What factor does the retinal pigment epithelium secrete to counteract VEGF?

What factor does the retinal pigment epithelium secrete to counteract VEGF?

• A. VEGF
• B. PEDF
• C. IGF-1
• D. EPO

Answer: (B)

A key idea here is that the retina keeps angiogenesis in check by balancing pro-angiogenic signals with anti-angiogenic ones produced by the retinal pigment epithelium. The RPE releases pigment epithelium-derived factor, PEDF, which strongly counteracts VEGF by inhibiting its angiogenic signaling and reducing vascular permeability. This anti-angiogenic support helps maintain stable retinal vessels; when PEDF is low or VEGF rises, abnormal neovascularization can occur, as seen in diseases like neovascular AMD. PEDF also has neuroprotective roles, adding to its retinal benefits. The other factors listed have different roles: VEGF promotes new vessel growth, IGF-1 supports cell survival and can interact with VEGF pathways, and EPO is primarily neuroprotective with broader effects. So the factor secreted by the RPE to counteract VEGF is PEDF.