Abstract
Purpose :
Pegylated IVT C3 and C5 therapy modestly decrease rate of atrophy growth but associate with risk of nAMD compared to sham controls in GA trials. This effect is not associated with non-pegylated complement therapeutics in clinical development. To investigate angiogenesis association with complement inhibition, we evaluated if C3 or FB KO increased CNV area compared to littermate controls in a mouse laser-induced CNV model.
Methods :
CNV induction was achieved by rupturing Bruch’s membrane with an Iridex Oculight® GLx (532nm, 3 lesions in each eye). Mice were injected iv with vascular label and euthanized 7 days post-laser. CNV lesions were captured by fluorescent microscopy and lesion area analyzed with Axiovision software with each lesion counting as an independent data point. Data acquisition, analysis and exclusion criteria were applied to masked data. Differences between groups were assessed by an unpaired two-tailed t-test.
KO and littermate wildtype (WT) control mice were rd8 negative, and generated by back crossing C3 KO or FB KO from Jackson Labs onto a C57BL/6 Taconic background. KO mice were compared to their sex-matched WT littermates generated from heterozygous breeding.
Results :
C3 KO was assessed in 5 studies of 3 female and 2 male cohorts (10-20 mice per cohort, 148 mice total). FB KO was assessed in 3 studies of two female and one male cohort (15-25 mice per cohort, 105 mice in total). 2 of 2 studies found reduction of CNV area by 50 or 51% in male C3 KO (p ≤ 0.001). 2/3 studies in female C3 KO mice showed a significant reduction in CNV (44.6% and 24.5%) and one found a significant increase in CNV (31%). As the C3 KO WT female had similar size CNV in each individual study, we combined raw data from the 3 experiments. In the combined analysis, CNV was not significantly smaller in C3 KO females (9% reduction). No difference in CNV area was observed between FB KO and littermate controls in all three studies (p = 0.38, 0.42, 0.80).
Conclusions :
This study does not support the hypothesis that complement inhibition is pro-angiogenic in ocular tissues, although this model is not necessarily predictive of macular degeneration. Previous reports describing a reduction in CNV in FB KO mice may be related to different environments and microbiome to our mice.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.