Elucidating the role played by bone marrow in visceral leishmaniasis.

Leishmaniasis is a widespread group of infectious diseases that significantly impact global health. Despite high prevalence, leishmaniasis often receives inadequate attention in the prioritization of measures targeting tropical diseases. The causative agents of leishmaniasis are protozoan parasites of the Leishmania genus, which give rise to a diverse range of clinical manifestations, including cutaneous and visceral forms. Visceral leishmaniasis (VL), the most severe form, can be life-threatening if left untreated. Parasites can spread systemically within the body, infecting a range of organs, such as the liver, spleen, bone marrow and lymph nodes. Natural reservoirs for these protozoa include rodents, dogs, foxes, jackals, and wolves, with dogs serving as the primary urban reservoir for Leishmania infantum. Dogs exhibit clinical and pathological similarities to human VL and are valuable models for studying disease progression. Both human and canine VL provoke clinical symptoms, such as organ enlargement, fever, weight loss and abnormal gamma globulin levels. Hematologic abnormalities have also been observed, including anemia, leukopenia with lymphocytosis, neutropenia, and thrombocytopenia. Studies in dogs have linked these hematologic changes in peripheral blood to alterations in the bone marrow. Mouse models of VL have also contributed significantly to our understanding of the mechanisms underlying these hematologic and bone marrow abnormalities. This review consolidates information on hematological and immunological changes in the bone marrow of humans, dogs, and mice infected with Leishmania species causing VL. It includes findings on the role of bone marrow as a source of parasite persistence in internal organs and VL development. Highlighting gaps in current knowledge, the review emphasizes the need for future research to enhance our understanding of VL and identify potential targets for novel diagnostic and therapeutic approaches.

Cysteinyl-leukotrienes promote cutaneous Leishmaniasis control.

Leishmaniasis is a neglected tropical parasitic disease with few approved medications. Cutaneous leishmaniasis (CL) is the most frequent form, responsible for 0.7 - 1.0 million new cases annually worldwide. Leukotrienes are lipid mediators of inflammation produced in response to cell damage or infection. They are subdivided into leukotriene B4 (LTB4) and cysteinyl leukotrienes LTC4 and LTD4 (Cys-LTs), depending on the enzyme responsible for their production. Recently, we showed that LTB4 could be a target for purinergic signaling controlling Leishmania amazonensis infection; however, the importance of Cys-LTs in the resolution of infection remained unknown. Mice infected with L. amazonensis are a model of CL infection and drug screening. We found that Cys-LTs control L. amazonensis infection in susceptible (BALB/c) and resistant (C57BL/6) mouse strains. In vitro, Cys-LTs significantly diminished the L. amazonensis infection index in peritoneal macrophages of BALB/c and C57BL/6 mice. In vivo, intralesional treatment with Cys-LTs reduced the lesion size and parasite loads in the infected footpads of C57BL/6 mice. The anti-leishmanial role of Cys-LTs depended on the purinergic P2X7 receptor, as infected cells lacking the receptor did not produce Cys-LTs in response to ATP. These findings suggest the therapeutic potential of LTB4 and Cys-LTs for CL treatment.

Visceral leishmaniasis in a patient with systemic lupus erythematosus: Dilemma in diagnosis and management.

Patients with systemic lupus erythemasus (SLE) have an increased risk of bacterial, viral, fungal or parasitic infections, especially if they are receiving immunosuppressive therapy. Leishmaniasis is a group of diseases caused by intracellular flagellate protozoan parasites belonging to the genus Leishmania. We present a 48-year-old female patient, diagnosed with SLE many years ago, who presented with high fever and pancytopenia. We thought that the patient's hematologic findings were related to SLE hematologic involvement. However, we investigated other possible causes when there was no response to drugs for the treatment of SLE. A second bone marrow biopsy showed Leishmania amastigotes and the patient was diagnosed with leishmaniasis. The patient was treated with liposomal amphotericin-B (treatment completed at 40 days). She showed rapid clinical improvement and showed no signs of disease after 4 months.

Epigenetic paradigms/exemplars of the macrophage: inflammasome axis in Leishmaniasis.

The infectious paradigms have recently led to the recognition interplay of complex phenomenon underpinning disease diagnosis and prognosis. Evidently, parasitic infection studies are depicting converging trends of the epigenetic, environmental, and microbiome contributions, assisting pathogen-directed modulations of host biological system. The molecular details of epigenetic variations and memory, along with the multi-omics data at the interface of the host-pathogen level becomes strong indicator of immune cell plasticity, differentiation, and pathogen survival. Despite being one of the most important aspects of the disease's etiopathology, the epigenetic regulation of host-pathogen interactions and evolutionary epigenetics have received little attention thus far. Recent evidence has focused on the growing need to link epigenetic and microbiome modulations on parasite phenotypic plasticity and pathogen-induced host phenotypic plasticity for designing futuristic therapeutic regimes. Leishmaniasis is a neglected tropical illness with varying degrees of disease severity that is linked to a trans-species and epigenetic heredity process, including the pathogen-induced host and strain-specific modulations. The review configures research findings aligning to the epigenetic epidemiology niche, involving co-evolutionary epigenetic inheritance and plasticity disease models. The epigenetic exemplars focus on the host-pathogen interactome expanse at the macrophage-inflammasome axis.

Planejamento e desenvolvimento de novos compostos com atividade frente a Leishmania spp: Síntese, avaliação da atividade e toxicidade de derivados 5-nitro-2-furfurilidênicos e estudos de relações estrutura-atividade / Design of new compounds against Leishmania spp: synthesis, biological evaluation and toxicity of 5-nitro-2-furfurylidene derivates and structure-activity relationship studies

A leishmaniose é uma zoonose de ampla distribuição mundial, causada pelos parasitas tripanossomatídeos do gênero Leishmania. Infelizmente, o arsenal terapêutico disponível é precário, mas vê-se crescente o interesse científico pela busca do potencial de derivados nitroheterocíclicos como alternativas terapêuticas. Nesse contexto, este trabalho analisou o potencial de derivados 5-nitro-2-furfurilidênicos contra diferentes cepas de Leishmania, assim como investigou um possível modo de ação para esta classe de nitrocompostos. Para tal, a quimioteca foi sintetizada de acordo com publicações prévias do grupo. O potencial de inibição de crescimento das culturas de promastigotas de L. (L.) infantum (Linf) e L. (L.) major (Lmaj) foi determinado, utilizando miltefosina (MILT) (Linf - IC50: 8,28±0,33 µM), anfotericina B (AMB) (Linf - IC50: 0,02±0,002 µM) e nifurtimox (NFX) (Lmaj - IC50: 3,5±0,09 µM) como referência. A maioria dos compostos apresentaram maior potencial que as referênias, destacando o composto 40 (Linf - IC50: 0,2±0,019 µM/ Lmaj - IC50: 0,087 ± 0,001 µM) como mais eficaz. Contra as formas amastigotas intracelulares, para Linf os compostos 40, 13 e 15 foram mais eficazes em reduzir a carga parasitária dos macrófagos infectados que fármacos de referência. Para Lmajor, o composto 40 (IC50: 0,006 ± 0,0003 µM) foi mais ativo que o NFX (IC50: 2,15 ± 0,01 µM). Também foi determinada a atividade da quimioteca frente a enzima nitrorredutase (NTR1), utilizando cepas de T. brucei superexpressantes de NTR1, e os compostos analisados foram até 18 vezes mais eficazes que à cepa wild-type. Ademais, a partir da análise exploratória de dados por análise de componentes principais (PCA) e de grupamentos hierárquicos (HCA), foi reconhecida a influência das propriedades relacionadas com o equilíbrio hidrófilo-lipófilo e da natureza estérica/geométrica das moléculas para atividade anti-Leishmania

Leishmaniasis is a worldwide zoonosis caused by trypanosomatid parasites of the genus Leishmania. Unfortunately, the available therapeutic arsenal is precarious, but there is growing scientific interest in searching the potential of nitroheterocyclic derivatives as therapeutic alternatives. In this context, this work analyzed the potential of 5-nitro-2-furfurylidene derivatives against different Leishmania strains, as well as investigated the potential mode of action for this nitro compounds class. To this end, the chemolibrary was synthesized according to our group's previous publications. The growth inhibitory potential potential for promastigote cultures of L. (L.) infantum (Linf) and L. (L.) major (Lmaj) was determined using miltefosine (MILT) (Linf - IC50: 8.28±0.33 µM), amphotericin B (AMB) (Linf - IC50: 0.02±0.002 µM) and nifurtimox (NFX) (Lmaj - IC50: 3.5±0.09 µM) as reference. Most of the compounds were more potent than the references, highlighting compound 40 (Linf - IC50: 0.2±0.019 µM/ Lmaj - IC50: 0.087 ± 0.001 µM) as the most effective. Against intracellular amastigote, for Linf, compounds 40, 13 and 15 were more effective in reducing the parasite load of infected macrophages than reference drugs. For Lmajor, compound 40 (IC50: 0.006 ± 0.0003 µM) was more active than NFX (IC50: 2.15 ± 0.01 µM). The activity against nitroreductase (NTR1) enzyme was determined using overexpressing NTR1 mutant T. brucei strains, and the analyzed compounds were up to 18 times more effective than wild-type. Furthermore, exploratory data analysis using principal component analysis (PCA) and hierarchical clustering (HCA) methods were used. The influence of properties related to the hydrophiliclipophilic balance and the steric/geometric nature of the molecules was associated with the anti-Leishmanial activity

Activity of Anti-Microbial Peptides (AMPs) against Leishmania and Other Parasites: An Overview.

Anti-microbial peptides (AMPs), small biologically active molecules, produced by different organisms through their innate immune system, have become a considerable subject of interest in the request of novel therapeutics. Most of these peptides are cationic-amphipathic, exhibiting two main mechanisms of action, direct lysis and by modulating the immunity. The most commonly reported activity of AMPs is their anti-bacterial effects, although other effects, such as anti-fungal, anti-viral, and anti-parasitic, as well as anti-tumor mechanisms of action have also been described. Their anti-parasitic effect against leishmaniasis has been studied. Leishmaniasis is a neglected tropical disease. Currently among parasitic diseases, it is the second most threating illness after malaria. Clinical treatments, mainly antimonial derivatives, are related to drug resistance and some undesirable effects. Therefore, the development of new therapeutic agents has become a priority, and AMPs constitute a promising alternative. In this work, we describe the principal families of AMPs (melittin, cecropin, cathelicidin, defensin, magainin, temporin, dermaseptin, eumenitin, and histatin) exhibiting a potential anti-leishmanial activity, as well as their effectiveness against other microorganisms.

Case Report: Progressive Dysphonia and Dysphagia due to Laryngeal Leishmaniasis.

Laryngeal leishmaniasis is an unusual form of the disease. We report the case of a patient who consulted for dysphonia and dysphagia in a context of asthenia and weight loss. The patient had lesions that were suggestive of laryngeal cancer but were revealed to be leishmaniasis by histopathology examination and polymerase chain reaction. Treatment with amphotericin B and miltefosine permitted complete resolution of the lesions and no recurrence during the 18-month follow-up period.

Oxidant activated soluble adenylate cyclase of Leishmania donovani regulates the cAMP-PKA signaling axis for its intra-macrophage survival during infection.

Adenosine 3',5'-cyclic monophosphate (cAMP) is a stress sensor molecule that transduces the cellular signal when Leishmania donovani moves from insect vector to mammalian host. At this stage, the parasite membrane-bound receptor adenylate cyclase predominantly produces cAMP to cope with the oxidative assault imposed by host macrophages. However, the role of soluble adenylate cyclase of L. donovani (LdHemAC) has not been investigated fully. In the present investigation, we monitored an alternative pool of cAMP, maintained by LdHemAC. The elevated cAMP effectively transmits signals by binding to Protein Kinase A (PKA) present in the cytosol and regulates antioxidant gene expression and phosphorylates several unknown PKA substrate proteins. Menadione-catalyzed production of reactive oxygen species (ROS) mimics host oxidative condition in vitro in parasites where cAMP production and PKA activity were found increased by ~1.54 ± 0.35, and ~1.78 ± 0.47-fold, respectively while expression of LdHemAC gene elevated by ~2.18 ± 0.17-fold. The LdHemAC sense these oxidants and became activated to cyclize ATP to enhance the cAMP basal level that regulates antioxidant gene expression to rescue parasites from oxidative stress. In knockdown parasites (LdHemAC-KD), the downregulated antioxidant genes expression, namely, Sod (2.30 ± 0.46), Pxn (2.73 ± 0.15), Tdr (2.7 ± 0.12), and Gss (1.57 ± 0.15) results in decreased parasite viability while in overexpressed parasites (LdHemAC-OE), the expression was upregulated by ~5.7 ± 0.35, ~2.57 ± 0.56, ~4.7 ± 0.36, and ~2.4 ± 0.83, respectively, which possibly overcomes ROS accumulation and enhances viability. Furthermore, LdHemAC-OE higher PKA activity regulates phosphorylation of substrate proteins (~56 kDs in membrane fraction and ~25 kDs in the soluble fraction). It reduced significantly when treated with inhibitors like DDA, Rp-cAMP, and H-89 and increased by ~2.1 ± 0.28-fold, respectively under oxidative conditions. The LdHemAC-KD was found less infective to RAW 264.7 macrophages and more prone to oxidative damage as compared to LdHemAC-OE and control parasites. Together, this study demonstrates mechanistic links among LdHemAC, cAMP, and PKA in parasite survival and invasion under host oxidative condition.

Development of loop-mediated isothermal amplification (LAMP) assay using SYBR safe and gold-nanoparticle probe for detection of Leishmania in HIV patients.

Asymptomatic leishmaniasis cases have continuously increased, especially among patients with HIV who are at risk to develop further symptoms of cutaneous and visceral leishmaniasis. Thus, early diagnosis using a simple, sensitive and reliable diagnostic assay is important because populations at risk mostly reside in rural communities where laboratory equipment is limited. In this study, the highly sensitive and selective determination of Leishmania infection in asymptomatic HIV patients was achieved using dual indicators (SYBR safe and gold-nanoparticle probe; AuNP-probe) in one-step LAMP method based on basic instruments. The assay can be simply evaluated under the naked eye due to clear interpretation of fluorescent emission of LAMP-SYBR safe dye-complex and colorimetric precipitate of specific AuNP-probes. The sensitivities and specificities of fluorescent SYBR safe dye and AuNP-probe indicators were equal, which were as high as 94.1 and 97.1%, respectively. Additionally, detection limits were 102 parasites/mL (0.0147 ng/µL), ten times more sensitivity than other related studies. To empower leishmaniasis surveillance, this inexpensive one-step SYBR safe and AuNP-LAMP assay is reliably fast and simple for field diagnostics to point-of-care settings, which can be set up in all levels of health care facilities including resource limited areas, especially in low to middle income countries.

Clustering of adenosine A2B receptors with ectonucleotidases in caveolin-rich lipid rafts underlies immunomodulation by Leishmania amazonensis.

Extracellular adenosine plays important roles in modulating the immune responses. We have previously demonstrated that infection of dendritic cells (DC) by Leishmania amazonensis leads to increased expression of CD39 and CD73 and to the selective activation of the low affinity A2B receptors (A2B R), which contributes to DC inhibition, without involvement of the high affinity A2A R. To understand this apparent paradox, we now characterized the alterations of both adenosine receptors in infected cells. With this aim, bone marrow-derived DC from C57BL/6J mice were infected with metacyclic promastigotes of L. amazonensis. Fluorescence microscopy revealed that L. amazonensis infection stimulates the recruitment of A2B R, but not of A2A R, to the surface of infected DC, without altering the amount of mRNA or the total A2B R density, an effect dependent on lipophosphoglycan (LPG). Log-phase promastigotes or axenic amastigotes of L. amazonensis do not stimulate A2B R recruitment. A2B R clusters are localized in caveolin-rich lipid rafts and the disruption of these membrane domains impairs A2B R recruitment and activation. More importantly, our results show that A2B R co-localize with CD39 and CD73 forming a "purinergic cluster" that allows for the production of extracellular adenosine in close proximity with these receptors. We conclude that A2B R activation by locally produced adenosine constitutes an elegant and powerful evasion mechanism used by L. amazonensis to down-modulate the DC activation.

An Elite Scaffold and a Wonderful Pharmacophore in Drug Discovery: Styrylquinoline.

Styrylquinoline is a quinoline molecule linked to phenyl rings with an unsaturated ethylene linker, resulting in a flat and rigid conformation. The synthesis of the molecule was reported almost a century ago but was not much explored due to its adverse toxicity and poor selectivity. In the last two decades, a plethora of work was reported related to the synthesis and antiretroviral activity of several styrylquinoline derivatives. Later, other activities such as antimicrobial and anticancer abilities of these derivatives were also reported. In this review, we summarize the diverse steps of the development and analyze the spectrum of the activity of styrylquinolines and their utilization in drug design. Styrylquinolines are extensively explored for new pharmacological activities in recent years and this makes the moiety gain more visibility as a potential drug candidate and lead molecule in medicinal chemistry. The data obtained in vitro and ex vivo shed light on their different mechanism of action. Styrylquinoline has proved to be a potential lead molecule in medicinal chemist's toolkit due to the exploration of a variety of avenues of its activity as a drug candidate.

Nanostructured lipid carrier containing hydroxymethylnitrofurazone: preparation, characterization and in vitro and in vivo evaluation of leishmanicidal activity / Carreador lipídico nanoestruturado contendo hidroximetilnitrofural: preparação, caracterização físico-química e avaliação in vitro e in vivo da atividade leishmanicida

Leishmaniasis, a neglected tropical disease (NTD), is a set of diseases caused by obligatory parasitic protozoa of the genus Leishmania. And it has cutaneous and visceral eishmaniasis as its main forms. Treatment includes pentavalent antimonials. These drugs have several disadvantages, such as the need for parenteral administration, use of high dosages, long duration of treatment, severe toxicity, resistance and variable efficacy. The candidate for hydroxymethylnitrofural drug (NFOH), a prodrug derived from nitrofural, showed high activity in cell cultures infected with Trypanosoma cruzi and less toxicity when compared to nitrofural. Due to its low solubility in water and reduced bioavailability, NFOH has failed the in vivo efficacy tests. Nanostructured drug delivery systems have the potential to overcome these challenges due to their evident advantages: greater therapeutic efficacy, less toxicity, modified drug release and increased gastrointestinal absorption of drugs with low water solubility. The objective of this project will be the preparation and evaluation of the physicochemical characteristics of a nanostructured lipid carrier containing hydroxymethylnitrofural (NLC-NFOH). The NFOH showed the highest solubility in Miglyol® 840 among the tested liquid lipids. For solid lipids, Gelucire® 50/13 and Precirol® ATO5 proved to be more suitable for the solubilization of NFOH. The optimized NLC-NFOH consisted of these three lipids. These lipids were selected using a quick Technobis Crystal 16TM methodology, microscopy and DSC. Different lipid selection tools provided scientific knowledge relevant to the development of NLC. The NLC-NFOH had an average z of 198.6 ± 5.4 nm, a PDI of 0.11 ± 0.01 and a zeta potential of -13.7 ± 0.7 mV. This study allowed a design space development approach of the first NLC-NFOH with the potential to treat leishmaniasis orally. The development of a sensitive bioanalytical method using HPLC and evaluation of some analytical figures of merit for the validation allowed the quantification of NFOH and NF. The bioanalytical method for analysis of NFOH and NF use Zorbax SB-C18, 5µm, (4.6x250mm) HPLC column. The mobile phase was consisted of acetonitrile:water (20:80 v/v) with flow rate of 1.2 ml/min, at UV detection of 370 nm. The linearity of NFOH and NF was found in the range 0.0253.0 µg/ml with a correlation coefficient of r > 0.98. The precision was 2.44 to 13.77% for NFOH and 2.61 to 18.42%; the accuracy was 2.66 to 14.28% for NFOH and 2.09 to 19.06% for NF. The method showed to be suitable for effectively evaluation of NFOH is serum. NLC-NFOH (2.8 mg/kg) was administered to animals by gavage, and the blocking flow of the chylomicrons model was performed with an intraperitoneal injection of cycloheximide. The presence of NFOH in serum was evaluated with and without cycloheximide. The cytotoxicity assay of NLC-NFOH and blank-NLC showed more than 90% viable cells at the maximum concentration used (2560 µM). NFOH and NF were detected at 1h after the gavage of DMSO-NFOH or NLC-NFOH, without the pretreatment with cycloheximide. The concentration found for DMSO-NFOH and NLC-NFOH were 0.0316 and 0.0291 µg/mL, respectively. The NLC presented the NFOH absorption by the lymphatic system, demonstrated by blocking chylomicrons flow

A leishmaniose, uma doença tropical negligenciada (DTN), é um conjunto de doenças causadas por protozoários parasitas obrigatórios do gênero Leishmania. E tem como formas principais a leishmaniose cutânea e visceral. O tratamento inclui antimoniais pentavalentes. Esses fármacos apresentam várias desvantagens, como necessidade de administração parenteral, uso de altas dosagens, longa duração do tratamento, toxicidade grave, resistência e eficácia variável. O candidato ao fármaco hidroximetilnitrofural (NFOH), um pró-fármaco derivado do nitrofural, apresentou alta atividade em culturas de células infectadas pelo Trypanosoma cruzi e menor toxicidade quando comparado ao nitrofural. Devido à sua baixa solubilidade em água e biodisponibilidade reduzida, o NFOH falhou nos testes de eficácia in vivo. Os sistemas nanoestruturados de liberação de fármacos têm potencial para superar esses desafios devido às suas vantagens evidentes: maior eficácia terapêutica, menor toxicidade, liberação modificada do fármaco e aumento da absorção gastrointestinal de fármacos com baixa solubilidade em água. O objetivo deste projeto será a preparação e avaliação das características físico-químicas de um carreador lipídico nanoestruturado contendo hidroximetilnitrofural (NLC-NFOH). O NFOH apresentou a maior solubilidade no Miglyol® 840 entre os lipídios líquidos testados. Para lipídios sólidos, Gelucire® 50/13 e Precirol® ATO5 se mostraram mais adequados para a solubilização de NFOH. O NLC-NFOH otimizado consistiu desses três lipídios. Esses lipídios foram selecionados usando Technobis Crystal 16TM, microscopia e DSC. Diferentes ferramentas de seleção de lipídios forneceram conhecimento científico relevante para o desenvolvimento de NLC. O NLC-NFOH teve z-average de 198,6 ± 5,4 nm, PDI de 0,11 ± 0,01 e potencial zeta de -13,7 ± 0,7 mV. Este estudo permitiu o desenvolvimento por abordagem de Design Space do primeiro NLC-NFOH com potencial para tratar a leishmaniose por via oral. O desenvolvimento de um VIII método bioanalítico sensível utilizando HPLC e a avaliação de algumas figuras analíticas de mérito para a validação permitiram a quantificação de NFOH e NF em soro. O método bioanalítico para análise de NFOH e NF usou coluna de HPLC Zorbax SB-C18, 5 µm, (4,6 x 250 mm). A fase móvel foi constituída por acetonitrila: água (20:80 v / v) com vazão de 1,2 ml / min, com detecção no UV de 370 nm. A linearidade de NFOH e NF foi encontrada na faixa de 0,0253,0 µg / ml com um coeficiente de correlação de r> 0,98. A precisão foi de 2,44 a 13,77% para NFOH e 2,61 a 18,42%; a precisão foi de 2,66 a 14,28% para NFOH e 2,09 a 19,06% para NF. O método mostrou-se adequado para avaliação efetiva do NFOH no soro. NLC-NFOH (2,8 mg / kg) foi administrado aos animais por gavagem, e o modelo de bloqueio do fluxo de quilomícrons foi realizado com injeção intraperitoneal de cicloheximida. A presença de NFOH no soro foi avaliada com e sem cicloheximida. O ensaio de citotoxicidade de NLC-NFOH e brancoNLC mostrou mais de 90% de células viáveis na concentração máxima utilizada (2560 µM). NFOH e NF foram detectados 1h após a gavagem de DMSO-NFOH ou NLC-NFOH, sem o pré-tratamento com cicloheximida. As concentrações encontradas para DMSO-NFOH e NLC-NFOH foram 0,0316 e 0,0291 µg / mL, respectivamente. O NLC apresentou a absorção do NFOH pelo sistema linfático, demonstrada pelo bloqueio do fluxo dos quilomícrons

Leishmania differentiation requires ubiquitin conjugation mediated by a UBC2-UEV1 E2 complex.

Post-translational modifications such as ubiquitination are important for orchestrating the cellular transformations that occur as the Leishmania parasite differentiates between its main morphological forms, the promastigote and amastigote. 2 E1 ubiquitin-activating (E1), 13 E2 ubiquitin-conjugating (E2), 79 E3 ubiquitin ligase (E3) and 20 deubiquitinating cysteine peptidase (DUB) genes can be identified in the Leishmania mexicana genome but, currently, little is known about the role of E1, E2 and E3 enzymes in this parasite. Bar-seq analysis of 23 E1, E2 and HECT/RBR E3 null mutants generated in promastigotes using CRISPR-Cas9 revealed numerous loss-of-fitness phenotypes in promastigote to amastigote differentiation and mammalian infection. The E2s UBC1/CDC34, UBC2 and UEV1 and the HECT E3 ligase HECT2 are required for the successful transformation from promastigote to amastigote and UBA1b, UBC9, UBC14, HECT7 and HECT11 are required for normal proliferation during mouse infection. Of all ubiquitination enzyme null mutants examined in the screen, Δubc2 and Δuev1 exhibited the most extreme loss-of-fitness during differentiation. Null mutants could not be generated for the E1 UBA1a or the E2s UBC3, UBC7, UBC12 and UBC13, suggesting these genes are essential in promastigotes. X-ray crystal structure analysis of UBC2 and UEV1, orthologues of human UBE2N and UBE2V1/UBE2V2 respectively, reveal a heterodimer with a highly conserved structure and interface. Furthermore, recombinant L. mexicana UBA1a can load ubiquitin onto UBC2, allowing UBC2-UEV1 to form K63-linked di-ubiquitin chains in vitro. Notably, UBC2 can cooperate in vitro with human E3s RNF8 and BIRC2 to form non-K63-linked polyubiquitin chains, showing that UBC2 can facilitate ubiquitination independent of UEV1, but association of UBC2 with UEV1 inhibits this ability. Our study demonstrates the dual essentiality of UBC2 and UEV1 in the differentiation and intracellular survival of L. mexicana and shows that the interaction between these two proteins is crucial for regulation of their ubiquitination activity and function.

Effects of extracellular vesicles released by peritoneal B-1 cells on experimental Leishmania (Leishmania) amazonensis infection.

B-1 cells are a B-lymphocyte subtype whose roles in immunity are not completely defined. These cells can produce cytokines (mainly IL-10) and natural and specific antibodies. Currently, extracellular vesicles (EVs) released by immune cells have emerged as new important entities in cell-cell communication. Immune cells release EVs that can activate and/or modulate other immune cells. Here, we characterized the EVs released by peritoneal B-1 cells infected or not with Leishmania (Leishmania) amazonensis. This Leishmania species causes cutaneous leishmaniasis and can infect macrophages and B-1 cells. Our results showed that peritoneal B-1 cells spontaneously release EVs, but the parasite stimulated an increase in EVs production by peritoneal B-1 cells. The treatment of BALB/c and C57BL/6 bone marrow-derived macrophages (BMDM) with EVs from infected peritoneal B-1 cells led to differential expression of iNOS, IL-6, IL-10, and TNF-α. Additionally, BALB/c mice previous treated with EVs released by peritoneal B-1 cells showed a significant lower lesion size and parasite burden. Thus, this study demonstrated that peritoneal B-1 cells could release EVs that can alter the functions of macrophages in vitro and in vivo these EVs altered the course of L. amazonensis infection. These findings represent the first evidence that EVs from peritoneal B-1 cells can act as a new mechanism of cellular communication between macrophages and B-1 cells, contributing to immunity against experimental leishmaniasis.

Lipophosphoglycan-3 recombinant protein vaccine controls hepatic parasitism and prevents tissue damage in mice infected by Leishmania infantum chagasi.

AIMS: In this work, we aimed to evaluate the effects of the Leishmania infantum chagasi infection on the liver of vaccinated mice, considering parameters of tissue damage and the inflammatory response elicited by vaccination. MAIN METHODS: We used recombinant LPG3 protein (rLPG3) as immunogen in BALB/c mice before challenge with promastigote forms of L. infantum chagasi. The animals were separated into five groups: NI: non-infected animals; NV: non-vaccinated; SAP: treated with saponin; rLPG3: immunized with rLPG3; rLPG3 + SAP: immunized with rLPG3 plus SAP. The experiment was conducted in replicate, and the vaccination protocol consisted of three subcutaneous doses of rLPG3 (40 µg + two boosters of 20 µg). The mice were challenged two weeks after the last immunization. KEY FINDINGS: Our results showed that rLPG3 + SAP immunization decreased the parasite burden in 99 %, conferring immunological protection in the liver of the infected animals. Moreover, the immunization improved the antioxidant defenses, increasing CAT and GST activity, while reducing the levels of oxidative stress markers, such as H2O2 and NO3/NO2, and carbonyl protein in the organ. As a consequence, rLPG3 + SAP immunization preserved tissue integrity and reduced the granuloma formation, inflammatory infiltrate and serum levels of AST, ALT, and ALP. SIGNIFICANCE: Taken together, these results showed that rLPG3 vaccine confers liver protection against L. infantum chagasi in mice, while maintaining the liver tissue protected against the harmful inflammatory effects caused by the vaccine followed by the infection.

First description of parasite load and clinicopathological and anatomopathological changes in a dog naturally coinfected with Dioctophyme renale and Leishmania infantum in Brazil.

This article reports the case of a domestic dog naturally coinfected with the nematode Dioctophyme renale and with the protozoan Leishmania infantum. The dog exhibited no clinical signs but had normocytic hypochromic anemia, hyperproteinemia, hyperglobulinemia, hypoalbuminemia, and hematuria. Necropsy revealed eight D. renale specimens in the abdominal cavity and in right kidney whose parenchyma was atrophied. Histopathological analysis showed glomerular atrophy, fibrosis and a marked diffuse pyogranulomatous inflammatory infiltrate in the right kidney. Moderate multifocal granulomatous peritonitis was observed in the greater omentum. Several Dioctophyme renale eggs were present amidst the inflammatory infiltrate of the right kidney and greater omentum. Leishmania infantum parasites were detected in perirenal adipose tissue of the right kidney, greater omentum, spleen, bone marrow, and popliteal lymph node. The high D. renale load and the severe and uncommon histological alterations associated with the eggs of this parasite may have been influenced by coinfection with L. infantum.

Leishmaniasis and tumor necrosis factor alpha antagonists in the Mediterranean basin. A switch in clinical expression.

BACKGROUND: Tumor necrosis factor alpha (TNF-α) blockers are recognized as a risk factor for reactivation of granulomatous infections. Leishmaniasis has been associated with the use of these drugs, although few cases have been reported. METHODOLOGY: We performed a retrospective observational study including patients with confirmed leishmaniasis acquired in the Mediterranean basin that were under TNF-α blockers therapy at the moment of the diagnosis. Patients diagnosed in our hospital from 2008 to 2018 were included. Moreover, a systematic review of the literature was performed and cases fulfilling the inclusion criteria were also included. PRINCIPAL FINDINGS: Forty-nine patients were analyzed including nine cases from our series. Twenty-seven (55.1%) cases were male and median age was 55 years. Twenty-five (51%) patients were under infliximab treatment, 20 (40.8%) were receiving adalimumab, 2 (4.1%) etanercept, one (2%) golimumab and one (2%) a non-specified TNF-α blocker. Regarding clinical presentation, 28 (57.1%) presented as cutaneous leishmaniasis (CL), 16 (32.6%) as visceral leishmaniasis (VL) and 5 (10.2%) as mucocutaneous leishmaniasis (MCL). All VL and MCL patients were treated with systemic therapies. Among CL patients, 13 (46.4%) were treated with a systemic drug (11 received L-AmB, one intramuscular antimonials and one miltefosine) while 14 (50%) patients were given local treatment (13 received intralesional pentavalent antimonials, and one excisional surgery). TNF-α blockers were interrupted in 32 patients (65.3%). After treatment 5 patients (10.2%) relapsed. Four patients with a CL (3 initially treated with local therapy maintaining TNF-α blockers and one treated with miltefosine) and one patient with VL treated with L-AmB maintaining TNF-α blockers. CONCLUSIONS: This data supports the assumption that the blockage of TNF-α modifies clinical expression of leishmaniasis in endemic population modulating the expression of the disease leading to atypical presentations. According to the cases reported, the best treatment strategy would be a systemic drug and the discontinuation of the TNF-α blockers therapy until clinical resolution.