Ferroptosis-related hub genes and immune cell dynamics as diagnostic biomarkers in age-related macular degeneration

Age-related Macular Degeneration (AMD) is widely acknowledged as a principal cause of vision loss in the elderly. Currently, the therapeutic interventions available in clinical practice fail to achieve satisfactory outcomes. Therefore, it is imperative that we approach the progress of AMD from novel perspectives in order to explore new therapeutic strategies.

We obtained transcriptomic data from the macular and the peripheral retina from patients with AMD and a control group from the Gene Expression Omnibus (GEO) database. Through Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, we identified differentially expressed genes (DEGs) that were significantly enriched in functions associated with ferroptosis. Subsequent application of machine learning techniques enabled the identification of key hub genes, whose diagnostic potential was further validated. Additionally, the expression of these hub genes was corroborated in both animal and cellular models. Finally, we performed a functional enrichment analysis of these hub genes.

In the macula of patients with AMD, 452 DEGs were identified, while in the peripheral retina, 222 DEGs were discovered. Within the macula, 19 genes were associated with ferroptosis, compared to 3 in the peripheral retina. Consequently, the macular was selected as the primary focus of the study. Subsequent screening of these 19 genes using LASSO regression, Support Vector Machine (SVM), and Random Forest algorithms identified four hub genes: FADS1, TFAP2A, AKR1C3, and TTPA. Consequently, we utilized cigarette smoke extract (CSE) to either stimulate retinal pigment epithelial (RPE) cells in vitro or administer it via intravitreal injection, thereby establishing in vitro and in vivo models of AMD. Results from RT-PCR and Western blot analyses revealed an upregulation of FADS1, AKR1C3, and TTPA, while TFAP2A exhibited decreased expression. Finally, we investigated the infiltration of immune cells within the macular and performed a functional enrichment analysis of the hub genes.

We identified four key ferroptosis-related genes (FRGs)-FADS1, AKR1C3, TFAP2A, and TTPA-that possess diagnostic relevance for AMD and correlate with immune cell infiltration. Moreover, significant changes in both mRNA and protein expression levels of these genes have been observed in in vitro experiments and mice models.