Veronica F. Amaral

Cell Populations in Lesions of Cutaneous Leishmaniasis of Leishmania†(L.)†amazonensis-infected Rhesus Macaques, Macaca mulatta

The cellular nature of the infiltrate in cutaneous lesion of rhesus monkeys experimentally infected with Leishmania (L.) amazonensis was characterized by immunohistochemistry. Skin biopsies from infected animals with active or healing lesions were compared to non-infected controls (three of each type) to quantitate inflammatory cell types. Inflammatory cells (composed of a mixture of T lymphocyte subpopulations, macrophages and a small number of natural killer cells and granulocytes) were more numerous in active lesions than in healing ones. T-cells accounted for 44.7 +/- 13.1% of the infiltrate in active lesions (versus CD2+ = 40.3 +/- 5.7% in healing lesions) and T-cell ratios favor CD8+ cells in both lesion types. The percentage of cells expressing class II antigen (HLA-DR+) in active lesions (95 +/- 7.1%) was significantly higher (P < 0.005) from the healing lesions (42.7 +/- 12.7%). Moreover, the expression of the activation molecules CD25 (@ 16%), the receptor for interleukin-2, suggests that many T cells are primed and proliferating in active lesions. Distinct histopathological patterns were observed in lesions at biopsy, but healing lesions contained more organized epithelioid granulomas and activated macrophages, followed by fibrotic substitution. The progression and resolution of skin lesions appears to be very similar to that observed in humans, confirming the potential for this to be used as a viable model to study the immune response in human cutaneous leishmaniasis.

Synthesis and antileishmanial evaluation of 1-aryl-4-(4,5-dihydro-1H-imidazol-2-yl)-1H-pyrazole derivatives

A series of 1-aryl-4-(4,5-dihydro-1H-imidazol-2-yl)-1H-pyrazoles (4a-g) and 5-amino-1-aryl-4-(4,5-dihydro-1H-imidazol-2-yl)-1H-pyrazoles (5a-g) were synthesized and evaluated in vitro against three Leishmania species: L. amazonensis, L. braziliensis and L. infantum (L. chagasi syn.). The cytotoxicity was assessed. Among the derivatives examined, six compounds emerged as the most active on promastigotes forms of L. amazonensis with IC(50) values ranging from 15 to 60 μM. The reference drug pentamidine presented IC(50)=10 μM. However, these new compounds were less cytotoxic than pentamidine. Based on these results, the more promising derivative 5d was tested further in vivo. This compound showed inhibition of the progression of cutaneous lesions in CBA mice infected with L. amazonensis relative to an untreated control.

4-(1H-Pyrazol-1-yl) benzenesulfonamide derivatives: identifying new active antileishmanial structures for use against a neglected disease.

Leishmaniasis is a neglected disease responsible for about 56,000 deaths every year. Despite its importance, there are no effective, safe and proper treatments for leishmaniasis due to strain resistance and/or drug side-effects. In this work we report the synthesis, molecular modeling, cytotoxicity and the antileishmanial profile of a series of 4-(1H-pyrazol-1-yl)benzenesulfonamides. Our experimental data showed an active profile for some compounds against Leishmania infantum and Leishmania amazonensis. The profile of two compounds against L. infantum was similar to that of pentamidine, but with lower cytotoxicity. Molecular modeling evaluation indicated that changes in electronic regions, orientation as well as lipophilicity of the derivatives were areas to improve the interaction with the parasitic target. Overall the compounds represent feasible prototypes for designing new molecules against L. infantum and L. amazonensis.

The in vivo activity of 1,3,4-thiadiazolium-2-aminide compounds in the treatment of cutaneous and visceral leishmaniasis

OBJECTIVES Researchers have recently investigated the biological activities of mesoionic (MI) compounds, which have shown in vitro activity against many species of Leishmania, as well as Trypanosoma cruzi. The main goal of this study was to evaluate and compare the activity of three MI compounds against Leishmania amazonensis and Leishmania infantum infection in vivo. METHODS The experiments were carried out using BALB/c mice infected with L. amazonensis or L. infantum as a highly sensitive murine model. The infected mice were treated with MI-HH, MI-4-OCH(3), MI-4-NO(2) or meglumine antimoniate by different routes (intralesional, topical or intraperitoneal). RESULTS Treatment with MI-4-OCH(3) and MI-4-NO(2) efficiently contained the progression of cutaneous and visceral leishmaniasis in comparison with the control group or mice treated with meglumine antimoniate. Interestingly, these MI compounds did not produce toxicological effects after treatment. Furthermore, treatment with these compounds led to a modulation of the immune response that was correlated with disease control. In this study, MI compounds, and MI-4-NO(2) in particular, exhibited high activity in the L. infantum murine model. In the L. amazonensis model, intralesional treatment with MI-4-OCH(3) or MI-4-NO(2) showed greater therapeutic efficacy than treatment with meglumine antimoniate, and the new topical formulations of these compounds also displayed great activity in the cutaneous leishmaniasis model. CONCLUSIONS Upon comparison of each MI compound, MI-4-NO(2) was clearly the compound with the greatest activity in these two in vivo infection models by each administration route tested.

The histopathological and immunological pattern of CBA mice infected with Leishmania amazonensis after treatment with pyrazole carbohydrazide derivatives.

Because there is no vaccine in clinical use, control of Leishmaniasis relies almost exclusively on chemotherapy and the conventional treatments exhibit high toxicity for patients and emerging drug resistance. Recently, we showed that oral treatment with synthetic pyrazole carbohydrazide compounds induced lower parasite load in draining lymph nodes and reduced skin lesion size without causing any toxic effects in an experimental murine infection model with Leishmania amazonensis. In this study, CBA mice were infected in the footpad with L. amazonensis and then orally treated with pyrazole carbohydrazides derivatives, such as BrNO(2), NO(2)Cl and NO(2)Br and their histopathological and immunological effects were then investigated. Epidermis and dermis had lower levels of inflammatory infiltration compared to the infected untreated control mice. In the dermis of treated animals, the numbers of vacuolated macrophages containing intracellular parasites were far lower than in infected untreated animals. In addition to dermal macrophages, we also observed a mixed inflammatory infiltrate containing lymphocytes and granulocyte cells. Lower numbers of B cells (B220+) and T lymphocytes (CD3+) were identified in the lesions of treated mice compared with the untreated, infected mice. In draining lymph node cells, the number of T lymphocytes (CD3+) was decreased, and the numbers of B cells (CD19+) and CD8+ T cells were increased in infected mice, when compared with the non-infected control group. In additional, we have shown that infected treated and untreated lymph node cells had similar levels of TGF-β and IFN-γ mRNA expression, whereas IL-4 was expressed at a lower level in the treated group. Increased levels of the specific anti-Leishmania IgG2a or IgG3 antibody subclass were observed in NO(2)Cl or BrNO(2)-treated group, respectively. Overall, our experimental findings suggest that pyrazole carbohydrazides exert modulation of IL-4 expression and B cell levels; however, further evaluation is required to determine the optimal treatment regime.

Antileishmanial Activity of 1,3,4-Thiadiazolium-2-Aminide in Mice Infected with Leishmania amazonensis

ABSTRACT The efficacy of two mesoionic derivatives (MI-H-H and MI-4-OCH3) was evaluated in CBA/J mice infected with Leishmania amazonensis. Treatment with these compounds demonstrated that the MI-4-OCH3 derivative and the reference drug meglumine antimoniate (Glucantime) presented significant activity relative to an untreated control. No apparent hepatic or renal toxicity due to these mesoionic compounds was found.

Synthesis and in vitro evaluation of new benzenesulfonamides as antileishmanial agents

This paper describes the synthesis and the antileishmanial activity of new pyrazolyl benzenesulfonamide derivatives. These were elucidated by spectrometric methods. Some compounds showed a significant in vitro activity against Leishmania amazonensis, highlighting the derivative 1e. These pyrazolyl benzenesulfonamide derivatives did not show any toxicity in murine macrophage.

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.