Targeted Ferroptosis Improves RPE Phagocytosis via MERTK/NFE2L2/HMOX1 Axis to Alleviate Retinitis Pigmentosa

Purpose: Retinitis pigmentosa (RP) is a heterogeneous inherited retinal disorder in which progressive rod and cone degeneration, together with retinal pigment epithelium (RPE) dysfunction, culminates in vision loss. Given the lack of effective therapies, we investigated RPE pathogenic alterations in RP models to inform potential therapeutic strategies. Methods: This study integrates Royal College of Surgeons (RCS) rat in vivo and human primary RPE cells in vitro to investigate the RP model. We employ single-cell RNA sequencing (scRNA-seq) to analyze the transcriptional differences in the retinas of RCS and RDY rats and to interrogate ferroptosis-related signal transduction. After treatment with the ferroptosis inhibitor Ferrostatin-1 (Fer-1) in both in vivo and in vitro RP models, therapeutic efficacy and RPE phagocytic function were assessed by using fundus photography, hematoxylin and eosin staining, electroretinography, Western blotting, immunofluorescence, and reverse transcription quantitative PCR. Results: Our scRNA-seq revealed marked transcriptional remodeling across retinal cell populations in RCS rats, with ferroptosis-related programs evident in most cell types and most pronounced in RPE. NFE2L2 and HMOX1 were significantly upregulated in RCS rats and in vitro MERTK-deficient RP models. Fer-1 ameliorated cytoskeletal disorganization and restored RPE phagocytic function, whereas selective silencing of NFE2L2 or HMOX1 reduced iron overload and rescued cytoskeletal integrity and phagocytosis, supporting a pathogenic role for ferroptosis in RP. Conclusions: Ferroptosis is a critical driver of MERTK-deficient RP, influencing RPE dysfunction through the MERTK/NFE2L2/HMOX1 axis. These insights highlight the potential therapeutic strategy of targeting ferroptosis to regulate RPE function in the treatment of MERTK-deficient RP.