Ação dos sucos digestivos sobre a absorção e destino do bcg Oral

Abstract

The absorption and the biological routing of Mycobacterium bovis BCG vaccine following intragastric administration to mice was studied. A harmful action of gastric (GJ) and duodenal juices (DJ) on BCG cells in vitro was found. Treatment with GJ induced a significant decrease of the oxygen uptake and a moderate loss of viability, as expressed by the number of colony-forming units (CFU) of BCG. Severe decreases of bacilli respiration and a notable fali of CFU counts were detected during DJ treatment. The biorouting of BCG cells was determined using carbon-14 labelled bacilli. The labelling was accomplished through a metabolic precursor of mycobacterial lipids, 14C -glycerol. The levels ofradioactivity recovered at thefirstday in the organs ofmice receiving either gastric instillation of14C-BCG, sonically disrupted 14-BCG or 14C glycerol were very similar. Subsequently, sonicated 14C-BCG and 14C -glycerol were involved in a biological decay process, while the level of 14C-BCG associated radioactivity remained stable in the organs from 6 to 24 days. Data on the biodecay from the small intestine and liver showed that absorptive events were fast enough to reach the highest level at 24 hours, dropping there after according to the complexity of the material given to the mice. In all instances, however, living BCG was not cultured from organs of mice given unlabelled BCG. The preceding data suggest that the great majority of BCG cells that passed the gut barriers were absorbed intact but not alive.

ARTIGOS

Ação dos sucos digestivos sobre a absorção e destino do bcg Oral

Rodnei C. MortattiI; Luiz Carlos S. MaiaII; Leila FonsecaI

IDepartamentos de Imunologia e Microbiologia Médica. Instituto de Microbiologia, Universidade Federal do Rio de Janeiro

IIFundação Ataulpho de Paiva, Rio de Janeiro

Endereço para correspondência

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RESUMO

Estudou-se a ação do suco gástrico artificial e suco duodenal humano sobre a vacina BCG, bem como a absorção e destino desta após administração intragástrica em camundongos. O contato de 2 horas do bacilo com o suco gástrico provocou uma diminuição significante do consumo de oxigênio e uma moderada perda da viabilidade. O suco duodenal induziu marcante decréscimo da respiração bacilar egrande redução da viabilidade. O BCG foi marcado com carbono-14 usando-se 14C-glicerol como precursor dos lipidios micobacterianos. Níveis similares de radioatividade foram obtidos nos órgãos dos animais, 24 horas após administração intragástrica de 14C- BCG, 14C-BCG rompido por ultra-som e 14C-glicerol. Os níveis de 14C-BCG permaneceram estáveis do 6o ao 24o dia, enquanto o sonicado de 14C-BCG e 14C-glicerol definiram um processo de decaimento biológico. As curvas de biodecaimento no intestino delgado e no fígado indicaram que o processo de absorção foi desencadeado rapidamente e alcançou seu nível máximo às 24 horas, decaindo em seguida de acordo com a complexidade química do material dado aos camundongos. Não foram isolados bacilos viáveis dos órgãos dos animais que receberam BCG não marcado. Pode-se concluir, portanto, que a maioria dos bacilos foram absorvidos intactos mas não viáveis.

Palavras-chave: Micobactéria. BCG oral. Sucos digestivos. Carbono-14. Absorção. Biodisponibilidade.

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ABSTRACT

The absorption and the biological routing of Mycobacterium bovis BCG vaccine following intragastric administration to mice was studied. A harmful action of gastric (GJ) and duodenal juices (DJ) on BCG cells in vitro was found. Treatment with GJ induced a significant decrease of the oxygen uptake and a moderate loss of viability, as expressed by the number of colony-forming units (CFU) of BCG. Severe decreases of bacilli respiration and a notable fali of CFU counts were detected during DJ treatment. The biorouting of BCG cells was determined using carbon-14 labelled bacilli. The labelling was accomplished through a metabolic precursor of mycobacterial lipids, 14C -glycerol. The levels ofradioactivity recovered at thefirstday in the organs ofmice receiving either gastric instillation of14C-BCG, sonically disrupted 14-BCG or 14C glycerol were very similar. Subsequently, sonicated 14C-BCG and 14C -glycerol were involved in a biological decay process, while the level of 14C-BCG associated radioactivity remained stable in the organs from 6 to 24 days. Data on the biodecay from the small intestine and liver showed that absorptive events were fast enough to reach the highest level at 24 hours, dropping there after according to the complexity of the material given to the mice. In all instances, however, living BCG was not cultured from organs of mice given unlabelled BCG. The preceding data suggest that the great majority of BCG cells that passed the gut barriers were absorbed intact but not alive.

Keywords: Mycobacteria. Oral BCG. Digestive juices. 14C-labelling. Absorption. Biovailability.

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Endereço para correspondência:

Dr. Rodnei C. Mortatti

Depto de Imunologia

Instituto de Microbiologia

UFRJ, CCS, Bloco I.

21941

Rio de Janeiro, RJ, Brasil.

Recebido para publicação em 10/3/86.

Financiado pelo Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) e Fundação Ataulpho de Paiva.