Integrative single-cell transcriptomic and experimental analyses unveil Qihuang granule's protection against retinal photodamage via PI3K/AKT/mTOR-mediated autophagy.

Light-induced retinal damage is a significant contributor to age-related macular degeneration (AMD). Qihuang granule (QHG), a traditional Chinese herbal formulation, has been clinically employed in the treatment of retinal diseases, including AMD; however, the precise protective mechanisms remain unclear. This study investigated the protective effects and underlying mechanisms of QHG using a rat model of blue light-induced retinal injury and a human retinal pigment epithelial (ARPE-19) cell model. The results demonstrated that QHG significantly alleviated retinal morphological abnormalities, ultrastructural damage, and apoptosis induced by light exposure. Single-cell RNA sequencing further revealed that specific cell clusters were notably enriched in the PI3K-AKT-mTOR and autophagy-related signaling pathways after QHG treatment, characterized by increased MAP1LC3B (LC3B) expression and decreased SQSTM1 (P62) expression. Validation at the protein and gene levels in vivo confirmed that QHG activated the autophagy pathway by downregulating PI3K, AKT, mTOR, and P62 expression while upregulating LC3B expression. Collectively, this study demonstrates that QHG protects against retinal photodamage by modulating autophagy via the PI3K/AKT/mTOR signaling pathway, providing theoretical support for its clinical application in the treatment of AMD.