Integrated Proteomic and Lipidomic Profiling of Aqueous Humor Reveals Inflammatory Signatures in Retinitis Pigmentosa

Background/Objectives: Retinitis pigmentosa (RP) is characterized by progressive degeneration of photoreceptors, with increasing evidence supporting the involvement of inflammation in disease progression. Aqueous humor (AH) reflects the intraocular microenvironment and represents an accessible source for biochemical analysis. This study aimed to characterize the profile of the main inflammatory proteins and bioactive lipids in the AH of RP patients and to compare it with healthy subjects. Methods: The AH was analyzed for cytokines using multiplex immunoassays and for lipid species using liquid chromatography-mass spectrometry. The concentrations of the analyzed molecules were compared between RP patients and the control group and then correlated with age and ellipsoid zone (EZ) width in RP patients. Results: A total of 26 RP patients and 13 controls were recruited. Significantly elevated levels of the pro-inflammatory IL-6 and a significant decrease in vascular endothelial growth factor (VEGF) were found in RP patients compared to controls. In RP patients, lipidomic analysis demonstrated significant increases in medium- and long-chain sphingomyelins (SMs) and very-long-chain unsaturated phosphatidylcholines (PCs). Higher levels of Cer 16:0, PC 32:0, and PC 34:0 were significantly associated with greater EZ preservation in RP patients. Additionally, in RP patients, VEGF and GM-CSF levels increased significantly with age, while IL-8 showed a non-significant decreasing trend. Conclusions: By integrating proteomic and, for the first time, lipidomic analyses of AH, we identified significant alterations in pro-inflammatory cytokines and bioactive lipid species in RP patients compared to controls, further highlighting a link between inflammatory activity, patient age, and disease stage. These preliminary findings need further validation in larger longitudinal cohorts to confirm the clinical utility of these bioactive mediators as potential disease biomarkers.