Leishmania (V.) braziliensis and L. (L.) amazonensis promote differential expression of dendritic cells and cellular immune response in murine model

Exploiting Leishmania-Primed Dendritic Cells as Potential Immunomodulators of Canine Immune Response

Dendritic cells (DCs) capture pathogens and process antigens, playing a crucial role in activating naïve T cells, bridging the gap between innate and acquired immunity. However, little is known about DC activation when facing Leishmania parasites. Thus, this study investigates in vitro activity of canine peripheral blood-derived DCs (moDCs) exposed to L. infantum and L. amazonensis parasites and their extracellular vesicles (EVs). L. infantum increased toll-like receptor 4 gene expression in synergy with nuclear factor κB activation and the generation of pro-inflammatory cytokines. This parasite also induced the expression of class II molecules of major histocompatibility complex (MHC) and upregulated co-stimulatory molecule CD86, which, together with the release of chemokine CXCL16, can attract and help in T lymphocyte activation. In contrast, L. amazonensis induced moDCs to generate a mix of pro- and anti-inflammatory cytokines, indicating that this parasite can establish a different immune relationship with DCs. EVs promoted moDCs to express class I MHC associated with the upregulation of co-stimulatory molecules and the release of CXCL16, suggesting that EVs can modulate moDCs to attract cytotoxic CD8+ T cells. Thus, these parasites and their EVs can shape DC activation. A detailed understanding of DC activation may open new avenues for the development of advanced leishmaniasis control strategies.

Annexin A1 improves immune responses and control of tissue parasitism during Leishmania amazonensis infection in BALB/c mice

Leishmaniases, a group of diseases caused by the species of the protozoan parasite Leishmania, remains a significant public health concern worldwide. Host immune responses play a crucial role in the outcome of Leishmania infections, and several mediators that regulate inflammatory responses are potential targets for therapeutic approaches. Annexin A1 (AnxA1), an endogenous protein endowed with anti-inflammatory and pro-resolving properties, has emerged as a potential player. We have shown that during L. braziliensis infection, deficiency of AnxA1 exacerbates inflammatory responses but does not affect parasite burden. Here, we have investigated the role of AnxA1 in L. amazonensis infection, given the non-healing and progressive lesions characteristic of this infectious model. Infection of AnxA1 KO BALB/c mice resulted in increased lesion size and tissue damage associated with higher parasite burdens and enhanced inflammatory response. Notably, therapeutic application of the AnxA1 peptidomimetic Ac2-26 improves control of parasite replication and increases IL-10 production in vivo and in vitro, in both WT and AnxA1 KO mice. Conversely, administration of WRW4, an inhibitor of FPR2/3, resulted in larger lesions and decreased production of IL-10, suggesting that the effects of AnxA1 during L. amazonensis infection are associated with the engagement of these receptors. Our study illuminates the role of AnxA1 in L. amazonensis infection, demonstrating its impact on the susceptibility phenotype of BALB/c mice. Furthermore, our results indicate that targeting the AnxA1 pathway by using the Ac2-26 peptide could represent a promising alternative for new treatments for leishmaniasis.

DC-SIGN receptor is expressed by cells from cutaneous leishmaniasis lesions and differentially binds to Leishmania (Viannia) braziliensis and L. (Leishmania) amazonensis promastigotes

BACKGROUND

Dendritic cells (DCs) specific intercellular adhesion molecule (ICAM)-3-grabbing non integrin receptor (DC-SIGN) binds to subgenera Leishmania promastigotes mediating its interaction with DC and neutrophils, potentially influencing the infection outcome.

OBJECTIVES

In this work, we investigated whether DC-SIGN receptor is expressed in cells from cutaneous leishmaniasis (CL) lesions as well as the in vitro binding pattern of Leishmania (Viannia) braziliensis (Lb) and L. (L.) amazonensis (La) promastigotes.

METHODS

DC-SIGN receptor was labeled by immunohistochemistry in cryopreserved CL tissue fragments. In vitro binding assay with CFSE-labeled Lb or La promastigotes and RAJI-transfecting cells expressing DC-SIGN (DC-SIGN^POS) or mock-transfected (DC-SIGN^NEG) were monitored by flow cytometry at 2 h, 24 h and 48 h in co-culture.

RESULTS

In CL lesion infiltrate, DC-SIGN^POS cells were present in the dermis and near the epidermis. Both Lb and La bind to DC-SIGN^POS cells, while binding to DC-SIGN^NEG was low. La showed precocious and higher affinity to DC-SIGN^hi population than to DC-SIGN^low, while Lb binding was similar in these populations.

CONCLUSION

Our results demonstrate that DC-SIGN receptor is present in L. braziliensis CL lesions and interact with Lb promastigotes. Moreover, the differences in the binding pattern to Lb and La suggest DC-SIGN can influence in a difference way the intake of the parasites at the first hours after Leishmania infection. These results raise the hypothesis that DC-SIGN receptor could participate in the immunopathogenesis of American tegumentary leishmaniasis accounting for the differences in the outcome of the Leishmania spp. infection.

Leishmania (Viannia) braziliensis replicates in mouse bone marrow

Leishmaniasis is a neglected disease caused by species of the protozoan Leishmania. Leishmania (Viannia) braziliensis causes the cutaneous and mucocutaneous forms of the disease. Experimental cutaneous infection of mice is one of the most important preclinical research models of leishmaniasis. Here, we investigated the course of infection in mice inoculated with two reference strains of L. (V.) braziliensis (MHOM/BR/00/BA788 strain [BA] and MHOM/BR/94/H-3227 strain [CE]). Although both parasite strains induced detectable footpad lesions, BA-infected mice developed small non-ulcerated lesions that self-healed, whereas CE-infected mice developed small non-ulcerated lesions that did not regress. The parasites were detected in the footpad lesions, lymph nodes draining the site of inoculation, spleen, and bone marrow of mice infected with BA or CE parasites at 6 and 25 weeks post-inoculation. These data indicate that L (V.) braziliensis-infected mice harbor parasites that spread, even when these animals do not display overt lesions. In addition, this is the first report of the presence of the parasite in the bone marrow of mice inoculated with L. (V.) braziliensis.

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

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

What makes mucosal and anergic diffuse cutaneous leishmaniases so clinically and immunopathogically different? A review in Brazil

American cutaneous leishmaniasis (ACL) is a parasitic protozoan disease caused by different Leishmania species widely distributed throughout Latin America. Fifteen Leishmania species belonging to the subgenera Viannia, Leishmania and Mundinia are known to cause ACL. Seven of these species are found in Brazil, of which Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis have the highest potential to cause mucosal (ML) and anergic diffuse cutaneous leishmaniasis (DCL), respectively, the most severe forms of ACL. The clinical and immunopathological differences between these two clinical forms are reviewed here, taking into account their different physiopathogenic mechanisms of dissemination from cutaneous lesions to mucosal tissues in the case of ML and to almost all body surfaces in the case of anergic DCL. We also discuss some immunopathogenic mechanisms of species-specific Leishmania antigens (from the subgenera Viannia and Leishmania) that are most likely associated with the clinical and immunopathological differences between ML and anergic DCL. Those discussions emphasize the pivotal importance of some surface antigens of L. (V.) braziliensis and L. (L.) amazonensis, such as lipophosphoglycan, phosphatidylserine and CD200 (an immunoregulatory molecule that inhibits macrophage activation), that have been shown to exert strong influences on the clinical and immunopathological differences between ML and anergic DCL.

Spatial and simultaneous seroepidemiology of anti-Leishmania spp. antibodies in dog owners and their dogs from randomly selected households in a major city of southern Brazil

Although leishmaniasis has been described as a classic example of a zoonosis requiring a comprehensive approach for control, to date, no study has been conducted on the spatial distribution of simultaneous Leishmania spp. seroprevalence in dog owners and dogs from randomly selected households in urban settings. Accordingly, the present study aimed to simultaneously identify the seroprevalence, spatial distribution and associated factors of infection with Leishmania spp. in dog owners and their dogs in the city of Londrina, a county seat in southern Brazil with a population of half a million people and ranked 18th in population and 145th in the human development index (HDI) out of 5570 Brazilian cities. Overall, 564 households were surveyed and included 597 homeowners and their 729 dogs. Anti-Leishmania spp. antibodies were detected by ELISA in 9/597 (1.50%) dog owners and in 32/729 (4.38%) dogs, with significantly higher prevalence (p = 0.0042) in dogs. Spatial analysis revealed associations between seropositive dogs and households located up to 500 m from the local railway. No clusters were found for either owner or dog case distributions. In summary, the seroepidemiological and spatial results collectively show a lack of association of the factors for infection, and the results demonstrated higher exposure for dogs than their owners. However, railway areas may provide favorable conditions for the maintenance of infected phlebotomines, thereby causing infection in nearby domiciled dogs. In such an urban scenario, local sanitary barriers should be focused on the terrestrial routes of people and surrounding areas, particularly railways, via continuous vector surveillance and identification of phlebotomines infected by Leishmania spp.

T lymphocytes and macrophages in the intestinal tissues of dogs infected with Leishmania infantum

This study was about a semi-quantitative analysis of T lymphocytes (CD4+ and CD8+, FoxP3+ regulatory T cells), and macrophages in the gut wall of dogs naturally infected with Leishmania infantum. Thirteen dogs were divided into three groups: group 1 (G1, n=5), dogs with canine visceral leishmaniasis (CVL) and infected with L. infantum amastigotes in the intestine; group 2 (G2, n=5), dogs with CVL but without intestinal amastigotes; and group 3 (G3, n=3), uninfected dogs (control group). There was no significant difference (p ≥ 0.05) on CD4+ and Treg cell numbers among the groups, whereas the levels of CD8+ T cells and macrophages were significantly higher in dogs from G1 group than in G2 and G3 (p ≤ 0.05), especially in intestinal segments with high parasite burden. Parasite burden correlated positively with levels of CD8+ T cells and macrophages (p ≤ 0.05), but was inversely correlated to levels of CD4+ T lymphocytes and FoxP3+ Treg cells. In conclusion, in the intestine of dogs with CVL, the increase of CD8+ T cells and macrophages population associated with high parasite burdens, but no changes of CD4+ T cells and FoxP3+ Treg cells suggest a possible immunoregulation by the parasite not dependent on Treg cells.

Annexin A1 Is Involved in the Resolution of Inflammatory Responses during Leishmania braziliensis Infection

Leishmaniases are diseases caused by several Leishmania species. Leishmania (Viannia) braziliensis can cause localized cutaneous leishmaniasis (LCL), which heals spontaneously, or mucosal leishmaniasis (ML), characterized by chronic and intense inflammation and scanty parasitism. Annexin A1 (AnxA1) is a protein involved in modulation and resolution of inflammation through multiple mechanisms. In the present study, the role of AnxA1 was investigated in L. braziliensis-infected BALB/c mice. AnxA1 levels increased at the peak of tissue lesion and parasitism in infected mice. AnxA1 increased also after L. braziliensis infection of BALB/c (wild-type [WT]) bone marrow derived macrophages. Despite a lower parasite intake, parasite burden in bone marrow-derived macrophages from AnxA1^-/- mice was similar to WT and associated with an early increase of TNF-α and, later, of IL-10. AnxA1^-/- mice controlled tissue parasitism similarly to WT animals, but they developed significantly larger lesions at later stages of infection, with a more pronounced inflammatory infiltrate and increased specific production of IFN-γ, IL-4, and IL-10. AnxA1^-/- mice also presented higher phosphorylation levels of ERK-1/2 and p65/RelA (NF-κB) and inducible NO synthase expression, suggesting that AnxA1 may be involved in modulation of inflammation in this model of experimental leishmaniasis. Finally, assessment of AnxA1 levels in sera from patients with LCL or ML revealed that ML patients had higher levels of serum AnxA1 than did LCL patients or control subjects. Collectively, these data indicate that AnxA1 is actively expressed during L. braziliensis infection. In the absence of AnxA1, mice are fully able to control parasite replication, but they present more intense inflammatory responses and delayed ability to resolve their lesion size.

Differential Recruitment of Dendritic Cells Subsets to Lymph Nodes Correlates with a Protective or Permissive T-Cell Response during Leishmania (Viannia) Braziliensis or Leishmania (Leishmania) Amazonensis Infection

Leishmania (L.) amazonensis (La) and L. (V.) braziliensis (Lb) are responsible for a large clinical and immunopathological spectrum in human disease; while La may be responsible for anergic disease, Lb infection leads to cellular hypersensitivity. To better understand the dichotomy in the immune response caused by these Leishmania species, we evaluated subsets of dendritic cells (DCs) and T lymphocyte in draining lymph nodes during the course of La and Lb infection in BALB/c mice. Our results demonstrated a high involvement of DCs in La infection, which was characterized by the greater accumulation of Langerhans cells (LCs); conversely, Lb infection led to an increase in dermal DCs (dDCs) throughout the infection. Considering the T lymphocyte response, an increase of effector, activated, and memory CD4⁺ T-cells was observed in Lb infection. Interleukin- (IL-) 4- and IL-10-producing CD4⁺and CD8⁺ T-cells were present in both La and Lb infection; however, interferon- (IFN-) γ-producing CD4⁺and CD8⁺ T-cells were detected only in Lb infection. The results suggest that during Lb infection, the dDCs were the predominant subset of DCs that in turn was associated with the development of Th1 immune response; in contrast La infection was associated with a preferential accumulation of LCs and total blockage of the development of Th1 immune response.

Dendritic Cells and Leishmania Infection: Adding Layers of Complexity to a Complex Disease

Leishmaniasis is a group of neglected diseases whose clinical manifestations depend on factors from the host and the pathogen. It is an important public health problem worldwide caused by the protozoan parasite from the Leishmania genus. Cutaneous Leishmaniasis (CL) is the most frequent form of this disease transmitted by the bite of an infected sandfly into the host skin. The parasites can be uptook and/or recognized by macrophages, neutrophils, and/or dendritic cells (DCs). Initially, DCs were described to play a protective role in activating the immune response against Leishmania parasites. However, several reports showed a dichotomic role of DCs in modulating the host immune response to susceptibility or resistance in CL. In this review, we discuss (1) the interactions between DCs and parasites from different species of Leishmania and (2) the crosstalk of DCs and other cells during CL infection. The complexity of these interactions profoundly affects the adaptive immune response and, consequently, the disease outcome, especially from Leishmania species of the New World.

Analysis of iron superoxide dismutase-encoding DNA vaccine on the evolution of the Leishmania amazonensis experimental infection

The present work aimed to evaluate the immunogenicity of Leishmania amazonensis iron superoxide dismutase (SOD)-encoding DNA experimental vaccine and the protective properties of this DNA vaccine during infection. The SOD gene was subcloned into the pVAX1 plasmid, and it was used to immunize BALB/c mice. Twenty-one days after the last immunization, mice were sacrificed (immunogenicity studies) or subcutaneously challenged with L. amazonensis (studies of protection), and alterations in cellular and humoral immune responses were evaluated, as well as the course of infection. Mice only immunized with pVAX1-SOD presented increased frequencies of CD4(+) IFN-γ(+), CD8(+)IFN-γ(+) and CD8(+)IL-4(+) lymphocytes; moreover, high levels of IgG2a were detected. After challenge, mice that were immunized with pVAX1-SOD had increased frequencies of the CD4(+)IL-4(+), CD8(+)IFN-γ(+) and CD8(+)IL-4(+) T lymphocytes. In addition, the lymph node cells produced high amounts of IFN-γ and IL-4 cytokines. Increased IgG2a was also detected. The pattern of immunity induced by pVAX1-SOD partially protected the BALB/c mice from a challenge with L. amazonensis, as the animals presented reduced parasitism and lesion size when compared to controls. Taken together, these results indicate that leishmanial SOD modulates the lymphocyte response, and that the elevation in IFN-γ possibly accounted for the decreased skin parasitism observed in immunized animals.

Immucillins Impair Leishmania (L.) infantum chagasi and Leishmania (L.) amazonensis Multiplication In Vitro

Chemotherapy against visceral leishmaniasis is associated with high toxicity and drug resistance. Leishmania parasites are purine auxotrophs that obtain their purines from exogenous sources. Nucleoside hydrolases release purines from nucleosides and are drug targets for anti-leishmanial drugs, absent in mammal cells. We investigated the substrate specificity of the Leishmania (L.) donovani recombinant nucleoside hydrolase NH36 and the inhibitory effect of the immucillins IA (ImmA), DIA (DADMe-ImmA), DIH (DADMe-ImmH), SMIH (SerMe-ImmH), IH (ImmH), DIG (DADMe-ImmG), SMIG (SerMe-ImmG) and SMIA (SerME-ImmA) on its enzymatic activity. The inhibitory effects of immucillins on the in vitro multiplication of L. (L.) infantum chagasi and L. (L.) amazonensis promastigotes were determined using 0.05–500 μM and, when needed, 0.01–50 nM of each drug. The inhibition on multiplication of L. (L.) infantum chagasi intracellular amastigotes in vitro was assayed using 0.5, 1, 5 and 10 μM of IA, IH and SMIH. The NH36 shows specificity for inosine, guanosine, adenosine, uridine and cytidine with preference for adenosine and inosine. IA, IH, DIH, DIG, SMIH and SMIG immucillins inhibited L. (L.) infantum chagasi and L. (L.) amazonensis promastigote growth in vitro at nanomolar to micromolar concentrations. Promastigote replication was also inhibited in a chemically defined medium without a nucleoside source. Addition of adenosine decreases the immucillin toxicity. IA and IH inhibited the NH36 enzymatic activity (Ki = 0.080 μM for IA and 0.019 μM for IH). IA, IH and SMIH at 10 μM concentration, reduced the in vitro amastigote replication inside mice macrophages by 95% with no apparent effect on macrophage viability. Transmission electron microscopy revealed global alterations and swelling of L. (L.) infantum chagasi promastigotes after treatment with IA and IH while SMIH treatment determined intense cytoplasm vacuolization, enlarged vesicles and altered kinetoplasts. Our results suggest that IA, IH and SMIH may provide new chemotherapy agents for leishmaniasis.

Differential modulation of macrophage response elicited by glycoinositolphospholipids and lipophosphoglycan from Leishmania (Viannia) shawi

In this work, some aspects of the glycobiology of Leishmania shawi were examined, as it is a causative agent of cutaneous leishmaniasis in the New World. Additionally, the interaction of L. shawi's main glycoconjugates [lipophosphoglycan (LPG) and glycoinositolphospholipids (GIPLs)] with macrophages was evaluated in vitro. L. shawi LPG was devoid of side-chains in its repeat units, whereas monosaccharide analysis showed that GIPLs were suggestive of mannose-rich (type I or hybrid). In order to evaluate the biological roles of those molecules, BALB/c resident peritoneal macrophages were incubated with these glycoconjugates for 24h, and the levels of nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-12p70 and IL-10, were determined. In general, the GIPLs exhibited a greater proinflammatory role than the LPGs did. However, for the first time, the GIPLs from this species were able to trigger the production of IL-10, an anti-inflammatory cytokine. In conclusion, L. shawi glycoconjugates were able to interact with the innate immune compartment. These data reinforce the role of parasite glycoconjugates during parasite and host cell interactions.

Salivary gland homogenates from wild-caught sand flies Lutzomyia flaviscutellata and Lutzomyia (Psychodopygus) complexus showed inhibitory effects on Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis infection in BALB/c mice

During the natural transmission of Leishmania parasites, the infected sand fly female regurgitates promastigotes into the host's skin together with its saliva. It has been reported that vector saliva contains immunomodulatory molecules that facilitate the establishment of infection. Thus, the main objective of this study was to evaluate the specificity of Lutzomyia (Lu.) flaviscutellata and Lu. (Psychodopygus) complexus salivas on the infectivity of Leishmania (L.) (Leishmania) amazonensis and L. (Viannia) braziliensis, respectively. BALB/c mice were inoculated into the skin of hind footpad with L. (L.) amazonensis and L. (V.) braziliensis promastigotes in the absence or presence of Lu. flaviscutellata and Lu. (P.) complexus salivary gland homogenates (SGHs). The evolution of the infection was evaluated by lesion size, histopathological analysis and determination of the parasite load in the skin biopsies collected from the site of infection at 4 and 8 weeks PI. The lesion size and the parasite load of both groups of mice infected in the presence of SGHs were smaller than the control groups. The histopathological features showed that the inflammatory reaction was less prominent in the groups of mice infected in the presence of both SGHs when compared to the control group. The results showed that the presence of SGHs of Lu. flaviscutellata and Lu. (P.) complexus led to induction of processes that were disadvantageous to parasite establishment during infection by L. (L.) amazonensis and L. (V.) braziliensis. An inhibitory effect on Leishmania infection could be observed in both groups inoculated with SGHs, especially when the SGH from Lu. (P.) complexus was used.

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

BACKGROUND

Leishmaniasis 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 FINDINGS

Exposure 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/SIGNIFICANCE

17-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.

Dynamic of the cellular immune response at the dermal site of Leishmania (L.) amazonensis and Leishmania (V.) braziliensis infection in Sapajus apella primate

The purpose of this study was to characterize the immunopathological response in the skin of S. apella infected with Leishmania (L.) amazonensis and L. (V.) braziliensis parasites, the main causative agents of localized cutaneous leishmaniasis in South America. In infected animals, amastigote forms of L. (L.) amazonensis could be detected till 120 days postinfection (PI), while, in L. (V.) braziliensis infection, parasites could be detected until 180 days PI in the skin sections. CD20(+) cells were detected throughout the experimental time in both groups as well as in CD3(+) cells, which appeared to be activated because high densities of inducible nitric oxide synthase (iNOS(+)) cells were detected at 60 and 90 days PI in both studied groups. After 60 and 120 days PI, decrease in iNOS(+) cells was observed in L. (L.) amazonensis and L. (V.) braziliensis, respectively, which was associated with parasite clearance. Increase in lysozyme(+) cells was observed during the experimental infections, which also can be associated with parasite killing.

Treatment with triterpenic fraction purified from Baccharis uncinella leaves inhibits Leishmania (Leishmania) amazonensis spreading and improves Th1 immune response in infected mice

The current medications used to treat leishmaniasis have many side effects for patients; in addition, some cases of the disease are refractory to treatment. Therefore, the search for new leishmanicidal compounds is indispensable. Recently, it was demonstrated that oleanolic- and ursolic-containing fraction from Baccharis uncinella leaves eliminated the promastigote and amastigote forms of Leishmania (Leishmania) amazonensis and L. (Viannia) braziliensis without causing toxic effects for J774 macrophages. Thus, the aim of the present work was to characterize the therapeutic effect of the triterpenic fraction in L. (L.) amazonensis-infected BALB/c mice. Oleanolic- and ursolic acid-containing fraction was extracted from B. uncinella leaves using organic solvents and chromatographic procedures. L. (L.) amazonensis-infected BALB/c mice were treated intraperitoneally with triterpenic fraction during five consecutive days with 1.0 and 5.0 mg/kg of triterpenic fraction, or with 10.0 mg/kg of amphotericin B drug. Groups of mice treated with the triterpenic fraction, presented with decreased lesion size and low parasitism of the skin-both of which were associated with high amounts of interleukin-12 and interferon gamma. The curative effect of this fraction was similar to amphotericin B-treated mice; however, the final dose, required to eliminate amastigotes, was lesser than amphotericin B. Moreover, triterpenic fraction did not cause microscopic alterations in liver, spleen, heart, lung, and kidney of experimental groups. This work suggests that this fraction possesses compounds that are characterized by leishmanicidal and immunomodulatory activities. From this perspective, the triterpenic fraction can be explored as a new therapeutic agent for use against American Tegumentar Leishmaniasis.