Cellular and molecular dysregulation of the esophageal epithelium in systemic sclerosis.

Systemic sclerosis (SSc) is a rare autoimmune disease characterized by vasculopathy and fibrosis of the skin and internal organs. Individuals with SSc often suffer from chronic acid reflux and dysphagia due to loss of esophageal motility. To determine whether distinct changes in esophageal epithelial cells contribute to esophageal involvement in SSc, we investigated the stratified squamous esophageal epithelium from proximal and distal biopsies using single-cell RNA sequencing in individuals with SSc compared with those with gastroesophageal reflux disease (GERD) and healthy controls. Cellular and molecular changes in SSc were highly correlated with those seen in GERD, indicating they were secondary to reflux; however, their magnitudes were more pronounced in the proximal esophagus, suggesting that esophageal dysmotility leads to greater proximal acid exposure, which may contribute to aspiration. SSc-specific gene dysregulation implicated immunoregulatory pathways likely pertinent to pathogenic mechanisms. Ligand-receptor interaction analysis revealed enhanced profibrotic signaling between fibroblasts and epithelial cells in SSc. Cell type localization and SSc-specific changes were confirmed by spatial molecular imaging. By offering a comprehensive view of transcriptional dysregulation at single-cell resolution in human esophageal epithelial cells in SSc compared with GERD and healthy tissue, this work clarifies the state of epithelial cells in SSc-induced esophageal dysfunction.