Piezo1 Activation by Shear Stress Induces Corneal Epithelial Homeostasis Disruption

The shear stress induced by abnormal blinking compromises tear film stability. This study aimed to investigate the effects of shear stress on corneal epithelial homeostasis and the role of the mechanosensor Piezo1 in this process.

In vivo, abnormal ocular surface shear stress was induced in C57BL/6J mice using a controlled blinking model. Corneal damage was assessed via fluorescein staining and tear secretion. In vitro, human SV40 immortalized corneal epithelial cells were exposed to low-level shear stress (L-SS, 2.6 dyn/cm²) or high-level shear stress (H-SS, 7 dyn/cm²), calibrated by computational fluid dynamics simulation. Piezo1 was modulated using Yoda1 and lentivirus-mediated knockdown. Proliferation, migration, pyroptosis, and intercellular junctions were evaluated via EdU, scratch assays, transmission electron microscopy, and immunofluorescence, respectively.

In vivo, increased blinking frequency caused corneal damage, reduced tear secretion, and Piezo1 upregulation. In vitro, both L-SS and H-SS activated Piezo1, modulating proliferation and migration via Ca2+ influx. L-SS upregulated zonula occludens 1 (ZO-1), promoting tight junction formation. In contrast, H-SS induced Piezo1 overactivation, which downregulated ZO-1, compromising barrier function, and upregulated pyroptosis markers (NLRP3, caspase-1, GSDMD, and IL-1β). Notably, these shear stress-induced biological effects were significantly reversed after Piezo1 knockdown.

This study established Piezo1 as a critical mechanosensor that mediates intensity-dependent responses caused by ocular surface shear stress in the corneal epithelial homeostasis. Specifically, Piezo1-mediated mechanotransduction under high-intensity shear stress triggers barrier failure and pyroptosis, highlighting Piezo1 as a promising therapeutic target for managing shear stress-related ocular surface disorders.