Abstract
Purpose :
Increasing evidence shows that angiogenesis, as well as lymphangiogenesis, play a key role in ocular physiology and pathology. Lymphangiogenesis and angiogenesis occur in concert, however, how blood and lymphatic vessels regulate each other has been unknown. VEGF-A in known to play an important role in angiogenesis as well as lymphangiogenesis. In this study, we evaluated VEGF-A induced corneal lymphangiogenesis and angiogenesis by dissecting the existing genetic heterogeneity using a systems genetic approach.
Methods :
Corneal angiogenesis & lymphangiogenesis was measured in 37 different inbred mouse strains from Hybrid Mouse Diversity Panel (HMDP) using a well-established corneal micropocket assay. A slow-release pellet containing 200ng of VEGF-A was implanted in the cornea. Neovascular area was assessed using a slit lamp. For measuring lymphangiogenesis, whole eyes were harvested, corneas were dissected, stained for Lyve1—lymphatic endothelial cell marker and imaged. The lymphatic vessel area was measured using AngioTool software. To identify candidate genes responsible for these two traits we employed efficient mixed-model association (EMMA) mapping. Comparison between the two traits was also performed. Candidate genes are now being evaluated using combinations of the following criteria: (1) location within the confidence intervals of loci; (2) genes have non-synonymous SNPs; (3) genes are expressed in the eye (4) genes have a biological association to ocular diseases.
Results :
We identified three genes within two novel peaks on chromosome 7 & 8 for angiogenesis. These novel candidates are known to be involved in transcription factor activity, regulation of ionic and water transport in cells. For lymphangiogenesis, we identified 18 candidates within five novel peaks located on chromosomes 1, 7, 11, 13 & 15. Top candidates were found to play critical roles ionic transport regulation, metabolic, lymphatic structure and transcription regulation. Comparison of the loci for both traits demonstrated that the genes were novel and were not shared, suggesting independent regulation. Additional studies are in progress to validate novel candidates for both the traits.
Conclusions :
We identified novel genomic regions that modulates corneal angiogenesis and lymphangiogenesis. Better understanding of these processes in the eye will provide a basis for the development of novel therapeutic strategies for incurable ocular diseases.
This is a 2020 ARVO Annual Meeting abstract.