Plant-feeding phlebotomine sand flies, vectors of leishmaniasis, prefer Cannabis sativa.

Blood-sucking phlebotomine sand flies (Diptera: Psychodidae) transmit leishmaniasis as well as arboviral diseases and bartonellosis. Sand fly females become infected with Leishmania parasites and transmit them while imbibing vertebrates' blood, required as a source of protein for maturation of eggs. In addition, both females and males consume plant-derived sugar meals as a source of energy. Plant meals may comprise sugary solutions such as nectar or honeydew (secreted by plant-sucking homopteran insects), as well as phloem sap that sand flies obtain by piercing leaves and stems with their needle-like mouthparts. Hence, the structure of plant communities can influence the distribution and epidemiology of leishmaniasis. We designed a next-generation sequencing (NGS)-based assay for determining the source of sand fly plant meals, based upon the chloroplast DNA gene ribulose bisphosphate carboxylase large chain (rbcL). Here, we report on the predilection of several sand fly species, vectors of leishmaniasis in different parts of the world, for feeding on Cannabis sativa We infer this preference based on the substantial percentage of sand flies that had fed on C. sativa plants despite the apparent "absence" of these plants from most of the field sites. We discuss the conceivable implications of the affinity of sand flies for C. sativa on their vectorial capacity for Leishmania and the putative exploitation of their attraction to C. sativa for the control of sand fly-borne diseases.

Sterile or nonantibiotic-responsive pustular dermatitis and canine leishmaniosis: a 14 case series description and a statistical association study on 2420 cases.

Background - No striking clinical and histopathological features of pustular dermatitis (PustD) in dogs suffering from canine leishmaniosis (CanL) have been identified; an association between CanL and PustD has not been demonstrated. Objectives - To characterize a series of dogs affected by CanL and pruritic PustD, and to evaluate a possible association between the two conditions. Conclusions - An association exists between PustD and CanL. At least in Leishmania-endemic areas, CanL should be ruled out before attempting an immunosuppressive treatment in dogs with PustD with the aforementioned characteristics. Staging of CanL through diagnostic procedures besides immunohistochemistry and PCR is recommended. Anti-leishmania treatment and short-to-medium courses of low-dose anti-inflammatory or immunomodulatory drugs are effective in controlling the clinical signs of PustD.

Broad Spectrum and Safety of Oral Treatment with a Promising Nitrosylated Chalcone in Murine Leishmaniasis.

The oral efficacy and safety of a leishmanicidal nitrochalcone (CH8) were studied in BALB/c mouse infections with Leishmania amazonensis and Leishmania infantum Although 10-fold-higher doses of CH8 were needed to produce the same antiparasitic effect as that seen with the reference drug miltefosine, the latter was nephrotoxic, whereas CH8 restored disease toxicity markers to normal. This study shows the therapeutic potential of an orally active and hepato-/nephroprotective chalcone against cutaneous and visceral leishmaniases.

RIPK1 and PGAM5 Control Leishmania Replication through Distinct Mechanisms.

Leishmaniasis is an important parasitic disease found in the tropics and subtropics. Cutaneous and visceral leishmaniasis affect an estimated 1.5 million people worldwide. Despite its human health relevance, relatively little is known about the cell death pathways that control Leishmania replication in the host. Necroptosis is a recently identified form of cell death with potent antiviral effects. Receptor interacting protein kinase 1 (RIPK1) is a critical kinase that mediates necroptosis downstream of death receptors and TLRs. Heme, a product of hemoglobin catabolism during certain intracellular pathogen infections, is also a potent inducer of macrophage necroptosis. We found that human visceral leishmaniasis patients exhibit elevated serum levels of heme. Therefore, we examined the impact of heme and necroptosis on Leishmania replication. Indeed, heme potently inhibited Leishmania replication in bone marrow-derived macrophages. Moreover, we found that inhibition of RIPK1 kinase activity also enhanced parasite replication in the absence of heme. We further found that the mitochondrial phosphatase phosphoglycerate mutase family member 5 (PGAM5), a putative downstream effector of RIPK1, was also required for inhibition of Leishmania replication. In mouse infection, both PGAM5 and RIPK1 kinase activity are required for IL-1ß expression in response to Leishmania However, PGAM5, but not RIPK1 kinase activity, was directly responsible for Leishmania-induced IL-1ß secretion and NO production in bone marrow-derived macrophages. Collectively, these results revealed that RIPK1 and PGAM5 function independently to exert optimal control of Leishmania replication in the host.

Leishmania amazonensis infection impairs dendritic cell migration from the inflammatory site to the draining lymph node.

BACKGROUND: In vitro studies show that Leishmania infection decreases the adhesion of inflammatory phagocytes to connective tissue by a mechanism dependent on the modulation of integrin function. However, we know little about the influence of this reduction in leukocyte adhesion on parasite dissemination from the infection site. METHODS: In this work, we used a model of chronic peritonitis induced by thioglycollate to study the effect of L. amazonensis infection on the ability of inflammatory phagocyte populations to migrate from an inflammatory site to the draining lymph node. Uninfected or Leishmania-infected thioglycollate-elicited peritoneal exudate cells were transferred from C57BL/6 to BALB/c mice or from Ly5.1+ to Ly5.1- mice. The transferred cells were injected into the peritoneal cavity and tracked to the draining lymph node. RESULTS: Migrating cells corresponded to approximately 1% of the injected leukocytes. The proportion of migrating CD11b+CD11c+ (myeloid dendritic cell) was lower after incubation with Leishmania (1.3 to 2.6 times lower in the experiments using C57BL/6 to BALB/c animals and 2.7 to 3.4 times lower in the experiments using Ly5.1+ to Ly5.1- animals) than after leukocyte incubation with medium alone (P < 0.01). There was no consistent decrease in the migration of CD11b+F4/80+ (macrophage) or SSChi GR-1+ (neutrophil) populations. CONCLUSIONS: Coincubation with Leishmania changes the migratory pattern of dendritic cells in vivo. Such changes in dendritic cell migration may be associated with immunological events that maintain inflammation at the sites of infection.

In vitro antiparasitic activity and chemical composition of the essential oil obtained from the fruits of Piper cubeba.

Protozoans of the trypanosomatid family cause the neglected tropical diseases leishmaniasis and trypanosomiasis, for which few drugs are available. In this context our group has recently reported that the essential oil obtained by steam distillation of the fruits of Piper cubeba is active against Schistosoma mansoni. Therefore, we have investigated the in vitro effects of the essential oil against the trypomastigote and amastigote forms of Trypanosoma cruzi isolated from an LLCMK2 cell line culture and the promastigote forms of Leishmania amazonensis. The in vitro activity of the essential oil against trypomastigotes of T. cruzi increased upon rising concentrations, giving IC50 values of 45.5 and 87.9 µg ·â€ŠmL⁻¹ against trypomastigotes and amastigotes, respectively. The essential oil was not active against L. amazonensis, since it displayed lyses of only 24 % at 400 µg ·â€ŠmL⁻¹, and an IC50 of 326.5 µg ·â€ŠmL⁻¹. Therefore, the essential oil should be further investigated to determine the compounds responsible for the observed activities, as well as its mechanism of action.

Afrotropical sand fly-host plant relationships in a leishmaniasis endemic area, Kenya.

The bioecology of phlebotomine sand flies is intimately linked to the utilization of environmental resources including plant feeding. However, plant feeding behavior of sand flies remains largely understudied for Afrotropical species. Here, using a combination of biochemical, molecular, and chemical approaches, we decipher specific plant-feeding associations in field-collected sand flies from a dry ecology endemic for leishmaniasis in Kenya. Cold-anthrone test indicative of recent plant feeding showed that fructose positivity rates were similar in both sand fly sexes and between those sampled indoors and outdoors. Analysis of derived sequences of the ribulose-1,5-bisphosphate carboxylase large subunit gene (rbcL) from fructose-positive specimens implicated mainly Acacia plants in the family Fabaceae (73%) as those readily foraged on by both sexes of Phlebotomus and Sergentomyia. Chemical analysis by high performance liquid chromatography detected fructose as the most common sugar in sand flies and leaves of selected plant species in the Fabaceae family. Analysis of similarities (ANOSIM) of the headspace volatile profiles of selected Fabaceae plants identified benzyl alcohol, (Z)-linalool oxide, (E)-ß-ocimene, p-cymene, p-cresol, and m-cresol, as discriminating compounds between the plant volatiles. These results indicate selective sand fly plant feeding and suggest that the discriminating volatile organic compounds could be exploited in attractive toxic sugar- and odor- bait technologies control strategies.

Selection and phenotype characterization of potassium antimony tartrate-resistant populations of four New World Leishmania species.

In the present study, we selected in vitro populations of Leishmania Viannia guyanensis, L.V. braziliensis, L. Leishmania amazonensis and L.L. infantum chagasi that were resistant to potassium antimony tartrate (SbIII). The resistance index of these populations varied from 4- to 20-fold higher than that of their wild-type counterparts. To evaluate the stability of the resistance phenotype, these four resistant populations were passaged 37 to 47 times in a culture medium without SbIII. No change was observed in the resistance indexes of L.V. guyanensis (19-fold) and L.L. infantum chagasi (4-fold). In contrast, a decrease in the resistance index was observed for L.V. braziliensis (from 20- to 10-fold) and L.L. amazonensis (from 6- to 3-fold). None of the antimony-resistant populations exhibited cross-resistance to amphotericin B and miltefosine. However, the resistant populations of L.V. braziliensis, L.L. amazonensis and L.L. infantum chagasi were also resistant to paromomycin. A drastic reduction was observed in the infectivity in mice for the resistant L.V. guyanensis, L.L. amazonensis and L.V. braziliensis populations. The SbIII-resistant phenotype of L.V. braziliensis was stable after one passage in mice. Although the protocol of induction was the same, the SbIII-resistant populations showed different degrees of tolerance, stability, infectivity in mice and cross-resistance to antileishmanial drugs, depending on the Leishmania species.

Some aspects of intracellular parasitism.

In intracellular parasitism the host cell is a true and hospitable host. The parasite does not have to break in the door. It has subtle ways of inducing the host to open the door and welcome it in. One of the exciting fields in the future of parasitology is to find out what these ways are and why they are sometimes so highly specific that the cell that invites one parasite in will not open the door to another closely related species. Once inside, the parasite not only exploits nutrients already available in the cell, and the cell's energy-yielding system, but it further induces the cell to assist actively in its nutrition. Like a bandit who has cajoled his way in, the parasite now forces his host to prepare a banquet for him. Finally it may destroy its host cell, as in most of the associations I have described herein, or it may stimulate its host cell to abnormal increase in size or to have an altered metabolism with the formation of new products. Or it may even contribute some positive benefit to the host cell or to the multicellular organism of which the cell is a part, so that the two kinds of organisms then live together in a state of mutualism or symbiosis (26).

Label-free bioanalysis of Leishmania infantum using refractive index tomography with partially coherent illumination.

In this work, we report the use of refractive index (RI) tomography for quantitative analysis of unstained DH82 cell line infected with Leishmania infantum. The cell RI is reconstructed by using a modality of optical diffraction tomography technique that employs partially coherent illumination, thus enabling inherent compatibility with conventional wide-field microscopes. The experimental results demonstrate that the cell dry mass concentration (DMC) obtained from the RI allows for reliable detection and quantitative characterization of the infection and its temporal evolution. The RI provides important insight for studying morphological changes, particularly membrane blebbing linked to an apoptosis (cell death) process induced by the disease. Moreover, the results evidence that infected DH82 cells exhibit a higher DMC than healthy samples. These findings open up promising perspectives for clinical diagnosis of Leishmania.

Infection of Human Neutrophils With Leishmania infantum or Leishmania major Strains Triggers Activation and Differential Cytokines Release.

Leishmaniases are neglected diseases, caused by intracellular protozoan parasites of the Leishmania (L.) genus. Although the principal host cells of the parasites are macrophages, neutrophils are the first cells rapidly recruited to the site of parasites inoculation, where they play an important role in the early recognition and elimination of the parasites. The nature of early interactions between neutrophils and Leishmania could influence the outcome of infection. Herein we aimed to evaluate whether different Leishmania strains, responsible for distinct clinical manifestations, could influence ex vivo functional activity of neutrophils. Human polymorphonuclear leukocytes were isolated from 14 healthy volunteers and the ex vivo infection of these cells was done with two L. infantum and one L. major strains. Infection parameters were determined and neutrophils activation was assessed by oxidative burst, degranulation, DNA release and apoptosis; cytokine production was measured by a multiplex flow cytometry analysis. Intracellular amastigotes were rescued to determine Leishmania strains survival. The results showed that L. infantum and L. major promastigotes similarly infected the neutrophils. Oxidative burst, neutrophil elastase, myeloperoxidase activity and apoptosis were significantly increased in infected neutrophils but with no differences between strains. The L. infantum-infected neutrophils induced more DNA release than those infected by L. major. Furthermore, Leishmania strains induced high amounts of IL-8 and stimulated the production of IL-1ß, TNF-α, and TGF-ß by human neutrophils. We observed that only one strain promoted IL-6 release by these neutrophils. The production of TNF-α was also differently induced by the parasites strains. All these results demonstrate that L. infantum and L. major strains were able to induce globally a similar ex vivo activation and apoptosis of neutrophils; however, they differentially triggered cytokines release from these cells. In addition, rescue of intracellular parasites indicated different survival rates further emphasizing on the influence of parasite strains within a species on the fate of infection.

Macrophages From Subjects With Isolated GH/IGF-I Deficiency Due to a GHRH Receptor Gene Mutation Are Less Prone to Infection by Leishmania amazonensis.

Isolated growth hormone (GH) deficiency (IGHD) affects approximately 1 in 4,000 to 1 in 10,000 individuals worldwide. We have previously described a large cohort of subjects with IGHD due to a homozygous mutation in the GH releasing hormone (GHRH) receptor gene. These subjects exhibit throughout the life very low levels of GH and its principal mediator, the Insulin Growth Factor-I (IGF-I). The facilitating role of IGF-I in the infection of mouse macrophages by different Leishmania strains is well-known. Nevertheless, the role of IGF-I in Leishmania infection of human macrophages has not been studied. This study aimed to evaluate the behavior of Leishmania infection in vitro in macrophages from untreated IGHD subjects. To this end, blood samples were collected from 14 IGHD individuals and 14 age and sex-matched healthy controls. Monocytes were isolated and derived into macrophages and infected with a strain of Leishmania amazonensis. In addition, IGF-I was added to culture medium to evaluate its effect on the infection. Cytokines were measured in the culture supernatants. We found that macrophages from IGHD subjects were less prone to Leishmania infection compared to GH sufficient controls. Both inflammatory and anti-inflammatory cytokines increase only in the supernatants of the control macrophages. Addition of IGF-I to the culture medium increased infection rates. In conclusion, we demonstrated that IGF-I is crucial for Leishmania infection of human macrophages.

Conventional Versus Natural Alternative Treatments for Leishmaniasis: A Review.

Leishmaniasis is a neglected disease caused by protozoan belonging to the Leishmania genus. There are at least 16 pathogenic species for humans that are able to cause different clinical forms, such as cutaneous or visceral leishmaniasis. In spite of the different species and clinical forms, the treatment is performed with few drug options that, in most cases, are considered outdated. In addition, patients under classical treatment show serious side effects during drug administration, moreover parasites are able to become resistant to medicines. Thus, it is believed and well accepted that is urgent and necessary to develop new therapeutic options to overpass these concerns about conventional therapy of leishmaniasis. The present review will focus on the efficacy, side effects and action mechanism of classic drugs used in the treatment of leishmaniasis, as well as the importance of traditional knowledge for directing a rational search toward the discovery and characterization of new and effective molecules (in vivo assays) from plants to be used against leishmaniasis.

Analysis of the Antigenic and Prophylactic Properties of the Leishmania Translation Initiation Factors eIF2 and eIF2B in Natural and Experimental Leishmaniasis.

Different members of intracellular protein families are recognized by the immune system of the vertebrate host infected by parasites of the genus Leishmania. Here, we have analyzed the antigenic and immunogenic properties of the Leishmania eIF2 and eIF2B translation initiation factors. An in silico search in Leishmania infantum sequence databases allowed the identification of the genes encoding the α, ß, and γ subunits and the α, ß, and δ subunits of the putative Leishmania orthologs of the eukaryotic initiation factors F2 (LieIF2) or F2B (LieIF2B), respectively. The antigenicity of these factors was analyzed by ELISA using recombinant versions of the different subunits. Antibodies against the different LieIF2 and LieIF2B subunits were found in the sera from human and canine visceral leishmaniasis patients, and also in the sera from hamsters experimentally infected with L. infantum. In L. infantum (BALB/c) and Leishmania major (BALB/c or C57BL/6) challenged mice, a moderate humoral response against these protein factors was detected. Remarkably, these proteins elicited an IL-10 production by splenocytes derived from infected mice independently of the Leishmania species employed for experimental challenge. When DNA vaccines based on the expression of the LieIF2 or LieIF2B subunit encoding genes were administered in mice, an antigen-specific secretion of IFN-γ and IL-10 cytokines was observed. Furthermore, a partial protection against murine CL development due to L. major infection was generated in the vaccinated mice. Also, in this work we show that the LieIF2α subunit and the LieIF2Bß and δ subunits have the capacity to stimulate IL-10 secretion by spleen cells from naïve mice. B-lymphocytes were identified as the major producers of this anti-inflammatory cytokine. Taking into account the data found in this study, it may be hypothesized that these proteins act as virulence factors implicated in the induction of humoral responses as well as in the production of the down-regulatory IL-10 cytokine, favoring a pathological outcome. Therefore, these proteins might be considered markers of disease.

Association between canine leishmaniosis and Ehrlichia canis co-infection: a prospective case-control study.

BACKGROUND: In the Mediterranean basin, Leishmania infantum is a major cause of disease in dogs, which are frequently co-infected with other vector-borne pathogens (VBP). However, the associations between dogs with clinical leishmaniosis (ClinL) and VBP co-infections have not been studied. We assessed the risk of VBP infections in dogs with ClinL and healthy controls. METHODS: We conducted a prospective case-control study of dogs with ClinL (positive qPCR and ELISA antibody for L. infantum on peripheral blood) and clinically healthy, ideally breed-, sex- and age-matched, control dogs (negative qPCR and ELISA antibody for L. infantum on peripheral blood) from Paphos, Cyprus. We obtained demographic data and all dogs underwent PCR on EDTA-blood extracted DNA for haemoplasma species, Ehrlichia/Anaplasma spp., Babesia spp., and Hepatozoon spp., with DNA sequencing to identify infecting species. We used logistic regression analysis and structural equation modelling (SEM) to evaluate the risk of VBP infections between ClinL cases and controls. RESULTS: From the 50 enrolled dogs with ClinL, DNA was detected in 24 (48%) for Hepatozoon spp., 14 (28%) for Mycoplasma haemocanis, 6 (12%) for Ehrlichia canis and 2 (4%) for Anaplasma platys. In the 92 enrolled control dogs, DNA was detected in 41 (45%) for Hepatozoon spp., 18 (20%) for M. haemocanis, 1 (1%) for E. canis and 3 (3%) for A. platys. No Babesia spp. or "Candidatus Mycoplasma haematoparvum" DNA was detected in any dog. No statistical differences were found between the ClinL and controls regarding age, sex, breed, lifestyle and use of ectoparasitic prevention. A significant association between ClinL and E. canis infection (OR = 12.4, 95% CI: 1.5-106.0, P = 0.022) was found compared to controls by multivariate logistic regression. This association was confirmed using SEM, which further identified that younger dogs were more likely to be infected with each of Hepatozoon spp. and M. haemocanis, and dogs with Hepatozoon spp. were more likely to be co-infected with M. haemocanis. CONCLUSIONS: Dogs with ClinL are at a higher risk of co-infection with E. canis than clinically healthy dogs. We recommend that dogs diagnosed with ClinL should be tested for E. canis co-infection using PCR.

Comparative genomics: from genotype to disease phenotype in the leishmaniases.

Recent progress in sequencing the genomes of several Leishmania species, causative agents of cutaneous, mucocutaneous and visceral leishmaniasis, is revealing unusual features of potential relevance to parasite virulence and pathogenesis in the host. While the genomes of Leishmania major, Leishmania braziliensis and Leishmania infantum are highly similar in content and organisation, species-specific genes and mechanisms distinguish one from another. In particular, the presence of retrotransposons and the components of a putative RNA interference machinery in L. braziliensis suggest the potential for both greater diversity and more tractable experimentation in this Leishmania Viannia species.

Leishmania amazonensis infection induces behavioral alterations and modulates cytokine and neurotrophin production in the murine cerebral cortex.

Neurological symptoms have been associated with Leishmania infection, however little is known about how the nervous system is affected in leishmaniasis. This work aimed to analyze parasitic load, production of cytokines/neurotrophins in the prefrontal cortex and behavioral changes in BALB/c mice infected with Leishmania amazonensis. At 2 and 4months post-infection, infected mice showed a decrease in IFN-γ, IL-1, IL-6, IL-4, IL-10 cytokines and BDNF and NGF neurotrophins in prefrontal cortex associated with increased anxiety behavior. Parasite DNA was found in brain of all animals at 4months post-infection, when the levels of IBA-1 (activated macrophage/microglia marker) and TNF-α was increased in the prefrontal cortex. However TNF-α returned to normal levels at 6months post-infection suggesting a neuroprotective mechanism.

Serologic evidence of mixed infection involving the zoonoses leishmaniasis and leptospirosis in Greek dogs.

Leishmaniasis, an important zoonosis, was serologically found to coexist with leptospirosis, another important zoonosis. The proportion of dogs positive to leishmaniasis was approximately 36%. Significant differences were observed between dogs located in greater Athens and those from rural Greece. Although dogs from either of the groups had a similar chance to be infected, rural dogs had significantly (p<0.01) higher titers (1/1,600) than dogs from greater Athens. Thirty two of the 344 dog serum samples examined had positive antibody titers against Leptospira spp., but only 13 of them had titers of 1/400 or over to both of the infectious agents. Whilst noted differences in the antibody titers of samples with evidence of leishmaniasis and leptospirosis were not observed their coexistence may complicate the clinical outcome of cases of mixed infection.

[Duration and character of the course of cutaneous leishmaniasis in the midday gerbil (Meriones meridianus Pall.)]. / Prodolzhitel'nost' i kharakter techeniia kozhnogo leishmanioza u poludennoi peschanki (Meriones meridianus Pall.)

The development of the infection process during cutaneous leishmaniosis was traced in one midday gerbil (Meriones meridianus Pall). The gerbil fell ill with cutaneous leishmaniosis after the feeding of san flies of Phlebotomus papatasi and Ph. mongolensis on it. The incubation process of the disease was less than 23 days. Leishmaniosic process began at the base of the concha auriculae and caused the destruction of ear tissues. The complete recover set in 67 days after the infection. Thus, the insignificant duration of the disease does not allow leishmaniae to be preserved in midday gerbils from one season to another.

Vaginal canine transmissible venereal tumour associated with intra-tumoural Leishmania spp. amastigotes in an asymptomatic female dog.

A 2-year-old female boxer dog was presented with a vaginal serosanguineous discharge not associated with oestrus. There was a friable mass occupying the upper caudal part of the vagina. Cytological and histological examination revealed a monomorphic population of neoplastic round cells consistent with canine transmissible venereal tumour (TVT). In addition, Leishmania spp. amastigotes were found within the neoplastic tissue. In order to characterize whether the amastigotes were present inside macrophages and/or neoplastic cells, a co-localization study using cell- and pathogen-specific markers was performed. To detect Leishmania spp. a 5.8S ribosomal RNA (rRNA) parasite-specific sequence was used for in-situ hybridization and Mac387 was used as a macrophage marker for immunohistochemistry. Leishmania spp. rRNA was detected inside Mac387(+) macrophages and within the cytoplasm of some neoplastic cells. DNA isolation and polymerase chain reaction using specific primers and sequencing analysis identified the organism as Leishmania infantum (syn. Leishmania chagasi). This is the first report describing infection of tumour cells by L. infantum in a genital TVT from an asymptomatic bitch. Transplantation of Leishmania-laden neoplastic cells could represent an alternative route of venereal transmission of leishmaniasis among dogs.