DEFAR - Artigos publicados em periódicos
URI permanente para esta coleçãohttp://www.hml.repositorio.ufop.br/handle/123456789/531
Navegar
3 resultados
Resultados da Pesquisa
Item Are increased frequency of macrophage-like and natural killer (NK) cells, together with high levels of NK T and CD4+CD25high T cells balancing activated CD8+ T cells, the key to control Chagas'disease morbidity?.(2006) Avelar, Danielle Marchetti Vitelli; Avelar, Renato Sathler; Massara, Rodrigo Lima; Borges, Jaila Dias; Lage, Paula Souza; Lana, Marta de; Carvalho, Andréa Teixeira de; Dias, João Carlos Pinto; Santos, Silvana Maria Elói; Martins Filho, Olindo AssisThe immunological response during early human Trypanosoma cruzi infection is not completely understood, despite its role in driving the development of distinct clinical manifestations of chronic infection. Herein we report the results of a descriptive flow cytometric immunophenotyping investigation of major and minor peripheral blood leucocyte subpopulations in T. cruzi - infected children, characterizing the early stages of the indeterminate clinical form of Chagas’ disease. Our results indicated significant alterations by comparison with uninfected children, including increased values of pre-natural killer (NK)-cells (CD3 – CD16 + CD56 – ), and higher values of proinflammatory monocytes (CD14 + CD16 + HLA-DR ++ ). The higher values of activated B lymphocytes (CD19 + CD23 + ) contrasted with impaired T cell activation, indicated by lower values of CD4 + CD38 + and CD4 + HLA-DR + lymphocytes, a lower frequency of CD8 + CD38 + and CD8 + HLA-DR + cells; a decreased frequency of CD4 + CD25 HIGH regulatory T cells was also observed. These findings reinforce the hypothesis that simultaneous activation of innate and adaptive immunity mechanisms in addition to suppression of adaptive cellular immune response occur during early events of Chagas’ disease. Comparative cross-sectional analysis of these immunophenotypes with those exhibited by patients with late chronic indeterminate and cardiac forms of disease suggested that a shift toward high values of macrophage-like cells extended to basal levels of proinflammatory monocytes as well as high values of mature NK cells, NKT and regulatory T cells, may account for limited tissue damage during chronic infection favouring the establishment/maintenance of a lifelong indeterminate clinical form of the disease. On the other hand, development of an adaptive cell-mediated inflammatory immunoprofile characterized by high levels of activated CD8 + cells and basal levels of mature NK cells, NKT and CD4 + CD25 HIGH cells might lead to late chronic pathologies associated with chagasic heart disease.Item Impact of dual infections on chemotherapeutic efficacy in balb/c mice infected with major genotypes of trypanosoma cruzi.(2007) Martins, Helen Rodrigues; Silva, Rodrigo Moreira da; Valadares, Helder Magno Silva; Toledo, Max Jean de Ornelas; Veloso, Vanja Maria; Avelar, Danielle Marchetti Vitelli; Carneiro, Cláudia Martins; Coelho, George Luiz Lins Machado; Bahia, Maria Terezinha; Martins Filho, Olindo Assis; Macedo, Andréa Mara; Lana, Marta deThe aim of this work was to investigate the impact of dual infections with stocks of Trypanosoma cruzi major genotypes on benznidazole (BZ) treatment efficacy. For this purpose, T. cruzi stocks representative of the genetic T. cruzi lineages, displaying different susceptibilities to BZ, belonging to the major T. cruzi genotypes broadly dispersed in North and South America and important in Chagas’ disease epidemiology were used. Therapeutic efficacy was observed in 27.8% of the animals treated. Following BZ susceptibility classification, significant differences were observed in dual infections on the major genotype level, demonstrating that combinations of genotypes 19 39 and genotypes 19 32 led to a shift in the expected BZ susceptibility profile toward the resistance pattern. Analysis on the T. cruzi stock level demonstrated that 9 out of 24 dual infections shifted the expected BZ susceptibility profile compared with the respective single infections, including shifts toward lower and higher BZ susceptibilities. Microsatellite identification was able to identify a mixture of T. cruzi stocks in 7.7% of the T. cruzi isolates from infected and untreated mice (6.9%) and infected and treated but not cured mice (9.0%), revealing in some mixtures of BZ-susceptible and -resistant stocks that the T. cruzi stock identified after BZ treatment was previously susceptible in single infections. Considering the clonal structure and evolution of T. cruzi, an unexpected result was the identification of parasite subpopulations with distinct microsatellite alleles in relation to the original stocks observed in 12.2% of the isolates. Taken together, the data suggest that mixed infections, already verified in nature, may have an important impact on the efficacy of chemotherapy.Item Persistence of PCR-positive tissue in benznidazole-treated mice with negative blood parasitological and serological tests in dual infections with Trypanosoma cruzi stocks from different genotypes.(2008) Martins, Helen Rodrigues; Moreira, Lílian Figueiredo; Silva, Jaquelline Carla Valamiel de Oliveira e; Carneiro, Cláudia Martins; Coelho, George Luiz Lins Machado; Avelar, Danielle Marchetti Vitelli; Bahia, Maria Terezinha; Martins Filho, Olindo Assis; Macedo, Andréa Mara; Lana, Marta deObjectives: To assess different methodologies to better define an early post-therapeutic cure criterion after benznidazole treatment in BALB/c mice following mixed infection with dual Trypanosoma cruzi genotypes. Methods: According to the classical cure criteria, animals were classified as treated not cured (TNC 5 76.4%), treated cured (TC 5 12.5%) and dissociated (DIS 5 11.1%) using parasitological [fresh blood examination (FBE), blood culture (BC) and blood PCR] and serological methods [conventional serology (CS-ELISA) and non-conventional serology (NCS-FC-ALTA)]. Tissues were also evaluated by PCR. Results: FBE was able to detect patent parasitaemia in only 18.1% of TNC and therapeutic failure was detected in 79.1% and 97.2% of TNC by BC and blood PCR, respectively. CS-ELISA should not be used before 3 months after treatment since it may lead to false-negative results. At 3 months after treatment with benznidazole, NCS-FC-ALTA was more efficient for categorizing the groups of treated mice. In the TNC group, although a decreased frequency of PCR-positive tissue was observed in several host tissues, increased positivity was also observed, despite the T. cruzi genotype combination. All TC animals presented at least two positive tissue-PCR results. Conclusions: Our results confirm that NSC-FC-ALTA and blood PCR are the most suitable methods to early detect therapeutic failure in acute murine T. cruzi infection. Additionally, our data show that BC positivity is highly dependent upon the T. cruzi genotype combination. Moreover, our findings demonstrated that PCR tests performed on tissues from animals considered cured after benznidazole treatment still detected T. cruzi DNA, most probably indicating residual infection.