Grx2 maintains GSH/GSSG homeostasis to enhance GPX4-mediated ferroptosis defense in UVB irradiation induced cataract.

PURPOSE: Ultraviolet B (UVB) irradiation induces cataract pathogenesis, and Glutaredoxin 2 (Grx2) deficiency causes the early onset of UVB-induced cataracts. Several researchers have shown that, apart from apoptosis and pyroptosis, UVB irradiation also can induce cell ferroptosis. We explored the role of ferroptosis caused by UVB irradiation in human lens epithelial cells (HLECs) and clarified how Grx2 protects against UVB-induced cataracts.

METHODS

HLE-B3 cells and mice lenses were treated with DMSO or ferroptosis inhibitors after various doses of UVB irradiation. Cell morphology and ultrastructure were observed by optical microscope and transmission electron microscopy. Lens opacity was observed ex vivo using an optical microscope and in vivo using a slit lamp. The lipid peroxidation level was measured by C11-BODIPY probe and 4-HNE (the lipid peroxidation marker) protein expression. Cell viability was determined using the CCK-8 kit and propodium iodide (PI) immunofluorescence. Grx2 KO and KI mice, Grx2 silencing and Grx2 overexpression in HLE-B3 cell lines were used for in vivo and in vitro experiments respectively.

RESULTS

UVB-caused HLE-B3 cells death, lens opacity and lipid peroxidation could be mitigated by ferroptosis inhibitors. Grx2 KO mice accelerate the appearance of lens opacity induced by UVB. Meanwhile, Grx2 silencing enhanced HLECs lipid peroxidation susceptibility, downregulated the GSH level, shrunk mitochondria, and reduced the number of cristae. Grx2 overexpression had opposite effects.

CONCLUSIONS

Ferroptosis appears involved in UVB-induced HLECs damage. Inhibiting ferroptosis prevented UVB-induced cataracts. Grx2 strengthens resistance to ferroptosis induced by UVB irradiation through maintaining HLEC cellular GSH/GSSG homeostasis.