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.

Unfolded protein response pathway in leishmaniasis: A review.

Alteration in the physiological state of the endoplasmic reticulum (ER) leads to the specific response known as unfolded protein response (UPR) or ER stress response. The UPR is driven by three sensor proteins, namely: Inositol-Requiring Enzyme 1, Protein Kinase RNA-like ER kinase and Activating Transcription Factor 6 to restore ER homeostasis. Pathogenic infection can initiate UPR activation; some pathogens can subvert the UPR to promote their survival and replication. Many intracellular pathogens, including Leishmania, can interact and hijack ER for their survival and replication, triggering ER stress and subsequently ER stress response. This review aims to provide a comprehensive overview of the ER stress response in infections with the Leishmania species.

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.

Temporary Shutdown of ERK1/2 Phosphorylation Is Associated With Activation of Adaptive Immune Cell Responses and Disease Progression During Leishmania amazonensis Infection in BALB/c Mice.

Leishmania spp. infection outcomes are dependent on both host and parasite factors. Manipulation of host signaling pathways involved in the generation of immune responses is thought to be one of the most common mechanisms used by parasites for persistence within the host. Considering the diversity of pathologies caused by different Leishmania spp., it is plausible that significant differences may exist in the mechanisms of host cell manipulation by each parasite species, which may have implications when developing new vaccine or treatment strategies. Here we show that in L. braziliensis-infection in BALB/c mice, a model of resistance, activation of ERK1/2 coincides with the peak of inflammatory responses and resolution of tissue parasitism. In contrast, in the susceptibility model of L. amazonensis-infection, an early silent phase of infection is observed, detected solely by quantification of parasite loads. At this early stage, only basal levels of P-ERK1/2 are observed. Later, after a brief shutdown of ERK1/2 phosphorylation, disease progression is observed and is associated with increased inflammation, lesion size and tissue parasitism. Moreover, the short-term down-regulation of ERK1/2 activation affected significantly downstream inflammatory pathways and adaptive T cell responses. Administration of U0126, a MEK/ERK inhibitor, confirmed this phenomenon, since bigger lesions and higher parasite loads were seen in infected mice that received U0126. To investigate how kinetics of ERK1/2 activation could affect the disease progression, U0126 was administered to L. amazonensis-infected animals earlier than the P-ERK1/2 switch off time-point. This intervention resulted in anticipation of the same effects on inflammatory responses and susceptibility phenotype seen in the natural course of infection. Additionally, in vitro inhibition of ERK1/2 affected the phagocytosis of L. amazonensis by BMDMs. Collectively, our findings reveal distinct temporal patterns of activation of inflammatory responses in L. braziliensis and L. amazonensis in the same animal background and a pivotal role for a brief and specific shutdown of ERK1/2 activation at late stages of L. amazonensis infection. Since activation of inflammatory responses is a crucial aspect for the control of infectious processes, these findings may be important for the search of new and specific strategies of vaccines and treatment for tegumentary leishmaniasis.

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

Morphological alterations of Thymus during the early murine leishmaniasis.

Leishmaniasis is a neglected and endemic disease that affects poorest population mainly in developing countries. Thymus provides an essential complex environment for T cell maturation and differentiation during leishmania infection. The aim of this study was to investigate the pathological alterations of the Thymus during early Leishmania amazonensis murine infection. BALB/c mice were infected with 105 amastigotes for 24 h, 3 days, 7 days, 15 days or 30 days. At different times of infection, the relative weight of the Thymus was obtained, and the Thymus cellularity was determined by counting total cells of one thymic lobe. The thymic lobe was, alternatively, processed for standard Haematoxylin and Eosin protocol. Our results suggest thymic alteration during the early days of BALB/c mice infection with L. amazonensis. The thymic hypertrophy was accompanied by histological alterations in Thymus architecture with thickening cortex at 3 days p.i. and loss of an evident delimitation between the cortex and medulla at 7 days p.i. when compared to the control mice. That is the first time that Thymus hypertrophy was observed during the early leishmaniasis. However, how it may contribute to infection susceptibility requires further investigation.

A New Target Organ of Leishmania (Viannia) braziliensis Chronic Infection: The Intestine.

Leishmania (Viannia) braziliensis is one of the main causes of cutaneous leishmaniasis in the Americas. This species presents genetic polymorphism that can cause destructive lesions in oral, nasal, and oropharyngeal tracts. In a previous study, the parasite caused several histopathological changes to hamster ileums. Our study evaluates immune response components, morphological changes, and effects on neurons in the ileums of hamsters infected by three different strains of L. (V.) braziliensis in two infection periods. For the experiment, we separated hamsters into four groups: a control group and three infected groups. Infected hamsters were euthanized 90- or 120-days post infection. We used three strains of L. (V.) braziliensis: the reference MHOM/BR/1975/M2903 and two strains isolated from patients who had different responses to Glucantime® treatment (MHOM/BR/2003/2314 and MHOM/BR/2000/1655). After laparotomy, ileums were collected for histological processing, biochemical analysis, and evaluation of neurons in the myenteric and submucosal plexuses of the enteric nervous system (ENS). The results demonstrated the increase of blood leukocytes after the infection. Optical microscopy analysis showed histopathological changes with inflammatory infiltrates, edemas, ganglionitis, and Leishmania amastigotes in the ileums of infected hamsters. We observed changes in the organ histoarchitecture of infected hamsters when compared to control groups, such as thicker muscular and submucosa layers, deeper and wider crypts, and taller and broader villi. The number of intraepithelial lymphocytes and TGF-ß-immunoreactive cells increased in all infected groups when compared to the control groups. Mast cells increased with longer infection periods. The infection also caused remodeling of intestinal collagen and morphometry of myenteric and submucosal plexus neurons; but this effect was dependent on infection duration. Our results show that L. (V.) braziliensis infection caused time-dependent alterations in hamster ileums. This was demonstrated by the reduction of inflammatory cells and the increase of tissue regeneration factors at 120 days of infection. The infected groups demonstrated different profiles in organ histoarchitecture, migration of immune cells, and morphometry of ENS neurons. These findings suggest that the small intestine (or at least the ileum) is a target organ for L. (V.) braziliensis infection, as the infection caused changes that were dependent on duration and strain.

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.

Acute kidney injury in patients with Visceral Leishmaniasis in Northwest Ethiopia.

BACKGROUND: Visceral Leishmaniasis (VL) is a neglected tropical disease endemic to several countries including Ethiopia. Outside of Africa, kidney involvement in VL is frequent and associated with increased mortality. There is however limited data on acute kidney injury (AKI) in VL patients in East-Africa, particularly in areas with high rates of HIV co-infection. This study aims to determine the prevalence, characteristics and associated factors of AKI in VL patients in Northwest Ethiopia. METHODS: A hospital based retrospective patient record analysis was conducted including patients treated for VL from January 2019 to December 2019 at the Leishmaniasis Research and Treatment Center (LRTC), Gondar, Ethiopia. Patients that were enrolled in ongoing clinical trials at the study site and those with significant incomplete data were excluded. Data was analyzed using SPSS version 20. P values were considered significant if < 0.05. RESULTS: Among 352 VL patients treated at LRTC during the study period, 298 were included in the study. All were male patients except two; the median age was 23 years (IQR: 20-27). The overall prevalence of AKI among VL patients was 17.4% (confidence interval (CI): 13.6%-22.2%). Pre-renal azotemia (57%) and drug-induced AKI (50%) were the main etiologies of AKI at admission and post-admission respectively. Proteinuria and hematuria occurred in 85% and 42% of AKI patients respectively. Multivariate logistic regression revealed HIV co-infection (adjusted odds ratio (AOR): 6.01 95% CI: 1.99-18.27, p = 0.001) and other concomitant infections (AOR: 3.44 95% CI: 1.37-8.65, p = 0.009) to be independently associated with AKI. CONCLUSION: AKI is a frequent complication in Ethiopian VL patients. Other renal manifestations included proteinuria, hematuria, and pyuria. HIV co-infection and other concomitant infections were significantly associated with AKI. Further studies are needed to quantify proteinuria and evaluate the influence of AKI on the treatment course, morbidity and mortality in VL patients.

Peculiarities of aminoacyl-tRNA synthetases from trypanosomatids.

Trypanosomatid parasites are responsible for various human diseases, such as sleeping sickness, animal trypanosomiasis, or cutaneous and visceral leishmaniases. The few available drugs to fight related parasitic infections are often toxic and present poor efficiency and specificity, and thus, finding new molecular targets is imperative. Aminoacyl-tRNA synthetases (aaRSs) are essential components of the translational machinery as they catalyze the specific attachment of an amino acid onto cognate tRNA(s). In trypanosomatids, one gene encodes both cytosolic- and mitochondrial-targeted aaRSs, with only three exceptions. We identify here a unique specific feature of aaRSs from trypanosomatids, which is that most of them harbor distinct insertion and/or extension sequences. Among the 26 identified aaRSs in the trypanosome Leishmania tarentolae, 14 contain an additional domain or a terminal extension, confirmed in mature mRNAs by direct cDNA nanopore sequencing. Moreover, these RNA-Seq data led us to address the question of aaRS dual localization and to determine splice-site locations and the 5'-UTR lengths for each mature aaRS-encoding mRNA. Altogether, our results provided evidence for at least one specific mechanism responsible for mitochondrial addressing of some L. tarentolae aaRSs. We propose that these newly identified features of trypanosomatid aaRSs could be developed as relevant drug targets to combat the diseases caused by these parasites.

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.

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.

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.

Systematic functional analysis of Leishmania protein kinases identifies regulators of differentiation or survival.

Differentiation between distinct stages is fundamental for the life cycle of intracellular protozoan parasites and for transmission between hosts, requiring stringent spatial and temporal regulation. Here, we apply kinome-wide gene deletion and gene tagging in Leishmania mexicana promastigotes to define protein kinases with life cycle transition roles. Whilst 162 are dispensable, 44 protein kinase genes are refractory to deletion in promastigotes and are likely core genes required for parasite replication. Phenotyping of pooled gene deletion mutants using bar-seq and projection pursuit clustering reveal functional phenotypic groups of protein kinases involved in differentiation from metacyclic promastigote to amastigote, growth and survival in macrophages and mice, colonisation of the sand fly and motility. This unbiased interrogation of protein kinase function in Leishmania allows targeted investigation of organelle-associated signalling pathways required for successful intracellular parasitism.

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.