RESUMO
BACKGROUND: Reduction in the number of circulating blood lymphocytes (lymphocytopaenia) has been reported during clinical episodes of malaria and is normalized after treatment with anti-malaria drugs. While this phenomenon is well established in malaria infection, the underlying mechanisms are still not fully elucidated. In the present study, the occurrence of apoptosis and its pathways in CD4+ T cells was investigated in naturally Plasmodium vivax-infected individuals from a Brazilian endemic area (Porto Velho - RO). METHODS: Blood samples were collected from P. vivax-infected individuals and healthy donors. The apoptosis was characterized by cell staining with Annexin V/FITC and propidium iodide and the apoptosis-associated gene expression profile was carried out using RT2 Profiler PCR Array-Human Apoptosis. The plasma TNF level was determined by ELISA. The unpaired t-test or Mann-Whitney test was applied according to the data distribution. RESULTS: Plasmodium vivax-infected individuals present low number of leukocytes and lymphocytes with a higher percentage of CD4+ T cells in early and/or late apoptosis. Increased gene expression was observed for TNFRSF1B and Bid, associated with a reduction of Bcl-2, in individuals with P. vivax malaria. Furthermore, these individuals showed increased plasma levels of TNF compared to malaria-naive donors. CONCLUSIONS: The results of the present study suggest that P. vivax infection induces apoptosis of CD4+ T cells mediated by two types of signaling: by activation of the TNFR1 death receptor (extrinsic pathway), which is amplified by Bid, and by decreased expression of the anti-apoptotic protein Bcl-2 (intrinsic pathway). The T lymphocytes apoptosis could reflect a strategy of immune evasion triggered by the parasite, enabling their persistence but also limiting the occurrence of immunopathology.
Assuntos
Apoptose , Linfócitos T CD4-Positivos/fisiologia , Interações Hospedeiro-Patógeno , Malária Vivax/imunologia , Proteínas Proto-Oncogênicas c-bcl-2/biossíntese , Receptores Tipo I de Fatores de Necrose Tumoral/biossíntese , Adulto , Brasil , Técnicas Citológicas , Feminino , Perfilação da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Transdução de Sinais , Adulto JovemRESUMO
As parasitoses intestinais são consideradas um importante problema de saúde pública, principalmente em crianças em idade escolar, as quais apresentam maior risco de infecção e podem mostrar sintomas de desnutrição, deficit intelectual e de crescimento. Este estudo teve por objetivo conhecer a ocorrência de parasitoses intestinais nos alunos e suas famílias que moravam nas proximidades da Escola Municipal Lírio do Vale da comunidade de Guarajuba, município de Paracambi-RJ. No período de abril a julho de 2005, foi realizado o exame parasitológico de fezes de 320 amostras. Na primeira coleta, seguiu-se a técnica MIF-C, método do mertiolato-iodo-formaldeido-concentração; na segunda, o método de Ritchie-Centrífugo-Sedimentação pela Formalina-Éter e o método Safranina - azul de metileno - Método Modificado da Safranina. A ocorrência encontrada foi de 11,9 por cento e 17,5 por cento na primeira e segunda coletas, respectivamente. Entre os protozoários, predominou a espécie Blastocystis hominis (31 por cento e 38 por cento). Os helmintos encontrados foram: Ascaris lumbricoides (9 por cento) e ancilostomídeos (9 por cento). Não foram encontrados oocistos de Cryptosporidium sp. Em relação à idade, verificou-se que os parasitos intestinais se revelaram predominantes nas crianças. Na primeira coleta, a variável idade teve significância estatística (p=0,048). Os resultados mostraram que a ocorrência de parasitoses intestinais na comunidade estudada é baixa, entretanto programas educacionais ainda são necessários para melhorar sua condição de vida.
Assuntos
Humanos , Masculino , Feminino , Blastocystis hominis , Doenças Parasitárias/epidemiologia , Saúde Pública , Brasil/epidemiologiaRESUMO
Tuberculosis and intestinal parasites affect primarily low social and economic level populations, living clustered in precarious habitational settings. One of the interesting aspects of this interaction is the parasitism influence in cellular response to tuberculosis. In the present study, we evaluated the prevalence of enteroparasitosis in tuberculosis patients, HIV-infected and non HIV infected, and we observed the influence of helminth presence in the response to tuberculin skin test (TST) and tuberculosis clinical outcomes. From 607 clinical records reviewed, 327 individuals met the study inclusion criteria and did not present any exclusion criteria. The prevalence of enteroparasites observed was 19.6 percent. There was no significant association among TST result and the variables related to the presence of: helminthes, protozoa, and stool test for parasites result (p>0.5). Considering the survival of this cohort, we may observe that there is no significant difference (p>0.05) between the survival curves of parasited and non parasited individuals. Solely the variable "eosinophils" presents a statistically significant association (p<0.001) with helminthes, all other associations are considered not significant. Our findings neither show an association between helminthic infection and a favorable tuberculosis outcome, nor between parasitism and TST response, unlike other in vitro studies. Apparently, experimental data do not correspond to the clinical findings.