Spatiotemporal Analysis of Lung Immune Dynamics in Lethal Coccidioides posadasii Infection

Coccidioidomycosis, or Valley Fever, is a lung disease caused by inhalation of Coccidioides fungi, prevalent in the Southwestern U.S., Mexico, and parts of Central and South America. 350,000 cases are reported annually in the U.S., although that number is expected to increase as climate change expands fungal geographic range. While 60% of infections are asymptomatic, the symptomatic 40% are often misdiagnosed due to similarities with bronchitis or pneumonia. A small subset of infection progress to severe illness, necessitating a better understanding of immune responses during lethal infection. Using single-cell RNA sequencing and spatial transcriptomics, we characterized lung responses during Coccidioides infection. We identified monocyte-derived Spp1 -expressing macrophages as potential mediators of tissue remodeling and fibrosis, marked by high expression of profibrotic and proinflammatory transcripts. These macrophages showed elevated TGF-β and IL-6 signaling, pathways involved in fibrosis pathogenesis. Additionally, we observed significant neutrophil infiltration and defective lymphocyte responses, indicating severe adaptive immunity dysregulation in lethal, acute infection. These findings enhance our understanding of Coccidioides infection and suggest new therapeutic targets.