Autophagy Impairment-Derived SQSTM1 Accumulation Promotes Ferroptosis in Corneal Epithelial Cells Through ACSL4 in Dry Eye.

PURPOSE

To reveal the function of autophagy impairment-derived sequestosome 1 (SQSTM1) in inducing ferroptosis in an experimental dry eye model and investigate the underlying mechanism.

METHODS

To induce the dry eye animal model, 8-week-old C57BL/6 mice were subcutaneously injected with scopolamine and exposed to a desiccated environment. To build the in vitro dry eye model, human corneal epithelial cells (HCECs) were applied with desiccating stress. Cell viability was examined using a CCK-8 kit. Intracellular reactive oxygen species (ROS), oxidative lipid, and Fe2+ were detected using the H2DCFDA assay kit, C11 BODIPY probe, and FerroOrange probe. Gene expression was screened by RNA sequencing. Protein expression was evaluated by western blot and immunofluorescence staining. Corneal defect area was assessed by fluorescein sodium staining. Conjunctiva goblet cells were counted by periodic acid-Schiff staining. Tear secretion was measured using phenol red cotton thread.

RESULTS

Desiccating stress induced ferroptosis and SQSTM1 accumulation in both HCECs and C57BL/6 mice. SQSTM1 knockdown alleviated ferroptosis in HCECs. In contrast, the overexpression of SQSTM1 promoted ferroptotic changes. Additionally, overexpression of SQSTM1 significantly increased acyl-CoA synthetase long chain family member 4 (ACSL4). Also, targeted inhibition of ACSL4 mitigated the dry eye symptoms and ferroptosis caused by both SQSTM1 overexpression and desiccating stress.

CONCLUSIONS

The accumulation of SQSTM1 triggers corneal epithelial cells ferroptosis through ACSL4 in dry eye disease.