Tectochrysin alleviates high-glucose-induced retinal pigment epithelial cell injury through Nrf2/HO-1 activation

Diabetic retinopathy involves retinal pigment epithelium (RPE) dysfunction. Tectochrysin is a natural flavonoid and antioxidant. However, its effects on retinal pigment epithelial cells remain unveiled. In this study, the investigation undertook the question of whether tectochrysin could protect human adult RPE cells ARPE-19 from high-glucose (HG) damage. Also the potential regulatory mechanism was explored.

Cell counting assay 8 (CCK8) was used to measure cell viability in ARPE-19 cells with tectochrysin treatment for 72 h to confirm the potential cytotoxicity. Furthermore, cells were treated by HG (40 mM glucose) for 48 h with or without tectochrysin treatment (5 or 10 μg/mL). Then cell viability, apoptosis and Reactive Oxygen Species (ROS) levels were evaluated using CCK8, flow cytometry and DCFH-DA fluorescence methods. Migration capacity was evaluated using wound healing and Transwel assays. In addition, malondialdehyde (MDA) content, glutathione (GSH), and Fe2+ levels were also examined with kits. Protein expression of ferroptosis markers (ACSL4, GPX4), EMT-related proteins (E-cadherin, vimentin, Snail), and Nrf2/HO-1 were determined using western blotting.

In ARPE-19 cells tectochrysin (5 or 10 μg/mL) significantly reversed HG-induced cytotoxicity, reducing apoptosis, ROS, MDA and Fe2+ levels, and increasing GSH. Tectochrysin reversed HG-induced ferroptosis-related protein ACSL4 and restored HG-inhibited GPX4 expression. In addition, tectochrysin inhibited HG-induced cell migration and vimentin and Snail levels and restored expression of HG-inhibited mesenchymal marker E-cadherin. Moreover, tectochrysin activated the Nrf2/HO-1 pathway.

The findings demonstrate that tectochrysin protects ARPE-19 cells from HG-induced injury by inhibiting apoptosis, ferroptosis and EMT while activating Nrf2/HO-1 signaling, suggesting its potential as a therapeutic agent for diabetic retinopathy.