Objectives:

Opportunistic infections represent a serious health threat to immunocompromised patients nowadays. One group of relevant fungal pathogens are the Mucorales. Members of this group play an increasing role in the clinic, but still only little is known about their biology, disease establishment, progression, and immune response. As for other filamentous fungi, the infectious agents are inhaled spores. Therefore, we study the interaction of clinically relevant Mucorales with bronchial and alveolar epithelial cells that are most likely the first cells of contact.

Methods:

In order to enhance throughput and facilitate comparison of different Mucorales species, we adapted a flow cytometric method to study phagocytosis by lung epithelial cells and macrophages in vitro. With this method we can distinguish between internalized and attached spores by differential staining using FITC and uvitex. As representatives of alveloar epithelial cells we used A549 cell line and NHBE cells as an example for bronchial epithelial cells. Furthermore, we tested our method also with ThP1- macrophages.

Results:

Our results so far show that significant difference in phagocytosis rates are obvious within the various Mucorales species by lung epithelial cells, whereas in macrophages phagocytosis rates of different Mucorales species were similar.

Conclusion:

Our results so far indicate that mechanisms for recognition, binding and uptake of Mucorales spores is not only species dependent, but also is variable in different cell types. Future work will aim to elucidate the parameters involved in recognition and uptake and shed light on the fate of internalized Mucorales spores.

Phagocytosis of Mucorales spores by lung epithelial cells and macrophages