Entamoeba histolytica Interaction with Enteropathogenic Escherichia coli Increases Parasite Virulence and Inflammation in Amebiasis.

Epidemiological studies suggest frequent association of enteropathogenic bacteria with during symptomatic infection. In this study, we sought to determine if the interaction with enteropathogenic (EPEC) or nonpathogenic (strain DH5α) could modify the virulence of to cause disease in animal models of amebiasis. studies showed a 2-fold increase in CaCo2 monolayer destruction when interacted with EPEC but not with DH5α for 2.5 h. This was associated with increased proteolytic activity as revealed by zymogram analysis and degradation of the CP-A1/5 (CP-A1/5) peptide substrate Z-Arg-Arg-pNC and CP4 substrate Z-Val-Val-Arg-AMC. Additionally, -EPEC interaction increased , -, -, and -, , , and C mRNA expression. Despite the marked upregulation of virulence factors, nonsignificant macroscopic differences in amebic liver abscess development were observed at early stages in hamsters inoculated with either -EPEC or - DH5α. Histopathology of livers of -EPEC-inoculated animals revealed foci of acute inflammation 3 h postinoculation that progressively increased, producing large inflammatory reactions, ischemia, and necrosis with high expression of , , and proinflammatory cytokine genes compared with that in livers of - DH5α-inoculated animals. In closed colonic loops from mice, intense inflammation was observed with -EPEC manifested by downregulation of mRNA with a corresponding increase in the expression of mucin and proinflammatory cytokine genes , , and These results demonstrate that /EPEC interaction enhanced the expression and production of key molecules associated with virulence, critical in pathogenesis and progression of disease.