Fig. 1

Role of the VEGF family and their receptors on corneal hem- and lymphangiogenesis. Expression patterns of Vascular Endothelial Growth Factor (VEGF) receptors and the binding specificity of their VEGF-ligands (VEGF-A, VEGF-B, VEGF-C, and VEGF-D) are integral to understanding their roles. VEGF-R1 is expressed on both blood vessel endothelium and immune cells such as macrophages and dendritic cells. VEGF-R2 is predominantly expressed on blood vessel endothelium, lymphatic endothelium, and dendritic cells. VEGFR-3 is primarily found on lymphatic endothelium and macrophages. The interactions between VEGF-A, VEGF-B, VEGF-C, and VEGF-D are indicated by dashed arrows. Macrophages play a dual role by not only secreting VEGFs to stimulate angiogenesis but also expressing VEGF-R1 and VEGF-R3. This dual expression facilitates myeloid cell chemotaxis, initiating an "immune-amplification cascade”