New World cutaneous leishmaniasis: updated review of current and future diagnosis and treatment

Artificial Intelligence in Cutaneous Leishmaniasis Diagnosis: Current Developments and Future Perspectives

Cutaneous Leishmaniasis (CL) is a major global health problem requiring appropriate diagnosis methods. Its diagnosis is challenging, particularly in resource-limited settings. The integration of Artificial Intelligence (AI) into medical diagnostics has shown promising results in various fields, including dermatology. In this systematic review, we aim to highlight the value of using AI for CL diagnosis and the AI-based algorithms that are employed in this process, and to identify gaps that need to be addressed. Our work highlights that only a limited number of studies are related to using AI algorithms for CL diagnosis. Among these studies, seven gaps were identified for future research. Addressing these considerations will pave the way for the development of robust AI systems and encourage more research in CL detection by AI. This could contribute to improving CL diagnosis and, ultimately, healthcare outcomes in CL-endemic regions.

Automated Identification of Cutaneous Leishmaniasis Lesions Using Deep-Learning-Based Artificial Intelligence

The polymorphism of cutaneous leishmaniasis (CL) complicates diagnosis in health care services because lesions may be confused with other dermatoses such as sporotrichosis, paracocidiocomycosis, and venous insufficiency. Automated identification of skin diseases based on deep learning (DL) has been applied to assist diagnosis. In this study, we evaluated the performance of AlexNet, a DL algorithm, to identify pictures of CL lesions in patients from Midwest Brazil. We used a set of 2458 pictures (up to 10 of each lesion) obtained from patients treated between 2015 and 2022 in the Leishmaniasis Clinic at the University Hospital of Brasilia. We divided the picture database into training (80%), internal validation (10%), and testing sets (10%), and trained and tested AlexNet to identify pictures of CL lesions. We performed three simulations and trained AlexNet to differentiate CL from 26 other dermatoses (e.g., chromomycosis, ecthyma, venous insufficiency). We obtained an average accuracy of 95.04% (Confidence Interval 95%: 93.81-96.04), indicating an excellent performance of AlexNet in identifying pictures of CL lesions. We conclude that automated CL identification using AlexNet has the potential to assist clinicians in diagnosing skin lesions. These results contribute to the development of a mobile application to assist in the diagnosis of CL in health care services.

Microgramma vacciniifolia Frond Lectin: In Vitro Anti-leishmanial Activity and Immunomodulatory Effects Against Internalized Amastigote Forms of Leishmania amazonensis

PURPOSE

The treatment of leishmaniasis, an anthropozoonosis caused by Leishmania protozoa, is limited by factors, such as adverse effects, toxicity, and excessive cost, which has highlighted the importance of novel drugs. In this context, natural products have been considered as sources of antileishmanial agents. This study investigated the leishmanicidal activity of Microgramma vacciniifolia frond lectin (MvFL) on promastigotes and amastigotes of Leishmania amazonensis.

METHODS

The effects of MvFL on promastigote proliferation and macrophage infection by amastigotes were evaluated and mean inhibitory concentrations (IC50) were calculated. As a safety assessment, the hemolytic capacity of MvFL (6.25-200 µg/mL) against mouse and human erythrocytes was determined. Additionally, the ability of MvFL (6.25-100 µg/mL) to modulate lysosomal and phagocytic activities and the nitric oxide (NO) production by murine peritoneal macrophages was also investigated.

RESULTS

After 24 h, MvFL inhibited the proliferation of L. amazonensis promastigotes, with an IC50 of 88 µg/mL; however, hemolytic activity was not observed. MvFL also reduced macrophage infection by amastigotes with an IC50 of 52 µg/mL. Furthermore, treatment with MvFL reduced the number of amastigotes internalized by infected murine peritoneal macrophages by up to 68.9% within 48 h. At a concentration of 25 µg/mL, MvFL stimulated lysosomal activity of macrophages within 72 h, but did not alter phagocytic activity or induce NO production at any of the tested concentrations.

CONCLUSION

MvFL exerts antileishmanial activity and further studies are needed to assess its therapeutic potential in in vivo experimental models of leishmaniasis.

Molecular Mechanisms of Persistence in Protozoan Parasites

Protozoan parasites are known for their remarkable capacity to persist within the bodies of vertebrate hosts, which frequently results in prolonged infections and the recurrence of diseases. Understanding the molecular mechanisms that underlie the event of persistence is of paramount significance to develop innovative therapeutic approaches, given that these pathways still need to be thoroughly elucidated. The present article provides a comprehensive overview of the latest developments in the investigation of protozoan persistence in vertebrate hosts. The focus is primarily on the function of persisters, their formation within the host, and the specific molecular interactions between host and parasite while they persist. Additionally, we examine the metabolomic, transcriptional, and translational changes that protozoan parasites undergo during persistence within vertebrate hosts, focusing on major parasites such as Plasmodium spp., Trypanosoma spp., Leishmania spp., and Toxoplasma spp. Key findings of our study suggest that protozoan parasites deploy several molecular and physiological strategies to evade the host immune surveillance and sustain their persistence. Furthermore, some parasites undergo stage differentiation, enabling them to acclimate to varying host environments and immune challenges. More often, stressors such as drug exposure were demonstrated to impact the formation of protozoan persisters significantly. Understanding the molecular mechanisms regulating the persistence of protozoan parasites in vertebrate hosts can reinvigorate our current insights into host-parasite interactions and facilitate the development of more efficacious disease therapeutics.

A Difficult-To-Diagnose Case of American Tegumentary Leishmaniasis

This case report presents a difficult-to-diagnose case of American tegumentary leishmaniasis (ATL) caused by Leishmania (Viannia) guyanensis in a 24-year-old Hispanic male with a travel history to the Panama jungle, an endemic region for tropical infectious diseases. The patient initially presented with persistent skin lesions that progressed to abscesses with ulceration. Despite negative initial diagnostic tests, including microbiological investigations and histopathological examination, a comprehensive diagnostic workup and subsequent polymerase chain reaction (PCR) confirmed the presence of Leishmania parasites. This case underscores the need to consider tropical infectious diseases despite initial negative tests. Accurate species identification is vital for proper drug treatment, with miltefosine as an emerging option. Early, precise diagnosis and tailored management are essential for successful treatment. This report emphasizes the significance of conducting a comprehensive diagnostic workup, including PCR, in individuals with a history of travel to endemic regions, to accurately diagnose and effectively manage complex infectious diseases.

Synthesis, antileishmanial activity and molecular modeling of new 1-aryl/alkyl-3-benzoyl/cyclopropanoyl thiourea derivatives

Due to the lack of effective vaccine(s) against leishmania and also pharmacokinetics issues of current drugs, it is necessary to discover new antileishmanial agents. Within this particular study, a series of novel 1-aryl/alkyl-3-benzoyl/cyclopropanoyl thiourea derivatives were synthesized (yields 69-84%) and evaluated as antileishmanial compounds (1-11). Synthetic derivatives were subjected to in vitro antileishmanial assessment against Leishmania major promastigotes by colorimetric MTT assay. Compounds 3 (IC50 38.54 µg/mL), 5 (IC50 84.75 µg/mL) and 10 (IC50 70.31 µg/mL) exhibited higher activities after 48 h but were less potent than amphotericin B (IC50 0.19 µg/mL). Antileishmanial activities indicated priority of 5-methyl-4-phenyl thiazole over furyl methyl substituents and 4-phenyl thiazole on thiourea nitrogen. N-myristoyltransferase (NMT) was selected as a validated L. major target for molecular docking studies. In silico results indicated the contribution of hydrophobic, π-stacking and H-bond interactions in binding to target. Most of the synthesized derivatives had lower binding affinities to human NMT (hNMT) than leishmanial enzyme. Docking conformations of top-ranked selective binders (compounds 3 and 5) were subjected to 50 ns MD simulations inside L. major HMT (LmNMT) active site. MD trajectories were used to extract RMSD, RMSF, Rg and durability of intramolecular/intermolecular H-bonds of the complex. It was observed that compound 3 escaped from LmNMT binding site during simulation period and no stable complex could be envisaged. Unlike 3, compound 5 attained stable binding conformation with converged stability parameters. Although mechanistic details for antileishmanial effects of synthesized derivatives are to be explored, current results may be implicated in further structure-guided approach toward potent antileishmanial agents.

Smartphone-readable RPA-LFA for the high-sensitivity detection of Leishmania kDNA using nanophosphor reporters

Early diagnosis of infectious diseases improves outcomes by enabling earlier delivery of effective treatment, and helps prevent further transmission by undiagnosed persons. We demonstrated a proof-of-concept assay combining isothermal amplification and lateral flow assay (LFA) for early diagnosis of cutaneous leishmaniasis, a vector-borne infectious disease that affects ca. 700,000 to 1.2 million people annually. Conventional molecular diagnostic techniques based on polymerase chain reaction (PCR) require complex apparatus for temperature cycling. Recombinase polymerase amplification (RPA) is an isothermal DNA amplification method that has shown promise for use in low-resource settings. Combined with lateral flow assay as the readout, RPA-LFA can be used as a point-of-care diagnostic tool with high sensitivity and specificity, but reagent costs can be problematic. In this work, we developed a highly-sensitive smartphone-based RPA-LFA for the detection of Leishmania panamensis DNA using blue-emitting [(Sr0.625Ba0.375)1.96Eu0.01Dy0.03]MgSi2O7 (SBMSO) persistent luminescent nanophosphors as LFA reporters. The greater detectability of nanophosphors allows the use of a reduced volume of RPA reagents, potentially reducing the cost of RPA-LFA. The limit of detection (LOD) of RPA with gold nanoparticle-based LFA readout is estimated at 1 parasite per reaction, but LOD can be 100-fold better, 0.01 parasites per reaction, for LFA based on SBMSO. This approach may be useful for sensitive and cost-effective point-of-care diagnosis and contribute to improved clinical and economic outcomes, especially in resource-limited settings.

Fatty Acid Composition and Metabolism in Leishmania Parasite Species: Potential Biomarkers or Drug Targets for Leishmaniasis?

Fatty acids have received growing interest in Leishmania biology with the characterization of the enzymes allowing the complete fatty acid synthesis of this trypanosomatid parasite. This review presents a comparative analysis of the fatty acid profiles of the major classes of lipids and phospholipids in different species of Leishmania with cutaneous or visceral tropism. Specificities relating to the parasite forms, resistance to antileishmanial drugs, and host/parasite interactions are described as well as comparisons with other trypanosomatids. Emphasis is placed on polyunsaturated fatty acids and their metabolic and functional specificities, in particular, their conversion into oxygenated metabolites that are inflammatory mediators able to modulate metacyclogenesis and parasite infectivity. The impact of lipid status on the development of leishmaniasis and the potential of fatty acids as therapeutic targets or candidates for nutritional interventions are discussed.

Development of Ag-ZnO/AgO Nanocomposites Effectives for Leishmania braziliensis Treatment

Tegumentary leishmaniasis (TL) is caused by parasites of the genus Leishmania. Leishmania braziliensis (L.b) is one of the most clinically relevant pathogens that affects the skin and mucosa, causing single or multiple disfiguring and life-threatening injuries. Even so, the few treatment options for patients have significant toxicity, high dropout rates, high cost, and the emergence of resistant strains, which implies the need for studies to promote new and better treatments to combat the disease. Zinc oxide nanocrystals are microbicidal and immunomodulatory agents. Here, we develop new Ag-ZnO/xAgO nanocomposites (NCPs) with three different percentages of silver oxide (AgO) nanocrystals (x = 49%, 65%, and 68%) that could act as an option for tegumentary leishmaniasis treatment. Our findings showed that 65% and 68% of AgO inhibit the extra and intracellular replication of L.b. and present a high selectivity index. Ag-ZnO/65%AgO NCPs modulate activation, expression of surface receptors, and cytokine production by human peripheral blood mononuclear cells toward a proinflammatory phenotype. These results point to new Ag-ZnO/AgO nanocomposites as a promising option for L. braziliensis treatment.

Apigenin and its dermatological applications: A comprehensive review

Apigenin is one of the abundant flavonoids in fruits and vegetables of human diet with several demonstrated health benefits. The aim of the present study is to provide an overview of the current evidence regarding the effect of apigenin on different dermatological complications. Electronic databases including PubMed, Scopus, and Web of Science were searched to retrieve all papers assessing the dermatological effects of apigenin. Preclinical studies support beneficial effects of apigenin on UV-induced skin damage, vitiligo, dermatitis, wounds, skin aging, and some types of skin cancer. The compound mostly acts via inhibition of inflammation through suppression of pro-inflammatory cytokines and intracellular inflammatory mediators, as well as antioxidant properties such as improvement of endogenous antioxidant defense mechanisms. There are also some studies for the design and development of novel drug delivery systems for apigenin to improve its oral and topical bioavailability. Nevertheless, no clinical study has evaluated apigenin as a natural supplement for skin conditions. Considering the benefits of apigenin in preclinical models of dermatological disorders, as well as the acceptable safety of this compound, apigenin may be a future candidate to be used in dermatological disorders. Future clinical studies are needed to further confirm the safety and efficacy of apigenin in skin care products.

Aminoacyl-tRNA synthetase (AARS) as an attractive drug target in neglected tropical trypanosomatid diseases-Leishmaniasis, Human African Trypanosomiasis and Chagas disease

TriTryp diseases (Leishmaniasis, Human African Trypanosomiasis (HAT), and Chagas disease) are devastating parasitic neglected tropical diseases (NTDs) that affect billions of people in developing countries, cause high mortality in humans, and impose a large socio-economic burden. The current treatment options against tritryp diseases are suboptimal and challenging due to the emergence of resistance against available tritryp drugs. Hence, designing and developing effective anti-tritryp drugs with novel targets are required. Aminoacyl-tRNA synthetases (AARSs) involved in specific aminoacylation of transfer RNAs (tRNAs), interrupt protein synthesis through inhibitors, and retard the parasite growth. AaRSs have long been studied as therapeutic targets in bacteria, and three aaRS inhibitors, mupirocin (against IleRS), tavaborole AN2690 (against LeuRS), and halofuginone (against ProRS), are already in clinical practice. The structural differences between tritryp and human aaRSs and the presence of unique sequences (N-terminal domain/C-terminal domain/catalytic domain) make them potential target for developing selective inhibitors. Drugs based on a single aaRS target developed by high-throughput screening (HTS) are less effective due to the emergence of resistance. However, designing multi-targeted drugs may be a better strategy for resistance development. In this perspective, we discuss the characteristics of tritryp aaRSs, sequence conservation in their orthologs and their peculiarities, recent advancements towards the single-target and multi-target aaRS inhibitors developed through rational design.

Discriminator for Cutaneous Leishmaniasis Using MALDI-MSI in a Murine Model

Cutaneous leishmaniasis is a skin disease caused by flagellate protozoa of the genus Leishmania and transmitted by sandflies of the genus Lutzomyia. Around 1 million new cases occur in the world annually, with a total of 12 million people affected, mainly in rural areas with low access to health services and adequate treatments. In the area of the Americas, Colombia has one of the highest infection rates after Brazil. Topical treatments with pentamidine isethionate (PMD) present an attractive alternative due to their ease of application and low costs. However, cutaneous leishmaniasis lesions present nodules with seropurulent exudate that, when drying, form hyperkeratotic lesions, hindering the effective penetration of drugs for their treatment. The use of molecular histology techniques, such as MALDI-MSI, allow in situ evaluation of the penetration of the treatment to the sections of the dermis where the disease-causing parasite resides. However, the large volume of information generated makes it impossible to process it manually. Machine learning techniques allow the unsupervised processing of large amounts of information, generating prediction models for the classification of new information. This work proposes a low-cost method to generate cutaneous leishmaniasis detection and classification models using MALDI-MSI images taken from murine models. The proposed models allow a 95% efficiency when separating healthy samples from infected samples and an effectiveness of 67% when separating effectively treated samples from unsuccessfully treated samples.

Insecticide-treated net (ITN) use, factors associated with non-use of ITNs, and occurrence of sand flies in three communities with reported cases of cutaneous leishmaniasis in Ghana

Background

The insecticide treated bed net (ITN) has been proven for malaria control. Evidence from systematic review also suggests benefits of ITN roll out in reducing the incidence of cutaneous leishmaniasis (CL) and other vector borne diseases.

Methods

Using a community-based cross-sectional study design, ITN use, factors associated with non-use of ITNs, and occurrence of sand flies were investigated in three communities with reported cases of CL in the Oti region of Ghana.

Results

A total of 587 households comprising 189 (32.2%), 200 (34.1%), and 198 (33.7%) households from Ashiabre, Keri, and Sibi Hilltop communities with de facto population of 3639 participated in this study. The proportion of households that owned at least one ITN was 97.1%. The number of households having at least one ITN for every two members was 386 (65.8%) and 3159 (86.8%) household population had access to ITN. The household population that slept in ITN the night before this survey was 2370 (65.1%). Lack of household access to ITN (AOR = 1.80; CI: 1.31, 2.47), having a family size of more than 10 members (AOR = 2.53; CI: 1.20, 4.24), having more than 10 rooms for sleeping in a household (AOR = 10.18; CI: 1.28, 81.00), having 2–4 screened windows (AOR = 1.49; CI: 1.00, 2.20), and having 8–10 screened windows (AOR = 3.57; CI: 1.25, 10.17) were significantly associated with increased odds of not sleeping in ITN the night before the survey. A total of 193 female sand flies were trapped from various locations within the study communities.

Conclusions

Factors associated with ITN non-use such as lack of household access to ITN should be incorporated into future efforts to improve ITN use. Species of sand flies and their potential vectorial role in the study communities should also be investigated.

β-carbolines RCC and C5 induce death of Leishmania amazonensis intracellular amastigotes

Background: Cutaneous leishmaniasis is caused by Leishmania spp., and its treatment is limited. The β-carbolines have shown activity against kinetoplastids. Aim: To evaluate the activity and effects of the β-carbolines, N-{2-[(4,6-bis(isopropylamino)-1,3,5-triazin-2-yl)amino]ethyl}-1-(4-methoxyphenyl)-β-carboline-3-carboxamide (RCC) and N-benzyl-1-(4-methoxy)phenyl-9H-beta-carboline-3-carboxamide (C5), against L. amazonensis intracellular amastigotes and to suggest their mechanism of action. Methods: We analyzed the activity and cytotoxicity of β-carbolines and the morphological alterations by electron microscopy. Mitochondrial membrane potential, production nitric oxide, reactive oxygen species, lipidic bodies, autophagic vacuoles and ATP were also evaluated. Results & conclusion: The results showed that RCC and C5 are active against intracellular amastigotes and were able to induce oxidative stress and ultrastructural alterations such as accumulation of lipid bodies and autophagic vacuoles, leading to parasite death.

Atypical Cutaneous Leishmaniasis Variant

Leishmaniasis is a complex group of parasitic infectious diseases caused by intracellular protozoa of the genus Leishmania. It is a zoonosis mainly transmitted by the bite of infected female Phlebotomus or Lutzomyia sandflies. Clinical manifestations of leishmaniasis are diverse and can range from asymptomatic presentations to disseminated systemic disease. Cutaneous leishmaniasis is endemic in more than 80 countries in the world, having a predominance in tropical and subtropical regions. Although the majority of cases follow a classic development, an increasing number of new and rare variants of cutaneous leishmaniasis have been reported. These variants should be suspected as a cause of diverse clinical presentations, especially in endemic regions and travelers, being a diagnostic challenge for physicians.

We present a case of atypical cutaneous leishmaniasis found as a single verrucous plaque of eight months of evolution in the left posterior thigh of a 35-year-old man, who presented mild pruritus. The patient reported shrimp farming as his main occupational activity and was living in a rural region surrounded by forest on the Pacific coast of Ecuador. On dermatological examination, a single 4 x 5 cm verrucous plaque with irregular borders and a scaly erythematous violaceous aspect was found. Histopathological analysis revealed the presence of lymphohistiocytic inflammatory infiltrate with plasmocytes and granulomatous inflammation. On the Giemsa stain, intracellular amastigotes (Leishman-Donovan bodies) were observed. The treatment consisted of intramuscular meglumine antimoniate, presenting significant improvement on follow-up.

Identification of potential antileishmanial agents via structure-based molecular simulations

Leishmaniasis is a parasitic disease with frequent annual incidence. An important issue in chemotherapy is the emergence of resistance, toxicity and lack of cost-effectiveness within current drugs. Therefore, it is of utmost importance to design effective drugs against disease. Current contribution was devoted to the in-silico analysis of binding a few flavonoids/alkaloids to relevant leishmanial targets. Docking scores were used to prioritize acquired affinities and top ranked binders were subjected to subsequent 100-ns MD simulation in explicit water. Binding trajectories revealed the tightest interaction modes for two flavonoid molecules (acerosin and nevadensin) in the uracil DNA glycolase (UDG) active site. Acerosin showed less conformational changes whereas, nevadensin interacted stably during longer simulation time. Conserved interactions of Gln205 and His331 to acerosin indicated their dominant biological role in complex stability. No conserved residues were perceived for nevadensin interactions and a completely new and stable binding conformation could be retrieved after 12 ns simulation. Moreover; acerosin was subjected to DFT analysis for pairwise decomposition evaluations of interacted residues. Although primary mechanisms of action are yet to be discovered, UDG may be a promising target for developing antileishmanial flavonoids.

Some Scaffolds as Anti-leishmanial Agents: An Review

Leishmaniasis is a parasitic infectious neglected tropical disease transmitted to humans by the parasites of Leishmania species. Mainly three types of leishmaniasis cases such as visceral (VL), cutaneous (CL) and mucocutaneous leishmaniasis are usually observed. In many western countries, almost 700,000 to 1million peoples are suffering from leishmaniasis and it is estimated that around 26000 to 65000 deaths occurs annually. For its treatment few drugs are available however none of them are ideal to treat leishmaniasis due to long treatment, discomfort mode of administration, risk of high level toxicity, high resistance against etc. Hence so many patients are unable to take complete treatment due to the high drug resistance. The present review will focus on antileishmanial activity of reported derivatives of betacarboline, chalcone, azole, quinoline, quinazoline, benzimidazole, benzadiazapine, thiaazoles, semicarbazone and hydontoin analogues. We believe that this present study will helpful to researcher to design new antileishmanial agents.

ENTPDases from Pathogenic Trypanosomatids and Purinergic Signaling: Shedding Light towards Biotechnological Applications

ENTPDases are enzymes known for hydrolyzing extracellular nucleotides and playing an essential role in controlling the nucleotide signaling via nucleotide/purinergic receptors P2. Moreover, ENTPDases, together with Ecto-5´-nucleotidase activity, affect the adenosine signaling via P1 receptors. These signals control many biological processes, including the immune system. In this context, ATP is considered as a trigger to inflammatory signaling, while adenosine (Ado) induces anti-inflammatory response. The trypanosomatids Leishmania and Trypanosoma cruzi, pathogenic agents of Leishmaniasis and Chagas Disease, respectively, have their own ENTPDases named "TpENTPDases," which can affect the nucleotide signaling, adhesion and infection, in order to favor the parasite. Besides, TpENTPDases are essential for the parasite nutrition, since the Purine De Novo synthesis pathway is absent in them, which makes these pathogens dependent on the intake of purines and nucleopurines for the Salvage Pathway, in which TpENTPDases also take place. Here, we review information regarding TpNTPDases, including their known biological roles and their effect on the purinergic signaling. We also highlight the roles of these enzymes in parasite infection and their biotechnological applications, while pointing to future developments.

Green Approach: ''A Forwarding Step for Curing Leishmaniasis-A Neglected Tropical Disease''

The present review focuses on a dreaded vector-mediated leishmaniasis, with the existing therapeutic approaches including a variety of drugs along with their limitations, the treatment with natural compounds, and different types of metal/metal oxide nanoparticles (NPs). As evidenced, various metallic NPs, comprising silver, silver oxide, gold, zinc oxide, titanium, lead oxide, etc., played a curative role to treat leishmaniasis, are also presented. Keeping in view the advance success of vaccines against the prevalent dreaded diseases in the past and the present scenario, efforts are also being made to develop vaccines based on these NP formulations.

1,3,5-Triazine: A versatile pharmacophore with diverse biological activities

1,3,5-Triazine and its derivatives have been the epicenter of chemotherapeutic molecules due to their effective biological activities, such as antibacterial, fungicidal, antimalarial, anticancer, antiviral, antimicrobial, anti-inflammatory, antiamoebic, and antitubercular activities. The present review represents a summarized report of the crucial biological activities possessed by substituted 1,3,5-triazine derivatives, with special attention to the most potent compounds.

The limited knowledge of placental damage due to neglected infections: ongoing problems in Latin America

The placenta works as a selective barrier, protecting the fetus from potential infections that may affect the maternal organism during pregnancy. In this review, we will discuss several challenging infections that are common within Latin American countries and that may affect the maternal-fetal interface and pose risks to fetal development. Specifically, we will focus on emerging infectious diseases including the arboviruses, malaria, leishmaniasis, and the bacterial foodborne disease caused by Shiga toxin-producing Escherichia coli. We will also highlight some topics of interest currently being studied by research groups that comprise an international effort aimed at filling the knowledge gaps in this field. These topics address the relationship between exposure to microorganisms and placental abnormalities, congenital anomalies, and complications of pregnancy.

ABBREVIATIONS

ADE: antibody-dependent enhancement; CCL2: monocyte chemoattractant protein-1; CCL3: macrophage inflammatory protein-1 α; CCL5: chemokine (C-C motif) ligand 5; CHIKV: chikungunya virus; DCL: diffuse cutaneous leishmaniasis; DENV: dengue virus; Gb3: glycolipid globotriaosylceramyde; HIF: hypoxia-inducible factor; HUS: hemolytic uremic syndrome; IFN: interferon; Ig: immunoglobulins; IL: interleukin; IUGR: intrauterine growth restriction; LCL: localized cutaneous leishmaniasis; LPS: lipopolysaccharid; MCL: mucocutaneous leishmaniasis; NO: nitric oxide; PCR: polymerase chain reaction; PGF: placental growth factor; PM: placental malaria; RIVATREM: Red Iberoamericana de Alteraciones Vasculares em transtornos del Embarazo; sVEGFR: soluble vascular endothelial growth factor receptor; STEC: shiga toxin-producing Escherichia coli; stx: shiga toxin protein; TNF: tumor necrosis factor; TOAS: T cell original antigenic sin; Var2CSA: variant surface antigen 2-CSA; VEGF: vascular endothelial growth factor; VL: visceral leishmaniasis; WHO: world health organization; YFV: yellow fever virus; ZIKV: Zika virus.

Immunoproteomics characterization of Leishmania panamensis proteins for potential clinical diagnosis of mucosal Leishmaniasis

Diagnosis of leishmaniasis based on antibodies detection represents a challenge due to cross-reaction of sera with other infectious agents, which co-exist in endemic areas of Leishmania sp, especially patients with Trypanosoma cruzi. This work is aimed at searching for immunogenic proteins in sera from patients with cutaneous and mucosal leishmaniasis that may be potential candidates for the development of diagnostic tests and/or vaccines that help control the infection. Total protein extracts of L. panamensis promastigotes were put in contact with sera from patients with cutaneous and mucosal leishmaniasis (immunoblots). Immunoreactive proteins were identified by mass spectrometry and bioinformatics tools. 81 proteins were identified. One of these was uniquely recognized by the sera from patients with ML but not from sera from either CL or Chagas disease patients. MS analysis of this band pointed to the putative leishmanial 3-oxoacyl-(Acylcarrierprotein) reductase.

Gene expression patterns associated with Leishmania panamensis infection in macrophages from BALB/c and C57BL/6 mice

Leishmania parasites can trigger different host immune responses that result in varying levels of disease severity. The C57BL/6 and BALB/c mouse strains are among the host models commonly used for characterizing the immunopathogenesis of Leishmania species and the possible antileishmanial effect of novel drug candidates. C57BL/6 mice tend to be resistant to Leishmania infections, whereas BALB/c mice display a susceptible phenotype. Studying species-specific interactions between Leishmania parasites and different host systems is a key step to characterize and validate these models for in vivo studies. Here, we use RNA-Seq and differential expression analysis to characterize the transcriptomic profiles of C57BL/6 and BALB/c peritoneal-derived macrophages in response to Leishmania panamensis infection. We observed differences between BALB/c and C57BL/6 macrophages regarding pathways associated with lysosomal degradation, arginine metabolism and the regulation of cell cycle. We also observed differences in the expression of chemokine and cytokine genes associated with regulation of immune responses. In conclusion, infection with L. panamensis induced an inflammatory gene expression pattern in C57BL/6 macrophages that is more consistently associated with a classic macrophage M1 activation, whereas in BALB/c macrophages a gene expression pattern consistent with an intermediate inflammatory response was observed.

A retrospective cohort study of the effectiveness and adverse events of intralesional pentavalent antimonials in the treatment of cutaneous leishmaniasis

Introduction

The standard therapy for American cutaneous leishmaniasis (ACL) is intravenous meglumine antimoniate (IV-MA). However, treatment interruptions due to adverse events (AEs) and non-adherence are frequent. Consequently, intralesional MA (IL-MA) was proposed.

Objective

This study examined the effectiveness of and AEs associated with IL-MA.

Methods

We performed a retrospective cohort study of 240 patients with ACL. We excluded patients with mucous lesions and disseminated leishmaniasis and those who received treatment in the previous 6 months. We considered protocol treatments as the main risk factors. IL-MA was performed using a subcutaneous injection of MA in a volume sufficient to elevate the lesion base (approximately 1 mL/cm² of lesion area) once weekly for 1–8 weeks. IV-MA was performed via intravenous injections of MA at a dosage of 10–20 mg Sb⁵⁺/kg/day for 20 days. The primary outcome was defined as a lesion cure 3 months after treatment, and AEs were secondary outcomes.

Results

Seventy-three patients were included. The IL-MA group consisted of 21 patients, and the IV-MA group consisted of 52 patients. The IL-MA group was older, had more comorbidities and more previous unsuccessful treatment of ACL. The antimonial dose was significantly lower in this group. The cure rate for IL-MA was 66.7%, which was lower than that in the IV-MA group (relative risk (RR) = 0.68, 95% CI: 0.50–0.92, p < 0.001), while the rate of AEs was similar. Female sex (RR = 1.16, 95% CI: 1.02–1.33), lesion diameter ≤1 cm (RR = 1.25, 95% CI: 1.00–1.56) and treatment with IV-MA (RR = 1.43, 95% CI: 1.06–1.93) were independently associated with achieving a cure. Comorbidities (RR = 1.7, 95% CI: 1.06–2.98) were independently associated with AEs.

Conclusions

Patients of IL-MA group were older, had more comorbidities and more previous unsuccessful treatment of ACL. Nevertheless, IL-MA had a cure rate of 66.7%, and it was useful in this context. A prospective randomized trial is recommended.

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Intralesional antimonials (IL-MA) had a 66.7% lower cure compared to systemic.

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IL-MA group was older, had more comorbidities and unsuccessful previous treatment.

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IL-MA was useful in this group, where worse clinical responses are expected.

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Lesions larger than 3 cm did not have more chance of failure with IL-MA.

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There was no mucous recurrence after IL-MA in an area of New World Leishmaniasis.

Gallic and Ellagic Acids Are Promising Adjuvants to Conventional Amphotericin B for the Treatment of Cutaneous Leishmaniasis

In this study, we demonstrated the potential associative effect of combining conventional amphotericin B (Amph B) with gallic acid (GA) and with ellagic acid (EA) in topical formulations for the treatment of cutaneous leishmaniasis in BALB/c mice. Preliminary stability tests of the formulations and in vitro drug release studies with Amph B, GA, Amph B plus GA, EA, and Amph B plus EA were carried out, as well as assessment of the in vivo treatment of BALB/c mice infected with Leishmania major After 40 days of infection, the animals were divided into 6 groups and treated twice a day for 21 days with a gel containing Amph B, GA, Amph B plus GA, EA, or Amph B plus EA, and the negative-control group was treated with the vehicle. In the animals that received treatment, there was reduction of the lesion size and reduction of the parasitic load. Histopathological analysis of the treatments with GA, EA, and combinations with Amph B showed circumscribed lesions with the presence of fibroblasts, granulation tissue, and collagen deposition, as well as the presence of activated macrophages. The formulations containing GA and EA activated macrophages in all evaluated parameters, resulting in the activation of cells of the innate immune response, which can generate healing and protection. GA and EA produced an associative effect with Amph B, which makes them promising for use with conventional Amph B in the treatment of cutaneous leishmaniasis.

Antileishmanial activity of a new chloroquine analog in an animal model of Leishmania panamensis infection

Leishmania panamensis is a relevant causative agent of tegumentary leishmaniasis in several Latin American countries. Available antileishmanial drugs have several limitations including relatively high toxicity, difficult administration, high production costs and the emergence of resistance in circulating strains. Therefore, the identification of new molecules as potential therapeutics for leishmaniasis is of great relevance. Here, we developed a murine model of L. panamensis infection and evaluated the effect of a new compound in vivo. After treatment of animals with the compound, we observed a significant reduction of inflammation and parasite load at the inoculation site, in a dose-dependent manner. We observed a reduction in IL-10 production by popliteal lymph nodes cells of infected mice. These results pave the way for future evaluation of this compound as a potential antileishmanial drug or as a suitable scaffold for lead optimization strategies.

Investigation of antileshmanial activities of Cuminum cyminum based green silver nanoparticles on L. tropica promastigotes and amastigotes in vitro

Leishmaniasis is one of the most important parasitic diseases, which is caused by Leishmania species. Nowadays; although pentavalent antimonials are used as the basic treatment option for Cutaneous Leishmaniasis, high cost, toxicity and resistance of the parasites to the medication over time are some important limitations causing several problems in the treatment. In recent years, the progress in the field of green nanotechnology provides the development of green nanoparticle-based treatment methods for Cutaneous Leishmaniasis. The importance of green nanoparticles has gradually increased due to their special reductive, stabilizing, antioxidant and non-toxic properties. Although there are many studies based on green nanoparticles against Leishmania parasites, we have not found any research about antileishmanial activities of biosynthesized silver nanoparticles (Bio-AgNPs) using Cuminum cyminum L (Cumin) seed extract. Therefore for the first time in this study in vitro antileishmanial effects of Bio-AgNPs prepared from Cumin seed extract were examined on L. tropica promastigote and amastigote forms and their efficacies were compared with chemically synthetized AgNPs. During the experiments, antileishmanial effects of synthetized nanoparticles were determined on both promastigote and amastigote forms of Leishmania parasites by detecting different parameters such as proliferation, infection index and produced nitric oxide (NO) amounts from macrophages. According to the results, it was shown that Bio-AgNPs and AgNPs excessively inhibited L. tropica promastigotes and amastigotes by significantly decreasing proliferation rates of promastigotes and metabolic activities of amastigotes, as well. Moreover, infection index rates of macrophages revealed remarkable anti-amastigote performances of Bio-AgNPs. Besides, Bio-AgNPs stimulated macrophages to release NO to kill Leishmania parasites. Consequently, for the first time, Bio-AgNPs were found to be more effective on both forms of Leishmania parasites than AgNPs. Obtained results indicated high antileishmanial potential of green nanoparticles on L. tropica parasites, causative agents of Cutaneous Leishmaniasis. Thus, obtained results demonstrated that green nanoparticles can lead to the development of new, safer, stable and more effective antileishmanial formulations against Cutaneous Leishmaniasis.

Application of laser for treatment of cutaneous leishmaniasis: a review of literature

Cutaneous leishmaniasis (CL) is a major health problem in developing countries with high economic and health impact. Despite suggested treatment for CL, there is still no definite therapy for this infection, and many of these treatments are associated with serious local and systemic side effects. In the current paper, use of different laser types including continuous and fractional CO2, argon, PDL, erbium glass, and Nd:YAG have been reviewed. Based on our review, given the high reported efficacy and low side-effect profile, use of laser can be considered as a good alternative to standard treatment of cutaneous leishmaniasis (CL). Performing more studies using different types of lasers is recommended to evaluate the efficacy of this method for treatment of CL.

Immune Profile of the Nasal Mucosa in Patients with Cutaneous Leishmaniasis

Localized skin lesions are characteristic of cutaneous leishmaniasis (CL); however, Leishmania (Viannia) species, which are responsible for most CL cases in the Americas, can spread systemically, sometimes resulting in mucosal disease. Detection of Leishmania has been documented in healthy mucosal tissues (conjunctiva, tonsils, and nasal mucosa) and healthy skin of CL patients and in individuals with asymptomatic infection in areas of endemicity of L (V) panamensis and L (V) braziliensis transmission. However, the conditions and mechanisms that favor parasite persistence in healthy mucosal tissues are unknown. In this descriptive study, we compared the cell populations of the nasal mucosa (NM) of healthy donors and patients with active CL and explored the immune gene expression signatures related to molecular detection of Leishmania in this tissue in the absence of clinical signs or symptoms of mucosal disease. The cellular composition and gene expression profiles of NM samples from active CL patients were similar to those of healthy volunteers, with a predominance of epithelial over immune cells, and within the CD45⁺ cell population, a higher frequency of CD66b⁺ followed by CD14⁺ and CD3⁺ cells. In CL patients with molecular evidence of Leishmania persistence in the NM, genes characteristic of an anti-inflammatory and tissue repair responses (IL4R, IL5RA, POSTN, and SATB1) were overexpressed relative to NM samples from CL patients in which Leishmania was not detected. Here, we report the first immunological description of subclinically infected NM tissues of CL patients and provide evidence of a local anti-inflammatory environment favoring parasite persistence in the NM.

Current Advances in the Synthesis and Biological Evaluation of Pharmacologically Relevant 1,2,4,5-Tetrasubstituted-1H-Imidazole Derivatives

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In recent years, the synthesis and evaluation of the biological properties of 1,2,4,5-tetrasubstituted-1H-imidazole derivatives have been the subject of a large number of studies by academia and industry. In these studies it has been shown that this large and highly differentiated class of heteroarene derivatives includes high valuable compounds having important biological and pharmacological properties such as antibacterial, antifungal, anthelmintic, anti-inflammatory, anticancer, antiviral, antihypertensive, cholesterol-lowering, antifibrotic, antiuricemic, antidiabetic, antileishmanial and antiulcer activities.

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The present review with 411 references, in which we focused on the literature data published mainly from 2011 to 2017, aims to update the readers on the recent developments on the synthesis and biological evaluation of pharmacologically relevant 1,2,4,5-tetrasubstituted-1H-imidazole derivatives with an emphasis on their different molecular targets and their potential use as drugs to treat various types of diseases. Reference was also made to substantial literature data acquired before 2011 in this burgeoning research area.

Garcinielliptone FC: Selective anti-amastigote and immunomodulatory effects on macrophages infected by Leishmania amazonensis

The present study was directed to the in vitro antileishmanial, cytotoxic and immunomodulatory effects of Garcinielliptone FC (GFC) against promastigote and macrophage-internalized amastigote forms of Leishmania amazonensis. GFC showed in vitro cytotoxicity against BALB/c peritoneal macrophages with CC₅₀ of 74.90 μM. The hemolytic activity against sheep erythrocytes only demonstrated a decrease of 20.42% in cell viability at the highest tested concentration tested (1326.0 μM). GFC promoted in vitro growth inhibition of both promastigote and intracellular amastigotes with IC₅₀ values of 14.06 and 1.91 μM, respectively, with 7.3-fold higher Selectivity Index (SI) for intracellular amastigotes (SI = 39.21) than for promastigotes (SI = 5.33). Interestingly, the pre-treatment of macrophages or promastigotes with GFC promoted decrease of infected macrophages and number of recovered amastigotes, respectively. Also, GFC was able to markedly promote macrophages activation by increase of phagocytic capability and nitrite production at concentrations able to solve infection of macrophages by L. amazonensis, suggesting the possible involvement of immunomodulatory modulation of macrophages leading to solve the infection. GFC is an emerging and promising chemical compound for the studies focused on the assessment of its therapeutic potential on in vivo experimental models of leishmaniasis.

Clinical and Pathological Aspects of Canine Cutaneous Leishmaniasis: A Meta-analysis

PURPOSE

In the present study, we described the most prevalent clinical symptoms, the most affected organs, and the macro and microscopic lesions associated with cutaneous leishmaniasis.

METHODS

Two independent researchers performed an extensive systematic review of the literature in four stages (identification, screening, eligibility, and inclusion) to identify studies published between January 2002 and November 2018 from the following electronic databases: Web of Science, PubMed, SciELO, Science Direct, and Google Scholar. Meta-analysis was conducted in "Metaprop" package of R 3.4.2 software.

RESULTS

The electronic search yielded 3896 results, out of which 155 were further analyzed based on the full-text. Data extracted from 16 articles were included in the meta-analysis, representing a total of 430 leishmaniasis cases. Only 43% of all animals were identified to exhibit the clinical and cutaneous changes characteristic of leishmaniasis based on the observation that skin lesions were the most prevalent clinical sign and were present in 86% of all cases. Other less prevalent symptoms included weight loss, cachexia, apathy and lymph node enlargement. Histopathological analysis showed that the skin was the most affected organ, affecting 64% of cases, followed by lymph nodes (12%), spleen (8%) and liver (7%).

CONCLUSIONS

Therefore, our current findings suggest that cutaneous leishmaniasis could lead to visceral disease. Notably, our findings indicated no clinical manifestation patterns in cutaneous leishmaniasis, since the same host species may present different clinical conditions.

Cost-effectiveness analysis of Mucosal Leishmaniasis diagnosis with PCR-based vs parasitological tests in Colombia

To estimate the cost-effectiveness of available diagnosis alternatives for Mucosal Leishmaniasis (ML) in Colombian suspected patients. A simulation model of the disease's natural history was built with a decision tree and Markov models. The model´s parameters were identified by systematic review and validated by expert consensus. A bottom-up cost analysis to estimate the costs of diagnostic strategies and treatment per case was performed by reviewing 48 clinical records of patients diagnosed with ML. The diagnostic strategies compared were as follows: 1) no diagnosis; 2) parasite culture, biopsy, indirect immunofluorescence assay (IFA), and Montenegro skin test (MST) combined ; 3) parasite culture, biopsy, and IFA combined; 4) PCR-miniexon; and 5) PCR-kDNA. Three scenarios were modeled in patients with ML clinical suspicion, according to ML prevalence scenarios: high, medium and low. Adjusted sensitivity and specificity parameters of a combination of diagnostic tests were estimated with a discrete event simulation (DES) model. For each alternative, the costs and health outcomes were estimated. The time horizon was life expectancy, considering the average age at diagnosis of 31 years. Incremental cost-effectiveness ratios (ICERs) were calculated per Disability Life Year (DALY) avoided, and deterministic and probabilistic sensitivity analyses were performed. A threshold of willingness to pay (WTP) of three-time gross domestic product per capita (GDPpc) (US$ 15,795) and a discount rate of 3% was considered. The analysis perspective was the third payer (Health System). All costs were reported in American dollars as of 2015. PCR- kDNA was the cost-effective alternative in clinical suspicion levels: low, medium and high with ICERs of US$ 7,909.39, US$ 5,559.33 and US$ 4,458.92 per DALY avoided, respectively. ML diagnostic tests based on PCR are cost-effective strategies, regardless of the level of clinical suspicion. PCR-kDNA was the most cost-effective strategy in the competitive scenario with the parameters included in the present model.

Therapeutic Interventions for Countering Leishmaniasis and Chagas's Disease: From Traditional Sources to Nanotechnological Systems

The incidence of neglected diseases in tropical countries, such as Leishmaniasis and Chagas's disease, is attributed to a set of biological and ecological factors associated with the socioeconomic context of developing countries and with a significant burden to health care systems. Both Leishmaniasis and Chagas's disease are caused by different protozoa and develop diverse symptoms, which depend on the specific species infecting man. Currently available drugs to treat these disorders have limited therapeutic outcomes, frequently due to microorganisms' drug resistance. In recent years, significant efforts have been made towards the development of innovative drug delivery systems aiming to improve bioavailability and pharmacokinetic profiles of classical drug therapy. This paper discusses the key facts of Leishmaniasis and Chagas's disease, the currently available pharmacological therapies and the new drug delivery systems for conventional drugs.

Medicinal chemistry of indole derivatives: Current to future therapeutic prospectives

Indole is a versatile pharmacophore, a privileged scaffold and an outstanding heterocyclic compound with wide ranges of pharmacological activities due to different mechanisms of action. It is an superlative moiety in drug discovery with the sole property of resembling different structures of the protein. Plenty of research has been taking place in recent years to synthesize and explore the various therapeutic prospectives of this moiety. This review summarizes some of the recent effective chemical synthesis (2014-2018) for indole ring. This review also emphasized on the structure-activity relationship (SAR) to reveal the active pharmacophores of various indole analogues accountable for anticancer, anticonvulsant, antimicrobial, antitubercular, antimalarial, antiviral, antidiabetic and other miscellaneous activities which have been investigated in the last five years. The precise features with motives and framework of each research topic is introduced for helping the medicinal chemists to understand the perspective of the context in a better way. This review will definitely offer the platform for researchers to strategically design diverse novel indole derivatives having different promising pharmacological activities with reduced toxicity and side effects.

Resistance of Leishmania (Viannia) Panamensis to Meglumine Antimoniate or Miltefosine Modulates Neutrophil Effector Functions

Leishmania (Viannia) panamensis (L. (V.) p.) is the main causative agent of cutaneous leishmaniasis in Colombia and is usually treated with either meglumine antimoniate (MA) or miltefosine (MIL). In recent years, there has been increasing evidence of the emergence of drug-resistance against these compounds. Neutrophils are known to play an important role in immunity against Leishmania. These cells are rapidly recruited upon infection and are also present in chronic lesions. However, their involvement in the outcome of infection with drug-resistant Leishmania has not been examined. In this study, human and murine neutrophils were infected in vitro with MA or MIL drug-resistant L. (V.) p. lines derived from a parental L. (V.) p. drug-susceptible strain. Neutrophil effector functions were assessed analyzing the production of reactive oxygen species (ROS), the formation of neutrophil extracellular trap (NET) and the expression of cell surface activation markers. Parasite killing by neutrophils was assessed using L. (V.) p. transfected with a luciferase reporter. We show here that MA and MIL-resistant L. (V.) p. lines elicited significantly increased NET formation and MA-resistant L. (V.) p. induced significantly increased ROS production in both murine and human neutrophils, compared to infections with the parental MIL and MA susceptible strain. Furthermore, neutrophils exposed to drug-resistant lines showed increased activation, as revealed by decreased expression of CD62L and increased expression of CD66b in human neutrophils yet presented higher survival within neutrophils than the drug-susceptible strain. These results provide evidence that parasite drug-susceptibility may influences neutrophil activation and function as well as parasite survival within neutrophils. Further investigaton of the inter-relationship of drug susceptibility and neutrophil effector function should contribute to better understanding of the factors involved in susceptibility to anti-Leishmania drugs.

Pathologic Features of Infectious Gastritis

This manuscript presents a review of infectious causes of gastritis aimed at the practicing anatomic pathologist. We shall highlight unique histologic findings and clinical attributes that will assist those analyzing endoscopically obtained mucosal biopsies of the stomach or resection specimens.

Prevalence of and Factors Associated with Negative Microscopic Diagnosis of Cutaneous Leishmaniasis in Rural Peru

Cutaneous leishmaniasis is endemic to South America where diagnosis is most commonly conducted via microscopy. Patients with suspected leishmaniasis were referred for enrollment by the Ministry of Health (MoH) in Lima, Iquitos, Puerto Maldonado, and several rural areas of Peru. A 43-question survey requesting age, gender, occupation, characterization of the lesion(s), history of leishmaniasis, and insect-deterrent behaviors was administered. Polymerase chain reaction (PCR) was conducted on lesion materials at the Naval Medical Research Unit No. 6 in Lima, and the results were compared with those obtained by the MoH using microscopy. Factors associated with negative microscopy and positive PCR results were identified using χ² test, t-test, and multivariate logistic regression analyses. Negative microscopy with positive PCR occurred in 31% (123/403) of the 403 cases. After adjusting for confounders, binary multivariate logistic regression analyses revealed that negative microscopy with positive PCR was associated with patients who were male (adjusted odds ration [OR] = 1.93 [1.06-3.53], P = 0.032), had previous leishmaniasis (adjusted OR = 2.93 [1.65-5.22], P < 0.0001), had larger lesions (adjusted OR = 1.02 [1.003-1.03], P = 0.016), and/or had a longer duration between lesion appearance and PCR testing (adjusted OR = 1.12 [1.02-1.22], P = 0.017). Future research should focus on further exploration of these underlying variables, discovery of other factors that may be associated with negative microscopy diagnosis, and the development and implementation of improved testing in endemic regions.

Immunodetection and molecular determination of visceral and cutaneous Leishmania infection using patients' urine

The diagnosis of leishmaniasis relies mainly on the use of invasive processes, to collect the biological material for detecting Leishmania parasites. Body fluids, which can be collected by non-invasive process, would greatly facilitate the leishmaniasis diagnosis. In the present study, we investigated the potency of urine immunoblotting to diagnose cutaneous and visceral leishmaniasis and we compared with routine molecular methods. A total of 80 samples, including 40 sera and their 40 corresponding urine samples were collected from 37 suspected patients with cutaneous and visceral leishmaniasis, and 3 healthy individuals (as control), in Ilam and Ardabil provinces of Iran. All sera and urine samples were analyzed, using immunoblotting. The confirmation of leishmaniasis infection was performed, using conventional and quantitative PCRs as well as by sequencing the amplicons. Among 37 suspected patients, 23 patients presented cutaneous lesions (CL) and 14 exhibited clinical symptoms reminiscent of visceral leishmaniasis (L. infantum). Among cutaneous patients, 15 were positive for zoonotic cutaneous leishmaniasis (L. major), and eight for anthroponotic cutaneous leishmaniasis (L. tropica). Molecular quantification of Leishmania parasites was performed on sera, urines and cutaneous biopsies of CL and VL patients, demonstrating that parasite load is lower in urines, compared to sera or biopsy. DNA can be detected in 20 out of 23 (86.9%) CL urine samples and in 13 out of 14 (92.8%) VL urine samples. Immunodetection analysis demonstrates that 22 out of 23 (95.6%) sera from CL patients and all patients suspected with VL are positive. For urine samples, 18 out of 23 (78.2%) urine of CL patients and 13 out of 14 (92.8%) urine of VL patients were positive, using Western blot. Therefore, immunodetection and molecular analysis using urine samples can be used as a diagnostic tool for surveying cutaneous and visceral leishmaniasis.

PD-L1 May Mediate T-Cell Exhaustion in a Case of Early Diffuse Leishmaniasis Caused by Leishmania (L.) amazonensis

Introduction

Diffuse cutaneous leishmaniasis (DCL) is a rare disease form associated with Leishmania (L.) amazonensis in South America. It represents the “anergic” pole of American Tegumentary Leishmaniasis, and the explanation for its resistance to treatment remains elusive. We aimed to study some possible immunological mechanisms involved in the poor DCL treatment response by evaluating some cell surface molecules obtained from a patient with DCL by flow cytometry.

Case presentation

A 65-year-old DCL patient who initially failed to respond to the standard treatment for the disease showed vacuolated macrophages filled with amastigotes in lesion biopsy, and L. (L.) amazonensis was identified through ITS1PCR amplification. The Leishmania skin test and indirect immunofluorescence analysis revealed negative results. Peripheral blood from the patient was collected after a few months of treatment, when the patient presented with no lesion. Peripheral blood mononuclear cells were analyzed ex vivo and in vitro after 48 h of stimulation with soluble L. (L.) amazonensis antigen (SLA). Cell death, surface molecules, and intracellular molecules, such as IFN-γ and granzyme B, were analyzed in the cells using flow cytometry. Analysis of the surface markers showed an increased expression of the inhibitory molecule programmed death ligand 1 (PD-L1) in the monocytes restimulated with SLA (approximately 65%), whereas the negative controls were 35% positive for PD-L1. Conversely, compared with the negative controls, we observed a decrease in CD4⁺IFN-γ⁺ T cells (8.32 versus 1.7%) and CD8⁺IFN-γ⁺ T cells (14% versus 1%). We also observed a relevant decrease in the granzyme B levels in the CD8⁺ T cells, from 31% in the negative controls to 5% after SLA restimulation.

Conclusion

The dysfunctional activation of PD-L1 inhibitory pathway after Leishmania antigen stimulation and reduced levels of IFN-gamma and granzyme B-producing cells could be closely related to unresponssiveness to standard drug treatment of DCL patient.

Distinct genetic profiles of Leishmania (Viannia) braziliensis associate with clinical variations in cutaneous-leishmaniasis patients from an endemic area in Brazil

American tegumentary leishmaniasis (ATL) samples obtained from the lesions of patients with typical (n = 25, 29%), atypical (n = 60, 69%) or both (n = 2%) clinical manifestations were analysed by multilocus enzyme electrophoresis, hsp70 restriction-fragment length polymorphism (PCR-RFLP), hsp70 sequencing and phylogenetics methods. The hsp70 PCR-RFLP analysis revealed two different profiles whose the most samples differed from those expected for Leishmania braziliensis and the other Leishmania species tested: of 39 samples evaluated, two (5%) had a restriction profile corresponding to L. braziliensis, and 37 (95%) had a restriction profile corresponding to a variant pattern. A 1300-bp hsp70 gene fragment was sequenced to aid in parasite identification and a phylogenetic analysis was performed including 26 consensus sequences from the ATL patient's samples and comparing to other Leishmania and trypanosomatids species. The dendrogram allowed to observe a potential population structure of L. braziliensis complex in the studied region, emphasizing that the majority of clinical samples presented a variant genetic profile. Of interest, the L. braziliensis diversity was associated with different clinical manifestations whose parasites with hsp70 variant profile were associated with atypical lesions. The results may be helpful to improve the diagnosis, treatment and control measures of the ATL in endemic areas.

Failure of fluconazole in treating cutaneous leishmaniasis caused by Leishmania guyanensis in the Brazilian Amazon: An open, nonrandomized phase 2 trial

BACKGROUND

The treatment of Leishmaniasis caused by Leishmania (Viannia) guyanensis is based on a weak strength of evidence from very few clinical trials and some case series reports. Current treatment guidelines recommend pentamidine isethionate or meglumine antimoniate (Glucantime) as the first-line choices. Both are parenteral drugs with a low therapeutic indexes leading to a high risk of undesired effects. Imidazole derivatives interfere with the production of leishmanial ergosterol, an essential component of their membrane structure. One drug that has been studied in different clinical presentations of Leishmania is fluconazole, a hydrophilic bis-triazole, which is easily absorbed through the oral route with a low toxicity profile and is considered safe for children. This drug is readily available in poor countries with a reasonable cost making it a potential option for treating leishmaniasis.

METHODS AND FINDINGS

An adaptive nonrandomized clinical trial with sequential groups with dose escalation of oral fluconazole was designed to treat adult men with localized cutaneous leishmaniasis (LCL) in Manaus, Brazil. Eligible participants were patients with LCL with confirmed Leishmania guyanensis infection.

RESULTS

Twenty adult male patients were treated with 450 mg of fluconazole daily for 30 days. One patient (5%) was cured within 30 days of treatment. Of the 19 failures (95%), 13 developed a worsening of ulcers and six evolved lymphatic spreading of the disease. Planned dose escalation was suspended after the disappointing failure rate during the first stage of the trial.

CONCLUSION/SIGNIFICANCE

Oral fluconazole, at the dose of 450mg per day, was not efficacious against LCL caused by Leishmania guyanensis in adult men.

TRIAL REGISTRATION

Brazilian Clinical Trial Registration (ReBec)-RBR-8w292w; UTN number-1158-2421.

Drug resistance and treatment failure in leishmaniasis: A 21st century challenge

Reevaluation of treatment guidelines for Old and New World leishmaniasis is urgently needed on a global basis because treatment failure is an increasing problem. Drug resistance is a fundamental determinant of treatment failure, although other factors also contribute to this phenomenon, including the global HIV/AIDS epidemic with its accompanying impact on the immune system. Pentavalent antimonials have been used successfully worldwide for the treatment of leishmaniasis since the first half of the 20th century, but the last 10 to 20 years have witnessed an increase in clinical resistance, e.g., in North Bihar in India. In this review, we discuss the meaning of “resistance” related to leishmaniasis and discuss its molecular epidemiology, particularly for Leishmania donovani that causes visceral leishmaniasis. We also discuss how resistance can affect drug combination therapies. Molecular mechanisms known to contribute to resistance to antimonials, amphotericin B, and miltefosine are also outlined.

Chemotherapy is central to the control and management of leishmaniasis. Antimonials remain the primary drugs against different forms of leishmaniasis in several regions. However, resistance to antimony has necessitated the use of alternative medications, especially in the Indian subcontinent (ISC). Compounds, notably the orally available miltefosine (MIL), parenteral paromomycin, and amphotericin B (AmB), are increasingly used to treat leishmaniasis. Although treatment failure (TF) has been observed in patients treated with most anti-leishmanials, its frequency of appearance may be important in patients treated with MIL, which has replaced antimonials within the kala-azar elimination program in the ISC. AmB is highly efficacious, and the associated toxic effects—when administered in its free deoxycholate form—are somewhat ameliorated in its liposomal formulation. Regrettably, laboratory experimentation has demonstrated a risk of resistance towards AmB as well. The rise of drug resistance impacts treatment outcome, and understanding its causes, spread, and impact will help us manage the risks it imposes. Here, we review the problem of TF in leishmaniasis and the contribution of drug resistance to the problem. Molecular mechanisms causing resistance to anti-leishmanials are discussed along with the appropriate use of additional available drugs, as well as the urgent need to consolidate strategies to monitor drug efficacy, epidemiological surveillance, and local policies. Coordination of these activities in national and international programs against leishmaniasis might represent a successful guide to further research and prevention activities.