Abstract
Heat-labile toxin I (LT-I), produced by strains of enterotoxigenic Escherichia coli (ETEC), causes profuse watery diarrhea in humans. Different in vitro and in vivo models have already elucidated the mechanism of action of this toxin; however, their use does not always allow for more specific studies on how the LT-I toxin acts in systemic tracts and intestinal cell lines. In the present work, zebrafish (Danio rerio) and human intestinal cells (Caco-2) were used as models to study the toxin LT-I. Caco-2 cells were used, in the 62nd passage, at different cell concentrations. LT-I was conjugated to FITC to visualize its transport in cells, as well as microinjected into the caudal vein of zebrafish larvae, in order to investigate its effects on survival, systemic traffic, and morphological formation. The internalization of LT-I was visualized in 3 × 104 Caco-2 cells, being associated with the cell membrane and nucleus. The systemic traffic of LT-I in zebrafish larvae showed its presence in the cardiac cavity, yolk, and regions of the intestine, as demonstrated by cardiac edema (100%), the absence of a swimming bladder (100%), and yolk edema (80%), in addition to growth limitation in the larvae, compared to the control group. There was a reduction in heart rate during the assessment of larval survival kinetics, demonstrating the cardiotoxic effect of LT-I. Thus, in this study, we provide essential new depictions of the features of LT-I.
Highlights
Heat-labile toxin I (LT-I) is one of the two toxins produced by enterotoxigenic Escherichia coli (ETEC) strains, a pathotype responsible for approximately 10 million cases of diarrhea per year worldwide, mainly affecting children under five years old in low-income areas of developing countries [3,4]
Real target of the toxin LT-I than adrenal and epithelial cells of murine origin do, for use as Rhodamine phalloidin and DAPI fluorophores at 1:200 dilutions allowed for mi an in vitro model for the detection and neutralization of the LT-I toxin
1), where the efficiency ofa labeling toxin LT-I with the analysis of the LT-I
Summary
Heat-labile toxin I (LT-I) is one of the two toxins produced by enterotoxigenic Escherichia coli (ETEC) strains, a pathotype responsible for approximately 10 million cases of diarrhea per year worldwide, mainly affecting children under five years old in low-income areas of developing countries [3,4]. It is considered the main pathotype that causes “traveler’s diarrhea,” which is associated with visitors in transit through some settings in 4.0/). Its internalization occurs mainly through the binding of the B sub-unit to the GM1 ganglioside receptor present in the intestinal epithelium, which is responsible for enabling the internalization of the enzymatically active A sub-unit of the toxin [6,7,8]
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