<scp>TIMP3</scp> Suppresses Oxidative Stress and Ferroptosis of Lens Epithelial Cells in Cataract Through Regulating the Keap1/Nrf2 Pathway

Cataract is the dominant cause of reversible blindness globally. Oxidative stress-induced lens epithelial cell death plays a key role in cataract, in which ferroptosis caused by lipid peroxide accumulation and ROS overproduction has gradually widespread attention. Nevertheless, the key pathogenic factors and related molecular mechanisms remain unclear. Single-cell and bulk transcriptomics analyses were conducted to characterize oxidative stress of diverse lens cell types in cataract. Lens epithelial cells were exposed to H₂O₂ to establish an oxidative stress microenvironment, and a rat cataract model was constructed by intraperitoneal injection of sodium selenite. The impact and molecular mechanisms of TIMP3 knockdown and overexpression on oxidative stress, ferroptosis, and inflammation in lens epithelial cells were investigated. Oxidative stress widely occurred in early fiber cells, fiber cells, transitional fiber cells, anterior epithelial cells, and equatorial epithelial cells in cataract lens. TIMP3⁺ anterior epithelial cells were determined as a novel lens epithelial cell subpopulation associated with oxidative stress. The expression of TIMP3 in cataract lens was notably higher than that in normal lens. In vitro, TIMP3 overexpression attenuated lipid peroxidation of lens epithelial cells upon H₂O₂ by elevating SOD and GSH levels, and declining ROS accumulation and BODIPY oxidation ratio. IntracellularFe²⁺ levels, ferroptosis under the transmission electron microscope, and cytokine expression were also suppressed by TIMP3 overexpression. TIMP3 knockdown exerted the opposite effects. Mechanistically, TIMP3 overexpression inactivated Keap1 and subsequently enhanced the expression of Nrf2, HO-1, and GPX4 in lens epithelial cells on exposure to H₂O₂, thus protecting lens epithelial cells from oxidative damage and ferroptosis. In vivo, TIMP3 overexpression delayed cataract formation in rat cataract models. Our study reveals that TIMP3 suppresses oxidative damage and ferroptosis of lens epithelial cells and delays cataract formation through modulating the Keap1/Nrf2 pathway, providing a novel antioxidative treatment strategy for cataract.