Anti TGF-β Peptides Reduce Progression Of Early Laser-induced Choroidal Neovascularization In Long Evans Rats

Abstract

Purpose: : To assess the effect of transforming growth factor beta (TGF-β) inhibitor peptides (p17 and p144) over early laser-induced choroidal neovascularization (Li-CNV) lesions.

Methods: : Forty-two Long Evans rats underwent a diode Li-CNV model. Sixteen days after laser application three groups received intravitreal injections of 7µL of p17 (G1;20 mg/ml), p144 (G2;3 mg/ml), or mixture of p17&p144 (G3;20 mg/ml & 3mg/ml), fellow eye received vehicle. Intravenous p17 (G5), p144 (G6) and vehicle (control; G4) was administered in five doses (0.2mg every 72 hours). CNV evolution was assessed weekly through fluorescein angiography (FA) for 4 weeks and leakage was measured in pixels. Gene expression for VEGF, TGFβ, MMP2, and IL6 was analyzed with Real-Time PCR. VEGF protein expression was determined by western-blot and MMP2 activity by gelatin zymogram. Results were statistically analyzed with SPSS 15.0 software.

Results: : A significant decrease in leakage was observed in G1 and G2 groups at 4^th week (p=0.045 and p=0.010, respectively). Leakage differences between pre-treatment and post-treatment FA revealed a significant reduction in G5 and G6 groups compared to control group at all timepoints (W1 p=0.004, W2 p=0.012, W3 p=0.004 and W4 p<0.001). The lowest leakage area was observed in G6. RT-PCR showed a significant decrease in VEGF gene in G3, G5 and G6 (p<0.001, p=0.026 and p=0.012, respectively) COX-2 gene showed significant differences in G5 and G6 (p=0.044 and p=0.032, respectively). VEGF western-blot showed a significant reduction in G2 and G6 (p=0.02 and p=0.009, respectively). MMP2 activity was significantly reduced in G1, G2 and G6 groups compared to controls (p=0.018, p=0.043 and p=0.009, respectively).

Conclusions: : TGF-β inhibitor peptides reduce progression of Li-CNV lesions. Further studies are needed to confirm these preliminary results.

Keywords: choroid: neovascularization