Zeaxanthin Mitigates Hydroxychloroquine-Induced Retinal Toxicity and Metabolic Reprogramming in ARPE-19 Cells

Long-term usage of the commonly used autoimmune disease drug hydroxychloroquine (HCQ) can result in retinal toxicity due to elevated lysosomal pH, mitochondrial damage, and oxidative stress. Zeaxanthin (ZEA), a carotenoid found mostly in the macula, is known for its antioxidant and cellular protective properties. The purpose of this study was to examine how ZEA would lessen the cytotoxicity, oxidative stress, mitochondrial dysfunction, and metabolic reprogramming driven by HCQ. ARPE-19 cells were treated with HCQ (1 mM), ZEA (1-10 μM), or their combinations for 72 h. Cell viability (MTT), apoptosis/necrosis (Annexin V-7AAD), reactive oxygen species (DCFDA), mitochondrial membrane potential (TMRM), and lysosomal acidification (Acridine Orange staining) were analyzed. Additionally, LC-QTOF/MS-based untargeted metabolomics analysis and pathway enrichment assessments were performed. HCQ treatment decreased cell viability to 23%, increased necrosis and ROS production, and led to mitochondrial hyperpolarization and lysosomal neutralization. Metabolomics analysis revealed a decrease in taurine, GABA, uric acid, and TCA intermediates, and an increase in palmitic acid and prostaglandin levels. Combination treatment with ZEA (10 μM) increased cell viability to 47%, reduced ROS and necrosis rates, and increased pantothenic acid, γ-glutamyl cysteine, and citrate levels, supporting glutathione synthesis and phase II detoxification pathways. ZEA demonstrated a significant protective effect on HCQ-induced oxidative, mitochondrial, and metabolic stress. These findings suggest that ZEA may be considered as a potential therapeutic agent against HCQ-induced retinotoxicity.