RESUMO
In this study an in vitro model was developed with the aim of investigating the modulatory effect of cholera toxin (CT) and its counterpart the heat labile toxin of Escherichia coli (LT) on TNF-alpha release induced by murine macrophages and primary human monocytes. Previous studies have demonstrated that the enzymatic activity of CT and LT molecules can inhibit TNF-alpha release by macrophages. The results obtained in this study showed that CT and LT are both, in a dose dependent manner, able either to induce or inhibit TNF-alpha release by murine macrophages and primary human monocytes. The results also showed that recombinant B subunits of CT and LT in the absence of their A subunit induce high levels of TNF-alpha release by macrophages and, in addition, increase the level of TNF-alpha release induced by LPS. The ability of both B subunits (CTB and LTB) in inducing TNF-alpha release by macrophages is not related to the level of LPS contamination, since direct measurements of LPS made in the samples employed in this study showed only traces of LPS (3.4 x 10(-8) EU/ml) which is in our system does not induce TNF-alpha release by macrophages. In contrast to the results obtained with the B subunits, incubation of cells with the A subunit of CT (CTA) inhibit TNF-alpha release induced by native CT, native LT, recombinant LTB and LPS. This inhibitory effect must be related to the activity of the A subunit since viability tests performed in terms of metabolic rate demonstrated that high concentrations of CTA are not toxic to the cells. The data presented herein demonstrate that the A subunits of CT and LT have an inhibitory effect on TNF-alpha release in macrophages, whereas their B subunits have a stimulatory effect on TNF-alpha. The results also suggest that the dose dependent bi-modal effect of native CT and native LT on TNF-alpha release by macrophages is a result of the combined effect of their individual A and B subunits.
Assuntos
Toxinas Bacterianas/farmacologia , Toxina da Cólera/farmacologia , Enterotoxinas/farmacologia , Proteínas de Escherichia coli/farmacologia , Escherichia coli/metabolismo , Macrófagos/efeitos dos fármacos , Subunidades Proteicas/farmacologia , Fator de Necrose Tumoral alfa/metabolismo , Animais , Células Cultivadas , Humanos , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Proteínas Recombinantes/farmacologiaRESUMO
OBJECTIVE: Constant antigenic stimulation of the large immune cell population contained within gut-associated lymphoid tissue during HIV infection may contribute to patients' total viral load. The aim of this investigation was to evaluate the effect of a mucosal antigenic challenge on HIV replication. DESIGN: Prospective clinical study. METHODS: Twelve HIV-1-infected men (mean age, 42.3 years) from the Casa de Apoio Santo Antonio, Rio de Janeiro, Brazil, were immunized with combined whole cell-toxin B subunit oral cholera vaccine. Blood was collected on days 0, 2, 4, 6, 10 and 15 after immunization and plasma was tested for cholera toxin-specific antibody response (IgG and IgA), beta2-microglobulin, and plasma viral load. CD4 lymphocyte counts were performed within 1 week before immunization. Five HIV-infected non-immunized individuals were studied as controls. RESULTS: There were no adverse effects following immunization and no deterioration in clinical outcome during 3 months of follow-up. A transient increase in viral load that ranged from twofold to 60-fold was observed in all cases and was statistically significant on days 2, 6 and 10 (P = 0.017, P = 0.025, P = 0.021, respectively). There was no correlation with CD4 cell counts. None of the non-immunized subjects demonstrated the pattern of viraemia observed after immunization (P > 0.10 on all days). CONCLUSIONS: Our data indicate that mucosal immunization with oral cholera vaccine induces a transient increase in HIV viraemia, regardless of clinical stage of infection and CD4 cell counts. These findings suggest that mucosal stimulation of HIV-infected patients enhances HIV replication.
Assuntos
Vacinas contra Cólera/imunologia , Infecções por HIV/imunologia , HIV-1/fisiologia , Carga Viral , Administração Oral , Adulto , Antitoxinas/sangue , Contagem de Linfócito CD4 , Toxina da Cólera/imunologia , Vacinas contra Cólera/administração & dosagem , Infecções por HIV/virologia , Humanos , Imunidade nas Mucosas , Imunoglobulina A/sangue , Imunoglobulina G/sangue , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Replicação Viral , Microglobulina beta-2/análiseRESUMO
The gut associated lymphoid tissue is responsible for specific responses to intestinal antigens. During HIV infection, mucosal immune deficiency may account for the gastrointestinal infections. In this review we describe the humoral and cellular mucosal immune responses in normal and HIV-infected subjects.
Assuntos
Humanos , Sistema Digestório , Infecções por HIV/imunologia , Formação de Anticorpos , Linfócitos T CD4-Positivos , Sistema Digestório , Imunidade nas Mucosas , Imunoglobulina A , Imunoglobulina A Secretora , Imunoglobulina G , Mucosa Intestinal , Tecido Linfoide , Mucosa Gástrica/imunologia , Mucosa Gástrica/virologiaRESUMO
The gut associated lymphoid tissue is responsible for specific responses to intestinal antigens. During HIV infection, mucosal immune deficiency may account for the gastrointestinal infections. In this review we describe the humoral and cellular mucosal immune responses in normal and HIV-infected subjects.
Assuntos
Sistema Digestório/imunologia , Infecções por HIV/imunologia , Formação de Anticorpos , Linfócitos T CD4-Positivos , Sistema Digestório/virologia , Mucosa Gástrica/imunologia , Mucosa Gástrica/virologia , Humanos , Imunidade nas Mucosas , Imunoglobulina A , Imunoglobulina A Secretora , Imunoglobulina G , Mucosa Intestinal/imunologia , Mucosa Intestinal/virologia , Tecido Linfoide/imunologia , Tecido Linfoide/virologiaAssuntos
Leishmaniose , Phlebotomus/fisiologia , África , Animais , América Central , Dípteros/fisiologia , Ecologia , Comportamento Alimentar , Humanos , Controle de Insetos , Insetos Vetores , Larva/crescimento & desenvolvimento , Leishmania/crescimento & desenvolvimento , Leishmaniose/epidemiologia , Leishmaniose Mucocutânea/epidemiologia , Leishmaniose Visceral/epidemiologia , Phlebotomus/classificação , Psychodidae/fisiologia , Pupa/crescimento & desenvolvimento , América do SulRESUMO
The article presents a synthesis of present knowledge concerning sandflies of the family Phlebotomidae in relation to leishmaniasis. Over 500 species of Phlebotominae are known, most of which belong to the genera Phlebotomus and Sergentomyia in the Old World and Lutzomyia in the New World. Phlebotomus is the dominant genus in the palaearctic region, extending also into the other regions of the Old World where Sergentomyia is the principal genus. Sandflies are of little importance in temperate North America but in tropical America Lutzomyia is the main genus and is found over large areas. The distribution of sandflies largely determines the occurrence of leishmaniasis. Certain species of Phlebotomus and Lutzomyia transmit dermal leishmaniasis in large areas of the palaearctic and neotropical regions. Visceral leishmaniasis is transmitted by some species of Phlebotomus in much of the palaearctic region, except desert areas of North Africa, and in limited areas of Africa and India, and by a species of Lutzomyia in north-eastern Brazil. Sandflies are quite likely to bite man in the open country of much of the Old World; they tend however to be localized in distribution on account of their need for a suitable microhabitat (e.g., the burrow of the Central Asian large gerbil, which has been extensively studied in relation to dermal leishmaniasis). It is noted that the distribution of sandflies and leishmaniasis appears to be changing.A few species of sandfly are regarded as proved vectors of human leishmaniasis according to five criteria; other species which are the only man-biting sandflies in the area are probably vectors. Although it is not possible to make a clear-cut list of vectors, a table of some proved and suspected vectors is included.
Assuntos
Phlebotomus , África , Ásia , América Central , Clima , Ecologia , Humanos , Insetos Vetores , Leishmaniose/epidemiologia , América do Sul , U.R.S.S. , Tempo (Meteorologia)Assuntos
Dípteros , Insetos Vetores , Onchocerca , África , Animais , América Central , DDT , Hong Kong , Humanos , Controle de Insetos , Inseticidas , Oncocercose/epidemiologia , América do SulRESUMO
The observations described in this paper were carried out between 6 September and 15 October 1963, except where otherwise indicated. The country around El Cayo has been described by Garnham and Lewis (1959) and may be roughly divided into high bush, medium bush, low bush and more or less cleared land. They regarded Leishmania mexicana in British Honduras, but the work of Lainson and Strangways-Dixon (1963) and other observation mentioned in this paper point to the possible importance of relatively sparse low vegetation, which covers much more of the country than before the 1961 hurricane. This has had a profound effect on ecology through initial destruction of plants and animals by wind, torrential rains and floods, followed by fire, shortage of food, and partial disappearance of the forest canopy which led to an increase in undergrowth (AU)
Assuntos
Humanos , Leishmaniose/epidemiologia , BelizeRESUMO
During a study carried out near San Antonio de Maturín, Venezuela, 12 Simulium forms were encountered, among which Simulium exiguum was abundant but of uncertain relation to onchocerciasis. As opposed to S. metallicum, which has its breeding places almost exclusively in small streams, S. exiguum breeds in big streams. In neither species is it possible to distinguish nuliparous and parous females from the size of their organism so it is necessary to examine the ovaries. During the rainy season pupae are swept away and the S. metallicum population is reduced
Generally speaking, adult S. exiguum have mostly been caputrd near large streams whereas adult S. metallicum have been primarily encountered near small streams. Besides these two species, two others have been caught on man. Unlike the other species which bite man and donkeys indistinctively, S. metallicum has a distinct preference for man. In the course of catches of S. exiguum, it was observed that the proportion of parous flies tended to increase after 1600 hours. Unlike what has been observed with captured individulas, reared S. exiguum were frequently found to have encysted metacercariae of a digenetic trematode. The parasite is often found in the head of the insect which is finally destroyed or prevented from biting man. Among these same simuliidae, carriers of mermithids are also found
The dissection of simuliidae showed that the ...(AU)
Publicado en inglés en el Bull. WHO 27(4-5), 1962