Targeted metabolomics reveals dysregulated tryptophan metabolism in retinitis pigmentosa

Retinitis pigmentosa (RP) is an inherited retinal degenerative disease characterized by progressive retinal pigment epithelium dysfunction and photoreceptor apoptosis, yet its pathogenesis remains unclear and no cure exists. Emerging evidence implicates the role of tryptophan metabolism in neuroinflammatory processes, prompting our investigation of serum tryptophan metabolites in RP patients versus healthy controls. Through targeted metabolomic profiling and clinical characterization, including age of onset, best corrected visual acuity (BCVA) and retinal thickness, we identified significant alterations in RP patients: marked decreases in cinnabarinic acid, xanthurenic acid, quinolinic acid and indole-3-carboxaldehyde (all p < 0.01), alongside elevated 5-Hydroxyindole-3-acetic acid (5-HIAA, p < 0.001). These disturbances correlated strongly with retinal thickness changes and were more pronounced in late-onset RP compared to early-onset. Our findings reveal tryptophan metabolic dysregulation as a potential feature of RP progression, providing both potential biomarkers and therapeutic targets for RP.