Figure 4.

Blocking VEGF in the LD model inhibits RPE permeability and extravascular albumin leakage. The left panel shows the expression of beta-catenin stained on flat-mounted RPE and analyzed on control unexposed to light (a) or 24 h after LD in the following groups: no treatment prior to LD (b), Sham- (c), LV-GFP- (d) and LV-V65-treated animals (e and f). In unexposed control, the interface of cells is clearly delineated by beta-catenin staining (white arrowheads in a). In the control groups (no treatment prior to LD, sham- and LV-GFP-injected), beta-catenin staining shows a clear translocation of the adherens-junction component toward the cytoplasm of RPE cells and is absent at the cell contacts. Contrariwise, in the LV-V65-treated group, beta-catenin staining is maintained at the interface of cells (white arrowheads in e and f), although slightly more diffuse than in absence of exposure to light. Note that GFP expression of LV-GFP (g) and LV-V65 (h) vectors are observed at the RPE level (n=5 per group – magnification × 400 (confocal analysis) – red: beta-catenin and green: GFP). The right panel presents serum albumin staining of mice unexposed to light (i and j), untreated before LD (k and l), Sham- (m and n), LV-GFP- (o and p) and LV-V65 (q and r)-treated groups and analyzed 10 days after LD. Plasma leakage is observed in Sham- and LV-GFP-injected groups. Albumin positivity is evident in the choriocapillaris, RPE, ONL, OPL, INL, IPL and GCL. However, in the LV-V65-treated group, albumin staining is only limited to the outer segments of the photoreceptors, which appeared to be protected by the blockade of VEGF (n=8 per group – magnification × 400, scale bar: 100 μm – red: albumin and blue: Dapi, OS: outer segments, ONL: outer nuclear layer, INL: inner nuclear layer)