Abstract
Purpose :
In previous study, we showed that selective pericyte depletion induced changes in vascular morphology in developing retinal neovessels that mimic vascular abnormalities in diabetic retinopathy including microaneurysms, retinal hemorrhage and edema [IOVS 2016; E-Abstract 4605 see also Lee et al. IOVS 2015; E-Abstract 2312]. In this study, we evaluated effects of systemic administration of anti(a)-IL6R antibody on inflammatory cell infiltration and vascular abnormalities in this pathological disease model.
Methods :
To establish the model: C57Bl/6 pups were given a subcutaneous (SC) injection of anti-PDGFRb (25mg/kg at Postnatal day (P)2 and at P5).
Study 1: At P7, mice were treated intraperitoneally (IP) at 25mg/kg human Fc (control protein) or a-IL6R antibody and sacrificed at P16;
Study 2: At P7, mice were treated intraperitoneal (IP) at 50mg/kg human Fc (control) or a-IL6R antibody and sacrificed at P16;
Pericyte coverage was assessed using a-NG2 (Millipore) immunofluorescence, vasculature integrity was assessed with Dylight Alexa 594 conjugated Tomato Lectin perfusion, leukocyte infiltration was assessed with CD45 antibody (BioRad) and vasculature was visualized using Biotinylated Lectin (Vector Labs).
Results :
In the pericyte depletion model at P16, there was a pronounced infiltration of inflammatory cells, indicating continued tissue remodeling, and blood vessel leakiness. At 25mg/kg, there were few notable differences between treatment with Fc and a-IL6R. However, systemic administration with a-IL6R at 50mg/kg produced partial normalization in blood vessel structure and limited the infiltration of leukocytes was observed at P16. With leukocyte counting, there was a significant reduction in the number of CD45+ cells in the group treated with a-IL6R (n=5, p < 0.005, -30%) compared to with human Fc treated pericyte depleted retinas.
Conclusions :
These studies demonstrate that selective pharmacological blockade with a-IL6R is effective in reduction of inflammatory cell infiltration in this pericyte depletion model with vascular abnormalities. This may provide insight in future treatment of diabetic retinopathy.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.