Lycium barbarum polysaccharide alleviates H₂O₂-induced premature senescence by downregulating miRNA-34a-5p in ARPE-19...

The premature senescence of retinal pigment epithelium (RPE) plays a significant role in the development of age-related macular degeneration. This study aimed to investigate the potential protective effect of Lycium barbarum polysaccharide (LBP) against H₂O₂-induced premature senescence and to elucidate the underlying mechanisms. The ARPE-19 cell line was subjected to H₂O₂ exposure to create a model of premature senescence. The modulation of microRNA-34a-5p expression was accomplished using antagomir and agomir, as assessed by quantitative real-time polymerase chain reaction. The senescence model was successfully established by treating cells with 200 μM H₂O₂ for 2 hours daily over a span of three consecutive days. This oxidative stress resulted in a notable increase in the proportion of senescence-associated beta-galactosidase-positive cells, reaching 33.5%, without significant alterations in cell viability or apoptosis. In the ARPE-19 cells undergoing premature senescence, there was a marked increase in reactive oxygen species (ROS) production and malondialdehyde levels, coupled with a significant decrease in the activity of total superoxide dismutase, glutathione peroxidase, and catalase. Additionally, microRNA-34a-5p was found to be overexpressed in these cells. Treatment with LBP alleviated H₂O₂-induced premature senescence, diminished the overexpression of microRNA-34a-5p, and suppressed ROS production. Moreover, the incubation with ago-34a reversed the protective effect of LBP in ARPE-19 cells. In conclusion, the overexpression of microRNA-34a-5p contributes to the H₂O₂-induced premature senescence of ARPE-19 cells. LBP appears to mitigate this premature senescence, at least in part, by downregulating microRNA-34a-5p expression and reducing oxidative stress.