Identification of an airway smooth muscle gene expression profile in COPD tissue versus control using spatial transcriptomics

<bold>Introduction:</bold> Airway smooth muscle (ASM) cells are essential for airway contraction and the maintenance of airway calibre. Airway smooth muscle thickness and altered function is a feature of COPD associated with airway inflammation, hyperresponsiveness and airway remodelling. However, spatial resolved studies looking at ASM gene expression are lacking on whole lung tissue sections currently. Spatial transcriptomics has the power to detect region and cell type specific gene expression profiles. <bold>Aims:</bold> To identify a spatially resolved airway smooth muscle gene expression profile in lung tissue derived from donors with COPD versus control tissue. <bold>Methods:</bold> Sections of human lung tissue were obtained from lung resection from control donors (n=3) and donors with a diagnosis of COPD (n=3). Slides were hybridised with the GeoMx Human Whole Transcriptome Atlas. ASM regions were identified by ACTA2 positive staining and histological features. mRNA hybridised barcodes were collected from airway smooth muscle regions (minimum 30 cells), pooled together and library prepared and sequenced. Count files were analysed in R using StandR and Limma. <bold>Results:</bold> We identified 14 genes (5% FDR) differentially expressed in the ASM in COPD tissues versus ASM in control lung tissue (10 regions v 5, respectively). Among these was <italic>TPM3</italic> (upregulated in COPD), which codes for Tropomyosin 3, a protein involved in smooth muscle contraction. <bold>Conclusion:</bold> This study has begun to identify a spatially resolved ASM gene expression profile in COPD lung tissue vs. control. Although there are modest gene expression changes, future work aims to expand these datasets to additional donors.