Exploiting Leishmania-Primed Dendritic Cells as Potential Immunomodulators of Canine Immune Response.

Dendritic cells (DCs) capture pathogens and process antigens, playing a crucial role in activating naïve T cells, bridging the gap between innate and acquired immunity. However, little is known about DC activation when facing Leishmania parasites. Thus, this study investigates in vitro activity of canine peripheral blood-derived DCs (moDCs) exposed to L. infantum and L. amazonensis parasites and their extracellular vesicles (EVs). L. infantum increased toll-like receptor 4 gene expression in synergy with nuclear factor κB activation and the generation of pro-inflammatory cytokines. This parasite also induced the expression of class II molecules of major histocompatibility complex (MHC) and upregulated co-stimulatory molecule CD86, which, together with the release of chemokine CXCL16, can attract and help in T lymphocyte activation. In contrast, L. amazonensis induced moDCs to generate a mix of pro- and anti-inflammatory cytokines, indicating that this parasite can establish a different immune relationship with DCs. EVs promoted moDCs to express class I MHC associated with the upregulation of co-stimulatory molecules and the release of CXCL16, suggesting that EVs can modulate moDCs to attract cytotoxic CD8+ T cells. Thus, these parasites and their EVs can shape DC activation. A detailed understanding of DC activation may open new avenues for the development of advanced leishmaniasis control strategies.

In vitro Evaluation of the Antileishmanial and Antischistosomal Activities of p-Coumaric Acid Prenylated Derivatives.

We have evaluated eight p-coumaric acid prenylated derivatives in vitro for their antileishmanial activity against Leishmania amazonensis promastigotes and their antischistosomal activity against Schistosoma mansoni adult worms. Compound 7 ((E)-3,4-diprenyl-4-isoprenyloxycinnamic alcohol) was the most active against L. amazonensis (IC50=45.92 µM) and S. mansoni (IC50=64.25 µM). Data indicated that the number of prenyl groups, the presence of hydroxyl at C9, and a single bond between C7 and C8 are important structural features for the antileishmanial activity of p-coumaric acid prenylated derivatives.

Treatment using vanillin-derived synthetic molecules incorporated into polymeric micelles is effective against infection caused by Leishmania amazonensis species.

Treatment against leishmaniasis presents problems, mainly due to the toxicity of the drugs, high cost, and the emergence of resistant strains. A previous study showed that two vanillin-derived synthetic molecules, 3s [4-(2-hydroxy-3-(4-octyl-1H-1,2,3-triazol-1-yl)propoxy)-3-methoxybenzaldehyde] and 3t [4-(3-(4-decyl-1H-1,2,3-triazol-1-yl)-2-hydroxypropoxy)-3-methoxybenzaldehyde], presented antileishmanial activity against Leishmania infantum, L. amazonensis, and L. braziliensis species. In the present work, 3s and 3t were evaluated to treat L. amazonensis-infected mice. Molecules were used pure or incorporated into Poloxamer 407-based micelles. In addition, amphotericin B (AmpB) and its liposomal formulation, Ambisome®, were used as control. Animals received the treatment and, one and 30 days after, they were euthanized to evaluate immunological, parasitological, and biochemical parameters. Results showed that the micellar compositions (3s/Mic and 3t/Mic) induced significant reductions in the lesion mean diameter and parasite load in the infected tissue and distinct organs, as well as a specific and significant antileishmanial Th1-type immune response, which was based on significantly higher levels of IFN-γ, IL-12, nitrite, and IgG2a isotype antibodies. Drug controls showed also antileishmanial action; although 3s/Mic and 3t/Mic have presented better and more significant parasitological and immunological data, which were based on significantly higher IFN-γ production and lower parasite burden in treated animals. In addition, significantly lower levels of urea, creatinine, alanine transaminase, and aspartate transaminase were found in mice treated with 3s/Mic and 3t/Mic, when compared to the others. In conclusion, results suggest that 3s/Mic and 3t/Mic could be considered as therapeutic candidates to treat against L. amazonensis infection.

Quinine and chloroquine: Potential preclinical candidates for the treatment of tegumentary Leishmaniasis.

Leishmaniasis is an endemic disease in more than 90 countries, constituting a relevant public health problem. Limited treatment options, increase in resistance, and therapeutic failure are important aspects for the discovery of new treatment options. Drug repurposing may accelerate the discovery of antiLeishmanial drugs. Recent tests indicating the in vitro potential of antimalarials Leishmania resulted in the design of this study. This study aimed at evaluating the susceptibility of Leishmania (L.) amazonensis to chloroquine (CQ) and quinine (QN), alone or in combination with amphotericin B (AFT) and pentamidine (PTN). In the in vitro tests, first, we evaluated the growth inhibition of 50 % of promastigotes (IC50) and cytotoxicity for HepG2 and THP-1 cells (CC50). The IC50 values of AFT and PNT were below 1 µM, while the IC50 values of CQ and QN ranged between 4 and 13 µM. Concerning cytotoxicity, CC50 values ranged between 7 and 30 µM for AFT and PNT, and between 22 and 157 µM for the antimalarials. We also calculated the Selectivity Index (SI), where AFT and PTN obtained the highest values, while the antimalarias obtained values between 5 and 12. Both antimalarials were additive (Æ©FIC 1.05-1.8) in combination with AFT and PTN. For anti-amastigote activity, the drugs obtained the following ICA50 values: AFT (0.26 µM), PNT (2.09 µM), CQ (3.77 µM) and QN (24.5 µM). In the in vivo tests, we observed that the effective dose for the death of 50 % of parasites (ED50) of AFT and CQ were 0.63 mg/kg and 27.29 mg/kg, respectively. When combining CQ with AFT, a decrease in parasitemia was observed, being statistically equal to the naive group. For cytokine quantification, it was observed that CQ, despite presenting anti-inflammatory activity was effective at increasing the production of IFN-γ. Overall, our data indicate that chloroquine will probably be a candidate for repurposing and use in drug combination therapy.

Annexin A1 improves immune responses and control of tissue parasitism during Leishmania amazonensis infection in BALB/c mice.

Leishmaniases, a group of diseases caused by the species of the protozoan parasite Leishmania, remains a significant public health concern worldwide. Host immune responses play a crucial role in the outcome of Leishmania infections, and several mediators that regulate inflammatory responses are potential targets for therapeutic approaches. Annexin A1 (AnxA1), an endogenous protein endowed with anti-inflammatory and pro-resolving properties, has emerged as a potential player. We have shown that during L. braziliensis infection, deficiency of AnxA1 exacerbates inflammatory responses but does not affect parasite burden. Here, we have investigated the role of AnxA1 in L. amazonensis infection, given the non-healing and progressive lesions characteristic of this infectious model. Infection of AnxA1 KO BALB/c mice resulted in increased lesion size and tissue damage associated with higher parasite burdens and enhanced inflammatory response. Notably, therapeutic application of the AnxA1 peptidomimetic Ac2-26 improves control of parasite replication and increases IL-10 production in vivo and in vitro, in both WT and AnxA1 KO mice. Conversely, administration of WRW4, an inhibitor of FPR2/3, resulted in larger lesions and decreased production of IL-10, suggesting that the effects of AnxA1 during L. amazonensis infection are associated with the engagement of these receptors. Our study illuminates the role of AnxA1 in L. amazonensis infection, demonstrating its impact on the susceptibility phenotype of BALB/c mice. Furthermore, our results indicate that targeting the AnxA1 pathway by using the Ac2-26 peptide could represent a promising alternative for new treatments for leishmaniasis.

Leishmanicidal and immunomodulatory activity of Terminalia catappa in Leishmania amazonensisin vitro infection.

Leishmaniases are infectious-parasitic diseases that impact public health around the world. Antileishmanial drugs presented toxicity and increase in parasitic resistance. Studies with natural products show an alternative to this effect, and several metabolites have demonstrated potential in the treatment of various diseases. Terminalia catappa is a plant species with promising pharmaceutical properties. The objective of this work was to evaluate the therapeutic potential of extracts and fractions of T. catappa on Leishmania amazonensis and investigate the immunomodulatory mechanisms associated with its action. In anti-Leishmania assays, the ethyl acetate fraction exhibited activity against promastigotes (IC50 86.07 ± 1.09 µg/mL) and low cytotoxicity (CC50 517.70 ± 1.68 µg/mL). The ethyl acetate fraction also inhibited the intracellular parasite (IC50 25.74 ± 1.08 µg/mL) with a selectivity index of 20.11. Treatment with T. catappa ethyl acetate fraction did not alter nitrite production by peritoneal macrophages stimulated with L. amazonensis, although there was a decrease in unstimulated macrophages treated at 50 µg/mL (p = 0.0048). The T. catappa ethyl acetate fraction at 100 µg/mL increased TNF-α levels (p = 0.0238) and downregulated HO-1 (p = 0.0030) and ferritin (p = 0.0002) gene expression in L. amazonensis-stimulated macrophages. Additionally, the total flavonoid and ellagic acid content for ethyl acetate fraction was 13.41 ± 1.86 mg QE/g and 79.25 mg/g, respectively. In conclusion, the T. catappa ethyl acetate fraction showed leishmanicidal activity against different forms of L. amazonensis and displayed immunomodulatory mechanisms, including TNF-α production and expression of pro and antioxidant genes.

Efficacy of the treatment using a microemulsion loaded with epoxy-α-lapachone in combination with meglumine antimoniate against murine infection by Leishmania (Leishmania) amazonensis.

Leishmaniasis is a disease caused by Leishmania spp., affecting millions of people around the world. For decades, its treatment has been based on pentavalent antimonials, which notoriously cause toxic side effects in patients. In this study, epoxy-α-lapachone incorporated into an oil-in-water-type microemulsion (ELAP-ME) and meglumine antimoniate (MA) were assayed in monotherapy and in combination (ELAP-ME/MA) in BALB/c mice infected with Leishmania (Leishmania) amazonensis. In general, there was a reduction in paw lesion size (up to 37% reduction) and decreases of parasite loads in the footpad (∼40%) and lymph nodes (∼31%) of animals treated with ELAP-ME/MA, when compared to the non-treated control groups. Analyses of serum biochemical parameters revealed that the ELAP-ME/MA showed lower renal and hepatic toxicity when compared to MA 2-doses/week monotherapy. These findings indicate that the ELAP-ME/MA combination may be a promising approach for the treatment of cutaneous leishmaniasis.

Intranasal delivery of LaAg vaccine improves immunity of aged mice against visceral Leishmaniasis.

There are no approved vaccines yet for human visceral leishmaniasis (VL), the most severe form of the leishmaniasis clinical manifestations that is fatal in over 95 % of untreated cases. It is well-accepted that immunological changes during aging have deleterious impact on the efficacy of vaccines and response to infections. In this work, we compared the response of young and aged mice to intranasal vaccination with killed Leishmania amazonensis promastigote antigens (LaAg) that were then challenged with L. infantum infection, a species that causes visceral leishmaniasis. Intranasal vaccination with LaAg induced a similar reduction in parasitism and hepatosplenomegaly in both young and aged mice compared to their unvaccinated counterparts. Following infection, there was also a less prominent inflammatory profile particularly in the vaccinated aged group, with lower production of TNF-α and nitrite compared to the respective unvaccinated group. Interestingly, the LaAg intranasal vaccination promoted increased production of IFN-γ that was observed in both young- and aged vaccinated groups. Additionally, CD4+ and CD8+T cells from both vaccinated groups presented decreased expression of the inhibitory receptors PD-1 and KLRG1 compared to their unvaccinated controls. Interestingly, a strong positive correlation was observed between the expression of both inhibitory receptors PD-1 and KLRG1 and parasitism, which was more conspicuous in the unvaccinated-aged mice than in the others. Overall, this study helps define new strategies to improve vaccine effectiveness and provides a perspective for prophylactic alternatives against leishmaniasis.

Diagnosis of Cutaneous Leishmaniasis Using FTIR Spectroscopy and Machine Learning: An Animal Model Study.

Cutaneous leishmaniasis (CL) is a polymorphic and spectral skin disease caused by Leishmania spp. protozoan parasites. CL is difficult to diagnose because conventional methods are time-consuming, expensive, and low-sensitive. Fourier transform infrared spectroscopy (FTIR) with machine learning (ML) algorithms has been explored as an alternative to achieve fast and accurate results for many disease diagnoses. Besides the high accuracy demonstrated in numerous studies, the spectral variations between infected and noninfected groups are too subtle to be noticed. Since variability in sample set characteristics (such as sex, age, and diet) often leads to significant data variance and limits the comprehensive understanding of spectral characteristics and immune responses, we investigate a novel methodology for diagnosing CL in an animal model study. Blood serum, skin lesions, and draining popliteal lymph node samples were collected from Leishmania (Leishmania) amazonensis-infected BALB/C mice under experimental conditions. The FTIR method and ML algorithms accurately differentiated between infected (CL group) and noninfected (control group) samples. The best overall accuracy (∼72%) was obtained in an external validation test using principal component analysis and support vector machine algorithms in the 1800-700 cm-1 range for blood serum samples. The accuracy achieved in analyzing skin lesions and popliteal lymph node samples was satisfactory; however, notable disparities emerged in the validation tests compared to results obtained from blood samples. This discrepancy is likely attributed to the elevated sample variability resulting from molecular compositional differences. According to the findings, the successful functioning of prediction models is mainly related to data analysis rather than the differences in the molecular composition of the samples.

Synthesis and evaluation of hybrid sulfonamide-chalcones with potential antileishmanial activity.

Leishmaniasis is an emerging tropical infectious disease caused by a protozoan parasite of the genus Leishmania. In this work, the molecular hybridization between a trimethoxy chalcone and a sulfonamide group was used to generate a series of sulfonamide-chalcones. A series of eight sulfonamide-chalcone hybrids were made with good yields (up to 95%). These sulfonamide-chalcones were tested against promastigotes of Leishmania amazonensis and cytotoxicity against mouse macrophages, which showed good antileishmanial activity with IC50 = 1.72-3.19 µM. Three of them (10c, 10g, and 10h) were also highly active against intracellular amastigotes and had a good selectivity index (SI > 9). Thus, those three compounds were docked in the cytosolic tryparedoxin peroxidase (cTXNPx) enzyme of the parasite, and molecular dynamics simulations were carried out. This enzyme was selected as a target protein for the sulfonamide-chalcones due to the fact of the anterior report, which identified a strong and stable interaction between the chalcone NAT22 (6) and the cTXNPx. In addition, a prediction of the drug-likeness, and the pharmacokinetic profile of all compounds were made, demonstrating a good profile of those chalcones.

In Vitro and In Vivo Antileishmanial Activity of Thioridazine.

INTRODUCTION: Leishmaniasis is a neglected disease with high prevalence and incidence in tropical and subtropical areas. Existing drugs are limited due to cost, toxicity, declining efficacy and unavailability in endemic places. Drug repurposing has established as an efficient way for the discovery of drugs for a variety of diseases. PURPOSE: The objective of the present work was testing the antileishmanial activity of thioridazine, an antipsychotic agent with demonstrated effect against other intracellular pathogens. METHODS: The cytotoxicity for mouse peritoneal macrophages as well as the activity against Leishmania amazonensis, Leishmania mexicana and Leishmania major promastigotes and intracellular amastigotes, as well as in a mouse model of cutaneous leishmaniasis, were assessed. RESULTS: Thioridazine inhibited the in vitro proliferation of promastigotes (50% inhibitory concentration-IC50-values in the range of 0.73 µM to 3.8 µM against L. amazonensis, L. mexicana and L. major) and intracellular amastigotes (IC50 values of 1.27 µM to 4.4 µM for the same species). In contrast, in mouse peritoneal macrophages, the 50% cytotoxic concentration was 24.0 ± 1.89 µM. Thioridazine inhibited the growth of cutaneous lesions and reduced the number of parasites in the infected tissue of mice. The dose of thioridazine that inhibited lesion development by 50% compared to controls was 23.3 ± 3.1 mg/kg and in terms of parasite load, it was 11.1 ± 0.97 mg/kg. CONCLUSIONS: Thioridazine was effective against the promastigote and intracellular amastigote stages of three Leishmania species and in a mouse model of cutaneous leishmaniasis, supporting the potential repurposing of this drug as an antileishmanial agent.

In Vitro Leishmanicidal Activity of Copaiba Oil and Kojic Acid Combination on the Protozoan Leishmania (Leishmania) amazonensis and Host Cell.

(1) Background: Leishmaniasis refers to a group of anthropozoonotic diseases caused by Leishmania. The major chemotherapeutic agent used for its treatment is Glucantime®®, but the search continues for new compounds that are economically viable and act on the protozoan without causing damage to the host cell. As an alternative approach, this study used a combination of copaiba oil (CO) and kojic acid (KA) to determine their in vitro action on host cells, on the Leishmania (Leishmania) amazonensis protozoan and its interaction with macrophages. (2) Methods: In vitro culture, analysis of cytokine release and microscopy assays were performed. Statistical analysis was performed with ANOVA (GraphPad Prism). (3) Results: The combination did not induce cytotoxic effects on macrophages after treatment but promoted morphological changes in the protozoan, such as nuclear alterations (apoptotic characteristics), alterations in the cellular body and an increase in the number of electrodense structures and acidocalcisomes, observed mainly at the concentrations of CO20KA50 and CO30KA50 µg/mL. We observed reductions in the intracellular amastigote number and in the production of proinflammatory cytokines, such as IL-6 and TNF-α, after treatment with CO30KA at 50 µg/mL. (4) Conclusions: We report here, for the first time, that the combination of CO and KA may be a promising approach against Leishmania (Leishmania) amazonensis.

Extracellular Vesicles Released by Leishmania (Leishmania) amazonensis Promastigotes with Distinct Virulence Profile Differently Modulate the Macrophage Functions.

Leishmania spp. is the aetiologic agent of leishmaniasis, a disease endemic in several developing countries. The parasite expresses and secretes several virulence factors that subvert the macrophage function and immune response. Extracellular vesicles (EVs) can carry molecules of the parasites that show immunomodulatory effects on macrophage activation and disease progression. In the present work, we detected a significantly higher expression of lpg3 and gp63 genes in Leishmania amazonensis promastigotes recovered after successive experimental infections (IVD-P) compared to those cultured for a long period (LT-P). In addition, we observed a significantly higher percentage of infection and internalized parasites in groups of macrophages infected with IVD-P. Macrophages previously treated with EVs from LT-P showed higher percentages of infection and production of inflammatory cytokines after the parasite challenge compared to the untreated ones. However, macrophages infected with parasites and treated with EVs did not reduce the parasite load. In addition, no synergistic effects were observed in the infected macrophages treated with EVs and reference drugs. In conclusion, parasites cultured for a long period in vitro and recovered from animals' infections, differently affected the macrophage response. Furthermore, EVs produced by these parasites affected the macrophage response in the early infection of these cells.

Leishmanial activity of Brazilian brown propolis and its diterpenes.

Propolis is a natural product widely used in folk medicine. Among its various applications, its antiparasitic properties stand out. Due to its great biodiversity, Brazil is a major producer of several types of propolis. This study proposes to evaluate the leishmanicidal properties of the hydroalcoholic extract of propolis collected in the southern region of Brazil (Brown propolis - HEBP) and its main isolated compounds: abietic acid (1), 13-epi-cupressic acid (2), 13-epi-torulosol (3), dehydroabietic acid (4), cis-communic acid (5) and ent-agatic acid (6). In general, the diterpenes did not show activity against the promastigotes of Leishmania (Leishmania) amazonensis at the evaluated concentrations. However, the HEBP was very active with an inhibition concentration of 50% at 8.32 µg/mL. Moreover, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) assays showed morphological and structural alterations in promastigote forms of L. (L.) amazonensis when incubated with HEBP.

Green SPIONs as a novel highly selective treatment for leishmaniasis: an in vitro study against Leishmania amazonensis intracellular amastigotes.

The main goal of this work was to evaluate the therapeutic potential of green superparamagnetic iron oxide nanoparticles (SPIONs) produced with coconut water for treating cutaneous leishmaniasis caused by Leishmania amazonensis. Optical and electron microscopy techniques were used to evaluate the effects on cell proliferation, infectivity percentage, and ultrastructure. SPIONs were internalized by both parasite stages, randomly distributed in the cytosol and located mainly in membrane-bound compartments. The selectivity index for intracellular amastigotes was more than 240 times higher compared to current drugs used to treat the disease. The synthesized SPIONs showed promising activity against Leishmania and can be considered a strong candidate for a new therapeutic approach for treating leishmaniases.

(-)-5-Demethoxygrandisin B a New Lignan from Virola surinamensis (Rol.) Warb. Leaves: Evaluation of the Leishmanicidal Activity by In Vitro and In Silico Approaches.

Leishmaniasis is a complex disease caused by infection with different Leishmania parasites. The number of medications used for its treatment is still limited and the discovery of new drugs is a valuable approach. In this context, here we describe the in vitro leishmanicidal activity and the in silico interaction between trypanothione reductase (TryR) and (-)-5-demethoxygrandisin B from the leaves of Virola surinamensis (Rol.) Warb. The compound (-)-5-demethoxygrandisin B was isolated from V. surinamensis leaves, a plant found in the Brazilian Amazon, and it was characterized as (7R,8S,7'R,8'S)-3,4,5,3',4'-pentamethoxy-7,7'-epoxylignan. In vitro antileishmanial activity was examined against Leishmania amazonensis, covering both promastigote and intracellular amastigote phases. Cytotoxicity and nitrite production were gauged using BALB/c peritoneal macrophages. Moreover, transmission electron microscopy was applied to probe ultrastructural alterations, and flow cytometry assessed the shifts in the mitochondrial membrane potential. In silico methods such as molecular docking and molecular dynamics assessed the interaction between the most stable configuration of (-)-5-demethoxygrandisin B and TryR from L. infantum (PDB ID 2JK6). As a result, the (-)-5-demethoxygrandisin B was active against promastigote (IC50 7.0 µM) and intracellular amastigote (IC50 26.04 µM) forms of L. amazonensis, with acceptable selectivity indexes. (-)-5-demethoxygrandisin B caused ultrastructural changes in promastigotes, including mitochondrial swelling, altered kDNA patterns, vacuoles, vesicular structures, autophagosomes, and enlarged flagellar pockets. It reduced the mitochondria membrane potential and formed bonds with important residues in the TryR enzyme. The molecular dynamics simulations showed stability and favorable interaction with TryR. The compound targets L. amazonensis mitochondria via TryR enzyme inhibition.

Silver(I) and Copper(II) 1,10-Phenanthroline-5,6-dione Complexes as Promising Antivirulence Strategy against Leishmania: Focus on Gp63 (Leishmanolysin).

Leishmaniasis, caused by protozoa of the genus Leishmania, encompasses a group of neglected diseases with diverse clinical and epidemiological manifestations that can be fatal if not adequately and promptly managed/treated. The current chemotherapy options for this disease are expensive, require invasive administration and often lead to severe side effects. In this regard, our research group has previously reported the potent anti-Leishmania activity of two coordination compounds (complexes) derived from 1,10-phenanthroline-5,6-dione (phendione): [Cu(phendione)3].(ClO4)2.4H2O and [Ag(phendione)2].ClO4. The present study aimed to evaluate the effects of these complexes on leishmanolysin (gp63), a virulence factor produced by all Leishmania species that plays multiple functions and is recognized as a potential target for antiparasitic drugs. The results showed that both Ag-phendione (-74.82 kcal/mol) and Cu-phendione (-68.16 kcal/mol) were capable of interacting with the amino acids comprising the active site of the gp63 protein, exhibiting more favorable interaction energies compared to phendione alone (-39.75 kcal/mol) or 1,10-phenanthroline (-45.83 kcal/mol; a classical gp63 inhibitor) as judged by molecular docking assay. The analysis of kinetic parameters using the fluorogenic substrate Z-Phe-Arg-AMC indicated Vmax and apparent Km values of 0.064 µM/s and 14.18 µM, respectively, for the released gp63. The effects of both complexes on gp63 proteolytic activity were consistent with the in silico assay, where Ag-phendione exhibited the highest gp63 inhibition capacity against gp63, with an IC50 value of 2.16 µM and the lowest inhibitory constant value (Ki = 5.13 µM), followed by Cu-phendione (IC50 = 163 µM and Ki = 27.05 µM). Notably, pretreatment of live L. amazonensis promastigotes with the complexes resulted in a significant reduction in the expression of gp63 protein, including the isoforms located on the parasite cell surface. Both complexes markedly decreased the in vitro association indexes between L. amazonensis promastigotes and THP-1 human macrophages; however, this effect was reversed by the addition of soluble gp63 molecules to the interaction medium. Collectively, our findings highlight the potential use of these potent complexes in antivirulence therapy against Leishmania, offering new insights for the development of effective treatments for leishmaniasis.

The Extraordinary Case of a Woman with a 30-Year-Long Diffuse Leishmaniasis Cured with One Single Ampoule of Intranasal Pentavalent Antimoniate.

Infection with Leishmania amazonensis and L. mexicana may lead to diffuse cutaneous leishmaniasis. The cure is exceptional, especially for the strange case of this lady. Case report: The patient acquired the disease in childhood and remained with lesions for over 30 years, albeit several treatments. She worsened after a pregnancy, developing disseminated lesions. Miltefosine with amphotericin B and pentamidine resulted in remission. Lesions reappeared after one year, accompanied by intra-nasal infiltration of the disease. The nasal spraying of a single ampoule of pentavalent antimoniate resulted in the sustained disappearance of the nasal symptoms and all the cutaneous lesions. After over eight years, she remains disease-free, albeit under renal replacement therapy. The high nasal mucosal antimonial concentration may explain the long-lasting cure via new MHC class I epitope-specific CD8+ cell clones against L. amazonensis present in the nasal mucosa.

Antileishmanial activity of tetra-cationic porphyrins with peripheral Pt(II) and Pd(II) complexes mediated by photodynamic therapy.

Leishmaniasis is a neglected disease that impacts more than one billion people in endemic areas of the globe. Several drawbacks are associated with the currently existing drugs for treatment such as low effectiveness, toxicity, and the emergence of resistant strains that demonstrate the importance of looking for novel therapeutic alternatives. Photodynamic therapy (PDT) is a promising novel alternative for cutaneous leishmaniasis treatment because its topical application avoids potential side effects generally associated with oral/parenteral application. A light-sensitive compound known as photosensitizer (PS) interacts with light and molecular oxygen to generate reactive oxygen species (ROS), which promote cell death by oxidative stress through PDT approaches. Here, for the first time, we demonstrate the antileishmanial effect of tetra-cationic porphyrins with peripheral Pt(II)- and Pd(II)-polypyridyl complexes using PDT. The isomeric tetra-cationic porphyrins in the meta positions, 3-PtTPyP, and 3-PdTPyP, exhibited the highest antiparasitic activity against promastigote (IC50-pro = 41.8 nM and 46.1 nM, respectively) and intracellular amastigote forms (IC50-ama = 27.6 nM and 38.8 nM, respectively) of L. amazonensis under white light irradiation (72 J cm-2) with high selectivity (SI > 50) for both forms of parasites regarding mammalian cells. In addition, these PS induced the cell death of parasites principally by a necrotic process in the presence of white light by mitochondrial and acidic compartments accumulation. This study showed that porphyrins 3-PtTPyP and 3-PdTPyP displayed a promising antileishmanial-PDT activity with potential application for cutaneous leishmaniasis treatment.

Laurequinone, a Lead Compound against Leishmania.

Among neglected tropical diseases, leishmaniasis is one of the leading causes, not only of deaths but also of disability-adjusted life years. This disease, caused by protozoan parasites of the genus Leishmania, triggers different clinical manifestations, with cutaneous, mucocutaneous, and visceral forms. As existing treatments for this parasitosis are not sufficiently effective or safe for the patient, in this work, different sesquiterpenes isolated from the red alga Laurencia johnstonii have been studied for this purpose. The different compounds were tested in vitro against the promastigote and amastigote forms of Leishmania amazonensis. Different assays were also performed, including the measurement of mitochondrial potential, determination of ROS accumulation, and chromatin condensation, among others, focused on the detection of the cell death process known in this type of organism as apoptosis-like. Five compounds were identified that displayed leishmanicidal activity: laurequinone, laurinterol, debromolaurinterol, isolaurinterol, and aplysin, showing IC50 values against promastigotes of 1.87, 34.45, 12.48, 10.09, and 54.13 µM, respectively. Laurequinone was the most potent compound tested and was shown to be more effective than the reference drug miltefosine against promastigotes. Different death mechanism studies carried out showed that laurequinone appears to induce programmed cell death or apoptosis in the parasite studied. The obtained results underline the potential of this sesquiterpene as a novel anti-kinetoplastid therapeutic agent.