Mecanismo molecular de patogenicidade da enterotoxina citotoxica de Aeromonas hydrophila

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The cytotoxic enterotoxin secreted by Aeromonas hydrophila (Ent-ctx) produces hemolytic and cytotoxic activities and possesses the ability to evoke a fluid secretory response in a ligated intestinal loop model, amongst other biological activities. In this study, rat erythrocytes were the most sensitive to the hemolytic activity. The cytopathic effects were neutralized using antiserum purified against the cytotoxin of A. hydrophila (titer >1 :16384). The immunoblotting analysis revealed one only band with molecular weight of 54 kDa. Vero (African green monkey kidney) and HT29 (human epithelial intestinal) cells treated with the Ent-ctx became round and lost their adhesion to each other and to the substrate. Cytoplasmic blebbing, nuclear condensation, fragmentation and formation of apoptotic bodies also occurred. Intemucleosomal DNA fragmentation was detected by TUNEL labeling, Feulgen staining in situ and agarose gel electrophoresis. These results confirmed that the Ent-ctx of A. hydrophila induces apoptosis in HT29. The cytotoxic response of this enterotoxin was irreversible and progressive showed that the lost of mitochondrial function come first that destruction of membrane permeability. In vivo studies revealed a dramatic structural disorganization, leading organelles damage, degeneration of epithelial cells and lost of the connective tissue in rat epithelial intestinal cells. Microscopic observations showed migration of eosinophils and neutrophils through the intestinal epithelium. Using L T-I, STa, and STb of E.coli as probe no homology to the whole cell DNA of A.hydrophila (AH 191) strain was detected on PCR analyses. These alterations induced by the cytotoxic enterotoxin of A. hydrophila, suggest that mechanism of this toxin could be associated to the enteropathogenicity involving A.hydrophila strains

ASSUNTO(S)

apoptose toxinas bacterianas

ACESSO AO ARTIGO

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