Abstract
Purpose :
Subretinal fibrosis is an adverse outcome of choroidal neovascularization (CNV) in age-related macular degeneration (AMD). Currently there is no treatment which directly targets macular fibrosis in wet AMD (nAMD) patients although some patient’s benefit from the anti-VEGF therapy, they still do develop scars. The molecular and cellular events that lead to CNV and associated scar formation remain largely unknown. Here we investigated the role of choroidal pericytes and the potential contribution of Hedgehog-Gli1 signaling axis to CNV and subretinal fibrosis and scar formation.
Methods :
Using a mouse model of laser induced CNV, as well as choroidal explants and ex vivo sprouting angiogenesis assays, we determined the role choroidal pericytes (Gli1+ cells) play in the pathogenesis of CNV and subretinal fibrosis. A reporter mouse, where pericytes were labeled, was used to assess their contribution to the development of CNV and subretinal fibrosis. Antibodies to specific cell markers labelling Gli1-expressing cells, fibrosis, and various cell types in the mouse choroid were also utilized. The Gli inhibitor, GANT61, was used to confirm the significance of Hedgehog- Gli signaling axis in CNV and associated subretinal fibrosis.
Results :
We found choroidal pericytes are the major cell type contributing to the formation of CNV and subretinal fibrosis. To examine the effect of Gli protein activities on the development of CNV, reporter mice subjected to laser induce CNV were injected subcutaneously with GANT61 every other day from the day of laser until day 13. On day 14, animals were sacrificed, and eyes were collected and stained for collagen I (fibrosis) and Gli1 (pericytes). We found the area covered by pericytes was equivalent to the CNV area and the area associated with subretinal fibrosis. Administration of GANT61 resulted in significant attenuation of both CNV and subretinal fibrosis. Gli inhibition also suppressed choroidal sprouting in the ex vivo cultures.
Conclusions :
Choroidal perivascular (Gli1+) cells are major contributors to the development of CNV and subretinal fibrosis. Inhibition of Gli proteins using GANT61 successfully suppressed the formation of CNV and subretinal fibrosis. Thus, targeting of the hedgehog- Gli signaling axis, either alone or in combination with anti-VEGF, may provide and alternative treatment strategy, which not only mitigates CNV but also prevents fibrosis and scar formation.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.