Evaluation of Escherichia coli STb toxin in an in vitro organ culture model (IVOC) / Avaliação de toxina STb de Escherichia coli em modelo de cultura de órgãos in vitro (IVOC)

ETEC pathogenesis comprises adhesion to the small intestine, colonization and enterotoxin production. STb is one of the heat-stable toxins produced by ETEC. Previous reports, using culture supernatants of STb-positive ETEC strains, indicated loss of villous absorptive cells causing mild atrophy and microscopic alterations in jejunum mucosa. These culture supernatants contained many other compounds beside STb toxin and in addition the quantity of toxin in these supernatants was not determined. Thus, this study was undertaken to evaluate the effect of pure STb toxin on piglet jejunum explants in an in vitro organ culture (IVOC) model. Tissues of piglets of 11 weeks were used and put into culture. Morphometric analysis of tissues revealed that villous epithelial area was reduced in tissues treated with pure STb after 3, 4 and 5 hours (p 0.0001) compared to untreated tissues. STb-treated tissues presented atrophic villi due to loss of villi tip. Our data shows that, in piglet jejunum explants, pure STb toxin can lead to cell modification and consequently to destruction, seen as villi atrophy. These changes result in a reduced absorptive area and could be partly responsible for the diarrhea observed in the animal following STb intoxication.