Endocytosis of DNA-Hsp65 Alters the pH of the Late Endosome/Lysosome and Interferes with Antigen Presentation

BACKGROUND: Experimental models using DNA vaccine has shown that this vaccine is efficient in generating humoral and cellular immune responses to a wide variety of DNA-derived antigens. Despite the progress in DNA vaccine development, the intracellular transport and fate of naked plasmid DNA in eukaryotic cells is poorly understood, and need to be clarified in order to facilitate the development of novel vectors and vaccine strategies. METHODOLOGY AND PRINCIPAL FINDINGS: Using confocal microscopy, we have demonstrated for the first time that after plasmid DNA uptake an inhibition of the acidification of the lysosomal compartment occurs. This lack of acidification impaired antigen presentation to CD4 T cells, but did not alter the recruitment of MyD88. The recruitment of Rab 5 and Lamp I were also altered since we were not able to co-localize plasmid DNA with Rab 5 and Lamp I in early endosomes and late endosomes/lysosomes, respectively. Furthermore, we observed that the DNA capture process in macrophages was by clathrin-mediated endocytosis. In addition, we observed that plasmid DNA remains in vesicles until it is in a juxtanuclear location, suggesting that the plasmid does not escape into the cytoplasmic compartment. CONCLUSIONS AND SIGNIFICANCE: Taken together our data suggests a novel mechanism involved in the intracellular trafficking of plasmid DNA, and opens new possibilities for the use of lower doses of plasmid DNA to regulate the immune response

Análise do termo de primeira ordem das séries de Molodenskii para o problema de valor de contorno da geodésia

Neste trabalho, avaliou-se o termo de primeira ordem das séries de Molodenskii usando as seguintes abordagens: a solução dada pela série de Molodenskii; a solução pelo gradiente vertical; e a solução pela correção de terreno como aproximação do termo <img border=0 width=32 height=32 src="../../../../img/revistas/bcg/v16n4/a05simb03.jpg">. As duas últimas soluções foram obtidas por Moritz. As duas primeiras soluções mostraram-se coerentes entre si nas condições aqui analisadas. A comparação foi feita em termos de anomalia de altitude de primeira ordem <img border=0 width=32 height=32 src="../../../../img/revistas/bcg/v16n4/a05simb04.jpg">. Em termos do quase geoide final, o uso da correção de terreno em vez do termo <img border=0 width=32 height=32 src="../../../../img/revistas/bcg/v16n4/a05simb03.jpg">mostrou-se eficiente em termos da avaliação realizada com dados independentes; neste caso, 42 referências de nível posicionadas por GPS. A metodologia, os resultados, as discussões, conclusões e recomendações práticas são apresentadas

Lack of galectin-3 alters the balance of innate immune cytokines and confers resistance to Rhodococcus equi infection

Galectin-3 is a p-galactoside-binding lectin implicated in the fine-tuning of innate immunity. Rhodococcus equi, a facultative intracellular bacterium of macrophages, causes severe granulomatous bronchopneumonia in young horses and immunocompromised humans. The aim of this study is to investigate the role of galectin-3 in the innate resistance mechanism against R. equi infection. The bacterial challenge of galectin-3-deficient mice (gal3(-/-)) and their wild-type counterpart (gal3(+/+)) revealed that the LD50 for the gal3(-/-) mice was about seven times higher than that for the gal3(+/+) mice. When challenged with a sublethal dose, gal3(-/-) mice showed lower bacteria counts and higher production of IL-12 and IFN-gamma production, besides exhibiting a delayed although increased inflammatory reaction. Gal3(-/-) macrophages exhibited a decreased frequency of bacterial replication and survival, and higher transcript levels of IL-1 beta, IL-6, IL-10, TLR2 and MyD88. R. equi-infected gal3(+/+) macrophages showed decreased expression of TLR2, whereas R. equi-infected gal3(-/-) macrophages showed enhanced expression of this receptor. Furthermore, galectin-3 deficiency in macrophages may be responsible for the higher IL-1 beta serum levels detected in infected gal3(-/-) mice. Therefore galectin-3 may exert a regulatory role in innate immunity by diminishing IL-1 beta production and thus affecting resistance to R. equi infection.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Pesquisa Cientifica e Tecnologica (CNPq