Toxigenic C. difficile induced inflammatory marker expression by human intestinal epithelial cells is asymmetrical

Area of Science:

• Microbiology
• Immunology
• Gastroenterology

Background:

• Clostridium difficile infection (CDI) causes significant morbidity and mortality, primarily attributed to toxin production.
• The precise mechanisms initiating CDI pathogenesis, particularly epithelial responses, require further elucidation.

Purpose of the Study:

• To investigate the role of toxigenic C. difficile in modulating human intestinal epithelial cell responses.
• To determine the involvement of specific inflammatory mediators, IL-8 and ICAM-1, in CDI pathogenesis.

Main Methods:

• Utilized in vitro models of human intestinal epithelial layers.
• Exposed epithelial layers to toxigenic C. difficile and toxin-containing supernatants.
• Assessed the expression of IL-8 and ICAM-1, and measured transepithelial electrical resistance.

Main Results:

• Toxigenic C. difficile upregulated epithelial IL-8 and ICAM-1 expression.
• IL-8 production was stimulated by both bacteria and their toxins, and inhibited by antiserum.
• ICAM-1 upregulation required basolateral exposure, while apical exposure impaired epithelial integrity.
• Apical exposure to C. difficile compromised transepithelial electrical resistance, suggesting barrier disruption.

Conclusions:

• C. difficile infection initiates inflammatory responses through upregulation of IL-8 and ICAM-1.
• Epithelial barrier disruption by apical bacterial exposure facilitates basolateral access, activating inflammatory pathways.
• These findings suggest a model where initial epithelial damage precedes full inflammatory activation in CDI.