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CDT of Clostridioides difficile Induces MLC-Dependent Intestinal Barrier Dysfunction in HT-29/B6 Epithelial Cell
Lucas Heils1, Martina Schneemann1, Ralf Gerhard2
1Clinical Physiology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, 12203 Berlin, Germany.
Toxins
|January 20, 2023
Summary
Clostridioides difficile binary toxin (CDT) damages the intestinal barrier even at low doses by altering tight junctions, leading to diarrhea. This occurs without causing cell death, highlighting a new mechanism for intestinal dysfunction.
Area of Science:
- Microbiology
- Cell Biology
- Gastroenterology
Background:
- Clostridioides difficile binary toxin (CDT) is linked to severe, often fatal, antibiotic-induced colitis.
- Understanding CDT's role in hypervirulence is crucial for treating nosocomial infections.
Purpose of the Study:
- To investigate how CDT affects the intestinal epithelial barrier.
- To elucidate the molecular mechanisms behind CDT-induced barrier dysfunction.
Main Methods:
- Human intestinal HT-29/B6 cell monolayers were used for functional barrier measurements.
- Macromolecular permeability and electrophysiology assessed barrier integrity.
- Super-resolution STED microscopy analyzed tight junction proteins and cytoskeleton.
Main Results:
- Sublethal CDT concentrations impaired barrier function, decreasing TER and increasing permeability.
- CDT caused tight junction proteins (tricellulin, occludin, claudin-4) to redistribute away from the junction.
- This redistribution was dependent on Myosin Light Chain Kinase (MLCK).
Conclusions:
- CDT compromises intestinal epithelial barrier function in a human colonic cell model.
- Barrier dysfunction and leak flux, not apoptosis, explain CDT-induced diarrhea.
- Alterations in epithelial tight junctions are the primary mechanism of CDT's effect.
