Norepinephrine Attenuates Benzalkonium Chloride-Induced Dry Eye Disease by Regulating the PINK1/Parkin Mitophagy Pathway.

BACKGROUND: Increased reactive oxygen species (ROS) are involved in the pathological process of dry eye disease. Our previous results suggested that norepinephrine (NE) has a protective effect on dry eye.

PURPOSE: This study explored the potential therapeutic role and underlying mechanisms of NE in benzalkonium chloride (BAC)-induced dry eye disease.

METHODS: BAC-pretreated human corneal epithelial cells (HCEpiC) were cultured with various concentrations of NE. A BAC-induced dry eye mice model was established to explore the role of NE. Alterations in mice corneal tissues, ROS levels, mitochondrial function, and mitophagy levels were analyzed.

RESULTS: In vitro, our results revealed that BAC-exposed HCEpiC led to mitochondrial malfunction, which involved excessive ROS production, decreased mitochondrial membrane potential (MMP), and promoted mitochondrial fragmentation through increased DRP1 and fission protein 1 (Fis1) expression and reduced mitofusin 2 (Mfn2) expression. Moreover, topical BAC application induced excessive mitophagy. These effects were reversed by NE. Additionally, the increased expression of LC3B, SQSTM1/p62, PINK1, and Parkin, which control mitophagy, in BAC-exposed HCEpiC was suppressed by NE. In BAC-induced C57BL/6J mice, NE resulted in lower fluorescein staining scores, decreased TUNEL-positive cells, and decreased mitochondrial fragmentation.

CONCLUSIONS: In conclusion, our findings showed that NE therapy prevented HCEpiC following BAC application by regulating mitochondrial quality control, which is controlled by PINK1/Parkin-dependent mitophagy. Our research suggests a potential targeted treatment for dry eye disease.