Breaking barriers: the fungal toxin candidalysin disrupts epithelial integrity and induces inflammation in a gut-on-chip model

Candida albicansis an opportunistic pathogenic yeast commonly found in the gastrointestinal tract, vagina, and mouth of healthy humans. Under certain conditions, it can become invasive, causing mucosal or life-threatening systemic infections. One mechanism used byC.albicansto breach the epithelial barrier is the secretion of candidalysin, a cytolytic peptide toxin. Candidalysin damages epithelial membranes and activates the innate epithelial immune response, making it key toC.albicans’pathogenicity and a promising therapeutic target. Although candidalysin mediatesC. albicanstranslocation through intestinal layers, its impact on epithelial responses is not fully understood.

This study aims to characterize this response and develop scalable, quantitative methodologies to assess candidalysin’s toxicological effects using gut-on-chip models.

We used the OrganoPlate®, a microfluidic platform to culture up to 64 perfused, membrane-free intestinal epithelial tubes. We exposed Caco-2 tubes to candidalysin and evaluated their response with trans-epithelial electrical resistance (TEER), protein detection, and immunostaining. We then validated our findings in a proof-of-concept experiment using human intestinal organoid tubules.

Candidalysin impaired barrier integrity, as indicated by decreased TEER and increased permeability in a fluorescent dye assay. It also induced actin remodeling and DRAQ7™ dye uptake, a marker of cell permeability. This disruption was associated with the release of LDH, cytokines, and the antimicrobial peptide LL37, suggesting cellular damage, inflammation, and antimicrobial activity.

This study strengthens our understanding of candidalysin’s role inC. albicanspathogenesis and suggests new therapeutic strategies targeting this toxin. Moreover, the use of patient-derived organoids shows promise for capturing patient heterogeneity and developing personalized treatments.