Conan, N.; Marthe, L.; Shekoory, A.; Latour-Lambert, P.; Franetich, J.-F.; Larsen, M.; Weiner, A.

Candida albicans is an opportunistic fungal pathogen normally found as a commensal in human mucosa. In susceptible patients, its hyphal filamentous form can invade and damage host epithelium leading to local or systemic infection. The secreted fungal toxin candidalysin is required for epithelial damage, although both hyphal extension and candidalysin are required for inducing maximal infection damage, for reasons that are not well understood. Here we study the interplay between hyphal extension and host damage in vitro using live cell imaging combined with damage-sensitive reporters followed by single-cell level quantitative analysis. We show that fungal load is inversely proportional to single-cell damage potential, and we quantify candidalysin-induced damage. We then determine the three-dimensional architecture of invasion and show that the spatial organization of host membrane rupture is regulated by candidalysin and is predictive of host cell death. Finally, we demonstrate that membrane rupture occurs at two distinct host subcellular niches: the juxtanuclear region and the cell-cell boundary, with the latter the main driver of subsequent host cell death. Based on these results, we propose that C. albicans invasion damages epithelia in a sequential process in which candidalysin secretion acts to prime host membranes enveloping invading hyphae for subsequent rupture. Hyphal traversal of two distinct host subcellular niches then triggers membrane rupture, resulting in a niche-specific host response that is predictive of host cell survival or death.