Heat-Labile Toxin from Enterotoxigenic Escherichia coli Causes Systemic Impairment in Zebrafish Model

Author(s)

Henrique, Camila ^[1] ; Pimentel Falcao, Maria Alice ^[2] ; Pimenta, Luciana De Araujo ^[3] ; Almeida Maleski, Adolfo Luis ^[2] ; Lima, Carla ^[2] ; Mitsunari, Thais ^[1] ; Sampaio, Sandra Coccuzzo ^[3] ; Lopes-Ferreira, Monica ^[2] ; Fontes Piazza, Roxane Maria ^[1]

Affiliation

^[1] Inst Butantan, Lab Bacteriol, BR-05503900 Sao Paulo, SP - Brazil

^[2] Inst Butantan, Lab Toxinol Aplicada, BR-05503900 Sao Paulo, SP - Brazil

^[3] Inst Butantan, Lab Fisiopatol, BR-05503900 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: TOXINS; v. 13, n. 6 JUN 2021.
• Web of Science Citations: 0

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 x 10(4) 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. (AU)

• FAPESP's process: 13/07467-1 - CeTICS - Center of Toxins, Immune-Response and Cell Signaling
• Grantee: Hugo Aguirre Armelin
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 17/17213-8 - Heat Labile (LT) and heat-stable (st) toxins produced by Enterotoxigenic Escherichia coli: study of a new in vivo model for the evaluation of the neutralizing potential of recombinant antibodies
• Grantee: Camila Henrique Pinto
• Support Opportunities: Scholarships in Brazil - Doctorate