Airway epithelial cells as a novel intracellular host reservoir for Cryptococcus spores

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 are non-professional phagocytic Airway Epithelial Cells (AECs). Here, we demonstrated that Cryptococcus spores preferentially invade 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 spore to cross AEC barriers. Together our work indicates that AECs can be invaded by Cryptococcus spores and may serve as a previously ignored intracellular host niche, providing alternative hypothesis for both Cryptococcus dissemination and latency.