The role of mitochondrial genes on nuclear gene expression in neovascular age related macular degeneration: analysis of nuclear VEGF gene expression after ranibizumab treatment in cytoplasmic hybrid retinal pigment epithelial cell lines correlated with clinical evolution.

PURPOSE

The present study tests the hypothesis that mitochondrial genes have retrograde signaling capacity that influences the expression of nuclear genes related to angiogenesis pathways. Cytoplasmic hybrid (cybrid) in vitro cell lines with patient specific mitochondria inserted into an immortalized retinal pigment epithelial cell line (ARPE-19) were used to test this hypothesis. This type of analysis can provide important information to identify the optimal regimen of anti-VEGF treatment, personalizing age-related macular degeneration (AMD) therapies.

METHODS

Mitochondria deficient ARPE-19 cells (Rho0) were fused with AMD donor's platelets to create individual cybrid cell lines containing mitochondria from patients with phenotypic AMD disease and nuclear DNA from the immortalized RPE cell line. The cybrids were treated with Ranibizumab (Lucentis, Genentech, San Francisco, CA), at 4 different concentrations for 24 h, and subsequently the levels of reactive oxygen species (ROS), gene expression for VEGF-A, hypoxia-inducible factor 1-alpha (HIF1-a) and manganese superoxide dismutase (SOD2) were measured. The clinical evolution of the two AMD-donors were correlated with the molecular findings found in their 'personalized' cybrids.

RESULTS

Cybrids from Patient-01 showed down-regulation of gene expression of VEGF-A and HIF-1a at both 1X and 4X Ranibizumab concentrations. Patient-01 AMD cybrid cultures had an increase in the ROS levels at 1X (P = 0.0317), no changes at 2X (P = 0.8350) and a decrease at 4X (P = 0.0015) and 10X (P = 0.0011) of Ranibizumab. Clinically, Patient-01 responded to anti-VEGF therapy but eventually developed geographic atrophy. Patient-02 cybrids demonstrated up-regulation of gene expression of VEGF-A and HIF-1a at Ranibizumab 1X and 4X concentrations. There was decreased ROS levels with Ranibizumab 1X (P = 0.1606), 2X (P = 0.0388), 4X (P = 0.0010) and 10X (P =  < 0.0001). Clinically, Patient-02 presented with a neovascular lesion associated with a prominent production of intraretinal fluid in clinical follow-up requiring regular and repeated intravitreal injections of Ranibizumab with recurrent subretinal fluid.

CONCLUSIONS

Our cybrid model has the potential to help personalize the treatment regimen with anti-VEGF drugs in patients with neovascular AMD. Further investigation is needed to better understand the role that the mitochondria play in the cellular response to anti-VEGF drugs. Future studies that focus on this model have the potential to help personalize anti-VEGF treatment.