Host Responses to Coccidioides by Human Airway Epithelium

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PROJECT SUMMARY Invasive fungal infections represent a major threat to immunocompromised patients and despite the availability of anti- fungal antibiotics, mortality rates remain as high as 50%. In the human host, the airway epithelium is the first point of contact upon inhalation of fungal conidia. As an immunologically active tissue, the airway epithelium may participate in active phagocytosis and coordinated immune cell recruitment. Soil fungi, including Coccidioides, do not need a human host to propagate, but upon disruption can enter the human body and lead to infection if not cleared. The fungal dimorph Coccidioides is native to arid regions in the southwestern U.S. and can establish infections in both immunocompetent and immunocompromised individuals. Unfortunately, little is known with regards to the initial response of human airway epithelium to Coccidioides. Currently, the Δcps1 strain of Coccidioides is being investigated as a potential vaccine candidate. Leveraging new technologies that permit the isolation of human airway stem cells, we demonstrated that primary differentiated human airway epithelial cells recapitulate the complexity of human airways. Our preliminary data showed infection at the apical surface of human airway epithelial cells by C. posadasii (Δcps1) elicits pro-inflammatory signals by the epithelium. Lastly, we demonstrated effective gene knockout in primary human airway epithelial cells using non-viral bulk nucleofection-based CRISPR strategy. Thus, our primary objective is to decipher the transcriptional and secretomal signatures critical to mount a successful response to Coccidioides in the human airway epithelium. To address our primary objective, we propose the following two specific aims: [1] determine the host response of human airway epithelium to both WT and the vaccine candidate C. posadasii (Δcps1), and [2] identify key signaling pathways to elicit an immune response to WT and the vaccine candidate C. posadasii (Δcps1) by human airway epithelium. This work will identify essential components of the human airway epithelium to mediate a protective response to these fungal infections and will provide the necessary foundation for future experiments to dissect the key pathways responsible for an effective host response to C. posadasii.