H2O2 induces oxidative stress damage through the BMP-6/SMAD/hepcidin axis

Age-related macular degeneration (AMD) is one of the leading causes of blindness in elderly individuals worldwide. Oxidative stress injury to retinal pigment epithelial (RPE) cells plays a major role in the pathogenesis of AMD. The purpose of this study was to observe the correlation between Hepcidin and neovascular age-related macular degeneration (nAMD) and to further observe whether oxidative stress can inhibit Hepcidin expression through relevant signaling pathways to produce oxidative damage. We compared the concentrations of Hepcidin in the aqueous humor of nAMD patients and a control group and found that the concentration of Hepcidin was lower in nAMD patients. Through PCR and western blotting, we observed that H2O2 can significantly inhibit the expression of Bone morphogenetic protein-6 (BMP-6) and Hepcidin and increase the intracellular iron concentration in RPE cells, while BMP-6 can reverse the inhibition of Hepcidin and the increase in iron concentration caused by H2O2. In addition, alterations in smad1 and smad5 expression were examined, and pretreatment with BMP-6 was demonstrated to reduce H2O2-induced activation of smad1 and smad5. The effects of BMP-6 were attenuated by smad1 and smad5 siRNA, further verifying that oxidative stress inhibits the expression of Hepcidin by inhibiting activation of the BMP/SMAD signaling pathway. To some extent, this study verified that oxidative stress injury plays a role in nAMD by affecting the level of hepcidin, which lays a foundation for exploring new methods to treat nAMD.