Corneal Stiffening and Hyperosmolar Stress Associate With YAP1/TAZ Activation and Ocular Surface Inflammation in Dry Eye Disease

Purpose: To test whether corneal biomechanical remodeling and hyperosmolar stress activate Yes-associated protein 1 (YAP1)/transcriptional coactivator with PDZ-binding motif (TAZ) signaling in dry eye disease (DED), and whether YAP1/transcriptional enhanced associate domain (TEAD) activity is required for ocular surface inflammation in vivo. Methods: A desiccating stress (DS) mouse model was established using low humidity and scopolamine. Tear secretion, corneal fluorescein staining, and stromal stiffness were measured. YAP1/TAZ activity was assessed. DS mice received topical verteporfin (VP) or vehicle control. Human corneal epithelial cells (HCECs) were cultured on substrates of defined stiffness (8, 25, and 50 kPa) and exposed to hyperosmolar medium (500 mOsm) with YAP1 overexpression or knockdown. Public single-cell RNA sequencing data (GSE182582) were reanalyzed. Results: DS reduced tear secretion and increased corneal fluorescein staining and central stromal stiffening. Decreased phosphorylated YAP1 (p-YAP1) and increased nuclear YAP1 indicated pathway activation. Topical VP reduced corneal injury and decreased YAP1, TAZ, connective tissue growth factor (CTGF), interleukin-1β (IL-1β), and interleukin-6 (IL-6), while increasing p-YAP1. In HCECs, substrate stiffness and hyperosmolar stress increased YAP1 activation and inflammatory mediator expression; YAP1 silencing attenuated these responses, whereas YAP1 overexpression enhanced them. Single-cell reanalysis showed inflammatory enrichment in squamous epithelial cells with increased YAP1/WW domain-containing transcription regulator 1 (WWTR1) expression and Hippo pathway activation. Conclusions: Corneal stiffening and hyperosmolar stress are associated with YAP1/TAZ activation and epithelial inflammation in DED. YAP1/TEAD inhibition in DS mice ameliorates corneal injury and inflammatory signaling, supporting functional involvement. Translational Relevance: Pharmacologic modulation of YAP1/TEAD signaling may represent a therapeutic strategy for inflammation-dominant DED.