Background.
Transforming growth factor-β (TGF-β) plays a major role in CNV. However, the mechanism is unclear. This study investigates the effect of
Pirfenidone (PFD) on TGF-β/Smad signaling pathway on the development of choroidal neovascular
fibrosis in
choroidal neovascularization (CNV) mouse model. C57BL/6J male mice (aged from 6 to 8 weeks) received
intravitreal injections of
phosphate-buffered saline (PBS)/PFD
solution on 14 days after
laser injury. Mice were anesthetized by
intraperitoneal injection of 4%
pentobarbital (0.05 mg/g
body weight). Optical Coherence Tomography (OCT), Fundus
Fluorescein angiography (FFA), and
hematoxylin-
eosin (HE) were used to assess CNV formation. The
fibrosis area was monitored by staining the
collagen type I (Col-I). Western blotting was used to analyze the expression of TGF-β2, Smad 2/3, phosphorylated Smad 2/3 (p-Smad 2/3), and α-smooth muscle actin (α-SMA). Terminal deoxynucleotidy1
transferase dUTP nick-end labelling (TUNEL) assay was performed on cryosections of mouse eyes to detect apoptosis. Our data showed PFD inhibited areas of
fibrosis during day 21 to day 28. We also found that the levels of TGF-β2
protein expressions increasingly reached the peak till the 3rd week during the CNV development. The
protein levels of Smad 2/3, p-Smad 2/3, and α-SMA also increased significantly in CNV mice, but this response was profoundly suppressed by the TGF-β inhibitor PFD. The results of this study suggest that TGF-β2 represents a target to prevent or treat choroidal neovascular
fibrosis, and PFD may provide an alternative to traditional methods for Wet
Age-related macular degeneration (wAMD) treatment.