Effective Treatment Of Visceral Leishmaniasis Research Articles

The Interaction of Zinc as an Essential Trace Element with Leishmania Parasites: A Systematic Review

Abstract Background: The trace element of zinc (Zn) has shown great effectiveness in control of leishmaniasis infection. Hence, the present study conducted a systematic review of in vitro and in vivo studies evaluating the zinc effect in the treatment or prevention of leishmaniasis. Materials and Methods: A systematic literature search was performed of all articles published in PubMed, SciELO, ScienceDirect, Scopus, Google Scholar, and Web of Science databases (1997–2023). The search terms were “zinc” OR “cutaneous leishmaniasis (CL)” OR “visceral leishmaniasis (VL)”. Results: Initial search yielded 89 citations, and 59 subjects were included. Data showed the zinc serum level in CL patients was lower than controls. Also, in vitro studies of zinc were more effective against L. tropica and L. major promastigotes compared to the amastigotes. Moreover, in vivo studies did not show destructive effects of zinc on the mammalian cell viability like macrophages. Furthermore, zinc depletion by specific chelators affected L. donovani survival and growth through promoting apoptosis and reactive oxygen species-dependent mechanisms. Conclusion: The serum level determination of zinc could be useful for estimating the leishmaniasis pathophysiology. Environmentally or genetically determined increases in zinc levels might augment resístanse to CL. In contrast, zinc depletion using a zinc-specific chelator could be effective treatment of VL in endemic areas.

Oral amodiaquine microparticles repurposed for the treatment of visceral leishmaniasis

BackgroundLeishmaniasis, a neglected tropical disease, is caused by parasites from the genus Leishmania and transmitted by the female phlebotamine sandfly. Visceral leishmaniasis is the systemic and most severe form of the disease, which is brought on by Leishmania donovani and Leishmania infantum complexes. Current treatment options have been plagued with a number of adverse effects, and resistance by the protozoan parasite (Leishmania spp). Following current trends of repurposing drugs, oral formulations of amodiaquine - an antimalarial drug, are tested in visceral leishmaniasis models. MethodsModified-release formulations of Amodiaquine were prepared by encapsulation in Hydroxypropylmethylcellulose using the spray-drying method and evaluated for size, zeta potential, drug content, entrapment efficiency and in vitro release properties. Mice models were created by infection with stationary phase L. donovani promastigotes. Three weeks after infection, mice were treated by orally administering amodiaquine powder or microparticles for two weeks. Amphotericin B and Pentamidine were administered intraperitoneally as Positive Controls and water given orally as a Negative Control. Giemsa-stained histological sections of mice liver and spleen were prepared and observed for parasite presence and drug activity. ResultsThe size range of the amodiaquine microparticles was between 2.01 and 15.9 µm and encapsulation efficiency of 95%. The release of amodiaquine from the microparticles was effectively extended. All three formulations of amodiaquine used were effective in treating the visceral leishmaniasis mouse model used in the study. ConclusionAmodiaquine, an anti-malarial drug, can be repurposed in all oral formulations for the safe and effective treatment of visceral leishmaniasis.

Functionalized 1,2,3-triazolium salts as potential agents against visceral leishmaniasis.

Visceral leishmaniasis (VL) is the most severe clinical form of leishmaniasis, being fatal if untreated. In search of a more effective treatment for VL, one of the main strategies is the development and screening of new antileishmanial compounds. Here, we reported the synthesis of seven new acetyl functionalized 1,2,3-triazolium salts, together with four 1,2,3-triazole precursors, and investigated their effect against different strains of L. infantum from dogs and humans. The 1,2,3-triazolium salts exhibited better activity than the 1,2,3-triazole derivatives with IC50 range from 0.12 to 8.66μM and, among them, compound 5 showed significant activity against promastigotes (IC50 from 4.55 to 5.28μM) and intracellular amastigotes (IC50 from 5.36 to 7.92μM), with the best selective index (SI ~ 6-9) and reduced toxicity. Our findings, using biochemical and ultrastructural approaches, demonstrated that compound 5 targets the mitochondrion of L. infantum promastigotes, leading to the formation of reactive oxygen species (ROS), increase of the mitochondrial membrane potential, and mitochondrial alteration. Moreover, quantitative transmission electron microscopy (TEM) revealed that compound 5 induces the reduction of promastigote size and cytoplasmic vacuolization. Interestingly, the effect of compound 5 was not associated with apoptosis or necrosis of the parasites but, instead, seems to be mediated through a pathway involving autophagy, with a clear detection of autophagic vacuoles in the cytoplasm by using both a fluorescent marker and TEM. As for the in vivo studies, compound 5 showed activity in a mouse model of VL at 20mg/kg, reducing the parasite load in both spleen and liver (59.80% and 26.88%, respectively). Finally, this compound did not induce hepatoxicity or nephrotoxicity and was able to normalize the altered biochemical parameters in the infected mice. Thus, our findings support the use of 1,2,3-triazolium salts as potential agents against visceral leishmaniasis.

Novel Nanocarrier Platform for Effective Treatment of Visceral Leishmaniasis.

Leishmaniasis is among the five parasitic diseases that still require the development of new drugs. Ultrasmall cerium (Ce3/4+) cation-doped maghemite (γ-Fe2O3) nanoparticles (NPs) were tested as a potential drug to treat visceral leishmaniasis, a disease affecting millions of people worldwide. The NPs were engineered for binding a polycationic branched polyethylenimine (PEI) polymer, thereby rupturing the single lysosome of these parasites and enabling entry of the anti-Leishmania drug, pentamidine. Exploiting the known lanthanide cation/complex-based coordinative chemical reactivity enabled the binding of both active agents onto the surface of the NPs. To optimize the fabrication of the cytotoxic NPs, optimization via a DoE (Design of Experiments) process was used to identify the optimal NP with toxicity against the two stages of the parasite, promastigotes, which propagate in the insect, and amastigotes, which infect the mammalian host. The screen identified a single optimized NP (DoE Opt) that was further examined in a mouse model of visceral leishmaniasis. Intravenous injection of the NPs had no adverse effects on the cellular composition or biochemical parameters of the blood, demonstrating no signs of systemic toxicity. The optimized NP was able to eradicate visceral disease caused by Leishmania donovani infection. The study demonstrates the versatile ability of the cerium-doped NPs to bind at least two cytotoxic ligands. This approach could be used for optimizing the binding of different drugs for the treatment of other diseases, including cancer. Since resistance to treatment with nanocarriers was not reported to date, such an approach could potentially overcome drug resistance that emerges when using soluble small molecule drugs.

Elucidation of role of an acetyltransferase like protein in paromomycin resistance in Leishmania donovani using in silico and in vitro approaches

Paromomycin, an aminoglycoside antibiotic, is an effective treatment for VL (visceral leishmaniasis) in India. The modification of aminoglycoside antibiotics by enzymes such as aminoglycoside acetyltransferases is the predominant mechanism of resistance to antibiotics in bacterial system. In the present study, we identified and characterized LdATLP (an acetyltransferase-like protein) and elucidated its role in paromomycin resistance in Leishmania donovani. Gene encoding LdATLP was consistently up-regulated (>2fold) in three distinct paromomycin resistant in comparison with sensitive parasites, although the gene sequence was identical in the two. In silico analysis revealed that LdATLP consisted of conserved GNAT (GCN5-related N-Acetyltransferase) domain which is characteristic of aminoglycoside N-acetyltransferases. Evolutionary relationship among LdATLP of Leishmania and aminoglycoside acetyltransferases of bacteria was established by phylogenetic analysis. The 3D structure of LdATLP, predicted by ab-initio modeling, constituted 6 α-helices and 6 β-sheets. A few residues, such as R175, R177, E196, R197, V198, V200, K202, R205, C206, D208, G210, R211, R215, A234, S237, S238, K239, D240, F241 and Y242 of GNAT domain were predicted to be present at active site. Molecular docking of LdATLP with paromomycin or indolicidin (broad spectrum inhibitor of aminoglycoside modifying enzymes), followed by molecular dynamics simulation of docked complex suggested that both paromomycin and indolicidin bind to LdATLP with comparable free energy of binding. In vitro studies revealed that in the presence of indolicidin, paromomycin resistant parasites exhibited reversion of phenotype into sensitive parasites with marked increase in paromomycin susceptibility, suggesting the role of LdATLP in paromomycin resistance.Communicated by Ramaswamy H. Sarma

Options for Effective Treatment of Visceral Leishmaniasis

Visceral Leishmaniasis (VL), also known as kala-azar, is caused by several species of Leishmania, a protozoan parasite (Leishmania donovani) transmitted to humans by the bite of infected phelobotomine argentipes sandflies. VL is a disease of poverty, affecting the poorest of the poor. It is a major cause of morbidity and mortality in some areas (localized). If the infection is left untreated, the patient dies in about 2 years. Several drugs are now available for the treatment of VL. However, some of them are very costly (miltefosine, lipid amphotericin B). Sodium stibogluconate is an effective drug and the backbone of VL treatment for about six decades. Unfortunately, parasites developed resistance against the drug. In some areas in India, for example in North Bihar, approximately 60% of isolates are resistant to this treatment. In addition, the compound exhibits high cardio-toxity, which is an important limiting factor for its use. Based on the new data, which became available, the WHO/SEARO Regional Technical Advisory Group (RTAG) especially constituted for the kala-azar elimination program undertaken by India, Nepal, and Bangladesh in 2005, recommended that miltefosine should be used as the first line drug. However, the RTAG at its meeting in Dhaka (Bangladesh) in 2009 modified the above recommendation and advised that miltefosine should be phased out and replaced by lipid amphotericin B. The decision to switch over to lipid amphotericin B could have been delayed, because the program had already made substantial progress using miltefosine. In view of drug resistance, low compliance, availability and cost, it is imperative that serious efforts should be made to develop new drugs, preferably oral, for the treatment of VL and PKDL.

Overexpressed Macrophage Mannose Receptor Targeted Nanocapsules- Mediated Cargo Delivery Approach for Eradication of Resident Parasite: In Vitro and In Vivo Studies.

Since, Leishmania protozoans are obligate intracellular parasites of macrophages, an immunopotentiating macrophage-specific Amphotericin B (AB) delivery system would be ideally appropriate to increase its superiority for leishmaniasis treatment and to eliminate undesirable toxicity. Herein, we report AB entrapped mannose grafted chitosan nanocapsules (MnosCNc-AB) that results in effective treatment of visceral leishmaniasis, while also enhancing L. donovani specific T-cell immune responses in infected host. MnosCNc-AB were prepared via synthesized mannosylated chitosan deposition on interface of oil/water nanoemulsion intermediate and were characterized. J774A.1 macrophage uptake potential, antileishmanial activity and immunomodulatory profile were evaluated in hamster. Tissue localization, biodistribution and toxicity profile were also investigated. MnosCNc-AB had nanometric size (197.8 ± 8.84nm), unimodal distribution (0.115 ± 0.04), positive zeta potential (+31.7 ± 1.03mV) and 97.5 ± 1.13% cargo encapsulation efficiency. Superior macrophage internalization of mannosylated chitosan nanocapsules compared to unmodified chitosan nanocapsules was observed by fluorescence-based assessment, further confirmed by rapid blood clearance and, greater localization and higher accumulation in macrophage rich liver and spleen. While, MnosCNc-AB mediated cargo distribution to kidney decreased. Augmented in vitro antileishmanial activity and in vivo pro-inflammatory mediator's expression were observed with MnosCNc-AB, led to significant reduction (∼90%) in splenic parasite burden. Results demonstrated that mannose ligand grafted chitosan nanocapsules could improve selective delivery of AB into macrophages via interactions with overexpressed mannose receptors thus reduce undesirable toxicity. Study provides evidence for MnosCNc-AB potential to leishmaniasis therapeutics and presents valuable therapeutic strategies for combating chronic macrophage-resident microbial infections.

Repurposing miltefosine for the treatment of immune-mediated disease?

Miltefosine is an ether lipid that was initially developed for cancer treatment in the early 1980s. Miltefosine largely failed development for oncology, although it was approved for the topical treatment of breast cancer metastasis. It was subsequently discovered that miltefosine is a highly effective treatment of visceral Leishmaniasis, a parasitic disease that affects millions worldwide and causes an estimated 30,000 fatalities each year. Oral treatment with miltefosine is generally well tolerated and has relatively few adverse effects. The exact mechanism of action of miltefosine treatment is still under investigation. Its close resemblance to phospholipids allows it to be quickly taken up by cell membranes and affect related processes, such as lipid metabolism and signaling through lipid rafts. These processes play an important role in the immune response and it comes as no surprise that miltefosine has been successfully tested for the treatment of a number of immune-mediated diseases in preclinical models of disease. Drug repurposing of miltefosine for immune-mediated diseases may provide an opportunity to expand the limited number of drugs that are currently available for therapeutic use.

In vitro evaluation of surface functionalized gelatin nanoparticles for macrophage targeting in the therapy of visceral leishmaniasis

The present study evaluates the potential of surface functionalized gelatin nanoparticles (f-GNPs) for efficient macrophage-specific delivery of amphotericin B (AmB) in the treatment of visceral leishmaniasis (VL). Further, the effect of spacer for macrophage targeting was also evaluated. Gelatin was functionalized either through conjugation to mannose via direct coupling (mGelatin) or via PEG spacer (m-Gelatin), and the synthesis was confirmed by FTIR. AmB-loaded f-GNPs, that is, mGNPs and m-GNPs prepared from mGelatin and m-Gelatin conjugates, respectively, were characterized. In vitro concanavalin A (Con-A) agglutination assay confirmed the availability of mannose on the surface of these f-GNPs. Kinetics of cellular uptake of AmB-loaded f-GNPs by J774A.1 macrophage cells assessed through flow cytometry demonstrated a steady increase and maximum cell-associated fluorescence was observed at 4h for m-GNPs and 6 h for m-GNPs. Measurement of cytotoxicity using Annexin-V–FITC/PI apoptosis assay delineated marginal changes (7–9%) in treated macrophages following 48 h incubation, establishing the safety of f-GNPs. m-GNPs showed a 5.4-fold reduction in IC50 in comparison with plain AmB suggesting significant enhancement of antileishmanial activity. Our results indicate that f-GNPs could be a promising carrier for specific delivery of AmB to macrophages for effective treatment of VL. Furthermore, spacer contributed significantly in reducing the cytotoxicity as well as increasing the uptake and activity of f-GNPs.

Aid Workers Face More Complex Hurdles

tious Disease Research Institute in Seattle, Wash, worked with the Corixa Corporation, now GlaxoSmithKline, to develop the first candidate vaccine for leishmaniasis, which sickens about 2 million a year, including 500 000 who contract the potentially fatal visceral form. Phase 1 clinical trials have been completed in Peru and Brazil; additional trials are under way in India, Sudan, and Venezuela. TheDNDI is anotherexampleof such partnerships.WithinternationalpharmaceuticalmakerSanofi-AventisandtheBraziliangovernment instituteFarmanguinhos, now Fiocruz, the DNDI in the last 2 years has ushered in 2 new artesunate combination treatments for malaria. With field support from MSF, the DNDI also supported clinical trials on the eflornithine-nifurtimox combination for sleeping sickness. Pecoul said the DNDI is beginning a phase 1 clinical trial of the antifungal fexinidazole, an oral treatment. “We need to have a very simple treatment to change the dynamic of control of sleeping sickness,” he noted. In addition, the DNDI is working on development of a pediatric formulation of benznidazole for Chagas disease and ways to combine existing medications for more effective treatment of visceral leishmaniasis. “The next step for us is to continue to strengthen the portfolio and make progress,” said Pecoul.

Liposomal amphotericin B colloidal dispersion is an effective treatment for visceral leishmaniasis,

Liposomal amphotericin B colloidal dispersion is an effective treatment for visceral leishmaniasis,

Amphotericin-B colloidal dispersion. A review of its use against systemic fungal infections and visceral leishmaniasis.

Formulation of amphotericin B with sodium cholesteryl sulphate alters the pharmacokinetic properties of the drug, particularly reducing its distribution to the kidneys. The antifungal activity in vitro of amphotericin B colloidal dispersion (ABCD) is similar to that of conventional amphotericin B (C-AmB) against true pathogenic organisms including Blastomyces, Coccidioides, Histoplasma and Paracoccidioides species and the opportunistic organisms such as Candida and Cryptococcus species. In animal models, ABCD was generally less effective than an identical dose of C-AmB, but overall was more effective because of its improved therapeutic index. Although ABCD appeared to be more effective than C-AmB in resolving infection and improving survival in patients with proven or probable invasive aspergillosis, the retrospective design of the study and the greater prevalence of neutropenia in patients treated with the conventional formulation necessitate cautious interpretation of the results. ABCD has been effective and seldom caused nephrotoxicity in patients with fungal infection who had previously failed to adequately respond or had developed renal toxicity with C-AmB. Similarly, ABCD was effective in patients with proven or suspected fungal infection after bone marrow transplantation. Preliminary results from a pilot study comparing ABCD and C-AmB in patients with neutropenia and persistent fever reported similar response rates with both formulations. ABCD is an effective treatment for visceral leishmaniasis in immunocompetent patients. In 1 study, about 12% of ABCD recipients discontinued the drug because of adverse events; infusion-related events were the most common cause of discontinuation. The renal tolerability of ABCD is better than that of C-AmB. ABCD appears to be an effective alternative to conventional amphotericin B in patients with invasive aspergillosis or visceral leishmaniasis and in those with proven or suspected systemic fungal infection who are intolerant of the conventional formulation or have pre-existing renal impairment. Preliminary data also suggest that ABCD is an alternative to C-AmB when used empirically in patients with neutropenia and fever. Nevertheless, the efficacy of ABCD compared with that of the conventional formulation has yet to be adequately demonstrated and the role of ABCD relative to that of liposomal and other lipid-based formulations has not been determined. ABCD, like other lipid-based and liposomal formulations of amphotericin B, has been designed to deliver the active drug to the target site, while reducing renal toxicity. The aim of increasing the therapeutic index compared with C-AmB has been achieved.

Activity of liposomal amphotericin B against experimental cutaneous leishmaniasis.

The polyene antibiotic amphotericin B is currently a second-line treatment for visceral leishmaniasis (VL) and mucocutaneous leishmaniasis. Lipid-amphotericin B formulations with lower toxicity than the parent drug that were developed for the treatment of systemic mycoses have proved to be an effective treatment for VL, especially AmBisome, a small unilamellar negatively charged liposome. In vitro, free amphotericin B was three to six times more active than the liposomal formulation AmBisome against both Leishmania major promastigotes in culture and amastigotes in murine macrophages. In a BALB/c L. major model of cutaneous infection, liposomal amphotericin B administered once a day on six alternate days by the intravenous route produced a dose-response effect between 6.25 and 50 mg/kg. Liposomal amphotericin B administered subcutaneously close to a lesion had no significant activity. Free drug was ineffective at nontoxic doses. The results suggest that liposomal amphotericin B may be useful in the treatment of cutaneous leishmaniasis.