and nitric oxide dosage involving nitrite production and Griess reagent. Morolic acid inhibited promastigote and axenic amastigote growth forms at IC50 values of 1.13 µM and 2.74 µM, respectively. For cytotoxicity to macrophages and VERO cells, morolic acid obtained respective CC50 values of 68.61 µM and 82.94 µM. The compound causes damage to the parasite membrane, leading to cellular leakage. In the infection assay, there was a decrease in parasite load, resulting in a CI50 of 2.56 µM. This effect was associated with immunomodulatory activity, altering macrophage structural and cellular parasite elimination mechanisms. Morolic acid proved to be an effective and selective natural compound, making it a strong candidate for future in vivo studies in cutaneous leishmaniasis.

The leishmaniases in Kenya: A scoping review

BACKGROUND

The leishmaniases are a group of four vector-borne neglected tropical diseases caused by 20 species of protozoan parasites of the genus Leishmania and transmitted through a bite of infected female phlebotomine sandflies. Endemic in over 100 countries, the four types of leishmaniasis-visceral leishmaniasis (VL) (known as kala-azar), cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), and post-kala-azar dermal leishmaniasis (PKDL)-put 1.6 billion people at risk. In Kenya, the extent of leishmaniasis research has not yet been systematically described. This knowledge is instrumental in identifying existing research gaps and designing appropriate interventions for diagnosis, treatment, and elimination.

METHODOLOGY/PRINCIPAL FINDINGS

This study used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology to determine the state of leishmaniases research in Kenya and identify research gaps. We searched seven online databases to identify articles published until January 2022 covering VL, CL, MCL, and/or PKDL in Kenya. A total of 7,486 articles were found, of which 479 underwent full-text screening, and 269 met our eligibility criteria. Most articles covered VL only (n = 141, 52%), were published between 1980 and 1994 (n = 108, 39%), and focused on the theme of "vectors" (n = 92, 34%). The most prevalent study types were "epidemiological research" (n = 88, 33%) tied with "clinical research" (n = 88, 33%), then "basic science research" (n = 49, 18%) and "secondary research" (n = 44, 16%).

CONCLUSION/SIGNIFICANCE

While some studies still provide useful guidance today, most leishmaniasis research in Kenya needs to be updated and focused on prevention, co-infections, health systems/policy, and general topics, as these themes combined comprised less than 4% of published articles. Our findings also indicate minimal research on MCL (n = 1, <1%) and PKDL (n = 2, 1%). We urge researchers to renew and expand their focus on these neglected diseases in Kenya.

Exploring drug repositioning for leishmaniasis treatment: Ivermectin plus polymeric micelles induce immunological response and protection against tegumentary leishmaniasis

Leishmania amazonensis can cause a wide spectrum of the clinical manifestations of leishmaniasis in humans. The development of new therapeutics is a long and expensive task; in this context, drug repositioning could be considered a strategy to identify new biological actions of known products. In the present study, ivermectin (IVE) was tested against distinct Leishmania species able to cause disease in humans. In vitro experiments showed that IVE was effective to reduce the infection degree and parasite load in Leishmania donovani- and L. amazonensis-infected macrophages that were treated with it. In addition, using the culture supernatant of treated macrophages, higher production of IFN-γ and IL-12 and lower levels of IL-4 and IL-10 were found. Then, IVE was used in a pure form or incorporated into Poloxamer 407-based polymeric micelles (IVE/M) for the treatment of L. amazonensis-infected BALB/c mice. Animals (n = 16 per group) were infected and later received saline, empty micelles, amphotericin B (AmpB), IVE, or IVE/M. They were euthanized at one (n = 8 per group) and 30 (n = 8 per group) days after treatment and, in both endpoints, immunological, parasitological, and biochemical evaluations were performed. Results showed that both IVE and IVE/M induced higher levels of IFN-γ, IL-12, GM-CSF, nitrite, and IgG2a antibodies, as well as higher IFN-γ expression evaluated by RT-qPCR in spleen cell cultures. Such animals showed low organic toxicity, as well as significant reductions in the lesion's average diameter and parasite load in their infected tissue, spleen, liver, and draining lymph node. The efficacy was maintained 30 days post-therapy, while control mice developed a polarized Th2-type response and high parasite load. In this context, IVE could be considered as a new candidate to be applied in future studies for the treatment against distinct Leishmania species.

Design, synthesis and evaluation of novel β-carboline ester analogues as potential anti-leishmanial agents

Leishmaniasis is one of today's most neglected diseases. The emergence of new anti-leishmanial therapies emphasizes several study groups funded by the World Health Organization. The present investigation will focus on the research to determine a few new potential derivatives of β-carboline ester derivatives against leishmaniasis. The in-silico predicted ADMET properties of most of the titled compounds are in an acceptable range and having drug like properties. Among all the tested analogs, compound ES-3 (EC₅₀ 3.36 μM; SI > 29.80) showed comparable and equipotent anti-leishmanial activity as that of standard drug miltefosine (EC₅₀ 4.80 μM; SI > 20.80) against amastigote forms of the tested L. infantum strain. Two compounds ES-6 and ES-10 exhibited significant activity with EC₅₀ 10.16, 13.56 μM; SI > 4.90, 7.37, respectively. In-silico based molecular docking and dynamics study of the significantly active analog also performed to study the putative binding mode, interaction pattern at the active site of the target leishmanial trypanothione reductase enzyme as well as stability of the target-ligand complex. The changes in the conformation of molecules during MD (frame wise trajectory analysis) provided new insights for the development of novel potent molecules. These findings will further give insight that will help modify the compound ES-3 for better potency and the design of novel inhibitors for leishmaniasis.Communicated by Ramaswamy H. Sarma.

Evidence map of diagnosis, treatment, prognosis, prevention, and control in visceral leishmaniasis

Objective

To develop an evidence map on visceral leishmaniasis prevention, control, diagnosis, treatment, and prognosis.

Methods

Systematic reviews on visceral leishmaniasis were searched using MEDLINE/PubMed and Virtual Health Library. After selection, each included systematic review was assessed, characterized, and categorized by intervention type and by outcomes, according to the methodology offered by the PAHO/WHO Latin American and Caribbean Center on Health Sciences Information (BIREME). The methodological quality was assessed using the AMSTAR2 tool to determine the confidence level of the evidence obtained.

Results

Among the prevention and control interventions, insecticide spraying, bednets, dog collars, and dog culling were the most assessed, emphasizing that insecticidal dog collars can reduce visceral leishmaniasis incidence in dogs. Regarding diagnosis, polymerase chain reaction (PCR), rK39 immunochromatographic test (rK39 ICT), and direct agglutination test (DAT) presented high sensitivity and specificity. As for treatment, pentavalent antimonials and amphotericin B were the most analyzed drugs and showed therapeutic success; however, serious adverse events can occur due to their use. The prognostic factors identified were anemia, edema, bleeding, jaundice, age, and HIV coinfection.

Conclusions

The evidence map developed shows rK39 ICT and DAT as promising diagnostic alternatives and reinforces the efficacy of liposomal amphotericin B and pentavalent antimonials. Insecticide-impregnated dog collars appear as a promising measure for the control of visceral leishmaniasis, but there is also a need for future studies and reviews with higher methodological quality, especially on prevention and control interventions.

The antimicrobial and immunomodulatory effects of Ionophores for the treatment of human infection

Ionophores are a diverse class of synthetic and naturally occurring ion transporter compounds which demonstrate both direct and in-direct antimicrobial properties against a broad panel of bacterial, fungal, viral and parasitic pathogens. In addition, ionophores can regulate the host-immune response during communicable and non-communicable disease states. Although the clinical use of ionophores such as Amphotericin B, Bedaquiline and Ivermectin highlight the utility of ionophores in modern medicine, for many other ionophore compounds issues surrounding toxicity, bioavailability or lack of in vivo efficacy studies have hindered clinical development. The antimicrobial and immunomodulating properties of a range of compounds with characteristics of ionophores remain largely unexplored. As such, ionophores remain a latent therapeutic avenue to address both the global burden of antimicrobial resistance, and the unmet clinical need for new antimicrobial therapies. This review will provide an overview of the broad-spectrum antimicrobial and immunomodulatory properties of ionophores, and their potential uses in clinical medicine for combatting infection.

Steroid-Functionalized Imidazolium Salts with an Extended Spectrum of Antifungal and Antibacterial Activity

It is established that high rates of morbidity and mortality caused by fungal infections are related to the current limited number of antifungal drugs and the toxicity of these agents. Imidazolium salts as azole derivatives can be successfully used in the treatment of fungal infections in humans. Steroid-functionalized imidazolium salts were synthesized using a new, more efficient method. As a result, 20 salts were obtained with high yields, 12 of which were synthesized and characterized for the first time. They were derivatives of lithocholic acid and 3-oxo-23,24-dinorchol-4-ene-22-al and were fully characterized by ¹H and ¹³C nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and high resolution mass spectrometry (HRMS). Due to the excellent activity against bacteria and Candida albicans, new research was extended to include tests on five species of pathogenic fungi and molds: Aspergillus niger ATCC 16888, Aspergillus fumigatus ATCC 204305, Trichophyton mentagrophytes ATCC 9533, Cryptococcus neoformans ATCC 14116, and Microsporum canis ATCC 11621. The results showed that the new salts are almost universal antifungal agents and have a broad spectrum of activity against other human pathogens. To initially assess the safety of the synthesized salts, hemocompatibility with host cells and cytotoxicity were also examined. No toxicity was observed at the concentration at which the compounds were active against pathogens.

Efficacy and safety of pentamidine isethionate for tegumentary and visceral human leishmaniasis: a systematic review

RATIONALE FOR REVIEW

We performed a systematic review of the literature to investigate the efficacy and safety of pentamidine isethionate for the treatment of human tegumentary and visceral leishmaniasis.

KEY FINDINGS

A total of 616 papers were evaluated, and 88 studies reporting data on 3108 cases of leishmaniasis (2082 patients with tegumentary leishmaniasis and 1026 with visceral leishmaniasis) were finally included. The majority of available studies were on New World cutaneous leishmaniasis and visceral leishmaniasis caused by Leishmania donovani. At the same time, few data are available for Old World cutaneous leishmaniasis, mucosal leishmaniasis, and visceral leishmaniasis caused by L. infantum. Pooled cure rate for tegumentary leishmaniasis was 78.8% (CI 95%, 76.9-80.6%) and 92.7% (CI 95%, 88.3-97.1%) according to controlled randomized trial and observational studies and case report and case series respectively. Pooled cure rate for visceral leishmaniasis was 84.8% (CI 95%, 82.6-87.1%) and 90.7% (CI 95%, 84.1-97.3%) according to controlled randomized trial and observational studies and case report and case series, respectively. Comparable cure rate was observed in recurrent and refractory cases of visceral leishmaniasis. Concerning the safety profile, among about 2000 treated subjects with some available information, the most relevant side effects were six cases of arrhythmia (including four cases of fatal ventricular fibrillation), 20 cases of irreversible diabetes, 26 cases of muscular aseptic abscess following intramuscular administration.

CONCLUSIONS/RECOMMENDATIONS

Pentamidine isethionate is associated with a similar cure rate of the first-line anti-leishmanial drugs. Severe and irreversible adverse effect appear to be rare. The drug may still have a role in the treatment of any form of human leishmaniasis when the first-line option has failed or in patients who cannot tolerate other drugs also in the setting of travel medicine. In difficult cases, the drug can also be considered as a component of a combination treatment regimen.

Synthesis and Antileishmanial Evaluation of Arylimidamide-Azole Hybrids Containing a Phenoxyalkyl Linker

Due to the limitations of existing medications, there is a critical need for new drugs to treat visceral leishmaniasis. Since arylimidamides and antifungal azoles both show oral activity in murine visceral leishmaniasis models, a molecular hybridization approach was employed where arylimidamide and azole groups were separated by phenoxyalkyl linkers in an attempt to capitalize on the favorable antileishmanial properties of both series. Among the target compounds synthesized, a greater antileishmanial potency against intracellular Leishmania donovani was observed as the linker length increased from two to eight carbons and when an imidazole ring was employed as the terminal group compared to a 1,2,4-triazole group. Compound 24c (N-(4-((8-(1H-imidazol-1-yl)octyl)oxy)-2-isopropoxyphenyl) picolinimidamide) displayed activity against L. donovani intracellular amastigotes with an IC₅₀ value of 0.53 μM. When tested in a murine visceral leishmaniasis model, compound 24c at a dose of 75 mg/kg/day p.o. for five consecutive days resulted in a modest 33% decrease in liver parasitemia compared to the control group, indicating that further optimization of these molecules is needed. While potent hybrid compounds bearing an imidazole terminal group were also strong inhibitors of recombinant CYP51 from L. donovani, as assessed by a fluorescence-based assay, additional targets are likely to play an important role in the antileishmanial action of these compounds.

Differentially modulated proteins associated with Leishmaniasis-a systematic review of in-vivo and in-vitro studies

High-throughput proteomic technologies are widely used for understanding the disease mechanism, drug-resistant mechanism, and to identify drug targets and markers for diagnostics. Studies with proteomics applications, relating to Leishmaniasis, are being constantly reported in the literature. However, from such studies, a readily accessible knowledge of differentially modulated proteins associated with Leishmaniasis is lacking. Hence, we performed a systematic review concerning differentially modulated proteins (DMP) in Leishmania as well as host infected with Leishmania from the published articles between the years 2000 and 2019. This review is classified into five different sections, namely, DMP in the host after Leishmania infection, DMP between different strains of Leishmania, DMP in drug-resistant Leishmania, DMP in Leishmania under stress, and DMP in different life stages of Leishmania. A lot of consensuses could be observed among the DMP in drug-resistant and stressed Leishmania. In addition to the review, a database was constructed with the data collected in this study (protein accession ID, protein name, gene name, host organism, experimental conditions, fold change, and regulatory data). A total of 2635 records are available in the database. We believe this review and the database will help the researcher in understanding the disease better and provide information for the targeted proteomics study related to Leishmaniasis. Database availability: http://ldepdb.biomedinformri.com/ .

Lipid Systems for the Delivery of Amphotericin B in Antifungal Therapy

Amphotericin B (AmB), a broad-spectrum polyene antibiotic in the clinic for more than fifty years, remains the gold standard in the treatment of life-threatening invasive fungal infections and visceral leishmaniasis. Due to its poor water solubility and membrane permeability, AmB is conventionally formulated with deoxycholate as a micellar suspension for intravenous administration, but severe infusion-related side effects and nephrotoxicity hamper its therapeutic potential. Lipid-based formulations, such as liposomal AmB, have been developed which significantly reduce the toxic side effects of the drug. However, their high cost and the need for parenteral administration limit their widespread use. Therefore, delivery systems that can retain or even enhance antimicrobial efficacy while simultaneously reducing AmB adverse events are an active area of research. Among those, lipid systems have been extensively investigated due to the high affinity of AmB for binding lipids. The development of a safe and cost-effective oral formulation able to improve drug accessibility would be a major breakthrough, and several lipid systems for the oral delivery of AmB are currently under development. This review summarizes recent advances in lipid-based systems for targeted delivery of AmB focusing on non-parenteral nanoparticulate formulations mainly investigated over the last five years and highlighting those that are currently in clinical trials.

Antileishmanial activity of new hybrid tetrahydroquinoline and quinoline derivatives with phosphorus substituents

Heterocyclic compounds, such as hybrid tetrahydroquinoline and quinoline derivatives with phosphorated groups, have been prepared by multicomponent cycloaddition reaction between phosphorus-substituted anilines, aldehydes and styrenes. The antileishmanial activity of these compounds has been evaluated on both promastigotes and intramacrophagic amastigotes of Leishmania infantum. Good antileishmanial activity of functionalized tetrahydroquinolines 4a, 5a, 6b and quinoline 8b has been observed with similar activity than the standard drug amphotericin B and close selective index (SI between 43 and 57) towards L. infantum amastigotes to amphotericin B. Special interest shows tetrahydroquinolylphosphine sulfide 5a with an EC₅₀ value (0.61 ± 0.18 μM) similar to the standard drug amphotericin B (0.32 ± 0.05 μM) and selective index (SI = 56.87). In addition, compound 4c shows remarkable inhibition on Leishmania topoisomerase IB. Parallel theoretical study of stereoelectronic properties, application of docking-based virtual screening methods, along with molecular electrostatic potential and predictive druggability analyses are also reported.

Treatment outcomes of visceral leishmaniasis in Ethiopia from 2001 to 2017: a systematic review and meta-analysis

Background

Ethiopia has the highest number of visceral leishmaniasis (VL) cases after Sudan in Sub-Saharan Africa. However, there was lack of comprehensive data on VL treatment outcome despite the huge burden of the diseases in the country. Hence, we aimed to perform a systematic review and meta-analysis on this topic to obtain stronger evidence on treatment outcomes of VL from the existing literature in Ethiopia.

Methods

The Cochrane guidelines to conduct meta-analysis following the Preferred Reporting Items for Systematic review and Meta-Analysis statement was used to conduct a computerized systematic search of the PubMed, Google Scholar, and ScienceDirect databases. Random effects model was used to combine studies showing heterogeneity of Cochrane Q P < 0.10 and I² > 50. Treatment outcomes were assessed at end of treatment and at 6 months follow-up. Subgroup analyses were performed on treatment outcomes based on the different antileishmanial treatment options and patients’ HIV status.

Results

Fifteen studies were included in the final analyses. At end of treatment, an overall treatment success rate of 82.6% was noticed. At 6 months follow-up, the overall treatment success rate was 72.2%. For patients treated with sodium stibogluconate (SSG), the treatment success rates at the end of treatment and at six-month follow-up were 81.5% and 80.7%, respectively. Multiple doses of liposomal-amphotericin B (L-AMB) had treatment success rates of 96.7 and 71–100% at the end of treatment and at 6 months follow-up, respectively. The combination of SSG with paromomycin (PM) gave treatment success rates of up to 90.1% at the end of treatment. HIV-infected individuals were found to have a higher mortality (odds ratio = 4.77, 95% CI: 1.30–17.43, P = 0.009) rate at 6 months follow-up.

Conclusions

SSG alone has shown lower treatment efficacy in the management of VL when compared to combination of SSG with PM and multiple doses of L-AMB. The combination of SSG with PM gave good treatment success rates with shorter duration of treatment. Hence, the combination of SSG with PM should be used preferentially over SSG monotherapy. Multiple doses of L-AMB showed great efficacy especially among patients with complications, severe disease, HIV co-infection, and intolerance to the adverse effects of antimonials. HIV-infected individuals had a worse prognosis than their HIV-negative counterparts.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0491-7) contains supplementary material, which is available to authorized users.