Purpose: The purpose of this study was to evaluate the expression of high-temperature requirement A serine peptidase 1 (HTRA1), TGF-β1, bone morphogenetic protein 4 (BMP4), growth differentiation factor 6 (GDF6), and VEGFA proteins in the aqueous humor of patients with naïve choroidal neovascularization (nCNV) secondary to AMD.
Methods: We measured by ELISA the concentrations of HTRA1, TGF-β1, BMP4, GDF6, and VEGFA in the aqueous humor of 23 patients affected by nCNV who received three consecutive monthly intravitreal injections of 0.5 mg ranibizumab. Samples were collected at baseline (before the first injection), month 1 (before the second injection), and month 2 (before the third injection). Twenty-three age-matched cataract patients served as controls.
Results: Bone morphogenetic protein 4 and GDF6 were not detectable in any samples. Baseline HTRA1 was higher than controls (P < 0.0001) and higher than both the month 1 (P < 0.0001) and the month 2 (P < 0.0001) values. Baseline VEGFA was higher than controls (P < 0.0001), not different from month 1 value (P = 0.0821), but higher than month 2 value (P < 0.0001). Baseline TGF-β1 was higher than controls (P = 0.0015) and not different from month 1 (P = 0.129) and month 2 values (P = 0.5529). No correlation was found in naïve patients between concentrations of HTRA1 and TGF-β1, HTRA 1 and VEGFA, or TGF-β1 and VEGFA.
Conclusions: In nCNV patients, HTRA1 and TGF-β1 were significantly higher compared to controls. After treatment, TGF-β1 was persistently elevated, while HTRA1 returned to control levels, suggesting the involvement of TGF-β1 and HTRA1 in neovascular AMD and a VEGFA-independent role for TGF-β1.