Single-Cell Transcriptomics Reveals Immune Remodeling of the Murine Lung Microenvironment Following Chronic House Dust Mite Exposure

Han Chang^*Liping ZengZahra MalakoutikhahChanond A. NasamranScott HerdmanMaripat CorrKathleen M. FischNicholas J.G. WebsterEyal RazSamuel Bertin^*

• University of California San Diego, La Jolla, United States

House dust mite (HDM) is a common environmental aeroallergen strongly associated with asthma and chronic airway inflammation. Using single-cell RNA sequencing (scRNA-seq), we investigated how chronic HDM exposure remodels the murine lung immune microenvironment, with a particular focus on the role of interleukin-1β (IL-1β). While acute HDM exposure elicits T helper 2 (Th2)-driven eosinophilic inflammation, hallmarks of the eosinophilic endotype of asthma, the chronic effects on neutrophilic inflammation, which is associated with IL-1β signaling and steroid-resistant asthma, as well as possible links to inflammation-associated lung cancer, remain poorly understood. Our analysis reveals that chronic HDM exposure promotes the recruitment and activation of diverse immune cell populations in the lungs, including neutrophils, M2-polarized macrophages, B-2 (follicular) B cells, and multiple subsets of regulatory and effector CD4+ T cells. These distinct immune populations contribute differently to the development or resolution of chronic lung inflammation via IL-1β-dependent or -independent mechanisms. While scRNA-seq analysis indicated that IL-1β signaling is critical for sustaining neutrophil and Th17 responses and that its deficiency promotes Th2-skewed polarization, our validation experiment using histopathology, RT-qPCR, ELISA, and immunofluorescence revealed that these effects depend on the endotoxin content of allergen extracts. Together, these findings provide a detailed cellular and molecular atlas of the lung immune landscape following chronic HDM exposure and highlight the context-dependent role of IL-1β in orchestrating inflammatory responses.