Intraocular Distribution and Aqueous–Vitreous Correlation of TGF-β Isoforms and GDF-15 in Retinal Diseases

PURPOSE: To investigate the intraocular distribution and correlation of transforming growth factor-β isoforms and growth differentiation factor-15 in paired aqueous humor and undiluted vitreous samples from patients with various retinal diseases. METHODS: = 12). Paired aqueous humor and undiluted vitreous samples were collected during surgery. Concentrations of transforming growth factor-β1, transforming growth factor-β2, transforming growth factor-β3, and growth differentiation factor-15 were measured using multiplex immunoassay and enzyme-linked immunosorbent assay. Intraocular distributions were compared, and correlations between aqueous humor and vitreous cytokine concentrations were evaluated using Spearman's rank correlation. RESULTS: In patients with epiretinal membrane and other macular disorders, transforming growth factor-β1 and transforming growth factor-β2 concentrations were significantly higher in the aqueous humor than in the vitreous body, whereas growth differentiation factor-15 was more abundant in the vitreous. Conversely, in proliferative diabetic retinopathy patients, transforming growth factor-β1, transforming growth factor-β2, and growth differentiation factor-15 levels were significantly higher in the vitreous body. Across all disease groups, a strong positive correlation was observed between aqueous and vitreous growth differentiation factor-15 levels, while no significant correlations were found for any transforming growth factor-β isoforms. CONCLUSION: Transforming growth factor-β isoforms and growth differentiation factor-15 display distinct intraocular distribution patterns depending on retinal diseases. Notably, growth differentiation factor-15 showed a consistent aqueous-vitreous correlation across disease groups, suggesting that its concentration in the aqueous humor may partially reflect posterior segment conditions and may serve as an indicative marker.