Excretion Products of Shigella dysenteriae and Apoptotic Cell Death on Chick Embryo Muscle Tissue

Abstract

SUMMARY: The aim of this study was to evaluate the acute cell injury of excretion products present in culture filtrate from Shigella dysenteriae in both whole lower limb of chick embryo ex vivo and myoblasts cells developed in hanging-drop cultures in vitro. Three controls were defined: a) Tyrode’s solution b) brain-heart broth infusion (CCC) and c) supernatant not toxigenic of E.coli O157:H7. Shigella dysenteriae were culture for 24 hours and the excretion products were obtained after centrifugation of the culture. After 1h of treatment, the morphologic changes in limbs treated with raw filtrate were evaluated through histopathological examination of sections stained with hematoxylin-eosin (H&E-stain) and Gomori’s trichrome by image analysis techniques. Quantification of apoptotic cells was measured by an enzyme-linked immunoassay TUNEL. The morphological feature of apoptosis were evaluated in culture myoblasts. In contrast with controls, the longitudinal section on treated thigh of chick embryo limb-buds show atrophy muscle tissue, detachment of few fibers, 57,14% decrease in the number of cells, and loss of collagen substrate. Apoptotic index percent increase and mitotic index decrease in response to excretion products were observed, but were not significant. Membrane blebbing, vacuolation, small aggregates of chromatin around the nucleus and loss of cell adhesion were observed. Culture filtrate from Shigella dysenteriae produced cytotoxic effect on cell of muscle fibers with acute cell injuries suspected to be related to the apoptotic cell death.