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Leishmania, a protozoan parasite, is responsible for the occurrence of leishmaniasis, a disease that is prevalent in tropical regions. Visceral Leishmaniasis (VL), also known as kala-azar in Asian countries, is one of the most significant forms of VL, along with Cutaneous Leishmaniasis (CL) and Mucocutaneous Leishmaniasis (ML). Management of this condition typically entails the use of chemotherapy as the sole therapeutic option. The current treatments for leishmaniasis present several drawbacks, including a multitude of side effects, prolonged treatment duration, disparate efficacy across different regions, and the emergence of resistance. To address this urgent need, it is imperative to identify alternative treatments that are both safer and more effective. The identification of appropriate pharmacological targets in conjunction with biological pathways constitutes the initial stage of drug discovery. In this review, we have addressed the key metabolic pathways that represent potential pharmacological targets as well as prominent treatment options for leishmaniasis., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

The protozoan parasite Leishmania donovani resides within mammalian macrophages and alters its antigen-presenting functions to negatively regulate host-protective T cell responses. This negative regulation of human T cell responses in vitro is attributed to myotubularin-related protein-6 (MTMR6), an ion channel-associated phosphatase. As mouse and human MTMR6 share homology, we studied whether MTMR6 silencing by lentivirally expressed MTMR6shRNA (Lv-MTMR6shRNA) reduced Leishmania growth in macrophages and whether MTMR6 silencing in Leishmania-susceptible BALB/c mice reduced the infection and reinstated host-protective T cell functions. MTMR6 silencing reduced amastigote count and IL-10 production, increased IL-12 expression and, induced IFN-γ-secreting T cells with anti-leishmanial activity in macrophage-T cell co-cultures. Lv-MTMR6shRNA reduced the infection, accompanied by increased IFN-γ expression, in susceptible BALB/c mice. Delays in Lv-MTMR6shRNA treatment by 7 days post-infection significantly reduced the infection suggesting MTMR6 as a plausible therapeutic target. Priming of BALB/c mice with avirulent parasites and Lv-MTMR6shRNA reduced parasite burden in challenge infection. These results indicate that MTMR6 is the first receptor-regulated ion channel-associated phosphatase regulating anti-leishmanial immune responses., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Data on cellular immunity mediators in the early phase of human leishmaniasis are still limited and controversial. In order to mimic the changes of humoral mediators during the early phase of human natural infection, some Th1, Th2, Treg, and Breg cytokines, MCP-1, and the nitric oxide (NO) from human PBMC, stimulated by Leishmania infantum, Leishmania major, Leishmania donovani and Leishmania tropica infective metacyclic promastigotes, were determined. After 4 h of L. major, L. donovani, and L. tropica challenge, TNFα, IL-1β, IL-6 levels were significantly higher than negative control cultures with saline (SF) instead of Leishmania promastigotes, unlike L. infantum-stimulated TNFα and L. major-stimulated IL-1β. We obtained higher levels of IL-4 and IL-10 cytokines after stimulation of human PBMCs by L. infantum and L. donovani, compared to those observed after the challenge of PBMCs by L. major and L. tropica. Regarding IL-35, such cytokine levels were significantly increased following infection with L. infantum and L. donovani, in contrast to L. major and L. tropica. Up to our knowledge, we are the first to study the effect of four different species of Leishmania on IL-35 levels in human cells. Our study highlights how several Leishmania species can up-regulate different groups of cytokines (Th1, Th2, Treg and Breg) and modulate NO release in a different way. This original aspect can be explained by different Leishmania cell products, such as LPG, obtained from different strains/species of live parasites. Our findings would contribute to the development of new therapeutics or vaccination strategies., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2023. Published by Elsevier B.V.)

One of the major reasons behind the limited success of vaccine candidates against all forms of leishmaniasis is the inability of parasitic antigens to induce robust cell-mediated immunity and immunological memory. Here we find, for the first time, that the adjuvantation of whole-killed Leishmania vaccine (Leishvacc) with anti-CD200 and anti-CD300a antibodies enhances CD4 + T cells mediated immunity in vaccinated mice and provides protection against wild-type parasites. The antibody adjuvantation, either alone or with a TLR4 agonist monophosphoryl A (MPL-A), induced the production of pro-inflammatory cytokines viz., IFN-γ, TNF-α, and IL-2 by antigen experienced CD4 + T cells, and also enhanced their rate of conversion into their memory phenotypes against Leishvacc antigens. The antibody adjuvanted vaccine also promoted the generation of IgG2a-mediated protective humoral immunity in vaccinated mice. Further, the mice vaccinated with antibodies adjuvanted vaccine showed strong resilience against metacyclic forms of L. donovani parasites as we observed reduced clinical features such as splenomegaly, hepatomegaly, granulomatous tissues in the liver, and parasitic load in their spleen. The findings of this study demonstrate that the anti-CD200 and anti-CD300a antibodies have potential to increase the protective efficacy of the whole-killed Leishmania vaccine, and opens up a new gateway to diversify the roles of immune checkpoints in vaccine development against leishmaniasis., Competing Interests: Declaration of Competing Interest The authors declare that the research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Antioxidant defense mechanisms are important for a parasite to overcome oxidative stress and survive within host macrophage cells. Mitochondrial iron superoxide dismutase A (FeSODA) and trypanothione reductase (TR) are critical enzymes in the antioxidant defense mechanism of Leishmania donovani. FeSODA is responsible for neutralizing reactive oxygen species in mitochondria, while TR is responsible for reducing trypanothione, the molecules that help the parasite fight oxidative stress in Leishmania. In this study, we used multitarget ligands to inhibit both the FeSODA and TR enzymes. We combined structure-based drug design using virtual screening approach to find inhibitors against both the targets. The ZINC15 database of biogenic compounds was utilized to extract drugs-like molecules against leishmaniasis. The compounds were screened by standard precision (SP) and extra precision (XP) docking methods. Two compounds, ZINC000008876351 and ZINC000253403245, were selected based on molecular docking based on the binding affinity for both the targets. The screened molecules ZINC000008876351 and ZINC000253403245 showed strong hydrogen bonding with the target proteins according to the Molecular mechanics with generalised Born and surface area solvation (MM-GBSA) techniques. These two compounds were also experimentally investigated on promastigotes stage of L. donovani. Under in vitro condition, the compounds show inhibitory effects on L. donovani promastigotes with IC 50 values of 24.82 ± 0.61 µM for ZINC000008876351 and 7.52 ± 0.17 µM for ZINC000253403245. Thus, the screened compounds seem to have good potential as therapeutic candidates for leishmaniasis., (© 2023. The Author(s).)

One of the global problems of rising concern is the spread of the neglected tropical disease, leishmaniasis. There are several drugs used for the treatment of the disease but the repertoire of drugs has drawbacks like toxicity and low therapeutic value. Considering the need for new drugs, we studied the synthesis of 4',7-dihydroxyflavone conjugated multi-walled carbon nanotubes (47DHF-MWCNTs) and evaluated their anti-leishmanial activity against Leishmania donovani. The compound 47DHF was conjugated to the acid oxidized MWCTNs by Steglich esterification. The synthesized 47DHF-MWCNTs were characterized by UV spectroscopy, and, from the zeta value of 35 mV, they were found to be stable. 47DHF-MWCNTs possessed 84% drug loading efficiency and 63% cumulative drug release at intra-macrophage pH of 5.8. Moreover, the evaluation of 47DHF-MWCNTs for activity showed an IC 50 value of 0.051 ± 0.01 μg/ml and 0.072 ± 0.01 μg/ml against the promastigote and amastigote form, respectively. 47DHF-MWCNTs exhibited an infectivity index of 42 and selectivity index of 95, suggesting the activity of 47DHF-MWCNTs against intracellular amastigotes in the study. The 47DHF-MWCNTs also had low cytotoxicity towards macrophage cells. Fascinatingly, the 47DHF-MWCNTs treatment causes a high accumulation of ROS in the promastigotes suggesting the mechanism of anti-leishmanial activity to be ROS mediated. Summarizing from our results, we propose for the first time a novel 47DHF conjugated MWCNTs capable of anti-leishmanial activity with lower cytotoxicity that has a huge potential to be a formulation against leishmaniasis., Competing Interests: Declaration of Competing Interest Prakash Saudagar reports financial support was provided by Science and Engineering Research Board. Prakash Saudagar has patent pending to IP India., (Copyright © 2023. Published by Elsevier B.V.)

Autochthonous leishmaniasis in Thailand has recently been a public health concern due to an increasing number of new clinical cases. Most indigenous cases were diagnosed with Leishmania (Mundinia) martiniquensis, and Leishmania (Mundinia) orientalis. However, some doubts regarding vector misidentification have arisen and need to be elucidated. Accordingly, we aimed to assess the species composition of sand flies and determine the molecular prevalence of trypanosomatids in the transmission area of leishmaniasis in southern Thailand. In the present study, a total of 569 sand flies were caught from the vicinity of a visceral leishmaniasis patient's house in Na Thawi District, Songkhla Province. Of these, 229 parous and gravid females consisted of Sergentomyia khawi, Se. barraudi, Phlebotomus stantoni, Grassomyia indica, and Se. hivernus, accounting for 31.4%, 30.6%, 29.7%, 7.9%, and 0.4%, respectively. However, Se. gemmea, which has previously been proposed as the most abundant species and putative vector of visceral leishmaniasis, was not found in the present study. Based on ITS1-PCR and sequence analysis, two specimens of Gr. indica and Ph. stantoni showed positive amplification of L. martiniquensis and L. donovani complex, respectively, the first one being presumed indigenous and the second one being not. Anuran Trypanosoma was also molecularly detected using SSU rRNA-PCR and ubiquitously found in 16 specimens of four dominant sand fly species except for Se. hivernus. The obtained sequences could be phylogenetically categorized into the two major amphibian clades (An04/Frog1 and An01+An02/Frog2). The existence of the monophyletic subgroup and distinct lineage suggests them as novel Trypanosoma species. The TCS network analysis of these anuran Trypanosoma sequences also revealed high haplotype diversity (Hd = 0.925 ± 0.050), but low nucleotide diversity (π = 0.019 ± 0.009). Furthermore, the living anuran trypanosomes were microscopically demonstrated in a single specimen of Gr. indica, supporting the vectorial capacity. Importantly, our data confirmed the scarcity of Se. gemmea and also uncovered, for the first time, the co-circulation of L. martiniquensis, L. donovani complex, and suspected novel anuran Trypanosoma spp. in phlebotomine sand files, implicating their potential role as vectors of trypanosomatid parasites. Therefore, the novel data from this study would greatly facilitate the comprehension of the complexity of trypanosomatid transmission and the establishment of prevention and control measures for this neglected disease more effectively., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The current regime for leishmaniasis is associated with several adverse effects, expensive, parenteral treatment for longer periods and the emergence of drug resistance. To develop affordable and potent antileishmanial agents, a series of N-acyl and homodimeric aryl piperazines were synthesized with high purity, predicted druggable properties by in silico methods and investigated their antileishmanial activity. The in vitro biological activity of synthesized compounds against clinically validated intracellular amastigote and extracellular promastigote form of Leishmania donovani parasite showed eight compounds inhibited 50% amastigotes growth below 25 µM. The half maximal inhibitory concentration (IC 50 ) and cytotoxicity assessment of eight active compounds, 4a, 4d and 4e demonstrated activity with an IC 50 2.0 - 9.1 µM and selectivity index 10 - 42. Compound 4d (IC 50 2.0 µM, SI = 42) found to be the best among them with four-folds more potent and eight-folds less toxic than the control drug miltefosine. Overall, results demonstrated that compound 4d is a promising lead candidate for further development as antileishmanial drug., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Leishmaniasis is considered as one of the 20 neglected tropical diseases. Current methods of leishmanial diagnosis depend on conventional laboratory-based techniques, which are time-consuming, costly and require special equipment and trained personnel. In this context, we aimed to provide an immuno field effect transistors (ImmunoFET) biosensor that matches the conventional standards for point-of-care (POC) monitoring and detection of Leishmania (L.) donovani/Leishmania major. Crude antigens prepared by repeated freeze thawing of L. donovani/L. major stationary phase promastigotes were used for ELISA and ImmunoFETs. Lesishmania-specific antigens were serially diluted in 1× PBS from a concentration of 10 6 -10 2 parasites/mL. A specific polyclonal antibody-based sandwich ELISA was established for the detection of Leishmania antigens. An immunoFET technology-based POC novel assay was constructed for the detection of Leishmania antigens. Interactions between antigen-antibody at the gate surface generate an electrical signal that can be measured by semiconductor field-effect principles. Sensitivity was considered and measured as the change in current divided by the initial current. The final L. donovani/L. major crude antigen protein concentrations were measured as 1.50 mg/mL. Sandwich ELISA against the Leishmania 40S ribosomal protein detected Leishmania antigens could detect as few as 100 L. donovani/L. major parasites. An immunoFET biosensor was constructed based on the optimization of aluminium gallium nitride/gallium nitride (AlGaN/GaN) surface oxidation methods. The device surface was composed by an AlGaN/GaN wafer with a 23 nm AlGaN barrier layer, a 2 μm GaN layer on the silicon carbide (SiC) substrate for Leishmania binding, and coated with a specific antibody against the Leishmania 40S ribosomal protein, which was successfully detected at concentrations from 10 6 to 10 2 parasites/mL in 1× PBS. At the concentration of 10 4 parasites, the immunoFETs device sensitivities were 13% and 0.052% in the sub-threshold regime and the saturation regime, respectively. Leishmania parasites were successfully detected by the ImmunoFET biosensor at a diluted concentration as low as 150 ng/mL. In this study, the developed ImmunoFET biosensor performed well. ImmunoFET biosensors can be used as an alternative diagnostic method to ELISA. Increasing the sensitivity and optimization of immuno-FET biosensors might allow earlier and faster detection of leishmaniasis., (© 2023 John Wiley & Sons Ltd.)

As important immunomodulators, CpG ODNs have broad application prospects in the treatment and prevention of leishmaniasis. In order to explore the immunomodulatory effect of CpG ODNs on mice infected with Leishmania parasites in different nutritional status, TLR9 agonist CpG ODN 2395 or TLR9 antagonist CpG ODN 2088 was injected into normal, obesity and undernutrition BALB/c mice infected with Leishmania donovani, respectively. Subsequently, spleen and liver parasite loads, spleen and liver immune gene expression, spleen T cell subsets proportion and PD-1 expression, serum lipids, serum cytokines, and anti-Leishmania antibodies were measured to assess the immune response of mice with different nutritional status. The results displayed that at the 8th week after infection, the spleen parasite load of obesity and undernutrition mice was significantly higher than that of normal mice, but the liver parasite load showed no statistical difference among the three groups. The treatment of CpG ODN 2395 or CpG ODN 2088 significantly reduced the spleen parasite load of obesity and undernutrition infected mice, but did not reduce that of normal infected mice. In obesity infected mice, CpG ODN 2395 promoted the up-regulation of TCR, ICOS and TLR4 in spleen, promoted the secretion of IFN-γ and anti-Leishmania total IgG and IgG1 antibodies, and increased the content of serum HDL-C. In undernutrition infected mice, CpG ODN 2395 promoted the up-regulation of spleen CD28 and TLR9, increased the proportion of spleen CD3 + T cells, and decreased the content of serum IL-10. Our results demonstrated that CpG ODN 2395 enhanced the immune response and clearance of Leishmania parasites in obesity and undernutrition mice, which might be used as a therapeutic agent for obesity and undernutrition leishmaniasis patients in the future., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The Oceanimonas sp. BPMS22 -derived protein protease inhibitor (PPI) has been proven to shift macrophages towards an inflammatory state and reduce Leishmania donovani infection in vitro and in vivo . The current study explored and validated the mechanistic aspects of the PPI and Toll-like receptor (TLR) interaction. The PPI exhibited the upregulation of TLR2, TLR4, and TLR6 during treatment which was proven to orchestrate parasite clearance effectively. An in silico study confirmed the high interaction with TLR4 and PPI. Immune blotting confirmed the significant upregulation of TLR4 in macrophages irrespective of L. donovani infection. Pharmacological inhibition and immune blot study confirmed the involvement of the PPI in TLR4-mediated phosphorylation of p38 MAPK and dephosphorylation of ERK1/2, repolarizing to pro-inflammatory macrophage state against experimental visceral leishmaniasis. In addition, in TLR4 knockdown condition, PPI treatment failed to diminish M2 phenotypical markers (CD68, Fizz1, Ym1, CD206, and MSR-2) and anti-inflammatory cytokines (IL-4, IL-10, and TGF-β). Simultaneously, the PPI failed to upregulate the M1 phenotypical markers and pro-inflammatory cytokines (IL-1β, IL-6, IL-12, and IFN-γ) ( p < 0.001) during the TLR4 knockdown condition. In the absence of TLR4, the PPI also failed to reduce the parasite load and T-cell proliferation and impaired the delayed-type hypersensitivity response. The absence of pro-inflammatory cytokines was observed during a co-culture study with PPI-treated macrophages (in the TLR4 knockdown condition) with day 10 T-cell obtained from L. donovani -infected mice. This study supports the immunotherapeutic potential of the PPI as it interacted with TLR4 and promoted macrophage repolarization (M2-M1) to restrict the L. donovani parasite burden and helps in the mounting immune response against experimental visceral leishmaniasis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Jayaraman, Srinivasan, Uppuluri and Kar Mahapatra.)

The unique bisubunit structure of Leishmania donovani topoisomerase 1B (LdTop1) is a potential drug target in the parasites unlike the monomeric Top1 from its human host counterpart. Here, we report the design, synthesis, and validation of a chimeric pyrido[2',1':2,3]imidazo[4,5- c ]quinoline derivative ( C17 ) as a novel antileishmanial agent that poisons topoisomerase 1-DNA covalent complexes (LdTop1cc) inside the parasites and inhibits Top1 religation activity both in the drug sensitive and antimony-resistant L. donovani clinical isolates. Importantly, the human Top1 is not sensitive to C17 . Further, C17 overcomes the chemical instability of camptothecin (CPT) by generating persistent LdTop1cc-induced DNA breaks inside the parasites even after 12 h of drug removal. Intraperitoneal administration of C17 results in marked reduction of the Leishmania amastigotes from the infected spleen and liver of BALB/c mice. C17 confers a host protective immune-response up-regulating the Th1 cytokines facilitating parasite clearance which can be exploited for treating drug-resistant leishmaniasis.

Purpose: Leishmaniasis is a parasitic disease transmitted by the bite of the phlebotomine female sand fly. Currently, no reported effective vaccines are available for the treatment of leishmaniasis; consequently, restricting this disease completely depends on controlling its transmission. Mitogen-activated protein (MAP) kinases have been reported to be involved in the regulation of the flagellum length and hence play an important role in disease transmission, especially the MAPK3 protein. Therefore, the current work focused on identifying approved drugs that can inhibit the MAPK3 protein., Methods: First, the recombinant plasmid (pET28b( +) MAPK3) was cloned into E. coli strain BL21 using the heatshock method. Afterward, E. coli was induced using IPTG, and cells were harvested for protein purification in the next step. After that, the MAPK3 protein was purified using Ni-NTA column. Then, the inhibition kinase activity of the purified MAPK3 protein was performed using an ADP-Glo ™ Kinase Assay kit. Furthermore, the cytotoxicity of Leishmania cells were detected by alamarBlue ™ Cell Viability Reagent. Finally, the binding affinity within the binding site of MAPK3 protein was performed by computational methods., Results: Purification of the MAPK3 protein was done using an Ni-NTA column and a protein band was identified at the expected 44 kDa molecular weight. Afterward, the ability of commercial drugs (afatinib and lapatinib) to inhibit the purified MAPK3 kinase activity was performed using an ADP-Glo ™ Kinase Assay kit. The half-maximal inhibitory concentrations (IC 50 ) of two drugs inhibited the MAPK3 protein within the same range of IC 50 values (3.27 and 2.22 µM for afatinib and lapatinib, respectively). Furthermore, the cytotoxicity assay of compounds toward the extracellular promastigote and intracellular amastigote stages was investigated using alamarBlue ™ Cell Viability Reagent. The results showed that both drugs were more efficient against extracellular promastigotes and intracellular amastigotes of both Leishmania donovani and Leishmania martiniquensis. Finally, the molecular dynamics simulation (MD) was performed to study the intermolecular interactions of both drugs with MAPK3 protein. From 100 ns molecular dynamics simulation, the structural stability of both drugs in a complex with MAPK3 was quite stable., Conclusion: This work was suggesting that afatinib and lapatinib act as MAPK3 inhibitors and might be developed for leishmaniasis treatment., (© 2023. The Author(s) under exclusive licence to Witold Stefański Institute of Parasitology, Polish Academy of Sciences.)

The available therapeutic treatment for leishmaniasis is inadequate and toxic due to side effects, expensive and emergence of drug resistance. Affordable and safe antileishmanial agents are urgently needed and toward this objective, we synthesized a series of 32 novel halogen rich salicylanilides including niclosamide and oxyclozanide and investigated their antileishmanial activity against amastigotes of Leishmania donovani. In vitro data showed fifteen compounds inhibited intracellular amastigotes with an IC 50 of below 5 μM and selectivity index above 10. Among 15 active compounds, 14 and 24 demonstrated better activity with an IC 50 of 2.89 μM and 2.09 μM respectively and selectivity index is 18. Compound 24 exhibited significant in vivo antileishmanial efficacy and reduced 65% of the splenic parasite load on day 28th post-treatment in the experimental visceral leishmaniasis golden hamster model. The data suggest that 24 can be a promising lead candidate possessing potential to be developed into a leishmanial drug candidate., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Leishmaniasis is a vector-borne parasitic disease that mostly affects populations in tropical and sub-tropical countries. There is currently no protective anti-leishmanial vaccine and only a paucity of clinical drugs is available to treat this disease albeit their toxicity. Leishmaniasis is curable but its eradication and elimination have been hampered by the emergence of multidrug resistant strains of the causative pathogens. This heightens the necessity for new and effective antileishmanial drugs. In search for such agents, nitrofurantoin, a clinical antibiotic, was appended to triazole scaffold through alkylene linkers of various length, and the resulting hybrids were evaluated for in vitro antileishmanial efficacy against Leishmania (L.) parasite of two strains. The hybrid 13, harboring a n-pentylene linker was uncovered as a leishmanicidal hit with micromolar activity against antimonial-resistant L. donovani, the causative of deadly visceral Leishmaniasis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Leishmaniasis is one of the Neglected Tropical Diseases (NTDs), a zoonotic disease of vector-borne nature that is caused by a protozoan parasite Leishmania . This parasite is transmitted by the vector sandfly into the human via a bite. Visceral leishmaniasis (VL), also called kala-azar, is the most fatal among the types of leishmaniasis, with high mortality mostly spread in the East Africa and South Asia regions. WHO report stated that approximately 3.3 million disabilities occur every year due to the disease along with approximately 50,000 annual deaths. The real matter of concern is that there is no particular effective medicine/vaccine available against leishmaniasis to date except a few approved drugs and chemotherapy for the infected patient. The current selection of small compounds was constrained, and their growing drug resistance had been a major worry. Additionally, the serious side effects on humans of the available therapy or drugs have made it essential to discover efficient and low-cost methods to speed up the development of new drugs against leishmaniasis. Ideally, the vaccine could be a low risk and effective alternative for both CL and VL and elicit long-lasting immunity against the disease. There are a number of vaccine candidates at various stages of clinical development and preclinical stage. However, none has successfully passed all clinical trials. But, the successful development and approval of commercially available vaccines for dogs against canine leishmaniasis (CanL) provides evidence that it can be possible for humans in distant future. In the present article, the approaches used for the development of vaccines for leishmaniasis are discussed and the progress being made is briefly reviewed., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Leishmaniasis, a category I neglected tropical disease, is a group of diseases caused by the protozoan parasite Leishmania species with a wide range of clinical manifestations. Current treatment options can be highly toxic and expensive, with drug relapse and the emergence of resistance. Bacteriocins, antimicrobial peptides ribosomally produced by bacteria, are a relatively new avenue for potential antiprotozoal drugs. Particular interest has been focused on enterocin AS-48, with previously proven efficacy against protozoan species, including Leishmania spp. Sequential characterization of enterocin AS-48 has illustrated that antibacterial bioactivity is preserved in linearized, truncated forms; however, minimal domains of AS-48 bacteriocins have not yet been explored against protozoans. Using rational design techniques to improve membrane penetration activity, we designed peptide libraries using the minimal bioactive domain of AS-48 homologs. Stepwise changes to the charge ( z ), hydrophobicity ( H ), and hydrophobic dipole moment (μ H ) were achieved through lysine and tryptophan substitutions and the inversion of residues within the helical wheel, respectively. A total of 480 synthetic peptide variants were assessed for antileishmanial activity against Leishmania donovani. One hundred seventy-two peptide variants exhibited 50% inhibitory concentration (IC 50 ) values below 20 μM against axenic amastigotes, with 60 peptide variants in the nanomolar range. Nine peptide variants exhibited potent activity against intracellular amastigotes with observed IC 50 values of <4 μM and limited in vitro host cell toxicity, making them worthy of further drug development. Our work demonstrates that minimal bioactive domains of naturally existing bacteriocins can be synthetically engineered to increase membrane penetration against Leishmania spp. with minimal host cytotoxicity, holding the promise of novel, potent antileishmanial therapies. IMPORTANCE Leishmaniasis is a neglected tropical disease caused by protozoan parasites of the genus Leishmania . There are three primary clinical forms, cutaneous, mucocutaneous, and visceral, with visceral leishmaniasis being fatal if left untreated. Current drug treatments are less than ideal, especially in resource-limited areas, due to the difficult administration and treatment regimens as well as the high cost and the emergence of drug resistance. Identifying potent antileishmanial agents is of the utmost importance. We utilized rational design techniques to synthesize enterocin AS-48 and AS-48-like bacteriocin-based peptides and screened these peptides against L. donovani using a fluorescence-based phenotypic assay. Our results suggest that bacteriocins, specifically these rationally designed AS-48-like peptides, are promising leads for further development as antileishmanial drugs.

Purpose: Leishmaniasis is a neglected infectious disease affecting millions of people worldwide. Visceral leishmaniasis (VL), caused by Leishmania infantum and Leishmania donovani, is one of the main clinical forms of the disease and fatal if not treated promptly and properly. Despite being available for the last 70 years, current drugs used in the treatment of leishmaniasis have serious problems as they have high toxicity, require long-term administration and cause serious side-effects, leading to the emergence of resistant and relapse cases. Therefore, there is an urgent need for the discovery of novel antileishmanial molecules and the development of new treatment regimens. The drug used for chemotherapy of B-cell malignancies, Ibrutinib, an inhibitor of Bruton's Tyrosine Kinase (BTK), can offer a new therapeutic perspective due to the functions of BTK on intracellular signaling mechanism of macrophages, which are the primary resident cell for Leishmania. Hence, the study aimed to evaluate ibrutinib as a potential anti-Leishmanial drug., Method: In this study, we evaluated the antileishmanial effect of Ibrutinib by in vitro L. infantum infection model using macrophages, with cell viability assay, parasite rescue assay, real-time qPCR., Results: We showed that Ibrutinib was significantly more effective than the Glucantime against L. infantum. In addition, our data revealed that Ibrutinib inhibited parasite growth and load without impairing macrophage viability., Conclusions: Consequently, due to its efficacy and safety, Ibrutinib may be a promising candidate for the treatment of VL caused by L. infantum as a host-targeted drug., (© 2022. The Author(s) under exclusive licence to Witold Stefański Institute of Parasitology, Polish Academy of Sciences.)

Leishmaniasis on the Indian subcontinent is thought to have an anthroponotic transmission cycle. There is no direct evidence that a mammalian host other than humans can be infected with Leishmania donovani and transmit infection to the sand fly vector. The aim of the present study was to evaluate the impact of sand fly feeding on other domestic species and provide clinical evidence regarding possible non-human reservoirs through experimental sand fly feeding on cows, water buffalo goats and rodents. We performed xenodiagnosis using colonized Phlebotomus argentipes sand flies to feed on animals residing in villages with active Leishmania transmission based on current human cases. Xenodiagnoses on mammals within the endemic area were performed and blood-fed flies were analyzed for the presence of Leishmania via qPCR 48hrs after feeding. Blood samples were also collected from these mammals for qPCR and serology. Although we found evidence of Leishmania infection within some domestic mammals, they were not infectious to vector sand flies. Monitoring infection in sand flies and non-human blood meal sources in endemic villages leads to scientific proof of exposure and parasitemia in resident mammals. Lack of infectiousness of these domestic mammals to vector sand flies indicates that they likely play no role, or a very limited role in Leishmania donovani transmission to people in Bihar. Therefore, a surveillance system in the peri-/post-elimination phase of visceral leishmaniasis (VL) must monitor absence of transmission. Continued surveillance of domestic mammals in outbreak villages is necessary to ensure that a non-human reservoir is not established, including domestic mammals not present in this study, specifically dogs., Competing Interests: The authors have declared that no competing interests exist.

People living with HIV (PLHIV) have an increased risk of developing visceral leishmaniasis (VL) and poor outcomes compared to HIV negative individuals. Here, we aim to establish the prevalence and determinants of asymptomatic Leishmania infection (ALI) in a cohort of PLHIV in Bihar, India. We hoped to evaluate optimal diagnostic algorithms to detect ALI in PLHIV. We conducted a cross-sectional survey of PLHIV ≥18 years of age with no history or current diagnosis of VL or post kala-azar dermal leishmaniasis (PKDL) at anti-retroviral therapy centres within VL endemic districts of Bihar. ALI was defined as a positive rK39 enzyme-linked immunosorbent assay (ELISA), rK39 rapid diagnostic test (RDT) and/or quantitative polymerase chain reaction (qPCR). Additionally, the urinary Leishmania antigen ELISA was evaluated. Determinants for ALI were established using logistic regression and agreement between diagnostic tests calculated using Cohen's Kappa. A total of 1,296 PLHIV enrolled in HIV care, 694 (53.6%) of whom were female and a median age of 39 years (interquartile range 33-46), were included in the analysis. Baseline prevalence of ALI was 7.4% (n = 96). All 96 individuals were positive by rK39 ELISA, while 0.5% (n = 6) and 0.4% (n = 5) were positive by qPCR and rK39 RDT, respectively. Negligible or weak agreement was seen between assays. Independent risk factors for ALI were CD4 counts <100 (OR 3.1; 95% CI 1.2-7.6) and CD4 counts 100-199 (OR = 2.1;95% CI:1.1-4.0) compared to CD4 counts ≥300, and a household size ≥5 (OR = 1.9;95% CI:1.1-3.1). A total of 2.2% (n = 28) participants were positive by Leishmania antigen ELISA, detecting 20 additional participants to the asymptomatic cohort. Prevalence of ALI in PLHIV in VL endemic villages in Bihar was relatively high. Using the Leishmania antigen ELISA, prevalence increased to 9.0%. Patients with low CD4 counts and larger household size were found to have significantly higher risk of ALI. Trial Registration: Clinical Trial Registration CTRI/2017/03/008120., Competing Interests: The authors have declared that no competing interests exist.

Myo-inositol is one of the vital nutritional requirements for the Leishmania parasites' survival and virulence in the mammalian host. . Myo-inositol-1-phosphate synthase (MIPS) is responsible for the synthesis of myo-inositol in Leishmania , which plays a vital role in Leishmania's virulence to mammalian hosts. Earlier studies suggest MIP synthase as a potential drug target against which valproate was used as a drug. So, MIP synthase can be used as a target for anti-leishmanial drugs, and its inhibition may help in preventing leishmaniasis. The present study aims to identify valproate's potent analogs as drugs against MIP synthase of L. donovani ( Ld- MIPS) with minimum side effects and toxicity to host.In this study, the three-dimensional structure of Ld- MIPS was built, followed by active site prediction. Ligand-based virtual screening was done using hybrid similarity recognition methods. The best 123 valproate analogs were filtered based on their quantitative structure activity relationship (QSAR) properties and were docked against Ld -MIPS using FlexX, PyRx and iGEMDOCK software. The topmost five ligands were selected for molecular dynamics simulation and pharmacokinetic analysis based on the docking score. Simulation studies up to 30 ns revealed that all five lead molecules bound with Ld -MIPS throughout MD simulation and there was no variation in their backbone. All the chosen inhibitors exhibited good pharmacokinetics/ADMET predictions with an excellent absorption profile, metabolism, oral bioavailability, solubility, excretion, and minimal toxicity, suggesting that these inhibitors may further be developed as anti-leishmaniasis drugs to prevent the spread of leishmaniasis.Communicated by Ramaswamy H. Sarma.

There is a need for new, cost-effective drugs to treat leishmaniasis. A strategy based on traditional medicine practiced in Bolivia led to the discovery of the 2-substituted quinoline series as a source of molecules with antileishmanial activity and low toxicity. This review documents the development of the series from the first isolated natural compounds through several hundred synthetized molecules to an optimized compound exhibiting an in vitro IC 50 value of 0.2 µM against Leishmania donovani , and a selectivity index value of 187, together with in vivo activity on the L. donovani /hamster model. Attempts to establish structure-activity relationships are described, as well as studies that have attempted to determine the mechanism of action. For the latter, it appears that molecules of this series act on multiple targets, possibly including the immune system, which could explain the observed lack of drug resistance after in vitro drug pressure. We also show how nanotechnology strategies could valorize these drugs through adapted formulations and how a mechanistic targeting approach could generate new compounds with increased activity.

Pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones were synthesized, for the first time, from indole chalcones and 6-aminouracil, and their ability to inhibit leishmaniasis and tuberculosis (Tb) infections was evaluated. The in vitro antileishmanial activity against promastigotes of Leishmania donovani revealed exceptional activities of compounds 3, 12 and 13, with IC 50 values ranging from 10.23 ± 1.50 to 15.58 ± 1.67 µg/ml, which is better than the IC 50 value of the standard drug pentostam of 500 μg/ml. The selectivity of the compounds towards Leishmania parasites was evaluated via ex vivo studies in Swiss albino mice. The efficiency of these compounds against Tb infection was then evaluated using the in vitro anti-Tb microplate Alamar Blue assay. Five compounds, 3, 7, 8, 9 and 12, showed MIC 100 values against the Mycobacterium tuberculosis H 37 Rv strain at 25 µg/ml, and compound 20 yielded an MIC 100 value of 50 µg/ml. Molecular modelling of these compounds highlighted interactions with binding sites of dihydrofolate reductase, pteridine reductase and thymidylate kinase, thus establishing the rationale of their pharmacological activity against both pathogens, which is consistent with the in vitro results. From the above results, it is clear that compounds 3 and 12 are promising lead candidates for Leishmania and Mycobacterium infections and may be promising for coinfections., (© 2022 Deutsche Pharmazeutische Gesellschaft.)

This study reports the synthesis and characterization of zinc derivatized 3,5-dihydroxy 4', 7- dimethoxyflavone (DHDM-Zn) compound for the development of new antileishmanial agents. The interaction studies of DHDM with zinc were carried out by UV spectra and fluorescence spectra analysis. Characterization of the complex was further accomplished by multi-spectroscopic techniques such as FTIR, Raman, HRMS, NMR, FESEM-EDX. The morphological and topographical studies of synthesized DHDM-Zn were carried out using FESEM with EDX. Further, it was demonstrated that DHDM-Zn exhibited an excellent in vitro antagonistic effect against the promastigote form of L. donovani. In addition, the possible mechanisms of promastigote L. donovani cell death, by involvement of derivatized compound in arrest of the cell cycle in the G1 phase and residual cell count reduction were investigated. Promastigote growth kinetics performed in the presence of the derivatized compound revealed a slow growth rate. The combination of growth kinetics and cell cycle analysis, made it possible to interpret and classify the cause of leishmanial cell death accurately. These results support that zinc derivatized complex (DHDM-Zn) might work as a lead compound for designing and developing a new antileishmanial drug., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: We report a clinically challenging and unusual case of L. donovani oral mucosal leishmaniasis., Case Presentation: Israeli resident with a former travel to central and North Africa, with no documented or prior cutaneous lesions presented with oral lesions of the maxillary gingiva and the upper lip. A delay in diagnosis and treatment have led to progression of the maxillary gingival lesions towards the hard palatal and the soft palate that could have potentially compromised the upper airway., Conclusions: This case highlights the importance of early diagnosis of leishmaniasis in patients with oral lesions and the laboratory workup necessary to appropriately characterize and treat the disease., (© 2022. The Author(s).)

Biology-Oriented Drug Synthesis (BIODS) deals with the simple chemical transformations on the commercially available drugs in order to enhance their new and diversified pharmacological profile. It opens new avenues for the rapid development of drug candidates for neglected tropical diseases (NTDs). Leishmaniasis is one of the NTDs which spread by the bite of sandflies (plebotomine). It ranges from cutaneous self-healing leishmaniasis to life threatening visceral leishmaniasis, known as kala-azar. The current treatment options include the use of pentamidine, miltefosine, and amphotericin B drugs. Unfortunately, all currently available drugs are associated with adverse effects, such as severe nephron- and cardiotoxicity, pancreatitis, and hepatotoxicity. This warrants the development of new drugs against leishmaniasis. Moreover, emergence of resistance against the current medications further worsens the conditions. With this objective, new N, N'-disubstituted benzylamine derivatives of ampyrone (4-aminoantipyrine) were synthesized by using ultrasonication, and microwave assistance. All derivatives were found to be new, except 1, 4, and 11. All the compounds were evaluated for their anti-leishmanial activity, and cellular cytotoxicity. Among them, compounds 4, 5, 8, and 9 showed a significant anti-leishmanial activity in vitro, in comparison to standard drug, miltefosine (IC 50  = 25.78 ± 0.2 µM). These compounds were also docked against various metabolic enzymes to predict their interactions and mechanism of action, and were found to act via targeting important enzymes of various metabolic pathways., (Copyright © 2022. Published by Elsevier Inc.)

Coinfection is less commonly observed in individuals around the world, yet it is more common than the single infection. Around 800 million people worldwide are infected with helminths as a result of various diseases. Lymphatic filariasis (LF) and visceral leishmaniasis (VL) are chronic, deadly, crippling, and debilitating neglected tropical diseases (NTDs) that are endemic in tropical and subtropical regions of the world. Due to poor hygienic conditions, poverty, and genetic predisposition, those living in endemic areas are more likely to develop both leishmaniasis and filariasis. One of the key challenges in the management of LF/VL coinfection is the development of an effective therapeutic strategy that not only treats the first episode of VL but also prevents LF. However, there is a scarcity of knowledge and data on the relationship between LF and VL coinfection. While reviewing it was apparent that only a few studies relevant to LF/VL coinfections have been reported from southeastern Spain, Sudan, and the Indian subcontinents, highlighting the need for greater research in the most affected areas. We also looked at LF and VL as a single disease and also as a coinfection. Some features of the immune response evolved in mammalian hosts against LF and VL alone or against coinfection are also discussed, including epidemiology, therapeutic regimens, and vaccines. In addition to being potentially useful in clinical research, our findings imply the need for improved diagnostic methodology and therapeutics, which could accelerate the deployment of more specific and effective diagnosis for treatments to lessen the impact of VL/LF coinfections in the population., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Immune metabolic adaptation in macrophages by intracellular parasites is recognized to play a crucial role during Leishmania infection. However, there is little accessible information about changes in a metabolic switch in L. donovani infected macrophages. In previous studies, we have reported on the anti-leishmanial synergic effect of eugenol oleate with amphotericin B. In the present study, we demonstrated that glycolytic enzymes were highly expressed in infected macrophages during combinatorial treatment of eugenol oleate (2.5 µM) and amphotericin B (0.3125 µM). Additionally, we found that the biphasic role in arachidonic acid metabolite, PGE2, and LTB4, is released during this treatment. In vitro data showed that COX-2 mediated PGE2 synthesis increased significantly (p<0.01) in infected macrophages. Not only was the level of prostaglandin synthesis decreased 4.38 fold in infected macrophages after treatment with eugenol oleate with amphotericin B. The mRNA expression of PTGES, MPGES, and PTGER4 were also moderately expressed in infected macrophages, and found to be decreased in combinatorial treatment. In addition, NOS2 expression was activated by the phosphorylation of p38MAPK when combination-treated macrophages were promoted to kill intracellular parasites. The findings of the present study indicate that the synergism between eugenol oleate and amphotericin B could play an important role in immune metabolism adaptation with a concomitant increase in host immune response against the intracellular pathogen, L. donovani ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Kar, Jayaraman, Kumar and Kar Mahapatra.)

A library of seventeen novel ether phospholipid analogues, containing 5-membered heterocyclic rings (1,2,3-triazolyl, isoxazolyl, 1,3,4-oxadiazolyl and 1,2,4-oxadiazolyl) in the lipid portion were designed and synthesized aiming to identify optimised miltefosine analogues. The compounds were evaluated for their in vitro antiparasitic activity against Leishmania infantum and Leishmania donovani intracellular amastigotes, against Trypanosoma brucei brucei and against different developmental stages of Trypanosoma cruzi . The nature of the substituents of the heterocyclic ring (tail) and the oligomethylene spacer between the head group and the heterocyclic ring was found to affect the activity and toxicity of these compounds leading to a significantly improved understanding of their structure-activity relationships. The early ADMET profile of the new derivatives did not reveal major liabilities for the potent compounds. The 1,2,3-triazole derivative 27 substituted by a decyl tail, an undecyl spacer and a choline head group exhibited broad spectrum antiparasitic activity. It possessed low micromolar activity against the intracellular amastigotes of two L. infantum strains and T. cruzi Y strain epimastigotes, intracellular amastigotes and trypomastigotes, while its cytotoxicity concentration (CC 50 ) against THP-1 macrophages ranged between 50 and 100 μM. Altogether, our work paves the way for the development of improved ether phospholipid derivatives to control neglected tropical diseases.

Leishmania donovani , causes leishmaniasis, a global health trouble with around 89 different countries and its population under its risk. Replication initiation events have been instrumental in regulating the DNA duplication and as the small subunit of L. donovani nuclear DNA primase ( Ld -PriS) inherits the catalytic site, it plays a vital role in DNA replication. In this study we have aimed Ld- PriS for the first time as a prospective target for the application of drug against Leishmania parasite. 3-D structures of Ld -PriS were built and ligand-based virtual screening was performed using hybrid similarity recognition techniques. Ligands from the ZINC database were used for the screening purposes based on known DNA primase inhibitor Sphingosine as a query. Top 150 ligands were taken into consideration for molecular docking against the query protein ( Ld -PriS) using PyRx and iGEMDOCK softwares. Top five compounds with the best docking score were selected for pharmacokinetic investigation and molecular dynamic simulation. These top five screened inhibitors showed very poor binding affinity toward the catalytic subunit of human primase indicating their safety toward the host normal replication mechanism. The top five compounds showed good pharmacokinetic profiles and ADMET predictions revealed good absorption, solubility, permeability, uniform distribution, proper metabolism, minimal toxicity and good bioavailability. Simulation studies upto 50 ns revealed the three leads ZINC000009219046, ZINC000025998119 and ZINC000004677901 bind with Ld -PriS throughout the simulation and there were no huge variations in their backbone suggesting that these three may play as potential lead compounds for developing new drug against leishmaniasis.Communicated by Ramaswamy H. Sarma.

Intracellular survival of Leishmania donovani demands rapid production of host ATP for its sustenance. However, a gradual decrease in intracellular ATP in spite of increased glycolysis suggests ATP efflux during infection. Accordingly, upon infection, we show here that ATP is exported and the major exporter was pannexin-1, leading to raised extracellular ATP levels. Extracellular ATP shows a gradual decrease after the initial increase, and analysis of cell surface ATP-degrading enzymes revealed induction of the ectonucleotidases CD39 and CD73. Ectonucleotidase-mediated ATP degradation leads to increased extracellular adenosine (eADO), and inhibition of CD39 and CD73 in infected cells decreased adenosine concentration and parasite survival, documenting the importance of adenosine in infection. Inhibiting adenosine uptake by cells did not affect parasite survival, suggesting that eADO exerts its effect through receptor-mediated signalling. We also show that Leishmania induces the expression of adenosine receptors A 2A R and A 2B R, both of which are important for anti-inflammatory responses. Treating infected BALB/c mice with CD39 and CD73 inhibitors resulted in decreased parasite burden and increased host-favourable cytokine production. Collectively, these observations indicate that infection-induced ATP is exported, and after conversion into adenosine, propagates infection via receptor-mediated signalling., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2020. Published by The Company of Biologists Ltd.)

Introduction: Leishmaniasis is a collective term used to describe various pathological conditions caused by an obligate intracellular protozoan of the genus Leishmania . It is one of the neglected diseases and has been given minimal attention by drug discovery and development stakeholders to narrow the safety and efficacy gaps of the drugs currently used to treat leishmaniasis. The challenge is further exacerbated by the emergence of drug resistance by the parasites., Methods: Aiming to look for potential anti-leishmanial hits and leads, we screened Medicines for Malaria Venture (MMV) Pathogen Box compounds against clinically isolated Leishmania donovani strain. In this medium-throughput primary screening assay, the compounds were screened against promastigotes, and then against amastigote stages., Results: From the total 400 compounds screened, 35 compounds showed >50% inhibitory activity on promastigotes in the initial screen (1 μM). Out of these compounds, nine showed >70% inhibition, with median inhibitory concentration (IC 50 ) ranging from 12 to 491 nM using the anti-promastigote assay, and from 53 to 704 nM using the intracellular amastigote assay. Identified compounds demonstrated acceptable safety profiles on THP-1 cell lines and sheep red blood cells, and had appropriate physicochemical properties suitable for further drug development. Two compounds (MMV690102 and MMV688262) were identified as leads. The anti-tubercular agent MMV688262 (delamanid) showed a synergistic effect with amphotericin B, indicating the prospect of using this compound for combination therapy., Conclusion: The current study indicates the presence of additional hits which may hold promise as starting points for anti-leishmanial drug discovery and in-depth structure-activity relationship studies., Competing Interests: The authors declare that they have no competing interests in this work., (© 2020 Tadele et al.)

Leishmaniasis is a neglected disease that affects 15 million people worldwide. Existing treatments are associated with limitations, including high costs and toxicity. Several classes of natural substances have been reported to display leishmanicidal activity in the literature. Isoquinoline alkaloids, which are commonly found in the Annonaceae family, represent an important skeleton for the development of anti-leishmaniasis products. This study presents an overview of the potential use of Annonaceae alkaloids to treat leishmaniasis and describes a molecular docking study examining 215 isoquinoline alkaloids. All selected compounds contain a bisbenzyltetrahydroisoquinoline, suggesting the affinity of this skeleton for the target., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Significant advances have been made in understanding the regulation of inflammasomes and its involvement in innate immunity during pathogenic infections. Inflammasome activation is a tightly regulated process that provides defense against pathogenic infection and important for inflammatory response. Very few studies on the involvement of NLRP3 inflammasome protein complex have been reported in leishmanial infections with contradictory results and without much mechanistic insights. However, the role of NLRP3 inflammasome and its components has not been well deciphered in Leishmania donovani infection. Here we report for the first time a detailed mechanism and plausible impairment of caspase 1 activation during L. donovani infection leading to the survival of these parasites inside the host cells. Low mRNA expression of pro-caspase 1 and lack of caspase 1 maturation were observed after infection, hindering the processing of pro-IL-1β and pro-IL-18 into their mature counter parts. Further, siRNA mediated knock-down of caspase 1 in macrophage cells (THP-1) resulted in significantly higher parasitic burden validating the importance of caspase 1 in the host defense mechanism. Taken together, our data suggests that the parasite inhibits caspase 1 activation to evade the inflammatory nature of pyroptosis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

High infection rates of Leishmania donovani and L. tropica were detected in Phlebotomus spp. sand flies collected from refugee camps in Greece, indicating increased risk of infection among local populations. Detection and treatment of leishmaniasis, community education, and vector control are essential measures to prevent pathogen transmission and protect public health.

We earlier found that F6 fraction of human filaria Brugia malayi cross-reacted with sera of Leishmania donovani infected hamsters and immunization with F6 inhibited both filarial and leishmanial infections. In the present study, we identified a 52.9-93.6 kDa fraction (Ld1) of L. donovani that cross-reacted with sera of B. malayi infected animals and investigated effect of Ld1 on filarial infection. Immunization of BALB/c mice with Ld1 facilitated B. malayi infection with remarkable increase in parasite burden. Facilitation of filarial infection was associated with downregulated cell proliferation, IL-5, IL-13, IFN-γ, TNF-α, and IL-2 levels and upregulated IL-4 and TGF-β. Ld1 exposure also suppressed MHC class-I, MHC class-II, and FcεR1 expression, and phagocytosis in naive mouse macrophages, and CD4+, CD8+, and CD19+ cell population in mouse spleen. Two-dimensional electrophoresis and matrix-assisted laser desorption ionization-time of flight-mass spectrometry revealed eight proteins in Ld1: putative heat shock protein (HSP) 70-related protein 1, HSP70 mitochondrial precursor, alanine aminotransferase, 2,3-bisphosphoglycerate-independent phosphoglycerate mutase, protein disulfide isomerase, putative ATPase beta subunit, trypanothione reductase, and a hypothetical protein. HSP70 protein mitochondrial precursor and trypanothione reductase showed homology with Trypanosoma cruzi and L. donovani, respectively, and the rest 6 proteins including hypothetical protein bear homology with L. infantum. In conclusion, the present study for the first time shows that immunization with filarial cross-reactive Ld1 fraction of L. donovani facilitates filarial infection by modulating Th1 and Th2 responses. Ld1 molecules may therefore facilitate filarial infection in filaria-leishmania co-infection.

Background: Immunmodulation combined with chemotherapy has emerged as an alternative to treat infections. The study evaluates immunomodulatory properties of a Leishmania recombinant protein (rA6) in activating macrophages and clearing intracellular parasites., Methods: The rA6 from a previously identified cDNA clone was analyzed for inducing the production of nitric oxide (NO) and reactive oxygen species (ROS) in macrophages, post and prior to infection with promastigotes by Griess method and flow cytometry. Phagocytosis and killing by treated macrophages was evaluated using Staphylococcus aureus as an index organism. Intracellular clearance of PKH67-labeled parasites from treated macrophages was assessed flowcytometrically. Combined effect of rA6 with miltefosine/AmBisome in reducing intracellular amastigotes was examined microscopically., Results: Treatment with rA6 post infection caused increased production of NO with increased number of macrophages producing NO and ROS coupled with enhanced phagocytic and killing capacity. Antigen stimulated macrophages expressed high level of iNOS and TNF-α mRNA. It synergized with miltefosine and AmBisome and facilitated early clearance of intracellular amastigotes at sub-optimal drug doses., Conclusion: The study demonstrates immunomodulatory potential of rA6 and presents first evidence on synergism between rA6 and anti-leishmanial drugs, thus placing it as a promising candidate for adjunct therapy., (© The Author 2016. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

As part of Drugs for Neglected Diseases initiative's lead optimization program for the development of new chemical entities to treat visceral leishmaniasis (VL), a series of aminothiazoles were synthesized and screened for in vitro efficacy, solubility and microsomal stability. The primary aim of identifying a lead structure with sub-micromolar activity was achieved. Out of 43 compounds synthesized, 16 compounds showed in vitro activity at less than 1 μM against VL. Compound 32 showed excellent antileishmanial potency (IC50 = 3 nM) and had all the acceptable properties except for metabolic instability. Blocking the metabolic soft spots in compound 32, where the 4-methoxy pyridine substituent was replaced by 5-ethoxy group, led to compound 36 (IC50 = 280 nM) with improved stability. To understand the disposition of 36, in vivo pharmacokinetic study was conducted in a mouse model. Compound 36 showed high clearance (91 mL/min/kg); short half-life (0.48 h) after intravenous administration (1 mg/kg) and exposure (AUC0-24) following oral administration was 362 ng h/mL with absolute bioavailability of 8%. To summarize, 43 analogs were synthesized out of which 15 compounds showed very potent sub-nanomolar efficacy in in vitro systems but the liability of metabolic instability seemed to be the major challenge for this chemical class and remains to be addressed., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

Intravital microscopy (IVM) is a powerful optical imaging technique that has made possible the visualization, monitoring and quantification of various biological events in real time and in live animals. This technology has greatly advanced our understanding of physiological processes and pathogen-mediated phenomena in specific organs. In this study, IVM is applied to the mouse liver and protocols are designed to image in vivo the circulatory system of the liver and measure red blood cell (RBC) velocity in individual hepatic vessels. To visualize the different vessel subtypes that characterize the hepatic organ and perform blood flow speed measurements, C57Bl/6 mice are intravenously injected with a fluorescent plasma reagent that labels the liver-associated vasculature. IVM enables in vivo, real time, measurement of RBC velocity in a specific vessel of interest. Establishing this methodology will make it possible to investigate liver hemodynamics under physiological and pathological conditions. Ultimately, this imaging-based methodology will be important for studying the influence of L. donovani infection on hepatic hemodynamics. This method can be applied to other infectious models and mouse organs and might be further extended to pre-clinical testing of a drug's effect on inflammation by quantifying its effect on blood flow.

The in vitro leishmanicidal activity of a series of imidazole-containing phthalazine derivatives 1-4 was tested on Leishmania infantum, Leishmania braziliensis and Leishmania donovani parasites, and their cytotoxicity on J774·2 macrophage cells was also measured. All compounds tested showed selectivity indexes higher than that of the reference drug glucantime for the three Leishmania species, and the less bulky monoalkylamino substituted derivatives 2 and 4 were clearly more effective than their bisalkylamino substituted counterparts 1 and 3. Both infection rate measures and ultrastructural alterations studies confirmed that 2 and 4 were highly leishmanicidal and induced extensive parasite cell damage. Modifications to the excretion products of parasites treated with 2 and 4 were also consistent with substantial cytoplasmic alterations. On the other hand, the most active compounds 2 and 4 were potent inhibitors of iron superoxide dismutase enzyme (Fe-SOD) in the three species considered, whereas their impact on human CuZn-SOD was low. Molecular modelling suggests that 2 and 4 could deactivate Fe-SOD due to a sterically favoured enhanced ability to interact with the H-bonding net that supports the antioxidant features of the enzyme.

Some novel heteroretinoid-bisbenzylidine ketone hybrids have been synthesized and evaluated for their in vitro antileishmanial activity against intramacrophagic amastigotes of Leishmania donovani. Among all the nine synthetic compounds, five compounds (7c, 7d and 7f-h) have shown significant (less than 7μM) activity against intramacrophagic amastigotes. The IC50 values of these compounds were found better than the reference drugs sodium stibogluconate (SSG) and miltefosine. This study helped us in identifying the new class of compounds that could be exploited as potent antileishmanial agents., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Introduction: Leishmaniasis imposes a substantial burden of mortality and morbidity affecting 12 million globally and continues to be a neglected tropical disease. Control of the disease is mainly based on chemotherapy, which relies on a handful of drugs with serious limitations. Over the last decade, target-based drug discovery is also being employed in addition to the random screening of compounds. Leishmanial dipeptidylcarboxypeptidase (LDCP), an angiotensin converting enzyme (ACE) related metallopeptidase, has been recently identified as a novel drug target for antileishmanial chemotherapy., Areas Covered: This article examines dipeptidylcarboxypeptidase (DCP) of Leishmania donovani and of other sources from the international literature regarding their biochemical and structural characterization in comparison to mammalian ACE. Furthermore, the author discusses the identification of LdDCP specific inhibitors by virtual screening and their effect on parasite multiplication. Finally, the review looks ahead at areas for further exploration of DCP inhibitors in Leishmania chemotherapy., Expert Opinion: The first step in targeted screening is to identify a suitable drug target and its validation followed by its use in high throughput screening of compounds. Limited studies on LDCP inhibitors have established a good correlation between parasite enzyme inhibition and their biological activity. This suggests that there is a potential for LDCP inhibitors as new antileishmanial drugs.

Clear and rational thinking: A series of rationally designed, lansine-derived carbazoles was synthesized and evaluated for activity against promastigotes and amastigotes of Leishmania donovani, the causative agent of leishmaniasis. Some structural modifications gave rise to compounds with enhanced activity and selectivity over lansine, allowing structure-activity relationships to be elucidated and providing a foundation for the further development of this pharmacophore., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The effect of infection by prototypes from the three major species of Leishmania on the oxidative burst of human mononuclear phagocytes in culture was examined. The presence of intracellular parasites of the three species, L.major, L.donovani and L.mexicana decreased hydrogen peroxide (H2O2) and superoxide anion (O2-) production. This was particularly apparent when infected cells were compared to control monocytes following treatment with IFN-gamma. Nitroblue tetrazolium (NBT) reduction by monocytes was also decreased in infected cells. This morphological analysis of infected monolayers clearly showed that infected monocytes were incapable of reducing the dye as compared to uninfected cells. Decrease in NBT positive cells and production of H2O2 and O2- was related to the degree of infection of the monocyte monolayers. These results suggest that the presence of intracellular Leishmania amastigotes in mononuclear phagocytes decreases the oxidative burst and may contribute to parasite survival. Failure of phagocytes from patients with chronic granulomatous disease to kill these intracellular parasites also emphasized the importance of the oxidative burst for this function. Nevertheless, the consistent increase in leishmaniacidal effect attained after IFN-gamma treatment of the monocyte monolayers indicates that other non-oxidative mechanisms induced by this cytokine are also important in the killing of these intracellular parasites.

A bibliographic-historical review of leishmaniasis in Spain during the period 1912-1985 is carried out. The bibliographical prospecting has allowed to collect a total of 402 works; out of them only 79 are included in this review. From reading them, it can be deduced that, starting from its discovery in the coast of Levante in 1912, leishmaniasis has been a very well known disease in Spain, during the first third of our century, period in which a remarkable prevalence took place, as it follows from the works published basically by Pittaluga and colleagues. In them, plentiful clinical and epidemiologic data are collected, many of them having laid the foundations of this disease knowledge in our country. Nevertheless, the extrapolation of data from other geographical regions introduced confusions, which have continued till recent time, basically on what refers to the existing relation between the aetiological agent and the clinical case. On the other hand, nowadays, current important matters such as the part of person's immune response in the appearance of a visceral or cutaneous case of leishmaniasis, independently from the parasites specific identity or the presence of asymptomatic leishmaniasis, are already found in pioneer works. In the course of the work, a review is made of the information, obtained form the Spanish bibliography, on the leishmaniasis aetiological agent in Spain, the vector and the host as well as the various clinical cases of human and canine leishmaniasis, their epidemiology, diagnostic and treatment.

Host preference of wild caught phlebotomine sandflies was studied in Marigat, Baringo District, Kenya, an endemic focus for both Leishmania donovani Laveran & Mensel and L. major Yakimov & Schokhov using precipitin test of blood meals. Sandflies of the Phlebotomus Rondani & Berte and Sergentomyia Franc & Parrot genera were encountered blood fed and resting in nine different habitats which were investigated. Analysis of their blood meals revealed a distinct host preference between the Phlebotomus and Sergentomyia genera. A distinction of host preference within species of each of the two genera was also observed. Furthermore, certain resting habitats from which the bloodfed sandflies were collected appeared to be favoured by specific sandfly species. It was observed that most of the wild hosts such as lizards and rodents except the hippopotamus, shared the same resting habitats with the sandflies. It was also observed that the man-biting sandflies preferred to rest outdoors after feeding. Domestic animals and man were the favoured hosts of vectors of both visceral and cutaneous leishmaniases, thus introducing an element of zooprophylaxis.

A survey of literature on modelling cutaneous leishmaniasis of man (common and metastatic) on some lines of mice, guinea pigs, golden hamsters infected with different species of Leishmania is given. Merits and demerits of each described model are pointed out.