Abstract
Purpose :
Diabetic retinopathy (DR) is characterized by retinal endothelial cell (REC) death and inadequate vascular repair by dysfunctional circulating angiogenic cells (CACs). We previously demonstrated ceramide-rich platform (CRP) formation as a pathogenic mechanism of DR. CAC dysfunction in DR is characterized by impaired migration to the site of injury. We hypothesized CRP formation on CACs in diabetes, to increase rigidity of CAC plasma membranes, reducing migration and preventing vascular repair. Using anti-ceramide Abs, we aimed to rescue CAC fluidity by dispersing CRPs, thus restoring vascular repair and preventing DR.
Methods :
CACs were lin- sca+. Anti-ceramide Abs administered at 10 (scFv) /100 (mAb) mg/mL and in vivo (subcu.) at 60mg/g BW. Streptozotocin utilized to induce hyperglycemia. CRPs quantified by IF. Membrane fluidity measured by fluorescence recovery after photobleaching. CAC migration assessed by trans-well assay. Vascular degeneration captured using FITC-albumin. Migration of CACs assessed in control mice; reendothelialization in 6-month diabetic mice. CACs introduced intravitreally and retinas examined by IF.
Results :
CACs in STZ mice had a significant increase (42% pos.) in CRPs on day 3, with increases on day 7, 14, 42, and 180 (70% pos.) post-hyperglycemia (n=9-12, p<0.0001). To establish a dosing regimen, mice received 1 dose of mAb 7 days post hyperglycemia. CRP pos. CACs were reduced after 1 day, returned to controls after 5 days, and increased after 10 days (n=12, p<0.05). Thus, STZ mice were treated every 5 days with anti-ceramide Ab for 6 wks, reducing CRP pos. CACs and protecting from retinal vascular permeability (n=10-12; p<0.01). TNFa was used to mimic diabetogenic conditions and examine CRPs in CAC. TNFa treated CACs had reduced migration (-60%) due to reduced fluidity (-85%), which was rescued by anti-ceramide Abs (scFv and mAb) (n=3; p<0.05). CAC migration and vascular repair in vivo was impaired in 6-month diabetic mice and rescued by anti-ceramide Abs (scFv and mAb) (n=4-7; p<0.08).
Conclusions :
Diabetes causes CRP formation in CACs, reducing fluidity, migration and repair. Systemic anti-ceramide Abs remove CRPs and return CACs to homeostasis and normalizes retinal vascular barrier in diabetic animals. This presents anti-ceramide Abs as a prospective treatment to restore microvascular repair via normalization of CACs to halt or reverse DR.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.