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Published on: December 23, 2022
Cytolethal distending toxin-producing Escherichia coli clinical isolates from Mexican children harbor different cdt
Jazmin Huerta-Cantillo1, Lucia Chavez-Dueñas1, Mussaret Bano Zaidi2,3
1Department of Cell Biology, CINVESTAV-IPN, Av. IPN 2508, 07360, Mexico City, Mexico.
Abstract:
Cytolethal distending toxins (CDTs), encoded by cdtABC genes, have DNase activity leading to cellular and nuclear distention, resulting in actin remodeling, irreversible cell cycle arrest and apoptosis of target cells. PCR cdt-positive Escherichia coli strains have been isolated from children with diarrhea worldwide. However, toxin production and biological activity of cdt+ strains are rarely confirmed. Here, we characterized the biological activity of cdt+ E. coli of clinical isolates from Mexican children with severe diarrhea and its relationship with the harbored cdt type. Ten isolates from seven patients containing cdt+ E. coli, one isolate from a patient containing cdt- E. coli, and a prototype CDT-producing E. coli were used to determine the harbored cdt-type, cell distention, actin remodeling and cell cycle arrest on epithelial cells. Three isolates harbored cdt type I, one type II, two type III, two type IV and two simultaneously type II and III. Lysates from eight cdt+ E. coli isolates caused cell distention, actin cytoskeletal remodeling and cell cycle arrest but two isolates from the same patient harboring simultaneously cdt type II/III did not. The cdt genes were necessary and enough to cause the cytolethal distending pathology. Mutants in cdtABIC (O86:H34 strain; cdt-I) and cdtABIIC (isolate; cdt-II) were complemented by cdtABIIC genes and both recovered the CDT-induced phenotypes. Transformation of E. coli BL21 by cdtABIIC genes caused this cytolethal distending pathology. These data indicate that cdt + E. coli isolates are potentially dangerous bacteria to cause serious epithelial cell damage and cell death to aggravate childhood diarrhea.
Insights
Cytolethal distending toxins (CDTs) from E. coli cause severe diarrhea in children. These toxins damage epithelial cells, leading to cell cycle arrest and apoptosis, highlighting the danger of cdt-positive E. coli.
Area of Science:
- Microbiology
- Molecular Biology
- Cell Biology
Background:
- Cytolethal distending toxins (CDTs) are virulence factors produced by various bacteria, including Escherichia coli (E. coli).
- CDTs possess DNase activity, inducing cell cycle arrest, apoptosis, and characteristic cell distention in target cells.
- While PCR can detect cdt genes in E. coli from diarrheal cases, toxin production and biological activity are often unconfirmed.
Purpose of the Study:
- To characterize the biological activity of cdt-positive E. coli clinical isolates from Mexican children with severe diarrhea.
- To investigate the relationship between harbored CDT types and their pathogenic effects on epithelial cells.
- To confirm the necessity and sufficiency of cdt genes in causing cytolethal distending pathology.
Main Methods:
- PCR was used to identify cdt-positive E. coli strains.
- Clinical isolates were analyzed for harbored cdt types (I, II, III, IV).
- Bacterial lysates were used to assess effects on epithelial cells, including cell distention, actin remodeling, and cell cycle arrest. Gene complementation and transformation experiments were performed.
Main Results:
- Ten cdt-positive E. coli isolates from seven children with severe diarrhea were analyzed, along with one cdt-negative isolate and a control strain.
- Eight of the ten cdt-positive isolates induced cell distention, actin remodeling, and cell cycle arrest in epithelial cells.
- The cdt genes were confirmed as necessary and sufficient for CDT-induced pathology, with successful complementation and transformation experiments demonstrating this.
Conclusions:
- cdt-positive E. coli isolates from children with severe diarrhea exhibit significant cytotoxic activity, causing epithelial cell damage and potentially aggravating diarrhea.
- The specific type of harbored cdt gene influences toxin activity, though some co-harbored types may lead to reduced activity.
- These findings underscore the potential danger posed by cdt-positive E. coli in pediatric diarrheal diseases.
