C29-02 A Single-cell Transcriptomic Atlas Reveals Distinct Cellular Landscapes in Rare Diffuse Cystic Lung Diseases

Abstract Background Diffuse cystic lung diseases (DCLD) represent a subtype of interstitial lung diseases comprising a spectrum of distinct entities. However, a systematic comparison of the cellular composition across different DCLD types is lacking, hindering a deeper understanding of their respective pathogenic mechanisms. To address this, we applied single-cell transcriptomics to profile multiple DCLDs and elucidate their cell-type-specific alterations. Methods We performed single-cell RNA sequencing on 25 samples encompassing 177,818 cells from patients with Birt-Hogg-Dubé (BHD; n = 4), Lymphangioleiomyomatosis (LAM; n = 11), Ehlers-Danlos syndrome (EDS; n = 1), Langerhans cell histiocytosis (LCH; n = 3), as well as healthy controls (n = 6). High-resolution cellular mapping was employed to systematically identify cell subtypes across epithelial, immune, and stromal lineages, with cross-disease enrichment analyzed using the Ro/e ratio. Results The single-cell atlas revealed distinct cellular identities for each DCLD. The most prominent feature of BHD syndrome is the extreme enrichment of epithelial-mesenchymal transition-like (Epi-EMT-like) cells, which exhibit coordinated activation of EMT, hypoxia, and angiogenesis pathways. LAM is characterized by the significant enrichment of fibroblast/smooth muscle cells, mast cells, plasma cells, and plasmacytoid dendritic cells (pDC), indicating a unique fibrotic and immune microenvironment. EDS presents a distinctive immune response pattern, with extensive involvement of B cells, monocyte/macrophages, and pDCs. LCH is primarily defined by the enrichment of Langerhans cell-like dendritic cells (cDC LC), the hallmark cells of the disease, accompanied by the enrichment of B cells and monocyte/macrophages. Furthermore, both LCH and LAM shared significant enrichment of Basal and Club cells, implying a potential common pathogenic pathway in airway epithelial remodeling. Conclusions This study establishes the first comprehensive single-cell transcriptomic atlas of DCLDs, revealing disease-specific cellular populations and their abundance variations. The constructed atlas provides a valuable foundational resource for elucidating the pathogenic mechanisms of DCLDs, identifying disease-driving cell types, and developing targeted therapeutic strategies, thereby offering significant scientific insight and innovative value. Figure 1 Single-Cell Transcriptomic Profiling of Different Cystic Lung Diseases. (A) UMAP projection of all single cells from Control, BHD, LAM, EDS, and LCH samples. Each point is a cell, colored by sample origin. (B) Same UMAP plot colored by defined cell types, with 12 major types listed. (C) Heatmap of cell type enrichment (red, Ro/e 1) or depletion (blue, Ro/e 1) across groups. Asterisks (***) indicate statistical significance. (D) QuSAGE dot plot shows activity of key signaling pathways (orange, up-regulated; blue, down-regulated). Dot size corresponds to statistical significance (-log10(FDR)). This abstract is funded by: Natural Science Foundation of Guangdong Province (2023A1515010308)、Project of 2022 Student Innovation Ability Enhancement Program of Guangzhou Medical University (02-408-2203-2106)、Guangdong Province 2022 Graduate Education Innovation Plan project(2022ANLK049)