Virulence factor candidalysin impairs epithelial barrier integrity and initiates inflammation in a gut-on-chip model

Candida albicans is an opportunistic pathogenic yeast commonly found in the gastrointestinal tract, vagina, and oral cavity of healthy humans. Under certain conditions, it can become invasive, causing mucosal or life-threatening systemic infections. One mechanism used by C.albicans to breach the epithelial barrier is the secretion of candidalysin, a cytolytic peptide toxin. Candidalysin damages epithelial membranes but also activates the innate epithelial immune response, making it a key player in the pathogenicity of C.albicans and a promising therapeutic target. Although candidalysin is known to mediate transcellular translocation of C. albicans through intestinal layers, the epithelial response to candidalysin remains an area of active research. This study aims to characterize this response using gut-on-chip models with Caco-2 and colon organoid tubules. We used the OrganoPlate, a microfluidic platform supporting the culture of 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 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 in C. albicans pathogenesis and suggests new therapeutic strategies targeting this toxin. Moreover, the use of patient-derived organoids in toxin response studies shows promise for capturing patient heterogeneity and developing personalized treatments.