Braziliensis Infection Research Articles

English

The effect of a quinone fraction (QF) isolated from the heartwood of Auxemma oncocalyx Taub. was investigated in vitro and in vivo on Leishmania braziliensis. Although QF (1-10 μg/mL) showing marked in vitro anti-Leishmania activity (81 to 94%), the oral treatment with the compound did not protect hamsters against progressive L. braziliensis infection. When QF was administered intraperitoneally (20 mg/kg) the lesion size was reduced by 65%; however, it was not able to promote parasite eradication, as evidenced by the high number of parasites in draining lymph nodes. Quinones are highly redox active molecules and with their semiquinones radicals can lead to formation of reactive oxygen species (ROS). The generation of ROS could probably explain the in vitro leishmanicidal activity of the quinones, since promastigotes are susceptible to H2O2 lethal effect in vitro. In conclusion, although quinones seem to be effective against Leishmania parasites in vitro, they do not demonstrate a therapeutic effect in experimental leishmaniasis. In addition, it can be hypothesized that QF in vivo might possibly be converted into non-active metabolite(s) or be inactivated either by reduction or by interaction with serum proteins, losing its leishmanicidal activity. Key words: Leishmania braziliensis, Auxemma oncocalyx, quinone, hamster, cutaneous leishmaniasis.

Intranasal vaccination with leishmanial antigens protects golden hamsters (Mesocricetus auratus) against Leishmania (Viannia) Braziliensis infection.

BackgroundPrevious results have shown that oral and intranasal administration of particulate Leishmania (Leishmania) amazonensis antigens (LaAg) partially protects mice against L. amazonensis infection. However, vaccination studies on species of the subgenus Viannia, the main causative agent of cutaneous and mucosal leishmaniasis in the Americas, have been hampered by the lack of easy-to-handle bio-models that accurately mimic the human disease. Recently, we demonstrated that the golden hamster is an appropriate model for studying the immunopathogenesis of cutaneous leishmaniasis caused by L. (Viannia) braziliensis. Using the golden hamster model, our current study investigated whether the protective effect of intranasal immunisation with LaAg can be extended to L. braziliensis infection.Methodology/Principal FindingsGolden hamsters vaccinated with either two intranasal (IN) doses of LaAg (10 µg) or two intramuscular doses of LaAg (20 µg) were challenged 2 weeks post-vaccination with L. braziliensis. The results showed that IN immunisation with LaAg significantly reduced lesion growth and parasitic load as well as serum IgG and IgG2 levels. At the experimental endpoint on day 114 post-infection, IN-immunised hamsters that were considered protected expressed IFN-γ and IL10 mRNA levels that returned to uninfected skin levels. In contrast to the nasal route, intramuscular (IM) immunisation failed to provide protection.Conclusions/SignificanceThese results demonstrate for the first time that the nasal route of immunisation can induce cross protection against L. braziliensis infection.

Matrix metalloproteinase 9 production by monocytes is enhanced by TNF and participates in the pathology of human cutaneous Leishmaniasis.

IntroductionCutaneous leishmaniasis (CL) due to L.braziliensis infection is characterized by a strong inflammatory response with high levels of TNF and ulcer development. Less attention has been given to the role of mononuclear phagocytes to this process. Monocytes constitute a heterogeneous population subdivided into classical, intermediate and non-classical, and are known to migrate to inflammatory sites and secrete inflammatory mediators. TNF participates in the induction of matrix metalloproteinases (MMPs). MMP-9 is an enzyme that degrades basal membrane and its activity is controlled by the tissue inhibitor of metalloproteinase.MethodsMononuclear cells were obtained from ex-vivo labeling sub-populations of monocytes and MMP-9, and the frequency was determined by flow cytometry. Culture was performed during 72 hours, stimulating the cells with SLA, levels of MMP-9 and TIMP-1 in the supernatants were determined by ELISA.ResultsWe observed that cells from CL lesions secrete high amounts of MMP-9 when compared to healthy subjects. Although MMP-9 was produced by monocytes, non-classical ones were the main source of this enzyme. We also observed that TNF produced in high level during CL contributes to MMP-9 production.ConclusionsThese observations emphasize the role of monocytes, TNF and MMP-9 in the pathogenesis of L. braziliensis infection.

Chemotherapeutic potential of 17-AAG against cutaneous leishmaniasis caused by Leishmania (Viannia) braziliensis.

BackgroundLeishmaniasis remains a worldwide public health problem. The limited therapeutic options, drug toxicity and reports of resistance, reinforce the need for the development of new treatment options. Previously, we showed that 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), a Heat Shock Protein 90 (HSP90)-specific inhibitor, reduces L. (L.) amazonensis infection in vitro. Herein, we expand the current knowledge on the leishmanicidal activity of 17-AAG against cutaneous leishmaniasis, employing an experimental model of infection with L. (V.) braziliensis.Methodology/Principal findingsExposure of axenic L. (V.) braziliensis promastigotes to 17-AAG resulted in direct dose-dependent parasite killing. These results were extended to L. (V.) braziliensis-infected macrophages, an effect that was dissociated from the production of nitric oxide (NO), superoxide (O−2) or inflammatory mediators such as TNF-α, IL-6 and MCP-1. The leishmanicidal effect was then demonstrated in vivo, employing BALB/c mice infected with L. braziliensis. In this model, 17-AAG treatment resulted in smaller skin lesions and parasite counts were also significantly reduced. Lastly, 17-AAG showed a similar effect to amphotericin B regarding the ability to reduce parasite viability.Conclusion/Significance17-AAG effectively inhibited the growth of L. braziliensis, both in vitro and in vivo. Given the chronicity of L. (V.) braziliensis infection and its association with mucocutaneous leishmaniasis, 17-AAG can be envisaged as a new chemotherapeutic alternative for cutaneous Leishmaniasis.

Can Equids Be a Reservoir of Leishmania braziliensis in Endemic Areas?

In this study, we detected Leishmania (Viannia) braziliensis infection in equids living in endemic regions of cutaneous leishmaniasis. To determine the role of these animals in the Leishmania cycle, we used two approaches: serological and molecular methods. Antibodies to the parasite were assayed using the Enzyme Linked Immunosorbent Assay (ELISA). Blood samples were collected and tested by polymerase chain reaction (PCR), and the positive products were sequenced. The results showed that 11.0% (25/227) of the equids were seropositive for Leishmania sp, and 16.3% (37/227) were PCR positive. Antibodies were detected in 20 horses, 3 donkeys, and 2 mules, and the parasite DNA was detected in 30 horses, 5 donkeys, and 2 mules. Sequencing the amplified DNA revealed 100% similarity with sequences for Viannia complex, corroborating the results of PCR for L. braziliensis. Our results show that equids are infected with L. braziliensis, which could be food sources for phlebotomines in the peridomiciliary environment and consequently play a role in the cutaneous leishmaniasis cycle.

The role of inflammatory and anti-inflammatory cytokines in the pathogenesis of human tegumentary leishmaniasis

In tegumentary leishmaniasis caused by Leishmania braziliensis, there is evidence that increased production of IFN-γ, TNF-α and absence of IL-10 is associated with strong inflammatory reaction and with tissue destruction and development of the lesions observed in cutaneous leishmaniasis (CL) and mucosal leishmaniasis (ML). We evaluate the role of regulatory cytokines and cytokine antagonists in the downregulation of immune response in L. braziliensis infection. Peripheral blood mononuclear cells from CL and ML were stimulated with soluble Leishmania antigen in the presence or absence of regulatory cytokines (IL-10, IL-27 and TGF-β) or antagonists of cytokines (α-TNF-α and α-IFN-γ). Cytokines production (IL-10, IL-17, TNF-α and IFN-γ) was measured by ELISA. IL-10 and TGF-β downmodulate TNF-α and IL-17 production, whereas IL-27 had no effect in the production of TNF-α, IFN-γ and IL-17 in these patients. Neutralization of TNF-α decreased IFN-γ level and the neutralization of IFN-γ decreased TNF-α level and increased IL-10 production. This study demonstrate that IL-10 and TGF-β are cytokines that appear to be more involved in modulation of immune response in CL and ML patients. IL-10 might have a protective role, since the neutralization of IFN-γ decreases the production of TNF-α in an IL-10-dependent manner.

Leishmania braziliensis-Reactive T Cells Are Down-Regulated in Long-Term Cured Cutaneous Leishmaniasis, but the Renewal Capacity of T Effector Memory Compartments Is Preserved

Leishmania (Viannia) braziliensis control and tissue damage relate to the effector immune response, which in turn affects clinical outcome. Leishmania reactive CD4+ and CD8+ T cells are expanded in long-term healed cutaneous leishmaniasis (hCL) patients but their functional characteristics remain to be determined. This study investigates antigen-specific recall in long-term healed CL caused by L. braziliensis infection. Healed CL subjects were grouped according to the time elapsed since the end of therapy: less than two years and two to five years. Activation phenotype (CD69+ or CD25+) and subpopulations of memory T cell phenotypes [central memory (Tcm): CD45RO+ CCR7+ or effector memory (Tem): CD45RO+ CCR7-] were quantified in ex vivo blood mononuclear cells and after Leishmania antigens stimuli. A reduction in the percentage of activated Leishmania-responder CD4+ and CD8+ T cells in hCL was associated with the time elapsed since clinical cure. Percentage of CD69+ in TCD4+ and TCD8+ cells were negatively correlated with IL-10 levels. Ex vivo analyses showed contracted Tem CD4+ and Tem CD8+ compartments from hCL with long time elapsed since clinical cure, although renewal of these compartments was observed following in vitro exposure to leishmanial stimuli. Our results show that healed L. braziliensis infected patients exhibit a recall response to Leishmania antigens with evident expansion of effector memory T cells. Regulated leishmanial-specific response seems to emerge only about two years after initial contact with the parasite antigens.

Small mammals as hosts of Leishmania spp. in a highly endemic area for zoonotic leishmaniasis in north-eastern Brazil

Leishmania parasites cause leishmaniasis in humans and animals worldwide. These parasites are transmitted by phlebotomine sand flies, which become infected upon feeding on an infected mammalian host. We assessed the occurrence of Leishmania infection in small mammals in an area of cutaneous and visceral leishmaniasis endemicity. A total of 180 small mammals were trapped in 2003 and 2006 in a rural area in north-eastern Brazil. Spleen and skin samples from these animals were assessed by two PCR protocols, one targeting Leishmania (Viannia) spp. and other Leishmania (Leishmania) infantum. Additionally, serum samples were tested by an immunochromatographic test with rK39 as antigen. Overall, 23.2% (38/164) of the animals were positive to L. (V.) spp. and 8.8% (14/160) to L. (L.) infantum). Five animals of four species (Didelphis albiventris, Nectomys squamipes, Rattus rattus and Holochilus sciureus) were positive by both PCR protocols, an overall co-infection rate of 2.5%. By serology, 5% (7/139) of the animals were positive, but all of them were PCR-negative. An isolate obtained from a water rat (N. squamipes) was characterized as L. (V.) braziliensis (zymodeme Z-74). This study reinforces the involvement of different small mammals (e.g., N. squamipes, R. rattus and H. scieurus) in the transmission cycles of L. (V.) braziliensis and L. (L.) infantum in north-eastern Brazil. The finding of L. (V.) braziliensis infection in black rats suggests a rapid process of adaptation of a New World Leishmania species to an Old World rodent and raises interesting questions regarding the co-evolution of these parasites and their vertebrate hosts.

Functional Transcriptomics of Wild-Caught Lutzomyia intermedia Salivary Glands: Identification of a Protective Salivary Protein against Leishmania braziliensis Infection

Background Leishmania parasites are transmitted in the presence of sand fly saliva. Together with the parasite, the sand fly injects salivary components that change the environment at the feeding site. Mice immunized with Phlebotomus papatasi salivary gland (SG) homogenate are protected against Leishmania major infection, while immunity to Lutzomyia intermedia SG homogenate exacerbated experimental Leishmania braziliensis infection. In humans, antibodies to Lu. intermedia saliva are associated with risk of acquiring L. braziliensis infection. Despite these important findings, there is no information regarding the repertoire of Lu. intermedia salivary proteins.Methods and FindingsA cDNA library from the Salivary Glands (SGs) of wild-caught Lu. intermedia was constructed, sequenced, and complemented by a proteomic approach based on 1D SDS PAGE and mass/mass spectrometry to validate the transcripts present in this cDNA library. We identified the most abundant transcripts and proteins reported in other sand fly species as well as novel proteins such as neurotoxin-like proteins, peptides with ML domain, and three small peptides found so far only in this sand fly species. DNA plasmids coding for ten selected transcripts were constructed and used to immunize BALB/c mice to study their immunogenicity. Plasmid Linb-11—coding for a 4.5-kDa protein—induced a cellular immune response and conferred protection against L. braziliensis infection. This protection correlated with a decreased parasite load and an increased frequency of IFN-γ-producing cells.ConclusionsWe identified the most abundant and novel proteins present in the SGs of Lu. intermedia, a vector of cutaneous leishmaniasis in the Americas. We also show for the first time that immunity to a single salivary protein from Lu. intermedia can protect against cutaneous leishmaniasis caused by L. braziliensis.

Dual effect of Lutzomyia longipalpis saliva on Leishmania braziliensis infection is mediated by distinct saliva-induced cellular recruitment into BALB/c mice ear

BackgroundLeishmania parasites are transmitted to their vertebrate hosts by infected Phlebotomine sand flies during the blood meal of the flies. Sand fly saliva is known to enhance Leishmania spp. infection, while pre-exposure to saliva protects mice against parasitic infections. In this study, we investigated the initial inflammatory leucocyte composition induced by one or three inocula of salivary gland extract (SGE) from Lutzomyia longipalpis in the presence or absence of Leishmania braziliensis.ResultsWe demonstrated that inoculating SGE once (SGE-1X) or three times (SGE-3X), which represented a co-inoculation or a pre-exposure to saliva, respectively, resulted in different cellular infiltrate profiles. Whereas SGE-1X led to the recruitment of all leucocytes subtypes including CD4+ T cells, CD4+CD25+ T cells, dendritic cells, macrophages and neutrophils, the immune cell profile in the SGE-3X group differed dramatically, as CD4+ T cells, CD4+CD25+ T cells, dendritic cells, macrophages and neutrophils were decreased and CD8+ T cells were increased. The SGE-1X group did not show differences in the ear lesion size; however, the SGE-1X group harbored a higher number of parasites. On the other hand, the SGE-3X group demonstrated a protective effect against parasitic disease, as the parasite burden was lower even in the earlier stages of the infection, a period in which the SGE-1X group presented with larger and more severe lesions. These effects were also reflected in the cytokine profiles of both groups. Whereas the SGE-1X group presented with a substantial increase in IL-10 production, the SGE-3X group showed an increase in IFN-γ production in the draining lymph nodes. Analysis of the inflammatory cell populations present within the ear lesions, the SGE-1X group showed an increase in CD4+FOXP3+ cells, whereas the CD4+FOXP3+ population was reduced in the SGE-3X group. Moreover, CD4+ T cells and CD8+ T cells producing IFN-γ were highly detected in the ears of the SGE-3X mice prior to infection. In addition, upon treatment of SGE-3X mice with anti-IFN-γ monoclonal antibody, we observed a decrease in the protective effect of SGE-3X against L. braziliensis infection.ConclusionsThese results indicate that different inocula of Lutzomyia longipalpis salivary gland extract can markedly modify the cellular immune response, which is reflected in the pattern of susceptibility or resistance to Leishmania braziliensis infection.

Clinical complexity of Leishmania (Viannia) braziliensis infections amongst travelers

The protozoan parasite Leishmania (Viannia) braziliensis is one of the main causes of cutaneous and mucocutaneous leishmaniasis in South America. Here, we describe three cases of L.(V.)braziliensis infection which were acquired during travelling in Bolivia, Peru or Paraguay and illustrate the phenotypic heterogeneity and therapeutic complexity of the disease. Two patients presented with unusual clinical manifestations, i.e. with prominent regional lymphadenopathy ("bubonic leishmaniasis") and with simultaneously emerged skin and mucosal lesions, respectively. Both patients insufficiently responded to oral treatment with miltefosine; resolution of the lesions was only achieved after a course of intravenous liposomal amphotericin B.

Vaccination with L. infantum chagasi Nucleosomal Histones Confers Protection against New World Cutaneous Leishmaniasis Caused by Leishmania braziliensis

BackgroundNucleosomal histones are intracellular proteins that are highly conserved among Leishmania species. After parasite destruction or spontaneous lysis, exposure to these proteins elicits a strong host immune response. In the present study, we analyzed the protective capability of Leishmania infantum chagasi nucleosomal histones against L. braziliensis infection using different immunization strategies.Methodology/Principal FindingsBALB/c mice were immunized with either a plasmid DNA cocktail (DNA) containing four Leishmania nucleosomal histones or with the DNA cocktail followed by the corresponding recombinant proteins plus CpG (DNA/Protein). Mice were later challenged with L. braziliensis, in the presence of sand fly saliva. Lesion development, parasite load and the cellular immune response were analyzed five weeks after challenge. Immunization with either DNA alone or with DNA/Protein was able to inhibit lesion development. This finding was highlighted by the absence of infected macrophages in tissue sections. Further, parasite load at the infection site and in the draining lymph nodes was also significantly lower in vaccinated animals. This outcome was associated with increased expression of IFN-γ and down regulation of IL-4 at the infection site.ConclusionThe data presented here demonstrate the potential use of L. infantum chagasi nucleosomal histones as targets for the development of vaccines against infection with L. braziliensis, as shown by the significant inhibition of disease development following a live challenge.

Leishmania (Viannia) braziliensis infection in two Colombian dogs: a note on infectivity for sand flies and response to treatment

Although canine cutaneous leishmaniasis has been reported in several foci of South America, no published information from Colombia is available. We report on two cases found in the Pacific coast region of this country, which presented as a single scrotal ulcer in one dog, and two ulcers on the external surface of the ear in a second dog. Parasites were isolated by culture in Senekjie's culture medium and identified using monoclonal antibodies. The capacity of these dogs to transmit the parasites to sand fly vectors (Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia longipalpis, Lutzomyia youngi) was tested by allowing the flies to feed on the lesion borders. Both isolates were identified as Leishmania (Viannia) braziliensis. No infections were detected upon dissection of engorged flies. A single peri-and sub-lesional injection of 1-2 ml of pentavalent antimony in the dog with ear lesions resulted in clinical cure 6 weeks post-treatment. These observations suggest that although dogs are susceptible to L. braziliensis, their reservoir competence could be low. However, if further studies indicate that canines are capable reservoir hosts of L. Viannia spp., the local treatment of lesions could become a feasible approach to diminish the risk of human infection in the peridomestic setting, without sacrificing infected dogs.

Transcriptome Patterns from Primary Cutaneous Leishmania braziliensis Infections Associate with Eventual Development of Mucosal Disease in Humans

IntroductionLocalized Cutaneous Leishmaniasis (LCL) and Mucosal Leishmaniasis (ML) are two extreme clinical forms of American Tegumentary Leishmaniasis that usually begin as solitary primary cutaneous lesions. Host and parasite factors that influence the progression of LCL to ML are not completely understood. In this manuscript, we compare the gene expression profiles of primary cutaneous lesions from patients who eventually developed ML to those that did not.MethodsUsing RNA-seq, we analyzed both the human and Leishmania transcriptomes in primary cutaneous lesions.ResultsLimited number of reads mapping to Leishmania transcripts were obtained. For human transcripts, compared to ML patients, lesions from LCL patients displayed a general multi-polarization of the adaptive immune response and showed up-regulation of genes involved in chemoattraction of innate immune cells and in antigen presentation. We also identified a potential transcriptional signature in the primary lesions that may predict long-term disease outcome.ConclusionsWe were able to simultaneously sequence both human and Leishmania mRNA transcripts in primary cutaneous leishmaniasis lesions. Our results suggest an intrinsic difference in the immune capacity of LCL and ML patients. The findings correlate the complete cure of L. braziliensis infection with a controlled inflammatory response and a balanced activation of innate and adaptive immunity.

P015 TSLP enhances type 1 immune response in cutaneous leishmaniasis patients

Introduction Leucocytes from cutaneous leishmaniasis (CL) patients due to L. braziliensis infection secrete high levels of IFN-gamma and TNF-alpha in response to soluble Leishmania antigen (SLA) and at lesion site. This type of immune response helps to control parasite multiplication but also mediates tissue damage and lesion development. Thus, we think CL patients would benefit from a balanced Th1/Th2 immune response. It has been shown that cells that do not classically participate in immune response, such as epithelial cells, can secrete soluble factors interfering on T cells responses to pathogens. Thymic stromal lymphopoietin (TSLP) is a recently described cytokine secreted by epithelial cells. TSLP-activated macrophages and dendritic cells enhance IL-4 and IL-13 secretion by memory CD4+ T cells in asthma and helminthes infections. Methods Peripheral blood mononuclear cells were obtained from CL individuals. Cells were stimulated with soluble Leishmania antigen or D. pteronyssinus in presence or absence of recombinant TSLP for 72 h. Cytokines were measured in cell culture supernatants by ELISA. For immunohistochemistry, biopsies were obtained from CL patients and stained for TSLP. Results Since TSLP induces Th2 responses, our hypothesis was that presence of TSLP would conditionate antigen presenting cells to enhance SLA-induced Th2 responses in CL patients decreasing levels of Th1 cytokines. Surprisingly, our data shows that in presence of TSLP, SLA-stimulated PBMC from CL individuals enhance IFN-gamma production, instead. No change in SLA-induced IL-5, TNF-alpha and IL-10 was observed. To test the effect of TSLP on antigens known to induce Th2 responses, we stimulated cells from the same patients with D. pteronyssinus (Derp) antigen in presence or absence of TSLP. As expected, presence of TSLP enhanced Derp-induced IL-5 production. The fact that TSLP can be expressed by skin epithelial cells, led us to investigate whether there was presence of TSLP in lesion of CL patients. Immunohistochemistry reveled TSLP expression in epithelial cells, endothelial cells and macrophages from CL individuals. We finally asked if Leishmania infection would interfere on TSLP receptor expression in monocytes. L. braziliensis-infected monocytes from healthy individuals up-regulated TSLP receptor expression. Conclusion Our results show a novel role for TSLP in inducing up-regulation of IFN-gamma production in CL patients. These data suggest that presence of TSLP may contribute for parasite killing and also maintenance of inflammatory response in these patients.

Liposomal amphotericin B in comparison to sodium stibogluconate for Leishmania braziliensis cutaneous leishmaniasis in travelers

New World cutaneous leishmaniasis is mostly acquired in the Amazon Basin of Bolivia where L viannia (V) braziliensis is endemic. Treatment with systemic pentavalent antimonial compounds has been shown to be effective in achieving clinical cure in only 75% of cases. We sought to assess the efficacy and safety of liposomal amphotericin B (L-AmB) treatment for primary infection of cutaneous L (V) braziliensis. A prospective observational evaluation was performed for cutaneous leishmaniasis due to L (V) braziliensis which was treated with L-AmB, 3 mg/kg, for 5 consecutive days, and a sixth dose on day 10. This therapy regimen was compared with the treatment regimen of sodium stibogluconate (SSG) 20 mg/kg for 3 weeks. Our study was divided into two groups; 34 patients received L-AmB and 34 received SSG treatment. Almost all patients were infected in Bolivia. In the L-AmB group, 29 patients (85%) had complete cure compared with 70% in the SSG group (P = not significant), 4 other patients were slow healers, and only one patient needed additional treatment with SSG. No relapses were seen during a mean 29-month follow-up period. Failure rate was 3% in the L-AmB versus 29% in the SSG group (P = .006). Treatment was interrupted in 65% of patients taking SSG because of adverse events, whereas all patients receiving L-AmB completed treatment. This was a non-blinded comparative study. Comparison of L-Amb to SSG treatment for L (V) braziliensis shows that the former is effective, better tolerated, and more cost effective. L-AmB should therefore be considered as the first-line treatment option for cutaneous L (V) braziliensis infection.

A mixed Th1/Th2 response induces optimal resistance to Leishmania braziliensis (43.21)

Abstract Leishmania braziliensis is a protozoan that causes cutaneous lesions that heal spontaneously or induces a disease where the parasites metastasize to the nasopharyngeal mucosa. The factors responsible for the severe forms of the disease remain poorly understood, but an exaggerated Th1 response is associated with the immunopathology observed in these patients. In the absence of IFN-γ or iNOS mice are extremely susceptible to L. braziliensis, indicating that Th1 responses are essential to control these parasites. However, we hypothesized that a more moderated response might be associated with less pathology. Since we previously found that CD8 T cells inhibit a Th2 response in leishmaniasis, we tested whether depletion of CD8 T cells might promote a mixed Th1/Th2 response and less pathology. In fact, BALB/c mice infected with L. braziliensis and depleted of CD8 T cells developed smaller lesions, and unexpectedly were better able to control the parasites. This enhanced protection was accompanied by an increase in IL-4 and IL-5 levels, and an infiltration of neutrophils and eosinophils into the lesions. Eosinophils were essential for the increased resistance, since the protective effect of anti-CD8 treatment was reversed when mice were depleted of eosinophils by anti-CCR3 or anti-IL-5 monoclonal antibodies. Taken together, these data demonstrate that a mixed Th1/Th2 response induces optimal control of a L. braziliensis infection, and eosinophils are required for this outcome.

Reply to Torres and Suarez

To the Editor—We appreciate Drs Torres and Suarez's interest in our article, “High-Dose Oral Fluconazole Therapy Effective for Cutaneous Leishmaniasis Due to Leishmania (Vianna) braziliensis” [1]. They refer to evidence of Leishmania amazonensis isolated from human as well as domestic and wild reservoir hosts from the state of Ceara and suggest it is an important etiologic agent of cutaneous leishmaniasis in the region. Concerning human hosts, their statement is based on 2 publications [2, 3] that showed a single isolate of L. amazonensis from only 1 human case of cutaneous leishmaniasis. Both articles deal with the same parasite grown from a human skin biopsy sample in 1984. Because that event was so rare, the question as to whether it was an imported case remains. In respect to domestic and wild reservoirs of L. amazonensis in the state of Ceara, there is no proof of isolates of L. amazonensis from any reservoir or from sandflies. The data available for isolates from humans [4–7], from domestic and wild reservoir hosts [4, 6], and from sandflies [4, 6, 8, 9] support our statement: Leishmania (Viannia) braziliensisis is the only known agent of cutaneous leishmaniasis in the state of Ceara. In a large study of 272 human isolates from 39 different municipalities, all were characterized as L. braziliensis [5]. In another report [6], the author studied 354 isolates from humans, rodents, dogs, and sandflies; all were characterized as L. braziliensis. Furthermore, because the patients in our study were from several different endemic areas, the hypothesis that the response of our patients was due to aspecific clinical syndrome caused by L. braziliensis from a specific endemic area is not true. The lymphadenopathy described in L. braziliensis infection [5] has been documented in other regions of Brazil, and its detection depends on the moment patients seek medical attention and on a comprehensive physical examination because this lymphadenopathy is an early manifestation of infection and, as a rule, the lymphadenopathy is painless and abates as the ulcer progresses. There is evidence that 1 strain of L. braziliensis from 1 region may be genetically different from another strain from other regions [10], and it is possible that these strains may respond differently to therapy. Hence, it is critically important that fluconazole be tested in other areas where L. braziliensis and other species of Leishmania are endemic, keeping in mind that optimal weight-based dosing is very likely to be an important determinant of therapeutic success [1].

Macrophages participate in host protection and the disease pathology associated with Leishmania braziliensisinfection

BackgroundLeishmania preferentially infects macrophages, which allow the parasite to multiply but can also kill the parasite. Although the T cell response in human leishmaniasis is well-characterized, little is known about the concomitant macrophage behavior. The aim of this study was to characterize the macrophage immune response after Leishmania braziliensis infection in cells derived from cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML) patients, subclinical individuals (SC) and healthy control subjects (HS).MethodsPeripheral blood mononuclear cell-derived macrophages from the different groups were exposed to L. braziliensis in vitro and were evaluated for susceptibility to Leishmania infection, ability to kill Leishmania and chemokine/cytokine production. Nitric Oxide (NO) and superoxide (O2-) levels in the supernatant of infected macrophage cultures were monitored.ResultsAfter exposure to L. braziliensis, peripheral blood mononuclear cell-derived macrophages from SC individuals showed a lower infection rate and a smaller number of intracellular amastigotes compared to cells from CL and ML patients. Macrophages from CL and ML patients produced more chemokines and TNF-α than those from the SC group. Production of NO and O2- were detected but did not vary significantly among the different groups.ConclusionsOur data indicate that macrophages play a pivotal role in controlling L. braziliensis infection and in leishmaniasis pathology by secreting pro-inflammatory chemokines/cytokines that activate and recruit T cells, overwhelming the inflammatory response.

The immunobiology of Leishmania braziliensis infection

Leishmaniases are a group of diseases caused by protozoa of the genus Leishmania that affect millions of people worldwide. These diseases are caused by distinct Leishmania species, of which L. braziliensis, a New World representative of the Leishmania genus, has been the least studied. Although leishmaniasis caused by L. braziliensis induces a range of clinical manifestations ranging from mild localized lesions to severe mucosal involvement, few studies have focused on elucidating the immune mechanisms behind this pathology. In this review, we focus on the immunobiology of L. braziliensis infection, emphasizing the innate and adaptive immune responses and taking into consideration both studies performed in endemic areas and experimental models of infection. Additionally, we address recent findings regarding the role of sand fly saliva in disease immunopathogenesis and vaccine development.