N6-methyltubercidin gives sterile cure in a cutaneous Leishmania amazonensis mouse model.

Leishmania is a trypanosomatid parasite that causes skin lesions in its cutaneous form. Current therapies rely on old and expensive drugs, against which the parasites have acquired considerable resistance. Trypanosomatids are unable to synthesize purines relying on salvaging from the host, and nucleoside analogues have emerged as attractive antiparasitic drug candidates. 4-Methyl-7-ß-D-ribofuranosyl-7H-pyrrolo[2,3-d]pyrimidine (CL5564), an analogue of tubercidin in which the amine has been replaced by a methyl group, demonstrates activity against Trypanosoma cruzi and Leishmania infantum. Herein, we investigated its in vitro and in vivo activity against L. amazonensis. CL5564 was 6.5-fold (P = 0.0002) more potent than milteforan™ (ML) against intracellular forms in peritoneal mouse macrophages, and highly selective, while combination with ML gave an additive effect. These results stimulated us to study the activity of CL5564 in mouse model of cutaneous Leishmania infection. BALB/c female and male mice infected by L. amazonensis treated with CL5564 (10 mg kg−1, intralesional route for five days) presented a >93% reduction of paw lesion size likely ML given orally at 40 mg kg−1, while the combination (10 + 40 mg kg−1 of CL5564 and ML, respectively) caused >96% reduction. The qPCR confirmed the suppression of parasite load, but only the combination approach reached 66% of parasitological cure. These results support additional studies with nucleoside derivatives.

Overexpression of TcNTPDase-1 Gene Increases Infectivity in Mice Infected with Trypanosoma cruzi.

Ecto-nucleoside triphosphate diphosphohydrolases (NTPDases) are enzymes located on the surface of the T. cruzi plasma membrane, which hydrolyze a wide range of tri-/-diphosphate nucleosides. In this work, we used previously developed genetically modified strains of Trypanosoma cruzi (T. cruzi), hemi-knockout (KO +/−) and overexpressing (OE) the TcNTPDase-1 gene to evaluate the parasite infectivity profile in a mouse model of acute infection (n = 6 mice per group). Our results showed significantly higher parasitemia and mortality, and lower weight in animals infected with parasites OE TcNTPDase-1, as compared to the infection with the wild type (WT) parasites. On the other hand, animals infected with (KO +/−) parasites showed no mortality during the 30-day trial and mouse weight was more similar to the non-infected (NI) animals. In addition, they had low parasitemia (45.7 times lower) when compared with parasites overexpressing TcNTPDase-1 from the hemi-knockout (OE KO +/−) group. The hearts of animals infected with the OE KO +/− and OE parasites showed significantly larger regions of cardiac inflammation than those infected with the WT parasites (p < 0.001). Only animals infected with KO +/− did not show individual electrocardiographic changes during the period of experimentation. Together, our results expand the knowledge on the role of NTPDases in T. cruzi infectivity, reenforcing the potential of this enzyme as a chemotherapy target to treat Chagas disease (CD).

Combination Chemotherapy with Suboptimal Doses of Benznidazole and Pentoxifylline Sustains Partial Reversion of Experimental Chagas' Heart Disease.

Chronic chagasic cardiomyopathy (CCC) progresses with parasite persistence, fibrosis, and electrical alterations associated with an unbalanced immune response such as high plasma levels of tumor necrosis factor (TNF) and nitric oxide (NO). Presently, the available treatments only mitigate the symptoms of CCC. To improve CCC prognosis, we interfered with the parasite load and unbalanced immune response using the trypanocidal drug benznidazole (Bz) and the immunoregulator pentoxifylline (PTX). C57BL/6 mice chronically infected with the Colombian strain of Trypanosoma cruzi and with signs of CCC were treated for 30 days with a suboptimal dose of Bz (25 mg/kg of body weight), PTX (20 mg/kg), or their combination (Bz plus PTX) and analyzed for electrocardiographic, histopathological, and immunological changes. Bz (76%) and Bz-plus-PTX (79%) therapies decreased parasite loads. Although the three therapies reduced myocarditis and fibrosis and ameliorated electrical alterations, only Bz plus PTX restored normal heart rate-corrected QT (QTc) intervals. Bz-plus-PTX-treated mice presented complementary effects of Bz and PTX, which reduced TNF expression (37%) in heart tissue and restored normal TNF receptor 1 expression on CD8(+) T cells, respectively. Bz (85%) and PTX (70%) therapies reduced the expression of inducible nitric oxide synthase (iNOS/NOS2) in heart tissue, but only Bz (58%) reduced NO levels in serum. These effects were more pronounced after Bz-plus-PTX therapy. Moreover, 30 to 50 days after treatment cessation, reductions of the prolonged QTc and QRS intervals were sustained in Bz-plus-PTX-treated mice. Our findings support the importance of interfering with the etiological agent and immunological abnormalities to improve CCC prognosis, opening an opportunity for a better quality of life for Chagas' disease (CD) patients.

Behavioural alterations are independent of sickness behaviour in chronic experimental Chagas disease.

The existence of the nervous form of Chagas disease is a matter of discussion since Carlos Chagas described neurological disorders, learning and behavioural alterations in Trypanosoma cruzi-infected individuals. In most patients, the clinical manifestations of the acute phase, including neurological abnormalities, resolve spontaneously without apparent consequence in the chronic phase of infection. However, chronic Chagas disease patients have behavioural changes such as psychomotor alterations, attention and memory deficits, and depression. In the present study, we tested whether or not behavioural alterations are reproducible in experimental models. We show that C57BL/6 mice chronically infected with the Colombian strain of T. cruzi (150 days post-infection) exhibit behavioural changes as (i) depression in the tail suspension and forced swim tests, (ii) anxiety analysed by elevated plus maze and open field test sand and (iii) motor coordination in the rotarod test. These alterations are neither associated with neuromuscular disorders assessed by the grip strength test nor with sickness behaviour analysed by temperature variation sand weight loss. Therefore, chronically T. cruzi-infected mice replicate behavioural alterations (depression and anxiety) detected in Chagas disease patients opening an opportunity to study the interconnection and the physiopathology of these two biological processes in an infectious scenario.

Genetic Polymorphism at CCL5 Is Associated With Protection in Chagas' Heart Disease: Antagonistic Participation of CCR1+ and CCR5+ Cells in Chronic Chagasic Cardiomyopathy.

Chronic cardiomyopathy is the main clinical manifestation of Chagas disease (CD), a disease caused by Trypanosoma cruzi infection. A hallmark of chronic chagasic cardiomyopathy (CCC) is a fibrogenic inflammation mainly composed of CD8+ and CD4+ T cells and macrophages. CC-chemokine ligands and receptors have been proposed to drive cell migration toward the heart tissue of CD patients. Single nucleotide polymorphisms (SNPs) in CC-chemokine ligand and receptor genes may determine protein expression. Herein, we evaluated the association of SNPs in the CC-chemokines CCL2 (rs1024611) and CCL5 (rs2107538, rs2280788) and the CCL5/RANTES receptors CCR1 (rs3181077, rs1491961, rs3136672) and CCR5 (rs1799987) with risk and progression toward CCC. We performed a cross-sectional association study of 406 seropositive patients from endemic areas for CD in the State of Pernambuco, Northeast Brazil. The patients were classified as non-cardiopathic (A, n = 110) or cardiopathic (mild, B1, n = 163; severe, C, n = 133). Serum levels of CCL5 and CCL2/MCP-1 were elevated in CD patients but were neither associated with risk/severity of CCC nor with SNP genotypes. After logistic regression analysis with adjustment for the covariates gender and ethnicity, CCL5 -403 (rs2107538) CT heterozygotes (OR = 0.5, P-value = 0.04) and T carriers (OR = 0.5, P-value = 0.01) were associated with protection against CCC. To gain insight into the participation of the CCL5-CCR5/CCR1 axis in CCC, mice were infected with the Colombian T. cruzi strain. Increased CCL5 concentrations were detected in cardiac tissue. In spleen, frequencies of CCR1+ CD8+ T cells and CD14+ macrophages were decreased, while frequencies of CCR5+ cells were increased. Importantly, CCR1+CD14+ macrophages were mainly IL-10+, while CCR5+ cells were mostly TNF+. CCR5-deficient infected mice presented reduced TNF concentrations and injury in heart tissue. Selective blockade of CCR1 (Met-RANTES therapy) in infected Ccr5-/- mice supported a protective role for CCR1 in CCC. Furthermore, parasite antigen stimulation of CD patient blood cells increased the frequency of CCR1+CD8+ T cells and CCL5 production. Collectively, our data support that a genetic variant of CCL5 and CCR1+ cells confer protection against Chagas heart disease, identifying the CCL5-CCR1 axis as a target for immunostimulation.

Integration of miRNA and gene expression profiles suggest a role for miRNAs in the pathobiological processes of acute Trypanosoma cruzi infection.

Chagas disease, caused by the parasite Trypanosoma cruzi, is endemic in Latin America. Its acute phase is associated with high parasitism, myocarditis and profound myocardial gene expression changes. A chronic phase ensues where 30% develop severe heart lesions. Mouse models of T. cruzi infection have been used to study heart damage in Chagas disease. The aim of this study was to provide an interactome between miRNAs and their targetome in Chagas heart disease by integrating gene and microRNA expression profiling data from hearts of T. cruzi infected mice. Gene expression profiling revealed enrichment in biological processes and pathways associated with immune response and metabolism. Pathways, functional and upstream regulator analysis of the intersections between predicted targets of differentially expressed microRNAs and differentially expressed mRNAs revealed enrichment in biological processes and pathways such as IFNγ, TNFα, NF-kB signaling signatures, CTL-mediated apoptosis, mitochondrial dysfunction, and Nrf2-modulated antioxidative responses. We also observed enrichment in other key heart disease-related processes like myocarditis, fibrosis, hypertrophy and arrhythmia. Our correlation study suggests that miRNAs may be implicated in the pathophysiological processes taking place the hearts of acutely T. cruzi-infected mice.

Análise da resposta inflamatória em fígado e baço de cães naturalmente infectados por Leishmania infantum

A Leishmaniose Visceral (LV) é uma doença complexa e os sinais clínicos no cão se apresentam de forma muito semelhante aos que ocorrem em humanos. Entre os órgãos afetados pela LV o fígado e o baço aparentam ser afetados em diferentes tempos e com respostas imune e evolução clínica diferenciada. A via de sinalização da MAP4K4 está relacionada a mau prognóstico em diversas patologias além de ser responsável pela ativação, migração, proliferação e apoptose celular. Além disso, MAP4K4 está envolvida na produção de TNFα e dano tecidual. O presente trabalho tem como objetivo avaliar o escore clínico de cães naturalmente infectados com Leishmania infantum, a carga parasitária dos animais e a organização do baço correlacionando esses dados com o perfil inflamatório em fígado e baço de cães por meio da expressão gênica e proteica de MAP4K4 e TNFα e expressão gênica de IFNγ, IL-10, CXCL-8 e CCL-2, além de analisar a presença ou não de dano tecidual nesses tecidos por meio da observação de alterações histológicas e deposição de laminina e fibronectina em baço e fígado e das enzimas hepáticas séricas. Após a separação dos grupos entre as diferentes organizações do baço e a carga parasitária dos animais e pelo escore clínico, não identificamos diferenças entre os diversos marcadores quando separados pela carga parasitária tanto em baço quanto em fígado. MAP4K4 e TNFα encontraram-se intimamente associadas a reações granulomatosas e a macrófagos hepáticos. Dano tecidual foi observado em baço e fígado através do aumento da deposição de fibronectina em animais com alto escore clínico. A expressão gênica de CXCL-8 se manteve relativamente constante em todos os grupos analisados e CCL-2 encontrou-se aumentada nos animais com baço desorganizado e alta carga (DAC) e em animais com médio escore clínico. Não foram observadas alterações, entre os grupos analisados, nas expressões de IFNγ e IL-10 em baço e fígado dos animais. Observamos que a expressão gênica de TNFα estava aumentada em animais DAC, no fígado, quando comparados a animais com baço organizado e baixa carga (OBC) e no baço de animais que apresentaram médio escore clínico quando com parados a animais com baixo e alto escore. Além disso, MAP4K4 teve sua expressão aumentada no fígado de animais com baixo escore clínico quando comparados a animais de alto escore, esse aumento também foi observado no baço de animais OBC e DAC quando comparados a animais com baço desorganizado e baixa carga (DBC). O aumento da expressão gênica de MAP4K4 nos estágios iniciais da doença e a sua relação com áreas de reação granulomatosa sugerem que esta via de sinalização pode estar relacionada com a exacerbação inespecífica da resposta imune e da injúria tecidual, porém sem impactar na carga parasitária

Behavioural alterations are independent of sickness behaviour in chronic experimental Chagas disease

The existence of the nervous form of Chagas disease is a matter of discussion since Carlos Chagas described neurological disorders, learning and behavioural alterations in Trypanosoma cruzi-infected individuals. In most patients, the clinical manifestations of the acute phase, including neurological abnormalities, resolve spontaneously without apparent consequence in the chronic phase of infection. However, chronic Chagas disease patients have behavioural changes such as psychomotor alterations, attention and memory deficits, and depression. In the present study, we tested whether or not behavioural alterations are reproducible in experimental models. We show that C57BL/6 mice chronically infected with the Colombian strain of T. cruzi (150 days post-infection) exhibit behavioural changes as (i) depression in the tail suspension and forced swim tests, (ii) anxiety analysed by elevated plus maze and open field test sand and (iii) motor coordination in the rotarod test. These alterations are neither associated with neuromuscular disorders assessed by the grip strength test nor with sickness behaviour analysed by temperature variation sand weight loss. Therefore, chronically T. cruzi-infected mice replicate behavioural alterations (depression and anxiety) detected in Chagas disease patients opening an opportunity to study the interconnection and the physiopathology of these two biological processes in an infectious scenario.

Busca de biomarcadores de infecção aguda e crônica pelo Trypanosoma cruziperfil de N-glicanas em proteínas séricas e glicofenótipos em leucócitos

Alterações no perfil de glicosilação de proteínas, células e tecidos têm sido utilizadas como marcadores biológicos para processos fisiológicos e patológicos. Glicoconjugados contendo o ácido siálico (Neu5Ac) estão envolvidas em interações celulares e parasito-hospedeiro, tráfego de linfócitos e regulação do sistema imune. O Trypanosoma cruzi, agente etiológico da doença de Chagas (DC), expressa em sua superfície e libera no plasma do hospedeiro, uma enzima restrita ao gênero Trypanosoma, a trans-sialidase (TS). Esta é capaz de transferir Neu5Ac de moléculas doadoras e realocá-las em moléculas na superfície do parasito ou sialilar glicoproteínas de células do hospedeiro. A molécula CD43 é um importante aceptor de Neu5Ac em células T e um provável sítio de ação da TS. Na infecção experimental pelo T. cruzi, as células T CD8+ apresentam, majoritariamente, perfis segregados (i) perforina+ (Pfn+), com ação citotóxica, ou (ii) interferon-gama+ (IFN\03B3+), com perfil inflamatório. Estas células estão diferencialmente compartimentalizadas e atuam de forma antagônica, enquanto as Pfn+ se acumulam na inflamação cardíaca e contribuem para a injúria tecidual, as IFN\03B3+ estão majoritariamente na periferia (sangue e baço) e atuam de forma benéfica. Neste trabalho, propomos que na infecção pelo T. cruzi há alterações de glicofenótipos em proteínas séricas e subpopulações de linfócitos T CD8+ funcionalmente segregadas. Camundongos C57BL/6 foram infectados pela cepa Colombiana do T. cruzi e analisados clinicamente. O glicofenótipo de proteínas séricas foi analisado por espectrometria de massas (MALDI-TOF) e o glicofenótipo de tecido cardíaco e de células do baço foi analisado usando lectinas por histoquímica e citometria de fluxo, respectivamente Não detectamos modificação no perfil glicosídico em proteínas séricas em animais infectados. Observamos, no tecido cardíaco, reduzida marcação para a lectina Peanut agglutinin (PNA), aumento para Sambucus nigra (SNA) e não alteração para Maackia amurensis (MAL) em células musculares e inflamatórias. Notamos nas fases aguda (42 dpi) e crônica (120 dpi) aumento na frequência de células PNA+ nas células T CD8+CD43+ e CD4+CD43+, redução no percentual de células SNA+ nas células T CD8+ e CD4+ e diminuição na proporção de células MAL+ nas células T CD4+ e CD8+CD4+. Células T CD8+ totais ou CD8+PNA+ apresentaram perfis semelhantes de ativação (CD44+CD62L-), migração (LFA-1+CCR5+ ou LFA-1+CCR1+) e funcionalidade (Pfn+, Pfn+IFN\03B3+ ou IFN\03B3+). Em 120 dpi, detectou-se enriquecimento de células CD8+PNA+IFN\03B3+ no baço. Assim, durante a DC experimental, células T CD8+PNA+ apresentam-se ativadas e com potencial de migrar e exercer atividade inflamatória (IFN\03B3+), contudo estas não foram detectadas em tecido cardíaco. Resta-nos esclarecer se estas células não migram para este tecido, acumulando-se na periferia, ou se ao entrarem no tecido cardíaco têm seu glicofenótipo alterado ou morrem de modo seletivo. Embora nossos achados não permitam a identificação de biomarcadores de natureza glicosídica de progressão e/ou gravidade da DC, abrem perspectivas para explorar outros modelos experimentais de infecção e para estudos sobre a compartimentalização de células fenotipicamente distintas e funcionalmente relacionadas à proteção contra a injúria cardíaca na infecção pelo T. cruzi