Abstract
Human fungal pathogens, including Cryptococcus neoformans, cause 1.5 million annual deaths. Cryptococcus causes disease when it disseminates out of the lung and into the brain, which can occur years after initial exposure (latency) via mechanisms that remain unknown. Spores of Cryptococcus display distinct surface epitopes, host interactions, and disease kinetics to the vegetatively growing yeast morphotype, yet they remain understudied, likely contributing to our lack of understanding of pathogenesis. One of the first barriers spores encounter is non-professional phagocytic airway epithelial cells (AECs). Here, we demonstrate that Cryptococcus spores are preferentially internalized by AECs both in vitro and in vivo. Once inside, spores can germinate, subsequently replicate, persist, and/or escape. This ability to enter AECs correlates with a preferential ability of spores to cross AEC barriers. Together, our work indicates that AECs internalize Cryptococcus spores and may serve as a previously ignored intracellular host niche, providing alternative hypotheses for both Cryptococcus dissemination and latency.IMPORTANCEFungal spores are a dormant, stress-resistant, and relatively understudied cell type and are presumed infectious cell types in cryptococcal disease. Cryptococcus spores have been shown to display distinct disease kinetics to the vegetative yeast morphotype and are significantly better at disseminating out of the host lung. While the molecular mechanisms by which spores disseminate out of the lung have yet to be identified, their preferential ability to get inside host cells likely enables their dissemination. Here, we show that spores, unlike yeast, readily get taken up by non-professional phagocytic cells, airway epithelial cells, both in vitro and in vivo, and once inside can germinate, replicate, escape, and/or persist. These results provide a previously unexplored host cell type that Cryptococcus can inhabit, likely affecting disease kinetics and could be a critical interaction in understanding both extrapulmonary dissemination and latency.