Single-nucleus chromatin accessibility identifies a critical role for TWIST1 in idiopathic pulmonary fibrosis myofibroblast activity

In idiopathic pulmonary fibrosis (IPF) myofibroblasts are key effectors of fibrosis and architectural distortion by excessive deposition of extracellular matrix and their acquired contractile capacity. Single-cell RNA-sequencing has precisely defined the IPF myofibroblast transcriptome, but identifying critical transcription factor activity by this approach is imprecise. We performed and integrated snATAC-seq and scRNA-seq from human IPF and donor control explants to identify differentially accessible chromatin regions and enriched transcription factor motifs within lung cell populations. TWIST1 and other E-box transcription factor motifs were significantly enriched in IPF myofibroblasts compared to both IPF non-myogenic and control fibroblasts. TWIST1 expression was also selectively upregulated in IPF myofibroblasts. Overexpression of Twist1 in lung COL1A2-expressing fibroblasts in bleomycin-injured mice was associated with increased collagen synthesis. Our studies utilizing human multiomic single-cell analyses combined with in vivo murine disease models confirm a critical regulatory function for TWIST1 in IPF myofibroblast activity in the fibrotic lung. Understanding the global process of opening TWIST1 and other E-box TF motifs that govern myofibroblast differentiation may identify new therapeutic interventions for fibrotic pulmonary diseases.