Spatiotemporal Analysis of Lung Immune Dynamics in LethalCoccidioides posadasiiInfection

Abstract

AbstractCoccidioidomycosis, or Valley Fever, is a lung disease caused by inhalation ofCoccidioidesfungi, 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 duringCoccidioidesinfection. We identified monocyte-derivedSpp1-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 ofCoccidioidesinfection and suggest new therapeutic targets.Importance:Coccidioidomycosis, commonly known as Valley Fever, is a lung disease caused by the inhalation ofCoccidioidesfungi, which is prevalent in the Southwestern U.S., Mexico, and parts of Central and South America. With climate change potentially expanding the geographic range of this fungus, understanding the immune responses during severe infections is crucial. Our study used advanced techniques to analyze lung responses duringCoccidioidesinfection, identifying specific immune cells that may contribute to tissue damage and fibrosis. These findings provide new insights into the disease mechanisms and suggest potential targets for therapeutic intervention, which could improve outcomes for patients suffering from severe Valley Fever.