Klotho relieves H₂O₂-induced lens epithelial cell damage via suppression of NOX4

Age-related cataract (ARC) is a common eye disease and represents a common contributing factor to visual damage and loss. Klotho is a longevity gene and has been reported to participate in aging-related disorders. This work aims to investigate the potential role of klotho in ARC.

In human lens epithelial cells (HLECs) induced by varying concentrations of hydrogen peroxide (H₂O₂), CCK-8 assay was used to detect cell viability. DCFH-DA probe was used to detect reactive oxygen species (ROS) level. Western blot was used to detect klotho expression. JC-1 fluorochrome assay was used to detect mitochondrial membrane potential (MMP). The concentrations of oxidative stress markers malondialdehyde (MDA) and superoxide dismutase (SOD) were detected by related assay kits. Flow cytometry analysis, immunofluorescence staining and western blot were used to detect cell apoptosis. SA-β-gal staining and western blot were used to detect cell senescence.

Klotho expression was decreased in HLECs induced by increasing concentrations of H₂O₂. Overexpression of klotho significantly inhibited ROS generation, decreased MDA content, increased SOD content, promoted cell viability and suppressed cell apoptosis and senescence in H₂O₂-induced HLECs. Furthermore, klotho down-regulated NOX4 expression and NOX4 elevation partially reversed the effects of klotho on H₂O₂-induced HLECs.

To sum up, klotho may down-regulate NOX4 to protect against H₂O₂-induced HLECs damage. This finding suggested the potential therapeutic use of klotho in ARC, which needs further investigation.